JP2015119305A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus capable of suppressing the decrease of a peripheral light quantity.SOLUTION: An imaging apparatus 1 is an imaging apparatus for dividing and imaging a field by using a plurality of imaging optical systems. The imaging apparatus 1 includes an optical system a, an optical system b having an optical axis inclined with respect to the optical axis of the optical system a, and an image sensor 40 imaging a field image formed by using each of the optical system a and the optical system b, to acquire image data. The aperture surface of a diaphragm 10b included in the optical system b is formed to be inclined with respect to the aperture surface of a diaphragm 10a included in the optical system a.

Description

  The present invention relates to an imaging apparatus.

  2. Description of the Related Art In recent years, a compound eye optical system that includes a plurality of optical systems and divides an object field to capture an image has been used for the purpose of widening, thinning, and downsizing an imaging optical system.

  For example, Patent Document 1 discloses a compound eye optical system that realizes a small and thin optical system by using an optical element in which a plurality of lenses are arranged in parallel.

Japanese Patent Laid-Open No. 10-145802

  However, the diameter of the light beam passing through the stop changes according to the incident angle of the light beam incident on the optical system. Specifically, the light amount of the light beam decreases as the inclination of the light beam with respect to the axis perpendicular to the aperture surface of the stop increases. For this reason, regardless of whether the optical system is monocular or compound, there is a problem in that the amount of peripheral light decreases in a wide-angle optical system.

  The present invention has been made in view of such a problem, and an object thereof is to provide an imaging apparatus capable of suppressing a decrease in the amount of peripheral light.

  An imaging apparatus according to an aspect of the present invention is an imaging apparatus that divides and captures an object scene using a plurality of imaging optical systems, and includes a first imaging optical system and the first imaging optical system. Imaging a field image formed using each of the second imaging optical system having an optical axis inclined with respect to the optical axis, and the first imaging optical system and the second imaging optical system; An image sensor for acquiring image data, and an aperture of a second aperture included in the second imaging optical system with respect to an aperture surface of the first aperture included in the first imaging optical system The surface is inclined.

  According to the present invention, it is possible to provide an imaging device capable of suppressing a decrease in the amount of peripheral light.

It is a schematic diagram of the compound eye optical system of the imaging device concerning an embodiment. It is sectional drawing of the compound eye optical system concerning embodiment. It is a figure for demonstrating the structure of the aperture_diaphragm | restriction concerning Embodiment. It is a figure which shows the light beam which injects into the compound-eye optical system concerning embodiment. It is a figure which shows the structure of the aperture_diaphragm | restriction of the conventional compound eye optical system. It is a figure which shows the structure of the aperture_diaphragm | restriction of the compound eye optical system concerning embodiment. It is a graph which shows the relationship between the incident angle of a light beam, and the light quantity of a light beam. It is a figure which shows the structure of the aperture_diaphragm | restriction of the compound eye optical system concerning the modification 1. FIG. It is a graph which shows the relationship between the incident angle of a light beam, and the light quantity of a light beam. It is a figure which shows the structure of the aperture_diaphragm | restriction of the compound-eye optical system concerning the modification 2. It is a graph which shows the relationship between the incident angle of a light beam, and the light quantity of a light beam.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, with reference to FIG. 1, the outline | summary of the imaging device 1 concerning this Embodiment is demonstrated. FIG. 1 is a schematic diagram of an imaging optical system (hereinafter simply referred to as an optical system) of an imaging apparatus 1 according to the present embodiment. The imaging device 1 includes an aperture plate 10, a first lens 20, a second lens 30, and an image sensor 40 as an optical system. The diaphragm plate 10, the first lens 20, the second lens 30, and the image sensor 40 are disposed along the optical axis of the imaging device 1. The optical system shown in FIG. 1 is a so-called compound eye optical system. In the compound eye optical system, a plurality of optical systems are gathered, and the object scene is divided, and the divided object scene is formed on the light receiving surface 41 of the image sensor 40 using each optical system. In FIG. 1, the aperture plate 10 side (the front side in FIG. 1) is the object side. That is, the diaphragm plate 10, the first lens 20, the second lens 30, and the image sensor 40 are arranged in order from the object side.

