JP5864989B2 - Imaging device and imaging apparatus - Google Patents

Description

  The present invention relates to an image pickup device having a focus detection pixel in part and an image pickup apparatus using the image pickup device.

  Currently, there is an imaging apparatus having a so-called moving image recording function capable of sequentially recording image signals continuously read from the imaging element in an imaging apparatus having a solid-state imaging element such as a CCD or a CMOS sensor.

  In addition, as a general method using a light beam that has passed through a photographing lens in an automatic focus detection / adjustment method of an imaging apparatus, a contrast detection method (so-called “blur method”) and a phase difference detection method (so-called “deviation method”) are available. is there.

  The contrast detection method is a method often used in video movie equipment (camcorder) for moving image shooting and electronic still cameras, and an image sensor is used as a focus detection sensor. Focusing on the output signal of the image sensor, particularly information on high-frequency components (contrast information), the position of the photographing lens with the largest evaluation value is used as the in-focus position. However, as called a hill-climbing method, it is necessary to scan the position where the evaluation value is maximized while moving the photographic lens by a small amount, so that it is not suitable for high-speed focus adjustment operation.

  On the other hand, the phase difference detection method is often used for a single-lens reflex camera using a silver salt film, and is the technology that has contributed most to the practical application of an auto focus (AF) single-lens reflex camera. In the phase difference detection method, the light beam that has passed through the exit pupil of the photographing lens is divided into two, and the two divided light beams are received by a pair of focus detection sensors. Then, the amount of deviation of the photographic lens in the focus direction is directly obtained by detecting the amount of deviation of the output signal according to the amount of received light, that is, the amount of relative positional deviation in the light beam splitting direction. Therefore, once the accumulation operation is performed by the focus detection sensor, the amount and direction of the focus shift can be obtained, and a high-speed focus adjustment operation is possible. However, in order to divide the light beam that has passed through the exit pupil of the photographic lens into two and obtain a signal corresponding to each light beam, optical path dividing means such as a quick return mirror or a half mirror is provided in the imaging optical path, and beyond that In general, a focus detection optical system and an AF sensor are provided. Therefore, there is a drawback that the apparatus is large and expensive. Also, when performing live view, the quick return mirror is retracted, so that it cannot be operated.

  In order to overcome the above-described drawbacks, there is an imaging device in which some of the light receiving elements (pixels) are provided with a pupil division function by decentering the sensitivity region of the light receiving unit with respect to the optical axis of the on-chip microlens. These pixels are used as focus detection pixels, and are arranged at predetermined intervals between the imaging pixel groups, thereby realizing AF by a high-speed phase difference method even when using an electronic viewfinder or shooting a moving image. For this purpose (for example, see Patent Document 1).

  On the other hand, regarding the image quality degradation caused by the change in the amount of crosstalk to the imaging pixel that occurs when the focus detection pixel is added to a part of the imaging pixel, the imaging pixel is based on the output of the focus detection pixel arranged in the periphery Has been disclosed (see, for example, Patent Document 2).

JP 2000-156823 A JP 2009-124573 A

  However, Patent Document 2 also has a problem that correct correction is difficult due to problems such as imaging conditions (lens diaphragm, exit pupil distance), image height position on the sensor, subject dependency, and the like. In particular, when the color filter provided in the focus detection pixel is changed to a transparent color or the like, there is a problem that it is necessary to estimate the color of the subject, and correction is difficult.

  In addition, when the area of the focus detection pixels is limited to the vicinity of the center of the imaging area where the optical conditions are good and relatively high focus detection accuracy is obtained, and a uniform surface subject is photographed, the following is performed: There was a serious problem. That is, there is a problem that image quality deterioration due to a correction error of an imaging pixel arranged around the focus detection pixel at the boundary between the focus detection pixel arrangement region and the non-arrangement region is easily recognized.

  The present invention has been made in view of the above problems, and when the focus detection pixel placement region is limited to a partial region of the imaging region, at the boundary between the focus detection pixel placement region and the non-placement region, It is an object of the present invention to make image quality deterioration due to a shift in an output signal of an imaging pixel arranged around a focus detection pixel more inconspicuous.

