阅读说明：本技术 焦点检测装置、拍摄装置以及可更换镜头 (Focus detection device, imaging device, and interchangeable lens ) 是由 三本木慎典 木下朗 喜多祐起 于 2019-07-19 设计创作，主要内容包括：焦点检测装置具备：拍摄部,其具有接受透射了光学系统的光而输出在焦点检测中使用的信号的第1像素及第2像素、和接受透射了所述光学系统的光而输出在图像生成中使用的信号的第3像素；输入部,其被输入与所述光学系统有关的信息；选择部,其基于被输入到所述输入部的所述信息,选择所述第1像素和所述第2像素中的至少一方；读出部,其基于所述选择部的选择,以与所述第3像素的信号不同的定时读出所述第1像素的信号和所述第2像素的信号中的至少一方；以及焦点检测部,其基于通过所述读出部读出的所述第1像素的信号和所述第2像素的信号中的至少一方,进行焦点检测。(The focus detection device includes: an imaging unit having a1 st pixel and a2 nd pixel that receive light transmitted through an optical system and output a signal used for focus detection, and a 3 rd pixel that receive light transmitted through the optical system and output a signal used for image generation; an input unit into which information relating to the optical system is input; a selection unit that selects at least one of the 1 st pixel and the 2 nd pixel based on the information input to the input unit; a reading unit that reads at least one of the signal of the 1 st pixel and the signal of the 2 nd pixel at a timing different from the signal of the 3 rd pixel based on the selection by the selection unit; and a focus detection unit that performs focus detection based on at least one of the signal of the 1 st pixel and the signal of the 2 nd pixel read by the reading unit.)

1. A focus detection device is provided with:

an imaging unit having a1 st pixel and a2 nd pixel that receive light transmitted through an optical system and output a signal used for focus detection, and a 3 rd pixel that receive light transmitted through the optical system and output a signal used for image generation;

an input unit into which information relating to the optical system is input;

a selection unit that selects at least one of the 1 st pixel and the 2 nd pixel based on the information input to the input unit;

a reading unit that reads at least one of the signal of the 1 st pixel and the signal of the 2 nd pixel at a timing different from the signal of the 3 rd pixel based on the selection by the selection unit; and

and a focus detection unit that performs focus detection based on at least one of the signal of the 1 st pixel and the signal of the 2 nd pixel read by the readout unit.

2. The focus detection apparatus according to claim 1,

the selection section selects the 1 st pixel or the 2 nd pixel based on the information input to the input section,

the readout section reads out the signal of the 1 st pixel or the signal of the 2 nd pixel at a timing different from the signal of the 3 rd pixel based on the selection by the selection section,

the focus detection unit performs focus detection based on the signal of the 1 st pixel or the signal of the 2 nd pixel read by the readout unit.

3. The focus detection apparatus according to claim 1 or 2,

the readout unit reads out at least one of the signal of the 1 st pixel and the signal of the 2 nd pixel before the signal of the 3 rd pixel.

4. The focus detection apparatus according to claim 3,

the readout unit can switch between a1 st readout in which at least one of a signal of the 1 st pixel and a signal of the 2 nd pixel is read out before a signal of the 3 rd pixel, and a2 nd readout in which a signal of the 3 rd pixel is read out next to the signal of the 1 st pixel and a signal of the 2 nd pixel is read out next to the signal of the 3 rd pixel.

5. The focus detection apparatus according to claim 4,

the imaging section has a plurality of the 3 rd pixels,

the readout unit performs the 1 st readout when reading out signals of a part of the 3 rd pixels or performing the readout by adding signals of the 3 rd pixels, and performs the 2 nd readout when reading out signals of the 3 rd pixels.

6. The focus detection apparatus according to any one of claims 1 to 5,

the imaging unit includes a signal line provided in a1 st direction and connecting at least one of the 1 st pixel and the 2 nd pixel and the 3 rd pixel.

7. The focus detection apparatus according to claim 6,

at least one of the 3 rd pixels is disposed between the 1 st pixel and the 2 nd pixel in the 1 st direction.

8. The focus detection apparatus according to claim 6 or 7,

the imaging unit includes a1 st pixel group and a2 nd pixel group arranged in the 1 st direction, the 1 st pixel group is provided with a plurality of 1 st pixels in a2 nd direction intersecting the 1 st direction, the 2 nd pixel group is provided with a plurality of 2 nd pixels in the 2 nd direction,

the selection unit selects at least one of the 1 st pixel group and the 2 nd pixel group based on the information.

9. The focus detection apparatus according to claim 8,

the imaging unit has a 3 rd pixel group which is provided between the 1 st pixel group and the 2 nd pixel group and has a plurality of 3 rd pixels in the 2 nd direction,

the readout unit reads out at least one of the 1 st pixel group signal and the 2 nd pixel group signal and the 3 rd pixel group signal at different timings.

10. The focus detection apparatus according to claim 9,

the readout unit reads out at least one of the signal of the 1 st pixel group and the signal of the 2 nd pixel group before the signal of the 3 rd pixel group.

11. The focus detection apparatus according to any one of claims 1 to 10,

the photographing part has a plurality of focus detection areas having the 1 st pixel and the 2 nd pixel,

the selection unit selects at least one of the 1 st pixel and the 2 nd pixel based on the information and a position of the focus detection region.

12. The focus detection apparatus according to claim 11,

the selection unit selects at least one of the 1 st pixel and the 2 nd pixel in a plurality of the focus detection regions.

13. The focus detection apparatus according to claim 11 or 12,

the selection unit selects the 1 st pixel in one of the focus detection regions, and selects the 1 st pixel in the other focus detection region, and selects the 2 nd pixel in the other focus detection region, when the 2 nd pixel is selected in one of the focus detection regions.

14. The focus detection apparatus according to any one of claims 11 to 13,

the selection unit selects at least one of the 1 st pixel and the 2 nd pixel based on the information and a position of the focus detection region farthest from an optical axis among the plurality of focus detection regions.

15. The focus detection apparatus according to claim 14,

the selection unit selects the 1 st pixel in the other focus detection region when the 1 st pixel is selected at a position of the focus detection region farthest from the optical axis among the plurality of focus detection regions, and selects the 2 nd pixel in the other focus detection region when the 2 nd pixel is selected at a position of the focus detection region farthest from the optical axis.

16. The focus detection apparatus according to any one of claims 11 to 15,

a plurality of the focus detection regions have a1 st focus detection region and a2 nd focus detection region farther from the optical axis than the 1 st focus detection region,

the selection unit selects at least one of the 1 st pixel and the 2 nd pixel based on the information and a position of the 2 nd focus detection region.

17. The focus detection apparatus according to claim 16,

the selection unit selects the 1 st pixel in the 1 st focus detection region when the 1 st pixel is selected in the 2 nd focus detection region, and selects the 2 nd pixel in the 1 st focus detection region when the 2 nd pixel is selected in the 2 nd focus detection region.

18. The focus detection apparatus according to any one of claims 11 to 17,

a setting unit capable of setting an arbitrary focus detection region from a plurality of focus detection regions,

the selection unit selects at least one of the 1 st pixel and the 2 nd pixel based on the information and the position of the focus detection region set by the setting unit.

19. The focus detection apparatus according to any one of claims 1 to 18,

the information is information relating to an exit pupil distance of the optical system.

20. The focus detection apparatus according to any one of claims 1 to 19,

the information is information relating to a position in an image plane and an exit pupil distance of the optical system.

21. The focus detection apparatus according to any one of claims 1 to 20,

the imaging section has a plurality of the 1 st pixels and a plurality of the 2 nd pixels,

the plurality of 1 st pixels include a pixel that receives light that has passed through a1 st pupil region of the optical system and a pixel that receives light that has passed through a2 nd pupil region different from the 1 st pupil region,

the plurality of 2 nd pixels include a pixel that receives light that has passed through the 1 st pupil region and a pixel that receives light that has passed through the 2 nd pupil region.

22. The focus detection apparatus according to any one of claims 1 to 21,

the 1 st pixel and the 2 nd pixel each have a photoelectric conversion portion,

the area of the photoelectric conversion portion of the 1 st pixel receiving light is different from the area of the photoelectric conversion portion of the 2 nd pixel receiving light.

23. An imaging device is provided with:

the focus detection apparatus according to any one of claims 1 to 22; and

and a generation unit that generates image data based on a signal output from at least one of the 1 st pixel, the 2 nd pixel, and the 3 rd pixel.

24. An interchangeable lens comprising a mount portion that can be mounted on the focus detection device according to any one of claims 1 to 22.

Technical Field

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

Background

An imaging element that reads out a signal for focus detection and a signal for image generation is known (for example, patent document 1). Such an imaging element is speeded up in reading a desired signal.

Documents of the prior art

Patent document

Patent document 1 Japanese patent application laid-open No. 2017-34606

Disclosure of Invention

According to claim 1 of the present invention, a focus detection device includes: an imaging unit having a1 st pixel and a2 nd pixel that receive light transmitted through an optical system and output a signal used for focus detection, and a 3 rd pixel that receive light transmitted through the optical system and output a signal used for image generation; an input unit into which information relating to the optical system is input; a selection unit that selects at least one of the 1 st pixel and the 2 nd pixel based on the information input to the input unit; a reading unit that reads at least one of the signal of the 1 st pixel and the signal of the 2 nd pixel at a timing different from the signal of the 3 rd pixel based on the selection by the selection unit; and a focus detection unit that performs focus detection based on at least one of the signal of the 1 st pixel and the signal of the 2 nd pixel read by the reading unit.

According to claim 2 of the present invention, an imaging apparatus includes: the focus detection apparatus according to claim 1; and a generation unit that generates image data based on a signal output from at least one of the 1 st pixel, the 2 nd pixel, and the 3 rd pixel.

According to claim 3 of the present invention, the interchangeable lens includes a mount portion that can be mounted to the focus detection apparatus according to claim 1.

Drawings

Fig. 1 is a diagram showing a configuration example of an imaging device according to embodiment 1.

Fig. 2 is a diagram illustrating a focus detection area of an imaging surface of the imaging device according to embodiment 1.

Fig. 3 is a diagram showing an example of arrangement of pixels in a focus detection area of the imaging device according to embodiment 1.

Fig. 4 is a diagram showing an example of a pixel configuration in the imaging device according to embodiment 1.

Fig. 5 is a cross-sectional view showing three types of AF pixel pairs arranged in the central area in the imaging device according to embodiment 1.

Fig. 6 is a cross-sectional view showing three types of AF pixel pairs arranged in a region at a predetermined image height position in the imaging apparatus according to embodiment 1.

Fig. 7 is a cross-sectional view showing three types of AF pixel pairs arranged in a region at a predetermined image height position in the imaging apparatus according to embodiment 1.

Fig. 8 is a diagram showing a relationship between a reference exit pupil and an image height in the imaging device according to embodiment 1.

Fig. 9 is a diagram showing various optical characteristics of the interchangeable lens in the imaging device according to embodiment 1, in which the exit pupil distance changes depending on the image height.

Fig. 10 is a diagram showing a relationship between an image height and an exit pupil in the imaging device according to embodiment 1.

Fig. 11 is a table showing a focus position section and constant terms and coefficients of a function for approximating a representative optical characteristic curve of the focus position section in the imaging device according to embodiment 1.

Fig. 12 is a table showing a section and constant terms and coefficients of functions for approximating a representative optical characteristic curve of the section in the imaging device according to embodiment 1.

Fig. 13 is a diagram showing threshold values relating to the exit pupil distance, the range from the 1 st exit pupil distance to the 3 rd exit pupil distance, and optical characteristic curves in the imaging device according to embodiment 1.

Fig. 14 is a diagram showing a circuit configuration of a pixel of the imaging element according to embodiment 1.

Fig. 15 is a diagram showing a partial configuration of an imaging element according to embodiment 1.

Fig. 16 is a diagram showing an example of the configuration of AF pixels in the imaging device according to the modification.

Fig. 17 is a diagram showing an example of the configuration of AF pixels in the imaging device according to the modification.

Detailed Description

(embodiment 1)

Fig. 1 is a diagram showing an example of the configuration of an electronic camera 1 (hereinafter referred to as a camera 1) as an example of an imaging device according to embodiment 1. The camera 1 is constituted by a camera body 2 and an interchangeable lens 3. The camera 1 is sometimes referred to as a camera system because it is composed of a camera body 2 and an interchangeable lens 3.

