JP2014215519A - Image-capturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image-capturing device for realizing a high magnification zoom function.SOLUTION: An image-capturing device 1 comprises a first lens group 10 including a first liquid crystal lens 11, a second lens group 20 including a second liquid crystal lens 21, a third lens group 30 including a fixed lens, and an image-capturing element for receiving light having passed through the third lens group 30 and converting the received light into an electric signal. The first lens group 10, the second lens group 20, and the third lens group 30 are positioned relative to each other, and are arranged so that light passes through the first lens group 10, the second lens group 20, and the third lens group 30 in the order stated. A first group principal pint M1 which is the principal point of the first lens group 10, a second group principal pint M2 which is the principal point of the second lens group 20, and a third group principal pint M3 which is the principal point of the third lens group 30 are located on the same optical axis, a distance between the first group principal pint M1 and the second group principal pint M2 being longer than a distance between the second group principal pint M2 and the third group principal pint M3.

Description

  The present invention relates to an imaging apparatus.

  A lens module having a fixed lens and a liquid crystal lens is known. Patent Document 1 describes an optical lens module in which two liquid crystal lenses are arranged. In the optical lens module described in Patent Document 1, the two liquid crystal lenses are arranged with a fixed distance between the liquid crystal lenses.

JP 2009-145878 A

  However, the lens module described in Patent Document 1 includes only a plurality of meniscus lenses in order to correct aberrations in addition to the liquid crystal lens. For this reason, it is difficult for the lens module described in Patent Document 1 to realize a zoom function at a high magnification.

  An object of the present invention is to provide an imaging device that realizes a zoom function with high magnification.

  An imaging apparatus according to the present invention includes a first lens group including at least one first liquid crystal lens, a second lens group including at least one second liquid crystal lens, and a third lens group including at least one fixed lens. An image sensor that receives light passing through the third lens group and converts the received light into an electrical signal, and the first lens group, the second lens group, and the third lens group are positioned with respect to each other, The first lens group, the second lens group, and the second lens group are arranged so that light passes through the first lens group, the second lens group, and the third lens group in this order, and are the main points on the image sensor side of the first lens group. The second group principal point, which is the principal point on the image sensor side, and the third group principal point, which is the principal point on the image sensor side of the third lens group, are located on the same optical axis, and the first group principal point And the second group principal point is longer than the distance between the second group principal point and the third group principal point. That.

  In the imaging apparatus according to the present invention, the first lens group, the second lens group, and the third lens group are principal points on the imaging element side of each lens group, a first group principal point, a second group principal point, And the third group principal point is located on the same optical axis, and the distance between the first group principal point and the second group principal point is longer than the distance between the second group principal point and the third group principal point. Are arranged to be. Since the first lens group, the second lens group, and the third lens group are positioned with respect to each other, the distance between the first lens group, the second lens group, and the third lens group is fixed. . As a result, a high magnification zoom function can be realized without moving the first lens group, the second lens group, and the third lens group in the optical axis direction.

  The first lens group, the second lens group, and the third lens group are respectively positioned with respect to the imaging element, and the polarity of the lens power of the first lens group and the polarity of the lens power of the second lens group are A control means for controlling the polarity of the lens power of the first liquid crystal lens and the polarity of the lens power of the second liquid crystal lens may be provided so as to be reversed. In this case, the control means can control to form a so-called afocal system in which the lens power obtained by synthesizing the lens power of the first lens group and the lens power of the second lens group is set to 0. A high magnification zoom function can be realized without moving the first lens group, the second lens group, and the third lens group with respect to the image sensor.

  The control means is such that the lens power polarity of the first lens group is negative, the lens power polarity of the second lens group is positive, and the lens power polarity of the first lens group is positive, The polarity of the lens power of the first liquid crystal lens and the polarity of the lens power of the second liquid crystal lens may be controlled so that either one of the polarities of the lens power of the lens group is negative. In this case, by controlling the polarity of the lens power of the first lens group to be negative and the polarity of the lens power of the second lens group to be positive, the light that has entered through the optical path with a wider viewing angle can be captured. Therefore, it functions as a wide-angle lens. By controlling the polarity of the lens power of the first lens group to be positive and the polarity of the lens power of the second lens group to be negative, the light entering from a farther subject is imaged on the image sensor. Can function as a telephoto lens. Therefore, the functions of the wide-angle lens and the telephoto lens can be realized.

