WO2017014317A1 - Projection device - Google Patents

Projection device Download PDF

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Publication number
WO2017014317A1
WO2017014317A1 PCT/JP2016/071624 JP2016071624W WO2017014317A1 WO 2017014317 A1 WO2017014317 A1 WO 2017014317A1 JP 2016071624 W JP2016071624 W JP 2016071624W WO 2017014317 A1 WO2017014317 A1 WO 2017014317A1
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WO
WIPO (PCT)
Prior art keywords
projection
optical system
lens group
optical path
imaging
Prior art date
Application number
PCT/JP2016/071624
Other languages
French (fr)
Japanese (ja)
Inventor
佐野永悟
Original Assignee
コニカミノルタ株式会社
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Publication date
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Publication of WO2017014317A1 publication Critical patent/WO2017014317A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/16—Optical objectives specially designed for the purposes specified below for use in conjunction with image converters or intensifiers, or for use with projectors, e.g. objectives for projection TV
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/18—Optical objectives specially designed for the purposes specified below with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B17/00—Systems with reflecting surfaces, with or without refracting elements
    • G02B17/08—Catadioptric systems
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B17/00—Details of cameras or camera bodies; Accessories therefor
    • G03B17/48—Details of cameras or camera bodies; Accessories therefor adapted for combination with other photographic or optical apparatus
    • G03B17/54—Details of cameras or camera bodies; Accessories therefor adapted for combination with other photographic or optical apparatus with projector
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/74—Projection arrangements for image reproduction, e.g. using eidophor

Definitions

  • the present invention relates to a projection apparatus capable of projecting and capturing an image, and more particularly to a projection apparatus capable of capturing a wide angle.
  • a projection apparatus that enlarges and projects an image displayed on an image display element onto a screen by a projection optical system is desired to have a wide-angle projection optical system that can be projected on a large screen even at a short projection distance while being small and light. Yes. Under such circumstances, short-focus projectors that can be arranged at positions close to the screen, such as directly below or directly above the screen, have appeared.
  • the projector can also project the PC screen onto a whiteboard or the like while writing handwritten characters on the screen and recording the information as an image with an imaging optical system.
  • projectors generally require various correction processes such as trapezoidal distortion correction of projected images and brightness correction according to the surrounding environment. If only trapezoidal distortion correction, brightness correction, or simple human motion detection is required, the imaging optical system needs only about VGA pixels, but handwritten characters are superimposed on the projected image, and the image data In order to capture the image, it is necessary to have a mega-class resolution, and it is desired that the imaging lens used for it has high performance.
  • an imaging optical system when an imaging optical system is to be incorporated in a short focus projector arranged at a position close to the screen as described above, the imaging lens needs to have a very wide angle. For this reason, it is difficult to ensure sufficient resolution at the periphery of the projection surface, and since distortion at the periphery is large, image processing such as distortion correction is performed on the captured image, resulting in resolution at the periphery. It will cause a decline. Therefore, there is a need for an optical system that suppresses as much as possible the barrel-shaped distortion that tends to occur in a wide-angle lens while having an ultra-wide angle.
  • the projection optical system can be used as it is as the imaging optical system
  • the apparatus itself can be downsized rather than mounting the imaging optical system separately from the projection optical system, and the resolution is high and the distortion is low. A photographed image can be obtained.
  • the imaging optical system has a wider angle of view than the projection optical system.
  • the optical system is exactly the same in the projection optical path and the imaging optical path, and therefore, when the image display element and the imaging element are the same size, the angle of view is For example, a character written outside the projected image cannot be captured.
  • the angle of view of the projection optical system is set wider than the projection range, and an imaging element having a larger area than the image display element is disposed. Therefore, problems such as an increase in the size and cost of the optical system and thus the apparatus arise.
  • the image display element and the image sensor are arranged at very close positions, there is a high risk that light from the illumination optical system incident on the image display element will be incident on the image sensor as stray light. It becomes a component and becomes a factor of deteriorating the captured image.
  • Patent Document 2 a projection optical system is commonly used by separating a projection-side optical path and an imaging-side optical path by a TIR prism disposed between an image display element and the projection optical system.
  • An optical system capable of obtaining an imaging means has been proposed.
  • An embodiment in which a magnification correction optical system is disposed between the TIR prism and the image sensor in order to make the projection field angle and the imaging field angle different is also disclosed.
  • magnification correction optical system since the optical path length in the TIR prism on the imaging side is longer than that on the projection side, a light beam forms an image once inside the TIR prism in the optical path on the imaging side. Therefore, although the details of the magnification correction optical system are not mentioned in the optical system of Patent Document 2, the magnification correction optical system needs to be a re-imaging relay optical system, and the degree of design difficulty is high. Will also increase.
  • JP 2003-44839 A Japanese Patent No. 5174273
  • An object of the present invention is to provide a small-sized projection device equipped with an imaging lens having an imaging field angle wider than the projection field angle and an ultra-wide angle.
  • a projection apparatus is a projection apparatus having a projection optical system that magnifies and projects an image obtained from an image display element illuminated by illumination light onto a projection plane.
  • An optical path separation element for separating the optical path is arranged at a position different from the optical path part of the illumination light inside the optical system, and the light from the projection surface is separated in a direction different from the optical path of the projection optical system by the optical path separation element.
  • An image sensor is disposed on the optical path, and lens groups having different refractive powers are disposed between the optical path separation element and the image display element, and between the optical path separation element and the image sensor, respectively, and are more than the projection field angle. Wide field of view.
  • an optical path separation element for separating an optical path is disposed inside the projection optical system, thereby projecting a part of the projection optical system (a lens group disposed on the projection plane side from the optical path separation element). Since it can be used in common for imaging, it is possible to reduce the number of parts compared to mounting the imaging optical system separately from the projection optical system, and as a result, it is possible to reduce the size of the projection apparatus. Further, by arranging the optical path separation element at a position different from the optical path portion of the illumination light, stray light caused by the illumination light can be suppressed, and a captured image with good image quality with reduced flare can be obtained.
  • the lens group between the image display element and the optical path separation element and between the optical path separation element and the imaging element, in the vicinity of the optical path separation element after emitting the optical path separation element on the imaging optical path. Since it is not necessary to use a re-imaging optical system for forming an image, the entire optical system can be simplified and reduced in size.
  • the imaging optical system can have a peripheral resolving power equivalent to that of the projection optical system and has little distortion. Further, by arranging lens groups having different refractive powers between the image display element and the optical path separation element and between the optical path separation element and the imaging element, respectively, the imaging field angle is made wider than the projection field angle, thereby projecting.
  • FIG. 1 is a cross-sectional view of an imaging optical system according to Example 1.
  • FIG. 5A and 5B are MTF characteristic diagrams showing performance on the projection surface of the projection optical system of Example 1.
  • FIG. 6A and 6B are MTF characteristic diagrams showing performance on the imaging surface of the imaging optical system of Example 1.
  • FIG. 7A and 7B are diagrams for explaining the MTF evaluation points on the projection plane or the imaging plane. 6 is a cross-sectional view of a projection optical system of Example 2.
  • FIG. 6 is a cross-sectional view of an imaging optical system according to Example 2.
  • FIG. 10A and 10B are MTF characteristic diagrams showing the performance of the projection optical system of Example 2 on the projection surface.
  • 11A and 11B are MTF characteristic diagrams showing performance on the imaging surface of the imaging optical system of Example 2.
  • FIG. 1 shows a projection apparatus incorporating a projection optical system according to an embodiment of the present invention
  • FIG. 2 shows a projection state by the projection optical system.
  • the projection apparatus 100 also enables imaging when projecting an image, and includes a projection optical system 10, an illumination optical system 20, a polarization beam splitter 30, a reflective liquid crystal element 40, an image drive circuit 41,
  • the imaging optical system 50, the imaging device 60, the parallel plate F2, the imaging drive circuit 61, the image processing unit 62, and the control circuit 80 are included.
  • the projection device 100 also has a function as an imaging device for a part of the configuration.
  • the projection apparatus 100 of the present embodiment is disposed directly below the projection body SB shown in FIG. 2, that is, the projection plane SC.
  • the projection optical system 10 enlarges an image obtained from the reflective liquid crystal element 40 that is an image display element and projects it on a screen or other projection body SB.
  • the projection optical system 10 includes a polarization beam splitter 30, a first lens group 11, an optical path separation element 91, a third lens group 92, and a reflection optical system 70 in order from the reflective liquid crystal element 40 side.
  • the optical path separation element 91, the third lens group 92, and the reflection optical system 70 are used in common with the imaging optical system 50 described later. Focusing can be performed by moving some of the first lens group 11 or the third lens group 92 or the entire lens group in the direction of the optical axis OA.
  • the third lens group 92 enables focusing that is common to the imaging optical system 50.
  • the first lens group 11 includes, in order from the reflective liquid crystal element 40 side, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5. And a sixth lens L6.
  • the first lens group 11 includes at least one aspheric lens.
  • an aperture stop ST is provided between the sixth lens L6 and the optical path separation element 91.
  • the illumination optical system 20 includes a light emission source, a condensing optical system, a polarization conversion element, and the like, although detailed description is omitted.
  • the light source for example, a light source incorporating three color LEDs or the like can be used, and the condensing optical system converts, for example, illumination light from the three color LEDs or the like into substantially parallel light.
  • the polarization conversion element converts the incident light into specific polarization without reducing the amount of incident light.
  • the polarization beam splitter (PBS) 30 is formed by bonding a pair of right-angle prisms, and reflects linearly polarized light in a predetermined direction incident from the illumination optical system 20 on the inclined surface of the one right-angle prism on the bonding surface.
  • a polarization separation surface 31 made of a polarization separation film is formed.
  • the polarization beam splitter (PBS) 30 is disposed in the optical path portion of the illumination light, reflects the illumination light emitted from the illumination optical system 20, and makes it incident on a reflective liquid crystal element 40 described later. Further, the modulated light emitted from the image display surface DD of the reflective liquid crystal element 40 is transmitted and incident on the first lens group 11.
  • the reflective liquid crystal element 40 is a display element (image display element) that forms image light, and can be said to be a light modulation element in that image light is formed from illumination light by changing a spatial reflectance.
  • the reflective liquid crystal element (image display element) 40 is an image display panel that is a plate-like electronic component.
  • the reflection type liquid crystal element 40 is a micro display also called LCOS (Liquid crystal on silicon), in which a circuit is directly formed on the surface of a silicon chip and a liquid crystal layer is sandwiched between a counter substrate. When a voltage corresponding to a drive signal is applied to a liquid crystal layer for each pixel, the reflective liquid crystal element 40 modulates illumination light by changing the arrangement of liquid crystal molecules and displays a desired image. .
  • the image driving circuit 41 is a circuit portion that operates the reflective liquid crystal element 40 based on an image signal.
  • the image drive circuit 41 operates based on a control signal from a control circuit 80 described later, and outputs a drive signal corresponding to the image signal to the reflective liquid crystal element 40 to perform an image display operation.
  • the imaging optical system 50 reduces the image of the projection surface SC and its periphery (rectangular outer region) and forms it on the image sensor 60.
  • the imaging optical system 50 includes a parallel plate F2, a second lens group 51, an optical path separation element 91, a third lens group 92, and a reflection optical system 70 in order from the imaging element 60 side.
  • the optical path separation element 91, the third lens group 92, and the reflection optical system 70 are used in common with the projection optical system 10. Focusing can be performed by moving some of the second lens group 51 or the third lens group 92 or the entire lens group in the direction of the optical axis OA.
  • the second lens group 51 includes, in order from the image sensor 60 side, a twelfth lens L12, a thirteenth lens L13, a fourteenth lens L14, a fifteenth lens L15, a sixteenth lens L16, And a seventeenth lens L17.
  • the second lens group 51 includes at least one aspheric lens.
  • an aperture stop ST is provided between the seventeenth lens L17 and the optical path separation element 91.
  • the first and second lens groups 11 and 51 which are lens groups having different refractive powers, between the optical path separating element 91 and the reflective liquid crystal element 40 and between the optical path separating element 91 and the imaging element 60, respectively.
  • the imaging field angle is wider than the projection field angle.
  • the image sensor 60 is a CMOS image sensor that detects a projected image.
  • the image sensor 60 is disposed on an optical path in which the light beam from the projection surface SC is separated in a direction different from the optical path of the projection optical system 10 by the optical path separation element 91.
  • An image formed by the imaging optical system 50 is formed on the imaging surface IS which is a photoelectric conversion unit of the imaging element 60. That is, an image on the whiteboard or other projection body SB is reduced and formed on the imaging surface IS of the imaging device 60.
  • the image pickup device 60 is not limited to the above-described CMOS type image sensor, and may be one to which another device such as a CCD is applied.
  • the imaging surface IS which is the light receiving surface of the imaging element 60, has a rectangular shape similar to the image display surface DD of the reflective liquid crystal element 40, and has an area equal to or less than that of the image display surface DD. Thereby, size reduction and cost reduction of the projection apparatus 100 can be achieved.
  • the image pickup drive circuit 61 outputs an image to the image pickup device 60 by outputting YUV or other digital pixel signals to an external circuit or receiving a voltage or a clock signal for driving the image pickup device 60 from the control circuit 80.
  • the detection operation is performed.
  • the imaging drive circuit 61 performs a focusing operation by the first and second lens groups 11 and 51 and other lens groups.
  • the image processing unit 62 can perform image processing such as color correction, gradation correction, and compression on the imaging data obtained by using the imaging drive circuit 61, and stores the acquired imaging data or processed data. You can also. Further, the image processing unit 62 corrects the trapezoidal distortion of the projection image acquired by the image sensor 60. The image processing unit 62 performs distortion correction processing on the image signal based on lens correction data read from a data storage unit (not shown).
  • the reflection optical system 70 reflects the projection light emitted from the third lens group 92 and guides it to the projection surface SC, and reflects the light beam from the region including the projection surface SC to guide it to the third lens group 92. is there.
  • the reflective optical system 70 is disposed between the third lens group 92 and the projection surface SC, and has at least one curved mirror 70a.
  • the curved mirror 70a has a convex shape or a concave shape
  • the curved mirror 70a has a free curved surface shape or an aspherical shape.
  • the reflection optical system 70 may be flat.
  • the reflective optical system 70 has one convex curved mirror 70a.
  • the curved mirror 70a may be cut out in a region not used in the optical path.
  • the control circuit 80 can appropriately operate the image driving circuit 41, the image sensor 60, and the like based on a program incorporated therein or an instruction from an operation unit (not shown).
  • the control circuit 80 outputs a drive signal or an image signal to the image drive circuit 41 based on, for example, a video signal or other signal input from the outside, and causes the reflective liquid crystal element 40 to perform a display operation.
  • the control circuit 80 is communicably connected to the imaging device 60 via the interface 81, and can operate the imaging driving circuit 61 to cause the imaging device 60 to perform an imaging operation, as well as control signals and images. Data can be exchanged.
  • the control circuit 80 receives an image signal from the image sensor 60 via the interface 81 after the image pickup by the image sensor 60.
  • This image signal includes not only the projected image but also an additional image such as a handwritten character or a light emitting pen locus.
  • the control circuit 80 can not only optimize the state of the projection image from the received image signal, but also extract an additional image, and can superimpose and record the additional image on the projection image by the extraction. .
