Imaging apparatus and control method of the same

Abstract

To suppress deterioration in the accuracy of information, such as a focal point acquired using a signal from an imaging element.SOLUTION: An imaging apparatus 120 includes an imaging element 122 that has a plurality of pixels photoelectrically converting each luminous flux that has passed through mutually different pupil areas in an optical system and in which signal readout from the pixels in a first direction is sequentially performed in a second direction. Detection means 125, 129 detects a phase difference between a pair of detection signals generated by the signals read out of at least a part of the plurality of pixels and acquires information about a focal point or a distance, performs first detection for detecting the phase difference in the first direction and second detection for detecting the phase difference in the second direction, performs first processing for acquiring the information by the first detection or the second detection in a case where shutter speed is longer than a predetermined time, performs second processing for acquiring the information not by the second detection but by the first detection in a case where the shutter speed is shorter than the predetermined time, and sets the predetermined time to be longer as an F-value is larger.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an imaging device that performs focus detection using an imaging surface phase difference detection method.

Background Art

[0002] In the imaging surface phase difference detection method, an imaging element for imaging a subject is used as a focus detection sensor that performs pupil division, and focus detection using the phase difference detection method is performed. Patent Documents 1 and 2 disclose imaging devices that perform focus detection in each of mutually different first and second pupil division directions.

[0003] Patent Document 2 discloses that, in order to ensure focus detection performance and live view display time, when performing high-speed readout from an imaging element, the focus detection signal in the second pupil division direction is thinned out or not generated under conditions such as a high continuous shooting speed, a bright F value, or a bright subject luminance.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Because the second pupil-division direction is different from the first pupil-division direction corresponding to the signal readout direction from the image sensor, the readout time difference in the correlation direction in which the phase difference is detected increases. When the readout time difference in the correlation direction increases, an error due to the time difference is superimposed on the focus detection signal, resulting in a decrease in focus detection accuracy. Conditions under which the degree of decrease in focus detection accuracy increases include when the subject image moves quickly on the image sensor, when the readout speed is slow compared to the shutter speed, and when the F-number is low. With the image sensor of Patent Document 2, it is difficult to suppress the decrease in focus detection accuracy caused by the readout time difference in the correlation direction according to the imaging conditions.

[0006] The present invention provides an imaging device that can suppress a decrease in accuracy of information about focus and the like acquired using a signal from an imaging element. [Means for solving the problem]

[0007] An imaging device according to one aspect of the present invention includes an imaging element in which pixels, each having a plurality of photoelectric conversion units that photoelectrically convert light beams that have passed through different pupil regions of an optical system, are arranged in a first direction, which is the row direction, and a second direction, which is the column direction; a readout means for sequentially reading out signals from the pixels in the imaging element row by row in the second direction; a focus detection means for detecting a first phase difference, which is the phase difference of the focus detection signal in the first direction, and a second phase difference, which is the phase difference of the focus detection signal in the second direction, based on the readout signals; and a focus adjustment means for performing focus control based on the first phase difference or the second phase difference, wherein the focus adjustment means performs a first process of performing first focus control based on the first phase difference when the shutter speed is shorter than a predetermined time, and performs a second process of selecting either the first focus control or second focus control based on the second phase difference when the shutter speed is longer than the predetermined time, and wherein the predetermined time is longer when the F-number of the optical system is set to a second F-number larger than the first F-number than when it is set to the first F-number. According to another aspect of the present invention, an imaging device includes an image sensor having a plurality of pixels that photoelectrically convert each of light beams that have passed through different pupil regions of an optical system, and detection means for detecting a phase difference between a pair of detection signals generated from signals read out from at least some of the plurality of pixels to acquire information about focus or distance. The detection means is capable of performing first detection for detecting the phase difference in a first direction and second detection for detecting the phase difference in a second direction different from the first direction. In a detection region of the image sensor that generates the pair of detection signals, if the readout time in the first direction is shorter than the readout time in the second direction, the information is acquired by the first detection, and if the readout time in the second direction is shorter than the readout time in the first direction, the information is acquired by the second detection.

[0008] Another aspect of the present invention is a control method for an imaging device having an imaging element in which pixels, each having a plurality of photoelectric conversion units that photoelectrically convert light beams that have passed through different pupil regions of the optical system, are arranged in a first direction, which is the row direction, and a second direction, which is the column direction.The control method includes: a readout process for sequentially reading out signals from the pixels in the imaging element row by row in the second direction; a focus detection process for detecting a first phase difference, which is the phase difference of the focus detection signal in the first direction, and a second phase difference, which is the phase difference of the focus detection signal in the second direction, based on the readout signals; and a focus adjustment process for performing focus control based on the first phase difference or the second phase difference.In the focus adjustment process, if the shutter speed is shorter than a predetermined time, a first process is performed to perform first focus control based on the first phase difference, and if the shutter speed is longer than the predetermined time, a second process is performed to select either the first focus control or second focus control based on the second phase difference and perform focus control.The predetermined time is longer when the F-number of the optical system is set to a second F-number larger than the first F-number than when it is set to the first F-number.

[0009] Another aspect of the present invention provides a control method for an imaging device having an imaging element in which pixels, each having a plurality of photoelectric conversion units that photoelectrically convert light beams that have passed through different pupil regions of the optical system, are arranged in a first direction, which is the row direction, and a second direction, which is the column direction. The control method includes: a readout process for sequentially reading out signals from the pixels in the imaging element row by row in the second direction; a focus detection process for detecting a first phase difference, which is the phase difference of the focus detection signal in the first direction, and a second phase difference, which is the phase difference of the focus detection signal in the second direction, based on the readout signals; and a focus adjustment process for performing focus control based on the detection result of the focus detection process. In the focus adjustment process, if the shutter speed is shorter than a predetermined time, focus control is performed based on the first phase difference; and if the shutter speed is longer than the predetermined time, focus control is performed based on the first phase difference and the second phase difference, and the predetermined time is longer when the F-number of the optical system is set to a second F-number larger than the first F-number than when it is set to the first F-number. Note that a program for causing a computer of an imaging device to execute processing according to each of the above control methods also constitutes another aspect of the present invention. [Effects of the Invention]