  The lens included in the first lens group other than the first liquid crystal lens has a negative lens power polarity of the entire lens other than the first liquid crystal lens, and the lens included in the second lens group other than the second liquid crystal lens is The polarity of the lens power of the entire lens other than the second liquid crystal lens may be positive. In this case, since the angle of view of the light that is incident on the first liquid crystal lens group and contributes to the image formation can be allowed to be larger, it is possible to increase without increasing the size of the first liquid crystal lens and the second liquid crystal lens. A high magnification zoom function can be achieved.

  The third lens group may include at least one third liquid crystal lens and further include a control unit that controls the lens power of the third liquid crystal lens. In this case, the image forming position is affected by the lens power of the third liquid crystal lens included in the third lens group with respect to minute fluctuations in the image forming position of the emitted light of the third lens group caused by the difference in perspective of the subject. Can be controlled in a direction perpendicular to the imaging surface of the imaging device. Therefore, it is possible to realize a control for always forming an image of a subject on the image sensor, that is, a focus adjustment function.

  Control means for controlling the orientation of the liquid crystal molecules of the third liquid crystal lens may be further provided so that the imaging position with respect to the image sensor moves. In this case, since the imaging position of the imaging element within the imaging surface can be controlled, it is possible to perform hand shake correction.

  You may further provide the 1st reflection member which is arrange | positioned on the optical path between a 1st lens group and a 2nd lens group, and reflects the light from a 1st lens group to a 2nd lens group. In this case, the optical path of the light incident on the first lens group is bent by the first reflecting member. For this reason, the size of the imaging device can be reduced when viewed along the optical axis of the light incident on the first lens group. Accordingly, the height of the imaging device can be reduced.

  A first reflection member and a second reflection arranged on the optical path between the first lens group and the second lens group so that the traveling direction of the light is reversed between the first lens group and the second lens group. A member may be further provided. In this case, the optical path of the light incident on the first lens group is bent by the first reflecting member, and further bent by the second reflecting member to the side where the first lens group is disposed. For this reason, when viewed along the optical axis of the light incident on the first lens group, the size of the imaging device can be further reduced. Therefore, the imaging device can be further downsized.

  The first reflecting member and the second reflecting member may be arranged so that the incident angle of light incident on the first reflecting member is different from the reflection angle of light reflected by the second reflecting member. In this case, the first reflecting member and the second reflecting member are arranged at different angles with respect to a plane perpendicular to the optical axis of the light incident on the first lens group. For this reason, when viewed along the optical axis of the light incident on the first lens group, the size of the imaging device can be further reduced. Therefore, the imaging device can be further downsized.

  According to the present invention, it is possible to provide an imaging device that realizes a high-magnification zoom function.

It is a schematic diagram for demonstrating the structure of the imaging device which concerns on 1st embodiment. It is a figure for demonstrating the cross-sectional structure of a liquid-crystal lens. It is a figure for demonstrating the relationship between a liquid crystal lens and lens power. It is a figure for demonstrating the structure of a liquid crystal lens. It is a figure for demonstrating the relationship between a liquid crystal lens and a focus position. It is a figure for demonstrating the lens system which implement | achieves a zoom function in a prior art, and the lens system which implement | achieves a zoom function in this embodiment. It is a schematic diagram for demonstrating the structure of the imaging device which concerns on 2nd embodiment. It is a schematic diagram for demonstrating the structure of the imaging device which concerns on 3rd embodiment. It is a schematic diagram for demonstrating the structure of the imaging device which concerns on 4th embodiment. It is a schematic diagram for demonstrating the structure of the imaging device which concerns on 5th embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

(First embodiment)
First, the configuration of the imaging apparatus 1 according to the first embodiment will be described with reference to FIGS. FIG. 1 is a diagram schematically illustrating a configuration of an imaging apparatus according to the first embodiment. FIG. 2 is a diagram for explaining the configuration of the liquid crystal lens. FIG. 3 is a diagram for explaining the relationship between the liquid crystal lens and the lens power. FIG. 4 is a diagram for explaining the configuration of the liquid crystal lens. FIG. 5 is a diagram for explaining the relationship between the liquid crystal lens and the focal position.