  • the optical path separating element 91 is disposed in a different position inside the projection optical system 10 and away from the optical path for guiding the illumination light to the reflective liquid crystal element 40, and the projection surface SC and its periphery (rectangular outer region). Is separated from the optical path of the projection optical system 10. Specifically, the optical path separation element 91 has an action of separating the projection optical path and the imaging optical path so as to be orthogonal to each other. As a result, the size of the optical path separation element 91 can be minimized, and the projection apparatus 100 can be advantageously reduced in size.
  • the optical path separation element 91 may be a prism or a mirror.
  • a polarization beam splitter or polarization mirror using polarization separation is desirable, but not limited to this, the light transmittance is simply controlled. It may be a half mirror.
  • the optical path separating element 91 is in the projection optical system 10. For this reason, when the optical path separating element 91 becomes large, it is necessary to increase the lens interval accordingly, and there is a risk of deteriorating optical performance. Therefore, it is desirable to make the optical path separation element 91 as small as possible.
  • the third lens group 92 is disposed between the optical path separation element 91 and the reflection optical system 70, and is commonly used for projection and imaging.
  • the third lens group 92 has a positive refractive power. Since the third lens group 92 commonly used for projection and imaging has a positive refractive power, the reflection optical system 70 can be made small, and the projection optical system 10 and thus the projection apparatus 100 can be reduced in size. .
  • the third lens group 92 includes, in order from the reflective liquid crystal element 40 side, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, and an eleventh lens L11. And have.
  • the third lens group 92 includes at least one aspheric lens.
  • a lens far from the reflective liquid crystal element 40 for example, the tenth and eleventh lenses L10 and L11 may be cut out in a region not used in the optical path as shown.
  • each of the first to third lens groups 11, 51, 92 includes at least one aspherical lens as described above.
  • the reflection optical system 70 and the third lens group 92 are commonly used for projection and imaging, the angle of view of the imaging optical system 50 is different from the angle of view of the projection optical system 10, and therefore the first lens group. 11 and the second lens group 51 have different aberrations to be corrected.
  • an aspheric lens for each of the first to third lens groups 11, 51, and 92, it is possible to improve the peripheral resolution and reduce the peripheral distortion.
  • the first lens group 11 disposed between the reflective liquid crystal element 40 and the optical path separation element 91 and the second lens group 51 disposed between the imaging element 60 and the optical path separation element 91. Satisfies the following conditional expression. 1.0 ⁇ fTr / fIm ⁇ 1.3 (1) However, the value fTr is the focal length of the first lens group 11, and the value fIm is the focal length of the second lens group 51.
  • Conditional expression (1) indicates that the focal length of the first lens group 11 disposed between the reflective liquid crystal element 40 and the optical path separation element 91 and the first distance disposed between the imaging element 60 and the optical path separation element 91.
  • This is a conditional expression for appropriately setting the focal length of the two lens group 51.
  • the first lens group 11 and the second lens group 51 have different focal lengths, and a difference in the angle of view between the projection optical system 10 and the imaging optical system 50 occurs due to the difference in focal length. Yes. Since the value fTr / fIm exceeds the lower limit of the conditional expression (1), the imaging optical system 50 can be made wider than the projection optical system 10, so that it is outside the projection image on the projection plane SC plane. The written character can be imaged.
  • the imaging optical system 50 is not excessively wide-angled, and an increase in the number of lenses in the second lens group 51 can be suppressed. Further, since the imaging optical system 50 does not become an excessively wide angle, it is possible to suppress a decrease in the resolution of the peripheral portion and an increase in distortion.
  • the projection apparatus 100 satisfies the following conditional expression. 0.2 ⁇ PRz / TL ⁇ 0.7 (2)
  • the value PRz is the distance on the optical axis OA from the reflective liquid crystal element 40 (more specifically, the display surface DD) to the surface of the optical path separating element 91 on the reflective liquid crystal element 40 side
  • the value TL is reflective type. This is the distance on the optical axis OA from the liquid crystal element 40 to the surface of the third lens group 92 closest to the projection surface SC (the eleventh lens L11 in FIG. 1) on the projection surface SC side.
  • Conditional expression (2) is a conditional expression for appropriately setting the position of the optical path separation element 91.
  • the optical path separation element 91 is not too close to the reflective liquid crystal element 40 side, and the influence of stray light due to strong light from the illumination optical system 20 is kept small. be able to. Further, since the installation space for the first lens group 11 and the second lens group 51 is increased, it is possible to configure the projection optical system 10 and the imaging optical system 50 in which aberrations are favorably corrected.
  • the optical path separating element 91 is not disposed too close to the projection surface SC, and the first lens group 11 and the second lens group 51 are simplified. Thus, the size of the projection optical system 10 and thus the projection apparatus 100 can be reduced.
  • the lens arranged in the projection optical system 10 closer to the projection plane SC than the optical path separation element 91 is commonly used for projection and imaging. It is. Therefore, if the optical path separation element 91 is too close to the projection surface SC, the number of lens groups that can be used in common is reduced, and the total optical length of the first lens group 11 and the second lens group 51 is increased. Since the first lens group 11 and the second lens group 51 are arranged in different directions, when the optical total length of the first lens group 11 and the second lens group 51 is increased, the projection apparatus is increased accordingly. . Accordingly, the projection optical system 10 and thus the projection apparatus 100 are reduced in size by falling below the upper limit of the conditional expression (2).
  • FIG. 2 shows the light path of the projection optical system 10 in the projection apparatus 100, and the light path of the imaging optical system 50 is not shown.
  • the projection light PL from the projection device 100 is projected onto the projection area SC1 (see FIG. 7A) in the projection plane SC.
  • the reflected light from the projection surface SC is incident on the projection device 100.
  • the reflected light incident on the projection device 100 is light reflected in the imaging region SC2 (see FIG. 7A) having a larger area than the projection region SC1.
  • the projection apparatus 100 is assumed to be a projector having an interactive function, and one of interactive functions is image recognition of handwritten characters.
  • the area to be imaged in the projection plane SC is wide including the area projected by the projection optical system 10 in the projection plane SC, so it is out of the projected range. Can also be taken.
  • the optical path separation element 91 for separating the optical path is disposed inside the projection optical system 10, and the optical path separation element 91 is disposed between the reflective liquid crystal element 40 and the imaging element 60. Since a part of the projection optical system 10 (the third lens group 92 and the reflection optical system 70 disposed on the projection surface SC side from the optical path separation element 91) can be used in common for projection and imaging, the projection optical system The number of parts can be reduced as compared with the case where the image pickup optical system is mounted separately from 10, and as a result, the projector 100 can be downsized. In addition, it is possible to obtain the imaging optical system 50 that has a peripheral resolving power equivalent to that of the projection optical system 10 and has little distortion.
  • the optical path separating element 91 is disposed at a position very close to the reflective liquid crystal element 40, strong light from the illumination optical system 20 for illuminating the reflective liquid crystal element 40 enters the imaging element 60. The risk of becoming higher.
  • the polarizing beam splitter 30 serving as the optical path of illumination light is disposed immediately before the reflective liquid crystal element 40, the first lens group 11 is disposed between the polarizing beam splitter 30 and the optical path separating element 91, and the optical path separating element.
  • the arrangement position of the optical path separation element 91 can be moved away from the polarization beam splitter 30 that is the optical path of the illumination light, and stray light caused by the illumination light Can be suppressed.
  • the first lens group 11 is disposed between the reflective liquid crystal element 40 and the optical path separation element 91
  • the second lens group 51 is disposed between the optical path separation element 91 and the imaging element 60, thereby capturing an image. It is not necessary to provide a re-imaging optical system that forms an image in the vicinity of the optical path separating element 91 after the light path separating element 91 is emitted on the optical path, so that the optical system can be simplified and miniaturized.
  • the first and second lens groups 11 and 51 having different refractive powers are arranged between the reflective liquid crystal element 40 and the optical path separating element 91 and between the optical path separating element 91 and the imaging element 60, respectively.
  • the angle wider than the projection angle of view it is possible to capture images up to the outer region of the projected image on the projection surface SC.
  • the size of the image sensor 60 can be made equal to or smaller than that of the reflective liquid crystal element 40, and the increase in size and cost of the optical system can be suppressed.
  • the surface described with “*” after each surface number is a surface having an aspherical shape, and the aspherical shape has the apex of the surface as the origin and the optical axis direction.
  • the Z axis (not necessarily coincident with the coordinates in FIG. 1) is taken, and the height in the direction perpendicular to the optical axis is h, and is expressed by the following “Expression 1”.
  • infinity is represented as “INF”
  • the display surface of the reflective liquid crystal element 40 is represented as “DD”
  • the aperture stop is represented as “ST”
  • the surface of the optical path separating element 91 is represented as “LD”
  • a curved mirror The reflecting surfaces 70a, 70b, and 70c are represented as “MR”
  • the projection surface is represented as “SC”
  • the imaging surface of the image sensor 60 is represented as “IS”.
  • Ai i-order aspheric coefficient
  • R radius of curvature
  • K conic constant
  • the surface with “**” after each surface number is a surface having an aspherical shape, and the free-form surface shape is the same as the aspherical shape with the vertex of the surface as the origin, and light
  • the Z axis is taken as the axial direction, and the height in the direction perpendicular to the optical axis is h.
  • Cj x m y coefficient n R: radius of curvature
  • K conical constant or conic constant
  • Example 1 The basic specifications of the projection optical system and the imaging optical system of Example 1 are shown below.
  • F number projection optical system
  • F number imaging optical system
  • F4.0 Display surface size of image display element: 13.5 mm x 7.6 mm
  • Image pickup surface size of the image pickup device 13.5 mm ⁇ 7.6 mm
  • Table 1 below shows data such as lens surfaces of the projection optical system and the imaging optical system of Example 1.
  • the description of the optical path separation element, the third lens group, and the reflection optical system (Surf. N: 14 to SC) used in common with the projection optical system is omitted ( The same applies to Example 2).
  • Table 2 shows the aspheric coefficients of the aspheric surfaces included in the projection optical system and the imaging optical system of Example 1.
  • a power of 10 for example, 2.5 ⁇ 10 ⁇ 02
  • E for example, 2.5E-02
  • Table 3 shows the free-form surface coefficients of the curved mirror 70a commonly used in the projection optical system and the imaging optical system of Example 1.
  • “*” represents a product
  • “**” represents a power (the same applies to the following examples).
  • FIG. 3 is a sectional view of the projection optical system 10A of the first embodiment. Specifically, it is a sectional view from the reflective liquid crystal element 40 to the reflective optical system 70.
  • FIG. 4 is a cross-sectional view of the imaging optical system 50A of the first embodiment, specifically, a cross-sectional view from the imaging element 60 to the reflection optical system 70.
  • the projection optical system 10A of Example 1 includes a polarization beam splitter 30, a first lens group 11, an optical path separation element 91, a third lens group 92, and a reflection optical system 70.
  • the imaging optical system 50A includes a parallel plate F2, a second lens group 51, an optical path separation element 91, a third lens group 92, and a reflection optical system 70.
  • the first lens group 11 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5 in order from the reflective liquid crystal element 40 that is an image display element. And a sixth lens L6.
  • the third lens group 92 includes, in order from the reflective liquid crystal element 40 side, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, and an eleventh lens L11.
  • the second lens group 51 includes, in order from the image sensor 60 side, a twelfth lens L12, a thirteenth lens L13, a fourteenth lens L14, a fifteenth lens L15, a sixteenth lens L16, and a seventeenth lens L17.
  • the first, tenth, eleventh, and twelfth lenses L1, L10, L11, and L12 are aspherical lenses.
  • the reflective optical system 70 has a refractive power, and is a convex free-form curved mirror 70a on the side close to the optical axis OA of the projection optical system 10A.
  • Reference numeral F ⁇ b> 1 indicates a parallel plate corresponding to the polarizing beam splitter 30 in which the image display element is disposed in front of the reflective liquid crystal element 40.
  • the parallel plate F1 may not be necessary. However, since the parallel plate F1 does not have refractive power, the optical system after the parallel plate F1 is not changed and the parallel plate F1 is excluded. You can also. In that case, the air space between the image display element and the first lens L1 may be set to an optimum position.
  • Reference numeral F2 is a parallel plate that is assumed to include, for example, an optical low-pass filter, an IR cut filter, a seal glass of the image sensor 60, and the like.
  • the imaging optical system 50 is arranged at a position bent in the orthogonal direction by the optical path separation element 91, but conversely, the projection optical system 10 is in a position bent in the orthogonal direction by the optical path separation element 91. You may arrange.
  • 5A and 5B are MTF (Modulation Transfer Function) characteristic diagrams on the projection surface SC of the projection optical system 10A.
  • 5A is an MTF characteristic diagram of the evaluation positions FP1 to FP3 in the projection region SC1 shown in FIG. 7A
  • FIG. 5B is an MTF characteristic diagram of the evaluation positions FP4 to FP6 in the projection region SC1 shown in FIG. 7A
  • 6A and 6B are MTF characteristics diagrams on the imaging surface IS of the imaging element 60 of the imaging optical system 50A.
  • 6A is an MTF characteristic diagram of the evaluation positions FP1 to FP3 in the imaging region SC2 shown in FIG. 7B
  • FIG. 6B is an MTF characteristic diagram of the evaluation positions FP4 to FP6 in the imaging region SC2 shown in FIG.
  • the projection area SC1 is a range in which a projection image is actually shown, and the area of the imaging area SC2 on the projection surface SC is larger than the area of the projection area SC1.
  • the vertical resolution of The wavelength weights for calculating the MTF are as follows (the same applies to the second embodiment). [Wavelength weight] Wavelength weight 656.3nm 34 587.6nm 63 546.1nm 100 486.1nm 83 435.8nm 26 404.7nm 8
  • Example 2 The basic specifications of the projection optical system and the imaging optical system of Example 2 are shown below.
  • Table 4 below shows data such as lens surfaces of the projection optical system and the imaging optical system of Example 2.
  • ⁇ Projection optics> Surf.N R [mm] D [mm] Nd ⁇ d DD 1.400 1 INF 13.660 1.5187 64.0 2 INF 1.000 3 40.496 15.914 1.8550 23.5 4 -98.169 8.972 5 81.768 3.227 1.4891 70.0 6 -42.587 2.980 1.8550 23.5 7 23.843 1.542 8 18.467 4.833 1.4891 70.0 9 -25.110 3.612 1.8550 23.5 10 -78.485 1.646 11 * 32.427 4.310 1.6347 23.9 12 * -84.647 1.846 13 ST INF 17.207 14 LD INF 25.000 1.8550 23.5 15 LD INF 1.000 16 118.247 4.534 1.8550 23.5 17 264.439 1.000 18 30.572 10.216 1.4891 70.0 19 -55.018 3.100 20 * -25.858 3.000 1.5305 56.0 21 * 96
  • Table 5 below shows the aspheric coefficients of the aspheric surfaces included in the projection optical system and the imaging optical system of Example 2.
  • FIG. 8 is a sectional view of the projection optical system 10B of the second embodiment. Specifically, it is a sectional view from the reflective liquid crystal element 40 to the reflective optical system 70.
  • FIG. 9 is a cross-sectional view of the image pickup optical system 50B of the second embodiment, specifically, a cross-sectional view from the image pickup element 60 to the reflection optical system 70.
  • the projection optical system 10B of Example 2 includes a polarization beam splitter 30, a first lens group 11, an optical path separation element 91, a third lens group 92, and a reflection optical system 70.
