WO2021145261A1 - Light-receiving device and electronic system - Google Patents

Light-receiving device and electronic system Download PDF

Info

Publication number
WO2021145261A1
WO2021145261A1 PCT/JP2021/000288 JP2021000288W WO2021145261A1 WO 2021145261 A1 WO2021145261 A1 WO 2021145261A1 JP 2021000288 W JP2021000288 W JP 2021000288W WO 2021145261 A1 WO2021145261 A1 WO 2021145261A1
Authority
WO
WIPO (PCT)
Prior art keywords
optical system
light
filter
receiving device
light receiving
Prior art date
Application number
PCT/JP2021/000288
Other languages
French (fr)
Japanese (ja)
Inventor
一幸 若山
Original Assignee
ソニーセミコンダクタソリューションズ株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ソニーセミコンダクタソリューションズ株式会社 filed Critical ソニーセミコンダクタソリューションズ株式会社
Publication of WO2021145261A1 publication Critical patent/WO2021145261A1/en

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C3/00—Measuring distances in line of sight; Optical rangefinders
    • G01C3/02—Details
    • G01C3/06—Use of electric means to obtain final indication
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/88—Lidar systems specially adapted for specific applications
    • G01S17/93—Lidar systems specially adapted for specific applications for anti-collision purposes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/22—Telecentric objectives or lens systems