[0010] According to the present invention, it is possible to suppress a decrease in accuracy of information relating to focus or distance obtained using a signal from an imaging element. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing the configuration of an imaging system according to a first embodiment. [Figure 2] FIG. 2 is a diagram showing a pixel array of an image sensor in the first embodiment. [Figure 3] 3A and 3B are a plan view and a cross-sectional view of a pixel in the first embodiment. [Figure 4] FIG. 3 is a diagram showing pupil division in the first embodiment. [Figure 5] FIG. 4 is another diagram showing pupil division in the first embodiment. [Figure 6] 5 is a graph showing the relationship between the image shift amount and the defocus amount in the first embodiment. [Figure 7] 5A and 5B are diagrams showing the relationship between the focus detection frame, the correlation direction of the focus detection signal, and the signal readout direction in the first embodiment. [Figure 8] 3 is a flowchart showing a process in the first embodiment. [Figure 9] FIG. 4 is a diagram showing a shutter speed threshold value in the first embodiment. [Figure 10] 10 is a flowchart showing a process in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. [Example]

[0013] 1 shows the configuration of an imaging system 10 including an imaging device (hereinafter referred to as a camera body) 120 according to a first embodiment. A lens unit (interchangeable lens) 100 is detachably attached to the camera body 120, which is a digital camera, via a mount M indicated by a dotted line in the figure. The imaging device may also be one in which an imaging optical system is integrally provided. Furthermore, the imaging device is not limited to a digital camera, and may be another imaging device such as a video camera.

[0014] The lens unit 100 has an imaging optical system that includes a first lens group 101, an aperture 102, a second lens group 103, and a focus lens group (hereinafter simply referred to as focus lens) 104, as well as a drive / control system. The imaging optical system captures light from a subject and forms an image of the subject.

[0015] The first lens group 101 is disposed closest to the object and is held movably in the direction of the optical axis OA. The diaphragm 102 adjusts the amount of light by changing its aperture diameter, and functions as a shutter for adjusting the exposure time when capturing a still image. The diaphragm 102 and the second lens group 103 are movable together in the direction of the optical axis, and perform zooming by moving in conjunction with the first lens group 101. The focus lens 104 is movable in the direction of the optical axis to perform focusing. Autofocus control (AF) is performed by controlling the position of the focus lens 104 in accordance with the focus detection results described below.

[0016] The drive / control system includes a zoom actuator 111, an aperture actuator 112, a focus actuator 113, a zoom drive circuit 114, an aperture drive circuit 115, a focus drive circuit 116, a lens MPU 117, and a lens memory 118. The zoom drive circuit 114 drives the zoom actuator 111 during zooming to move the first lens group 101 and the third lens group 103 in the optical axis direction. The aperture drive circuit 115 drives the aperture actuator 112 to operate the aperture 102, thereby performing aperture operation and shutter operation.

[0017] During focusing, the focus drive circuit 116 drives the focus actuator 113 to move the focus lens 104 in the optical axis direction. The focus drive circuit 116 functions as a position detection unit that detects the current position of the focus lens 104 (hereinafter referred to as the focus position) through the focus actuator 113.

[0018] The lens MPU 117 is a computer that executes calculations and processing related to the lens unit 100, and controls the zoom drive circuit 114, aperture drive circuit 115, and focus drive circuit 116. The lens MPU 117 is also communicatively connected to a camera MPU 125 in the camera body 120 via a communication terminal on the mount M, and exchanges commands and data. For example, the lens MPU 117 notifies the camera MPU 125 of lens information in response to a request from the camera MPU 125. This lens information includes information such as the focus position, the position and diameter of the exit pupil of the imaging optical system in the optical axis direction, and the position and diameter of the lens frame that limits the luminous flux of the exit pupil in the optical axis direction.

[0019] The exit pupil of the imaging optical system is a virtual image formed by a lens located closer to the image side than the aperture stop 102. Light from a point on an object forms an image on the imaging surface of the image sensor 122 (described later) as a conical light beam with the exit pupil as its base. In other words, the light beam received by the image sensor 122 is determined by the exit pupil. The position of the exit pupil is the intersection of the chief ray of off-axis exit light and the optical axis OA. Particularly at peripheral image heights, the light beam passing through the exit pupil is limited by an upper line and a lower line according to the imaging optical system. In this embodiment, the limitation of the light beam passing through the exit pupil is called lens frame vignetting. Normally, the degree of lens frame vignetting differs depending on the lens unit (imaging optical system).

[0020] Furthermore, the lens MPU 117 controls the zoom drive circuit 114, the aperture drive circuit 115, and the focus drive circuit 116 in response to requests from the camera MPU 125. The lens memory 118 stores optical information necessary for AF. The camera MPU 125 controls the operation of the lens unit 100 by executing programs stored in the built-in nonvolatile memory and the lens memory 118.

[0021] The camera body 120 has an optical low-pass filter 121, an image sensor 122, an image processing circuit 124, and a drive / control system. The optical low-pass filter 121 is provided to reduce false colors and moiré. The image sensor 122 is composed of a CMOS sensor and its peripheral circuits, and photoelectrically converts a subject image (optical image) formed by the imaging optical system, outputting an image signal and a pair of focus detection signals (two image signals). The image sensor 122 has multiple image pixels arranged in a horizontal direction of m pixels and a vertical direction of n pixels (m and n are integers of 2 or greater). Each image pixel includes a pair of focus detection pixels, as described below, and has a pupil-splitting function that enables focus detection using a phase difference detection method.

[0022] The drive / control system includes an image sensor drive circuit 123, an image processing circuit 124, a camera MPU 125, a display 126, an operation switch (SW) 127, a memory 128, a phase difference AF unit 129, a flicker detection unit 130, an AE unit 131, and a white balance (WB) adjustment unit 132. The image sensor drive circuit 123 controls charge accumulation and signal readout in the image sensor 122, and performs A / D conversion on the image signal and the paired focus detection signal output from the image sensor 122, and outputs them to the image processing unit 124 and the camera MPU 125. The image processing circuit 124 performs image processing such as gamma conversion, color interpolation, and compression encoding on the digital image signal from the image sensor drive circuit 123 to generate image data.

