JP2016224207A - Imaging device and focus adjustment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging device, focus detection method, program and program recording medium that enable a selective use of an image pick-up element acquiring an image signal and implementing phase difference method focus detection in accordance with a degree of defocus.SOLUTION: An image pick-up element 102 and image pick-up element 103 (or an image pick-up element 104) each acquiring an image signal for displaying or recording, and enabling an acquisition of a signal for implementing a phase difference method focus detection are configured to receive one light flux of a light flux and other light flux of the light flux passing through an imaging lens and divided by a main mirror 101, respectively. In the second image pick-up element, an area of a pair of pupil regions on an exit pupil through which light to be received by a pair of photoelectric conversion units of a pixel unit passes is small when compared with that of a pair of pupil regions in the first image pick-up element. A camera CPU 107 is configured to select any of the image pick-up element 102 and image pick-up element 103 (or the image pick-up element 104) for use in focus adjustments in accordance with a result of determination of a degree of defocus of a subject by the camera CPU 107.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an imaging apparatus capable of focus adjustment.

  2. Description of the Related Art In recent years, an imaging apparatus such as an interchangeable lens camera is known that has a plurality of imaging elements that acquire an image signal for display or recording and perform phase difference type focus detection. The imaging device of Patent Document 1 has two imaging elements used for generating an image. Depending on whether a moving image is shot or a still image is shot, which image sensor is used to generate an image is properly used. It is disclosed that when an image is to be generated with one image sensor, focus detection is performed using the other image sensor.

Japanese Patent Laying-Open No. 2015-034917

  However, since Patent Document 1 does not take into consideration the difference in focus detection performance of each image sensor, only an image sensor that is not used for image generation is used for focus detection regardless of the degree of defocus. Therefore, the focus detection accuracy may decrease depending on the degree of defocus.

  The present invention relates to an image pickup apparatus, a focus adjustment method, a program, and an image pickup apparatus capable of suppressing a decrease in focus detection accuracy due to the degree of defocusing for two image pickup elements that acquire an image signal for display or recording and perform focus detection. And a storage medium.

  The present invention provides an image pickup apparatus having first and second image pickup elements, each of which obtains an image signal for display or recording, and a signal for performing phase difference type focus detection. A first light beam splitting unit configured to split a light beam that has passed through the photographing lens into a plurality of light beam; and a first determination unit that determines a degree of defocus, and the first light beam that receives one of the split light beams. Each of the plurality of pixel portions included in each of the image sensor and the second image sensor that receives the other light flux has a pair of photoelectric conversion portions per pixel portion, and the light flux received by the pair of photoelectric conversion portions. The areas of a pair of pupil regions, which are regions of the photographing lens through which each passes, differ between the first image sensor and the second image sensor, and according to the determination result of the first determination means, The control means is the first photographing. A signal obtained from the elements, characterized by being configured to have a control means for controlling either the use in focus adjustment of the signal acquired from the second image sensor.

  According to the present invention, it is possible to suppress a decrease in focus detection accuracy due to the degree of defocus.

Schematic diagram of interchangeable lens camera Structure diagram of pixel portion included in imaging element 102 and imaging element 103 The figure which shows the pupil area | region corresponding to the image pick-up elements 102 and 103 Flow chart of focus detection using image sensors 102 and 103 Flow chart as a modification of FIG. The figure which shows the pupil area | region corresponding to the image pick-up element 104 Flow chart of focus detection using image sensors 102 and 104 Flow chart as a modification of FIG. The figure which showed the case where the division direction of a pupil area differs

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

[First Embodiment]
[Description of imaging device]
FIG. 1 is a schematic diagram of an interchangeable lens camera body 100 and an interchangeable lens 200 as an example of an imaging apparatus embodying the present invention. The interchangeable lens 200 has a lens group and is defined as a photographing lens 201 here. A lens having a focus function among the photographing lenses is defined as a focus lens 210.

  The light beam that has passed through the photographing lens 201 of the interchangeable lens 200 is incident on the main mirror 101 in a mirror unit (not shown) provided in the camera body 100. The main mirror 101 which is a light beam splitting unit is a half mirror in this embodiment, but may not be a half mirror as long as it can split a light beam. One of the light beams divided by the main mirror 101 passes through the main mirror 101 and is guided to the image sensor 102 as the first image sensor. The other of the light beams divided by the main mirror 101 is reflected by the main mirror 101 and guided to the image sensor 103 as the second image sensor. In general, with respect to the main mirror 101 which is a half mirror, it is known that the image quality of an image formed by the transmitted light on the image sensor is better than the reflected light sensitively influenced by the accuracy of the mirror surface. In this embodiment, the image sensor 102 that receives transmitted light is used for imaging as well as focus detection, and the image sensor 103 that receives reflected light is mainly used for focus detection. However, this may be a form in which imaging is performed using the imaging element 103, the positions of the imaging element 102 and the imaging element 103 are switched, and imaging is performed with reflected light. The focus detection is to detect a focus state, in other words, to detect how much the focus is in agreement.