Definitions

  • This disclosure relates to a light receiving device and an electronic system.
  • ToF Time of Flight
  • the ToF distance measurement technology is expected to be used in a wide range of fields such as automatic driving and face recognition.
  • the ToF type distance measurement light receiving device receives light that has passed through a lens (hereinafter, ToF lens), but it is necessary to make the F value of the ToF lens as small as possible so that even weak light can be received.
  • ToF lens a lens
  • a ToF type light receiving device may be installed in a mobile device such as a smartphone for the purpose of face recognition or the like.
  • a mobile device such as a smartphone for the purpose of face recognition or the like.
  • smartphones and the like it is necessary to make the light receiving device as small as possible, and it is required to make the ToF lens thinner.
  • the CRA Choef Ray Angle
  • the CRA is the angle of incidence of the main light beam on the filter, and the angle of incidence in this case is the angle of inclination of the incident surface of the filter from the normal direction.
  • the filter transmits light in a frequency band different from the frequency band that should originally transmit. Therefore, light having a wavelength component different from the originally intended wavelength component is incident on the image sensor. As a result, the S / N ratio of the image sensor is lowered, and the distance measurement accuracy is lowered.
  • the CRA To improve the spectral characteristics of the filter, it is necessary to reduce the CRA.
  • the light emitted from the ToF lens should be substantially parallel to the optical axis direction, but if the traveling direction of the light beam is changed inside the ToF lens, the lens length will increase. It will be long. In smartphones and the like, it is difficult to use a ToF lens with a long lens length because the installation space is limited.
  • the present disclosure provides a light receiving device and an electronic system capable of improving the spectral characteristics of the filter without increasing the lens length.
  • a telecentric optical system having a Fresnel surface and a telecentric optical system, A filter that transmits light in a predetermined wavelength band from the light that has passed through the telecentric optical system,
  • a light receiving device including an imaging unit that photoelectrically converts light that has passed through the filter.
  • the telecentric optical system is The front group optical system that diverges the main ray of the incident peripheral luminous flux, It has a rear group optical system that parallelizes the peripheral luminous flux that has passed through the front group optical system.
  • the rear group optical system may have the Fresnel surface.
  • the rear group optical system has a first surface which is arranged to face the front group optical system and a second surface which is arranged to face the filter.
  • the second surface may be a Fresnel surface.
  • the degree of curvature of the first surface may be larger than the degree of curvature of the second surface.
  • the rear group optical system may have a lens whose thickness decreases from the center of the optical axis toward the periphery.
  • the rear group optical system has a transparent base material having a uniform thickness and has a uniform thickness.
  • the transparent base material has a third surface arranged on the front group optical system side and a fourth surface arranged on the imaging unit side.
  • the third surface is a Fresnel surface,
  • the filter may be a layer coated on the fourth surface.
  • the telecentric optical system is incident with the reflected light emitted from the light source and reflected by the object.
  • the filter has Wcut_on as the upper limit wavelength at which the transmittance becomes 50% when light is incident from a direction inclined by a predetermined angle from the normal direction of the filter, and when light is incident from the normal direction of the filter.
  • Wcut_off the lower limit wavelength at which the transmittance becomes 50%
  • Wld the amount of change in the emission wavelength of the light source due to the initial wavelength variation of the light source and the temperature change
  • the telecentric optical system may have a glass base material having a rectangular outer shape and a Fresnel surface.
  • the telecentric optical system may have a resin base material having a rectangular outer shape and a Fresnel surface.
  • the telecentric optical system has a convex resin base material and a flat glass base material bonded to the resin base material.
  • the filter may be a layer coated on the surface of the glass substrate.
  • the telecentric optical system is incident with the reflected light emitted from the light source and reflected by the object.
  • the light receiving device may have a distance measuring unit that measures the distance to the object by the time difference between the timing when the light source emits light and the timing when the light receiving device receives the reflected light.
  • a light source that emits light and A light receiving device that receives the reflected light that is emitted by the light source and reflected by the object.
  • An electronic system including a support substrate that supports the light source and the light receiving device.
  • the light receiving device is Telecentric optics with Fresnel surface and A filter that transmits light in a predetermined wavelength band from the light that has passed through the telecentric optical system.
  • An electronic system is provided that includes an imaging unit that photoelectrically converts light that has passed through the filter.
  • the light receiving device may have a distance measuring unit that measures the distance to the object by the time difference between the timing when the light source emits light and the timing when the light receiving device receives the reflected light.
  • the telecentric optical system is The front group optical system that diverges the main ray of the incident peripheral luminous flux, It has a rear group optical system that parallelizes the main light beam of the peripheral luminous flux that has passed through the front group optical system.
  • the rear group optical system may have the Fresnel surface.
  • the rear group optical system has a first surface which is arranged to face the front group optical system and a second surface which is arranged to face the filter.
  • the second surface may be a Fresnel surface.
  • the degree of curvature of the first surface may be larger than the degree of curvature of the second surface.
  • the rear group optical system may have a lens whose thickness decreases from the center of the optical axis toward the periphery.
  • the rear group optical system has a transparent base material having a uniform thickness and has a uniform thickness.
  • the transparent base material has a third surface arranged on the front group optical system side and a fourth surface arranged on the imaging unit side.
  • the third surface is a Fresnel surface,
  • the filter may be a layer coated on the fourth surface.
  • the telecentric optical system is incident with the reflected light emitted from the light source and reflected by the object.
  • the filter has Wcut_on as the upper limit wavelength at which the transmittance becomes 50% when light is incident from a direction inclined by a predetermined angle from the normal direction of the filter, and when light is incident from the normal direction of the filter.
  • Wcut_off the lower limit wavelength at which the transmittance becomes 50%
  • Wld the amount of change in the emission wavelength of the light source due to the initial wavelength variation of the light source and the temperature change
  • the telecentric optical system may have a glass base material having a rectangular outer shape and a Fresnel surface.
  • the figure which shows the optical composition of a light receiving device. The figure explaining the Fresnel surface.
  • the cross-sectional view which shows an example of the rear group optical system of a hybrid structure.
  • the figure which shows the correspondence relationship of the wavelength of the light incident on the filter, the incident angle and the spectral transmittance when the excess bandwidth BW is 55 nm.
  • the figure which shows the correspondence relationship of the wavelength of the light incident on the filter, the incident angle and the spectral transmittance when the excess bandwidth BW is 45 nm.
  • the figure which shows the correspondence relationship of the wavelength of the light incident on the filter, the incident angle and the spectral transmittance when the excess bandwidth BW is 35 nm.
  • the figure which shows the correspondence relationship of the wavelength of the light incident on the filter, the incident angle and the spectral transmittance when the excess bandwidth BW is 25 nm.
  • SNR S / N ratio
  • FIG. 6 is a diagram showing a curved surface shape before forming a Fresnel surface on the glass base material of FIG. 16 and a detailed shape of the Fresnel surface 14.
  • It is a block diagram which shows an example of the schematic structure of a vehicle control system. It is explanatory drawing which shows an example of the installation position of the vehicle exterior information detection unit and the image pickup unit. It is a figure which shows the example of the installation position of the imaging unit.
  • FIG. 1 is a diagram showing a module configuration of an electronic system 2 including a light receiving device 1 according to the first embodiment.
  • the electronic system 2 of FIG. 1 includes a light receiving device 1, a light source 3, and a support substrate 4.
  • the light receiving device 1 and the light source 3 are arranged apart from each other on one main surface of the support substrate 4.
  • the electronic system 2 of FIG. 1 irradiates an object (not shown) with the light emitted from the light source 3, and the light receiving device 1 receives the reflected light from the object.
  • the light receiving device 1 measures the distance from the electronic system 2 to the object by the time difference between the time when the light is emitted from the light source 3 and the time when the reflected light from the object is received.
  • the electronic system 2 of FIG. 1 functions as a ToF system.
  • the light source 3 has, for example, a light emitting element such as a vertical cavity surface emitting laser (VCSEL), a diffuser that uniformly diffuses the light emitted by the light emitting element, and a driver that supplies driving power to the light emitting element.
  • the light source 3 emits light in the wavelength band of infrared light, for example.
  • the wavelength band of the light emitted by the light source 3 is arbitrary.
  • FIG. 2 is a diagram showing an optical configuration of the light receiving device 1.
  • the light receiving device 1 includes a telecentric optical system 11, a bandpass filter (hereinafter, simply referred to as a filter) 12, and an imaging unit 13.
  • the telecentric optical system 11, the filter 12, and the imaging unit 13 are arranged in order along the optical axis 20.
  • the filter 12 has a transmission characteristic that transmits light in the same wavelength band as the light emitted by the light source 3 and blocks light in other wavelength bands.
  • the filter 12 is an IRBPF that transmits an infrared light wavelength band.
  • the telecentric optical system 11 has a feature that light substantially parallel to the optical axis 20 can be emitted without increasing the lens length.
  • the lens length of the telecentric optical system 11 is L1.
  • the telecentric optical system 11 according to the present embodiment has a Fresnel surface 14 as described later.
  • the Fresnel surface 14 replaces the curved surface of the lens with a plurality of concentric grooves. By providing the Fresnel surface 14, the thickness of the lens can be reduced.
  • FIG. 3 is a diagram illustrating the Fresnel surface 14.
  • the broken line in FIG. 3 shows the curved surface of a general convex lens.
  • the Fresnel surface 14 is a stepped curved surface formed by dividing the curved surface of the convex lens into a plurality of concentric circles and moving the curved surface of each divided region in the direction of the central surface 14a of the convex lens.
  • a plurality of grooves are formed on the Fresnel surface 14, and the bottom surface of each groove has a curvature similar to the curved surface of the convex lens.
  • the left side of the Fresnel surface 14 in FIG. 3 is the light incident side, and the right side is the filter 12 side.
  • the thin dashed arrow line in FIG. 3 indicates the traveling direction of the light incident on the telecentric optical system 11.
  • the light incident substantially parallel to the Fresnel surface 14 is focused on the focal position in the same manner as a normal convex lens.
  • the light obliquely incident on the Fresnel surface 14 is refracted in a direction close to the optical axis 20 direction and emitted.
  • the telecentric optical system 11 has an optical configuration in which a lens group composed of a plurality of lenses is arranged in the optical axis 20 direction, and a Fresnel surface 14 is provided as a part of the lens group.
  • FIG. 4 is a diagram showing a detailed optical configuration of the telecentric optical system 11 according to the present embodiment.
  • the traveling direction of the light incident on the telecentric optical system 11 from diagonally below the optical axis 20 is shown by a fine solid line.
  • the telecentric optical system 11 has a front group optical system 21 and a rear group optical system 22.
  • the front group optical system 21 has a refractive power that focuses the incident light and diverges each main ray.
  • the rear group optical system 22 collimates the main light beam that has passed through the front group optical system 21. Collimating is the parallelization of light.
  • the rear group optical system 22 has the Fresnel surface 14 described above.
  • the light emitted from the rear group optical system 22 is incident on the filter 12.
  • the light transmitted through the filter 12 is incident on the imaging unit 13.
  • the right end of FIGS. 2 and 4 represents the imaging surface of the imaging unit 13.
  • the front group optical system 21 has a configuration in which a plurality of lenses are arranged along the optical axis 20.
  • the front group optical system 21 is composed of a lens group composed of three lenses, but the number and shape of the lenses constituting the front group optical system 21 are arbitrary.
  • the rear group optical system 22 has a first surface which is arranged to face the front group optical system 21 and a second surface which is arranged to face the filter 12, and the second surface is a Fresnel surface 14.
  • the rear group optical system 22 may be composed of a lens group composed of a plurality of lenses.
  • the surface of the rear group optical system 22 facing the filter 12 is the Fresnel surface 14, but the surface of the rear group optical system 22 other than the surface facing the filter 12 is the Fresnel surface. It may be the surface 14.
  • the Fresnel surface is provided on the side closer to the filter 12, the direction of the light incident on the filter 12 can be made closer to the direction of the optical axis 20.
  • the rear group optical system 22 of FIG. 4 has a lens 23 whose thickness gradually decreases from the center of the optical axis toward the periphery.
  • the surface (second surface) of the lens 23 facing the filter 12 is a Fresnel surface 14.
  • the Fresnel surface 14 can reduce the thickness of the lens 23, that is, the degree of curvature.
  • the Fresnel surface 14 side of the rear group optical system 22 is a flat surface as an overall shape.
  • the front group optical system 21 side of the rear group optical system 22 is largely curved, and the optical axis center side protrudes toward the front group optical system 21 side rather than the peripheral edge side.
  • the rear group optical system 22 is thicker toward the center of the optical axis and thinner toward the peripheral edge.
  • the CRA at the peripheral edge of the rear group optical system 22 can be reduced. Further, by making the surface (second surface) of the rear group optical system 22 facing the filter 12 a Fresnel surface 14, the traveling direction of the light emitted from the rear group optical system 22 is made substantially parallel to the optical axis 20. be able to.
  • FIG. 5 is a diagram for explaining the shape of the Fresnel surface 14 of the rear group optical system 22 in more detail.
  • the curved surface on the left side of FIG. 5 shows the lens curved surface of the convex lens before forming the Fresnel surface 14.
  • a stepped Fresnel surface 14 as shown on the right side of FIG. 5 is formed. Will be done. Comparing the thicknesses of the lenses before and after forming the Fresnel surface 14, the thickness can be significantly reduced. For example, in the example of FIG.
  • FIG. 6 is a diagram showing the optical characteristics of the telecentric optical system 11 according to the present embodiment, and more specifically, the correspondence between the image height (mm) and the light incident angle (degrees) of the telecentric optical system 11 according to the present embodiment.
  • FIG. 6 illustrates the characteristic w1 of the main ray, the characteristic w2 of the ray below the main ray, and the characteristic w3 of the ray above the main ray.
  • the ray incident angle (CRA) of the main ray is almost 0 degrees regardless of the image height, and it can be seen that the CRA is sufficiently small.
  • a sufficiently small CRA means that light is incident on the filter 12 from a direction close to the normal direction of the incident surface of the filter 12. This eliminates the risk of deterioration of the spectral characteristics of the filter 12.
  • FIG. 7A is a perspective view showing an example of the rear group optical system 22, and FIG. 7B is a cross-sectional view of the rear group optical system 22.
  • the outer shape of the rear group optical system 22 shown in FIG. 7A is rectangular according to the outer shapes of the filter 12 and the imaging unit 13.
  • the surface of the rear group optical system 22 facing the front group optical system 21 has a convex shape as shown in the figure.
  • the surface of the rear group optical system 22 facing the filter 12 side is a flat surface, but in reality, a minute-sized Fresnel surface 14 is formed on this flat surface.
  • the outer shape of the rear group optical system 22 does not necessarily have to be rectangular, but it is desirable to have a shape that matches the outer shape of the filter 12 and the imaging unit 13.
  • the rear group optical system 22 is formed using, for example, a glass base material. By etching the glass substrate, the Fresnel surface 14 can be formed relatively easily. The Fresnel surface 14 is formed on the bottom surface side of FIGS. 7A and 7B.
  • FIG. 7C is a cross-sectional view showing an example of the rear group optical system 22 having a hybrid structure.
  • a resin base material 221 having a thickness as large as the center of the optical axis is bonded to the Fresnel surface.
  • a coating layer that functions as a filter 12 may be provided on the surface of the glass substrate 220 opposite to the bonding surface with the resin substrate 221.
  • FIG. 8A is a diagram showing an optical configuration of the optical system 25 according to the first comparative example.
  • FIG. 8B is a diagram showing the optical characteristics of the optical system 25 of FIG. 8A, and shows the correspondence between the image height of the optical system 25 of FIG. 8A and the light ray incident angle. Since the optical system 25 of FIG. 8A is not the telecentric optical system 11, the lens length can be shortened, but the CRA is larger than that of FIG. In the CRA of FIG. 8B, since light is incident on the filter 12 from a direction inclined from the normal direction of the filter 12, the spectral characteristics of the filter 12 are deteriorated.
  • FIG. 9A is a diagram showing an optical configuration of the optical system 26 according to the second comparative example.
  • 9B is a diagram showing the optical characteristics of the optical system 26 of FIG. 9A, and shows the correspondence between the image height of the optical system 26 of FIG. 9A and the light ray incident angle.
  • the optical system 26 of FIG. 9A realizes a telecentric optical system by increasing the thickness of the lens on the rear side of the optical axis, and as shown in FIG. 9B, the CRA can also be reduced.
  • the lens length of the optical system 26 of FIG. 9A is longer than that of FIGS. 3 and 8A, it is difficult to mount it on a portable device such as a smartphone.
  • the wavelength of the light emitted from the light source 3 fluctuates due to manufacturing variations and temperature changes.
  • the wavelength of the light received by the light receiving device 1 also fluctuates, which adversely affects the spectral characteristics of the filter 12.
  • FIG. 10A is a diagram showing a change in the characteristics of the light source 3
  • FIG. 10B is a diagram showing the temperature dependence of the light source 3. It should be noted that FIGS. 10A and 10B show changes in the characteristics of the specific light source 3, and different results can be obtained if the type of the light source 3 is different.
  • the horizontal axis of FIG. 10B is the wavelength [nm], and the vertical axis is the light intensity [a.u.].
  • the upper two stages of FIG. 10A show wavelength fluctuations due to manufacturing variations of the light source 3.
  • the third to sixth stages from the top of FIG. 10A show the fluctuation of the wavelength depending on the temperature of the light source 3.
  • the emission wavelength of the light source 3 increases and the light intensity decreases.
  • the wavelength of the light emitted from the light source 3 fluctuates due to manufacturing variations, temperature, and the like, and the wavelength band of the reflected light from the object received by the light receiving device 1 also fluctuates accordingly.
  • the spectral transmittance of the filter 12 changes depending on the wavelength of the light incident on the filter 12.
  • the spectral transmittance of the filter 12 also changes depending on the incident angle of the light incident on the filter 12.
  • FIG. 11 is a diagram showing the correspondence between the wavelength of light incident on the filter 12, the angle of incidence, and the spectral transmittance.
  • the curve w4 in FIG. 11 shows the correspondence between the wavelength at 0 degree incident and the spectral transmittance
  • the curve w5 shows the correspondence between the wavelength at 30 degree incident and the spectral transmittance.
  • the incident angle is an inclination angle of the filter 12 with respect to the normal direction
  • 0 degree means that light is incident from the normal direction.
  • the wavelength at which the spectral transmittance is 50% with respect to the 30-degree incident light beam is called the cut-on wavelength Wcut_on
  • the lower limit wavelength at which the spectral transmittance is 50% with respect to the 0-degree incident light beam is called the cut-off wavelength. We call it Wcut_off.
  • the wavelength width of the difference between the cut-on wavelength Wcut_on and the cut-off wavelength Wcut_off (hereinafter referred to as the wavelength fluctuation bandwidth) can be transmitted by the filter 12 even if the incident angle of light changes within the range of 0 to 30 degrees.
  • the bandwidth of light that can be produced (wavelength fluctuation bandwidth).
  • the wavelength fluctuation bandwidth is separated from the transmission bandwidth BW of the 0-degree incident ray, the wavelength at which the spectral transmittance is 50% with respect to the 0-degree incident ray, and the spectrum with respect to the 30-degree incident ray. It is equal to the value obtained by subtracting the difference bandwidth Ws from the wavelength at which the transmittance becomes 50%. That is, the relationship of the following equation (1) holds.
  • BW-Ws Wcut_on-Wcut_off ... (1)
  • the wavelength fluctuation bandwidth which is the difference between the cut-on wavelength Wcut_on and the cut-off wavelength Wcut_off, differs depending on the type of the filter 12.
  • 12A, 12B, 12C, and 12D are diagrams showing the correspondence between the wavelength, the angle of incidence, and the spectral transmittance of the light incident on the filter 12 having a transmission bandwidth BW of 55 nm, 45 nm, 35 nm, and 25 nm, respectively. be.
  • the above-mentioned differential bandwidth Ws also differs depending on the transmission bandwidth BW.
  • the amount of fluctuation due to the temperature change of the emission wavelength of the light emitting element is 21.1 nm from FIG. 10A. If the difference (wavelength fluctuation bandwidth) between the cut-on wavelength Wcut_on and the cut-off wavelength Wcut_off in the above equation (1) is not 21.1 nm or more, the spectral characteristics of the filter 12 may deteriorate.
  • FIG. 13 is a diagram summarizing the characteristics of the filter 12 of FIGS. 12A to 12D.
  • the wavelength fluctuation bandwidth is too narrow, the reflected light may not be transmitted when the wavelength of the light emitted from the light source 3 fluctuates due to manufacturing variation or temperature change.
  • FIG. 14 is a diagram showing the correspondence between the transmission bandwidth of the filter 12 and the depth value, and the correspondence between the transmission bandwidth of the filter 12 and the S / N ratio (SNR).
  • the depth value is the distance error to the object measured by the light receiving device 1, and the larger the depth value, the larger the distance error. Further, it is shown that the larger the S / N ratio is, the less susceptible to noise.
  • Graph w6 of FIG. 14 shows the correspondence between the transmission bandwidth of the filter 12 and the depth value.
  • the difference between the cut-on wavelength Wcut_on and the cut-off wavelength Wcut_off (wavelength fluctuation bandwidth) is larger than the fluctuation amount of 21.1 nm due to the temperature change of the emission wavelength of the light emitting element in the transmission bandwidth BW.
  • the minimum value, transmission bandwidth BW 35 nm, is selected.
  • the transmission characteristics of the filter 12 are set so as to satisfy the inequality of the following equation (2).
  • Wld in the formula (2) is the amount of fluctuation of the emission wavelength due to the initial wavelength variation of the light source 3 and the temperature change.
  • Wcut_off-Wcut_on is the upper limit wavelength at which the transmittance becomes 50% when light is incident from the normal direction of the filter 12, and the direction inclined by a predetermined angle (for example, 30 degrees) from the normal direction of the filter 12. It is a difference wavelength from the upper limit wavelength at which the transmittance becomes 50% when light is incident from the above.
  • the filter 12 can transmit all the light rays emitted from the telecentric optical system 11 with a transmittance of 50% or more. Thereby, the spectral characteristics of the filter 12 can be improved.
  • FIG. 15 is a diagram comparing the characteristics of the optical system 25 according to the first comparative example and the telecentric optical system 11 according to the present embodiment.
  • the left side of the upper part of FIG. 15 shows the optical characteristics of the optical system 25 according to the first comparative example, and the right side of the upper part shows the optical characteristics of the optical system 11 according to the present embodiment.
  • the left side of the lower part of FIG. 15 shows the transmission characteristics of the filter 12 according to the first comparative example
  • the right side of the lower part shows the transmission characteristics of the filter 12 according to the present embodiment. From the upper part of FIG. 15, it can be seen that this embodiment can make the CRA smaller than that of the first comparative example. Further, from the lower part of FIG. 15, in the present embodiment, even if the transmission bandwidth of the filter 12 is narrower than that of the first comparative example, the wavelength fluctuation range of the reflected light can be contained within the transmission bandwidth.
  • the telecentric optical system 11 having the Fresnel surface 14 is provided in the light receiving device 1, the direction of the light emitted from the telecentric optical system 11 can be made substantially parallel to the optical axis. can. As a result, the CRA when the light transmitted through the telecentric optical system 11 is incident on the filter 12 can be reduced, and the spectral characteristics of the filter 12 can be improved.
  • FIG. 16 is a diagram showing an optical configuration of the light receiving device 1a according to the second embodiment.
  • the light receiving device 1a of FIG. 16 includes a telecentric optical system 11a having an optical configuration different from that of FIG. 2, a filter 12, and an imaging unit 13.
  • the telecentric optical system 11a of FIG. 16 has a front group optical system 21a and a rear group optical system 22a.
  • the front group optical system 21a has, for example, four lenses arranged in order in the optical axis direction. The number and shape of the lenses can be changed to those other than those shown in FIG.
  • the filter 12 is integrally formed in the rear group optical system 22a.
  • the rear group optical system 22a has a glass substrate having a substantially uniform thickness.
  • the surface of the glass substrate facing the front group optical system 21a is the Fresnel surface 14.
  • a coating layer 23a is provided on the surface of the glass substrate on the image pickup unit 13 side.
  • the coating layer 23a is a layer that functions as a filter 12, and transmits light in a predetermined wavelength band and does not transmit light in other wavelength bands.
  • the rear group optical system 22a of FIG. 16 is different from the rear group optical system 22a of FIG. 2 in that it has a glass substrate having a uniform thickness. Further, the rear group optical system 22a of FIG. 16 is different from the rear group optical system 22a of FIG. 2 in that the surface of the rear group optical system 22a facing the front group optical system 21a is a Fresnel surface 14.
  • the lens length L4 of the telecentric optical system 11a of FIG. 16 can be made approximately the same as the lens length L1 of the telecentric optical system 11a of FIG. Specifically, the lens length can be controlled by adjusting the internal lens configurations of the front group optical system 21a and the rear group optical system 22a. This lens length L4 is shorter than the lens length L3 of the second comparative example shown in FIG. 9A.
  • FIG. 17 is a diagram showing a curved surface shape before forming the Fresnel surface 14 on the glass substrate of FIG. 16 and a detailed shape of the Fresnel surface 14. Similar to FIG. 5, the Fresnel surface 14 formed on the glass base material of FIG. 16 is provided with a plurality of divided regions concentrically from the center of the optical axis of the glass base material, and the curved surface of each divided region is formed on the glass base material. It is formed by moving it toward the central surface.
  • FIG. 18 is a diagram showing the correspondence between the image height (mm) of the telecentric optical system 11a and the light ray incident angle (degrees) according to the second embodiment.
  • the telecentric optical system 11a according to the second embodiment has a coating that can reduce the CRA and functions as a filter 12, similarly to the telecentric optical system 11a according to the first embodiment. Since light substantially parallel to the optical axis can be incident on the layer 23a, the spectral characteristics of the filter 12 can be improved.
  • a resin member may be provided instead of the glass base material described above. Even if it is a resin member, the surface on the front group optical system 21a side can be made into a Fresnel surface 14, and the surface on the imaging unit 13 side can be provided with a coating layer 23a to function as a filter 12.
  • a glass base material or a resin base material having a substantially uniform thickness is provided inside the telecentric optical system 11a, and the surface of the base material on the front group optical system 21a side is a Fresnel surface. Since the coating layer 23a is provided on the surface of the imaging unit 13 to function as the filter 12, the CRA can be reduced with a simple structure, and the spectral characteristics of the filter 12 can be improved as in the first embodiment.
  • FIG. 19 is a diagram showing an optical configuration of the light receiving device 1b according to the third embodiment.
  • the light receiving device 1b of FIG. 19 includes a telecentric optical system 11b having no Fresnel surface 14.
  • the telecentric optical system 11b of FIG. 19 includes a front group optical system 21b and a rear group optical system 22b.
  • the optical configuration of the front group optical system 21b is almost the same as that in FIGS. 2 and 16.
  • the resin base material 22d is bonded to the surface of the flat glass base material 22c on the front group optical system 21b side, and the coating layer 23a is provided on the surface of the glass base material 22c on the image pickup portion 13 side. There is.
  • the resin base material 22d is thicker toward the center of the optical axis and thinner toward the periphery. By thinning the peripheral side of the resin base material 22d in this way, the CRA can be made small, and the light transmitted through the resin base material 22d can be made substantially parallel to the optical axis even without the Fresnel surface 14.
  • FIG. 20 is a diagram showing the correspondence between the image height (mm) of the telecentric optical system 11b and the light ray incident angle (degree 9) according to the third embodiment. As shown in the figure, the CRA is reduced regardless of the image height. can do.
  • the resin base material 22d bonded to the glass base material 22c is provided in the rear group optical system 22b inside the telecentric optical system 11b, and the thickness of the resin base material 22d is set as the optical axis. Since the thickness is gradually reduced from the center side to the peripheral edge, the CRA can be reduced without providing the Fresnel surface 14. Further, since the coating layer 23a is formed on the surface of the glass base material 22c on the image pickup unit 13 side to function as the filter 12, the spectral characteristics of the filter 12 can be improved even though the optical configuration is simple.
  • the electronic system 2 provided with the light receiving device 1 according to the first to third embodiments described above irradiates the object with the light emitted by the light source 3, receives the reflected light, and the light source 3 emits the light.
  • the distance to the object can be measured based on the time difference between the time and the time when the light receiving device 1 receives the reflected light.
  • FIG. 21 is a detailed block diagram of an electronic system 2 including a light source 3 and a light receiving device 1.
  • the light source 3 may have one light emitting element 31 or may have a plurality of light emitting elements 31.
  • the light emitting element 31 emits light by the electric power from the driver 32.
  • the driver 32 controls the timing of supplying electric power to the light emitting element 31 by the signal from the light receiving device 1.
  • the light receiving device 1 includes, for example, a light receiving unit 33, a TDC 34, a calculation unit 35, a trigger generation unit 36, a control unit 37, and an interface unit 38.
  • the light receiving unit 33 has a SPAD array 39 and a read circuit 40.
  • the SPAD array 39 is a plurality of SPADs (Single Photon Avalanche Diodes) arranged in a one-dimensional or two-dimensional direction. A photoelectric conversion element other than SPAD may be provided.
  • SPADs Single Photon Avalanche Diodes
  • a photoelectric conversion element other than SPAD may be provided.
  • the read circuit 40 reads an electric signal output from any SPAD in the SPAD array 39.
  • the TDC 34 measures the time difference between the timing of the electric signal read by the reading circuit 40 and the timing of the trigger generation unit 36 transmitting the trigger signal to the driver 32.
  • the calculation unit 35 performs various signal processing based on the output signal of the TDC 34.
  • the signal processing performed by the calculation unit 35 includes, for example, a process of measuring the distance to the object based on the time difference between the time when the light emitting element 31 emits light and the time when the light receiving unit 33 receives the reflected light. I'm out.
  • the light receiving unit 33 may receive not only reflected light from an object but also noise light such as sunlight. Since the timing at which the noise light is received is different from the timing at which the original reflected light is received, the light source 3 repeatedly emits light, and the light receiving device 1 repeatedly receives the reflected light and repeats the distance measurement accordingly. , The distance may be measured in a state where the influence of noise light is removed by averaging a plurality of distance measurement results. Therefore, the calculation unit 35 may be provided with a histogram generation unit 35a. The histogram generation unit 35a averages the distance measurement results of a plurality of times, and measures the distance from the plurality of distance measurement results by a majority vote.
  • the control unit 37 controls each unit in the light receiving device 1.
  • the distance measurement result calculated by the calculation unit 35 is sent to the outside via the control unit 37 and the interface unit 38.
  • the trigger generation unit 36 determines the timing at which the light source 3 emits light, and outputs a trigger signal. This trigger signal is received by the driver 32.
  • the driver 32 drives the light source 3 in synchronization with the reception timing of the trigger signal.
  • control system of the light receiving device 1 shown in FIG. 21 can be chipped together with the optical system or chipped separately from the optical system and mounted on the support substrate 4 of FIG.
  • the technology related to this disclosure can be applied to various products.
  • the technology according to the present disclosure is realized as a device mounted on a moving body of any kind such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, a personal mobility, an airplane, a drone, a ship, and a robot. You may.
  • FIG. 22 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile control system to which the technique according to the present disclosure can be applied.
  • the vehicle control system 12000 includes a plurality of electronic control units connected via the communication network 12001.
  • the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside information detection unit 12030, an in-vehicle information detection unit 12040, and an integrated control unit 12050.
  • a microcomputer 12051, an audio image output unit 12052, and an in-vehicle network I / F (interface) 12053 are shown as a functional configuration of the integrated control unit 12050.
  • the drive system control unit 12010 controls the operation of the device related to the drive system of the vehicle according to various programs.
  • the drive system control unit 12010 provides a driving force generator for generating the driving force of the vehicle such as an internal combustion engine or a driving motor, a driving force transmission mechanism for transmitting the driving force to the wheels, and a steering angle of the vehicle. It functions as a control device such as a steering mechanism for adjusting and a braking device for generating a braking force of a vehicle.
  • the body system control unit 12020 controls the operation of various devices mounted on the vehicle body according to various programs.
  • the body system control unit 12020 functions as a keyless entry system, a smart key system, a power window device, or a control device for various lamps such as headlamps, back lamps, brake lamps, blinkers or fog lamps.
  • the body system control unit 12020 may be input with radio waves transmitted from a portable device that substitutes for the key or signals of various switches.
  • the body system control unit 12020 receives inputs of these radio waves or signals and controls a vehicle door lock device, a power window device, a lamp, and the like.
  • the vehicle outside information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000.
  • the image pickup unit 12031 is connected to the vehicle exterior information detection unit 12030.
  • the vehicle outside information detection unit 12030 causes the image pickup unit 12031 to capture an image of the outside of the vehicle and receives the captured image.
  • the vehicle exterior information detection unit 12030 may perform object detection processing or distance detection processing such as a person, a vehicle, an obstacle, a sign, or a character on the road surface based on the received image.
  • the imaging unit 12031 is an optical sensor that receives light and outputs an electric signal according to the amount of the light received.
  • the image pickup unit 12031 can output an electric signal as an image or can output it as distance measurement information. Further, the light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.
  • the in-vehicle information detection unit 12040 detects the in-vehicle information.
  • a driver state detection unit 12041 that detects the driver's state is connected to the in-vehicle information detection unit 12040.
  • the driver state detection unit 12041 includes, for example, a camera that images the driver, and the in-vehicle information detection unit 12040 determines the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041. It may be calculated, or it may be determined whether or not the driver has fallen asleep.
  • the microcomputer 12051 calculates the control target value of the driving force generator, the steering mechanism, or the braking device based on the information inside and outside the vehicle acquired by the vehicle exterior information detection unit 12030 or the vehicle interior information detection unit 12040, and the drive system control unit.
  • a control command can be output to 12010.
  • the microcomputer 12051 realizes ADAS (Advanced Driver Assistance System) functions including vehicle collision avoidance or impact mitigation, follow-up driving based on inter-vehicle distance, vehicle speed maintenance driving, vehicle collision warning, vehicle lane deviation warning, and the like. It is possible to perform cooperative control for the purpose of.
  • ADAS Advanced Driver Assistance System
  • the microcomputer 12051 controls the driving force generator, the steering mechanism, the braking device, and the like based on the information around the vehicle acquired by the vehicle exterior information detection unit 12030 or the vehicle interior information detection unit 12040. It is possible to perform coordinated control for the purpose of automatic driving, etc., which runs autonomously without depending on the operation.
  • the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle acquired by the vehicle exterior information detection unit 12030.
  • the microcomputer 12051 controls the headlamps according to the position of the preceding vehicle or the oncoming vehicle detected by the external information detection unit 12030, and performs coordinated control for the purpose of anti-glare such as switching the high beam to the low beam. It can be carried out.
  • the audio image output unit 12052 transmits an output signal of at least one of audio and an image to an output device capable of visually or audibly notifying information to the passenger or the outside of the vehicle.
  • an audio speaker 12061, a display unit 12062, and an instrument panel 12063 are exemplified as output devices.
  • the display unit 12062 may include, for example, at least one of an onboard display and a heads-up display.
  • FIG. 23 is a diagram showing an example of the installation position of the imaging unit 12031.
  • the vehicle 12100 has image pickup units 12101, 12102, 12103, 12104, 12105 as the image pickup unit 12031.
  • the imaging units 12101, 12102, 12103, 12104, 12105 are provided at positions such as the front nose, side mirrors, rear bumpers, back doors, and the upper part of the windshield in the vehicle interior of the vehicle 12100, for example.
  • the imaging unit 12101 provided on the front nose and the imaging unit 12105 provided on the upper part of the windshield in the vehicle interior mainly acquire an image in front of the vehicle 12100.
  • the imaging units 12102 and 12103 provided in the side mirrors mainly acquire images of the side of the vehicle 12100.
  • the imaging unit 12104 provided on the rear bumper or the back door mainly acquires an image of the rear of the vehicle 12100.
  • the images in front acquired by the imaging units 12101 and 12105 are mainly used for detecting a preceding vehicle or a pedestrian, an obstacle, a traffic light, a traffic sign, a lane, or the like.
  • FIG. 23 shows an example of the photographing range of the imaging units 12101 to 12104.
  • the imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose
  • the imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively
  • the imaging range 12114 indicates the imaging range of the imaging units 12102 and 12103.
  • the imaging range of the imaging unit 12104 provided on the rear bumper or the back door is shown. For example, by superimposing the image data captured by the imaging units 12101 to 12104, a bird's-eye view image of the vehicle 12100 as viewed from above can be obtained.
  • At least one of the imaging units 12101 to 12104 may have a function of acquiring distance information.
  • at least one of the image pickup units 12101 to 12104 may be a stereo camera composed of a plurality of image pickup elements, or may be an image pickup element having pixels for phase difference detection.
  • the microcomputer 12051 uses the distance information obtained from the imaging units 12101 to 12104 to obtain the distance to each three-dimensional object within the imaging range 12111 to 12114 and the temporal change of this distance (relative velocity with respect to the vehicle 12100). By obtaining, it is possible to extract as the preceding vehicle a three-dimensional object that is the closest three-dimensional object on the traveling path of the vehicle 12100 and that travels in substantially the same direction as the vehicle 12100 at a predetermined speed (for example, 0 km / h or more). can.
  • a predetermined speed for example, 0 km / h or more.
  • the microcomputer 12051 can set an inter-vehicle distance to be secured in front of the preceding vehicle in advance, and can perform automatic braking control (including follow-up stop control), automatic acceleration control (including follow-up start control), and the like. In this way, it is possible to perform coordinated control for the purpose of automatic driving or the like in which the vehicle travels autonomously without depending on the operation of the driver.
  • the microcomputer 12051 converts three-dimensional object data related to a three-dimensional object into two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on the distance information obtained from the imaging units 12101 to 12104. It can be classified and extracted and used for automatic avoidance of obstacles. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into obstacles that can be seen by the driver of the vehicle 12100 and obstacles that are difficult to see. Then, the microcomputer 12051 determines the collision risk indicating the risk of collision with each obstacle, and when the collision risk is equal to or higher than the set value and there is a possibility of collision, the microcomputer 12051 is used via the audio speaker 12061 or the display unit 12062. By outputting an alarm to the driver and performing forced deceleration and avoidance steering via the drive system control unit 12010, driving support for collision avoidance can be provided.
  • At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared rays.
  • the microcomputer 12051 can recognize a pedestrian by determining whether or not a pedestrian is present in the captured image of the imaging units 12101 to 12104.
  • pedestrian recognition includes, for example, a procedure for extracting feature points in an image captured by an imaging unit 12101 to 12104 as an infrared camera, and pattern matching processing for a series of feature points indicating the outline of an object to determine whether or not the pedestrian is a pedestrian. It is done by the procedure to determine.
  • the audio image output unit 12052 When the microcomputer 12051 determines that a pedestrian is present in the captured images of the imaging units 12101 to 12104 and recognizes the pedestrian, the audio image output unit 12052 outputs a square contour line for emphasizing the recognized pedestrian.
  • the display unit 12062 is controlled so as to superimpose and display. Further, the audio image output unit 12052 may control the display unit 12062 so as to display an icon or the like indicating a pedestrian at a desired position.
  • the above is an example of a vehicle control system to which the technology according to the present disclosure can be applied.
  • the technique according to the present disclosure can be applied to, for example, the imaging unit 12031 among the configurations described above.
  • the above-mentioned light receiving circuit, light receiving device, or distance measuring device can be mounted on the imaging unit 12031.
  • the present technology can have the following configurations.
  • the telecentric optical system is The front group optical system that diverges the main ray of the incident peripheral luminous flux, It has a rear group optical system that parallelizes the main light beam of the peripheral luminous flux that has passed through the front group optical system.
  • the rear group optical system has a first surface which is arranged to face the front group optical system and a second surface which is arranged to face the filter.
  • the light receiving device according to (2), wherein the second surface is a Fresnel surface.
  • the light receiving device according to (3), wherein the degree of curvature of the first surface is larger than the degree of curvature of the second surface.
  • the rear group optical system has a transparent base material having a uniform thickness.
  • the transparent base material has a third surface arranged on the front group optical system side and a fourth surface arranged on the imaging unit side.
  • the third surface is a Fresnel surface
  • the telecentric optical system is incident with the reflected light emitted from the light source and reflected by the object.
  • the filter has Wcut_on as the upper limit wavelength at which the transmittance becomes 50% when light is incident from a direction inclined by a predetermined angle from the normal direction of the filter, and when light is incident from the normal direction of the filter.
  • the transmittance has a transmission characteristic satisfying Wcut_on-Wcut_off> Wld.
  • the light receiving device according to any one of (1) to (6).
  • the telecentric optical system has a glass base material having a rectangular outer shape and a Fresnel surface.
  • the telecentric optical system has a resin base material having a rectangular outer shape and a Fresnel surface.
  • the telecentric optical system has a convex resin base material and a flat glass base material bonded to the resin base material.
  • the telecentric optical system is incident with the reflected light emitted from the light source and reflected by the object.
  • the light receiving device has a distance measuring unit that measures the distance to the object by the time difference between the timing when the light source emits light and the timing when the light receiving device receives the reflected light (1) to.
  • the light receiving device according to any one of (10).
  • (12) A light source that emits light and A light receiving device that receives the reflected light that is emitted by the light source and reflected by the object.
  • An electronic system including a support substrate that supports the light source and the light receiving device.
  • the light receiving device is Telecentric optics with Fresnel surface and A filter that transmits light in a predetermined wavelength band from the light that has passed through the telecentric optical system,
  • An electronic system comprising an imaging unit that photoelectrically converts light that has passed through the filter.
  • the light receiving device has a distance measuring unit that measures the distance to the object by the time difference between the timing when the light source emits light and the timing when the light receiving device receives the reflected light. 12) The electronic system according to.
  • the telecentric optical system is The front group optical system that diverges the main ray of the incident peripheral luminous flux, It has a rear group optical system that parallelizes the main light beam of the peripheral luminous flux that has passed through the front group optical system.
  • the rear group optical system has a first surface which is arranged to face the front group optical system and a second surface which is arranged to face the filter.
  • the electronic system according to (14), wherein the second surface is a Fresnel surface.
  • the electronic system according to (15), wherein the degree of curvature of the first surface is larger than the degree of curvature of the second surface.
  • the rear group optical system has a transparent base material having a uniform thickness.
  • the transparent base material has a third surface arranged on the front group optical system side and a fourth surface arranged on the imaging unit side.
  • the third surface is a Fresnel surface,
  • the electronic system according to (14), wherein the filter is a layer coated on the fourth surface.
  • the telecentric optical system is incident with the reflected light emitted from the light source and reflected by the object.
  • the filter has Wcut_on as the upper limit wavelength at which the transmittance becomes 50% when light is incident from a direction inclined by a predetermined angle from the normal direction of the filter, and when light is incident from the normal direction of the filter.
  • the transmittance has a transmission characteristic satisfying Wcut_on-Wcut_off> Wld.
  • 1 light receiving device 2 electronic system, 3 light source, 4 support substrate, 11, 11a, 11b telecentric optical system, 12 bandpass filter, 13 imaging unit, 14 Frenel surface, 20 optical axis, 21, 21a, 21b front group optical system , 22, 22a, 22b rear group optical system, 23 lens, 23a coating layer, 25 optical system, 26 optical system, 220 glass base material, 221 resin base material, 31 light emitting element, 32 driver, 33 light receiving part, 34 TDC, 35 arithmetic unit, 36 trigger generation unit, 37 control unit, 38 interface unit, 39 SPAD array, 40 read circuit,

