JP2018182549A - Imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus that is able to realize a more appropriate photographic image through appropriate focus detection without dropping yield of an imager in focus detection using an imaging-surface phase difference system.SOLUTION: An imaging apparatus comprises: an imager having a plurality of photoelectric conversion parts in one micro-lens, configured to have a first drive in which at least two or more groups into which pixel signals are divided are separately read from the plurality of photoelectric conversion parts and a second drive in which pixel signals are read all at once from the plurality of photoelectric conversion part, and capable of setting the first drive for an arbitrary row; defective-row database means in which defective-row information of a pupil division signal of the imager is stored in advance; and reading control means that exerts reading control in which the first drive is not performed for the defective row stored in the defective-row database means. The reading control means includes performing the first drive for a non-defective row near the defective row for which the first drive has not been performed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an imaging device, and more particularly to an imaging device that acquires recording pixels and focus detection pixels from an image signal obtained from an imaging device.

  In an imaging device using a focusing optical system and an imaging element, a photoelectric conversion unit of a pixel unit provided under a focusing microlens formed on the imaging element is divided into a plurality of parts, and the emission of the focusing optical system is performed. Patent document 1 is mentioned as a technique for acquiring the image which divided | segmented the pupil as an image signal, and performing focus detection based on the image signal containing the image which divided | segmented the said exit pupil.

  In addition, as a method of reading out pixels from an imaging device, Patent Document 2 can be cited as a technology that can improve manufacturing yield and reduce cost by reading out rows or columns including defective pixels.

JP, 2013-106194, A Japanese Patent Application Laid-Open No. 9-284656

  However, in the configuration of the prior art, the following problems occur. In the technique disclosed in Patent Document 1, when a defect caused by manufacturing variation of an imaging element or the like, in particular, a defect occurs continuously in a line (line) direction, the line is used for focus detection calculation. In this case, the accuracy of focus detection is reduced. Further, in the technique disclosed in Patent Document 2, if the row including the defective pixel is skipped for the row including the pixel for focus detection, the pixels for focus detection are reduced, and the accuracy of focus detection is lowered.

  The present invention has been made in view of the problems of the related art as described above, and in focus detection using the imaging surface phase difference method, a preferred captured image is realized by suitable focus detection without lowering the yield of the imaging device. Providing an imaging device capable of

In order to achieve the above object, an imaging device according to the present invention is
A first drive having a plurality of photoelectric conversion units in one microlens and reading out pixel signals by dividing into at least two or more from the plurality of photoelectric conversion units, and pixel signals at one time from the plurality of photoelectric conversion units An imaging element capable of setting the first drive to an arbitrary row; defect row database means storing in advance defect row information of pupil division signals of the imaging device; and the defect row The read control means for performing read control not to perform the first drive with respect to the defective line stored in the database means, and the read control means are provided in the vicinity of the defect line for which the first drive was not performed. And performing the first driving on a non-defective row.

  According to the present invention, in focus detection using the imaging surface phase difference method, a suitable captured image can be realized by suitable focus detection without lowering the yield of the imaging device.

The figure which shows the structure of the imaging device which concerns on the 1st Embodiment of this invention. Block diagram showing the configuration of the imaging device A conceptual diagram in which a light flux emitted from the exit pupil of the photographing lens is incident on a unit pixel A diagram for explaining a pixel circuit and a column circuit of an imaging device according to an embodiment of the present invention A conceptual view that the image A and the image B of the imaging device according to the embodiment of the present invention become a defective row A diagram showing an example of reading out the A + B image and the A image from part of the imaging screen A diagram showing an example of thinning-out reading of readout of image A in a frame with respect to a distance measurement frame Flow chart showing photographing processing according to the embodiment of the present invention Flowchart showing still image shooting processing according to an embodiment of the present invention Flow chart showing focus state detection processing according to an embodiment of the present invention Diagram schematically showing an example of a distance measurement area handled in focus state detection processing A diagram showing an example of an image signal obtained from the focus detection area shown in FIG. FIG. 13 shows an example of the relationship between the shift amount of the image signal and the correlation amount shown in FIG. 12 FIG. 13 shows an example of the relationship between the shift amount of the image signal and the correlation change amount ΔCOR shown in FIG. 12 Diagram showing defective rows of imaging elements The figure which illustrated the reading interval of A picture to the whole image pick-up screen concerning a 1st embodiment of the present invention The figure which shows the structure of the imaging device which concerns on the 2nd Embodiment of this invention. The figure which illustrated the reading interval of A picture to the whole image pick-up screen concerning a 2nd embodiment of the present invention

