JP2015060111A - Imaging device, imaging system, control method and program of imaging device, and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging device that causes highly accurate focus detection to be balanced with high-definition image generation, using an image pickup element containing a focus detection pixel.SOLUTION: An imaging device has: an image pickup element that contains a unit pixel group composed of a plurality of first pixels with a dead zone and a second pixel without the dead zone; first signal generation means for generating an imaging signal using pixel data from at least the second pixel; second signal generation means for generating a focus detection signal using image data from the plurality of first pixels and the second pixel; and focus detection means for performing focus detection on the basis of the focus detection signal. The number of first pixels contained in the unit pixel group is N(N≥3), and each of the plurality of first pixels has the dead zone in a mutually different one area, each of which is divided into N-divisions (N≥3).

Description

  The present invention relates to an imaging apparatus capable of performing focus detection by a phase difference method using an imaging element including focus detection pixels.

  2. Description of the Related Art Conventionally, an imaging apparatus capable of performing focus detection by a phase difference method using an image sensor including focus detection pixels is known. Japanese Patent Application Laid-Open No. 2004-228561 discloses an imaging element having a pupil division function by arranging a photodiode so as to receive one of divided pixels obtained by dividing each of some pixels into two. The image sensor of Patent Literature 1 uses these divided pixels as focus detection pixels and arranges the focus detection pixels at a predetermined interval between the image pickup pixel groups, thereby enabling phase difference type focus detection.

  Patent Document 2 discloses an imaging device including a focus detection pixel configured by dividing one pixel of a light receiving unit into four quadrants and arranging the light receiving unit only in any one quadrant.

Japanese Patent No. 4797606 JP 2008-299184 A

  When a focus detection pixel is provided in the image sensor as in Patent Document 1 and Patent Document 2, it is effective in focus detection, but is treated as a defective (scratched) pixel in image generation. In particular, if an attempt is made to improve the focus detection performance by increasing the density of focus detection pixels, the number of defective pixels increases and it is difficult to generate a high-quality image. Further, even when a defective pixel is interpolated using surrounding imaging pixels, it is often difficult to generate a high-quality image.

  Accordingly, the present invention provides an imaging device, an imaging system, an imaging device control method, a program, and a storage medium that achieve both high-precision focus detection and high-quality image generation using an imaging device including focus detection pixels. To do.

  An imaging apparatus according to an aspect of the present invention includes an imaging device including a unit pixel group including a plurality of first pixels having a dead zone and a second pixel having no dead zone, and at least the second A first signal generating unit configured to generate an imaging signal using pixel data from the pixel; and a second signal generating a focus detection signal using pixel data from the plurality of first pixels and the second pixel. A signal generation unit and a focus detection unit that performs focus detection based on the focus detection signal, and the number of the plurality of first pixels included in the unit pixel group is N (N ≧ 3), Each of the plurality of first pixels has the dead zone in one different region divided into N (N ≧ 3).

  An imaging system as another aspect of the present invention includes a lens unit and the imaging device.

  According to another aspect of the present invention, there is provided a method for controlling an imaging apparatus including an imaging device including a plurality of first pixels having a dead zone and a unit pixel group including a second pixel having no dead zone. A method for controlling an imaging apparatus, comprising: generating an imaging signal using at least pixel data from the second pixel; and using pixel data from the plurality of first pixels and the second pixel A step of generating a focus detection signal; and a step of performing focus detection based on the focus detection signal, wherein the number of the plurality of first pixels included in the unit pixel group is N (N ≧ 3). In addition, each of the plurality of first pixels has the dead zone in one different region divided into N (N ≧ 3).

  A program according to another aspect of the present invention causes a computer to execute a method for controlling the imaging apparatus.

  A storage medium according to another aspect of the present invention stores the program.

  Other objects and features of the present invention are illustrated in the following examples.

  According to the present invention, an imaging device, an imaging system, an imaging device control method, a program, and a storage medium that achieve both high-precision focus detection and high-quality image generation using an imaging device including focus detection pixels are provided. Can be provided.

It is a block diagram of the imaging device in each embodiment. It is a block diagram of the imaging sensor in each Example. It is explanatory drawing of the production | generation process of the focus detection signal by the focus detection signal generation circuit in Example 1. FIG. It is explanatory drawing of the focus detection signal in Example 1. FIG. It is explanatory drawing of the focus detection signal in Example 2. FIG. It is explanatory drawing of the production | generation process of the focus detection signal by the focus detection signal generation circuit in Example 2. FIG. 6 is a pixel configuration diagram of an image sensor in Embodiment 3. FIG. 6 is a pixel array diagram of an image sensor in Embodiment 3. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same members are denoted by the same reference numerals, and redundant description is omitted.