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Lenses (AREA)
  • Length Measuring Devices By Optical Means (AREA)
  • Measurement Of Optical Distance (AREA)
  • Optical Radar Systems And Details Thereof (AREA)

Abstract

[Problem] To make it possible to improve the spectral characteristics of a filter without increasing lens length. [Solution] A light-receiving device equipped with a telecentric optical system which has a Fresnel surface, a filter for allowing light in a prescribed wavelength band of the light passing through the telecentric optical system to pass therethrough, and an imaging unit for subjecting the light which has passed through the filter to a photoelectric conversion.

Description

受光装置及び電子システムReceiver and electronic system
　本開示は、受光装置及び電子システムに関する。 This disclosure relates to a light receiving device and an electronic system.
　対象物に対して光を照射した時刻と、対象物からの反射光を受光した時刻との時間差に基づいて、対象物までの距離を計測するＴｏＦ（Time of Flight）方式の距離計測技術が知られている。ＴｏＦ方式の距離計測技術は、自動運転や顔認証など、広範な分野での利用が見込まれている。 ToF (Time of Flight) distance measurement technology that measures the distance to an object based on the time difference between the time when the object is irradiated with light and the time when the reflected light from the object is received is known. Has been done. The ToF distance measurement technology is expected to be used in a wide range of fields such as automatic driving and face recognition.
　ＴｏＦ方式の距離計測用の受光装置では、レンズ（以下、ＴｏＦ用レンズ）を通した光を受光するが、微弱な光でも受光できるようにＴｏＦ用レンズのＦ値はできるだけ小さくする必要がある。 The ToF type distance measurement light receiving device receives light that has passed through a lens (hereinafter, ToF lens), but it is necessary to make the F value of the ToF lens as small as possible so that even weak light can be received.
　最近は、顔認証などの目的でスマートフォン等の携帯機器にもＴｏＦ方式の受光装置が搭載される場合がある。スマートフォン等では、受光装置をできるだけ小型化する必要があり、ＴｏＦ用レンズを薄くすることが求められている。 Recently, a ToF type light receiving device may be installed in a mobile device such as a smartphone for the purpose of face recognition or the like. In smartphones and the like, it is necessary to make the light receiving device as small as possible, and it is required to make the ToF lens thinner.
米国特許公開公報ＵＳ２０１３０２５００３９Ａ１US Patent Publication US201130250039A1
　しかしながら、ＴｏＦ用レンズを薄くすると、光軸中心から離れるほど屈折角度が大きくなる。ＴｏＦ用レンズを通過した光は、バンドパスフィルタ（以下、単にフィルタと呼ぶ）に入射されて、所定の波長帯域の光成分のみが抽出されて、撮像センサに入射される。ＴｏＦ用レンズを薄くすると、フィルタに入射される光のＣＲＡ（Chief Ray Angle）が大きくなる。ここで、ＣＲＡとは、フィルタへの主光線の入射角度であり、この場合の入射角度はフィルタの入射面の法線方向からの傾斜角度である。 However, if the ToF lens is made thinner, the refraction angle becomes larger as the distance from the center of the optical axis increases. The light that has passed through the ToF lens is incident on a bandpass filter (hereinafter, simply referred to as a filter), and only the light component in a predetermined wavelength band is extracted and incident on the image sensor. When the ToF lens is made thinner, the CRA (Chief Ray Angle) of the light incident on the filter becomes larger. Here, the CRA is the angle of incidence of the main light beam on the filter, and the angle of incidence in this case is the angle of inclination of the incident surface of the filter from the normal direction.
　ＣＲＡが大きくなると、フィルタへの入射角度も大きくなり、フィルタの分光特性が悪化してしまう。より具体的には、ＣＲＡが大きくなると、フィルタは本来透過するべき周波数帯域とは異なる周波数帯域の光を透過する。このため、撮像センサには、本来意図した波長成分とは異なる波長成分の光が入射される。これにより、撮像センサのＳ／Ｎ比が低下し、距離計測精度が低下してしまう。 As the CRA increases, the angle of incidence on the filter also increases, and the spectral characteristics of the filter deteriorate. More specifically, as the CRA increases, the filter transmits light in a frequency band different from the frequency band that should originally transmit. Therefore, light having a wavelength component different from the originally intended wavelength component is incident on the image sensor. As a result, the S / N ratio of the image sensor is lowered, and the distance measurement accuracy is lowered.
　フィルタの分光特性をよくするには、ＣＲＡを小さくする必要がある。ＣＲＡを小さくするには、ＴｏＦ用レンズから出射される光が光軸方向に略平行になるようにすればよいが、ＴｏＦ用レンズの内部で光線の進行方向を変更しようとすると、レンズ長が長くなってしまう。スマートフォン等では、設置スペースが限られているため、レンズ長の長いＴｏＦレンズを採用するのは困難である。 To improve the spectral characteristics of the filter, it is necessary to reduce the CRA. In order to reduce the CRA, the light emitted from the ToF lens should be substantially parallel to the optical axis direction, but if the traveling direction of the light beam is changed inside the ToF lens, the lens length will increase. It will be long. In smartphones and the like, it is difficult to use a ToF lens with a long lens length because the installation space is limited.
　そこで、本開示では、レンズ長を長くすることなく、フィルタの分光特性を改善可能な受光装置及び電子システムを提供するものである。 Therefore, the present disclosure provides a light receiving device and an electronic system capable of improving the spectral characteristics of the filter without increasing the lens length.
　上記の課題を解決するために、本開示によれば、フレネル面を有するテレセントリック光学系と、
　前記テレセントリック光学系を通過した光の中から、所定の波長帯域の光を透過させるフィルタと、
　前記フィルタを通過した光を光電変換する撮像部と、を備える、受光装置が提供される。 In order to solve the above problems, according to the present disclosure, a telecentric optical system having a Fresnel surface and a telecentric optical system,
A filter that transmits light in a predetermined wavelength band from the light that has passed through the telecentric optical system,
Provided is a light receiving device including an imaging unit that photoelectrically converts light that has passed through the filter.
　前記テレセントリック光学系は、
　入射する周辺光束の主光線を発散させる前群光学系と、
　前記前群光学系を通過した周辺光束を平行化する後群光学系と、を有し、
　前記後群光学系は、前記フレネル面を有してもよい。 The telecentric optical system is
The front group optical system that diverges the main ray of the incident peripheral luminous flux,
It has a rear group optical system that parallelizes the peripheral luminous flux that has passed through the front group optical system.
The rear group optical system may have the Fresnel surface.
　前記後群光学系は、前記前群光学系に対向配置される第１面と、前記フィルタに対向配置される第２面と、を有し、
　前記第２面はフレネル面であってもよい。 The rear group optical system has a first surface which is arranged to face the front group optical system and a second surface which is arranged to face the filter.
The second surface may be a Fresnel surface.
　前記第１面の湾曲度合いは、前記第２面の湾曲度合いよりも大きくてもよい。 The degree of curvature of the first surface may be larger than the degree of curvature of the second surface.
　前記後群光学系は、光軸中心から周縁に向かうに従って、厚みが薄くなるレンズを有してもよい。 The rear group optical system may have a lens whose thickness decreases from the center of the optical axis toward the periphery.
　前記後群光学系は、厚みが均一な透明基材を有し、
　前記透明基材は、前記前群光学系側に配置される第３面と、前記撮像部側に配置される第４面と、を有し、
　前記第３面はフレネル面であり、
　前記フィルタは、前記第４面にコーティングされた層であってもよい。 The rear group optical system has a transparent base material having a uniform thickness and has a uniform thickness.
The transparent base material has a third surface arranged on the front group optical system side and a fourth surface arranged on the imaging unit side.
The third surface is a Fresnel surface,
The filter may be a layer coated on the fourth surface.
　前記テレセントリック光学系には、光源から発光されて対象物で反射された反射光が入射され、
　前記フィルタは、前記フィルタの法線方向から所定角度傾斜した方向から光が入射された場合に透過率が５０％になる上限の波長をＷcut_on、前記フィルタの法線方向から光が入射された場合に透過率が５０％になる下限の波長をＷcut_off、前記光源の初期波長ばらつき及び温度変化による前記光源の発光波長の変化量をＷldとしたとき、Ｗcut_on－Ｗcut_off＞Ｗldを満たす透過特性を有してもよい。 The telecentric optical system is incident with the reflected light emitted from the light source and reflected by the object.
The filter has Wcut_on as the upper limit wavelength at which the transmittance becomes 50% when light is incident from a direction inclined by a predetermined angle from the normal direction of the filter, and when light is incident from the normal direction of the filter. When the lower limit wavelength at which the transmittance becomes 50% is Wcut_off and the amount of change in the emission wavelength of the light source due to the initial wavelength variation of the light source and the temperature change is Wld, it has a transmission characteristic satisfying Wcut_on-Wcut_off> Wld. You may.
　前記テレセントリック光学系は、外形が矩形状でフレネル面を有するガラス基材を有してもよい。 The telecentric optical system may have a glass base material having a rectangular outer shape and a Fresnel surface.
　前記テレセントリック光学系は、外形が矩形状でフレネル面を有する樹脂基材を有してもよい。 The telecentric optical system may have a resin base material having a rectangular outer shape and a Fresnel surface.
　前記テレセントリック光学系は、凸形状の前記樹脂基材と、前記樹脂基材に接合される平坦なガラス基材とを有し、
　前記フィルタは、前記ガラス基材の表面にコーティングされた層であってもよい。 The telecentric optical system has a convex resin base material and a flat glass base material bonded to the resin base material.
The filter may be a layer coated on the surface of the glass substrate.
　前記テレセントリック光学系には、光源から発光されて対象物で反射された反射光が入射され、
　前記受光装置は、前記光源が光を発光したタイミングと、前記受光装置が前記反射光を受光したタイミングとの時間差により、前記対象物までの距離を計測する距離計測部を有してもよい。 The telecentric optical system is incident with the reflected light emitted from the light source and reflected by the object.
The light receiving device may have a distance measuring unit that measures the distance to the object by the time difference between the timing when the light source emits light and the timing when the light receiving device receives the reflected light.
　本開示によれば、光を発光する光源と、
　前記光源で発光されて対象物で反射された反射光を受光する受光装置と、
　前記光源と前記受光装置とを支持する支持基板と、を備えた電子システムであって、
　前記受光装置は、
　フレネル面を有するテレセントリック光学系と、
　前記テレセントリック光学系を通過した光の中から、所定の波長帯域の光を透過させるフィルタと、
　前記フィルタを通過した光を光電変換する撮像部と、を有する、電子システムが提供される。 According to the present disclosure, a light source that emits light and
A light receiving device that receives the reflected light that is emitted by the light source and reflected by the object.
An electronic system including a support substrate that supports the light source and the light receiving device.
The light receiving device is
Telecentric optics with Fresnel surface and
A filter that transmits light in a predetermined wavelength band from the light that has passed through the telecentric optical system,
An electronic system is provided that includes an imaging unit that photoelectrically converts light that has passed through the filter.
　前記受光装置は、前記光源が光を発光したタイミングと、前記受光装置が前記反射光を受光したタイミングとの時間差により、前記対象物までの距離を計測する距離計測部を有してもよい。 The light receiving device may have a distance measuring unit that measures the distance to the object by the time difference between the timing when the light source emits light and the timing when the light receiving device receives the reflected light.
　前記テレセントリック光学系は、
　入射する周辺光束の主光線を発散させる前群光学系と、
　前記前群光学系を通過した周辺光束の主光線を平行化する後群光学系と、を有し、
　前記後群光学系は、前記フレネル面を有してもよい。 The telecentric optical system is
The front group optical system that diverges the main ray of the incident peripheral luminous flux,
It has a rear group optical system that parallelizes the main light beam of the peripheral luminous flux that has passed through the front group optical system.
The rear group optical system may have the Fresnel surface.
　前記後群光学系は、前記前群光学系に対向配置される第１面と、前記フィルタに対向配置される第２面と、を有し、
　前記第２面はフレネル面であってもよい。 The rear group optical system has a first surface which is arranged to face the front group optical system and a second surface which is arranged to face the filter.
The second surface may be a Fresnel surface.
　前記第１面の湾曲度合いは、前記第２面の湾曲度合いよりも大きくてもよい。 The degree of curvature of the first surface may be larger than the degree of curvature of the second surface.
　前記後群光学系は、光軸中心から周縁に向かうに従って、厚みが薄くなるレンズを有してもよい。 The rear group optical system may have a lens whose thickness decreases from the center of the optical axis toward the periphery.
　前記後群光学系は、厚みが均一な透明基材を有し、
　前記透明基材は、前記前群光学系側に配置される第３面と、前記撮像部側に配置される第４面と、を有し、
　前記第３面はフレネル面であり、
　前記フィルタは、前記第４面にコーティングされた層であってもよい。 The rear group optical system has a transparent base material having a uniform thickness and has a uniform thickness.
The transparent base material has a third surface arranged on the front group optical system side and a fourth surface arranged on the imaging unit side.
The third surface is a Fresnel surface,
The filter may be a layer coated on the fourth surface.
　前記テレセントリック光学系には、光源から発光されて対象物で反射された反射光が入射され、
　前記フィルタは、前記フィルタの法線方向から所定角度傾斜した方向から光が入射された場合に透過率が５０％になる上限の波長をＷcut_on、前記フィルタの法線方向から光が入射された場合に透過率が５０％になる下限の波長をＷcut_off、前記光源の初期波長ばらつき及び温度変化による前記光源の発光波長の変化量をＷldとしたとき、Ｗcut_on－Ｗcut_off＞Ｗldを満たす透過特性を有してもよい。 The telecentric optical system is incident with the reflected light emitted from the light source and reflected by the object.
The filter has Wcut_on as the upper limit wavelength at which the transmittance becomes 50% when light is incident from a direction inclined by a predetermined angle from the normal direction of the filter, and when light is incident from the normal direction of the filter. When the lower limit wavelength at which the transmittance becomes 50% is Wcut_off and the amount of change in the emission wavelength of the light source due to the initial wavelength variation of the light source and the temperature change is Wld, it has a transmission characteristic satisfying Wcut_on-Wcut_off> Wld. You may.
　前記テレセントリック光学系は、外形が矩形状でフレネル面を有するガラス基材を有してもよい。 The telecentric optical system may have a glass base material having a rectangular outer shape and a Fresnel surface.
第１の実施形態による受光装置を備えた電子システムのモジュール構成を示す図。The figure which shows the module structure of the electronic system provided with the light receiving device by 1st Embodiment. 受光装置の光学構成を示す図。The figure which shows the optical composition of a light receiving device. フレネル面を説明する図。The figure explaining the Fresnel surface. テレセントリック光学系の詳細な光学構成を示す図。The figure which shows the detailed optical composition of a telecentric optical system. 後群光学系のフレネル面の形状をより詳細に説明する図。The figure explaining the shape of the Fresnel surface of a rear group optical system in more detail. 本実施形態によるテレセントリック光学系の光学特性を示す図。The figure which shows the optical characteristic of the telecentric optical system by this embodiment. 後群光学系の一例を示す斜視図。The perspective view which shows an example of the rear group optical system. 後群光学系の断面図。Sectional view of the rear group optical system. ハイブリッド構造の後群光学系の一例を示す断面図。The cross-sectional view which shows an example of the rear group optical system of a hybrid structure. 第１比較例による光学系の光学構成を示す図。The figure which shows the optical composition of the optical system by 1st comparative example. 図８Ａの光学系の光学特性を示す図。The figure which shows the optical characteristic of the optical system of FIG. 8A. 第２比較例による光学系の光学構成を示す図。The figure which shows the optical composition of the optical system by 2nd comparative example. 図９Ａの光学系の光学特性を示す図。The figure which shows the optical characteristic of the optical system of FIG. 9A. 光源の特性変化を示す図。The figure which shows the characteristic change of a light source. 光源の温度依存性を示す図。The figure which shows the temperature dependence of a light source. フィルタに入射される光の波長、入射角度及び分光透過率の対応関係を示す図。The figure which shows the correspondence relationship of the wavelength of the light incident on a filter, the incident angle and the spectral transmittance. 過帯域幅ＢＷが５５ｎｍの場合のフィルタに入射される光の波長、入射角度及び分光透過率の対応関係を示す図。The figure which shows the correspondence relationship of the wavelength of the light incident on the filter, the incident angle and the spectral transmittance when the excess bandwidth BW is 55 nm. 過帯域幅ＢＷが４５ｎｍの場合のフィルタに入射される光の波長、入射角度及び分光透過率の対応関係を示す図。The figure which shows the correspondence relationship of the wavelength of the light incident on the filter, the incident angle and the spectral transmittance when the excess bandwidth BW is 45 nm. 過帯域幅ＢＷが３５ｎｍの場合のフィルタに入射される光の波長、入射角度及び分光透過率の対応関係を示す図。The figure which shows the correspondence relationship of the wavelength of the light incident on the filter, the incident angle and the spectral transmittance when the excess bandwidth BW is 35 nm. 過帯域幅ＢＷが２５ｎｍの場合のフィルタに入射される光の波長、入射角度及び分光透過率の対応関係を示す図。The figure which shows the correspondence relationship of the wavelength of the light incident on the filter, the incident angle and the spectral transmittance when the excess bandwidth BW is 25 nm. 図１２Ａ～図１２Ｄのフィルタの特性をまとめた図。It is a figure which summarized the characteristic of the filter of FIG. 12A to FIG. 12D. フィルタの透過帯域幅とデプス値の対応関係、及びフィルタの透過帯域幅とＳ／Ｎ比（ＳＮＲ）の対応関係を示す図。The figure which shows the correspondence relationship between the transmission bandwidth of a filter and a depth value, and the correspondence relationship between a transmission bandwidth of a filter and an S / N ratio (SNR). 第１比較例による光学系と、本実施形態によるテレセントリック光学系の特性を比較した図。The figure which compared the characteristic of the optical system by 1st comparative example and the telecentric optical system by this embodiment. 第２の実施形態による受光装置の光学構成を示す図。The figure which shows the optical structure of the light receiving device by 2nd Embodiment. 図１６のガラス基材にフレネル面を形成する前の曲面形状と、フレネル面１４の詳細な形状とを示す図。FIG. 6 is a diagram showing a curved surface shape before forming a Fresnel surface on the glass base material of FIG. 16 and a detailed shape of the Fresnel surface 14. 第２の実施形態によるテレセントリック光学系の像高（ｍｍ）と光線入射角度（度）との対応関係を示す図。The figure which shows the correspondence relationship between the image height (mm) and the ray incident angle (degrees) of the telecentric optical system by 2nd Embodiment. 第３の実施形態による受光装置の光学構成を示す図。The figure which shows the optical structure of the light receiving device according to 3rd Embodiment. 第３の実施形態によるテレセントリック光学系の像高（ｍｍ）と光線入射角度（度９との対応関係を示す図。The figure which shows the correspondence relationship between the image height (mm) of the telecentric optical system by 3rd Embodiment, and the ray incident angle (degree 9). 車両制御システムの概略的な構成の一例を示すブロック図である。It is a block diagram which shows an example of the schematic structure of a vehicle control system. 車外情報検出部及び撮像部の設置位置の一例を示す説明図である。It is explanatory drawing which shows an example of the installation position of the vehicle exterior information detection unit and the image pickup unit. 撮像部の設置位置の例を示す図である。It is a figure which shows the example of the installation position of the imaging unit.
　以下、図面を参照して、本開示による受光装置及び電子システムの実施形態について説明する。以下では、本開示による受光装置及び電子システムの主要な構成部分を中心に説明するが、本開示による受光装置及び電子システムには、図示又は説明されていない構成部分や機能が存在しうる。以下の説明は、図示又は説明されていない構成部分や機能を除外するものではない。 Hereinafter, embodiments of the light receiving device and the electronic system according to the present disclosure will be described with reference to the drawings. In the following, the main components of the light receiving device and the electronic system according to the present disclosure will be mainly described, but the light receiving device and the electronic system according to the present disclosure may have components and functions not shown or described. The following description does not exclude components or functions not shown or described.
　（第１の実施形態）
　図１は第１の実施形態による受光装置１を備えた電子システム２のモジュール構成を示す図である。図１の電子システム２は、受光装置１と、光源３と、支持基板４とを備えている。受光装置１と光源３は、支持基板４の一主面上に離隔して配置されている。 (First Embodiment)
FIG. 1 is a diagram showing a module configuration of an electronic system 2 including a light receiving device 1 according to the first embodiment. The electronic system 2 of FIG. 1 includes a light receiving device 1, a light source 3, and a support substrate 4. The light receiving device 1 and the light source 3 are arranged apart from each other on one main surface of the support substrate 4.
　図１の電子システム２は、光源３から発光された光を不図示の対象物に照射し、対象物からの反射光を受光装置１で受光する。受光装置１は、光源３から光を発光した時刻と、対象物からの反射光を受光した時刻との時間差により、電子システム２から対象物までの距離を計測する。このように、図１の電子システム２は、ＴｏＦシステムとして機能する。 The electronic system 2 of FIG. 1 irradiates an object (not shown) with the light emitted from the light source 3, and the light receiving device 1 receives the reflected light from the object. The light receiving device 1 measures the distance from the electronic system 2 to the object by the time difference between the time when the light is emitted from the light source 3 and the time when the reflected light from the object is received. As described above, the electronic system 2 of FIG. 1 functions as a ToF system.
　光源３は、例えば垂直共振器面発光レーザ（ＶＣＳＥＬ）などの発光素子と、発光素子が発光した光を均一に拡散するディフューザと、発光素子に駆動電力を供給するドライバとを有する。光源３は、例えば赤外光の波長帯域の光を発光する。なお、光源３が発光する光の波長帯域は任意である。 The light source 3 has, for example, a light emitting element such as a vertical cavity surface emitting laser (VCSEL), a diffuser that uniformly diffuses the light emitted by the light emitting element, and a driver that supplies driving power to the light emitting element. The light source 3 emits light in the wavelength band of infrared light, for example. The wavelength band of the light emitted by the light source 3 is arbitrary.
　図２は受光装置１の光学構成を示す図である。図２に示すように、受光装置１は、テレセントリック光学系１１と、バンドパスフィルタ（以下では、単にフィルタと呼ぶ）１２と、撮像部１３とを備えている。テレセントリック光学系１１、フィルタ１２、及び撮像部１３は、光軸２０に沿って順に配置されている。 FIG. 2 is a diagram showing an optical configuration of the light receiving device 1. As shown in FIG. 2, the light receiving device 1 includes a telecentric optical system 11, a bandpass filter (hereinafter, simply referred to as a filter) 12, and an imaging unit 13. The telecentric optical system 11, the filter 12, and the imaging unit 13 are arranged in order along the optical axis 20.
　フィルタ１２は、光源３が発光した光の波長帯域と同じ波長帯域の光を透過させ、それ以外の波長帯域の光を遮断する透過特性を有する。例えば、光源３が赤外光を発光する場合には、フィルタ１２は赤外光の波長帯域を透過させるＩＲＢＰＦである。 The filter 12 has a transmission characteristic that transmits light in the same wavelength band as the light emitted by the light source 3 and blocks light in other wavelength bands. For example, when the light source 3 emits infrared light, the filter 12 is an IRBPF that transmits an infrared light wavelength band.
　テレセントリック光学系１１は、レンズ長を長くすることなく、光軸２０に略平行な光を出射できるという特徴を有する。図２では、テレセントリック光学系１１のレンズ長をＬ１としている。本実施形態によるテレセントリック光学系１１は、後述するようにフレネル面１４を有する。フレネル面１４とは、レンズの曲面を、複数の同心円状の溝に置換したものである。フレネル面１４を設けることで、レンズの厚みを薄くすることができる。 The telecentric optical system 11 has a feature that light substantially parallel to the optical axis 20 can be emitted without increasing the lens length. In FIG. 2, the lens length of the telecentric optical system 11 is L1. The telecentric optical system 11 according to the present embodiment has a Fresnel surface 14 as described later. The Fresnel surface 14 replaces the curved surface of the lens with a plurality of concentric grooves. By providing the Fresnel surface 14, the thickness of the lens can be reduced.
　図３はフレネル面１４を説明する図である。図３の破線は一般的な凸レンズの曲面を示している。フレネル面１４は、凸レンズの曲面を同心円状に複数に分割し、各分割領域の曲面を凸レンズの中心面１４ａの方向に移動させて形成される段差状の曲面である。これにより、フレネル面１４には、複数の溝が形成され、各溝の底面が凸レンズの曲面と同様の曲率を有する。 FIG. 3 is a diagram illustrating the Fresnel surface 14. The broken line in FIG. 3 shows the curved surface of a general convex lens. The Fresnel surface 14 is a stepped curved surface formed by dividing the curved surface of the convex lens into a plurality of concentric circles and moving the curved surface of each divided region in the direction of the central surface 14a of the convex lens. As a result, a plurality of grooves are formed on the Fresnel surface 14, and the bottom surface of each groove has a curvature similar to the curved surface of the convex lens.
