JP2009060279A - Imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging device in a simplified structure for detecting the focal point with less influence on an image signal. <P>SOLUTION: The imaging device 1 is provided with a plurality of pixels, each of which includes a photoelectric converting section, and filters for a plurality of colors arranged for the plurality of pixels. The filters for the plurality of colors are arranged in the first layout in the first domain and in the second layout in the second domain. In the second layout, the pixels corresponding to that for which the filters other than the filters of colors in which the luminance signal is the most weighted among the first layout are constituted as the pixels S1, S2 for detecting the focal point. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an imaging apparatus having a focus detection function.

  There are several methods for the focus detection method of the imaging device, but Patent Document 1 discloses an apparatus that performs pupil division-type focus detection using a two-dimensional light receiving sensor in which a microlens is formed in each pixel of the sensor. Has been.

  FIG. 12 is a diagram illustrating the principle of a method for performing focus detection using the pupil division method proposed in Patent Document 1. In FIG.

  The image sensor 10 is disposed on the planned imaging plane of the photographic lens 5. One pixel of the image sensor 10 includes two photoelectric conversion units 13α and 13β. The photoelectric conversion units 13α and 13β are configured to receive light beams transmitted through different positions of the pupil of the photographing lens 5 by the microlens 11 formed on the photographing lens side of each photoelectric conversion unit. Here, the photoelectric conversion unit 13α mainly receives a light beam that passes through the upper part of the pupil of the photographing lens 5 in the drawing, and the photoelectric conversion unit 13β mainly receives a light beam that passes through the lower part of the pupil of the photographing lens 5 in the drawing. . At the time of focus detection, the output from each photoelectric conversion unit is read out, and further, an image signal is generated by the light flux that has passed through different pupil positions of the photographing lens by the output from the plurality of pixels. A method of performing focus detection using an image signal generated from a light beam that has passed through different pupil positions of the photographing lens is a known technique as disclosed in Patent Document 2.

  Further, the present applicant has disclosed an imaging apparatus capable of performing pupil-division focus detection in Patent Document 3. The imaging device of Patent Document 3 is configured such that a part of the photoelectric conversion unit group receives a light beam that passes through a specific region of the pupil of the photographing lens, and the first obtained from the output of the specific photoelectric conversion unit. The focus state of the photographic lens is detected based on the phase difference between the first image signal and the second image signal. Here, the phase difference is a relative positional relationship between two image signals. When a normal image is captured, an image is generated by a photoelectric conversion unit group excluding a photoelectric conversion unit that receives a light beam that passes through a specific region of the photographing lens.

Patent Document 4 also discloses an imaging apparatus capable of performing pupil division type focus detection. The imaging device disclosed in Patent Document 4 is arranged on a straight line passing through the center of the microlens of pixels in which adjacent color filters of the same color are arranged in a row, and the adjacent pixels are shifted in the opposite direction with respect to the center of the microlens. Are arranged. Thus, the light beam passing through a specific area of the pupil of the photographing lens is received. Then, the focus state of the photographing lens is detected based on the phase difference between the first image signal and the second image signal obtained from the outputs of these specific pixels.
JP-A-58-24105 JP-A-5-127074 JP 2000-156823 A JP 2005-303409 A

  However, the conventional imaging device disclosed in Patent Document 3 and capable of detecting the focus of the photographic lens has focus detection pixels formed of pixels corresponding to a G (green) filter. Therefore, in order to form an image signal, the video signal of the G color filter portion of the focus detection pixel is interpolated using the peripheral pixels. Here, the normal Bayer array sensor is provided with a color filter to form an RGB filter. The G color filter has a broadband spectral characteristic compared to the R color (red) and B color (blue) filters, and has a sensitivity characteristic close to human visual sensitivity. Therefore, if the video signal of the G color filter portion of the focus detection pixel is interpolated using peripheral pixels, there is a problem in that the image signal is affected.

  Further, in Patent Document 4, in order to form a focus detection pixel with a G color filter portion and form an image signal, the image signal is formed as a video signal received by the G color filter of the focus detection pixel. . For this reason, the light beam is received by the focus detection pixel when in the vicinity of the focus, but there is a problem that the light beam is not received by the focus detection pixel when it is not in the vicinity of the focus. As a result, if the video signal of the G color filter portion of the focus detection pixel that is not in the vicinity of the focus is interpolated using the peripheral pixels, there is a problem that the image signal is affected.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an imaging apparatus capable of focus detection with a simple configuration and little influence on an image signal.