  First, the configuration of an imaging apparatus (imaging system) in Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a block diagram of the imaging apparatus 10.

  The lens unit 100 (shooting optical system) includes a focus lens, a zoom lens, a diaphragm, and the like. The image sensor 101 (image sensor) includes a CMOS, a CCD, and the like, and photoelectrically converts a subject image (optical image) obtained via the lens unit 101. As will be described later, the imaging sensor 101 includes a plurality of focus detection pixels (a plurality of first pixels) having a mask (dead zone) and an imaging pixel (a second pixel) having no mask (dead zone). A basic pixel group (unit pixel group).

  The imaging signal generation circuit 102a (first signal generation means) generates an imaging signal using an output signal of the imaging sensor 101 (at least using pixel data from the second pixel). The signal processing circuit 104 performs a plurality of noise processes on the output signal (imaging signal) from the imaging signal generation circuit 102a. The image processing circuit 105 converts the output signal from the signal processing circuit 104 into various image formats. The image memory 107 stores a signal related to the image being processed by the image processing circuit 105. The recording circuit 106 records the image processed by the image processing circuit 105 on a recording medium (not shown).

  A CPU 109 (system controller) performs various controls and lens drive control. The CPU 109 also functions as a focus detection unit that performs focus detection based on the focus detection signal. The memory 108 holds programs and data executed by the CPU 109. The lens driving circuit 110 drives a focus lens, a diaphragm, and the like in the lens unit 100 based on a command from the CPU 109.

  The focus detection signal generation circuit 102b (second signal generation means) uses the output signal from the image sensor 101 (using pixel data from the plurality of first pixels and second pixels) to detect the phase difference. A signal (focus detection signal) for focus detection of the system is generated. The luminance evaluation circuit 103 evaluates the luminance of the focus detection signals of two images (a pair). The CPU 109 performs focus calculation (focus detection) using a phase difference method based on the luminance evaluated by the luminance evaluation circuit 103.

  In the present embodiment, the imaging apparatus 10 is configured integrally with the lens unit 100 and the imaging apparatus main body including the imaging sensor 101, but is not limited thereto. The present embodiment can also be applied to an imaging system that includes an imaging apparatus body and a lens unit (imaging optical system) that can be attached to and detached from the imaging apparatus body.

  Next, the configuration of the image sensor 101 (image sensor) in the present embodiment will be described with reference to FIG. FIG. 2 is a configuration diagram of the image sensor 101. The entire image sensor 101 (the entire image sensor 200) has a size of about 24 mm × 14 mm, for example, and each pixel of R (red), G (green), and B (blue) is 5 μm square. Like pixels 201 to 216 shown by enlarging a part of the entire image sensor 200, each of R, G, and B constitutes a Bayer array type image sensor 101 (image sensor) together with a microlens (not shown). doing.

  Pixels 201, 203, 209, and 211 are R (red) pixels. Pixels 206, 208, 214, and 216 are B (blue) pixels. Pixels 202, 204, 205, 207, 210, 212, 213, and 215 are G (green) pixels. Among these pixels, the pixels 202, 204, 210, and 212 (focus detection pixels) are provided with a mask (dead zone) in a partial region between the photodiode and the microlens. This region is a region shown in black in FIG. These pixels are masked at positions in different quadrants, and are configured to block incident light from a part of directions with different quadrants. As shown in FIG. 2, the second quadrant of the pixel 202 is masked. Pixel 204 is masked in the third quadrant, pixel 210 is masked in the first quadrant, and pixel 212 is masked in the fourth quadrant. The entire image sensor 200 is repeatedly arranged with the 16 pixels (pixel group) as one set (unit pixel group).

  Next, the processing of the focus detection signal generation circuit 102b will be described with reference to FIG. FIG. 3 is an explanatory diagram of generation processing of a focus detection signal (focus detection pixel data). In FIG. 3A, each pixel signal (pixel data) is defined as follows in order to simplify the description in comparison with the pixel arrangement in FIG. That is, a pixel signal (pixel data) in which the second quadrant corresponding to the pixel 202 is masked is defined as “A”, and a pixel signal (pixel data) in which the third quadrant corresponding to the pixel 204 is masked is defined as “B”. . Also, a pixel signal (pixel data) in which the first quadrant corresponding to the pixel 210 is masked is “D”, and a pixel signal (pixel data) in which the fourth quadrant corresponding to the pixel 212 is masked is “C”. Further, an unmasked pixel signal (pixel) corresponding to the pixel 207 disposed between the pixels 202, 204, 210, and 212 (sandwiched between the pixels 202 and 212 or the pixels 204 and 210). Data) is “E”.