The camera body 2 is provided with a body-side fixing portion 201 to which the interchangeable lens 3 is attached. The interchangeable lens 3 is provided with a lens-side fixing portion 301 that can be attached to the camera body 2. The lens-side fixing portion 301 and the body-side fixing portion 201 are provided with a lens-side connecting portion 302 and a body-side connecting portion 202, respectively. The lens-side connection portion 302 and the body-side connection portion 202 are provided with a plurality of terminals such as a clock signal terminal, a data signal terminal, and a power supply terminal. The interchangeable lens 3 is detachably attached to the camera body 2 via the lens-side fixing portion 301 and the body-side fixing portion 201.

When the interchangeable lens 3 is attached to the camera body 2, the terminal provided in the body-side connecting portion 202 is electrically connected to the terminal provided in the lens-side connecting portion 302. This enables power supply from the camera body 2 to the interchangeable lens 3 and communication between the camera body 2 and the interchangeable lens 3.

The interchangeable lens 3 includes a photographing optical system (imaging optical system) 31, a lens control unit 32, and a lens memory 33. The image pickup optical system 31 includes a plurality of lenses including a zoom lens (variable power lens)31a for changing a focal length, a focus lens (focus adjustment lens)31 b, and a diaphragm 31c, and forms an object image on an image pickup surface 22a of the image pickup device 22. Further, in fig. 1, the zoom lens 31a and the focus lens 31b are schematically illustrated, but a general photographing optical system is generally configured by a large number of optical elements.

As described later, the photographing optical system 31 of the interchangeable lens 3 has optical characteristics in which the position of the exit pupil, that is, the exit pupil distance changes according to the image height. In other words, the exit pupil distance of the photographing optical system 31 varies depending on the position in the photographing surface 22a, that is, the distance from the optical axis OA1 of the photographing optical system 31 in the photographing surface 22 a. The optical axis OA1 of the imaging optical system 31 intersects the imaging surface 22a at the center of the imaging surface 22 a. It can also be said that the exit pupil distance of the imaging optical system 31 varies depending on the distance from the center of the imaging surface 22 a. Here, the exit pupil distance refers to a distance between the exit pupil of the photographing optical system 31 and the image plane of the image of the photographing optical system 31. The imaging surface 22a of the imaging element 22 is a surface on which a photoelectric conversion unit described later is disposed or a surface on which a microlens is disposed, for example.

The imaging optical system 31 differs depending on the type of the interchangeable lens 3 attached to the body-side fixing portion 201. Therefore, the exit pupil distance of the photographing optical system 31 differs depending on the kind of the interchangeable lens 3. Further, the optical characteristics of the exit pupil distance that vary according to the image height also differ according to the type of the interchangeable lens 3.

The lens control unit 32 is composed of a processor such as a CPU, FPGA, or ASIC, and a memory such as a ROM or RAM, and controls each unit of the interchangeable lens 3 based on a control program. The lens control unit 32 controls the position of the zoom lens 31a, the position of the focus lens 31b, and the driving of the diaphragm 31c based on a signal output from the body control unit 210 of the camera body 2. When a signal indicating the movement direction, the movement amount, or the like of the focus lens 31b is input from the body control unit 210, the lens control unit 32 moves the focus lens 31b forward and backward in the direction of the optical axis OA1 based on the signal, and adjusts the focal position of the photographing optical system 31. The lens control unit 32 controls the position of the zoom lens 31a and the aperture diameter of the diaphragm 31c based on a signal output from the body control unit 210 of the camera body 2.

The lens memory 33 is configured by, for example, a nonvolatile storage medium. Information associated with the interchangeable lens 3 is stored (recorded) in the lens memory 33 as lens information. The lens information includes data relating to optical characteristics (exit pupil distance, F value) of the photographing optical system 31, data relating to an infinite position, an extremely close position of the focus lens 31b, data relating to a shortest focal length and a longest focal length of the interchangeable lens 3, and the like. Further, the lens information differs depending on the kind of the interchangeable lens 3. The lens information may be stored in a memory inside the lens control unit 32. The lens information may be stored in a body memory 23 of the camera body 2 described later. In this case, the body memory 23 stores lens information of a plurality of interchangeable lenses 3.

In the present embodiment, the lens information includes information on the exit pupil distance of the photographing optical system 31. The information on the exit pupil distance will be described later, but includes information indicating the exit pupil distance (Co) at a position where the imaging plane 22a intersects the optical axis OA1 (position where the image height is zero), and information of coefficients (h4, h2) included in the arithmetic expression indicating the relationship between the exit pupil distance and the image height. The lens control unit 32 controls writing of data into the lens memory 33 and reading of data from the lens memory 33. When the interchangeable lens 3 is attached to the camera body 2, the lens control section 32 transmits lens information to the body control section 210 via the terminals of the lens-side connecting section 302 and the body-side connecting section 202. The lens control unit 32 transmits, to the body control unit 210, position information (focal length information) of the zoom lens 31a after the control, position information of the focus lens 31b after the control, information of the F value of the diaphragm 31c after the control, and the like.

In the present embodiment, the lens control unit 32 functions as an output unit that transmits information on the exit pupil distance of the photographing optical system 31 to the camera body 2. The body control unit 210 functions as an input unit to which information on the exit pupil distance of the photographing optical system 31 is input from the interchangeable lens 3.

The lens control unit 32 performs communication for bidirectionally transmitting and receiving information between the camera body 2 and the interchangeable lens 3 via the terminals of the lens-side connecting unit 302 and the body-side connecting unit 202. When a signal requesting transmission of information (h4, h2, Co) about the exit pupil distance is input from the camera body 2, the lens control unit 32 transmits the information about the exit pupil distance to the camera body 2. Further, the information on the exit pupil distance differs depending on the kind of the interchangeable lens 3. The lens control unit 32 may transmit information on the exit pupil distance to the camera body 2 every time the image pickup device 22 performs image pickup. The lens control unit 32 may transmit information on the exit pupil distance to the camera body 2 when the zoom lens 31a moves and the focal length of the photographing optical system 31 changes. The lens control unit 32 may transmit information on the focal length of the photographing optical system 31 and information on the exit pupil distance to the camera body 2 by one-time bidirectional communication.

Next, the structure of the camera body 2 will be described. The camera body 2 includes an imaging element 22, a body memory 23, a display unit 24, an operation unit 25, and a body control unit 210. The imaging element 22 is a CMOS image sensor or a CCD image sensor. The imaging element 22 captures an image of the subject formed by the imaging optical system 31. The plurality of pixels having photoelectric conversion portions of the imaging element 22 are arranged in a two-dimensional shape (row direction and column direction). The photoelectric conversion portion is constituted by a Photodiode (PD). The image pickup device 22 photoelectrically converts the received light by the photoelectric conversion unit to generate a signal, and outputs the generated signal to the body control unit 210.

As described later, the imaging element 22 includes imaging pixels that output signals used for image generation and AF pixels (focus detection pixels) that output signals used for focus detection. The photographing pixel includes: a pixel (hereinafter, referred to as an R pixel) having a color filter (filter) having spectral characteristics for splitting light in the 1 st wavelength range (light of red (R)) of the incident light; a pixel (hereinafter referred to as a "G pixel") having a color filter having spectral characteristics for splitting light in the 2 nd wavelength range (light of green (G)) of the incident light; and pixels (hereinafter, referred to as "B pixels") having color filters having spectral characteristics for splitting light in the 3 rd wavelength range (light of blue (B)) out of the incident light. The R pixels, the G pixels, and the B pixels are arranged in a Bayer (Bayer) arrangement. The AF pixels are arranged so as to be replaced with part of the imaging pixels, and are arranged so as to be dispersed over substantially the entire imaging surface 22a of the imaging device 22. In the following description, the term "pixel" refers to either or both of a capture pixel and an AF pixel.

The body memory 23 is formed of, for example, a nonvolatile storage medium. Image data, a control program, and the like are recorded in the body memory 23. The body control unit 210 controls writing of data into the body memory 23 and reading of data from the body memory 23. The display unit 24 displays an image based on image data, an image indicating a focus detection area (AF area) such as an AF frame, information related to shooting such as a shutter speed and an F value, and a menu screen. The operation unit 25 includes various setting switches such as a release button, a power switch, and a switch for switching various modes, and outputs signals corresponding to the respective operations to the body control unit 210. The operation unit 25 is a setting unit capable of setting an arbitrary focus detection area from a plurality of focus detection areas, and a user can select an arbitrary focus detection area by operating the operation unit 25.

The body control unit 210 is composed of a processor such as a CPU, FPGA, or ASIC, and a memory such as a ROM or RAM, and controls each unit of the camera 1 based on a control program. The body control unit 210 includes an area setting unit 211, a distance calculation unit 212, a pixel selection unit 213, a readout unit 214, a focus detection unit 215, and an image data generation unit 216.

The region setting unit 211 sets (selects) at least one focus detection region 100 among the plurality of focus detection regions 100 provided on the imaging surface 22a of the imaging element 22 shown in fig. 2 (a). The plurality of AF frames displayed on the display unit 24 correspond to the plurality of focus detection areas 100 provided in the imaging element 22, respectively. The area setting unit 211 sets, as an area to be subjected to focus detection, the focus detection area 100 corresponding to the AF frame selected by the user through operation of the operation unit 25 among the plurality of AF frames displayed on the display unit 24, or the focus detection area 100 automatically selected by the camera 1. The focus detection unit 215 detects the amount of shift (defocus amount) between the image of the imaging optical system 31 and the imaging surface 22a using the signal output from the AF pixel in the focus detection area 100 set by the area setting unit 211, which will be described later.

As schematically shown in fig. 2 (b), in the focus detection area 100, a plurality of types of pairs of AF pixels (AF pixel pairs) are arranged in addition to the imaging pixel, and in the present embodiment, the 1 st AF pixel pair, the 2 nd AF pixel pair, and the 3 rd AF pixel pair are arranged. In order to accurately detect the defocus amount even at exit pupil distances that differ depending on the image height or the type of interchangeable lens, a1 st AF pixel pair, a2 nd AF pixel pair, and a 3 rd AF pixel pair are arranged. One of the AF pixels constituting the AF pixel pair outputs a1 st signal Sig1, and the other AF pixel constituting the AF pixel pair outputs a2 nd signal Sig 2. The 1 st AF pixel pair, the 2 nd AF pixel pair, and the 3 rd AF pixel pair will be described later.

As shown in fig. 2 (a), the plurality of focus detection regions 100 are arranged in two-dimensional directions (row direction and column direction) and are provided at positions having different image heights. A small region 110a (see fig. 2 (b)) in the focus detection region 100a at the center of the imaging surface 22a is located on the optical axis OA1 of the imaging optical system 31, and the image height H thereof is substantially zero. The image height H of the focus detection area 100 increases as it is separated from the center of the imaging surface 22a (the optical axis OA1 of the imaging optical system 31). In other words, the image height H of the focus detection area 100 increases as the distance from the center of the imaging surface 22a increases. Therefore, the focus detection regions 100 farthest from the optical axis OA1 of the photographing optical system 31 (the image height H is highest) in the row in which the focus detection region 100a is located are focus detection regions 100b, 100c located at the left end (-end in the X direction) and the right end (+ end in the X direction) of the row. In the imaging element 22, the focus detection areas 100 in which the image height H is highest are 4 focus detection areas 100 located at the corners of the imaging surface 22 a.

Further, the focus detection area 100 has a predetermined area, and therefore, the image height differs for each AF pixel according to the position within the focus detection area 100. The image height of the small region 110a (see fig. 2 b) at the center and the small regions 110b and 110c (see fig. 2 b) at the left end (-end in the X direction) and the right end (+ end in the X direction) in the same focus detection region 100 are different. However, in the present embodiment, the value of the image height H at the center position of one focus detection region 100 is set as the value of the image height of the entire focus detection region 100. The image height of the focus detection area 100a at the center of the imaging surface 22a is zero, and the image heights of the focus detection areas 100b and 100c are a predetermined image height H.

The distance calculation unit 212 calculates the exit pupil distance of the photographing optical system 31 at the image height H. The distance calculation unit 212 calculates the exit pupil distance po (H) of the photographing optical system 31 at the image height H of the focus detection area 100 set by the area setting unit 211 according to the following expression (1).