  The present invention relates to an imaging apparatus, comprising: a plurality of pixels each having a photoelectric conversion unit; and a plurality of color filters arranged in each of the plurality of pixels, In the region, the first array is arranged, and in the second region, the second array is arranged. In the second array, the luminance signal is most weighted in the first array. A pixel corresponding to a pixel in which a filter other than this filter is arranged is configured as a focus detection pixel.

  According to the present invention, it is possible to provide an imaging apparatus capable of focus detection with a simple configuration and little influence on an image signal.

  Hereinafter, an imaging device according to a preferred embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a configuration diagram of an imaging apparatus such as a digital still camera according to a preferred embodiment of the present invention. Reference numeral 1 denotes an imaging apparatus main body. Reference numeral 10 denotes an image sensor (hereinafter referred to as “image sensor”), which is disposed on the planned imaging plane of the photographing lens 5 of the imaging device 1. The imaging apparatus 1 includes an image sensor control circuit 21 that drives and controls the image sensor 10 and a memory circuit 22 that records an image captured by the image sensor 10. The imaging apparatus 1 also includes an interface circuit 23 that outputs an image processed by the image processing circuit 24 to the outside of the imaging apparatus 1 and an image processing circuit 24 that performs image processing on an image signal captured by the image sensor 10. The imaging device 1 also includes a liquid crystal display element 9 for displaying a captured image, a liquid crystal display element driving circuit 25 for driving the liquid crystal display element 9, an eyepiece lens 3 for observing a subject image displayed on the liquid crystal display element 9, An operation switch SW2 is provided for recording an image taken by the photographer. The entire imaging apparatus 1 is controlled by the CPU 20.

  The photographing lens 5 is an interchangeable lens that is attached to the imaging device 1. In FIG. 1, for the sake of simplicity of illustration, the photographing lens 5 is shown as two lenses 5a and 5b. However, the present invention is not limited to this and may be constituted by three or more lenses. . The taking lens 5 is adjusted to the in-focus state by the taking lens driving mechanism 26 based on the lens driving amount sent from the CPU 20. The CPU 20 and the image sensor 10 also serve as a focus detection device. Reference numeral 30 denotes an aperture device, which is configured to be reduced to a predetermined aperture value by the aperture drive mechanism 27. Reference numeral 31 denotes a photographing lens memory circuit that records information unique to the photographing lens 5. The photographic lens driving mechanism 26, the aperture driving mechanism 27, and the photographic lens memory circuit 31 can communicate with the CPU 20 of the imaging device 1 through a communication terminal provided in a mounting portion of the imaging device 1.

  FIG. 2 is a diagram showing a color arrangement of the image sensor 10 according to the present embodiment. The basic color array as the first array is arranged in a first area composed of pixels of a plurality of colors. For example, a Bayer array of a plurality of color green pixels, red pixels, and blue pixels can be used. Each pixel has an opening through which a light beam received by the photoelectric conversion unit of the image sensor passes. In FIG. 2, the opening in the green pixel is represented as G, the opening in the red pixel is represented as R, the opening in the blue pixel is represented as B, and the opening in the achromatic (= white) pixel is represented as S1 and S2. Specifically, a color filter that allows a green light beam to pass through the opening G of the green pixel, a color filter that allows a red light beam to pass through the opening R of the red pixel, and a blue light beam to the opening B of the blue pixel. A color filter to be passed is arranged. Further, no filter layer is disposed in the openings S1 and S2 of the achromatic pixel. Alternatively, a substantially transparent filter layer may be disposed in the openings S1 and S2.

  A photoelectric conversion unit exists under each opening. A microlens described later is disposed on the upper surface of each opening. One photoelectric conversion unit, a color filter disposed thereon, and a microlens disposed further thereon constitute one pixel.