  • the imaging optical system 50 ⁇ / b> B includes a parallel plate F ⁇ b> 2, a second lens group 51, an optical path separation element 91, a third lens group 92, and a reflection optical system 70.
  • the first lens group 11 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5 in order from the reflective liquid crystal element 40 that is an image display element. And a sixth lens L6.
  • the third lens group 92 includes, in order from the reflective liquid crystal element 40 side, a seventh lens L7, an eighth lens L8, and a ninth lens L9.
  • the second lens group 51 includes, in order from the image sensor 60 side, a tenth lens L10, an eleventh lens L11, a twelfth lens L12, a thirteenth lens L13, a fourteenth lens L14, and a fifteenth lens L15.
  • the sixth, ninth, and fifteenth lenses L6, L9, and L15 are aspheric lenses.
  • the reflective optical system 70 includes an aspheric type curved mirror 70b having refractive power and an aspheric type curved mirror 70c.
  • 10A and 10B are MTF characteristics diagrams on the projection plane SC of the projection optical system 10B.
  • 11A and 11B are MTF characteristics diagrams on the imaging surface IS of the imaging element 60 of the imaging optical system 50B.
  • the number of lenses in the first and second lens groups 11 and 51 is the same, but it may be different. Further, the number of lenses constituting the first to third lens groups 11, 51, 92 may be one or more. Further, the radius of curvature and the core thickness of the constituting lens can be appropriately changed. Further, the reflection optical system 70 may not be used.
  • the image display element is not limited to the reflective liquid crystal element 40 such as LCOS, but a micromirror device including a micromirror, a transmissive LCD, or the like can be used.
  • the polarization beam splitter 30 is changed to an optical system suitable for each.
  • the light source of the illumination optical system 20 is not limited to the LED, and a mercury lamp, a laser, or the like can be used, and these light sources can be used in the same type or different types.
  • the number of red, green, and blue light sources may be arbitrarily combined according to the output. Further, it is possible to increase the brightness by adding an optical system for multiplexing and arranging a plurality of light sources for white or a specific color.

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Abstract

This projection device 100 includes a projection optical system 10 that magnifies an image acquired from a reflective liquid crystal element 40 that is an image display element irradiated with illumination light and projects the image onto a projection screen SC. A light path separation element 91 is arranged to separate a light path and directs a portion of the light path to a position different from the position of the light path for the illumination light inside the projection optical system 10. An imaging element 60 is arranged in the light path separated by the light path separation element 91 where a portion of a beam from the projection screen SC is separated in a different direction from the light path for the projection optical system 10. First and second lens groups 11, 51 having mutually different refractive powers are arranged between the light path separation element 91 and the reflective liquid crystal element 40, and between the light path separation element 91 and the imaging element 60, respectively. The imaging angle of view is wider than the projection angle of view.

Description

投影装置Projection device
　本発明は、画像の投影及び撮像が可能な投影装置に関するものであり、特に広角な撮像が可能な投影装置に関する。 The present invention relates to a projection apparatus capable of projecting and capturing an image, and more particularly to a projection apparatus capable of capturing a wide angle.
　近年、画像表示素子に表示された画像を投影光学系によってスクリーン上に拡大投影する投影装置には、小型軽量でありながら、短い投影距離でも大画面に映し出せる広角な投影光学系が望まれている。そのような中で、スクリーンの真下や真上等、スクリーンに近接した位置に配置できる短焦点プロジェクターが登場している。 In recent years, a projection apparatus that enlarges and projects an image displayed on an image display element onto a screen by a projection optical system is desired to have a wide-angle projection optical system that can be projected on a large screen even at a short projection distance while being small and light. Yes. Under such circumstances, short-focus projectors that can be arranged at positions close to the screen, such as directly below or directly above the screen, have appeared.
　また、プロジェクターには、単にＰＣ画面をスクリーン等に投影するだけでなく、ホワイトボード等にＰＣ画面を投影しながら、そこに手書きの文字を書き込み、その情報を撮像光学系によって画像として記録したり発表者の動きを感知して投影画面のページを進ませたりする等の、インタラクティブな機能の付いたものが出てきている。 In addition to simply projecting a PC screen onto a screen or the like, the projector can also project the PC screen onto a whiteboard or the like while writing handwritten characters on the screen and recording the information as an image with an imaging optical system. Something with interactive features, such as detecting the presenter's movement and advancing the projection screen page, has come out.
　また、プロジェクターには、一般的に投影画像の台形歪み補正や周辺環境に合わせた明るさ補正等の各種補正処理が必要である。台形歪み補正や明るさ補正、又は人物の単純な動きを検出するだけであれば、撮像光学系はＶＧＡ程度の画素数で十分であるが、手書きの文字を投影画像に重畳させて、画像データとして取り込むためにはメガクラスの解像度が必要となり、それに用いられる撮像レンズにも高性能であることが望まれてくる。 Also, projectors generally require various correction processes such as trapezoidal distortion correction of projected images and brightness correction according to the surrounding environment. If only trapezoidal distortion correction, brightness correction, or simple human motion detection is required, the imaging optical system needs only about VGA pixels, but handwritten characters are superimposed on the projected image, and the image data In order to capture the image, it is necessary to have a mega-class resolution, and it is desired that the imaging lens used for it has high performance.
　特に、上述のようなスクリーンに近接した位置に配置する短焦点プロジェクターに撮像光学系を組み込もうとすると、撮像レンズが非常に広角である必要がある。そのため、投影面周辺部の解像力を十分に確保するのが難しく、さらに、周辺部での歪曲収差が大きいため、取り込まれる画像に歪曲補正等の画像処理を行うことで、結果として周辺部の解像力低下を引き起こしてしまうことになる。したがって、超広角でありながら広角レンズに発生しがちな樽型の歪曲収差を極力抑えた光学系が必要となってくる。 In particular, when an imaging optical system is to be incorporated in a short focus projector arranged at a position close to the screen as described above, the imaging lens needs to have a very wide angle. For this reason, it is difficult to ensure sufficient resolution at the periphery of the projection surface, and since distortion at the periphery is large, image processing such as distortion correction is performed on the captured image, resulting in resolution at the periphery. It will cause a decline. Therefore, there is a need for an optical system that suppresses as much as possible the barrel-shaped distortion that tends to occur in a wide-angle lens while having an ultra-wide angle.
　広角ながら収差を抑えた撮像光学系を得る手法として、比較的歪曲収差が補正され、周辺部まで解像力の高い投影光学系の全て、又は一部をそのまま撮像光学系として使用するものがある（特許文献１及び２参照）。特許文献１には、画像表示素子と投影光学系との間に配置された偏光ビームスプリッターによって、投影側の光路と撮像側の光路とを分けることで、投影光学系を共通に使用しつつ撮像手段を得ることができる光学系が提案されている。特許文献１の光学系では、投影光学系をそのまま撮像光学系として使用できるため、投影光学系とは別に撮像光学系を搭載するよりも装置自体の小型化が達成でき、高解像度で低歪曲な撮影画像を得ることができるようになる。 As a technique for obtaining an imaging optical system that suppresses aberrations while having a wide angle, there is a technique in which all or part of a projection optical system that has relatively high distortion and has a relatively high resolution is used as an imaging optical system as it is. Reference 1 and 2). Japanese Patent Laid-Open No. 2004-260688 divides an optical path on the projection side and an optical path on the imaging side by using a polarization beam splitter disposed between the image display element and the projection optical system, thereby capturing an image while using the projection optical system in common. An optical system capable of obtaining means has been proposed. In the optical system of Patent Document 1, since the projection optical system can be used as it is as the imaging optical system, the apparatus itself can be downsized rather than mounting the imaging optical system separately from the projection optical system, and the resolution is high and the distortion is low. A photographed image can be obtained.
　ところで、手書きの文字は投影画像の投影範囲内に書かれるとは限らない。従って、撮像光学系は投影光学系よりも画角が広いことが望ましい。しかしながら、特許文献１のような光学系では、投影の光路と撮像の光路とで光学系が全く同じであるため、画像表示素子と撮像素子とが同じサイズであった場合には、画角が共通となってしまい、例えば、投影画像の外側に書かれた文字を撮像することができない。特許文献１の光学系で投影画像の外側に書かれた文字を撮像しようとした場合、投影光学系の画角を投影範囲より広くしておき、画像表示素子より大きな面積の撮像素子を配置する必要があり、光学系、ひいては装置の大型化及びコスト増といった問題が生じる。また、画像表示素子と撮像素子とが非常に近接した位置に配置されるため、画像表示素子に入射する照明光学系からの光線が迷光として撮像素子に入射してしまうリスクが高く、迷光はフレア成分となり、撮影画像を劣化させる要因となってしまう。 By the way, handwritten characters are not always written within the projection range of the projected image. Therefore, it is desirable that the imaging optical system has a wider angle of view than the projection optical system. However, in the optical system as in Patent Document 1, the optical system is exactly the same in the projection optical path and the imaging optical path, and therefore, when the image display element and the imaging element are the same size, the angle of view is For example, a character written outside the projected image cannot be captured. When an image written outside the projected image is to be captured by the optical system of Patent Document 1, the angle of view of the projection optical system is set wider than the projection range, and an imaging element having a larger area than the image display element is disposed. Therefore, problems such as an increase in the size and cost of the optical system and thus the apparatus arise. In addition, since the image display element and the image sensor are arranged at very close positions, there is a high risk that light from the illumination optical system incident on the image display element will be incident on the image sensor as stray light. It becomes a component and becomes a factor of deteriorating the captured image.
　一方、特許文献２には、画像表示素子と投影光学系との間に配置されたＴＩＲプリズムによって、投影側の光路と撮像側の光路とを分けることで、投影光学系を共通に使用しつつ撮像手段を得ることができる光学系が提案されている。また、投影画角と撮像画角とを異ならせるために、ＴＩＲプリズムと撮像素子との間に倍率補正光学系が配置されている実施例も開示されている。 On the other hand, in Patent Document 2, a projection optical system is commonly used by separating a projection-side optical path and an imaging-side optical path by a TIR prism disposed between an image display element and the projection optical system. An optical system capable of obtaining an imaging means has been proposed. An embodiment in which a magnification correction optical system is disposed between the TIR prism and the image sensor in order to make the projection field angle and the imaging field angle different is also disclosed.
　しかしながら、特許文献２のような光学系では、撮像側のＴＩＲプリズム内での光路長が投影側よりも長いため、撮像側の光路ではＴＩＲプリズムの内部で光線が一度結像することになる。従って、特許文献２の光学系では、倍率補正光学系の詳細については触れられていないが、倍率補正光学系は、再結像リレー光学系とする必要があり、設計難易度が高く、レンズ枚数も増加したものとなる。 However, in an optical system such as Patent Document 2, since the optical path length in the TIR prism on the imaging side is longer than that on the projection side, a light beam forms an image once inside the TIR prism in the optical path on the imaging side. Therefore, although the details of the magnification correction optical system are not mentioned in the optical system of Patent Document 2, the magnification correction optical system needs to be a re-imaging relay optical system, and the degree of design difficulty is high. Will also increase.
特開２００３－４４８３９号公報JP 2003-44839 A 特許第５１７４２７３号公報Japanese Patent No. 5174273
　本発明は、上記背景技術の問題点に鑑みてなされたものであり、撮像側の光路に投影光学系の一部を共通で使用することで、周辺部まで高解像力、低歪みでありながらも、撮像画角が投影画角よりも広く、超広角な撮像レンズを搭載する小型の投影装置を提供することを目的とする。 The present invention has been made in view of the above-mentioned problems of the background art, and by using a part of the projection optical system in common in the optical path on the imaging side, while having high resolution and low distortion up to the peripheral part. An object of the present invention is to provide a small-sized projection device equipped with an imaging lens having an imaging field angle wider than the projection field angle and an ultra-wide angle.
　上記目的を達成するため、本発明にかかる投影装置は、照明光により照明された画像表示素子から得られる像を拡大して投影面上に投影する投影光学系を有する投影装置であって、投影光学系の内部の照明光の光路部とは異なる位置に光路を分離するための光路分離素子が配置され、光路分離素子によって投影面からの光線が投影光学系の光路とは異なる方向に分離された光路上に撮像素子が配置され、光路分離素子と画像表示素子の間と、光路分離素子と撮像素子の間には、互いに異なる屈折力を有するレンズ群がそれぞれ配置され、投影画角よりも撮像画角が広い。 In order to achieve the above object, a projection apparatus according to the present invention is a projection apparatus having a projection optical system that magnifies and projects an image obtained from an image display element illuminated by illumination light onto a projection plane. An optical path separation element for separating the optical path is arranged at a position different from the optical path part of the illumination light inside the optical system, and the light from the projection surface is separated in a direction different from the optical path of the projection optical system by the optical path separation element. An image sensor is disposed on the optical path, and lens groups having different refractive powers are disposed between the optical path separation element and the image display element, and between the optical path separation element and the image sensor, respectively, and are more than the projection field angle. Wide field of view.
　上記投影装置では、投影光学系の内部に光路を分離するための光路分離素子を配置することで、投影光学系の一部（光路分離素子から投影面側に配置されたレンズ群）を投影及び撮像で共通して使用することができるので、投影光学系とは別に撮像光学系を搭載するよりも部品点数を削減でき、結果として投影装置の小型化を達成できる。また、光路分離素子を照明光の光路部と異なる位置に配置することで、照明光に起因する迷光を抑制することができ、フレアの抑制された良好な画質の撮像画像を得ることができる。また、画像表示素子と光路分離素子の間、及び光路分離素子と撮像素子の間の両方にレンズ群を配置する構成とすることによって、撮像の光路上において光路分離素子出射後に光路分離素子近傍で結像する再結像光学系とする必要がなくなるため、光学系を全体として簡素化し小型化することができる。また、投影光学系と同等レベルの周辺解像力を有し、歪みが少ない撮像光学系とすることができる。さらに、画像表示素子と光路分離素子の間、及び光路分離素子と撮像素子の間に互いに異なる屈折力を有するレンズ群をそれぞれ配置し、投影画角よりも撮像画角を広くすることによって、投影面上での投影画像の外側領域まで撮像することができる。これにより、撮像素子の大きさを画像表示素子と同等かそれ以下にでき、光学系の大型化及びコスト増を抑制することができる。 In the projection apparatus, an optical path separation element for separating an optical path is disposed inside the projection optical system, thereby projecting a part of the projection optical system (a lens group disposed on the projection plane side from the optical path separation element). Since it can be used in common for imaging, it is possible to reduce the number of parts compared to mounting the imaging optical system separately from the projection optical system, and as a result, it is possible to reduce the size of the projection apparatus. Further, by arranging the optical path separation element at a position different from the optical path portion of the illumination light, stray light caused by the illumination light can be suppressed, and a captured image with good image quality with reduced flare can be obtained. In addition, by arranging the lens group between the image display element and the optical path separation element and between the optical path separation element and the imaging element, in the vicinity of the optical path separation element after emitting the optical path separation element on the imaging optical path. Since it is not necessary to use a re-imaging optical system for forming an image, the entire optical system can be simplified and reduced in size. In addition, the imaging optical system can have a peripheral resolving power equivalent to that of the projection optical system and has little distortion. Further, by arranging lens groups having different refractive powers between the image display element and the optical path separation element and between the optical path separation element and the imaging element, respectively, the imaging field angle is made wider than the projection field angle, thereby projecting. It is possible to take an image up to the outer region of the projected image on the surface. Thereby, the magnitude | size of an image pick-up element can be made into the same or less than an image display element, and the enlargement and cost increase of an optical system can be suppressed.
