JP2016038467A - Image pick-up element, focus detection device and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure an amount of incident light upon each of a pair of photoelectric conversion parts provided relative to one micro lens.SOLUTION: An image pick-up element has: a plurality of pixels that has a plurality of micro lenses; and a pair of photoelectric conversion units that is provided relative to the plurality of micro lenses, receives a pair of light fluxes passing through a pair of pupil areas and is two-dimensionally arrayed. In the plurality of pixels, a sum of an area of the pair of photoelectric conversion units is substantially equal, and an area of each oh the pair of photoelectric conversion units is different in accordance with an array position of the plurality of pixels.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an imaging device, a focus detection device, and an imaging device.

  Conventionally, a pair of light receiving elements are provided for one microlens, and the focus detection pixels arranged so that the pair of light receiving elements are symmetrical with respect to the optical axis of the microlens, and the optical axis of the microlens On the other hand, an image sensor is known in which focus detection pixels are arranged so that a pair of light receiving elements are asymmetric (for example, Patent Document 1).

JP 2011-221253 A

  However, since the amount of light incident on each of the pair of light receiving elements arranged for the same microlens is different, the output of one of the light receiving elements is saturated and cannot be used for focus detection calculation. There is a problem that the accuracy cannot be maintained.

The imaging device according to claim 1 is provided for each of the plurality of microlenses and the plurality of microlenses, and a pair of photoelectric conversions that receive a pair of light beams that have passed through a pair of pupil regions of the imaging optical system. A plurality of pixels arranged two-dimensionally, and all the plurality of pixels are substantially equal in total area of the pair of photoelectric conversion units, and are in accordance with the arrangement positions of the plurality of pixels. Thus, the areas of the pair of photoelectric conversion units are different.
The image pickup device according to claim 7 includes a plurality of microlenses and a plurality of pixels arranged in a two-dimensional manner for each of the plurality of microlenses, and the plurality of pixels includes a pair of pupil regions. The first pixel having a photoelectric conversion unit that receives one of a pair of light beams that have passed through and the second pixel having a photoelectric conversion unit that receives the other of the pair of light beams that have passed through a pair of pupil regions are alternately arranged. The sum of the areas of the photoelectric conversion unit of the first pixel that receives one of the pair of light beams and the photoelectric conversion unit of the second pixel that receives the other of the pair of light beams is substantially equal, depending on the arrangement position of the plurality of pixels Thus, the area of the photoelectric conversion unit of the first pixel is different from the area of the photoelectric conversion unit of the second pixel.
A focus detection apparatus according to a ninth aspect of the present invention is a detection for detecting a focus state of a subject using the image sensor according to any one of the first to eighth aspects and a signal output from a pair of photoelectric conversion units. Means.
According to a tenth aspect of the present invention, there is provided an imaging apparatus that detects a focus state of a subject using the imaging element according to any one of the first to eighth aspects and a signal output from a pair of photoelectric conversion units. And image generation means for adding the signals output from the pair of photoelectric conversion units to generate an image signal.

  According to the present invention, it is possible to prevent saturation of the output of one of the pair of photoelectric conversion units even in pixels located near the periphery of the plurality of pixels, and to suppress a decrease in focus detection accuracy.

1 is a cross-sectional view illustrating the configuration of an imaging apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating a main configuration of an imaging apparatus according to an embodiment The figure which shows an example of the arrangement | sequence of the imaging pixel by embodiment The figure which shows typically the projection relationship of the area of the 1st photoelectric conversion part of the imaging pixel in embodiment, and the 2nd photoelectric conversion part, and the exit pupil area | region of a photographic lens system The figure which shows an example of the arrangement | sequence of the imaging pixel in a modification The figure which shows an example of the arrangement | sequence of the imaging pixel in a modification The figure which shows an example of the arrangement | sequence of the imaging pixel in a modification

With reference to the drawings, an image sensor according to an embodiment of the present invention, and a focus detection apparatus and an image apparatus including the image sensor will be described.
FIG. 1 is a cross-sectional view illustrating a configuration of a digital camera 100 that is an imaging apparatus according to an embodiment. For convenience of explanation, a coordinate system including an x-axis, a y-axis, and a z-axis is set as illustrated.

  The digital camera 100 includes a camera main body 200 and a photographing lens main body 300, and the photographing lens main body 300 is a so-called mirrorless camera that is mounted via a mount unit (not shown). A photographic lens body 300 having various photographic optical systems can be attached to the camera body 200 via a mount portion. The mount portion is provided with electrical contacts 201 and 202. When the camera body 200 and the photographing lens body 300 are coupled, an electrical connection is established via the electrical contacts 201 and 202.

