JP2019144462A - Image capturing device, control method therefor, and program - Google Patents

Abstract

To achieve high focus detection accuracy regardless of the presence/absence of auxiliary light irradiation.SOLUTION: A camera MPU 125 provides control to increase the number of summation of AF-A images (first signals) and AF-B images (second signals) in the vertical direction when an optical pattern is being irradiated, compared with when the optical pattern is not irradiated, in a region where a contrast border caused by the optical pattern appears in the vertical direction when the optical pattern is irradiated.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an imaging apparatus having an auxiliary light irradiation function for assisting focus detection, a control method therefor, and a program.

  Conventionally, in an imaging apparatus such as a digital camera or a video camera, a contrast AF method and a phase difference AF method are known as automatic focus detection (AF) methods. Both the contrast AF method and the phase difference AF method are AF methods that are often used in video cameras and digital still cameras. Some of these apparatuses use an image sensor as a focus detection sensor. Since these AF methods perform focus detection using the contrast of an optical image, higher focus detection accuracy can be realized if sufficient contrast is obtained. On the other hand, in a low illuminance environment, the SN ratio of the focus detection signal is lowered, and sufficient focus detection accuracy may not be obtained. As a countermeasure, it is known to add signals of different areas on the image sensor. Although the signal-to-noise ratio is improved by adding signals, if the direction in which the signals are added and the direction of the boundary that causes the contrast of the subject are not parallel, the contrast is lowered and the focus detection accuracy may be lowered. .

  In addition, in order to obtain sufficient focus detection accuracy in a low illuminance environment, an imaging device that emits AF auxiliary light for the purpose of assisting focus detection is known. As AF auxiliary light, there is one that uniformly illuminates the front of the imaging device, and one that projects an optical image having a predetermined pattern (optical pattern) onto a subject (pattern AF auxiliary light) (Patent Document 1). ). The pattern AF auxiliary light is effective in securing the contrast of the focus detection signal while improving the SN of the focus detection signal and realizing higher focus detection accuracy. In Patent Document 1, there are various AF auxiliary light patterns (horizontal pattern, vertical pattern, diagonal pattern), and they are switched depending on the situation.

JP 2006-171147 A

  However, Patent Document 1 does not disclose a method for solving both the problem of a decrease in the SN ratio of a focus detection signal in a low illumination environment and the problem of a decrease in contrast when auxiliary light is used in focus detection. In order to achieve high focus detection accuracy, there is room for improvement in terms of auxiliary light irradiation and signal processing.

  An object of this invention is to implement | achieve high focus detection precision irrespective of the presence or absence of auxiliary light irradiation.

  In order to achieve the above object, the present invention provides an acquisition unit that acquires a plurality of signals corresponding to light beams passing through an imaging optical system corresponding to different positions in a first direction on an image sensor, and the acquisition unit. An adding means for adding the acquired signals in the first direction, a detecting means for detecting a focus based on the signals added by the adding means, and the first direction when assisting focus detection An irradiation unit that irradiates a subject with an optical pattern having a light / dark difference boundary substantially parallel to the object, and a region where the light / dark difference boundary due to the optical pattern is generated in the first direction when the optical pattern is irradiated. When the irradiation of the optical pattern by the irradiating means is performed, the first method by the adding means is compared with the case of not irradiating the optical pattern. And having a control means for controlling so as to increase the addition number of the signal in.

  According to the present invention, high focus detection accuracy can be realized regardless of the presence or absence of auxiliary light irradiation.

It is a block diagram of an imaging device. It is a figure which shows the structural example of an image pick-up element. It is a figure which shows the relationship between a photoelectric conversion area | region and an exit pupil. It is a block diagram of a TVAF part. It is a figure which shows the example of a focus detection area | region. It is a flowchart of AF processing. It is a figure for demonstrating the difference in the signal generation by the presence or absence of auxiliary light. It is a figure explaining the reason for changing the number of addition lines at the time of focus detection signal generation by presence or absence of auxiliary light. It is a figure explaining the reason for changing the number of addition lines at the time of focus detection signal generation by presence or absence of auxiliary light. It is a figure which shows a grid | lattice-like optical pattern.

  Embodiments of the present invention will be described below with reference to the drawings.

  In order to facilitate understanding and explanation of the present invention, the embodiments have specific and specific configurations, but the present invention is not limited to such specific configurations. For example, an embodiment in which the present invention is applied to a single-lens reflex digital camera capable of exchanging lenses will be described below, but the present invention can also be applied to a digital camera and video camera in which lenses cannot be interchanged. The present invention can also be applied to any electronic device equipped with a camera, such as a mobile phone, a personal computer (laptop, tablet, desktop type, etc.), a game machine, and the like.

(Description of configuration of imaging apparatus-lens unit)
FIG. 1 is a block diagram of an imaging apparatus according to an embodiment of the present invention. This imaging apparatus is, for example, a lens interchangeable single-lens reflex digital camera, and includes a lens unit 100 and a camera body 120. The lens unit 100 is attached to the camera body 120 via a mount M indicated by a dotted line in the center of FIG.

  The lens unit 100 includes an optical system (a first lens group 101, a diaphragm 102, a second lens group 103, a focus lens group (hereinafter simply referred to as “focus lens”) 104), and a drive / control system. Thus, the lens unit 100 is a photographing lens that includes the focus lens 104 and forms an optical image of a subject.

  The first lens group 101 is disposed at the tip of the lens unit 100 and is held movably in the optical axis direction OA. The aperture 102 functions as a mechanical shutter that controls the exposure time during still image shooting, in addition to the function of adjusting the amount of light during shooting. The aperture 102 and the second lens group 103 are integrally movable in the optical axis direction OA, and a zoom function is realized by moving in conjunction with the first lens group 101. The focus lens 104 is also movable in the optical axis direction OA, and the subject distance (focus distance) at which the lens unit 100 is focused changes according to the position of the focus lens 104. By controlling the position of the focus lens 104 in the optical axis direction OA, focus adjustment for adjusting the in-focus distance of the lens unit 100 is performed.

  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 uses the zoom actuator 111 to drive the first lens group 101 and the second lens group 103 in the optical axis direction OA, and controls the angle of view of the optical system of the lens unit 100. The diaphragm drive circuit 115 drives the diaphragm 102 using the diaphragm actuator 112 and controls the aperture diameter and opening / closing operation of the diaphragm 102. The focus driving circuit 116 drives the focus lens 104 in the optical axis direction OA using the focus actuator 113, and controls the focusing distance of the optical system of the lens unit 100. The focus driving circuit 116 detects the current position of the focus lens 104 using the focus actuator 113.