  Below, each embodiment of the present invention is described in detail based on an attached drawing.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an example of a functional configuration of a lens-interchangeable camera as an example of an imaging device according to an embodiment of the present invention. The imaging apparatus of the present embodiment is composed of a replaceable lens unit 101 and a camera body 102. The lens control unit 108 that integrally controls the operation of the entire lens and the camera control unit 124 that generally controls the operation of the entire camera system including the lens unit 101 can communicate with each other through a terminal provided on the lens mount.

  First, the configuration of the lens unit 101 will be described. The fixed lens 103, the diaphragm 104, and the focus lens 105 constitute an imaging optical system. The diaphragm 104 is driven by the diaphragm drive unit 106 to control the amount of light incident on the image sensor 110 described later. The focus lens 105 is driven by the focus lens drive unit 107, and the focusing distance of the imaging optical system changes according to the position of the focus lens 105. The diaphragm drive unit 106 and the focus lens drive unit 107 are controlled by the lens control unit 108 to determine the aperture of the diaphragm 104 and the position of the focus lens 105.

  The lens operation unit 109 is an input device group for the user to make settings regarding the operation of the lens unit 101, such as switching of AF / MF mode, setting of shooting distance range, and setting of camera shake correction mode. When the lens operation unit 109 is operated, the lens control unit 108 performs control according to the operation.

  The lens control unit 108 controls the diaphragm drive unit 106 and the focus lens drive unit 107 according to control commands and control information received from a camera control unit 124 described later, and transmits lens control information to the camera control unit 124. .

  Next, the configuration of the camera body 102 will be described. The camera body 102 is configured to be able to obtain an imaging signal from the light flux that has passed through the imaging optical system of the lens unit 101.

  The imaging element 110 is configured of a CCD or a CMOS sensor. A light flux incident from the photographing optical system of the lens unit 101 forms an image on the light receiving surface of the imaging element 110, and is converted into a signal charge according to the incident light amount by a photodiode provided in a pixel arrayed in the imaging element 110 Ru. The signal charge stored in each photodiode is sequentially read out from the imaging device 110 as a voltage signal corresponding to the signal charge from the drive pulse output from the timing generator 126 in accordance with an instruction from the camera control unit 124.

  Here, the imaging element 110 according to the present embodiment will be described with reference to FIG. In this embodiment, each of the microlenses 201 forming the microlens array is defined as one pixel, and this is defined as a unit pixel 202.

  In addition, a plurality of divided pixels are arranged to correspond to one microlens 201. In the present embodiment, the unit pixel 202 has two divided pixels in the X-axis direction, which are respectively defined as 201A and 201B.

  FIG. 3 is a view of a state in which light emitted from the fixed lens 103 passes through one microlens 201 and is received by the imaging device 110 from a direction perpendicular to the optical axis Z (Y-axis direction). . Reference numerals 301 and 302 denote the exit pupils of the photographing lens.

  The light passing through the exit pupil is incident on the unit pixel 202 around the optical axis Z. As shown in FIG. 3, the light flux passing through the pupil region 301 is received by the micro lens 201 at 201 A, and the light flux passing through the pupil region 302 is received by the micro lens 201 at 201 B. Therefore, each of 201A and 201B receives light in different regions of the exit pupil of the photographing lens. The signal of 201A thus pupil-divided is acquired from the plurality of unit pixels 202 aligned in the X-axis direction, and an object image composed of these output signal groups is taken as an A-image. Similarly, a pupil-divided signal 201 B is acquired from a plurality of unit pixels 202 aligned in the X-axis direction, and an object image formed by these output signal groups is taken as a B image.

  A correlation operation is performed on the A and B images to detect the amount of image shift (pupil division phase difference). Further, by multiplying the shift amount of the image by the focal position and a conversion coefficient determined from the optical system, it is possible to calculate the focal position corresponding to an arbitrary object position on the screen. By controlling the focus lens 105 (not shown in FIG. 3) based on the focus position information calculated here, imaging surface phase difference AF becomes possible. Further, by adding the A image signal and the B image signal to the A + B image signal, this A + B image signal can be used for the above-described imaging pixel.

