JP2018042157A - Imaging apparatus and focal point detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely detect a phase difference without an error in a case where a defective row excluded in a photographing image is included in an image for detecting the phase difference.SOLUTION: An imaging apparatus includes: an imaging element 100 capable of acquiring a first signal based on a beam having passed through a partial region of a photographic optical system exit pupil from a first photoelectric conversion part, a second signal based on a beam having passed through a partial region different from the partial region of the photographic optical system exit pupil from a second photoelectric conversion part, and a third signal based on a beam having passed through a whole region of the photographic optical system exit pupil; row addition means of adding first and second signals to a row direction and generating first and second addition signals; and phase difference arithmetic means of calculating a phase amount acquired on the basis of the phase difference between the first and second addition signals. The imaging apparatus includes means of removing, when there is a defective row constructed by defective pixels appearing in the first and second signals as defection although no appearance in the third signal, the defective row from a target row of the row addition to perform row addition.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an imaging device and a focus detection device.

  2. Description of the Related Art Conventionally, there is a technique of performing phase difference type focus detection simultaneously with imaging by using a configuration in which pixels in an imaging element receive light from different pupil planes of an imaging lens. In Patent Document 1 to Patent Document 2, by dividing a photodiode (hereinafter referred to as PD) collected by one microlens in one pixel, each PD has a different pupil plane of the imaging lens. It is configured to receive light. Thereby, the focus detection by the imaging lens is performed by comparing the outputs of the two PDs. Moreover, in patent document 3, it is comprised so that the light of the different pupil plane of an imaging lens may be light-received by changing the wiring layer in front of PD with a pixel.

  In these technologies, image shift amount detection, that is, phase difference detection, is performed from each PD signal that has received light from different pupil surfaces of the imaging lens, and the focus shift amount is calculated from the image shift amount to detect the focus. Is going.

  In the case of an imaging apparatus that detects a phase difference with an imaging element, it is desirable to use a two-dimensional distance measurement area instead of a one-dimensional detection area. This is because the distance measurement area of only one row has a distance measurement area in the row direction only for the pixel pitch of the image sensor, and the distance measurement area is too narrow. However, when using a two-dimensional ranging area, if a defective row in which defective pixels continue in the column direction is included in the row of the ranging area, an error occurs in the phase difference detection result, and the phase difference The accuracy of detection is reduced.

  In addition, in the case of an image sensor having two PDs with one microlens, it takes twice as long to read the two PDs individually. In Patent Document 4, although it is not a configuration of phase difference detection in an image sensor having two PDs with one microlens, a PD signal sharing two readout circuits is read at high speed. Specifically, the reset signal is read out, then the first PD signal is read, and then added to the first PD signal to read the second PD signal.

  In this way, the second PD signal can be obtained by subtracting the first PD signal from the addition signal of the two PDs, and the speed is increased by reducing the number of times the reset signal is read. Is realized. This technique can contribute to speeding up even when the phase difference is detected by the image sensor.

JP 2001-083407 A JP 2001-250931 A Japanese Patent No. 3592147 JP 2004-134867 A

  By the way, when performing phase difference detection with an image sensor, a signal obtained by adding two PDs is used as an image signal, and the signals obtained by separately reading two PD signals are used for phase difference detection. . In this case, a signal obtained by adding two PD signals is normally output, but the signal of each PD may be defective. Specifically, when reading the signal of the first PD, the signals of the two PDs are mixed and read due to a defect. In this case, two PD signals are read when the first PD signal is read, and two PD signals are obtained when the synthesized PD signal is read.

  That is, even if the first PD signal is subtracted from the synthesized PD signal, the second PD signal cannot be obtained. As described above, when the signals of the two PDs are read at high speed, it is possible that the image used for phase difference detection has a defect even though the photographed image has no defective row. As described above, if the image used for the phase difference detection has a defect, the accuracy of the phase difference detection is lowered. Defective rows in captured images are usually treated as defective, but even if there are no defective rows in the captured image, even if there are defective rows in the image for phase difference detection, if they are treated as defective, the yield will be reduced End up.