In order to achieve the above object, an image pickup device of the present invention is an image pickup pixel that receives a light beam that has passed through an optical system by a photoelectric conversion unit, has a wiring layer having an opening, and is used for recording or viewing A plurality of imaging pixels that generate image signals, and focus detection pixels that receive light beams that have passed through the optical system with a photoelectric conversion unit, and have a wiring layer having a smaller opening than the imaging pixels. and, an imaging device having a plurality of focus detection pixels for generating a focus detection signal used for focus detection of a phase difference detection method, a mixing ratio of the plurality of focus detection pixels are different respectively, and the plurality has the first region and a second region in which the pixels for image picking plurality of focus detection pixels are regularly arranged, and a third region where the focus detection pixel is not mixed, the , The second region includes the first region and the third region. The region is disposed between the first region and the third region so as to be adjacent to the region, and the mixing rate in the second region is the mixing rate in the first region. Smaller than .

  According to the present invention, when the focus detection pixel placement area is limited to a partial area of the imaging area, the focus detection pixel is placed around the focus detection pixel at the boundary between the focus detection pixel placement area and the non-placement area. Further, it is possible to make the image quality deterioration due to the shift of the output signal of the imaging pixel more inconspicuous.

1 is a schematic configuration diagram of an imaging apparatus according to a preferred embodiment of the present invention. FIG. 3 is a block diagram illustrating a configuration example of an imaging element in an embodiment. Explanatory drawing of all the pixel readout in embodiment. Explanatory drawing of the thinning-out reading in embodiment. 2A and 2B are a plan view and a cross-sectional view of an imaging pixel of an imaging element in an embodiment. 2A and 2B are a plan view and a cross-sectional view of a focus detection pixel of an image sensor in an embodiment. FIG. 6 is a pixel arrangement diagram of imaging pixels and focus detection pixels in the embodiment. FIG. 6 is a region arrangement diagram of blocks including focus detection pixels in the embodiment.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is a configuration diagram of an imaging apparatus according to a preferred embodiment of the present invention, and shows an electronic camera in which a camera body having an imaging element and a photographing optical system are integrated. In FIG. 1, a first lens group 101 is disposed at the tip of a photographing optical system (imaging optical system) and is held so as to be able to advance and retreat in the optical axis direction. The aperture / shutter 102 adjusts the aperture diameter to adjust the amount of light during shooting, and also has a function of adjusting the exposure time when shooting a still image. The aperture / shutter 102 and the second lens group 103 integrally move forward / backward in the optical axis direction, and perform a zooming function (zoom function) in conjunction with the forward / backward movement of the first lens group 101.

  The third lens group 105 performs focus adjustment by moving back and forth in the optical axis direction. The optical low-pass filter 106 is an optical element for reducing false colors and moire in the captured image. The image sensor 107 is composed of a CMOS image sensor and its peripheral circuits. The imaging element 107 has a plurality of light receiving pixels arranged in m pixels in the horizontal direction and n pixels in the vertical direction, and a two-dimensional image in which a Bayer array primary color mosaic filter is formed on-chip on the light receiving pixels. A single plate color sensor is used.

  The zoom actuator 111 rotates a cam cylinder (not shown) to drive the first lens group 101 to the second lens group 103 forward and backward in the optical axis direction, thereby performing a zooming operation. The aperture shutter actuator 112 controls the aperture diameter of the aperture / shutter 102 to adjust the amount of photographing light, and controls the exposure time during still image photographing. The focus actuator 114 adjusts the focus by driving the third lens group 105 back and forth in the optical axis direction.

  The subject illumination electronic flash 115 is used at the time of photographing, and a flash illumination device using a xenon tube is suitable, but an illumination device including an LED that emits light continuously may be used. The AF auxiliary light emitting unit 116 projects an image of a mask having a predetermined opening pattern onto the object field via the light projection lens, and improves the focus detection capability for a dark subject or a low-contrast subject.