  The image sensor 102 and the image sensor 103 made of CMOS area sensors have pixel portions arranged in a matrix that converts a subject image into an electric signal. The plurality of pixel portions included in each of the image sensor 102 and the image sensor 103 can acquire both a focus detection signal and an image signal for recording or display. The structure of the pixel portion will be described later. The image signal converted into the electrical signal is subjected to image processing, correction processing, and conversion processing into a recorded image by the camera CPU 107. The display image and various setting states of the camera main body 100 are displayed on the external display unit 109 which is an external monitor configured by an LCD (liquid crystal display) or a finder internal display unit 106 described later. In the finder unit 110, a backlight (not shown) configured by LEDs and a finder internal display unit 106 configured by a TFT liquid crystal display are combined with the eyepiece unit 105. A display image converted by the image sensor 102 is displayed on the finder internal display unit 106 to display a finder (EVF). At the time of shooting, imaging information processed by the correction processing unit 107a including an image correction processing unit inside the camera CPU 107 is recorded in a recording device 108 including an internal memory or an external memory card.

  In the present embodiment, focus detection (autofocus, AF) is performed by using the focus detection signals of the image sensor 102 and the image sensor 103. A focus detection calculation unit 107b in the camera CPU 107 acquires signals output from the image sensor 102 and the image sensor 103, and calculates a defocus amount. Based on the defocus amount, the camera CPU 107 calculates a value corresponding to the lens drive amount for moving the focus lens 210 to a position where the focus lens 210 is in focus. The lens driving amount is transmitted to the lens CPU 203 through the lens communication unit 204. However, the lens CPU 203 may calculate the value corresponding to the lens driving amount based on the defocus amount obtained by the focus detection calculation unit 107b. In this case, the lens CPU 203 receives the defocus amount from the camera CPU 107. The lens CPU 203 controls the actuator 202 to drive the photographing lens 201 to adjust the focus.

[Pixel structure]
A structure of a plurality of pixel portions included in the imaging elements 102 and 103 will be described with reference to FIG. FIG. 2 is a cross-sectional view of several pixel units among the plurality of pixel units included in the image sensor 102.

  The pixel portion included in the imaging element 102 includes a wiring layer 302 below the microlens 301, and a pair of photoelectric conversion units 303 a and 303 b that convert received light into an electrical signal below the wiring layer 302. A light beam 304a indicates a light beam received by the photoelectric conversion unit 303a.

  When performing phase difference type focus detection, the camera CPU independently processes the output signals of the photoelectric conversion unit 303a and the photoelectric conversion unit 303b to obtain a one-to-two image, and the relative image shift between the two images. The defocus amount of the subject image on the imaging surface is calculated from the amount. When recording or displaying an image, the output signals of the photoelectric conversion unit 303a and the photoelectric conversion unit 303b are added to obtain a recording or display signal.

  A pixel portion (not shown) included in the imaging element 103 also includes a pair of photoelectric conversion units 310 a and a photoelectric conversion unit 310 b as in the imaging element 102. The camera CPU performs phase difference type focus detection in the same manner as the image sensor 102 and obtains a recording or display signal.

[A pair of pupil regions in the exit pupil corresponding to the image sensor 102]
In the present embodiment, the camera CPU selectively uses the image sensors 102 and 103 to perform focus detection for focus adjustment. The focus detection characteristics and image quality of the image sensor 102 and the image sensor 103 will be described with reference to FIG.

  FIG. 3A is a diagram illustrating regions on the photographing lens corresponding to the photoelectric conversion units 303 a and 303 b of the pair of photoelectric conversion units included in the pixel unit of the image sensor 102. Through the microlens 301, the exit pupil 401 of the photographing lens 201 and the upper surfaces of the photoelectric conversion unit 303a and the photoelectric conversion unit 303b are optically substantially conjugate. The pair of photoelectric conversion units 303 a and 303 b included in the pixel unit of the image sensor 102 respectively receive a pair of light beams that have passed through the exit pupil 401 of the photographing lens 201. The photoelectric conversion unit 303a mainly receives and photoelectrically converts the light beam that has passed through the inside of the pupil region 402a in the exit pupil 401. Similarly, the photoelectric conversion unit 303b mainly receives and photoelectrically converts the light beam that has passed through the inside of the pupil region 402b in the exit pupil 401. In a plurality of pixel portions included in the image sensor 102, a pair of photoelectric conversion units included in each pixel portion receives a light beam that has passed through the inside of the corresponding pair of pupil regions 402a and 402b and formed an image on the imaging surface. To do.