本発明の一実施形態にかかる投影装置の概略構成を説明する図である。It is a figure explaining schematic structure of the projection device concerning one embodiment of the present invention. 図１に示す投影装置を用いた投影状態を説明する図である。It is a figure explaining the projection state using the projector shown in FIG. 実施例１の投影光学系の断面図である。1 is a cross-sectional view of a projection optical system of Example 1. FIG. 実施例１の撮像光学系の断面図である。1 is a cross-sectional view of an imaging optical system according to Example 1. FIG. 図５Ａ及び５Ｂは、実施例１の投影光学系の投影面上における性能を示すＭＴＦ特性図である。5A and 5B are MTF characteristic diagrams showing performance on the projection surface of the projection optical system of Example 1. FIG. 図６Ａ及び６Ｂは、実施例１の撮像光学系の撮像面上における性能を示すＭＴＦ特性図である。6A and 6B are MTF characteristic diagrams showing performance on the imaging surface of the imaging optical system of Example 1. FIG. 図７Ａ及び７Ｂは、投影面又は撮像面上のＭＴＦ評価ポイントを説明する図である。7A and 7B are diagrams for explaining the MTF evaluation points on the projection plane or the imaging plane. 実施例２の投影光学系の断面図である。6 is a cross-sectional view of a projection optical system of Example 2. FIG. 実施例２の撮像光学系の断面図である。6 is a cross-sectional view of an imaging optical system according to Example 2. FIG. 図１０Ａ及び１０Ｂは、実施例２の投影光学系の投影面上における性能を示すＭＴＦ特性図である。10A and 10B are MTF characteristic diagrams showing the performance of the projection optical system of Example 2 on the projection surface. 図１１Ａ及び１１Ｂは、実施例２の撮像光学系の撮像面上における性能を示すＭＴＦ特性図である。11A and 11B are MTF characteristic diagrams showing performance on the imaging surface of the imaging optical system of Example 2. FIG.
　以下、図面を参照しつつ、本発明の実施形態にかかる投影光学系について説明する。 Hereinafter, a projection optical system according to an embodiment of the present invention will be described with reference to the drawings.
　図１に、本発明の実施形態にかかる投影光学系を組み込んだ投影装置を示し、図２に、投影光学系による投影状態を示す。投影装置１００は、画像の投影に際して撮像をも可能にするものであり、投影光学系１０と、照明光学系２０と、偏光ビームスプリッター３０と、反射型液晶素子４０と、画像駆動回路４１と、撮像光学系５０と、撮像素子６０と、平行平板Ｆ２と、撮像駆動回路６１と、画像処理部６２と、制御回路８０とを有する。投影装置１００は、投影装置としての機能の他に、その一部構成について撮像装置としての機能も有する。本実施形態の投影装置１００は、図２に示す投影体ＳＢ、すなわち投影面ＳＣの直下に配置される。 FIG. 1 shows a projection apparatus incorporating a projection optical system according to an embodiment of the present invention, and FIG. 2 shows a projection state by the projection optical system. The projection apparatus 100 also enables imaging when projecting an image, and includes a projection optical system 10, an illumination optical system 20, a polarization beam splitter 30, a reflective liquid crystal element 40, an image drive circuit 41, The imaging optical system 50, the imaging device 60, the parallel plate F2, the imaging drive circuit 61, the image processing unit 62, and the control circuit 80 are included. In addition to the function as a projection device, the projection device 100 also has a function as an imaging device for a part of the configuration. The projection apparatus 100 of the present embodiment is disposed directly below the projection body SB shown in FIG. 2, that is, the projection plane SC.
　投影光学系１０は、画像表示素子である反射型液晶素子４０から得られる像を拡大してスクリーンその他の投影体ＳＢに投影する。投影光学系１０は、反射型液晶素子４０側から順に、偏光ビームスプリッター３０と、第１レンズ群１１と、光路分離素子９１と、第３レンズ群９２と、反射光学系７０とを有する。投影光学系１０のうち、光路分離素子９１、第３レンズ群９２、及び反射光学系７０は、後述する撮像光学系５０と共通で使用される。第１レンズ群１１又は第３レンズ群９２のうち一部のレンズ又はレンズ群全体を光軸ＯＡ方向に移動させることにより、フォーカシングを行わせることができる。なお、第３レンズ群９２は、撮像光学系５０にも共通するフォーカシングを可能にする。 The projection optical system 10 enlarges an image obtained from the reflective liquid crystal element 40 that is an image display element and projects it on a screen or other projection body SB. The projection optical system 10 includes a polarization beam splitter 30, a first lens group 11, an optical path separation element 91, a third lens group 92, and a reflection optical system 70 in order from the reflective liquid crystal element 40 side. In the projection optical system 10, the optical path separation element 91, the third lens group 92, and the reflection optical system 70 are used in common with the imaging optical system 50 described later. Focusing can be performed by moving some of the first lens group 11 or the third lens group 92 or the entire lens group in the direction of the optical axis OA. The third lens group 92 enables focusing that is common to the imaging optical system 50.
　図１の例において、第１レンズ群１１は、反射型液晶素子４０側から順に、第１レンズＬ１と、第２レンズＬ２と、第３レンズＬ３と、第４レンズＬ４と、第５レンズＬ５と、第６レンズＬ６とを有する。第１レンズ群１１は、非球面レンズを少なくとも１枚以上含む。なお、第１レンズ群１１において、第６レンズＬ６と光路分離素子９１との間には、開口絞りＳＴが設けられている。 In the example of FIG. 1, the first lens group 11 includes, in order from the reflective liquid crystal element 40 side, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5. And a sixth lens L6. The first lens group 11 includes at least one aspheric lens. In the first lens group 11, an aperture stop ST is provided between the sixth lens L6 and the optical path separation element 91.
　照明光学系２０は、詳細な説明を省略するが、発光源、集光光学系、偏光変換素子等を備える。発光源としては、例えば３色のＬＥＤ等を組み込んだものを用いることができ、集光光学系は、例えば３色のＬＥＤ等からの照明光を略平行光に変換する。また偏光変換素子は、入射した光の光量を低下させずに特定の偏光に変換する。 The illumination optical system 20 includes a light emission source, a condensing optical system, a polarization conversion element, and the like, although detailed description is omitted. As the light source, for example, a light source incorporating three color LEDs or the like can be used, and the condensing optical system converts, for example, illumination light from the three color LEDs or the like into substantially parallel light. The polarization conversion element converts the incident light into specific polarization without reducing the amount of incident light.
　偏光ビームスプリッター（ＰＢＳ）３０は、一対の直角プリズムを貼り合わせたものであり、貼合わせ面において、一方の直角プリズムの斜面には、照明光学系２０から入射した所定方向の直線偏光を反射させる偏光分離膜からなる偏光分離面３１が形成されている。偏光ビームスプリッター（ＰＢＳ）３０は、照明光の光路部に配置され、照明光学系２０から射出された照明光を反射させ、後述する反射型液晶素子４０に入射させる。また、この反射型液晶素子４０の画像表示面ＤＤから射出された変調光を透過させ、第１レンズ群１１に入射させる。 The polarization beam splitter (PBS) 30 is formed by bonding a pair of right-angle prisms, and reflects linearly polarized light in a predetermined direction incident from the illumination optical system 20 on the inclined surface of the one right-angle prism on the bonding surface. A polarization separation surface 31 made of a polarization separation film is formed. The polarization beam splitter (PBS) 30 is disposed in the optical path portion of the illumination light, reflects the illumination light emitted from the illumination optical system 20, and makes it incident on a reflective liquid crystal element 40 described later. Further, the modulated light emitted from the image display surface DD of the reflective liquid crystal element 40 is transmitted and incident on the first lens group 11.
　反射型液晶素子４０は、映像光を形成する表示素子（画像表示素子）であり、特に空間的な反射率を変化させることによって照明光から映像光を形成する点で光変調素子と言える。反射型液晶素子（画像表示素子）４０は、板状の電子部品である画像表示パネルからなる。この反射型液晶素子４０は、ＬＣＯＳ（Liquid crystal on silicon）とも称されるマイクロディスプレイであり、シリコンチップの表面に直接回路が形成され対向基板との間に液晶層を挟み込んだものである。反射型液晶素子４０は、液晶層に対し駆動信号に応じた電圧が画素毎に印加されると、液晶分子の配列を変化させることで照明光を変調し、所望の画像を表示するものである。 The reflective liquid crystal element 40 is a display element (image display element) that forms image light, and can be said to be a light modulation element in that image light is formed from illumination light by changing a spatial reflectance. The reflective liquid crystal element (image display element) 40 is an image display panel that is a plate-like electronic component. The reflection type liquid crystal element 40 is a micro display also called LCOS (Liquid crystal on silicon), in which a circuit is directly formed on the surface of a silicon chip and a liquid crystal layer is sandwiched between a counter substrate. When a voltage corresponding to a drive signal is applied to a liquid crystal layer for each pixel, the reflective liquid crystal element 40 modulates illumination light by changing the arrangement of liquid crystal molecules and displays a desired image. .
　画像駆動回路４１は、画像信号に基づいて反射型液晶素子４０を動作させる回路部分である。画像駆動回路４１は、後述する制御回路８０からの制御信号に基づいて動作し、反射型液晶素子４０に画像信号に対応する駆動信号を出力し画像の表示動作を行わせる。 The image driving circuit 41 is a circuit portion that operates the reflective liquid crystal element 40 based on an image signal. The image drive circuit 41 operates based on a control signal from a control circuit 80 described later, and outputs a drive signal corresponding to the image signal to the reflective liquid crystal element 40 to perform an image display operation.
　撮像光学系５０は、投影面ＳＣ及びその周辺（矩形の外側領域）の像を縮小して撮像素子６０上に結像させる。撮像光学系５０は、撮像素子６０側から順に、平行平板Ｆ２と、第２レンズ群５１と、光路分離素子９１と、第３レンズ群９２と、反射光学系７０とを有する。既に説明したように、撮像光学系５０のうち、光路分離素子９１、第３レンズ群９２、及び反射光学系７０は、投影光学系１０と共通で使用される。第２レンズ群５１又は第３レンズ群９２のうち一部のレンズ又はレンズ群全体を光軸ＯＡ方向に移動させることにより、フォーカシングを行わせることができる。 The imaging optical system 50 reduces the image of the projection surface SC and its periphery (rectangular outer region) and forms it on the image sensor 60. The imaging optical system 50 includes a parallel plate F2, a second lens group 51, an optical path separation element 91, a third lens group 92, and a reflection optical system 70 in order from the imaging element 60 side. As already described, in the imaging optical system 50, the optical path separation element 91, the third lens group 92, and the reflection optical system 70 are used in common with the projection optical system 10. Focusing can be performed by moving some of the second lens group 51 or the third lens group 92 or the entire lens group in the direction of the optical axis OA.
　図１の例において、第２レンズ群５１は、撮像素子６０側から順に、第１２レンズＬ１２と、第１３レンズＬ１３と、第１４レンズＬ１４と、第１５レンズＬ１５と、第１６レンズＬ１６と、第１７レンズＬ１７とを有する。第２レンズ群５１は、非球面レンズを少なくとも１枚以上含む。なお、第２レンズ群５１において、第１７レンズＬ１７と光路分離素子９１との間には、開口絞りＳＴが設けられている。 In the example of FIG. 1, the second lens group 51 includes, in order from the image sensor 60 side, a twelfth lens L12, a thirteenth lens L13, a fourteenth lens L14, a fifteenth lens L15, a sixteenth lens L16, And a seventeenth lens L17. The second lens group 51 includes at least one aspheric lens. In the second lens group 51, an aperture stop ST is provided between the seventeenth lens L17 and the optical path separation element 91.
　以上において、光路分離素子９１と反射型液晶素子４０の間と、光路分離素子９１と撮像素子６０の間には、それぞれ異なる屈折力を有するレンズ群である第１及び第２レンズ群１１，５１が配置され、投影画角よりも撮像画角の方が広くなっている。 In the above, the first and second lens groups 11 and 51, which are lens groups having different refractive powers, between the optical path separating element 91 and the reflective liquid crystal element 40 and between the optical path separating element 91 and the imaging element 60, respectively. Are arranged, and the imaging field angle is wider than the projection field angle.
　撮像素子６０は、投影体像を検出するＣＭＯＳ型のイメージセンサーである。撮像素子６０は、投影面ＳＣからの光線が、光路分離素子９１によって投影光学系１０の光路とは異なる方向に分離される光路上に配置されている。撮像素子６０の光電変換部である撮像面ＩＳ上には、撮像光学系５０によって形成された像が結像される。つまり、撮像素子６０の撮像面ＩＳ上には、ホワイトボードその他の投影体ＳＢ上の画像が縮小結像される。なお、撮像素子６０は、上述のＣＭＯＳ型のイメージセンサーに限るものでなく、ＣＣＤ等の他のものを適用したものであってもよい。撮像素子６０の受光面である撮像面ＩＳは、反射型液晶素子４０の画像表示面ＤＤと相似の矩形形状を有し、画像表示面ＤＤと同等、またはそれ以下の面積を有している。これにより、投影装置１００の小型化及び低コスト化を達成できる。 The image sensor 60 is a CMOS image sensor that detects a projected image. The image sensor 60 is disposed on an optical path in which the light beam from the projection surface SC is separated in a direction different from the optical path of the projection optical system 10 by the optical path separation element 91. An image formed by the imaging optical system 50 is formed on the imaging surface IS which is a photoelectric conversion unit of the imaging element 60. That is, an image on the whiteboard or other projection body SB is reduced and formed on the imaging surface IS of the imaging device 60. Note that the image pickup device 60 is not limited to the above-described CMOS type image sensor, and may be one to which another device such as a CCD is applied. The imaging surface IS, which is the light receiving surface of the imaging element 60, has a rectangular shape similar to the image display surface DD of the reflective liquid crystal element 40, and has an area equal to or less than that of the image display surface DD. Thereby, size reduction and cost reduction of the projection apparatus 100 can be achieved.
　撮像駆動回路６１は、ＹＵＶその他のデジタル画素信号を外部回路へ出力したり、制御回路８０から撮像素子６０を駆動するための電圧やクロック信号の供給を受けたりすることによって、撮像素子６０に像検出動作を行わせている。また、撮像駆動回路６１は、第１及び第２レンズ群１１，５１その他のレンズ群による合焦動作等も行わせている。 The image pickup drive circuit 61 outputs an image to the image pickup device 60 by outputting YUV or other digital pixel signals to an external circuit or receiving a voltage or a clock signal for driving the image pickup device 60 from the control circuit 80. The detection operation is performed. In addition, the imaging drive circuit 61 performs a focusing operation by the first and second lens groups 11 and 51 and other lens groups.
　画像処理部６２は、撮像駆動回路６１を用いて得た撮像データに対して色補正、階調補正、圧縮等の画像処理を行うことができ、取得した撮像データ又は処理後のデータを保管することもできる。また、画像処理部６２は、撮像素子６０で取得した被投影像の台形歪みを補正する。画像処理部６２では、不図示のデータ保管部から読み出されたレンズ補正データに基づいて画像信号に対して歪み補正処理を実行する。 The image processing unit 62 can perform image processing such as color correction, gradation correction, and compression on the imaging data obtained by using the imaging drive circuit 61, and stores the acquired imaging data or processed data. You can also. Further, the image processing unit 62 corrects the trapezoidal distortion of the projection image acquired by the image sensor 60. The image processing unit 62 performs distortion correction processing on the image signal based on lens correction data read from a data storage unit (not shown).
