JP6762849B2 - Image sensor, its control method, program and recording medium - Google Patents

Description

The present invention relates to an image pickup device having a focus detection function.

Recent still cameras and video cameras generally have an autofocus detection (AF) function. In order to realize rapid AF, it is necessary to read out the focus detection signal at a high frame rate. However, when the focus detection signal is read out at a high frame rate, the amount of data transferred to the signal processing unit located behind the solid-state image sensor is increased. Therefore, a solid-state image sensor has been proposed in which an AF evaluation value detection unit for detecting an AF evaluation value is provided inside the solid-state image sensor, and the AF evaluation value detected by the AF evaluation value detection unit is output to the outside (patented). Reference 1).

Japanese Unexamined Patent Publication No. 2015-12489

By the way, as the AF method, AF by the phase difference detection method, that is, phase difference AF, and AF by the contrast detection method, that is, contrast AF are combined to achieve both high speed and high accuracy of focusing operation. Hybrid AF is known. In hybrid AF, it is common to roughly adjust the focusing operation using phase-difference AF and then fine-tune the focusing operation using contrast AF. However, in order to calculate the evaluation values for performing phase-difference AF and contrast AF, it is necessary to wait for the completion of reading the imaging signal for generating the captured image, which delays the start of hybrid AF. There was a challenge.

Patent Document 1 does not consider such a hybrid AF technique. Therefore, the applicant examined a method for speeding up focus detection by combining a phase difference detection method and a contrast detection method.

The imaging element according to the present invention is an imaging element in which a first chip and a second chip are laminated on each other, and is composed of a plurality of imaging pixels that receive light focused by the imaging optical system and an imaging optical system. A pixel array in which a plurality of phase difference detection pixels that receive a pair of light beams that have passed through different pupil region regions are arranged in a matrix, and a circuit that reads an image pickup signal from the image pickup pixel and reads out a phase difference signal from the phase difference detection pixel. The contrast evaluation value calculation unit that calculates the contrast evaluation value based on the imaging signal, and the phase difference evaluation value calculation unit that calculates the phase difference evaluation value based on the phase difference signal before the reading of the imaging signal is completed. When, and a determining unit in accordance with whether or not to calculate a contrast evaluation value to the phase difference evaluation value, the pixel array is disposed in the first chip, the contrast evaluation value calculating unit and the phase difference evaluation value calculation unit is characterized that you have been disposed on the second chip.

According to the present invention, it is possible to obtain an image sensor capable of performing focus detection by combining a phase difference detection method and a contrast detection method at a higher speed and a control method thereof.

It is a block diagram which shows the structure of the image pickup apparatus which concerns on 1st Embodiment. It is the schematic which shows the structure of the image sensor which concerns on 1st Embodiment together with the perspective view. It is the schematic which shows the composition of the pixel in the image sensor which concerns on 1st Embodiment. It is a schematic diagram which shows the structure of the image pickup pixel in the image pickup device which concerns on 1st Embodiment. It is a schematic diagram which shows the structure of the phase difference detection pixel in the image sensor which concerns on 1st Embodiment. It is a schematic diagram which shows the focus detection area on the pixel array in the image sensor which concerns on 1st Embodiment. It is the schematic which shows the example of the pair of phase difference signals for focus detection in the image sensor which concerns on 1st Embodiment. It is a figure which shows the relationship between the shift amount and the correlation amount of the phase difference signal in the image pickup device which concerns on 1st Embodiment. It is a figure which shows the relationship between the shift amount of a phase difference signal and the correlation change amount in the image pickup device which concerns on 1st Embodiment. It is a schematic diagram which shows the arrangement of the sub-pixel in the image sensor which concerns on 1st Embodiment. It is a timing chart which shows the control method of the image sensor which concerns on 1st Embodiment. It is a flowchart which shows the control method of the image sensor which concerns on 1st Embodiment. It is the schematic which shows the structure of the image sensor in the image sensor which concerns on 2nd Embodiment. It is a timing chart which shows the control method of the image sensor which concerns on 2nd Embodiment. It is a flowchart which shows the control method of the image sensor which concerns on 2nd Embodiment. It is a timing chart which shows the example of the hybrid AF in the conventional image pickup apparatus.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments, and can be appropriately modified without departing from the gist thereof. Further, in the drawings described below, those having the same function may be designated by the same reference numerals, and the description thereof may be omitted or simplified.

FIG. 16 is a timing chart showing an example of hybrid AF in a conventional imaging device. In the hybrid AF, as described above, the focus is first detected by using the phase difference detection method, and then the focus is detected by using the contrast detection method. In the image pickup device, a plurality of phase difference detection pixels that receive a pair of light fluxes that have passed through different pupil region regions of the image pickup optical system are arranged in a part region on the pixel array. Hereinafter, the conventional hybrid AF will be described with reference to FIG.

For example, when the still image continuous shooting mode is started by a user operation, a still image continuous shooting control signal indicating that the still image continuous shooting mode is set is set to HIGH. As a result, at the same time that the mechanical shutter is opened, the accumulated charge of the pixel is reset and the exposure on the pixel is started (time T0). After that, when a predetermined exposure period elapses, the mechanical shutter is closed, the light from the subject is blocked, and the exposure on the pixel is completed (time TF0).

Next, reading from a normal imaging pixel is started (time TF0). When the imaging signals are read from all the imaging pixels, the reading from the phase difference detection pixels is subsequently started. When the phase difference signal is read out from all the phase difference detection pixels (time TF1), the image sensor calculates the phase difference evaluation value based on the phase difference signal and also calculates the contrast evaluation value based on the image pickup signal (time TF1). Periods TF1 to TF2).

Next, the image sensor outputs the calculated phase difference evaluation value and contrast evaluation value to the control unit outside the image sensor in the form of being added to the image pickup signal (periods TF2 to TF3). The control unit drives the focus lens based on the phase difference evaluation value and the contrast evaluation value to perform the focusing operation (period TF3 to TF4). When the focusing operation is completed, the exposure operation on the pixels is started for the next still image shooting in the same manner as at the time T0 (time TF4).

As described above, in the conventional hybrid AF, the calculation of the phase difference evaluation value and the contrast evaluation value is started after waiting for the completion of reading the imaging signal for generating the captured image. Therefore, by the time the hybrid AF is completed. There was a problem that it took time. As a result, for example, the continuous shooting speed in continuous shooting of still images is reduced. In the embodiment described later, a method for increasing the speed of the hybrid AF will be described.

(First Embodiment)
The image pickup apparatus according to the first embodiment will be described with reference to FIGS. 1 to 12. FIG. 1 is a block diagram showing a configuration of an imaging device according to the first embodiment. The image pickup apparatus shown in FIG. 1 includes an image pickup optical system 101, an image sensor 102, a drive unit 103, a signal processing unit 104, a compression / expansion unit 105, a control unit 106, a light emitting unit 107, an operation unit 108, an image display unit 109, and an image recording unit. The unit 110 is provided. The imaging device of the present embodiment is applied to, for example, a still camera, a video camera, or the like.

The image pickup optical system 101 includes an optical lens barrel, a lens, and an optical mechanism unit 1011 for concentrating light from a subject on the image pickup element 102. The optical mechanism unit 1011 is driven by the drive unit 103 to adjust the zoom, shutter, aperture value, and focus of the imaging optical system 101. The image sensor 102 has pixels arranged in a matrix and an AD converter or the like that reads signals output from the pixels, and performs operations such as exposure, signal reading, and reset of each pixel. As the image sensor 102, for example, an XY readout type CMOS image sensor or the like is used. The drive unit 103 is controlled by the control unit 106 to drive the optical mechanism unit 1011 and the image sensor 102.

The AF evaluation value calculation unit 1021 in the image sensor 102 is controlled by the control unit 106, calculates the phase difference evaluation value and the contrast evaluation value based on the image pickup signal and the phase difference signal read from the pixels, and outputs the phase difference evaluation value and the contrast evaluation value to the control unit 106. To do. The control unit 106 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The control unit 106 comprehensively controls the image pickup apparatus by loading the program stored in the ROM or the like into the RAM and executing the program in the CPU.

The signal processing unit 104 is controlled by the control unit 106, and is corrected by performing signal processing such as white balance adjustment processing, color correction processing, and AE (Auto Exposure) processing on the image pickup signal output from the image pickup element 102. The signal is output to the compression / expansion unit 105. The compression / decompression unit 105 is controlled by the control unit 106, performs coding processing on the corrected imaging signal, and outputs the coded signal to the control unit 106. As a method for encoding the imaging signal by the compression / decompression unit 105, for example, a JPEG (Joint Photographic Coding Experts Group) method is used when a still image is generated. Further, when generating a moving image, an MPEG (Moving Picture Experts Group) method or the like is used. The compression / decompression unit 105 may have a decoding function in addition to the coding function.

The light emitting unit 107 irradiates the subject with light, for example, when the signal processing unit 104 determines that the brightness of the subject is low by the AE process. As the light emitting unit 107, for example, a strobe device using a xenon tube, an LED light emitting device, or the like can be used. The operation unit 108 has various operation keys such as a shutter release button, a lever, a dial, and the like, and outputs a signal corresponding to the operation by the user to the control unit 106. The image display unit 109 has a display device such as an LCD (Liquid Crystal Display), an interface circuit for driving the display device, and the like, and displays image data output from the control unit 106 on the display device. The image recording unit 110 is configured by using a portable semiconductor memory, an optical disk, an HDD (Hard Disk Drive), a magnetic tape, or the like, and stores encoded image data output from the control unit 106.

Here, the flow of signals and data in the image pickup apparatus shown in FIG. 1 will be briefly described. The image pickup signal read from the pixels of the image pickup device 102 is subjected to CDS (Correlated Double Sampling) processing, AGC (Automatic Gain Control) processing, and the like, and then digitized by the AD conversion unit.

The digitized image pickup signal is output to the signal processing unit 104 and the AF evaluation value calculation unit 1021 in the image pickup device 102. The AF evaluation value calculation unit 1021 calculates the contrast evaluation value based on the contrast information of the imaging signal and outputs it to the control unit 106. The signal processing unit 104 performs image quality correction processing on the image pickup signal, and outputs the corrected signal to the control unit 106. The control unit 106 causes the image display unit 109 to display the image pickup signal as a live view image. As a result, the user can adjust the angle of view by looking at the displayed live view image.

Next, when the shutter release button of the operation unit 108 is pressed while the live view image is displayed on the image display unit 109, the image sensor 102 outputs the image pickup signal to the signal processing unit 104. The signal processing unit 104 performs image quality correction processing on the image pickup signal, and outputs the corrected signal to the compression / decompression unit 105. The compression / decompression unit 105 encodes the corrected imaging signal and outputs the encoded signal to the control unit 106. The control unit 106 records the encoded imaging signal in the image recording unit 110 as a still image or moving image file.

Next, when the play button of the operation unit 108 is pressed while the still image or moving image file recorded in the image recording unit 110 is selected, the control unit 106 images the selected still image or moving image file. It is read from the recording unit 110 and output to the compression / decompression unit 105. The compression / decompression unit 105 decodes the read image data and outputs it to the control unit 106. The control unit 106 causes the image display unit 109 to display the decoded image data. As a result, the user can reproduce and view the recorded still image or moving image.

On the other hand, the AF evaluation value calculation unit 1021 performs a correlation calculation on a pair of phase difference signals output from the phase difference detection pixels to obtain a relative image shift amount. Then, the defocus amount of the imaging optical system 101 is calculated (detected) from the image shift amount. The control unit 106 calculates the drive amount for moving the focus lens to a position near the in-focus position based on the defocus amount. Then, the drive unit 103 is controlled based on the drive amount to drive the focus lens in the optical mechanism unit 1011 to perform the focusing operation.

Further, the control unit 106 acquires the contrast evaluation value from the AF evaluation value calculation unit 1021 at a predetermined cycle while controlling the optical mechanism unit 1011 to move the focus lens. Then, the focus lens is driven in a direction in which the contrast evaluation value calculated based on the imaging signal of the still image captured this time is larger than the contrast evaluation value calculated based on the imaging signal of the still image captured last time. To perform focusing operation.

FIG. 2 is a schematic view showing the configuration of the image sensor 102 according to the first embodiment together with a perspective view. FIG. 2A shows a perspective view of the image sensor 102, and FIG. 2B shows a schematic view of the configuration of the image sensor 102. As shown in FIG. 2A, the image pickup device 102 of the present embodiment includes a first chip 20 and a second chip 21 laminated on the first chip 20. ..

A plurality of pixels 201 are arranged in a matrix on the first chip 20. A transfer signal line 203, a reset signal line 204, and a row selection signal line 205 are connected to each row of the plurality of pixels 201, and a column signal line 202 is connected to each column.

On the other hand, the AD conversion unit 211, the row scanning circuit 212, the column scanning circuit 213, the timing control circuit 214, the signal switching unit 216, and the AF evaluation value calculation unit 1021 are arranged on the second chip 21. In this way, by arranging the pixel 201 and its peripheral circuit separately on the first chip 20 and the second chip 21, the wiring of the peripheral circuit is made thinner and denser, and the speed of the image sensor 102 is increased. , Can be miniaturized and highly functional.

The AD conversion unit 211 AD-converts the signal output to the column signal line 202 and outputs it to the horizontal signal line 215. The row scanning circuit 212 scans each row of the image sensor 102, and the column scanning circuit 213 scans each column of the image sensor 102. The timing control circuit 214 is controlled by the control unit 106 to control the scanning timings of the row scanning circuit 212 and the column scanning circuit 213.

The signal switching unit 216 distributes and supplies the digital signal output to the horizontal signal line 215 to the phase difference evaluation value calculation unit 217, the contrast evaluation value calculation unit 218, and the signal processing unit 104, respectively. The AF evaluation value calculation unit 1021 includes a phase difference evaluation value calculation unit 217 and a contrast evaluation value calculation unit 218, and detects (calculates) the AF evaluation value used for focus detection. The phase difference evaluation value calculation unit 217 and the contrast evaluation value calculation unit 218 will be described in detail later.

FIG. 3 is a schematic view showing the configuration of pixels 201 in the image sensor 102 according to the first embodiment. Pixel 201 includes a photoelectric conversion unit PD, a transfer transistor M1, a reset transistor M2, an amplification transistor M3, and a selection transistor M4. As these transistors, for example, an n-channel MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) can be used.

A transfer signal line 203, a reset signal line 204, and a line selection signal line 205 are connected to each gate terminal of the transfer transistor M1, the reset transistor M2, and the selection transistor M4, respectively. A control signal is output from the row scanning circuit 212 to these signal lines, and pixels 201 in the same row are simultaneously driven. With such a configuration, it is possible to perform a row-sequential operation type rolling shutter operation and an all-row simultaneous drive type global shutter operation. A column signal line 202 is connected to the source terminal of the selection transistor M4.

The photoelectric conversion unit PD is a photodiode that stores the electric charge generated by the photoelectric conversion. The p-type side of the photodiode is grounded, and the n-type side is connected to the source terminal of the transfer transistor M1. When the transfer transistor M1 is turned on, the electric charge accumulated in the photoelectric conversion unit PD is transferred to the floating diffusion FD. Here, the floating diffusion FD refers to a stray capacitance region formed at the connection points of the drain terminal of the transfer transistor M1, the gate terminal of the amplification transistor M3, and the source terminal of the reset transistor M2.

The amplification transistor M3 outputs a signal corresponding to the amount of electric charge transferred to the floating diffusion FD. A power supply voltage Vdd is supplied to the drain terminal of the amplification transistor M3. The selection transistor M4 selects a pixel for reading a signal. The drain terminal of the selection transistor M4 is connected to the source terminal of the amplification transistor M3, and the source terminal of the selection transistor M4 is connected to the column signal line 202. When the selection transistor M4 is turned on, a signal corresponding to the amount of charge transferred to the floating diffusion FD is output to the column signal line 202. The reset transistor M2 resets the electric charge transferred to the floating diffusion FD. The power supply voltage Vdd is supplied to the drain terminal of the reset transistor M2, and the source terminal of the reset transistor M2 is connected to the floating diffusion FD.

FIG. 4 is a schematic view showing the structure of the image pickup pixel in the image pickup device 102 according to the first embodiment. Here, the imaging pixel refers to a normal pixel 201 that does not include a sub-pixel for focus detection. FIG. 4A shows a plan view of the imaging pixel, and FIG. 4B shows a cross-sectional view taken along the line AA of FIG. 4A. For example, in the image sensor 102 that employs the Bayer arrangement, as shown in FIG. 4A, pixels having G (green) spectral sensitivity are arranged at two diagonal positions in the pixels of 2 rows × 2 columns, and other pixels have Pixels having spectral sensitivities of R (red) and B (blue) are arranged at two locations, respectively.

The imaging pixel shown in FIG. 4B has a microlens ML, a color filter CF, a wiring layer CL, and a photoelectric conversion unit PD. Here, given the subscript a color filter CF, which indicates the color of the light passing, for example, a color filter CF _R passes the red light (Red), color filter CF _G is green light (Green) Let it pass. Similarly, the color filter CF _B (not shown) allows blue light (Brue) to pass through. The photoelectric conversion unit PD corresponds to the photoelectric conversion unit PD of the CMOS sensor shown in FIG. The wiring layer CL is a signal line that transmits various signals in the CMOS sensor.

The microlens ML of the imaging pixel and the photoelectric conversion unit PD are configured to capture the luminous flux that has passed through the photographing optical system TL as effectively as possible. In other words, the exit pupil EP of the photographing optical system TL and the photoelectric conversion unit PD are arranged in a conjugated relationship by the microlens ML. As a result, the exit pupil EP corresponding to the photoelectric conversion unit PD has a large diameter, the effective area of the photoelectric conversion unit PD becomes large, and the luminous flux from the subject can be efficiently captured to improve the S / N. Although the structure of the R pixel is shown in FIG. 4B, the G pixel and the B pixel also have the same structure.

FIG. 5 is a schematic view showing the structure of the phase difference detection pixel in the image sensor 102 according to the first embodiment. Here, the phase difference detection pixel refers to a pixel 201 including a sub-pixel for focus detection. FIG. 5A shows a plan view of the phase difference detection pixel, and FIG. 5B shows a cross-sectional view taken along the line BB of FIG. 5A.

Of the RGB signals output by the RGB pixels, the G signal is the main component of the luminance information. Since human image recognition characteristics are sensitive to luminance information, image quality deterioration is likely to be observed when the G signal is lost. On the other hand, the R signal or the B signal is a signal for acquiring the color information, but since human beings are insensitive to the color information, the R signal or the B signal is hard to notice the deterioration of the image quality even if some loss occurs. .. Therefore, in the present embodiment, as shown in FIG. 5A, two G pixels out of the four pixels of 2 rows × 2 columns are left as normal imaging pixels, and a predetermined ratio is set at the positions of the R pixel and the B pixel. Sub-pixels SHA and SHB are arranged at.

In the present embodiment, the sub-pixel SHA and the sub-pixel SHB form a phase difference detection pixel. The microlens ML and the photoelectric conversion unit PD have substantially the same structure as the imaging pixels shown in FIG. 4 (b). In the present embodiment, since the phase difference signal output from the sub-pixel is not used as the imaging signal for generating the captured image, as shown in FIG. 5B, it is transparent instead of the color separation color filter. the color filter CF _W film (white film) is disposed. It is also possible to use the phase difference detection pixel as an imaging pixel. In this case, the sum of the pair of phase difference signals output from the phase difference detection pixels is used as the imaging signal.

The phase difference detection pixel shown in FIG. 5B performs pupil division in the x direction. The opening OP _HA of the wiring layer CL of the sub-pixel SHA is biased to the right side (-x direction), and the photoelectric conversion unit PD of the sub-pixel SHA is the exit pupil region (third) on the left side (+ x direction) of the photographing optical system TL. 1 pupil region) Receives the light flux that has passed through EP _HA . On the other hand, the opening OP _HB of the wiring layer CL of the sub-pixel SHB is biased to the left side (+ x direction), and the photoelectric conversion unit PD of the sub-pixel SHB is the exit pupil region on the right side (-x direction) of the photographing optical system TL. (Second pupil region) _Receives the light flux that has passed through the EP _HB .

The subject image acquired by the plurality of sub-pixel SHAs (first pixel group) regularly arranged in the x direction is defined as the A image (first image). Further, a subject image acquired by a plurality of sub-pixels SHB (second pixel group) regularly arranged in the x direction is referred to as a B image (second image). By detecting the relative positional deviation (phase difference) between the A image and the B image, the defocus amount of the photographing optical system TL with respect to the subject can be calculated.

Here, the operation of the image sensor 102 will be described again with reference to FIG. 2 (b). The imaging signal and phase detection signal output to the column signal line 202 are digitized by the AD conversion unit 211. The digitized phase detection signal and imaging signal are output to the signal switching unit 216 via the horizontal signal line 215. The signal switching unit 216 switches the output destination of the signal read out via the column signal line 202. The signal switching unit 216 outputs the phase difference signal to the phase difference evaluation value calculation unit 217, and outputs the imaging signal to the contrast evaluation value calculation unit 218 and the signal processing unit 104.

The phase difference evaluation value calculation unit 217 performs a correlation calculation based on the phase difference signal and calculates the phase difference evaluation value. On the other hand, the contrast evaluation value calculation unit 218 performs a contrast calculation based on the image pickup signal and calculates the contrast evaluation value. The calculated phase difference evaluation value and contrast evaluation value are output to the control unit 106 via the signal processing unit 104 in the form of being added to the image pickup signal at the timing when the reading of the image pickup signal from the image pickup pixel is completed.

Next, focus detection by the phase difference method will be described with reference to FIGS. 6 to 9. FIG. 6 is a schematic view showing a focus detection region 602 on the pixel array 601 of the image sensor 102 according to the first embodiment. The focus detection region 602 shown in FIG. 6 indicates a pixel region in which focus detection can be performed by a phase difference method. Further, the shift regions 603 on both sides of the focus detection region 602 are regions necessary for the correlation calculation. That is, for the focus detection by the phase difference method, the pixel area 604 that combines the focus detection area 602 and the shift area 603 is required. P, q, s, and t shown in FIG. 6 represent the coordinates in the horizontal direction (x-axis direction), of which p and q are the x-coordinates of the start point and the end point of the pixel area 604, respectively, and s and t are the coordinates. It represents the x-coordinates of the start and end points of the focus detection area 602.

FIG. 7 is a schematic view showing an example of a pair of phase difference signals 701 and 702 for focus detection in the image sensor 102 according to the first embodiment. In FIG. 7A, one of the pair of phase difference signals after filtering is shown by a solid line, and the other phase difference signal 702 is shown by a broken line. Strictly speaking, the phase difference signals 701 and 702 shown in FIG. 7A show a pair of subject images along the x direction obtained from a plurality of sub-pixels SHA and SHB arranged in the x direction. However, in the following description, such a pair of subject images will be referred to as phase difference signals 701 and 702.

When calculating the correlation amount of the pair of phase difference signals 701 and 702, the phase difference signals 701 and 702 are one pixel each in opposite directions as shown in FIGS. 7 (b) and 7 (c). Shift. FIG. 7B shows the results of shifting the phase difference signals 701 and 702 shown in FIG. 7A in the directions of the arrows shown in FIG. 7B, respectively. On the other hand, FIG. 7 (c) shows the results of shifting the phase difference signals 701 and 702 shown in FIG. 7 (a) in the directions of the arrows shown in FIG. 7 (c), which are opposite to those of FIG. 7 (b). Is shown.

The phase difference evaluation value calculation unit 217 shifts the pair of phase difference signals 701 and 702 one pixel at a time as shown in FIGS. 7 (b) and 7 (c), and positions the pair of phase difference signals 701 and 702 in the focus detection region 602. The sum of the absolute values of the differences of the phase difference signals 702 is calculated. The correlation amount COR is calculated by the following equation (1) using the shift amount i, the minimum shift amount ps, the maximum shift amount qt, the start coordinate s of the focus detection area 602, and the end coordinate t of the focus detection area 602. Given.

FIG. 8 is a diagram showing the relationship between the shift amount i of the phase difference signal and the correlation amount COR in the image sensor 102 according to the first embodiment. The horizontal axis represents the shift amount i, and the vertical axis represents the correlation amount COR. The correlation amount COR shown in FIG. 8A changes according to the shift amount i, and the change amount becomes zero at the extreme values 802 and 803. FIG. 8B shows an enlarged view of the vicinity of the extreme value 802, which is the smaller of the extreme values 802 and 803. For the correlation change amount ΔCOR per unit shift amount i, the shift amount i, the minimum shift amount p−s, the maximum shift amount q−t, the start coordinate s of the focus detection area 602, and the end coordinate t of the focus detection region 602 are used. It is given by the following equation (2).
ΔCOR [i] = COR [i-1] -COR [i + 1]
{(P-s + 1) <(q-t-1)} (2)

FIG. 9 is a diagram showing the relationship between the shift amount i of the phase difference signal and the correlation change amount ΔCOR in the image sensor 102 according to the first embodiment. The horizontal axis represents the shift amount i, and the vertical axis represents the correlation change amount ΔCOR per unit shift amount i. The correlation change amount ΔCOR shown in FIG. 9A changes according to the shift amount i, and the value changes from minus to plus at the extreme values 802 and 803. The point where the correlation change amount ΔCOR becomes zero is called zero cross, and the degree of coincidence between the pair of phase difference signals 701 and 702 is the highest. The shift amount i that gives zero cross is the image shift amount.

The phase difference evaluation value calculation unit 217 outputs the shift amount i that gives zero cross to the control unit 106 as a phase difference evaluation value for calculating the drive amount of the focus lens. FIG. 9B shows an enlarged view of the vicinity of the extremum 802 that gives zero cross. The shift amount i = α + β that gives a zero cross is divided into an integer part β (= k-1) and a decimal part α. The fractional part α of the amount of image shift is calculated by the following equation (3) from the similarity relationship between the triangle ABC and the triangle ADE shown in FIG. 9 (b).
AB: AD = BC: DE
ΔCOR [k-1]: ΔCOR [k-1] −ΔCOR [k] = α: k− (k-1)
α = ΔCOR [k-1] / (ΔCOR [k-1] −ΔCOR [k]) (3)

Further, the integer part β of the image shift amount is calculated by the following equation (4).
β = k-1 (4)

As shown in FIG. 9A, when there are a plurality of zero crosses of the correlation change amount ΔCOR, the shift amount i of the zero cross having the largest change rate of the correlation change amount ΔCOR (hereinafter referred to as “steepness”) is the phase difference. It is output to the control unit 106 as an evaluation value. The steepness is an index showing the ease of performing focus detection, and the larger the steepness, the more accurately the focus can be detected. The steepness maxder is given by the following equation (5).
maxder = | ΔCOR [k-1] | + | ΔCOR [k] | (5)

Next, a method of calculating the reliability of the phase difference evaluation value will be described. The evaluation value reliability is defined by the degree of coincidence fnclvl of the pair of phase difference signals 701 and 702. The degree of coincidence fnclvl is an index showing the accuracy of the amount of image shift, and the larger the value, the better the accuracy of focus detection. The degree of agreement fnclvl is calculated by the following equation (6) as the reciprocal of the magnitude of the extremum 802 shown in FIG. 8 (b).
(A): When | ΔCOR [k-1] | × 2 ≦ maxder
fnclvl = 4 / (COR [k-1] + ΔCOR [k-1])
(B): When | ΔCOR [k-1] | × 2> maxder,
fnclvl = 4 / (COR [k] -ΔCOR [k]) (6)

Next, the hybrid AF in the imaging device of the present embodiment will be described. FIG. 10 is a schematic view showing the arrangement of sub-pixels in the image sensor 102 according to the first embodiment. In the image pickup device of the present embodiment, the sub-pixels SHA and SHB that output the phase difference signals 701 and 702 and the normal image pickup pixels are arranged in a matrix on the image pickup element 102, for example, as shown in FIG. .. In FIG. 10, the same pixel arrangement is repeated in a cycle of 8 rows, and within each cycle of the pixel arrangement, sub-pixels SHA, SHB, and imaging pixels are arranged in the 1st to 2nd rows, and the 3rd to 8th rows are arranged. Imaging pixels are arranged in a row.

The row scanning circuit 212 of the present embodiment first scans the phase difference detection row in which the sub-pixels SHA and SHB are arranged, and then scans the imaging row in which the sub-pixels SHA and SHB are not arranged. Specifically, when shooting is started by operating the operation unit 108 or the like, first, the first line, the second line, the ninth line, the tenth line, ..., Which are the phase difference detection lines, are sequentially scanned. After that, the 3rd to 8th rows, the 11th to 16th rows, ..., Which are the imaging rows, are sequentially scanned. In this way, by starting the row scan from the phase difference detection row in which the sub-pixels SHA and SHB are arranged, the sub-pixels SHA and SHB do not have to wait for the completion of reading the imaging signal for generating the captured image. The output phase difference signals 701 and 702 for focus detection can be acquired.

The pixel arrangement in the image sensor 102 is not necessarily limited to the 8-row period as shown in FIG. 10, and may not be periodic. In the image sensor 102 of the present embodiment, at least one row may be present for each of the phase difference detection row in which the sub-pixels SHA and SHB are arranged and the imaging row in which the sub-pixels SHA and SHB are not arranged. ..

FIG. 11 is a timing chart showing a control method of the image pickup device 102 according to the first embodiment. As described above, in the hybrid AF of the present embodiment, first, the phase difference detection row in which the sub-pixels SHA and SHB are arranged is scanned, and then the imaging row in which only the normal imaging pixels are arranged is scanned.

For example, when the operation unit 108 is operated by the user to start the still image continuous shooting mode, the control unit 106 sets the still image continuous shooting control signal indicating that the still image continuous shooting mode is HIGH (time T0). As a result, at the same time that the mechanical shutter of the optical mechanism unit 1011 is opened, the accumulated charge of the pixel 201 is reset and the exposure on the pixel 201 is started. After that, when the exposure period set to satisfy a predetermined exposure condition elapses, the mechanical shutter of the optical mechanism unit 1011 is closed, the light from the subject is blocked, and the exposure at the pixel 201 ends (time TF0).

First, the AF evaluation value calculation unit 1021 performs focus detection using the phase difference detection method. The phase difference evaluation value calculation unit 217 of the AF evaluation value calculation unit 1021 starts reading the phase difference signal in order to calculate the phase difference evaluation value required for the phase difference AF (time TF0). When the phase difference signal is read out from all the phase difference detection pixels (time TF1), the reading of the image pickup signal from the image pickup pixel is subsequently started. The phase difference evaluation value calculation unit 217 calculates the phase difference evaluation value based on the phase difference signal while the image pickup signal is being read from the image pickup pixels (periods TF1 to TF2). Then, based on the calculated phase difference evaluation value, the evaluation value reliability for determining whether or not focusing on the subject is possible is calculated (periods TF2 to TF3).

When the calculated evaluation value reliability is equal to or higher than a predetermined threshold value, the determination unit (not shown) of the image sensor 102 determines that the subject can be focused by focus detection using the phase difference detection method. .. Then, after the imaging signals are read out from all the imaging pixels, the phase difference evaluation value is added to the imaging signal and output to the control unit 106 via the signal processing unit 104 (periods TF4 to TF5). The control unit 106 drives the focus lens of the optical mechanism unit 1011 based on the phase difference evaluation value to perform a focusing operation (periods TF5 to TF7). When the focusing operation is completed, the exposure operation on the pixel 201 is started for the next still image shooting in the same manner as at the time T0 (time TF7).

On the other hand, the determination unit (not shown) of the image sensor 102 determines that it is difficult to focus on the subject only by focusing detection using the phase difference detection method when the calculated evaluation value reliability is less than a predetermined threshold value. To do. Therefore, the AF evaluation value calculation unit 1021 subsequently performs focus detection using the contrast detection method. The determination unit (not shown) may be the phase difference evaluation value calculation unit 217 or the contrast evaluation value calculation unit 218. Alternatively, it may be a peripheral circuit (circuit unit) provided on the second chip 21 shown in FIG. 2 (b).

Here, before explaining the operation of the contrast evaluation value calculation unit 218 of the AF evaluation value calculation unit 1021, the contrast AF will be briefly described. In contrast AF, the contrast evaluation value is calculated at a predetermined cycle while controlling the optical mechanism unit 1011 to move the focus lens. Then, the focus lens is driven in a direction in which the contrast evaluation value calculated based on the imaging signal of the still image captured this time is larger than the contrast evaluation value calculated based on the imaging signal of the still image captured last time. To perform focusing operation. In contrast AF, in order to determine the driving direction of the focus lens, contrast evaluation values at at least two different times are required.

Therefore, when the first still image is taken, the focus lens is generally focused in advance based on the imaging signal at the time of live view before the still image is taken. Next, when shooting the second still image, the focus lens is based on the difference between the contrast evaluation value based on the image pickup signal during live view and the contrast evaluation value based on the image pickup signal during the first still image shooting. Determine the driving direction of. The same applies when the third and subsequent still images are taken.

The operation of the contrast evaluation value calculation unit 218 will be described again with reference to FIG. When the image pickup signal is read out from all the image pickup pixels (time TF4), the contrast evaluation value calculation unit 218 calculates the contrast evaluation value based on the image pickup signal from which the high frequency component is extracted (period TF4 to TF6). The image sensor 102 outputs the calculated contrast evaluation value to the control unit 106 via the signal processing unit 104 (periods TF6 to TF8). Since the contrast evaluation value is output in the form of being added to the imaging signal, a blanking period is set from the reading of the imaging signal to the calculation of the contrast evaluation value (periods TF4 to TF6).

When the control unit 106 acquires the contrast evaluation value from the contrast evaluation value calculation unit 218 (time TF8), the control unit 106 drives the focus lens of the optical mechanism unit 1011 based on the contrast evaluation value to perform a focusing operation (period TF8 to TF9). ). When the focusing operation is completed, the exposure operation on the pixel 201 is started for the next still image shooting in the same manner as in the phase difference AF (time TF9).

As described above, in the present embodiment, the imaging signal is read after the phase difference signal is read. As a result, the phase difference evaluation value can be calculated without waiting for the completion of reading the imaging signals from all the imaging pixels, so that the hybrid AF can be started at an earlier timing. As a result, for example, the continuous shooting speed of still images can be improved.

Further, in the present embodiment, whether or not to calculate the contrast evaluation value is determined according to the phase difference evaluation value. As a result, when focusing on the subject is possible by focus detection using the phase difference detection method, focus detection using the contrast detection method is omitted, so that the focusing operation can be speeded up. .. In addition, even if it is difficult to focus on the subject only by focusing detection using the phase difference detection method, focus detection using the contrast detection method should be started as soon as the reading of the imaging signals from all the imaging pixels is completed. Can be done. Therefore, the focusing operation can be speeded up.

FIG. 12 is a flowchart showing a control method of the image pickup device 102 according to the first embodiment. The control unit 106 of the present embodiment performs hybrid AF according to the flowchart shown in FIG. For example, when the operation unit 108 is operated by the user to start the still image continuous shooting mode, the control unit 106 controls the optical mechanism unit 1011 to open the mechanical shutter (step S1201). As a result, the exposure on the pixel 201 starts (step S1202). After that, when a predetermined exposure period elapses, the control unit 106 controls the optical mechanism unit 1011 to close the mechanical shutter (step S1203).

Subsequently, the phase difference evaluation value calculation unit 217 starts reading the phase difference signal in order to calculate the phase difference evaluation value required for the phase difference AF (step S1204). Then, the reading of the phase difference signal is repeated until the reading of the phase difference signal from all the phase difference detection pixels is completed (step S1205). When the reading of the phase difference signal from all the phase difference detection pixels is completed, the reading of the imaging signal from the imaging pixel is started (step S1206). The read image pickup signal is output to the contrast evaluation value calculation unit 218 and the signal processing unit 104.

The phase difference evaluation value calculation unit 217 calculates the phase difference evaluation value based on the read phase difference signal before the reading of the imaging signal is completed (step S1207). The determination unit of the image sensor 102 calculates the evaluation value reliability fnclvl, which is the degree of coincidence of the pair of phase difference signals, based on the phase difference evaluation value, and whether or not the evaluation value reliability fnclvl is equal to or higher than a predetermined threshold value fth. (Step S1208).

In step S1208, when the reliability fnclvl is equal to or higher than the threshold value fth (YES), the determination unit of the image sensor 102 determines that the subject can be focused by the focus detection using the phase difference detection method. Then, the process proceeds to step S1209. Then, it waits for the reading of the imaging signals from all the imaging pixels to be completed.

When the image pickup signals are read out from all the image pickup pixels, the image pickup element 102 outputs the phase difference evaluation value to the control unit 106 via the signal processing unit 104 in the form of adding the phase difference evaluation value to the image pickup signal (step S1210). The control unit 106 determines the feedback control amount based on the phase difference evaluation value, controls the drive unit 103 to drive the focus lens in the optical mechanism unit 1011 and performs the focusing operation (step S1211).

On the other hand, in step S1208, when the reliability fnclvl is less than the threshold value fth (NO), the determination unit of the image sensor 102 determines that it is difficult to focus on the subject only by focusing detection using the phase difference detection method. Then, the process proceeds to step S1212. Then, it waits for the reading of the imaging signals from all the imaging pixels to be completed.

When the image pickup signals are read out from all the image pickup pixels, the contrast evaluation value calculation unit 218 calculates the contrast evaluation value based on the image pickup signals (step S1213). The image sensor 102 outputs the contrast to the control unit 106 via the signal processing unit 104 in the form of adding contrast to the image pickup signal (step S1214). The control unit 106 determines the feedback control amount based on the phase difference evaluation value, controls the drive unit 103 to drive the focus lens in the optical mechanism unit 1011 to perform the focusing operation (step S1215).

When the focusing operation is completed, the control unit 106 confirms, for example, whether or not the operation unit 108 is operated by the user to end the still image continuous shooting mode (step S1216). When the still image continuous shooting mode is terminated (YES), the hybrid AF processing is terminated. On the other hand, if the still image continuous shooting mode is continuing (NO), the process returns to step S1201 and the above flowchart is repeated to shoot the next still image.

As described above, the image sensor of the present embodiment has a phase difference evaluation value calculation unit that calculates a phase difference evaluation value based on a phase difference signal and a contrast evaluation value calculation unit that calculates a contrast evaluation value based on an imaging signal. And have. Then, before the reading of the imaging signal is completed, the phase difference evaluation value is calculated based on the phase difference signal, and whether or not to calculate the contrast evaluation value is determined according to the phase difference evaluation value.

With such a configuration, the phase difference evaluation value can be calculated without waiting for the completion of reading the imaging signals from all the imaging pixels, so that the start timing of the hybrid AF can be accelerated. That is, the focus detection that combines the phase difference detection method and the contrast detection method can be performed at higher speed.

Further, when the focus on the subject can be focused by the focus detection using the phase difference detection method, the focus detection using the contrast detection method can be omitted, so that the focus detection can be further speeded up. it can. The determination unit for determining whether or not to calculate the contrast evaluation value may be the phase difference evaluation value calculation unit 217 or the contrast evaluation value calculation unit 218. Alternatively, it may be a peripheral circuit (circuit unit) provided on the second chip 21 shown in FIG. 2 (b).

(Second Embodiment)
Next, the image pickup apparatus according to the second embodiment will be described with reference to FIGS. 13 to 15. In the first embodiment, a configuration having one row signal line 202 for each row of the image sensor 102 has been described. On the other hand, in the present embodiment, at least two row signal lines 202a and 202b are provided for each row of the image sensor 102b, and the image pickup signal from the image pickup pixel and the phase difference signal from the phase difference detection pixel are parallel to each other. The configuration that can be read out will be described.

FIG. 13 is a schematic view showing the configuration of the image pickup device 102b according to the second embodiment. The image sensor 102b of the present embodiment shown in FIG. 13 has two row signal lines 202a and 202b for each row. Then, the AD conversion unit 211a, the row scanning circuit 213a, and the horizontal signal line 215a are provided on one side of the pixel array of the image sensor 102b, and the AD conversion unit 211b, the row scanning circuit 213b, and the horizontal are on the other side. It has a signal line 215b. Since other configurations are substantially the same as those of the first embodiment, description thereof will be omitted. Hereinafter, a configuration different from that of the first embodiment will be mainly described.

Similar to the first embodiment, a plurality of pixels 201 are arranged in a matrix on the first chip 20 of the image sensor 102b of the present embodiment. Among these pixels 201, the column signal line 202b is connected to the pixel 201 of the phase difference detection row in which the sub-pixels SHA and SHB are both arranged. On the other hand, the column signal line 202a is connected to the pixel 201 of the imaging row in which only the normal imaging pixel is arranged. The configuration is not necessarily limited to this, and in the present embodiment, all the sub-pixels SHA and SHB of the pixel array may be connected to the column signal line 202b.

On the other hand, the AD conversion unit 211a, the AD conversion unit 211b, the row scanning circuit 213a, and the row scanning circuit 213b are arranged on the second chip 21 of the image pickup device 102b of the present embodiment. The AD conversion unit 211a is controlled by the column scanning circuit 213a, AD-converts the imaging signal output to the column signal line 202a, and outputs the imaging signal to the horizontal signal line 215a. Similarly, the AD conversion unit 211b is controlled by the column scanning circuit 213b, AD-converts the imaging signal or the phase difference signal output to the column signal line 202b, and outputs the imaging signal or the phase difference signal to the horizontal signal line 215b. The column scanning circuits 213a and 213b are controlled by the timing control circuit 214.

With such a configuration, the imaging signal output from the normal imaging pixel is output to the contrast evaluation value calculation unit 218 and the signal processing unit 104 via the column signal line 202a or the column signal line 202b. On the other hand, the phase difference signal output from the phase difference detection pixel including the sub-pixels SHA and SHB is output to the signal switching unit 216 via the column signal line 202b. The signal switching unit 216 switches the output destination of the signal read out via the column signal line 202b. The signal switching unit 216 outputs the imaging signal to the contrast evaluation value calculation unit 218 and the signal processing unit 104, and outputs the phase difference signal to the phase difference evaluation value calculation unit 217.

Here, the hybrid AF in the image pickup apparatus of the present embodiment will be described again with reference to FIG. The row scanning circuit 212 of the present embodiment scans the phase difference detection row in which the sub-pixels SHA and SHB are arranged and the scanning row in which only the normal imaging pixels are arranged in parallel.

Specifically, when shooting is started by operating the operation unit 108 or the like, the first line, the second line, the ninth line, the tenth line, ..., Which are the phase difference detection lines, are sequentially scanned. At the same time, the imaging rows 3 to 8, 11 to 16, ..., Are sequentially scanned. In this way, by reading out the imaging signal and the phase difference signal in parallel using the two column signal lines 202a and 202b, it is possible to speed up the reading of the imaging signal and the phase difference signal.

The pixel arrangement in the image sensor 102b is not necessarily limited to the 8-row cycle as shown in FIG. 10, and does not have to be periodic. In the image sensor 102b of the present embodiment, it is sufficient that at least one row each of the phase difference detection row in which the sub-pixels SHA and SHB are arranged and the imaging row in which the sub-pixels SHA and SHB are not arranged are present. ..

Next, the hybrid AF in the imaging device of the present embodiment will be described. FIG. 14 is a timing chart showing a control method of the image pickup device 102b according to the second embodiment. In the timing chart of the first embodiment shown in FIG. 11, reading of the imaging signal is started after the reading of the phase difference signal is completed. On the other hand, in the timing chart of the present embodiment shown in FIG. 14, the image pickup signal is read out in parallel with the reading out of the phase difference signal. Since other configurations are substantially the same as those of the first embodiment, description thereof will be omitted. Hereinafter, a configuration different from that of the first embodiment will be mainly described.

For example, when the operation unit 108 is operated by the user to start the still image continuous shooting mode, the control unit 106 sets the still image continuous shooting control signal indicating that the still image continuous shooting mode is HIGH (time T0). As a result, at the same time that the mechanical shutter of the optical mechanism unit 1011 is opened, the accumulated charge of the pixel 201 is reset and the exposure on the pixel 201 is started. After that, when the exposure period set to satisfy a predetermined exposure condition elapses, the mechanical shutter of the optical mechanism unit 1011 is closed, the light from the subject is blocked, and the exposure at the pixel 201 ends (time TF0).

First, the AF evaluation value calculation unit 1021 performs focus detection using the phase difference detection method. The phase difference evaluation value calculation unit 217 of the AF evaluation value calculation unit 1021 is positioned from the phase difference detection pixel via the horizontal signal line 215b and the signal switching unit 216 in order to calculate the phase difference evaluation value required for the phase difference AF. The reading of the phase difference signal is started (time TF0). At the same time, reading of the imaging signal from the imaging pixel is started via the horizontal signal line 215a (time TF0).

When the phase difference signal is read from all the phase difference detection pixels (time TF1), the phase difference evaluation value calculation unit 217 calculates the phase difference evaluation value based on the phase difference signal (periods TF1 to TF2). After that, the phase difference evaluation value calculation unit 217 calculates the evaluation value reliability for determining whether or not focusing on the subject is possible based on the calculated phase difference evaluation value (periods TF2 to TF3). ). Since the subsequent processing is the same as the timing chart of the first embodiment shown in FIG. 11, the description thereof will be omitted.

FIG. 15 is a flowchart showing a control method of the image pickup device 102b according to the second embodiment. The control unit 106 of the present embodiment performs hybrid AF according to the flowchart shown in FIG. In the flowchart of the first embodiment shown in FIG. 12, the reading of the imaging signal is started after the reading of the phase difference signal is completed. On the other hand, in the flowchart of the present embodiment shown in FIG. 15, the imaging signal is read out in parallel with the reading out of the phase difference signal. Since other configurations are substantially the same as those of the first embodiment, description thereof will be omitted. Hereinafter, a configuration different from that of the first embodiment will be mainly described.

For example, when the operation unit 108 is operated by the user to start the still image continuous shooting mode, the control unit 106 controls the optical mechanism unit 1011 to open the mechanical shutter (step S1201). As a result, the exposure on the pixel 201 starts (step S1202). After that, when a predetermined exposure period elapses, the control unit 106 controls the optical mechanism unit 1011 to close the mechanical shutter (step S1203).

Subsequently, the phase difference evaluation value calculation unit 217 starts reading the phase difference signal in order to calculate the phase difference evaluation value required for the phase difference AF (step S1204). At the same time, reading of the image pickup signal from the image pickup pixel is started via the horizontal signal line 215a (step S1206). The read image pickup signal is output to the contrast evaluation value calculation unit 218 and the signal processing unit 104. Then, the reading of the phase difference signal is repeated until the reading of the phase difference signal from all the phase difference detection pixels is completed (step S1205).

When the reading of the phase difference signal from all the phase difference detection pixels is completed, the phase difference evaluation value calculation unit 217 calculates the phase difference evaluation value based on the read phase difference signal before the reading of the imaging signal is completed. (Step S1207). Since the subsequent processing is the same as the flowchart of the first embodiment shown in FIG. 12, the description thereof will be omitted.

As described above, the image sensor of the present embodiment scans the row in which the phase difference detection pixel is arranged and the row in which the phase difference detection pixel is not arranged in parallel. As a result, the reading of the imaging signal from the imaging pixel is completed earlier, so that the hybrid AF can be started earlier. That is, the focus detection that combines the phase difference detection method and the contrast detection method can be further speeded up.

(Modified Embodiment)
The present invention is not limited to the above embodiment, and various modifications are possible. For example, the configuration of the image pickup apparatus described in the above embodiment shows an example, and the image pickup apparatus to which the present invention can be applied is not limited to the configuration of the above embodiment.

The present invention supplies a program that realizes one or more functions of the above-described embodiment to a system or device via a network or storage medium, and one or more processors in the computer of the system or device reads and executes the program. It can also be realized by the processing to be performed. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

It should be noted that the above embodiments are merely examples of implementation of the present invention, and the technical scope of the present invention should not be construed in a limited manner by these. That is, the present invention can be implemented in various forms without departing from the technical idea or its main features.

101: Image pickup optical system 102, 102b: Image sensor 106: Control unit 201: Pixel 202: Column signal line 211: AD conversion unit 215: Horizontal signal line 217: Phase difference evaluation value calculation unit 218: Contrast evaluation value calculation unit 1021: AF evaluation value calculation unit

Claims (10)

An image sensor in which a first chip and a second chip are laminated on each other.
A plurality of imaging pixels that receive light focused by the imaging optical system and a plurality of phase difference detection pixels that receive a pair of light fluxes that have passed through different pupil region regions of the imaging optical system are arranged in a matrix. Pixel array and
A circuit unit that reads an imaging signal from the imaging pixel and reads a phase difference signal from the phase difference detecting pixel.
A contrast evaluation value calculation unit that calculates a contrast evaluation value based on the image pickup signal,
A phase difference evaluation value calculation unit that calculates a phase difference evaluation value based on the phase difference signal before the reading of the imaging signal is completed.
A determination unit that determines whether or not to calculate the contrast evaluation value according to the phase difference evaluation value.
Equipped with a,
The pixel array is disposed in the first chip, the image pickup device in which the contrast evaluation value calculating unit and the phase difference evaluation value calculating unit is characterized that you have been disposed on the second chip. The contrast evaluation value is calculated when the reliability of the evaluation value representing the degree of coincidence of the pair of the phase difference signals is less than a predetermined threshold value, and the contrast evaluation value is calculated when the reliability of the evaluation value is equal to or more than the threshold value. The image pickup device according to claim 1, wherein the image pickup device is not calculated. Before SL circuit unit, after the phase difference detecting pixels are scanned arranged rows, the imaging device according to claim 1 or 2, wherein the phase difference detection pixel scans the rows that have not been arranged .. Before SL circuit includes a scanning line which the phase difference detection pixels are arranged, in claim 1 or 2, wherein the phase difference detection pixels and performing in parallel the scanning lines not disposed The image sensor described. The third or fourth aspect of the present invention, wherein the phase difference evaluation value calculation unit calculates the phase difference evaluation value while scanning a row in which the phase difference detection pixel is not arranged. Image sensor. Further, it has a signal switching unit for switching the output destination of the signal read from the pixel array by the circuit unit .
The signal switching unit is arranged on the second chip, outputs the image pickup signal to the contrast evaluation value calculation unit, and outputs the phase difference signal to the phase difference evaluation value calculation unit. Item 3. The image pickup device according to item 3. Each row of the pixel array has a first row signal line and a second row signal line.
The image pickup signal is output to the contrast evaluation value calculation unit via the first row signal line or the second row signal line, and the phase difference signal is output to the contrast evaluation value calculation unit via the second row signal line. The image pickup device according to claim 4, wherein the image pickup device is output to an evaluation value calculation unit. When the contrast evaluation value is calculated, the contrast evaluation value is output to an external control unit of the image sensor, and when the contrast evaluation value is not calculated, the phase difference evaluation value is output to the control unit. The image pickup device according to any one of claims 1 to 7. The image pickup device according to claim 8, wherein the phase difference evaluation value or the contrast evaluation value is output to the control unit in a form of being added to the image pickup signal. Comprising the imaging device according to any one of claims 1-9, wherein the imaging optical system, and a control section, a
The control unit is an imaging device that performs a focusing operation of the imaging optical system based on either the phase difference evaluation value or the contrast evaluation value.

Images