  The CPU 121 manages various controls of the camera body in the imaging apparatus. The CPU 121 includes, for example, a calculation unit, ROM, RAM, A / D converter, D / A converter, communication interface circuit, and the like. The CPU 121 drives various circuits included in the imaging device based on a predetermined program stored in the ROM, and executes a series of operations such as AF, shooting, image processing, and recording.

  The electronic flash control circuit 122 controls lighting of the electronic flash 115 in synchronization with the photographing operation. The auxiliary light driving circuit 123 controls the lighting of the AF auxiliary light emitting unit 116 in synchronization with the focus detection operation. The image sensor driving circuit 124 controls the image capturing operation of the image sensor 107, A / D converts the acquired image signal, and transmits it to the CPU 121. The image processing circuit 125 performs processing such as γ conversion, color interpolation, and JPEG compression of the image acquired by the image sensor 107.

  The focus drive circuit 126 controls the focus actuator 114 based on the focus detection result, and adjusts the focus by driving the third lens group 105 back and forth in the optical axis direction. The aperture shutter drive circuit 128 controls the aperture of the aperture / shutter 102 by drivingly controlling the aperture shutter actuator 112. The zoom drive circuit 129 drives the zoom actuator 111 according to the zoom operation of the photographer.

  A display 131 such as an LCD displays information related to the shooting mode of the imaging apparatus, a preview image before shooting and a confirmation image after shooting, a focus state display image when focus is detected, and the like. The operation switch group 132 includes a power switch, a release (shooting trigger) switch, a zoom operation switch, a shooting mode selection switch, and the like. The detachable flash memory 133 records captured images.

  FIG. 2 is a block diagram showing a configuration of the image sensor 107 in the embodiment of the present invention. Note that FIG. 2 shows a minimum configuration that can explain a readout operation described later, and a pixel reset signal and the like are omitted. In FIG. 2, the photoelectric conversion unit 201 includes a photodiode, a pixel amplifier, a reset switch, and the like, and m columns × n rows of photoelectric conversion units are arranged two-dimensionally.

  The switch 202 is a switch for selecting the output of the photoelectric conversion unit 201 and is selected in units of rows by a vertical scanning circuit 208 described later. The line memory 203 is provided to temporarily store the output of the photoelectric conversion unit 201, and the signal MEM becomes the H level when the output of the photoelectric conversion unit 201 in the row selected by the vertical scanning circuit 208 is obtained. Sometimes it is stored via the vertical output line VL. As the line memory 203, a capacitor is usually used. The switch 204 is a switch connected to the horizontal output line HL for resetting the horizontal output line HL to a predetermined potential VHRST, and is controlled by a signal HRST. The switch 205 is a switch for sequentially outputting the output of the photoelectric conversion unit 201 stored in the line memory 203 to the horizontal output line HL.

  The horizontal scanning circuit 206 sequentially scans the switch 205 using the signals H0 to Hm-1, thereby sequentially outputting the output of the photoelectric conversion unit 201 stored in the line memory 203 to the horizontal output line HL. The signal PHST is a data input of the horizontal scanning circuit 206, and the signals PH1 and PH2 are shift clock inputs. The data is set when PH1 is at H level, and the data is latched when PH2 is at H level. By inputting a shift clock to the signals PH1 and PH2, PHST can be sequentially shifted, the signals H0 to Hm-1 can be sequentially set to the H level, and the switch 205 can be sequentially turned on. SKIP is a signal for performing setting at the time of thinning-out reading described later. By setting the SKIP terminal to H level, the horizontal scanning circuit 206 can be skipped at a predetermined interval. Details regarding the read operation will be described later.

  The amplifier 207 amplifies the pixel signal output from the line memory 203 via the horizontal output line HL at a predetermined ratio and outputs it as VOUT.