  First, the focus detection signal generation circuit 102b executes calculations represented by the following expressions (1a) to (1b) based on these pixel signals (pixel data).

E−A = A ′ (1a)
E−B = B ′ (1b)
E−C = C ′ (1c)
E−D = D ′ (1d)
FIG. 3B shows a data image of the pixel signals A ′ to D ′ (pixel data) obtained by the calculations of the expressions (1a) to (1d). That is, the pixel signal A ′ is image data in the second quadrant. The pixel signal B ′ is image data in the third quadrant. The pixel signal C ′ is image data in the fourth quadrant. The pixel signal D ′ is image data in the first quadrant. However, as a premise thereof, it is necessary to satisfy the following formula (2).

A + B + C + D≈3 × E (2)
In this embodiment, the pixel signal E ′ or the pixel signal E ″ may be used instead of the pixel signal E. As shown in FIG. 3A, the pixel signal E ′ or the pixel signal E ″ Adjacent same color pixel data. Further, the average value of the pixel signal E + E ″ may be used as the pixel signal E when calculating the pixel signal B ′ or the pixel signal C ′. It is possible to generate a sample (signal) at the same position in the horizontal direction as the position of the pixel data A. Similarly, calculate the pixel signals A ′ and D ′ using the pixel data of the pixel signals A and D. In this case, an average value of the pixel signal E + E ′ may be used instead of the pixel signal E.

  Next, the focus detection signal generation circuit 102b is expressed by the following equations (3a) to (3d) using the signals A ′ to D ′ calculated by the operations of the equations (1a) to (1d). In addition, pixel signals Df, Uf, Rf, and Lf (focus detection signals) are generated.

A ′ + B ′ = Df (3a)
C ′ + D ′ = Uf (3b)
A ′ + D ′ = Rf (3c)
C ′ + B ′ = Lf (3d)
FIG. 3C shows a data image of the pixel signals Df, Uf, Rf, Lf (pixel data). That is, the pixel signal Df obtained by adding the pixel signal A ′ and the pixel signal B ′ corresponds to a pixel signal (pixel data) when the lower half of one pixel is exposed. A pixel signal Uf obtained by adding the pixel signal C ′ and the pixel signal D ′ corresponds to a pixel signal (pixel data) when the upper half of one pixel is exposed. Similarly, the pixel signal Rf obtained by adding the pixel signal A ′ and the pixel signal C ′ corresponds to a pixel signal (pixel data) when the right half of one pixel is exposed. A pixel signal Lf obtained by adding the pixel signal C ′ and the pixel signal B ′ corresponds to a pixel signal (pixel data) when the left half of one pixel is exposed.

  The pixel signals Df and Uf are used as a pair to form a horizontal line detection vertical eye, and the pixel signals Rf and Lf are used as a set to form a vertical line detection horizontal eye. As described above, the focus detection signal generation circuit 102b performs the above-described processing on the basic pixel group (unit pixel group) of 16 pixels. That is, the focus detection signal generation circuit 102b generates four pixel data (two for the vertical eye and two for the horizontal eye) for phase difference detection using the basic pixel group (16 pixels). In this embodiment, this basic pixel group is arranged on the image sensor 101, and by arranging such a basic pixel group, image data (focus detection signal) used for phase difference detection is generated. The

  FIG. 4 is an explanatory diagram of a focus detection signal (focus detection pixel data). In FIG. 4, reference numerals 401 to 425 are serial numbers assigned to basic pixel groups (unit pixel groups). FIG. 4 shows a part of the angle of view. The number of pixels in units of R, G, and B considered independently is 16 pixels in both horizontal and vertical directions, and the basic pixel group unit is in the range of 4 × 4 in the horizontal and vertical directions. Is shown. As described with reference to FIG. 3, pixel signals Uf, Df, Rf, and Lf (four focus detection signals, that is, focus detection pixel data) are generated from the basic pixel group 401, respectively.