  As shown in FIG. 1, the imaging device 1 includes a first lens group 10, a second lens group 20, a third lens group 30, and an imaging element S.

  The first lens group 10, the second lens group 20, and the third lens group 30 are each positioned with respect to the image sensor S. The first lens group 10, the second lens group 20, and the third lens group 30 are positioned with respect to each other, and the optical paths L 1 and L 2 are those of the first lens group 10, the second lens group 20, and the third lens group 30. It is arranged to pass in order. An optical path L1 and an optical path L2 represent optical paths of light incident on the imaging device 1. The optical path L1 and the optical path L2 have different incident angles incident on the first lens group 10.

  As shown in FIG. 1, the first group principal point M1, the second group principal point M2, and the third group principal point M3 are located on the same optical axis L. The first group principal point M1 is a principal point on the imaging element S side of the first lens group 10. The second group principal point M2 is a principal point of the second lens group 20 on the image sensor S side. The third group principal point M3 is a principal point of the third lens group 30 on the image sensor S side. The distance between the first group principal point M1 and the second group principal point M2 is longer than the distance between the second group principal point M2 and the third group principal point M3.

  The first lens group 10 includes at least one first liquid crystal lens 11. Here, the first liquid crystal lens 11 will be described. The first liquid crystal lens 11 is a liquid crystal lens whose refractive index is adjustable.

  First, the liquid crystal lens 11 used as the first liquid crystal lens 11 will be described with reference to FIG. As shown in FIG. 2, in the liquid crystal lens 11, the liquid crystal layer LC is sandwiched between a pair of transparent substrates CG. In the liquid crystal lens 11, the common electrode EL1 is disposed on one surface of the liquid crystal layer LC, and the external electrode EL2 and the internal electrode EL3 are disposed on the other surface.

  Here, the refractive index of the liquid crystal lens 11 will be described with reference to FIG. FIG. 3 shows a difference in applied voltage that is a voltage applied to the liquid crystal lens 11. FIG. 3A schematically shows the liquid crystal lens 11 when there is no voltage applied by the external electrode EL2 and the internal electrode EL3. FIG. 3B schematically shows the liquid crystal lens 11 when the voltage applied by the external electrode EL2 is higher than the voltage applied by the internal electrode EL3. FIG. 3C schematically shows the liquid crystal lens 11 when the applied voltage by the external electrode EL2 is lower than the applied voltage by the internal electrode EL3.

  As shown in FIG. 3A, the light incident on the liquid crystal lens 11 when no voltage is applied to the external electrode EL2 and the internal electrode EL3 is not affected by refraction by the liquid crystal lens 11. . For this reason, the incident light is transmitted without being refracted.

  As shown in FIG. 3B, when the applied voltage by the external electrode EL2 is higher than the applied voltage by the internal electrode EL3, the refractive index of the liquid crystal lens 11 decreases as the distance from the center of the liquid crystal lens 11 increases. Thus, the liquid crystal molecules LM in the liquid crystal layer LC are controlled. For this reason, the light incident on the liquid crystal lens 11 is refracted toward the central direction of the liquid crystal lens 11. Therefore, the control unit can control the liquid crystal lens 11 so that the polarity of the lens power becomes positive by controlling the applied voltage in this way.

