KR100730852B1 - Imaging device - Google Patents

Abstract

An object of the present invention is to provide an imaging device that can be thinned without degrading optical performance.

The imaging device 100 according to the present invention comprises an imaging device 50 and a plurality of lenses including non-circular lenses 1, 3, and 7. Here, the imaging device 50 has a rectangular light receiving surface 50a. In addition, the imaging element 50 is an element which converts the optical image formed on the light receiving surface 50a into an electrical signal. In addition, the plurality of lenses form an image of the subject on the light receiving surface 50a. In addition, the non-circular lenses 1, 3, 7 have a shape in which the portion which does not contribute to the image formation from the circular lens to the light receiving surface 50a is removed.

Description

Imaging Device {IMAGING DEVICE}

1 is a cross-sectional view showing a configuration when the imaging device 100 according to the embodiment is viewed from above;

2 is a cross-sectional view showing a configuration when the imaging device 100 according to the embodiment is viewed from the front,

3 is a plan view showing a configuration of an imaging device and a rectangular light receiving surface;

4 is a view for explaining a state of change of the luminous flux in the imaging device according to the embodiment;

5 is a plan view showing a region of an image forming position on a light receiving surface;

6 is a view for explaining a portion that does not contribute to an image formation on a light receiving surface in a circular lens;

7 is a view for explaining a portion that does not contribute to an image formation on a light receiving surface in a circular lens;

8 is a plan view showing a difference in shape between a circular lens and a non-circular lens;

9 is a cross-sectional view showing the shape of one end surface of a non-circular lens,

10 is a cross-sectional view showing another cross-sectional shape of a non-circular lens,

11 is a plan view of a non-circular lens obtained by D-cutting a circular lens in four directions;

12 is a view showing an imageable area when a circular lens is used;

FIG. 13 is a view showing an image-capable area when a D-cut non-circular lens is used;

14 is a view for explaining thinning in a predetermined direction of an imaging device;

15 is a view for explaining thinning in a predetermined direction of an imaging device;

16 is a view for explaining miniaturization of a first lens;

17 is a view for explaining miniaturization of a first lens;

18 is a view for explaining miniaturization of a first lens group;

19 is a diagram for explaining the miniaturization of the first lens group.

Explanation of symbols for the main parts of the drawings

1: first lens 2: prism lens

3: second lens 4: third lens

5: fourth lens 6: aperture aperture

7: fifth lens 10: first lens group

15: first lens holding frame 16: first lens group holding frame

17: second lens group holding frame 18: third lens group holding frame

19: imaging device package 20: second lens group

25: outer housing 30: third lens group

35: guide shaft 36: 1-axis drive device

40: infrared cut filter 50: imaging device

50a: light receiving surface 60, 70: optical axis

100: imaging device 150: circular lens

Industrial Applicability The present invention relates to an imaging device comprising an imaging element and a plurality of lenses, and can be applied to, for example, an imaging device that can be mounted in a thin portable terminal.

Imaging devices such as CCD (Charge Coupled Device) and an imaging device composed of a plurality of lenses exist conventionally. In recent years, the imaging device has been mounted in portable terminals such as mobile phones.

Conventionally, the imaging device has been applied to a digital still camera, but an imaging device having a function of bending an optical axis in the vertical direction has been mounted in the digital still camera because of a thin request. Patent documents 1, 2, and 3 exist as an imaging device which has the said bending function.

By the way, when the mounting of the imaging device in a mobile telephone is considered, for example, it is preferable that the imaging device is as follows.

That is, it is preferable that the imaging device has a wider angle of view at a zoom wide end (wide angle end) for purposes of use. In addition, the structure of the optical system is preferably an image side telecentric (meaning that the incident angle of light rays to the imaging plane is substantially constant) in order to suppress a decrease in the marginal lumination. .

Patent document 1, patent document 2, and patent document 3 all employ the retro focus structure, and implement | achieve the wide angle of view in the zoom wide end, and the upper telecentric in the whole zoom area. In addition, in the first lens group and the fourth lens group, the enlargement of each lens is suppressed by tightening the luminous flux.