  One row of achromatic pixels arranged in the second region diagonally arranged in a row is a focus detection pixel row as the second array. In the present embodiment, in the basic color array, focus detection pixels are arranged in pixels in which filters other than the color filter that weights the luminance signal most among the filters of a plurality of colors are arranged. For example, in the Bayer array, as shown in FIG. 13, the G color filter corresponds to the color that most weights the luminance signal. Therefore, S1 of the first focus detection pixel is formed at the opening R in the red pixel, and S2 of the second focus detection pixel is formed at the position of the opening B in the blue pixel. By providing a light-shielding layer at a part of the openings of the focus detection pixels arranged in a row adjacent to each other, the exit pupil of the photoelectric conversion unit is configured to be biased with respect to the optical axis of the photographing lens. The direction of the bias is opposite between adjacent focus detection pixels. Similarly, for color arrays other than the Bayer array, pixels corresponding to pixels in which a filter other than the color filter that weights the luminance signal most among the plurality of color filters are arranged as focus detection pixels. sell. Note that the second region is not limited to those formed by pixels arranged in an oblique line as shown in FIG. 2, and may be formed by pixels in other arrangements.

  FIG. 3 is an enlarged view of four pixels including two focus detection pixels, one red pixel, and one blue pixel. The shape of the opening will be described with reference to FIG.

  The upper left and lower right pixels are focus detection pixels (achromatic pixels), and the upper right and lower left pixels are green pixels. Reference numeral 11 denotes a microlens disposed on the upper surface of each opening. Reference numerals 37a and 37b denote microlens centers in adjacent focus detection pixels. Reference numeral 36 denotes a straight line passing through the center of the microlenses of the focus detection pixels arranged in a row adjacent to each other. Reference numeral 38a denotes an opening shape of a normal red pixel which is not a focus detection pixel. Reference numeral 38b denotes an opening shape of a normal blue pixel which is not a focus detection pixel. Reference numerals 39a and 39b denote the opening shapes of the focus detection pixels. The normal red pixel opening shape 38a and the normal blue pixel opening shape 38b are respectively centered on the reduction centers 35a and 35b other than the center of the microlens. It is a reduced shape. Here, the reduction centers 35a and 35b are points separated from the microlens centers 37a and 37b by equal distances in the opposite directions on the straight line 36, respectively. Since the opening shapes 39a and 39b of the focus detection pixels are reduced in size around the reduction centers 35a and 35b, the neighboring pixels are biased in different directions. In other words, the center of the opening shape 39a of the focus detection pixel is arranged to be biased toward the center side of the microlens center 37b with respect to the microlens center 37a. Further, the center of the opening shape 39b of the focus detection pixel is arranged to be biased toward the center side of the microlens center 37a with respect to the microlens center 37b. In addition, the opening shapes 39 a and 39 b of the focus detection pixels are symmetrical with respect to a line 46 perpendicular to the straight line 36.

FIG. 4 is a diagram illustrating a pixel structure of the image sensor 10. 4A is a structural view seen from above, and FIG. 4B is a cross-sectional view taken along line AA in FIG. 4A. Reference numeral 201 denotes a clock gate electrode formed of light-transmitting polysilicon, and a semiconductor surface under the electrode is a clock phase region. The clock phase region is divided into two regions by ion implantation. One is a clock barrier region 202 and the other is a clock well region 203 formed by implanting ions so that the potential is higher than that of the clock barrier region 202. A virtual phase region 204 functions as a virtual gate for fixing the channel potential by forming a P ⁺ layer on the semiconductor surface. The virtual phase region is also divided into two regions by implanting N-type ions into a layer deeper than the P ⁺ layer. One is a virtual barrier region 205 and the other is a virtual well region 206. Reference numeral 207 denotes an insulating layer such as an oxide film disposed between the electrode and the semiconductor. Reference numeral 208 denotes a channel stop for separating the channels of each VCCD.

  The clock gate electrode 201, the clock barrier region 202, the clock well region 203, the virtual gate 204, the virtual barrier region 205, and the virtual well region 206 form a photoelectric conversion unit, and converts the incident light beam into an electric signal.

  Although not shown here, a function of preventing a blooming phenomenon in which charges overflow into adjacent pixels and become a pseudo signal when strong light is incident can be added. A typical method is to provide a horizontal overflow drain.

  A color filter is provided above the image sensor shown in FIG. In addition, a metal light shielding layer is provided between the color filter and the CCD cell to prevent color mixing of each color.

  FIG. 5 is a structural diagram of a normal photographing pixel. FIG. 5A is a structural view seen from above, and FIG. 5B is a cross-sectional view taken along line AA in FIG. The same components as those in FIG. 4 are given the same reference numerals.