  Therefore, an object of the present invention is to accurately detect a phase difference without generating an error when a defective row not included in a captured image is present in an image for phase difference detection.

An imaging optical system for forming an imaging light beam and pixels having microlenses are arranged in a matrix, and the pixels have at least two or more photoelectric conversion units, from the first photoelectric conversion unit of the photoelectric conversion units The first signal based on the light beam that has passed through a partial region of the exit pupil of the photographing optical system and the partial region of the exit pupil of the photographing optical system from the second photoelectric conversion unit of the photoelectric conversion unit. An imaging device capable of acquiring a second signal based on a light beam that has passed through a different partial area, and a third signal based on a light beam that has passed through the entire area of the exit pupil of the photographing optical system, , And the second signal are added in the row direction to generate a first addition signal and a second addition signal, and the order of the first addition signal and the second addition signal. A phase difference calculating means for calculating a correlation amount obtained based on the phase difference; In the imaging apparatus,
If there is a defective row composed of defective pixels that do not appear as defects in the third signal but appear as defects in the first signal and the second signal, the defective row is defined as the row. A means for excluding the addition target line and performing the line addition;

  According to the present invention, when there is a defective row that is not in the captured image in the phase difference detection image, the phase difference can be detected without generating an error, so that the yield of the image sensor can be improved. Also, by excluding defective rows from the pixel addition target, it is possible to simultaneously improve the ranging performance for low-luminance subjects and low-contrast subjects by pixel addition and reduce the load of correlation calculation processing.

1 is a diagram schematically showing an overall configuration of an image sensor according to an embodiment of the present invention. It is a figure which shows the outline of a structure of 1 pixel of the image pick-up element of embodiment of this invention. It is a figure showing roughly a pixel array of an image sensor of an embodiment of the present invention. It is a figure which shows typically the imaging relationship of an object. It is a figure which shows typically the circuit of the pixel of this invention. 4 is a timing chart showing a drive pattern of the image sensor according to the embodiment of the present invention. It is a figure which shows typically the relationship between the defective row and output of an image signal, A image signal, and B image signal. It is a figure which illustrates the focus detection of a phase difference system typically. 1 is a system configuration diagram including an image sensor related to phase difference detection according to a first embodiment of the present invention. It is a figure which shows the outline of the imaging device of this invention. It is a figure which shows roughly the ranging area of the image pick-up element of embodiment of this invention. It is a flowchart figure which shows the focus adjustment of embodiment of this invention.

[Example 1]
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an outline of an image sensor of the present invention. In FIG. 1, the image sensor 100 includes a pixel array 101, a vertical selection circuit 102 that selects a row in the pixel array 101, and a horizontal selection circuit 104 that selects a column in the pixel array 101. Further, it may be configured to include a readout circuit 103 that reads a signal of a pixel selected by the vertical selection circuit 102 among the pixels in the pixel array 101, and a serial interface 105 for determining an operation mode of each circuit from the outside. The reading circuit 103 includes a memory for storing signals, a gain amplifier, an AD converter, and the like for each column.

The image sensor 100 includes a timing generator or a control circuit for providing timing to the vertical selection circuit 102, the horizontal selection circuit 104, the signal reading unit 103, and the like, in addition to the illustrated components.

Typically, the vertical selection circuit 102 sequentially selects a plurality of rows of the pixel array 101 and reads them to the reading circuit 103. The horizontal selection circuit 104 sequentially selects a plurality of pixel signals read by the reading circuit 103 for each column. FIG. 2 is a diagram showing an outline of the configuration of one pixel of the image sensor 100 of the present invention. 201 represents a pixel. One pixel has a microlens 202. One pixel has two photodiodes (hereinafter referred to as PDs), PD203 and PD204. Transfer switches 205 and 206 for reading out the signals of the PD 203 and PD 204 and a floating diffusion 207 for temporarily storing the PD signals are also provided. The pixel includes a plurality of constituent elements to be described later in addition to the illustrated constituent elements.