  The photographic lens main body 300 includes a photographic lens system 1, a diaphragm 2, a drive mechanism 3, and a lens data unit 4. The photographing lens system 1 is an optical system for forming a subject image on a predetermined planned focal plane, and is composed of a plurality of lenses including a focus adjustment lens. The diaphragm 2 forms an aperture whose aperture diameter is variable around the optical axis L in order to limit the light beam passing through the photographing lens system 1, that is, the amount of incident light. The drive mechanism 3 calculates the lens drive amount using the defocus amount input from the camera body 200 side through the electrical contact 201, and moves the focus adjustment lens constituting the photographing lens system 1 according to the lens drive amount to the optical axis. Drive to the in-focus position along the L direction (z-axis direction). The drive mechanism 3 controls the drive of the diaphragm 2 by outputting a diaphragm drive signal in response to a command from the camera body 200 side.

  The lens data unit 4 is configured by, for example, a non-volatile recording medium, and stores various lens information related to the photographing lens main body 300, for example, the focal length and brightness (open F value) of the lens. The lens data unit 4 transmits the above lens information and the like to and from the camera body 200 via the electrical contact 202.

  In the camera body 200, an arithmetic processing control unit 5, an image sensor control circuit 6, a mechanical shutter 7, an image sensor 8, an electronic viewfinder (EVF) 9, and an eyepiece 10 are provided. The camera body 200 is provided with an operation unit 11. In the imaging element 8, imaging pixels such as a CCD and a CMOS are two-dimensionally arranged (rows and columns) on the xy plane. The imaging pixels of the imaging device 8 are provided with R (red), G (green), and B (blue) color filters, respectively. The image sensor 8 receives a light beam incident through the photographing lens system 1 and the mechanical shutter 7 to capture a subject image, and outputs an image signal to the image sensor controller 6. The imaging signal is used as a signal for generating image data (image signal) and a signal for focus detection (focus detection signal). Since the image pickup device 8 picks up a subject image through the color filter, the image pickup signal output from the image pickup pixel of the image pickup device 8 has color information of the RGB color system. Details of the image sensor 8 will be described later.

  The mechanical shutter 7 is provided immediately before the image sensor 8 and includes a front curtain and a rear curtain made up of a plurality of light shielding blades. The mechanical shutter 7 travels by driving a drive mechanism (not shown) constituted by a drive motor (for example, an electric motor such as a DC motor or a stepping motor) to shield the image sensor 8 from the subject light. The electronic viewfinder 9 displays an image corresponding to the display image data generated by the arithmetic processing control unit 5. The electronic viewfinder 9 displays various information (shutter speed, aperture value, ISO sensitivity, etc.) related to the shooting conditions. The image and various information displayed on the electronic viewfinder 9 are observed by the user through the eyepiece 10.

  The operation unit 11 includes various switches provided corresponding to various operation members operated by the user, and outputs an operation signal corresponding to the operation of the operation member to the arithmetic processing control unit 5. The operation member is, for example, a release button, a menu button for displaying a menu screen on a rear monitor (not shown) provided on the rear surface of the camera body 200, or a cross key operated when selecting and operating various settings. , A determination button for determining the setting selected by the cross key, an operation mode switching button for switching the operation of the digital camera 100 between the shooting mode and the playback mode, an exposure mode switching button for setting the exposure mode, and the like. .

  Further, the control system of the digital camera 100 will be described with reference to the block diagram shown in FIG. As shown in FIG. 2, the digital camera 100 includes an A / D conversion unit 12, an image processing circuit 13, a focus detection calculation circuit 14, and a body-lens communication unit 15. The arithmetic processing control unit 5 includes a CPU, a ROM, a RAM, and the like, and is an arithmetic circuit that controls each component of the digital camera 100 and executes various data processing based on a control program. The control program is stored in a nonvolatile memory (not shown) in the arithmetic processing control unit 5. The image sensor driving circuit 6 is controlled by the arithmetic processing control unit 5 and controls driving of the image sensor 8 and the A / D converter 12 to cause the image sensor 8 to perform charge accumulation, image signal readout, and the like. The A / D converter 12 converts the analog imaging signal output from the imaging device 8 into digital.

  The image processing circuit 13 uses the image signal output from the image sensor 8 as an image signal, performs various image processing on the image signal to generate image data, and then adds additional information and the like to generate an image file. Generate. The image processing circuit 13 records the generated image file on a recording medium (not shown) such as a memory card. The image processing circuit 13 generates display image data to be displayed on the electronic viewfinder 9 and a rear monitor (not shown) based on the generated image data and image data recorded on the recording medium.