  Here, it is assumed that the pixel signals generated from the basic pixel group 401 are Uf (01), Df (01), Rf (01), and Lf (01), respectively. At this time, the pixel signals Uf (02) to Uf (25), Df (02) to Df (25), Rf (02) to Rf (25), and Lf (02) to the basic pixel groups 402 to 425 are displayed. Lf (25) is generated. By arranging these pixel signals in the vertical direction and the horizontal direction, line data for focus detection by the phase difference method in each line can be obtained.

  4, pixel signals Uf (01), Uf (08), Uf (15), Uf (22),... Are line U images for focus detection of the line V1 (Line V1). Pixel signals Df (01), Df (08), Df (15), Df (22),... Are line D images for focus detection of the line V1. The CPU 109 obtains the focus information for the horizontal line related to the line V1 by calculating the correlation between the U image and the D image to obtain the phase difference information. Similarly, pixel signals Uf (05), Uf (12), Uf (19),... Are line U images for focus detection of line V2 (Line V2). Pixel signals Df (05), Df (12), Df (19),... Are line D images for focus detection of the line V2. The CPU 109 obtains the focus information for the horizontal line related to the line V2 by calculating the correlation between the U image and the D image to obtain the phase difference information. Similarly, the CPU 109 can obtain focus information for the horizontal lines of the lines V3 to Vn. As shown in FIG. 4, in the present embodiment, the line V1 and the line V2 are arranged at positions where their sampling positions are shifted from each other by half phase. Thereby, the sampling density is virtually improved, and highly accurate focus detection is possible.

  The pixel signals Lf (01), Lf (02), Lf (03), Lf (04),... Are line L images for focus detection of the line H1 (Line H1). Pixel signals Rf (01), Rf (02), Rf (03), Rf (04),... Are line R images for focus detection of the line H1. The CPU 109 obtains the focus information for the vertical line related to the line H1 by calculating the correlation between the L image and the R image to obtain the phase difference information. Similarly, pixel signals Lf (05), Lf (06), Lf (07), Lf (08),... Are line L images for focus detection of the line H2 (Line H2). Pixel signals Rf (05), Rf (06), Rf (07), Rf (08),... Are line R images for focus detection of the line H2. The CPU 109 obtains focus information for the vertical line in the line H2 by performing correlation calculation between the L image and the R image to obtain phase difference information. Similarly, the CPU 109 can obtain focus information for the vertical lines H3 to Hn. As shown in FIG. 4, in this embodiment, the line H <b> 1 and the line H <b> 2 are arranged at positions where their sampling positions are shifted from each other by a half phase. Thereby, the sampling density is virtually improved, and highly accurate focus detection is possible.

  Subsequently, processing of the imaging signal generation circuit 102a will be described. In FIG. 2, for example, the pixel 204 lacks information in the third quadrant, and a sensitivity difference from the unmasked pixel 207 occurs as it is, and a photographed image with spots like spots is formed. For this reason, some correction processing is required. Therefore, when the corrected pixel signal of the pixel 204 is COR (204), the imaging signal generation circuit 102 performs the correction represented by the following equations (4a) to (4d). Here, the pixel signals (pixel data) described with reference to FIG.

COR (204) = B + (A + C + D−2 × E) (4a)
COR (202) = A + (B + C + D−2 × E) (4b)
COR (210) = D + (A + B + C−2 × E) (4c)
COR (212) = C + (A + B + D−2 × E) (4d)
Thereby, correction is performed using information close to the missing information. However, the correction method is not limited to this. For example, correction can be performed simply as represented by the following formula (5).

COR (204) = (B × 4) ÷ 3 (5)
Or you may correct | amend so that it may be represented by the following formula | equation (6).

COR (204) = B + ((A + C + D−2 × E) ÷ 2) + (B ÷ 6) (6)
In the present embodiment, the number N of the plurality of first pixels (focus detection pixels) included in the unit pixel group of the image sensor 101 has been described as four. However, the present invention is not limited to this. If the number N of the plurality of first pixels is 3 or more (N ≧ 3), the present embodiment can be applied to obtain the same effect as the present embodiment. In the present embodiment, each of the plurality of first pixels has a mask (dead zone) in one different region divided into N (N ≧ 3). In the specific example of this embodiment, the number of the plurality of first pixels is four, and each of the plurality of first pixels has a mask (dead zone) in one quarter region different from each other divided into four. The case where it has is explained.