  Reference numeral 209 denotes a protective layer on the semiconductor surface. Reference numeral 210 denotes a metal light shielding layer for preventing color mixing. However, it may be composed of a black pigment layer made of the same material as the color filter. The region cut out by the metal light shielding layer 210 is an opening, and the light beam that has passed through the opening reaches the photoelectric conversion unit. Reference numeral 211 denotes a smoothing layer for flattening the surface on which the color filter layer is arranged, 212 denotes a red / green / blue color filter layer, and 213 denotes a protective layer for protecting the filter layer. The microlens 11 is configured on the upper surface of the protective layer 213. In the normal photographing pixel, the center of the microlens is configured to be the center of the opening formed by the metal light shielding layer 210.

  FIG. 6 is a structural diagram of focus detection pixels. FIG. 6A is a structural view seen from above, and FIG. 6B is a cross-sectional view taken along line AA in FIG. The same components as those in FIG. 4 are given the same reference numerals.

  Reference numeral 209 denotes a protective layer on the semiconductor surface. Reference numeral 210 denotes a metal light shielding layer for preventing color mixing. However, it may be composed of a black pigment layer made of the same material as the color filter. The region cut out by the metal light shielding layer 210 is an opening, and the light beam that has passed through the opening reaches the photoelectric conversion unit. 211 is a smooth layer for flattening the surface on which the color filter layer is arranged, 212 is an achromatic color filter layer, and 213 is a protective layer for protecting the filter layer. The microlens 11 is configured on the upper surface of the protective layer 213.

  In the focus detection pixel, the shape of the metal light shielding layer 210 is different from that of the normal photographing pixel. The metal light shielding layer 210 is formed so that the shape of the opening is deviated from the center of the microlens.

  FIG. 7 is a diagram illustrating the photoelectric conversion unit of the focus detection pixel projected onto the pupil of the photographing lens. FIG. 7 is drawn with the direction in which the focus detection pixels are arranged (the direction of the straight line 36) being horizontal. Reference numerals 39a-1 and 39b-1 are projections of the photoelectric conversion units of the focus detection pixels on the pupil 40 of the photographing lens. Since the projected photoelectric conversion units 39a-1 and 39b-1 are partially shielded from light by the openings, the photoelectric conversion units 39a-1 and 39b-1 have a shape that is biased with respect to the optical axis of the photographing lens. Reference numerals 41a and 41b denote exit pupil areas of focus detection pixels. The exit pupil regions 41a and 41b of the photoelectric conversion unit are portions where the projected photoelectric conversion units 39a-1 and 39b-1 overlap with the pupil of the photographing lens.

  Assuming that a line perpendicular to the direction in which the focus detection pixels are arranged (the direction of the straight line 36) is 46, the exit pupil regions 41a and 41b of the photoelectric conversion unit are substantially line-symmetric with respect to 46. Therefore, the A image signal-B image signal obtained by receiving the light flux that has passed through the exit pupil regions 41a and 41b of the photoelectric conversion unit has a substantially bilaterally symmetric shape as shown in FIG. As a result, the obtained A image signal-B image signal is also shifted by substantially the same shape.

  When performing focus detection, correlation calculation is performed on the A image signal-B image signal, and the focus state is detected from the phase difference between the two image signals. At this time, if the shapes of the A image signal and the B image signal do not match, there is a problem in accuracy. However, in the focus detection apparatus according to the present embodiment, as shown in FIG. 8, the shapes of the A image signal and the B image signal are almost the same, so that highly accurate focus detection can be realized.

  When a captured image is recorded, the focus detection pixel S1 portion is interpolated by the peripheral red pixels, and the focus detection pixel S2 portion is interpolated by the peripheral blue pixels.

  FIG. 13 is a diagram illustrating spectral characteristics of red, green, and blue color filters. The red filter has spectral characteristics centered at about 590 nm. The green filter has spectral characteristics centered at about 560 nm. The blue filter has spectral characteristics centered at about 450 nm. The green filter has a wide band characteristic for red and blue, and has a sensitivity characteristic close to human visual sensitivity. That is, the imaging apparatus according to the present embodiment realizes an image signal with less influence of the focus detection pixels by disposing the focus detection pixels in the red and blue color filter portions away from human visibility. Can do.

  In the imaging apparatus according to the present embodiment, the focus detection pixels that receive the A image signal-B image signal used for focus detection are arranged on the same line as shown in FIG. The A image signal-B image signal is an image signal based on light emitted from the same line of the subject. Therefore, when the focus detection state is detected, a shape in which the A image signal-B image signal substantially coincides is obtained, and high-precision focus detection is realized.