  The focus detection calculation circuit 14 uses the imaging signal output from the imaging device 8 as a focus detection signal and calculates a defocus amount using a known phase difference detection method. The body-lens communication unit 15 is controlled by the arithmetic processing control unit 5 and communicates with the drive mechanism 3 and the lens data unit 4 in the photographic lens main body 300 via the electrical contacts 201 and 202 to obtain camera information (defocus amount). And aperture value) and lens information are received.

Next, the image sensor 8 in the present embodiment will be described in detail.
FIG. 3A is a plan view schematically showing a partial region including the central portion of the image sensor 8, and FIG. 3B is a diagram of one image pickup pixel 80 provided near the center of the image sensor 8. FIG. 3C is a diagram schematically showing a cross section of one image pickup pixel 80 provided in the peripheral portion of the image sensor 8. Also in FIG. 3, a coordinate system including the x-axis, y-axis, and z-axis is set in the same manner as in the example shown in FIG. In the imaging element 8, a plurality of imaging pixels 80 are two-dimensionally arranged in a row direction (x direction) and a column direction (y direction). At each pixel position of the imaging pixel 80, for example, the color filters (R: red filter, G: green filter, B: blue filter) described above are arranged according to the rules of the Bayer array. In FIG. 3A, the color of the color filter arranged in the imaging pixel 80 is schematically expressed as “R”, “G”, or “B”.

  The imaging pixel 80 includes a microlens 81 and a first photoelectric conversion unit 82 and a second photoelectric conversion unit 83 provided under one microlens 81. The first photoelectric conversion unit 82 and the second photoelectric conversion unit 83 are arranged side by side in the x direction. In the example illustrated in FIG. 3, the first photoelectric conversion unit 82 is provided on the x direction + side, and the second photoelectric conversion unit 83 is provided on the x direction − side. Light incident through the different regions of the photographic lens system 1 is incident on the first photoelectric conversion unit 82 and the second photoelectric conversion unit 83. That is, a pair of subject light beams used by the focus detection calculation circuit 14 for phase difference detection calculation are incident.

  In the present embodiment, in each row, the boundary portion 84 between the first photoelectric conversion unit 82 and the second photoelectric conversion unit 83 is shifted from the center of the microlens 81 according to the position where the imaging pixel 80 is arranged ( (Refer FIG.3 (c)). In all the imaging pixels 80, the total value of the area of the first photoelectric conversion unit 82 and the area of the second photoelectric conversion unit 83 is substantially the same. In other words, the size (area) of the first photoelectric conversion unit 82 and the size (area) of the second photoelectric conversion unit 83 are different. On the x direction + side from the center row C of the image sensor 8, the boundary portion 84 is shifted to the x direction − side with respect to the center of the microlens 81, and from the center row C to the x direction − side, In contrast, the boundary portion 84 is shifted to the + direction in the x direction. In other words, the area of the first photoelectric conversion unit 82 is larger than the area of the second photoelectric conversion unit 83, and the area of the first photoelectric conversion unit 82 and the second photoelectric conversion unit 83 according to the distance from the center column C. The difference from the area becomes larger. On the x direction − side, the area of the second photoelectric conversion unit 83 is larger than the area of the first photoelectric conversion unit 82, and the area of the second photoelectric conversion unit 83 and the first photoelectric conversion unit 83 are set according to the distance from the center column C. The difference from the area of the photoelectric conversion unit 82 increases.

  Even if the shift amount of the boundary portion 84 with respect to the microlens 81, that is, the difference between the area of the second photoelectric conversion unit 83 and the area of the first photoelectric conversion unit 82 changes linearly according to the distance from the center row C. Alternatively, it may be changed stepwise for each predetermined number of imaging pixels 80. In each row, in the imaging pixels 80 arranged in the center column C of the imaging element 8, the center of the microlens 81 and the boundary portion 84 substantially coincide, that is, the area of the first photoelectric conversion unit 82 and the second photoelectric conversion unit. The area of 83 is equal. As described above, since the total value of the area of the first photoelectric conversion unit 82 and the area of the second photoelectric conversion unit 83 is substantially the same in all the image pickup pixels 80, the image pickup pixel 80 includes the image sensor 8. The area ratio between the first photoelectric conversion unit 82 and the second photoelectric conversion unit 83 differs depending on the distance in the x direction from the center column C.