  The lens MPU (processor) 117 performs all calculations and control related to the lens unit 100 and controls the zoom drive circuit 114, the aperture drive circuit 115, and the focus drive circuit 116. The lens MPU 117 is connected to the camera MPU 125 through the mount M, and communicates commands and data. For example, the lens MPU 117 detects the position of the focus lens 104 and notifies lens position information in response to a request from the camera MPU 125. This lens position information includes the position of the focus lens 104 in the optical axis direction OA, the position and diameter of the exit pupil in the optical axis direction OA when the optical system is not moving, and the optical axis of the lens frame that restricts the luminous flux of the exit pupil. Contains information such as position and diameter in direction OA. The lens MPU 117 controls the zoom drive circuit 114, the aperture drive circuit 115, and the focus drive circuit 116 in response to a request from the camera MPU 125. The lens memory 118 stores optical information necessary for automatic focus detection in advance. The camera MPU 125 controls the operation of the lens unit 100 by executing a program stored in, for example, a built-in nonvolatile memory or the lens memory 118.

(Explanation of imaging device configuration-camera body)
The camera body 120 includes an optical system (optical low-pass filter 121 and image sensor 122) and a drive / control system. The first lens group 101, the aperture 102, the second lens group 103, the focus lens 104 of the lens unit 100, and the optical low-pass filter 121 of the camera body 120 constitute a photographing optical system.

  The optical low-pass filter 121 reduces false colors and moire in the captured image. The image sensor 122 includes a CMOS image sensor and a peripheral circuit, and includes a plurality of pixels arranged in m pixels in the horizontal direction and n pixels in the vertical direction (n and m are integers of 2 or more). The image sensor 122 of the present embodiment has a pupil division function and can perform phase difference AF using image data. The image processing circuit 124 generates data for phase difference AF and image data for display, recording, and contrast AF (TVAF) from the image data output from the image sensor 122.

  The drive / control system includes a sensor drive circuit 123, an image processing circuit 124, a camera MPU 125, a display 126, an operation switch group (SW) 127, a memory 128, a phase difference AF unit 129, a TVAF unit 130, and an auxiliary light emitting unit 200. Have.

  The sensor drive circuit 123 controls the operation of the image sensor 122, A / D converts the acquired image signal, and transmits it to the image processing circuit 124 and the camera MPU 125. The image processing circuit 124 performs general image processing performed by a digital camera, such as γ conversion, white balance adjustment processing, color interpolation processing, and compression coding processing, on the image data acquired by the image sensor 122. The image processing circuit 124 also generates a signal for phase difference AF.

  The camera MPU (processor) 125 performs all calculations and controls related to the camera body 120, and includes a sensor drive circuit 123, an image processing circuit 124, a display 126, an operation switch group 127, a memory 128, a phase difference AF unit 129, and a TVAF. The unit 130 is controlled. The camera MPU 125 is connected to the lens MPU 117 via the signal line of the mount M, and communicates commands and data with the lens MPU 117. The camera MPU 125 issues a lens position acquisition request, a diaphragm / focus lens / zoom drive request with a predetermined driving amount, an optical information acquisition request unique to the lens unit 100, and the like to the lens MPU 117. The camera MPU 125 includes a ROM 125a that stores a program for controlling camera operations, a RAM 125b that stores variables, and an EEPROM 125c that stores various parameters.

  The display 126 is configured by an LCD or the like, and displays information related to the shooting mode of the camera, a preview image before shooting and a confirmation image after shooting, a focus state display image at the time of focus detection, and the like. The operation switch group 127 includes a power switch, a release (shooting trigger) switch, a zoom operation switch, a shooting mode selection switch, and the like. The memory 128 is a detachable flash memory, and records captured images.

  The phase difference AF unit 129 performs focus detection processing by the phase difference detection method using the focus detection data obtained by the image processing circuit 124. More specifically, the image processing circuit 124 generates a pair of image data formed by a light beam passing through a pair of pupil regions of the photographing optical system as focus detection data, and the phase difference AF unit 129 The defocus amount is detected based on the image data shift amount. As described above, the phase difference AF unit 129 performs phase difference AF (imaging surface phase difference AF) based on the output of the image sensor 122 without using a dedicated AF sensor. The operation of the phase difference AF unit 129 will be described in detail later.

  The TVAF unit 130 performs contrast type focus detection processing based on the TVAF evaluation value (contrast information of the image data) generated by the image processing circuit 124. In contrast type focus detection processing, the focus lens 104 is moved and the focus lens position where the evaluation value reaches a peak is detected as the focus position.

  As described above, the digital camera according to the present embodiment can execute both phase difference AF and TVAF, and can be selectively used or used in combination depending on the situation.

  The auxiliary light emitting unit 200 as an irradiating unit emits (irradiates) and turns off according to a light emission instruction and a light off instruction from the camera MPU 125. When the subject for which focus adjustment is to be performed has low contrast or low illuminance, it is possible to increase the number of situations where focus adjustment is possible by irradiating the subject with auxiliary light. The auxiliary light emitting unit 200 has so-called pattern AF auxiliary light that projects an optical image having a predetermined pattern (optical pattern) onto a subject. The light having the optical pattern emitted from the auxiliary light emitting unit 200 is projected onto the subject through the optical system. Therefore, the contrast of the optical pattern varies depending on the distance, and there is a distance at which the pattern is formed and a high-contrast image is formed, and a distance at which the pattern is blurred and a low-contrast image is formed.

(Description of focus detection operation: phase difference AF)
Hereinafter, operations of the phase difference AF unit 129 and the TVAF unit 130 will be further described. First, the operation of the phase difference AF unit 129 will be described.

  FIG. 2A is a diagram illustrating a pixel array of the image sensor 122. FIG. 2 shows a state in which a range of 6 rows in the vertical direction (Y direction) and 8 columns in the horizontal direction (X direction) of the two-dimensional CMOS area sensor is observed from the lens unit 100 side. The image sensor 122 is provided with a Bayer color filter. The odd-numbered pixels have green (G) and red (R) color filters alternately from the left, and the even-numbered pixels sequentially from the left. Blue (B) and green (G) color filters are alternately arranged. In the pixel 211, a circle 211i represents an on-chip microlens, and a plurality of rectangles 211a and 211b arranged inside the on-chip microlens are photoelectric conversion units.