  In the characteristic part of the present invention, the range for reading out the signal of the photodiode A in the image sensor 110 is set in the AF signal generation range setting unit to be described later, and the division with the range for reading only the imaging pixel (A + B image) I do. Based on the focus detection pixels obtained from the photodiode A, two image signals are generated by an addition signal separation unit 112 described later, and the AF signal processing unit 114 performs correlation operation on the two image signals, and an image shift is generated. Calculate quantity and various reliability information.

  The CDS / AGC / AD converter 111 performs correlated double sampling and gain adjustment to remove reset noise with respect to the imaging pixel (A + B image) and the focus detection pixel (A image) read from the imaging element 110. Digitize the signal. The signal processed by the CDS / AGC / AD converter 111 is input to the addition signal separation unit 112, and the addition signal separation unit 112 subtracts the A image from the A + B image to generate a B image, and processes the A + B image. The image A and the image B are output to the AF signal processing unit 114, respectively.

  The image processing unit 113 performs known image processing such as color conversion, white balance, and gamma correction, resolution conversion processing, image compression processing, and the like on the imaging signal output from the CDS / AGC / AD converter 111, for example. The image signal subjected to each processing is stored in the SDRAM 121 via the bus 116. The image signal stored in the SDRAM 121 is read by the display control unit 117 via the bus 116 and displayed on the display unit 118. In the operation mode for recording an imaging signal, the image signal stored in the SDRAM 121 is recorded on the recording medium 120 by the recording medium control unit 119.

  The ROM 122 stores control programs to be executed by the camera control unit 124 and various data required for control, and the flash ROM 123 stores various setting information and the like regarding the operation of the camera body 102 such as user setting information and the like. There is.

  The AF signal processing unit 114 performs a correlation operation on the two image signals (image A and image B) for AF output from the addition signal separation unit 112, and generates an image shift amount, reliability information (degree of image coincidence, Two image steepness, contrast information, saturation information, flaw information, etc. are calculated. Each process described above is performed on each distance measurement area based on the distance measurement area designation signal from the camera control unit 124. Further, the AF signal processing unit 114 outputs the image shift amount and the reliability information calculated for each distance measurement area to the camera control unit 124.

  In the defect row database unit 115, row information of A and B images to be defect rows is set in advance in the imaging element 110, and the defect row information is read from a camera control unit 124 described later.

  Here, a method of reading out two image signals (A and B images) for AF and an image signal (A + B image) from the image pickup element 110 of the present embodiment will be described with reference to FIG. A conceptual diagram of the fact that the image is a defect row and the image for recording is not a defect row will be described using FIG. 5 to define the defect row in the present invention.

  FIG. 4 is a view showing an example of a circuit and a column circuit showing the unit pixel 202 of the imaging device 110 in the embodiment of the present invention. The unit pixel 401 (202 in FIG. 2) has first and second PDs 402A and 402B. The transfer switch 403A is connected to 402A, and the transfer switch 403B is connected to the other 402B. The transfer switches 403A and 403B transfer the charges generated by the PDs 402A and 402B to the common FD 405, respectively.

  The charges transferred from the PDs 402A and 402B are temporarily held by the FD 405, converted into voltages, and output from the source follower amplifier (SF) 406. A selection switch 407 collectively outputs pixel signals of one row to the vertical output line 408.

  A reset switch 404 resets the potential of the FD 405 and the potentials of the PDs 402A and 402B to VDD via the transfer switches 403A and 403B. The transfer switches 403A and 403B are controlled by transfer pulse signals PTXA and PTXB, respectively. The reset switch 404 and the selection switch 407 are respectively controlled by signal lines PRES and PSEL connected to the vertical scanning circuit. 409 is a constant current source.

  The circuit configuration of the column circuit 410 will be described. An amplifier 411 amplifies the signal of the pixel. A capacitor 413 holds a signal voltage, and a switch 412 controls writing to the capacitor 413. The switch 412 is turned on and off by control of the signal line PSH. Reference numeral 414 denotes a comparator, which receives the reference voltage Vslope supplied from the slope voltage generation means at one end, and the output of the amplifier 411 at the other end. The comparator 413 compares the output of the amplifier 411, that is, the signal from the pixel with Vslope, and takes two values of low level and high level depending on the magnitude relationship. Specifically, it takes a low level when Vslope is smaller than the output of the amplifier 411, and takes a high level when it is larger. A counter 415 counts up in response to CLK. CLK starts simultaneously with the start of the Vslope transition, and the counter 415 operates when the output of the comparator 414 is at high level, and stops the counting signal at the same time when the output of 414 reverses to low level.