  The vertical scanning circuit 208 can select the selection switch 202 in units of rows by setting the signals V0 to Vn-1 to the H level. Similar to the horizontal scanning circuit 206, the vertical scanning circuit 208 is controlled by a data input PVST, shift clocks PV1 and PV2, and a thinning / reading setting signal SKIP. Since the operation is the same as that of the horizontal scanning circuit 206, detailed description thereof is omitted.

  FIG. 3 is an explanatory diagram for reading out all the pixels of the image sensor 107 having the configuration shown in FIG. In FIG. 3A, symbols R, G, and B represent the color of the color filter that covers each pixel. In the description of the present embodiment, out of 4 pixels of 2 rows × 2 columns, pixels having G (green) spectral sensitivity are arranged in 2 diagonal pixels, and R (red) and B are arranged in the other 2 pixels. The description will be made on the basis of a Bayer array in which one pixel having (blue) spectral sensitivity is arranged. Also, the numbers appended to the top and the left side of the pixel array in FIG. 3A are numbers in the X and Y directions. In addition, the hatched pixels are read targets. Here, since all pixels are read out, all the pixels in FIG. 3A are hatched. Note that the image sensor 107 is usually provided with an OB (optical black) pixel that is shielded to detect the black level, and reading is also performed from the OB pixel. However, in this embodiment, the description is complicated. Therefore, it is omitted.

  FIG. 3B shows a timing chart when reading all the pixels of the image sensor 107. The CPU 121 controls the image sensor drive circuit 124 and sends a pulse to the image sensor 107 so that the readout is performed. . Here, the all-pixel readout operation will be described with reference to FIG.

  First, the vertical scanning circuit 208 is driven to make V0 active. At this time, the outputs of the pixels in the 0th row are respectively output to the vertical output lines VL. In this state, the signal MEM is activated and the data of each pixel is held in the line memory 203. Next, PHST is activated, shift clocks are input to PH1 and PH2, and pixel outputs are output to the horizontal output line HL by sequentially activating H0 to Hm-1. The output pixel output is output as VOUT via the amplifier 207, converted into digital data by an A / D converter (not shown), and subjected to predetermined image processing by the image processing circuit 125.

  Next, when the vertical scanning circuit 208 activates V1, the pixel output of the first row is output to the vertical output line VL. Similarly, in this state, the signal MEM is activated to output the pixel to the line memory 203. Is held. Next, the operation of outputting the pixel output to the horizontal output line HL is the same by activating PHST, inputting a shift clock to PH1 and PH2, and sequentially activating H0 to Hm-1. Similarly, reading up to the (n-1) th row is sequentially performed by sequentially activating up to Vn-1.

  FIG. 4 is a diagram for explaining an example of thinning readout of the image sensor 107 having the configuration shown in FIG. In FIG. 4A, similarly to FIG. 3A, the hatched pixels are read target pixels at the time of thinning readout. Here, a case of reading by 1/3 decimation in both the X and Y directions is shown.

  FIG. 4B shows a timing chart at the time of decimation reading, and the operation of decimation reading will be described with reference to the timing chart of FIG. Setting for thinning readout is performed by activating the SKIP terminal, which is the control terminal of the horizontal scanning circuit 206. By making the SKIP terminal active, the operation of the vertical scanning circuit 208 and the horizontal scanning circuit 206 is changed from sequential scanning for each pixel to sequential scanning for every three pixels. Since the specific method is a known technique, the details are omitted.

At the time of thinning readout, first, the vertical scanning circuit 208 is driven to make V0 active. At this time, the outputs of the pixels in the 0th row are respectively output to the vertical output lines VL. In this state, the signal MEM is activated and the data of each pixel is held in the line memory 203. Next, PHST is activated and a shift clock is input to PH1 and PH2. At this time, by making the SKIP terminal active, the path of the shift register is changed, and pixel outputs are sequentially output to the horizontal output line HL every three pixels, such as H0, H3, H6... Hm-3. To do. The output pixel output is output as VOUT through an amplifier 207, converted into digital data by an A / D converter (not shown), and subjected to predetermined image processing by an image processing circuit 125.