  In the image sensor 122, the photoelectric conversion units of all the pixels are divided into two in the X direction, and the photoelectric conversion signals of the individual photoelectric conversion units and the sum of the photoelectric conversion signals can be read independently. Further, a signal corresponding to the photoelectric conversion signal of the other photoelectric conversion unit can be obtained by subtracting the photoelectric conversion signal of one photoelectric conversion unit from the sum of the photoelectric conversion signals. The photoelectric conversion signal in each photoelectric conversion unit can be used as data for phase difference AF, or can be used to generate a parallax image constituting a 3D (3-Dimensional) image. The sum of photoelectric conversion signals can be used as normal captured image data.

  Here, a pixel signal when performing phase difference AF will be described. As will be described later, in this embodiment, the exit lens of the photographing optical system is pupil-divided by the micro lens 211i shown in FIG. 2A and the divided photoelectric conversion units 211a and 211b. For a plurality of pixels 211 within a predetermined range arranged in the same pixel row, a combination of the output of the photoelectric conversion unit 211a and the output of the photoelectric conversion unit 211b combined with the output of the photoelectric conversion unit 211a A B image for AF is used. Therefore, the AF A image (first signal) and the AF B image (second signal) correspond to light beams passing through different pupil regions of the imaging optical system and correspond to different positions in the vertical direction on the image sensor. Thus, a plurality of signals are acquired. As the outputs of the photoelectric conversion units 211a and 211b, pseudo luminance (Y) signals calculated by adding the outputs of green, red, blue, and green included in the unit array of the color filter are used. However, the AF A image and the B image may be knitted for each of red, blue, and green colors. By detecting the relative image shift amount between the AF A image and the AF B image generated in this way by correlation calculation, the defocus amount (defocus amount) of the predetermined region can be detected. In this embodiment, it is assumed that the sum of the output of one photoelectric conversion unit and the output of all the photoelectric conversion units is read from the image sensor 122. For example, the output of the photoelectric conversion unit 211a and the sum of the outputs of the photoelectric conversion units 211a and 211b are read out. In this case, the output of the photoelectric conversion unit 211b is obtained by subtracting the output of the photoelectric conversion unit 211a from the sum. Thereby, both an A image for AF and a B image can be obtained, and phase difference AF can be realized. Such an image pickup device is known as disclosed in Japanese Patent Application Laid-Open No. 2004-134867, and thus detailed description thereof is omitted.

  FIG. 2B is a diagram illustrating a configuration example of a readout circuit of the image sensor 122. The readout circuit includes a horizontal scanning circuit 151 and a vertical scanning circuit 153. Horizontal scanning lines 152a and 152b and vertical scanning lines 154a and 154b are wired at the boundary between the pixels, and signals are read out to the photoelectric conversion units through these scanning lines.

  Note that this digital camera has the following two readout modes in addition to the above-described readout method in the pixel from the image sensor 122. The first readout mode is called an all-pixel readout mode and is a mode for capturing a high-definition still image. In this case, signals of all pixels are read out. The second readout mode is called a thinning readout mode, and is a mode for performing only moving image recording or preview image display. Since the number of pixels required in this case is smaller than all the pixels, only the pixels thinned out at a predetermined ratio in both the X direction and the Y direction are read out. Also, when it is necessary to read out at high speed, the thinning-out reading mode is similarly used. When thinning out in the X direction, the sensor driving circuit 123 performs signal addition to improve the S / N ratio, and thinning out in the Y direction ignores the signal output of the thinned out rows. The phase difference AF and the contrast AF are also usually performed based on the signal read in the second reading mode.

  FIG. 3A is a diagram for explaining the conjugate relationship between the exit pupil plane of the photographing optical system and the photoelectric conversion unit of the image sensor disposed at the image height zero, that is, near the center of the image plane. The photoelectric conversion unit in the image sensor 122 and the exit pupil plane of the photographing optical system are designed to have a conjugate relationship by an on-chip microlens. The exit pupil of the photographic optical system generally coincides with the surface on which the iris diaphragm for adjusting the amount of light is placed. On the other hand, the photographing optical system in the present embodiment includes a zoom lens having a zoom function, but depending on the optical type, the distance and the size of the exit pupil from the image plane change when the zoom operation is performed. FIG. 3A shows a state where the focal length of the lens unit 100 is at the center between the wide-angle end and the telephoto end. Using the exit pupil distance Zep in this state as a standard value, the optimum design of the eccentricity parameter according to the shape of the on-chip microlens and the image height (X, Y coordinates) is made.

  In FIG. 3A, 101 is a first lens group, 101 b is a lens barrel member that holds the first lens group, 104 is a focus lens, and 104 b is a lens barrel member that holds the focus lens 104. Reference numeral 102 denotes an aperture, reference numeral 102a denotes an aperture plate that defines an aperture diameter when the aperture is opened, and reference numeral 102b denotes an aperture blade for adjusting the aperture diameter when the aperture is closed. Note that reference numerals 101b, 102a, 102b, and 104b that act as limiting members for the light beam passing through the photographing optical system indicate optical virtual images when observed from the image plane. Further, the synthetic aperture in the vicinity of the stop 102 is defined as the exit pupil of the lens, and the distance from the image plane is Zep as described above.

  The pixel 211 is disposed in the vicinity of the center of the image plane, and is referred to as a central pixel in the present embodiment. The pixel 211 is composed of photoelectric conversion units 211a and 211b, wiring layers 211e to 211g, a color filter 211h, and an on-chip microlens 211i from the bottom layer. The two photoelectric conversion units are projected on the exit pupil plane of the photographing optical system by the on-chip microlens 211i. In other words, the exit pupil of the photographing optical system is projected onto the surface of the photoelectric conversion unit via the on-chip microlens 211i.

  FIG. 3B is a diagram illustrating a projected image of the photoelectric conversion unit on the exit pupil plane of the photographing optical system. Projected images on the photoelectric conversion units 211a and 211b are projected images EP1a and EP1b. The image sensor 122 includes a pixel that can obtain the output of either one of the two photoelectric conversion units 211a and 211b and the sum of both. The sum of both outputs is a photoelectric conversion of the light beam that has passed through both regions of the projection images EP1a and EP1b, which are almost the entire pupil region of the photographing optical system.

