JP2019212952A - Imaging device and control method thereof - Google Patents

Abstract

To provide an imaging device capable of acquiring phase difference information corresponding to a subject while suppressing a decrease in the frame rate.SOLUTION: A main body 200 of an imaging device includes an imaging element 201 and can acquire phase difference information. A signal can be read from a pixel portion of the imaging element 201 in units of rows. A system control unit 209 performs control to change the interval between read lines in accordance with the detection state of a subject. When a still object is photographed, the system control unit 209 makes the vertical period related to the read line of the phase difference information constant. In addition, when a moving object is photographed, the system control unit 209 dynamically changes the vertical period related to the read line of the phase difference information according to distance information of the subject, and sets read line of the phase difference information in a range including a subject region in the image.SELECTED DRAWING: Figure 1

Description

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

  An imaging apparatus such as a digital camera performs an autofocus (AF) calculation using phase difference information acquired from an imaging element. In order to achieve both signal readout that enables highly accurate focus detection and low-power consumption and high-speed signal readout, various methods relating to readout of the image sensor have been proposed.

  In Patent Document 1, each pixel unit has a plurality of photoelectric conversion units, and signals of the plurality of photoelectric conversion units are independently read out in some pixel units in all pixels, and the remaining pixel units include a plurality of photoelectric conversion units. A method of synthesizing signals and then reading them is disclosed. Since the phase difference information is read out only in a necessary area, it is possible to shorten the operation time and the power consumption.

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

  Japanese Patent Application Laid-Open No. 2004-133867 discloses switching the reading method based on the spatial frequency of the subject image for each divided area. Precise focusing is possible for a high-frequency subject, and power consumption can be suppressed when shooting a low-frequency subject.

JP 2013-2111833 A JP, 2015-79162, A Japanese Patent Laying-Open No. 2015-165280

In an imaging apparatus, phase difference information obtained from an imaging device can be used in various situations. In the conventional technique, when phase difference information is read out from a part of a group of pixels in all pixels, it is impossible to read out so as to simultaneously satisfy conditions necessary for a plurality of functions in one frame. In addition, when phase difference information is read from the entire pixel, it can be used for a plurality of functions, but a reduction in frame rate is unavoidable.
An object of the present invention is to provide an imaging apparatus capable of acquiring phase difference information corresponding to a subject while suppressing a decrease in frame rate.

  An apparatus according to an embodiment of the present invention includes an imaging unit having a plurality of pixel units capable of acquiring phase difference information, and a control unit that performs control to read out signals from the pixel units in units of rows. The control means obtains subject distance information and performs control to change the interval of the readout rows of the phase difference information corresponding to the distance information.

  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.

It is a block diagram which shows the structural example of the imaging device which concerns on embodiment of this invention. It is a schematic diagram which shows 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. It is a flowchart explaining operation | movement of the imaging device of this embodiment. It is a flowchart explaining AF operation | movement of this embodiment. It is a flowchart explaining the process following FIG. It is a flowchart explaining the focus detection process of this embodiment. It is a flowchart explaining the servo AF control of this embodiment. It is a figure which shows the example of a setting of the reading line of phase difference information. It is a figure which shows another example of the setting of the reading line of phase difference information. It is a flowchart explaining the setting of the reading line of phase difference information. It is a flowchart explaining the process following FIG.

  Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration example of an imaging apparatus according to the present embodiment. As an example, an interchangeable lens type camera system will be described. However, the present invention is applicable to an imaging apparatus having a configuration in which a photographing lens unit is incorporated in a camera body unit.

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

  The lens apparatus 100 includes a photographing lens unit 101 including a zoom mechanism, an aperture and shutter 102 that controls the amount of light, and a focus lens 103 that performs focus adjustment. The motor 104 drives the focus lens 103 in accordance with a control command from the lens controller 105. The lens controller 105 includes a CPU (Central Processing Unit), and performs drive control of the movable lens, the diaphragm and shutter 102, and the focus lens 103 in the photographing lens unit 101.

  The main body 200 includes an image sensor 201, photoelectrically converts reflected light from a subject imaged through the lens device 100, and outputs an electrical signal. The imaging device 201 is a CCD (charge coupled device) image sensor or a CMOS (complementary metal oxide semiconductor) image sensor. An A / D (analog / digital) converter 202 acquires the output signal of the image sensor 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 of the image sensor 201 and a non-linear amplification circuit that performs amplification before A / D conversion.