[0023] The camera MPU (control means) 125 is a computer that executes calculations and processing related to the camera body 120, and controls the image sensor drive circuit 123, image processing circuit 124, display 126, phase difference AF unit 129, flicker detection unit 130, AE unit 131, and WB adjustment unit 132. The camera MPU 125 is also communicatively connected to the lens MPU 117 via a communication terminal of the mount M, and exchanges commands and data with the lens MPU 117. For example, the camera MPU 125 requests lens information and optical information from the lens MPU 117, and requests the driving of the lenses 101 and 104 and the aperture 102. The camera MPU 125 receives the lens information and optical information transmitted from the lens MPU 117.

[0024] The camera MPU 125 has built-in ROM 125a for storing various programs, RAM 125b for storing variables, and EEPROM 125c for storing various parameters. The camera MPU 125 executes various processes including AF processing, which will be described later, in accordance with the programs stored in ROM 125a. The camera MPU 125 generates two-image data from a pair of digital focus detection signals from the image sensor drive circuit 123 and outputs the data to a phase-difference AF unit 129.

[0025] The display 126 is configured with an LCD or the like, and displays information about the imaging mode, a preview image before imaging, a confirmation image after imaging, the focus state, etc. The operation switches 127 include a power switch, a release (imaging instruction) switch, a zoom switch, an imaging mode selection switch, etc. The memory 128 is a flash memory that is detachable from the camera body 120, and stores images for recording obtained by imaging.

[0026] The phase-difference AF unit 129 performs phase-difference AF using the phase-difference image data generated by the camera MPU 125. The image sensor 122 photoelectrically converts a pair of optical images formed by light beams that have passed through a pair of different pupil regions of the exit pupil of the imaging optical system, and outputs a pair of focus detection signals. The phase-difference AF unit 129 performs a correlation operation on the two image data generated by the camera MPU 125 to calculate the amount of image shift, which is the phase difference between them, and calculates (acquires) a defocus amount as information related to the focus from the image shift amount. The phase-difference AF unit 129 also calculates the drive amount of the focus lens 104 according to the calculated defocus amount. In this way, the phase-difference AF section 129 performs image-plane phase-difference AF using the output of the image sensor 122, without using an AF sensor dedicated to focus detection. In this embodiment, the phase-difference AF section 129 has an acquisition section 129a and a calculation section 129b. The operation of the phase-difference AF section 129 having the acquisition section 129a and the calculation section 129b will be described later. Note that at least one of the acquisition section 129a and the calculation section 129b may be provided in the camera MPU 125. The camera MPU 125 and the phase-difference AF section 129 form a detection means.

[0027] The flicker detection unit 130 detects flicker from the image data for flicker detection obtained from the image processing circuit 124. The camera MPU 125 performs control to adjust the amount of exposure so as to reduce the influence of the detected flicker.

[0028] The AE unit 131 performs exposure control (AE) by performing photometry using image data for AE obtained from the image processing circuit 124. Specifically, the AE unit 131 acquires brightness information of the image data for AE, and calculates the aperture value, shutter speed (shutter time), and ISO sensitivity as imaging conditions from the difference between the exposure amount obtained from this brightness information and a preset exposure amount. Then, AE is performed by controlling the aperture value, shutter speed, and ISO sensitivity to the calculated values.

[0029] The WB adjustment unit 132 calculates the WB of the image data for WB adjustment obtained from the image processing circuit 124, and performs WB adjustment by adjusting the weights of RGB colors according to the difference between the calculated WB and a predetermined appropriate WB.

[0030] Furthermore, the camera MPU 125 can perform processing to detect subjects such as a human face in the image data obtained from the image processing circuit 124. The camera MPU 125 can select the image height range for performing phase difference AF, AE, and WB adjustment according to the position and size of the detected subject.

[0031] (Regarding the image sensor 122) FIG. 2 shows the pixel arrangement on the imaging surface of the image sensor 122, which serves as a two-dimensional CMOS sensor in this embodiment. Here, the imaging pixel arrangement is shown as a 4-column by 4-row area. A pixel group 200, which includes 2 columns by 2 rows of imaging pixels, includes a pixel 200R located in the upper left and having a spectral sensitivity of R (red), pixels 200Ga and 200Gb located in the upper right and lower left and having a spectral sensitivity of G (green), and a pixel 200B located in the lower right and having a spectral sensitivity of B (blue). Each imaging pixel is composed of a first focus detection pixel 201 and a second focus detection pixel 202. In the pixels 200R, 200Ga, and 200B, the first focus detection pixel 201 and the second focus detection pixel 202 are arranged horizontally, while in the pixel 200Gb, the first focus detection pixel 201 and the second focus detection pixel 202 are arranged vertically.

[0032] Fig. 3(a) shows pixel 200Ga as viewed from the incident side (+z side) of the image sensor 122, and Fig. 3(b) shows the pixel structure when the aa cross section of pixel 200Ga in Fig. 3(a) is viewed from the -y side. In pixel 200Ga, a microlens 305 for collecting incident light is formed on the incident side, and photoelectric conversion units 301 and 302 that are divided into two in the x direction are formed. The photoelectric conversion units 301 and 302 correspond to the first focus detection pixel 201 and the second focus detection pixel 202, respectively.

[0033] The photoelectric conversion units 301 and 302 may be pin structure photodiodes with an intrinsic layer sandwiched between p-type and n-type layers, or may be pn junction photodiodes without the intrinsic layer. A color filter 306 is formed between the microlens 305 and the photoelectric conversion units 301 and 302. The spectral transmittance of the color filter may be different for each focus detection pixel, or the color filter may be omitted.

[0034] Two light beams incident on pixel 200Ga from the paired pupil regions are each collected by microlens 305, dispersed by color filter 306, and then received by photoelectric conversion units 301 and 302. In each photoelectric conversion unit, electrons and holes are generated in pairs according to the amount of received light, and after being separated by a depletion layer, the negatively charged electrons are accumulated in the n-type layer. Meanwhile, the holes are ejected to the outside of image sensor 122 through a p-type layer connected to a constant voltage source (not shown). The electrons accumulated in the n-type layer of each photoelectric conversion unit are transferred to a capacitance unit (FD) via a transfer gate and converted into a voltage signal.