  In FIG. 3A, when the outermost part of the light beam passing through the photographing optical system is denoted by L, the light beam L is regulated by the aperture plate 102a of the diaphragm, and the projected images EP1a and EP1b are vignetted by the photographing optical system. Almost no occurrence. In FIG.3 (b), the light beam L of Fig.3 (a) is shown by TL. Since most of the projected images EP1a and EP1b of the photoelectric conversion unit are included in the circle indicated by TL, it can be seen that almost no vignetting occurs. Since the light beam L is limited only by the aperture plate 102a of the diaphragm, TL can be restated as the aperture plate 102a. At this time, the vignetting state of each of the projected images EP1a to EP1b is symmetric with respect to the optical axis at the center of the image plane, and the amount of light received by each of the photoelectric conversion units 211a and 211b is equal.

  When performing phase difference AF, the camera MPU 125 controls the sensor drive circuit 123 so as to read the above-described two types of outputs from the image sensor 122. Then, the camera MPU 125 gives information on the focus detection area to the image processing circuit 124, generates data for AF A and B images from the output of the pixels included in the focus detection area, and generates the phase difference AF unit 129. To supply to. The image processing circuit 124 generates AF A and B image data in accordance with this command and outputs it to the phase difference AF unit 129. The image processing circuit 124 also supplies RAW image data to the TVAF unit 130.

  As described above, the image sensor 122 constitutes a part of the focus detection apparatus for both the phase difference AF and the contrast AF.

  Here, as an example, the configuration in which the exit pupil is divided into two in the horizontal direction has been described. However, a configuration in which some of the pixels of the image sensor 122 are divided in the vertical direction may be used. Further, the exit pupil may be divided in both the horizontal and vertical directions. By providing pixels that divide the exit pupil in the vertical direction, phase difference AF corresponding to the contrast of the subject in the vertical direction as well as in the horizontal direction becomes possible.

(Description of focus detection operation: contrast AF)
Next, contrast AF (TVAF) will be described with reference to FIG. FIG. 4 is a block diagram of the TVAF unit 130. The contrast AF is realized by the camera MPU 125 and the TVAF unit 130 cooperating to repeatedly drive the focus lens 104 and calculate the evaluation value.

  When the RAW image data is input from the image processing circuit 124 to the TVAF unit 130, the AF evaluation signal processing circuit 401 extracts the green (G) signal from the Bayer array signal and emphasizes the low luminance component to increase the luminance. A gamma correction process for suppressing the component is performed. In this embodiment, a case where TVAF is performed using a green (G) signal is described, but all signals of red (R), blue (B), and green (G) may be used. Further, a luminance (Y) signal may be generated using all RGB colors. The output signal generated by the AF evaluation signal processing circuit 401 is referred to as a luminance signal Y in the following description regardless of the type of signal used.

  It is assumed that a focus detection area is set in the area setting circuit 413 from the camera MPU 125. The region setting circuit 413 generates a gate signal that selects a signal in the set region. The gate signal is input to each circuit of the line peak detection circuit 402, the horizontal integration circuit 403, the line minimum value detection circuit 404, the line peak detection circuit 409, the vertical integration circuits 406 and 410, and the vertical peak detection circuits 405, 407, and 411. The Further, the timing at which the luminance signal Y is input to each circuit is controlled so that each focus evaluation value is generated by the luminance signal Y in the focus detection region. In the area setting circuit 413, a plurality of areas can be set in accordance with the focus detection area.

  A method for calculating the Y peak evaluation value will be described. The gamma-corrected luminance signal Y is input to the line peak detection circuit 402, and the Y line peak value for each horizontal line is obtained within the focus detection area set in the area setting circuit 413. The output of the line peak detection circuit 402 is peak-held in the vertical direction within the focus detection area by the vertical peak detection circuit 405, and a Y peak evaluation value is generated. The Y peak evaluation value is an effective index for determining a high brightness subject or a low illumination subject.

  A method for calculating the Y integral evaluation value will be described. The gamma-corrected luminance signal Y is input to the horizontal integration circuit 403, and an integral value of Y is obtained for each horizontal line within the focus detection area. Further, the output of the horizontal integration circuit 403 is integrated in the vertical direction in the focus detection region by the vertical integration circuit 406, and a Y integration evaluation value is generated. The Y integral evaluation value can be used as an index for determining the brightness of the entire focus detection area.

  A method for calculating the Max-Min evaluation value will be described. The gamma-corrected luminance signal Y is input to the line peak detection circuit 402, and the Y line peak value for each horizontal line is obtained within the focus detection area. Further, the luminance signal Y subjected to gamma correction is input to the line minimum value detection circuit 404, and the minimum value of Y is detected for each horizontal line in the focus detection area. The detected Y line peak value and minimum value for each horizontal line are input to the subtractor, and (line peak value−minimum value) is input to the vertical peak detection circuit 407. The vertical peak detection circuit 407 performs peak hold in the vertical direction within the focus detection area, and generates a Max-Min evaluation value. The Max-Min evaluation value is an effective index for determining low contrast and high contrast.

  A method for calculating the region peak evaluation value will be described. By passing the gamma-corrected luminance signal Y through the BPF 408, a specific frequency component is extracted and a focus signal is generated. This focus signal is input to the line peak detection circuit 409, and the line peak value for each horizontal line is obtained within the focus detection area. The line peak value is peak-held in the focus detection area by the vertical peak detection circuit 411, and an area peak evaluation value is generated. The area peak evaluation value is an effective index for restart determination that determines whether or not to shift from the in-focus state to the process of searching for the in-focus point again because the change is small even when the subject moves within the focus detection area.

  A method for calculating the total line integral evaluation value will be described. Similar to the area peak evaluation value, the line peak detection circuit 409 obtains a line peak value for each horizontal line in the focus detection area. Next, the line peak detection circuit 409 inputs the line peak value to the vertical integration circuit 410 and integrates the total number of horizontal scanning lines in the vertical direction within the focus detection area to generate the total line integration evaluation value. The high-frequency all-line integral evaluation value is a main AF evaluation value because it has a wide dynamic range and high sensitivity due to the integration effect. Therefore, in the present embodiment, when it is simply described as a focus evaluation value, it means an all-line integral evaluation value.

  The AF control unit 150 of the camera MPU 125 acquires each of the above-described focus evaluation values, and moves the focus lens 104 in a predetermined direction along the optical axis direction through the lens MPU 117. Then, the various evaluation values described above are calculated based on the newly obtained image data, and the focus lens position at which the total integrated evaluation value is the maximum value is detected.

  In the present embodiment, the camera MPU 125 inputs various AF evaluation values in the horizontal line direction and the vertical line direction by inputting each horizontal line and each vertical line to the TVAF unit 130 shown in FIG. . Thereby, focus detection can be performed on the contrast information of the subject in two directions that are orthogonal to each other in the horizontal and vertical directions.