  In the prior art, if the image pickup apparatus is configured such that the A image signal and the B image signal are image signals based on light emitted from the same line of the subject, the signal sample pitch becomes twice the normal pixel pitch. I have. However, in the imaging apparatus according to the present embodiment, it is possible to suppress the sample pitch to about 1.4 times the pitch of the normal pixels by using focus detection pixels that are obliquely aligned in a line as shown in FIG. became. For this reason, even when the photographing lens is in the vicinity of in-focus and the two image signals contain a lot of high-frequency components, highly accurate focus detection is realized.

  Furthermore, in the imaging apparatus according to the present embodiment, since it is not necessary to shorten the microlens interval between specific pixels, there is a concern that adjacent microlenses may stick together when manufacturing the spherical shape of the microlens by heat treatment. Absent. Therefore, it can sufficiently cope with future miniaturization of the imaging device.

  Next, an operation flow of the imaging apparatus according to the present embodiment will be described with reference to FIG.

  In S101, the CPU 20 checks the state of the main switch. When the photographer turns on the main switch of the imaging apparatus 1 (not shown in FIG. 1) (“Yes” in S101), the CPU 20 executes focus detection of the photographing lens 5 (S201). In the focus detection in S201, the defocus amount of the photographing lens 5 is calculated as described later, and the driving amount of the photographing lens is calculated using the obtained defocus amount.

  Based on the driving amount of the photographing lens calculated in the focus detection of S201, the CPU 20 sends a lens driving signal to the photographing lens driving mechanism 26, and drives the photographing lens 5 to set the focus state (S102).

  When the lens driving in S102 is completed, the CPU 20 sends an imaging signal to the image sensor control circuit 21 to cause the image sensor 10 to perform imaging (S103). The image signal picked up by the image sensor 10 is A / D converted by the image sensor control circuit 21 and then subjected to image processing by the image processing circuit 24.

  The image signal subjected to the image processing is sent to the liquid crystal display element driving circuit 25 through the CPU 20 and displayed on the liquid crystal display element 9 (S104). As a result, the photographer can observe the subject image displayed on the liquid crystal display element 9 through the eyepiece 3.

  Further, the CPU 20 checks the state of the operation switch SW2 for recording the captured image (S105).

  If the photographer has not operated the operation switch SW2 (“No” in S105), the CPU 20 returns to S102 and confirms the state of the main switch.

  On the other hand, if the photographer presses the operation switch SW2 to photograph the subject (“Yes” in S105), the CPU 20 sends an imaging signal to the image sensor control circuit 21 to cause the image sensor 10 to perform the main imaging. (S106).

  The image signal subjected to A / D conversion by the image sensor control circuit 21 is subjected to image processing by the image processing circuit 24, then sent to the liquid crystal display element driving circuit 25 and displayed on the liquid crystal display element 9 (S107).

  Further, the CPU 20 stores the captured image signal as it is in the memory circuit 22 of the imaging device 1 (S108).

  When the photographing operation is completed and the photographer turns off the main switch (“No” in S101), the power supply of the imaging apparatus 1 is turned off and a standby state is entered.

  Next, FIG. 10 shows an operation flow of the focus detection subroutine in S201 of FIG.

  When focus detection is executed, the CPU 20 of the imaging apparatus 1 sends an imaging start signal for focus detection to the image sensor control circuit 21, and causes the image sensor 10 to perform imaging of the focus detection light beam (S202). The CPU 20 generates an A image signal and a B image signal from the achromatic output signal based on the focus detection light flux that has passed through different pupil regions of the photographing lens 5.

  Next, the CPU 20 performs a correlation operation using the A image signal-B image signal generated in the shooting of S202, and calculates the defocus amount of the shooting lens 5 from the shift amount of the two image signals (S203).

  Next, the CPU 20 calculates the driving amount of the photographing lens based on the defocus amount calculated in the defocus amount calculation in S203 (S204).

  When the driving amount of the photographing lens is calculated in S204, the CPU 20 returns to the main routine (S205).

