Image pickup element and image pickup device

Abstract

To suppress reduction in focus detection accuracy when an exchangeable lens with a different exit pupil position is attached.SOLUTION: An imaging element comprises: a plurality of first pixels each of which has a first photoelectric conversion part that performs photoelectric conversion of light transmitted through an optical system and a first light shading part provided at a first interval from the first photoelectric conversion part to block a part of light entering the first photoelectric conversion part, each first pixel outputting a signal used for focus detection based on the photoelectric conversion at the first photoelectric conversion part; a plurality of second pixels each of which has a second photoelectric conversion part that performs photoelectric conversion of light transmitted through the optical system to generate electric charges and a second light shading part provided at a second interval different from the first interval from the second photoelectric conversion part to block a part of light entering the second photoelectric conversion part, each second pixel outputting a signal used for focus detection based on the photoelectric conversion at the second photoelectric conversion part; and an output part that outputs at least one of a signal outputted from the plurality of the first pixels and a signal outputted from and the plurality of the second pixels, on the basis of at least one information of a distance from an optical axis of the optical system and a depth of field.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an image pickup device and an imaging device Regarding. [Background technology]

[0002] Conventionally, there has been known an image sensor in which the distance between a microlens and a light blocking portion is varied according to the position of a focus detection pixel of a pupil division method on an imaging surface (for example, Patent Document 1). However, the technology of Patent Document 1 has a problem that the accuracy of focus detection decreases when an interchangeable lens with a different exit pupil position is attached. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japan Patent Publication No. 2012-43939 Summary of the Invention

[0004] According to a first aspect, an image sensor includes a first photoelectric conversion unit that photoelectrically converts light transmitted through an optical system, and a first light-shielding unit that blocks a portion of the light incident on the first photoelectric conversion unit, and a plurality of first pixels that output signals used for focus detection based on photoelectric conversion in the first photoelectric conversion unit, a second photoelectric conversion unit that photoelectrically converts light transmitted through the optical system to generate electric charges, a plurality of second pixels that have a second light-shielding unit that blocks a portion of the light incident on the second photoelectric conversion unit and has an area different from that of the first light-shielding unit, and output signals used for focus detection based on photoelectric conversion in the second photoelectric conversion unit, and an output unit that outputs signals output from the plurality of first pixels and signals output from the plurality of second pixels, and among the signals output from the plurality of first pixels and the signals output from the plurality of second pixels, a signal of a pixel selected based on information on a distance between an optical axis of the optical system and the first pixels and a distance between the optical axis of the optical system and the second pixels is used for focus detection. an area of ​​the first light-shielding portion included in at least two of the plurality of first pixels varies depending on a position on the imaging surface; an area of ​​the second light-shielding portion included in at least two of the plurality of second pixels varies depending on a position on the imaging surface; an area of ​​the first light-shielding portion included in the first pixel located near a center of the imaging surface among the plurality of first pixels is smaller than an area of ​​the first light-shielding portion included in the first pixel located near an edge of the imaging surface; and an area of ​​the second light-shielding portion included in the second pixel located near the center of the imaging surface among the plurality of second pixels is smaller than an area of ​​the second light-shielding portion included in the second pixel located near the edge of the imaging surface. . According to a second aspect, an image sensor includes a first photoelectric conversion unit that performs photoelectric conversion on light transmitted through an optical system, and a first light shielding unit that blocks a portion of light incident on the first photoelectric conversion unit, and includes a plurality of first pixels that output signals used for focus detection based on photoelectric conversion in the first photoelectric conversion unit, a second photoelectric conversion unit that performs photoelectric conversion on light transmitted through the optical system to generate electric charges, a plurality of second pixels that have a second light shielding unit that blocks a portion of light incident on the second photoelectric conversion unit and has an area different from that of the first light shielding unit, and output signals used for focus detection based on photoelectric conversion in the second photoelectric conversion unit, and an output unit that outputs signals output from the plurality of first pixels and signals output from the plurality of second pixels, and a signal of a pixel selected based on information on a distance between an optical axis of the optical system and the first pixels and a distance between the optical axis of the optical system and the second pixels is used for focus detection, and the number of the first pixels is different from the number of the second pixels. No. 3According to this aspect, an imaging device includes the imaging element according to the first aspect, The above signals output from a plurality of the first pixels; and The above and a control unit that controls a position of the optical system to a focusing position where an image formed by the optical system is focused on the imaging element based on at least one of the signals output from the second pixels. [Brief description of the drawings]

[0005] [Figure 1] 1 is a cross-sectional view illustrating a configuration of an imaging device according to an embodiment. [Diagram 2] 1 is a block diagram illustrating a configuration of a main part of an imaging device according to an embodiment. [Diagram 3] 4 is a diagram showing an example of an arrangement of imaging pixels and focus detection pixels of an image sensor according to an embodiment. FIG. [Figure 4] 3 is a cross-sectional view illustrating an example of the structure of an imaging pixel and a focus detection pixel. FIG. [Diagram 5] 11 is a diagram showing positions where light blocking portions of focus detection pixels are projected by microlenses. [Figure 6] 4A and 4B are diagrams illustrating the relationship between a light beam incident on a focus detection pixel and an exit pupil region of an imaging optical system according to an embodiment. [Figure 7] 13A and 13B are diagrams illustrating an example of a light blocking portion of a focus detection pixel in a modified example. [Figure 8] FIG. 11 is a cross-sectional view illustrating an example of the structure of a focus detection pixel in another example. [Figure 9] FIG. 11 is a cross-sectional view illustrating an example of the structure of a focus detection pixel in another example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] An image sensor according to an embodiment of the present invention, and a focus detection device and an image sensor including the image sensor will be described with reference to the drawings. 1 is a cross-sectional view for explaining the configuration of a digital camera 100, which is an image capturing apparatus according to this embodiment. For convenience of explanation, a coordinate system consisting of x, y, and z axes is set as shown in the figure.

[0007] Digital camera 100 is a so-called mirrorless camera that is composed of a camera body 200 and a photographing lens body 300, and photographing lens body 300 is attached via a mount section (not shown). Photographing lens body 300 having various photographing optical systems can be attached to camera body 200 via the mount section. Electrical contacts 201 and 202 are provided on the mount section, and when camera body 200 and photographing lens body 300 are coupled, electrical connection is established via electrical contacts 201 and 202.

[0008] The photographing lens body 300 includes a photographing optical system 1, a drive mechanism 3, and a lens data unit 4. The photographing optical system 1 is an optical system for forming a subject image on the imaging surface of an image sensor 8, and is composed of multiple lenses including a focus adjustment lens. The drive mechanism 3 calculates the lens drive amount using the defocus amount input from the camera body 200 side via an electrical contact 201, and drives the focus adjustment lens that constitutes the photographing optical system 1 to a focus position along the direction of the optical axis L (z-axis direction) in accordance with the lens drive amount.

[0009] The lens data section 4 is configured, for example, by a non-volatile recording medium, and stores various lens information related to the photographing lens body 300, such as the position of the exit pupil of the photographing optical system 1. The lens data section 4 transmits the above lens information and the like between the camera body 200 and the lens data section 4 via the electrical contacts 202.

[0010] Inside the camera body 200, there are provided a control unit 5, an image sensor drive circuit 6, an image sensor 8, an electronic viewfinder (EVF) 9, and an eyepiece lens 10. The camera body 200 is provided with an operation unit 11. The image sensor 8 has image pixels such as CCD or CMOS and focus detection pixels arranged two-dimensionally (rows and columns) on the xy plane. The image pixels receive a light beam that has passed through the entire exit pupil region of the photographing optical system 1, and output an image signal to the control unit 5. The focus detection pixels receive a light beam that has passed through a part of the exit pupil region, such as the left and right or the top and bottom of the photographing optical system 1, and output a focus detection signal to the control unit 5. The image pixels of the image sensor 8 are provided with R (red), G (green), and B (blue) color filters, respectively. Since the image sensors capture the subject image through the color filters, the image signal has color information in the RGB color system. Note that the focus detection pixels may not be provided with color filters, and all focus detection pixels may be provided with the same color filter (for example, G). The image pickup element 8 will be described in detail later.