(Description of focus detection area)
FIG. 5 is a diagram illustrating an example of the focus detection area within the imaging range. As described above, both phase difference AF and contrast AF are performed based on signals obtained from pixels included in the focus detection area. In FIG. 5, a rectangle indicated by a dotted line indicates an imaging range 217 in which pixels of the image sensor 122 are formed. In the imaging range 217, focus detection areas 218ah, 218bh, and 218ch for phase difference AF are set. In the present embodiment, focus detection areas 218ah, 218bh, and 218ch for phase difference AF are set at a total of three locations, that is, the central portion of the imaging range 217 and two locations on the left and right. The focus detection areas 219a, 219b, and 219c for TVAF are set so as to include one of the focus detection areas 218ah, 218bh, and 218ch for phase difference AF. FIG. 5 is an example of setting the focus detection area, and the number, position, and size are not limited to those shown in the figure.

(Explanation of focus detection process flow)
Next, an automatic focus detection (AF) operation in the digital camera will be described with reference to FIG. FIG. 6 is a flowchart of the AF process. This process is realized by the camera MPU 125 reading the program stored in the ROM 125a into the RAM 125b and executing it. The following AF processing operations are executed mainly by the camera MPU 125, unless other subjects are specified. When the camera MPU 125 drives and controls the lens unit 100 by transmitting a command or the like to the lens MPU 117, the operation subject may be described as the camera MPU 125 for the sake of brevity. This is because the camera MPU 125 substantially controls the lens unit 100 via the lens MPU 117. In the process of FIG. 6, the camera MPU 125 corresponds to an acquisition unit, an addition unit, and a detection unit in the present invention.

  First, in S101, the camera MPU 125 sets a focus detection area. Here, three focus detection areas as shown in FIG. 5 are set for both phase difference AF and contrast AF.

  In step S102, the camera MPU 125 exposes the image sensor 122 to read out an image signal, and the image processing circuit 124 reads the image signal for phase difference AF based on the image data in the focus detection areas 218ah, 218bh, and 218ch for phase difference AF. Is generated. Further, the camera MPU 125 supplies the RAW image data generated by the image processing circuit 124 to the TVAF unit 130, and causes the TVAF unit 130 to calculate an evaluation value based on the pixel data in the focus detection areas 219 a, 219 b, and 219 c for TVAF. . In addition, before generating the image signal for phase difference AF, the image processing circuit 124 corrects the asymmetry of the exit pupil due to the vignetting of the light beam by the lens frame of the photographing lens (see Japanese Patent Application Laid-Open No. 2010-117679). May be applied. The focus evaluation value calculated by the TVAF unit 130 is stored in the RAM 125b in the camera MPU 125. A method for generating an image signal for phase difference AF and a method for generating a signal used for calculating a focus evaluation value will be described later.

  In step S103, the camera MPU 125 determines whether or not auxiliary light is necessary. In general, auxiliary light is effective when focus detection is performed on a subject with low illuminance and low contrast. Therefore, the camera MPU 125 compares the contrast (brightness / darkness difference) and average output value of the image signal for phase difference AF acquired in S102 with a predetermined threshold value, and if it is determined that the contrast is low or the illuminance is low, Judge that auxiliary light is necessary. If it is determined that auxiliary light is not necessary, the camera MPU 125 proceeds to S106, and if it is determined that auxiliary light is necessary, the camera MPU 125 proceeds to S106 after executing S104 and S105.

  In S104, the camera MPU 125 issues an auxiliary light emission instruction to cause the auxiliary light emission unit 200 to emit light. Thus, the optical pattern is irradiated onto the subject to assist in focus detection. At this time, the camera MPU 125 sets “1” indicating the light emission state to the auxiliary light flag for determining whether the auxiliary light is on or off.

  Next, in S105, the camera MPU 125 executes the same processing as in S102, that is, the image processing circuit 124 generates a phase difference AF image signal, the TVAF unit 130 calculates a focus evaluation value, and the like. However, in S102 and S105, when the signal corresponding to the light beam passing through the imaging optical system is added, the number of signals added in the vertical direction (Y direction) (first direction) in the image sensor 122 is different. Is more in S105. Including this, a method of generating an image signal for phase difference AF and a signal used for calculating a focus evaluation value for TVAF will be described with reference to FIGS.

  7A to 7C are diagrams for explaining a difference in signal generation depending on the presence or absence of auxiliary light. A signal generation method based on the presence or absence of auxiliary light is controlled by the camera MPU 125. The camera MPU 125 performs signal addition in the vertical direction with respect to the signal for detecting the phase difference in the horizontal direction.

  FIG. 7A shows the signal output read from the area in the image sensor 122 corresponding to one focus detection area 218 in units of rows. In the example of FIG. 7A, the focus detection area 218 is configured by 12 signal rows. The first to twelfth lines of the AF A image and B image are La (1) to La (12) and Lb (1) to Lb (12), respectively. The camera MPU 125 acquires a signal used for TVAF as the sum of the signals of the AF A image and the AF B image. In the following, the addition of image signals for phase difference AF will be mainly described. However, by using the sum of a pair of signals for AF A and B images as a signal for TVAF before addition, The present invention can be similarly applied to the addition method.

FIG. 7B shows an example of a method for generating a focus detection signal when auxiliary light is not used. As described above, the signals of the 12 rows of the image sensor 122 have different spectral sensitivities of the signal output included in the even rows and the odd rows due to the color filters in the Bayer array. In the present embodiment, in order to align the spectral sensitivities of each row, the camera MPU 125 performs addition, for example, in units of two rows to generate six rows of focus detection signals. For example, for the AF A image, the added signal La_off (1) in the first row is calculated by the following Equation 1.
[Equation 1]
La_off (1) = La (1) + La (2)

  Therefore, for example, the signals of the third and fourth rows are added, and the signals of the fifth and sixth rows are added. Similarly, for the AF B image, the camera MPU 125 adds, for example, in units of two rows to generate six rows of focus detection signals. That is, when the auxiliary light is not used, six rows of focus detection signals are generated.

  The camera MPU 125 performs correlation calculation on the generated focus detection signals of 6 pairs (for 6 rows of AF A image and B image) to obtain six correlation amount waveforms, and further, After adding the correlation amount, the defocus amount is calculated (described later in S107).

FIG. 7C shows an example of a method for generating a focus detection signal when auxiliary light is used. When the auxiliary light is used, the camera MPU 125 performs addition using more rows for the purpose of improving the SN ratio of the focus detection signal. In the example of FIG. 7C, the camera MPU 125 performs addition in units of 4 rows to generate focus detection signals for 3 rows. For example, the added signal La_on (1) in the first row is calculated by the following Equation 2.
[Equation 2]
La_on (1) = La (1) + La (2) + La (3) + La (4)

  Therefore, for example, the signals in the 5th to 8th rows are added, and the signals in the 9th to 12th rows are added. Similarly, with respect to the AF B image, the camera MPU 125 performs addition in units of, for example, four rows, and generates three rows of focus detection signals. That is, when the auxiliary light is used, three rows of focus detection signals are generated.

  The camera MPU 125 performs correlation calculation on the generated three pairs of focus detection signals (for three rows of AF A image and B image) to obtain three correlation amount waveforms. Are added, and then the defocus amount is calculated (described later in S107).

  In this manner, the camera MPU 125 changes the combination of the number of output signals from the image sensor 122 and the number of correlation amounts according to the presence / absence of auxiliary light, so that signals in substantially the same area on the image sensor can be obtained. To focus detection. If the focus detection area is enlarged too much, there is a high possibility that focus detection will be performed on subjects at various distances, and focus detection accuracy is impaired due to so-called distance competition. In the present embodiment, it is not necessary to unnecessarily widen the focus detection area, so that high focus detection accuracy can be maintained.

  The reason for changing the number of added rows when generating a focus detection signal according to the presence or absence of auxiliary light will be described with reference to FIG. FIG. 8A shows a pattern of an optical image projected by the auxiliary light emitting unit 200, that is, an optical pattern. In FIG. 8A, an optical image is projected where the shaded portion is bright and the other portions are dark. That is, this optical pattern is composed of a plurality of lines substantially parallel to the vertical direction (first direction) in which signal outputs are added. The size of the optical image, the contrast of light and darkness, and the degree of blur vary depending on the distance of the illuminated subject. This optical pattern has a boundary of contrast (contrast) substantially parallel to the vertical direction. In the example of FIG. 8A, there are four boundaries that cause a difference in brightness.

  FIG. 8B shows a state in which the optical pattern is imaged on the image sensor. In FIG. 8B, the rows of the focus detection signals that have been subjected to the signal addition processing in the case of emitting auxiliary light described in FIG. 7C are shown superimposed. In FIG. 8B, the boundary causing the difference in brightness of the auxiliary light is the vertical direction, and the addition direction of the focus detection signals is also the vertical direction, and they coincide with each other.

  FIG. 8C is a diagram showing signal output in the first row shown in FIG. In FIG. 8C, the horizontal axis indicates the pixel number, and the vertical axis indicates the signal intensity. As described above, since the boundary of the optical image of the auxiliary light and the addition direction of the focus detection signal coincide with each other in the vertical direction, the contrast of the optical image hardly decreases even when the signals are added. On the other hand, the signal-to-noise ratio at the time of generating the focus detection signal is improved by signal addition. Therefore, high focus detection accuracy can be maintained while improving the SN ratio at the time of generating the focus detection signal.

  On the other hand, when the boundary of the optical image of the auxiliary light does not coincide with the addition direction of the focus detection signal, the focus detection accuracy does not increase as described below. FIG. 9A shows a case where the boundary of the optical image of the auxiliary light is inclined with respect to the vertical direction. FIG. 9B is a diagram showing the signal output of the first row shown in FIG. In contrast to the example of FIG. 8C, in the example of FIG. 9B, the number of edges indicating the brightness difference of the focus detection signal is 4 because the boundary of the brightness difference of the optical image of the auxiliary light is inclined. Reduced from two to two. In addition, the steepness (inclination) of the edge indicating the brightness difference of the focus detection signal is also gentle. These events indicate that the amount of information in the focus detection signal is decreasing, leading to a decrease in focus detection accuracy.

  In FIG. 9A, the case where the boundary between the light and dark differences is inclined as the optical image of the auxiliary light has been described. However, the direction of the boundary of the subject when the auxiliary light is not used can take any direction. On the other hand, when the optical image of the auxiliary light is projected, although it is influenced by the shape of the subject, it is possible to generally receive the optical image maintaining the emitted pattern shape. For this reason, in the present embodiment, the number of rows to be added when generating a focus detection signal is changed depending on whether or not auxiliary light is emitted.

  As described above, when the camera MPU 125 does not emit auxiliary light, the camera MPU 125 performs focus detection with high accuracy regardless of the boundary direction of the contrast of the subject, and therefore, the number of rows is smaller than that when the auxiliary light is emitted. Signal addition. On the other hand, in the case of emitting auxiliary light, the direction of the boundary of the contrast of the subject (optical image pattern of auxiliary light) is the vertical direction. Using this, the camera MPU 125 adds a larger number of rows to improve the SN ratio of the focus detection signal while maintaining the signal of the subject (the number of edges in the signal and the steepness). Yes. Thereby, high-precision focus detection is realized regardless of whether or not auxiliary light is emitted.

  In S106 of FIG. 6, the camera MPU 125 determines whether or not a reliable peak (maximum value) of the focus evaluation value has been detected. If a reliable peak is detected, the camera MPU 125 advances the process to S108 in order to finish the focus detection process. The method for calculating the reliability of the peak of the focus evaluation value is not limited. For example, a method described in FIGS. 10 to 13 of JP 2010-78810 A may be used. Specifically, the camera MPU 125 determines whether the detected peak is the peak of a mountain, the difference between the maximum value and the minimum value of the focus evaluation value, and the length of the portion that is inclined with a slope equal to or greater than a certain value (SlopeThr). , And the slope of the sloped portion is determined by comparison with respective threshold values. If all the threshold values are satisfied, it can be determined that the peak is reliable.

  In the present embodiment, phase difference AF and contrast AF are used together. For this reason, if the presence of a closer subject is confirmed in the same focus detection area or another focus detection area, the focus evaluation value peak is detected even when a reliable focus evaluation value peak is detected. The process may be advanced to S107 without finishing the detection. However, in this case, the position of the focus lens 104 corresponding to the reliable focus evaluation value peak is stored, and the stored focus is obtained when a reliable focus detection result is not obtained in the processing after S107. The position of the lens 104 is a focus detection result. That is, when a more reliable focus detection result is not obtained by the phase difference AF, the stored contrast AF result is adopted.

  In step S107, the phase difference AF unit 129 calculates a correlation amount between the AF A image and the B image as a pair of image signals supplied from the image processing circuit 124 (performs a correlation calculation). The correlation calculation is performed for each of the focus detection regions 218ch, 218ah, and 218bh and for a plurality of pairs of image signals (correlation calculation is performed a number of times corresponding to the number of pairs). Thereafter, the phase difference AF unit 129 converts the phase difference into a defocus amount using a conversion coefficient stored in advance. Here, the image signal used in S107 is generated in S105 when it passes through S105, but it is generated in S102 when it does not pass through S105. When the AF A and B image signals are expressed as A (k) and B (k) (1 ≦ k ≦ P), the correlation amount COR (h) calculated by the correlation calculation is calculated by, for example, Equation 3 below. Is done.

  In Formula 3, W1 corresponds to the size of the window (the number of data in the field of view) for calculating the correlation amount, and hmax corresponds to the number of times the position of the window is changed between the pair of signals (the number of shift data).

  After a plurality of correlation amounts are calculated from a plurality of pairs of A image and B image signals, the camera MPU 125 adds the correlation amounts according to Equation 4 below. Here, a case where three correlation amounts are added is described as an example.

  The phase difference AF unit 129 obtains the correlation amount COR (h) for each shift amount h by adding the correlation amounts, and then the shift amount h that provides the highest correlation between the A image and the B image, that is, the correlation amount COR. Find the value of the shift amount h that minimizes. Note that the shift amount h when calculating the correlation amount COR (h) is an integer. However, when obtaining the shift amount h that minimizes the correlation amount COR (h), the phase difference AF unit 129 performs interpolation processing as appropriate to improve the accuracy of the defocus amount, and the value (actual value) in subpixel units. (Numerical value) may be obtained.

The camera MPU 125 calculates the shift amount dh in which the sign of the difference value of the correlation amount COR changes as the shift amount h that minimizes the correlation amount COR (h). First, the phase difference AF unit 129 calculates a correlation value difference value DCOR according to the following Equation 5.
[Equation 5]
DCOR (h) = COR (h) −COR (h−1)

Then, the phase difference AF unit 129 obtains the shift amount dh in which the sign of the difference amount changes using the correlation amount difference value DCOR. Assuming that the value of the shift amount h immediately before the change of the sign of the difference amount is h1, and the value of the shift amount h of which the sign has changed is h2 (h2 = h1 + 1), the phase difference AF unit 129 sets the shift amount dh to the following formula: 6 is calculated.
[Equation 6]
dh = h1 + | DCOR (h1) | / | DCOR (h1) −DCOR (h2) |

  As described above, the phase difference AF unit 129 calculates the shift amount dh that maximizes the correlation between the A image and the B image in units of subpixels. The method for calculating the phase difference between the two one-dimensional image signals is not limited to that described here, and any known method can be used.

  In S107, the camera MPU 125 also determines the reliability of the calculated defocus amount, and uses only the defocus amount of the focus detection area determined to have the predetermined reliability in the subsequent AF processing. The phase difference detected between the pair of image signals includes more errors as the defocus amount increases due to the vignetting effect of the lens frame or the like. For this reason, when the obtained defocus amount is larger than the threshold, when the degree of coincidence between the shape of the pair of image signals is low, or when the contrast of the image signals is low, the obtained defocus amount has a predetermined reliability. It can be determined that it does not exist (low reliability). Hereinafter, when it is determined that the obtained defocus amount has predetermined reliability, it is expressed as “the defocus amount has been calculated”. Further, when the defocus amount cannot be calculated for some reason, or when it is determined that the reliability of the defocus amount is low, it is expressed as “the defocus amount cannot be calculated”.

  Here, as described above, the number of image signals to be added in the vertical direction is larger in the case with auxiliary light (with irradiation of the optical pattern) than in the case without auxiliary light. Therefore, in the addition of the correlation amount in S107, the greater the number of added image signals, the smaller the number of signals after addition.

  In S108, the camera MPU 125 selects a focus detection area. In the present embodiment, the detection result of the focus detection area indicating that the subject is present on the closer side is employed. This is because, in general, the main subject is frequently located on the close side. The method for selecting the focus detection area is not limited to this. For example, various methods are conceivable, such as preferentially selecting a detection result of a person's face or a focus detection area at the center of the screen.

  In step S109, the camera MPU 125 drives the focus lens 104 through the lens MPU 117 based on the defocus amount calculated for the selected focus detection region. In S110, the camera MPU 125 instructs the auxiliary light to be turned off, and sets the auxiliary light flag to “0” indicating the off state. In this embodiment, the auxiliary light is turned off after driving the lens to the in-focus position, but the timing of turning off the light is not limited to this. For example, the light may be turned off when highly reliable focus detection is obtained. Thereby, the light emission period can be shortened and power saving can be realized. In step S111, the camera MPU 125 superimposes and displays a display (AF frame display) representing the focus detection area in which the defocus amount used for driving the focus lens 104 is calculated, for example, on the live view image, as shown in FIG. This AF processing is finished.

  As described above, when the number of output signal addition rows is small, the number of correlation amount additions is larger than when there are many addition rows. On the other hand, when the auxiliary light is emitted, the number of added lines of the output signal increases, so that there is a risk that the focus detection accuracy is lowered if the subject has a boundary having a contrast difference in the oblique direction. However, the auxiliary light is usually required to detect the focus of a low-illuminance or low-contrast subject, so that the risk of reducing the focus detection accuracy is small even if the auxiliary light is emitted. Therefore, in situations such as low illuminance, high-accuracy focus detection can be realized by emitting auxiliary light and increasing the signal addition number before the correlation calculation to improve the SN ratio.

  By the way, it is assumed that the optical pattern is composed of a plurality of lines substantially parallel to the vertical direction, and the boundary of the contrast of the optical image of the auxiliary light has only the vertical direction. However, the configuration of the optical pattern is not limited to this. For example, as illustrated in FIG. 10, an optical pattern having a boundary between brightness and darkness in a lattice shape in both a first direction (vertical direction) and a second direction (horizontal direction) substantially orthogonal to the first direction. It may be adopted. In this case, if the conditions other than the presence or absence of irradiation are the same, the following may be performed. In other words, the process of increasing the number of signals added in the direction substantially parallel to the signal addition direction (vertical direction) when irradiating the optical pattern as compared to the non-irradiation direction is an area where the boundary of the light and dark difference in the vertical direction (for example, You may apply in area | region R2, R4). Then, the same process may not be applied to a region (for example, the regions R1 and R3) where the boundary between the light and dark differences in the vertical direction does not occur.