Po(H)＝h4×H⁴+h2×H²+Co…(1)

Equation (1) is a calculation equation having the image height H as a variable, the parameter (H4) is a coefficient of the variable H in terms of degree 4, the parameter (H2) is a coefficient of the variable H in terms of degree 2, and the constant term Co is the exit pupil distance at the position where the image height is zero (the position of the optical axis OA1 on the imaging plane 22 a). The parameters (h4), (h2) and the constant term Co are information on the exit pupil distance corresponding to different image heights, and are values determined according to the optical characteristics of the photographing optical system 31. Information representing the parameters (h4), (h2), and the constant term Co is transmitted as lens information from the interchangeable lens 3 to the camera body 2. The arithmetic expression (1) is stored in a memory inside the body control unit 210.

The distance calculation unit 212 calculates an exit pupil distance po (H) associated with the image height H of the focus detection area 100 set by the area setting unit 211, based on the image height H of the focus detection area 100, the lens information (H4, H2, Co), and the arithmetic expression (1). The arithmetic expression (1) may be a memory stored in the lens control unit 32. The lens control unit 32 may transmit the arithmetic expression (1), the parameters (h4), (h2), and the constant term Co to the camera body 2 as lens information.

The pixel selection unit 213 selects at least one of the plurality of types of AF pixel pairs provided in the imaging element 22. In the present embodiment, the pixel selection unit 213 selects one type of AF pixel pair of the three types of AF pixel pairs (the 1 st AF pixel pair to the 3 rd AF pixel pair) arranged in the focus detection area 100 set by the area setting unit 211. The pixel selection unit 213 selects an AF pixel pair that matches the exit pupil distance po (h) calculated by the distance calculation unit 212 from among three AF pixel pairs, as will be described later. When a plurality of focus detection areas 100 are set by the area setting unit 211, the pixel selection unit 213 selects the same type of AF pixel pair in each of the selected focus detection areas 100.

The reading unit 214 reads a signal from the imaging element 22. When the display unit 24 displays a through image (live view image) of the subject or when moving image capturing is performed, the reading unit 214 reads out a signal used for image generation or a signal used for focus detection from the imaging device 22 at predetermined intervals. The readout unit 214 sequentially selects pixels of the imaging element 22 in units of lines, and reads out signals from the selected pixel lines in a so-called rolling shutter (rolling shutter) system.

The readout section 214 executes the 1 st readout mode and the 2 nd readout mode. In the 1 st readout mode, the readout unit 214 sequentially selects a pixel row in which AF pixels constituting the AF pixel pair selected by the pixel selection unit 213 are arranged (hereinafter, referred to as an AF pixel row) and a pixel row in which no AF pixel is arranged (hereinafter, referred to as a capture pixel row), and reads out a signal from each pixel. In the 2 nd readout mode, the readout section 214 separately performs readout of signals from the AF pixel rows and readout of signals from the photographing pixel rows.

For example, the reading unit 214 performs the 1 st reading mode when continuously capturing still images or when capturing moving images with high resolution (e.g., 4K moving image capturing). When the display unit 24 displays the through image or when the low-resolution moving image capturing (for example, Full HD moving image capturing) is performed, the reading unit 214 performs the 2 nd reading mode. The 1 st readout mode and the 2 nd readout mode will be described later.

The focus detection unit 215 performs focus detection processing necessary for automatic focus Adjustment (AF) of the photographing optical system 31. The focus detection unit 215 detects a focusing position (a movement amount of the focus lens 31b to the focusing position) of the focus lens 31b on the imaging surface 22a for focusing (imaging) an image of the imaging optical system 31. The focus detection unit 215 calculates the defocus amount by a pupil-division phase difference detection method using the 1 st signal Sig1 and the 2 nd signal Sig2 of the AF pixel pair read out by the readout unit 214.

The focus detection unit 215 calculates an image shift amount by performing a correlation operation between a1 st signal Sig1 generated by capturing an image generated by a1 st light flux passing through a1 st pupil area of the exit pupil of the imaging optical system 31 and a2 nd signal Sig2 generated by capturing an image generated by a2 nd light flux passing through a2 nd pupil area. The focus detection unit 215 converts the image shift amount into a defocus amount based on a predetermined conversion expression. The focus detection unit 215 calculates the movement amount of the focus lens 31b to the in-focus position based on the calculated defocus amount.

The focus detection unit 215 determines whether or not the defocus amount is within the allowable value. When the defocus amount is within the allowable value, the focus detection unit 215 determines that the focus is on. On the other hand, when the defocus amount exceeds the allowable value, the focus detection unit 215 determines that the lens is not in focus, and transmits a signal instructing the movement amount and lens movement of the focus lens 31b to the lens control unit 32 of the interchangeable lens 3. The lens control unit 32 automatically performs focus adjustment by moving the focus lens 31b in accordance with the movement amount.

The focus detection unit 215 may perform a focus detection process of a contrast detection method in addition to the focus detection process of the phase difference detection method. The body control unit 210 sequentially calculates the contrast evaluation value of the subject image based on the signals output from the imaging pixels while moving the focus lens 31b of the imaging optical system 31 in the direction of the optical axis OA 1. The body control unit 210 associates the position of the focus lens 31b with the contrast evaluation value using the position information of the focus lens 31b transmitted from the interchangeable lens 3. Then, the body control unit 210 detects the position of the focusing lens 31b at which the contrast evaluation value exhibits a peak value, that is, a maximum value, as the focusing position. The body control unit 210 transmits information of the position of the focus lens 31b corresponding to the detected in-focus position to the lens control unit 32. The lens control unit 32 moves the focus lens 31b to the in-focus position to perform focus adjustment.

The image data generation unit 216 performs various image processing on the signal of the imaging pixel read by the reading unit 214 to generate image data. The image data generation unit 216 may also generate image data using signals output from the AF pixels.

Fig. 3 is a diagram showing an example of arrangement of pixels in the focus detection area 100. The R pixels 13, G pixels 13, and B pixels 13 are arranged in a bayer arrangement. The 1 st AF pixel 11 and the 2 nd AF pixel 12 are arranged so as to be replaced with a part of the pickup pixel 13 of R, G, B subjected to the bayer arrangement. The 1 st AF pixel 11 and the 2 nd AF pixel 12 have light-shielding portions 43, respectively. The 1 st AF pixel 11 and the 2 nd AF pixel 12 differ in position of the light shielding portion 43.

As shown in fig. 3, the imaging element 22 has a pixel group (1 st imaging pixel row) 401 in which the R pixels 13 and the G pixels 13 are alternately arranged in the left-right direction, that is, the row direction, and a pixel group (2 nd imaging pixel row) 402 in which the G pixels 13 and the B pixels 13 are alternately arranged in the row direction. In addition, the imaging element 22 has a pixel group (1 st AF pixel row) 403 in which the G pixels 13 and the 1 st AF pixels 11 are alternately arranged in the row direction, and a pixel group (2 nd AF pixel row) 404 in which the G pixels 13 and the 2 nd AF pixels 12 are alternately arranged in the row direction.

The 1 st AF pixel 11a and the G pixel 13 are alternately arranged in the 1 st AF pixel row 403 a. The 2 nd AF pixels 12a and the G pixels 13 are alternately arranged in the 2 nd AF pixel row 404a that is apart from the 1 st AF pixel row 403a by a predetermined row. Further, the arrangement position of the 1 st AF pixel 11a in the 1 st AF pixel row 403a and the arrangement position of the 2 nd AF pixel 12a in the 2 nd AF pixel row 404a are the same as each other. That is, the 1 st AF pixel 11a and the 2 nd AF pixel 12a are arranged in the same column. The 1 st AF pixel 11a of the 1 st AF pixel row 403a and the 2 nd AF pixel 12a of the 2 nd AF pixel row 404a constitute a1 st AF pixel pair.

The 1 st AF pixel 11b and the G pixel 13 are alternately arranged in the 1 st AF pixel row 403b apart from the 2 nd AF pixel row 404a by a predetermined row. The 2 nd AF pixels 12b and the G pixels 13 are alternately arranged in the 2 nd AF pixel row 404b apart from the 1 st AF pixel row 403b by a predetermined row. Further, the arrangement position of the 1 st AF pixel 11b in the 1 st AF pixel row 403b and the arrangement position of the 2 nd AF pixel 12b in the 2 nd AF pixel row 404b are the same as each other. That is, the 1 st AF pixel 11b and the 2 nd AF pixel 12b are arranged in the same column. The 1 st AF pixel 11b of the 1 st AF pixel row 403b and the 2 nd AF pixel 12b of the 2 nd AF pixel row 404b constitute a2 nd AF pixel pair.

The 1 st AF pixel 11c and the G pixel 13 are alternately arranged in the 1 st AF pixel row 403c separated from the 2 nd AF pixel row 404b by a predetermined row. The 2 nd AF pixels 12c and the G pixels 13 are alternately arranged in the 2 nd AF pixel row 404c apart from the 1 st AF pixel row 403c by a predetermined row. Further, the arrangement position of the 1 st AF pixel 11c in the 1 st AF pixel row 403c and the arrangement position of the 2 nd AF pixel 12c in the 2 nd AF pixel row 404c are the same as each other. That is, the 1 st AF pixel 11c and the 2 nd AF pixel 12c are arranged in the same column. The 1 st AF pixel 11c of the 1 st AF pixel row 403c and the 2 nd AF pixel 12c of the 2 nd AF pixel row 404c constitute a 3 rd AF pixel pair.

In addition, a plurality of 1 st AF pixel pairs may be arranged such that the 1 st AF pixel row 403a and the 2 nd AF pixel row 404a are arranged in a plurality of rows. In addition, a plurality of 2 nd AF pixel pairs may be arranged such that the 1 st AF pixel row 403b and the 2 nd AF pixel row 404b are arranged in a plurality of rows. A plurality of 3 rd AF pixel pairs may also be arranged such that the 1 st AF pixel row 403c and the 2 nd AF pixel row 404c are arranged in a plurality of rows.

Further, as described above, the 1 st AF pixel pair, the 2 nd AF pixel pair, and the 3 rd AF pixel pair are arranged to detect the defocus amount with good accuracy even if the exit pupil distance varies depending on the image height or the kind of interchangeable lens. Therefore, the areas of the light shielding portions 43 of the 1 st AF pixel pair, the 2 nd AF pixel pair, and the 3 rd AF pixel pair are different except for the pixel pair around the optical axis OA1 (the center of the imaging surface 22 a) of the imaging optical system 31. When the exit pupil distances are different, the incident angle of light incident to the AF pixel is different except for the AF pixel at the periphery of the optical axis OA1 of the photographing optical system 31. When the exit pupil distance becomes shorter, the incident angle becomes larger, and when the exit pupil distance becomes longer, the incident angle becomes smaller. In order to shield a part of light incident at an incident angle different according to the exit pupil distance, the area of the light shielding portion 43 is different according to the AF pixel pair. Thus, the focus detection unit 215 can accurately detect the defocus amount even at different exit pupil distances. However, the pair of pixels around the optical axis OA1 (the center of the imaging surface 22 a) of the imaging optical system 31 has an incident angle of 0 ° regardless of the exit pupil distance. Therefore, the areas of the light shielding portions 43 of the 1 st AF pixel pair, the 2 nd AF pixel pair, and the 3 rd AF pixel pair are the same. Although described later, the area of the light shielding portion 43 differs depending on the position (image height) of the AF pixel.

The 1 st AF pixel 11a, 11b, and 11c and the 2 nd AF pixel 12a, 12b, and 12c each have a color filter having spectral characteristics for splitting light in the 2 nd wavelength range (light of green (G)) out of incident light. The color filters included in the AF pixels of the 1 st AF pixel 11a to 11c and the 2 nd AF pixel 12a to 12c may have spectral characteristics for splitting light in the 1 st wavelength range (red (R) light) or light in the 3 rd wavelength range (blue (B) light). The 1 st AF pixels 11a to 11c and the 2 nd AF pixels 12a to 12c may include color filters having spectral characteristics for splitting light in the 1 st wavelength range, the 2 nd wavelength range, and the 3 rd wavelength range among the incident light.