  Next, a specific configuration of the compound eye optical system will be described with reference to FIG. 2 is a cross-sectional view taken along plane A in FIG. The plane A is a plane that passes through the center of the compound-eye optical system.

  The diaphragm plate 10 has a plurality of diaphragms (openings). As shown in FIG. 1, in the present embodiment, the diaphragm plate 10 has nine diaphragms. FIG. 2 shows three diaphragms 10 a to 10 c in the center of the diaphragm plate 10. As shown in FIG. 2, the aperture plate 10 has a bent shape so as to be convex toward the object side.

  The first lens 20 includes a lens formed corresponding to the diaphragms 10a to 10c. In FIG. 2, lenses 20 a to 20 c included in the first lens 20 are shown. Similarly, the second lens 30 includes lenses formed corresponding to the diaphragms 10a to 10c. In FIG. 2, lenses 30 a to 30 c included in the second lens 30 are shown. The first lens 20 and the second lens 30 are also bent so as to be convex toward the subject, corresponding to the shape of the diaphragm plate 10.

  The image sensor 40 is, for example, a sensor such as a CMOS (Complementary Metal Oxide Semiconductor) or a CCD (Charge Coupled Device). The image sensor 40 includes imaging elements 40 a to 40 c that are divided into a plurality of regions on the light receiving surface 41. The image sensor 40 captures an object scene image formed using each of the nine optical systems, and acquires image data.

  2, the diaphragms 10a to 10c, the lenses 20a to 20c, 30a to 30c, and the image sensors 40a to 40c constitute three optical systems a to c. Specifically, the aperture 10a, the lenses 20a and 30a, and the image sensor 40a constitute an optical system a. Similarly, the aperture 10b, the lenses 20b and 30b, and the image sensor 40b constitute an optical system b. The aperture 10c, the lenses 20c and 30c, and the image sensor 40c constitute an optical system c. Therefore, the compound eye optical system shown in FIG. 1 has nine optical systems in total.

  The optical system a (first imaging optical system) is a central optical system among the nine optical systems. The aperture surface of the diaphragm 10a (first diaphragm) of the optical system a is formed to be substantially parallel to the light receiving surface 41 of the image sensor 40. In contrast, in the optical system b (second imaging optical system) adjacent to the optical system a, the aperture surface of the diaphragm 10b (second diaphragm) is formed to be inclined with respect to the light receiving surface 41. . That is, the opening surface of the diaphragm 10b is formed to be inclined with respect to the opening surface of the diaphragm 10a. Similarly, the aperture surface of the diaphragm 10c of the optical system c is also formed to be inclined with respect to the light receiving surface 41 and the aperture surface of the diaphragm 10a. More specifically, the opening surface of the diaphragm 10 b and the opening surface of the diaphragm 10 c are inclined so as to be away from the image sensor 40 toward the center of the image sensor 40.

  That is, the aperture surface of the diaphragm of the optical system other than the central optical system a is formed to be inclined so as to approach the image sensor 40 toward the outside of the image sensor 40. Therefore, although illustration is omitted, even when the compound eye optical system in FIG. 1 is cut in a longitudinal section (a plane passing through the optical system a and orthogonal to the plane A), the sectional view is the same as FIG.

  A detailed configuration of the diaphragm 10a will be described with reference to FIG. The diaphragm 10 a has an opening (hole) 101. The diaphragm 10 a has opening surfaces 102 and 103 of the opening 101. At this time, the opening surface 102 is a surface on which the diaphragm 10a is opened and a surface on the object side. Moreover, the opening surface 103 means a surface on which the diaphragm 10a is opened and is a surface on the image sensor 40 side. In the present embodiment, the opening surface 102 and the opening surface 103 are substantially parallel. The inner wall 104 of the opening 101 is a surface perpendicular to the opening surfaces 102 and 103. In FIG. 3, the diaphragm 10 a has been described as an example, but the diaphragms 10 b and 10 c have the same configuration.