  As shown in FIG. 3C, when the applied voltage by the external electrode EL2 is lower than the applied voltage by the internal electrode EL3, the refractive index of the liquid crystal lens 11 increases as the distance from the center of the liquid crystal lens 11 increases. Thus, the liquid crystal molecules LM in the liquid crystal layer LC are controlled. For this reason, the light incident on the liquid crystal lens 11 is refracted so as to spread from the center direction of the liquid crystal lens 11. Therefore, the control unit can control the liquid crystal lens 11 so that the polarity of the lens power becomes negative by controlling the applied voltage in this way.

  Next, the liquid crystal lens 31 used as the third liquid crystal lens 31 will be described with reference to FIG. The liquid crystal lens 31 has the same configuration as the liquid crystal lens 11 described above, and further includes a control unit 32 that adjusts the refractive index of the liquid crystal lens 31. The control unit 32 can adjust the liquid crystal lens 31 to a desired lens power by controlling the voltage applied to the liquid crystal lens 31. The control unit 32 performs control to apply an applied voltage to the four corners 31a, 31b, 31c, and 31d of the liquid crystal lens 31.

  Furthermore, as shown in FIG. 5, the control unit 32 applies an applied voltage to locally change the orientation of the liquid crystal molecules LM of the liquid crystal lens 31. For this reason, the focal position (imaging position) of the liquid crystal lens 31 can be controlled on a plane passing through the image sensor S (x direction or y direction). Further, by locally changing the external electrode EL2 and the internal electrode EL3 of the liquid crystal lens 31, the focal position of the liquid crystal lens 31 can be controlled in a direction approaching the liquid crystal lens 31 (vertical direction, z direction). it can. As described above, as the liquid crystal lens 31 capable of controlling the focal position, for example, a liquid crystal lens of a type described in JP-A-2006-91826 can be used.

  As described above, the first lens group 10 includes the first liquid crystal lens 11. By controlling the polarity of the lens power of the first liquid crystal lens 11 by the control unit of the first liquid crystal lens 11, the polarity of the lens power of the first lens group 10 can be controlled.

  The second lens group 20 includes at least one second liquid crystal lens 21. The second liquid crystal lens 21 is a liquid crystal lens whose refractive index is adjustable. The second liquid crystal lens 21 is the liquid crystal lens 11. By controlling the polarity of the lens power of the second liquid crystal lens 21 by the control unit of the second liquid crystal lens 21, the polarity of the lens power of the second lens group 20 can be controlled.

  The third lens group 30 includes at least one fixed lens. The third lens group 30 may include, for example, a plurality of fixed lenses.

  The image sensor S is an element that converts light incident through the lens into an electrical signal. The image sensor S is an image sensor such as a CCD or CMOS. The image sensor S may be electrically connected to the wiring and output an image signal.

  Here, with reference to FIG. 6, the zoom function by the liquid crystal lens in this embodiment is demonstrated. FIG. 6 is a diagram for explaining a lens system 100 that realizes a zoom function in the prior art and a lens system that realizes a zoom function in the present embodiment. FIGS. 6A and 6B schematically show a configuration of a lens system 100 that realizes a zoom function in the prior art. FIGS. 6C and 6D schematically show the configuration of a lens system that realizes a zoom function in this embodiment.

  6A shows the arrangement of lenses for functioning as a wide-angle lens in the lens system 100. FIG. FIG. 6B is an arrangement of lenses for functioning as a tele lens in the lens system 100.

  As shown in FIGS. 6A and 6B, the lens system 100 includes a plurality of concave lenses and convex lenses. In order to make the lens system 100 functioning as a wide-angle lens into the lens system 100 functioning as a telephoto lens, the lens system 100 is moved so that the focal position of the entire lens system 100 is kept constant. Was necessary.

  FIG. 6C shows a lens arrangement for functioning as a wide-angle lens in the present embodiment. FIG. 6D shows an arrangement of lenses for functioning as a tele lens in this embodiment.

  The liquid crystal lens 11 has the lens power polarity of the first liquid crystal lens 11 and the second liquid crystal lens so that the lens power polarity of the first lens group 10 and the lens power polarity of the second lens group 20 are reversed. The polarity of the lens power of 21 can be controlled.

