WO2012147359A1 - 撮像レンズおよび撮像装置 - Google Patents
撮像レンズおよび撮像装置 Download PDFInfo
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- WO2012147359A1 WO2012147359A1 PCT/JP2012/002899 JP2012002899W WO2012147359A1 WO 2012147359 A1 WO2012147359 A1 WO 2012147359A1 JP 2012002899 W JP2012002899 W JP 2012002899W WO 2012147359 A1 WO2012147359 A1 WO 2012147359A1
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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
- G02B13/04—Reversed telephoto objectives
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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
- G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
- G02B13/0015—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design
- G02B13/002—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface
- G02B13/004—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface having four lenses
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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
- G02B13/06—Panoramic objectives; So-called "sky lenses" including panoramic objectives having reflecting surfaces
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B9/00—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or -
- G02B9/34—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or - having four components only
Definitions
- the present invention relates to an imaging lens and an imaging apparatus, and more specifically, to an in-vehicle camera, a mobile terminal camera, a monitoring camera, and the like using an imaging element such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor).
- an imaging element such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor).
- the present invention relates to an imaging lens suitable for the imaging, and an imaging device including the imaging lens.
- image sensors such as CCDs and CMOSs have been greatly reduced in size and pixels.
- an image pickup apparatus body including these image pickup elements is also downsized, and an image pickup lens mounted thereon is required to be downsized in addition to good optical performance.
- it is required to be compact and can be configured at low cost, and to have a wide angle and high performance.
- Patent Documents 1 to 3 describe a four-lens imaging lens including an aspherical lens.
- the present invention can realize downsizing, cost reduction, wide angle, and high performance, and an imaging lens with no limitation on an imaging element to be used, and an imaging apparatus including the imaging lens Is intended to provide.
- the first imaging lens of the present invention includes, in order from the object side, a negative first lens, a negative second lens, a plano-convex shape with a convex surface facing the object side, or a positive meniscus shape with a convex surface facing the object side
- the second imaging lens of the present invention includes, in order from the object side, a negative first lens, A negative second lens, a plano-convex shape with a convex surface facing the object side, or a positive meniscus third lens with a convex surface facing the object side, and a plano-convex shape with a convex surface facing the image side or a convex surface facing the image side A positive meniscus fourth lens facing
- conditional expression (2) is satisfied.
- the third imaging lens of the present invention includes, in order from the object side, a negative first lens, A negative second lens, a plano-convex shape with a convex surface facing the object side, or a positive meniscus third lens with a convex surface facing the object side, and a plano-convex shape with a convex surface facing the image side or a convex surface facing the image side A positive meniscus fourth lens facing
- conditional expression (8) is satisfied.
- the fourth imaging lens of the present invention includes a negative first lens and a biconcave shape in order from the object side. Negative second lens, a plano-convex shape with a convex surface facing the object side, or a positive meniscus third lens with a convex surface facing the object side, and a plano-convex shape with a convex surface facing the image side or a convex surface facing the image side A positive meniscus fourth lens facing The following conditional expression (9) is satisfied.
- conditional expressions (3) to (7), (10) to (20), (3-1) to (3-1) 7-1), (11-1), (12-1), and (12-2) are preferably satisfied.
- any one of the following conditional expressions (3) to (7), (10) to (20), (3-1) to (7-1), and (11-1) is used. It may have, or may have a configuration in which any two or more are combined.
- the material constituting the third lens is polycarbonate.
- the imaging device of the present invention is characterized by including at least one of the first to fourth imaging lenses of the present invention described above.
- the power arrangement in the entire system, the surface shapes of the third lens and the fourth lens, etc. are suitably set, and the conditional expression (1) is satisfied. Therefore, it is possible to achieve downsizing, cost reduction, and widening of the angle, as well as good correction of curvature of field, spherical aberration, coma, distortion, and lateral chromatic aberration, and a good image up to the periphery of the imaging area.
- An imaging lens having high optical performance capable of obtaining the above can be realized.
- the second imaging lens of the present invention in a minimum of four lens systems, the power arrangement in the entire system, the surface shapes of the third lens and the fourth lens, etc. are suitably set, and the conditional expression (2) is satisfied. Therefore, it is possible to achieve downsizing, cost reduction, and widening of the angle, as well as good correction of curvature of field, spherical aberration, coma, distortion, and lateral chromatic aberration, and a good image up to the periphery of the imaging area.
- An imaging lens having high optical performance capable of obtaining the above can be realized.
- the third imaging lens of the present invention in a minimum of four lens systems, the power arrangement in the entire system, the surface shapes of the third lens and the fourth lens, etc. are suitably set, and the conditional expression (8) is satisfied. Therefore, it is possible to achieve downsizing, cost reduction, and widening of the angle, and to correct the curvature of field, spherical aberration, coma aberration and distortion well, and obtain a good image up to the periphery of the imaging area. Therefore, it is possible to realize an imaging lens having high optical performance.
- the fourth imaging lens of the present invention in a minimum of four lens systems, the power arrangement in the entire system, the surface shapes of the second lens, the third lens, and the fourth lens are suitably set, and the conditional expression ( 9) is satisfied so that downsizing, cost reduction, and wide angle can be achieved, and the field curvature, spherical aberration, coma aberration, and distortion are corrected well, and the periphery of the imaging region is excellent.
- An imaging lens having high optical performance capable of obtaining an image can be realized.
- the imaging lens of the present invention since the imaging lens of the present invention is provided, it can be configured to be small and inexpensive, has a sufficiently wide angle of view, and can obtain a good image with high resolution using the imaging device. it can.
- FIG. 1 The figure which shows the structure and optical path of the imaging lens which concerns on one Embodiment of this invention.
- the figure for demonstrating the surface shape etc. of a 2nd lens Sectional drawing which shows the lens structure of the imaging lens of Example 1 of this invention.
- Sectional drawing which shows the lens structure of the imaging lens of Example 2 of this invention.
- Sectional drawing which shows the lens structure of the imaging lens of Example 3 of this invention.
- Sectional drawing which shows the lens structure of the imaging lens of Example 4 of this invention Sectional drawing which shows the lens structure of the imaging lens of Example 5 of this invention.
- FIGS. 32A to 32D are graphs showing aberrations of the imaging lens according to Example 1 of the present invention.
- 33A to 33D are diagrams showing aberrations of the image pickup lens of Example 2 of the present invention.
- 34 (A) to 34 (D) are graphs showing aberrations of the image pickup lens of Example 3 of the present invention.
- 35 (A) to 35 (D) are graphs showing aberrations of the imaging lens according to Example 4 of the present invention.
- 36 (A) to 36 (D) are graphs showing aberrations of the imaging lens according to Example 5 of the present invention.
- 37A to 37D are aberration diagrams of the imaging lens of Example 6 of the present invention.
- 38 (A) to 38 (D) are graphs showing aberrations of the imaging lens according to Example 7 of the present invention.
- 39A to 39D are diagrams showing aberrations of the imaging lens according to the eighth embodiment of the present invention.
- 40 (A) to 40 (D) are graphs showing aberrations of the imaging lens according to Example 9 of the present invention.
- 41 (A) to 41 (D) are graphs showing aberrations of the imaging lens according to Example 10 of the present invention.
- 42 (A) to 42 (D) are graphs showing aberrations of the image pickup lens of Example 11 of the present invention.
- 43 (A) to 43 (D) are graphs showing aberrations of the image pickup lens of Example 12 of the present invention.
- 44A to 44D are diagrams showing aberrations of the imaging lens according to the thirteenth embodiment of the present invention.
- 45A to 45D are aberration diagrams of the imaging lens of Example 14 of the present invention.
- 46 (A) to 46 (D) are graphs showing aberrations of the image pickup lens of Example 15 of the present invention.
- 47 (A) to 47 (D) are graphs showing aberrations of the imaging lens according to Example 16 of the present invention.
- 48 (A) to 48 (D) are graphs showing aberrations of the imaging lens according to Example 17 of the present invention.
- 49A to 49D are aberration diagrams of the image pickup lens of Example 18 of the present invention.
- 50A to 50D are aberration diagrams of the imaging lens of Example 19 of the present invention.
- 51A to 51D are aberration diagrams of the imaging lens of Example 20 of the present invention.
- 52 (A) to 52 (D) are graphs showing aberrations of the image pickup lens of Example 21 of the present invention.
- 53A to 53D are graphs showing aberrations of the image pickup lens of Example 22 of the present invention.
- 54A to 54D are diagrams showing aberrations of the image pickup lens of Example 23 of the present invention.
- 55 (A) to 55 (D) are graphs showing aberrations of the image pickup lens of Example 24 of the present invention.
- 56 (A) to 56 (D) are graphs showing aberrations of the image pickup lens of Example 25 of the present invention.
- 57 (A) to 57 (D) are graphs showing aberrations of the image pickup lens of Example 26 of the present invention.
- 58 (A) to 58 (D) are graphs showing aberrations of the image pickup lens of Example 27 of the present invention.
- 59A to 59D are aberration diagrams of the imaging lens of Example 28 of the present invention. The figure for demonstrating arrangement
- FIG. 1 is a diagram illustrating a configuration and an optical path of an imaging lens 1 according to an embodiment of the present invention.
- the imaging lens 1 shown in FIG. 1 corresponds to an imaging lens according to Example 3 of the present invention described later.
- the imaging lens 1 shown in FIG. 1 has the configurations of the first to third embodiments of the present invention described below.
- FIG. 2 is a diagram showing a configuration and an optical path of an imaging lens 1 ′ according to another embodiment of the present invention.
- An imaging lens 1 ′ shown in FIG. 2 corresponds to an imaging lens according to Example 17 of the present invention described later.
- the imaging lens 1 ′ shown in FIG. 2 has the configuration of the fourth embodiment of the present invention described below in addition to the configurations of the first to third embodiments of the present invention.
- the left side of the figure is the object side
- the right side is the image side
- off-axis light beams 3 and 4 at a full field angle 2 ⁇ are also included. It is shown.
- the imaging element 5 disposed on the image plane Sim including the image point Pim of the imaging lenses 1 and 1 ′ is also illustrated in consideration of the case where the imaging lens 1 is applied to the imaging device. .
- the image pickup device 5 converts an optical image formed by the image pickup lenses 1 and 1 ′ into an electric signal.
- a CCD image sensor or a CMOS image sensor can be used.
- FIG. 2 shows an example in which the parallel plate-like optical member PP that assumes these is arranged between the lens closest to the image side and the image sensor 5 (image plane Sim).
- the imaging lens according to the first embodiment of the present invention includes, in order from the object side, a negative first lens L1, a negative second lens L2, a plano-convex shape with a convex surface facing the object side, or a convex surface facing the object side. And a positive meniscus fourth lens L4 with a convex surface facing the image side or a positive meniscus fourth lens L4 with the convex surface facing the image side.
- an aperture stop St is disposed between the third lens L3 and the fourth lens L4. Note that the aperture stop St in FIG. 1 does not indicate the shape or size, but indicates the position on the optical axis Z.
- This imaging lens is composed of as few as four lenses, so that the cost can be reduced and the total length in the optical axis direction can be reduced.
- the first lens L1 and the second lens L2, which are two lenses disposed on the object side are both negative lenses, so that it is easy to widen the angle of the entire lens system. Further, by using two negative lenses, correction of each aberration required for the negative lens can be shared by these two lenses, and can be effectively corrected.
- the positive lens on the image side is also composed of two lenses, the third lens L3 and the fourth lens L4, so that the convergence effect for connecting the image on the image plane and the correction of each aberration required for the positive lens are achieved. These two lenses can be shared and can be corrected effectively.
- both the third lens L3 and the fourth lens L4 are positive lenses, it is possible to favorably correct curvature of field and spherical aberration.
- the third lens L3 has a plano-convex shape with the convex surface facing the object side or a positive meniscus shape with the convex surface facing the object side
- the fourth lens L4 has a plano-convex shape with the convex surface facing the image side or a convex surface facing the image side.
- the imaging lens according to the first embodiment of the present invention is configured to satisfy the following conditional expression (1).
- ⁇ d2 Abbe number with respect to the d-line of the material of the second lens L2
- ⁇ d3 Abbe number with respect to the d-line of the material of the third lens L3 Satisfying the lower limit of the conditional expression (1) makes it easy to correct the lateral chromatic aberration.
- the imaging lens according to the second embodiment of the present invention includes, in order from the object side, a negative first lens L1, a negative second lens L2, and a plano-convex shape with a convex surface facing the object side or a convex surface facing the object side. And a positive meniscus fourth lens L4 with a convex surface facing the image side or a positive meniscus fourth lens L4 with the convex surface facing the image side.
- This imaging lens is composed of as few as four lenses, so that the cost can be reduced and the total length in the optical axis direction can be reduced.
- the first lens L1 and the second lens L2, which are two lenses disposed on the object side are both negative lenses, so that it is easy to widen the angle of the entire lens system. Further, by using two negative lenses, correction of each aberration required for the negative lens can be shared by these two lenses, and can be effectively corrected.
- the positive lens on the image side is also composed of two lenses, the third lens L3 and the fourth lens L4, so that the convergence effect for connecting the image on the image plane and the correction of each aberration required for the positive lens are achieved. These two lenses can be shared and can be corrected effectively.
- both the third lens L3 and the fourth lens L4 are positive lenses, it is possible to favorably correct curvature of field and spherical aberration.
- the third lens L3 has a plano-convex shape with the convex surface facing the object side or a positive meniscus shape with the convex surface facing the object side
- the fourth lens L4 has a plano-convex shape with the convex surface facing the image side or a convex surface facing the image side.
- the imaging lens according to the second embodiment of the present invention is configured to satisfy the following conditional expression (2).