[Patent Document 1] Japanese Unexamined Patent Publication No. 2004-37927

[Patent Document 2] Japanese Unexamined Patent Publication No. 2004-56362

[Patent Document 3] Japanese Unexamined Patent Publication No. 2003-222946

By the way, in the imaging devices according to Patent Documents 1 to 3, the thickness (the thickness in the direction perpendicular to the normal direction of the imaging device) of the imaging device is a lens (especially a lens arranged on the normal axis of the imaging device, and has an aperture function. And lenses other than the lens group having the same). Therefore, the smaller the size of the lens is, the thinner the imaging device can be.

However, when the image telecentric is realized, the diameter of the circular lens most disposed on the imaging element side needs to be at least larger than the diagonal of the imaging element, and there is a limit to the thinning of the imaging device.

In addition, by setting the retro focus, the diameter of the circular lens belonging to the lens group most disposed on the subject side becomes large when the wide angle of view is used. The expansion of the circular lens diameter has been a factor that hinders the thinning of the imaging device.

In other words, a lens group having an optical axis bending function is usually composed of a prism lens and lenses disposed before and after the prism lens.

Since the lens group having the optical axis bending function is configured as described above, miniaturization of the lens group has been limited in order to prevent interference (physical contact) between the lenses. Such limitation of miniaturization of the lens group having the optical axis bending function has become a factor that hinders the thinning of the imaging device.

In addition, the thinner the imaging device, the thinner the thickness of the digital still camera on which the imaging device is mounted.

Then, an object of this invention is to provide the imaging device which can be thinned, without reducing optical performance.

In order to achieve the above object, the imaging device according to claim 1 according to the present invention has an image receiving element which has a rectangular light receiving surface and converts an optical image formed on the light receiving surface into an electrical signal, and an image of a subject. ) Is provided with a plurality of lenses for forming an image on the light receiving surface, wherein at least one of the plurality of lenses has a shape in which at least one predetermined peripheral portion is removed from a portion that does not contribute to the image formation from the circular lens to the light receiving surface. It is comprised by the non-circular lens which has.

Each lens disposed in the imaging device had a conventional circular shape. However, the inventors have focused on the fact that the circular lens has a portion that does not contribute to the imaging of the image pickup element on the light receiving surface.

When the imaging device employs a non-circular lens having a shape in which at least one predetermined peripheral portion is removed among the portions that do not contribute to the imaging from the circular lens to the light receiving surface, the inventor can make the imaging device thinner. In thought, the invention shown below was created.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated concretely based on drawing which shows the Example.

(Example 1)

1 is a cross-sectional view of the imaging device 100 according to the present embodiment when viewed from above. 2 is sectional drawing which looked at the imaging device 100 which concerns on a present Example from the front direction (subject direction). 1 and 2 also show the x, y and z directions.

As shown in FIG. 1, the imaging device 100 includes a first lens group 10, a second lens group 20, a third lens group 30, an infrared cut filter 40, and an imaging device 50. It consists of).

As described below, the imaging device 100 according to the present embodiment arranges a lens group having negative power on the subject side, and arranges a lens having positive power on the imaging element 50 side. It has a focus structure.

The imaging element 50 has a light receiving surface. The imaging device 50 is an element capable of converting an optical image formed on the light receiving surface into an electrical signal. In addition, the light receiving surface has a rectangular shape in which the ratio of the long side to the short side is generally 4: 3 because of the limitation of the motor that illuminates the image. In addition, the top view of the imaging element 50 is shown in FIG. As shown in FIG. 3, the imaging element 50 has the rectangular light-receiving surface 50a.

The plurality of lenses (the first lens group 10, the second lens group 20, and the third lens group 30) are members that form an image of a subject on the light receiving surface 50a of the imaging device 50.

The first lens group 10 has a function of folding the optical axis back in the vertical direction (FIG. 1, from the optical axis 60 to the optical axis 70). In addition, the first lens group 10 has negative power as a whole. The first lens group 10 is constituted by the first lens 1, the prism lens 2, and the second lens 3.