　図３のフレネル面１４の左側が光入射側で、右側がフィルタ１２側である。図３の細破線矢印線は、テレセントリック光学系１１に入射された光の進行方向を示している。図３に示すように、フレネル面１４に略平行に入射された光は、通常の凸レンズと同様に、焦点位置に集光される。一方、フレネル面１４に斜めに入射された光は、光軸２０方向に近い方向に屈折されて出射される。 The left side of the Fresnel surface 14 in FIG. 3 is the light incident side, and the right side is the filter 12 side. The thin dashed arrow line in FIG. 3 indicates the traveling direction of the light incident on the telecentric optical system 11. As shown in FIG. 3, the light incident substantially parallel to the Fresnel surface 14 is focused on the focal position in the same manner as a normal convex lens. On the other hand, the light obliquely incident on the Fresnel surface 14 is refracted in a direction close to the optical axis 20 direction and emitted.
　図２では、テレセントリック光学系１１に入射される光線を細実線で表している。テレセントリック光学系１１は、複数のレンズからなるレンズ群を光軸２０方向に並べた光学構成を有し、このレンズ群の一部にフレネル面１４が設けられている。 In FIG. 2, the light rays incident on the telecentric optical system 11 are represented by fine solid lines. The telecentric optical system 11 has an optical configuration in which a lens group composed of a plurality of lenses is arranged in the optical axis 20 direction, and a Fresnel surface 14 is provided as a part of the lens group.
　図４は本実施形態によるテレセントリック光学系１１の詳細な光学構成を示す図である。図４には、光軸２０の斜め下方からテレセントリック光学系１１に入射された光の進行方向を細実線で示している。図２及び図４に示すように、テレセントリック光学系１１は、前群光学系２１と後群光学系２２を有する。前群光学系２１は、入射光を集束させつつ、且つ、各々の主光線は発散させる屈折力を有する。後群光学系２２は、前群光学系２１を通過した主光線をコリメートする。コリメートとは、光を平行化することである。後群光学系２２は、上述したフレネル面１４を有する。後群光学系２２から出射された光は、フィルタ１２に入射される。フィルタ１２を透過した光は、撮像部１３に入射される。図２及び図４の右端は、撮像部１３の撮像面を表している。 FIG. 4 is a diagram showing a detailed optical configuration of the telecentric optical system 11 according to the present embodiment. In FIG. 4, the traveling direction of the light incident on the telecentric optical system 11 from diagonally below the optical axis 20 is shown by a fine solid line. As shown in FIGS. 2 and 4, the telecentric optical system 11 has a front group optical system 21 and a rear group optical system 22. The front group optical system 21 has a refractive power that focuses the incident light and diverges each main ray. The rear group optical system 22 collimates the main light beam that has passed through the front group optical system 21. Collimating is the parallelization of light. The rear group optical system 22 has the Fresnel surface 14 described above. The light emitted from the rear group optical system 22 is incident on the filter 12. The light transmitted through the filter 12 is incident on the imaging unit 13. The right end of FIGS. 2 and 4 represents the imaging surface of the imaging unit 13.
　前群光学系２１は、複数のレンズを光軸２０に沿って並べた構成を有する。図４の例では、前群光学系２１を３つのレンズからなるレンズ群で構成しているが、前群光学系２１を構成するレンズの数や形状は任意である。 The front group optical system 21 has a configuration in which a plurality of lenses are arranged along the optical axis 20. In the example of FIG. 4, the front group optical system 21 is composed of a lens group composed of three lenses, but the number and shape of the lenses constituting the front group optical system 21 are arbitrary.
　後群光学系２２は、前群光学系２１に対向配置される第１面と、フィルタ１２に対向配置される第２面とを有し、第２面はフレネル面１４である。図２及び図４の例では、後群光学系２２が一つのレンズで構成されている例を示しているが、複数のレンズからなるレンズ群で後群光学系２２を構成してもよい。図２及び図４では、後群光学系２２におけるフィルタ１２に対向配置される面をフレネル面１４にしているが、後群光学系２２内のフィルタ１２に対向配置される面以外の面をフレネル面１４にしてもよい。ただし、フィルタ１２に近い側にフレネル面を設けた方が、フィルタ１２に入射される光の方向を光軸２０方向に近づけることができる。 The rear group optical system 22 has a first surface which is arranged to face the front group optical system 21 and a second surface which is arranged to face the filter 12, and the second surface is a Fresnel surface 14. Although the examples of FIGS. 2 and 4 show an example in which the rear group optical system 22 is composed of one lens, the rear group optical system 22 may be composed of a lens group composed of a plurality of lenses. In FIGS. 2 and 4, the surface of the rear group optical system 22 facing the filter 12 is the Fresnel surface 14, but the surface of the rear group optical system 22 other than the surface facing the filter 12 is the Fresnel surface. It may be the surface 14. However, if the Fresnel surface is provided on the side closer to the filter 12, the direction of the light incident on the filter 12 can be made closer to the direction of the optical axis 20.
　図４の後群光学系２２は、光軸中心から周縁に向かうに従って、厚みが徐々に薄くなるレンズ２３を有する。このレンズ２３のフィルタ１２に対向する面（第２面）をフレネル面１４にしている。図３に示したように、フレネル面１４はレンズ２３の厚み、すなわち湾曲度合いを小さくすることができる。図４の例では、後群光学系２２のフレネル面１４側は、全体的な形状としては平坦な面である。これに対して、後群光学系２２の前群光学系２１側は大きく湾曲しており、光軸中心側が周縁側よりも前群光学系２１側に突き出ている。この結果、後群光学系２２は、光軸中心側ほど分厚く、周縁側ほど薄くなっている。 The rear group optical system 22 of FIG. 4 has a lens 23 whose thickness gradually decreases from the center of the optical axis toward the periphery. The surface (second surface) of the lens 23 facing the filter 12 is a Fresnel surface 14. As shown in FIG. 3, the Fresnel surface 14 can reduce the thickness of the lens 23, that is, the degree of curvature. In the example of FIG. 4, the Fresnel surface 14 side of the rear group optical system 22 is a flat surface as an overall shape. On the other hand, the front group optical system 21 side of the rear group optical system 22 is largely curved, and the optical axis center side protrudes toward the front group optical system 21 side rather than the peripheral edge side. As a result, the rear group optical system 22 is thicker toward the center of the optical axis and thinner toward the peripheral edge.
　後群光学系２２の厚みを光軸中心から周縁に向かうに従って徐々に薄くすることにより、後群光学系２２の周縁部でのＣＲＡを小さくすることができる。また、後群光学系２２のフィルタ１２と対向する面（第２面）をフレネル面１４にすることで、後群光学系２２から出射される光の進行方向を光軸２０に略平行にすることができる。 By gradually reducing the thickness of the rear group optical system 22 from the center of the optical axis toward the peripheral edge, the CRA at the peripheral edge of the rear group optical system 22 can be reduced. Further, by making the surface (second surface) of the rear group optical system 22 facing the filter 12 a Fresnel surface 14, the traveling direction of the light emitted from the rear group optical system 22 is made substantially parallel to the optical axis 20. be able to.
　図５は後群光学系２２のフレネル面１４の形状をより詳細に説明する図である。図５の左側の曲面は、フレネル面１４を形成する前の凸レンズのレンズ曲面を示している。このレンズ曲面を光軸中心から同心円状に複数の領域に分割して、各領域の分割曲面をレンズ中心面側に移動させることで、図５の右側のような段差状のフレネル面１４が形成される。フレネル面１４を形成する前と後で、レンズの厚みを比較すると、厚みを大幅に小さくできる。例えば、図５の例だと、フレネル面１４を形成する前と後では、１０倍以上の厚みの違いがある。フレネル面１４は、厚みを小さくしても、光学特性自体は、フレネル面１４を形成する前の凸レンズの光学特性を維持できるため、フレネル面１４にて入射光のコリメートを行うことができる。 FIG. 5 is a diagram for explaining the shape of the Fresnel surface 14 of the rear group optical system 22 in more detail. The curved surface on the left side of FIG. 5 shows the lens curved surface of the convex lens before forming the Fresnel surface 14. By dividing this lens curved surface into a plurality of regions concentrically from the center of the optical axis and moving the divided curved surface of each region toward the lens center surface side, a stepped Fresnel surface 14 as shown on the right side of FIG. 5 is formed. Will be done. Comparing the thicknesses of the lenses before and after forming the Fresnel surface 14, the thickness can be significantly reduced. For example, in the example of FIG. 5, there is a difference in thickness of 10 times or more before and after forming the Fresnel surface 14. Even if the thickness of the Fresnel surface 14 is reduced, the optical characteristics themselves can maintain the optical characteristics of the convex lens before forming the Fresnel surface 14, so that the incident light can be collimated on the Fresnel surface 14.
　図６は本実施形態によるテレセントリック光学系１１の光学特性を示す図であり、より具体的には、本実施形態によるテレセントリック光学系１１の像高（ｍｍ）と光線入射角度（度）との対応関係をしている。図６には、主光線の特性ｗ１と、主光線よりも下方側の光線の特性ｗ２と、主光線よりも上方側の光線の特性ｗ３とが図示されている。主光線の光線入射角度（ＣＲＡ）は、像高によらず、ほぼ０度であり、ＣＲＡが十分に小さいことがわかる。ＣＲＡが十分に小さいということは、フィルタ１２の入射面の法線方向に近い方向からフィルタ１２に光が入射されることを意味する。これにより、フィルタ１２の分光特性が悪化するおそれがなくなる。 FIG. 6 is a diagram showing the optical characteristics of the telecentric optical system 11 according to the present embodiment, and more specifically, the correspondence between the image height (mm) and the light incident angle (degrees) of the telecentric optical system 11 according to the present embodiment. Have a relationship. FIG. 6 illustrates the characteristic w1 of the main ray, the characteristic w2 of the ray below the main ray, and the characteristic w3 of the ray above the main ray. The ray incident angle (CRA) of the main ray is almost 0 degrees regardless of the image height, and it can be seen that the CRA is sufficiently small. A sufficiently small CRA means that light is incident on the filter 12 from a direction close to the normal direction of the incident surface of the filter 12. This eliminates the risk of deterioration of the spectral characteristics of the filter 12.
　図７Ａは後群光学系２２の一例を示す斜視図、図７Ｂは後群光学系２２の断面図である。図７Ａに示す後群光学系２２の外形形状は、フィルタ１２及び撮像部１３の外形形状に合わせて矩形状である。後群光学系２２の前群光学系２１に対向配置される面は、図示のように凸形状である。これに対して、後群光学系２２のフィルタ１２側に対向配置される面は、平坦面であるが、実際にはこの平坦面には微小サイズのフレネル面１４が形成されている。なお、後群光学系２２の外形形状は必ずしも矩形状である必要はないが、フィルタ１２や撮像部１３の外形形状に合わせた形状にするのが望ましい。 FIG. 7A is a perspective view showing an example of the rear group optical system 22, and FIG. 7B is a cross-sectional view of the rear group optical system 22. The outer shape of the rear group optical system 22 shown in FIG. 7A is rectangular according to the outer shapes of the filter 12 and the imaging unit 13. The surface of the rear group optical system 22 facing the front group optical system 21 has a convex shape as shown in the figure. On the other hand, the surface of the rear group optical system 22 facing the filter 12 side is a flat surface, but in reality, a minute-sized Fresnel surface 14 is formed on this flat surface. The outer shape of the rear group optical system 22 does not necessarily have to be rectangular, but it is desirable to have a shape that matches the outer shape of the filter 12 and the imaging unit 13.
　後群光学系２２は、例えばガラス基材を用いて形成される。ガラス基材をエッチング処理することで、比較的容易にフレネル面１４を形成できる。フレネル面１４は、図７Ａ及び図７Ｂの底面側に形成される。 The rear group optical system 22 is formed using, for example, a glass base material. By etching the glass substrate, the Fresnel surface 14 can be formed relatively easily. The Fresnel surface 14 is formed on the bottom surface side of FIGS. 7A and 7B.
　後群光学系２２をガラス基材のみで形成する代わりに、樹脂基材とガラス基材のハイブリッド構造にしてもよい。図７Ｃはハイブリッド構造の後群光学系２２の一例を示す断面図である。図７Ｃの例では、平坦なガラス基材２２０の上面をフレネル面に加工した後、このフレネル面に、光軸中心ほど厚みが大きい樹脂基材２２１を接合している。ガラス基材２２０の樹脂基材２２１との接合面とは反対側の面に、フィルタ１２として機能するコーティング層を設けてもよい。これにより、後群光学系２２とフィルタ１２とを密着させることができ、光の利用効率を向上できる。 Instead of forming the rear group optical system 22 only with a glass base material, a hybrid structure of a resin base material and a glass base material may be used. FIG. 7C is a cross-sectional view showing an example of the rear group optical system 22 having a hybrid structure. In the example of FIG. 7C, after the upper surface of the flat glass base material 220 is processed into a Fresnel surface, a resin base material 221 having a thickness as large as the center of the optical axis is bonded to the Fresnel surface. A coating layer that functions as a filter 12 may be provided on the surface of the glass substrate 220 opposite to the bonding surface with the resin substrate 221. As a result, the rear group optical system 22 and the filter 12 can be brought into close contact with each other, and the light utilization efficiency can be improved.
　図８Ａは第１比較例による光学系２５の光学構成を示す図である。図８Ｂは図８Ａの光学系２５の光学特性を示す図であり、図８Ａの光学系２５の像高と光線入射角度との対応関係を示している。図８Ａの光学系２５は、テレセントリック光学系１１ではないため、レンズ長を短くできるものの、図６に比べてＣＲＡが大きくなる。図８ＢのＣＲＡでは、フィルタ１２の法線方向から傾斜した方向からフィルタ１２に光が入射されるため、フィルタ１２の分光特性が悪化してしまう。 FIG. 8A is a diagram showing an optical configuration of the optical system 25 according to the first comparative example. FIG. 8B is a diagram showing the optical characteristics of the optical system 25 of FIG. 8A, and shows the correspondence between the image height of the optical system 25 of FIG. 8A and the light ray incident angle. Since the optical system 25 of FIG. 8A is not the telecentric optical system 11, the lens length can be shortened, but the CRA is larger than that of FIG. In the CRA of FIG. 8B, since light is incident on the filter 12 from a direction inclined from the normal direction of the filter 12, the spectral characteristics of the filter 12 are deteriorated.
　図９Ａは第２比較例による光学系２６の光学構成を示す図である。図９Ｂは図９Ａの光学系２６の光学特性を示す図であり、図９Ａの光学系２６の像高と光線入射角度との対応関係を示している。図９Ａの光学系２６は、光軸後方側のレンズの厚みを大きくすることでテレセントリック光学系を実現しており、図９Ｂに示すようにＣＲＡも小さくできる。ところが、図９Ａの光学系２６のレンズ長は、図３や図８Ａよりも長くなるため、スマートフォン等の携帯機器に実装するのは困難である。 FIG. 9A is a diagram showing an optical configuration of the optical system 26 according to the second comparative example. 9B is a diagram showing the optical characteristics of the optical system 26 of FIG. 9A, and shows the correspondence between the image height of the optical system 26 of FIG. 9A and the light ray incident angle. The optical system 26 of FIG. 9A realizes a telecentric optical system by increasing the thickness of the lens on the rear side of the optical axis, and as shown in FIG. 9B, the CRA can also be reduced. However, since the lens length of the optical system 26 of FIG. 9A is longer than that of FIGS. 3 and 8A, it is difficult to mount it on a portable device such as a smartphone.
　光源３から発光される光の波長は、製造ばらつきや温度変化により変動する。光源３から発光される光の波長が変動すると、受光装置１で受光される光の波長も変動し、フィルタ１２の分光特性にも悪影響を与えてしまう。 The wavelength of the light emitted from the light source 3 fluctuates due to manufacturing variations and temperature changes. When the wavelength of the light emitted from the light source 3 fluctuates, the wavelength of the light received by the light receiving device 1 also fluctuates, which adversely affects the spectral characteristics of the filter 12.
　図１０Ａは光源３の特性変化を示す図、図１０Ｂは光源３の温度依存性を示す図である。なお、図１０Ａと図１０Ｂは特定の光源３についての特性変化を示したものであり、光源３の種類が異なれば、異なる結果が得られる。図１０Ｂの横軸は波長［ｎｍ］、縦軸は光強度［a.u.］である。 FIG. 10A is a diagram showing a change in the characteristics of the light source 3, and FIG. 10B is a diagram showing the temperature dependence of the light source 3. It should be noted that FIGS. 10A and 10B show changes in the characteristics of the specific light source 3, and different results can be obtained if the type of the light source 3 is different. The horizontal axis of FIG. 10B is the wavelength [nm], and the vertical axis is the light intensity [a.u.].
　図１０Ａの上２段は光源３の製造ばらつきによる波長の変動を示している。図１０Ａの上から３段目から６段目は光源３の温度による波長の変動を示している。 The upper two stages of FIG. 10A show wavelength fluctuations due to manufacturing variations of the light source 3. The third to sixth stages from the top of FIG. 10A show the fluctuation of the wavelength depending on the temperature of the light source 3.
　図１０Ａに示すように、光源３の製造ばらつきにより、発光波長は９５１．５－９３５．５＝１６ｎｍ変化し、中心波長は９４３．５ｎｍである。 As shown in FIG. 10A, the emission wavelength changes by 951.5-935.5 = 16 nm due to the manufacturing variation of the light source 3, and the center wavelength is 943.5 nm.
　また、図１０Ａ及び図１０Ｂに示すように、温度が高くなるに従って、光源３の発光波長は高くなるとともに、光強度は小さくなる。例えば、０℃と８５℃で比較すると、発光波長は９５５．１－９３４＝２１．１ｎｍ異なる。 Further, as shown in FIGS. 10A and 10B, as the temperature increases, the emission wavelength of the light source 3 increases and the light intensity decreases. For example, when compared at 0 ° C. and 85 ° C., the emission wavelengths differ by 955.1-934 = 21.1 nm.
　図１０Ａからわかるように、発光波長の変動量は、発光素子の製造ばらつきによる変動量（＝１６ｎｍ）よりも、温度変化による変動量（＝２１．１ｎｍ）の方が大きい。 As can be seen from FIG. 10A, the fluctuation amount of the emission wavelength is larger (= 21.1 nm) due to the temperature change than the fluctuation amount (= 16 nm) due to the manufacturing variation of the light emitting element.
　このように、光源３から発光される光の波長は、製造ばらつきや温度等により変動し、これに伴って受光装置１で受光される対象物からの反射光の波長帯域も変動する。フィルタ１２の分光透過率は、フィルタ１２に入射される光の波長により変化する。また、フィルタ１２の分光透過率は、フィルタ１２に入射される光の入射角度によっても変化する。 In this way, the wavelength of the light emitted from the light source 3 fluctuates due to manufacturing variations, temperature, and the like, and the wavelength band of the reflected light from the object received by the light receiving device 1 also fluctuates accordingly. The spectral transmittance of the filter 12 changes depending on the wavelength of the light incident on the filter 12. The spectral transmittance of the filter 12 also changes depending on the incident angle of the light incident on the filter 12.
　図１１はフィルタ１２に入射される光の波長、入射角度及び分光透過率の対応関係を示す図である。図１１の曲線ｗ４は０度入射時の波長と分光透過率の対応関係を示し、曲線ｗ５は３０度入射時の波長と分光透過率の対応関係を示している。ここで、入射角度とは、フィルタ１２の法線方向に対する傾斜角度であり、０度は法線方向から光が入射されることを意味する。 FIG. 11 is a diagram showing the correspondence between the wavelength of light incident on the filter 12, the angle of incidence, and the spectral transmittance. The curve w4 in FIG. 11 shows the correspondence between the wavelength at 0 degree incident and the spectral transmittance, and the curve w5 shows the correspondence between the wavelength at 30 degree incident and the spectral transmittance. Here, the incident angle is an inclination angle of the filter 12 with respect to the normal direction, and 0 degree means that light is incident from the normal direction.
　図１１では、３０度入射光線に対して分光透過率が５０％になる波長をカットオン波長Ｗcut_onと呼び、０度入射光線に対して分光透過率が５０％になる下限の波長をカットオフ波長Ｗcut_offと呼んでいる。 In FIG. 11, the wavelength at which the spectral transmittance is 50% with respect to the 30-degree incident light beam is called the cut-on wavelength Wcut_on, and the lower limit wavelength at which the spectral transmittance is 50% with respect to the 0-degree incident light beam is called the cut-off wavelength. We call it Wcut_off.
　カットオン波長Ｗcut_onとカットオフ波長Ｗcut_offとの差分の波長幅（以下、波長変動帯域幅）は、０～３０度の範囲内で光の入射角度が変化しても、フィルタ１２が透過させることができる光の帯域幅（波長変動帯域幅）である。 The wavelength width of the difference between the cut-on wavelength Wcut_on and the cut-off wavelength Wcut_off (hereinafter referred to as the wavelength fluctuation bandwidth) can be transmitted by the filter 12 even if the incident angle of light changes within the range of 0 to 30 degrees. The bandwidth of light that can be produced (wavelength fluctuation bandwidth).
　波長変動帯域幅は、図１１に示すように、０度入射光線の透過帯域幅ＢＷから、０度入射光線に対して分光透過率が５０％になる波長と、３０度入射光線に対して分光透過率が５０％になる波長との差分帯域幅Ｗｓを引いた値に等しい。すなわち、以下の式（１）の関係が成り立つ。
　ＢＷ－Ｗs＝Ｗcut_on－Ｗcut_off　　…（１） As shown in FIG. 11, the wavelength fluctuation bandwidth is separated from the transmission bandwidth BW of the 0-degree incident ray, the wavelength at which the spectral transmittance is 50% with respect to the 0-degree incident ray, and the spectrum with respect to the 30-degree incident ray. It is equal to the value obtained by subtracting the difference bandwidth Ws from the wavelength at which the transmittance becomes 50%. That is, the relationship of the following equation (1) holds.
BW-Ws = Wcut_on-Wcut_off ... (1)
　フィルタ１２の種類によって、カットオン波長Ｗcut_onとカットオフ波長Ｗcut_offとの差分である波長変動帯域幅は異なる。図１２Ａ、図１２Ｂ、図１２Ｃ、図１２Ｄはそれぞれ、透過帯域幅ＢＷが５５ｎｍ、４５ｎｍ、３５ｎｍ、２５ｎｍのフィルタ１２に入射される光の波長、入射角度及び分光透過率の対応関係を示す図である。上述した差分帯域幅Ｗsも、透過帯域幅ＢＷによって異なる。 The wavelength fluctuation bandwidth, which is the difference between the cut-on wavelength Wcut_on and the cut-off wavelength Wcut_off, differs depending on the type of the filter 12. 12A, 12B, 12C, and 12D are diagrams showing the correspondence between the wavelength, the angle of incidence, and the spectral transmittance of the light incident on the filter 12 having a transmission bandwidth BW of 55 nm, 45 nm, 35 nm, and 25 nm, respectively. be. The above-mentioned differential bandwidth Ws also differs depending on the transmission bandwidth BW.
　発光素子の発光波長の温度変化による変動量は、図１０Ａから２１．１ｎｍである。上述した式（１）のカットオン波長Ｗcut_onとカットオフ波長Ｗcut_offとの差分（波長変動帯域幅）が２１．１ｎｍ以上でないと、フィルタ１２の分光特性が悪化するおそれがある。 The amount of fluctuation due to the temperature change of the emission wavelength of the light emitting element is 21.1 nm from FIG. 10A. If the difference (wavelength fluctuation bandwidth) between the cut-on wavelength Wcut_on and the cut-off wavelength Wcut_off in the above equation (1) is not 21.1 nm or more, the spectral characteristics of the filter 12 may deteriorate.
　図１３は図１２Ａ～図１２Ｄのフィルタ１２の特性をまとめた図である。カットオン波長Ｗcut_onとカットオフ波長Ｗcut_offとの差分（波長変動帯域幅）が大きいほど、フィルタ１２は光源３から発光された光の反射光以外のノイズ光も透過してしまう。その一方で、波長変動帯域幅が狭すぎると、光源３から発光される光の波長が製造ばらつきや温度変化で変動したときに、反射光を透過できないおそれがある。 FIG. 13 is a diagram summarizing the characteristics of the filter 12 of FIGS. 12A to 12D. The larger the difference (wavelength fluctuation bandwidth) between the cut-on wavelength Wcut_on and the cut-off wavelength Wcut_off, the more noise light other than the reflected light of the light emitted from the light source 3 is transmitted by the filter 12. On the other hand, if the wavelength fluctuation bandwidth is too narrow, the reflected light may not be transmitted when the wavelength of the light emitted from the light source 3 fluctuates due to manufacturing variation or temperature change.
　図１４は、フィルタ１２の透過帯域幅とデプス値の対応関係、及びフィルタ１２の透過帯域幅とＳ／Ｎ比（ＳＮＲ）の対応関係を示す図である。デプス値とは、受光装置１で計測される対象物までの距離誤差であり、デプス値が大きいほど距離誤差が大きいことを示す。また、Ｓ／Ｎ比は大きい程ノイズの影響を受けにくいことを示す。図１４のグラフｗ６はフィルタ１２の透過帯域幅とデプス値との対応関係を表している。グラフｗ７はフィルタ１２の透過帯域幅とＳ／Ｎ比との対応関係を表している。グラフｗ６上に破線で示すように、透過帯域幅ＢＷ＝３５のときのデプス値１３．８は、透過帯域幅ＢＷ＝４５のときのデプス値１６．１よりも小さい。また、透過帯域幅ＢＷが小さいほどＳ／Ｎ比は高くなる。以上より、透過帯域幅ＢＷは小さい方が距離計測を行う観点では望ましいことがわかる。 FIG. 14 is a diagram showing the correspondence between the transmission bandwidth of the filter 12 and the depth value, and the correspondence between the transmission bandwidth of the filter 12 and the S / N ratio (SNR). The depth value is the distance error to the object measured by the light receiving device 1, and the larger the depth value, the larger the distance error. Further, it is shown that the larger the S / N ratio is, the less susceptible to noise. Graph w6 of FIG. 14 shows the correspondence between the transmission bandwidth of the filter 12 and the depth value. Graph w7 shows the correspondence between the transmission bandwidth of the filter 12 and the S / N ratio. As shown by the broken line on the graph w6, the depth value 13.8 when the transmission bandwidth BW = 35 is smaller than the depth value 16.1 when the transmission bandwidth BW = 45. Further, the smaller the transmission bandwidth BW, the higher the S / N ratio. From the above, it can be seen that the smaller the transmission bandwidth BW is, the more desirable from the viewpoint of distance measurement.