  As shown in FIG. 3A, a boundary portion 84a between the first photoelectric conversion unit 82a and the second photoelectric conversion unit 83a provided in the imaging pixels 80a arranged in the center column C of the imaging element 8 is a microlens 81a. Is substantially equal to the center of That is, the first photoelectric conversion unit 82a and the second photoelectric conversion unit 83a have the same area. In the imaging pixel 80b arranged on the x direction + side with respect to the imaging pixel 80a, the boundary portion 84b is shifted to the x direction − side with respect to the center of the micro lens 81b. That is, the area of the first photoelectric conversion unit 82b is larger than the area of the second photoelectric conversion unit 83b. As described above, in all the imaging pixels 80, the total value of the area of the first photoelectric conversion unit 82 and the area of the second photoelectric conversion unit 83 is formed to be the same. Therefore, the area of the first photoelectric conversion unit 82b of the imaging pixel 80b is larger than the area of the first photoelectric conversion unit 82a of the imaging pixel 80a, and the imaging pixel 80b is larger than the area of the second photoelectric conversion unit 83a of the imaging pixel 80a. The area of the second photoelectric conversion unit 83b is smaller.

  In the imaging pixel 80c arranged on the + side in the x direction with respect to the imaging pixel 80b, the shift amount of the boundary portion 84c with respect to the center of the microlens 81c is larger than the shift amount of the boundary portion 84b with respect to the center of the microlens 81b. That is, as the imaging pixel 80 is arranged on the x direction + side, the amount of deviation between the boundary portion 84 and the center of the microlens 81 increases toward the x direction − side. The area of the first photoelectric conversion unit 82c of the imaging pixel 80c is larger than the area of the first photoelectric conversion unit 82b of the imaging pixel 80b, and the area of the imaging pixel 80c is larger than the area of the second photoelectric conversion unit 83b of the imaging pixel 80b. The area of the two photoelectric conversion unit 83c is smaller.

In the imaging pixel 80d arranged on the x direction minus side with respect to the imaging pixel 80a, the boundary portion 84d is shifted to the x direction plus side with respect to the center of the micro lens 81d. That is, the area of the second photoelectric conversion unit 83d is larger than the area of the first photoelectric conversion unit 82d. Therefore, the area of the first photoelectric conversion unit 82d of the imaging pixel 80d is smaller than the area of the first photoelectric conversion unit 82a of the imaging pixel 80a, and the imaging pixel 80d is smaller than the area of the second photoelectric conversion unit 83a of the imaging pixel 80a. The area of the second photoelectric conversion unit 83d is larger. In the imaging pixel 80e arranged on the x direction minus side from the imaging pixel 80d, the amount of deviation of the boundary portion 84e from the center of the micro lens 81e in the x direction plus side is x with respect to the center of the micro lens 81d in the boundary portion 84d. Larger than the deviation on the direction + side. That is, the area of the second photoelectric conversion unit 83e of the imaging pixel 80e is larger than the area of the second photoelectric conversion unit 83d of the imaging pixel 80d, and the imaging pixel 80e is larger than the area of the first photoelectric conversion unit 82d of the imaging pixel 80d. The area of the first photoelectric conversion unit 82e is smaller.
The relationship between the boundary portion 84 and the center of the microlens 81 and the relationship between the area of the first photoelectric conversion unit 82 and the area of the second photoelectric conversion unit 83 will be described later in detail.

  In each of the first photoelectric conversion unit 82 and the second photoelectric conversion unit 83 of the imaging pixel 80, the first photoelectric conversion unit 82 is changed by changing the length in the x direction without changing the length in the y direction. And the area ratio with the 2nd photoelectric conversion part 83 is changed. That is, in the imaging pixels 80 arranged in the x direction + side, the length in the x direction of the first photoelectric conversion unit 82 increases as the distance from the center column C of the imaging element 8 increases, and the second photoelectric conversion unit. The length of 83 in the x direction decreases. In the imaging pixels 80 arranged on the x direction − side, the length of the first photoelectric conversion unit 82 in the x direction decreases as the distance from the center column C of the imaging element 8 increases, and the second photoelectric conversion unit 83 The length in the x direction increases.

  In the image pickup pixel 80 arranged in the column direction (y direction) in the image pickup device 8, the first photoelectric conversion unit 82 and the second photoelectric conversion unit 83 have the same area. That is, for example, for the imaging pixels 80 arranged in the same column as the imaging pixel 80c, the first photoelectric conversion unit 82 having the same area as the first photoelectric conversion unit 82c and the same area as the second photoelectric conversion unit 83c. A second photoelectric conversion unit 83 is provided.