[Focus Detection Characteristic of Image Sensor 102]
The pupil region 402a and the pupil region 402b of the image sensor 102 have a larger area than the pupil region 502a and the pupil region 502b of the image sensor 103, respectively. That is, the pixel portion of the image sensor 102 can capture more light. For this reason, when the image sensor 102 is used for focus detection, the focus detection accuracy is high when the subject is in a low luminance state compared to when the image sensor 103 is used for focus detection. On the other hand, the larger the pair of pupil regions, the more easily the focus detection signal waveform is blurred when the degree of defocus is large. Therefore, when the image sensor 102 is used, when the image sensor 103 is used for focus detection, the defocus amount is not less than the first predetermined value, that is, the degree of defocus is not large defocus. The focus detection accuracy under the circumstances is inferior. In addition, the area of each of the pair of pupil regions 402 a and the pupil region 402 b of the image sensor 102 is larger than the area of the pair of pupil regions in the image sensor 103. Accordingly, a wider range of the exit pupil 401 can be covered by the pair of pupil regions 402a and 402b of the image sensor 102 than in the case of the image sensor 103. In other words, a wider area of light can be captured. From this, when the signals of the photoelectric conversion units 303a and 303b corresponding to the pair of pupil regions 402a and 402b are added, an image signal with higher image quality can be acquired. The baseline length, which is the distance between the centroids of the pupil region 402a and the pupil region 402b, is shorter than the pupil region 502a and the pupil region 502b of the pixel portion of the image sensor 103.

[A pair of pupil regions in the exit pupil corresponding to the image sensor 103]
FIG. 3B is a diagram illustrating regions on the photographing lens corresponding to the photoelectric conversion units 310 a and 310 b (not shown) of the pair of photoelectric conversion units included in the pixel unit of the image sensor 103. Via the micro lens 311 (not shown), the exit pupil 401 of the photographing lens 201 and the upper surfaces of the photoelectric conversion unit 310a and the photoelectric conversion unit 310b are optically substantially conjugate. The pair of photoelectric conversion units 310 a and 310 b included in the pixel unit of the image sensor 103 respectively receive a pair of light beams that have passed through the exit pupil 401 of the photographing lens 201. The photoelectric conversion unit 310a mainly receives light that has passed through the inside of the pupil region 402a in the exit pupil 401 and performs photoelectric conversion. Similarly, the photoelectric conversion unit 310b mainly receives and photoelectrically converts light that has passed through the inside of the pupil region 402b in the exit pupil 401.

  In a plurality of pixel portions included in the image sensor 103, a pair of photoelectric conversion units included in each pixel portion receives a light beam that has passed through the corresponding pair of pupil regions 502a and 502b and formed an image on the imaging surface. To do.

  In this embodiment, when comparing the area of the pupil region between the image sensor 102 and the image sensor 103, the areas of the pupil region 402a and the pupil region 402b are substantially equal, and the areas of the pupil region 502a and the pupil region 502b are equal. The case where it is almost equal is assumed.

  However, the area of the pair of pupil regions may differ greatly depending on the image height of the pixels, the flux of the light flux, and the like. For this reason, when comparing the areas of the pupil regions between the image sensor 102 and the image sensor 103, the total area of the pair of pupil regions may be compared between the two image sensors. That is, the total area of the pupil region 402a and the pupil region 402b of the image sensor 102 may be compared with the total area of the pupil region 502a and the pupil region 502b of the image sensor 103.

[Focus Detection Characteristics of Image Sensor 103]
The pupil area 502a and the pupil area 502b of the image sensor 103 are smaller in area than the pupil area 402a and the pupil area 402b of the image sensor 102, respectively. Thereby, even when the degree of defocus is large, the focus detection signal waveform is not easily broken. For this reason, when the image sensor 103 is used for focus detection, the focus detection accuracy is high under a large defocus condition as compared with the case where the image sensor 102 is used. On the other hand, the image sensor 103 pupil region 502 a and the pupil region 502 b have a smaller area that captures light than the pupil region 402 a and the pupil region 402 b of the image sensor 102. For this reason, when the image sensor 103 is used for focus detection, the focus detection accuracy under a situation where the subject has low luminance is inferior to the case where the image sensor 102 is used.