  The unit pixel 401 has two PDs, and in the mode for performing imaging plane phase difference AF, the A image signal and the A + B image signal are separately read (details will be described later). Therefore, the column circuit 410 includes two memories for holding AD converted digital signals. A memory 416 holds a digital signal obtained by AD-converting the signal of the PD 402A (hereinafter referred to as S (A) signal). A memory 417 holds a digital signal obtained by AD-converting the signals 402A and 402B (hereinafter, S (A + B) signal). The signals held in the memories 416 and 417 are output to the digital output processing circuit 419 through the horizontal output line 418 by the signal from the horizontal scanning circuit.

  Here, an A image read out signal from the AF signal generation range setting unit 127 described later is received, and if it is an A image read out line, the A signal is read out from the memory 416. It outputs to the digital processing circuit 419 via When it is not the A image reading line, the A + B signal is output from the memory 417 alone to the digital processing circuit 419 through the horizontal output line 418.

  Although the image A signal, the image B signal, and the image signal are obtained by the above-described operation, it is assumed here that the wiring of the transfer pulse PTXA and the wiring of the transfer pulse PTXB are shorted due to a manufacturing defect. In this case, the PD 402 B signal is read out in the operation of reading out the A image signal. The A + B image signal has no effect because the transfer pulse PTXA and the transfer pulse PTXB are simultaneously H at the same time. As a result, in the row in which the line of the transfer pulse PTXA and the line of the transfer pulse PTXA are shorted, an image signal can be obtained as usual, but the same signal as the image signal is read out as an A image signal. Further, the B image signal obtained by subtracting the A image signal from the image signal loses the signal. That is, although there is no problem in the image signal of the row, the phenomenon that the A and B image signals are defective occurs.

  FIG. 5 is a view schematically showing signal levels of the image signal, the A image signal and the B image signal. Here, in the arrangement of 4 rows and 4 columns, only the third row indicates a defective row, and in the normal case, the image signal is 2 and both the A image signal and the B image signal are 1. Since the B image signal is obtained by subtracting the A image signal from the image signal, the B image signal is 1 since the normal row is the image signal 2 and the A image signal is 1. For a defective row, the image signal is normal at 2 but the A image signal is 2 of the same signal as the image signal, and the B image signal is 0.

  The definition of a defective row in the present invention is a row in which the transfer pulse PTXA and the transfer pulse PTXB are shorted due to a manufacturing defect as described above.

  Based on the image shift amount and the reliability information obtained by the AF signal processing unit 114, the defective line information read out from the defective line database unit 115, and the state information of the lens 101 and the camera 102, the camera control unit 124 is necessary. As a result, the setting of the AF signal processing unit 114 is changed or defective row information is output to the AF signal generation range setting unit 127. For example, processing such as changing the type of band pass filter for the AF signal processing unit 114 according to the contrast information. Defective row information is output to the AF signal generation range setting unit as the characteristic setting of the present invention.

  The camera control unit 124 performs control by exchanging information with each functional block in the camera body 102. The camera control unit 124 turns on / off the power, changes settings, starts recording, starts AF control, checks recorded images, etc. according to the input from the camera operation unit 125 as well as processing in the camera body 102. Perform various camera functions operated by the user. In addition, the camera control unit 124 sends control instructions and control information of the lens unit 101 to the lens control unit 108, and acquires information of the lens unit 101 from the lens control unit 108.

  The camera control unit 124 is, for example, one or more programmable processors, and executes the control program stored in the ROM 122, for example, to realize the entire operation of the camera system including the lens unit 101.

  The camera control unit 124 controls the focus lens 105 via the lens control unit 108 based on the result of one specific distance measurement area among the correlation calculation results acquired for each of the plurality of distance measurement areas from the AF signal processing unit 114. Drive.

  The AF signal generation range setting unit 127 receives the control information of the camera 102 acquired from the camera control unit 124, the information of the state of the lens 101, and the defective line information from the camera control unit 124 with respect to the imaging device 201. The A image signal is transmitted to the image sensor 110 so as to maintain the periodicity of the readout signal.