[0035] FIG. 4 shows the relationship between the pixel structure shown in FIGS. 3(a) and 3(b) and pupil division. The lower part of FIG. 4 shows the pixel structure when the aa cross section in FIG. 3(a) is viewed from the +y side, and the upper part shows the pupil plane at pupil distance DS. Note that in FIG. 4, the x-axis and y-axis of the pixel structure are inverted relative to FIG. 3(b) to correspond to the coordinate axes of the pupil plane. The pupil plane corresponds to the entrance pupil position of the image sensor 122. In this embodiment, the microlens position in each pixel is offset (shrunk) from the center of the image sensor 122, so that the entrance pupils of each pixel overlap each other to form the entrance pupil of a single image sensor 122. The pupil distance DS is the distance between the pupil plane and the image sensor, and will be referred to as the sensor pupil distance in the following description.

[0036] As shown in FIG. 4, the first pupil region 501 of the first focus detection pixel 201 is in a roughly conjugate relationship with the light receiving surface of the photoelectric conversion unit 301, whose center of gravity is decentered in the -x direction, via a microlens. The first pupil region 501 is a pupil region through which a light beam that can be received by the first focus detection pixel 201 passes. The center of gravity of the first pupil region 501 is decentered on the +X side on the pupil plane. Furthermore, the second pupil region 502 of the second focus detection pixel 202 is in a roughly conjugate relationship with the light receiving surface of the photoelectric conversion unit 302, whose center of gravity is decentered in the +x direction, via a microlens. The second pupil region 502 is a pupil region through which a light beam that can be received by the second focus detection pixel 202 passes. The center of gravity of the second pupil region 502 is decentered on the -X side on the pupil plane. The pupil region 500 is a pupil region through which light beams that can be received by the entire pixel 200G, which is a combination of the photoelectric conversion unit 301 and the photoelectric conversion unit 302 (the first focus detection pixel 201 and the second focus detection pixel 202), pass.

[0037] As shown in FIG. 5, light beams that enter the imaging optical system from the subject (the vertical line on the left side of the figure) and pass through the first pupil region 501 and the second pupil region 502 are incident on each imaging pixel at different angles and are received by the photoelectric conversion units 301 and 302. Pixels 200R, 200Ga, and 200B perform pupil division in the horizontal direction, while pixel 200Gb performs pupil division in the vertical direction. Each imaging pixel, which has a first focus detection pixel and a second focus detection pixel, receives light beams that pass through the first pupil region 501 and the second pupil region 502. A pair of focus detection signals is generated by combining the output signals of the first focus detection pixel 201 and the second focus detection pixel 202 of the multiple imaging pixels. Furthermore, an imaging signal with a resolution of the number of effective pixels N (= m × n) is generated by adding the output signals of the first focus detection pixel 201 and the second focus detection pixel 202 of the multiple imaging pixels. Note that one of the pair of focus detection signals may be subtracted from the imaging signal to generate the other focus detection signal.

[0038] In addition, in this embodiment, a first and a second focus detection pixel are provided for each of all imaging pixels of the image sensor 122, but two imaging pixels may be used as the first and second focus detection pixels, or first and second focus detection pixels may be provided for some imaging pixels.

[0039] (Relationship between defocus amount and image shift amount) 6 shows the relationship between the defocus amount and the image shift amount of two image data. 800 denotes the imaging plane of the image sensor 122, and the pupil plane of the image sensor 122 is divided into a first pupil region 501 and a second pupil region 502. The defocus amount d is defined as |d|, where the distance from the imaging position of the subject image to the imaging plane 800 is a negative sign (d<0) for a front-focus state in which the imaging position is located on the subject side of the imaging plane, and a positive sign (d>0) for a back-focus state in which the imaging position is located on the opposite side of the subject from the imaging plane 800. The in-focus state in which the imaging position is located on the imaging plane 800 is d=0.

[0040] 6, subject 801 shows a focused state (d=0), and subject 802 shows a front-focused state (d<0). The front-focused state (d<0) and the back-focused state (d>0) are combined to form a defocused state (|d|>0).

[0041] In a front-focus state, light beams from the subject 802 that pass through the first pupil region 501 and the second pupil region 502 are focused once and then spread to widths Γ1 and Γ2 centered at the positions G1 and G2 of the centers of gravity of the light beams, forming blurred optical images on the imaging plane 800. These blurred images are received by the first focus detection pixel 201 and the second focus detection pixel 202 in each imaging pixel on the imaging plane 800, which generate a pair of focus detection signals, a first focus detection signal and a second focus detection signal. The first focus detection signal and the second focus detection signal are recorded as blurred images of the subject 802 at the positions G1 and G2 of the centers of gravity on the imaging plane 800, with the blur widths Γ1 and Γ2 spreading across them. The blur widths Γ1 and Γ2 increase approximately in proportion to an increase in the magnitude of the defocus amount d, |d|. Similarly, the magnitude |p| of the image shift amount p (= the difference G1-G2 in the center of gravity positions of the light beams) between the first focus detection signal and the second focus detection signal also increases roughly in proportion to the increase in the magnitude |d| of the defocus amount d. The same is true in the back-focus state (d>0), although the direction of the image shift between the first focus detection signal and the second focus detection signal is opposite to that in the front-focus state.

[0042] In this embodiment, the difference in the centers of gravity of the incident angle distributions in the first pupil region 501 and the second pupil region 502 is referred to as the base line length. The relationship between the defocus amount d and the image shift amount p on the imaging plane 800 is roughly similar to the relationship between the base line length and the sensor pupil distance. Because the magnitude of the image shift amount between the first focus detection signal and the second focus detection signal increases as the magnitude of the defocus amount d increases, the phase difference AF section 129 converts the image shift amount into a defocus amount using a conversion coefficient calculated based on the base line length, based on this relationship.

[0043] In the following description, calculating the defocus amount using a pair of focus detection signals from focus detection pixels that divide the pupil horizontally, such as pixel 200Ga, is referred to as horizontal eye focus detection (first detection). Calculating the defocus amount using a pair of focus detection signals from focus detection pixels that divide the pupil vertically, such as pixel 200b, is referred to as vertical eye focus detection (second detection).

[0044] (Relationship between baseline length and focus detection accuracy) The shorter the base line length, the lower the focus detection accuracy. The base line length is the difference (distance) between the centers of gravity of the incident angle distribution of the light receiving sensitivity in the first pupil region 501 and the second pupil region 502 on the pupil plane of the image sensor 122. In image plane phase difference AF, the calculated image shift amount is converted into a defocus amount by multiplying it by a gain serving as a conversion coefficient. In this case, if the image shift amount is small, a larger gain must be multiplied. Since the base line length and the image shift amount are roughly proportional to each other, the shorter the base line length, the smaller the image shift amount and the larger the gain must be multiplied. The larger the gain multiplied, the more likely it is that errors contained in the image shift amount will be magnified in the defocus amount, and so the shorter the base line length, the lower the focus detection accuracy.