- Nd2 Refractive index for the d-line of the material of the second lens L2
- Nd3 Refractive index for the d-line of the material of the third lens L3
- the imaging lens according to the third embodiment of the present invention includes, in order from the object side, a negative first lens L1, a negative second lens L2, a plano-convex shape with a convex surface facing the object side, or a convex surface facing the object side. And a positive meniscus fourth lens L4 with a convex surface facing the image side or a positive meniscus fourth lens L4 with the convex surface facing the image side.
- This imaging lens is composed of as few as four lenses, so that the cost can be reduced and the total length in the optical axis direction can be reduced.
- the first lens L1 and the second lens L2, which are two lenses disposed on the object side are both negative lenses, so that it is easy to widen the angle of the entire lens system. Further, by using two negative lenses, correction of each aberration required for the negative lens can be shared by these two lenses, and can be effectively corrected.
- the positive lens on the image side is also composed of two lenses, the third lens L3 and the fourth lens L4, so that the convergence effect for connecting the image on the image plane and the correction of each aberration required for the positive lens are achieved. These two lenses can be shared and can be corrected effectively.
- both the third lens L3 and the fourth lens L4 are positive lenses, it is possible to favorably correct curvature of field and spherical aberration.
- the third lens L3 has a plano-convex shape with the convex surface facing the object side or a positive meniscus shape with the convex surface facing the object side
- the fourth lens L4 has a plano-convex shape with the convex surface facing the image side or a convex surface facing the image side.
- the imaging lens according to the third embodiment of the present invention is configured to satisfy the following conditional expression (8).
- the imaging lens according to the fourth embodiment of the present invention includes, in order from the object side, a negative first lens L1, a biconcave negative second lens L2, and a plano-convex shape with a convex surface facing the object side or A positive meniscus third lens L3 having a convex surface facing the object side and a plano-convex shape having a convex surface facing the image side or a positive meniscus fourth lens L4 having a convex surface facing the image side are provided.
- This imaging lens is composed of as few as four lenses, so that the cost can be reduced and the total length in the optical axis direction can be reduced.
- the first lens L1 and the second lens L2, which are two lenses disposed on the object side are both negative lenses, so that it is easy to widen the angle of the entire lens system. Further, by using two negative lenses, correction of each aberration required for the negative lens can be shared by these two lenses, and can be effectively corrected.
- the positive lens on the image side is also composed of two lenses, the third lens L3 and the fourth lens L4, so that the convergence effect for connecting the image on the image plane and the correction of each aberration required for the positive lens are achieved. These two lenses can be shared and can be corrected effectively.
- the second lens L2 may have a plano-concave shape.
- both the third lens L3 and the fourth lens L4 are positive lenses, it is possible to favorably correct curvature of field and spherical aberration.
- the third lens L3 has a plano-convex shape with the convex surface facing the object side or a positive meniscus shape with the convex surface facing the object side
- the fourth lens L4 has a plano-convex shape with the convex surface facing the image side or a convex surface facing the image side.
- the imaging lens according to the fourth embodiment of the present invention is configured to satisfy the following conditional expression (9).
- the imaging lens according to the first to fourth embodiments may have at least one of the configurations of the other embodiments, or at least one of the preferable configurations of the other embodiments.
- the imaging lens according to the first embodiment may have the configuration of the second embodiment, and the imaging lens according to the second embodiment is preferably described in the configuration of the first embodiment. It may have a configuration.
- f focal length of the entire system
- f2 focal length of the second lens L2 Satisfying the upper limit of the conditional expression (3) makes it easy to increase the power of the second lens L2 and facilitate widening of the angle. It becomes easy to downsize the lens system. If the lower limit of conditional expression (3) is not reached, the power of the second lens L2 becomes too strong, and the light beam is bent sharply by the second lens L2, so that it becomes difficult to correct the distortion or the image. It becomes difficult to correct the surface curvature.
- the second lens L2 has a negative meniscus shape with a convex surface facing the object side, it is easy to reduce the size of the lens system in the radial direction. Therefore, even if the upper limit is set to 2.7, the size of the lens system in the radial direction is reduced. It becomes easy to reduce the size. If the lower limit of conditional expression (3-1) is not reached, the power of the second lens L2 becomes too strong, and the light beam is bent sharply by the second lens L2, so that it becomes difficult to correct the distortion. Correction of curvature of field becomes difficult. Note that the second lens L2 may have a plano-concave shape.
- the second lens L2 may have a plano-concave shape.
- f focal length of the entire system
- f3 focal length of the third lens L3
- the second lens L2 By making the second lens L2 into a biconcave shape, widening of the angle is facilitated, and correction of field curvature, distortion, and spherical aberration is facilitated. In addition, since the second lens L2 has a biconcave shape, it becomes easy to correct the curvature of field, so that even when the upper limit is 4.6, the curvature of field can be favorably corrected. If the lower limit of conditional expression (5-1) is not reached, the power of the third lens L3 becomes too strong and the back focus becomes too short. Or, the power of the third lens L3 becomes too strong, and the tolerance of the eccentric manufacturing error becomes too small, and the manufacturing becomes difficult. Note that the second lens L2 may have a plano-concave shape.
- the object-side surface of the fourth lens L4 can be made flat or concave, and the power of the fourth lens L4 can be suppressed from becoming too strong. It becomes easy to lengthen the focus.
- the lower limit of conditional expression (6) it is possible to prevent the radius of curvature of the image side surface of the fourth lens L4 from becoming too small, and the power of the fourth lens L4 becomes too weak. This makes it easy to suppress the angle at which light rays enter the sensor at the periphery of the image sensor, or it can prevent the curvature radius of the object side surface from becoming too large, and spherical aberration. It becomes easy to correct.
- the fourth lens L4 can be formed into a plano-convex shape with the convex surface facing the image side or a meniscus shape with the convex surface facing the image side.
- the curvature and spherical aberration can be corrected satisfactorily.
- the object-side surface of the fourth lens L4 can be made flat or concave, and the power of the fourth lens can be suppressed from becoming too strong. It becomes easy to lengthen the back focus.
- the second lens L2 may have a plano-concave shape.
- R8 radius of curvature of object side surface of fourth lens L4 f: focal length of entire system Satisfying the lower limit of conditional expression (7) facilitates correction of spherical aberration.
- the second lens L2 may have a plano-concave shape.
- D4 Air distance on the optical axis between the second lens L2 and the third lens L3
- D5 Center thickness of the third lens L3 f: Focal length of the entire system Widening the angle by making the second lens L2 a biconcave shape This makes it easy to correct field curvature, distortion, and spherical aberration.
- conditional expression (10) spherical aberration, distortion, and coma aberration are corrected satisfactorily, the back focus can be increased, the angle of view can be increased, and sufficient performance can be obtained.
- the second lens L2 may have a plano-concave shape.
- R4 radius of curvature of the image-side surface of the second lens L2 f: focal length of the entire system
- the second lens L2 has a meniscus lens shape with the convex surface facing the object side, it is preferable that the following conditional expression (11-1) is satisfied.
- the second lens L2 may be a plano-concave lens.
- the second lens L2 can be a biconcave lens in which the absolute value of the curvature radius of the object-side surface is smaller than the absolute value of the curvature radius of the image-side surface. Correction is easy.
- the absolute value of the radius of curvature of the object side surface of the second lens L2 is compared with the absolute value of the radius of curvature of the image side surface of the second lens L2 in the biconcave lens. Therefore, it is easy to reduce the curvature of field, correction of field curvature, coma aberration, and spherical aberration.
- R1 radius of curvature of the object side surface of the first lens L1 f: focal length of the entire system If the upper limit of the conditional expression (13) is exceeded, the radius of curvature of the object side surface of the first lens L1 increases, and this surface Since the light beam is bent sharply, it becomes difficult to correct the distortion. If the lower limit of conditional expression (13) is not reached, the radius of curvature of the object-side surface of the first lens L1 becomes too small, making it difficult to widen the angle.
- D3 Center thickness f of the second lens L2: Focal length of the entire system If the upper limit of the conditional expression (15) is exceeded, the lens system becomes large. If the lower limit of conditional expression (15) is not reached, the center thickness of the second lens L2 becomes small, the thickness ratio between the peripheral part and the center part of the second lens L2 becomes large, and molding becomes difficult.
- R1 radius of curvature L of the object side surface of the first lens L1: distance from the surface vertex of the object side of the first lens L1 to the image plane If the upper limit of the conditional expression (17) is exceeded, the object side of the first lens L1 The radius of curvature of the surface becomes too large, and the light rays are bent sharply on this surface, making it difficult to correct the distortion. If the lower limit of conditional expression (17) is not reached, the total length becomes too long and it becomes difficult to reduce the size, or the radius of curvature of the object side surface of the first lens L1 becomes too small and it is difficult to widen the angle. Become.
- f focal length of the entire system
- f123 combined focal length of the first lens L1, the second lens L2, and the third lens L3
- conditional expression (19) If the lower limit of conditional expression (19) is not reached, the negative power of the first lens L1 and the second lens L2 becomes too strong, making it difficult to correct field curvature, or the positive power of the third lens L3 is weak. Thus, it becomes difficult to correct curvature of field and lateral chromatic aberration.
- f34 Combined focal length of the third lens L3 and the fourth lens L4 f: Focal length of the entire system If the upper limit of the conditional expression (20) is exceeded, the combined power of the third lens L3 and the fourth lens L4 becomes weak. In addition, it is difficult to correct curvature of field and lateral chromatic aberration, and it is difficult to suppress the incident angle of the light beam to the image sensor. If the lower limit of conditional expression (20) is not reached, the combined power of the third lens L3 and the fourth lens L4 becomes too strong, making it difficult to ensure back focus.
- conditional expressions satisfy the conditions in which the upper limit is further added or the lower limit or the upper limit is changed as follows. Further, as a preferable aspect, a conditional expression configured by combining a lower limit change value and an upper limit change value described below may be satisfied. Although a preferable example of changing the conditional expression will be described below as an example, the example of changing the conditional expression is not limited to the example described as an expression below, and may be a combination of the changed values described.
- the change value of the lower limit of conditional expression (1) As the change value of the lower limit of conditional expression (1), 2.3 is preferable, which makes it possible to further enhance the above-described effects. Further, 2.35 is more preferable in order to further enhance the effect. It is preferable to set the upper limit of conditional expression (1), and the upper limit value is preferably 2.8.
- the upper limit value is more preferably 2.7, and more preferably 2.6.
- conditional expressions (1-2) to (1-6) are satisfied, for example.
- the lower limit of conditional expression (2) is preferably 0.10 or more. This further facilitates correction of chromatic aberration and curvature of field. It is preferable to set the upper limit of conditional expression (2), and the upper limit value is preferably 0.16. This makes it easy to increase the refractive index of the second lens L2, so that the distortion is increased along with the widening of the angle. Correction is easy.
- the upper limit of conditional expression (2) is more preferably 0.14, and even more preferably 0.11.
- conditional expressions (2-1) to (2-4) are satisfied, for example.
- conditional expression (3) and conditional expression (3-1) is preferably 1.2, which makes it possible to enhance the above-described effects. In order to further enhance the action and effect, 1.5 is more preferable, 1.7 is further preferable, 1.8 is further more preferable, and 1.9 is still more preferable.
- the upper limit change value of conditional expression (3) and conditional expression (3-1) is preferably 2.4, which makes it possible to further enhance the above-described effects. In order to further enhance the action and effect, 2.2 is more preferable, 2.19 is further preferable, 2.18 is even more preferable, and 2.15 is even more preferable.
- conditional expression (4) 1.5 is preferable, and this makes it possible to further enhance the above-described effects.
- 2 is more preferable, and 2.04 is even more preferable.
- the upper limit change value of conditional expression (4) is preferably 2.4, which makes it possible to further enhance the above-described effects.
- 2.2 is more preferable.
- conditional expressions (4-2) to (4-4) are satisfied, for example.
- conditional expression (4-1) is preferably 1.5, which makes it possible to further enhance the above-described effects. In order to further enhance the action and effect, 2 is more preferable, and 2.04 is even more preferable.
- the upper limit change value of conditional expression (4-1) is preferably 2.7, which makes it possible to further enhance the above-described effects. In order to further enhance the action and effect, 2.5 is more preferable, and 2.3 is more preferable.
- conditional expressions (5-2) to (5-5) are satisfied, for example.
- conditional expression (6) 1.5 ⁇ f3 / f ⁇ 4.4 (5-2) 1.5 ⁇ f3 / f ⁇ 4.2 (5-3) 1.5 ⁇ f3 / f ⁇ 3.5 (5-4) 2.2 ⁇ f3 / f ⁇ 3.2 (5-5)
- 0.78 is preferable, and this makes it possible to further enhance the above-described effects. Further, 0.81 is more preferable in order to enhance the effect.
- the upper limit change value of conditional expression (6) is preferably 0.99, which makes it easier to increase the back focus. In order to further increase the back focus, 0.95 is more preferable.
- the change value of the lower limit of conditional expression (6-1) is preferably 0.65, which makes it possible to further enhance the above-described effects. Furthermore, 0.7 is more preferable in order to enhance the effect.
- the upper limit change value of conditional expression (6-1) is preferably 0.99, which makes it easier to increase the back focus. In order to further increase the back focus, 0.95 is more preferable.
- the change value of the lower limit of conditional expression (7) 7 is preferable, and this makes it possible to further enhance the above-described effects. In order to further enhance the action and effect, 10 is more preferable, 15 is more preferable, and 20 is even more preferable. It is preferable to set the upper limit of conditional expression (7).
- the upper limit value of conditional expression (7) is preferably 10,000, and satisfying this facilitates correction of field curvature and coma. In order to facilitate correction of field curvature and coma, the upper limit is more preferably 1000, and even more preferably 500.
- conditional expressions (7-2) to (7-5) are satisfied, for example.