Here, the first lens 1 has negative power. In addition, the prism lens 2 has a reflecting surface which bends an optical path and has a lens surface. In addition, the second lens 3 has negative power. The first lens 1 is held and fixed by the first lens holding frame 15. In addition, the entire first lens group 10 is held and fixed by the first lens group holding frame 16.

In addition, the second lens group 20 has a positive power as a whole. The second lens group 20 is constituted by the third lens 4 and the fourth lens 5. Here, the third lens 4 has a positive power. In addition, the fourth lens 5 has negative power.

On the subject side of the third lens 4, an aperture stop 6 for limiting incident light is disposed. The aperture stop 6 and the second lens group 20 are held and fixed by the second lens group holding frame 17.

In addition, the third lens group 30 has a positive power as a whole and is constituted by the fifth lens 7. Here, the third lens group 30 is held and fixed by the third lens group holding frame 18.

In addition, an infrared light cut filter 40 is disposed between the third lens group 30 and the imaging device 50. Here, the infrared cut filter 40 has a function of blocking infrared light contained in incident light. In addition, the infrared cut filter 40 and the imaging device 50 are mounted and fixed in the imaging device package 19.

In addition, the center of each said lens 1-5, 7 and the center of the imaging element 50 correspond to the optical axis 60 and the optical axis 70 which are optical center axes of the imaging device 100. As shown in FIG. In addition, the first lens holding frame 15, the first lens group holding frame 16, and the imaging device package 19 are respectively fixed by the outer housing 25.

In addition, as shown in FIG. 2, two guide shafts 35 are disposed in the imaging device 100. Here, the guide shafts 35 are arranged with a predetermined distance therebetween, and are parallel to each other. The guide shaft 35 is arranged to be substantially parallel to the direction of the optical axis 70.

The second lens group holding frame 17 and the third lens group holding frame 18 are each formed with a cylindrical guide portion or a U-shaped groove having a predetermined length. In addition, the hollow portion or the groove of the cylindrical guide portion is associated with the guide shaft 35. That is, the hollow portion or the groove may move on the guide shaft 35.

By this structure, the 2nd lens group 20 and the 3rd lens group 30 can move to the optical axis 70 direction, and movement of the other direction is regulated. In addition, the single-axis drive device 36 is fixed to the outer housing 25, and the second lens group 20 and the third lens group 30 are formed on the optical axis by the driving force of the single-axis drive device 36. Operate in the direction of 70.

4 is a view showing an optical lens system of the imaging device 100 and the state of change in luminous flux width at the zoom wide end.

As shown in FIG. 4, first, the light beam incident on the first lens group 10 from the subject side is enlarged by the first lens group 10. In addition, although not shown in FIG. 4, the light beam is bent by 90 degrees by the prism lens 2 including the reflection surface.

Thereafter, the width of the light beam is limited in the aperture stop 6 (not shown in FIG. 4). The light beam of which the width is limited is formed on the light receiving surface 50a by the second lens group 20 and the third lens group 30. In addition, although not shown in FIG. 4, the light beam has passed through the infrared light cut filter 40 before it is image-formed on the light receiving surface 50a.

Here, the shift and focus adjustment are performed by changing the positions of the second lens group 20 and the third lens group 30.

In the imaging device 50, microlenses exist for each pixel sensor constituting the light receiving surface 50a. Therefore, the smaller the incidence angle (angle τ in FIG. 6) of the light emitted from the third lens group 30 to the light receiving surface 50a is preferable. This is because when the incident angle to the light receiving surface is large, Kerare occurs in each pixel sensor, and the amount of ambient light decreases.

From the above, in the imaging device 100 according to the present embodiment, the optical system is configured such that the angle of incidence on the light receiving surface becomes small telecentric.

By the way, in the imaging device 100 which concerns on a present Example, each lens (for example, 2nd lens 3, a 1st lens) arrange | positioned on the normal axis of the imaging element 50 (namely, on the optical axis 70), One of the five lenses 7 and the like, and each of the lenses (e.g., the first lens 1) disposed to face the subject (i.e., disposed on the optical axis 60) is a non-circular lens.

