JP7175635B2 - Imaging device and its control method - Google Patents

Description

The present invention relates to acquisition processing of phase difference information in an imaging device.

Imaging devices such as digital cameras perform calculations for autofocus (AF) using phase difference information obtained from an imaging device. In order to achieve both signal readout that enables highly accurate focus detection and high-speed signal readout with low power consumption, various methods related to image sensor readout have been proposed.

In Patent Document 1, each pixel portion has a plurality of photoelectric conversion portions, and the signals of the plurality of photoelectric conversion portions are read out independently in some pixel portions of all the pixels, and the signals of the plurality of photoelectric conversion portions are read out in the remaining pixel portion. A method for combining and then reading out signals is disclosed. Since the phase difference information is read out only in the required area, it is possible to shorten the operation time and reduce the power consumption.

In Patent Document 2, the imaging range is divided into a plurality of areas, the phase difference information is read in the first area where focus detection needs to be performed, and the thinning rate is set larger in the second area than in the first area. is disclosed. Thereby, power consumption can be reduced.

Japanese Patent Application Laid-Open No. 2002-200003 discloses switching the reading method based on the spatial frequency of the subject image for each divided area. Precise focusing is possible for high-frequency subjects, and power consumption can be suppressed when shooting low-frequency subjects.

JP 2013-211833 A JP 2015-79162 A JP 2015-165280 A

2. Description of the Related Art In imaging apparatuses, phase difference information obtained from an imaging element can be used in various situations. In the prior art, when reading out phase difference information from some pixel groups out of all pixels, it was not possible to read out so as to simultaneously satisfy the conditions necessary for a plurality of functions within one frame. Further, when the phase difference information is read out from the entire pixel, it can be used for a plurality of functions, but the frame rate is unavoidably lowered.
SUMMARY OF THE INVENTION An object of the present invention is to provide an imaging apparatus capable of acquiring phase difference information according to a subject while suppressing a decrease in frame rate.

An image pickup apparatus according to an embodiment of the present invention includes an image pickup unit having a plurality of pixel units capable of acquiring phase difference information corresponding to distance information of a subject, and a control for reading out signals from the pixel units in units of rows. and a control means for determining the interval and the number of rows of phase difference information to be read out, wherein the control means controls the image pickup means to read out a moving object more than the number of rows when the image pickup means picks up an image of a stationary object. It is characterized by increasing the number of rows when imaging.

ADVANTAGE OF THE INVENTION According to this invention, the imaging device which can acquire the phase difference information according to a to-be-photographed object can be provided, suppressing the fall of a frame rate.

1 is a block diagram showing a configuration example of an imaging device according to an embodiment of the present invention; FIG. It is a schematic diagram which shows the pixel arrangement|positioning in an image pick-up element. It is a block diagram which shows the structural example of an image pick-up element. 4 is a flowchart for explaining the operation of the imaging device of this embodiment; 4 is a flowchart for explaining AF operation of the embodiment; FIG. 6 is a flowchart for explaining processing subsequent to FIG. 5; FIG. 5 is a flowchart for explaining focus detection processing according to the embodiment; 4 is a flowchart for explaining servo AF control according to the embodiment; FIG. 10 is a diagram showing a setting example of readout rows of phase difference information; FIG. 10 is a diagram showing another example of setting of readout rows of phase difference information; 9 is a flowchart for explaining setting of readout rows of phase difference information; FIG. 12 is a flowchart for explaining processing subsequent to FIG. 11; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of an imaging device according to this embodiment. As an example, a lens interchangeable camera system will be described, but the present invention can be applied to an image pickup apparatus having a configuration in which a photographing lens section is incorporated in a camera body section.

A digital camera main body (hereinafter simply referred to as a main body) 200 is mountable with a lens device 100 that is an interchangeable lens. The lens device 100 is detachably attached to the body portion 200 via a mount portion (not shown) having the electrical contact unit 106 .

The lens device 100 includes a photographing lens unit 101 including a zoom mechanism, a diaphragm and shutter 102 for controlling the amount of light, and a focus lens 103 for focus adjustment. A motor 104 drives the focus lens 103 according to a control command from the lens controller 105 . A lens controller 105 includes a CPU (Central Processing Unit), and controls driving of the movable lens, diaphragm and shutter 102 and focus lens 103 in the photographing lens unit 101 .

The main unit 200 includes an imaging element 201, photoelectrically converts reflected light from an object imaged through the lens device 100, and outputs an electric signal. The imaging device 201 is a CCD (charge-coupled device) type image sensor or a CMOS (complementary metal oxide semiconductor) type image sensor. An A/D (analog/digital) conversion unit 202 acquires an output signal from the imaging element 201 and converts it into a digital signal. The A/D conversion unit 202 includes a CDS (correlated double sampling) circuit that removes output noise from the image sensor 201 and a nonlinear amplifier circuit that performs amplification before A/D conversion.

An image processing unit 203 acquires the output of the A/D conversion unit 202 and performs image correction processing, development processing, and the like. An AF signal processing unit 204 acquires the output of the A/D conversion unit 202 and performs AF signal processing for focus adjustment.

A format conversion unit 205 performs predetermined format conversion on the data processed by the image processing unit 203 and outputs the converted data to the memory 206 . The memory 206 is a high-speed built-in memory, and uses, for example, a random access memory (hereinafter referred to as DRAM). A DRAM functions as a high-speed buffer for temporarily storing image data, or is used as a working memory for compressing or decompressing an image.

An image recording unit 207 includes a recording medium such as a memory card and an interface unit, and records captured image data on the recording medium. A timing generator 208 outputs a timing control signal to the image sensor 201, A/D converter 202, and other components in accordance with a control command from the system controller 209. FIG.

A system control unit 209 includes a CPU, executes a predetermined control program, controls a photographing sequence, and supervises control of the entire camera system. The system control unit 209 can communicate with the lens controller 105 of the lens device 100 via the lens communication unit 210 . The lens communication unit 210 has a communication function between the main unit 200 and the lens device 100, and transmits and receives data at the timing of the synchronization signal.

An AE processing unit 211 performs AE (automatic exposure) processing according to a control command from the system control unit 209 . An image display memory (hereinafter referred to as VRAM) 212 is connected to the memory 206 and the image display unit 213 and stores image display data. The image display unit 213 displays images according to the image display data acquired from the VRAM 212, displays for operation assistance, displays the camera status, and displays the shooting screen and the distance measurement area (focus detection area) during shooting. do.

The operation unit 214 includes operation members for the user to operate the imaging device. For example, the operation unit 214 is operation means such as a menu operation switch for setting the imaging function of the imaging device and image reproduction, and a touch panel used on the display screen. A shooting mode SW (switch) 215 is an operation switch for the user to select a shooting mode such as macro mode or sports mode. A main switch 216 is a switch used when powering on the camera system.

Switches 217 and 218 are switches that are turned on and off by operating the release button. The first switch 217 is a switch (hereinafter referred to as SW1) for performing shooting standby operations such as AF and AE. The second switch 218 is a photographing switch (hereinafter referred to as SW2) for which the user issues a photographing instruction after operating SW1.

Acquisition processing of an imaging signal in this embodiment will be described. The imaging device 201 receives light that has passed through the imaging optical system of the lens device 100, and photoelectrically converts the light into signal charges according to the amount of incident light by means of a photodiode. The signal charge accumulated in each photodiode is sequentially read out from the image sensor 201 as a voltage signal corresponding to the signal charge based on the driving pulse given from the timing generator 208 according to the command from the system control unit 209 .

In the present embodiment, an example in which each pixel portion of the image sensor 201 is composed of a pair of photodiodes A and B and one microlens provided in common for the pair of photodiodes A and B will be described. That is, the incident light is split by the microlens to form a pair of optical images on the pair of photodiodes A and B. FIG. A pair of photodiodes A and B output a pair of pixel signals used for generating AF signals, which will be described later. A pixel signal output from the photodiode A is referred to as an A signal, and a pixel signal output from the photodiode B is referred to as a B signal. Phase difference information can be acquired by phase difference detection calculation using the A signal and the B signal. Further, by adding the A signal and the B signal, an imaging signal (A+B signal) can be obtained.

In AF using the imaging plane phase difference detection method (so-called imaging plane phase difference AF), a signal for AF (focus detection and a signal for focus adjustment) are obtained. The AF signal processing unit 204 performs a correlation operation on the pair of acquired image signals to calculate a phase difference (hereinafter referred to as an image shift amount) that is a shift amount between the pair of image signals. The AF signal processing unit 204 calculates the defocus amount and defocus direction of the imaging optical system from the image shift amount. Distance information from the imaging device to the subject can be obtained using the imaging relational expression of the imaging optical system based on the amount of image shift or the amount of defocus.

The configuration of the imaging element 201 will be described with reference to FIGS. 2 and 3. FIG. FIG. 2 partially shows the pixel array 300 of the imaging device 201 . A pixel array 300 has a configuration in which a large number of unit pixels 301 are arranged in rows and columns. The microlenses 302 are arranged corresponding to the unit pixels 301 . Photodiodes (hereinafter abbreviated as PDs) 303 a and 303 b as photoelectric conversion means are arranged below the microlens 302 to form a unit pixel 301 . The PDs 303a and 303b have a pupil division structure, and two images (hereinafter referred to as A image and B image) of the same subject having different phase differences are incident. The PD 303a constitutes a photoelectric conversion unit for A image, and the PD 303b constitutes a photoelectric conversion unit for B image. Although FIG. 2 shows a configuration in which each pixel unit includes two photoelectric conversion units corresponding to one microlens 302, a configuration including three or more divided photoelectric conversion units may be used.

The circuit configuration of the imaging element 201 will be described with reference to FIG. In the pixel array 300, (m+1) unit pixels 301 are arranged in the horizontal direction, and (n+1) unit pixels 301 are arranged in the vertical direction. Vertical scanning of each pixel is performed by a vertical scanning circuit control unit 304 and a vertical scanning circuit 306, and it is possible to control reading out signals from all pixels in units of rows.

The vertical scanning circuit control unit 304 includes a first readout setting unit 305a and a second readout setting unit 305b, and controls the vertical scanning circuit 306 based on programmed readout settings. The vertical scanning circuit 306 transfers pixel signals by sending pulses to the unit pixels 301 according to the readout setting units 305a and 305b.

A timing generator (TG) 307 supplies control pulses necessary for signal readout to each circuit unit according to settings by the CPU of the system control unit 209 . Each circuit section includes a vertical scanning circuit 306, a reading circuit 310, an AD conversion circuit 311, a horizontal scanning circuit 312, and the like. Although the timing generator 307 illustrated in FIG. 3 is built in the image sensor 201, it may be arranged outside the image sensor 201. FIG.

Pixel signals photoelectrically converted by the unit pixels 301 are output to vertical output lines 308 row by row by driving signals supplied from the vertical scanning circuit 306 . The vertical scanning circuit control unit 304 controls whether the vertical scanning circuit 306 reads out pixel signals in a first drive mode or a second drive mode, which will be described later, when obtaining an output from a specific row. A constant current source 309 is connected to a vertical output line 308 and forms a source follower circuit together with a pixel amplifier transistor (not shown).

The readout circuit 310 has a function of amplifying the output from the vertical output line 308 of each pixel column. The AD conversion circuit 311 performs A/D conversion on the output of the reading circuit 310 and outputs a digital signal. The digital image signals converted by the AD conversion circuit 311 are sequentially selected by the horizontal scanning circuit 312 . The output unit 313 processes the selected pixel signal and outputs it to the outside of the image sensor 201 .

FIG. 4 is a flow chart for explaining the operation of the imaging device according to this embodiment. The following processing is realized by the CPU of the system control unit 209 executing a predetermined program. In S301, the AE processing unit 211 acquires the output of the image processing unit 203, performs AE processing, and proceeds to processing in S302.

In S302, the system control unit 209 checks the state of the first switch 217 (SW1) to determine whether SW1 is ON. If it is determined that SW1 is ON, the process proceeds to S303, and if it is determined that SW1 is OFF, the process returns to S301. In S303, an AF operation, which will be described later, is performed, and then the process proceeds to S304.

In S304, the system control unit 209 checks the state of the first switch 217 (SW1) to determine whether SW1 is ON. If it is determined that SW1 is ON, the process proceeds to S305, and if it is determined that SW1 is OFF, the process returns to S301. In S305, AF processing (hereinafter referred to as servo AF), which will be described later, is executed. Servo AF is a function capable of capturing an image while continuously focusing on a moving subject, and is effective when performing focus adjustment on a moving subject. In this embodiment, the configuration is such that the servo AF can be arbitrarily switched according to an operation instruction from the user. Thereafter, in S306, the system control unit 209 checks the state of the second switch 218 (SW2) to determine whether SW2 is ON. If it is determined that SW2 is ON, the process proceeds to S307, and if it is determined that SW2 is OFF, the process returns to S304. After the photographing operation is performed in S306, the process returns to S301.

5 and 6 are flowcharts for explaining S303 (AF operation) in FIG. First, in S401 of FIG. 5, the AE processing unit 211 performs AE processing based on the output of the image processing unit 203, and proceeds to S402. In S402, the AF signal processing unit 204 and the system control unit 209 perform focus detection processing to detect the defocus amount, the defocus direction, and their reliability, and proceed to S403. Details of the focus detection process will be described later with reference to FIG.

In S403, the system control unit 209 compares the reliability of the focus detection result obtained in S402 with a preset threshold. Let this threshold be a reliability threshold 2 . If the reliability is determined to be higher than the reliability threshold 2, the process proceeds to S404, and if the reliability is less than or equal to the reliability threshold 2, the process proceeds to S410 in FIG. If it is determined that the reliability is equal to or lower than the reliability threshold 2, the accuracy of the defocus amount cannot be guaranteed, but the direction of the focus position of the subject corresponding to the defocus direction can be guaranteed.

In S404, the system control unit 209 compares the defocus amount detected in S402 with a preset threshold value. Let this threshold be the Def amount threshold 2 . Regarding the Def amount threshold 2, for example, when the defocus amount is equal to or less than the Defocus amount threshold 2, a value (for example, 5 times the depth of focus). If it is determined that the defocus amount is equal to or less than Def amount threshold 2, the process proceeds to S405, and if it is determined that the defocus amount is greater than Def amount threshold 2, the process proceeds to S409.

In S405, the system control unit 209 compares the reliability of the focus detection result obtained in S402 with a preset threshold. Let this threshold be a reliability threshold 1 . For the reliability threshold 1, for example, when the reliability is equal to or higher than the reliability threshold 1, the variation in accuracy of the defocus amount is set to a value within a predetermined range (for example, within the depth of focus). If the reliability is determined to be higher than the reliability threshold 1, the process proceeds to S406, and if it is determined to be the reliability threshold 1 or less, the process proceeds to S409.

In S406, the system control unit 209 compares the defocus amount detected in S402 with a preset threshold value. This threshold is defined as Def amount threshold 1 . For Def amount threshold 1, for example, when the detected defocus amount is equal to or less than Def amount threshold 1, it is set to a value that controls the position of the focus lens 103 within the depth of focus. If it is determined that the defocus amount is equal to or less than the Def amount threshold value 1, the process proceeds to S407, and if it is determined to be greater than the Def amount threshold value 1, the process proceeds to S408.

In S407, the system control unit 209 determines that the current focus detection state is the in-focus state, and shifts to return processing. Also, in S408, the system control unit 209 transmits a drive amount control signal corresponding to the defocus amount detected in S402 to the lens controller 105 via the lens communication unit 210. FIG. The lens controller 105 drives the motor 104 according to the control signal received from the lens communication unit 210 to drive the focus lens 103 . After S408, the process returns to S402.

In S<b>409 , the system control unit 209 transmits to the lens controller 105 via the lens communication unit 210 a drive amount control signal corresponding to a predetermined ratio of the defocus amount detected in S<b>402 . The predetermined ratio is a ratio set so that the drive amount of the focus lens 103 is reduced with respect to the defocus amount, and is set to about 80%, for example. The lens controller 105 drives the motor 104 according to the control signal received from the lens communication unit 210 to drive the focus lens 103 . The drive speed of the focus lens 103 set at that time is set to be slower than the speed at which the lens can be driven in the time corresponding to one frame, for example. As a result, it is possible to prevent the focus lens 103 from being driven beyond the focus position (in-focus position) where the subject is focused when the detected defocus amount is not accurate. After S409, the process returns to S402.

In S410 of FIG. 6, the system control unit 209 determines whether or not the out-of-focus condition is satisfied. Here, the out-of-focus condition is a condition for determining that there is no subject to be focused. For example, the condition is set when lens driving is completed in the entire movable range of the focus lens 103, that is, when both the far-side and near-side lens ends are detected in drive control of the focus lens 103 and returned to the initial positions. be. If the out-of-focus condition is satisfied, the process proceeds to S411, and if the out-of-focus condition is not satisfied, the process proceeds to S412. In S411, the system control unit 209 determines that the current focus detection state is the out-of-focus state, and then shifts to return processing.

In S412, the system control unit 209 determines whether the focus lens 103 has reached the far side or near side lens end. If it is determined that the focus lens 103 has reached the far-side or near-side lens end, the process proceeds to S413; if it is determined that the focus lens 103 has not reached the far-side or near-side lens end, the process proceeds to S414. move on.

In S413, the system control unit 209 transmits a control signal to the lens controller 105, performs control to reverse the driving direction of the focus lens 103, and then proceeds to the processing of S402 in FIG. Also, in S414, the system control unit 209 transmits a control signal to the lens controller 105, performs control to drive the focus lens 103 in a predetermined direction (forward direction), and then proceeds to the processing of S402 in FIG. The drive speed of the focus lens 103 is set to the fastest value within the permissible range of the lens drive speed so that, for example, the subject does not pass the in-focus position when the defocus amount becomes detectable. be.

Next, S402 (focus detection processing) in FIG. 5 will be described with reference to FIG. First, in S501, the system control unit 209 sets a readout row for phase difference information. Details of the setting process will be described later with reference to FIGS. 9, 10, 11 and 12. FIG. In S502, processing for acquiring a pair of image signals (A image signal and B image signal) for focus detection from the image sensor 201 for the readout row set in S501 is performed. In S503, the AF signal processing unit 204 performs vertical row averaging processing on the pair of image signals acquired in S502. This processing can suppress the influence of noise on the image signal.

In S504, the AF signal processing unit 204 performs filter processing on the signal subjected to vertical row averaging processing in S503, and extracts signal components in a predetermined frequency band. Next, proceeding to S505, the AF signal processing unit 204 performs correlation calculation for phase difference detection using the signal filtered in S504 to calculate the amount of correlation. In S506, the AF signal processing unit 204 calculates the amount of correlation change from the amount of correlation calculated in S505, calculates the amount of image shift from the amount of correlation change in the next S507, and proceeds to S508. In S<b>508 , the AF signal processing unit 204 calculates reliability indicating how reliable the calculated image shift amount is. In S509, after conversion processing for converting the image shift amount into the defocus amount is performed, the focus detection processing is terminated and the process proceeds to return processing. Since the correlation amount, the correlation change amount, the calculation of the reliability, and the defocus conversion are known, detailed description thereof will be omitted.

FIG. 8 is a flowchart for explaining servo AF control in this embodiment. In S600, the AF operation described with reference to FIGS. 5 and 6 is performed. In S<b>601 , the system control unit 209 acquires the defocus amount data calculated in S<b>600 and stores it in the memory (DRAM) 206 . In S602, the focus detection processing described with reference to FIG. 7 is performed. The latest acquired defocus amount data is stored in the memory 206 .

In S603, the system control unit 209 compares the defocus amount in S601 stored in the memory 206 with the latest defocus amount acquired in S602, and determines that the defocus amount is equal to or greater than a predetermined value (threshold). Determine if it has changed. If it is determined that the amount of change in the defocus amount is greater than or equal to the threshold, the process proceeds to S604, and if it is determined that the amount of change in the defocus amount is less than the threshold, the process returns to S602 to continue the process.

In S604, the system control unit 209 counts the number of times the defocus amount, which is an evaluation value, has changed by a predetermined value or more determined in S603, and compares it with a predetermined number of times (threshold). If it is determined that the counted number of times is equal to or greater than the predetermined number of times, the process returns to S600 and the AF operation is performed again. For example, when the user changes the subject of interest or the composition, control of the AF operation is started. Further, when it is determined that the number of times counted in S604 is less than the predetermined number of times, the process returns to S602, the focus detection operation is performed, and the monitoring of the defocus amount is continued. By repeatedly performing focus detection after focusing, it is possible to perform a focus adjustment operation that follows the movement of the subject.

The setting of the phase difference information readout row shown in S501 of FIG. 7 will be described with reference to FIGS. 9 and 10. FIG. 9 and 10 are diagrams illustrating lines from which phase difference information is read in the AF operation shown in S303 and the servo AF shown in S305 of FIG. In the image examples shown in FIGS. 9 and 10, the readout rows of the phase difference information are schematically indicated by solid horizontal lines. When a stationary object is imaged (or when a stationary object is detected), the system control unit 209 sets the interval between readout rows of phase difference information to be constant. Further, the system control unit 209 sets the number of readout lines of the phase difference information to be larger when shooting a moving object (or when a moving object is detected) than when shooting a stationary object.

FIG. 9 shows an image example for explaining a method of reading phase difference information in AF operation immediately after the first switch SW1 is turned on by operating the release button. A focus frame (focus state detection frame) 901 in the screen is located in the face area of the main subject. In the AF operation immediately after the first switch SW1 is turned ON, the interval between the rows from which the phase difference information is read is widened as much as possible, and the rows to be read out are evenly arranged in the vertical direction. For example, the minimum size of the face region of the subject that can be detected determines the readout row spacing. The system control unit 209 sets the line spacing D so that one or more horizontal lines for reading the phase difference information can be arranged for the minimum face size.

FIG. 10A shows an example image for explaining a method of reading phase difference information at the start of servo AF shown in S305 of FIG. A focus frame 901 in the screen is positioned in a subject area at a long distance from the imaging device. This is a setting in which the line intervals D of the readout lines of the phase difference information are evenly arranged. This setting corresponds to control for reading pixel signals in the first drive mode by the vertical scanning circuit 306 . When a moving object is located far away, the servo AF continues the phase difference information reading method shown in FIG. 10A while focusing on the object. In this embodiment, for example, distance information of the object is calculated from the focus lens position at which focusing is performed. When the subject is positioned farther than the distance corresponding to a predetermined threshold magnification (for example, 50 times) related to the focal length of the lens device 100 being used, the phase difference information reading method shown in FIG. 10A continues. do.

FIG. 10B shows an example of an image for explaining a method of reading phase difference information when the distance information of a moving object is positioned closer than the distance corresponding to the threshold magnification for the focal length. . A focus frame 901 in the screen is located in the face area of the subject at a short distance from the imaging device. In this case, since the object is moving on the near side, it is necessary to read out as much phase difference information as possible in order to reduce the distance measurement error. Furthermore, in order to suppress the power consumption of the imaging device, the line spacing D is set so that signals are read out from the minimum required area when a moving object is detected. This setting corresponds to control for reading pixel signals in the second drive mode by the vertical scanning circuit 306 . In FIG. 10B, the readout lines are concentrated in the face area of the moving object and its neighboring area, and the line interval D is narrow. By reading the phase difference information in a limited range in the image in this way, it is possible to read the phase difference information at high speed while suppressing power consumption, and realize AF control with high focus detection accuracy.

11 and 12 are flowcharts for explaining the setting of the number of readout lines of phase difference information, that is, the number of readout lines to be set. In S801, the system control unit 209 determines whether the current AF setting mode is the one-shot mode or the servo AF mode. As an AF setting mode other than the servo AF mode, a one-shot mode in which the focus adjustment operation is performed once is exemplified. Using the operation unit 214, the user selects the one-shot mode when instructing focus adjustment to focus on a stationary object, and selects the servo AF mode when instructing focus adjustment to focus on a moving object. can do. If the system control unit 209 determines that the one-shot mode is set, the process advances to S802, and if it determines that the servo AF mode is set, the process advances to S806 in FIG.

In S802, the system control unit 209 determines whether a subject such as a person's face has been detected. If it is determined that the subject has been detected, the process proceeds to S803, and if it is determined that the subject has not been detected, the process proceeds to S806.

In S803, the system control unit 209 executes processing for calculating the contrast value within the rangefinding frame. The distance measurement frame is a focus state detection frame within the photographing screen, and the contrast value can be calculated by a known method from the maximum and minimum pixel values within the distance measurement frame. If it is determined that the contrast value of the image within the range-finding frame (detection frame) calculated in S803 is equal to or greater than the predetermined threshold, the process advances to S804, and if it is determined that the contrast value is less than the predetermined threshold to S805.

In S804, the system control unit 209 sets the readout row number X of the phase difference information to X1. Also, in S805, the system control unit 209 sets the readout row number X of the phase difference information to X2. Let "X1<X2". Proceeding to S813 after S804 and S805, the system control unit 209 sets the final set number of lines to the calculated number of lines, that is, X1 or X2. In this case, the readout lines of the phase difference information are arranged at regular intervals over the entire screen. This row arrangement corresponds to the first driving mode by the vertical scanning circuit 306. FIG. After that, the readout row setting process ends.

On the other hand, in S806 of FIG. 12, the system control unit 209 calculates the contrast value within the rangefinding frame and compares it with a predetermined threshold value. If it is determined that the calculated contrast value is greater than or equal to the threshold, the process proceeds to S807, and if it is determined that the contrast value is less than the threshold, the process proceeds to S808.

In S807, the system control unit 209 sets the readout row number Y of the phase difference information to Y1. Also, in S808, the system control unit 209 sets the readout row number Y of the phase difference information to Y2. It is assumed that "Y1<Y2".

After S807 and S808, the system control unit 209 advances to S809 to determine whether or not to set the phase difference information readout row for the first time. When setting the readout row for the first time, the process proceeds to S810, and when setting the readout row for the second and subsequent times, the process proceeds to S811.

In S810, the system control unit 209 sets the calculated number of lines, that is, Y1 or Y2, arranges the readout lines of the phase difference information at regular intervals on the entire screen, and ends the process. In this embodiment, the number of readout rows X and Y have the relationship of the following formula (1).
X1<X2≤Y1<Y2 Formula (1)

In step S811, the system control unit 209 uses the currently calculated defocus amount to determine whether the distance from the imaging device to the subject (subject distance) is greater than or equal to a predetermined threshold. For example, assume that the threshold is 50f (50 times the focal length f). The object distance can be calculated from the defocus amount and the imaging relational expression related to the imaging optical system of the lens device. If it is determined in S811 that the subject distance is greater than the predetermined threshold, the process ends. If it is determined that the subject distance is equal to or less than the predetermined threshold, the process advances to S812.

In step S<b>812 , the system control unit 209 performs processing for narrowing the range centered on the subject area by concentrating and arranging the readout rows of the phase difference information in the subject area. This row arrangement corresponds to the second drive mode by the vertical scanning circuit 306. FIG. The S/N ratio (signal-to-noise ratio) of the phase difference detection signal in the important area is eliminated, and the unnecessary distance measurement area (focus detection area) is excluded for the subject moving toward the near side (imaging device side). ) can be increased.

In this embodiment, in a split-pupil imaging device capable of acquiring phase difference information, signal readout suitable for a plurality of functions is performed by dynamically changing the vertical period related to the readout row according to the distance information of the subject. . As a result, more accurate phase difference detection can be performed while suppressing a decrease in frame rate.
Although preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention.

103 focus lens 105 lens controller 201 image sensor 204 AF signal processing unit 209 system control unit 302 microlens 303a, 303b photoelectric conversion unit 304 vertical scanning circuit control unit 306 vertical scanning circuit

Claims (10)

an imaging means having a plurality of pixel units capable of acquiring phase difference information corresponding to distance information of a subject ;
a control means for determining the interval and the number of readout rows of the phase difference information by controlling the readout of signals from the pixel unit on a row-by-row basis ;
The control means increases the number of rows when imaging a moving subject by the imaging means compared to the number of rows when imaging a stationary object by the imaging means.
An imaging device characterized by: The control means controls the interval to be constant when imaging the stationary object by the imaging means, and dynamically changing the interval when imaging the moving object by the imaging means. 2. The imaging device according to claim 1, wherein: 3. The imaging apparatus according to claim 1 , wherein said control means sets said readout row to a range including a subject area of said moving subject . 4. The method according to any one of claims 1 to 3, wherein the control means makes the number of lines when the moving subject is detected larger than the number of lines when the moving subject is not detected. The imaging device according to any one of items 1 and 2. The control means sets the number of lines to the first number of lines when the contrast value of the image within the focus state detection frame is higher than a threshold, and sets the number of lines to the first number when the contrast value is equal to or less than the threshold. 4. The imaging apparatus according to any one of claims 1 to 3 , wherein a second number of rows larger than one is set. The control means narrows the interval when the distance information of the moving subject is equal to or less than the threshold than the interval when the distance information of the moving subject is greater than the threshold. The imaging device according to any one of claims 1 to 5 . an operation means for instructing focus adjustment to bring the subject into focus;
focus adjustment means for performing focus detection using the phase difference information and performing focus adjustment on the moving object when the operating means issues a focus adjustment instruction to focus on the moving object . The imaging device according to any one of claims 1 to 6 , characterized by: The control means arranges the readout rows at a uniform first interval, and arranges the readout rows at a second interval narrower than the first interval in a range including the subject area of the moving subject. control placement
4. The imaging device according to claim 3, characterized in that: The pixel unit includes microlenses and a plurality of photoelectric conversion units corresponding to the microlenses, and the plurality of photoelectric conversion units output a plurality of signals having the phase difference information. Item 9. The imaging device according to any one of Items 1 to 8 . Control executed by an imaging device comprising imaging means having a plurality of pixel units capable of acquiring phase difference information corresponding to subject distance information , and control means for performing control to read out signals from the pixel units on a row-by-row basis a method,
a control step of determining, by the control means, the interval and the number of readout rows of the phase difference information in the control of reading out signals from the pixel unit on a row-by-row basis;
In the control step, the control means increases the number of rows when imaging a moving subject by the imaging means compared to the number of rows when imaging a stationary object by the imaging means.
A control method characterized by:

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