- conditional expression (7-5) As the change value of the lower limit of conditional expression (7-1), 5 is preferable, which makes it possible to further enhance the above-described effects. In order to further enhance the effect, 6 is more preferable, and 6.5 is more preferable. It is preferable to set the upper limit of conditional expression (7-1).
- the upper limit value of conditional expression (7-1) is preferably 10,000, which facilitates correction of field curvature and coma. Furthermore, in order to facilitate correction of field curvature and coma, 1000 is more preferable, and 500 is more preferable.
- conditional expressions (7-6) to (7-9) are satisfied, for example.
- conditional expression (8) As a change value of the lower limit of conditional expression (8), 9 is preferable, and this makes it possible to further enhance the above-described effects. In order to further enhance the action and effect, 10 is more preferable, and 10.5 is even more preferable. As an upper limit change value of conditional expression (8), 13.8 is preferable, and this makes it possible to further enhance the above-described effects. In order to further enhance the action and effect, 13.5 is more preferable, 13 is more preferable, and 12 is even more preferable.
- conditional expressions (8-1) to (8-4) are satisfied, for example.
- conditional expression (9) 9.0 ⁇ L / f ⁇ 13.8 (8-1) 9.0 ⁇ L / f ⁇ 13.5 (8-2) 10 ⁇ L / f ⁇ 13 (8-3) 10.5 ⁇ L / f ⁇ 12 (8-4)
- the upper limit change value of conditional expression (9) is preferably 2.8, which makes it possible to further enhance the above-described effects. In order to further enhance the action and effect, 2.5 is more preferable, and 2.35 is further preferable.
- conditional expressions (9-1) to (9-3) are satisfied, for example.
- conditional expressions (10-1) to (10-3) are satisfied, for example.
- conditional expression (11-1) It is preferable to set a lower limit value in conditional expression (11-1), and the lower limit value is preferably 0.1, which facilitates correction of field curvature. Further, in order to facilitate correction of field curvature, 0.5 is more preferable, 0.7 is more preferable, and 0.8 is more preferable.
- the change value of the upper limit of conditional expression (11-1) is preferably 1.2, which makes it possible to further enhance the above-described effects. In order to further enhance the effect, 1.1 is more preferable, and 1 is more preferable.
- conditional expressions (11-7) to (11-10) are satisfied, for example.
- the change value of the lower limit of conditional expression (12) is preferably ⁇ 30, and this makes it possible to further enhance the above-described effects.
- ⁇ 20 is more preferable, ⁇ 10 is further preferable, and ⁇ 8 is even more preferable.
- 0.82 is preferable, and it becomes possible to raise said effect more.
- 0.8 is more preferable, and 1 is more preferable.
- conditional expressions (12-3) to (12-6) are satisfied, for example.
- the change value of the upper limit of conditional expression (12-1) is preferably -1.1. This makes the radius of curvature of the image side surface too large or the radius of curvature of the object side surface becomes too small. Can be easily suppressed, and correction of field curvature and distortion is facilitated. In order to further enhance the action and effect, -1.5 is more preferable, and -2.0 is more preferable.
- the change value of the lower limit of the conditional expression (12-1) can be considered in the same way as the conditional expression (12).
- conditional expressions (12-7) to (12-8) are satisfied, for example.
- conditional expression (12-2) is preferably 0.3, which makes it possible to further enhance the above-described effects. In order to further enhance the action and effect, 0.5 is more preferable, and 0.7 is more preferable.
- the upper limit change value of conditional expression (12-2) can be considered in the same manner as conditional expression (12).
- conditional expressions (12-9) to (12-10) are satisfied, for example.
- conditional expression (13) As a change value of the lower limit of conditional expression (13), 10 is preferable, and this makes it possible to further enhance the above-described effects. In order to further enhance the action and effect, 12 is more preferable, and 13 is more preferable.
- the upper limit change value of conditional expression (13) is preferably 35, which makes it possible to further enhance the above-described effects. In order to further enhance the action and effect, 30 is more preferable, and 26 is more preferable.
- the change value of the lower limit of conditional expression (14) is preferably 6. This makes it possible to further enhance the above-described effects. In order to further enhance the action and effect, 20 is more preferred, 30 is more preferred, and 35 is even more preferred. It is preferable to set an upper limit in conditional expression (14), and the upper limit value is preferably 5000, which facilitates correction of field curvature and coma. Furthermore, in order to satisfactorily correct curvature of field and coma, the upper limit is preferably 1000, more preferably 100, and even more preferably 70.
- conditional expressions (14-1) to (14-5) are satisfied, for example.
- conditional expressions (15-1) to (15-3) are satisfied, for example.
- conditional expression (16) 0.7 ⁇ D3 / f ⁇ 2.0 (15-1) 0.8 ⁇ D3 / f ⁇ 1.8 (15-2) 0.9 ⁇ D3 / f ⁇ 1.5 (15-3)
- 0.4 is preferable, and this makes it possible to further enhance the above-described effects.
- 0.5 is more preferable, and 0.55 is even more preferable.
- the upper limit change value of conditional expression (16) is preferably 0.7, which further facilitates distortion correction. Further, 0.68 is more preferable for facilitating distortion correction.
- conditional expressions (16-1) to (16-3) are satisfied, for example.
- conditional expressions (17-1) to (17-4) are satisfied, for example.
- conditional expression (18) is preferably ⁇ 0.2, and this makes it possible to further enhance the above-described effects.
- -0.4 is more preferable, -0.6 is further preferable, and -0.7 is still more preferable.
- conditional expressions (18-1) to (18-4) are satisfied, for example.
- conditional expression (19) is preferably ⁇ 0.6, which makes it possible to further enhance the above-described effects. In order to further enhance the effect, -0.5 is more preferable, and -0.3 is even more preferable. As an upper limit change value of conditional expression (19), 0.5 is preferable, and this makes it possible to further enhance the above-described effects. In order to further enhance the effect, 0.3 is more preferable, and 0.1 is even more preferable.
- conditional expression (20) 1.5 is preferable, and this makes it possible to further enhance the above-described effects. Further, 2 is more preferable in order to further enhance the effect. As a change value of the upper limit of conditional expression (20), 8 is preferable, and this makes it possible to further enhance the above-described effects. In order to further enhance the action and effect, 6.5 is more preferable.
- the aperture stop is preferably disposed between the third lens L3 and the fourth lens L4. By disposing the aperture stop between the third lens L3 and the fourth lens L4, the entire system can be reduced in size.
- the Abbe number of the material of the first lens L1, the second lens L2, and the fourth lens L4 with respect to the d-line is 40 or more, thereby suppressing the occurrence of chromatic aberration and obtaining good resolution performance. It becomes.
- the Abbe number of the material of the third lens L3 with respect to the d-line is 40 or less, which makes it possible to satisfactorily correct lateral chromatic aberration. Further, it is more preferably 30 or less, further preferably 28 or less, and even more preferably 25 or less.
- ⁇ d1 / ⁇ d2 is preferably 0.7 or more. Occurrence of chromatic aberration can be suppressed and good resolution performance can be obtained. Furthermore, it is more preferable that it is 0.8 or more.
- ⁇ d1 / ⁇ d3 is preferably 1.95 or more
- Axial chromatic aberration and lateral chromatic aberration can be satisfactorily corrected.
- it is more preferably 2.00 or more, and further preferably 2.05 or more.
- ⁇ d1 / ⁇ d3 is preferably 2.5 or less.
- the Abbe number of the third lens L3 can be prevented from becoming too small, and the material of the third lens L3 can be easily made inexpensive, or the Abbe number of the first lens L1 can be suppressed. Therefore, it is easy to increase the refractive index of the first lens L1 to increase the power of the first lens L1, and it is easy to reduce the size of the lens system and correct distortion. Further, in order to facilitate the correction of the size reduction and distortion of the system, it is more preferably 2.40 or less, and further preferably 2.20 or less.
- ⁇ d4 / ⁇ d3 is preferably 2.1 or more. It is possible to satisfactorily correct axial chromatic aberration and lateral chromatic aberration. Furthermore, in order to satisfactorily correct axial chromatic aberration and lateral chromatic aberration, it is more preferably 2.2 or more, further preferably 2.30 or more, and even more preferably 2.35 or more. .
- ⁇ d2 / ⁇ d4 is preferably 0.8 or more and 1.2 or less.
- the refractive index of the material of the first lens L1 with respect to the d-line is preferably 1.88 or less, which makes it easy to make the material of the first lens L1 inexpensive. Furthermore, by using a material having a low refractive index, a material having a large Abbe number can be selected, chromatic aberration can be easily corrected, and good resolution performance can be easily obtained. Furthermore, in order to correct chromatic aberration satisfactorily, it is more preferably 1.85 or less, and further preferably 1.80 or less.
- the refractive index of the material of the first lens L1 with respect to the d-line is preferably 1.60 or more, which makes it easy to increase the power of the first lens L1, facilitate widening and processing, Distortion correction is easy. Furthermore, in order to facilitate the widening, processing and distortion correction, it is more preferably 1.65 or more, and even more preferably 1.70 or more.
- the refractive index of the material of the second lens L2 with respect to the d-line is 1.70 or less, whereby the material of the second lens L2 can be made inexpensive. Furthermore, since the Abbe number becomes small in a material having a high refractive index, chromatic aberration becomes large, and it becomes difficult to obtain good resolution performance. In order to make the material of the second lens L2 inexpensive, it is more preferably 1.65 or less, and further preferably 1.60 or less.
- the refractive index of the material of the second lens L2 with respect to the d-line is preferably 1.50 or more, which makes it easy to increase the power of the second lens L2 and easily correct distortion. Moreover, since it becomes easy to increase the power of the second lens L2, it is easy to reduce the size of the lens system.
- the refractive index of the material of the third lens L3 with respect to the d-line is 1.75 or less, so that the material of the third lens L3 can be made inexpensive.
- it is more preferably 1.70 or less, further preferably 1.68 or less, and even more preferably 1.65 or less.
- the refractive index of the material of the third lens L3 with respect to the d-line is 1.50 or more, thereby increasing the refractive index of the material of the third lens L3 and increasing the power of the third lens L3. This facilitates correction of chromatic aberration of magnification and curvature of field. It is more preferably 1.55 or more, further preferably 1.60 or more, and even more preferably 1.63 or more.
- the refractive index of the fourth lens material with respect to the d-line is preferably 1.70 or less, which makes it possible to reduce the cost of the material of the fourth lens L4. Furthermore, since the Abbe number becomes small in a material having a high refractive index, chromatic aberration becomes large, and it becomes difficult to obtain good resolution performance. In order to further suppress the material cost and further correct the chromatic aberration, the refractive index of the material of the fourth lens L4 with respect to the d-line is more preferably 1.65 or less, and further preferably 1.60 or less. preferable.
- the refractive index of the material of the fourth lens L4 with respect to the d-line is 1.50 or more, thereby increasing the refractive index of the material of the fourth lens L4 and increasing the power of the fourth lens L4. It becomes easy.
- the power of the fourth lens L4 it becomes easy to correct spherical aberration with the fourth lens L4, and it is easy to bend the light beam greatly with the fourth lens L4, so that the peripheral light beam enters the image sensor. It becomes easy to suppress the angle, and it becomes easy to suppress shading.
- Nd1 / Nd2 is preferably 0.95 or more and 1.3 or less. If the lower limit of this condition is exceeded, it will be difficult to allocate negative power in a balanced manner to the first lens L1 and the second lens L2, and it will be difficult to correct distortion, or Nd2 will become too large. The Abbe number of the two lenses L2 becomes large and it becomes difficult to correct the lateral chromatic aberration.
- the lower limit change value is preferably 1.0, and more preferably 1.05.
- the change value of the upper limit is preferably 1.2, and more preferably 1.15. It should be noted that a condition configured by combining the lower limit change value and the upper limit change value may be satisfied.
- Nd3 / Nd2 is 1.0 or more and 1.2 or less. preferable.
- the refractive index of the material of the second lens L2 can be reduced and the power of the second lens L2 can be prevented from being weakened, and the negative power balance of the first lens L1 and the second lens L2 can be appropriately maintained. This makes it easy to correct the distortion or to reduce the size of the lens system.
- Nd1 / Nd4 is preferably 0.95 or more and 1.3 or less. .
- Nd1 can be reduced and the power of the first lens L1 can be prevented from being weakened, and it is easy to widen the angle or to reduce the size of the lens system.
- the refractive index of the material of the 4th lens L4 becomes large, it can suppress that the Abbe number of the material of the 4th lens L4 becomes small, and correction
- the change value of the lower limit of this condition is preferably 1.0.
- the object-side surface of the second lens L2 is preferably an aspherical surface, which facilitates downsizing and widening of the lens system. Or it becomes easy to correct
- the image-side surface of the second lens L2 is preferably an aspherical surface, so that field curvature and distortion can be corrected well.
- the image side surface of the third lens L3 is preferably an aspherical surface, which makes it possible to correct field curvature well.
- the object side surface of the fourth lens L4 is preferably an aspherical surface, which makes it possible to satisfactorily correct spherical aberration and curvature of field.
- the image side surface of the fourth lens L4 be an aspherical surface, which makes it possible to satisfactorily correct spherical aberration, curvature of field, and distortion.
- the object side surface of the second lens L2 is preferably an aspherical surface.
- the object side surface of the second lens L2 has a positive power at the center and has a shape in which the positive power is weaker than the center at the effective diameter end, or has a positive power at the center, and is negative at the effective diameter end.
- a shape having power is preferable.
- the “effective diameter of the surface” is a circle consisting of the outermost point in the radial direction (the point farthest from the optical axis) when the point where all the rays that contribute to image formation intersect with the lens surface is considered. It means the diameter, and “effective diameter end” means the outermost point.
- the figure composed of the outermost points is a circle. However, in a system that is not rotationally symmetric, it may not be a circle.