　反射光学系７０は、第３レンズ群９２から射出された投影光を反射させて投影面ＳＣに導くとともに、投影面ＳＣを含む領域からの光束を反射させて第３レンズ群９２へ導くものである。反射光学系７０は、第３レンズ群９２と投影面ＳＣとの間に配置され、少なくとも１枚の湾曲ミラー７０ａを有する。湾曲ミラー７０ａは、凸形状又は凹形状である場合、自由曲面形状や非球面形状を有する。また、反射光学系７０は、平板状であってもよい。図１の例において、反射光学系７０は、１枚の凸形状の湾曲ミラー７０ａを有する。なお、湾曲ミラー７０ａは、光路に使用されていない領域が切り欠かれていてもよい。 The reflection optical system 70 reflects the projection light emitted from the third lens group 92 and guides it to the projection surface SC, and reflects the light beam from the region including the projection surface SC to guide it to the third lens group 92. is there. The reflective optical system 70 is disposed between the third lens group 92 and the projection surface SC, and has at least one curved mirror 70a. When the curved mirror 70a has a convex shape or a concave shape, the curved mirror 70a has a free curved surface shape or an aspherical shape. The reflection optical system 70 may be flat. In the example of FIG. 1, the reflective optical system 70 has one convex curved mirror 70a. The curved mirror 70a may be cut out in a region not used in the optical path.
　制御回路８０は、これに組み込まれたプログラムや不図示の操作部からの指示に基づいて、画像駆動回路４１、撮像素子６０等を適宜動作させることができる。制御回路８０は、例えば外部から入力されたビデオ信号その他の信号に基づいて画像駆動回路４１に対して駆動信号や画像信号を出力し、反射型液晶素子４０に表示動作を行わせる。また、制御回路８０は、インターフェース８１を介して撮像素子６０と通信可能に接続されており、撮像駆動回路６１を動作させて撮像素子６０に撮像動作を行わせることができるとともに、制御信号や画像データの授受が可能となっている。制御回路８０は、撮像素子６０による撮像後には、撮像素子６０からインターフェース８１を介して画像信号を受け取る。この画像信号は、投影画像だけでなく、例えば手書き文字、発光ペンの軌跡等の追加画像を含む。制御回路８０は、受け取った画像信号から投影画像の状態を最適化することができるだけでなく、追加画像を抽出することができ、その抽出によって投影画像に追加画像を重畳させて記録することができる。 The control circuit 80 can appropriately operate the image driving circuit 41, the image sensor 60, and the like based on a program incorporated therein or an instruction from an operation unit (not shown). The control circuit 80 outputs a drive signal or an image signal to the image drive circuit 41 based on, for example, a video signal or other signal input from the outside, and causes the reflective liquid crystal element 40 to perform a display operation. The control circuit 80 is communicably connected to the imaging device 60 via the interface 81, and can operate the imaging driving circuit 61 to cause the imaging device 60 to perform an imaging operation, as well as control signals and images. Data can be exchanged. The control circuit 80 receives an image signal from the image sensor 60 via the interface 81 after the image pickup by the image sensor 60. This image signal includes not only the projected image but also an additional image such as a handwritten character or a light emitting pen locus. The control circuit 80 can not only optimize the state of the projection image from the received image signal, but also extract an additional image, and can superimpose and record the additional image on the projection image by the extraction. .
　光路分離素子９１は、投影光学系１０の内部であって、照明光を反射型液晶素子４０に導く光路とは離れた、異なる位置に配置され、投影面ＳＣ及びその周辺（矩形の外側領域）からの光束を投影光学系１０の光路から分離するものである。具体的には、光路分離素子９１は、投影の光路と撮像の光路とが直交するように分離する作用を有する。これにより、光路分離素子９１の大きさを最小限に抑えることができるので、投影装置１００の小型化に有利な構成となる。光路分離素子９１は、プリズムであってもよいし、ミラーであってもよい。また、光線を分離する手法に関して、迷光の影響を小さくできるという観点では、偏光分離を使用した偏光ビームスプリッターや偏光ミラーであることが望ましいが、これに限らず、単純に光線の透過率を制御したハーフミラーであってもよい。光路分離素子９１は投影光学系１０中にある。そのため、光路分離素子９１が大きくなると、その分レンズ間隔を空ける必要が出てくるため、光学性能の劣化を招くおそれがある。したがって、光路分離素子９１はできるだけ小さく構成することが望ましい。 The optical path separating element 91 is disposed in a different position inside the projection optical system 10 and away from the optical path for guiding the illumination light to the reflective liquid crystal element 40, and the projection surface SC and its periphery (rectangular outer region). Is separated from the optical path of the projection optical system 10. Specifically, the optical path separation element 91 has an action of separating the projection optical path and the imaging optical path so as to be orthogonal to each other. As a result, the size of the optical path separation element 91 can be minimized, and the projection apparatus 100 can be advantageously reduced in size. The optical path separation element 91 may be a prism or a mirror. In addition, with regard to the method of separating the light beam, from the viewpoint that the influence of stray light can be reduced, a polarization beam splitter or polarization mirror using polarization separation is desirable, but not limited to this, the light transmittance is simply controlled. It may be a half mirror. The optical path separating element 91 is in the projection optical system 10. For this reason, when the optical path separating element 91 becomes large, it is necessary to increase the lens interval accordingly, and there is a risk of deteriorating optical performance. Therefore, it is desirable to make the optical path separation element 91 as small as possible.
　第３レンズ群９２は、光路分離素子９１と反射光学系７０の間に配置され、投影及び撮像で共通して使用される。第３レンズ群９２は正の屈折力を有する。投影及び撮像で共通して使用される第３レンズ群９２が正の屈折力を有することにより、反射光学系７０を小さくすることができ、投影光学系１０ひいては投影装置１００の小型化を達成できる。 The third lens group 92 is disposed between the optical path separation element 91 and the reflection optical system 70, and is commonly used for projection and imaging. The third lens group 92 has a positive refractive power. Since the third lens group 92 commonly used for projection and imaging has a positive refractive power, the reflection optical system 70 can be made small, and the projection optical system 10 and thus the projection apparatus 100 can be reduced in size. .
　図１の例において、第３レンズ群９２は、反射型液晶素子４０側から順に、第７レンズＬ７と、第８レンズＬ８と、第９レンズＬ９と、第１０レンズＬ１０と、第１１レンズＬ１１とを有する。第３レンズ群９２は、非球面レンズを少なくとも１枚以上含む。なお、第３レンズ群９２のうち反射型液晶素子４０から遠いレンズ、例えば第１０及び第１１レンズＬ１０，Ｌ１１は、図示のように光路に使用されていない領域が切り欠かれていてもよい。 In the example of FIG. 1, the third lens group 92 includes, in order from the reflective liquid crystal element 40 side, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, and an eleventh lens L11. And have. The third lens group 92 includes at least one aspheric lens. In the third lens group 92, a lens far from the reflective liquid crystal element 40, for example, the tenth and eleventh lenses L10 and L11 may be cut out in a region not used in the optical path as shown.
　以上において、第１～第３レンズ群１１，５１，９２のいずれも、既述のように非球面レンズを少なくとも１枚以上含む。反射光学系７０及び第３レンズ群９２は投影及び撮像で共通して使用されるが、撮像光学系５０の画角は、投影光学系１０の画角と異なるものになるため、第１レンズ群１１と第２レンズ群５１とで補正すべき収差が異なることになる。第１～第３レンズ群１１，５１，９２に、それぞれ非球面レンズを用いることで、周辺解像力の向上、周辺歪みの低減を行うことができる。 In the above, each of the first to third lens groups 11, 51, 92 includes at least one aspherical lens as described above. Although the reflection optical system 70 and the third lens group 92 are commonly used for projection and imaging, the angle of view of the imaging optical system 50 is different from the angle of view of the projection optical system 10, and therefore the first lens group. 11 and the second lens group 51 have different aberrations to be corrected. By using an aspheric lens for each of the first to third lens groups 11, 51, and 92, it is possible to improve the peripheral resolution and reduce the peripheral distortion.
　上記投影装置１００において、反射型液晶素子４０と光路分離素子９１との間に配置された第１レンズ群１１と、撮像素子６０と光路分離素子９１との間に配置された第２レンズ群５１とは以下の条件式を満足する。
　１．０＜ｆＴｒ／ｆＩｍ＜１．３　　…　　（１）
ただし、値ｆＴｒは第１レンズ群１１の焦点距離であり、値ｆＩｍは第２レンズ群５１の焦点距離である。 In the projection apparatus 100, the first lens group 11 disposed between the reflective liquid crystal element 40 and the optical path separation element 91 and the second lens group 51 disposed between the imaging element 60 and the optical path separation element 91. Satisfies the following conditional expression.
1.0 <fTr / fIm <1.3 (1)
However, the value fTr is the focal length of the first lens group 11, and the value fIm is the focal length of the second lens group 51.
　条件式（１）は、反射型液晶素子４０と光路分離素子９１との間に配置された第１レンズ群１１の焦点距離と、撮像素子６０と光路分離素子９１との間に配置された第２レンズ群５１の焦点距離とを適切に設定するための条件式である。上述の通り、第１レンズ群１１と第２レンズ群５１とは異なる焦点距離を有しており、その焦点距離の差によって、投影光学系１０と撮像光学系５０との画角差が生じている。値ｆＴｒ／ｆＩｍが条件式（１）の下限を上回ることで、投影光学系１０よりも撮像光学系５０の方を広角にすることができるので、投影面ＳＣ面上で投影画像よりも外側に書かれた文字を撮像することができる。一方、条件式（１）の上限を下回ることで、撮像光学系５０が過度に広角になることがなくなり、第２レンズ群５１のレンズ枚数が増大するのを抑制することができる。また、撮像光学系５０が過度に広角にならないことで、周辺部の解像力低下や歪曲収差の増大を抑えることができる。 Conditional expression (1) indicates that the focal length of the first lens group 11 disposed between the reflective liquid crystal element 40 and the optical path separation element 91 and the first distance disposed between the imaging element 60 and the optical path separation element 91. This is a conditional expression for appropriately setting the focal length of the two lens group 51. As described above, the first lens group 11 and the second lens group 51 have different focal lengths, and a difference in the angle of view between the projection optical system 10 and the imaging optical system 50 occurs due to the difference in focal length. Yes. Since the value fTr / fIm exceeds the lower limit of the conditional expression (1), the imaging optical system 50 can be made wider than the projection optical system 10, so that it is outside the projection image on the projection plane SC plane. The written character can be imaged. On the other hand, by falling below the upper limit of conditional expression (1), the imaging optical system 50 is not excessively wide-angled, and an increase in the number of lenses in the second lens group 51 can be suppressed. Further, since the imaging optical system 50 does not become an excessively wide angle, it is possible to suppress a decrease in the resolution of the peripheral portion and an increase in distortion.
　本発明の別の側面によれば、上記投影装置１００は、以下の条件式を満足する。
　０．２＜ＰＲｚ／ＴＬ＜０．７　　…　　（２）
ただし、値ＰＲｚは反射型液晶素子４０（より詳細にはその表示面ＤＤ）から光路分離素子９１の反射型液晶素子４０側の面までの光軸ＯＡ上の距離であり、値ＴＬは反射型液晶素子４０から第３レンズ群９２の最も投影面ＳＣ側のレンズ（図１では第１１レンズＬ１１）の投影面ＳＣ側の面までの光軸ＯＡ上の距離である。 According to another aspect of the present invention, the projection apparatus 100 satisfies the following conditional expression.
0.2 <PRz / TL <0.7 (2)
However, the value PRz is the distance on the optical axis OA from the reflective liquid crystal element 40 (more specifically, the display surface DD) to the surface of the optical path separating element 91 on the reflective liquid crystal element 40 side, and the value TL is reflective type. This is the distance on the optical axis OA from the liquid crystal element 40 to the surface of the third lens group 92 closest to the projection surface SC (the eleventh lens L11 in FIG. 1) on the projection surface SC side.
　条件式（２）は、光路分離素子９１の位置を適切に設定するための条件式である。値ＰＲｚ／ＴＬが条件式（２）の下限を上回ることで、光路分離素子９１が反射型液晶素子４０側に近づきすぎることがなくなり、照明光学系２０からの強い光による迷光の影響を小さく抑えることができる。また、第１レンズ群１１や第２レンズ群５１の設置スペースが増えるので、良好に収差補正のされた投影光学系１０及び撮像光学系５０を構成することができる。一方、条件式（２）の上限を下回ることで、光路分離素子９１が投影面ＳＣ側に過度に近づいて配置されることがなくなり、第１レンズ群１１と第２レンズ群５１とを簡素化でき、投影光学系１０、ひいては投影装置１００の小型化を達成することができる。 Conditional expression (2) is a conditional expression for appropriately setting the position of the optical path separation element 91. When the value PRz / TL exceeds the lower limit of the conditional expression (2), the optical path separation element 91 is not too close to the reflective liquid crystal element 40 side, and the influence of stray light due to strong light from the illumination optical system 20 is kept small. be able to. Further, since the installation space for the first lens group 11 and the second lens group 51 is increased, it is possible to configure the projection optical system 10 and the imaging optical system 50 in which aberrations are favorably corrected. On the other hand, by falling below the upper limit of the conditional expression (2), the optical path separating element 91 is not disposed too close to the projection surface SC, and the first lens group 11 and the second lens group 51 are simplified. Thus, the size of the projection optical system 10 and thus the projection apparatus 100 can be reduced.
　既に説明したように、本投影装置１００において、投影光学系１０の中で光路分離素子９１より投影面ＳＣ側に配置されたレンズは、投影及び撮像で共通して使用される第３レンズ群９２である。したがって、光路分離素子９１が投影面ＳＣ側へ近づきすぎると、その分共通で使用できるレンズ群が少なくなり、第１レンズ群１１及び第２レンズ群５１の光学全長が長くなってしまう。第１レンズ群１１と第２レンズ群５１とは、異なる方向に配置されているため、第１レンズ群１１及び第２レンズ群５１の光学全長が大きくなると、その分投影装置が大きくなってしまう。そこで、条件式（２）の上限を下回ることにより、投影光学系１０、ひいては投影装置１００の小型化を図っている。 As already described, in the projection apparatus 100, the lens arranged in the projection optical system 10 closer to the projection plane SC than the optical path separation element 91 is commonly used for projection and imaging. It is. Therefore, if the optical path separation element 91 is too close to the projection surface SC, the number of lens groups that can be used in common is reduced, and the total optical length of the first lens group 11 and the second lens group 51 is increased. Since the first lens group 11 and the second lens group 51 are arranged in different directions, when the optical total length of the first lens group 11 and the second lens group 51 is increased, the projection apparatus is increased accordingly. . Accordingly, the projection optical system 10 and thus the projection apparatus 100 are reduced in size by falling below the upper limit of the conditional expression (2).