  According to the present embodiment, the camera MPU 125 controls to increase the number of signals added in the vertical direction when the optical pattern is irradiated as compared to when the optical pattern is not irradiated. In the phase difference AF, the signal here corresponds to an AF A image (first signal) and an AF B image (second signal). In TVAF, the sum of the A and B images for AF corresponds. In the case where the optical pattern is in a lattice shape or the like, the above control is applied in a region where a boundary between light and dark differences due to the optical pattern is generated in the vertical direction by irradiation of the optical pattern. As a result, the SN ratio can be improved while avoiding the problem of a decrease in contrast when auxiliary light is used. Therefore, high focus detection accuracy can be realized regardless of the presence or absence of auxiliary light irradiation.

  In the present embodiment, the case where the contrast detection direction of phase difference AF or TVAF is the horizontal direction and the direction in which the focus detection signal is added is the vertical direction has been described. However, the present invention can be similarly applied to the case where so-called cross-type focus detection is performed in which the focus detection is performed in the horizontal and vertical directions. In this case, after the focus detection direction is selected to be horizontal or vertical, the addition number of focus detection signals may be determined, or the focus detection signals are added separately in the horizontal and vertical directions corresponding to the focus detection direction. The number may be determined. For example, in the case of auxiliary light having a vertical light / dark difference as shown in FIG. 8A, the signal for performing focus detection with the contrast in the horizontal direction increases the number of additions, and the focus detection is performed with the contrast in the vertical direction. It is conceivable that the number of additions is reduced in the signal for performing.

  Note that, as described above, the contrast of the optical image formed by the auxiliary light varies depending on the distance of the subject to be projected and the reflectance. Further, the distance at which the optical image is formed on the subject varies depending on the optical system that projects the auxiliary light. Therefore, the focus detection signal addition process may be changed according to the distance of the subject and the brightness of the auxiliary light. By doing so, more accurate focus detection can be realized. Also, when the subject is near or the subject's reflectance is high, the number of row additions is reduced when the contrast difference of the focus detection signal is sufficient compared to when the contrast is insufficient. Can be considered.

  Note that, when the imaging distance of the designed optical image of the auxiliary light is close to the distance of the subject, it is assumed that a steep contrast change can be acquired as a focus detection signal at the boundary of the contrast of the optical image. In such a case, it can be considered to increase the number of row additions of the focus detection signal. The camera MPU 125 calculates and determines the subject distance from the defocus amount obtained by focus detection and the position of the focus lens. That is, in the case where the optical pattern is irradiated, the camera MPU 125 determines that the signal distance between the determined subject distance and the image formation distance in the design of the optical pattern does not match as compared with the case where both match. Control is performed to reduce the number of signals added in the addition direction.

(Other embodiments)
The present invention is also realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, etc.) of the system or apparatus reads the program code. It is a process to be executed. In this case, the program and the storage medium storing the program constitute the present invention.

  Although the present invention has been described in detail based on preferred embodiments thereof, the present invention is not limited to these specific embodiments, and various forms within the scope of the present invention are also included in the present invention. included.

125 camera MPU
129 Phase difference AF unit 200 Auxiliary light emitting unit

Claims (8)

Obtaining means for obtaining a plurality of signals corresponding to different positions in the first direction on the image sensor, corresponding to the light flux passing through the imaging optical system;
Adding means for adding the signals acquired by the acquiring means in the first direction;
Detecting means for detecting a focal point based on the signal added by the adding means;
An irradiating means for irradiating an object with an optical pattern having a boundary between light and darkness substantially parallel to the first direction when assisting focus detection;
In the region where the boundary between the light and dark differences due to the optical pattern is generated in the first direction due to the irradiation of the optical pattern, when the optical pattern is irradiated by the irradiation means, An image pickup apparatus comprising: control means for controlling to increase the number of additions of the signal in the first direction by the addition means as compared with a case where irradiation is not performed. The acquisition means acquires, as the signal, a first signal and a second signal corresponding to light beams that pass through different pupil regions of the imaging optical system,
The adding means adds the first and second signals acquired by the acquiring means in the first direction,
Furthermore, it has a calculation means for calculating a correlation amount between the first signal after addition by the addition means and the second signal after addition,
The detection means determines a phase difference in a second direction substantially orthogonal to the first direction based on the correlation amount calculated by the calculation means, detects a focus based on the determined phase difference,
In the region where the boundary between the brightness and the darkness difference occurs, the control means is more effective when the optical pattern is irradiated by the irradiation means than when the optical pattern is not irradiated. The imaging apparatus according to claim 1, wherein control is performed so as to increase the number of additions of the first and second signals in the first direction. The detection means adds the correlation amount in the first direction, determines the phase difference based on the correlation amount after the addition,
In the region where the boundary between the light and dark differences is generated, the control unit is configured such that when the irradiation of the optical pattern is performed by the irradiation unit, the detection unit performs the irradiation of the optical pattern. The imaging apparatus according to claim 2, wherein control is performed so as to reduce the number of additions of the correlation amount in the first direction.   In the case where the optical pattern is irradiated by the irradiation unit, the control unit is configured such that, in the region where the boundary of the brightness difference is generated, compared with the region where the boundary of the brightness difference is not generated, The imaging apparatus according to claim 1, wherein control is performed so as to increase the number of additions of the signal in one direction. Means for determining a subject distance based on the focus detected by the detection means;
In the case where the optical pattern is irradiated by the irradiating unit, the control unit is configured such that both of the determined subject distance and the design imaging distance of the optical pattern by the irradiating unit do not match. 5. The image pickup apparatus according to claim 1, wherein control is performed such that the number of additions of the signal in the first direction by the addition unit is reduced as compared with a case where they match.   The imaging apparatus according to claim 1, wherein the optical pattern includes a plurality of lines substantially parallel to the first direction. When assisting focus detection, a method for controlling an imaging apparatus including an irradiation device that irradiates a subject with an optical pattern having a boundary between light and darkness substantially parallel to a first direction,
Obtaining a plurality of signals corresponding to different positions in the first direction on the image sensor, corresponding to the light beam passing through the imaging optical system;
Adding the acquired signals in the first direction;
Detecting a focus based on the summed signal;
In the region where the boundary between the light and dark differences due to the optical pattern is generated in the first direction due to the irradiation of the optical pattern, when the optical pattern is irradiated by the irradiation device, the optical pattern A control method for an imaging apparatus, wherein control is performed so that the number of additions of the signal in the first direction is increased as compared with a case where irradiation is not performed. A program for causing a computer to execute the control method for an imaging apparatus according to claim 7.

Images