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

  The format conversion unit 205 performs a 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 for example, a random access memory (hereinafter referred to as DRAM) is used. The DRAM functions as a high-speed buffer that temporarily stores image data, or is used as a working memory for image compression or decompression.

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

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

  The 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 an image in accordance with the image display data acquired from the VRAM 212, displays an operation assist display and a camera state, and displays a shooting screen and a distance measurement area (focus detection area) at the time of shooting. To do.

  The operation unit 214 includes an operation member for the user to operate the imaging apparatus. For example, the operation unit 214 is an operation unit such as a menu operation switch for performing a shooting function of the image pickup apparatus, setting for image reproduction, or a touch panel used on the display screen. The shooting mode SW (switch) 215 is an operation switch for the user to select a shooting mode such as a macro mode or a sports mode. The main switch 216 is a switch used when power is supplied to 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 a shooting standby operation such as AF or AE. The second switch 218 is a shooting switch (hereinafter referred to as SW2) that gives a shooting instruction after the user operates SW1.

  An imaging signal acquisition process in this embodiment will be described. The imaging element 201 receives light that has passed through the imaging optical system of the lens apparatus 100, and performs photoelectric conversion to a signal charge corresponding to the amount of incident light by 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 a drive pulse supplied from the timing generator 208 in accordance with a command from the system control unit 209.

  In the present embodiment, an example in which each pixel portion of the image sensor 201 is configured by a pair of photodiodes A and B and one microlens provided in common to the pair of photodiodes A and B will be described. That is, the incident light is divided by the microlens to form a pair of optical images on the pair of photodiodes A and B. The pair of photodiodes A and B outputs a pair of pixel signals used for generating an AF signal described later. A pixel signal output from the photodiode A is an A signal, and a pixel signal output from the photodiode B is a B signal. The phase difference information can be acquired by the 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 acquired.

  In AF using an imaging surface phase difference detection method (so-called imaging surface phase difference AF), a plurality of A signals and a plurality of B signals respectively output from a plurality of pixel units are combined for each signal, thereby generating an AF signal (focus detection). And a pair of image signals as a focus adjustment signal). The AF signal processing unit 204 performs a correlation operation on the acquired pair of image signals, and calculates a phase difference (hereinafter referred to as an image shift amount) that is a shift amount of 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. The distance information from the imaging device to the subject can be acquired using the imaging relational expression of the imaging optical system based on the image shift amount or the defocus amount.

  The configuration of the image sensor 201 will be described with reference to FIGS. FIG. 2 partially shows the pixel array 300 of the image sensor 201. The pixel array 300 has a configuration in which a large number of unit pixels 301 are arranged in a matrix direction. The micro lenses 302 are arranged corresponding to the unit pixels 301. Photodiodes (hereinafter abbreviated as PD) 303 a and 303 b as photoelectric conversion means are arranged below the microlens 302 to constitute a unit pixel 301. The PDs 303a and 303b have a pupil division configuration, and light of two images (hereinafter referred to as an A image and a B image) having different phase differences from the same subject is incident thereon. 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 photoelectric conversion units divided into three or more may be used.

  With reference to FIG. 3, the circuit configuration of the image sensor 201 will be described. 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. The vertical scanning of each pixel is performed by the vertical scanning circuit control unit 304 and the vertical scanning circuit 306, and control for reading out signals from all pixels in units of rows is possible.

  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 the programmed readout setting. The vertical scanning circuit 306 transfers a pixel signal by sending a pulse to each unit pixel 301 in accordance with the readout setting units 305a and 305b.

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

  The pixel signal photoelectrically converted by the unit pixel 301 is output to the vertical output line 308 for each row by the drive signal supplied from the vertical scanning circuit 306. The vertical scanning circuit control unit 304 controls whether the vertical scanning circuit 306 reads a pixel signal in a first driving mode or a second driving mode, which will be described later, when acquiring an output in a specific row. The constant current source 309 is connected to the 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 flowchart for explaining the operation of the imaging apparatus according to this embodiment. The following processing is realized by the CPU of the system control unit 209 executing a predetermined program. In step S301, the AE processing unit 211 acquires the output of the image processing unit 203, performs AE processing, and proceeds to processing in step S302.

  In S302, the system control unit 209 checks the state of the first switch 217 (SW1) and determines 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 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) and determines whether SW1 is ON. If it is determined that SW1 is ON, the process proceeds to S305. If it is determined that SW1 is OFF, the process returns to S301. In S305, an AF process (hereinafter referred to as servo AF) described later is executed. Servo AF is a function that enables imaging while continuing to focus on a moving subject, and is effective when performing focus adjustment on a moving subject. In the present embodiment, the servo AF can be arbitrarily switched by a user operation instruction. Thereafter, in S306, the system control unit 209 checks the state of the second switch 218 (SW2) and determines 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 the process proceeds to S402. In S402, the AF signal processing unit 204 and the system control unit 209 perform focus detection processing, detect the defocus amount and defocus direction, and their reliability, and proceed to S403. Details of the focus detection process will be described later with reference to FIG.

  In step S403, the system control unit 209 compares the reliability of the focus detection result obtained in step S402 with a preset threshold value. This threshold is defined as a reliability threshold 2. When it is determined that the reliability is higher than the reliability threshold 2, the process proceeds to S404, and when the reliability is equal to or less than the reliability threshold 2, the process proceeds to S410 in FIG. When it is determined that the reliability is equal to or less than the reliability threshold value 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 step S404, the system control unit 209 compares the defocus amount detected in step S402 with a preset threshold value. This threshold is defined as Def amount threshold 2. For the Def amount threshold 2, for example, when the defocus amount is less than or equal to the Def amount threshold 2, a value (for example, the focus lens can be controlled within the depth of focus within a predetermined number of times (for example, 3 times) according to the subsequent defocus amount (for example, The amount is 5 times the depth of focus). If it is determined that the defocus amount is equal to or smaller than the Def amount threshold 2, the process proceeds to S405. If it is determined that the defocus amount is greater than the Def amount threshold 2, the process proceeds to S409.

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

  In step S406, the system control unit 209 compares the defocus amount detected in step S402 with a preset threshold value. This threshold is defined as Def amount threshold 1. For example, if the detected defocus amount is equal to or less than the Def amount threshold 1, the Def amount threshold 1 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 less than or equal to the Def amount threshold value 1, the process proceeds to S407, and if it is determined that the defocus amount is greater than the Def amount threshold value 1, the process proceeds to S408.

  In step S407, the system control unit 209 determines that the current focus detection state is an in-focus state, and proceeds to return processing. In step S <b> 408, the system control unit 209 transmits a drive amount control signal corresponding to the defocus amount detected in step S <b> 402 to the lens controller 105 via the lens communication unit 210. The lens controller 105 controls the driving of the motor 104 according to the control signal received from the lens communication unit 210 and drives the focus lens 103. After S408, the process returns to S402.

  In step S409, the system control unit 209 transmits a drive amount control signal corresponding to a predetermined ratio to the defocus amount detected in step S402 to the lens controller 105 via the lens communication unit 210. The predetermined ratio is a ratio that is set so that the drive amount of the focus lens 103 is smaller than the defocus amount, and is set to about 80%, for example. The lens controller 105 controls the driving of the motor 104 according to the control signal received from the lens communication unit 210 and drives the focus lens 103. The driving 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, for example, in a time corresponding to one frame. Thereby, when the detected defocus amount is not accurate, the focus lens 103 can be prevented from being driven beyond the focus position (focus position) where the subject is focused. 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, when the lens drive is completed in the entire movable range of the focus lens 103, that is, it is set as a condition that both the far and near lens ends are detected and returned to the initial position in the drive control of the focus lens 103. The If the non-focus condition is satisfied, the process proceeds to S411. If the non-focus condition is not satisfied, the process proceeds to S412. In step S411, the system control unit 209 determines that the current focus detection state is an out-of-focus state, and then proceeds to return processing.

  In step 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 or near lens end, the process proceeds to S413. If it is determined that the focus lens 103 has not reached the far or near lens end, the process proceeds to S414. move on.

  In step 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 process of step S402 in FIG. In step 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 process of step S402 in FIG. The drive speed of the focus lens 103 is set to the fastest value within the allowable range of the lens drive speed so that the focus position of the subject does not pass when the defocus amount can be detected, for example. The

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

  In step S504, the AF signal processing unit 204 performs filter processing on the signal that has been subjected to the row addition averaging process in the vertical direction in step S503, and extracts a signal component in a predetermined frequency band. In step S505, the AF signal processing unit 204 calculates a correlation amount by performing correlation calculation for phase difference detection using the signal filtered in step S504. In S506, the AF signal processing unit 204 calculates a correlation change amount from the correlation amount calculated in S505. In the next S507, the image shift amount is calculated from the correlation change amount, and the process proceeds to S508. In step S <b> 508, the AF signal processing unit 204 calculates a reliability indicating how reliable the calculated image shift amount is. In S509, after the conversion process for converting the image shift amount into the defocus amount is performed, the focus detection process is terminated and the process proceeds to a return process. 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 illustrating servo AF control in the present embodiment. In S600, the AF operation described in FIGS. 5 and 6 is performed. In step S <b> 601, the system control unit 209 acquires the defocus amount data calculated in step S <b> 600 and stores it in the memory (DRAM) 206. In S602, the focus detection process described in FIG. 7 is performed. The acquired latest defocus amount data is stored in the memory 206.

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

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

  With reference to FIGS. 9 and 10, the setting of the readout row for the phase difference information shown in S501 of FIG. 7 will be described. FIG. 9 and FIG. 10 are diagrams exemplifying rows for reading phase difference information in the AF operation shown in S303 of FIG. 4 and the servo AF shown in S305. In the image examples shown in FIGS. 9 and 10, the readout row of the phase difference information is schematically shown by a solid horizontal line. The system control unit 209 makes the interval between readout rows of phase difference information constant when photographing a stationary body (or when a stationary body is detected). In addition, the system control unit 209 performs setting so that the number of rows from which phase difference information is read is increased when a moving object is imaged (or when a moving object is detected) than when a stationary object is imaged.

  FIG. 9 shows an example of an image for explaining a method of reading phase difference information in the 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 for reading the phase difference information is increased as much as possible, and the rows to be read in the vertical direction are evenly arranged. For example, the interval between read lines is determined by the minimum size of the detectable face area of the subject. The system control unit 209 sets the row interval D so that a horizontal line for reading out phase difference information of one or more rows can be arranged for the minimum face size.

  FIG. 10A shows an example of an 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 located 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 the control for reading the pixel signal in the first drive mode by the vertical scanning circuit 306. When the moving subject is located far away, the servo AF continues the method of reading phase difference information shown in FIG. 10A while focusing on the subject. In the present embodiment, for example, the distance information of the subject is calculated from the focus lens position where the focusing is performed. The phase difference information reading method shown in FIG. 10A continues when the subject is located farther than a distance corresponding to a predetermined threshold magnification (for example, 50 times) related to the focal length of the lens apparatus 100 being used. To do.

  FIG. 10B shows an example of an image for explaining a method of reading phase difference information when distance information of a moving subject is positioned closer to the distance corresponding to the threshold magnification related to 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 apparatus. In this case, since the subject is moving on the near side, it is necessary to read as much phase difference information as possible in order to reduce the ranging error. Further, in order to reduce the power consumption of the imaging apparatus, the row interval D is set so that a signal is read from the minimum necessary area when a moving subject is detected. This setting corresponds to the control for reading the pixel signal in the second drive mode by the vertical scanning circuit 306. In FIG. 10B, read lines are concentrated on the face area of the moving subject and its neighboring area, and the line interval D is narrowed. Thus, by reading out the phase difference information within a limited range in the image, it is possible to read out the phase difference information at high speed while suppressing power consumption, and to realize AF control with high focus detection accuracy.

  11 and 12 are flowcharts for explaining the setting of the number of read rows of phase difference information, that is, the number of read rows to be set. In step 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. The user uses the operation unit 214 to select the one-shot mode when instructing the focus adjustment to focus on the stationary object, and the servo AF mode when instructing the focus adjustment to focus on the moving object. can do. If the system control unit 209 determines that the one-shot mode is set, the process proceeds to S802. If it is determined that the servo AF mode is set, the process proceeds to S806 in FIG.

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

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

  In step S804, the system control unit 209 sets the number X of read rows of the phase difference information to X1. In step S805, the system control unit 209 sets the number X of read rows of the phase difference information to X2. Assume that “X1 <X2”. After S804 and S805, the process proceeds to S813, and the system control unit 209 sets the final set number of rows to the calculated number of rows, that is, X1 or X2. In this case, the readout lines of the phase difference information are arranged at equal intervals over the entire screen. This row arrangement corresponds to the first driving mode by the vertical scanning circuit 306. Thereafter, the readout row setting process is terminated.

  On the other hand, in S806 of FIG. 12, the system control unit 209 calculates the contrast value within the distance measurement 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 value, the process proceeds to S807. If it is determined that the contrast value is less than the threshold value, the process proceeds to S808.

  In step S807, the system control unit 209 sets the number Y of read phase difference information rows to Y1. In step S808, the system control unit 209 sets the number Y of read phase difference information rows to Y2. Assume that “Y1 <Y2”.

  After S807 and S808, the process proceeds to S809, where the system control unit 209 determines whether or not to set a read line for phase difference information for the first time. When setting the first read line, the process proceeds to S810, and when setting the second and subsequent read lines, the process proceeds to S811.

In step S810, the system control unit 209 sets the calculated number of rows, that is, Y1 or Y2, arranges read phase difference information rows at equal intervals in the entire screen, and ends the process. In the present embodiment, the read row numbers 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 determines whether the distance from the imaging device to the subject (subject distance) is equal to or greater than a predetermined threshold, using the defocus amount calculated at the present time. For example, the threshold value is 50f (50 times the focal length f). The subject distance can be calculated from the defocus amount and an imaging relational expression related to the imaging optical system of the lens apparatus. If it is determined in S811 that the subject distance is greater than the predetermined threshold value, the process ends. If it is determined that the subject distance is equal to or smaller than the predetermined threshold value, the process proceeds to S812.

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

In the present embodiment, in a pupil-divided image sensor that can acquire phase difference information, the vertical period related to the readout row is dynamically changed in accordance with the distance information of the subject to perform signal readout suitable for a plurality of functions. . Thereby, phase difference detection with higher accuracy can be performed while suppressing a decrease in the frame rate.
As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to the said embodiment, A various deformation | transformation and change are possible within the range of the summary.

DESCRIPTION OF SYMBOLS 103 Focus lens 105 Lens controller 201 Image pick-up element 204 AF signal processing part 209 System control part 302 Micro lens 303a, 303b Photoelectric conversion part 304 Vertical scanning circuit control part 306 Vertical scanning circuit

Claims (11)

Imaging means having a plurality of pixel units capable of acquiring phase difference information;
Control means for performing control to read out signals from the pixel unit in units of rows,
The image pickup apparatus, wherein the control unit acquires distance information of a subject and performs control to change an interval between read lines of the phase difference information corresponding to the distance information. When the imaging means captures a subject that is a stationary object, the control means uses a constant interval between readout rows of the phase difference information. When the imaging means captures a subject that is a moving object, the control means is based on the distance information. The imaging apparatus according to claim 1, wherein control is performed to dynamically change an interval between readout rows of the phase difference information. The imaging apparatus according to claim 2, wherein the control unit sets a readout row of the phase difference information in a range including a subject area of a moving body. 4. The control unit according to claim 2, wherein the control unit increases the number of readout rows of the phase difference information when imaging a moving object as compared to imaging a stationary object by the imaging unit. 5. The imaging device described. The control means increases the number of readout lines of the phase difference information when a moving subject is detected, more than the number of readout lines of the phase difference information when a moving subject is not detected. The imaging apparatus according to any one of claims 2 to 4, wherein the imaging apparatus is characterized in that: The control means sets the number of readout rows of the phase difference information to the first number when the contrast value of the image in the focus state detection frame is higher than the threshold value, and the contrast value is equal to or less than the threshold value. The imaging apparatus according to any one of claims 1 to 4, wherein the second number of rows larger than the first number of rows is set in some cases. The control means sets the interval of the phase difference information readout row when the distance information of the moving subject is less than or equal to the threshold, and the phase difference information readout row when the subject distance information is greater than the threshold. The imaging apparatus according to claim 2, wherein the imaging apparatus is narrower than the interval. Operating means for instructing focus adjustment to focus on the subject;
A focus adjustment unit that performs focus detection using the phase difference information and performs focus adjustment on the moving subject when the operation unit instructs the focus adjustment to focus on the moving subject. The imaging apparatus according to any one of claims 1 to 7, further comprising: The control unit is characterized in that the interval between the readout rows set in a range including the subject area of the moving object is narrower than the interval between the readout rows set when imaging a subject that is a stationary body. The imaging apparatus according to 3. The pixel unit of the imaging unit includes a microlens and a plurality of photoelectric conversion units corresponding to the microlens, and the plurality of photoelectric conversion units output a plurality of signals having the phase difference information. The imaging device according to any one of claims 1 to 9. A control method that is executed in an imaging apparatus including an imaging unit having a plurality of pixel units capable of acquiring phase difference information and a control unit that performs control to read out signals from the pixel units in units of rows,
The control means acquiring distance information of the subject;
And a step of controlling the control means to change an interval between readout rows of the phase difference information corresponding to the distance information of the subject.

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