In the present embodiment, the first lens 1, the second lens 3, and the fifth lens 7 are non-circular lenses, and the story is advanced. Further, all of the lenses 1, 3, and 7 may not be non-circular lenses. Although not employed in this embodiment, the third lens 4 or the fourth lens 5 may be a non-circular lens.

Here, a non-circular lens is a lens which has the shape which removed at least 1 predetermined peripheral part among the parts which do not contribute to the imaging from the circular lens to the said light receiving surface.

Hereinafter, the part which does not contribute to the imaging to the light receiving surface in a circular lens is demonstrated.

First, as shown in FIG. 5, the case where an optical beam is image-formed in the diagonal end area | region P (region located in the distance from an optical axis position) of the rectangular light-receiving surface 50a is demonstrated.

FIG. 6 is a view showing an optical lens system for forming a light beam in an area P of the light receiving surface 50a at the zoom wide end, and a state of change in the light beam width.

Here, although the optical lens system shown in FIG. 6 has a structure substantially the same as the optical lens system shown in FIG. 4, both optical lens systems differ in the following points. That is, although the optical lens system shown in FIG. 4 contains a non-circular lens, in the optical lens system shown in FIG. 6, all the lenses are circular lenses. Therefore, the optical lens system shown in Fig. 6 also has a retro focus configuration and adopts an image-side telecentric method.

As shown in FIG. 6, the light beam is incident on the first lens group 10 at the chief ray incident angle θd. The light beam is enlarged by the first lens group 10 having negative power. The light beam width is limited by the aperture stop (not shown). Thereafter, the light flux is imaged on the area P of the light receiving surface 50a by the second lens group 20 and the third lens group 30.

As shown in FIG. 6, when the luminous flux forms an image on the area P of the light receiving surface 50a, each circular lens is disposed so that the luminous flux passes near the outer peripheral ends of the first lens group 10 and the third lens group 30. The size of is designed.

By the way, as shown in FIG. 5, the case where the light beam forms an image in the long side center region Q of the rectangular light-receiving surface 50a is demonstrated.

FIG. 7 is a view showing an optical lens system for forming a light beam in an area Q of the light receiving surface 50a at the zoom wide end, and a state of change in the light beam width. Here, the optical lens system shown in FIG. 6 and the optical lens system shown in FIG. 7 have the same configuration. 6 shows the cross-sectional structure of the position away from the center of the lens, while FIG. 7 shows the cross-sectional structure near the center of the lens. Therefore, both FIG. 6, 7 has shown the different cross section.

The light beam enters the first lens group 10 at the main ray incident angle θh (incident angle θh becomes smaller than the incident angle θd). The light beam is enlarged by the first lens group 10 having negative power. The light beam width is limited by the aperture stop (not shown). Thereafter, the light flux is imaged on the area Q of the light receiving surface 50a by the second lens group 20 and the third lens group 30.

As shown in FIG. 7, when the luminous flux forms an image in the area Q of the light receiving surface 50a, the first lens group 10 is positioned inwardly by a distance 43 from the outer peripheral end of the first lens group 10. The light beam passes through the area to be made. In addition, the light beam passes through the third lens group 30 located inward from the outer peripheral end of the third lens group 30 by a distance 44.

In this manner, in the same optical lens system, when the imaging region on the light receiving surface 50a is different, the optical paths in the first lens group 10 and the third lens group 30 are different. It goes without saying that the values of the distances 43 and 44 become larger as they approach the long side center region Q from the diagonal end region P.

As can be seen from the comparison of Figs. 6 and 7, the first lens group 10 composed of the circular lens and the third lens group 30 of the circular shape are directed to the rectangular light receiving surface 50a. The part which does not contribute to image formation (part corresponding to 43 and 44 of FIG. 7) arises.

In each circular lens constituting the first lens group 10 shown in Figs. 6 and 7, a non-circular lens in which the portion which does not contribute to the image formation on the light-receiving surface 50a is removed according to the present embodiment. It is the 1st lens 1 and the 2nd lens 3.