In the present embodiment, the first photoelectric conversion unit 82 and the second photoelectric conversion unit 83 of the imaging pixel 80 are configured as described above, thereby reducing the influence of vignetting in the peripheral region of the imaging element 8. Hereinafter, the principle will be described.
FIG. 4 schematically shows the projection relationship between the area of the first photoelectric conversion unit 82 and the second photoelectric conversion unit 83 of the imaging pixel 80 and the exit pupil region of the photographing lens system 1. FIG. 4A shows a case where the exit pupil distance PO1 of the photographing lens system 1 and the exit pupil distance PO2 of the imaging pixel 80 are substantially equal, that is, to fit the digital camera 100 in which the photographing lens system 1 is a mirrorless camera. The case of a special interchangeable lens designed in Fig. 1 is shown. 4B shows a case where the exit pupil distance PO1 of the photographic lens system 1 is longer than the exit pupil distance PO2 of the imaging pixel 80, that is, the photographic lens system 1 is an interchangeable lens designed for a single lens reflex camera, for example. A case where a long exit pupil distance PO1 is set is a dedicated interchangeable lens designed to be compatible with the digital camera 100 which is a mirrorless camera. In FIG. 4B, for the purpose of facilitating understanding, the taking lens system 1 when the exit pupil distances PO1 and PO2 are equal is indicated by a broken line. In the present embodiment, the exit pupil distance PO2 of the imaging pixel 80 is set to be shorter than the center value of the exit pupil distances PO1 that differ for each of the various dedicated interchangeable lenses. In the following description, the imaging pixel 80c arranged in the peripheral region on the x direction + side in FIG. 3 will be described as an example.

  As shown in FIG. 4A, the first photoelectric conversion unit 82c has a light beam 851 that has passed through the exit pupil region 841 of the pair of exit pupil regions 841 and 842 of the photographing lens system 1 out of the light beam from the subject. Is received through the micro lens 81c, and the second photoelectric conversion unit 83c receives the light beam 852 that has passed through the exit pupil region 842 through the micro lens 81c. As described above, FIG. 4A shows a case in which the exit pupil distances PO1 and PO2 are substantially equal. Therefore, the luminous fluxes 851 and 852 have no vignetting due to the structure of the photographing lens body 300 or the like. In this state, the light enters the first photoelectric conversion unit 82c and the second photoelectric conversion unit 83c.

  As shown in FIG. 4B, the light beam 852 from the subject passes through the exit pupil region 842 of the photographing lens system 1 and enters the second photoelectric conversion unit 83c through the microlens 81c of the imaging pixel 80c. Since the exit pupil distance PO1 of the photographing lens system 1 is longer than the exit pupil distance PO2 of the imaging pixel 80, part of the luminous flux 851 from the subject is vignetted. That is, of the light beam 851, the light beam 851a passes through the exit pupil region 841 of the photographing lens system 1 and enters the first photoelectric conversion unit 82c via the microlens 81c, and the light beam 851b vignetts and enters the first photoelectric conversion unit 82c. Not incident.

  In the schematic plan view of the imaging pixel 80c in FIG. 4C, the luminous flux 852, the luminous flux 851 affected by the vignetting as described above, the first photoelectric conversion unit 82c and the second photoelectric conversion unit 83c of the imaging pixel 80c, and The positional relationship of is shown. In FIG. 4C, a region that will be incident on the first photoelectric conversion unit 82c if there is no vignetting in the light beam 851b is indicated by a broken line. In the present embodiment, the first photoelectric conversion unit 82c has a region 82c1 where the light beam 851a is incident and a region 821c2 that would be incident if the light beam 851b was not vignetted. In the imaging pixel 80c, the amount of deviation of the boundary portion 84c in the x direction − side is such that the region 82c1 of the first photoelectric conversion portion 82c and the second photoelectric conversion portion 83c on which the light beam 852 is incident have the same area. It has been decided. Therefore, when the boundary portion 84c is shifted toward the x direction − side with respect to the center of the microlens 81c, the incident light beams 852 and 851a are substantially changed in the first photoelectric conversion portion 82c and the second photoelectric conversion portion 83c, respectively. Light is received in the same area.

  For the imaging pixel 80b, similarly to the imaging pixel 80c, the shift amount of the boundary 84b, that is, the areas of the first photoelectric conversion unit 82b and the second photoelectric conversion unit 83b are determined. However, as described above, since the imaging pixel 80b is arranged on the x direction minus side from the imaging pixel 80c, the shift amount of the boundary portion 84b is smaller than the shift amount of the boundary portion 84c. That is, the area of the first photoelectric conversion unit 82b of the imaging pixel 80b is smaller than the area of the first photoelectric conversion unit 82c of the imaging pixel 80c. In addition, with respect to the imaging pixels 8 arranged on the x direction − side from the center row C of the imaging element 8, the direction in which the boundary portion 84 is shifted from the center of the microlens 81, that is, the first photoelectric conversion unit 82 and the second photoelectric conversion unit. The area relationship of the conversion unit 83 is reversed.