Fig. 4 is a diagram for explaining a configuration example of AF pixels and imaging pixels provided in the imaging element 22 according to embodiment 1. Fig. 4 (a) shows an example of a cross section of the 1 st AF pixel 11 and the 2 nd AF pixel 12 constituting the AF pixel pair, and fig. 4 (b) shows an example of a cross section of the 2 nd AF pixel 12 of the 1 st AF pixel 11 and the 2 nd AF pixel 12. Fig. 4 (c) shows an example of a cross section of the imaging pixel 13(R pixel, G pixel, B pixel).

In fig. 4, each of the 1 st AF pixel 11, the 2 nd AF pixel 12, and the photographing pixel 13 has a microlens 44, a color filter 51, and a photoelectric conversion portion 42(PD42) that photoelectrically converts light transmitted (passed) through the microlens 44 and the color filter 51. The 1 st light flux 61 is a light flux passing through the 1 st pupil area that approximately bisects the exit pupil of the photographing optical system 31. The 2 nd light flux 62 is a light flux passing through the 2 nd pupil area that approximately bisects the exit pupil of the photographing optical system 31.

In fig. 4 (a), the 1 st AF pixel 11 is provided with a light shielding portion 43L that shields the 2 nd light beam 62 of the 1 st light beam 61 and the 2 nd light beam 62. The light shielding portion 43L is located between the color filter 51 and the photoelectric conversion portion 42, and is provided on the photoelectric conversion portion 42. In the example shown in fig. 4 (a), the light shielding portion 43L is arranged to shield the left half portion (-X direction side) of the photoelectric conversion portion 42 from light. The right end (+ end in the X direction) of the light shielding portion 43L substantially coincides with a center line bisecting the photoelectric conversion portion 42 in the left-right direction. The photoelectric conversion portion 42 of the 1 st AF pixel 11 receives the 1 st light beam 61. The photoelectric conversion portion 42 of the 1 st AF pixel 11 photoelectrically converts the 1 st light beam 61 to generate electric charges, and the 1 st AF pixel 11 outputs the 1 st signal Sig1 based on the electric charges generated in the photoelectric conversion portion 42.

The area of the light shielding portion 43L differs depending on the position (image height) of the 1 st AF pixel 11 except for the 1 st AF pixel 11 around the optical axis OA1 (the center of the imaging surface 22 a) of the imaging optical system 31. When the 1 st AF pixel 11 is different in position, that is, different in image height, the incident angle of light incident to the 1 st AF pixel 11 is different. The incident angle increases when the image height increases, decreases when the image height decreases, and becomes 0 ° when the image height is 0. In order to block the 2 nd light flux 62 out of the light beams incident at the incident angles different according to the image height, the area of the light blocking portion 43L is different according to the image height.

In fig. 4 (b), the 2 nd AF pixel 12 is provided with a light shielding portion 43R that shields the 1 st light beam 61 of the 1 st light beam 61 and the 2 nd light beam 62. The light shielding portion 43R is located between the color filter 51 and the photoelectric conversion portion 42, and is provided on the photoelectric conversion portion 42. In the example shown in fig. 4 (b), the light shielding portion 43R is arranged to shield the right half (+ X direction side) of the photoelectric conversion portion 42 from light. The left end (end in the X direction) of the light shielding portion 43R substantially coincides with the center line bisecting the photoelectric conversion portion 42 in the left-right direction. The photoelectric conversion portion 42 of the 2 nd AF pixel 12 receives the 2 nd light beam 62. The photoelectric conversion portion 42 of the 2 nd AF pixel 12 photoelectrically converts the 2 nd light beam 62 to generate electric charges, and the 2 nd AF pixel 12 outputs the 2 nd signal Sig2 based on the electric charges generated in the photoelectric conversion portion 42.

Similarly to the 1 st AF pixel 11, the area of the light shielding portion 43R differs depending on the position (image height) of the 2 nd AF pixel 12 except for the 2 nd AF pixel 12 around the optical axis OA1 (the center of the imaging surface 22 a) of the imaging optical system 31. In order to block the 1 st light flux 61 out of the light beams incident at different incident angles according to the image height, the area of the light blocking portion 43R is different according to the image height.

In fig. 4 (c), the photoelectric conversion portion 42 of the photographing pixel 13 receives the 1 st and 2 nd light beams 61 and 62 that have passed through the 1 st and 2 nd pupil areas, respectively, of the exit pupil of the photographing optical system 31. The photoelectric conversion portion 42 of the imaging pixel 13 photoelectrically converts the 1 st light beam 61 and the 2 nd light beam 62 to generate electric charges, and the imaging pixel 13 outputs a signal based on the electric charges generated in the photoelectric conversion portion 42.

Fig. 5 is a cross-sectional view of three types of AF pixel pairs arranged in a small area 110a (see fig. 2 (b)) within the focus detection area 100 a. Fig. 5 (a) shows the 1 st AF pixel 11a and the 2 nd AF pixel 12a constituting the 1 st AF pixel pair arranged in the 1 st AF pixel row 403a and the 2 nd AF pixel row 404a of fig. 3, respectively. Fig. 5 (b) shows the 1 st AF pixel 11b and the 2 nd AF pixel 12b constituting the 2 nd AF pixel pair arranged in the 1 st AF pixel row 403b and the 2 nd AF pixel row 404b of fig. 3, respectively. Fig. 5 (c) shows the 1 st AF pixel 11c and the 2 nd AF pixel 12c constituting the 3 rd AF pixel pair arranged in the 1 st AF pixel row 403c and the 2 nd AF pixel row 404c of fig. 3, respectively. As shown in fig. 5, the lines of the 1 st AF pixel 11a to 11c and the 2 nd AF pixel 12a to 12c passing through the center of the photoelectric conversion portion 42 substantially coincide with the optical axis OA2 of the microlens 44. Light incident at an incident angle of 0 ° with respect to the optical axis OA2 of the microlens 44 is condensed on the optical axis OA2 of the microlens. The line passing through the center of the photoelectric conversion portion 42 coincides with the optical axis OA2 of the microlens 44, and thus the light incident on the microlens 44 is condensed on the line passing through the center of the photoelectric conversion portion 42. That is, the light having passed through the imaging optical system 31 is condensed on a line passing through the center of the photoelectric conversion portion 42.

In fig. 5 (a), the right end (+ end in the X direction) of the light shielding portion 43L of the 1 st AF pixel 11a substantially coincides with the optical axis OA2 of the microlens 44. The light-shielding portion 43L of the 1 st AF pixel 11a shields the left half portion (-X direction side) of the photoelectric conversion portion 42 from light. The 2 nd light beam 62 having passed through the microlens 44 is shielded by the light shielding portion 43L before being input to the photoelectric conversion portion 42. Thereby, the photoelectric conversion portion 42 of the 1 st AF pixel 11a receives the 1 st light beam 61. The left end (-end in the X direction) of the light shielding portion 43R of the 2 nd AF pixel 12a substantially coincides with the optical axis OA2 of the microlens 44. The 1 st light beam 61 transmitted through the microlens 44 is shielded by the light shielding portion 43R before entering the photoelectric conversion portion 42. Thereby, the photoelectric conversion portion 42 of the 2 nd AF pixel 12a receives the 2 nd light beam 62.

As shown in fig. 5 (b) and (c), the right end (+ end in the X direction) of the light shielding portion 43L of each of the 1 st AF pixels 11b and 11c substantially coincides with the optical axis OA2 of the microlens 44. Therefore, the photoelectric conversion portions 42 of the 1 st AF pixels 11b and 11c receive the 1 st light beam 61, as in the 1 st AF pixel 11 a. The left end (-end in the X direction) of the light shielding portion 43R of each of the 2 nd AF pixels 12b and 12c substantially coincides with the optical axis OA2 of the microlens 44. Therefore, like the 1 st AF pixel 12a, the photoelectric conversion portions 42 of the 2 nd AF pixels 12b and 12c receive the 2 nd light beam 62.

Fig. 6 is a cross-sectional view of three types of AF pixel pairs arranged in a small region 110c (see fig. 2 (b)) separated from the small region 110a in the focus detection region 100a in the + X direction. Fig. 6 (a) shows the 1 st AF pixel 11a and the 2 nd AF pixel 12a constituting the 1 st AF pixel pair. Fig. 6 (b) shows the 1 st AF pixel 11b and the 2 nd AF pixel 12b constituting the 2 nd AF pixel pair. Fig. 6 (c) shows the 1 st AF pixel 11c and the 2 nd AF pixel 12c constituting the 3 rd AF pixel pair.

In fig. 6, lines passing through the centers of the photoelectric conversion portions 42 of the 1 st AF pixels 11a to 11c and the 2 nd AF pixels 12a to 12c are shifted in the + X direction with respect to the optical axis OA2 of the microlens 44. In the present embodiment, the 1 st AF pixel and the 2 nd AF pixel arranged apart from the small region 110a in the + X direction are shifted in the + X direction with respect to the optical axis OA2 of the microlens 44 by a line passing through the center of the photoelectric conversion portion 42. Further, lines passing through the centers of the photoelectric conversion portions 42 of the 1 st AF pixel and the 2 nd AF pixel arranged apart from the small region 110a in the-X direction are shifted in the-X direction with respect to the optical axis OA2 of the microlens 44.

In fig. 6, the areas of the light shielding portions 43L of the 1 st AF pixels 11a to 11c are different from each other. The area of the light-shielding portion 43L of the 1 st AF pixel 11a is smaller than the area of the light-shielding portion 43L of the 1 st AF pixel 11 b. The area of the light-shielding portion 43L of the 1 st AF pixel 11b is smaller than the area of the light-shielding portion 43L of the 1 st AF pixel 11 c. The areas of the light shielding portions 43R of the 2 nd AF pixels 12a to 12c are different. The area of the light-shielding portion 43R of the 2 nd AF pixel 12a is larger than the area of the light-shielding portion 43R of the 2 nd AF pixel 12 b. The area of the light shielding portion 43R of the 2 nd AF pixel 12b is larger than the area of the light shielding portion 43R of the 2 nd AF pixel 12 c.

In fig. 6, a line passing through the center of the photoelectric conversion portion 42 is shifted from the optical axis OA2 of the microlens 44, and the areas of the light shielding portions 43 of the 1 st AF pixel and the 2 nd AF pixel are different, so that the ends of the light shielding portions of the 1 st AF pixel and the 2 nd AF pixel are shifted from the optical axis OA2 of the microlens 44. In fig. 6 (a), for example, the right end (+ X direction end) of the light shielding portion 43L of the 1 st AF pixel 11a is located at a position shifted from the optical axis OA2 of the microlens 44 by a shift amount d1 in the + X direction. The left end (-end in the X direction) of the light shielding portion 43R of the 2 nd AF pixel 12a is shifted from the optical axis OA2 of the microlens 44 by the shift amount d1 in the + X direction.

As shown in fig. 6, the 2 nd AF pixel pair and the 3 rd AF pixel pair are different in shift amount from the 1 st AF pixel pair. The shift amount d2 of the 1 st AF pixel 11b and the 2 nd AF pixel 12b constituting the 2 nd AF pixel pair is larger than the shift amount d1 of the 1 st AF pixel 11a and the 2 nd AF pixel 12a constituting the 1 st AF pixel pair. The shift amount d3 of the 1 st AF pixel 11c and the 2 nd AF pixel 12c constituting the 3 rd AF pixel pair is larger than the shift amount d2 of the 1 st AF pixel 11b and the 2 nd AF pixel 12b constituting the 2 nd AF pixel pair. Namely, d1 < d2 < d 3.

Fig. 7 is a cross-sectional view of a part of three AF pixel pairs in the focus detection area 100c separated from the focus detection area 100a in the + X direction in fig. 2. Fig. 7 (a) shows the 1 st AF pixel 11a and the 2 nd AF pixel 12a constituting the 1 st AF pixel pair. Fig. 7 (b) shows the 1 st AF pixel 11b and the 2 nd AF pixel 12b constituting the 2 nd AF pixel pair. Fig. 7 (c) shows the 1 st AF pixel 11c and the 2 nd AF pixel 12c constituting the 3 rd AF pixel pair.

Similarly to the three types of AF pixel pairs shown in fig. 6, lines passing through the centers of the photoelectric conversion portions 42 of the 1 st AF pixels 11a to 11c and the 2 nd AF pixels 12a to 12c shown in fig. 7 are shifted in the + X direction with respect to the optical axis OA2 of the microlens 44. In addition, the areas of the light shielding portions 43L of the 1 st AF pixels 11a to 11c are different from each other, similarly to the three types of AF pixel pairs shown in fig. 6. The areas of the light shielding portions 43R of the 2 nd AF pixels 12a to 12c are different.