　以下、投影装置１００の使用状態について説明する。図２は、投影装置１００のうち投影光学系１０の光線経路を示しており、撮像光学系５０の光線経路については、図示を省略している。図２に示すように、投影装置１００からの投影光ＰＬは、投影面ＳＣのうち投影領域ＳＣ１（図７Ａ参照）に投影される。一方、投影面ＳＣからの反射光は、投影装置１００に入射する。投影装置１００に入射する反射光は、投影領域ＳＣ１より面積が大きい撮像領域ＳＣ２（図７Ａ参照）において反射された光となっている。投影装置１００は、インタラクティブな機能を有するプロジェクター用途を想定しており、インタラクティブ機能の１つに、手書き文字の画像認識が挙げられる。例えば、ホワイトボードへ資料を投影しつつ、投影像上又はその周辺に手書きでコメント等を追記する場合がある。本実施形態の投影装置１００において、投影面ＳＣのうち撮像される領域が、投影面ＳＣのうち投影光学系１０で投影されている領域を含めて広くなっているため、投影している範囲外の画像も撮影することができる。 Hereinafter, the usage state of the projection apparatus 100 will be described. FIG. 2 shows the light path of the projection optical system 10 in the projection apparatus 100, and the light path of the imaging optical system 50 is not shown. As shown in FIG. 2, the projection light PL from the projection device 100 is projected onto the projection area SC1 (see FIG. 7A) in the projection plane SC. On the other hand, the reflected light from the projection surface SC is incident on the projection device 100. The reflected light incident on the projection device 100 is light reflected in the imaging region SC2 (see FIG. 7A) having a larger area than the projection region SC1. The projection apparatus 100 is assumed to be a projector having an interactive function, and one of interactive functions is image recognition of handwritten characters. For example, while projecting a document on a whiteboard, a comment or the like may be added by handwriting on or around the projected image. In the projection apparatus 100 of the present embodiment, the area to be imaged in the projection plane SC is wide including the area projected by the projection optical system 10 in the projection plane SC, so it is out of the projected range. Can also be taken.
　上記投影装置１００では、投影光学系１０の内部に光路を分離するための光路分離素子９１を配置し、反射型液晶素子４０と撮像素子６０との間に光路分離素子９１を配置することで、投影光学系１０の一部（光路分離素子９１から投影面ＳＣ側に配置された第３レンズ群９２及び反射光学系７０）を投影及び撮像で共通して使用することができるので、投影光学系１０とは別に撮像光学系を搭載するよりも部品点数を削減し、結果として投影装置１００の小型化を達成できる。また、投影光学系１０と同等レベルの周辺解像力を有し、歪みが少ない撮像光学系５０を得ることができる。 In the projection apparatus 100, the optical path separation element 91 for separating the optical path is disposed inside the projection optical system 10, and the optical path separation element 91 is disposed between the reflective liquid crystal element 40 and the imaging element 60. Since a part of the projection optical system 10 (the third lens group 92 and the reflection optical system 70 disposed on the projection surface SC side from the optical path separation element 91) can be used in common for projection and imaging, the projection optical system The number of parts can be reduced as compared with the case where the image pickup optical system is mounted separately from 10, and as a result, the projector 100 can be downsized. In addition, it is possible to obtain the imaging optical system 50 that has a peripheral resolving power equivalent to that of the projection optical system 10 and has little distortion.
　ここで、反射型液晶素子４０に非常に近い位置に光路分離素子９１を配置してしまうと、反射型液晶素子４０を照明するための照明光学系２０からの強い光が撮像素子６０に入射してしまうリスクが高くなってしまう。そこで、反射型液晶素子４０の直前に照明光の光路となる偏光ビームスプリッター３０を配置し、偏光ビームスプリッター３０と光路分離素子９１との間に第１レンズ群１１を配置し、かつ光路分離素子９１と撮像素子６０との間に第２レンズ群５１を配置することで、光路分離素子９１の配置位置を照明光の光路となる偏光ビームスプリッター３０から遠ざけることができ、照明光に起因する迷光を抑制することができる。また、反射型液晶素子４０と光路分離素子９１との間に第１レンズ群１１を配置し、かつ光路分離素子９１と撮像素子６０との間に第２レンズ群５１を配置することによって、撮像の光路上において光路分離素子９１出射後に光路分離素子９１近傍で結像する再結像光学系とする必要がなくなるため、光学系を簡素化し小型化することができる。 Here, if the optical path separating element 91 is disposed at a position very close to the reflective liquid crystal element 40, strong light from the illumination optical system 20 for illuminating the reflective liquid crystal element 40 enters the imaging element 60. The risk of becoming higher. In view of this, the polarizing beam splitter 30 serving as the optical path of illumination light is disposed immediately before the reflective liquid crystal element 40, the first lens group 11 is disposed between the polarizing beam splitter 30 and the optical path separating element 91, and the optical path separating element. By arranging the second lens group 51 between 91 and the image sensor 60, the arrangement position of the optical path separation element 91 can be moved away from the polarization beam splitter 30 that is the optical path of the illumination light, and stray light caused by the illumination light Can be suppressed. In addition, the first lens group 11 is disposed between the reflective liquid crystal element 40 and the optical path separation element 91, and the second lens group 51 is disposed between the optical path separation element 91 and the imaging element 60, thereby capturing an image. It is not necessary to provide a re-imaging optical system that forms an image in the vicinity of the optical path separating element 91 after the light path separating element 91 is emitted on the optical path, so that the optical system can be simplified and miniaturized.
　さらに、反射型液晶素子４０と光路分離素子９１との間、及び光路分離素子９１と撮像素子６０との間にそれぞれ異なる屈折力の第１及び第２レンズ群１１，５１を配置し、撮像画角を投影画角よりも広くすることにより、投影面ＳＣ上での投影画像の外側領域まで撮像することができる。見方を変えれば、撮像素子６０の大きさを反射型液晶素子４０と同等かそれ以下にでき、光学系の大型化及びコスト増を抑制することができる。 Further, the first and second lens groups 11 and 51 having different refractive powers are arranged between the reflective liquid crystal element 40 and the optical path separating element 91 and between the optical path separating element 91 and the imaging element 60, respectively. By making the angle wider than the projection angle of view, it is possible to capture images up to the outer region of the projected image on the projection surface SC. In other words, the size of the image sensor 60 can be made equal to or smaller than that of the reflective liquid crystal element 40, and the increase in size and cost of the optical system can be suppressed.
〔実施例〕
　以下、本発明にかかる投影装置の実施例を示す。各実施例に使用する記号は下記の通りである。
Ｒ　　　：近軸曲率半径
Ｄ　　　：軸上面間隔
Ｎｄ　　：レンズ材料のｄ線に対する屈折率
νｄ　　：レンズ材料のアッベ数 〔Example〕
Embodiments of the projection apparatus according to the present invention will be described below. Symbols used in each example are as follows.
R: Paraxial radius of curvature D: Axial distance Nd: Refractive index νd of lens material with respect to d-line: Abbe number of lens material
　各実施例において、各面番号（Surf.N）の後に「＊」が記載されている面が非球面形状を有する面であり、非球面の形状は、面の頂点を原点とし、光軸方向にＺ軸（図１の座標とは必ずしも一致しない）をとり、光軸と垂直方向の高さをｈとして以下の「数１」で表す。その他、無限大を「ＩＮＦ」と表し、反射型液晶素子４０の表示面を「ＤＤ」と表し、開口絞りを「ＳＴ」と表し、光路分離素子９１の表面を「ＬＤ」と表し、湾曲ミラー７０ａ，７０ｂ，７０ｃの反射面を「ＭＲ」と表し、投影面を「ＳＣ」と表し、撮像素子６０の撮像面を「ＩＳ」で表している。
〔数１〕
Figure JPOXMLDOC01-appb-I000001
ただし、
Ａｉ：ｉ次の非球面係数
Ｒ　：曲率半径
Ｋ　：円錐定数 In each embodiment, the surface described with “*” after each surface number (Surf.N) is a surface having an aspherical shape, and the aspherical shape has the apex of the surface as the origin and the optical axis direction. The Z axis (not necessarily coincident with the coordinates in FIG. 1) is taken, and the height in the direction perpendicular to the optical axis is h, and is expressed by the following “Expression 1”. In addition, infinity is represented as “INF”, the display surface of the reflective liquid crystal element 40 is represented as “DD”, the aperture stop is represented as “ST”, the surface of the optical path separating element 91 is represented as “LD”, and a curved mirror The reflecting surfaces 70a, 70b, and 70c are represented as “MR”, the projection surface is represented as “SC”, and the imaging surface of the image sensor 60 is represented as “IS”.
[Equation 1]
Figure JPOXMLDOC01-appb-I000001
However,
Ai: i-order aspheric coefficient R: radius of curvature K: conic constant
　また、各面番号（Surf.N）の後に「＊＊」が記載されている面が非球面形状を有する面であり、自由曲面形状は、非球面形状と同じく面の頂点を原点とし、光軸方向にＺ軸をとり、光軸と垂直方向の高さをｈとして以下の「数２」で表す。
〔数２〕
Figure JPOXMLDOC01-appb-I000002
ただし、
Ｃｊ：ｘｍｙｎの係数
Ｒ　：曲率半径
Ｋ　：円錐定数又はコーニック定数 The surface with “**” after each surface number (Surf.N) is a surface having an aspherical shape, and the free-form surface shape is the same as the aspherical shape with the vertex of the surface as the origin, and light The Z axis is taken as the axial direction, and the height in the direction perpendicular to the optical axis is h.
[Equation 2]
Figure JPOXMLDOC01-appb-I000002
However,
Cj: x m y coefficient n R: radius of curvature K: conical constant or conic constant
　以下、本発明の投影装置に適用される投影光学系及び撮像光学系の具体的な実施例を説明する。
〔実施例１〕
　実施例１の投影光学系及び撮像光学系の基本的な仕様を以下に示す。
Ｆナンバー（投影光学系）：Ｆ２．８
Ｆナンバー（撮像光学系）：Ｆ４．０
画像表示素子の表示面サイズ：１３．５ｍｍ×７．６ｍｍ
撮像素子の撮像面サイズ：１３．５ｍｍ×７．６ｍｍ Hereinafter, specific examples of the projection optical system and the imaging optical system applied to the projection apparatus of the present invention will be described.
[Example 1]
The basic specifications of the projection optical system and the imaging optical system of Example 1 are shown below.
F number (projection optical system): F2.8
F number (imaging optical system): F4.0
Display surface size of image display element: 13.5 mm x 7.6 mm
Image pickup surface size of the image pickup device: 13.5 mm × 7.6 mm
　実施例１の投影光学系及び撮像光学系のレンズ面等のデータを以下の表１に示す。なお、表１の撮像光学系において、投影光学系と共通して使用される光路分離素子、第３レンズ群及び反射光学系（Surf.N：14～SC）については記載を省略している（実施例２も同様）。
　〔表１〕
＜投影光学系＞
Surf.N     R[mm]       D[mm]      Nd         νd
DD                     1.710
 1         INF        16.000     1.5163     64.1
 2         INF         5.000
 3*      27.214        7.552     1.5305     56.0
 4*     -28.130       11.026
 5     -216.833        3.629     1.7015     41.2
 6       12.028        5.499     1.6228     57.0
 7      -70.199        2.000
 8     -130.547        1.938     1.6989     30.1
 9       31.997        2.053     1.5182     58.9
10       68.417        2.075
11       31.770        2.226     1.4875     70.2
12      -56.932        1.538
13 ST      INF         9.276
14 LD      INF        35.000     1.8467     23.7
15 LD      INF         1.000
16      119.582        4.735     1.8044     39.5
17      -70.660        2.000
18       25.355        4.927     1.8467     23.7
19       23.339       10.055
20      -49.762        2.000     1.8467     23.7
21     -280.315       21.204
22*     -10.244        5.000     1.5305     56.0
23*      -7.800       11.605
24*      -7.654        5.548     1.5305     56.0
25*     -25.762       42.283
26** MR  24.942     -250.000
SC         INF
＜撮像光学系＞
Surf.N     R[mm]       D[mm]      Nd         νd
IS                     1.710
 1         INF        16.000     1.5163     64.1
 2         INF         5.000
 3*      27.041        6.375     1.5305     56.0
 4*     -27.342        9.515
 5     -187.514        2.000     1.7015     41.2
 6       15.199        3.758     1.6228     57.0
 7      -52.621        1.115
 8     -101.679        0.500     1.6989     30.1
 9       26.541        1.969     1.5182     58.9
10       52.689        2.000
11       32.540        1.891     1.4875     70.2
12      -43.721        2.000
13 ST      INF         9.276
（Surf.N：14～SCについては、投影光学系と共通） Table 1 below shows data such as lens surfaces of the projection optical system and the imaging optical system of Example 1. In the imaging optical system of Table 1, the description of the optical path separation element, the third lens group, and the reflection optical system (Surf. N: 14 to SC) used in common with the projection optical system is omitted ( The same applies to Example 2).
[Table 1]
<Projection optics>
Surf.N R [mm] D [mm] Nd νd
DD 1.710
1 INF 16.000 1.5163 64.1
2 INF 5.000
3 * 27.214 7.552 1.5305 56.0
4 * -28.130 11.026
5 -216.833 3.629 1.7015 41.2
6 12.028 5.499 1.6228 57.0
7 -70.199 2.000
8 -130.547 1.938 1.6989 30.1
9 31.997 2.053 1.5182 58.9
10 68.417 2.075
11 31.770 2.226 1.4875 70.2
12 -56.932 1.538
13 ST INF 9.276
14 LD INF 35.000 1.8467 23.7
15 LD INF 1.000
16 119.582 4.735 1.8044 39.5
17 -70.660 2.000
18 25.355 4.927 1.8467 23.7
19 23.339 10.055
20 -49.762 2.000 1.8467 23.7
21 -280.315 21.204
22 * -10.244 5.000 1.5305 56.0
23 * -7.800 11.605
24 * -7.654 5.548 1.5305 56.0
25 * -25.762 42.283
26 ** MR 24.942 -250.000
SC INF
<Imaging optical system>
Surf.N R [mm] D [mm] Nd νd
IS 1.710
1 INF 16.000 1.5163 64.1
2 INF 5.000
3 * 27.041 6.375 1.5305 56.0
4 * -27.342 9.515
5 -187.514 2.000 1.7015 41.2
6 15.199 3.758 1.6228 57.0
7 -52.621 1.115
8 -101.679 0.500 1.6989 30.1
9 26.541 1.969 1.5182 58.9
10 52.689 2.000
11 32.540 1.891 1.4875 70.2
12 -43.721 2.000
13 ST INF 9.276
(Surf.N: 14 to SC are common with the projection optical system)
　実施例１の投影光学系及び撮像光学系に含まれる非球面の非球面係数を以下の表２に示す。なお、これ以降（表のレンズデータを含む）において、１０のべき乗数（たとえば２．５×１０－０２）をＥ（たとえば２．５Ｅ－０２）を用いて表すものとする。
〔表２〕
第3面（投影光学系）
K=0.0000E+00, A4=-8.6920E-06, A6=-2.8456E-08, A8=2.3815E-11, 
A10=1.3399E-12, A12=-9.5667E-16
第3面（撮像光学系）
K=0.0000E+00, A4=-1.2067E-05, A6=1.8741E-08, A8=-3.8763E-10, 
A10=1.1703E-12, A12=-1.5482E-15
第4面（投影光学系）
K=0.0000E+00, A4=2.7756E-05, A6=-6.8355E-08, A8=2.9753E-10, 
A10=3.2797E-13, A12=1.9888E-16
第4面（撮像光学系）
K=0.0000E+00, A4=3.4470E-05, A6=-7.4901E-08, A8=2.8389E-10, 
A10=-1.3924E-12, A12=2.7251E-15
第22面
K=-7.1737E-01, A4=9.9725E-05, A6=-1.4471E-06, A8=8.4400E-09, 
A10=-2.3754E-11, A12=2.4601E-14
第23面
K=-8.9335E-01, A4=1.5669E-04, A6=-1.2119E-06, A8=5.5428E-09, 
A10=-1.0861E-11, A12=8.1071E-15
第24面
K=-3.5605E+00, A4=-4.0390E-04, A6=2.1662E-06, A8=-7.2387E-09, 
A10=1.3009E-11, A12=-***1E-15
第25面
K=-6.0201E-05, A4=-1.1138E-04, A6=3.6668E-07, A8=-7.4039E-10, 
A10=7.9105E-13, A12=-3.6903E-16 Table 2 below shows the aspheric coefficients of the aspheric surfaces included in the projection optical system and the imaging optical system of Example 1. In the following (including the lens data in the table), a power of 10 (for example, 2.5 × 10 −02 ) is expressed by using E (for example, 2.5E-02).