- the circle diameter may be considered as the effective diameter.
- the aspherical shape when a certain point on the i-th lens surface is Xi and the intersection of the normal line and the optical axis at that point is Pi, the length of Xi ⁇ Pi (
- the point Pi is located on the image side from the point Qi is defined as positive power, and the case where the point Pi is located on the object side from the point Qi is defined as negative power.
- the point Pi is defined as The case where the point is located on the object side from the point Qi is defined as positive power, and the case where the point Pi is located on the image side from the point Qi is defined as negative power.
- FIG. 3 is an optical path diagram of the imaging lens 1 shown in FIG.
- a point Q3 is the center of the object-side surface of the second lens L2, and is the intersection of the object-side surface of the second lens L2 and the optical axis Z.
- a point X3 in FIG. 3 is an effective diameter end point of the object-side surface of the second lens L2, and is an intersection of the outermost ray 6 included in the off-axis light beam 3 and the object-side surface of the second lens L2. It is.
- the intersection of the normal of the lens surface at the point X3 and the optical axis Z is a point P3 as shown in FIG. 3, and a line segment X3-P3 connecting the point X3 and the point P3 is a radius of curvature RX3 at the point X3.
- of the line segment X3-P3 is defined as the absolute value
- the radius of curvature at the point Q3, that is, the radius of curvature of the center of the object side surface of the second lens L2 is R3, and its absolute value is
- Having positive power at the center” on the object side surface of the second lens L2 means that the paraxial region including the point Q3 is convex.
- the shape where the positive power is weaker than the center at the effective diameter end” of the object side surface of the second lens L2 means that the point P3 is closer to the image side than the point Q3, and the curvature at the point X3. This means that the absolute value
- a circle CQ3 centered on a point on the optical axis passes through a point Q3 with a radius
- the circle CX3 is larger than the circle CQ3, and it is clearly indicated that
- the “shape having negative power at the effective diameter end” of the object side surface of the second lens L2 means a shape in which the point P3 is closer to the object side than the point Q3.
- the object side surface of the second lens L2 has a negative power at the center and has a shape with a negative power weaker than the center at the effective diameter end, or a negative power at the center, and a positive power at the effective diameter end. It is good also as a shape with power.
- the surface shape of the second lens L2 on the object side can be considered as follows in the same manner as described above with reference to FIG. “Having negative power at the center” means that the paraxial region including the point Q3 is concave. Further, “the shape where the negative power is weaker than the center at the effective diameter end” of the object side surface of the second lens L2 means that the point P3 is closer to the object side than the point Q3, and the curvature at the point X3 is This means that the absolute value
- the “shape having a positive power at the effective diameter end” of the object side surface of the second lens L2 means a shape in which the point P3 is located on the image side from the point Q3.
- the image side surface of the second lens L2 is preferably an aspherical surface. It is preferable that the image-side surface of the second lens L2 has a negative power at the center and a shape having a weaker negative power than the center at the effective diameter end. With the second lens L2 having such a shape, it is possible to favorably correct distortion and curvature of field.
- the above shape of the image side surface of the second lens L2 can be considered as follows in the same manner as the shape of the object side surface of the second lens L2 described with reference to FIG.
- the point X4 and the point P4 are
- the connecting line segment X4-P4 is defined as the radius of curvature at the point X4, and the length
- the shape having a negative power at the center and a weaker negative power than the center at the effective diameter end” on the image side surface of the second lens L2 is a concave shape in the paraxial region including the point Q4.
- the point P4 is closer to the image side than the point Q4, and the absolute value
- the image-side surface of the second lens L2 may have a negative power at the center, and a shape having a stronger negative power than the center at a point where the effective diameter is 50%.
- a shape having a stronger negative power than the center at a point where the effective diameter is 50% By making the image side surface of the second lens L2 in such a shape, it is possible to satisfactorily correct curvature of field and distortion.
- “50% of the effective diameter” means a lens surface in which the radial coordinate of the lens surface (coordinate in the direction perpendicular to the optical axis) is a distance from the center of the lens that is 50% of the effective diameter of the lens. Means the top point.
- the shape of the image side surface of the second lens L2 having a negative power at the center and a strong negative power compared to the center at 50% of the effective diameter Assuming that a point 50% of the effective diameter of the image side surface of the two lens L2 is a point X4 'and an intersection of the normal at that point and the optical axis Z is a point P4', it is concave in the paraxial region including the point Q4.
- of the radius of curvature at the point Q4. means.
- the image side surface of the second lens L2 may have a shape in which the power at the position of the effective diameter end is weaker than the 50% effective diameter point.
- the shape in which the power at the end of the effective diameter is weaker than the 50% of the effective diameter means that the absolute value
- the 50% point of the effective diameter and the effective diameter end both have negative power, and compared with the 50% point of the effective diameter, at the effective diameter end,
- the shape may have a weak negative power.
- the shape with 50% of the effective diameter and the end of the effective diameter both have negative power, and the negative power at the end of the effective diameter is weaker than the point of 50% of the effective diameter” means the point X4 and
- the second lens L2 may have a meniscus shape with a convex surface facing the object side, which facilitates correction of field curvature while reducing the size of the lens system.
- the center of the second lens object side surface has a positive power, and a positive power compared to the center at the effective diameter end. It is preferable that the shape is weak or has a negative power at the end of the effective diameter. As a result, the lens system can be reduced in size and widened, and at the same time, the field curvature can be corrected well.
- the second lens L2 may have a biconcave shape, which facilitates correction of field curvature and distortion while reducing the size and widening of the lens system. Further, when the second lens L2 has a biconcave shape, the object side surface of the second lens L2 has a negative power at the center, and has a negative power weaker than the center at the effective diameter end. It is preferable that This makes it possible to correct the field curvature and distortion well at the same time as widening the angle. When the second lens L2 has a biconcave shape, the object-side surface of the second lens L2 may have a shape having a negative power at the center and a positive power at the effective diameter end. As a result, it is possible to satisfactorily correct field curvature and distortion simultaneously with widening of the angle.
- the object side surface of the third lens L3 is preferably an aspherical surface. It is preferable that the object side surface of the third lens L3 has a positive power at the center, and has a shape with a stronger positive power than the center at 50% of the effective diameter. By making the object side surface of the third lens L3 into such a shape, it is possible to favorably correct curvature of field and lateral chromatic aberration.
- the above shape of the object side surface of the third lens L3 can be considered as follows in the same manner as the shape of the object side surface of the second lens L2 described with reference to FIG.
- 50% of the effective diameter of the object-side surface of the third lens L3 is a point X5 '
- the intersection of the normal at that point and the optical axis Z is a point P5'
- the line segment X5'-P5 'connecting X5' and the point P5 ' is the radius of curvature at the point X5', and the length of the line segment connecting the point X5 'and the point P5'
- the absolute value of the radius of curvature at X5 ′ is
- the shape of the object side surface of the third lens L3 having a positive power at the center and a stronger positive power than the center at 50% of the effective diameter is a paraxial region including the point Q5.
- the shape is convex, the point P5 'is closer to the image side than the point Q5, and the absolute value of the radius of curvature at the point X5'
- the object side surface of the third lens L3 may have a shape in which the power at the end of the effective diameter is weaker than the point at the effective diameter of 50%.
- the shape in which the power at the end of the effective diameter is weaker than the 50% of the effective diameter means that the absolute value
- the object side surface of the third lens L3 may have a shape having positive power at both the 50% effective diameter point and the effective diameter end point.
- a shape in which both 50% of the effective diameter points and the end of the effective diameter have positive power means that both the points P5 and P5 ′ are closer to the image side than the point Q5.
- the object side surface of the third lens L3 may have a shape including a point where the center has a positive power and a positive power is stronger between the center and the end of the effective diameter than the center.
- the above shape of the object side surface of the third lens L3 can be considered as follows in the same manner as the shape of the object side surface of the second lens L2 described with reference to FIG.
- a point between the center of the object side surface of the third lens L3 and the effective diameter end is defined as a point X5 ′′, and an intersection of the normal line and the optical axis Z at that point is defined as a point P5 ′′.
- the line segment X5 ′′ -P5 ′′ connecting the point X5 ′′ and the point P5 ′′ is the radius of curvature at the point X5 ′′, and the length of the line connecting the point X5 ′′ and the point P5 ′′
- X5 ′′ -P5 Let "
- the shape including the point where the center has positive power and the positive power is stronger than the center between the center and the effective diameter end is a convex shape in the paraxial region including the point Q5.
- the point P5 ′′ is closer to the image side than the point Q5, and the absolute value
- the image side surface of the third lens L3 is preferably an aspherical surface.
- the image-side surface of the third lens L3 has a negative power at the center, a shape having a stronger negative power than the center at the effective diameter end, or a flat center at the effective diameter end, and a negative power at the effective diameter end. It is preferable to have a shape. By making the third lens L3 such a shape, it is possible to favorably correct curvature of field.
- the above shape of the image side surface of the third lens L3 can be considered as follows in the same manner as the shape of the object side surface of the second lens L2 described with reference to FIG.
- the effective diameter end of the image side surface of the third lens L3 is a point X6 and the intersection of the normal line at that point and the optical axis Z is a point P6
- the point X6 and the point P6 are
- the connecting line segment X6-P6 is defined as the radius of curvature at the point X6, and the length
- the shape having a negative power at the center and a stronger negative power than the center at the effective diameter end” on the image side surface of the third lens L3 is a concave shape in the paraxial region including the point Q6.
- Point P6 is closer to the image side than point Q6, and the absolute value
- a shape having a flat center and a negative power at the effective diameter end means a shape which is a plane in the paraxial region including the point Q6 and the point P6 is closer to the image side than the point Q6.
- the object side surface of the fourth lens L4 is preferably an aspherical surface.
- the object-side surface of the fourth lens L4 has a negative power at the center and a shape having a stronger negative power than the center at the effective diameter end, or a flat center at the effective diameter end, and a negative power at the effective diameter end. It is preferable to have a shape. With the fourth lens L4 having such a shape, it is possible to satisfactorily correct spherical aberration and field curvature.
- the above shape of the object side surface of the fourth lens L4 can be considered as follows in the same manner as the shape of the object side surface of the second lens L2 described with reference to FIG.
- the point X8 and the point P8 are
- the connecting line segment X8-P8 is defined as the radius of curvature at the point X8, and the length
- the shape having a negative power at the center and a strong negative power at the effective diameter end” on the object side surface of the fourth lens L4 is a concave shape in the paraxial region including the point Q8.
- the point P8 is closer to the object side than the point Q8, and the absolute value
- a shape having a center at a plane and having negative power at the end of the effective diameter means a shape that is a plane in the paraxial region including the point Q8 and the point P8 is closer to the object side than the point Q8.
- the image side surface of the fourth lens L4 is preferably an aspherical surface. It is preferable that the image side surface of the fourth lens L4 has a positive power at the center and has a weaker positive power than the center at the effective diameter end. With the fourth lens L4 having such a shape, it is possible to satisfactorily correct spherical aberration, field curvature, and distortion.
- the above shape of the image side surface of the fourth lens L4 can be considered as follows in the same manner as the shape of the object side surface of the second lens L2 described with reference to FIG.
- the point X9 and the point P9 are
- the connecting line segment X9-P9 is the radius of curvature at the point X9
- of the line segment connecting the point X9 and the point P9 is the absolute value
- the shape of the image side surface of the fourth lens L4 having positive power at the center and weaker than the center at the effective diameter end is a convex shape in the paraxial region including the point Q9.
- the point P9 is closer to the object side than the point Q9, and the absolute value
- each surface from the object-side surface of the second lens L2 to the image-side surface of the fourth lens L4 into an aspheric shape as described above distortion is added in addition to spherical aberration, field curvature, and coma. It becomes possible to correct well.
- the first lens L1 preferably has a positive meniscus shape, which makes it possible to produce a wide-angle lens exceeding, for example, 180 degrees.
- the first lens L1 is a biconcave lens, it is easy to increase the power of the first lens L1, and thus widening the angle is easy.
- the light rays are suddenly bent by the first lens L1, distortion is caused. Correction becomes difficult.
- the object-side surface is concave, the incident angle when the peripheral ray is incident on the lens surface increases, and the reflection loss at the time of incidence on the surface increases, so that the peripheral portion becomes dark.
- a light beam having an incident angle exceeding 180 degrees cannot be incident. Therefore, in order to facilitate distortion correction while having a wide angle, the first lens L1 is preferably a positive meniscus lens having a convex surface facing the object side.
- the second lens L2 has a biconcave shape.
- the absolute value of the radius of curvature of the object side surface may be smaller than the absolute value of the radius of curvature of the image side surface.
- the second lens L2 may have a meniscus shape with a convex surface facing the object side. By making the second lens L2 have a meniscus shape with a convex surface facing the object side, it is easy to reduce the radial direction of the lens system while having a wide angle.
- the second lens L2 may have a plano-concave shape with the plane facing the object side, which makes it easy to reduce the lens diameter while favorably correcting curvature of field.
- the third lens L3 has a meniscus shape with a convex surface facing the object side, which makes it possible to satisfactorily correct field curvature and coma.
- the third lens L3 may be a plano-convex shape having a convex surface facing the object side in the paraxial region, which makes it possible to correct field curvature and coma favorably.
- the fourth lens L4 has a meniscus shape with a convex surface facing the image side, which makes it possible to satisfactorily correct spherical aberration and curvature of field.
- the fourth lens L4 may have a plano-convex shape with a convex surface facing the image side, which makes it possible to favorably correct spherical aberration and curvature of field.
- the material of the first lens L1 is preferably glass.