  In FIG. 4D, when it is assumed that the imaging pixel 80a is arranged at the position where the imaging pixel 80c is arranged, that is, when the boundary portion 84 substantially coincides with the center of the microlens 81, the exit pupil distance PO1 is It is a top view which shows typically the light beams 851 and 852 which inject into the 1st photoelectric conversion part 82a and the 2nd photoelectric conversion part 83a, respectively, when it is larger than the exit pupil distance PO2. In this case, vignetting of the light beam 851 causes the light beam 851a to be received by the first photoelectric conversion unit 82a in the shaded area in the figure. The light beam 852 is received by the entire region of the second photoelectric conversion unit 83a. For this reason, the output of the imaging signal from the 1st photoelectric conversion part 82a falls compared with the output of the imaging signal from the 2nd photoelectric conversion part 83a. That is, the output of the imaging signal from the second photoelectric conversion unit 83c is saturated before the imaging signal from the first photoelectric conversion unit 82c reaches a sufficient output.

  On the other hand, the present embodiment has a structure shown in FIG. Therefore, it is possible to prevent the output of the imaging signal from the first photoelectric conversion unit 82c from being lowered as compared with the output of the imaging signal from the second photoelectric conversion unit 83c, and the imaging signal from the first photoelectric conversion unit 82c is sufficient. Before reaching the output, the output of the imaging signal from the second photoelectric conversion unit 83c is prevented from being saturated.

  The focus detection calculation circuit 14 uses the imaging signal output from the imaging pixel 80 having the above-described structure as a focus detection signal, and calculates a defocus amount using a known phase difference detection method. The focus detection calculation circuit 14 includes a first signal sequence {an} in which focus detection signals from the first photoelectric conversion unit 82 are sequentially arranged, and a second signal sequence in which focus detection signals from the second photoelectric conversion unit 83 are sequentially arranged. A relative shift amount with respect to {bn} is detected, and a focus adjustment state of the photographing lens system 1, that is, a defocus amount is detected.

  The image processing circuit 13 uses the imaging signal output from the imaging pixel 80 as an image signal when generating image data. For each imaging pixel 80, the image processing circuit 13 adds the imaging signal output from the first photoelectric conversion unit 82 and the imaging signal output from the second photoelectric conversion unit 83 to handle as an image signal. Therefore, there is no influence due to the area difference between the first photoelectric conversion unit 82 and the second photoelectric conversion unit 83. Since the imaging pixel 80 is provided with a color filter of any of R, G, and B colors, the added image signal has color information corresponding to the color filter provided in the imaging pixel 80. The image processing circuit 13 performs various image processing on the image signal generated by the addition to generate image data, and adds additional information and the like to generate an image file.

According to the embodiment described above, the following operational effects can be obtained.
In all of the plurality of imaging pixels 80, the total area of the pair of first photoelectric conversion units 82 and second photoelectric conversion units 83 is substantially equal, and the arrangement position of the plurality of imaging pixels 80, that is, the center of the imaging element 8. The areas of the pair of first photoelectric conversion units 82 and second photoelectric conversion units 83 differ depending on the distance from the vicinity. That is, as the distance from the vicinity of the center of the image sensor 8 increases, the area difference between the pair of first photoelectric conversion units 82 and second photoelectric conversion units 83 increases. Accordingly, the incident light flux is affected by vignetting at the periphery of the image sensor 8 as in the case where the photographing lens system 1 having the exit pupil distance PO1 longer than the exit pupil distance PO2 of the image sensor 8 is mounted. Even so, the amount of light incident on the first photoelectric conversion unit 82 or the second photoelectric conversion unit 83 can be secured. Therefore, the second photoelectric conversion unit 83 receives the light beam 852 that is not affected by the vignetting until the second photoelectric conversion unit 83 receives the light amount that the first photoelectric conversion unit 82 can calculate the light beam 851 that is affected by the vignetting. It is possible to prevent the output of the two photoelectric conversion unit 83 from being saturated, and to suppress a decrease in focus detection accuracy.