[0045] (Causes of reduced baseline length) The light beam received by the image sensor 122 is determined by the exit pupil of the imaging optical system. Therefore, the shape of the exit pupil cuts off the incident angle distribution of light sensitivity on the pupil plane, and the baseline length, which is the difference in the center of gravity of the incident angle distribution, is determined. The baseline length depends on the aperture; the smaller the aperture, the more the light beam passing through the exit pupil is narrowed, resulting in a shorter baseline length. Furthermore, the baseline length at peripheral image heights is generally shorter than the baseline length at central image heights. If the position of the exit pupil of the imaging optical system is misaligned with the position of the pupil of the image sensor 122, the position at which the incident angle distribution of light sensitivity on the pupil plane is cut off by the exit pupil shifts as the image height increases, resulting in a shorter baseline length. Furthermore, the possibility of vignetting from the lens frame at high image heights also contributes to a shorter baseline length.

[0046] (Deterioration of focus detection accuracy due to readout time differences in the correlation direction) In this embodiment, a focus detection frame (detection area) is set on the imaging surface as an area where focus detection is performed, and focus detection is performed using a pair of focus detection signals generated from signals from pixels within the focus detection frame.

[0047] FIG. 7 shows the relationship between a focus detection frame 700, a correlation direction in which correlation calculations are performed on paired focus detection signals, and a signal readout direction from the image sensor 122. In this embodiment, signals are read out sequentially row by row from multiple pixel rows of the image sensor 122 in a direction 703 from top to bottom. As a result, the readout time in the correlation direction (second direction) 702 for vertical eye focus detection within the focus detection frame 700 is longer than the readout time in the correlation direction (first direction) 701 for horizontal eye focus detection. In the correlation direction 702 for vertical eye focus detection within the focus detection frame 700, the difference in signal readout time for each row is accumulated as a readout time difference. As a result, the readout time difference in the correlation direction 702 is greater than the readout time difference in the correlation direction (first direction) 701 for horizontal eye focus detection. When the readout time difference in the correlation direction becomes large, the difference due to the readout time difference is superimposed on the original pair of focus detection signals, making it impossible to obtain a correct image shift amount and reducing focus detection accuracy. This type of reduction in focus detection accuracy is likely to be particularly noticeable when the subject is moving.

[0048] In this embodiment, settings such as the number of pixels added in the horizontal and vertical directions and the number of rows thinned out when reading signals from the image sensor 122 can be controlled for each readout mode, depending on the balance between power consumption and focus detection accuracy. For example, in an imaging mode that requires high-speed signal readout and increases the power load, such as when capturing high-frame-rate video, pixel addition and vertical row thinning are performed within the image sensor 122 to reduce the power load. On the other hand, when capturing still images in a dark environment, signals are read out without addition and row thinning to improve the S / N ratio and focus detection accuracy. Signal readout without addition and row thinning requires higher power and is slower than signal readout with addition and row thinning.

[0049] If the signal is thinned out in rows during vertical eye focus detection, the signal is lost in the correlation direction, resulting in reduced focus detection accuracy. Therefore, in this embodiment, vertical eye focus detection is performed only when the signal is read out without thinning out rows. More specifically, the system switches between a first readout mode with addition and no thinning out rows at normal brightness (first brightness state) and a second readout mode with no addition and no thinning out rows at low brightness (second brightness state) that is lower than normal brightness.

[0050] The following three cases can be cited as cases in which the focus detection accuracy decreases significantly due to the readout time difference in the correlation direction.

[0051] First, this occurs when the readout time difference in the correlation direction within the focus detection frame is large relative to the shutter speed, which includes the time from the start of charge accumulation in the image sensor 122 to the generation of the focus detection signal. The slower the readout speed or the shorter the shutter speed, the greater the decrease in focus detection accuracy.

[0052] The second problem occurs when the base line length is short. The shorter the base line length, the larger the conversion coefficient for converting the image shift amount into the defocus amount, which results in the image shift amount error being magnified in the defocus amount, resulting in a significant decrease in focus detection accuracy. The base line length becomes short when focus detection is performed with a small aperture, when focus detection is performed at a high image height on the imaging plane, when there is significant vignetting of the lens frame at the exit pupil of the imaging optical system, and when there is a large difference between the exit pupil distance of the imaging optical system and the sensor pupil distance.

[0053] The third case is when the horizontal movement speed of the subject image on the imaging surface is high, such as when the subject moves quickly as a moving object, or when the subject image and the imaging surface move relatively quickly due to camera shake, such as camera shake, during super-telephoto photography.

[0054] (Issues and solutions when performing focus detection in two directions) As described above, in this embodiment, focus detection is performed in each of two directions (horizontal and vertical) within the focus detection frame, but only one focus detection result (defocus amount) is used to move the focus lens 104. One method is to select the most appropriate focus detection result from the focus detection results in the two directions each time, but if a focus detection result with reduced focus detection accuracy due to a readout time difference in the correlation direction is selected, high-precision AF cannot be performed.

[0055] For this reason, in this embodiment, the decrease in AF accuracy is suppressed by not using the results of focus detection in the direction in which the decrease in focus detection accuracy due to the readout time difference in the correlation direction is greater than the results of focus detection in the two directions.

[0056] The flowchart in Figure 8 shows the process (control method) executed by the camera MPU 125 according to a program. Here, as mentioned above, it is assumed that signals are read out sequentially from the image sensor 122 row by row, from top to bottom. Therefore, the readout time difference occurring in the correlation direction during vertical eye focus detection within the focus detection frame is larger than the readout time difference occurring in the correlation direction during horizontal eye focus detection, resulting in reduced focus detection accuracy during vertical eye focus detection. Furthermore, it is assumed that either AF (and AE) is performed at a predetermined cycle for a subject image moving on the imaging surface, or continuous still image capture is repeated, i.e., continuous shooting is performed. During continuous shooting, AF (and AE) is performed for each image capture. In the following explanation, "S" stands for step.