  As shown in (C) of FIG. 6, when the control unit performs control so that the lens power polarity of the first lens group 10 is negative and the lens power polarity of the second lens group 20 is positive, The optical paths L1 and L2 that have entered through the optical path having a wider viewing angle can be imaged on the image sensor S. Therefore, the first lens group 10, the second lens group 20, and the third lens group 30 function as a wide-angle lens with respect to the light passing through the first lens group 10, the second lens group 20, and the third lens group 30. To do.

  As shown in (D) of FIG. 6, when the control unit performs control so that the lens power polarity of the first lens group 10 is positive and the lens power polarity of the second lens group 20 is negative, The optical paths L1 and L2 that have entered from a farther subject can be imaged on the image sensor S. Therefore, the first lens group 10, the second lens group 20, and the third lens group 30 function as a telephoto lens with respect to light passing through the first lens group 10, the second lens group 20, and the third lens group 30. To do.

  As described above, in the imaging apparatus 1, the first lens group 10, the second lens group 20, and the third lens group 30 are positioned with respect to the imaging element S. The second lens group 20 and the third lens group 30 do not move with respect to the image sensor S. An image is formed on the image sensor S without moving the first lens group 10, the second lens group 20, and the third lens group 30. Since the distance between the first group principal point M1 and the second group principal point M2 is longer than the distance between the second group principal point M2 and the third group principal point M3, the lens group is used to change the zoom magnification. The zoom function can be realized without mechanically moving the lens in the optical axis direction.

  Further, the control unit 110 can control the lens power polarity of the first lens group 10 and the lens power polarity of the second lens group 20. For example, when control is performed so that the lens power polarity of the first lens group is negative and the lens power polarity of the second lens group is positive, the first lens group 10, the second lens group 20, and the third lens group are controlled. The lens group 30 functions as a wide-angle lens for light passing through the first lens group 10, the second lens group 20, and the third lens group 30. On the other hand, when the control is performed such that the lens power polarity of the first lens group is positive and the lens power polarity of the second lens group is negative, the first lens group 10, the second lens group 20, and the third lens group are controlled. The lens group 30 functions as a telephoto lens for light passing through the first lens group 10, the second lens group 20, and the third lens group 30. It is possible to continuously change the focal length while keeping the focal position of the entire lens system constant.

  As mentioned above, according to 1st embodiment, the imaging device 1 which implement | achieves a zoom function of a high magnification can be provided. Furthermore, the functions of the wide-angle lens and the telephoto lens can be realized with stepless magnification.

(Second embodiment)
With reference to FIG. 7, an imaging apparatus according to the second embodiment will be described. The imaging device 1 according to the second embodiment is the same as the imaging device 1 according to the first embodiment except for the first lens group 10 and the second lens group 20. Hereinafter, overlapping description with the first embodiment will be omitted, and differences will be mainly described.

  FIG. 7 is a diagram schematically illustrating the configuration of the imaging apparatus 1 according to the second embodiment.

  As shown in FIG. 7, the first lens group 10 includes a lens 12 in addition to the first liquid crystal lens 11. The lens power polarity of the entire lens 12 is negative. The second lens group 20 includes a lens 22 in addition to the second liquid crystal lens 21. The lens power polarity of the entire lens 22 is positive.

  In the second embodiment, the angle of view of light that enters the first lens group 10 and contributes to image formation can be allowed to be larger than that in the first embodiment. For this reason, it is not necessary to increase the sizes of the first liquid crystal lens 11 and the second liquid crystal lens 21 in order to achieve a zoom function with a higher magnification. Therefore, the imaging device 1 can be reduced in size.

  As described above, according to the second embodiment, it is possible to obtain the imaging device 1 that can further reduce the size of a lens that realizes a high-magnification zoom function.