Similarly, in the circular lens constituting the third lens group 30 shown in Figs. 6 and 7, a non-circular lens in which the portion which does not contribute to the image forming on the light receiving surface 50a is removed. According to the fifth lens 7.

In this way, the non-circular lens from which a part of the circular lens is removed is more compact than the circular lens.

The means (ie, non-circular shape) of the removal of the part which does not contribute to the imaging from the circular lens to the light receiving surface 50a can be arbitrarily selected. An example of a non-circular lens is shown below.

8 is a plan view showing one form of the fifth lens 7 of non-circular shape. 9 is a sectional view A-A of the non-circular lens shown in FIG. 10 is B-B sectional drawing of the non-circular lens shown in FIG.

The non-circular fifth lens 7 shown in FIG. 8 has a D-cut shape cut along a straight line in a portion not contributing to the imaging from the dotted circular lens 150 to the light receiving surface 50a. Here, although the 5th lens 7 shown in FIG. 7 is cut D two places in the parts a and b, only one place may be D cut.

In addition, even in the left and right ends of the non-circular fifth lens 7 shown in FIG. 7, a portion which does not contribute to the image formation on the light receiving surface 50a exists although there are few regions. Therefore, the fifth lens 7 of non-circular shape may be sufficient as the shape shown in FIG. 11 (that is, D cut also in the left and right ends of the dotted circular lens 150).

Here, when the non-circular lens having the D-cut shape shown in Fig. 8 is disposed on the normal axis of the imaging element 50 (that is, on the optical axis 70), the D-cut of the non-circular lens seen in plan view is It is preferable that the linear part of a part and the long side of the light receiving surface 50a are substantially parallel.

In addition, when the non-circular lens is disposed to face the subject (i.e., disposed on the optical axis 60), the straight portion of the cut portion of the non-circular lens seen from the plane and the long side of the light receiving surface 50a. Is preferably substantially parallel.

Here, the size of the diameter of the circular lens 150 on which it is based is preferably about the same length as the diagonal of the imaging surface 50a.

That is, when the image-side telecentric method having a small incident angle (angle τ shown in FIG. 6) of the light beam to the light receiving surface 50a is adopted, the main light ray of the light beam is between the third lens group 30 and the light receiving surface 50a. It is almost parallel to the optical axis at. Therefore, the size of the lens diameter needs to be substantially the same as the diagonal of the light receiving surface 50a at the minimum. In addition, in consideration of the compactness of the lens, it is not preferable that the size of the lens diameter exceeds the diagonal length of the light receiving surface 50a more than necessary.

In view of the above, in the imaging device 100 according to the present embodiment of the image-side telecentric method, in order to prevent unnecessary enlargement of the lens diameter, the diameter of the circular lens 150 as the base of the non-circular lens is the light receiving surface 50a. It is preferable to make the value almost equal to the diagonal of the square.

In addition, when the imaging device is configured with a circular lens, the outline of the image-capable image area A1 of the light beam with respect to the light receiving surface 50a is as shown in FIG. 12. In contrast, when the imaging device 100 including the non-circular lens is configured, the outline of the image-capable image area A2 of the light flux with respect to the light receiving surface 50a is as shown in FIG. 13.

As can be seen from Fig. 13, even if a non-circular lens is adopted, for example, an unnecessary image formation area is reduced, and the image formation on the light receiving surface 50a is not affected. That is, by employing the non-circular lens, the surface area of the lens can be reduced without affecting the imaging on the light receiving surface 50a.

As described above, the imaging device 100 according to the present embodiment employs a non-circular lens.

Therefore, the surface area of the lens can be made smaller than that of the circular lens without degrading the optical performance (that is, without affecting the imaging on the light receiving surface 50a). By reducing the surface area of the lens, it becomes possible to reduce or reduce the size of the imaging device 100 in which the size is rate-specific to the size of the predetermined lens.

In addition, the imaging apparatus 100 which concerns on a present Example employ | adopts a D-cut lens as a non-circular lens.

Therefore, the non-circular lens can be easily produced by removing the portion which does not contribute to the imaging from the circular lens to the light receiving surface 50a.