　そこで、本実施形態では、カットオン波長Ｗcut_onとカットオフ波長Ｗcut_offとの差分（波長変動帯域幅）が発光素子の発光波長の温度変化による変動量２１．１ｎｍよりも大きい透過帯域幅ＢＷの中で最小の値である透過帯域幅ＢＷ＝３５ｎｍを選択する。 Therefore, in the present embodiment, the difference between the cut-on wavelength Wcut_on and the cut-off wavelength Wcut_off (wavelength fluctuation bandwidth) is larger than the fluctuation amount of 21.1 nm due to the temperature change of the emission wavelength of the light emitting element in the transmission bandwidth BW. The minimum value, transmission bandwidth BW = 35 nm, is selected.
　なお、透過帯域幅ＢＷが変動量２１．１ｎｍより大きければよいため、透過帯域幅ＢＷ＝４５ｎｍ又は５５ｎｍを選択してもよい。 Since the transmission bandwidth BW may be larger than the fluctuation amount of 21.1 nm, the transmission bandwidth BW = 45 nm or 55 nm may be selected.
　以上をまとめると、本実施形態では、以下の式（２）の不等式を満たすようにフィルタ１２の透過特性を設定する。式（２）におけるＷldは、光源３の初期波長ばらつきと温度変化による発光波長の変動量である。また、Ｗcut_off－Ｗcut_onは、フィルタ１２の法線方向から光が入射された場合に透過率が５０％になる上限の波長と、フィルタ１２の法線方向から所定角度（例えば３０度）傾斜した方向から光が入射された場合に透過率が５０％になる上限の波長との差分波長である。式（２）を満たすようにすることで、テレセントリック光学系１１から出射されるすべての光線を、フィルタ１２は５０％以上の透過率で透過させることができる。これにより、フィルタ１２の分光特性を改善できる。
　Ｗcut_off－Ｗcut_on＞Ｗld　　…（２） Summarizing the above, in the present embodiment, the transmission characteristics of the filter 12 are set so as to satisfy the inequality of the following equation (2). Wld in the formula (2) is the amount of fluctuation of the emission wavelength due to the initial wavelength variation of the light source 3 and the temperature change. Wcut_off-Wcut_on is the upper limit wavelength at which the transmittance becomes 50% when light is incident from the normal direction of the filter 12, and the direction inclined by a predetermined angle (for example, 30 degrees) from the normal direction of the filter 12. It is a difference wavelength from the upper limit wavelength at which the transmittance becomes 50% when light is incident from the above. By satisfying the equation (2), the filter 12 can transmit all the light rays emitted from the telecentric optical system 11 with a transmittance of 50% or more. Thereby, the spectral characteristics of the filter 12 can be improved.
Wcut_off－Wcut_on> Wld… (2)
　図１５は第１比較例による光学系２５と、本実施形態によるテレセントリック光学系１１の特性を比較した図である。図１５の上段の左側は第１比較例による光学系２５の光学特性を示し、上段の右側は本実施形態による光学系１１の光学特性を示している。また、図１５の下段の左側は第１比較例によるフィルタ１２の透過特性を示し、下段の右側は本実施形態によるフィルタ１２の透過特性を示している。図１５の上段の図から、本実施形態は第１比較例よりもＣＲＡを小さくできることがわかる。また、図１５の下段の図から、本実施形態は第１比較例よりもフィルタ１２の透過帯域幅を狭くしても、その透過帯域幅内に反射光の波長変動範囲を収めることができる。 FIG. 15 is a diagram comparing the characteristics of the optical system 25 according to the first comparative example and the telecentric optical system 11 according to the present embodiment. The left side of the upper part of FIG. 15 shows the optical characteristics of the optical system 25 according to the first comparative example, and the right side of the upper part shows the optical characteristics of the optical system 11 according to the present embodiment. Further, the left side of the lower part of FIG. 15 shows the transmission characteristics of the filter 12 according to the first comparative example, and the right side of the lower part shows the transmission characteristics of the filter 12 according to the present embodiment. From the upper part of FIG. 15, it can be seen that this embodiment can make the CRA smaller than that of the first comparative example. Further, from the lower part of FIG. 15, in the present embodiment, even if the transmission bandwidth of the filter 12 is narrower than that of the first comparative example, the wavelength fluctuation range of the reflected light can be contained within the transmission bandwidth.
　このように、第１の実施形態では、受光装置１内にフレネル面１４を有するテレセントリック光学系１１を設けるため、テレセントリック光学系１１から出射される光の方向を光軸に略平行にすることができる。これにより、テレセントリック光学系１１を透過した光がフィルタ１２に入射される際のＣＲＡを小さくすることができ、フィルタ１２の分光特性を改善することができる。 As described above, in the first embodiment, since the telecentric optical system 11 having the Fresnel surface 14 is provided in the light receiving device 1, the direction of the light emitted from the telecentric optical system 11 can be made substantially parallel to the optical axis. can. As a result, the CRA when the light transmitted through the telecentric optical system 11 is incident on the filter 12 can be reduced, and the spectral characteristics of the filter 12 can be improved.
　（第２の実施形態）
　図１６は第２の実施形態による受光装置１ａの光学構成を示す図である。図１６の受光装置１ａは、図２とは異なる光学構成のテレセントリック光学系１１ａと、フィルタ１２と、撮像部１３とを備えている。図１６のテレセントリック光学系１１ａは、前群光学系２１ａと、後群光学系２２ａとを有する。前群光学系２１ａは、光軸方向に順に配置される例えば４つのレンズを有する。なお、レンズの枚数及び形状は図１６に示した以外のものに変更可能である。 (Second embodiment)
FIG. 16 is a diagram showing an optical configuration of the light receiving device 1a according to the second embodiment. The light receiving device 1a of FIG. 16 includes a telecentric optical system 11a having an optical configuration different from that of FIG. 2, a filter 12, and an imaging unit 13. The telecentric optical system 11a of FIG. 16 has a front group optical system 21a and a rear group optical system 22a. The front group optical system 21a has, for example, four lenses arranged in order in the optical axis direction. The number and shape of the lenses can be changed to those other than those shown in FIG.
　後群光学系２２ａには、フィルタ１２が一体形成されている。後群光学系２２ａは、厚さが略均一なガラス基材を有する。ガラス基材の前群光学系２１ａに対向する面はフレネル面１４である。また、ガラス基材の撮像部１３側の面にはコーティング層２３ａが設けられている。このコーティング層２３ａは、フィルタ１２として機能する層であり、所定の波長帯域の光を透過し、それ以外の波長帯域の光を透過させない。 The filter 12 is integrally formed in the rear group optical system 22a. The rear group optical system 22a has a glass substrate having a substantially uniform thickness. The surface of the glass substrate facing the front group optical system 21a is the Fresnel surface 14. Further, a coating layer 23a is provided on the surface of the glass substrate on the image pickup unit 13 side. The coating layer 23a is a layer that functions as a filter 12, and transmits light in a predetermined wavelength band and does not transmit light in other wavelength bands.
　このように、図１６の後群光学系２２ａは、厚さが均一なガラス基材を有する点で、図２の後群光学系２２ａとは異なる。また、図１６の後群光学系２２ａは、後群光学系２２ａの前群光学系２１ａに対向配置される面をフレネル面１４とする点でも図２の後群光学系２２ａとは異なる。 As described above, the rear group optical system 22a of FIG. 16 is different from the rear group optical system 22a of FIG. 2 in that it has a glass substrate having a uniform thickness. Further, the rear group optical system 22a of FIG. 16 is different from the rear group optical system 22a of FIG. 2 in that the surface of the rear group optical system 22a facing the front group optical system 21a is a Fresnel surface 14.
　図１６のテレセントリック光学系１１ａのレンズ長Ｌ４は、図２のテレセントリック光学系１１ａのレンズ長Ｌ１と同程度にすることができる。具体的には、前群光学系２１ａと後群光学系２２ａの内部のレンズ構成を調整することで、レンズ長を制御することができる。このレンズ長Ｌ４は、図９Ａに示す第２比較例のレンズ長Ｌ３よりも短い。 The lens length L4 of the telecentric optical system 11a of FIG. 16 can be made approximately the same as the lens length L1 of the telecentric optical system 11a of FIG. Specifically, the lens length can be controlled by adjusting the internal lens configurations of the front group optical system 21a and the rear group optical system 22a. This lens length L4 is shorter than the lens length L3 of the second comparative example shown in FIG. 9A.
　図１７は図１６のガラス基材にフレネル面１４を形成する前の曲面形状と、フレネル面１４の詳細な形状とを示す図である。図１６のガラス基材に形成されるフレネル面１４は、図５と同様に、ガラス基材の光軸中心から同心円状に複数の分割領域を設けて、各分割領域の曲面をガラス基材の中心面方向に移動させて形成される。 FIG. 17 is a diagram showing a curved surface shape before forming the Fresnel surface 14 on the glass substrate of FIG. 16 and a detailed shape of the Fresnel surface 14. Similar to FIG. 5, the Fresnel surface 14 formed on the glass base material of FIG. 16 is provided with a plurality of divided regions concentrically from the center of the optical axis of the glass base material, and the curved surface of each divided region is formed on the glass base material. It is formed by moving it toward the central surface.
　図１８は第２の実施形態によるテレセントリック光学系１１ａの像高（ｍｍ）と光線入射角度（度）との対応関係を示す図である。図１８と図６を比較すればわかるように、第２の実施形態によるテレセントリック光学系１１ａは、第１の実施形態によるテレセントリック光学系１１ａと同様に、ＣＲＡを小さくでき、フィルタ１２として機能するコーティング層２３ａに対して、光軸に略平行な光を入射させることができるため、フィルタ１２の分光特性を改善できる。 FIG. 18 is a diagram showing the correspondence between the image height (mm) of the telecentric optical system 11a and the light ray incident angle (degrees) according to the second embodiment. As can be seen by comparing FIG. 18 and FIG. 6, the telecentric optical system 11a according to the second embodiment has a coating that can reduce the CRA and functions as a filter 12, similarly to the telecentric optical system 11a according to the first embodiment. Since light substantially parallel to the optical axis can be incident on the layer 23a, the spectral characteristics of the filter 12 can be improved.
　上述したガラス基材の代わりに、樹脂部材を設けてもよい。樹脂部材であっても、前群光学系２１ａ側の面をフレネル面１４にし、かつ撮像部１３側の面にコーティング層２３ａを設けて、フィルタ１２として機能させることができる。 A resin member may be provided instead of the glass base material described above. Even if it is a resin member, the surface on the front group optical system 21a side can be made into a Fresnel surface 14, and the surface on the imaging unit 13 side can be provided with a coating layer 23a to function as a filter 12.
　このように、第２の実施形態では、テレセントリック光学系１１ａの内部に、厚みが略均一なガラス基材又は樹脂基材を設けて、この基材の前群光学系２１ａ側の面をフレネル面１４にし、かつ撮像部１３側の面にコーティング層２３ａを設けてフィルタ１２として機能させるため、簡易な構造でＣＲＡを小さくでき、第１の実施形態と同様にフィルタ１２の分光特性を改善できる。 As described above, in the second embodiment, a glass base material or a resin base material having a substantially uniform thickness is provided inside the telecentric optical system 11a, and the surface of the base material on the front group optical system 21a side is a Fresnel surface. Since the coating layer 23a is provided on the surface of the imaging unit 13 to function as the filter 12, the CRA can be reduced with a simple structure, and the spectral characteristics of the filter 12 can be improved as in the first embodiment.
　（第３の実施形態）
　上述した第１及び第２の実施形態は、テレセントリック光学系１１の内部の後群光学系２２がフレネル面１４を有する例を説明したが、フレネル面１４なしの構成も考えられる。 (Third Embodiment)
Although the first and second embodiments described above have described an example in which the rear group optical system 22 inside the telecentric optical system 11 has a Fresnel surface 14, a configuration without a Fresnel surface 14 is also conceivable.
　図１９は第３の実施形態による受光装置１ｂの光学構成を示す図である。図１９の受光装置１ｂは、フレネル面１４を持たないテレセントリック光学系１１ｂを備えている。図１９のテレセントリック光学系１１ｂは、前群光学系２１ｂと後群光学系２２ｂを備えている。前群光学系２１ｂの光学構成は、図２や図１６等とほぼ同じである。後群光学系２２ｂは、平坦なガラス基材２２ｃの前群光学系２１ｂ側の面に樹脂基材２２ｄを接合するとともに、ガラス基材２２ｃの撮像部１３側の面にコーティング層２３ａを設けている。樹脂基材２２ｄは光軸中心ほど厚く、周縁に向かうに従って薄くしている。このように、樹脂基材２２ｄの周縁側を薄くすることにより、ＣＲＡを小さくでき、フレネル面１４がなくても、樹脂基材２２ｄを透過する光を光軸に略平行にすることができる。 FIG. 19 is a diagram showing an optical configuration of the light receiving device 1b according to the third embodiment. The light receiving device 1b of FIG. 19 includes a telecentric optical system 11b having no Fresnel surface 14. The telecentric optical system 11b of FIG. 19 includes a front group optical system 21b and a rear group optical system 22b. The optical configuration of the front group optical system 21b is almost the same as that in FIGS. 2 and 16. In the rear group optical system 22b, the resin base material 22d is bonded to the surface of the flat glass base material 22c on the front group optical system 21b side, and the coating layer 23a is provided on the surface of the glass base material 22c on the image pickup portion 13 side. There is. The resin base material 22d is thicker toward the center of the optical axis and thinner toward the periphery. By thinning the peripheral side of the resin base material 22d in this way, the CRA can be made small, and the light transmitted through the resin base material 22d can be made substantially parallel to the optical axis even without the Fresnel surface 14.
　図２０は第３の実施形態によるテレセントリック光学系１１ｂの像高（ｍｍ）と光線入射角度（度９との対応関係を示す図である。図示のように、像高によらず、ＣＲＡを小さくすることができる。 FIG. 20 is a diagram showing the correspondence between the image height (mm) of the telecentric optical system 11b and the light ray incident angle (degree 9) according to the third embodiment. As shown in the figure, the CRA is reduced regardless of the image height. can do.
　このように、第３の実施形態では、テレセントリック光学系１１ｂの内部の後群光学系２２ｂにガラス基材２２ｃに接合された樹脂基材２２ｄを設けて、この樹脂基材２２ｄの厚みを光軸中心側から周縁にかけて徐々に薄くするため、フレネル面１４を設けなくても、ＣＲＡを小さくできる。また、ガラス基材２２ｃの撮像部１３側の面にコーティング層２３ａを形成してフィルタ１２として機能させるため、簡易な光学構成でありながら、フィルタ１２の分光特性を改善できる。 As described above, in the third embodiment, the resin base material 22d bonded to the glass base material 22c is provided in the rear group optical system 22b inside the telecentric optical system 11b, and the thickness of the resin base material 22d is set as the optical axis. Since the thickness is gradually reduced from the center side to the peripheral edge, the CRA can be reduced without providing the Fresnel surface 14. Further, since the coating layer 23a is formed on the surface of the glass base material 22c on the image pickup unit 13 side to function as the filter 12, the spectral characteristics of the filter 12 can be improved even though the optical configuration is simple.
　（電子システム２の詳細構成）
　上述した第１～第３の実施形態における受光装置１を備えた電子システム２は、光源３が発光した光を対象物に照射して、その反射光を受光し、光源３が光を発光した時刻と、受光装置１が反射光を受光した時刻との時間差に基づいて、対象物までの距離を計測することができる。 (Detailed configuration of electronic system 2)
The electronic system 2 provided with the light receiving device 1 according to the first to third embodiments described above irradiates the object with the light emitted by the light source 3, receives the reflected light, and the light source 3 emits the light. The distance to the object can be measured based on the time difference between the time and the time when the light receiving device 1 receives the reflected light.
　図２１は光源３及び受光装置１を備える電子システム２の詳細なブロック図である。光源３は、１つの発光素子３１を有していてもよいし、複数の発光素子３１を有していてもよい。発光素子３１は、ドライバ３２からの電力により光を発光する。ドライバ３２は、受光装置１からの信号により、発光素子３１に電力を供給するタイミングを制御する。 FIG. 21 is a detailed block diagram of an electronic system 2 including a light source 3 and a light receiving device 1. The light source 3 may have one light emitting element 31 or may have a plurality of light emitting elements 31. The light emitting element 31 emits light by the electric power from the driver 32. The driver 32 controls the timing of supplying electric power to the light emitting element 31 by the signal from the light receiving device 1.
　受光装置１は、例えば、受光部３３と、ＴＤＣ３４と、演算部３５と、トリガ生成部３６と、制御部３７と、インタフェース部３８とを有する。 The light receiving device 1 includes, for example, a light receiving unit 33, a TDC 34, a calculation unit 35, a trigger generation unit 36, a control unit 37, and an interface unit 38.
　受光部３３は、ＳＰＡＤアレイ３９と、読み出し回路４０を有する。ＳＰＡＤアレイ３９は、複数のＳＰＡＤ(Single Photon Avalanche Diode)を一次元又は二次元方向に配置したものである。なお、ＳＰＡＤ以外の光電変換素子を設けてもよい。ＳＰＡＤアレイ３９内の任意のＳＰＡＤが光を検知すると、光量に応じた振幅の電気信号が出力される。読み出し回路４０は、ＳＰＡＤアレイ３９内の任意のＳＰＡＤから出力された電気信号を読み出す。ＴＤＣ３４は、読み出し回路４０が読み出した電気信号のタイミングと、トリガ生成部３６がドライバ３２にトリガ信号を送信するタイミングとの時間差を計測する。演算部３５は、ＴＤＣ３４の出力信号に基づいて、各種の信号処理を行う。演算部３５が行う信号処理は、例えば、発光素子３１が光を発光する時刻と、受光部３３が反射光を受光する時刻との時間差に基づいて、対象物までの距離を計測する処理を含んでいる。 The light receiving unit 33 has a SPAD array 39 and a read circuit 40. The SPAD array 39 is a plurality of SPADs (Single Photon Avalanche Diodes) arranged in a one-dimensional or two-dimensional direction. A photoelectric conversion element other than SPAD may be provided. When any SPAD in the SPAD array 39 detects light, an electric signal having an amplitude corresponding to the amount of light is output. The read circuit 40 reads an electric signal output from any SPAD in the SPAD array 39. The TDC 34 measures the time difference between the timing of the electric signal read by the reading circuit 40 and the timing of the trigger generation unit 36 transmitting the trigger signal to the driver 32. The calculation unit 35 performs various signal processing based on the output signal of the TDC 34. The signal processing performed by the calculation unit 35 includes, for example, a process of measuring the distance to the object based on the time difference between the time when the light emitting element 31 emits light and the time when the light receiving unit 33 receives the reflected light. I'm out.
　受光部３３は、対象物からの反射光だけでなく、太陽光などのノイズ光も受光する可能性がある。ノイズ光が受光されるタイミングは、本来の反射光が受光されるタイミングとは異なるため、繰り返し光源３が光を発光し、それに合わせて受光装置１も繰り返し反射光を受光して距離計測を繰り返し、複数の距離計測結果を平均化するなどして、ノイズ光による影響を除去した状態で距離を計測してもよい。このため、演算部３５には、ヒストグラム生成部３５ａを設けてもよい。ヒストグラム生成部３５ａは、複数回の距離計測結果を平均化したり、複数の距離計測結果から多数決により距離を計測する。 The light receiving unit 33 may receive not only reflected light from an object but also noise light such as sunlight. Since the timing at which the noise light is received is different from the timing at which the original reflected light is received, the light source 3 repeatedly emits light, and the light receiving device 1 repeatedly receives the reflected light and repeats the distance measurement accordingly. , The distance may be measured in a state where the influence of noise light is removed by averaging a plurality of distance measurement results. Therefore, the calculation unit 35 may be provided with a histogram generation unit 35a. The histogram generation unit 35a averages the distance measurement results of a plurality of times, and measures the distance from the plurality of distance measurement results by a majority vote.
　制御部３７は、受光装置１内の各部を制御する。演算部３５で演算された距離計測結果は、制御部３７とインタフェース部３８を介して外部に送られる。 The control unit 37 controls each unit in the light receiving device 1. The distance measurement result calculated by the calculation unit 35 is sent to the outside via the control unit 37 and the interface unit 38.
　トリガ生成部３６は、光源３が光を発光するタイミングを決定して、トリガ信号を出力する。このトリガ信号は、ドライバ３２で受信される。ドライバ３２は、トリガ信号の受信タイミングに同期させて光源３を駆動する。 The trigger generation unit 36 determines the timing at which the light source 3 emits light, and outputs a trigger signal. This trigger signal is received by the driver 32. The driver 32 drives the light source 3 in synchronization with the reception timing of the trigger signal.
　図２１に示す受光装置１の制御系は光学系とともにチップ化され、あるいは光学系とは別にチップ化されて、図１の支持基板４に実装することができる。 The control system of the light receiving device 1 shown in FIG. 21 can be chipped together with the optical system or chipped separately from the optical system and mounted on the support substrate 4 of FIG.
　本開示に係る技術（本技術）は、様々な製品へ応用することができる。例えば、本開示に係る技術は、自動車、電気自動車、ハイブリッド電気自動車、自動二輪車、自転車、パーソナルモビリティ、飛行機、ドローン、船舶、ロボット等のいずれかの種類の移動体に搭載される装置として実現されてもよい。 The technology related to this disclosure (this technology) can be applied to various products. For example, the technology according to the present disclosure is realized as a device mounted on a moving body of any kind such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, a personal mobility, an airplane, a drone, a ship, and a robot. You may.
　図２２は、本開示に係る技術が適用され得る移動体制御システムの一例である車両制御システムの概略的な構成例を示すブロック図である。 FIG. 22 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile control system to which the technique according to the present disclosure can be applied.
　車両制御システム１２０００は、通信ネットワーク１２００１を介して接続された複数の電子制御ユニットを備える。図２２に示した例では、車両制御システム１２０００は、駆動系制御ユニット１２０１０、ボディ系制御ユニット１２０２０、車外情報検出ユニット１２０３０、車内情報検出ユニット１２０４０、及び統合制御ユニット１２０５０を備える。また、統合制御ユニット１２０５０の機能構成として、マイクロコンピュータ１２０５１、音声画像出力部１２０５２、及び車載ネットワークＩ／Ｆ（ｉｎｔｅｒｆａｃｅ）１２０５３が図示されている。 The vehicle control system 12000 includes a plurality of electronic control units connected via the communication network 12001. In the example shown in FIG. 22, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside information detection unit 12030, an in-vehicle information detection unit 12040, and an integrated control unit 12050. Further, as a functional configuration of the integrated control unit 12050, a microcomputer 12051, an audio image output unit 12052, and an in-vehicle network I / F (interface) 12053 are shown.
　駆動系制御ユニット１２０１０は、各種プログラムにしたがって車両の駆動系に関連する装置の動作を制御する。例えば、駆動系制御ユニット１２０１０は、内燃機関又は駆動用モータ等の車両の駆動力を発生させるための駆動力発生装置、駆動力を車輪に伝達するための駆動力伝達機構、車両の舵角を調節するステアリング機構、及び、車両の制動力を発生させる制動装置等の制御装置として機能する。 The drive system control unit 12010 controls the operation of the device related to the drive system of the vehicle according to various programs. For example, the drive system control unit 12010 provides a driving force generator for generating the driving force of the vehicle such as an internal combustion engine or a driving motor, a driving force transmission mechanism for transmitting the driving force to the wheels, and a steering angle of the vehicle. It functions as a control device such as a steering mechanism for adjusting and a braking device for generating a braking force of a vehicle.
　ボディ系制御ユニット１２０２０は、各種プログラムにしたがって車体に装備された各種装置の動作を制御する。例えば、ボディ系制御ユニット１２０２０は、キーレスエントリシステム、スマートキーシステム、パワーウィンドウ装置、あるいは、ヘッドランプ、バックランプ、ブレーキランプ、ウィンカー又はフォグランプ等の各種ランプの制御装置として機能する。この場合、ボディ系制御ユニット１２０２０には、鍵を代替する携帯機から発信される電波又は各種スイッチの信号が入力され得る。ボディ系制御ユニット１２０２０は、これらの電波又は信号の入力を受け付け、車両のドアロック装置、パワーウィンドウ装置、ランプ等を制御する。 The body system control unit 12020 controls the operation of various devices mounted on the vehicle body according to various programs. For example, the body system control unit 12020 functions as a keyless entry system, a smart key system, a power window device, or a control device for various lamps such as headlamps, back lamps, brake lamps, blinkers or fog lamps. In this case, the body system control unit 12020 may be input with radio waves transmitted from a portable device that substitutes for the key or signals of various switches. The body system control unit 12020 receives inputs of these radio waves or signals and controls a vehicle door lock device, a power window device, a lamp, and the like.
　車外情報検出ユニット１２０３０は、車両制御システム１２０００を搭載した車両の外部の情報を検出する。例えば、車外情報検出ユニット１２０３０には、撮像部１２０３１が接続される。車外情報検出ユニット１２０３０は、撮像部１２０３１に車外の画像を撮像させるとともに、撮像された画像を受信する。車外情報検出ユニット１２０３０は、受信した画像に基づいて、人、車、障害物、標識又は路面上の文字等の物体検出処理又は距離検出処理を行ってもよい。 The vehicle outside information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, the image pickup unit 12031 is connected to the vehicle exterior information detection unit 12030. The vehicle outside information detection unit 12030 causes the image pickup unit 12031 to capture an image of the outside of the vehicle and receives the captured image. The vehicle exterior information detection unit 12030 may perform object detection processing or distance detection processing such as a person, a vehicle, an obstacle, a sign, or a character on the road surface based on the received image.
　撮像部１２０３１は、光を受光し、その光の受光量に応じた電気信号を出力する光センサである。撮像部１２０３１は、電気信号を画像として出力することもできるし、測距の情報として出力することもできる。また、撮像部１２０３１が受光する光は、可視光であっても良いし、赤外線等の非可視光であっても良い。 The imaging unit 12031 is an optical sensor that receives light and outputs an electric signal according to the amount of the light received. The image pickup unit 12031 can output an electric signal as an image or can output it as distance measurement information. Further, the light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.