  FIG. 3 is a diagram illustrating the pixel array 101. The pixel array 101 is configured by arranging a plurality of pixels as shown in FIG. 2 in a two-dimensional array in order to provide a two-dimensional image. Reference numerals 301, 302, 303, and 304 denote pixels. 301L, 302L, 303L, and 304L are the PD 203 shown in FIG. 2, and 301R, 302R, 303R, and 304R are the PD 204 shown in FIG.

  The state of light reception in the image sensor 100 having the pixel configuration as shown in FIG. 3 will be described with reference to FIG. FIG. 4 is a conceptual diagram in which the light beam emitted from the exit pupil of the photographing lens enters the image sensor 100.

  Reference numeral 401 denotes a cross section of the pixel array. Reference numeral 402 denotes a microlens, reference numeral 403 denotes a color filter, and reference numerals 404 and 405 denote photodiodes. PD 404 and PD 405 are PD 203 and PD 204, respectively, as shown in FIG. Reference numeral 406 denotes an exit pupil of the photographing lens.

  Here, for the pixel having the microlens 402, the center of the light beam emitted from the exit pupil is defined as the optical axis 409. The light emitted from the exit pupil enters the image sensor 100 with the optical axis 409 as the center. Reference numerals 407 and 408 denote partial areas of the exit pupil of the photographing lens. The outermost rays of light passing through the partial area 407 of the exit pupil are indicated by 410 and 411, and the outermost rays of light passing through the partial area 408 of the exit pupil are indicated by 412 and 413. As can be seen from this figure, among the light beams emitted from the exit pupil, the upper light beam is incident on the PD 405 and the lower light beam is incident on the PD 404 with the optical axis 409 as a boundary.

  That is, each of the PD 404 and the PD 405 receives light from another area of the exit pupil of the photographing lens. The present invention is a pixel for detecting a phase difference in a pixel arranged two-dimensionally with a configuration capable of separately acquiring information of a light beam emitted from an exit pupil of a photographing lens by an image sensor, although the photographed image has no defective row. As long as the image has a defective line, the configuration is not limited to that described.

In the imaging device, A pixels and B pixels that receive light from different exit pupils of the imaging lens are two-dimensionally arranged. Referring to FIG. 3, in the row 305, the pixels 301L, 302L, 303L, and 304L are defined as A pixels, and the pixels 301R, 302R, 303R, and 304R are defined as B pixels. An image formed by the A pixel is defined as an A image, and an image that can be formed by the B pixel is defined as a B image.

FIG. 5 is an equivalent circuit diagram showing a circuit configuration relating to pixels constituting the pixel portion of FIG. Here, pixels for three columns and one row are schematically described.

  In FIG. 5, 201 indicates a pixel. Reference numerals 203 and 204 denote the PDs described above. The transfer switches 205 and 206 are driven by transfer pulses φTX1 and φTX2, respectively, and are switches that transfer photocharges generated in the PDs 203 and 204 to the floating diffusion 207, respectively. An FD 207 is a floating diffusion unit (FD) that serves as a buffer for temporarily storing charges, 501 is an amplification MOS amplifier that functions as a source follower, and 502 is a selection switch that selects a pixel by a vertical selection pulse φSEL.

A floating diffusion amplifier is configured by the FD 207, the amplification MOS amplifier 501, and a constant current source (not shown). The signal charge of the FD 207 of the pixel selected by the selection switch 502 is converted into a voltage and output to the vertical output line 503 for reading. Read out to the circuit 103. Reference numeral 504 denotes a reset switch that receives the reset pulse φRES and resets the FD 207 with VDD. As described above, the PD 203 and the PD 204 have transfer switches 205 and 206 corresponding to the PD 203 and the PD 204, respectively, but the circuits used for signal readout after the FD 207 are shared among circuits in the pixel. With such a configuration, the pixels can be reduced. Further, as shown in the figure, the wirings that provide the transfer pulses φTX1 and φTX2 are shared in one row.