  Here, the angle of the light beam received by each optical system will be described with reference to FIG. FIG. 4 is a diagram showing a light beam received by each optical system shown in FIG. The optical axis of the optical system a is an axis (0 °) perpendicular to the light receiving surface 41 of the image sensor 40. The optical system a can receive a light beam tilted by −30 ° to + 30 ° with respect to an axis perpendicular to the light receiving surface 41 (optical axis of the optical system a). That is, the angle of view of the optical system a is −30 ° to + 30 °.

  The optical axis of the optical system b is an axis inclined by 45 ° with respect to an axis perpendicular to the light receiving surface 41 of the image sensor 40. The optical system b can receive a light beam inclined by + 30 ° to + 60 ° with respect to an axis perpendicular to the light receiving surface 41. That is, the angle of view of the optical system b is + 30 ° to + 60 °. In other words, the optical system b can receive a light beam tilted by −15 ° to + 15 ° with respect to the optical axis (45 °) of the optical system b.

  The optical axis of the optical system c is an axis inclined by −45 ° with respect to an axis perpendicular to the light receiving surface 41 of the image sensor 40. The optical system c receives a light beam tilted by −30 ° to −60 ° with respect to an axis perpendicular to the light receiving surface 41. That is, the angle of view of the optical system c is −30 ° to −60 °. In other words, the optical system c can receive a light beam tilted by −15 ° to + 15 ° with respect to the optical axis (−45 °) of the optical system c. Thus, the optical axes of the optical systems b and c are inclined with respect to the optical axis of the optical system a. Therefore, the image data captured by each of the optical systems a to c is image data having a different angle of view. As a result, the imaging apparatus 1 can capture an image by dividing the object scene into a plurality of regions.

  Next, the operation and effect of the configuration of the imaging device 1 according to the present embodiment will be specifically described. First, the configuration of a conventional compound eye optical system will be described with reference to FIG. FIG. 5 shows two optical systems m and n stops 10m and 10n included in a conventional compound-eye optical system.

  The optical system m is located at the center of the image sensor (not shown). The optical system n is located outside the image sensor with respect to the optical system m. The incident angle of the light beam that can be received by the optical system m is −30 ° to + 30 °. That is, the angle of view of the optical system m is −30 ° to + 30 °. The incident angle of the light beam that can be received by the optical system n is + 30 ° to + 60 °. That is, the angle of view of the optical system n is + 30 ° to + 60 °.

  At this time, the stop 10m of the optical system m and the stop 10n of the optical system n are arranged on the same plane. That is, the opening surface 102m of the stop 10m of the optical system m and the opening surface 102n of the stop 10n of the optical system n are the same surface. The aperture surfaces 102m and 102n of the diaphragms 10m and 10n are substantially parallel to the light receiving surface of the image sensor. Therefore, the optical axes of the optical systems m and n are axes perpendicular to the light receiving surface (0 ° light flux).

  In general, the diameter of the light beam becomes the largest when the incident light beam is perpendicular to the aperture surface of the stop. The diameter of the incident light beam becomes smaller as the incident light beam is tilted from the axis perpendicular to the aperture surface of the stop. Specifically, if the inclination of the light beam with respect to the axis perpendicular to the aperture plane is θ, the diameter of the light beam incident on the optical system is reduced at a ratio of cos θ. In the conventional compound eye optical system, as the distance from the center of the image sensor increases, the inclination of the light beam with respect to the axis perpendicular to the aperture surface of the stop increases. Therefore, in the conventional compound eye optical system, the diameter of the light beam incident on each optical system becomes smaller toward the periphery of the image sensor. As a result, the peripheral light amount is reduced.