  In addition, since the area of each of the pupil region 502a and the pupil region 502b is smaller than that of the pupil region 402a and the pupil region 402b and the region where light can be captured is smaller, the image sensor 103 has a smaller area than the image sensor 102. Inferior in terms of image quality. The baseline length, which is the distance between the centroids of the pupil region 502a and the pupil region 502b, is longer than the baseline length of the pupil region 402a and the pupil region 402b of the pixel portion of the image sensor 103. By taking a long base line length, the resolution in focus detection is increased, so that focus detection accuracy is further improved.

  Note that the size and arrangement of the pupil regions 402a and 402b and the pupil regions 502a and 502b are the pixel units such as the photoelectric conversion units 303a and 303b, the arrangement of the photoelectric conversion units 310a and 310b, the size of the pixel units, and the shape of the microlens. It can be changed depending on the structure.

[Focus adjustment flow]
FIG. 4 shows a flowchart of focus adjustment when the image sensors 102 and 103 are used for focus detection. When the focus detection operation is started, focus detection by the image sensor 102 is performed in step S601. The focus detection signal as the focus detection result is stored in the CPU 107 and is read as appropriate in a later step.

  In subsequent step S602, focus detection by the image sensor 103 is performed. The focus detection signal as the focus detection result is stored in the CPU 107 and is read as appropriate in a later step. When the focus detection result is stored in step S602, the process proceeds to the next step S603.

  In step S603, the camera CPU 107 serving as the second determination unit determines whether or not the subject that is the target of focus detection is a low-luminance subject that may have a low focus detection accuracy when performing focus detection by the image sensor 103. Determined. Here, the determination of low luminance may be performed using the focus detection signal acquired in step S601 or step S602, or may be performed using an AE sensor provided separately. If the subject brightness is equal to or lower than the second predetermined value, the camera CPU 107 determines that the subject has low brightness, and proceeds to step S604.

  If the luminance of the subject is higher than the second predetermined value, the camera CPU 107 determines that the subject is not low luminance. When the camera CPU 107 determines that the subject does not have low brightness, the camera CPU 107 as a control unit performs control so that the signal acquired from the image sensor 103 is used for focus adjustment. That is, the process proceeds to step S609, and the lens driving amount is calculated using the focus detection result of the image sensor 103 in step S602. In subsequent step S610, the actuator 202 as the adjusting means drives the focus lens 210 based on the lens driving amount. Since the subject is not low-luminance, focus detection can be performed with high accuracy even with the image sensor 103 having a small area of a pair of pupil regions. Furthermore, since the image sensor 103 has a long base line length, focus detection can be performed with higher accuracy than the image sensor 102. Furthermore, even if the subject is largely defocused, focus detection can be performed with higher accuracy by using the image sensor 103 having a small area of a pair of pupil regions.

  In step S604, the camera CPU 107 determines whether the degree of defocus is large defocus using the focus detection result in step S602 or step 603. When the defocus amount is equal to or smaller than the first predetermined value, the camera CPU 107 as the first determination unit determines that the degree of defocus is not large defocus. In this case, in step S608, the camera CPU 107 as a control unit performs control so that a signal acquired from the image sensor 102 that can accurately detect a focus even on a low-luminance subject is used for focus adjustment. That is, the process proceeds to step S608, where the lens drive amount is calculated using the focus detection result of the image sensor 102 in step S601. In step S610, the actuator 202 as the adjusting unit drives the focus lens 210 based on the lens drive amount. .

  On the other hand, when the defocus amount is larger than the first predetermined value, the camera CPU 107 as the first determination unit determines that the degree of defocus is large defocus. In this case, the camera CPU 107 serving as a control unit performs control so that a signal acquired from the image sensor 103 that can accurately detect a focus even during large defocusing is used for focus adjustment. That is, the process proceeds to step S605, where the lens driving amount is calculated using the focus detection result of the image sensor 103 in step 602. In step S606, the actuator 202 as the adjusting unit drives the focus lens 210 based on the lens driving amount. To do. When the lens is driven, the process proceeds to step S607.

  In S607, a signal is acquired again from the image sensor 102 serving as the first image sensor, and focus detection is performed again.

  Here, the focus detection result in step S602 used when calculating the drive amount in step S605 is the focus detection result for the low-luminance subject by the image sensor 103 with high focus detection accuracy for the low-luminance subject. In order to further improve the focus detection accuracy for the low-luminance subject, in step S607, focus detection is performed again using a signal acquired from the image sensor 102 with high focus detection accuracy for the low-luminance subject. Note that, as described above, the focus detection accuracy of the image sensor 102 may be reduced during large defocus. However, since the lens is driven based on the focus detection result by the image sensor 103 in step S606, the situation of large defocus is removed, and it is possible to perform focus detection with higher accuracy.

  In step S608, the lens drive amount of the focus lens 210 for focusing is calculated using the focus detection result stored in S607. When the driving amount of the lens is calculated, the process proceeds to step S609. In step S609, the actuator 202 as the adjusting unit drives the focus lens 210 by the lens driving amount calculated in step S608.

  In the calculation of the lens driving amount in the present embodiment, correction values such as a focus shift by an individual lens and a shift of a camera individual are applied, and the driving amount is set so as to obtain an optimum focus state for each camera. Calculated.

  As described above, when performing focus detection for focus adjustment, the imaging apparatus according to the present embodiment uses a focus detection result obtained by the image sensor 103 having a long baseline length unless the subject has low luminance. This is because the imaging device 103 has higher focus detection accuracy than the baseline length of the imaging device 102 is longer than the baseline length. However, since the image sensor 103 has a smaller area of the pupil regions 502 a and 502 b than the pupil regions 402 a and 402 b of the image sensor 102, the focus detection accuracy for a low-luminance subject is inferior to that of the image sensor 102. When the luminance is low and the defocus is not large, the focus detection result by the image sensor 102 having a larger pupil area than the image sensor 103 is used. This is because the imaging element 102 has a large pupil area, and thus the focus detection accuracy may be reduced in large defocusing, but the focus detection can be accurately performed on a low-luminance subject. Further, in the case of low luminance and large defocus, the lens is driven using the focus detection result of the image sensor 103, and after the large defocus state is removed, the focus detection is accurately performed even for the low luminance subject. The focus detection result of the image sensor 102 that can be used is used.

  As described above, in the present embodiment, when performing focus detection, it is possible to appropriately use the two image pickup devices in accordance with the degree of defocus. In addition, according to the present embodiment, when performing focus detection, it is possible to properly use the two image pickup devices according to the luminance of the subject. By using the two image sensors in focus detection according to the subject brightness and the degree of defocus, the overall focus detection accuracy can be improved.

  In the present embodiment, as described above, focus detection using the image sensor 102 in step S601 and focus detection using the image sensor 103 in step S602 are performed at the beginning of the flow, and both image sensors are used. Focus detection is performed. However, focus detection may be performed using one of the image sensors first, and focus detection may be performed using the other image sensor only when necessary later.

  As an example, there is a flow as shown in FIG. In the flow of FIG. 5, focus detection is performed using a signal acquired from the image sensor 103 in the first step S701. On the other hand, when it is determined in step S703 that there is no large defocus, focus detection using a signal from the image sensor 102 is newly performed. If it is determined in step S702 that the subject is not low-luminance, the focus detection result using the image sensor 103 is also obtained in the flow of FIG. 5 as the lens driving amount in step S709 as in the flow of FIG. Used to calculate In this way, by using only the image sensor 103 for focus detection first, it is not necessary to drive the image sensor 102 and perform focus detection when the subject is not low in luminance, so that power consumption can be suppressed.

  Note that the image sensor 102 used for focus detection first may be the image sensor 102. In this case, the flow corresponding to step S707 in FIG. 5 can be omitted. As described above, by performing focus detection only with one image sensor first, it is not necessary to drive in focus detection of one image sensor depending on the brightness of the subject or the degree of defocusing, so that power consumption is suppressed. be able to.

[Second Embodiment]
Subsequently, an imaging apparatus according to the second embodiment will be described. A description of the same configuration as that of the first embodiment will be omitted, and differences will be mainly described. In the present embodiment, an image sensor 104 as a second image sensor is provided instead of the image sensor 103 in the first embodiment. The imaging apparatus according to the present embodiment selectively uses the imaging element 102 and the imaging element 104 and performs focus detection for focus adjustment.

[Pixel structure]
The image sensor 104 has a pair of photoelectric conversion units 333 a and 333 b (not shown), like the image sensor 102. The image sensor 104 performs phase difference type focus detection in the same manner as the image sensor 102 to obtain a recording or display signal.

[A pair of pupil regions in the exit pupil corresponding to the image sensor 104]
The focus detection characteristics and image quality of the image sensor 104 as the second image sensor will be described with reference to FIG. FIG. 6 is a diagram illustrating regions on the photographing lens corresponding to a pair of photoelectric conversion units 333a and 333b (not shown) included in the pixel unit of the image sensor 104.

  Through the micro lens 331 (not shown), the exit pupil 401 of the photographing lens 201 and the upper surfaces of the photoelectric conversion unit 333a and the photoelectric conversion unit 333b are optically substantially conjugate. The pair of photoelectric conversion units 333 a and 333 b included in the pixel unit of the image sensor 104 respectively receive a pair of light beams that have passed through the exit pupil 401 of the photographing lens 201. The photoelectric conversion unit 333a mainly receives and photoelectrically converts light that has passed through the inside of the pupil region 602a in the exit pupil 401. Similarly, the photoelectric conversion unit 333b mainly receives light that has passed through the inside of the pupil region 602b in the exit pupil 401 and performs photoelectric conversion. Then, in the plurality of pixel portions included in the image sensor 104, the pair of photoelectric conversion units included in each pixel unit passes through the inside of the pair of pupil regions 602a and 602b corresponding to the pair of photoelectric conversion units. The light beam imaged on the surface is received.

[Focus Detection Characteristic of Image Sensor 104]
The pupil region 602a and the pupil region 602b of the image sensor 104 are smaller in area than the pupil region 402a and the pupil region 402b of the image sensor 102, respectively. A signal acquired using light that has passed through a pupil area having a small area is larger in defocus amount than a signal acquired using light that has passed through a pupil area having a large area. Even in this case, the focus detection signal waveform is not easily broken. That is, when the image sensor 104 is used for focus detection, the focus detection accuracy in a large defocus situation is better than when the image sensor 102 is used. On the other hand, in the pupil region 602a and the pupil region 602b of the image sensor 104, the region that captures light is smaller than the pupil region 402a and the pupil region 402b of the image sensor 102. For this reason, when the image sensor 104 is used for focus detection, the focus detection accuracy in a situation where the subject has a low luminance is inferior to that when the image sensor 102 is used.

  In addition, since the areas of the pupil region 602a and the pupil region 602b are smaller than the areas of the pupil region 402a and the pupil region 402b, the area where light can be captured becomes small. Compared to the image quality. The baseline length, which is the distance between the centroids of the pupil region 602a and the pupil region 602b, is shorter than the baseline length of the pupil region 402a and the pupil region 402b of the pixel portion of the image sensor 103. Since the image sensor 102 has a longer base line length than the image sensor 104, the focus detection resolution is high, and thus the focus detection accuracy is higher.

  Note that the size and arrangement of the pupil regions 602a and 602b can be changed according to the structure of the pixel unit such as the arrangement of the photoelectric conversion unit 303, the size of the pixel unit, and the shape of the microlens 331.

  Also in this embodiment, in comparing the areas of a pair of pupil regions of the image sensor 102 and the image sensor 104, the total area of the pupil region 402a and the pupil region 402b of the image sensor 102 and the pupil region of the image sensor 104 You may compare the total area of 602a and the pupil area | region 602b.

[Focus adjustment flow]
FIG. 7 shows a flowchart in focus adjustment when the image sensors 102 and 104 are used for focus detection. When the focus detection operation is started, focus detection by the image sensor 102 is performed in step S801. The focus detection signal as the focus detection result is stored in the CPU 107 and is read as appropriate in a later step.

  In subsequent step S802, focus detection by the image sensor 104 is performed. The focus detection signal as the focus detection result is stored in the CPU 107 and is read as appropriate in a later step. When the focus detection result is stored in step S802, the process proceeds to the next step S803.

  In step S803, the camera CPU 107 determines whether the degree of defocus is large defocus using the focus detection result stored in step S801. When the defocus amount is equal to or smaller than the first predetermined value, the camera CPU 107 as the first determination unit determines that the degree of defocus is not large defocus. In this case, the camera CPU 107 serving as a control unit performs control so that a signal acquired from the image sensor 102 having a base length longer than the image sensor 103 is used for focus adjustment in step S801. There is a possibility that the focus detection accuracy of the image sensor 102 is reduced at large defocus, but if the degree of defocus is not large defocus, the focus is better when the image sensor 102 has a longer baseline length and higher focus detection accuracy. This is because the detection accuracy is high. That is, the process proceeds to step S807, the lens drive amount is calculated using the focus detection result of the image sensor 102 in step S801, and the actuator 202 as the adjusting unit drives the focus lens 210 based on the lens drive amount in step S808. .

  On the other hand, when the defocus amount is larger than the first predetermined value, the camera CPU 107 as the first determination unit determines that the degree of defocus is large defocus. In this case, the camera CPU 107 as a control unit performs control so that a signal acquired from the image sensor 103 with high focus detection accuracy is used for focus adjustment even in large defocus. That is, the process proceeds to step S804, and the lens driving amount is calculated using the focus detection result of the image sensor 104 in step 802. In subsequent step S805, the actuator 202 as the adjusting means drives the focus lens 210 based on the lens driving amount. When the lens is driven, the process proceeds to step S806.

  In a state where large defocus is removed in step S805, in step S806, a signal is acquired again from the image sensor 102 as the first image sensor, and focus detection is performed again. By performing focus detection again with the image sensor 102, even if the subject has low luminance that may cause the focus detection accuracy to be lowered in the image sensor 103, more accurate focus detection is possible. In addition, since the image sensor 102 has a longer base line length than the image sensor 103, the focus detection can be performed with higher accuracy by performing focus detection again with the image sensor 102.

  In step S807, the lens driving amount of the focus lens 210 for focusing is calculated using the focus detection signal which is the focus detection result by the image sensor 102 stored in step S806. When the driving amount of the lens is calculated, the process proceeds to step S808.

  In step S808, the actuator 202 as the adjusting unit drives the focus lens 210 by the lens driving amount calculated in step S807.

  In the calculation of the lens driving amount in the present embodiment, correction values such as a focus shift by an individual lens and a shift of a camera individual are applied, and the driving amount is set so as to obtain an optimum focus state for each camera. Calculated.

  As described above, when performing focus detection, the imaging apparatus according to the present embodiment uses a focus detection result obtained by the image sensor 102 having a long baseline length unless the determination result is large defocus. This is because the focus detection accuracy is higher because the base line length is longer than that of the image sensor 104. However, since the areas of the pupil regions 402a and 402b of the image sensor 102 are larger than the areas of the pupil regions 602a and 602b of the image sensor 104, the focus detection accuracy in large defocus may be reduced. Therefore, when the determination result is large defocus, the lens is driven using the focus detection result in the image sensor 104, and the focus detection result in the image sensor 102 having a long base line length is removed after the large defocus state is removed. Is used. First, by using the image sensor 104, the pupil regions 602a and 602b of the image sensor 104 have a smaller area than the pupil regions 402a and 402b of the image sensor 102, so that focus detection can be performed with high accuracy even in large defocus. it can. On the other hand, the image sensor 104 has a shorter base length than the image sensor 102, and the image sensor 104 is inferior in focus detection accuracy to the image sensor 102 from the viewpoint of the baseline length. Therefore, the image sensor 102 performs focus detection with higher accuracy. Thus, focus detection is performed again. As described above, in the present embodiment, when performing focus detection, it is possible to appropriately use the two image pickup devices in accordance with the degree of defocus. By using the two image sensors in focus detection according to the degree of defocusing, overall focus detection accuracy can be improved.

  In the present embodiment, focus detection is performed using both image sensors, such as focus detection using the image sensor 102 in step S801 and focus detection using the image sensor 104 in step S802 at the beginning of the flow. It is carried out. However, focus detection may be performed using one of the image sensors first, and focus detection may be performed using the other image sensor only when necessary later.

  An example is the flow shown in FIG. In the flow of FIG. 8, focus detection is performed using a signal acquired from the image sensor 102 in the first step S901. If it is determined in step S902 that the defocus amount is larger than the first predetermined value and the degree of defocus is large defocus, focus detection using a signal from the image sensor 104 is newly performed in step S903. On the other hand, when the defocus amount is equal to or smaller than the first predetermined value in step S902, it is determined that the degree of defocus is not large defocus. At this time, the lens drive amount of the focus lens 210 is calculated in step S907 using the focus detection signal from the image sensor 102, which is the focus detection result in step S901. In this way, by first performing focus detection using only the image sensor 102, if the degree of defocus is not large defocus, it is not necessary to drive the image sensor 104 to perform focus detection, thus reducing power consumption. be able to.

  Note that the image sensor 104 used for focus detection first may be the image sensor 104. In this case, the step corresponding to step S903 in FIG. 8 can be omitted. As described above, by performing focus detection only with one image sensor first, it is not necessary to drive in focus detection of one image sensor depending on the brightness of the subject or the degree of defocusing, so that power consumption is suppressed. be able to.

[Other Embodiments]
In the above-described embodiment, a pair of pupil regions are arranged in the horizontal direction as shown in FIGS. However, the division direction of the pupil region may be different. For example, as shown in FIG. 9, the pair of pupil regions may be arranged in the vertical direction. A pair of pupil regions may be arranged in the vertical direction only in one of the two imaging elements of the imaging apparatus.

  Further, in one or both of the two image sensors, the corresponding two types of pixel portions may be discretely arranged so that a pair of pupil regions are arranged in the vertical direction and the horizontal direction. In particular, it is preferable to discretely arrange the two types of pixel portions in the second imaging element (imaging element 103 or imaging element 104) that mainly performs focus detection. Thereby, two image sensors can be used properly in focus detection according to the subject while maintaining the image quality of the first image sensor (image sensor 102). A pixel unit that receives light passing through a pair of pupil regions arranged in the horizontal direction of the paper and a pixel unit that receives light passing through a pair of pupil regions arranged in the vertical direction have an imaging element. It is possible to detect the focus regardless of the contrast direction.