[0057] First, in S800, the camera MPU 125 acquires information on the shutter speed, readout mode, F-number, and horizontal movement speed of the subject image on the imaging surface (hereinafter referred to as horizontal subject speed).

[0058] Next, in S801, the camera MPU 125 sets a shutter speed threshold as a predetermined time. The shutter speed threshold is the longest shutter speed that allows for a decrease in focus detection accuracy due to a readout time difference in the correlation direction in vertical eye focus detection, and is set for each readout mode. Specifically, the camera MPU 125 sets the shutter speed threshold so that the longer the readout time difference in the correlation direction relative to the shutter speed in the focus detection frame, the longer the shutter speed. More specifically, the second readout mode, which does not perform addition and does not perform line thinning, has a slower readout speed than the first readout mode, which performs addition and does not perform line thinning. Therefore, the camera MPU 125 sets the shutter speed threshold in the second readout mode to a longer shutter speed than the shutter speed threshold in the first readout mode.

[0059] The camera MPU 125 also sets the shutter speed threshold so that the larger the F-number, the longer the exposure time. That is, the larger the conversion coefficient from the image shift amount to the defocus amount in the focus detection frame, the longer the exposure time. Figure 9 shows the shutter speed threshold that is set to a longer exposure time as the F-number (Fno) increases.

[0060] In this embodiment, an F-number is acquired as one of the indices of the conversion coefficient from the image shift amount to the defocus amount, and the shutter speed threshold is set according to the F-number. However, the shutter speed threshold may be set not only according to the F-number but also according to the base length of the focus detection frame, the image height at which focus detection is performed, or the relationship between the exit pupil distance and the sensor pupil distance. In this case, the shutter speed threshold is set to a longer exposure time as the base length becomes shorter, the conversion coefficient used to convert the image shift amount to the defocus amount becomes larger, the image height at which focus detection is performed becomes higher, and the distance between the exit pupil distance and the sensor pupil distance becomes greater. Furthermore, the shutter speed threshold may be set for each imaging optical system (lens unit 100) according to lens frame vignetting. In this case, the shutter speed threshold is set to a longer exposure time as the imaging optical system experiences greater lens frame vignetting.

[0061] Furthermore, the camera MPU 125 sets the shutter speed threshold so that the faster the horizontal subject velocity on the imaging plane, the longer the shutter speed. When a subject moves relative to a fixed imaging system 10, even if the subject distance L and horizontal subject velocity V are the same, the longer the focal length f of the imaging optical system, the smaller the imaging magnification and the larger the horizontal subject velocity V' on the imaging plane, as shown in the following equation (1).

[0062] V′=V / imaging magnification=V / (L / f) (1) Furthermore, when a stationary subject is subject to camera shake or other camera shake that causes the subject image to move horizontally on the imaging surface (i.e., image blur), the relationship between the amount of image blur R on the imaging surface at a camera shake angle θ and the focal length f is expressed by the following equation (2):

[0063] R=f tan(θ) (2) The horizontal subject velocity R' on the imaging plane is expressed by the following equation (3) using the angular velocity θ', and becomes larger as the focal length f becomes longer.

[0064] R′=f / cos 2 (θ) θ' (3) Therefore, the shutter speed threshold may be set according to the focal length of the imaging optical system, in which case the shutter speed threshold is set so that the longer the focal length, the longer the shutter speed.

[0065] The shutter speed threshold may be stored in advance as table data in the internal memory of the camera MPU 125, and may be read out from the table data and set in accordance with the information acquired in S800.

[0066] In step S802, the camera MPU 125 starts AF or continuous shooting in response to the operation of the release switch, and proceeds to S803 to determine whether the shutter speed is longer than the shutter speed threshold set in S801. If the shutter speed is longer than the shutter speed threshold, the camera MPU 125 performs the process of S804, and if the shutter speed is the same as or shorter than the shutter speed threshold, the camera MPU 125 performs the process of S805.

[0067] In S804, the camera MPU 125 selects either the focus detection result obtained by side-eye focus detection (hereinafter referred to as side-eye detection result) or the focus detection result obtained by vertical-eye focus detection (hereinafter referred to as vertical-eye detection result). FIG. 9 shows a region where the shutter speed is longer than the shutter speed threshold and the side-eye detection result or the vertical-eye detection result can be selected as the side-eye / vertical-eye selection region. Next, in S806, the camera MPU 125 selects one of the side-eye detection result or the vertical-eye detection result as the focus detection result to be used and performs a process (first process) to perform AF based on the selected focus detection result. Specifically, the reliability of the side-eye detection result and the vertical-eye detection result are determined based on the degree of variation in each of the side-eye detection result and the vertical-eye detection result, and the focus detection result with the higher reliability is selected. Alternatively, the edge components of the subject image may be detected and the focus detection result may be selected based on the edge direction. For example, the side-eye detection result may be selected for a subject image with a large vertical edge component, and the vertical-eye detection result may be selected for a subject image with a large horizontal edge component.

[0068] On the other hand, in S805, the camera MPU 125 allows only the side-eye detection result to be selected. Figure 9 shows the region where the shutter speed is equal to or less than the shutter speed threshold and where only the side-eye detection result can be selected (the vertical eye detection result cannot be selected) as the side-eye selection region. Next, in S807, the camera MPU 125 selects only the side-eye detection result as the focus detection result to be used, and performs a process (second process) to perform AF using the selected focus detection result. As a result, at shutter speeds where a decrease in the accuracy of the vertical eye detection result is unacceptable, the vertical eye detection result is not selected, and AF is performed based on the side-eye detection result, thereby suppressing a decrease in AF accuracy.

[0069] After this, during AF or continuous shooting, the camera MPU 125 continues the processing method set in S804 or S805 at the start of AF or continuous shooting (either side-eye detection result or vertical eye detection result can be selected, or only side-eye detection result can be selected) until AF or continuous shooting ends in S808. This maintains the continuity of focus detection results even if the shutter speed changes relative to the shutter speed threshold due to changes in the brightness of the subject during AF or continuous shooting. For example, if the vertical eye detection result is selected for a subject image with many horizontal edge components, and the subject becomes brighter, causing the shutter speed to become shorter relative to the shutter speed threshold and enter the side-eye selection area, the vertical eye detection result can continue to be selected, thereby maintaining the continuity of detection results. [Example]

[0070] 10 shows a process (control method) executed by the camera MPU 125 in Example 2. In Example 1, a case where signals are read out sequentially row by row from the top row to the bottom row from a plurality of pixel rows of the image sensor 122 is described. In contrast, Example 2 describes a case where a user can select between a readout mode in which signals are read out sequentially row by row from the image sensor 122 and a readout mode in which signals are read out sequentially column by column. The configurations of the camera body 120 and the lens unit 100 are the same as those shown in FIG. 1 in Example 1, and components in Example 2 that are common to Example 1 are denoted by the same reference numerals as in Example 1.