- the first lens L1 disposed closest to the object side is resistant to surface deterioration due to wind and rain, temperature change due to direct sunlight, Is required to use materials that are resistant to chemicals such as oils and detergents, that is, materials with high water resistance, weather resistance, acid resistance, chemical resistance, etc., and materials that are hard and hard to break are required. Sometimes. These requirements can be satisfied by using glass as the material. Moreover, you may use transparent ceramics as a material of the 1st lens L1.
- the one or both surfaces of the first lens L1 may be aspheric.
- various aberrations can be corrected more satisfactorily.
- a protective means for enhancing strength, scratch resistance and chemical resistance may be applied to the object side surface of the first lens L1, and in this case, the material of the first lens L1 may be plastic.
- Such protective means may be a hard coat or a water repellent coat.
- the material is plastic.
- plastic By using plastic as the material, it is possible to configure the lens system at a low cost and light weight, and when an aspheric surface is provided, the aspherical shape can be accurately produced, so that a good performance can be obtained.
- a lens can be manufactured.
- the material of the second lens L2 is preferably polyolefin.
- Polyolefin has low water absorption, high transparency, low birefringence, and a material with a large Abbe number.
- polyolefin As the material of the second lens L2, it is possible to create a lens that has a small shape change due to water absorption, a high transmittance, and a low birefringence.
- a material having a large Abbe number can be used, the occurrence of axial chromatic aberration and lateral chromatic aberration can be suppressed, and it becomes possible to create a lens with high environmental resistance and good resolution performance.
- the material of the third lens L3 is preferably polycarbonate.
- Polycarbonate is characterized by a small Abbe number. By using polycarbonate for the third lens L3, it is possible to satisfactorily correct lateral chromatic aberration.
- the material of the fourth lens L4 is preferably polyolefin.
- Polyolefin has low water absorption, high transparency, low birefringence, and a material with a large Abbe number.
- polyolefin As the material of the fourth lens L4, it is possible to create a lens that has a small shape change due to water absorption, a high transmittance, and a low birefringence.
- a material having a large Abbe number can be used, the occurrence of axial chromatic aberration and lateral chromatic aberration can be suppressed, and it becomes possible to create a lens with high environmental resistance and good resolution performance.
- the material of the second lens L2 and the fourth lens L4 may be acrylic. Since acrylic is inexpensive, it is possible to make the lens system inexpensive by using acrylic.
- a so-called nanocomposite material in which particles smaller than the wavelength of light are mixed into the plastic is used as the material. It may be used.
- the material of the second lens L2, the third lens L3, and the fourth lens L4, or any combination of them may be glass. By using glass as the material, it is possible to suppress performance deterioration due to temperature changes.
- At least one of the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 preferably has a glass transition temperature (Tg) of 145 ° C. or higher, more preferably, It is preferable that it is 150 degreeC or more.
- Tg glass transition temperature
- a filter that cuts blue light from ultraviolet light or an IR (InfraRed) cut filter that cuts infrared light is inserted between the lens system and the imaging device 5. May be.
- a coat having the same characteristics as the filter may be applied to the lens surface.
- a material that absorbs ultraviolet light, blue light, infrared light, or the like may be used as a material of any lens.
- FIG. 1 shows an example in which the optical member PP assuming various filters is arranged between the lens system and the image sensor 5. Instead, these various filters are arranged between the lenses. Also good. Or you may give the coat
- a light shielding means for shielding the stray light as necessary.
- the light shielding means for example, an opaque paint may be applied to a portion outside the effective diameter of the lens, or an opaque plate material may be provided.
- an opaque plate material may be provided in the optical path of a light beam that becomes stray light to serve as a light shielding unit.
- a hood that blocks stray light may be disposed further on the object side of the most object side lens. As an example, FIG.
- the light shielding means 11 and 12 are provided outside the effective diameters of the image-side surfaces of the first lens L1 and the second lens L2.
- the location where the light shielding means is provided is not limited to the example shown in FIG. 1, and may be arranged between other lenses or between the lenses.
- a member such as a diaphragm that blocks the peripheral light beam may be disposed between the lenses so long as the peripheral light amount ratio has no practical problem.
- a peripheral ray is a ray that passes through a peripheral portion of the entrance pupil of the optical system among rays from an object point outside the optical axis Z.
- the lens system is configured to include only four lenses, that is, the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4. It is preferable. By configuring the lens system with only four lenses, the lens system can be made inexpensive.
- the imaging apparatus includes the imaging lens according to the present embodiment, the imaging apparatus can be configured to be small and inexpensive, have a sufficiently wide angle of view, and obtain a good image with high resolution using the imaging element. be able to.
- the imaging lens according to the first to fourth embodiments may have at least one of the configurations of the other embodiments, or at least one of the preferable configurations of the other embodiments.
- the imaging lens according to the first embodiment may have the configuration of the second embodiment, and the imaging lens according to the second embodiment is preferably described in the configuration of the first embodiment. It may have a configuration.
- FIGS. 4 to 31 [Numerical example of imaging lens]
- the imaging lens of the present invention will be described.
- Lens cross-sectional views of the imaging lenses of Examples 1 to 28 are shown in FIGS. 4 to 31, respectively. 4 to 31, the left side of the figure is the object side, and the right side is the image side.
- the aperture stop St, the optical member PP, and the image sensor 5 disposed on the image plane Sim are also shown. It is shown.
- the aperture stop St in each figure does not indicate the shape or size, but indicates the position on the optical axis Z.
- Tables 1 to 28 show lens data of the imaging lenses of Examples 1 to 28, respectively.
- (A) shows basic lens data
- (B) shows various data
- (C) shows aspherical data.
- Ri column indicates the radius of curvature of the i-th surface
- Di column indicates the surface spacing on the optical axis Z between the i-th surface and the i + 1-th surface. The sign of the radius of curvature is positive when the surface shape is convex on the object side and negative when the surface shape is convex on the image side.
- the refractive index with respect to the d-line (wavelength: 587.6 nm) of the j-th (j 1, 2, 3,%) Optical element that sequentially increases toward the image side with the most object-side lens as the first.
- the column of ⁇ dj indicates the Abbe number for the d-line of the jth optical element.
- the basic lens data includes the aperture stop St and the optical member PP, and the word “St” is also written in the surface number column of the surface corresponding to the aperture stop St.
- the surface number of the aspheric surface is marked with *, and the paraxial curvature radius (center curvature radius) is shown as the curvature radius of the aspheric surface.
- the aspheric data shows the surface number of the aspheric surface and the aspheric coefficient for each aspheric surface.
- the numerical value “E ⁇ n” (n: integer) of the aspheric data means “ ⁇ 10 ⁇ n”, and “E + n” means “ ⁇ 10n”.
- Zd Depth of aspheric surface (length of perpendicular drawn from a point on the aspherical surface of height Y to a plane perpendicular to the optical axis where the aspherical vertex contacts)
- Y Height (distance from the optical axis to the lens surface)
- C paraxial curvature KA
- Bf (in Air) is the distance on the optical axis Z from the image-side surface of the lens closest to the image side to the image plane Sim (corresponding to back focus, air-converted length)
- L (in Air) is the first The distance on the optical axis Z from the object side surface of the one lens L1 to the image plane Sim (the back focus component is the air conversion length)
- f is the focal length of the entire system
- f1 is the focal length of the first lens L1
- f2 is The focal length of the second lens L2
- f3 is the focal length of the third lens L3
- f34 is the combined focal length of the third lens L3 and the fourth lens L4, and
- f123 is the first lens L1, the second lens L2, and the third lens.
- Tables 29 and 30 collectively show values corresponding to the conditional expressions (1) to (20) of the respective examples.
- mm is used for the length, but this is an example, and the optical system can be used even with proportional enlargement or reduction, so other appropriate units may be used. it can.
- the first lens L1 is a glass spherical lens
- the second lens L2, the third lens L3, and the fourth lens L4 are plastic aspheric lenses.
- FIGS. 32A to 32D, FIGS. 33A to 33D, and FIGS. D Aberration diagrams of the imaging lenses according to Examples 1 to 28 are shown in FIGS. 32A to 32D, FIGS. 33A to 33D, and FIGS. D), FIGS. 35 (A) to 35 (D), FIGS. 36 (A) to 36 (D), FIGS. 37 (A) to 37 (D), FIGS. 38 (A) to 38 (D). 39 (A) to 39 (D), FIG. 40 (A) to FIG. 40 (D), FIG. 41 (A) to FIG. 41 (D), FIG. 42 (A) to FIG. 42 (D), FIG. 43 (A) to 43 (D), FIG. 44 (A) to FIG. 44 (D), FIG. 45 (A) to FIG. 45 (D), FIG. 46 (A) to FIG. 46 (D), FIG.
- FIG. 47D A) to FIG. 47D, FIG. 48A to FIG. 48D, FIG. 49A to FIG. 49D, FIG. 50A to FIG. 50D, and FIG. FIG. 51 (D), FIG. 52 (A) to FIG. 52 (D), and FIG. 53 (A) to FIG. D
- FIGS. 54 (A) to 54 (D) 55 (A) to 55 (D), 56 (A) to 56 (D), and 57 (A) to 57 (D).
- the aberration diagrams of Example 1 will be described as an example, but the same applies to the aberration diagrams of other Examples.
- 32 (A), 32 (B), 32 (C), and 32 (D) are spherical aberration, astigmatism, distortion (distortion aberration), and lateral chromatic aberration (magnification aberration) of the imaging lens according to Example 1, respectively.
- the aberration diagram of chromatic aberration of magnification is shown.
- F in the spherical aberration diagram means F value
- ⁇ in other aberration diagrams means half angle of view.
- the distortion diagram shows the amount of deviation from the ideal image height of 2f ⁇ tan ( ⁇ / 2) using the focal length f and the angle of view ⁇ (variable treatment, 0 ⁇ ⁇ ⁇ ⁇ ) of the entire system.
- Each aberration diagram shows aberration with d-line (587.56 nm) as a reference wavelength, but spherical aberration diagram shows F-line (wavelength 486.13 nm), C-line (wavelength 656.27 nm), and sine condition violation
- the aberration for the quantity (denoted as SNC) is also shown, and the chromatic aberration diagram for the magnification shows the aberration for the F-line and C-line. Since the line type of the chromatic aberration diagram of magnification is the same as that of the spherical aberration diagram, the description is omitted.
- the imaging lenses of Examples 1 to 28 are configured with a small number of lenses of four, and can be manufactured in a small size and at a low cost, and the total angle of view is about 150 to 200 degrees. A wide angle of view is achieved, the F-number is as small as 2.0 to 2.6, each aberration is corrected well, and the optical performance is good.
- These imaging lenses can be suitably used for surveillance cameras, in-vehicle cameras for taking images of the front, side, rear, etc. of automobiles.
- FIG. 60 shows a state in which an imaging apparatus including the imaging lens of the present embodiment is mounted on the automobile 100.
- an automobile 100 includes an on-vehicle camera 101 for imaging a blind spot range on the side surface on the passenger seat side, an on-vehicle camera 102 for imaging a blind spot range on the rear side of the automobile 100, and a rear surface of a rearview mirror.
- An in-vehicle camera 103 is attached and is used for photographing the same field of view as the driver.
- the vehicle exterior camera 101, the vehicle exterior camera 102, and the vehicle interior camera 103 are imaging devices according to embodiments of the present invention, and convert an imaging lens according to an embodiment of the present invention and an optical image formed by the imaging lens into an electrical signal.
- An image pickup device An image pickup device.
- the outside cameras 101 and 102 and the inside camera 103 can also be configured to be small and inexpensive, have a wide angle of view, and have an imaging region peripheral portion. A good image can be obtained.
- the present invention has been described with reference to the embodiment and examples, the present invention is not limited to the above embodiment and example, and various modifications can be made.
- the values of the radius of curvature, the surface interval, the refractive index, and the Abbe number of each lens component are not limited to the values shown in the above numerical examples, and can take other values.
- all the lenses are made of a homogeneous material, but a gradient index lens may be used.
- the second lens L2 to the fourth lens L4 are constituted by refractive lenses provided with aspheric surfaces, but diffractive optical elements may be formed on one surface or a plurality of surfaces. .
- the present invention is not limited to this application, and for example, a mobile terminal camera or a surveillance camera The present invention can also be applied.