[0011] The electronic viewfinder 9 displays an image corresponding to the display image data generated by the control unit 5. The electronic viewfinder 9 also displays various information related to shooting conditions (shutter speed, aperture value, ISO sensitivity, etc.). The image and various information displayed on the electronic viewfinder 9 are observed by the user through an eyepiece 10. The image and various information may also be displayed on a rear monitor (not shown).

[0012] The operation unit 11 includes various switches provided in correspondence with various operation members operated by the user, and outputs operation signals corresponding to the operation of the operation members to the control unit 5. The operation members include, for example, a release button, a menu button for displaying a menu screen on a rear monitor (not shown) provided on the rear of the camera body 200, a cross key operated when selecting various settings, etc., a confirmation button for confirming settings, etc. selected by the cross key, an operation mode switching button for switching the operation of the digital camera 100 between a shooting mode and a playback mode, an exposure mode switching button for setting the exposure mode, etc.

[0013] Further, the control system of the digital camera 100 will be described with reference to the block diagram shown in FIG. 2. As shown in FIG. 2, the digital camera 100 has an A / D conversion unit 12, an image processing circuit 13, a focus detection calculation circuit 14, a body-lens communication unit 15, and a storage unit 16. The control unit 5 is a calculation circuit having a CPU, a ROM, a RAM, etc., and 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 non-volatile memory (not shown) in the control unit 5. The control unit 5 has a selection unit 51 as a function, and selects a focus detection pixel that outputs a focus detection signal used for focus detection calculation from among the focus detection pixels of the image sensor 8 according to the attached photographing lens body 300. The selection unit 51 will be described in detail later. The image sensor drive circuit 6 is controlled by the control unit 5, and controls the drive of the image sensor 8 and the A / D conversion unit 12 to cause the image sensor 8 to accumulate electric charges and read out an image signal. The A / D converter 12 converts the analog image signal output from the image sensor 8 into a digital signal.

[0014] The image processing circuit 13 uses the imaging signals output from the imaging pixels of the imaging element 8 as image signals, performs various image processes on the image signals to generate image data, and then adds additional information and the like to generate an image file. 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 or a rear monitor (not shown) based on the generated image data and image data recorded on the recording medium.

[0015] The focus detection calculation circuit 14 calculates the defocus amount by a known phase difference detection method using the focus detection signals output from the focus detection pixels of the image sensor 8. The body-lens communication unit 15 is controlled by the control unit 5 and communicates with the drive mechanism 3 and the lens data unit 4 in the photographing lens body 300 via electrical contacts 201 and 202, transmitting camera information (defocus amount, aperture value, etc.) and receiving lens information (exit pupil position, etc.). The storage unit 16 is, for example, a non-volatile storage medium, and stores programs for the control unit 5 to execute various processes, data for the control unit 5 to execute various processes, and the like.

[0016] Next, the imaging element 8 in this embodiment will be described in detail. Fig. 3(a) is a diagram showing a schematic diagram of an imaging surface 800 of an image sensor 8. In Fig. 3, a coordinate system consisting of an x-axis, a y-axis, and a z-axis is set in the same manner as in the example shown in Fig. 1. The imaging surface 800 is provided with focus detection areas 810 for acquiring focus detection signals used to calculate a defocus amount. In the diagram, an example in which nine focus detection areas 810 are provided is shown, but the number of focus detection areas 810 is not limited to this.

[0017] FIG. 3B is a schematic diagram showing an enlarged portion of a focus detection area 810a provided in the peripheral portion of the imaging surface 800 on the positive side of the X axis among the multiple focus detection areas 810. The focus detection area 810a has a first pixel group 851, a second pixel group 852, and a third pixel group 853 (collectively referred to as pixel group 850). Note that FIG. 3B shows an example in which the pixel group 850 has three rows, but the pixel group is not limited to three rows. Also, the arrangement order of the first pixel group 851, the second pixel group 852, and the third pixel group 853 along the Y axis direction is not limited to the example shown in FIG. 3B, and may be arranged in any order. Also, the differences between the first pixel group 851, the second pixel group 852, and the third pixel group 853 will be described later.

[0018] In the pixel group 850, the imaging pixels 80 and the focus detection pixels 81, 82 are alternately provided along the X-axis direction, i.e., the imaging pixels 80 are provided between the multiple focus detection pixels 81. That is, the pixel group 850 is provided along the X-axis direction. The first pixel group 851, the second pixel group 852, and the third pixel group 853 are provided in the Y-axis direction. The imaging pixels 80 are provided between the first pixel group 851 and the second pixel group 852 and between the second pixel group 852 and the third pixel group 853 in the Y-axis direction.

[0019] In this embodiment, the first pixel group 851, the second pixel group 852, and the third pixel group 853 are configured so that the positions of the exit pupils of the photographing optical system 1 at which the focus detection pixels 81, 82 included in each of them can output focus detection signals are different. For this reason, the positions of the light-shielding parts in the first pixel group 851, the second pixel group 852, and the third pixel group 853 are different from each other. Below, the structures of the imaging pixels 80 and the focus detection pixels 81, 82 included in the first pixel group 851, the second pixel group 852, and the third pixel group 853 will be described.

[0020] Fig. 4(a) is a cross-sectional view showing a schematic structure of an imaging pixel 80 and focus detection pixels 81, 82 in a first pixel group 851, Fig. 4(b) is a cross-sectional view showing a schematic structure of an imaging pixel 80 and focus detection pixels 81, 82 in a second pixel group 852, and Fig. 4(c) is a cross-sectional view showing a schematic structure of an imaging pixel 80 and focus detection pixels 81, 82 in a third pixel group 853. In Fig. 4, a coordinate system consisting of x-axis, y-axis, and z-axis is set in the same manner as in the examples shown in Figs. 1 and 3.

[0021] -1st pixel group 851- The focus detection pixel 81 of the first pixel group 851 has a microlens 811, a photoelectric conversion unit 812 provided below the microlens 811, and a light shielding unit 813. The light shielding unit 813 is provided between the microlens 811 and the photoelectric conversion unit 812. A light beam from the imaging optical system 1 passes through the microlens 811, and then enters the photoelectric conversion unit 812 with a portion of the light being shielded (restricted) by the light shielding unit 813.

[0022] The light shielding portion 813 is formed of a circuit wiring of the focus detection pixel 81 manufactured using a conductive member such as aluminum. The light shielding portion 813 limits a light flux directed toward the + side of the X axis of the focus detection pixel 81. The light shielding portion 813 has a first light shielding portion 813a, a second light shielding portion 813b, and a third light shielding portion 813c, each of which is at a different distance from the microlens 811. In this embodiment, the distance between the microlens 811 and the second light shielding portion 813b is greater than the distance between the microlens 811 and the first light shielding portion 813a. The distance between the microlens 811 and the third light shielding portion 813c is greater than the distance between the microlens 811 and the second light shielding portion 813b.

[0023] In the focus detection pixel 81 of the first pixel group 851, the area of ​​the third light-shielding portion 813c on a surface parallel to the XY plane (i.e., the light-shielding area) is larger than the light-shielding area of ​​the first light-shielding portion 813a and the light-shielding area of ​​the second light-shielding portion 813b. In other words, in the focus detection pixel 81, the light flux is limited by the third light-shielding portion 813c, which is farthest from the microlens 811.

[0024] The focus detection pixel 82 of the first pixel group 851 has a microlens 821, a photoelectric conversion unit 822 provided below the microlens 821, and a light shielding unit 823. The microlens 821 has the same focal length as the microlens 811 of the focus detection pixel 81. The distance between the photoelectric conversion unit 822 and the microlens 821 is equal to the distance between the photoelectric conversion unit 812 and the microlens 811 of the focus detection pixel 81. The light shielding unit 823 is provided between the microlens 821 and the photoelectric conversion unit 822. After a light beam from the imaging optical system 1 passes through the microlens 821, a portion of the light is shielded (restricted) by the light shielding unit 823 and enters the photoelectric conversion unit 822.

[0025] The light shielding portion 823 is formed of a circuit wiring of the focus detection pixel 82 manufactured using a conductive member such as aluminum. The light shielding portion 823 limits a light flux directed toward the negative side of the X axis of the focus detection pixel 82. The light shielding portion 823 has a first light shielding portion 823a, a second light shielding portion 823b, and a third light shielding portion 823c, each of which has a different distance from the microlens 821. In this embodiment, the distance between the microlens 821 and the second light shielding portion 823b is greater than the distance between the microlens 821 and the first light shielding portion 823a. The distance between the microlens 821 and the third light shielding portion 823c is greater than the distance between the microlens 821 and the second light shielding portion 823b. The distance between the third light shielding portion 823c and the microlens 821 is equal to the distance between the third light shielding portion 813c and the microlens 811 of the focus detection pixel 81.

[0026] Also in the focus detection pixel 82, the area of ​​the third light-shielding portion 823c on a surface parallel to the XY plane (i.e., the light-shielding area) is larger than the light-shielding area of ​​the first light-shielding portion 823a and the light-shielding area of ​​the second light-shielding portion 823b. In other words, in the focus detection pixel 81, the light flux is limited by the third light-shielding portion 823c, which is farthest from the microlens 821.

[0027] In the first pixel group 851, the focus detection pixels 81, 82 have the above-mentioned structure, and therefore the third light-shielding portions 813c, 823c that are equidistant from the microlenses 811, 821 restrict light beams from different regions of the photographing optical system 1. That is, light beams from different regions of the photographing optical system are incident on the photoelectric conversion portions 812, 822 of the focus detection pixels 81, 82 of the first pixel group 851, and a pair of subject light beams that are used by the focus detection calculation circuit 14 for phase difference detection calculation are incident thereon.

[0028] The imaging pixel 80 has a microlens 801 and a photoelectric conversion unit 802 provided under one of the microlenses 801. A light beam that has passed through the entire area of ​​the imaging optical system 1 is incident on the photoelectric conversion unit 802 via the microlens 801. The imaging pixel 80 has the same structure whether it is provided in the second pixel group 852 or in the third pixel group 853. Furthermore, the imaging pixel 80 provided outside each pixel group 850 also has the same structure.

[0029] -Second pixel group 852- The focus detection pixels 81, 82 in the second pixel group 852 will be described mainly with respect to the differences from the focus detection pixels 81, 82 in the first pixel group 851. Points that are not particularly described are similar to the focus detection pixels 81, 82 in the first pixel group 851. In the focus detection pixel 81 in the second pixel group 852, the light-shielding area of ​​the second light-shielding portion 813b on a surface parallel to the XY plane is larger than the light-shielding area of ​​the first light-shielding portion 813a and the light-shielding area of ​​the third light-shielding portion 813c. In other words, in the focus detection pixel 81, the second light-shielding portion 813b provided between the first light-shielding portion 813a and the third light-shielding portion 813c as viewed from the microlens 821 restricts the incidence of the light flux to the +X-axis side.

[0030] In the focus detection pixel 82 of the second pixel group 852, the light shielding area of ​​the second light shielding portion 823b on a surface parallel to the XY plane is larger than the light shielding area of ​​the first light shielding portion 823a and the light shielding area of ​​the third light shielding portion 823c. In other words, in the focus detection pixel 82, the second light shielding portion 823b provided between the first light shielding portion 823a and the third light shielding portion 823c as viewed from the microlens 821 limits the incidence of the light beam on the negative side of the X axis. In the second pixel group 852, the focus detection pixels 81 and 82 have the above-mentioned structure, so that the second light shielding portions 813b and 823b, which are at the same distance from the microlenses 811 and 821, limit the light beams from different regions of the photographing optical system 1. That is, light beams from different regions of the photographing optical system are incident on the photoelectric conversion units 812, 822 of the focus detection pixels 81, 82 of the second pixel group 852, and a pair of subject light beams that are used by the focus detection calculation circuit 14 for phase difference detection calculation are incident thereon.

[0031] -Third pixel group 853- The focus detection pixels 81, 82 in the third pixel group 853 will be described mainly with respect to the differences from the focus detection pixels 81, 82 in the first pixel group 851. Points that are not particularly described are similar to the focus detection pixels 81, 82 in the first pixel group 851. In the focus detection pixel 81 in the third pixel group 853, the light-shielding area of ​​the first light-shielding portion 813a on a surface parallel to the XY plane is larger than the light-shielding area of ​​the second light-shielding portion 813b and the light-shielding area of ​​the third light-shielding portion 813c. In other words, in the focus detection pixel 81, the first light-shielding portion 813a, which is the closest to the microlens 821, restricts the incidence of the light flux to the + side of the X axis.

[0032] In the focus detection pixel 82 of the third pixel group 853, the light shielding area of ​​the first light shielding portion 823a on a surface parallel to the XY plane is larger than the light shielding area of ​​the second light shielding portion 823b and the light shielding area of ​​the third light shielding portion 823c. In other words, in the focus detection pixel 82, the first light shielding portion 823a, which is the shortest distance from the microlens 821, restricts the incidence of the light beam to the negative side of the X axis. In the third pixel group 853, the focus detection pixels 81 and 82 have the above-mentioned structure, so that the first light shielding portions 813a and 823a, which are the same distance from the microlenses 811 and 821, restrict the light beams from different regions of the photographing optical system 1. That is, the light beams from different regions of the photographing optical system are incident on the photoelectric conversion portions 812 and 822 of the focus detection pixels 81 and 82 of the third pixel group 853, and a pair of subject light beams used by the focus detection calculation circuit 14 for phase difference detection calculation are incident thereon.

[0033] As described above, the positions (distance from the microlenses 811, 821) of the light shielding portions 813, 823 for restricting the light flux of the focus detection pixels 81, 82 differ between the first pixel group 851, the second pixel group 852, and the third pixel group 853.

[0034] FIG. 5 shows a schematic diagram of the relationship between the positions where the pupils at different exit pupil positions PO1, PO2, and PO3 of the imaging optical system 1 are projected by the microlens 811 and the position of the light blocking portion 813 in the Z-axis direction. As shown in FIG. 5A, the pupil at the exit pupil position PO1 of the photographing optical system 1 is projected by the microlens 811 onto the third light-shielding portion 813c of the focus detection pixel 81 of the first pixel group 851. That is, the third light-shielding portion 813c is provided at a position where the pupil at the exit pupil position PO1 is projected onto the microlens 811. As shown in FIG. 5B, the pupil at the exit pupil position PO2 of the photographing optical system 1 is projected by the microlens 811 onto the second light-shielding portion 813b of the focus detection pixel 81 of the second pixel group 852. That is, the second light-shielding portion 813b is provided at a position where the pupil at the exit pupil position PO2 is projected by the microlens 811. As shown in FIG. 5C, the pupil at the exit pupil position PO3 of the photographing optical system 1 is projected by the microlens 811 onto the first light-shielding portion 813a of the focus detection pixel 81 of the third pixel group 853. That is, the first light-shielding portion 813a is provided at a position where the pupil at the exit pupil position PO3 is projected by the microlens 811. Note that in Figures 5(a) to 5(c), the third light-shielding portion 813c, the second light-shielding portion 813b, and the first light-shielding portion 813a are shown as representatives, respectively. Also, since the focus detection pixel 82 has the same structure as the focus detection pixel 81 and is axially symmetrical, the projection position of the light-shielding portion 823 of the focus detection pixel 82 has the same relationship as the light-shielding portion 813 of the focus detection pixel 81. The positions where the pupils at different exit pupil positions PO1, PO2, PO3 are projected by the microlens 811 differ for each pixel group 850. As a result, the photographing optical system 1 having exit pupil positions suitable for the focus detection pixels to be used during focus detection differs between the first pixel group 851, the second pixel group 852, and the third pixel group 853.