In addition, in the imaging device 100 according to the present embodiment, the non-circular lenses (for example, the second lens 3 and the fifth lens 7) are positioned on the normal axis of the imaging element 50 (that is, the optical axis). Above 70). Moreover, the linear part of the cut part of the said non-circular lens 5 and 7 seen from the plane, and the long side of the light receiving surface 50a are substantially parallel.

Therefore, the imaging apparatus 100 can be thinned in the y direction of FIG.

That is, as shown in FIG. 14, the long side L1 of the rectangular light-receiving surface 50a and the linear part L2 of the D-cut part of the non-circular lens 7 seen from the plane are not parallel. In this case, as is apparent from FIG. 14, the thickness of the imaging device 100 in the y direction cannot be reduced.

However, as shown in FIG. 15, the long side L1 of the rectangular light-receiving surface 50a and the linear part L3 of the D-cut part of the non-circular lens 7 seen from the plane are parallel. Then, as is apparent from the comparison of Figs. 14 and 15, the thickness of the y-direction of the imaging device 100 can be reduced.

In addition, as described above, the lenses 4 and 5 constituting the second lens group 20 may be non-circular lenses. However, since the lenses 4 and 5 are close to the aperture stop 6, the effect of thinning the imaging device 100 is not so great.

In contrast, the thickness of the imaging device 100 is controlled by the third lens 4 and the fifth lens 7. Therefore, the non-circular lens of the third lens 4 and the fifth lens 7 contributes to the thinning of the imaging device 100.

In addition, in the imaging device 100 according to the present embodiment, the non-circular lens (for example, the first lens 1) is disposed facing the subject (that is, disposed on the optical axis 60). Or the linear part of the D-cut part of the non-circular lens 1 seen from the plane, and the long side of the light receiving surface 50a are substantially parallel.

Therefore, the surface area of the first lens 1 can be made small without degrading the optical performance (that is, without affecting the imaging on the light receiving surface 50a as the angle of view can be maintained). .

That is, as shown in FIG. 16, it is assumed that the long side L1 of the rectangular light-receiving surface 50a and the straight part L5 of the D-cut part of the non-circular lens 1 seen from the plane are not parallel. In this case, even if the optical performance is not deteriorated, as apparent from FIG. 16, it is impossible to make the surface area of the first lens 1 so small.

However, as shown in FIG. 17, the long side L1 of the rectangular light-receiving surface 50a and the linear part L6 of the D-cut part of the non-circular lens 1 seen from the plane are parallel. If so, the surface area of the first lens 1 can be made sufficiently small, as is apparent from the comparison of Figs. 16 and 17, without degrading the optical performance.

And since the surface area of the 1st lens 1 became small, the whole size of the 1st lens group 10 can also be reduced.

That is, for example, when both the first lens 1 and the second lens 3 are circular lenses, the first lens group 10 has a cross-sectional structure shown in FIG. In the case of the structure shown in FIG. 18, miniaturization of the first lens group 10 is limited due to contact between both lenses in the proximal portion 57 between the first lens 1 and the second lens 3, and the like. there was.

However, when the first lens 1 and the second lens 3 are non-circular lenses, the first lens group 10 has a cross-sectional structure shown in FIG. That is, contact between both lenses is eliminated, and the first lens group 10 can be miniaturized.

Further, even if only the first lens 1 is a non-circular lens, the first lens group 10 can be miniaturized.

Incidentally, the non-circular lens may be disposed only on the optical axis 70 of the imaging element 50, or the non-circular lens may be disposed only on the optical axis 60. In the former case, the imaging device 100 can be thinned mainly. In contrast, in the latter case, the first lens group 10 can be miniaturized.

As can be seen from the above consideration, as in the above embodiment, the non-circular lens is disposed on the normal axis of the imaging device 50 (that is, on the optical axis 70), and the non-circular lens is placed on the subject. By arranging it (that is, placing it on the optical axis 60), it becomes possible to reduce the thickness of the imaging device 100 and to reduce the size of the first lens group 10.