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Abstract
Description
下記条件式(1)を満足することを特徴とするものである。
ただし、
νd2:前記第2レンズの材質のd線に対するアッベ数
νd3:前記第3レンズの材質のd線に対するアッベ数
本発明の第2の撮像レンズは、物体側から順に、負の第1レンズと、負の第2レンズと、物体側に凸面を向けた平凸形状または物体側に凸面を向けた正メニスカス形状の第3レンズと、像側に凸面を向けた平凸形状または像側に凸面を向けた正メニスカス形状の第4レンズとを備え、
下記条件式(2)を満足することを特徴とするものである。
ただし、
Nd2:前記第2レンズの材質のd線に対する屈折率
Nd3:前記第3レンズの材質のd線に対する屈折率
本発明の第3の撮像レンズは、物体側から順に、負の第1レンズと、負の第2レンズと、物体側に凸面を向けた平凸形状または物体側に凸面を向けた正メニスカス形状の第3レンズと、像側に凸面を向けた平凸形状または像側に凸面を向けた正メニスカス形状の第4レンズとを備え、
下記条件式(8)を満足することを特徴とするものである。
ただし、
L:前記第1レンズの物体側の面頂点から像面までの距離
f:全系の焦点距離
本発明の第4の撮像レンズは、物体側から順に、負の第1レンズと、両凹形状の負の第2レンズと、物体側に凸面を向けた平凸形状または物体側に凸面を向けた正メニスカス形状の第3レンズと、像側に凸面を向けた平凸形状または像側に凸面を向けた正メニスカス形状の第4レンズとを備え、
下記条件式(9)を満足することを特徴とするものである。
ただし、
Bf:最も像側のレンズの像側の面頂点から像面までの距離(空気換算長)
f:全系の焦点距離
また、上記本発明の第1~第4の撮像レンズにおいては、下記条件式(3)~(7)、(10)~(20)、(3-1)~(7-1)、(11-1)、(12-1)、(12-2)を満足することが好ましい。なお、好ましい態様としては、下記条件式(3)~(7)、(10)~(20)、(3-1)~(7-1)、(11-1)のいずれか1つの構成を有するものでもよく、あるいは任意の2つ以上を組み合わせた構成を有するものでもよい。
1.0<|f2/f|<2.7 … (3-1)
1.0<D2/f<2.5 … (4)
1.0<D2/f<2.8 … (4-1)
1.5<f3/f<3.0 … (5)
1.5<f3/f<4.6 … (5-1)
0.75≦(R8-R9)/(R8+R9)≦1.0 … (6)
0.60≦(R8-R9)/(R8+R9)≦1.0 … (6-1)
6.2<|R8/f| … (7)
4.5<|R8/f| … (7-1)
1.5<(D4+D5)/f<3.3 … (10)
3.1<R4/f … (11)
R4/f<1.3 … (11-1)
-160<(R3-R4)/(R3+R4)<0.85 … (12)
-160<(R3-R4)/(R3+R4)<-1.0 … (12-1)
0.2<(R3-R4)/(R3+R4)<0.85 … (12-2)
8<R1/f<50 … (13)
2<R6/f … (14)
0.5<D3/f<5.0 … (15)
0.1≦(R1-R2)/(R1+R2)≦1.0 … (16)
0.2<R1/L<3.0 … (17)
-1.0≦(R5-R6)/(R5+R6)≦-0.1 … (18)
-0.8<f/f123<0.8 … (19)
1≦f34/f≦10 … (20)
ただし、
f:全系の焦点距離
f2:第2レンズの焦点距離
f3:第3レンズの焦点距離
R1:第1レンズ物体側の面の曲率半径
R2:第1レンズ像側の面の曲率半径
R3:第2レンズ物体側の面の曲率半径
R4:第2レンズ像側の面の曲率半径
R5:第3レンズ物体側の面の曲率半径
R6:第3レンズ像側の面の曲率半径
R8:第4レンズ物体側の面の曲率半径
R9:第4レンズ像側の面の曲率半径
D2:第1レンズと第2レンズとの光軸上の間隔
D3:第2レンズの中心厚
D4:第2レンズと第3レンズとの光軸上の空気間隔
D5:第3レンズの中心厚
f123:第1レンズ、第2レンズおよび第3レンズの合成焦点距離
f34:第3レンズおよび第4レンズの合成焦点距離
なお、本発明においては、凸面、凹面、平面、両凹、メニスカス、両凸、平凸および平凹等といったレンズの面形状、正のレンズおよび負のレンズといったレンズの屈折力の符号は、非球面が含まれているものについてはとくに断りのない限り近軸領域で考えるものとする。また、本発明においては、曲率半径の符号は、面形状が物体側に凸の場合を正、像側に凸の場合を負とすることにする。
まず、図1および図2を参照しながら、本発明の実施形態に係る撮像レンズについて説明する。図1は、本発明の実施形態に係る撮像レンズ1の構成と光路を示す図である。なお、図1に示す撮像レンズ1は後述する本発明の実施例3に係る撮像レンズに対応するものである。図1に示す撮像レンズ1は、以下に述べる本発明の第1から第3の実施形態の構成を備えている。
ただし、
νd2:第2レンズL2の材質のd線に対するアッベ数
νd3:第3レンズL3の材質のd線に対するアッベ数
条件式(1)の下限を満足することで、倍率色収差の補正が容易となる。
ただし、
Nd2:第2レンズL2の材質のd線に対する屈折率
Nd3:第3レンズL3の材質のd線に対する屈折率
条件式(2)の下限を満足することで、第3レンズL3の屈折率を大きくすることができ、第3レンズL3のパワーを強くすることが容易となり、倍率色収差および像面湾曲の補正が容易となる。または、第2レンズL2の屈折率が大きくなりすぎるのを抑えることができ、材質のアッベ数が小さくなりすぎるのを防ぐことができ、色収差の補正が容易となる。
ただし、
L:第1レンズL1の物体側の面頂点から像面までの距離
f:全系の焦点距離
条件式(8)の上限を満足することで、レンズ系の小型化が容易となる。条件式(8)の下限を下回ると、焦点距離が長くなりすぎてしまい、広角化を達成することが困難となるか、広角化のためにディストーションが大きくなりすぎてしまい、周辺の画像が小さく結像されてしまう。またはレンズ系が小型になりすぎてしまい、その結果、各レンズの厚さおよび間隔が小さくなることから、製造が困難となるとともに、コストアップの原因となる。
ただし、
Bf:最も像側のレンズの像側の面頂点から像面までの距離(空気換算長)
f:全系の焦点距離
条件式(9)の上限を上回ると、レンズ系が大型化してしまう。条件式(9)の下限を下回ると、レンズ系と撮像素子との間隔が小さくなりすぎてしまい、レンズ系と撮像素子との間に各種フィルタやカバーガラス等を挿入することが困難となったり、使用する撮像素子に制限ができたりしてしまう。
ただし、
f:全系の焦点距離
f2:第2レンズL2の焦点距離
条件式(3)の上限を満足することで、第2レンズL2のパワーを強くすることが容易となり、広角化が容易となるとともに、レンズ系を小型化することが容易となる。条件式(3)の下限を下回ると、第2レンズL2のパワーが強くなりすぎてしまい、光線が第2レンズL2で急激に曲げられてしまうため、ディストーションの補正が困難となるか、または像面湾曲の補正が困難となる。
第2レンズL2を物体側に凸面を向けた負メニスカス形状とすることで、レンズ系の径方向の小型化が容易となるため、上限を2.7としても、レンズ系の径方向のサイズを小型化することが容易となる。条件式(3-1)の下限を下回ると、第2レンズL2のパワーが強くなりすぎてしまい、光線が第2レンズL2で急激に曲げられてしまうため、ディストーションの補正が困難となるか、像面湾曲の補正が困難となる。なお、第2レンズL2を平凹形状としてもよい。
ただし、
f:全系の焦点距離
D2:第1レンズL1と第2レンズL2との光軸上の間隔
条件式(4)の上限を満足することで、レンズ系を小型化することが可能となる。条件式(4)の下限を下回ると、第1レンズL1と第2レンズL2との間隔が小さくなってしまい、第2レンズL2の物体側の面の面形状が制限され、像面湾曲およびディストーションの補正が困難となる。
第2レンズL2を両凹形状とすることで、広角化が容易となるとともに、像面湾曲、ディストーションおよび球面収差の補正が容易となる。また、第2レンズL2を両凹形状とした場合には、物体側に凸面を向けたメニスカス形状とした場合より、第2レンズL2の物体側の面の有効径端の点がより物体側に位置しやすくなる。このため、上限を2.8としても、レンズ系の大型化を防止しつつ、像面湾曲を補正することが容易となる。条件式(4-1)の下限を下回ると、第1レンズL1と第2レンズL2との間隔が小さくなってしまい、第2レンズ物体側の面の面形状が制限され、像面湾曲およびディストーションの補正が困難となる。なお、第2レンズL2を平凹形状としてもよい。
ただし、
f:全系の焦点距離
f3:第3レンズL3の焦点距離
条件式(5)の上限を満足することで、第3レンズL3のパワーが弱くなりすぎることを防止でき、像面湾曲および倍率色収差の補正が容易となる。条件式(5)の下限を下回ると、第3レンズL3のパワーが強くなりすぎてしまい、バックフォーカスが短くなりすぎてしまう。もしくは第3レンズL3のパワーが強くなりすぎてしまって偏心の製造誤差の許容量が少なくなりすぎてしまい、製造が困難となる。
第2レンズL2を両凹形状とすることで、広角化が容易となるとともに、像面湾曲、ディストーションおよび球面収差の補正が容易となる。また、第2レンズL2を両凹形状とすることで、像面湾曲の補正が容易となるため、上限を4.6としても、像面湾曲を良好に補正することが可能となる。条件式(5-1)の下限を下回ると、第3レンズL3のパワーが強くなりすぎてしまい、バックフォーカスが短くなりすぎてしまう。もしくは第3レンズL3のパワーが強くなりすぎてしまって偏心の製造誤差の許容量が少なくなりすぎてしまい、製造が困難となる。なお、第2レンズL2を平凹形状としてもよい。
ただし、
R8:第4レンズL4の物体側の面の曲率半径
R9:第4レンズL4の像側の面の曲率半径
条件式(6)の上限および下限を満足することで、第4レンズL4を像側に凸面を向けた平凸形状もしくは像側に凸面を向けたメニスカス形状にすることができ、像面湾曲と球面収差を良好に補正することが可能となる。条件式(6)の上限を満足することで、第4レンズL4の物体側の面を平面または凹面とすることができ、第4レンズL4のパワーが強くなりすぎるのを抑えることができ、バックフォーカスを長くすることが容易となる。条件式(6)の下限を満足することで、第4レンズL4の像側の面の曲率半径が小さくなりすぎてしまうのを防ぐことができ、第4レンズL4のパワーが弱くなりすぎるのを防止することができ、撮像素子周辺部で光線がセンサに入射する角度を抑えることが容易となるか、または物体側の面の曲率半径が大きくなりすぎてしまうのを防ぐことができ、球面収差の補正が容易となる。
第2レンズL2を両凹形状とすることで、広角化が容易となるとともに、像面湾曲、ディストーションおよび球面収差の補正が容易となる。また、第2レンズL2を両凹形状とすることで、第2レンズL2のパワーを強くすることが容易となり、レンズで光線を大きく曲げることができるため、第4レンズL4に入射する光線の角度を小さくすることができる。このため下限を0.60としても、周辺での光線がセンサに入射する角度を抑えることが可能となる。条件式(6-1)の上限および下限を満足することで、第4レンズL4を像側に凸面を向けた平凸形状もしくは像側に凸面を向けたメニスカス形状にすることができ、像面湾曲と球面収差を良好に補正することが可能となる。条件式(6-1)の上限を満足することで、第4レンズL4の物体側の面を平面または凹面とすることができ、第4レンズのパワーが強くなりすぎるのを抑えることができ、バックフォーカスを長くすることが容易となる。なお、第2レンズL2を平凹形状としてもよい。
ただし、
R8:第4レンズL4の物体側の面の曲率半径
f:全系の焦点距離
条件式(7)の下限を満足することで、球面収差の補正が容易となる。
第2レンズL2を両凹形状とすることで、広角化が容易となるとともに、像面湾曲、ディストーションおよび球面収差の補正が容易となる。また、第2レンズL2を両凹形状とすることで、球面収差の補正が容易となり、下限を4.5とした場合でも、良好な解像性能を得ることが可能となる。なお、第2レンズL2を平凹形状としてもよい。
ただし、
D4:第2レンズL2と第3レンズL3との光軸上の空気間隔
D5:第3レンズL3の中心厚
f:全系の焦点距離
第2レンズL2を両凹形状とすることで、広角化が容易となるとともに、像面湾曲、ディストーションおよび球面収差の補正が容易となる。条件式(10)を満足することで、球面収差、ディストーション、コマ収差が良好に補正され、さらにバックフォーカスが長くとれ、画角を大きくすることができ、十分な性能が得られる。条件式(10)の上限を満足することで、最も物体側の負レンズの径を小さくすることが容易となり、かつレンズ全長を短くすることが容易となるため、小型化が容易となる。条件式(10)の下限を満足することで、球面収差およびコマ収差の補正が容易となり、F値が小さなレンズを得るのが容易となる。なお、第2レンズL2を平凹形状としてもよい。
ただし、
R4:第2レンズL2の像側の面の曲率半径
f:全系の焦点距離
第2レンズL2を両凹形状とすることで、広角化が容易となるとともに、像面湾曲、ディストーションおよび球面収差の補正が容易となる。また、第2レンズL2が両凹形状でありながら、条件式(11)の下限を満足することで、第2レンズL2の像側の面の曲率半径が小さくなるのを抑えることができ、像面湾曲および球面収差の補正が容易となる。または、第2レンズL2のパワーを抑えることができ、このレンズで光線が急激に曲げられるのを抑えることができ、ディストーションの補正が容易となる。
第2レンズL2を物体側に凸面を向けたメニスカス形状とすることで、広角でありながらレンズ系の径方向を小型化することが可能となる。また、第2レンズL2が物体側に凸面を向けたメニスカス形状でありながら、条件式(11-1)の上限を上回ると、第2レンズL2のパワーが弱くなりすぎてしまい、広角化、ディストーションの補正が困難となる。なお、第2レンズL2は平凹レンズとしてもよい。
ただし、
R3:第2レンズL2の物体側の面の曲率半径
R4:第2レンズL2の像側の面の曲率半径
条件式(12)の上限を満足することで、物体側に凸面を向けたメニスカス形状で物体側の面の曲率半径を小さくすることが容易となり、レンズ系の小型化が容易となる。条件式(12)の下限を満足することで、両凹レンズにおいて、第2レンズL2の物体側の面の曲率半径絶対値を第2レンズL2の像側の面の曲率半径絶対値と比べて小さくすることが容易となり、像面湾曲、コマ収差および球面収差の補正が容易となる。
上限を-1.0とすると、第2レンズL2を物体側の面の曲率半径絶対値が像側の面の曲率半径の絶対値より小さい両凹レンズとすることができ、像面湾曲およびディストーションの補正が容易となる。条件式(12-1)の下限を満足することで、両凹レンズにおいて、第2レンズL2の物体側の面の曲率半径絶対値を第2レンズL2の像側の面の曲率半径絶対値と比べて小さくすることが容易となり、像面湾曲、コマ収差および球面収差の補正が容易となる。
第2レンズL2が物体側に凸面を向けたメニスカス形状でありながら下限を0.2とすると、第2レンズL2のパワーを強くすることが容易となり、像面湾曲およびディストーションの補正が容易となる。条件式(12-2)の上限を満足することで、物体側に凸面を向けたメニスカス形状で物体側の面の曲率半径を小さくすることが容易となり、レンズ系の小型化が容易となる。
ただし、
R1:第1レンズL1の物体側の面の曲率半径
f:全系の焦点距離
条件式(13)の上限を上回ると、第1レンズL1の物体側の面の曲率半径が大きくなり、この面で光線が急激に曲げられてしまうため、ディストーションの補正が困難となる。条件式(13)の下限を下回ると、第1レンズL1の物体側の面の曲率半径が小さくなりすぎてしまい、広角化が困難となる。
ただし、
R6:第3レンズL3の像側の面の曲率半径
f:全系の焦点距離
条件式(14)の下限を下回ると、第3レンズL3のパワーが弱くなり、像面湾曲、球面収差および倍率色収差の補正が困難となる。
ただし、
D3:第2レンズL2の中心厚
f:全系の焦点距離