  Specifically, as shown in FIG. 5, in the optical system m, the diameter of the light beam with an incident angle of 30 ° is smaller than the diameter of the light beam with an incident angle of 0 °. Further, in the optical system n, the diameter of the light beam with an incident angle of 60 ° is smaller than the diameter of the light beam with an incident angle of 30 °. More specifically, if the diameter of the light beam with an incident angle of 0 ° is 1, the diameter of the light beam with an incident angle of 60 ° is cos 60 ° = ½. That is, the diameter of the light beam with an incident angle of 60 ° is half the diameter of the light beam with an incident angle of 0 °. As a result, the light amount of the light beam having an incident angle of 60 ° is also reduced to half the light amount of the light beam having an incident angle of 0 °.

  On the other hand, the structure of the compound eye optical system concerning this Embodiment is demonstrated with reference to FIG. FIG. 6 shows diaphragms 10a and 10b of optical systems a and b included in the compound-eye optical system according to the present embodiment.

  The configuration of the aperture 10a is the same as the configuration of the aperture 10m in FIG. That is, the opening surface 102 a of the diaphragm 10 a is substantially parallel to the light receiving surface 41 of the image sensor 40. The aperture surface 102a of the stop 10a is perpendicular to the light beam perpendicular to the light receiving surface 41 (light beam with an incident angle of 0 °).

  On the other hand, the opening surface 102b of the diaphragm 10b is inclined by 30 ° with respect to the opening surface 102b of the diaphragm 10a and the light receiving surface 41 of the image sensor 40. That is, the aperture surface 102b of the stop 10b is perpendicular to the light flux with an incident angle of 30 °. Therefore, the diameter of the light flux with an incident angle of 30 ° is the largest. Then, as the incident angle of the light beam is inclined from 30 °, the diameter of the light beam is reduced.

  More specifically, in the optical system a, if the diameter of the light beam with an incident angle of 0 ° (the optical axis of the optical system a) is 1, the diameter of the light beam with an incident angle of 30 ° is cos 30 ° = √3 / 2. . In the optical system b, if the diameter of the light beam with an incident angle of 30 ° is √3 / 2, the diameter of the light beam with an incident angle of 60 ° is cos (60 ° -30 °) = √3 / 2. That is, the diameter of the light beam with an incident angle of 60 ° is √3 / 2 × √3 / 2 = 3/4 times the diameter of the light beam with an incident angle of 0 °. As a result, the light amount of the light beam with the incident angle of 60 ° is reduced to 3/4 times the light amount of the light beam with the incident angle of 0 °. However, the diameter of the light beam having an incident angle of 60 ° is larger than that of the conventional configuration shown in FIG. Therefore, compared with the conventional configuration, the light quantity of the luminous flux having an incident angle of 60 ° is increased.

  Here, with reference to FIG. 7, the difference in light quantity between the conventional configuration and the configuration of the present application will be described. FIG. 7 is a graph showing the relationship between the incident angle of the light beam and the light amount of the light beam. The horizontal axis represents the incident angle of the light beam (the incident angle of the light beam when the axis perpendicular to the light receiving surface of the image sensor is 0 °). The vertical axis represents the light amount of the light beam (ratio when the light amount at an incident angle of 0 ° is 1).

  First, attention is focused on a range where the incident angle of the light beam is 0 ° to 30 °. In this range, the optical system a or the optical system m receives a light beam in this range. As described above, since the configurations of the optical system a and the optical system m are the same, there is no difference in the amount of light between the conventional and the present embodiment.

  Next, attention is focused on the range where the incident angle of the light beam is 30 ° to 60 °. In this range, the optical system b or the optical system n receives a light beam in this range. As indicated by the broken line, in the conventional optical system n, the amount of light decreases at the same rate (1 × cos θ) as 0 ° to 30 °. For this reason, when the incident angle of the light beam is 60 °, 1 × cos 60 ° = 0.5.