　車内情報検出ユニット１２０４０は、車内の情報を検出する。車内情報検出ユニット１２０４０には、例えば、運転者の状態を検出する運転者状態検出部１２０４１が接続される。運転者状態検出部１２０４１は、例えば運転者を撮像するカメラを含み、車内情報検出ユニット１２０４０は、運転者状態検出部１２０４１から入力される検出情報に基づいて、運転者の疲労度合い又は集中度合いを算出してもよいし、運転者が居眠りをしていないかを判別してもよい。 The in-vehicle information detection unit 12040 detects the in-vehicle information. For example, a driver state detection unit 12041 that detects the driver's state is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that images the driver, and the in-vehicle information detection unit 12040 determines the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041. It may be calculated, or it may be determined whether or not the driver has fallen asleep.
　マイクロコンピュータ１２０５１は、車外情報検出ユニット１２０３０又は車内情報検出ユニット１２０４０で取得される車内外の情報に基づいて、駆動力発生装置、ステアリング機構又は制動装置の制御目標値を演算し、駆動系制御ユニット１２０１０に対して制御指令を出力することができる。例えば、マイクロコンピュータ１２０５１は、車両の衝突回避あるいは衝撃緩和、車間距離に基づく追従走行、車速維持走行、車両の衝突警告、又は車両のレーン逸脱警告等を含むＡＤＡＳ（Ａｄｖａｎｃｅｄ　Ｄｒｉｖｅｒ　Ａｓｓｉｓｔａｎｃｅ　Ｓｙｓｔｅｍ）の機能実現を目的とした協調制御を行うことができる。 The microcomputer 12051 calculates the control target value of the driving force generator, the steering mechanism, or the braking device based on the information inside and outside the vehicle acquired by the vehicle exterior information detection unit 12030 or the vehicle interior information detection unit 12040, and the drive system control unit. A control command can be output to 12010. For example, the microcomputer 12051 realizes ADAS (Advanced Driver Assistance System) functions including vehicle collision avoidance or impact mitigation, follow-up driving based on inter-vehicle distance, vehicle speed maintenance driving, vehicle collision warning, vehicle lane deviation warning, and the like. It is possible to perform cooperative control for the purpose of.
　また、マイクロコンピュータ１２０５１は、車外情報検出ユニット１２０３０又は車内情報検出ユニット１２０４０で取得される車両の周囲の情報に基づいて駆動力発生装置、ステアリング機構又は制動装置等を制御することにより、運転者の操作に拠らずに自律的に走行する自動運転等を目的とした協調制御を行うことができる。 Further, the microcomputer 12051 controls the driving force generator, the steering mechanism, the braking device, and the like based on the information around the vehicle acquired by the vehicle exterior information detection unit 12030 or the vehicle interior information detection unit 12040. It is possible to perform coordinated control for the purpose of automatic driving, etc., which runs autonomously without depending on the operation.
　また、マイクロコンピュータ１２０５１は、車外情報検出ユニット１２０３０で取得される車外の情報に基づいて、ボディ系制御ユニット１２０２０に対して制御指令を出力することができる。例えば、マイクロコンピュータ１２０５１は、車外情報検出ユニット１２０３０で検知した先行車又は対向車の位置に応じてヘッドランプを制御し、ハイビームをロービームに切り替える等の防眩を図ることを目的とした協調制御を行うことができる。 Further, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle acquired by the vehicle exterior information detection unit 12030. For example, the microcomputer 12051 controls the headlamps according to the position of the preceding vehicle or the oncoming vehicle detected by the external information detection unit 12030, and performs coordinated control for the purpose of anti-glare such as switching the high beam to the low beam. It can be carried out.
　音声画像出力部１２０５２は、車両の搭乗者又は車外に対して、視覚的又は聴覚的に情報を通知することが可能な出力装置へ音声及び画像のうちの少なくとも一方の出力信号を送信する。図２２の例では、出力装置として、オーディオスピーカ１２０６１、表示部１２０６２及びインストルメントパネル１２０６３が例示されている。表示部１２０６２は、例えば、オンボードディスプレイ及びヘッドアップディスプレイの少なくとも一つを含んでいてもよい。 The audio image output unit 12052 transmits an output signal of at least one of audio and an image to an output device capable of visually or audibly notifying information to the passenger or the outside of the vehicle. In the example of FIG. 22, an audio speaker 12061, a display unit 12062, and an instrument panel 12063 are exemplified as output devices. The display unit 12062 may include, for example, at least one of an onboard display and a heads-up display.
　図２３は、撮像部１２０３１の設置位置の例を示す図である。 FIG. 23 is a diagram showing an example of the installation position of the imaging unit 12031.
　図２３では、車両１２１００は、撮像部１２０３１として、撮像部１２１０１，１２１０２，１２１０３，１２１０４，１２１０５を有する。 In FIG. 23, the vehicle 12100 has image pickup units 12101, 12102, 12103, 12104, 12105 as the image pickup unit 12031.
　撮像部１２１０１，１２１０２，１２１０３，１２１０４，１２１０５は、例えば、車両１２１００のフロントノーズ、サイドミラー、リアバンパ、バックドア及び車室内のフロントガラスの上部等の位置に設けられる。フロントノーズに備えられる撮像部１２１０１及び車室内のフロントガラスの上部に備えられる撮像部１２１０５は、主として車両１２１００の前方の画像を取得する。サイドミラーに備えられる撮像部１２１０２，１２１０３は、主として車両１２１００の側方の画像を取得する。リアバンパ又はバックドアに備えられる撮像部１２１０４は、主として車両１２１００の後方の画像を取得する。撮像部１２１０１及び１２１０５で取得される前方の画像は、主として先行車両又は、歩行者、障害物、信号機、交通標識又は車線等の検出に用いられる。 The imaging units 12101, 12102, 12103, 12104, 12105 are provided at positions such as the front nose, side mirrors, rear bumpers, back doors, and the upper part of the windshield in the vehicle interior of the vehicle 12100, for example. The imaging unit 12101 provided on the front nose and the imaging unit 12105 provided on the upper part of the windshield in the vehicle interior mainly acquire an image in front of the vehicle 12100. The imaging units 12102 and 12103 provided in the side mirrors mainly acquire images of the side of the vehicle 12100. The imaging unit 12104 provided on the rear bumper or the back door mainly acquires an image of the rear of the vehicle 12100. The images in front acquired by the imaging units 12101 and 12105 are mainly used for detecting a preceding vehicle or a pedestrian, an obstacle, a traffic light, a traffic sign, a lane, or the like.
　なお、図２３には、撮像部１２１０１ないし１２１０４の撮影範囲の一例が示されている。撮像範囲１２１１１は、フロントノーズに設けられた撮像部１２１０１の撮像範囲を示し、撮像範囲１２１１２，１２１１３は、それぞれサイドミラーに設けられた撮像部１２１０２，１２１０３の撮像範囲を示し、撮像範囲１２１１４は、リアバンパ又はバックドアに設けられた撮像部１２１０４の撮像範囲を示す。例えば、撮像部１２１０１ないし１２１０４で撮像された画像データが重ね合わせられることにより、車両１２１００を上方から見た俯瞰画像が得られる。 Note that FIG. 23 shows an example of the photographing range of the imaging units 12101 to 12104. The imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose, the imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively, and the imaging range 12114 indicates the imaging range of the imaging units 12102 and 12103. The imaging range of the imaging unit 12104 provided on the rear bumper or the back door is shown. For example, by superimposing the image data captured by the imaging units 12101 to 12104, a bird's-eye view image of the vehicle 12100 as viewed from above can be obtained.
　撮像部１２１０１ないし１２１０４の少なくとも１つは、距離情報を取得する機能を有していてもよい。例えば、撮像部１２１０１ないし１２１０４の少なくとも１つは、複数の撮像素子からなるステレオカメラであってもよいし、位相差検出用の画素を有する撮像素子であってもよい。 At least one of the imaging units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the image pickup units 12101 to 12104 may be a stereo camera composed of a plurality of image pickup elements, or may be an image pickup element having pixels for phase difference detection.
　例えば、マイクロコンピュータ１２０５１は、撮像部１２１０１ないし１２１０４から得られた距離情報を基に、撮像範囲１２１１１ないし１２１１４内における各立体物までの距離と、この距離の時間的変化（車両１２１００に対する相対速度）を求めることにより、特に車両１２１００の進行路上にある最も近い立体物で、車両１２１００と略同じ方向に所定の速度（例えば、０ｋｍ／ｈ以上）で走行する立体物を先行車として抽出することができる。さらに、マイクロコンピュータ１２０５１は、先行車の手前に予め確保すべき車間距離を設定し、自動ブレーキ制御（追従停止制御も含む）や自動加速制御（追従発進制御も含む）等を行うことができる。このように運転者の操作に拠らずに自律的に走行する自動運転等を目的とした協調制御を行うことができる。 For example, the microcomputer 12051 uses the distance information obtained from the imaging units 12101 to 12104 to obtain the distance to each three-dimensional object within the imaging range 12111 to 12114 and the temporal change of this distance (relative velocity with respect to the vehicle 12100). By obtaining, it is possible to extract as the preceding vehicle a three-dimensional object that is the closest three-dimensional object on the traveling path of the vehicle 12100 and that travels in substantially the same direction as the vehicle 12100 at a predetermined speed (for example, 0 km / h or more). can. Further, the microcomputer 12051 can set an inter-vehicle distance to be secured in front of the preceding vehicle in advance, and can perform automatic braking control (including follow-up stop control), automatic acceleration control (including follow-up start control), and the like. In this way, it is possible to perform coordinated control for the purpose of automatic driving or the like in which the vehicle travels autonomously without depending on the operation of the driver.
　例えば、マイクロコンピュータ１２０５１は、撮像部１２１０１ないし１２１０４から得られた距離情報を元に、立体物に関する立体物データを、２輪車、普通車両、大型車両、歩行者、電柱等その他の立体物に分類して抽出し、障害物の自動回避に用いることができる。例えば、マイクロコンピュータ１２０５１は、車両１２１００の周辺の障害物を、車両１２１００のドライバが視認可能な障害物と視認困難な障害物とに識別する。そして、マイクロコンピュータ１２０５１は、各障害物との衝突の危険度を示す衝突リスクを判断し、衝突リスクが設定値以上で衝突可能性がある状況であるときには、オーディオスピーカ１２０６１や表示部１２０６２を介してドライバに警報を出力することや、駆動系制御ユニット１２０１０を介して強制減速や回避操舵を行うことで、衝突回避のための運転支援を行うことができる。 For example, the microcomputer 12051 converts three-dimensional object data related to a three-dimensional object into two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on the distance information obtained from the imaging units 12101 to 12104. It can be classified and extracted and used for automatic avoidance of obstacles. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into obstacles that can be seen by the driver of the vehicle 12100 and obstacles that are difficult to see. Then, the microcomputer 12051 determines the collision risk indicating the risk of collision with each obstacle, and when the collision risk is equal to or higher than the set value and there is a possibility of collision, the microcomputer 12051 is used via the audio speaker 12061 or the display unit 12062. By outputting an alarm to the driver and performing forced deceleration and avoidance steering via the drive system control unit 12010, driving support for collision avoidance can be provided.
　撮像部１２１０１ないし１２１０４の少なくとも１つは、赤外線を検出する赤外線カメラであってもよい。例えば、マイクロコンピュータ１２０５１は、撮像部１２１０１ないし１２１０４の撮像画像中に歩行者が存在するか否かを判定することで歩行者を認識することができる。かかる歩行者の認識は、例えば赤外線カメラとしての撮像部１２１０１ないし１２１０４の撮像画像における特徴点を抽出する手順と、物体の輪郭を示す一連の特徴点にパターンマッチング処理を行って歩行者か否かを判別する手順によって行われる。マイクロコンピュータ１２０５１が、撮像部１２１０１ないし１２１０４の撮像画像中に歩行者が存在すると判定し、歩行者を認識すると、音声画像出力部１２０５２は、当該認識された歩行者に強調のための方形輪郭線を重畳表示するように、表示部１２０６２を制御する。また、音声画像出力部１２０５２は、歩行者を示すアイコン等を所望の位置に表示するように表示部１２０６２を制御してもよい。 At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether or not a pedestrian is present in the captured image of the imaging units 12101 to 12104. Such pedestrian recognition includes, for example, a procedure for extracting feature points in an image captured by an imaging unit 12101 to 12104 as an infrared camera, and pattern matching processing for a series of feature points indicating the outline of an object to determine whether or not the pedestrian is a pedestrian. It is done by the procedure to determine. When the microcomputer 12051 determines that a pedestrian is present in the captured images of the imaging units 12101 to 12104 and recognizes the pedestrian, the audio image output unit 12052 outputs a square contour line for emphasizing the recognized pedestrian. The display unit 12062 is controlled so as to superimpose and display. Further, the audio image output unit 12052 may control the display unit 12062 so as to display an icon or the like indicating a pedestrian at a desired position.
　以上、本開示に係る技術が適用され得る車両制御システムの一例について説明した。本開示に係る技術は、以上説明した構成のうち、例えば、撮像部１２０３１に適用され得る。具体的には、撮像部１２０３１に、上述の受光回路、受光装置または測距装置を実装することができる。撮像部１２０３１に、本開示に係る技術を適用することにより、広いＦＯＶ（視野）において、正確な距離情報を得ることができ、車両１２１００の機能性および安全性を高めることができる。 The above is an example of a vehicle control system to which the technology according to the present disclosure can be applied. The technique according to the present disclosure can be applied to, for example, the imaging unit 12031 among the configurations described above. Specifically, the above-mentioned light receiving circuit, light receiving device, or distance measuring device can be mounted on the imaging unit 12031. By applying the technique according to the present disclosure to the imaging unit 12031, accurate distance information can be obtained in a wide FOV (field of view), and the functionality and safety of the vehicle 12100 can be enhanced.
　なお、本技術は以下のような構成を取ることができる。
　（１）フレネル面を有するテレセントリック光学系と、
　前記テレセントリック光学系を通過した光の中から、所定の波長帯域の光を透過させるフィルタと、
　前記フィルタを通過した光を光電変換する撮像部と、を備える、受光装置。
　（２）前記テレセントリック光学系は、
　入射する周辺光束の主光線を発散させる前群光学系と、
　前記前群光学系を通過した周辺光束の主光線を平行化する後群光学系と、を有し、
　前記後群光学系は、前記フレネル面を有する、（１）に記載の受光装置。
　（３）前記後群光学系は、前記前群光学系に対向配置される第１面と、前記フィルタに対向配置される第２面と、を有し、
　前記第２面はフレネル面である、（２）に記載の受光装置。
　（４）前記第１面の湾曲度合いは、前記第２面の湾曲度合いよりも大きい、（３）に記載の受光装置。
　（５）前記後群光学系は、光軸中心から周縁に向かうに従って、厚みが薄くなるレンズを有する、（２）乃至（４）のいずれか一項に記載の受光装置。
　（６）前記後群光学系は、厚みが均一な透明基材を有し、
　前記透明基材は、前記前群光学系側に配置される第３面と、前記撮像部側に配置される第４面と、を有し、
　前記第３面はフレネル面であり、
　前記フィルタは、前記第４面にコーティングされた層である、（２）に記載の受光装置。
　（７）前記テレセントリック光学系には、光源から発光されて対象物で反射された反射光が入射され、
　前記フィルタは、前記フィルタの法線方向から所定角度傾斜した方向から光が入射された場合に透過率が５０％になる上限の波長をＷcut_on、前記フィルタの法線方向から光が入射された場合に透過率が５０％になる下限の波長をＷcut_off、前記光源の初期波長ばらつき及び温度変化による前記光源の発光波長の変化量をＷldとしたとき、Ｗcut_on－Ｗcut_off＞Ｗldを満たす透過特性を有する、（１）乃至（６）のいずれか一項に記載の受光装置。
　（８）前記テレセントリック光学系は、外形が矩形状でフレネル面を有するガラス基材を有する、（１）乃至（７）のいずれか一項に記載の受光装置。
　（９）前記テレセントリック光学系は、外形が矩形状でフレネル面を有する樹脂基材を有する、（１）乃至（７）のいずれか一項に記載の受光装置。
　（１０）前記テレセントリック光学系は、凸形状の前記樹脂基材と、前記樹脂基材に接合される平坦なガラス基材とを有し、
　前記フィルタは、前記ガラス基材の表面にコーティングされた層である、（９）に記載の受光装置。
　（１１）前記テレセントリック光学系には、光源から発光されて対象物で反射された反射光が入射され、
　前記受光装置は、前記光源が光を発光したタイミングと、前記受光装置が前記反射光を受光したタイミングとの時間差により、前記対象物までの距離を計測する距離計測部を有する、（１）乃至（１０）のいずれか一項に記載の受光装置。
　（１２）光を発光する光源と、
　前記光源で発光されて対象物で反射された反射光を受光する受光装置と、
　前記光源と前記受光装置とを支持する支持基板と、を備えた電子システムであって、
　前記受光装置は、
　フレネル面を有するテレセントリック光学系と、
　前記テレセントリック光学系を通過した光の中から、所定の波長帯域の光を透過させるフィルタと、
　前記フィルタを通過した光を光電変換する撮像部と、を有する、電子システム。
　（１３）前記受光装置は、前記光源が光を発光したタイミングと、前記受光装置が前記反射光を受光したタイミングとの時間差により、前記対象物までの距離を計測する距離計測部を有する、（１２）に記載の電子システム。
　（１４）前記テレセントリック光学系は、
　入射する周辺光束の主光線を発散させる前群光学系と、
　前記前群光学系を通過した周辺光束の主光線を平行化する後群光学系と、を有し、
　前記後群光学系は、前記フレネル面を有する、（１２）に記載の電子システム。
　（１５）前記後群光学系は、前記前群光学系に対向配置される第１面と、前記フィルタに対向配置される第２面と、を有し、
　前記第２面はフレネル面である、（１４）に記載の電子システム。
　（１６）前記第１面の湾曲度合いは、前記第２面の湾曲度合いよりも大きい、（１５）に記載の電子システム。
　（１７）前記後群光学系は、光軸中心から周縁に向かうに従って、厚みが薄くなるレンズを有する、（１４）乃至（１６）のいずれか一項に記載の電子システム。
　（１８）前記後群光学系は、厚みが均一な透明基材を有し、
　前記透明基材は、前記前群光学系側に配置される第３面と、前記撮像部側に配置される第４面と、を有し、
　前記第３面はフレネル面であり、
　前記フィルタは、前記第４面にコーティングされた層である、（１４）に記載の電子システム。
　（１９）前記テレセントリック光学系には、光源から発光されて対象物で反射された反射光が入射され、
　前記フィルタは、前記フィルタの法線方向から所定角度傾斜した方向から光が入射された場合に透過率が５０％になる上限の波長をＷcut_on、前記フィルタの法線方向から光が入射された場合に透過率が５０％になる下限の波長をＷcut_off、前記光源の初期波長ばらつき及び温度変化による前記光源の発光波長の変化量をＷldとしたとき、Ｗcut_on－Ｗcut_off＞Ｗldを満たす透過特性を有する、（１２）乃至（１８）のいずれか一項に記載の電子システム。
　（２０）前記テレセントリック光学系は、外形が矩形状でフレネル面を有するガラス基材を有する、請求項１２乃至１９のいずれか一項に記載の電子システム。 The present technology can have the following configurations.
(1) A telecentric optical system with a Fresnel surface and
A filter that transmits light in a predetermined wavelength band from the light that has passed through the telecentric optical system,
A light receiving device including an imaging unit that photoelectrically converts light that has passed through the filter.
(2) The telecentric optical system is
The front group optical system that diverges the main ray of the incident peripheral luminous flux,
It has a rear group optical system that parallelizes the main light beam of the peripheral luminous flux that has passed through the front group optical system.
The light receiving device according to (1), wherein the rear group optical system has the Fresnel surface.
(3) The rear group optical system has a first surface which is arranged to face the front group optical system and a second surface which is arranged to face the filter.
The light receiving device according to (2), wherein the second surface is a Fresnel surface.
(4) The light receiving device according to (3), wherein the degree of curvature of the first surface is larger than the degree of curvature of the second surface.
(5) The light receiving device according to any one of (2) to (4), wherein the rear group optical system has a lens whose thickness decreases from the center of the optical axis toward the peripheral edge.
(6) The rear group optical system has a transparent base material having a uniform thickness.
The transparent base material has a third surface arranged on the front group optical system side and a fourth surface arranged on the imaging unit side.
The third surface is a Fresnel surface,
The light receiving device according to (2), wherein the filter is a layer coated on the fourth surface.
(7) The telecentric optical system is incident with the reflected light emitted from the light source and reflected by the object.
The filter has Wcut_on as the upper limit wavelength at which the transmittance becomes 50% when light is incident from a direction inclined by a predetermined angle from the normal direction of the filter, and when light is incident from the normal direction of the filter. When the lower limit wavelength at which the transmittance becomes 50% is Wcut_off and the amount of change in the emission wavelength of the light source due to the initial wavelength variation of the light source and the temperature change is Wld, the transmittance has a transmission characteristic satisfying Wcut_on-Wcut_off> Wld. The light receiving device according to any one of (1) to (6).
(8) The light receiving device according to any one of (1) to (7), wherein the telecentric optical system has a glass base material having a rectangular outer shape and a Fresnel surface.
(9) The light receiving device according to any one of (1) to (7), wherein the telecentric optical system has a resin base material having a rectangular outer shape and a Fresnel surface.
(10) The telecentric optical system has a convex resin base material and a flat glass base material bonded to the resin base material.
The light receiving device according to (9), wherein the filter is a layer coated on the surface of the glass substrate.
(11) The telecentric optical system is incident with the reflected light emitted from the light source and reflected by the object.
The light receiving device has a distance measuring unit that measures the distance to the object by the time difference between the timing when the light source emits light and the timing when the light receiving device receives the reflected light (1) to. The light receiving device according to any one of (10).
(12) A light source that emits light and
A light receiving device that receives the reflected light that is emitted by the light source and reflected by the object.
An electronic system including a support substrate that supports the light source and the light receiving device.
The light receiving device is
Telecentric optics with Fresnel surface and
A filter that transmits light in a predetermined wavelength band from the light that has passed through the telecentric optical system,
An electronic system comprising an imaging unit that photoelectrically converts light that has passed through the filter.
(13) The light receiving device has a distance measuring unit that measures the distance to the object by the time difference between the timing when the light source emits light and the timing when the light receiving device receives the reflected light. 12) The electronic system according to.
(14) The telecentric optical system is
The front group optical system that diverges the main ray of the incident peripheral luminous flux,
It has a rear group optical system that parallelizes the main light beam of the peripheral luminous flux that has passed through the front group optical system.
The electronic system according to (12), wherein the rear group optical system has the Fresnel surface.
(15) The rear group optical system has a first surface which is arranged to face the front group optical system and a second surface which is arranged to face the filter.
The electronic system according to (14), wherein the second surface is a Fresnel surface.
(16) The electronic system according to (15), wherein the degree of curvature of the first surface is larger than the degree of curvature of the second surface.
(17) The electronic system according to any one of (14) to (16), wherein the rear group optical system has a lens whose thickness decreases from the center of the optical axis toward the peripheral edge.
(18) The rear group optical system has a transparent base material having a uniform thickness.
The transparent base material has a third surface arranged on the front group optical system side and a fourth surface arranged on the imaging unit side.
The third surface is a Fresnel surface,
The electronic system according to (14), wherein the filter is a layer coated on the fourth surface.
(19) The telecentric optical system is incident with the reflected light emitted from the light source and reflected by the object.
The filter has Wcut_on as the upper limit wavelength at which the transmittance becomes 50% when light is incident from a direction inclined by a predetermined angle from the normal direction of the filter, and when light is incident from the normal direction of the filter. When the lower limit wavelength at which the transmittance becomes 50% is Wcut_off and the amount of change in the emission wavelength of the light source due to the initial wavelength variation of the light source and the temperature change is Wld, the transmittance has a transmission characteristic satisfying Wcut_on-Wcut_off> Wld. The electronic system according to any one of (12) to (18).
(20) The electronic system according to any one of claims 12 to 19, wherein the telecentric optical system has a glass substrate having a rectangular outer shape and a Fresnel surface.
　本開示の態様は、上述した個々の実施形態に限定されるものではなく、当業者が想到しうる種々の変形も含むものであり、本開示の効果も上述した内容に限定されない。すなわち、特許請求の範囲に規定された内容およびその均等物から導き出される本開示の概念的な思想と趣旨を逸脱しない範囲で種々の追加、変更および部分的削除が可能である。 The aspects of the present disclosure are not limited to the individual embodiments described above, but also include various modifications that can be conceived by those skilled in the art, and the effects of the present disclosure are not limited to the above-mentioned contents. That is, various additions, changes and partial deletions are possible without departing from the conceptual idea and purpose of the present disclosure derived from the contents defined in the claims and their equivalents.
　１　受光装置、２　電子システム、３　光源、４　支持基板、１１、１１ａ、１１ｂ　テレセントリック光学系、１２　バンドパスフィルタ、１３　撮像部、１４　フレネル面、２０　光軸、２１、２１ａ、２１ｂ　前群光学系、２２、２２ａ、２２ｂ　後群光学系、２３　レンズ、２３ａ　コーティング層、２５　光学系、２６　光学系、２２０　ガラス基材、２２１　樹脂基材、３１　発光素子、３２　ドライバ、３３　受光部、３４　ＴＤＣ、３５　演算部、３６　トリガ生成部、３７　制御部、３８　インタフェース部、３９　ＳＰＡＤアレイ、４０　読み出し回路、 1 light receiving device, 2 electronic system, 3 light source, 4 support substrate, 11, 11a, 11b telecentric optical system, 12 bandpass filter, 13 imaging unit, 14 Frenel surface, 20 optical axis, 21, 21a, 21b front group optical system , 22, 22a, 22b rear group optical system, 23 lens, 23a coating layer, 25 optical system, 26 optical system, 220 glass base material, 221 resin base material, 31 light emitting element, 32 driver, 33 light receiving part, 34 TDC, 35 arithmetic unit, 36 trigger generation unit, 37 control unit, 38 interface unit, 39 SPAD array, 40 read circuit,