条件式(15)の上限を上回るとレンズ系が大型化してしまう。条件式(15)の下限を下回ると、第2レンズL2の中心厚が小さくなってしまい、第2レンズL2の周辺部と中心部との肉厚比が大きくなり、成形が困難となる。
ただし、
R1:第1レンズL1の物体側の面の曲率半径
R2:第1レンズL1の像側の面の曲率半径
条件式(16)の上限を上回ると、第1レンズL1の物体側の面が凹面となってしまい、この面で光線が急激に曲げられてしまうため、ディストーションの補正が困難となる。または、周辺の光線がレンズ面に入射する角度が大きくなり、反射損失が大きくなるため周辺が暗くなってしまう。条件式(16)の下限を下回ると、第1レンズL1の物体側の面の曲率半径と像側の面の曲率半径とが近くなり、第1レンズL1のパワーが弱くなるため広角化が困難となる。
ただし、
R1:第1レンズL1の物体側の面の曲率半径
L:第1レンズL1の物体側の面頂点から像面までの距離
条件式(17)の上限を上回ると、第1レンズL1の物体側の面の曲率半径が大きくなりすぎてしまい、この面で光線が急激に曲げられてしまうためディストーションの補正が困難となる。条件式(17)の下限を下回ると、全長が長くなりすぎてしまい小型化が困難となるか、または第1レンズL1の物体側の面の曲率半径が小さくなりすぎてしまい広角化が困難となる。
ただし、
R5:第3レンズL3の物体側の面の曲率半径
R6:第3レンズL3の像側の面の曲率半径
条件式(18)の上限を上回ると、物体側の面と像側の面との曲率半径の絶対値が近くなり、第3レンズL3のパワーが弱くなるため、倍率色収差、球面収差の補正が困難となる。条件式(18)の下限を満足することで、第3レンズL3を物体側に凸面を向けた平凸形状もしくは物体側に凸面を向けたメニスカス形状とすることが可能となり、像面湾曲およびコマ収差の補正が容易となる。
ただし、
f:全系の焦点距離
f123:第1レンズL1、第2レンズL2および第3レンズL3の合成焦点距離
条件式(19)の上限を上回ると、第1レンズL1、第2レンズL2および、第3レンズL3の合成パワーが強い正のパワーとなりすぎる。すなわち、第3レンズL3の正のパワーが強くなりすぎてバックフォーカスが短くなってしまうか、または第1レンズL1および第2レンズL2の負のパワーが弱くなり、広角化が困難となるか、レンズが大型化してしまう。条件式(19)の下限を下回ると、第1レンズL1および第2レンズL2の負のパワーが強くなりすぎて像面湾曲補正が困難となるか、または第3レンズL3の正のパワーが弱くなりすぎて像面湾曲および倍率色収差の補正が困難となる。
ただし、
f34:第3レンズL3と第4レンズL4との合成焦点距離
f:全系の焦点距離
条件式(20)の上限を越えると、第3レンズL3と第4レンズL4との合成パワーが弱くなり、像面湾曲および倍率色収差の補正が困難となるとともに、撮像素子への光線の入射角度を抑えることが困難となる。条件式(20)の下限を下回ると、第3レンズL3と第4レンズL4との合成パワーが強くなりすぎてしまい、バックフォーカスの確保が困難となる。
2.35<νd2/νd3 … (1-3)
2.25<νd2/νd3<2.8 … (1-4)
2.3 <νd2/νd3<2.7 … (1-5)
2.35<νd2/νd3<2.6 … (1-6)
条件式(2)の下限は、0.10以上とすることが好ましい。これにより、色収差および像面湾曲の補正がさらに容易となる。条件式(2)の上限を設定することが好ましく、上限の値としては0.16が好ましく、これにより、第2レンズL2の屈折率を高くすることが容易となるため、広角化とともにディストーションの補正が容易となる。もしくは、第3レンズL3の屈折率が高くなるのを抑えることができ、第3レンズL3の材料のコストを抑えることが容易となる。さらに広角化、ディストーションの補正およびコスト抑制を容易とするためには、条件式(2)の上限値として0.14がより好ましく、0.11がさらに好ましい。
0.09<Nd3-Nd2<0.16 … (2-2)
0.10≦Nd3-Nd2<0.14 … (2-3)
0.10≦Nd3-Nd2<0.11 … (2-4)
条件式(3)および条件式(3-1)の下限の変更値としては、1.2が好ましく、これにより、上記の作用効果を高めることが可能となる。さらに作用効果を高めるためには、1.5がより好ましく1.7がさらに好ましく、1.8がさらにより好ましく、1.9がさらによりいっそう好ましい。条件式(3)および条件式(3-1)の上限の変更値としては、2.4が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、2.2がより好ましく、2.19がさらに好ましく、2.18がさらにより好ましく、2.15がさらによりいっそう好ましい。
1.2<|f2/f|<2.6 … (3-3)
1.5<|f2/f|<2.4 … (3-4)
1.7<|f2/f|<2.2 … (3-5)
1.8<|f2/f|<2.19 … (3-6)
1.9<|f2/f|<2.18 … (3-7)
1.9<|f2/f|<2.6 … (3-8)
条件式(4)の下限の変更値としては、1.5が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、2がより好ましく、2.04がさらに好ましい。条件式(4)の上限の変更値としては、2.4が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、2.2がより好ましい。
2<D2/f<2.4 … (4-3)
2.04<D2/f<2.2 … (4-4)
条件式(4-1)の下限の変更値としては、1.5が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、2がより好ましく、2.04がさらに好ましい。条件式(4-1)の上限の変更値としては、2.7が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、2.5がより好ましく、2.3がさらに好ましい。
1.5<D2/f<2.7 … (4-6)
1.5<D2/f<2.5 … (4-7)
2<D2/f<2.3 … (4-8)
条件式(5)の下限の変更値としては、2が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、2.2がより好ましく、2.5がさらに好ましい。条件式(5)の上限の変更値としては、2.95が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、2.9がより好ましく、2.88がさらに好ましく、2.8がさらにより好ましい。
2.2<f3/f<2.9 … (5-7)
2.5<f3/f<2.88 … (5-8)
条件式(5-1)の下限の変更値としては、2が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、2.2がより好ましく、2.5がさらに好ましい。条件式(5-1)の上限の変更値としては、4.4が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、4.2がより好ましく、3.5がさらに好ましく、3.2がさらにより好ましい。
1.5<f3/f<4.2 … (5-3)
1.5<f3/f<3.5 … (5-4)
2.2<f3/f<3.2 … (5-5)
条件式(6)の下限の変更値としては、0.78が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、0.81がより好ましい。条件式(6)の上限の変更値としては、0.99が好ましく、これにより、バックフォーカスを長くすることがさらに容易となる。さらにバックフォーカスを長くするためには、0.95がより好ましい。
0.81≦(R8-R9)/(R8+R9)≦0.95 … (6-3)
条件式(6-1)の下限の変更値としては、0.65が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、0.7がより好ましい。条件式(6-1)の上限の変更値としては、0.99が好ましく、これにより、バックフォーカスを長くすることがさらに容易となる。さらにバックフォーカスを長くするためには、0.95がより好ましい。
0.7 ≦(R8-R9)/(R8+R9)≦1.0 … (6-5)
0.65≦(R8-R9)/(R8+R9)≦0.99 … (6-6)
条件式(7)の下限の変更値としては、7が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、10がより好ましく、15がさらに好ましく、20がさらにより好ましい。条件式(7)の上限を設定することが好ましく、条件式(7)の上限値としては、10000が好ましく、これを満足することで、像面湾曲およびコマ収差の補正が容易となる。さらに像面湾曲およびコマ収差の補正を容易とするためには、上限値は1000とすることがより好ましく、500がさらに好ましい。
7.0<|R8/f|<10000 … (7-3)
10<|R8/f|<1000 … (7-4)
15<|R8/f|<500 … (7-5)
条件式(7-1)の下限の変更値としては、5が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、6がより好ましく、6.5がさらに好ましい。条件式(7-1)の上限を設定することが好ましく、条件式(7-1)の上限値としては、10000が好ましく、これにより、像面湾曲およびコマ収差の補正が容易となる。さらに像面湾曲およびコマ収差の補正を容易とするためには、1000がより好ましく、500がさらに好ましい。
5<|R8/f|<10000 … (7-7)
6<|R8/f|<1000 … (7-8)
6.5<|R8/f|<500 … (7-9)
条件式(8)の下限の変更値としては、9が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、10がより好ましく、10.5がさらに好ましい。条件式(8)の上限の変更値としては、13.8が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、13.5がより好ましく、13がさらに好ましく、12がさらにより好ましい。
9.0<L/f<13.5 … (8-2)
10 <L/f<13 … (8-3)
10.5<L/f<12 … (8-4)
条件式(9)の下限の変更値としては、1.5が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、1.7がより好ましい。条件式(9)の上限の変更値としては、2.8が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、2.5がより好ましく、2.35がさらに好ましい。
1.5<Bf/f<2.5 … (9-2)
1.7<Bf/f<2.3 … (9-3)
条件式(10)の下限の変更値としては、2が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、2.3がより好ましく、2.5がさらに好ましい。条件式(10)の上限の変更値としては、3.2が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、3がより好ましく、2.9がさらに好ましい。
2.3<(D4+D5)/f<3 … (10-2)
2.5<(D4+D5)/f<2.9 … (10-3)
条件式(11)の下限の変更値としては、3.2が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、3.3がより好ましく、3.5がさらに好ましく、3.8がさらにより好ましい。条件式(11)に上限値を設定することが好ましく、上限の値としては、50が好ましく、これにより、第2レンズL2の像側の面の曲率半径が大きくなりすぎるのを防ぐことができ、ディストーションの補正が容易となる。さらにディストーションの補正を容易とするためには、上限値としては、20.0がより好ましく、10.0がさらにより好ましく、8がより好ましく、6がさらに好ましい。
3.2<R4/f<20.0 … (11-3)
3.3<R4/f<10.0 … (11-4)
3.5<R4/f<8.0 … (11-5)
3.8<R4/f<6.0 … (11-6)
条件式(11-1)に下限値を設定することが好ましく、下限値としては、0.1が好ましく、これにより、像面湾曲の補正が容易となる。さらに像面湾曲の補正を容易とするためには、0.5がより好ましく、0.7がより好ましく、0.8がさらに好ましい。条件式(11-1)の上限の変更値としては、1.2が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、1.1がより好ましく、1がさらに好ましい。
0.5<R4/f<1.2 … (11-8)
0.7<R4/f<1.1 … (11-9)
0.8<R4/f<1 … (11-10)
条件式(12)の下限の変更値としては、-30が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、-20がより好ましく、-10がさらに好ましく、-8がさらにより好ましい。条件式(12)の上限の変更値としては、0.82が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、0.8がより好ましく、1がさらに好ましい。
-20<(R3-R4)/(R3+R4)<0.82 … (12-4)
-10<(R3-R4)/(R3+R4)<0.8 … (12-5)
-8<(R3-R4)/(R3+R4)<1 … (12-6)
条件式(12-1)の上限の変更値としては、-1.1が好ましく、これにより、像側の面の曲率半径が大きくなりすぎたり、物体側の面の曲率半径が小さくなりすぎるのを抑えることが容易となり、像面湾曲およびディストーションの補正が容易となる。さらに作用効果を高めるためには、-1.5がより好ましく、-2.0がさらに好ましい。条件式(12-1)の下限の変更値は、条件式(12)と同様に考えることができる。
-30<(R3-R4)/(R3+R4)<-1.5 … (12-8)
条件式(12-2)の下限の変更値としては、0.3が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、0.5がより好ましく、0.7がさらに好ましい。条件式(12-2)の上限の変更値は、条件式(12)と同様に考えることができる。
0.5<(R3-R4)/(R3+R4)<0.82 … (12-10)
条件式(13)の下限の変更値としては、10が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、12がより好ましく、13がさらに好ましい。条件式(13)の上限の変更値としては、35が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、30がより好ましく、26がさらに好ましい。
12<R1/f<30 … (13-2)
13<R1/f<26 … (13-3)
条件式(14)の下限の変更値としては、6が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、20がより好ましく、30がさらに好ましく、35がさらにより好ましい。条件式(14)に上限を設定することが好ましく、上限の値としては、5000が好ましく、これにより、像面湾曲およびコマ収差の補正が容易となる。さらに像面湾曲およびコマ収差を良好に補正するためには、上限値として1000がより好ましく、100がさらに好ましく、70がさらによりいっそう好ましい。
6<R6/f<5000 … (14-2)
20<R6/f<1000 … (14-3)
30<R6/f<100 … (14-4)
35<R6/f<70 … (14-5)
条件式(15)の下限の変更値としては、0.7が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、0.8がより好ましく、0.9がさらに好ましい。条件式(15)の上限の変更値としては、2が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、1.8がより好ましく、1.5がさらに好ましい。