Next, a method for driving the solid-state imaging device having the above configuration will be described. FIG. 6 is a timing chart showing drive patterns. The driving for reading out one row of signals to the reading circuit will be described. First, during t601, φRES, φTX1, and φTX2 are simultaneously set to a high potential (hereinafter, “H”), so that the reset switch 504 and the transfer switches 203 and 204 are turned on, and the potentials of PD203, PD204, and FD207 are set to VDD. Reset to initial potential. Thereafter, when φTX1 and φTX2 become low potential (hereinafter “L”), charge accumulation starts in the PDs 203 and 204.

  Next, after the elapse of a predetermined time determined based on the charge accumulation time, φSEL is set to H at t603 and the selection switch 502 is turned on to select a reading row, and a signal reading operation for one row is performed. At the same time, φRES is set to L, and the FD 207 is released from reset.

  φTN is set to H during t604, and the N signal which is a reset signal of the FD 207 is read and recorded in the reading circuit 103. Although not shown, the readout circuit 103 reads the potential of the FD 207 through the vertical output line based on the control of φTN, φS1, and φS2, and records each signal.

  Next, during t605, φTX1 and φS1 are simultaneously set to H to turn on the transfer switch 205, thereby recording the first PD signal, which is an addition signal of the optical signal of the PD 203 and the N signal, in the readout circuit 103. Next, in a state where the reset switch 504 is not turned on, φTX1, φTX2, and φS2 are simultaneously set to H during t606 to turn on the transfer switches 205 and 206, thereby turning on the PD203 optical signal, the PD204 optical signal, and the N signal. The second PD signal that is the addition signal is recorded in the readout circuit 103. Since φTX1 is turned on once at time t604 and the signal of the PD 203 is read out to the FD 207, φTX1 may be off at time t606. Strictly speaking, the accumulation time t602 is from the end of t601 to the end of t606.

  The N signal, the first PD signal, and the second PD signal read to the readout circuit 103 by the above operation are the A image signal obtained by subtracting the N signal from the first PD signal and the image signal obtained by subtracting the N signal from the second PD signal. Selected by the horizontal scanning circuit and output to the outside of the image sensor. Since the image signal is a signal obtained by combining the signals of PD 203 and PD 204, the B image signal is generated by subtracting the A image signal from the image signal. Although the A image signal, the B image signal, and the image signal are obtained by the above-described operation, a case where the wiring of φTX1 and the wiring of φTX2 are short-circuited due to a manufacturing defect is considered. At this time, φTX2 that should originally be at L becomes H at time t605.

  Then, in the operation of reading the first PD signal, the second PD signal is read. The second PD signal is not affected because φTX1 and φTX2 become H at the same time. As a result, in the row where the φTX1 wiring and φTX2 wiring are shorted, the image signal is obtained as usual, but the A image signal reads the same signal as the image signal, and further subtracts the A image signal from the image signal. As a result, the B image signal to be obtained disappears. That is, there is no problem with the image signal in that row, but the phenomenon that the A and B images are defective rows occurs. FIG. 7 is a diagram schematically showing signal levels of the image signal and the A image signal B image signal.

  Here, of the arrangement of 4 rows and 4 columns, only the 3rd row indicates a defective row, and when it is normal, the image signal is 2, and both the A image signal and the B image signal have a signal of 1. Since the B image signal is obtained by subtracting the A image signal from the image signal, since the normal row is the image signal 2 and the A image signal 1, the B image signal is 1. For the defective row, the image signal is 2 and normal, but the A image signal is 2 which is the same signal as the image signal, and the B image signal is 0. Next, a description will be given of distance measurement calculation that is detection of a phase difference that makes use of the characteristic that an image of another region of the exit pupil of the photographing lens can be obtained by the image sensor.

  Although known, the distance measuring method will be described with reference to FIG. The upper part of FIG. 8 shows pixel arrangements arranged in one row for each of the A and B images of the distance measuring area of the image sensor, and the lower part shows images at each focus position. 8A shows a focused state, FIG. 8B shows a front pin state, and FIG. 8C shows a rear pin state. As can be seen from FIG. 8, the A line data and the B line data, which are data for one row of the A image and the B image, can be obtained depending on whether the in-focus state, the front pin state, or the rear pin state. The intervals are different.