Claims (20)

  1. 　フレネル面を有するテレセントリック光学系と、
    　前記テレセントリック光学系を通過した光の中から、所定の波長帯域の光を透過させるフィルタと、
    　前記フィルタを通過した光を光電変換する撮像部と、を備える、受光装置。     Telecentric optics with Fresnel surface and
    A filter that transmits light in a predetermined wavelength band from the light that has passed through the telecentric optical system,
    A light receiving device including an imaging unit that photoelectrically converts light that has passed through the filter.
  2. 　前記テレセントリック光学系は、
    　入射する周辺光束の主光線を発散させる前群光学系と、
    　前記前群光学系を通過した周辺光束の主光線を平行化する後群光学系と、を有し、
    　前記後群光学系は、前記フレネル面を有する、請求項１に記載の受光装置。     The telecentric optical system is
    The front group optical system that diverges the main ray of the incident peripheral luminous flux,
    It has a rear group optical system that parallelizes the main light beam of the peripheral luminous flux that has passed through the front group optical system.
    The light receiving device according to claim 1, wherein the rear group optical system has the Fresnel surface.
  3. 　前記後群光学系は、前記前群光学系に対向配置される第１面と、前記フィルタに対向配置される第２面と、を有し、
    　前記第２面はフレネル面である、請求項２に記載の受光装置。     The rear group optical system has a first surface which is arranged to face the front group optical system and a second surface which is arranged to face the filter.
    The light receiving device according to claim 2, wherein the second surface is a Fresnel surface.
  4. 　前記第１面の湾曲度合いは、前記第２面の湾曲度合いよりも大きい、請求項３に記載の受光装置。 The light receiving device according to claim 3, wherein the degree of curvature of the first surface is larger than the degree of curvature of the second surface.
  5. 　前記後群光学系は、光軸中心から周縁に向かうに従って、厚みが薄くなるレンズを有する、請求項２に記載の受光装置。 The light receiving device according to claim 2, wherein the rear group optical system has a lens whose thickness decreases from the center of the optical axis toward the periphery.
  6. 　前記後群光学系は、厚みが均一な透明基材を有し、
    　前記透明基材は、前記前群光学系側に配置される第３面と、前記撮像部側に配置される第４面と、を有し、
    　前記第３面はフレネル面であり、
    　前記フィルタは、前記第４面にコーティングされた層である、請求項２に記載の受光装置。     The rear group optical system has a transparent base material having a uniform thickness and has a uniform thickness.
    The transparent base material has a third surface arranged on the front group optical system side and a fourth surface arranged on the imaging unit side.
    The third surface is a Fresnel surface,
    The light receiving device according to claim 2, wherein the filter is a layer coated on the fourth surface.
  7. 　前記テレセントリック光学系には、光源から発光されて対象物で反射された反射光が入射され、
    　前記フィルタは、前記フィルタの法線方向から所定角度傾斜した方向から光が入射された場合に透過率が５０％になる上限の波長をＷcut_on、前記フィルタの法線方向から光が入射された場合に透過率が５０％になる下限の波長をＷcut_off、前記光源の初期波長ばらつき及び温度変化による前記光源の発光波長の変化量をＷldとしたとき、Ｗcut_on－Ｗcut_off＞Ｗldを満たす透過特性を有する、請求項１に記載の受光装置。     The telecentric optical system is incident with the reflected light emitted from the light source and reflected by the object.
    The filter has Wcut_on as the upper limit wavelength at which the transmittance becomes 50% when light is incident from a direction inclined by a predetermined angle from the normal direction of the filter, and when light is incident from the normal direction of the filter. When the lower limit wavelength at which the transmittance becomes 50% is Wcut_off and the amount of change in the emission wavelength of the light source due to the initial wavelength variation of the light source and the temperature change is Wld, the transmittance has a transmission characteristic satisfying Wcut_on-Wcut_off> Wld. The light receiving device according to claim 1.
  8. 　前記テレセントリック光学系は、外形が矩形状でフレネル面を有するガラス基材を有する、請求項１に記載の受光装置。 The light receiving device according to claim 1, wherein the telecentric optical system has a glass base material having a rectangular outer shape and a Fresnel surface.
  9. 　前記テレセントリック光学系は、外形が矩形状でフレネル面を有する樹脂基材を有する、請求項１に記載の受光装置。 The light receiving device according to claim 1, wherein the telecentric optical system has a resin base material having a rectangular outer shape and a Fresnel surface.
  10. 　前記テレセントリック光学系は、凸形状の前記樹脂基材と、前記樹脂基材に接合される平坦なガラス基材とを有し、
    　前記フィルタは、前記ガラス基材の表面にコーティングされた層である、請求項９に記載の受光装置。     The telecentric optical system has a convex resin base material and a flat glass base material bonded to the resin base material.
    The light receiving device according to claim 9, wherein the filter is a layer coated on the surface of the glass substrate.
  11. 　前記テレセントリック光学系には、光源から発光されて対象物で反射された反射光が入射され、
    　前記受光装置は、前記光源が光を発光したタイミングと、前記受光装置が前記反射光を受光したタイミングとの時間差により、前記対象物までの距離を計測する距離計測部を有する、請求項１に記載の受光装置。     The telecentric optical system is incident with the reflected light emitted from the light source and reflected by the object.
    The light receiving device has a distance measuring unit that measures the distance to the object by the time difference between the timing when the light source emits light and the timing when the light receiving device receives the reflected light. The light receiving device according to the description.
  12. 　光を発光する光源と、
    　前記光源で発光されて対象物で反射された反射光を受光する受光装置と、
    　前記光源と前記受光装置とを支持する支持基板と、を備えた電子システムであって、
    　前記受光装置は、
    　フレネル面を有するテレセントリック光学系と、
    　前記テレセントリック光学系を通過した光の中から、所定の波長帯域の光を透過させるフィルタと、
    　前記フィルタを通過した光を光電変換する撮像部と、を有する、電子システム。     A light source that emits light and
    A light receiving device that receives the reflected light that is emitted by the light source and reflected by the object.
    An electronic system including a support substrate that supports the light source and the light receiving device.
    The light receiving device is
    Telecentric optics with Fresnel surface and
    A filter that transmits light in a predetermined wavelength band from the light that has passed through the telecentric optical system,
    An electronic system comprising an imaging unit that photoelectrically converts light that has passed through the filter.
  13. 　前記受光装置は、前記光源が光を発光したタイミングと、前記受光装置が前記反射光を受光したタイミングとの時間差により、前記対象物までの距離を計測する距離計測部を有する、請求項１２に記載の電子システム。 12. The light receiving device has a distance measuring unit that measures the distance to the object by the time difference between the timing when the light source emits light and the timing when the light receiving device receives the reflected light. The electronic system described.
  14. 　前記テレセントリック光学系は、
    　入射する周辺光束の主光線を発散させる前群光学系と、
    　前記前群光学系を通過した周辺光束の主光線を平行化する後群光学系と、を有し、
    　前記後群光学系は、前記フレネル面を有する、請求項１２に記載の電子システム。     The telecentric optical system is
    The front group optical system that diverges the main ray of the incident peripheral luminous flux,
    It has a rear group optical system that parallelizes the main light beam of the peripheral luminous flux that has passed through the front group optical system.
    The electronic system according to claim 12, wherein the rear group optical system has the Fresnel surface.
  15. 　前記後群光学系は、前記前群光学系に対向配置される第１面と、前記フィルタに対向配置される第２面と、を有し、
    　前記第２面はフレネル面である、請求項１４に記載の電子システム。     The rear group optical system has a first surface which is arranged to face the front group optical system and a second surface which is arranged to face the filter.
    The electronic system according to claim 14, wherein the second surface is a Fresnel surface.
  16. 　前記第１面の湾曲度合いは、前記第２面の湾曲度合いよりも大きい、請求項１５に記載の電子システム。 The electronic system according to claim 15, wherein the degree of curvature of the first surface is larger than the degree of curvature of the second surface.
  17. 　前記後群光学系は、光軸中心から周縁に向かうに従って、厚みが薄くなるレンズを有する、請求項１４に記載の電子システム。 The electronic system according to claim 14, wherein the rear group optical system has a lens whose thickness decreases from the center of the optical axis toward the periphery.
  18. 　前記後群光学系は、厚みが均一な透明基材を有し、
    　前記透明基材は、前記前群光学系側に配置される第３面と、前記撮像部側に配置される第４面と、を有し、
    　前記第３面はフレネル面であり、
    　前記フィルタは、前記第４面にコーティングされた層である、請求項１４に記載の電子システム。     The rear group optical system has a transparent base material having a uniform thickness and has a uniform thickness.
    The transparent base material has a third surface arranged on the front group optical system side and a fourth surface arranged on the imaging unit side.
    The third surface is a Fresnel surface,
    The electronic system according to claim 14, wherein the filter is a layer coated on the fourth surface.
  19. 　前記テレセントリック光学系には、光源から発光されて対象物で反射された反射光が入射され、
    　前記フィルタは、前記フィルタの法線方向から所定角度傾斜した方向から光が入射された場合に透過率が５０％になる上限の波長をＷcut_on、前記フィルタの法線方向から光が入射された場合に透過率が５０％になる下限の波長をＷcut_off、前記光源の初期波長ばらつき及び温度変化による前記光源の発光波長の変化量をＷldとしたとき、Ｗcut_on－Ｗcut_off＞Ｗldを満たす透過特性を有する、請求項１２に記載の電子システム。     The telecentric optical system is incident with the reflected light emitted from the light source and reflected by the object.
    The filter has Wcut_on as the upper limit wavelength at which the transmittance becomes 50% when light is incident from a direction inclined by a predetermined angle from the normal direction of the filter, and when light is incident from the normal direction of the filter. When the lower limit wavelength at which the transmittance becomes 50% is Wcut_off and the amount of change in the emission wavelength of the light source due to the initial wavelength variation of the light source and the temperature change is Wld, the transmittance has a transmission characteristic satisfying Wcut_on-Wcut_off> Wld. The electronic system according to claim 12.
  20. 　前記テレセントリック光学系は、外形が矩形状でフレネル面を有するガラス基材を有する、請求項１２に記載の電子システム。 The electronic system according to claim 12, wherein the telecentric optical system has a glass base material having a rectangular outer shape and a Fresnel surface.
PCT/JP2021/000288 2020-01-14 2021-01-07 Light-receiving device and electronic system WO2021145261A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2020003556A JP2021110868A (en) 2020-01-14 2020-01-14 Light receiving device and electronic system
JP2020-003556 2020-01-14