  Next, like the horizontal scanning circuit 206, the vertical scanning circuit 208 skips V1 and V2, activates V3, and outputs the pixel output of the third row to the vertical output line VL. Thereafter, the pixel output is held in the line memory 203 by the signal MEM. The operation in which PHST is activated, shift clocks are input to PH1 and PH2, H0, H3, H6... Hm-3 are sequentially activated, and the pixel output is output to the horizontal output line HL is the 0th row. The same. As described above, reading up to the n-3th row is sequentially performed. As described above, 1/3 thinning-out reading is performed both in the horizontal and vertical directions.

  5 and 6 are diagrams illustrating the structures of the imaging pixels and the focus detection pixels. In the present embodiment, focus detection pixels having a structure to be described later are distributed and arranged according to a predetermined rule between the Bayer arrays described above.

  FIG. 5 shows the arrangement and structure of the imaging pixels. FIG. 5A is a plan view of 2 × 2 imaging pixels. As is well known, in the Bayer array, G pixels are arranged diagonally, and R and B pixels are arranged in the other two pixels. A structure of 2 rows × 2 columns is repeatedly arranged.

  FIG. 5B is a cross-sectional view taken along the line AA in FIG. ML is an on-chip microlens disposed on the forefront of each pixel, CFR is an R (red) color filter, and CFG is a G (green) color filter. PD (PhotoDiode) schematically shows the photoelectric conversion unit 201 of the image sensor 107 described in FIG. CL (Contact Layer) is a wiring layer for forming signal lines for transmitting various signals in the CMOS image sensor. TL schematically shows the photographing optical system.

  Here, the on-chip microlens ML and the photoelectric conversion element PD of the imaging pixel are configured to capture the light beam that has passed through the photographing optical system TL (Taking Lens) as effectively as possible. In other words, the exit pupil EP (ExitPupil) of the photographing optical system TL and the photoelectric conversion element PD are in a conjugate relationship by the microlens ML, and the effective area of the photoelectric conversion element PD is designed to be large. Further, FIG. 5B describes the incident light beam of the R pixel, but the G pixel and the B (blue) pixel have the same structure. Therefore, the exit pupil EP corresponding to each RGB pixel for imaging has a large diameter, and the S / N of the image signal is improved by efficiently taking in the light flux (photon) from the subject.

  FIG. 6 shows the arrangement and structure of focus detection pixels for performing pupil division in the horizontal direction of the photographing optical system. By performing pupil division in the horizontal direction, focus detection can be performed on an object having a luminance distribution in the horizontal direction, for example, a vertical line. FIG. 6A is a plan view of pixels of 2 rows × 2 columns including focus detection pixels. When obtaining an image signal for recording or viewing, the main component of luminance information is acquired by G pixels. This is because human image recognition characteristics are sensitive to luminance information, and if G pixels are lost, image quality degradation is easily recognized. On the other hand, the R pixel or the B pixel is a pixel that acquires color information (color difference information). However, since human visual characteristics are insensitive to color information compared to luminance information, the pixel that acquires color information. Even if some deficiencies occur, image quality degradation is difficult to recognize. Therefore, in the present embodiment, among the pixels of 2 rows × 2 columns, the G pixel is left as an imaging pixel, and the R pixel and the B pixel are replaced with focus detection pixels. The focus detection pixels are denoted by SA and SB in FIG.

FIG. 6B is a cross-sectional view taken along the line AA in FIG. The microlens ML and the photoelectric conversion element PD have the same structure as the imaging pixel shown in FIG. In the present embodiment, since the signal of the focus detection pixel is not used for image generation, a transparent film CF _W (white) is disposed instead of the color separation color filter. Further, since pupil division is performed in units of the photoelectric conversion unit 201, the opening of the wiring layer CL is biased in one direction with respect to the center line of the microlens ML. Specifically, since the opening OPHA of the pixel SA is biased in the horizontal direction (right side in FIG. 6), the light beam that has passed through the left exit pupil EPHA of the imaging optical system TL is received. Similarly, the opening OPHB of the pixel SB is biased to the left in the direction opposite to that of the pixel SA, and receives the light flux that has passed through the right exit pupil EPHB of the photographing optical system TL. The pixels SA having the above-described configuration are regularly arranged in the horizontal direction, the subject images acquired by these pixel groups are set as A images, and the pixels B having the above-described configuration are also regularly arranged in the horizontal direction. A subject image acquired by these pixel groups is defined as a B image. Then, by detecting the relative position (phase difference) between the obtained A and B images, it is possible to detect the amount of defocus (defocus amount) of the subject image.