  On the other hand, as shown by the solid line, in the optical system b according to the present embodiment, the reduction rate is small. Specifically, it decreases at a rate of (√3 / 2) cos (θ-30 °). For this reason, when the incident angle of the light beam is 60 °, (√3 / 2) cos (60 ° -30 °) = 0.75. That is, when the incident angle of the light beam is 60 °, the optical system b according to the present embodiment can receive a light amount 1.5 times that of the conventional optical system n.

  In the present embodiment, it is preferable that the amount of light when the optical system a receives a light beam with an incident angle of 30 ° is equal to the amount of light when the optical system b receives light. That is, it is preferable that the graph of FIG. 7 is not interrupted (continuous) at a point where the incident angle is 30 °. Thus, when the optical system a and the optical system b receive a light beam with an incident angle of 30 °, the brightness of the image data captured by the optical system a and the brightness of the image data captured by the optical system b , Are equal. In other words, the amount of light when the optical system a receives a light beam with the maximum field angle (30 °) of the optical system a, and the amount of light when the optical system b receives a light beam with the maximum field angle (30 °) of the optical system b. The amount of light is the same. Therefore, it is not necessary to separately adjust the brightness using image processing after the image data is generated, and the burden of calculation processing is reduced. Accordingly, the stop 10a of the optical system a is set so that the amount of light when the optical system a receives a light beam with an incident angle of 30 ° is equal to the amount of light when the optical system b receives a light beam with an incident angle of 30 °. And the aperture area of the stop 10b of the optical system b are preferably determined.

  As described above, according to the configuration of the imaging apparatus 1 according to the present embodiment, the imaging apparatus 1 includes the plurality of optical systems a to c having different optical axes and divides and captures the object scene image. The aperture surface of the diaphragm 10b included in the optical system b is formed to be inclined with respect to the aperture surface of the diaphragm 10a included in the optical system a. For this reason, in the peripheral portion of the image sensor, when the light beam having an incident angle closer to the axis perpendicular to the aperture surface of the aperture stop 10b is received than the axis perpendicular to the aperture surface of the aperture aperture 10a, The diameter is larger than the diameter of the light beam passing through the stop 10a. As a result, the imaging apparatus 1 can suppress a decrease in the amount of ambient light as compared with a diaphragm having a plurality of aperture surfaces formed on the same surface.

  In the above embodiment, the inclination of the aperture surface of the diaphragm 10b is set to 30 °, but the present invention is not limited to this. The aperture surface of the stop 10b may be formed so as to be substantially perpendicular to the principal ray of the light beam (30 ° to 60 °) that can be received by the optical system b. The principal ray is a ray that passes through the center of the aperture of the stop. In the following modified examples 1 and 2, the case where the inclination of the opening surface of the diaphragm 10b is 45 ° and the case where it is 60 ° will be exemplified.

(Modification 1)
A first modification of the present embodiment will be described. FIG. 8 shows configurations of the diaphragm 10a of the optical system a and the diaphragm 10b of the optical system b according to the first modification. Other configurations are the same as the configurations in FIGS. 1 and 2, and thus the description thereof is omitted.

  As shown in FIG. 8, the opening surface 102b of the diaphragm 10b according to Modification 1 is formed to be inclined by 45 ° with respect to the opening surface 102a of the diaphragm 10a. That is, the diameter of the light beam passing through the stop 10b is maximized when the incident angle of the light beam is 45 °.

  Next, with reference to FIG. 9, the difference in light quantity between the conventional configuration and the configuration of Modification 1 will be described. The graph of FIG. 9 corresponds to the graph shown in FIG. 6, the horizontal axis indicates the incident angle of the light beam, and the vertical axis indicates the light amount of the light beam.

  As shown in FIG. 9, the light quantity of the light beam passing through the stop 10b of the optical system b gradually increases from the point where the incident angle is 30 °, reaches a peak when the incident angle is 45 °, and then gradually decreases. To go. When the incident angle of the light beam is 60 °, the light amount according to the configuration of the first modification is 0.87. That is, when the incident angle of the light beam is 60 °, according to the configuration of the first modification, it is possible to receive 1.74 times the amount of light compared to the light amount of the conventional configuration. As a result, a decrease in the amount of ambient light can be suppressed.