The focusing lens of the imaging lens is moved so that the image interval becomes the in-focus interval, and the focus is adjusted. That is, the amount of movement of the focusing lens can be calculated from the amount of deviation between the two images. However, in the defective row, there is an incorrect signal on the A image side and no signal on the B image side, so the interval between the two images cannot be calculated.

Next, a distance measuring method considering a defective row will be described. FIG. 9 is a system configuration diagram including an image sensor related to phase difference detection. As described above, the image signal and the A image signal are output from the image sensor. The image signal and the A image signal from the image sensor may be output simultaneously or in time series. The ranging calculation circuit generates a B image by subtracting the A image signal from the image signal from the image sensor at the B image generation unit. The distance measuring circuit has a defective line recording memory for recording the address of the above-described defective line. The ranging calculation unit performs a ranging calculation, which will be described later, from the A image signal and the B image signal. However, the ranging calculation unit does not perform the ranging calculation for the defective row recorded in the defective row recording memory.

  Details will be described later. With respect to the information on the defective row recorded in the defective row recording memory, it is possible to obtain information on the defective row by performing a test at the time of shipment of the imaging device or the imaging apparatus. Specifically, as described above, a defective row can be extracted from a row in which the image signal and the A image signal are the same signal, or a row in which the B image signal does not have a signal. Information on a row that is determined to be a defective row in a test at the time of shipment is recorded in a defective row recording memory. Further, not only a test at the time of shipment but also a defective row can be extracted at the time of starting the imaging apparatus. Next, based on FIG. 10, an embodiment when the above-described imaging device is applied to a digital camera as an imaging device will be described in detail.

  In FIG. 10, reference numeral 1001 denotes a lens unit that forms an optical image of a subject on the image sensor 1005, and zoom control, focus control, aperture control, and the like are performed by a lens driving device 1002. Reference numeral 1003 denotes a mechanical shutter which is controlled by the shutter control means 1004. Reference numeral 1005 denotes an image sensor for taking in the subject imaged by the lens unit 1001 as an image signal. Reference numeral 1006 denotes image signal processing for performing various corrections on the image signal output from the solid-state image sensor 1005 and compressing data. Circuit.

  Further, the distance calculation circuit described above is also included. Reference numeral 1007 denotes a solid-state imaging device 1005, a timing generation circuit that is a driving unit that outputs various timing signals to the imaging signal processing circuit 1006, 1009 a control circuit that controls various operations and the entire imaging apparatus, and 1008 temporarily stores image data. Memory for storing, 1010 is an interface for recording or reading on a recording medium, 1011 is a detachable recording medium such as a semiconductor memory for recording or reading image data, and 1012 is various information and photographed images. It is a display part to display.

  Next, the operation of the digital camera at the time of shooting in the above configuration will be described. When the main power supply is turned on, the power supply for the control system is turned on, and the power supply for the image pickup system circuit such as the image pickup signal processing circuit 1006 is turned on.

  Then, when a release button (not shown) is pressed, the distance calculation described above is performed based on the data from the image sensor, and the distance to the subject is calculated based on the distance measurement result. At that time, defective line information is obtained from a memory (not shown), and the defective line is omitted from the distance measurement calculation. Or replace with the data of the previous line. Thereafter, the lens unit is driven by the lens driving device 1002 to determine whether or not the lens unit is in focus. When it is determined that the lens unit is not in focus, the lens unit is driven again to perform distance measurement.

  Then, after the in-focus state is confirmed, the photographing operation starts. When the photographing operation is completed, the image signal output from the solid-state imaging device 1005 is subjected to image processing by the photographing signal processing circuit 1006 and written to the memory by the control circuit 1009. In the photographing signal processing circuit, rearrangement processing, addition processing, and selection processing thereof are performed. Data stored in the memory 1008 is recorded on a removable recording medium 1011 such as a semiconductor memory through the recording medium control I / F unit 1010 under the control of the control circuit 1009.

  Further, the image may be processed by directly inputting to a computer or the like through an external I / F unit (not shown).