[0071] First, in S1000, the camera MPU 125 acquires the readout time in the correlation direction (first direction) of horizontal eye focus detection and the readout time in the correlation direction (second direction) of vertical eye focus detection. At this time, instead of the actual readout times, information indicating which readout time is longer (shorter) may be acquired. Also, it may acquire whether the readout mode performing row-by-row sequential readout or column-by-column sequential readout is selected, and acquire the relationship between the readout times in each correlation direction.

[0072] Next, in S1001, the camera MPU 125, which has started AF or continuous shooting in response to operation of the release switch, proceeds to S1002 and compares the readout time in the correlation direction of side-eye focus detection with the readout time in the correlation direction of vertical-eye focus detection. If the readout time in the correlation direction of side-eye focus detection is shorter than the readout time in the correlation direction of vertical-eye focus detection, the camera MPU 125 proceeds to S1003 and selects the side-eye detection result as the focus detection result to use. On the other hand, if the readout time in the correlation direction of vertical-eye focus detection is shorter than the readout time in the correlation direction of side-eye focus detection, the camera MPU 125 proceeds to S1004 and selects the vertical-eye detection result as the focus detection result to use.

[0073] After this, during AF or continuous shooting, the camera MPU 125 continues focus detection (sideways or vertical focus detection) that obtains the focus detection result selected in S1003 or S1004 at the start of AF or continuous shooting until AF or continuous shooting ends in S1005. This maintains the continuity of focus detection results during AF or continuous shooting.

[0074] In the above embodiments, the case where information about the focus (defocus amount) is obtained from the phase difference between a pair of detection signals and AF is performed using that information has been described. However, information about the distance may be obtained from the phase difference and that information may be used to create a distance map, detect a subject, or perform other processing.

[0075] The above embodiment includes the following configurations.

[0076] (Configuration 1) an image sensor having a plurality of pixels that photoelectrically convert each of light beams that have passed through different pupil regions of an optical system, and in which signals are read out from the pixels in a first direction sequentially in a second direction; a detection means for detecting a phase difference between a pair of detection signals generated by signals read out from at least some of the plurality of pixels, thereby obtaining information about focus or distance; The detection means a first detection for detecting the phase difference in the first direction and a second detection for detecting the phase difference in the second direction can be performed; performing a first process of acquiring the information by either the first or second detection when a shutter speed including a time when the pair of detection signals is generated is longer than a predetermined time; If the shutter speed is shorter than the predetermined time, a second process is performed to acquire the information by the first detection without relying on the second detection; The imaging device is characterized in that the predetermined time is set to be longer as the F-number of the optical system increases. (Configuration 2) 2. The imaging device according to configuration 1, wherein in the detection region of the imaging element that generates the pair of detection signals, the readout time in the second direction is longer than the readout time in the first direction. (Configuration 3) a readout mode for reading out the signals from the pixels in the detection area without thinning out the signals in the second direction can be switched between a first readout mode and a second readout mode in which the readout time in the second direction is longer than that of the first readout mode; 3. The imaging device according to configuration 2, wherein the detection means sets the predetermined time in the second readout mode to be longer than the predetermined time in the first readout mode. (Configuration 4) The imaging device according to any one of configurations 1 to 3, wherein the detection means continues to perform one of the first processing and the second processing that was set at the start of the information acquisition while repeatedly acquiring the information. (Configuration 5) The detection means The information is obtained by multiplying the phase difference by a conversion coefficient; 5. The imaging device according to any one of configurations 1 to 4, wherein the predetermined time is set to be longer as the conversion coefficient increases. (Configuration 6) 6. The imaging device according to any one of configurations 1 to 5, wherein the detection means sets the predetermined time to be longer as the image height at which the phase difference is detected increases. (Configuration 7) 7. The imaging device according to any one of configurations 1 to 6, wherein the detection means sets the predetermined time to be longer as the moving speed of the subject image on the imaging element increases. (Configuration 8) 8. The imaging device according to any one of configurations 1 to 7, wherein the detection means sets the predetermined time to be longer as the focal length of the optical system is longer. (Configuration 9) an image sensor having a plurality of pixels that photoelectrically converts each of light beams that have passed through different pupil regions of the optical system; a detection means for detecting a phase difference between a pair of detection signals generated by signals read out from at least some of the plurality of pixels, thereby obtaining information about focus or distance; The detection means It is possible to perform a first detection of detecting the phase difference in a first direction and a second detection of detecting the phase difference in a second direction different from the first direction, When a readout time in the first direction is shorter than a readout time in the second direction in a detection region of the imaging element that generates the pair of detection signals, the information is acquired by the first detection; When the readout time in the second direction is shorter than the readout time in the first direction, the information is obtained by the second detection. (Other Examples) The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program.The present invention can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0077] The embodiments described above are merely representative examples, and various modifications and alterations are possible to each embodiment when implementing the present invention. [Explanation of symbols]

[0078] 120 Camera body (imaging device) 122 Image sensor 125 Camera MPU 129 Phase difference AF section 129

Claims

1. an image sensor in which a plurality of pixels, each having a plurality of photoelectric conversion units that photoelectrically converts light beams that have passed through different pupil regions of an optical system, are arranged in a first direction that is a row direction and a second direction that is a column direction; a readout means for sequentially reading out signals from the pixels row by row in the second direction in the image sensor; a focus detection unit that detects, based on the readout signal, a first phase difference that is a phase difference of the focus detection signal in the first direction and a second phase difference that is a phase difference of the focus detection signal in the second direction; a focus adjustment unit that performs focus control based on the first phase difference or the second phase difference, The focus adjustment means When the shutter speed is shorter than a predetermined time, a first process is performed to perform a first focus control based on the first phase difference; When the shutter speed is longer than the predetermined time, a second process is performed to select either the first focus control or the second focus control based on the second phase difference and perform focus control; An imaging device characterized in that the predetermined time is longer when the F-number of the optical system is set to a second F-number that is larger than the first F-number than when the F-number is set to the first F-number.