(Third embodiment)
With reference to FIG. 8, the imaging apparatus according to the third embodiment will be described. The imaging device 1 according to the third embodiment is the same as the imaging device 1 according to the second embodiment except for the third lens group 30. Hereinafter, overlapping description with the second embodiment will be omitted, and the description will focus on the differences.

  FIG. 8 is a diagram schematically illustrating a configuration of the imaging apparatus 1 according to the third embodiment.

  As shown in FIG. 8, the third lens group 30 includes at least one third liquid crystal lens 31. The third liquid crystal lens 31 is a liquid crystal lens whose refractive index can be adjusted. The third liquid crystal lens 31 is the liquid crystal lens 31. The third liquid crystal lens 31 controls the lens power of the third lens group 30 by controlling the lens power of the third liquid crystal lens 31 and its polarity by the control unit 32. The control unit 110 controls the applied voltage applied to the third liquid crystal lens 31 so that the imaging position with respect to the image sensor S moves.

  In the third embodiment, since the focal length of the third lens group 30 is controlled, the third lens group is capable of dealing with minute fluctuations in the imaging position of the emitted light of the third lens group caused by the difference in perspective of the subject. The image forming position can be controlled in a direction perpendicular to the imaging surface of the imaging device by the action of the lens power of the third liquid crystal lens included in the imaging device. Therefore, a function for controlling the imaging position, that is, a focus adjustment function can be realized. Camera shake correction can be performed by moving the imaging position within the imaging surface of the imaging device S.

  As described above, according to the third embodiment, it is possible to obtain the imaging device 1 having a focus adjustment function and a camera shake correction function while realizing a high-magnification zoom function.

(Fourth embodiment)
An imaging apparatus according to the fourth embodiment will be described with reference to FIG. The imaging device 1 according to the fourth embodiment is the same as the imaging device 1 according to the second embodiment except that the first reflection member 41 is provided. Hereinafter, overlapping description with the second embodiment will be omitted, and the description will focus on the differences.

  FIG. 9 is a diagram schematically illustrating the configuration of the imaging apparatus 1 according to the fourth embodiment.

  As shown in FIG. 9, a first reflecting member 41 that reflects an optical path of light is provided between the first lens group 10 and the second lens group 20.

  In the fourth embodiment, the optical paths L 1, L 2 and L 3 of the light incident on the first lens group 10 are bent by the first reflecting member 41. For this reason, the size of the imaging device 1 can be reduced when viewed along the optical axis of the light incident on the first lens group 10.

  As described above, according to the fourth embodiment, it is possible to reduce the height of the imaging device 1 while realizing a high-magnification zoom function.

(Fifth embodiment)
With reference to FIG. 10, an imaging apparatus according to the fifth embodiment will be described. The imaging device 1 according to the fifth embodiment is the same as the imaging device 1 according to the second embodiment, except that the first reflection member 41 and the second reflection member 42 are provided. Hereinafter, overlapping description with the second embodiment will be omitted, and the description will focus on the differences.

  FIG. 10 is a diagram schematically illustrating a configuration of the imaging apparatus 1 according to the fifth embodiment.

  As shown in FIG. 10, a first reflecting member 41 and a second reflecting member 42 that reflect an optical path of light are disposed between the first lens group 10 and the second lens group 20.

  In the fifth embodiment, the optical paths L 1, L 2 and L 3 of the light incident on the first lens group 10 are bent by the first reflecting member 41. The second reflecting member 42 reflects the optical path of light incident on the second reflecting member 42 toward the side where the first lens group 10 is disposed.

  The first reflecting member 41 and the second reflecting member 42 may be arranged such that the incident angle of light incident on the first reflecting member 41 is different from the reflection angle of light reflected by the second reflecting member 42. Good. In this case, the first reflecting member 41 and the second reflecting member 42 are arranged at different angles with respect to a plane perpendicular to the optical axis of the light incident on the first lens group 10.

  For this reason, the size of the imaging device 1 can be reduced when viewed along the optical axis of the light incident on the first lens group 10.