In addition, the three types of AF pixel pairs shown in fig. 6 and 7 differ in the amount of shift of the line passing through the center of the photoelectric conversion portion 42 with respect to the optical axis OA2 of the microlens 44. In addition, the area of the light shielding portion 43L is different from the area of the light shielding portion 43R except for the 1 st AF pixel 11b and the 2 nd AF pixel 12 b. The three AF pixel pairs shown in fig. 7 are shifted by a larger amount with respect to the optical axis OA2 of the microlens 44 than in fig. 6. In addition, the light shielding portions 43L and 43R of the 1 st and 2 nd AF pixels 11a and 12a shown in fig. 7 have smaller areas and larger areas, respectively, than those of fig. 6. As compared with fig. 6, the light shielding portions 43L and 43R of the 1 st AF pixel 11c and the 2 nd AF pixel 12c shown in fig. 7 have larger areas and smaller areas. The 1 st AF pixel 11b and the 2 nd AF pixel 12b shown in fig. 7 have the same area as the light shielding portion 43L and the same area as the light shielding portion 43R in fig. 6.

The right end (+ end in the X direction) of the light shielding portion 43L of the 1 st AF pixel 11a is shifted in the + X direction by a shift amount d4 with respect to the optical axis OA2 of the microlens 44. The left end (-end in the X direction) of the light shielding portion 43R of the 2 nd AF pixel 12a is shifted in the + X direction by a shift amount d4 with respect to the optical axis OA2 of the microlens 44.

The 2 nd AF pixel pair and the 3 rd AF pixel pair are different in shift amount from the 1 st AF pixel pair. The shift amount d5 of the 1 st AF pixel 11b and the 2 nd AF pixel 12b constituting the 2 nd AF pixel pair is larger than the shift amount d4 of the 1 st AF pixel 11a and the 2 nd AF pixel 12a constituting the 1 st AF pixel pair. The shift amount d6 of the 1 st AF pixel 11c and the 2 nd AF pixel 12c constituting the 3 rd AF pixel pair is larger than the shift amount d5 of the 1 st AF pixel 11b and the 2 nd AF pixel 12b constituting the 2 nd AF pixel pair. Namely, d4 < d5 < d 6.

As shown in fig. 5, 6, and 7, the shift amount between the line passing through the center of the photoelectric conversion portion 42 and the optical axis OA2 of the microlens 44 differs depending on the image height. The higher the image height, the larger the shift amount, and the lower the image height, the smaller the shift amount. At the position of the image height, the light having passed through the imaging optical system 31 enters the microlens 44 obliquely. That is, light is incident at an incident angle greater than 0 ° with respect to the optical axis OA2 of the microlens 44. Therefore, it can be said that the shift amount increases as the incident angle of light to the microlens 44 increases. Light incident at an incident angle larger than 0 ° with respect to the optical axis OA2 of the microlens 44 is collected by being shifted in the + X direction or the-X direction from the optical axis OA2 of the microlens. The line passing through the center of the photoelectric conversion portion 42 is shifted from the optical axis OA2 of the microlens 44, and thus the light incident on the microlens 44 is condensed on the line passing through the center of the photoelectric conversion portion 42. That is, the light transmitted through the imaging optical system 31 is condensed on a line passing through the center of the photoelectric conversion portion 42. This can increase the amount of light that passes through the imaging optical system 31 and enters the photoelectric conversion portion 42.

As shown in fig. 5, 6, and 7, the area of the light shielding portion 43 differs depending on the AF pixel pair. As described above, the exit pupil distance of the photographing optical system 31 differs depending on the kind of the interchangeable lens 3. Therefore, the 1 st AF pixel pair, the 2 nd AF pixel pair, and the 3 rd AF pixel pair each have light-shielding portions 43 having different areas in order to accurately detect the defocus amount at different exit pupil distances. The area of the light-shielding portion 43L and the area of the light-shielding portion 43R included in the 1 st AF pixel pair differ depending on the position (image height) at which the 1 st AF pixel pair is arranged. As described above, the exit pupil distance of the photographing optical system 31 differs according to the image height. Therefore, the 1 st AF pixel pair has the light-shielding portions 43L and 43R having areas that vary according to the image height in order to accurately detect the defocus amount at different exit pupil distances. The 3 rd AF pixel pair is also the same as the 1 st AF pixel pair. Thus, the focus detection unit 215 can accurately detect the defocus amount even at different exit pupil distances. That is, even if the image height or the type of interchangeable lens changes, the focus detection unit 215 can accurately detect the defocus amount.

Therefore, the amount of shift of the optical axes of the light shielding portion 43 and the microlens 44 of the 1 st to 3 rd AF pixel pairs is larger as the image becomes higher in the + X direction from the small region 110a in fig. 2 (b). The following is a comparison of the shift amounts of the 1 st to 3 rd AF pixel pairs in the three regions having heights of Ha, Hb, and Hc (Ha < Hb < Hc). The shift amount of the 1 st AF pixel pair in the region of the image height Hb is larger than that of the 1 st AF pixel pair in the region of the image height Ha and is smaller than that of the 1 st AF pixel pair in the region of the image height Hc. Similarly, the shift amounts of the 2 nd AF pixel pair and the 3 rd AF pixel pair in the image height Hb region are larger than those of the 2 nd AF pixel pair and the 3 rd AF pixel pair in the image height Ha region, and are smaller than those of the 2 nd AF pixel pair and the 3 rd AF pixel pair in the image height Hc region. The shift amount d4 of the 1 st AF pixel pair arranged in the focus detection area 100c shown in fig. 7 is larger than the shift amount d1 of the 1 st AF pixel pair arranged in the small area 110c shown in fig. 6. The shift amounts d5, d6 of the 2 nd AF pixel and the 3 rd AF pixel pair arranged in the focus detection area 100c shown in fig. 7 are larger than the shift amounts d2, d3 of the 2 nd AF pixel pair and the 3 rd AF pixel pair arranged in the small area 110c shown in fig. 6, respectively.

The 1 st to 3 rd AF pixel pairs arranged in the small region 110b separated from the small region 110a in the-X direction in fig. 2 (b) are provided with the same shift amounts d1 to d3 in the direction opposite to the shift direction shown in fig. 6. In the 1 st to 3 rd AF pixel pairs arranged in the focus detection area 100b of fig. 2 (a), the same shift amounts as the shift amounts d4 to d6 are applied in the direction opposite to the shift direction shown in fig. 7. The larger the image height, the larger the shift amount of the 1 st to 3 rd AF pixel pairs arranged apart from the small region 110a in the-X direction.

As described above, the 1 st AF pixel pair to the 3 rd AF pixel pair are different in shift amount. Therefore, in a plane intersecting the direction in which light enters, the areas of the photoelectric conversion portions 42 of the 1 st AF pixels 11a to 11c that receive light are different from each other, and the areas of the photoelectric conversion portions 42 of the 2 nd AF pixels 12a to 12c that receive light are different from each other. As described above, in the present embodiment, the light receiving areas of the photoelectric conversion portions 42 of the 1 st AF pixel pair to the 3 rd AF pixel pair are different, and therefore pupil division can be performed in accordance with different incident angles. Thus, the focus detection unit 215 can accurately detect the defocus amount.

Next, an example of a method for determining the shift amount of the 1 st to 3 rd AF pixel pairs in the focus detection area 100 will be described. In fig. 8, a position of the small region 110 located at the image height Hd from a position 0 (a center position of the imaging surface 22 a) where the optical axis OA1 of the imaging optical system 31 intersects the imaging surface 22a of the imaging element 22 is denoted by 110 α. The 1 st, 2 nd, and 3 rd reference exit pupils EP1, EP2, and EP3 are set on the optical axis OA1 of the photographing optical system 31. The 2 nd reference exit pupil EP2 is located closer to the imaging surface 22a than the 1 st reference exit pupil EP1 is, and is located on the + Z direction side than the 1 st reference exit pupil EP1 is. The 3 rd reference exit pupil EP3 is located closer to the imaging surface 22a than the 2 nd reference exit pupil EP2 is, and is located on the + Z direction side than the 2 nd reference exit pupil EP2 is.

The distance between the 1 st reference exit pupil EP1 and the imaging surface 22a is defined as a1 st reference exit pupil distance Po1, the distance between the 2 nd reference exit pupil EP2 and the imaging surface 22a is defined as a2 nd reference exit pupil distance Po2, and the distance between the 3 rd reference exit pupil EP3 and the imaging surface 22a is defined as a 3 rd reference exit pupil distance Po 3. Further, Po1 > Po2 > Po 3.

In fig. 8, L1 denotes a principal ray of a light beam incident through the 1 st reference exit pupil EP1 to the AF pixel within the small area 110 at the position 110 α. L2 denotes a principal ray of a light beam incident through the 2 nd reference exit pupil EP2 to the AF pixel in the small area 110 at the position 110 α. L3 denotes a principal ray of the light beam incident through the 3 rd reference exit pupil EP3 to the AF pixel in the small area 110 at the position 110 α.

In fig. 8, when θ 1 is an incident angle of the principal ray L1 to the AF pixel, the shift amount of the 1 st AF pixel pair in the small region 110 of the image height Hd is determined based on the incident angle θ 1. Similarly, when θ 2 and θ 3 are set as incident angles of the principal rays L2 and L3 to the AF pixels, respectively, the shift amounts of the 2 nd AF pixel pair and the 3 rd AF pixel pair in the small region 110 of the image height Hd are determined based on the incident angles θ 2 and θ 3, respectively. As described above, the larger the incident angle, the larger the shift amount. In addition, except for the position (position 0) where the image height is 0, the longer the exit pupil distance, the smaller the incident angle, and therefore, θ 1 < θ 2 < θ 3. Therefore, the shift amounts d1, d2, and d3 of the 1 st AF pixel pair, the 2 nd AF pixel pair, and the 3 rd AF pixel pair shown in (a) to (c) of fig. 6 are d1 < d2 < d 3. Note that the shift amounts d4, d5, and d6 of the 1 st AF pixel pair, the 2 nd AF pixel pair, and the 3 rd AF pixel pair shown in (a) to (c) of fig. 7 are d4 < d5 < d 6.

In this way, the shift amount of the 1 st AF pixel pair with respect to the 1 st reference exit pupil EP 1(1 st reference exit pupil distance Po1) is determined. Similarly, the shift amount of the 2 nd AF pixel pair from the 2 nd reference exit pupil EP2 (the 2 nd reference exit pupil distance Po2) is determined, and the shift amount of the 3 rd AF pixel pair from the 3 rd reference exit pupil EP3 (the 3 rd reference exit pupil distance Po3) is determined.

Next, the relationship between the exit pupil distance of the photographing optical system 31 and the 1 st to 3 rd AF pixel pairs will be described. In fig. 8, the 1 st threshold Th1 relating to the exit pupil distance is set at the intermediate position between the 1 st reference exit pupil EP1 and the 2 nd reference exit pupil EP2, and the 2 nd threshold Th2 relating to the exit pupil distance is set at the intermediate position between the 2 nd reference exit pupil EP2 and the 3 rd reference exit pupil EP 3. An area where the exit pupil distance is equal to or greater than the 1 st threshold Th1 is defined as a1 st exit pupil distance range R1, an area where the exit pupil distance is between the 1 st threshold Th1 and the 2 nd threshold Th2 is defined as a2 nd exit pupil distance range R2, and an area where the exit pupil distance is equal to or less than the 2 nd threshold Th2 is defined as a 3 rd exit pupil distance range R3.

The pixel selection unit 213 selects the 1 st AF pixel pair when the exit pupil distance of the photographing optical system 31 is equal to or greater than the 1 st threshold Th1, that is, when the distance falls within the 1 st exit pupil distance range R1. The pixel selection unit 213 selects the 2 nd AF pixel pair when the exit pupil distance of the photographing optical system 31 is between the 1 st threshold Th1 and the 2 nd threshold Th2, that is, when it belongs to the 2 nd exit pupil distance range R2. The pixel selection unit 213 selects the 3 rd AF pixel pair when the exit pupil distance of the photographing optical system 31 is equal to or less than the 2 nd threshold Th2, that is, when the 3 rd exit pupil distance range R3 is included.