The following modifications are also within the scope of the present invention, and one or a plurality of modifications can be combined with the above-described embodiment.
(1) In the embodiment, the case where the exit pupil distance PO1 of the photographing lens system 1 is longer than the exit pupil distance PO2 of the imaging pixel 80 as shown in FIG. A case where the system 1 is mounted will be described. In this case, vignetting does not occur in the light beam 851, but vignetting occurs in the light beam 852. Therefore, the light beam 851 from the subject passes through the exit pupil region 841 of the photographing lens system 1 and enters the first photoelectric conversion unit 82c via the microlens 81c of the imaging pixel 80c. Further, the vignetting of the light beam 852 causes a part of the light beam 852 to pass through the exit pupil region 842 of the photographing lens system 1 and enter the second photoelectric conversion unit 83c via the micro lens 81c. In this case, in order to reduce the influence of vignetting in the peripheral region of the image sensor 8, the area of the first photoelectric conversion unit 82c of the image sensor 80c is configured to be larger than the area of the second photoelectric conversion unit 83c. That's fine. That is, the imaging pixel 80e may be arranged in place of the imaging pixel 80c shown in FIG.

  FIG. 5 shows an example of the arrangement of the imaging pixels 80 in the imaging element 8 when the exit pupil distance PO1 is made to correspond to the photographing lens system 1 shorter than the exit pupil distance PO2. As shown in FIG. 5, the area of the first photoelectric conversion unit 82 is smaller than the area of the second photoelectric conversion unit 83 on the x direction + side from the center column C of the image sensor 8, and from the center column C. The difference between the area of the first photoelectric conversion unit 82 and the area of the second photoelectric conversion unit 83 increases according to the distance. On the x direction − side, the area of the second photoelectric conversion unit 83 is smaller than the area of the first photoelectric conversion unit 82, and the first photoelectric conversion unit 83 and the first photoelectric conversion unit 83 are arranged according to the distance from the center column C. The difference from the area of the photoelectric conversion unit 82 increases. Also in this case, the area of the first photoelectric conversion unit 82 and the area of the second photoelectric conversion unit 83 are equal in the imaging pixels 80 arranged in the center column C of the imaging element 8 in each row.

(2) In FIG. 6, the photographing lens system 1 is any of the photographing lens system 1 whose exit pupil distance PO1 is longer than the exit pupil distance PO2 and the photographing lens system 1 whose exit pupil distance PO1 is shorter than the exit pupil distance PO2. An example of the arrangement of the image pickup pixels 80 of the image pickup device 8 in the case of corresponding to each other is also shown. In this case, a row in which the imaging pixels 80 having the structure shown in FIG. 3A are arranged (rows D2, D4, and D6 in FIG. 6) and a row in which the imaging pixels 80 having the structure shown in FIG. Rows D1, D3, D5) in FIG. 6 are alternately arranged along the y direction. Therefore, in the case of the taking lens system 1 in which the exit pupil distance PO1 is longer than the exit pupil distance PO2, the imaging signals output from the imaging pixels 80 arranged in the rows D2, D4, and D6 are used, and the exit pupil distance PO1. In the case of the taking lens system 1 shorter than the exit pupil distance PO2, by using the image pickup signal output from the image pickup pixels 80 arranged in the rows D1, D3, D5, focus detection with reduced influence of vignetting Can be performed.

(3) Instead of the first photoelectric conversion unit 82 and the second photoelectric conversion unit 83 included in the imaging pixel 80 being arranged side by side in the x direction, the first photoelectric conversion unit 82 and the second photoelectric conversion unit What is arranged side by side in the y direction is also included in one embodiment of the present invention. The imaging element 8 includes an imaging pixel 80 in which a first photoelectric conversion unit 82 and a second photoelectric conversion unit 83 are arranged in the x direction, and a first photoelectric conversion unit 82 and a second photoelectric conversion unit 83. An arrangement in which the imaging pixels 80 arranged in the y direction are arranged is also included in one embodiment of the present invention.

(4) As shown in FIG. 7, the image sensor 8 in which the first photoelectric conversion unit 82 is arranged in one of the pair of imaging pixels 80 and the second photoelectric conversion unit 83 is arranged in the other imaging pixel 80 is also present. It is included in one aspect of the invention. In this case, in the pair of imaging pixels 80a1 and 80a2 arranged in the center column C of the imaging element 8, the second photoelectric conversion unit 83a included in the imaging pixel 80a1 and the first photoelectric conversion unit 82a included in the imaging pixel 80a2 , The area is substantially equal. In the pair of imaging pixels 80c1 and 80c2 arranged in the peripheral portion of the imaging element 8 (x direction + side in FIG. 7), the imaging pixel 80c2 has an area of the second photoelectric conversion unit 83c included in the imaging pixel 80c1. It is larger than the area of the first photoelectric conversion unit 82c. The area difference is determined according to the distance from the center row C of the image sensor 8 as in the case of the embodiment. Therefore, even when the imaging device 8 is configured by the imaging pixel 80 having the configuration shown in FIG. 7, it is possible to reduce the influence of vignetting on the peripheral portion of the imaging device 8 and maintain the incident light amount. Therefore, it is possible to suppress a decrease in focus detection accuracy.