  In the present embodiment, when the AF position set by the user at the camera operation unit 125 is set as shown in FIG. 6, as shown in FIG. 7, instead of always reading out the A + B image and the A image from all the AF areas. Then, the readout of the A image signal in the frame is thinned out and read out periodically.

  Details regarding the operation of the AF signal generation range setting unit 127 that performs the control will be described later using a flowchart that describes control of the camera body 102.

  Next, the operation of the camera body 102 will be described using FIG. 8 to FIG. FIG. 8 is a flowchart showing the procedure of shooting processing of the camera body 102. In step S801, the camera control unit 124 performs initialization processing such as camera settings, and advances the processing to step S802. In step S802, the camera control unit 124 determines whether the shooting mode of the camera body 102 is the moving image shooting mode or the still image shooting mode. If the moving image shooting mode is selected, the process proceeds to step S803. If the still image shooting mode is selected, the process proceeds to step S804. .

  In step S803, the camera control unit 124 performs moving image shooting processing, and the processing proceeds to step S805. If the still image shooting mode is selected in S802, the camera control unit 124 performs still image shooting processing in S804, and the process proceeds to S805.

  The present invention can be applied to both moving image and still image shooting modes, but in the present embodiment, control by still image shooting processing in S804 will be described based on FIG. In the present embodiment, the details of the moving image shooting process of S803 will be omitted. In step S805, the camera control unit 124 determines whether the shooting processing has been stopped. If the shooting processing has not been stopped, the processing proceeds to step S806 and is stopped. If it has been, the photographing process is ended. When shooting processing is stopped, operations other than shooting, such as when the power of the camera body 102 is turned off through the camera operation unit 125, user setting processing for the camera, playback processing for checking captured images and videos, etc. Is done.

  In step S806, the camera control unit 125 determines whether the shooting mode has been changed. If it has been changed, the process proceeds to step S801. If it is not changed, the process proceeds to step S802. , Return the process. If the shooting mode has not been changed, the camera control unit 124 continues the processing of the current shooting mode, and if the shooting mode is changed, the processing of the shooting mode is changed after the initialization processing is performed in S801. I do.

  Next, the still image photographing process of S804 in FIG. 8 will be described with reference to FIG. In step S901, the camera control unit 124 performs focus state detection processing, and advances the processing to step S902. The focus state detection process is a process of acquiring defocus information and reliability information for performing imaging plane phase difference AF by the camera control unit 124, the AF signal processing unit 114, and the AF signal generation range setting unit 127, Details will be described later with reference to FIG. In step S902, the camera control unit 124 determines whether an AF instruction has been issued by the camera operation unit 125. If the AF instruction has been issued, the process advances to step S903. If the AF instruction is not issued, the camera control unit 124 performs step S904. Proceed to

  In the present embodiment, the AF instruction indicates the case where the shutter button is pressed halfway or the case where the AF ON button for performing AF is pressed. Of course, the AF instruction may be performed by other means. In step S 903, the camera control unit 124 performs an AF process, and ends the still image shooting process.

  In step S904, the camera control unit 124 determines whether a shooting instruction is issued by the camera operation unit 125. If the shooting instruction is issued, the process proceeds to step S905. If not, the process advances to step S 907. In the present embodiment, the photographing instruction indicates the case where the shutter button is fully pressed. Of course, the configuration may be such that the photographing instruction is issued by other means.

  In step S905, the camera control unit 124 determines whether it is in the in-focus stop state by the AF processing in step S903. If it is not in the in-focus stop state, the process proceeds to step S903. If the in-focus state is not in effect, the process advances to step S906. If it is determined in step S905 that the subject is not in focus, it is determined that the subject is not in focus, and the subject is brought into focus by starting or continuing AF processing.

  In step S906, the camera control unit 124 performs photographing processing, stores the photographed image in the recording medium 120 via the recording medium control unit 119, and advances the process to step S907. If a shooting instruction has not been issued in step S904, or the process advances after the shooting process is performed in step S906, the camera control unit 124 cancels the in-focus stop state in step S907 and ends the still image shooting process. When the shooting is completed or when the AF / shooting instruction has not been issued, the state is reset to the non-focused state.

  Next, the focus state detection process of S901 in FIG. 9 will be described using FIG. First, in step S1001, the camera control unit 124 acquires parameter information used for AF that the camera body 102 or the lens 101 has, and the process proceeds to step S1002. The imaging parameters are information including the diaphragm information of the diaphragm 104 in the lens 101, the sensor gain applied to the imaging element 110 in the camera body 102, and the like, and the camera does not depend on the configuration of the present embodiment. Necessary information may be acquired appropriately according to the configuration. Based on the camera parameters, the camera control unit 124 provides information so that it can be applied to the process related to AF signal generation in the AF signal processing unit 114 and the process in the AF signal generation range setting unit 127.

  Next, in step S1002, the camera control unit 124 performs setting / arrangement of a ranging area position where the focus state detection is performed from within the focus detection range of the imaging screen. The method of setting / arranging may be, for example, setting an area set by the user as the distance measuring area position as long as the configuration allows object detection. Next, in step S1003, the AF signal generation range setting unit 127 generates a range for generating two image signals used for AF of the imaging surface phase difference detection method from within the imaging screen based on the defective row information held by the camera control unit 124. It decides and advances processing to S1004.

  At this time, based on the control parameters set in S1001, the ranging area position set in S1002, the other AF control information calculated in the focus state detection process, etc., the range for generating the two-image signal is suitable. Control to change as appropriate.

  Further, setting the range for generating the two-image signal means setting, in the imaging device as shown in FIG. 2, which range the scanning line for generating the A-image signal is to be set. In a line which does not generate two image signals, only one signal is generated as an A + B image signal. By controlling the range in which the two-image signal is generated to a non-defective row, it is possible to acquire an A-image signal and a B-image signal optimal for focus detection.

  Next, in S1004, the AF signal processing unit 114 acquires a pair of image signals (A image signal and B image signal) for AF from the pixels included in the image data generation range set in S1003. Next, in S1005, the AF signal processing unit 114 calculates the amount of correlation between the acquired image signals. The correlation amount is calculated for each scanning line in the image data generation range set in S1003 within the ranging area, and the processing from S1004 to S1009 in the subsequent stage is similarly performed for each scanning line in the ranging area. Do for each Subsequently, in S1006, the AF signal processing unit 114 calculates the amount of change in correlation from the amount of correlation calculated in S1005.

  Then, in S1007, the AF signal processing unit 114 calculates the image shift amount from the correlation change amount. In S1008, the AF signal processing unit 114 calculates the reliability indicating how reliable the image shift amount is. Then, in S1009, the AF signal processing unit 114 converts the image shift amount calculated in S1008 into a defocus amount by multiplying the conversion coefficient, and ends the focus state detection processing.

  Next, the focus state detection processing described in FIG. 10 will be described in detail using FIGS. 11 to 14. FIG. 11 is a view schematically showing an example of the distance measurement area handled in the focus state detection process, and shows an example of the distance measurement area 1102 in the pixel array of the imaging device 201. The shift area 1103 is an area necessary for the correlation operation. Therefore, an area 1104 obtained by combining the distance measurement area 1102 and the shift area 1103 is a pixel area required for the correlation calculation. In the figure, p, q, s, and t respectively represent coordinates in the x-axis direction, p and q are x coordinates of the start point and end point of the pixel area 1104, and s and t are x points of the start point and end point of the distance measurement area 1102. Represents coordinates.

  FIG. 12 shows an example of an image signal for AF acquired from the pixels included in the distance measurement area 1102 set in FIG. The solid line 1201 is the image signal A, and the broken line 1202 is the image signal B. FIG. 12 (a) shows an example of the image signal before shifting. FIGS. 12 (b) and 12 (c) show a state in which the image waveform before the shift in FIG. 12 (a) is shifted in the positive and negative directions. When calculating the amount of correlation, both the image signal A 1201 and the image signal B 1202 are shifted by one bit in the direction of the arrow. Subsequently, a method of calculating the correlation amount COR will be described.

  First, as shown in FIGS. 12B and 12C, each of the image signal A 1201 and the image signal B 1202 is shifted by 1 bit, and the sum of the absolute value of the difference between the image signal A and the image signal B at that time is calculate. At this time, the shift amount is represented by i, the minimum shift amount is ps in FIG. 12, and the maximum shift amount is qt in FIG. Also, x is a start coordinate of the distance measurement area 1102, and y is an end coordinate of the distance measurement area 1202. Using these, the correlation amount COR in the focus detection area can be calculated by the following equation (1).

  FIG. 13A is a diagram showing an example of the relationship between the shift amount and the correlation amount. The horizontal axis indicates the shift amount, and the vertical axis indicates the correlation amount. The degree of coincidence between the image signal A and the image signal B is higher as the correlation amount is smaller among the extreme values 1302 and 1303 in the correlation amount waveform 1301. Subsequently, a method of calculating the correlation change amount ΔCOR will be described.

  First, from the correlation amount waveform of FIG. 13 (a), the correlation change amount is calculated from the difference between the correlation amounts of one shift skipping. The shift amount is represented by i, the minimum shift amount is p-s in FIG. 8, and the maximum shift amount is q-t in FIG. Using these, the correlation change amount ΔCOR can be calculated by the following equation (2).

FIG. 14A shows an example of the relationship between the shift amount and the correlation change amount ΔCOR. The horizontal axis indicates the shift amount, and the vertical axis indicates the correlation change amount. In the correlation change amount waveform 1401, reference numerals 1402 and 1403 denote areas around which the correlation change amount changes from plus to minus. It is called a state zero crossing where the amount of change in correlation is zero, the degree of coincidence between image signals is the highest, and the amount of shift at the time of zero crossing is the amount of image shift.
FIG. 14B is an enlarged view of a portion 1402 of FIG. 14A, and 1404 is a part of the correlation change amount waveform 1401. The method of calculating the image shift amount PRD will be described with reference to FIG.

  Here, the shift amount (k-1 + α) at the time of zero crossing is divided into an integer part β (= k-1) and a decimal part α. The fractional part α can be calculated by the following equation (3) from the similarity relationship between the triangle ABC and the triangle ADE in the figure.

  Subsequently, the integer part β can be calculated by the following equation (4) from FIG. 14 (b).

β = k−1 (4)
The image shift amount PRD can be calculated from the sum of α and β.

  Further, as shown in FIG. 14A, when there are a plurality of shift amounts at which the zero crossing occurs, the place where the steepness of the change in the correlation amount at the zero crossing is large is taken as the first zero crossing. The steepness is an index indicating the ease of AF, and indicates that the larger the value, the easier the AF is. The steepness maxder can be calculated by the following equation (5).

  As described above, when there are a plurality of zero crossings, the first zero crossing is determined by the steepness. Subsequently, a method of calculating the reliability of the image shift amount will be described. The reliability can be defined by the above-described sharpness and the degree of coincidence fnclvl of the image signals A and B (hereinafter referred to as the degree of coincidence between two images). The degree of coincidence between two images is an index indicating the accuracy of the image shift amount, and in the correlation calculation method in the present embodiment, the smaller the value, the better the accuracy.

  FIG. 13B is an enlarged view of a portion 1302 of FIG. 13A, in which 1304 is a part of the correlation amount waveform 1301. The calculation method of the sharpness and the degree of coincidence between two images will be described with reference to FIG. The two-image coincidence degree fnclvl can be calculated by the following equation (6).

  Next, the camera control unit 124 of FIG. 1 and the AF signal generation range setting unit 127, which are characteristic parts of the present invention, will be described with reference to FIGS. FIGS. 16A and 16B illustrate an area in which the A + B image and the A image are read out from the imaging element 110. FIG. Here, in addition to reading the A + B image for 126 lines in total, the case of reading 30 lines for reading the A image is illustrated.

  FIG. 16A shows the initial setting of the image pickup apparatus, in which the readout start position of the image A line is from the seventh line, and a 2-line A image is read for 8 lines periodically (A-image interval 6 lines) It is. At this time, for example, if there is a defect line on the 31st and 35th lines, when performing the focus state detection process using the 31st line when performing the above-mentioned focus state detection process, the focus state detection accuracy is improved. It will decrease.

  In addition, even when the focus state detection process is performed without using the 31st line which is a defective line, the number of lines for focus state detection decreases, so that the accuracy of the focus state detection decreases. Therefore, the camera control unit 124 reads the defective line information on the 31st and 35th lines as the defective line information shown in FIG. 15 and outputs the AF signal generation range setting unit 127.

  In FIG. 16B, the 31st and 35th lines are input as defect row information to the AF signal generation range setting unit 127, and the image signal is read out so that the defect row does not hit the A image line. Transmit to element 110. Specifically, with the start position of the readout signal of the A image line starting from the ninth row, a 2-row A image is read for 8 lines periodically (A image interval 6 lines) to form a defective row. You can get rid of it.

  As described above, the imaging device according to the present embodiment changes the reading start position of the scanning line that generates the two-image signal for performing the imaging plane phase difference AF, according to the defective row information. Therefore, in focus detection using the imaging plane phase difference method, a suitable captured image can be realized by suitable focus detection without lowering the yield of the imaging device. The scope of the present invention is not limited to the configuration exemplified in the present embodiment, and any other configuration may be adopted as long as the content of the present invention is achieved.

  As mentioned above, although the 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.

  A second embodiment of the present invention will be described using FIG. 16 (a), FIG. 17 and FIG. 18 as an example. In the following, the same symbols are given to the same components, and the description thereof is omitted.

  The AF signal generation range setting unit 1727 shown in FIG. 17 is an imaging device based on control information of the camera 102 acquired from the camera control unit 124, information on the state of the lens 101, and defective row information from the camera control unit 124. In step S201, the A image signal is transmitted to the image sensor 110 so as to avoid a defective line without maintaining periodicity in the readout signal.

  FIG. 16A shows the initial setting of the image pickup apparatus, in which the readout start position of the image A line is from the seventh line, and a 2-line A image is read for 8 lines periodically (A-image interval 6 lines) It is. At this time, for example, if there is a defect line on the 31st and 35th lines, when performing the focus state detection process using the 31st line when performing the above-mentioned focus state detection process, the focus state detection accuracy is improved. It will decrease. In addition, even when the focus state detection process is performed without using the 31st line which is a defective line, the number of lines for focus state detection decreases, so that the accuracy of the focus state detection decreases. Therefore, the camera control unit 124 reads the defective line information on the 31st and 35th lines as the defective line information shown in FIG. 18 and outputs the AF signal generation range setting unit 127.

  As shown in FIG. 18, the 31st and 35th lines are input to the AF signal generation range setting unit 127 as defective line information. The AF signal generation range setting unit 127 reads out the A image signal and transmits a signal to the imaging element 110 so that the defective line does not hit the A image line.

  Specifically, while the start position of the readout signal of the A image line remains on the seventh row, a 2-line A image is read for 8 lines periodically (A image interval 6 lines), but defective rows In order to avoid the 31st and 32nd lines, defective lines can be avoided by controlling the image sensor 110 so that the 33rd and 34th lines are read as the A image line without maintaining the periodicity. .

  As described above, the imaging device according to the present embodiment changes the reading of the scanning line for generating the two-image signal for performing imaging plane phase difference AF so as to avoid the defective row according to the defective row information. Therefore, in focus detection using the imaging plane phase difference method, a suitable captured image can be realized by suitable focus detection without lowering the yield of the imaging device. The scope of the present invention is not limited to the configuration exemplified in the present embodiment, and any other configuration may be adopted as long as the content of the present invention is achieved.

  As mentioned above, although the 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.

101 lens unit, 102 camera body, 103 fixed lens,
104 aperture, 105 focus lens, 106 aperture drive unit,
107 focus lens drive unit, 108 lens control unit, 109 lens operation unit,
110 imaging device, 111 CDS / AGC / AD, 112 addition signal separating means,
113 image processing unit 114 AF signal processing unit 115 defect row database unit
116 bus, 117 display control unit, 118 display unit, 119 recording medium control unit,
120 recording medium, 121 SDRAM, 122 ROM,
123 flash ROM, 124 camera control unit, 125 camera operation unit,
126 timing generator, 127 AF signal generation range setting unit,
201 micro lens, 202 unit pixels, 301, 302 exit pupils

Claims (3)

It has a plurality of photoelectric conversion units in one microlens,
A first drive for reading out pixel signals by dividing into at least two or more from the plurality of photoelectric conversion units;
A second drive for reading out pixel signals at one time from the plurality of photoelectric conversion units,
An imaging element capable of setting the first drive to an arbitrary row;
Defect row database means storing in advance defect row information of pupil division signals of the image pickup element;
A read control unit that performs read control not to perform the first driving on the defective rows stored in the defective row database unit;
An imaging apparatus characterized by having:   The imaging apparatus according to claim 1, wherein the read control unit performs the first drive on a non-defective row in the vicinity of the defective row in which the first drive is not performed.   The read control means sets the row for performing the first drive at a predetermined cycle, and performs the first drive so that the defective row does not hit the row for performing the first drive of the predetermined cycle. The imaging apparatus according to claim 1 or 2, wherein a start line is set.