As described above, the pixel selection section 213 selects an appropriate AF pixel pair from the 1 st AF pixel pair to the 3 rd AF pixel pair according to which of the 1 st exit pupil distance range R1 to the 3 rd exit pupil distance range R3 the exit pupil distance of the photographing optical system belongs to.

Next, the optical characteristics of the photographing optical system 31 of the interchangeable lens 3, that is, the optical characteristics in which the exit pupil distance changes depending on the image height will be described. Fig. 9 shows optical characteristics of the interchangeable lens 3 attached to the camera body 2 of fig. 1 in which the exit pupil distance changes according to the image height. In fig. 9, the horizontal axis represents the exit pupil distance Po, and the vertical axis represents the image height H. Fig. 9 (a), (b), (c), and (d) show optical characteristics of interchangeable lenses of different types. The optical characteristics of the photographing optical system 31 of the interchangeable lens 3 shown in fig. 9 (a) are represented by an optical characteristic curve 200a, and the exit pupil distance Po becomes smaller as the image height H becomes larger. The optical characteristic curve 200a of fig. 9 (a) shows: the exit pupil distance is Poa at zero image height, becomes gradually smaller as the image height H becomes larger, and becomes (Poa- Δ p1) at the maximum image height Hmax.

The optical characteristics of the photographing optical system 31 of the interchangeable lens 3 shown in fig. 9 (b) are represented by an optical characteristic curve 200b, and the exit pupil distance Po becomes larger as the image height H becomes larger. The optical characteristic curve 200b of fig. 9 (b) shows: the exit pupil distance is Pob at zero image height, becomes gradually larger as the image height H becomes larger, and becomes (Pob + Δ p2) at the maximum image height Hmax.

In the following description, an optical characteristic curve in which the exit pupil distance Po becomes small as the height H becomes large, like the optical characteristic curve 200a, is referred to as a negative optical characteristic curve. In addition, an optical characteristic curve in which the exit pupil distance Po becomes larger as the height H becomes larger, like the optical characteristic curve 200b, is referred to as a positive optical characteristic curve.

The photographing optical system 31 of the interchangeable lens 3 shown in fig. 9 (c) is a photographing optical system whose optical characteristic curve differs, i.e., changes, depending on the position of the focus lens 31b of fig. 1. The photographing optical system 31 exhibits an optical characteristic 200c when the focus lens 31b is at the 1 st position, and exhibits an optical characteristic 200d when the focus lens 31b is at the 2 nd position. The 1 st position and the 2 nd position of the focus lens 31b are arbitrary positions between the infinity position and the very close position including the infinity position and the very close position of the focus lens 31 b. The infinity position of the focus lens 31b is a position for focusing on a subject at an infinity distance, and the very close position is a position for focusing on a subject at a very close distance.

In fig. 9 (c), an optical characteristic curve 200c represents the optical characteristics of the photographing optical system 31 when the focus lens 31b is located at the 1 st position. The optical characteristic 200c represents: the exit pupil distance is Poc at zero image height, gradually decreases as the image height H increases, and becomes (Poc- Δ p3) at the maximum image height Hmax. The optical characteristic curve 200d represents the optical characteristic of the photographing optical system 31 when the focus lens 31b is located at the 2 nd position. The optical characteristic 200d represents: the exit pupil distance is Pod at zero image height, gradually increases as the image height H increases, and becomes (Pod + Δ p4) at the maximum image height Hmax.

In fig. 9 (c), the optical characteristic curve 200c when the focus lens 31b is at the 1 st position is represented as a negative optical characteristic curve, and the optical characteristic curve 200d when the focus lens 31b is at the 2 nd position is represented as a positive optical characteristic curve. However, there is also an interchangeable lens 3 having optical characteristics in which both the optical characteristic curve 200c and the optical characteristic curve 200d are positive or negative.

The photographing optical system 31 of the interchangeable lens 3 shown in fig. 9 (d) is a photographing optical system whose optical characteristic curve differs, i.e., changes, according to the focal length of the zoom lens (the position of the zoom lens 31a of fig. 1). The photographing optical system 31 exhibits an optical characteristic curve 200e at a focal length f1 and an optical characteristic curve 200f at a focal length f 2.

In fig. 9 (d), an optical characteristic curve 200e represents the optical characteristics of the photographing optical system 31 when the focal length is f 1. The optical characteristic 200e represents: the exit pupil distance is Poe at zero image height, gradually decreases as the image height H increases, and becomes (Poe- Δ p5) at the maximum image height Hmax. The optical characteristic curve 200f represents the optical characteristic of the photographing optical system 31 at the focal length f 2. The optical characteristic 200f represents: the exit pupil distance is Pof at zero image height, becomes gradually larger as the image height H becomes larger, and becomes (Pof + Δ p6) at the maximum image height Hmax.

In fig. 9 (d), the optical characteristic curve 200e at the focal length f1 is represented as a negative optical characteristic curve, and the optical characteristic curve 200f at the focal length f2 is represented as a positive optical characteristic curve. However, there is also an interchangeable lens 3 having optical characteristics in which both the optical characteristic curve 200e and the optical characteristic curve 200f are positive or negative.

Note that the exit pupil distance Po at the image height H in the above description is the distance of the exit pupil of the photographing optical system 31 viewed from the image height H of the photographing surface 22 a. In other words, the exit pupil distance Po at the image height H is the distance of the exit pupil of the photographing optical system 31 (distance from the photographing surface 22 a) through which the light flux that has passed through the photographing optical system 31 and entered the position of the image height H of the photographing surface 22a passes.

Fig. 10 shows the relationship between the image height H and the exit pupil distance Po. In fig. 10, the light flux having passed through the exit pupil EPa (exit pupil distance Poa) of the photographing optical system 31 enters the AF pixel (the microlens 44 is illustrated in fig. 10 to represent the AF pixel) located at the center position 0 (the image height is zero) of the photographing surface 22 a. The exit pupil distance Poa of the exit pupil EPa is the exit pupil distance relative to the exit pupil EPa with an image height of zero.

Further, the light flux having passed through the exit pupil EPb of the photographing optical system 31 enters the AF pixel (the microlens 44 is illustrated in fig. 10 to represent the AF pixel) located at the image height He. The exit pupil distance (Poa- Δ p) of the exit pupil EPb is the exit pupil distance of the exit pupil EPb relative to the image height H.

Here, the relationship between the optical characteristics of each interchangeable lens 3 and the above equation (1) will be described. Po (H) ═ H4 × H of formula (1) above⁴+h2×H ²The + Co is a function for approximating the optical characteristic curves 200a, 200b, 200c, 200d, 200e, 200f and the like shown in fig. 9 (a) to 9 (d). The optical characteristic curve 200a in fig. 9 (a) is approximated by the calculation of equation (1) by setting the constant term Co of the calculation equation (1) to the exit pupil distance Poa at which the image height in fig. 9 (a) is zero and setting the coefficients h4 and h2 to the coefficients h4a and h2a corresponding to the curve (curve) of the optical characteristic curve 200 a. The interchangeable lens 3 having the optical characteristics of fig. 9 (a) stores the constant term Poa and the coefficients h4a and h2a as lens information in the lens memory 33 as described above.

Similarly, the interchangeable lens 3 having the optical characteristic shown in fig. 9 (b) stores the constant term Pob and the coefficients h4b and h2b, which determine the operation of the expression (1) for approximating the optical characteristic curve 200b, in the lens memory 33 as lens information.

The interchangeable lens 3 in fig. 9 (c) has an optical characteristic in which an optical characteristic curve changes depending on the position of the focus lens 31 b. The interchangeable lens 3 stores the constant term Co and the coefficients h4 and h2 obtained by the calculation of expression (1) for approximating the optical characteristic curve at each position of the focus lens 31b in the lens memory 33. The range in which the focus lens 31b moves (between the infinity position and the close position) is divided into a plurality of zones Z1 to Zn, and one optical characteristic curve representing the zone (range) is specified for each of the zones Z1 to Zn. For example, an optical characteristic curve when the focus lens 31b is at the center position of one section is taken as an optical characteristic curve representing the section.

The optical characteristic curve of the representative section Zk is referred to as an optical characteristic curve Zk (k is 1, 2, … …, n). The constant term Co and the coefficients h4 and h2 of the calculation of expression (1) that approximates the representative optical characteristic curve Z1 of the section Z1 are Poz1, h4Z1, and h2Z 1. The constant term Co and the coefficients h4 and h2 of the calculation of expression (1) that approximates the optical characteristic curve Z2 of the section Z2 are Poz2, h4Z2, and h2Z2, respectively. Similarly, the constant term Co and the coefficients h4 and h2 are set to Pozn, h4Zn, and h2Zn, respectively, for the calculation of expression (1) that approximates the optical characteristic curve Zn of the interval Zn. Fig. 11 shows constant terms and coefficients for these intervals and for the calculation of approximating the optical characteristic curve representing the interval. The interchangeable lens 3 stores the relationships between the zones Z1 to Zn and the constant terms Poz1 to Pozn and the coefficients h4Z1 to h4Zn and h2Z1 to h2Zn shown in fig. 11 in the lens memory 33 as lens information.

The interchangeable lens 3 in fig. 9 (d) is a zoom lens having optical characteristics in which an optical characteristic curve changes according to a focal length. The interchangeable lens 3 stores the constant term Co and the coefficients h4 and h2 obtained by the operation of expression (1) for approximating the optical characteristic curve of each focal length in the lens memory 33. The interval between the maximum focal length and the minimum focal length of the zoom lens set by the zoom lens 31a of fig. 1 is divided into a plurality of intervals W1 to Wn, and one optical characteristic curve representing the interval is determined for each of the intervals W1 to Wn. For example, an optical characteristic curve at a focal length in the middle of one interval is taken as an optical characteristic curve representing the interval.

The optical characteristic curve of the representative section Wk is referred to as an optical characteristic curve Wk (k is 1, 2, … …, n). The constant term Co and the coefficients h4 and h2 of the calculation of expression (1) that approximates the optical characteristic curve W1 of the section W1 are Pow1, h4W1, and h2W1, respectively. The constant term Co and the coefficients h4 and h2 of the calculation of expression (1) that approximates the optical characteristic curve W2 of the section W2 are Pow2, h4W2, and h2W2, respectively. Similarly, the constant term Co and the coefficients h4 and h2 are set to Pown, h4Wn, and h2Wn, respectively, for the calculation of expression (1) that approximates the optical characteristic curve Wn of the section Wn. Fig. 12 shows constant terms and coefficients for these intervals and for the calculation of approximating the optical characteristic curve representing the interval. The interchangeable lens 3 stores the relationships between the sections W1 to Wn shown in fig. 12 and the constant terms Pow1 to Pown and the coefficients h4W1 to h4Wn and h2W1 to h2Wn as lens information in the lens memory 33.

Further, the interchangeable lens 3 of fig. 9 (d) is a zoom lens having optical characteristics in which an optical characteristic curve varies depending on a focal length, but the other zoom lenses have optical characteristics in which an optical characteristic curve varies depending on a focal length, and further an optical characteristic curve also varies depending on a position of the focus lens 31 b. That is, the optical characteristic curves of the other zoom lenses vary depending on both the position (focal length) of the zoom lens 31a and the position of the focus lens 31 b.

Next, the relationship between the optical characteristic curve of the optical characteristic of the interchangeable lens 3 shown in fig. 9 and the 1 st to 3 rd exit pupil distance ranges R1 to R3 shown in fig. 8 will be described. Fig. 13 shows the 1 st and 2 nd threshold values Th1 and Th2, the 1 st to 3 rd exit pupil distance ranges R1 to R3, and the optical characteristic curves illustrated in fig. 9, which are related to the exit pupil distance shown in fig. 8. In fig. 13, the entire curve of the optical characteristic curve 200g, that is, the exit pupil distance from the image height zero to the maximum image height Hmax is within the 2 nd exit pupil distance range R2. When the interchangeable lens 3 having the optical characteristic curve 200g is attached to the camera body 2, the pixel selection unit 213 selects the 2 nd AF pixel pair regardless of the image height H of the focus detection area 100 set by the area setting unit 211.

The exit pupil distance from the image height of zero to the image height Hf of the optical characteristic curve 200h falls within the 2 nd exit pupil distance range R2, but the exit pupil distance from the image height Hf to the maximum image height Hmax falls within the 1 st exit pupil distance range R1. The pixel selection unit 213 selects the 2 nd AF pixel pair when the area setting unit 211 sets the focus detection area 100 having the image height Hf or less, and selects the 1 st AF pixel pair when the area setting unit 211 sets the focus detection area having the image height Hf greater than the image height Hf.