As described above, when the first lens 1 or the second lens 3 is a non-circular lens, only the size of the prism lens 2 is changed without changing the size of the entire first lens group 10. It can also be downsized.

As described above, when the size of the prism lens 2 is reduced in size, the distance between the prism lens 2 and the first lens 1 or the distance between the prism lens 2 and the second lens 3 becomes wider. . Therefore, since the degree of freedom in designing the lens arrangement can be increased, it is possible to improve the optical performance of the imaging device 100.

In addition, in the imaging device 100 according to the present embodiment, the first lens group 10 has negative power. Therefore, the surface area of the 1st lens 1 which comprises the 1st lens group 10, and the surface area of the 2nd lens 3 can be made smaller.

That is, when the 1st lens group 10 has positive power, the light beam which contributes to the image incident on the 1st lens group 10 becomes thick. This is because it is impossible to change the size of the aperture stop 6 after designing it. In this way, when the luminous flux becomes thicker, the area of the first lens 1 and the second lens 3 that can be removed from the circular lens (that is, the portion that does not contribute to the imaging to the light receiving surface 50a) is reduced. Becomes smaller.

However, as mentioned above, when the 1st lens group 10 has negative power, the light beam which contributes to the image incident on the 1st lens group 10 becomes thin. Therefore, the area of the first lens 1 and the second lens 3 that can be removed from the circular lens (that is, the portion that does not contribute to the imaging to the light receiving surface 50a) is increased. That is, the surface area of the first lens 1 and the surface area of the second lens 3 can be made smaller.

In addition, in the imaging device 100 which concerns on a present Example, as shown in FIG. 8, the non-circular lens is cut D at two opposing locations. Therefore, the surface area of the lens can be made smaller than the non-circular lens having only one D cut.

In addition, the part which does not contribute to the imaging to the light-receiving surface 50a from the reflective surface of the prism lens 2 can also be deleted.

In the case where the non-circular lens is made of plastic, it is not preferable to extremely enlarge the portion to be removed from the circular lens for the following reasons.

That is, in the case where the non-circular lens is made of plastic, the more the shape is different from the circular shape, the more the nonuniformity of the resin flow method or the cooling method occurs.

However, if there are few parts to remove, deterioration of formation precision can be prevented. That is, the error between a design dimension and an actual dimension can be reduced.

An imaging device according to claim 1 of the present invention includes an imaging device having a rectangular light receiving surface and converting an optical image formed on the light receiving surface into an electrical signal, and a plurality of lenses for forming an image of a subject on the light receiving surface. Since at least one of the said plurality of lenses is comprised by the non-circular lens which has the shape which removed at least 1 predetermined peripheral part among the parts which do not contribute to the imaging from the circular lens to the said light receiving surface, The surface area of the lens can be made smaller. Thereby, the reduction and thickness of the imaging device can be aimed at.

Claims (6)

An imaging element having a rectangular light receiving surface and converting an optical image formed on the light receiving surface into an electrical signal; A plurality of lenses for forming an image of the subject on the light receiving surface Equipped with At least one of the plurality of lenses, The part which does not contribute to the imaging from a circular lens to the said light receiving surface is comprised by the non-circular lens which has the shape which removed at least 1 predetermined peripheral part. An imaging device, characterized in that. The method of claim 1, And the predetermined peripheral portion has a D-cut shape obtained by cutting a circular arc portion of a circular lens along a straight line. The method of claim 2, The non-circular lens, It is disposed on the normal axis of the imaging device, The straight portion of the D-cut portion of the non-circular lens seen from the plane and the long side of the light-receiving surface are parallel An imaging device, characterized in that. The method of claim 2, In the plurality of lenses, Has a function of bending an optical axis, and includes a lens group having the non-circular lens, The non-circular lens is disposed facing the subject, The straight portion of the D-cut portion of the non-circular lens seen from the plane and the long side of the light-receiving surface are parallel An imaging device, characterized in that. The method of claim 4, wherein The lens group has a negative power. The method according to any one of claims 2 to 5, The said non-circular lens is the said D cut in two opposing places, The imaging device characterized by the above-mentioned.

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