  When it is desired to detect a subject having a luminance distribution in the vertical direction, for example, the amount of defocusing of the horizontal line, it is rotated 90 degrees so that the opening OPHA of the pixel SA is shifted downward and the opening OPHB of the pixel SB is biased upward. What is necessary is just to comprise. Alternatively, the opening OPHA may be biased upward, and the opening OPHB of the pixel SB may be biased downward.

  FIG. 7 is a pixel arrangement diagram illustrating an example of the arrangement of the imaging pixels and focus detection pixels SA and SB described with reference to FIGS. 5 and 6. Note that in this embodiment, it is possible to perform thinning readout so that the number of pixels in the image sensor 107 is 1/3 in the horizontal direction and 1/3 in the vertical direction, as described above. Shall. In FIGS. 7A and 7B, the hatched pixels are read out pixels, and the focus detection pixels are arranged in rows and columns that are read out during thinning out reading.

  Further, in consideration of the fact that focus detection pixels cannot be used for imaging, in the present embodiment, focus detection pixels are discretely arranged at a certain interval in the horizontal and vertical directions. It is configured as follows. Further, as described above, it is preferable not to arrange the focus detection pixels in the G pixel portion so that the deterioration of the image is not noticeable. In the present embodiment, as shown in FIG. 7A, a high-density block in which four sets of pixels SA and pixels SB are arranged in a 12 × 24 pixel block is defined as a first arrangement. Further, as shown in FIG. 7B, a block having a lower density than the first arrangement in which two sets of pixels SA and SB are arranged in a block of 12 × 24 pixels is arranged in the second arrangement. And The first arrangement and the second arrangement are each configured such that the pixel arrangement pattern is completed in one block.

  In FIG. 7A, the focus detection pixels are arranged at a higher density than the image pickup pixel group in FIG. 7B, so that the focus detection capability is high, but the image quality deteriorates because the number of image pickup pixels is small. The impact on is great. As an influence on image quality degradation, there is a problem of Patent Document 2 cited as a prior art document. According to Patent Document 2, there is a problem that the output of normal imaging pixels arranged around the focus detection pixels changes by using some of the normal imaging pixel groups as functional pixels.

FIG. 8 is a region layout diagram showing the layout of blocks including focus detection pixels for the entire imaging screen in the present embodiment. In FIG. 8, an effective pixel area 801 in the image sensor 107 indicates an area in which imaging pixels for obtaining an image signal for generating a recorded image are arranged. Region 802 shown in the central portion of FIG. 8 shows the focus detection area (first area), the focus detection pixels high density (first mixed markups) shown in FIGS. 7 (a) The included pixel blocks of the first arrangement are continuously arranged in the horizontal and vertical directions. Further, in the peripheral region 803 of the region 802 (second region), the pixel of the second arrangement of focus detection pixels shown in FIG. 7 (b) is included in a low density (second mixed markups) The blocks are continuously arranged in the horizontal and vertical directions.

As shown in FIG. 8, the image density at the boundary between the focus detection pixel placement area and the non-placement area ( third area) is reduced by gradually reducing the focus detection pixel placement density with respect to the normal imaging pixels. It becomes possible to make deterioration less noticeable. In addition, by arranging the focus detection pixels in a circular shape and aligning them with the center of the optical axis, the optical aberrations of the lens are combined, making it possible to make image quality degradation on the captured image even less noticeable. Become.