The exit pupil distance from the image height of zero to the image height Hg of the optical characteristic curve 200i falls within the 3 rd exit pupil distance range R3, but the exit pupil distance from the image height Hg to the maximum image height Hmax falls within the 2 nd exit pupil distance range R2. The pixel selection unit 213 selects the 3 rd AF pixel pair when the area setting unit 211 sets the focus detection area 100 having the image height of Hg or less, and selects the 2 nd AF pixel pair when the area setting unit 211 sets the focus detection area having the image height of Hg greater than the image height.

In addition, as described above, when the plurality of focus detection areas 100 are set by the area setting unit 211, the pixel selection unit 213 selects the same type of AF pixel pair in each of the selected focus detection areas 100. In this case, the pixel selection unit 213 selects an AF pixel pair based on the position of the focus detection area 100 farthest from the optical axis OA1 of the photographing optical system 31 (highest image height H) among the plurality of selected focus detection areas 100. In the present embodiment, the pixel selection unit 213 selects the AF pixel pair as described above, based on the image height of the focus detection area 100 having the highest image height among the plurality of selected focus detection areas 100. The pixel selection unit 213 selects, in the other focus detection areas 100, the same kind of AF pixel pair as the AF pixel pair selected in the focus detection area 100 having the highest image height among the plurality of selected focus detection areas 100.

The circuit configuration and operation of the imaging element 22 according to embodiment 1 will be described with reference to fig. 14 and 15. Fig. 14 is a diagram showing a pixel structure of the imaging element 22 according to embodiment 1. The pixel 13 includes a photoelectric conversion unit 42, a transfer unit 52, a reset unit 53, a floating diffusion (fd) 54, an amplifier 55, and a selection unit 56. The photoelectric conversion unit 42 is a photodiode PD, and converts incident light into electric charges and accumulates the electric charges obtained by photoelectric conversion.

The transfer section 52 is constituted by a transistor M1 controlled by a signal TX, and transfers electric charges photoelectrically converted in the photoelectric conversion section 42 to the FD 54. The transistor M1 is a pass transistor. The capacitance C of the FD54 accumulates (holds) the charge transferred to the FD 54.

The amplification unit 55 outputs a signal based on the charge accumulated in the capacitor C of the FD 54. The amplification section 55 and the selection section 56 constitute an output section that generates and outputs a signal based on the electric charge generated by the photoelectric conversion section 42.

The reset unit 53 is formed of a transistor M2 controlled by a signal RST, and discharges the electric charge accumulated in the FD54 to reset the voltage of the FD 54. The transistor M2 is a reset transistor.

The selection unit 56 is composed of a transistor M4 controlled by a signal SEL, and electrically connects or disconnects the amplification unit 55 to or from the vertical signal line 60. The transistor M4 is a selection transistor.

As described above, the electric charges photoelectrically converted by the photoelectric conversion portion 42 are transferred to the FD54 by the transfer portion 52. Then, a signal corresponding to the electric charge transferred to the FD54 is output to the vertical signal line 60. The pixel signal is an analog signal generated based on the electric charges photoelectrically converted by the photoelectric conversion portion 42. The signal output from the imaging pixel 13 is converted into a digital signal and then output to the body control unit 210.

In this embodiment, the circuit configuration of the 1 st AF pixel 11(11a to 11c) and the 2 nd AF pixel 12(12a to 12c) is the same as that of the imaging pixel 13. The signals output from the 1 st AF pixel 11 and the 2 nd AF pixel 12 are converted into digital signals, and then output to the body control section 210 as a pair of signals (the 1 st signal Sig1 and the 2 nd signal Sig2) used in focus detection.

Fig. 15 is a diagram showing a configuration example of an imaging element according to embodiment 1. The imaging element 22 includes a plurality of imaging pixels 13, 1 st AF pixels 11, and 2 nd AF pixels 12, a vertical control section 70, and a plurality of column circuit sections 80. In fig. 15, for the sake of simplifying the description, only 128 pixels of 8 pixels in the row direction (± X direction) by 16 pixels in the column direction (± Y direction) are illustrated. In fig. 15, the pixel at the upper left corner is defined as the imaging pixel 13(1, 1) at the 1 st row and 1 st column, and the imaging pixel at the lower right corner is defined as the imaging pixel 13(16, 8) at the 16 th row and 8 th column. The imaging element 22 is provided with a plurality of vertical signal lines 60 (vertical signal lines 60a to 60 h). The plurality of vertical signal lines 60 are connected to pixel columns (1 st column to 8 th column) which are columns of a plurality of pixels arranged in a column direction, that is, a vertical direction. The vertical signal lines 60a, 60c, 60e, and 60g connect a plurality of imaging pixels 13 arranged in the same column, and output signals of the connected imaging pixels 13, respectively. The vertical signal lines 60b, 60d, 60f, and 60h connect the plurality of imaging pixels 13, the plurality of 1 st AF pixels 11, and the plurality of 2 nd AF pixels 12 arranged in the same column, and output signals of the connected imaging pixels 13, 1 st AF pixels 11, and 2 nd AF pixels 12, respectively.

The vertical control section 70 is provided in common to a plurality of pixel columns. The vertical control unit 70 supplies the signal TX, the signal RST, and the signal SEL shown in fig. 14 to each pixel, and controls the operation of each pixel. The vertical control unit 70 supplies a signal to the gate of each transistor of the pixel to set the transistor in an ON state (a connected state, a conductive state, a short-circuited state) or an OFF state (a disconnected state, a non-conductive state, an open state, or an open state).

The column circuit unit 80 includes an analog/digital conversion unit (AD conversion unit), and converts an analog signal input from each pixel via the vertical signal line 60 into a digital signal and outputs the digital signal. The signal of the pixel converted into a digital signal is input to a signal processing unit, not shown, subjected to signal processing such as correlated double sampling and signal amount correction, and then output to the body control unit 210 of the camera 1.

The readout unit 214 of the camera 1 controls the vertical control unit 70 to perform a1 st readout mode in which signals of the respective pixels are read out by sequentially selecting all the pixel rows, and a2 nd readout mode in which reading out of signals of the respective pixels of the AF pixel row and reading out of signals of the respective pixels of the imaging pixel row are separately performed.

When the 1 st readout mode is set by the readout unit 214, the vertical control unit 70 sequentially selects a plurality of pixel rows so that signals are output from the pixels. In fig. 15, the vertical control unit 70 sequentially selects the shooting pixel rows 401 and 402 and the AF pixel rows 403a, 404a, 403b, and 404b from the 1 st row to the 16 th row. The vertical control section 70 causes signals to be output from each pixel of the selected shooting pixel row or AF pixel row to the vertical signal line 60. The readout section 214 reads out the signal output to the vertical signal line 60. An example of a signal reading method in the 1 st reading mode will be described below.

First, the vertical control section 70 turns ON the selection sections 56 of the R pixels 13(1, 1) to G pixels 13(1, 8) as the pixels of the 1 st imaging pixel row 401 in the 1 st row, respectively. The vertical control section 70 turns OFF the selection sections 56 of the pixels in the rows other than the 1 st row. Thereby, signals of the R pixels 13(1, 1) to G pixels 13(1, 8) in the 1 st row are output to the vertical signal lines 60a to 60h connected to the respective pixels via the selection portions 56 of the respective pixels. The readout section 214 reads out signals output from the R pixels 13(1, 1) to G pixels 13(1, 8) to the vertical signal line 60.

Next, the vertical control section 70 turns ON the selection section 56 of the G pixel 13(2, 1) -1 AF pixel 11a (2, 8), which is the pixel of the 1 st AF pixel row 403a in the 2 nd row. The vertical control unit 70 turns OFF the selection unit 56 of the pixels in the other rows than the 2 nd row. Thereby, signals of the G pixel 13(2, 1) to the 1 st AF pixel 11a (2, 8) in the 2 nd row are output to the vertical signal line 60a to the vertical signal line 60h, respectively. The readout section 214 reads out signals output from the G pixels 13(2, 1) to the 1 st AF pixels 11a (2, 8) in the 2 nd row to the vertical signal line 60.

Similarly, the vertical control unit 70 sequentially selects pixel rows after the 3 rd row (the 1 st imaging pixel row 401, the 2 nd imaging pixel row 402, the 1 st AF pixel row 403, and the 2 nd AF pixel row 404) in the order of the 3 rd row, the 4 th row, the 5 th row, and the 6 th row, one by one. The vertical control section 70 causes signals to be output from each pixel of the selected shooting pixel row or AF pixel row to the vertical signal line 60. The readout section 214 reads out the signal output to the vertical signal line 60.

In this way, in the 1 st readout mode, the readout section 214 reads out signals from the pixels in all the pixel rows. The signals read from the respective pixels are subjected to signal processing by the column circuit unit 80 and the like, and then output to the body control unit 210.

When the 2 nd readout mode is set by the readout unit 214, the vertical control unit 70 separately outputs the signal of each pixel in the AF pixel row to the vertical signal line 60 and outputs the signal of each pixel in the imaging pixel row to the vertical signal line 60. In the present embodiment, the vertical control section 70 first sequentially selects only AF pixel rows so that signals are output from the respective pixels of the selected AF pixel rows to the vertical signal lines 60. Then, the vertical control section 70 sequentially selects the imaging pixel row so that a signal is output from each pixel of the selected imaging pixel row to the vertical signal line 60. The readout section 214 first reads out only signals output from the respective pixels of the AF pixel row to the vertical signal line 60, and then reads out signals output from the respective pixels of the imaging pixel row to the vertical signal line 60.

An example of a signal reading method in the 2 nd reading mode will be described below. Further, the vertical control unit 70 selects an AF pixel row in which the AF pixel pair selected by the pixel selection unit 213 is arranged in the focus detection area(s) 100 set by the area setting unit 211. In the example shown below, it is assumed that the 1 st AF pixel pair is selected by the pixel selection unit 213 based on the exit pupil distance of the photographing optical system 31.

First, the vertical control section 70 turns ON the selection sections 56 of the G pixels 13(2, 1) to 1AF pixels 11a (2, 8) constituting the 1 st AF pixel row 403a of the 2 nd row shown in fig. 15, respectively. The vertical control unit 70 turns OFF the selection units 56 of the pixels in the rows other than row 2. Thus, the signals of the G pixel 13(2, 1) to the 1 st AF pixel 11a (2, 8) are output to the vertical signal lines 60a to 60h connected to the respective pixels via the selection portions 56 of the respective pixels. The readout section 214 reads out signals output from the G pixel 13(2, 1) to the 1 st AF pixel 11a (2, 8) to the vertical signal line 60.

Next, the vertical control section 70 turns ON the selection section 56 of the G pixel 13(6, 1) to the 2 nd AF pixel 12a (6, 8) constituting the 2 nd AF pixel row 404a of the 6 th row shown in fig. 15. The vertical control unit 70 turns OFF the selection unit 56 of the pixels in the rows other than row 6. Thereby, signals of the G pixel 13(6, 1) to the 2 nd AF pixel 12a (6, 8) are output to the vertical signal line 60a to the vertical signal line 60h, respectively. The readout section 214 reads out signals output from the G pixel 13(6, 1) to the 2 nd AF pixel 12a (6, 8) to the vertical signal line 60.

Although not shown, the 1 st AF pixel row 403a and the 2 nd AF pixel row 404a are also arranged in a plurality of rows after the 16 th row. The vertical control portion 70 sequentially selects only the plurality of 1 st AF pixel rows 403a and 2 nd AF pixel rows 404a in the column direction (+ Y direction). The vertical control portion 70 causes signals to be output from the respective pixels constituting the selected 1 st AF pixel row 403a and 2 nd AF pixel row 404a to the vertical signal line 60. The readout section 214 reads out signals output from the G pixel 13, the 1 st AF pixel 11a, and the 2 nd AF pixel 12a to the vertical signal line 60. The signals sequentially read from the respective AF pixel rows are subjected to signal processing by the column circuit section 80 and the like, and then output to the main body control section 210.