2. 2. The imaging device according to claim 1, wherein the pixels include a pixel having a photoelectric conversion unit divided into two in the first direction and a pixel having a photoelectric conversion unit divided into two in the second direction.

3. 2. The imaging apparatus according to claim 1, wherein in the first process, focus control is performed with only the first phase difference being selectable.

4. 2. The imaging apparatus according to claim 1, wherein in the first process, a first focus control is performed based on the first phase difference without depending on the second phase difference.

5. 2. The imaging device according to claim 1, wherein the imaging element is configured to read out signals using a rolling shutter method in a detection region where the focus detection signal is generated, and the time required to generate the focus detection signal in the second direction is longer than the time required to generate the focus detection signal in the first direction.

6. 2. The imaging apparatus according to claim 1, wherein when focus detection is repeatedly performed by the focus detection means, one of the first process and the second process, whichever process is set at the start, is continuously performed.

7. the focus detection means obtains a defocus amount by multiplying the phase difference by a conversion coefficient; 2. The imaging device according to claim 1, wherein the predetermined time is longer when the conversion coefficient is set to a second value greater than the first value than when the conversion coefficient is set to the first value.

8. 2. The imaging device according to claim 1, wherein the predetermined time is longer when the image height of the detection area for generating the focus detection signal is set to a second image height that is higher than the first image height than when the image height is set to the first image height.

9. 2. The imaging device according to claim 1, wherein the predetermined time is longer when the moving speed of the subject image on the imaging element is set to a second speed that is faster than the first speed than when the moving speed is set to a first speed.

10. 2. The imaging device according to claim 1, wherein the predetermined time is longer when the focal length of the optical system is set to a second focal length that is longer than the first focal length than when the focal length of the optical system is set to the first focal length.

11. an image sensor in which a plurality of pixels, each having a plurality of photoelectric conversion units that photoelectrically converts light beams that have passed through different pupil regions of an optical system, are arranged in a first direction that is a row direction and a second direction that is a column direction; a readout means for sequentially reading out signals from the pixels row by row in the second direction in the image sensor; a focus detection unit that detects, based on the readout signal, a first phase difference that is a phase difference of the focus detection signal in the first direction and a second phase difference that is a phase difference of the focus detection signal in the second direction; a focus adjustment unit that performs focus control based on the detection result by the focus detection unit, The focus adjustment means When the shutter speed is shorter than a predetermined time, focus control is performed based on the first phase difference; When the shutter speed is longer than the predetermined time, focus control is performed based on the first phase difference and the second phase difference; An imaging device characterized in that the predetermined time is longer when the F-number of the optical system is set to a second F-number that is larger than the first F-number than when the F-number is set to the first F-number.

12. 12. The imaging device according to claim 11, wherein the pixels include a pixel having a photoelectric conversion unit divided into two in the first direction and a pixel having a photoelectric conversion unit divided into two in the second direction.

13. 12. The imaging apparatus according to claim 11, wherein when a shutter speed is shorter than the predetermined time, focus control is performed with only the first phase difference being selectable.

14. 12. The imaging apparatus according to claim 11, wherein when a shutter speed is shorter than the predetermined time, a first focus control is performed based on the first phase difference without relying on the second phase difference.

15. the focus detection means obtains a defocus amount by multiplying the phase difference by a conversion coefficient; 12. The imaging device according to claim 11, wherein the predetermined time is longer when the conversion coefficient is set to a second value greater than the first value than when the conversion coefficient is set to the first value.

16. 12. The imaging device according to claim 11, wherein the predetermined time is longer when the image height of the detection area for generating the focus detection signal is set to a second image height that is higher than the first image height than when the image height is set to the first image height.

17. 12. The imaging device according to claim 11, wherein the predetermined time is longer when the moving speed of the subject image on the imaging element is set to a second speed that is faster than the first speed than when the moving speed is set to a first speed.

18. 12. The imaging device according to claim 11, wherein the predetermined time is longer when the focal length of the optical system is set to a second focal length that is longer than the first focal length than when the focal length of the optical system is set to the first focal length.

19. A control method for an imaging device having an imaging element in which a plurality of pixels, each having a plurality of photoelectric conversion units that photoelectrically converts light beams that have passed through different pupil regions of an optical system, are arranged in a first direction that is a row direction and a second direction that is a column direction, the method comprising: a readout step of sequentially reading out signals from the pixels row by row in the second direction in the image sensor; a focus detection step of detecting a first phase difference, which is a phase difference of the focus detection signal in the first direction, and a second phase difference, which is a phase difference of the focus detection signal in the second direction, based on the readout signal; a focus adjustment step of performing focus control based on the first phase difference or the second phase difference, In the focus adjustment step, When the shutter speed is shorter than a predetermined time, a first process is performed to perform a first focus control based on the first phase difference; When the shutter speed is longer than the predetermined time, a second process is performed to select either the first focus control or the second focus control based on the second phase difference and perform focus control; A control method characterized in that the predetermined time is longer when the F-number of the optical system is set to a second F-number larger than the first F-number than when the F-number is set to a first F-number.

20. A control method for an imaging device having an imaging element in which a plurality of pixels, each having a plurality of photoelectric conversion units that photoelectrically converts light beams that have passed through different pupil regions of an optical system, are arranged in a first direction that is a row direction and a second direction that is a column direction, the method comprising: a readout step of sequentially reading out signals from the pixels row by row in the second direction in the image sensor; a focus detection step of detecting a first phase difference, which is a phase difference of the focus detection signal in the first direction, and a second phase difference, which is a phase difference of the focus detection signal in the second direction, based on the readout signal; a focus adjustment step of performing focus control based on the detection result of the focus detection step, In the focus adjustment step, When the shutter speed is shorter than a predetermined time, focus control is performed based on the first phase difference; When the shutter speed is longer than the predetermined time, focus control is performed based on the first phase difference and the second phase difference; A control method characterized in that the predetermined time is longer when the F-number of the optical system is set to a second F-number larger than the first F-number than when the F-number is set to a first F-number.

21. 21. A program causing a computer of the imaging device to execute a process according to the control method of claim 19.

Images