[Table 2]
Third surface (projection optical system)
K = 0.0000E + 00, A4 = -8.6920E-06, A6 = -2.8456E-08, A8 = 2.3815E-11,
A10 = 1.3399E-12, A12 = -9.5667E-16
Third surface (imaging optics)
K = 0.0000E + 00, A4 = -1.2067E-05, A6 = 1.8741E-08, A8 = -3.8763E-10,
A10 = 1.1703E-12, A12 = -1.5482E-15
4th surface (projection optical system)
K = 0.0000E + 00, A4 = 2.7756E-05, A6 = -6.8355E-08, A8 = 2.9753E-10,
A10 = 3.2797E-13, A12 = 1.9888E-16
4th surface (imaging optics)
K = 0.0000E + 00, A4 = 3.4470E-05, A6 = -7.4901E-08, A8 = 2.8389E-10,
A10 = -1.3924E-12, A12 = 2.7251E-15
22nd page
K = -7.1737E-01, A4 = 9.9725E-05, A6 = -1.4471E-06, A8 = 8.4400E-09,
A10 = -2.3754E-11, A12 = 2.4601E-14
23rd page
K = -8.9335E-01, A4 = 1.5669E-04, A6 = -1.2119E-06, A8 = 5.5428E-09,
A10 = -1.0861E-11, A12 = 8.1071E-15
24th page
K = -3.5605E + 00, A4 = -4.0390E-04, A6 = 2.1662E-06, A8 = -7.2387E-09,
A10 = 1.3009E-11, A12 = -***1E-15
25th page
K = -6.0201E-05, A4 = -1.1138E-04, A6 = 3.6668E-07, A8 = -7.4039E-10,
A10 = 7.9105E-13, A12 = -3.6903E-16
　実施例１の投影光学系及び撮像光学系で共通に使用される湾曲ミラー７０ａの自由曲面係数を以下の表３に示す。なお、自由曲面係数の表中の「＊」は積を表し、「＊＊」はべき乗を表すものとする（以降の実施例も同様）。
〔表３〕
Figure JPOXMLDOC01-appb-I000003
Table 3 below shows the free-form surface coefficients of the curved mirror 70a commonly used in the projection optical system and the imaging optical system of Example 1. In the table of free-form surface coefficients, “*” represents a product, and “**” represents a power (the same applies to the following examples).
[Table 3]
Figure JPOXMLDOC01-appb-I000003
　図３は、実施例１の投影光学系１０Ａの断面図である。具体的には、反射型液晶素子４０から反射光学系７０までの断面図である。図４は、実施例１の撮像光学系５０Ａの断面図である、具体的には、撮像素子６０から反射光学系７０までの断面図である。 FIG. 3 is a sectional view of the projection optical system 10A of the first embodiment. Specifically, it is a sectional view from the reflective liquid crystal element 40 to the reflective optical system 70. FIG. 4 is a cross-sectional view of the imaging optical system 50A of the first embodiment, specifically, a cross-sectional view from the imaging element 60 to the reflection optical system 70.
　実施例１の投影光学系１０Ａは、偏光ビームスプリッター３０と、第１レンズ群１１と、光路分離素子９１と、第３レンズ群９２と、反射光学系７０とを有する。また、撮像光学系５０Ａは、平行平板Ｆ２と、第２レンズ群５１と、光路分離素子９１と、第３レンズ群９２と、反射光学系７０とを有する。第１レンズ群１１は、画像表示素子である反射型液晶素子４０側から順に、第１レンズＬ１と、第２レンズＬ２と、第３レンズＬ３と、第４レンズＬ４と、第５レンズＬ５と、第６レンズＬ６とを有する。第３レンズ群９２は、反射型液晶素子４０側から順に、第７レンズＬ７と、第８レンズＬ８と、第９レンズＬ９と、第１０レンズＬ１０と、第１１レンズＬ１１とを有する。第２レンズ群５１は、撮像素子６０側から順に、第１２レンズＬ１２と、第１３レンズＬ１３と、第１４レンズＬ１４と、第１５レンズＬ１５と、第１６レンズＬ１６と、第１７レンズＬ１７とを有する。これらのうち、第１、第１０、第１１、及び第１２レンズＬ１，Ｌ１０，Ｌ１１，Ｌ１２は非球面レンズである。反射光学系７０は、屈折力を有し、投影光学系１０Ａの光軸ＯＡに近い側では凸面状の自由曲面タイプの湾曲ミラー７０ａである。また、符号Ｆ１は、画像表示素子を反射型液晶素子４０の前面に配置された偏光ビームスプリッター３０に相当する平行平板を示す。画像表示素子の方式によっては、平行平板Ｆ１は必要ない場合もあるが、平行平板Ｆ１は屈折力を持たないため、平行平板Ｆ１以降の光学系は変えずに平行平板Ｆ１を除いた構成とすることもできる。その場合には、画像表示素子と第１レンズＬ１との空気間隔を最適な位置に設定すればよい。また、符号Ｆ２は、例えば光学的ローパスフィルター、ＩＲカットフィルター、撮像素子６０のシールガラス等を含むことを想定した平行平板である。 The projection optical system 10A of Example 1 includes a polarization beam splitter 30, a first lens group 11, an optical path separation element 91, a third lens group 92, and a reflection optical system 70. Further, the imaging optical system 50A includes a parallel plate F2, a second lens group 51, an optical path separation element 91, a third lens group 92, and a reflection optical system 70. The first lens group 11 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5 in order from the reflective liquid crystal element 40 that is an image display element. And a sixth lens L6. The third lens group 92 includes, in order from the reflective liquid crystal element 40 side, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, and an eleventh lens L11. The second lens group 51 includes, in order from the image sensor 60 side, a twelfth lens L12, a thirteenth lens L13, a fourteenth lens L14, a fifteenth lens L15, a sixteenth lens L16, and a seventeenth lens L17. Have. Among these, the first, tenth, eleventh, and twelfth lenses L1, L10, L11, and L12 are aspherical lenses. The reflective optical system 70 has a refractive power, and is a convex free-form curved mirror 70a on the side close to the optical axis OA of the projection optical system 10A. Reference numeral F <b> 1 indicates a parallel plate corresponding to the polarizing beam splitter 30 in which the image display element is disposed in front of the reflective liquid crystal element 40. Depending on the type of image display element, the parallel plate F1 may not be necessary. However, since the parallel plate F1 does not have refractive power, the optical system after the parallel plate F1 is not changed and the parallel plate F1 is excluded. You can also. In that case, the air space between the image display element and the first lens L1 may be set to an optimum position. Reference numeral F2 is a parallel plate that is assumed to include, for example, an optical low-pass filter, an IR cut filter, a seal glass of the image sensor 60, and the like.
　図１では、撮像光学系５０を光路分離素子９１により、直交する方向に折り曲げた位置に配置しているが、逆に投影光学系１０を光路分離素子９１により、直交する方向に折り曲げた位置に配置してもよい。 In FIG. 1, the imaging optical system 50 is arranged at a position bent in the orthogonal direction by the optical path separation element 91, but conversely, the projection optical system 10 is in a position bent in the orthogonal direction by the optical path separation element 91. You may arrange.
　図５Ａ及び５Ｂは、投影光学系１０Ａの投影面ＳＣ上でのＭＴＦ（Modulation Transfer Function）特性図である。図５Ａは、図７Ａに示す投影領域ＳＣ１のうち評価位置ＦＰ１～ＦＰ３のＭＴＦ特性図であり、図５Ｂは、図７Ａに示す投影領域ＳＣ１のうち評価位置ＦＰ４～ＦＰ６のＭＴＦ特性図である。また、図６Ａ及び６Ｂは、撮像光学系５０Ａの撮像素子６０の撮像面ＩＳ上でのＭＴＦ特性図である。図６Ａは、図７Ｂに示す撮像領域ＳＣ２のうち評価位置ＦＰ１～ＦＰ３のＭＴＦ特性図であり、図６Ｂは、図７Ｂに示す撮像領域ＳＣ２のうち評価位置ＦＰ４～ＦＰ６のＭＴＦ特性図である（実施例２も同様）。なお、投影領域ＳＣ１は、実際に投影画像が映る範囲であり、投影面ＳＣ上での撮像領域ＳＣ２の面積は、投影領域ＳＣ１の面積よりも大きくなっている。図５Ａ、５Ｂ、６Ａ、及び６Ｂ中のＦｉ－Ｘ（ｉ＝１～６）は、Ｆｉの位置での水平方向解像力を示し、Ｆｉ－Ｙ（ｉ＝１～６）は、Ｆｉの位置での垂直方向解像力を示す。ＭＴＦを計算する上での波長ウェイトは以下の通りである（実施例２も同様）。
〔波長ウェイト〕
波長　　　　　重み
656.3nm　　　34
587.6nm　　　63
546.1nm　　　100
486.1nm　　　83
435.8nm　　　26
404.7nm　　　8 5A and 5B are MTF (Modulation Transfer Function) characteristic diagrams on the projection surface SC of the projection optical system 10A. 5A is an MTF characteristic diagram of the evaluation positions FP1 to FP3 in the projection region SC1 shown in FIG. 7A, and FIG. 5B is an MTF characteristic diagram of the evaluation positions FP4 to FP6 in the projection region SC1 shown in FIG. 7A. 6A and 6B are MTF characteristics diagrams on the imaging surface IS of the imaging element 60 of the imaging optical system 50A. 6A is an MTF characteristic diagram of the evaluation positions FP1 to FP3 in the imaging region SC2 shown in FIG. 7B, and FIG. 6B is an MTF characteristic diagram of the evaluation positions FP4 to FP6 in the imaging region SC2 shown in FIG. 7B. The same applies to Example 2). Note that the projection area SC1 is a range in which a projection image is actually shown, and the area of the imaging area SC2 on the projection surface SC is larger than the area of the projection area SC1. In FIGS. 5A, 5B, 6A, and 6B, Fi-X (i = 1 to 6) indicates the horizontal resolving power at the position of Fi, and Fi-Y (i = 1 to 6) is the position of Fi. The vertical resolution of The wavelength weights for calculating the MTF are as follows (the same applies to the second embodiment).
[Wavelength weight]
Wavelength weight
656.3nm 34
587.6nm 63
546.1nm 100
486.1nm 83
435.8nm 26
404.7nm 8
〔実施例２〕
　実施例２の投影光学系及び撮像光学系の基本的な仕様を以下に示す。
Ｆナンバー（投影光学系）：Ｆ２．８
Ｆナンバー（撮像光学系）：Ｆ４．０
画像表示素子の表示面サイズ：１３．５ｍｍ×７．６ｍｍ
撮像素子の撮像面サイズ：１３．５ｍｍ×７．６ｍｍ [Example 2]
The basic specifications of the projection optical system and the imaging optical system of Example 2 are shown below.
F number (projection optical system): F2.8
F number (imaging optical system): F4.0
Display surface size of image display element: 13.5 mm x 7.6 mm
Image pickup surface size of the image pickup device: 13.5 mm × 7.6 mm
　実施例２の投影光学系及び撮像光学系のレンズ面等のデータを以下の表４に示す。
　〔表４〕
＜投影光学系＞
Surf.N     R[mm]       D[mm]      Nd         νd
DD                     1.400
 1         INF        13.660     1.5187     64.0
 2         INF         1.000
 3       40.496       15.914     1.8550     23.5
 4      -98.169        8.972
 5       81.768        3.227     1.4891     70.0
 6      -42.587        2.980     1.8550     23.5
 7       23.843        1.542
 8       18.467        4.833     1.4891     70.0
 9      -25.110        3.612     1.8550     23.5
10      -78.485        1.646
11*      32.427        4.310     1.6347     23.9
12*     -84.647        1.846
13 ST      INF        17.207
14 LD      INF        25.000     1.8550     23.5
15 LD      INF         1.000
16      118.247        4.534     1.8550     23.5
17      264.439        1.000
18       30.572       10.216     1.4891     70.0
19      -55.018        3.100
20*     -25.858        3.000     1.5305     56.0
21*      96.824      120.000
22* MR  -50.380      -92.418
23* MR  -66.741      250.000
SC         INF
＜撮像光学系＞
Surf.N     R[mm]       D[mm]      Nd         νd
IS                     1.400
 1         INF         5.000     1.5187     64.0
 2         INF         1.000
 3       39.566       23.993     1.8550     23.5
 4       69.103        6.352
 5       27.170        2.500     1.4891     70.0
 6     -717.494        2.500     1.8550     23.5
 7       28.123        1.144
 8       21.495        4.463     1.4891     70.0
 9      -29.510        1.200     1.8550     23.5
10      -56.405        1.000
11*      28.665        6.527     1.6347     23.9
12*    -442.669        1.762
13 ST      INF        17.207
（Surf.N：14～SCについては、投影光学系と共通） Table 4 below shows data such as lens surfaces of the projection optical system and the imaging optical system of Example 2.