Preferably, in the focus detection signal generation circuit 102b, the sum D _1n of the pixel data of each of the plurality of first pixels and the pixel data D ₂ of the _second pixel are D _1n = D ₂ × (N−1). Determine whether the relationship is satisfied. This determination is not only strictly equal, but also when it is evaluated as being substantially equal (when substantially equal), that is, whether D _1n ≈D ₂ × (N−1) is satisfied. It can also be done. At this time, a predetermined threshold value may be set. More preferably, when this relationship is satisfied, the focus detection signal generation circuit 102b outputs a focus detection signal to the CPU 109 (focus detection means).

  Preferably, the focus detection signal generation circuit 102b is obtained by subtracting the pixel data of each of the plurality of first pixels (pixel signals A to D) from the pixel data (pixel signal E) of the second pixel. A focus detection signal is generated using a plurality of first signals (pixel signals A ′ to D ′). More preferably, the focus detection signal generation circuit 102b includes at least two different signals (two different pixels among the pixel signals A ′ to D ′) among the plurality of first signals (pixel signals A ′ to D ′). Signal) is added to generate a focus detection signal.

  Next, a second embodiment of the present invention will be described. In the present embodiment, the configuration of an image sensor 101 (image sensor) including focus detection pixels having a pixel arrangement with a higher density than that of the first embodiment will be described.

  FIG. 5 is an explanatory diagram of a focus detection signal (focus detection pixel data) in the present embodiment. FIG. 5 is a partial area cut out of the entire image sensor, and corresponds to FIG. 4 described in the first embodiment. Further, as described with reference to FIG. 2, the black area is a mask area, and each dotted square corner is one pixel of the image sensor 101. The image sensor of the present embodiment is different from the image sensor of Embodiment 1 in which pixels without masks and lines with masks are alternately arranged in that pixels masked in all lines are arranged. In FIG. 5, circles denoted by reference numerals 501 to 503 indicate basic pixel groups (unit pixel groups), respectively.

  Next, the processing of the focus detection signal generation circuit 102b in the present embodiment will be described with reference to FIG. FIG. 6 is an explanatory diagram of a process for generating a focus detection signal (focus detection pixel data). The masked signals among the pixel signals of the basic pixel groups 501 to 503 are denoted by A to D, respectively, as shown in FIG. First, the focus detection signal generation circuit 102b calculates the pixel signal E as represented by the following formula (7).

E = (A + B + C + D) ÷ 3 (7)
Next, the focus detection signal generation circuit 102b uses the pixel signal E calculated by Expression (7) as the signal in each quadrant, and converts the pixel signals A ′, B ′, C ′, and D ′ into the following Expression (8a). ) To (8d).

E−A = A ′ (8a)
E−B = B ′ (8b)
E−C = C ′ (8c)
E−D = D ′ (8d)
Since the subsequent processing is the same as that of the first embodiment, description thereof is omitted here.

  Next, Embodiment 3 of the present invention will be described with reference to FIGS. FIG. 7 is a pixel configuration diagram of the image sensor in the present embodiment. FIG. 8 is a pixel array diagram of the image sensor in the present embodiment.

  In Example 1 and Example 2, the masked area (mask area) in one pixel is an area obtained by equally dividing a square pixel into squares. On the other hand, in this embodiment, as shown in FIG. 7A, the mask region is configured in a triangular shape (black portion in FIG. 7A) when a diagonal line is drawn in one pixel (west pixel). Has been. Since the mask region only needs to be configured symmetrically with respect to the optical axis, a configuration as shown in FIG. 7A can also be adopted.

  FIG. 7B is a configuration example in which the mask region shown in the first embodiment is further halved diagonally. The mask area is one-eighth of the entire area of one pixel, and the aperture ratio is high, and the sampling ability as a focus detection pixel is slightly lowered, but the sensitivity as an imaging pixel is high, and pixel scratches are not noticeable. . As shown in the first embodiment and the second embodiment, this configuration is established if 8 pixels or 9 pixels are used as a basic pixel group (unit pixel group). FIG. 7C shows another form of the configuration in which the mask region shown in the first embodiment is halved. The mask area is one-eighth of the entire area of one pixel, and the aperture ratio is high, and the sampling ability as a focus detection pixel is slightly lowered, but the sensitivity as an imaging pixel is high, and pixel scratches are not noticeable. . Similar to the configuration of FIG. 7B, this configuration is established if 8 pixels or 9 pixels are used as a basic pixel group.