  Here, the correlation calculation process in the defocus amount calculation in S203 will be described. Assume that after the image pickup for focus detection (S202), the A image signal and the B image signal as shown in FIG. In this case, the phase difference between the two generated image signals changes depending on the imaging state (focused state, front pin state, rear pin state) of the photographic lens. When the imaging lens is in the focused state, the phase difference between the two image signals is eliminated. On the other hand, when the imaging lens is in the front pin state or the rear pin state, phase differences in different directions occur. Further, the phase difference between the two image signals has a certain relationship with the defocus amount of the photographing lens. Here, the defocus amount is the distance between the position where the subject image is formed by the photographing lens and the top surface of the microlens. The defocus amount of the photographing lens is obtained from the phase difference between the two image signals, and the focus detection is performed by calculating the lens driving amount that brings the photographing lens into a focused state.

  The phase difference between the two image signals can be obtained by correlating the two image signals. The method of obtaining the correlation is called “MIN algorithm”. Here, when the output data of the A image signal is A [1] to A [n] and the output data of the B image signal is B [1] to B [n], the correlation amount U0 is expressed by the following Equation 1. The

  Here, min (a, b) means the smaller value of a and b. First, this U0 is calculated, and then, as shown in FIG. 11, the correlation amount U1 between the data obtained by shifting the A image signal by 1 bit of the signal voltage and the data of the B image signal is calculated. This U1 is expressed by the following mathematical formula 2.

  In this way, the correlation amount shifted by one bit is sequentially calculated. If the two image signals match, this correlation amount takes the maximum value Umax. Therefore, the shift amount that takes the maximum value is obtained, the true maximum value of the correlation amount is interpolated from the data before and after that, and the shift amount is taken as the phase difference between the two image signals. The focus detection can be performed by obtaining the defocus amount of the photographing lens from the phase difference between the two image signals and calculating the lens driving amount so that the photographing lens is brought into focus.

1 is a configuration diagram of an imaging apparatus such as a digital still camera according to a preferred embodiment of the present invention. It is a figure which shows the color arrangement | sequence of the image sensor which concerns on this embodiment. FIG. 3 is an enlarged view of the color arrangement in FIG. 2. It is a figure which shows the pixel structure of an image sensor. FIG. 3 is a structural diagram of a normal photographing pixel. It is a structural diagram of a pixel for focus detection. It is a figure which shows the photoelectric conversion part of the pixel for focus detection projected on the pupil of the imaging lens. It is a figure which shows two image signals obtained from the pixel row | line for focus detection. It is a figure explaining the operation | movement flow of the imaging device which concerns on this embodiment. It is a figure which shows the operation | movement flow of the focus detection subroutine in S201 of FIG. It is a figure explaining a correlation calculation process. It is a principle explanatory view of a method of performing pupil division type focus detection. It is a figure explaining the spectral characteristic of a color filter.

Explanation of symbols

1 Imaging devices S1, S2 Focus detection pixels

Claims (6)

A plurality of pixels each having a photoelectric conversion unit;
A plurality of color filters disposed in each of the plurality of pixels;
With
The multi-color filters are arranged in a first array in the first region, and are arranged in a second array in the second region,
In the second array, a pixel corresponding to a pixel in which a filter other than the color filter that weights the luminance signal most in the first array is arranged as a focus detection pixel. An imaging device that is characterized. The color filter that weights the luminance signal most is a green filter,
The image pickup apparatus according to claim 1, wherein the filters other than the color filter that weights the luminance signal most are red and blue filters.   The imaging device according to claim 1, wherein the focus detection pixel is configured by not arranging the filter.   The imaging device according to claim 1, wherein an achromatic filter is disposed in the focus detection pixel. The focus detection pixels include adjacent first focus detection pixels and second focus detection pixels,
A microlens is disposed in each of the first and second focus detection pixels,
The center of the opening of the first focus detection pixel is closer to the center side of the microlens arranged in the second focus detection pixel than the center of the microlens arranged in the first focus detection pixel. Is biased to
The center of the opening of the second focus detection pixel is closer to the center side of the microlens arranged in the first focus detection pixel than the center of the microlens arranged in the second focus detection pixel. The image pickup apparatus according to claim 1, wherein the image pickup apparatus is arranged so as to be biased.   The openings of the first and second focus detection pixels have a reduced shape around a point other than the center of the microlens arranged in each of the first and second focus detection pixels. 6. The imaging apparatus according to claim 5, wherein the center of the reduced shape is on a straight line passing through the center of a microlens arranged in each of the first and second focus detection pixels.

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