  As described above, according to the fifth embodiment, it is possible to reduce the size and height of the imaging device 1 while realizing a zoom function with high magnification.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to such embodiment at all, In the range which does not deviate from the summary of this invention, it can implement with a various aspect.

  For example, in the fourth embodiment and the fifth embodiment described above, the third lens group 30 may include the third liquid crystal lens 31. In this case, it is possible to reduce the height of the imaging device 1 while providing the focus adjustment (focusing) function or the hand shake correction function.

  In the embodiment described above, the control means for controlling the lens power polarity of the first liquid crystal lens 11, the control means for controlling the lens power polarity of the second liquid crystal lens 21, and the lens power polarity of the third liquid crystal lens 31. Control means for controlling may be provided in each of the first liquid crystal lens 11, the second liquid crystal lens 21, and the third liquid crystal lens 31. Even in this case, the above-described actions and effects can be achieved.

  DESCRIPTION OF SYMBOLS 1 ... Imaging device, 10 ... 1st lens group, 11 ... 1st liquid crystal lens, 20 ... 2nd lens group, 21 ... 2nd liquid crystal lens, 30 ... 3rd lens group, 31 ... 3rd liquid crystal lens, 41 ... 1st One reflecting member, 42 ... second reflecting member, M1 ... first group principal point, M2 ... second group principal point, M3 ... third group principal point, S ... imaging element.

Claims (9)

A first lens group including at least one first liquid crystal lens;
A second lens group including at least one second liquid crystal lens;
A third lens group including at least one fixed lens;
An image sensor that receives light that has passed through the third lens group, and converts the received light into an electrical signal;
With
The first lens group, the second lens group, and the third lens group are positioned with respect to each other, and light passes through the first lens group, the second lens group, and the third lens group in this order. Placed in
A first group principal point that is a principal point on the image sensor side of the first lens group, a second group principal point that is a principal point on the image sensor side of the second lens group, and the third lens group The third group principal point that is the principal point on the image sensor side is located on the same optical axis, and the distance between the first group principal point and the second group principal point is the second group principal point and the second group principal point. An imaging apparatus characterized by being longer than the distance from the third group principal point.   The first lens group, the second lens group, and the third lens group are respectively positioned with respect to the imaging element, and the polarity of the lens power of the first lens group and the second lens group The imaging apparatus according to claim 1, further comprising a control unit that controls the lens power polarity of the first liquid crystal lens and the lens power polarity of the second liquid crystal lens so that the lens power polarity is reversed.   The control means has a negative lens power polarity of the first lens group, a positive lens power polarity of the second lens group, and a positive lens power polarity of the first lens group. And the polarity of the lens power of the first liquid crystal lens and the polarity of the lens power of the second liquid crystal lens are controlled such that the lens power polarity of the second lens group is negative. The imaging apparatus according to claim 1 or 2, wherein The lens included in the first lens group other than the first liquid crystal lens has a negative polarity of the lens power of the entire lens other than the first liquid crystal lens,
The lens included in the second lens group other than the second liquid crystal lens has positive polarity of the lens power of the entire lens other than the second liquid crystal lens. The imaging device according to item. The third lens group includes at least one third liquid crystal lens;
The imaging apparatus according to claim 1, further comprising a control unit that controls a polarity of lens power of the third liquid crystal lens.   The imaging apparatus according to claim 1, further comprising a control unit that controls an orientation of liquid crystal molecules of the third liquid crystal lens so that an imaging position with respect to the imaging element is moved. .   It further comprises a first reflecting member that is disposed on the optical path between the first lens group and the second lens group and reflects the light from the first lens group to the second lens group. The imaging device according to any one of claims 1 to 6.   A first reflecting member disposed on an optical path between the first lens group and the second lens group so that a traveling direction of light is reversed between the first lens group and the second lens group. The imaging apparatus according to claim 1, further comprising a second reflection member.   The first reflecting member and the second reflecting member are disposed such that an incident angle of light incident on the first reflecting member is different from a reflection angle of light reflected by the second reflecting member. The imaging device according to claim 8.

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