0.8<D3/f<1.8 … (15-2)
0.9<D3/f<1.5 … (15-3)
条件式(16)の下限の変更値としては、0.4が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、0.5がより好ましく、0.55がさらに好ましい。条件式(16)の上限の変更値としては、0.7が好ましく、これにより、ディストーションの補正がさらに容易となる。さらにディストーションの補正を容易とするためには、0.68がより好ましい。
0.5≦(R1-R2)/(R1+R2)≦0.7 … (16-2)
0.55≦(R1-R2)/(R1+R2)≦0.68 … (16-3)
条件式(17)の下限の変更値としては、0.5が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、1がより好ましく、1.1がさらに好ましく、1.2がさらにより好ましい。条件式(17)の上限の変更値としては、2が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、1.7がより好ましく、1.5がさらに好ましい。
1.0<R1/L<2.0 … (17-2)
1.1<R1/L<1.7 … (17-3)
1.2<R1/L<1.5 … (17-4)
条件式(18)の上限の変更値としては、-0.2が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、-0.4がより好ましく、-0.6がさらに好ましく、-0.7がさらにより好ましい。
-1.0≦(R5-R6)/(R5+R6)≦-0.4 … (18-2)
-1.0≦(R5-R6)/(R5+R6)≦-0.6 … (18-3)
-1.0≦(R5-R6)/(R5+R6)≦-0.7 … (18-4)
条件式(19)の下限の変更値としては、-0.6が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、-0.5がより好ましく、-0.3がさらにより好ましい。条件式(19)の上限の変更値としては、0.5が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、0.3がより好ましく、0.1がさらに好ましい。
-0.5<f/f123<0.3 … (19-2)
-0.3<f/f123<0.1 … (19-3)
条件式(20)の下限の変更値としては、1.5が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、2がより好ましい。条件式(20)の上限の変更値としては、8が好ましく、これにより、上記の作用効果をより高めることが可能となる。さらに作用効果を高めるためには、6.5がより好ましい。
2.0≦f34/f≦6.5 … (20-2)
開口絞りは第3レンズL3と第4レンズL4との間に配置されていることが好ましい。開口絞りを第3レンズL3と第4レンズL4との間に配置することで系全体を小型化することが可能となる。
次に、本発明の撮像レンズの数値実施例について説明する。実施例1~実施例28の撮像レンズのレンズ断面図をそれぞれ図4~図31に示す。図4~図31において、図の左側が物体側、右側が像側であり、図1および図2と同様、開口絞りSt、光学部材PP、像面Simに配置された撮像素子5も併せて図示している。各図の開口絞りStは形状や大きさを表すものではなく、光軸Z上の位置を示すものである。各実施例において、レンズ断面図の符号Ri、Di(i=1、2、3、…)は以下に説明するレンズデータのRi、Diと対応している。
垂直な平面に下ろした垂線の長さ)
Y:高さ(光軸からのレンズ面までの距離)
C:近軸曲率
KA、RBm:非球面係数(m=3、4、5、…20)
各種データにおいて、Fno.はFナンバー、Bf(in Air)は最も像側のレンズの像側の面から像面Simまでの光軸Z上の距離(バックフォーカスに相当、空気換算長)、L(in Air)は第1レンズL1の物体側の面から像面Simまでの光軸Z上の距離(バックフォーカス分は空気換算長)、fは全系の焦点距離、f1は第1レンズL1の焦点距離、f2は第2レンズL2の焦点距離、f3は第3レンズL3の焦点距離、f34は第3レンズL3と第4レンズL4との合成焦点距離、f123は第1レンズL1と第2レンズL2と第3レンズL3との合成焦点距離であるである。
図60に使用例として、自動車100に本実施形態の撮像レンズを備えた撮像装置を搭載した様子を示す。図60において、自動車100は、その助手席側の側面の死角範囲を撮像するための車外カメラ101と、自動車100の後側の死角範囲を撮像するための車外カメラ102と、ルームミラーの背面に取り付けられ、ドライバーと同じ視野範囲を撮影するための車内カメラ103とを備えている。車外カメラ101と車外カメラ102と車内カメラ103とは、本発明の実施形態に係る撮像装置であり、本発明の実施例の撮像レンズと、該撮像レンズにより形成される光学像を電気信号に変換する撮像素子とを備えている。
Claims (21)
- 物体側から順に、負の第1レンズと、負の第2レンズと、物体側に凸面を向けた平凸形状または物体側に凸面を向けた正メニスカス形状の第3レンズと、像側に凸面を向けた平凸形状または像側に凸面を向けた正メニスカス形状の第4レンズとを備え、
下記条件式(1)を満足することを特徴とする撮像レンズ。
2.25<νd2/νd3 … (1)
ただし、
νd2:前記第2レンズの材質のd線に対するアッベ数
νd3:前記第3レンズの材質のd線に対するアッベ数 - 下記条件式(1-4)を満足することを特徴とする請求項1記載の撮像レンズ。
2.25<νd2/νd3<2.8 … (1-4) - 下記条件式(1-6)を満足することを特徴とする請求項1記載の撮像レンズ。
2.35<νd2/νd3<2.6 … (1-6) - 物体側から順に、負の第1レンズと、負の第2レンズと、物体側に凸面を向けた平凸形状または物体側に凸面を向けた正メニスカス形状の第3レンズと、像側に凸面を向けた平凸形状または像側に凸面を向けた正メニスカス形状の第4レンズとを備え、
下記条件式(2)を満足することを特徴とする撮像レンズ。
0.09<Nd3-Nd2 … (2)
ただし、
Nd2:前記第2レンズの材質のd線に対する屈折率
Nd3:前記第3レンズの材質のd線に対する屈折率 - 下記条件式(2-2)を満足することを特徴とする請求項4記載の撮像レンズ。
0.09<Nd3-Nd2<0.16 … (2-2) - 物体側から順に、負の第1レンズと、負の第2レンズと、物体側に凸面を向けた平凸形状または物体側に凸面を向けた正メニスカス形状の第3レンズと、像側に凸面を向けた平凸形状または像側に凸面を向けた正メニスカス形状の第4レンズとを備え、
下記条件式(8)を満足することを特徴とする撮像レンズ。
8.0<L/f< 13.9 … (8)
ただし、
L:前記第1レンズの物体側の面頂点から像面までの距離
f:全系の焦点距離 - 下記条件式(8-2)を満足することを特徴とする請求項6記載の撮像レンズ。
9.0<L/f<13.5 … (8-2) - 下記条件式(8-3)を満足することを特徴とする請求項6記載の撮像レンズ。
10 <L/f<13 … (8-3) - 物体側から順に、負の第1レンズと、両凹形状の負の第2レンズと、物体側に凸面を向けた平凸形状または物体側に凸面を向けた正メニスカス形状の第3レンズと、像側に凸面を向けた平凸形状または像側に凸面を向けた正メニスカス形状の第4レンズとを備え、
下記条件式(9)を満足することを特徴とする撮像レンズ。
1.0<Bf/f<3.0 … (9)
ただし、
Bf:最も像側のレンズの像側の面頂点から像面までの距離(空気換算長)
f:全系の焦点距離 - 下記条件式(9-2)を満足することを特徴とする請求項9記載の撮像レンズ。
1.5<Bf/f<2.5 … (9-2) - 下記条件式(9-3)を満足することを特徴とする請求項9記載の撮像レンズ。
1.7<Bf/f<2.3 … (9-3) - 下記条件式(13)を満足することを特徴とする請求項1から11のいずれか1項記載の撮像レンズ。
8<R1/f<50 … (13)
ただし、
R1:前記第1レンズの物体側の面の曲率半径
f:全系の焦点距離 - 下記条件式(14)を満足することを特徴とする請求項1から12のいずれか1項記載の撮像レンズ。
2<R6/f … (14)
ただし、
R6:前記第3レンズの像側の面の曲率半径
f:全系の焦点距離 - 下記条件式(15)を満足することを特徴とする請求項1から13のいずれか1項記載の撮像レンズ。
0.5<D3/f<5.0 … (15)
ただし、
D3:前記第2レンズの中心厚
f:全系の焦点距離 - 下記条件式(16)を満足することを特徴とする請求項1から14のいずれか1項記載の撮像レンズ。
0.1≦(R1-R2)/(R1+R2)≦1.0 … (16)
ただし、
R1:前記第1レンズの物体側の面の曲率半径
R2:前記第1レンズの像側の面の曲率半径 - 下記条件式(17)を満足することを特徴とする請求項1から15のいずれか1項記載の撮像レンズ。
0.2<R1/L<3.0 … (17)
ただし、
R1:前記第1レンズの物体側の面の曲率半径
L:前記第1レンズの物体側の面頂点から像面までの距離 - 下記条件式(18)を満足することを特徴とする請求項1から16のいずれか1項記載の撮像レンズ。
-1.0≦(R5-R6)/(R5+R6)≦-0.1 … (18)
ただし、
R5:前記第3レンズ物体側の面の曲率半径
R6:前記第3レンズ像側の面の曲率半径 - 下記条件式(19)を満足することを特徴とする請求項1から17のいずれか1項記載の撮像レンズ。
-0.8<f/f123<0.8 … (19)
ただし、
f:全系の焦点距離
f123:前記第1レンズ、前記第2レンズおよび前記第3レンズの合成焦点距離 - 下記条件式(20)を満足することを特徴とする請求項1から18のいずれか1項記載の撮像レンズ。
1≦f34/f≦10 … (20)
ただし、
f34:前記第3レンズおよび前記第4レンズの合成焦点距離
f:全系の焦点距離 - 前記第3レンズを構成する材質がポリカーボネイトであることを特徴とする請求項1から19のいずれか1項記載の撮像レンズ。
- 前記1から20のいずれか1項記載の撮像レンズを搭載した撮像装置。
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Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
TW390459U (en) | 1998-05-22 | 2000-05-11 | Global Win Technology Co Ltd | Improved folding heat radiator |
JP2005227426A (ja) * | 2004-02-12 | 2005-08-25 | Nagano Kogaku Kenkyusho:Kk | 広角レンズ |
JP2006259704A (ja) | 2005-02-21 | 2006-09-28 | Fujinon Corp | 広角撮像レンズ |
JP2007206516A (ja) * | 2006-02-03 | 2007-08-16 | Enplas Corp | 撮像レンズ |
JP2009003343A (ja) * | 2007-06-25 | 2009-01-08 | Fujinon Corp | 超広角撮像レンズおよび撮像装置 |
JP2009265354A (ja) * | 2008-04-25 | 2009-11-12 | Fujinon Corp | 撮像レンズおよびこの撮像レンズを用いた撮像装置 |
JP2010014855A (ja) * | 2008-07-02 | 2010-01-21 | Fujinon Corp | 撮像レンズおよび撮像装置 |
JP2011065132A (ja) | 2009-04-10 | 2011-03-31 | Fujifilm Corp | 撮像レンズおよび撮像装置 |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4885776B2 (ja) | 2007-03-27 | 2012-02-29 | 富士フイルム株式会社 | 撮像用広角レンズおよび撮像装置 |
JP5270425B2 (ja) * | 2009-03-31 | 2013-08-21 | 富士フイルム株式会社 | 撮像レンズおよび撮像装置 |
JP2011158868A (ja) * | 2010-02-04 | 2011-08-18 | Fujifilm Corp | 撮像レンズおよび撮像装置 |
-
2012
- 2012-04-27 JP JP2013511942A patent/JP5778259B2/ja not_active Expired - Fee Related
- 2012-04-27 US US14/063,099 patent/US9036278B2/en not_active Expired - Fee Related
- 2012-04-27 WO PCT/JP2012/002899 patent/WO2012147359A1/ja active Application Filing
- 2012-04-27 EP EP12776822.4A patent/EP2703866A4/en not_active Withdrawn
- 2012-04-27 CN CN201290000468.5U patent/CN203519913U/zh not_active Expired - Lifetime
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
TW390459U (en) | 1998-05-22 | 2000-05-11 | Global Win Technology Co Ltd | Improved folding heat radiator |
JP2005227426A (ja) * | 2004-02-12 | 2005-08-25 | Nagano Kogaku Kenkyusho:Kk | 広角レンズ |
JP2006259704A (ja) | 2005-02-21 | 2006-09-28 | Fujinon Corp | 広角撮像レンズ |
JP2007206516A (ja) * | 2006-02-03 | 2007-08-16 | Enplas Corp | 撮像レンズ |
JP2009003343A (ja) * | 2007-06-25 | 2009-01-08 | Fujinon Corp | 超広角撮像レンズおよび撮像装置 |
JP2009265354A (ja) * | 2008-04-25 | 2009-11-12 | Fujinon Corp | 撮像レンズおよびこの撮像レンズを用いた撮像装置 |
JP2010014855A (ja) * | 2008-07-02 | 2010-01-21 | Fujinon Corp | 撮像レンズおよび撮像装置 |
JP2011065132A (ja) | 2009-04-10 | 2011-03-31 | Fujifilm Corp | 撮像レンズおよび撮像装置 |
Non-Patent Citations (1)
Title |
---|
See also references of EP2703866A4 |
Also Published As
Publication number | Publication date |
---|---|
EP2703866A1 (en) | 2014-03-05 |
US9036278B2 (en) | 2015-05-19 |
CN203519913U (zh) | 2014-04-02 |
US20140078604A1 (en) | 2014-03-20 |
JPWO2012147359A1 (ja) | 2014-07-28 |
EP2703866A4 (en) | 2015-04-22 |
JP5778259B2 (ja) | 2015-09-16 |
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