  Next, a method for calculating the distance between the two images of the A image and the B image, which is a distance measurement calculation according to the present invention, will be described with reference to FIGS. FIG. 11A is a diagram illustrating an example of a distance measurement area 1101 set in the shooting range 1100. When focus detection is performed using the pixel output of the image sensor 100, the pixel output of the pixel array 101 corresponding to the distance measurement area 1101 is used. Therefore, it can be said that the distance measurement area 1101 is set in the pixel array 101. In the following, the distance measurement area 1101 will be described as the pixel area of the pixel array 101 for ease of explanation and understanding.

  In FIG. 11A, the distance measurement area 1101 indicates that the Y direction is a range from r rows to s rows. FIG. 11B shows the arrangement of the color filters 403 for each pixel of the pixel array 101. R (1,1) has a red color filter, Gr (2,1) and Gb (2,1) have a green color filter, and B (2,2) has a blue color filter. Arranged to form a Bayer array.

  FIG. 12 is a flowchart showing a flow of adjusting the focus state by obtaining the focus shift amount from the image data obtained from the image sensor. When ranging calculation starts, the first row Y = r is selected in S1201.

  In step S1202, an initialization operation for clearing the addition memory is executed. The addition memory is used to add pixel signal outputs of the A image and the B image included in the ranging area 1101 in the Y direction from r rows to s rows. By adding a plurality of pixel signals, random noise can be reduced, and in particular, ranging performance of a low-luminance subject or a low-contrast subject can be improved. Further, since the correlation calculation described later performs processing with a relatively high system load, the processing load can be reduced by reducing the number of pixels input to the correlation calculation in advance by pixel addition.

  In S1203, based on the information of the defective row address recorded in the defective row recording memory, it is determined whether or not the currently selected Y row and Y + 1 row are defective rows. If it is determined that it is not a defective row, the process advances to step S1204 to output the pixel signals of the currently selected Y row and Y + 1 row A and B images and the A image in the addition memory, and B The pixel signals of the image are added for each pixel and stored in the addition memory. Then, it progresses to S1205. If it is determined as a defective row, the pixel addition process is not executed and the process proceeds to S1205.

  That is, the defective row is excluded from the pixel addition target. In S1205, Y + 2 is substituted for Y and the selected row is advanced by two. In the present embodiment, as described above, since the color filters arranged in the pixels are configured as a Bayer array, the defective row determination (S1203), the pixel in units of two rows with the Y row and the Y + 1 row as a pair. By performing the addition process (S1204) and the line feed (S1205), the influence on the distance measurement accuracy due to the color balance of the pixel signals in the addition memory being lost is avoided.

  In S1206, Y> S is compared, and it is determined whether the currently selected Y row has reached the S row at the lower end of the distance measuring area 1101. If the Y row has not reached the S row, the process proceeds to S1203, and pixel addition processing in the Y direction is executed until the S row is reached. In step S1107, correlation calculation processing is performed to calculate a shift amount that maximizes the correlation between the A image and B image signals in the addition memory. The correlation amount COR (k) used for the correlation calculation can be calculated by the following equation (1), for example.

  The variable k used in the equation (1) is a shift amount at the time of correlation calculation, and is an integer from −kmax to kmax. The variable l indicates the starting point of the subject area for calculating the correlation amount, and the variable w indicates the data length of the subject area for calculating the correlation amount. The center of gravity position of the A image and the B image on the exit pupil plane generates an image signal by a photoelectric change unit that is symmetrically biased in the horizontal (X-axis) direction. Arise.

  Therefore, in Expression (1), the subject areas of the A image and the B image are given a predetermined shift amount by the variable k to calculate the correlation amount between the subject areas of the A image and the B image.

  After obtaining the correlation amount COR (k) for each shift amount k, the shift amount k at which the correlation between the A image and the B image is the highest, that is, the value of the shift amount k that minimizes the correlation amount COR is obtained. Note that the shift amount k at the time of calculating the correlation amount COR (k) is an integer, but when obtaining the shift amount k that minimizes the correlation amount COR (k), in order to improve the accuracy of the defocus amount, Interpolation processing is performed as appropriate to obtain a value (real value) in units of subpixels. In the present embodiment, the shift amount dk in which the sign of the difference value of the correlation amount COR changes is calculated as the shift amount k that minimizes the correlation amount COR (k).