Publications (1)

Publication Number Publication Date
WO2021145261A1 true WO2021145261A1 (en) 2021-07-22

Family

ID=76864393

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2021/000288 WO2021145261A1 (en) 2020-01-14 2021-01-07 Light-receiving device and electronic system

Country Status (2)

Country Link
JP (1) JP2021110868A (en)
WO (1) WO2021145261A1 (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06194571A (en) * 1992-12-25 1994-07-15 Olympus Optical Co Ltd Objective lens of endoscope
JPH10115777A (en) * 1996-10-11 1998-05-06 Olympus Optical Co Ltd Photographic lens
JP2000258686A (en) * 1999-03-08 2000-09-22 Nikon Corp Photographing lens system having high-resolution
US20130250039A1 (en) * 2012-03-20 2013-09-26 Microsoft Corporation Wide-angle depth imaging lens construction
JP2019144578A (en) * 2017-12-07 2019-08-29 日本板硝子株式会社 Optical filter and imaging device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06194571A (en) * 1992-12-25 1994-07-15 Olympus Optical Co Ltd Objective lens of endoscope
JPH10115777A (en) * 1996-10-11 1998-05-06 Olympus Optical Co Ltd Photographic lens
JP2000258686A (en) * 1999-03-08 2000-09-22 Nikon Corp Photographing lens system having high-resolution
US20130250039A1 (en) * 2012-03-20 2013-09-26 Microsoft Corporation Wide-angle depth imaging lens construction
JP2019144578A (en) * 2017-12-07 2019-08-29 日本板硝子株式会社 Optical filter and imaging device

Also Published As

Publication number Publication date
JP2021110868A (en) 2021-08-02

Similar Documents

Publication Publication Date Title
CN106488091B (en) Vehicle-mounted camera apparatus that captures image ahead of vehicle and performs vehicle control
CN107380056A (en) Vehicular illumination device and vehicle
KR101816572B1 (en) Camera apparatus for vehicle and vehicle
JP7445397B2 (en) Photodetector and electronic equipment
CN112612032A (en) Light detection device, method of detecting light, and distance measurement sensor
WO2021065494A1 (en) Distance measurement sensor, signal processing method, and distance measurement module
JP7494200B2 (en) Illumination device, method for controlling illumination device, and distance measuring module
WO2020184233A1 (en) Light source module, ranging device, and control method
WO2021145261A1 (en) Light-receiving device and electronic system
WO2021065495A1 (en) Ranging sensor, signal processing method, and ranging module
WO2021065500A1 (en) Distance measurement sensor, signal processing method, and distance measurement module
US11579369B2 (en) Optical communication connector, optical communication cable, and electronic device
WO2020189101A1 (en) Distance measurement device
WO2021161858A1 (en) Rangefinder and rangefinding method
WO2020189091A1 (en) Optical module and distance measurement device
CN115104056A (en) Lens optical system, light receiving device, and distance measuring system
JP7441796B2 (en) Optical module and ranging device
WO2024075409A1 (en) Photodetection device
WO2023218873A1 (en) Ranging device
WO2023238513A1 (en) Photodetector and photodetection device
WO2021131684A1 (en) Ranging device, method for controlling ranging device, and electronic apparatus
WO2023286403A1 (en) Light detection device and distance measurement system
WO2023181662A1 (en) Range-finding device and range-finding method
WO2021161857A1 (en) Distance measurement device and distance measurement method
US20230228875A1 (en) Solid-state imaging element, sensing system, and control method of solid-state imaging element

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 21741071

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 21741071

Country of ref document: EP

Kind code of ref document: A1