[Table 4]
<Projection optics>
Surf.N R [mm] D [mm] Nd νd
DD 1.400
1 INF 13.660 1.5187 64.0
2 INF 1.000
3 40.496 15.914 1.8550 23.5
4 -98.169 8.972
5 81.768 3.227 1.4891 70.0
6 -42.587 2.980 1.8550 23.5
7 23.843 1.542
8 18.467 4.833 1.4891 70.0
9 -25.110 3.612 1.8550 23.5
10 -78.485 1.646
11 * 32.427 4.310 1.6347 23.9
12 * -84.647 1.846
13 ST INF 17.207
14 LD INF 25.000 1.8550 23.5
15 LD INF 1.000
16 118.247 4.534 1.8550 23.5
17 264.439 1.000
18 30.572 10.216 1.4891 70.0
19 -55.018 3.100
20 * -25.858 3.000 1.5305 56.0
21 * 96.824 120.000
22 * MR -50.380 -92.418
23 * MR -66.741 250.000
SC INF
<Imaging optical system>
Surf.N R [mm] D [mm] Nd νd
IS 1.400
1 INF 5.000 1.5187 64.0
2 INF 1.000
3 39.566 23.993 1.8550 23.5
4 69.103 6.352
5 27.170 2.500 1.4891 70.0
6 -717.494 2.500 1.8550 23.5
7 28.123 1.144
8 21.495 4.463 1.4891 70.0
9 -29.510 1.200 1.8550 23.5
10 -56.405 1.000
11 * 28.665 6.527 1.6347 23.9
12 * -442.669 1.762
13 ST INF 17.207
(Surf.N: 14 to SC are common with the projection optical system)
　実施例２の投影光学系及び撮像光学系に含まれる非球面の非球面係数を以下の表５に示す。
〔表５〕
第11面（投影光学系）
K=4.7511E+00, A4=2.4031E-06, A6=1.7035E-07, A8=-4.5366E-10, 
A10=1.8472E-11, A12=0.0000E+00
第11面（撮像光学系）
K=3.9483E+00, A4=-6.3120E-07, A6=5.3761E-08, A8=-7.6708E-10, 
A10=8.2865E-12, A12=0.0000E+00
第12面（投影光学系）
K=5.7947E+00, A4=4.1130E-05, A6=3.0879E-07, A8=-9.1413E-10, 
A10=3.5890E-11, A12=0.0000E+00
第12面（撮像光学系）
K=5.0000E+01, A4=4.8738E-05, A6=2.6678E-07, A8=-2.6813E-09, 
A10=5.1110E-11, A12=0.0000E+00
第20面
K=0.0000E+00, A4=6.1292E-06, A6=2.8576E-08, A8=9.6727E-12, 
A10=-8.4770E-14, A12=1.0227E-16
第21面
K=0.0000E+00, A4=4.2449E-06, A6=1.6633E-08, A8=-2.5704E-11, 
A10=7.4961E-14, A12=-8.5651E-17
第22面
K=0.0000E+00, A3=-2.5633E-06, A4=1.7991E-06, A5=-1.8257E-08, 
A6=1.7290E-10, A7=0.0000E+00, A8=5.0452E-14, A9=0.0000E+00, 
A10=-1.3729E-17, A11=0.0000E+00, A12=4.2597E-21
第23面
K=-1.1236E+01, A3=9.0737E-06, A4=-3.0593E-08, A5=-1.1552E-10, 
A6=-6.6922E-13, A7=0.0000E+00, A8=1.1620E-16, A9=0.0000E+00, 
A10=-3.2741E-21, A11=0.0000E+00, A12=0.0000E+00 Table 5 below shows the aspheric coefficients of the aspheric surfaces included in the projection optical system and the imaging optical system of Example 2.
[Table 5]
11th surface (projection optics)
K = 4.7511E + 00, A4 = 2.4031E-06, A6 = 1.7035E-07, A8 = -4.5366E-10,
A10 = 1.8472E-11, A12 = 0.0000E + 00
11th surface (imaging optical system)
K = 3.9483E + 00, A4 = -6.3120E-07, A6 = 5.3761E-08, A8 = -7.6708E-10,
A10 = 8.2865E-12, A12 = 0.0000E + 00
12th surface (projection optics)
K = 5.7947E + 00, A4 = 4.1130E-05, A6 = 3.0879E-07, A8 = -9.1413E-10,
A10 = 3.5890E-11, A12 = 0.0000E + 00
12th surface (imaging optics)
K = 5.0000E + 01, A4 = 4.8738E-05, A6 = 2.6678E-07, A8 = -2.6813E-09,
A10 = 5.1110E-11, A12 = 0.0000E + 00
20th page
K = 0.0000E + 00, A4 = 6.1292E-06, A6 = 2.8576E-08, A8 = 9.6727E-12,
A10 = -8.4770E-14, A12 = 1.0227E-16
21st page
K = 0.0000E + 00, A4 = 4.2449E-06, A6 = 1.6633E-08, A8 = -2.5704E-11,
A10 = 7.4961E-14, A12 = -8.5651E-17
22nd page
K = 0.0000E + 00, A3 = -2.5633E-06, A4 = 1.7991E-06, A5 = -1.8257E-08,
A6 = 1.7290E-10, A7 = 0.0000E + 00, A8 = 5.0452E-14, A9 = 0.0000E + 00,
A10 = -1.3729E-17, A11 = 0.0000E + 00, A12 = 4.2597E-21
23rd page
K = -1.1236E + 01, A3 = 9.0737E-06, A4 = -3.0593E-08, A5 = -1.1552E-10,
A6 = -6.6922E-13, A7 = 0.0000E + 00, A8 = 1.1620E-16, A9 = 0.0000E + 00,
A10 = -3.2741E-21, A11 = 0.0000E + 00, A12 = 0.0000E + 00
　図８は、実施例２の投影光学系１０Ｂの断面図である。具体的には、反射型液晶素子４０から反射光学系７０までの断面図である。図９は、実施例２の撮像光学系５０Ｂの断面図である、具体的には、撮像素子６０から反射光学系７０までの断面図である。 FIG. 8 is a sectional view of the projection optical system 10B of the second embodiment. Specifically, it is a sectional view from the reflective liquid crystal element 40 to the reflective optical system 70. FIG. 9 is a cross-sectional view of the image pickup optical system 50B of the second embodiment, specifically, a cross-sectional view from the image pickup element 60 to the reflection optical system 70.
　実施例２の投影光学系１０Ｂは、偏光ビームスプリッター３０と、第１レンズ群１１と、光路分離素子９１と、第３レンズ群９２と、反射光学系７０とを有する。また、撮像光学系５０Ｂは、平行平板Ｆ２と、第２レンズ群５１と、光路分離素子９１と、第３レンズ群９２と、反射光学系７０とを有する。第１レンズ群１１は、画像表示素子である反射型液晶素子４０側から順に、第１レンズＬ１と、第２レンズＬ２と、第３レンズＬ３と、第４レンズＬ４と、第５レンズＬ５と、第６レンズＬ６とを有する。第３レンズ群９２は、反射型液晶素子４０側から順に、第７レンズＬ７と、第８レンズＬ８と、第９レンズＬ９とを有する。第２レンズ群５１は、撮像素子６０側から順に、第１０レンズＬ１０と、第１１レンズＬ１１と、第１２レンズＬ１２と、第１３レンズＬ１３と、第１４レンズＬ１４と、第１５レンズＬ１５とを有する。これらのうち、第６、第９、及び第１５レンズＬ６，Ｌ９，Ｌ１５は非球面レンズである。反射光学系７０は、屈折力を有する非球面タイプの湾曲ミラー７０ｂと、非球面タイプの湾曲ミラー７０ｃとを有する。 The projection optical system 10B of Example 2 includes a polarization beam splitter 30, a first lens group 11, an optical path separation element 91, a third lens group 92, and a reflection optical system 70. The imaging optical system 50 </ b> B includes a parallel plate F <b> 2, a second lens group 51, an optical path separation element 91, a third lens group 92, and a reflection optical system 70. The first lens group 11 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5 in order from the reflective liquid crystal element 40 that is an image display element. And a sixth lens L6. The third lens group 92 includes, in order from the reflective liquid crystal element 40 side, a seventh lens L7, an eighth lens L8, and a ninth lens L9. The second lens group 51 includes, in order from the image sensor 60 side, a tenth lens L10, an eleventh lens L11, a twelfth lens L12, a thirteenth lens L13, a fourteenth lens L14, and a fifteenth lens L15. Have. Among these, the sixth, ninth, and fifteenth lenses L6, L9, and L15 are aspheric lenses. The reflective optical system 70 includes an aspheric type curved mirror 70b having refractive power and an aspheric type curved mirror 70c.
　図１０Ａ及び１０Ｂは、投影光学系１０Ｂの投影面ＳＣ上でのＭＴＦ特性図である。また、図１１Ａ及び１１Ｂは、撮像光学系５０Ｂの撮像素子６０の撮像面ＩＳ上でのＭＴＦ特性図である。 10A and 10B are MTF characteristics diagrams on the projection plane SC of the projection optical system 10B. 11A and 11B are MTF characteristics diagrams on the imaging surface IS of the imaging element 60 of the imaging optical system 50B.
　以下の表６は、参考のため、条件式（１）及び（２）に対応する実施例１及び２の値をまとめたものである。
〔表６〕
Figure JPOXMLDOC01-appb-I000004
Table 6 below summarizes the values of Examples 1 and 2 corresponding to the conditional expressions (1) and (2) for reference.
[Table 6]
Figure JPOXMLDOC01-appb-I000004
　以上、実施形態や実施例に即して本発明を説明したが、本発明は、上記実施形態等に限定されるものではない。例えば、上記実施形態において、投影光学系１０や撮像光学系５０の具体的な構成は、図示のものに限らず用途等に応じて適宜変更することができる。 As mentioned above, although this invention was demonstrated according to embodiment and an Example, this invention is not limited to the said embodiment etc. For example, in the above embodiment, the specific configurations of the projection optical system 10 and the imaging optical system 50 are not limited to those shown in the drawings, and can be changed as appropriate according to the application.
　また、上記実施形態において、第１及び第２レンズ群１１，５１のレンズの枚数を同じにしたが、異なる枚数にしてもよい。また、第１～第３レンズ群１１，５１，９２を構成するレンズは、１枚以上であればよい。また、構成するレンズの曲率半径や芯厚も適宜変更することができる。また、反射光学系７０を用いないものであってもよい。 In the above embodiment, the number of lenses in the first and second lens groups 11 and 51 is the same, but it may be different. Further, the number of lenses constituting the first to third lens groups 11, 51, 92 may be one or more. Further, the radius of curvature and the core thickness of the constituting lens can be appropriately changed. Further, the reflection optical system 70 may not be used.
　また、上記実施形態において、画像表示素子としては、ＬＣＯＳ等の反射型液晶素子４０に限らず、マイクロミラーからなるマイクロミラーデバイス、透過型のＬＣＤ等を用いることができる。この場合、偏光ビームスプリッター３０は、それぞれに適合する光学系に変更する。 In the above embodiment, the image display element is not limited to the reflective liquid crystal element 40 such as LCOS, but a micromirror device including a micromirror, a transmissive LCD, or the like can be used. In this case, the polarization beam splitter 30 is changed to an optical system suitable for each.
　また、上記実施形態において、照明光学系２０の光源としては、ＬＥＤに限らず、水銀ランプ、レーザー等を用いることができ、これらの光源を同種又は異種で組み合わせることもできる。特に、ＬＥＤやレーザーを光源とする場合、赤色・緑色・青色の光源数は出力に合わせ任意に組み合わせても良い。また、合波するための光学系を追加し、白色又は特定色に関して複数の光源を配置することで明るさを上げることもできる。 In the above embodiment, the light source of the illumination optical system 20 is not limited to the LED, and a mercury lamp, a laser, or the like can be used, and these light sources can be used in the same type or different types. In particular, when LEDs or lasers are used as light sources, the number of red, green, and blue light sources may be arbitrarily combined according to the output. Further, it is possible to increase the brightness by adding an optical system for multiplexing and arranging a plurality of light sources for white or a specific color.

Claims (7)

  1. 　照明光により照明された画像表示素子から得られる像を拡大して投影面上に投影する投影光学系を有する投影装置であって、
    　前記投影光学系の内部の前記照明光の光路部とは異なる位置に光路を分離するための光路分離素子が配置され、
    　前記光路分離素子によって前記投影面からの光線が前記投影光学系の光路とは異なる方向に分離された光路上に撮像素子が配置され、
    　前記光路分離素子及び前記画像表示素子の間と、前記光路分離素子及び前記撮像素子の間とには、互いに異なる屈折力を有するレンズ群がそれぞれ配置され、
    　投影画角よりも撮像画角が広い、投影装置。     A projection apparatus having a projection optical system for enlarging and projecting an image obtained from an image display element illuminated by illumination light onto a projection plane,
    An optical path separation element for separating the optical path at a position different from the optical path portion of the illumination light inside the projection optical system;
    An imaging element is disposed on the optical path in which the light beam from the projection surface is separated in a direction different from the optical path of the projection optical system by the optical path separation element,
    Lens groups having different refractive powers are disposed between the optical path separation element and the image display element and between the optical path separation element and the imaging element, respectively.
    A projection device with a wider imaging field angle than the projection field angle.
  2. 　前記画像表示素子と前記光路分離素子との間に配置されたレンズ群を第１レンズ群とし、前記撮像素子と前記光路分離素子との間に配置されたレンズ群を第２レンズ群とし、前記光路分離素子より前記投影面側に配置されたレンズ群を第３レンズ群としたとき、前記第１レンズ群と前記第２レンズ群が以下の条件式を満足する、請求項１に記載の投影装置。
    　１．０＜ｆＴｒ／ｆＩｍ＜１．３　　…　　（１）
    ただし、
    ｆＴｒ：前記第１レンズ群の焦点距離
    ｆＩｍ：前記第２レンズ群の焦点距離     The lens group disposed between the image display element and the optical path separation element is a first lens group, the lens group disposed between the imaging element and the optical path separation element is a second lens group, 2. The projection according to claim 1, wherein the first lens group and the second lens group satisfy the following conditional expression when the lens group disposed closer to the projection surface than the optical path separation element is a third lens group. apparatus.
    1.0 <fTr / fIm <1.3 (1)
    However,
    fTr: focal length of the first lens group fIm: focal length of the second lens group
  3. 前記光路分離素子より前記投影面側に配置されたレンズ群を第３レンズ群としたとき、以下の条件式を満足する、請求項１及び２のいずれか一項に記載の投影装置。
    　０．２＜ＰＲｚ／ＴＬ＜０．７　　…　　（２）
    ただし、
    ＰＲｚ：前記画像表示素子から前記光路分離素子の前記画像表示素子側の面までの光軸上の距離
    ＴＬ：前記画像表示素子から前記第３レンズ群の最も投影面側のレンズの投影面側の面までの光軸上の距離     3. The projection apparatus according to claim 1, wherein the following conditional expression is satisfied when the third lens group is a lens group disposed closer to the projection surface than the optical path separation element.
    0.2 <PRz / TL <0.7 (2)
    However,
    PRz: distance on the optical axis from the image display element to the surface of the optical path separation element on the image display element side TL: the distance from the image display element to the projection surface side of the lens closest to the projection surface of the third lens group Distance on the optical axis to the surface
  4. 　前記光路分離素子は、投影の光路と撮像の光路とが直交するように分離する、請求項１～３のいずれか一項に記載の投影装置。 The projection apparatus according to any one of claims 1 to 3, wherein the optical path separation element separates the projection optical path and the imaging optical path so as to be orthogonal to each other.
  5. 　前記撮像素子の受光面は、前記画像表示素子の表示面と同等、またはそれ以下の面積を有している、請求項１～４のいずれか一項に記載の投影装置。 The projection device according to any one of claims 1 to 4, wherein a light receiving surface of the imaging element has an area equal to or less than a display surface of the image display element.
  6. 　前記第１レンズ群、前記第２レンズ群、及び前記第３レンズ群は、それぞれに非球面レンズを少なくとも１枚以上含む、請求項２に記載の投影装置。 The projection apparatus according to claim 2, wherein each of the first lens group, the second lens group, and the third lens group includes at least one aspheric lens.
  7. 　前記投影光学系は、前記第３レンズ群と投影面との間に反射光学系を有し、前記第３レンズ群は、正の屈折力を有する、請求項２、３、及び６のいずれか一項に記載の投影装置。 The projection optical system includes a reflection optical system between the third lens group and a projection surface, and the third lens group has a positive refractive power. The projection device according to one item.
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