  As long as the characteristics of the present invention are not impaired, the present invention is not limited to the above-described embodiments, and other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention. .

8 ... Image sensor, 13 ... Image processing circuit, 14 ... Focus detection arithmetic circuit,
80 ... Imaging pixels, 81 ... Microlens, 82 ... First photoelectric conversion unit,
83: Second photoelectric conversion unit, 100: Digital camera

Claims (10)

A plurality of microlenses, and a pair of photoelectric conversion units that are provided for each of the plurality of microlenses and receive a pair of light beams that have passed through a pair of pupil regions, and are arranged in a two-dimensional manner With multiple pixels,
In the plurality of pixels, the total area of the pair of photoelectric conversion units is substantially equal,
An image sensor in which the areas of the pair of photoelectric conversion units are different depending on the arrangement position of the plurality of pixels. The imaging device according to claim 1,
An imaging device in which an area difference between the pair of photoelectric conversion units increases as the distance from the center of the array position increases. The image sensor according to claim 1 or 2,
When the distance along the first direction in the arrangement direction of the pair of photoelectric conversion units increases from the vicinity of the center of the array position, an area difference between the other photoelectric conversion unit with respect to one photoelectric conversion unit increases, and the center of the array position The imaging device in which an area difference between the one photoelectric conversion unit with respect to the other photoelectric conversion unit is increased when a distance along a second direction opposite to the first direction is increased from the vicinity. The imaging device according to any one of claims 1 to 3,
Among the plurality of pixels arranged in the two-dimensional shape, the pair of photoelectric conversion units in one pixel row extends from the vicinity of the center of the arrangement position along a first direction in the arrangement direction of the pair of photoelectric conversion units. As the distance increases, the area difference between the other photoelectric conversion unit with respect to one photoelectric conversion unit increases, and the distance along the second direction, which is opposite to the first direction, increases from the vicinity of the center of the array position. , An area difference of the one photoelectric conversion unit with respect to the other photoelectric conversion unit is increased,
When the distance along the first direction in the arrangement direction of the pair of photoelectric conversion units increases from the vicinity of the center of the arrangement position, the pair of photoelectric conversion units in the other pixel rows is compared with the other photoelectric conversion unit. When the area difference of one photoelectric conversion unit increases and the distance along the second direction from the vicinity of the center of the arrangement position increases, the area difference of the other photoelectric conversion unit with respect to the one photoelectric conversion unit increases. ,
An image sensor in which the one pixel row and the other pixel row are alternately arranged. The imaging device according to any one of claims 1 to 4,
In the pair of photoelectric conversion units, the length in the direction along the arrangement direction changes according to the distance from the vicinity of the center of the arrangement position, and the length along the direction orthogonal to the arrangement direction from the vicinity of the center. An image sensor that is constant regardless of the distance. In the imaging device according to any one of claims 1 to 5,
The image sensor, wherein the difference in area between the pair of photoelectric conversion units linearly changes in accordance with a distance from the vicinity of the center of the arrangement position. A plurality of microlenses and a plurality of pixels arranged in a two-dimensional manner provided for each of the plurality of microlenses,
The plurality of pixels include a first pixel having a photoelectric conversion unit that receives one of a pair of light beams that have passed through a pair of pupil regions, and a photoelectric conversion unit that receives the other of the pair of light beams that have passed through the pair of pupil regions. Are alternately arranged with second pixels having
The sum of the areas of the photoelectric conversion unit of the first pixel that receives one of the pair of light beams and the photoelectric conversion unit of the second pixel that receives the other of the pair of light beams is substantially equal,
An image sensor in which an area of the photoelectric conversion unit of the first pixel and an area of the photoelectric conversion unit of the second pixel are different from each other in accordance with an arrangement position of the plurality of pixels. The image pickup device according to claim 7,
The imaging device in which an area difference between the photoelectric conversion unit of the first pixel and the photoelectric conversion unit of the second pixel increases as the distance from the center of the arrangement position increases. The imaging device according to any one of claims 1 to 8,
A focus detection apparatus comprising: detection means for detecting a focus state of a subject using signals output from a pair of photoelectric conversion units. The imaging device according to any one of claims 1 to 8,
Detecting means for detecting a focus state of a subject using signals output from a pair of photoelectric conversion units;
An image pickup apparatus comprising: an image generation unit that generates an image signal by adding signals output from the pair of photoelectric conversion units.

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