  In this embodiment, the area including the focus detection pixels is arranged in the center of the screen. However, this is limited to an area where the optical conditions are good and relatively high focus detection accuracy can be obtained. It is.

In this embodiment, the region including the focus detection pixels is arranged in the circular region in the center of the imaging screen. However, the present invention is not limited to this arrangement. For example, the focus detection region may be configured in a case where regions including focus detection pixels are discretely arranged in a plurality of regions, or in a shape such as a rectangle or a cross. In such a configuration also, it is possible to image degradation at the boundary of the placement area and the area where arrangement of focus detection pixels by changing the mixing markups of focus detection pixels in stages is less noticeable.

In the present embodiment, two types of block arrangement patterns of focus detection pixels have been described. However, the present invention can also be applied to a case where a plurality of types of block arrangement patterns are used. Further, since the same effect is stepwise changed at will mixing markups of focus detection pixels in the all pixel readout for still image is obtained clear, the scope of the present invention is not limited to thinning readout.

  Furthermore, in the present embodiment, a case has been described in which the focus detection pixels SA and SB are taken as one set and an image signal for obtaining a phase difference is acquired. However, the configuration of the focus detection pixels is not limited to this. Absent. For example, one focus detection pixel has a plurality of photoelectric conversion regions and can be read independently from each photoelectric conversion region, so that it is based on subject light that has passed through different pupil regions of the imaging optical system. A plurality of images having a phase difference can be acquired.

As described above, according to this embodiment, mixed markups of focus detection pixels for a normal imaging pixel so as to reduce stepwise, disposing a region including the focus detection pixels having different mixing markups. As a result, it is possible to make the image quality deterioration less noticeable at the boundary between the focus detection pixel arrangement area and the non-arrangement area.

Claims (10)

A plurality of imaging pixels that have a wiring layer having an opening and generate an image signal for recording or viewing;
A focus detection pixel that receives a light beam that has passed through an optical system by a photoelectric conversion unit and has a wiring layer having a smaller opening than the imaging pixel, and is used for focus detection of a phase difference detection method An imaging device having a plurality of focus detection pixels for generating a signal ,
The first region and the second region in which the mixing ratios of the plurality of focus detection pixels are different from each other, and the plurality of imaging pixels and the plurality of focus detection pixels are regularly arranged, and the focus A third region in which no detection pixel is mixed ,
The second region is a region disposed between the first region and the third region so as to be adjacent to the first region and the third region;
Wherein the mixing ratio in the second region, the image pickup element being smaller than the mixing ratio in the first region.   The image sensor according to claim 1, wherein the first region is adjacent to the second region in at least a first direction and a second direction orthogonal to the first direction.   The imaging device according to claim 1, wherein the first region and the second region are arranged in a circular shape. Said first region, the imaging device according to any one of claims 1 to 3, characterized in that it is arranged in central portion in said imaging element.   4. The image sensor according to claim 1, comprising a plurality of the first region and the second region. 5.   One or more different regions between the first region and the third region;
  6. The image pickup device according to claim 1, wherein each region is arranged from the first region to the third region so that the mixing ratio decreases step by step. . An imaging device capable while pulling read, the focus detection pixels, according to any one of claims 1 to 6, characterized in that it is arranged at a position of the pixels that are read out during thinning readout Image sensor. The plurality of imaging pixels have a color filter for acquiring color information ,
Wherein the plurality of focus detection pixels, the image pickup device according to any one of claims 1 to 7, characterized in that it is arranged replaced with a plurality of the image pickup pixels.   The color filter is a red, blue or green color filter,
  The image pickup device according to claim 8, wherein the focus detection pixel is arranged by being replaced with the image pickup pixel having a red or blue color filter. Optical system,
The imaging device according to any one of claims 1 to 9 ,
Focus detection means for detecting a defocus amount based on a phase difference of the focus detection signals obtained from the focus detection pixels of the image sensor;
Control means for adjusting the focus by controlling the optical system based on the defocus amount obtained by the focus detection means ;
An imaging device comprising: