Imaging device and its control method

Abstract

To provide an imaging apparatus capable of improving focus detection accuracy when performing focus detection using an imaging element having a pupil division function.SOLUTION: An imaging apparatus includes a pixel array having a plurality of pixel columns in which pixels are arranged in a matrix and each column of pixels is provided with a plurality of column output lines including a first column output line and a second column output line, and a readout circuit that reads out signals from pixels via column output lines, and the readout circuit performs a first readout scan for reading out signals from a first pixel group of the pixel array via the first column output line, and performs a second readout scan for reading out a signal via, the second column output line from a second pixel group different from the first pixel group of the pixel array, reads out a horizontal phase difference signal by the first readout scan, and reads out a vertical phase difference signal by the second readout scan.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to an imaging device and a control method thereof.

Background Art

[0002] Imaging devices such as digital cameras and video cameras use imaging elements such as CMOS image sensors.

[0003] Some imaging elements have a pupil division function. In an imaging device equipped with such an imaging element, automatic focus adjustment (autofocus) is possible by detecting the phase difference from a plurality of signals obtained by photoelectrically converting the pupil-divided subject image.

[0004] Patent Document 1 discloses an imaging device having an imaging element in which a plurality of photoelectric conversion units are provided for one microlens. In the imaging device disclosed in Patent Document 1, a phase difference signal between an A image signal and a B image signal is generated from the pupil-divided subject image. By performing a correlation operation on the A image signal and the B image signal, the amount of focus shift (defocus amount) can be calculated.

[0005] Further, Patent Document 2 discloses an imaging device that performs pupil division not only in the horizontal direction but also in the vertical direction and detects the phase difference. According to the imaging device disclosed in Patent Document 2, by switching the pupil division direction at a predetermined cycle, it is possible to suppress a decrease in focus detection accuracy due to a mismatch between the image separation direction of the imaging element and the image direction of the subject (vertical or horizontal line).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

[0007] As disclosed in Patent Document 2, if the separation direction of the image on the image sensor and the image direction of the subject do not coincide, the focus detection accuracy will decrease.

[0008] Furthermore, in the prior art disclosed in Patent Document 2, when reading pixel signals from multiple pixels arranged on an image sensor, the pixel signals are read sequentially in a predetermined direction. When acquiring phase difference signals divided into pupils in the horizontal direction (row direction) by sequentially reading pixel signals in the row direction, focus detection for the same row is possible in approximately the reading time of one row.

[0009] On the other hand, when acquiring phase difference signals divided vertically (in the column direction) by sequentially reading out pixel signals in the row direction, focus detection for the same column cannot be performed until all phase difference signals for that column have been read out. In other words, in order to perform focus detection in the column direction, it is necessary to read out approximately one frame's worth of signals, which takes time equivalent to the readout time for one frame. As a result, the time required for focus adjustment will differ depending on the scanning direction of the image sensor's signal readout and the direction of pupil division.

[0010] Furthermore, the difference in the time it takes for focus detection to become possible, due to the direction of pupil division and the direction of signal readout, has a greater impact on focus detection performance when the subject is moving.

[0011] In other words, when pupil division is horizontal (row-oriented), readout is completed in approximately one row's worth of time (several microseconds to tens of microseconds), so even if the subject is moving, the subject position shift is small. However, when pupil division is vertical (column-oriented), the readout time is approximately one frame's worth (several milliseconds to tens of milliseconds), so the subject position shift becomes relatively larger, and the focus detection performance deteriorates.

[0012] The present invention has been made in view of the above-mentioned problems, and its objective is to provide an imaging device that can improve focus detection accuracy when performing focus detection using an image sensor having pupil division function. [Means for solving the problem]

[0013] The imaging device according to the present invention has a pixel array having a plurality of pixel rows in which pixels are arranged in a matrix, and each row of pixels has a plurality of column output lines including a first column output line and a second column output line, and the signal from the pixels multiple The pixel array comprises a readout circuit that reads via a column output line, wherein the readout circuit performs a first readout scan that reads a signal from a first group of pixels of the pixel array via the first column output line, and a second readout scan that reads a signal from a second group of pixels of the pixel array different from the first group of pixels via the second column output line, characterized in that the first readout scan reads a horizontal phase difference signal and the second readout scan reads a vertical phase difference signal. [Effects of the Invention]

[0014] According to the present invention, when performing focus detection using an image sensor with pupil division functionality, it is possible to improve the accuracy of focus detection. [Brief explanation of the drawing]

[0015] [Figure 1] A diagram showing the configuration of the image sensor's pixels and surrounding circuits. [Figure 2] A diagram illustrating the pixel configuration in an image sensor. [Figure 3] Circuit diagram of pixels in an image sensor. [Figure 4] A schematic diagram showing the stacked structure of an image sensor. [Figure 5] A block diagram showing an example configuration of an imaging device. [Figure 6] A timing chart showing the first read operation. [Figure 7] A timing chart showing the second read operation. [Figure 8] Timing chart showing the third read operation. [Figure 9] Conceptual diagram showing vertical scanning and pupil division direction in the first embodiment. [Figure 10] Conceptual diagram showing vertical scanning and pupil division direction in the second embodiment. [Figure 11] Conceptual diagram showing vertical scanning and pupil division direction in the third embodiment. [Figure 12] Configuration diagram of pixels in the fourth embodiment. [Figure 13] Conceptual diagram showing vertical scanning and pupil division direction in the fourth embodiment.

Mode for Carrying Out the Invention

[0016] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential for the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant explanations are omitted.

[0017] (First Embodiment) FIG. 1 is a block diagram showing a configuration example of pixels and peripheral circuits of an image pickup device 100 according to the first embodiment of the present invention.

[0018] In FIG. 1, pixels 102 are arranged in a matrix in a pixel portion (pixel array) 101, and a so-called Bayer array in which color filters are formed in each is configured. In the present embodiment, it will be described assuming that two output lines are arranged in each pixel column of the pixel array, but the number of output lines is not limited to this, and any number such as 4, 12, 20, etc. can be arranged according to the required performance.

[0019] Pixel 102A is connected to column output line 105A by a selection switch (not shown), and outputs the pixel signal to column circuit 106A row by row. In this embodiment, pixels 102C, 102D, and 102F are also connected to column output line 105A.

[0020] Pixel 102B is connected to column output line 105B by a selection switch (not shown), and outputs the pixel signal to column circuit 106B row by row. In this embodiment, pixel 102E is also connected to column output line 105B.

[0021] Here, it is also acceptable to provide multiple selection switches for each pixel and configure it so that each pixel is connected to both column output lines 105A and 105B.

[0022] The selection switch is a switch that controls the selection of pixels in a specific row via the signal line 103 from the vertical scanning circuit 104, and is scanned in the row direction by the vertical scanning circuit 104.

[0023] The timing generator (TG) 110 generates pulse signals to control the vertical scanning circuit 104 and transistors within the pixels 102, as well as a reference signal. The digital-to-analog converter (DAC) 111 generates a reference signal (slope signal or ramp signal) whose level changes over time. The reference signal is input as one of the signals to the comparator 107 under the control of the TG 110.

[0024] Column circuits 106 include column circuits 106A and 106B, which correspond to column output lines 105A and 105B.

[0025] The column circuit 106 is configured to include a comparator 107, a counter 108, and a column memory 109.

[0026] One input of comparator 107 is connected to a reference signal generated by DAC 111, and the other input is connected to column output line 105. Comparator 107 compares the potential V of column output line 105 with the reference signal, which changes over time, and detects the time until their relative magnitudes reverse.

[0027] The counter 108 measures the time until the above-mentioned greater-than / less-than relationship reverses, based on the clock, and converts this measured time into a digital signal. The column memory 109 holds the digital signal measured by the counter 108.

[0028] The horizontal scanning circuit 112 scans the column circuit in the row direction and outputs the digital signals held in the column memory 109 through horizontal signal lines 113A and 113B that are commonly connected to each column. The horizontal scanning circuit 112 is also controlled by TG110.

[0029] Figure 2 shows the configuration of pixel 102. In Figure 2(a), the unit pixel 102 has sub-pixels 201, 202, 203, and 204, each containing a photoelectric conversion unit, and these four sub-pixels share a single microlens.

[0030] As shown in Figure 2(b), by separating and reading out the combined signals of subpixels 201 and 202 from those of subpixels 203 and 204, a pupil-divided signal in the left-right direction (row direction) is obtained. Also, as shown in Figure 2(c), by separating and reading out the combined signals of subpixels 201 and 203 from those of subpixels 202 and 204, a pupil-divided signal in the up-down direction (column direction) is obtained. Finally, as shown in Figure 2(d), the imaging signal is obtained by combining all the signals of the four subpixels.

[0031] Signals divided horizontally (in the row direction) are primarily suited for detecting subjects containing vertical lines, and this division direction is sometimes referred to as horizontal eye division. Similarly, signals divided vertically (in the column direction) are primarily suited for detecting subjects containing horizontal lines, and this division direction is sometimes referred to as vertical eye division.

[0032] In the following, the signals based on photoelectric conversion of sub-pixels 201, 202, 203, and 204 will be referred to as signals A, B, C, and D, respectively. Furthermore, the combined signal of sub-pixels 201 and 202 will be referred to as the A+B signal.

[0033] Figure 3 is a circuit diagram showing an example of the configuration of pixel 102. The photodiode (hereinafter referred to as PD) 301A, which is the photoelectric conversion unit included in the sub-pixel 201, is connected to a common floating diffusion (hereinafter referred to as FD) 303 via a transfer switch 302A. Here, the transfer switch 302A is controlled by a transfer pulse PTXA output from the vertical scanning circuit 104.

[0034] The same applies to sub-pixels 202, 203, and 204, with their respective PD301B, 301C, and 301D connected to a common FD303 via transfer switches 302B, 302C, and 302D. The transfer switches 302B, 302C, and 302D of each sub-pixel 202, 203, and 204 are controlled by transfer pulses PTXB, PTXC, and PTXD, respectively.

[0035] FD303 temporarily stores the charge transferred from PD301A~301D and converts the charge into voltage. The reset switch 304 is controlled by the reset pulse PRES and supplies a reference potential VDD to FD303.

[0036] The pixel amplifier 305 is a source follower circuit consisting of a MOS transistor and a constant current source. The selection switch 306 is controlled by a selection pulse PSEL and outputs the potential fluctuation of the pixel amplifier 305 from the column output line 105 to the column circuit 106.

[0037] Figure 4 is a schematic diagram showing the structure of the image sensor 100 of this embodiment. The image sensor 100 is constructed by stacking a first substrate 401 on which pixel sections 101 and the like are formed, and a second substrate 402 on which readout circuits such as column circuits 106 are formed.

[0038] The second circuit board 402 comprises a column circuit 106, a digital front end 403, and a circuit board memory 404. The column circuit 106 is electrically connected to the first circuit board 401 by bumps or the like. The digital front end 403 performs various calculation and correction processes. The circuit board memory 404 is a volatile memory such as DRAM and is used to temporarily hold data when the signals from the column circuit 106 are processed by the digital front end 403.

[0039] Figure 5 is a block diagram showing the configuration of the imaging device 500 in this embodiment.

[0040] The image sensor 100 converts incident light into an electrical signal and outputs it. The photographic lens 501 is controlled by the lens drive circuit 502, which controls the focus and other functions, and forms an optical image of the subject on the image sensor 100.

[0041] The shutter 503, which controls the exposure amount, is controlled by the mechanical drive circuit 504. The signal processing circuit 505 performs various calculations on the image signal, such as gain processing, offset correction processing, and white balance correction processing.

[0042] The image sensor 100 and the signal processing circuit 505 are connected by multiple signal lines. In the imaging device 500 of this embodiment, the signals output from the horizontal signal lines 113A and 113B of the image sensor 100 are independently input to the signal processing circuit 505.

[0043] The control circuit 506 controls the entire imaging device 500 while performing various processes such as driving control of the image sensor 100, autofocus calculation, and shutter control. The signal processing circuit 505 may be incorporated into the control circuit 506.

[0044] The memory circuit 507 is a memory that holds image data and offset correction values. The memory circuit 507 is also connected to the signal processing circuit 505. Furthermore, the memory circuit 507 may also be connected to the digital front end 403 of the image sensor 100, and may be configured to selectively communicate data and correction values.

[0045] The removable recording circuit 508, such as a semiconductor memory, records image data. The operation and display circuit 509 accepts user input and displays various information.

[0046] Figure 6 is a timing chart representing the first readout mode in this embodiment. Figure 6 shows the case where only the imaging signal is readout.

[0047] Assume that the pixel unit 101 is reset and charge accumulation begins by time t600. Here, the reset is performed by setting the reset pulse PRES to Hi and the transfer pulse PTX to Hi, and during charge accumulation, the reset pulse PRES is Hi and the transfer pulse PTX is Lo.

[0048] At time t601, a selection pulse PSEL connects a unit pixel 102 of a certain row to a column output line 105.

[0049] At time t602, the reset pulse PRES changes from Hi to Lo, and the potential V (N signal) of FD303 after the reset is released is input to comparator 107 via column output line 105.

[0050] At time t603, DAC111 begins outputting a reference signal VL that changes in a ramp-like manner. Simultaneously with DAC111 outputting the reference signal VL, the counter 108 begins counting.

[0051] At time t604, the relative magnitudes of the input signal and the reference signal VL are reversed, causing the output of the comparator 107 to invert, and the count value of the counter 108 at that time is stored in the column memory 109. Subsequently, after the reference signal VL transitions until it reaches a predetermined upper limit at time t605, the horizontal scanning circuit 112 outputs a signal, completing the reading of the signal (N signal) after the reset release of the pixel 102.

[0052] At time t606, the transfer pulses PTXA, PTXB, PTXC, and PTXD transfer the charge from the four sub-pixels 201-204 to FD303, and the potential V of the column output line 105 becomes the potential corresponding to the pixel signal (A+B+C+D signal). In addition, the comparator 107 is reset.

[0053] At time t607, DAC111 begins outputting a reference signal VL that changes in a ramp-like manner. Simultaneously with DAC111 outputting the reference signal VL, the counter 108 begins counting.

[0054] At time t608, the relative magnitudes of the input signal and the reference signal VL are reversed, causing the output of the comparator 107 to invert, and the count value of the counter 108 at that time is stored in the column memory 109. Subsequently, after the reference signal VL transitions until it reaches a predetermined upper limit at time t609, the horizontal scanning circuit 112 outputs a signal, completing the reading of the pixel signal (A+B+C+D signal) of pixel 102.

[0055] Subsequently, predetermined signal processing is performed, such as subtracting the N signal from the A+B+C+D signal.

[0056] The above series of operations are performed independently on the column output lines 105A, 105B, the column circuits 106A, 106B, and the horizontal signal lines 113A, 113B.

[0057] Figure 7 is a timing chart representing the second readout mode in this embodiment. Figure 7 shows the case where both the imaging signal and the left-right (horizontal) phase difference signal are read out.

[0058] The process from the time t705 when the reset is released until the end of reading the signal (N signal) is the same as in Figure 6, so the explanation is omitted.

[0059] At time t706, the transfer pulses PTXA and PTXB transfer the charge from sub-pixels 201 and 202 to FD303, and the potential V of column output line 105 becomes the potential corresponding to the pixel signal (A+B signal). In addition, comparator 107 is reset.

[0060] At time t707, DAC111 begins outputting a reference signal VL that changes in a ramp-like manner. Simultaneously with DAC111 outputting the reference signal VL, the counter 108 begins counting.

[0061] At time t708, the relative magnitudes of the input signal and the reference signal VL are reversed, causing the output of the comparator 107 to invert, and the count value of the counter 108 at that time is stored in the column memory 109. Subsequently, after the reference signal VL transitions until it reaches a predetermined upper limit value at time t709, the horizontal scanning circuit 112 outputs a signal. This completes the reading of the pixel signal (A+B signal) of pixel 102.

[0062] At time t710, the transfer pulses PTXA, PTXB, PTXC, and PTXD transfer the charge from the four sub-pixels 201-204 to FD303, and the potential V of the column output line 105 becomes the potential corresponding to the pixel signal (A+B+C+D signal). In addition, the comparator 107 is reset.

[0063] At time t711, DAC111 begins outputting a reference signal VL that changes in a ramp-like manner. Simultaneously with DAC111 outputting the reference signal VL, the counter 108 begins counting.

[0064] At time t712, the relative magnitudes of the input signal and the reference signal VL are reversed, causing the output of the comparator 107 to invert, and the count value of the counter 108 at that time is stored in the column memory 109. Subsequently, after the reference signal VL transitions until it reaches a predetermined upper limit value at time t713, the horizontal scanning circuit 112 outputs a signal. This completes the reading of the pixel signal (A+B+C+D signal) of pixel 102.

[0065] Subsequently, predetermined signal processing is performed, such as subtracting the N signal from the A+B signal and the A+B+C+D signal. Furthermore, the C+D signal is obtained by subtracting the A+B signal from the A+B+C+D signal. The imaging signal is formed by the A+B+C+D signal, and the phase difference signal is formed by the A+B signal and the C+D signal.

[0066] Figure 8 is a timing chart representing the third readout mode in this embodiment. Figure 8 shows the case where both the imaging signal and the vertical phase difference signal are read out.

[0067] Sections similar to those in Figure 7 are omitted from explanation as they would be redundant. The difference from Figure 7 is that the charge transfer at time t806 is performed by transfer pulses PTXA and PTXC. As a result, the charges of sub-pixels 201 and 203 are transferred to FD303, and the pixel signal (A+C signal) of pixel 102 is read out.

[0068] By subtracting the A+C signal from the A+B+C+D signal, the B+D signal is obtained. The A+B+C+D signal constitutes the imaging signal, and the A+C signal and the B+D signal constitute the phase difference signal.

[0069] The acquired imaging signal is used for live view display, etc., while the phase difference signal is used for focus detection, etc. If both signals are read out, whether both are used or only one is used depends on the operating mode of the imaging device.

[0070] Figure 9 is a conceptual diagram illustrating the relationship between the readout scan and the pupil division direction in the pixel signal readout operation of this embodiment. In Figure 9, six rows of pixels are shown as an example, illustrating the case where the readout scan is performed sequentially row by row.

[0071] In Figure 9, rows 6N, 6N+2, 6N+3, and 6N+5 represent rows for obtaining the phase difference signals for left-right pupil division, and these constitute the first pixel group. Rows 6N+1 and 6N+4 represent rows for obtaining the phase difference signals for upper-lower pupil division, and these constitute the second pixel group.

[0072] In this embodiment, the signals of the first pixel group are read out in a second readout mode via the column output line 105A, and this is referred to as scan 1. Similarly, the signals of the second pixel group are read out in a third readout mode via the column output line 105B, and this is referred to as scan 2.

[0073] The left diagram in Figure 9 shows a so-called slit-rolling operation, where the imaging timing is defined by a vertical synchronization signal (VD). The vertical axis of the diagram indicates the row number, and the horizontal axis indicates time. The solid line represents the signal readout timing for the corresponding row, the dashed line represents the reset timing (start of electronic shutter accumulation) for the corresponding row, and the hatched area corresponds to the exposure time for the corresponding row.

[0074] The signal readout for scan 1 begins with the vertical synchronization signal VD. The reset (start of accumulation) in scan 1 is initiated in the previous frame. After a predetermined time has elapsed since the start of the signal readout for scan 1, the signal readout for scan 2 begins independently. The reset (start of accumulation) for scan 2 can be set to a different timing and accumulation time than that of scan 1. For example, in scan 1's 6N+3 rows and scan 2's 6N+4 rows, accumulation occurs for different lengths during the same time period, and signal readout occurs in parallel on different systems during the same time period. Also, while scan 1 involves one signal readout per VD, scan 2 allows for multiple signal readouts.

[0075] In scan 1, four out of six rows are read out in order to perform live view imaging and detect focus in the left-right direction using the imaging device 100. On the other hand, in scan 2, two out of six rows are read out in order to prioritize the frame rate and detect focus in the up-down direction.

[0076] As described above, in this embodiment, scan 1 is performed with left and right pupil division, and scan 2 is performed with upper and lower pupil division, so focus detection is possible in both scans. Scan 2 reads out the pixel signals of the rows that were downsampled in scan 1, and since the number of signal readout rows is smaller than in scan 1, the phase difference signal can be acquired at high speed.

[0077] In other words, in scan 1, the signals from the first pixel group are read out at a first frame rate. Then, in scan 2, the signals from the second pixel group are read out at a second frame rate, which is faster than the first frame rate. Therefore, in scan 2, the readout time can be shortened compared to reading out the vertical phase difference signals in scan 1 (reduced to about one-third in this example), and it is possible to suppress the decrease in focus detection accuracy due to the high speed of the moving subject.

[0078] The imaging signal and phase difference signal read out during scan 1 and scan 2, respectively, undergo predetermined processing such as correction and correlation calculations by the signal processing circuit 505 and the control circuit 506. These are then used for live view display in the operation / display circuit 509 and for focusing the imaging lens 501 via the lens drive circuit 502. Focusing the imaging lens 501 is performed by the control circuit 506 using the phase difference signal read out during scan 1 or scan 2.

[0079] In this way, by dividing the scan according to the direction of the pupil division for autofocus for each selected row, it is possible to suppress the shift in the subject's position and improve the accuracy of focus detection, even when the pupil division is vertical and the subject is moving.

[0080] (Second embodiment) Figure 10 is a conceptual diagram illustrating the relationship between the readout scan and the pupil division direction in the pixel signal readout operation of the second embodiment. In Figure 10, six rows of pixels are shown as an example, illustrating the case where the readout scan is performed sequentially row by row.

[0081] In Figure 10, rows 6N and 6N+2 represent rows for obtaining the phase difference signals for left-right pupil division, and rows 6N+3 and 6N+5 represent rows for obtaining the phase difference signals for upper-lower pupil division. These are designated as the first pixel group. Rows 6N+1 and 6N+4 represent rows for obtaining the phase difference signals for upper-lower pupil division, and these are designated as the second pixel group.

[0082] In the second embodiment, the signals of rows 6N and 6N+2 of the first pixel group are read out in a second readout mode via column output line 105A, and the signals of rows 6N+3 and 6N+5 of the first pixel group are read out in a third readout mode via column output line 105A, which is referred to as scan 1. Similarly, the signals of the second pixel group are read out in a third readout mode via column output line 105B, which is referred to as scan 2.

[0083] Note that the left diagram in Figure 10 is the same as Figure 9, so its explanation is omitted.

[0084] In scan 1, four out of six rows are read out in order to capture live view images from the imaging device and to detect focus in the left-right and up-down directions. On the other hand, in scan 2, two out of six rows are read out in order to prioritize the frame rate for detecting focus in the up-down direction.

[0085] As described above, in the second embodiment, scan 1 is performed by dividing the pupils left and right and by dividing them up and down, and scan 2 is performed by dividing the pupils up and down, so that focus detection is possible in both scans.

[0086] Scan 1 reads out phase difference signals in both the left-right and up-down directions, thus suppressing the decrease in focus detection accuracy due to the image orientation of the subject. Furthermore, Scan 2 reads out the pixel signals of the rows that were downsampled in Scan 1, and since the number of signal readout rows is smaller than in Scan 1, phase difference signals can be acquired at high speed. Therefore, Scan 2 can suppress the decrease in focus detection accuracy due to the high speed of the moving subject.

[0087] Depending on the characteristics of the subject, the phase difference signals from scan 1 and scan 2 are used accordingly. For example, scan 1 has a higher resolution than scan 2, allowing for highly accurate focus detection of still objects. On the other hand, scan 2, with its advantage of high speed, is suitable for increasing the frequency (number of calculations) of focus detection and for detecting moving objects.

[0088] Scan 1 and Scan 2 may perform correlation calculations on the same subject in the same area within the field of view, or they may perform correlation calculations on different subjects in different areas.

[0089] Alternatively, scan 2 may also be read out using left and right pupil splitting. In this case, both scan 1 and scan 2 will read out phase difference signals in both the left-right and up-down directions, enabling faster focus detection in the left-right direction than scan 1.

[0090] The phase difference signals in the left-right or up-down direction read out in scan 1 and scan 2, respectively, may be combined into a single phase difference signal using the signal processing circuit 505 or the control circuit 506.

[0091] For example, in Figure 10, rows 6N+3 of scan 1 and row 6N+4 of scan 2 are accumulated at almost the same time, meaning they detect almost the same subject image. By interpolating the signals of the rows that have been downsampled in both scans, the resolution of focus detection can be improved. In this case, the difference in accumulation time between scan 1 and scan 2 is corrected using gain processing or similar methods.

[0092] In this way, by dividing the scan according to the direction of the pupil division for autofocus for each selected row, it is possible to suppress the shift in the subject's position and improve the accuracy of focus detection, even when the pupil division is vertical and the subject is moving.

[0093] (Third embodiment) Figure 11 is a conceptual diagram illustrating the relationship between the readout scan and the pupil division direction in the pixel signal readout operation of the third embodiment. In Figure 11, six rows of pixels are shown as an example, illustrating the case where the readout scan is performed sequentially row by row.

[0094] In Figure 11, rows 6N, 6N+2, 6N+3, and 6N+5 represent rows for obtaining only the imaging signal, and these constitute the first pixel group. Rows 6N+1 and 6N+4 represent rows for obtaining the phase difference signal for upper and lower pupil division, and these constitute the second pixel group.

[0095] In the third embodiment, the signals of the first pixel group are read out via the column output line 105A in a first readout mode, which is referred to as scan 1. Similarly, the signals of the second pixel group are read out via the column output line 105B in a third readout mode, which is referred to as scan 2.

[0096] Note that the left diagram in Figure 11 is the same as Figure 9, so its explanation is omitted.

[0097] In scan 1, four out of six rows are read out in order to capture live view images from the imaging device 100. On the other hand, in scan 2, two out of six rows are read out in order to prioritize the frame rate for vertical focus detection.

[0098] As described above, in the third embodiment, scan 1 is performed without pupil division, and scan 2 is performed with upper and lower pupil division, so focus detection is possible with scan 2 alone. Since the phase difference signal is not read out in scan 1, it is possible to improve the frame rate or reduce power consumption by implementing power saving during blanking.

[0099] In scan 2, the pixel signals of the rows that were downsampled in scan 1 are read out, and since the number of signal readout rows is smaller than in scan 1, the phase difference signal can be acquired at high speed. Therefore, in scan 2, it is possible to suppress the decrease in focus detection accuracy caused by the high speed of the moving subject.

[0100] In this way, by dividing the scan according to the direction of the pupil division for autofocus for each selected row, it is possible to suppress the shift in the subject's position and improve the accuracy of focus detection, even when the pupil division is vertical and the subject is moving.

[0101] (Modified version of the third embodiment) As described above, in the third embodiment, scan 2 is performed using vertical pupil division, but this can also be done using horizontal pupil division. Furthermore, the direction of pupil division can be changed depending on the shooting frame, for example, by applying vertical pupil division in the first frame of scan 2 and horizontal pupil division in the second frame of scan 2. In this way, focus detection becomes possible regardless of the image direction of the subject.

[0102] (Fourth embodiment) Figure 12 shows the pixel configuration in the fourth embodiment. In Figure 12, in the unit pixel array (4 pixels) of the Bayer array, there is a mixture of pixels 102 with pupil division in the left-right direction (row direction) and pixels 102 with pupil division in the up-down direction (column direction). In this example, pixels 102 labeled R, G1, and B are equipped with red, green, and blue color filters, respectively, and are divided in the left-right direction. Pixel 102 labeled G2 is equipped with a green color filter and is divided in the up-down direction.

[0103] As shown in Figure 12(a), the sub-pixels 201, 202, 203, and 204, which are divided into four parts within a single unit pixel 102, are read as either left-right or up-down pupil-dividing pixels for each pixel 102 by the control of the transfer pulses PTXA, PTXB, PTXC, and PTXD.

[0104] For example, the transfer switch 302B of sub-pixel 202 of pixel G2 may be controlled by the transfer pulse PTXC, and the transfer switch 302C of sub-pixel 203 may be controlled by the transfer pulse PTXB. In this case, the phase difference signals of pixels R, G1, B and pixel G2 are always read out in different directions.

[0105] Alternatively, two or more signal lines may be connected to the transfer switch 302 of sub-pixels 202 and 203, and different transfer pulses may be connected to each unit pixel R, G1, G2, and B. In this case, by individually controlling the transfer pulses of sub-pixels 202 and 203 for each unit pixel R, G1, G2, and B, phase difference signals in both the left-right and up-down directions can be read out in a single scan.

[0106] Furthermore, as shown in Figure 12(b), the subpixels may be formed as simple two divisions instead of four, and the left-right pupil division and the up-down pupil division may be mixed and arranged for each unit pixel 102. In this case, regardless of the unit pixels R, G1, G2, B, the transfer switch 302 of subpixel 201 is wired to be controlled by the transfer pulse PTXA, and the transfer switch 302 of subpixel 202 is wired to be controlled by the transfer pulse PTXC. Note that the transfer pulses PTXB and PTXD are not used.

[0107] This configuration allows for the reading of phase difference signals in both the left-right and up-down directions in a single scan for rows containing unit pixels G2.

[0108] Figure 13 is a conceptual diagram illustrating the relationship between the readout scan and the pupil division direction in the pixel signal readout operation of the fourth embodiment. In Figure 13, six rows of unit pixels are shown as an example, illustrating the case where the readout scan is performed sequentially row by row.

[0109] In Figure 13, rows 6N, 6N+2, 6N+3, and 6N+5 represent rows for obtaining phase difference signals, and these constitute the first pixel group. Rows 6N+1 and 6N+4 represent rows for obtaining only the imaging signal, and these constitute the second pixel group.

[0110] In the fourth embodiment, a signal is read out from the first pixel group via the column output line 105A in the second readout mode, which is referred to as scan 1. Similarly, a signal from the second pixel group is read out via the column output line 105B in the first readout mode, which is referred to as scan 2.

[0111] Note that the left diagram in Figure 13 is the same as Figure 9, so its explanation is omitted.

[0112] In scan 1, four out of six rows are read out using a decimation method for live view imaging of the imaging device and focus detection in the left-right and up-down directions. On the other hand, in scan 2, frame rate is prioritized, and two out of six rows are read out using a decimation method. Furthermore, according to the configuration shown in Figure 12, the left-right phase difference signals are read out in rows 6N and 6N+2. Also, in the columns containing unit pixels G2 in rows 6N+3 and 6N+5, the up-down phase difference signals are read out, and in the columns containing pixels B in rows 6N+3 and 6N+5, the left-right phase difference signals are read out.

[0113] As described above, in the fourth embodiment, the physical configuration of the unit pixel is already configured to output phase difference signals in both the left-right and up-down directions. Therefore, in scan 1, it is possible to suppress the decrease in focus detection accuracy due to the image direction of the subject. Scan 2 reads out the pixel signals of the rows that were downsampled in scan 1, and since it reads out fewer signal rows than scan 1 and does not read out phase difference signals, it is possible to acquire the imaging signal at high speed. In scan 1, the phase difference signal also serves as the imaging signal, so the imaging signal of scan 2 does not necessarily have to be used for the display image. For example, it may be used as a photometric signal for dimming or flicker detection.

[0114] In this way, by dividing the scan according to the direction of the pupil division for autofocus for each selected row, it becomes possible to improve the accuracy of focus detection regardless of the image direction of the subject.

[0115] The operations described in the above embodiment can be used depending on the characteristics of the subject and the various modes of the imaging device.

[0116] (Other embodiments) Furthermore, the present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by a process in which one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0117] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of Symbols]

[0118] 101: Pixel section, 102: Pixel, 103: Signal line, 104: Vertical scanning circuit, 105: Column output line, 106: Column circuit, 107: Comparator, 108: Counter, 109: Column memory, 110: Timing generator, 111: D / A converter, 112: Horizontal scanning circuit, 113: Horizontal signal line, 301: Photodiode, 302: Transfer switch, 303: Floating diffusion, 304: Reset switch, 305: Pixel amplifier, 306: Selection switch

Claims

1. A pixel array having multiple pixel columns, each of which pixels are arranged in a matrix, and each column of pixels has multiple column output lines, including a first column output line and a second column output line. The system includes a readout circuit that reads signals from the pixels via the plurality of column output lines, The imaging apparatus is characterized in that the readout circuit performs a first readout scan to read a signal from a first group of pixels in the pixel array via the first column output line, and a second readout scan to read a signal from a second group of pixels different from the first group of pixels in the pixel array via the second column output line, thereby reading a horizontal phase difference signal by the first readout scan and reading a vertical phase difference signal by the second readout scan.

2. The imaging apparatus according to claim 1, characterized in that the readout circuit reads both the horizontal phase difference signal and the vertical phase difference signal by the first readout scan, and reads the vertical phase difference signal by the second readout scan.

3. The imaging apparatus according to claim 1, characterized in that the readout circuit reads out both the horizontal phase difference signal and the vertical phase difference signal by the first readout scan, and reads out both the horizontal phase difference signal and the vertical phase difference signal by the second readout scan.

4. The imaging apparatus according to any one of claims 1 to 3, characterized in that the readout circuit further reads out the imaging signal by the first readout scan.

5. The imaging apparatus according to any one of claims 1 to 4, characterized in that the readout circuit further reads out the imaging signal by the second readout scan.

6. The imaging apparatus according to any one of claims 1 to 5, further comprising a focus adjustment means for adjusting the focus by combining the horizontal phase difference signal or vertical phase difference signal read out in the first readout scan with a phase difference signal having the same pupil division direction as at least one of the horizontal phase difference signal or vertical phase difference signal read out in the second readout scan.

7. A pixel array having multiple pixel columns, each of which pixels are arranged in a matrix, and each column of pixels has multiple column output lines, including a first column output line and a second column output line. The system includes a readout circuit that reads signals from the pixels via the plurality of column output lines, The readout circuit performs a first readout scan to read a signal from a first group of pixels in the pixel array via the first column output line, and a second readout scan to read a signal from a second group of pixels different from the first group of pixels in the pixel array via the second column output line, the first readout scan reads an imaging signal which is the sum of the signals of the four sub-pixels that each pixel has, and the second readout scan reads a phase difference signal which is pupil-splitting in the left-right or up-down direction by the four sub-pixels. An imaging apparatus characterized in that, within a single vertical synchronization period, a portion of the exposure period of the first pixel group and a portion of the exposure period of the second pixel group overlap, while other portions do not overlap, and the time required for the second readout scan is shorter than the time required for the first readout scan.

8. The imaging apparatus according to claim 7, characterized in that the readout circuit reads out both the imaging signal and the phase difference signal by the first readout scan.

9. The imaging apparatus according to claim 7 or 8, characterized in that the readout circuit reads out the vertical phase difference signal by the second readout scan.

10. A pixel array having multiple pixel columns, each of which pixels are arranged in a matrix, and each column of pixels has multiple column output lines, including a first column output line and a second column output line. The system includes a readout circuit that reads signals from the pixels via the plurality of column output lines, The readout circuit performs a first readout scan to read a signal from a first group of pixels in the pixel array via the first column output line, and a second readout scan to read a signal from a second group of pixels different from the first group of pixels in the pixel array via the second column output line, reading a phase difference signal with the first readout scan and reading a signal for flicker detection with the second readout scan. An imaging apparatus characterized in that, within a single vertical synchronization period, a portion of the exposure period of the first pixel group and a portion of the exposure period of the second pixel group overlap, while other portions do not overlap, and the time required for the second readout scan is shorter than the time required for the first readout scan.

11. The imaging apparatus according to claim 10, characterized in that the readout circuit reads out the horizontal phase difference signal by the first readout scan.

12. The imaging apparatus according to claim 10 or 11, characterized in that the readout circuit reads out the vertical phase difference signal by the first readout scan.

13. The imaging apparatus according to any one of claims 10 to 12, characterized in that the readout circuit reads out the imaging signal together with the phase difference signal by the first readout scan.

14. A method for controlling an imaging device having a pixel array in which pixels are arranged in a matrix, and each row of pixels has a plurality of column output lines, including a first column output line and a second column output line, wherein The reading process includes reading the signal from the pixel via the plurality of column output lines, A control method for an imaging device, characterized in that the readout step involves performing a first readout scan to read a signal from a first group of pixels in the pixel array via the first column output line, and a second readout scan to read a signal from a second group of pixels different from the first group of pixels in the pixel array via the second column output line, thereby reading a horizontal phase difference signal by the first readout scan and reading a vertical phase difference signal by the second readout scan.

15. A method for controlling an imaging device having a pixel array in which pixels are arranged in a matrix, and each row of pixels has a plurality of column output lines, including a first column output line and a second column output line, wherein The reading process includes reading the signal from the pixel via the plurality of column output lines, In the readout step, a first readout scan is performed to read a signal from a first group of pixels in the pixel array via the first column output line, and a second readout scan is performed to read a signal from a second group of pixels different from the first group of pixels in the pixel array via the second column output line, the first readout scan reads an imaging signal which is the sum of the signals of the four sub-pixels that each pixel has, and the second readout scan reads a phase difference signal which is pupil-splitting in the left-right or up-down direction by the four sub-pixels. A control method for an imaging device, characterized in that, within a single vertical synchronization period, a portion of the exposure period of the first pixel group and a portion of the exposure period of the second pixel group overlap, while other portions do not overlap, and the time required for the second readout scan is shorter than the time required for the first readout scan.

16. A method for controlling an imaging device having a pixel array in which pixels are arranged in a matrix, and each row of pixels has a plurality of column output lines, including a first column output line and a second column output line, wherein The reading process includes reading the signal from the pixel via the plurality of column output lines, In the readout step, a first readout scan is performed to read a signal from a first group of pixels in the pixel array via the first column output line, and a second readout scan is performed to read a signal from a second group of pixels different from the first group of pixels in the pixel array via the second column output line, the phase difference signal is read out by the first readout scan, and the signal for flicker detection is read out by the second readout scan. A control method for an imaging device, characterized in that, within a single vertical synchronization period, a portion of the exposure period of the first pixel group and a portion of the exposure period of the second pixel group overlap, while other portions do not overlap, and the time required for the second readout scan is shorter than the time required for the first readout scan.

Images