[0035] Fig. 6 shows a schematic relationship between the photoelectric conversion units 812, 822 of the focus detection pixels 81, 82 included in a partial area of ​​the second pixel group 852 and the position of the exit pupil 940 of the photographing optical system 1. Fig. 6(a) shows a case where a photographing lens body 300 is attached in which the projection position of the pupil at the exit pupil position PO2 of the photographing optical system 1 is substantially equal to the second light-shielding units 813b, 823b of the focus detection pixels 81, 82 of the second pixel group 852. In other words, the case where the exit pupil position PO2 of the photographing optical system 1 and the second light-shielding units 813b, 823b are conjugate with the microlenses 811, 821 is shown.

[0036] The photoelectric conversion unit 812 of the focus detection pixel 81 receives, through the microlens 811, a light beam 951 that has passed through the exit pupil region 941a of the pair of exit pupil regions 941a and 942a of the photographing optical system 1, among the light beams from the subject. In other words, the light beam from the exit pupil region 942a is blocked by the second light blocking portion 813b. The photoelectric conversion unit 822 of the focus detection pixel 82 receives, through the microlens 821, a light beam 952 that has passed through the exit pupil region 942a of the photographing optical system 1, among the light beams from the subject. In other words, the light beam from the exit pupil region 941a is blocked by the second light blocking portion 823b. As shown in FIG. 6A, the light beams 951 and 952 enter the photoelectric conversion units 812 and 822, respectively, without or with little vignetting due to the structure of the photographing lens body 300 or the like.

[0037] Fig. 6(b) shows a case where a photographing lens body 300 having a photographing optical system 1 with an exit pupil position PO3 that is longer than the photographing lens body 300 with the exit pupil position PO2 is attached. In this case, the second light-shielding portions 813b, 823b of the focus detection pixels 81, 82 block light that has passed through a portion (area) different from the exit pupil regions 941a, 942a that are part of the region of the exit pupil 940 of the photographing optical system 1 described above. Note that in Fig. 6(b), for the purpose of facilitating understanding, the exit pupil 940 of the photographing optical system 1 having the exit pupil position PO2 is indicated by a dashed line.

[0038] A light beam 952 from the subject passes through the exit pupil region 942b of the photographing optical system 1 and enters the photoelectric conversion unit 822 via the microlens 821 of the focus detection pixel 82. Since the exit pupil position PO3 of the photographing optical system 1 is longer than the exit pupil position PO2, a part of the light beam 951 from the subject is vignetted. That is, of the light beam 951, a light beam 951a passes through the exit pupil region 941b of the photographing optical system 1 and enters the photoelectric conversion unit 812 via the microlens 811, and a light beam 951b is vignetted and does not enter the photoelectric conversion unit 812. Therefore, the light amount of the light beam entering each of the photoelectric conversion units 812 and 822 differs between the focus detection pixels 81 and 82, and the output of the focus detection signal from the photoelectric conversion unit 812 is lower than the output of the focus detection signal from the photoelectric conversion unit 822. In other words, if the focus detection pixels 81 of the second light blocking portion 813b are used for the photographing optical system 1 with the exit pupil position PO3, the calculation accuracy of the focus detection calculation will decrease.

[0039] When the photographing optical system 1 has an exit pupil position PO3, light beams from exit pupil regions 941b, 942b are made incident on focus detection pixels 81, 82 having first light-shielding portions 813a, 823a provided at positions where the pupils at the exit pupil position PO3 are projected by the microlenses 811, 821. As shown in Fig. 6C, in a third pixel group 853 provided with focus detection pixels 81, 82 that limit light beams with the first light-shielding portions 813a, 823a that are the shortest distance from the microlenses 811, 821, light beams are made incident on the focus detection pixels 81, 82 with no or little vignetting as shown in Fig. 5B.

[0040] In addition, when the exit pupil position of the photographing optical system 1 is shorter than PO2, for example, the light beam from the exit pupil region is made incident on the focus detection pixels 81, 82 having the third light shielding portions 813c, 823c provided at the position where the pupil at the exit pupil position PO1 is projected by the microlenses 811, 821. That is, the light beam from the exit pupil region is made incident on the focus detection pixels 81, 82 of the first pixel group 851, which limit the light beam by the third light shielding portions 813c, 823c that are the longest distance from the microlenses 811, 821. That is, even when the exit pupil positions of the photographing optical system 1 are different, it is possible to make the light beam that is not affected by vignetting or is less affected by vignetting incident on the photoelectric conversion units 812, 822 in any of the pixel groups 850. As a result, in this embodiment, when the type of photographing lens body 300 is different, or when the photographing lens body 300 is a zoom lens in which the position of the exit pupil of the photographing optical system 1 changes, focus detection is possible using focus detection signals from focus detection pixels 81, 82 that receive a light beam that is less affected by vignetting, etc.

[0041] In addition, in a focus detection area 810b (see FIG. 3(a)) provided at a position symmetrical to the focus detection area 810a with respect to the center of the imaging surface 800, the focus detection pixels 81, 82 of each pixel group 850 are different from the focus detection pixels 81, 82 in the focus detection area 810a. In this case, in the focus detection area 810b, the focus detection pixel 82 is provided at a position symmetrical to the focus detection pixel 81 of the focus detection area 810a with respect to the center of the imaging surface 800. The focus detection pixel 81 is provided at a position symmetrical to the focus detection pixel 82 of the focus detection area 810a with respect to the center of the imaging surface 800.

[0042] In each pixel group 850 provided in the focus detection area 810a, the focus detection pixels 81, 82 provided at the end on the negative side of the X axis are affected differently by the oblique incidence of the light flux that has passed through the photographing optical system 1, from the focus detection pixels 81, 82 provided at the end on the positive side of the X axis. For this reason, the light-blocking area of ​​the light-blocking portions 813, 823 of the focus detection pixels 81, 82 provided at the end on the positive side of the X axis needs to be larger along the X axis direction than the light-blocking area of ​​the light-blocking portions 813, 823 of the focus detection pixels 81, 82 provided at the end on the negative side of the X axis. The increase in the light-blocking area can be determined by multiplying the distance of the focus detection pixels 81, 82 from the center of the imaging surface 800, i.e., the image height, by a predetermined coefficient. In this case, the light-shielding area of ​​the light-shielding portions 813, 823 may be increased linearly in the X-axis direction as the position of the pixel group 850 increases in the +X-axis direction, or the light-shielding area of ​​the light-shielding portions 813, 823 may be increased stepwise along the X-axis direction for each predetermined number of focus detection pixels 81, 82.

[0043] In each pixel group 850 provided in the focus detection region 810b, the light-blocking areas of the light-blocking portions 813, 823 of the focus detection pixels 81, 82 provided at the ends on the negative side of the X axis are made larger along the X axis direction than the light-blocking areas of the light-blocking portions 813, 823 of the focus detection pixels 81, 82 provided at the ends on the positive side of the X axis. In this case as well, the light-blocking areas of the light-blocking portions 813, 823 may be increased linearly in the X axis direction as the position of the pixel group 850 in the positive X axis direction increases, or the light-blocking areas of the light-blocking portions 813, 823 may be increased stepwise in the X axis direction for each predetermined number of focus detection pixels 81, 82. In other words, the positional relationship in the X-axis direction perpendicular to the optical axis of the microlenses 811, 812 between the light-shielding portions 813, 823 of the focus detection pixels 81, 82 provided at one end of the pixel group 850 in the X-axis direction is different from the positional relationship in the X-axis direction perpendicular to the optical axis of the microlenses 811, 812 between the light-shielding portions 813, 823 of the focus detection pixels 81, 82 provided at the other end and the microlenses 811, 812. In addition, in the focus detection area 810c (see FIG. 3(a)) provided in the center of the imaging surface 800 of the image sensor 8, the light flux is not affected by vignetting, so there is no need to increase the light blocking area of ​​the light blocking portions 813 and 823.

[0044] Furthermore, in a focus detection region 810 provided in the peripheral portion of the imaging surface 800 of the image sensor 8, the pixel groups 850 may be arranged in greater numbers and at higher density than the pixel groups 850 in the focus detection region 810 provided in the center of the imaging surface 800. In this case, the first pixel groups 851 and the third pixel groups 853 can be arranged in greater numbers and more densely than the second pixel groups 852 in the peripheral focus detection region 810. The closer the focus detection region 810 is to the peripheral portion, the greater the numbers of the first pixel groups 851 and the third pixel groups 853 can be, and the more densely they can be arranged.

[0045] Alternatively, the first pixel group 851 in which the focus detection pixels 81, 82 corresponding to the exit pupil position PO3 shown in FIG. 5(c) are provided may be arranged in greater numbers and at higher density than the third pixel group 853 in which the focus detection pixels 81, 82 corresponding to the exit pupil position PO1 shown in FIG. 5(a) are provided. That is, the third pixel group 853 may be arranged in smaller numbers and at lower density than the first pixel group 851. When the photographing lens body 300 has a photographing optical system 1 with a long exit pupil position (for example, a telephoto lens, etc.), the depth of field is shallow, so that a shift in the focus position is easily noticeable. On the other hand, when the photographing lens body 300 has a photographing optical system 1 with a short exit pupil position (for example, a wide-angle lens, etc.), the depth of field is deep, so that a shift in the focus position is not easily noticeable. Therefore, by arranging a large number of first pixel groups 851 corresponding to the exit pupil position PO3 at a high density, it is possible to suppress a decrease in focus detection accuracy even when a lens with a long exit pupil position is attached to the digital camera 100 as the photographing lens 300. Alternatively, a large number of pixel groups 850 each having focus detection pixels 81, 82 corresponding to the exit pupil positions of the photographing optical system 1 of the photographing lens body 300 (e.g., a standard lens, a wide-angle lens, etc.) that is frequently used by the user may be arranged at a high density within the focus detection area 810.

[0046] The focus detection operation of the digital camera 100 equipped with the image sensor 8 having the above configuration will now be described. The photographic lens body 300 is attached to the camera body 200, and an electrical connection is established between the camera body 200 and the photographic lens body 300 by electrical contacts 201, 202 provided on the mount. The body-lens communication unit 15 receives lens information, i.e., information regarding the position of the exit pupil, from the lens data unit 4 of the photographic lens body 300 via the electrical contacts 201, 202.

[0047] The selection unit 51 of the control unit 5 selects a pixel group 850 having focus detection pixels 81, 82 suitable for the photographing optical system 1 included in the attached photographing lens body 300 based on the lens information received from the photographing lens body 300. When the position of the exit pupil of the photographing optical system 1 exceeds a predetermined first threshold, the selection unit 51 selects a third pixel group 853 having focus detection pixels 81, 82 with the smallest distance between the microlenses 811, 821 and the light shielding portions 813, 823. When the position of the exit pupil of the photographing optical system 1 is less than a predetermined second threshold (<first threshold), the selection unit 51 selects a first pixel group 851 having focus detection pixels 81, 82 with the largest distance between the microlenses 811, 821 and the light shielding portions 813, 823. When the position of the exit pupil of the photographing optical system 1 is equal to or greater than the second threshold and less than the first threshold, the selection unit 51 selects a second pixel group 852. That is, the selection unit 51 selects a pixel group 850 that includes the focus detection pixels 81 and 82 that have a range finding pupil position that is small in difference from the exit pupil position of the photographing optical system 1 . In addition, the selection unit 51 can switch and select the number and type of pixel groups 850 in the focus detection area 810 based on the position of the focus detection area 810 on the imaging surface 800 of the image sensor 8 and the position of the exit pupil of the photographing optical system 1. Furthermore, when the photographing lens body 300 is a zoom lens, the position of the exit pupil changes depending on the zoom position. In this case, the selection unit 51 acquires information on the position of the exit pupil corresponding to the set zoom based on the received lens information, and selects the pixel group 850 suitable for the acquired information on the position of the exit pupil as described above. This allows the selection unit 851 to automatically switch the pixel group 850 to be selected based on the set zoom. Information on the position of the exit pupil corresponding to the zoom is stored in advance in the lens data unit 4. Note that information on the position of the exit pupil corresponding to the zoom may be stored in advance in the storage unit 16 of the digital camera 100.

[0048] Furthermore, when focus detection is performed based on the output from a focus detection region 810 (810a in FIG. 3A) near the center of the imaging surface 800 of the image sensor 8, the selection unit 851 may select the focus detection pixels 81 and 82 of the first pixel group 851, the second pixel group 852, and the third pixel group 853. This improves focus detection accuracy, subject tracking performance, and subject discrimination performance. When focus detection is performed based on the output from the focus detection region 810 in the periphery of the imaging surface 800 of the image sensor 8, the selection unit 851 selects only the pixel group 850 having the focus detection pixels 81 and 82 corresponding to the position of the exit pupil of the photographing optical system 1. In the periphery of the imaging surface 800, the outputs from the focus detection pixels 81 and 82 other than the focus detection pixels 81 and 82 corresponding to the position of the exit pupil of the photographing optical system 1 are affected by vignetting and the like. Therefore, the outputs from the focus detection pixels 81 and 82 affected by such vignetting or the like are not used during focus detection, so that a decrease in focus detection accuracy can be prevented.

[0049] The focus detection calculation circuit 14 calculates the defocus amount using a known phase difference detection method using the focus detection signals output from the focus detection pixels 81, 82 of the selected pixel group 850 out of the focus detection signals output from the focus detection pixels 81, 82. The focus detection calculation circuit 14 detects the relative shift amount between a first signal sequence {an} in which the focus detection signals from the photoelectric conversion unit 812 of the focus detection pixel 81 are sequentially arranged, and a second signal sequence {bn} in which the focus detection signals from the photoelectric conversion unit 822 of the focus detection pixel 82 are sequentially arranged, and detects the focus adjustment state of the photographing optical system 1, i.e., the defocus amount. In other words, the selection unit 851 selects the focus detection pixels 81, 82 as described above, and the focus detection calculation circuit 14 detects the position at which the image generated by the photographing optical system 1 is focused on the image sensor 8 based on at least one of the outputs from the focus detection pixels 81, 82 of the first pixel group 851, the outputs from the focus detection pixels 81, 82 of the second pixel group 852, and the outputs from the focus detection pixels 81, 82 of the third pixel group 853.

[0050] According to the above-described embodiment, the following advantageous effects can be obtained. (1) In each pixel group 850, focus detection pixels 81, 82 are provided along the X-axis direction to receive light beams that have passed through a portion of the pupil region of the photographing optical system 1. Third light-shielding portions 813c, 823c of the focus detection pixels 81, 82 of the first pixel group 851 are provided between the microlenses 811, 822 and the photoelectric conversion units 812, 822, and limit the light beams that have passed through a portion of the exit pupil region of the photographing optical system 1. Second light-shielding portions 813b, 823b of the focus detection pixels 81, 82 of the second pixel group 852 are provided between the microlenses 811, 822 and the photoelectric conversion units 812, 822, and limit the light beams that have passed through a portion of the exit pupil region of the photographing optical system 1. The first light-shielding portions 813a, 823a of the focus detection pixels 81, 82 of the third pixel group 853 are provided between the microlenses 811, 822 and the photoelectric conversion portions 812, 822, and limit the light flux that has passed through a part of the pupil region of the photographing optical system 1. The distances between the microlenses 811, 821 of the focus detection pixels 81, 82 of the first pixel group 851 and the third light-shielding portions 813c, 823c, the distances between the microlenses 811, 821 of the focus detection pixels 81, 82 of the second pixel group 852 and the second light-shielding portions 813b, 823b, and the distances between the microlenses 811, 821 of the focus detection pixels 81, 82 of the third pixel group 853 and the first light-shielding portions 813a, 823a are different from one another. Therefore, even if the position of the exit pupil of the photographing optical system 1 is different, the focus detection signals are output from the focus detection pixels 81 and 82 into which a light beam that is less affected by vignetting, etc., is incident, among the pixel groups 850. In other words, it is possible to suppress a decrease in the accuracy of the focus detection calculation.

[0051] (2) The light shielding portions 813 and 823 are circuit wiring, and therefore can be shared with other members to prevent an increase in the number of parts.

[0052] (3) In the focus detection pixels 81, 82 provided in each pixel group 850, the focal lengths of the microlenses 811, 812 are equal, and the distances between the microlenses 811, 821 and the photoelectric conversion units 812, 822 are equal, respectively. As a result, by providing the light blocking units 813, 823 in the focus detection pixels 81, 82 having the same structure, focus detection suitable for the photographing optical system 1 having different exit pupil distances can be performed.

[0053] (4) In each pixel group 850 provided in the peripheral portion of the imaging surface 800 of the image sensor 8, the positional relationship in the Z axis direction between the light-shielding portions 813, 823 and the microlenses 811, 821 of the focus detection pixels 81, 82 provided at one end (X-axis minus side) of the pixel group 850 is different from the positional relationship in the Z axis direction between the light-shielding portions 813, 823 and the microlenses 811, 821 of the focus detection pixels 81, 82 provided at the other end (X-axis plus side). This allows the photoelectric conversion portions 812, 822 to receive light beams that are obliquely incident on the peripheral portion of the imaging surface 800 with little or no effect of vignetting. Also, focus detection is possible in the peripheral portion of the imaging surface 800 of the image sensor 8.

[0054] (5) The focus detection calculation circuit 14 detects the focus state of the photographing optical system 1 using any one of the focus detection signals output from the focus detection pixels 81 and 82 of the first pixel group 851, the focus detection signals output from the focus detection pixels 81 and 82 of the second pixel group, and the focus detection signals output from the focus detection pixels 81 and 82 of the third pixel group 853. A plurality of focus detection areas 810 used for detecting the focus state are provided on the imaging surface 800 of the image sensor 8, and the focus detection area 810 has a pixel group 850. Therefore, even if the position of the exit pupil of the photographing optical system 1 is different, the focus detection calculation can be performed using the focus detection signals from the focus detection pixels 81 and 82 that are less affected by vignetting and the like within the focus detection area 810.

[0055] (6) The selection unit 51 selects one of the first, second, or third pixel groups based on lens information related to the position of the exit pupil of the photographing optical system 1, and the focus detection calculation circuit 14 detects the focus state of the photographing optical system 1 using the focus detection signals output from the focus detection pixels 81, 82 of the pixel group 850 selected by the selection unit 51. Therefore, it is possible to perform focus detection calculation using the focus detection signals from the focus detection pixels 81, 82 that are least affected by vignetting, etc., from among the multiple pixel groups 850.

[0056] In the embodiment described above, the structure of the focus detection pixels 81, 82 has been described with reference to FIG. 4, but the structure of the focus detection pixels 81, 82 is not limited to that shown in FIG. Fig. 8 is a cross-sectional view showing a schematic structure of focus detection pixels 81 and 82 in another example. Fig. 8(a), Fig. 8(b), and Fig. 8(c) respectively show the structures of the imaging pixel 80 and the focus detection pixels 81 and 82 in the first pixel group 851, the second pixel group 852, and the third pixel group 853 (see Fig. 3(b)) in the same manner as Fig. 4(a), Fig. 4(b), and Fig. 4(c). Note that in Fig. 8 as well, a coordinate system consisting of the x-axis, y-axis, and z-axis is set in the same manner as in the examples shown in Figs. 1 and 3.

[0057] In the example shown in FIG. 8, the focus detection pixels 81 and 82 each have one light-shielding portion 813 and 823. In the first pixel group 851 shown in FIG. 8(a), the focus detection pixels 81 and 82 have the third light-shielding portions 813c and 823c similar to those in FIG. 4(a), and do not have the first light-shielding portions 813a and 823a and the second light-shielding portions 813b and 823b shown in FIG. 4(a). That is, the focus detection pixels 81 and 82 in FIG. 8(a) only have the third light-shielding portions 813c and 823c, which have the largest light-shielding areas, among the light-shielding portions 813 and 823 shown in FIG. 4(a). In this case, too, the light beam from the photographing optical system 1 passes through the microlenses 811 and 821, and then enters the photoelectric conversion portions 812 and 822 of the focus detection pixels 81 and 822, with a portion of the light being blocked (restricted) by the third light-shielding portions 813c and 823c.

[0058] In the second pixel group 852 shown in Fig. 8(b), the focus detection pixels 81 and 82 have the second light-shielding portions 813b and 823b similar to those in Fig. 4(b), and do not have the first light-shielding portions 813a and 823a and the third light-shielding portions 813c and 823c shown in Fig. 4(b). That is, the focus detection pixels 81 and 82 in Fig. 8(b) only have the second light-shielding portions 813b and 823b, which have the largest light-shielding areas, among the light-shielding portions 813 and 823 shown in Fig. 4(b). In this case, too, the light beam from the photographing optical system 1 passes through the microlenses 811 and 821, and then enters the photoelectric conversion portions 812 and 822 of the focus detection pixels 81 and 82, with a portion of the light being blocked (restricted) by the second light-shielding portions 813b and 823b.

[0059] In the third pixel group 853 shown in Fig. 8(c), the focus detection pixels 81 and 82 have the first light-shielding portions 813a and 823a similar to those in Fig. 4(c), and do not have the second light-shielding portions 813b and 823b and the third light-shielding portions 813c and 823c shown in Fig. 4(c). That is, the focus detection pixels 81 and 82 in Fig. 8(a) only have the first light-shielding portions 813a and 823a, which have the largest light-shielding areas, among the light-shielding portions 813 and 823 shown in Fig. 4(c). In this case, too, the light beam from the photographing optical system 1 passes through the microlenses 811 and 821, and then enters the photoelectric conversion portions 812 and 822 of the focus detection pixels 81 and 82, with a portion of the light being blocked (restricted) by the first light-shielding portions 813a and 823a.

[0060] Another example of focus detection pixels 81, 82 shown in Figure 8 has the configuration described above, and therefore can limit the light flux from the photographic optical system 1 in the same manner as in the embodiment, while making it possible to reduce the number of parts. Note that the focus detection pixels 81 and 82 are not limited to having one light-shielding portion 813 and one light-shielding portion 823, as shown in FIGS. 8(a) to 8(c). For example, as shown in FIG. 8(d), the focus detection pixel 81 of the first pixel group 851 has a first light-shielding portion 813a, a second light-shielding portion 813b, and a third light-shielding portion 813c as the light-shielding portion 813, similar to the case shown in FIG. 4(a). The focus detection pixel 82 has only the third light-shielding portion 823c as the light-shielding portion 823, and does not have the first light-shielding portion 823a or the second light-shielding portion 823b. In this case, as in the focus detection pixels 81 and 82 of the embodiment, the light beam from the photographing optical system 1 can be shielded (restricted) by the third light-shielding portions 813c and 823c. 8(d), the focus detection pixel 81 may include one light-shielding portion 813, and the focus detection pixel 82 may include multiple light-shielding portions 823 as shown in Fig. 4(a). Also, in Fig. 8(d), the structure of the focus detection pixels 81, 82 in the first pixel group 851 is given as an example, but the above structure can be applied to the focus detection pixels 81, 82 included in the second pixel group 852 and the third pixel group 853.

[0061] 9, the structure of focus detection pixels 81, 82 in yet another example will be described. In the following description, a case will be taken as an example in which the focus detection pixels 81, 82 have different structures based on their positions on the imaging surface 800 of the image sensor 8. That is, the focus detection pixels 81, 82 arranged near the center of the imaging surface 800 of the image sensor 8 (for example, focus detection area 810c in FIG. 3(a)) and the focus detection pixels 81, 82 arranged near the periphery of the imaging surface 800 (for example, focus detection area 810d in FIG. 3(a)) have different structures.

[0062] Fig. 9(a) is a diagram showing a schematic cross-sectional structure of focus detection pixels 81, 82 of a pixel group 850 provided in a focus detection region 810c near the center of an imaging surface 800. A first light-shielding portion 813a, a second light-shielding portion 813b, and a third light-shielding portion 813c included in a light-shielding portion 813 of a focus detection pixel 81 shown in Fig. 9(a) have light-shielding areas similar to those of the first light-shielding portion 813a in Fig. 4(c), the second light-shielding portion 813b in Fig. 4(b), and the third light-shielding portion 813c in Fig. 4(a), respectively. Similarly, the first light-shielding portion 823a, the second light-shielding portion 823b and the third light-shielding portion 823c included in the light-shielding portion 823 of the focus detection pixel 82 shown in Figure 9(a) have the same light-shielding area as the first light-shielding portion 823a of Figure 4(c), the second light-shielding portion 823b of Figure 4(b) and the third light-shielding portion 823c of Figure 4(a), respectively.

[0063] The focus detection pixels 81, 82 arranged in positions that are less susceptible to vignetting, such as near the center of the imaging surface 800, can block (limit) the light beam from the photographing optical system 1 by the first light shielding portions 813a, 823a, the second light shielding portions 813b, 823b, and the third light shielding portions 813c, 823c. By blocking the light beam with a plurality of light shielding portions, it is possible to suppress light diffraction and the like, and therefore it is possible to further improve the light shielding performance for the light beam. By improving the light shielding performance, i.e., by improving the pupil division accuracy, it is possible to improve the accuracy of focus detection performed by the focus detection calculation circuit 14.

[0064] 9B is a diagram showing a schematic cross-sectional structure of focus detection pixels 81, 82 of a first pixel group 851 provided in a focus detection region 810d near the periphery of the imaging surface 800. In the light-shielding portion 813 of the focus detection pixel 81, the light-shielding area of ​​the second light-shielding portion 813b is larger than that of the first light-shielding portion 813a, and the light-shielding area of ​​the third light-shielding portion 813c is larger than that of the second light-shielding portion 813b. In the light-shielding portion 823 of the focus detection pixel 82, the light-shielding area of ​​the second light-shielding portion 823b is larger than that of the first light-shielding portion 823a, and the light-shielding area of ​​the third light-shielding portion 823c is larger than that of the second light-shielding portion 823b.

[0065] 9C shows a schematic cross-sectional structure of focus detection pixels 81 and 82 of a third pixel group 853 provided in a focus detection region 810d. In the light-shielding portion 813 of the focus detection pixel 81, the second light-shielding portion 813b has a larger light-shielding area than the third light-shielding portion 813c, and the first light-shielding portion 813a has a larger light-shielding area than the second light-shielding portion 813b. In the light-shielding portion 823 of the focus detection pixel 82, the second light-shielding portion 823b has a larger light-shielding area than the third light-shielding portion 823c, and the first light-shielding portion 823a has a larger light-shielding area than the second light-shielding portion 823b.

[0066] As described above, in the focus detection pixels 81, 82 of the first pixel group 851 and the focus detection pixels 81, 82 of the third pixel group 853, the light beam from the photographing optical system 1 can be blocked (restricted) by the first light-shielding portions 813a, 823a, the second light-shielding portions 813b, 823b, and the third light-shielding portions 813c, 823c. By blocking the light beam with a plurality of light-shielding portions, it is possible to suppress light diffraction and the like, and therefore the light-shielding performance for the light beam can be further improved. By improving the light-shielding performance of the focus detection pixels 81, 82 in the peripheral portion of the imaging surface 800 of the image sensor 8, that is, by improving the pupil division accuracy, the accuracy of focus detection performed by the focus detection calculation circuit 14 can be improved. In addition, in a focus detection area 810 provided on the periphery of the imaging surface 800, the focus detection pixels 81, 82 of the second pixel group 852 may have the structure of FIG. 9(a) or the structure of FIG. 4(b).

[0067] Moreover, the focus detection pixels 81 and 82 of the first pixel group 851 may have a structure shown in FIG. 9(d). The focus detection pixel 81 includes a light shielding portion 833 in addition to the light shielding portion 813. The light shielding portions 813 and 833 are provided on opposite sides along the x-axis, that is, the light shielding portion 813 is provided on the positive side of the x-axis, and the light shielding portion 833 is provided on the negative side of the x-axis. The light shielding portion 813 shown in FIG. 9(d) has the same configuration as that shown in FIG. 9(b). The light shielding portion 833 includes a first light shielding portion 833a, a second light shielding portion 833b, and a third light shielding portion 833c. The distance between the microlens 811 and the second light shielding portion 833b is greater than the distance between the microlens 811 and the first light shielding portion 833a. The distance between the microlens 811 and the third light shielding portion 833c is greater than the distance between the microlens 811 and the second light shielding portion 833b. Furthermore, the second light-shielding portion 833b has a larger light-shielding area than the third light-shielding portion 833c, and the first light-shielding portion 833a has a larger light-shielding area than the second light-shielding portion 833b. Since the focus detection pixel 81 has such a structure, it is possible to improve the light-shielding performance of the light beam from the photographing optical system 1 by the light-shielding portion 813 from the x-axis + side and the light-shielding portion 833 from the x-axis - side. As a result, the accuracy of pupil division is improved, and the accuracy of focus detection performed by the focus detection calculation circuit 14 can be improved.

[0068] The focus detection pixel 82 in FIG. 9(d) includes a light shielding portion 843 in addition to the light shielding portion 823. The light shielding portions 823 and 843 are provided on opposite sides along the x-axis, that is, the light shielding portion 823 is provided on the negative side of the x-axis, and the light shielding portion 843 is provided on the positive side of the x-axis. In this case, the light shielding portion 823 has a configuration similar to that of FIG. 9(b). The light shielding portion 843 includes a first light shielding portion 843a, a second light shielding portion 843b, and a third light shielding portion 843c. The distance between the microlens 811 and the second light shielding portion 843b is greater than the distance between the microlens 811 and the first light shielding portion 843a. The distance between the microlens 811 and the third light shielding portion 843c is greater than the distance between the microlens 811 and the second light shielding portion 843b. Furthermore, the second light-shielding portion 843b has a larger light-shielding area than the third light-shielding portion 843c, and the first light-shielding portion 843a has a larger light-shielding area than the second light-shielding portion 843b. By having the above-described structure for the focus detection pixel 82, it is possible to improve the light-shielding performance of the light beam from the photographing optical system 1 by the light-shielding portion 823 from the negative x-axis side and the light-shielding portion 843 from the positive x-axis side. As a result, the accuracy of pupil division is improved, and the accuracy of focus detection performed by the focus detection calculation circuit 14 can be improved. 9D, the focus detection pixel 81 of the third pixel group 853 may include a light-shielding portion 813 and a light-shielding portion 833, and the focus detection pixel 82 may include a light-shielding portion 823 and a light-shielding portion 843. In this case, in the light-shielding portion 833, the light-shielding area of ​​the second light-shielding portion 833b is larger than that of the first light-shielding portion 833a, and the light-shielding area of ​​the third light-shielding portion 833c is larger than that of the second light-shielding portion 833b. In the light-shielding portion 843, the light-shielding area of ​​the second light-shielding portion 843b is larger than that of the first light-shielding portion 843a, and the light-shielding area of ​​the third light-shielding portion 843c is larger than that of the second light-shielding portion 843b. In the focus detection pixels 81 and 82 of the third pixel group 853 having such a structure, the light-shielding property of the light beam can be improved, as in the case of the focus detection pixels 81 and 82 of the first pixel group 851. As a result, the accuracy of pupil division is improved, and the accuracy of focus detection performed by the focus detection calculation circuit 14 can be improved.

[0069] -Variations- The following modifications are also within the scope of the present invention and can be combined with the above-described embodiment. FIG. 7 is a plan view showing a schematic diagram of focus detection pixels 81, 82 provided in an image sensor 8 in a modified example. FIG. 7(a) shows a first pixel group 851, FIG. 7(b) shows a second pixel group 852, and FIG. 7(c) shows a third pixel group 853. In the modified example, in each pixel group 850, an imaging pixel 80 is not provided between a pair of focus detection pixels 81, 82 along the X-axis direction, but an imaging pixel 80 is provided between a pair of focus detection pixels 81, 82 and another pair of focus detection pixels 81, 82. The focus detection pixels 81, 82 of each pair have a common light-shielding portion 813. The light-shielding area of ​​the light-shielding portion 813 is the same regardless of which pixel group 850 the focus detection pixels 81, 82 are provided in. That is, the light shielding area of ​​the third light shielding portion 813c in the first pixel group 851, the light shielding area of ​​the second light shielding portion 813b in the second pixel group 852, and the light shielding area of ​​the first light shielding portion 813a in the third pixel group 853 are equal to each other.

[0070] The position where the light shielding portion 813 is provided along the X-axis direction is different for each pixel group 850. In the first pixel group 851 shown in FIG. 7(a), the third light shielding portion 813c is provided at a position offset by a predetermined amount toward the X-axis + side from the position of the second light shielding portion 813b of the second pixel group 852 shown in FIG. 7(b). In the third pixel group 853 shown in FIG. 7(c), the first light shielding portion 813a is provided at a position offset by a predetermined amount toward the X-axis - side from the position of the second light shielding portion 813b of the second pixel group 852 shown in FIG. 7(b). The predetermined amount of deviation may be determined by multiplying the distance of the focus detection pixels 81 and 82 from the center of the imaging surface 800, i.e., the image height, by a predetermined coefficient. Furthermore, when the light-shielding portions 813a and 813b are provided symmetrically with respect to the center of the imaging surface 800 of the imaging element 8, the third light-shielding portion 813c of the first pixel group 851 can be offset toward the negative side in the X-axis direction, and the first light-shielding portion 813a of the third pixel group 853 can be offset toward the positive side in the X-axis direction. With the above configuration, an increase in the number of parts can be suppressed.

[0071] In addition, in the above-described embodiment, an example has been described in which the selection unit 51 selects, from the first pixel group 851 to the third pixel group 853, the pixel group 850 that is suitable for the photographing optical system 1 provided in the attached photographing lens body 300 based on lens information, but this is not limited to this. For example, the first pixel group 851 to the third pixel group 853 may all be selected, and the most suitable one may be weighted to perform focus detection calculations. For example, if the first pixel group 851 is most suitable for the photographing optical system 1 and the third pixel group 853 is least suitable for the photographing optical system 1, a weight of 1 may be assigned to the focus detection result obtained using the first pixel group 851, a weight of 0.5 may be assigned to the focus detection result obtained using the second pixel group 852, and a weight of 0.1 may be assigned to the focus detection result obtained using the third pixel group 853. For example, among the first pixel group 851 to the third pixel group 853, the pixel group 850 that is least suitable for the photographing optical system 1 may be excluded, and the focus detection calculation may be performed using the two pixel groups 850. Furthermore, the pixel groups 950 may be arranged arbitrarily. For example, one type of pixel group 850 (e.g., second pixel group 852) may be arranged in the center of the imaging surface 800 (e.g., near 810c in FIG. 3), and three types of pixel groups 850 (e.g., first pixel group 851 to third pixel group 853) may be arranged in the periphery of the imaging surface 800 (e.g., near 810a in FIG. 3).

[0072] 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 that are conceivable within the scope of the technical idea of ​​the present invention are also included within the scope of the present invention.

[0073] The disclosures of the following priority applications are incorporated herein by reference: Japanese Patent Application No. 2015-254898 (filed December 25, 2015) [Explanation of symbols]

[0074] 5...control unit, 8...image sensor, 14...focus detection calculation circuit, 15...body-lens communication unit, 51...selection unit, 80...imaging pixel, 81, 82...focus detection pixel, 100...digital camera, 811, 821...microlens, 813, 823...light shielding unit, 812, 822...photoelectric conversion unit, 850...pixel group, 851...first pixel group, 852...second pixel group, 853...third pixel group

Claims

1. a plurality of first pixels each including a first photoelectric conversion unit that performs photoelectric conversion on light that has passed through an optical system and a first light shielding unit that shields a portion of light that is incident on the first photoelectric conversion unit, the first pixels outputting a signal used for focus detection based on the photoelectric conversion in the first photoelectric conversion unit; a second photoelectric conversion unit that performs photoelectric conversion on light that has passed through the optical system to generate electric charges; and a second light-shielding unit that blocks a portion of light that is incident on the second photoelectric conversion unit and has an area different from that of the first light-shielding unit, and a plurality of second pixels that output a signal used for focus detection based on the photoelectric conversion in the second photoelectric conversion unit; an output section that outputs signals output from the plurality of first pixels and signals output from the plurality of second pixels; Equipped with a signal of a pixel selected from among the signals output from the plurality of first pixels and the signals output from the plurality of second pixels based on information on a distance between an optical axis of the optical system and the first pixel and a distance between the optical axis of the optical system and the second pixel is used for focus detection; an area of ​​the first light-shielding portion of each of at least two of the plurality of first pixels varies depending on a position on an imaging surface; an area of ​​the second light-shielding portion included in each of at least two of the second pixels varies depending on a position on the imaging surface; an area of ​​the first light-shielding portion of a first pixel located near a center of the imaging surface among the plurality of first pixels is smaller than an area of ​​the first light-shielding portion of a first pixel located near an edge of the imaging surface; an area of ​​the second light-shielding portion of the second pixel located near a center of the imaging surface is smaller than an area of ​​the second light-shielding portion of the second pixel located near an edge of the imaging surface; Image sensor.

2. 2. The imaging device according to claim 1, An imaging element, wherein a light-shielding area where the first light-shielding portion blocks light is different from a light-shielding area where the second light-shielding portion blocks light.

3. 3. The imaging device according to claim 1, the first pixel receives light that has passed through a first region of the optical system; The second pixel is an imaging element that receives light that has passed through a second region of the optical system that is different from the first region.

4. 4. The imaging device according to claim 1, An image sensor in which the amount of light photoelectrically converted by the first photoelectric conversion unit is different from the amount of light photoelectrically converted by the second photoelectric conversion unit.

5. A first photoelectric conversion unit that performs photoelectric conversion on light that has passed through an optical system, and a first shading unit that blocks a portion of the light that is incident on the first photoelectric conversion unit, and a plurality of first pixels that output signals used for focus detection based on the photoelectric conversion in the first photoelectric conversion unit; a second photoelectric conversion unit that performs photoelectric conversion on light that has passed through the optical system to generate electric charges; and a second light-shielding unit that blocks a portion of light that is incident on the second photoelectric conversion unit and has an area different from that of the first light-shielding unit, and a plurality of second pixels that output a signal used for focus detection based on the photoelectric conversion in the second photoelectric conversion unit; an output section that outputs signals output from the plurality of first pixels and signals output from the plurality of second pixels; Equipped with a signal of a pixel selected from among the signals output from the plurality of first pixels and the signals output from the plurality of second pixels based on information on a distance between an optical axis of the optical system and the first pixel and a distance between the optical axis of the optical system and the second pixel is used for focus detection; The imaging element, wherein the number of the first pixels is different from the number of the second pixels.

6. 6. The imaging device according to claim 1, An imaging element, wherein the first light-shielding portion is wiring of a circuit arranged in the first pixel, and the second light-shielding portion is wiring of a circuit arranged in the second pixel.

7. The imaging element according to any one of claims 1 to 6, a control unit that controls a position of the optical system to a focusing position where an image formed by the optical system is focused on the imaging element based on at least one of signals output from the plurality of first pixels and signals output from the plurality of second pixels; An imaging device comprising:

Images