  In the present embodiment, a pixel arrangement as shown in FIG. 8 can also be adopted. The pixel arrangement is not limited to the Bayer arrangement, and pixels such as circles and polygons can also be used. FIG. 8A shows a configuration in which hexagonal pixels are arranged, and the mask areas are different from each other in one-sixth areas. FIG. 8B also shows a configuration in which hexagonal pixels are arranged, and the mask regions are different from each other in one-third regions. Even with the pixel configuration and pixel arrangement of the present embodiment, it is possible to generate the focus detection signal by applying the calculation formula described in the first embodiment.

  In each embodiment, preferably, the plurality of first pixels and second pixels have the same shape. Preferably, the plurality of first pixels and second pixels are symmetrical with respect to the pixel center. More preferably, the symmetrical shape is a circle or a regular polygon. Preferably, the symmetrical shape is an ellipse or a polygon, and is symmetric with respect to the pupil shape.

[Other Embodiments]
The present invention is also realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and the computer (or CPU, MPU, etc.) of the system or apparatus reads the program. To be executed. In this case, a computer-executable program describing the procedure of the imaging apparatus control method and a storage medium storing the program constitute the present invention.

  According to each embodiment, when a focus detection pixel is used as an imaging pixel, a large amount of information can be obtained, so that a flaw in a captured image can be made inconspicuous. Further, by using the focus detection pixel as the imaging pixel, the density of the focus detection pixel can be increased, and the focus detection performance is also improved. Therefore, according to each embodiment, using an imaging device including a focus detection pixel, an imaging device, an imaging system, an imaging device control method, a program, and an imaging device that achieve both high-precision focus detection and high-quality image generation, and A storage medium can be provided.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

DESCRIPTION OF SYMBOLS 10 Imaging device 101 Imaging sensor 102a Focus detection signal generation circuit 102b Imaging signal generation circuit 109 CPU

Claims (15)

An image sensor including a plurality of first pixels having a dead zone and a unit pixel group composed of a second pixel not having the dead zone;
First signal generating means for generating an imaging signal using pixel data from at least the second pixel;
Second signal generating means for generating a focus detection signal using pixel data from the plurality of first pixels and the second pixels;
Focus detection means for performing focus detection based on the focus detection signal,
The number of the plurality of first pixels included in the unit pixel group is N (N ≧ 3),
Each of the plurality of first pixels has the dead zone in one different region divided into N (N ≧ 3).   The imaging apparatus according to claim 1, wherein the plurality of first pixels are focus detection pixels, and the second pixel is an imaging pixel.   The imaging device according to claim 1, wherein the plurality of first pixels and the second pixels have the same shape.   4. The imaging apparatus according to claim 1, wherein the plurality of first pixels and the second pixels are symmetrical with respect to a pixel center. 5.   The imaging apparatus according to claim 4, wherein the symmetrical shape is a circle or a regular polygon.   The imaging apparatus according to claim 4, wherein the symmetrical shape is an ellipse or a polygon and is symmetric with respect to a pupil shape. The second signal generation means is configured such that the total pixel data D _1n of each of the plurality of first pixels and the pixel data D ₂ of the _second pixel are D _1n = D ₂ × (N−1). The imaging apparatus according to claim 1, wherein it is determined whether or not a relationship is satisfied.   The imaging apparatus according to claim 7, wherein the second signal generation unit outputs the focus detection signal to the focus detection unit when the relationship is satisfied.   The second signal generation means uses the plurality of first signals obtained by subtracting the pixel data of the plurality of first pixels from the pixel data of the second pixel to perform the focus detection. The imaging apparatus according to claim 1, wherein a signal is generated.   The imaging apparatus according to claim 9, wherein the second signal generation unit generates the focus detection signal by adding at least two different signals among the plurality of first signals. . The number of the plurality of first pixels included in the unit pixel group is 4,
11. The imaging apparatus according to claim 1, wherein each of the plurality of first pixels has the dead zone in a different one-fourth region divided into four. 11. A lens unit;
An imaging system comprising: the imaging device according to claim 1. A control method for an imaging device including an imaging device including a plurality of first pixels having a dead zone and a unit pixel group including a second pixel not having the dead zone,
Generating an imaging signal using pixel data from at least the second pixel;
Generating a focus detection signal using pixel data from the plurality of first pixels and the second pixels;
Performing focus detection based on the focus detection signal,
The number of the plurality of first pixels included in the unit pixel group is N (N ≧ 3),
Each of the plurality of first pixels has the dead zone in one different region which is divided into N (N ≧ 3).   A program configured to cause a computer to execute the control method of the imaging apparatus according to claim 13.   A storage medium storing the program according to claim 14.