(Modification 2)
A second modification of the present embodiment will be described. FIG. 10 shows configurations of the diaphragm 10a of the optical system a and the diaphragm 10b of the optical system b according to the second modification. Other configurations are the same as the configurations in FIGS. 1 and 2, and thus the description thereof is omitted.

  As shown in FIG. 10, the opening surface 102b of the diaphragm 10b according to Modification 1 is formed to be inclined by 60 ° with respect to the opening surface 102a of the diaphragm 10a. That is, the diameter of the light beam passing through the stop 10b is maximized when the incident angle of the light beam is 60 °.

  Next, with reference to FIG. 11, the difference in light quantity between the conventional configuration and the configuration of Modification 1 will be described. The graph of FIG. 11 corresponds to the graph shown in FIG. 7, the horizontal axis indicates the incident angle of the light beam, and the vertical axis indicates the light amount of the light beam.

  As shown in FIG. 11, the light quantity of the light beam passing through the stop 10b of the optical system b gradually increases from the point where the incident angle is 30 °, and reaches a peak when the incident angle is 60 °. When the incident angle of the light beam is 60 °, the light amount by the configuration of the modification 2 is 1.0. That is, when the incident angle of the light beam is 60 °, according to the configuration of the second modification, it is possible to receive twice the amount of light as compared with the light amount of the conventional configuration. As a result, a decrease in the amount of ambient light can be suppressed.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed and combined without departing from the spirit of the present invention. For example, in the above-described embodiment, a compound eye optical system including nine optical systems has been described, but the number of optical systems is not limited to this. Further, although 30 °, 45 °, and 60 ° are employed as examples of angles formed by the aperture surface of the diaphragm 10a and the aperture surface of the diaphragm 10b, the present invention is not limited to these angles. Further, the number and shape of the lenses 20 and 30 are not limited to the number and shape of the present embodiment. Further, in FIG. 2, the end of the diaphragm 10a is connected to the end of the diaphragm 10b and the end of the diaphragm 10c, but these diaphragms may be physically separated. Further, the distance from each aperture to the image sensor 40 is not limited to the configuration shown in FIG.

DESCRIPTION OF SYMBOLS 1 Imaging device 10 Diaphragm | plate 10a-10c Diaphragm | restriction 20 1st lens 30 2nd lens 20a-20c, 30a-30c Lens 40 Image sensor 40a-40c Image pick-up element 41 Light-receiving surface 101 Opening part 102, 103 Opening surface 104 Inner wall

Claims (5)

An imaging apparatus that divides and captures an object scene using a plurality of imaging optical systems,
A first imaging optical system;
A second imaging optical system having an optical axis inclined with respect to the optical axis of the first imaging optical system;
An image sensor that captures an object scene image formed using each of the first imaging optical system and the second imaging optical system and acquires image data; and
An imaging apparatus in which an aperture surface of a second diaphragm included in the second imaging optical system is inclined with respect to an aperture surface of a first aperture included in the first imaging optical system.   2. The imaging apparatus according to claim 1, wherein an opening surface of the second diaphragm is inclined so as to be separated from the image sensor toward a center of the image sensor. An opening surface of the first diaphragm is substantially parallel to a light receiving surface of the image sensor;
The imaging apparatus according to claim 1, wherein an opening surface of the second diaphragm is inclined with respect to a light receiving surface of the image sensor.   The opening surface of the second diaphragm is formed so as to be substantially perpendicular to a principal ray of a light beam that can be received by the second imaging optical system. Imaging device. The first imaging optical system and the second imaging optical system are disposed adjacent to each other,
The light amount when the first imaging optical system receives a light beam with a maximum angle of view and the light amount when the second imaging optical system receives a light beam with a maximum angle of view are the same light amount. The imaging apparatus as described in any one of -4.

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