First, the correlation value difference value DCOR is calculated according to the following equation (2).
DCOR (k) = COR (K) −COR (K−1) (2)
Then, a shift amount dk at which the sign of the difference amount changes is obtained using the difference value DCOR of the correlation amount. If the value of k immediately before the sign of the difference amount changes is k1, and the value of k where the sign changes is k2 (k2 = k1 + 1), the shift amount dk is calculated according to the following equation (3).

dk = k1 + | DCOR (k1) | / | DCOR (k1) −DCOR (k2) | (3)
As described above, the shift amount dk that maximizes the correlation amount between the A image and the B image is calculated in units of subpixels, and the process of S1207 is completed. The method for calculating the phase difference between the two one-dimensional image signals is not limited to that described here, and any known method can be used.

  In step S1208, the shift amount dk is converted into the defocus amount DEF by multiplying the shift amount dk by, for example, sensitivity stored in advance in a non-illustrated nonvolatile memory. When the calculation of the defocus amount DEF ends, the defocus amount calculation process ends. In step S1209, the lens driving amount of the photographing lens 1001 is calculated based on the defocus amount DEF obtained in step S1208.

  In step S <b> 1210, information on the lens driving amount and the driving direction is transmitted to the focus control unit 1002 of the photographing lens 1001. The focus control unit 1002 drives the focus focus lens based on the received lens driving amount and driving direction information. Thereby, the focus of the photographic lens 1001 is adjusted.

  As described above, in the case of performing a distance measurement calculation in two dimensions, even if a defective row not included in the image signal is present in the A image signal or the B image signal, the distance measurement is performed by excluding the defective row. The influence on accuracy can be suppressed. Therefore, it is possible to use an image sensor having a defective row only in the A image signal and the B image signal, and the yield can be improved.

  Also, by excluding defective rows from the pixel addition target, it is possible to simultaneously improve the ranging performance for low-luminance subjects and low-contrast subjects by pixel addition and reduce the load of correlation calculation processing.

1001 photographing lens, 1002 lens driving device, 1003 mechanical shutter,
1004 Shutter control means, 1005 imaging device, 1006 imaging signal processing circuit,
1007 Timing generation unit, 1008 memory, 1009 overall control calculation unit (CPU),
1010 Recording medium control, I / F unit, 1011 Recording medium, 1012 External I / F unit

Claims (3)

A photographic optical system (1001) for forming an image of a photographic light beam;
Pixels having microlenses are arranged in a matrix, the pixels have at least two or more photoelectric conversion units, and the first photoelectric conversion unit (203) of the photoelectric conversion units has an exit pupil of the photographing optical system. A first signal based on the light beam that has passed through the partial area and a partial area different from the partial area of the exit pupil of the imaging optical system from the second photoelectric conversion unit (204) of the photoelectric conversion unit. An image sensor (1005) capable of acquiring a second signal based on the light beam that has passed through and a third signal based on the light beam that has passed through the entire area of the exit pupil of the imaging optical system;
A row addition means (1006) for adding the first signal and the second signal in the row direction to generate a first addition signal and a second addition signal;
In the imaging apparatus having phase difference calculation means (S1207) for calculating a correlation amount obtained based on the phase difference between the first addition signal and the second addition signal,
If there is a defective row composed of defective pixels that do not appear as defects in the third signal but appear as defects in the first signal and the second signal, the defective row is defined as the row. An imaging apparatus characterized by excluding from addition target rows and performing the row addition. The imaging device according to claim 1,
The pixel is an image sensor in which color filters having different spectral characteristics are periodically arranged in units of m rows × n columns, and when there is the defective row, m rows including the defective row are added to the row. An imaging apparatus characterized in that the row addition is performed by excluding the target from the above. In the imaging device according to claim 1 or 2,
The imaging apparatus further comprises a focus adjusting unit (S1210) for adjusting a focus state of the photographing optical system based on an output of the phase difference calculating unit.