After reading out the signals from the respective pixels of the AF pixel row, the vertical control section 70 sequentially selects the shooting pixel rows in the column direction (+ Y direction). The vertical control section 70 causes signals to be output from the pixels of the selected imaging pixel row to the vertical signal line 60. The readout section 214 reads out signals output from the pixels in the imaging pixel row to the vertical signal line 60. The vertical control section 70 turns ON the selection section 56 of the R pixels 13(1, 1) to G pixels 13(1, 8) constituting the 1 st imaging pixel row 401 of the 1 st row shown in fig. 15. The vertical control unit 70 turns OFF the selection unit 56 of the pixels in the rows other than row 1. Thereby, signals of the R pixels 13(1, 1) to the G pixels 13(1, 8) are output to the vertical signal lines 60a to 60h, respectively. The readout section 214 reads out signals output from the R pixels 13(1, 1) to G pixels 13(1, 8) to the vertical signal line 60.

Next, the vertical control section 70 turns ON the selection section 56 of the R pixel 13(3, 1) to G pixel 13(3, 8) constituting the 1 st imaging pixel row 401 of the 3 rd row shown in fig. 15. The vertical control unit 70 turns OFF the selection unit 56 of the pixels in the rows other than row 3. Thereby, signals of the R pixels 13(3, 1) to the G pixels 13(3, 8) are output to the vertical signal lines 60a to 60h, respectively. The readout section 214 reads out signals output from the R pixels 13(3, 1) to G pixels 13(3, 8) to the vertical signal line 60.

Further, the vertical control section 70 turns ON the selection section 56 of the G pixel 13(4, 1) to the B pixel 13(4, 8) constituting the 1 st imaging pixel row 402 of the 4 th row shown in fig. 15. The vertical control unit 70 turns OFF the selection unit 56 of the pixels in the row other than row 4. Thereby, signals of the G pixel 13(4, 1) to the B pixel 13(4, 8) are output to the vertical signal line 60a to the vertical signal line 60h, respectively. The readout section 214 reads out signals output from the G pixels 13(4, 1) to the B pixels 13(4, 8) to the vertical signal line 60.

Similarly, the image pickup pixel rows (the 1 st image pickup pixel row 401 and the 2 nd image pickup pixel row 402) are also selected in sequence line by line from the 5 th line and the subsequent lines. The vertical control unit 70 outputs signals to the vertical signal line 60 from the pixels constituting the selected 1 st and 2 nd image pickup pixel rows 401 and 402. The readout section 214 reads out signals output from the R pixel 13, the G pixel 13, and the B pixel 13 to the vertical signal line 60. The signals sequentially read from the respective imaging pixel rows are subjected to signal processing by the column circuit unit 80 and the like, and then read by the body control unit 210.

In this way, in the 2 nd readout mode, the readout section 214 controls the vertical control section 70 to read out signals from the respective pixels of the AF pixel row prior to the imaging pixel row. Therefore, the 1 st signal Sig1 and the 2 nd signal Sig2 of the AF pixel pair can be read out at high speed, and the time required for focus adjustment can be shortened. Further, since the readout unit 214 reads out the signal of each pixel in the AF pixel row separately from the signal of each pixel in the imaging pixel row, the signal used for focus detection can be obtained efficiently, and the load of signal processing for AF can be reduced. The camera 1 according to the present embodiment reads the 1 st signal Sig1 and the 2 nd signal Sig2 of the AF pixel pair selected based on the exit pupil distance of the imaging optical system 31, and performs focus detection processing. Therefore, high-precision focus detection can be realized.

When the 2 nd readout mode is set, the readout unit 214 may read out signals from the pixels in the imaging pixel row prior to the AF pixel row. In this case as well, signals of AF pixel pairs selected based on the exit pupil distance of the photographing optical system 31 are read out and focus detection processing is performed, and therefore, high-precision focus detection can be realized. In addition, signals of the respective pixels of the AF pixel row can be read out separately from signals of the respective pixels of the imaging pixel row, and the load of signal processing for AF can be reduced.

In addition, when the 2 nd readout mode is set and signals are read from the pixels in the imaging pixel row (the 1 st imaging pixel row 401 and the 2 nd imaging pixel row 402), the readout unit 214 may perform thinning readout in which signals are read with thinning out the imaging pixels in a specific row and column among all the imaging pixels. In the case of thinning-out readout, the readout unit 214 selects the image pickup pixels in a specific row or column among all the image pickup pixels, and reads out signals from the selected image pickup pixels. The reading unit 214 can read signals at high speed by skipping signals of pixels in a specific row or column by controlling the vertical control unit 70. In this case, by performing the 2 nd readout mode, it is possible to perform readout of signals from the AF pixel rows prior to readout of signals from the imaging pixel rows, and it is possible to perform readout of signals from the imaging pixel rows at high speed. Therefore, by performing the 2 nd readout mode when displaying a live view image and capturing a moving image, it is possible to perform focus detection at high speed and capture images at high speed. The readout unit 214 may add signals of a plurality of imaging pixels to perform readout.

According to the above embodiment, the following operational effects can be obtained.

(1) The focus detection device includes: an imaging unit (imaging element 22) having 1 st and 2 nd pixels (AF pixels) that receive light transmitted through an optical system (imaging optical system 31) and output signals used for focus detection, and a 3 rd pixel (imaging pixel) that receives light passed through the optical system and outputs signals used for image generation; an input unit (body control unit 210) to which information relating to the optical system is input; a selection unit (pixel selection unit 213) that selects at least one of the 1 st pixel and the 2 nd pixel based on information input to the input unit; a reading unit (reading unit 214) that reads at least one of the signal of the 1 st pixel and the signal of the 2 nd pixel at a timing different from the signal of the 3 rd pixel based on the selection by the selection unit; and a focus detection unit 215 that performs focus detection based on at least one of the signal of the 1 st pixel and the signal of the 2 nd pixel read by the readout unit. In the present embodiment, the readout unit 214 reads out signals from the respective pixels of the AF pixel row prior to the shooting pixel row. Therefore, the focus detection device can read out the signals of the AF pixel pairs at high speed, and can perform focus adjustment at high speed. In addition, signals of the respective pixels of the AF pixel row can be read out separately from signals of the respective pixels of the imaging pixel row, and the load of signal processing for AF can be reduced. The focus detection unit 215 performs focus detection processing using a signal output from an AF pixel pair selected based on the exit pupil distance of the photographing optical system 31. Therefore, high-precision focus detection can be realized.

The following modifications are also within the scope of the present invention, and one or more of the modifications may be combined with the above-described embodiments.

(modification 1)

In embodiment 1, 3 reference exit pupils (the 1 st exit pupil EP1 to the 3 rd exit pupil EP3) are used as the reference exit pupil, but 2 reference exit pupils may be used, or 4 or more reference exit pupils may be used.

(modification 2)

The method of determining the exit pupil distance according to the image height is not limited to the method of determining using the above equation (1). For example, a calculation formula using a cube with a high image height may be applied instead of the formula (1). Further, information (table) indicating the relationship between the image height and the exit pupil distance may be used without using the arithmetic expression.

(modification 3)

In embodiment 1, an example is described in which information on the exit pupil distance is stored in advance in the lens memory 33 or the like, and information on the exit pupil distance is input from the interchangeable lens 3 to the camera body 2. However, the information of the exit pupil distance may be input to the camera body 2 from the outside of the interchangeable lens 3. For example, it may be: the body memory 23 stores information of the exit pupil distance in advance, and the body control unit 210 acquires information of the exit pupil distance from the body memory 23. The camera body 2 may acquire information on the exit pupil distance from a storage medium, or may acquire information on the exit pupil distance from an external device by wired communication or wireless communication. Further, the information on the exit pupil distance may also be information on an exit pupil distance corresponding to one image height.

(modification 4)

In embodiment 1, as the information on the exit pupil distance, the parameters (h4), (h2) and the constant term Co used for calculating the exit pupil distance po (h) are explained as an example. However, the camera body 2 may acquire the value po (h) of the exit pupil distance itself corresponding to the image height as the information on the exit pupil distance from the interchangeable lens 3, a storage medium, or the like.

(modification 5)

In the above-described embodiment, an example in which the 1 st AF pixel pair to the 3 rd AF pixel pair different in shift amount from each other are arranged as a plurality of types of AF pixel pairs in the imaging element 22 is described. However, a plurality of types of AF pixel pairs having different arrangement positions of the light shielding portions between the color filter 51 and the photoelectric conversion portion 42 may be arranged in the imaging element 22. Fig. 16 is a diagram showing an example of the configuration of the AF pixels of the imaging element 22 according to the modification. In the drawings, the same reference numerals are given to the same or corresponding portions as those in the above-described embodiments.

The light-shielding portion 43L of the 1 st AF pixel 11a is provided at a predetermined interval h1 from the photoelectric conversion portion 42 between the color filter 51 and the photoelectric conversion portion 42. The light-shielding portion 43L of the 1 st AF pixel 11b is provided at a predetermined interval h2 from the photoelectric conversion portion 42 between the color filter 51 and the photoelectric conversion portion 42. In addition, the light shielding portion 43L of the 1 st AF pixel 11c is provided at a position at a predetermined interval h3 from the photoelectric conversion portion 42 between the color filter 51 and the photoelectric conversion portion 42. Interval h2 is smaller than interval h1 and larger than interval h 3. Namely, h1 > h2 > h 3. Thus, the light-shielding portions 43L of the 1 st AF pixels 11a, 11b, and 11c are arranged at different positions. The light shielding portions 43R of the second 2 nd AF pixels 12a, 12b, and 12c constituting each AF pixel pair are arranged at different positions. Thus, the 1 st to 3 rd AF pixel pairs can perform pupil division corresponding to different incident angles, as in the case of the above-described embodiment.

(modification 6)

In embodiment 1, an example in which one photoelectric conversion unit is disposed in one pixel is described, but a pixel may have a configuration in which two or more photoelectric conversion units are provided for each pixel.

(modification 7)

Fig. 17 is a diagram showing an example of the configuration of AF pixels of the imaging element 22 according to a modification. As an example, fig. 17 shows a cross-sectional view of three types of AF pixel pairs in a part of the focus detection area 100c of fig. 2. In the drawings, the same reference numerals are given to the same or corresponding portions as those in the above-described embodiments. Each of the three types of AF pixels shown in (a) to (c) of fig. 17 includes a microlens 44, and a1 st photoelectric conversion portion 42a and a2 nd photoelectric conversion portion 42b that photoelectrically convert light that has passed through the microlens 44. In the present modification, the light receiving areas of the 1 st photoelectric conversion portion 42a and the 2 nd photoelectric conversion portion 42b of the 1 st AF pixel pair to the 3 rd AF pixel pair, which receive light, are different from each other. In this case, the 1 st to 3 rd AF pixel pairs can also perform pupil division in accordance with different incident angles, as in the case of the above-described embodiment.

(modification 8)

The pixel selection unit 213 may select a plurality of types of AF pixel pairs. In this case, the focus detection unit 215 may calculate a plurality of defocus amounts from the selected plurality of types of AF pixel pairs, and calculate the movement amount of the focus lens 31b based on the average value of the defocus amounts. For example, the movement amount of the focus lens 31b may be determined based on the defocus amount calculated using the 1 st signal Sig1 and the 2 nd signal Sig2 of the 1 st AF pixel pair and the average value of the defocus amounts calculated using the 1 st signal Sig1 and the 2 nd signal Sig2 of the 2 nd AF pixel pair.

(modification 9)

In the above-described embodiment, the case where the primary color (RGB) color filter is used for the imaging element 22 has been described, but a complementary Color (CMY) color filter may be used.

(modification 10)

The imaging device described in the above embodiment and modification example can be applied to a camera, a smartphone, a tablet PC, a camera built in a PC, an in-vehicle camera, a camera mounted on an unmanned aerial vehicle (an unmanned aerial vehicle, a radio controller, or the like), and the like.

In the above, various embodiments and modifications have been described, but the present invention is not limited to these. Other technical solutions conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.

The disclosures of the following priority base applications are hereby incorporated by reference.

Japanese special wish 2018-

Description of the reference symbols

1, a shooting device; 2, a camera body; 3, a replaceable lens; 11AF pixels; 12AF pixels; 13 shooting a pixel; 22a photographing element; 31a photographing optical system; a 32-lens control unit; 42a photoelectric conversion portion; 210 a body control unit; 211, an area setting unit; 212 a distance calculating unit; 213 a pixel selection section; 214 a readout unit; 215 a focus detection unit; 216 image data generating section.