  In addition, a pixel portion that receives light passing through a pair of pupil regions having a long base line length in FIG. 3B is arranged near the image height 0 of the second image sensor, and a portion where the image height is high is illustrated in FIG. A pixel portion that receives light passing through a pair of pupil regions having a short baseline length of 6 may be disposed. By arranging the pixel part of the form according to the image height of the image sensor at the end of the image sensor where the exit pupil is likely to be displaced, even if the exit pupil is disposed, the AF pupil is not distracted, and higher accuracy The focus can be detected with.

  In addition, a pixel portion that receives light passing through a pair of pupil regions having a long base length in FIG. 3B, and a pixel portion that receives light passing through a pair of pupil regions having a short base length in FIG. May be discretely arranged in the image sensor. In particular, it is preferable to discretely arrange the two types of pixel portions in the second imaging element (imaging element 103 or imaging element 104) that mainly performs focus detection. Thereby, two image sensors can be used properly in focus detection according to the subject while maintaining the image quality of the first image sensor (image sensor 102). The pixel portion corresponding to the pair of pupil regions in FIG. 3B and the pixel portion corresponding to the pair of pupil regions in FIG. 6 are discretely arranged on the image sensor, thereby increasing the open F value. The focus detection accuracy is improved even in an interchangeable lens having a small exit pupil.

  In the above-described embodiment, each of the two imaging elements has a pixel unit having a pair of photoelectric conversion units, and performs phase difference type focus detection using respective signals of the pair of photoelectric conversion units. Explained. In addition, it has been described that a signal for recording or display is generated by adding signals of a pair of photoelectric conversion units. On the other hand, both or one of the two image sensors is a known image sensor having two types of pixel parts, a pixel part for acquiring a recording or display image and a pixel part for focus detection. Also good. At this time, from the viewpoint of image quality, the first image sensor may be configured so that the number of focus detection pixel portions is smaller than that of the second image sensor. Thereby, two image sensors can be used properly in focus detection according to the subject while maintaining the image quality of the first image sensor (image sensor 102).

  In addition, the present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read the program. It can also be realized by executing processing. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

DESCRIPTION OF SYMBOLS 100 Camera main body 101 Main mirror 102 1st image sensor 103 2nd image sensor 107 Camera CPU
DESCRIPTION OF SYMBOLS 201 Photographic lens 301 Micro lens 303 Photoelectric conversion part of the pixel part of the image sensor 102 310 Photoelectric conversion part of the pixel part of the image sensor 103 Exit pupil 402 Pair of pupil regions of the image sensor 102 502 Pair of pupils of the image sensor 103 region

Claims (16)

In the imaging apparatus having the first and second imaging elements, each of which obtains an image signal for display or recording, and a signal for performing phase difference type focus detection,
Light beam splitting means for splitting the light beam that has passed through the taking lens into a plurality of light beams;
First determining means for determining the degree of defocus,
The plurality of pixel units included in each of the first image sensor that receives one of the divided light beams and the second image sensor that receives the other light beam each include a pair of photoelectric conversion units. And the area of the pair of pupil regions, which are regions of the photographing lens through which the light beams received by the pair of photoelectric conversion units pass, differ between the first image sensor and the second image sensor,
Control means for controlling which of the signal acquired from the first image sensor and the signal acquired from the second image sensor is used for focus adjustment according to the determination result of the first determination unit. An imaging apparatus characterized by the above.   2. The imaging apparatus according to claim 1, wherein an area of the pair of pupil regions in the second imaging element is larger than an area of the pair of pupil regions in the first imaging element.   The imaging apparatus according to claim 2, wherein an area of the pair of pupil regions is a total area of an area of the pair of pupil regions.   The first determination unit determines a degree of defocus using a signal acquired from the first image sensor or a signal acquired from the second image sensor. 4. The imaging device according to any one of 3.   When the first determination unit determines that the defocus amount is equal to or less than a first predetermined value, the control unit controls to use the signal acquired from the first image sensor for focus adjustment. The imaging device according to any one of claims 2 to 4, wherein the imaging device is characterized in that:   When the first determination unit determines that the defocus amount is larger than the first predetermined value, the control unit controls to use a signal acquired from the second image sensor for focus detection. The imaging apparatus according to claim 5. Adjusting means for adjusting the focus in accordance with the control of the control means;
When the control unit performs control so that focus detection is performed using a signal acquired from the second image sensor and the adjustment unit performs focus adjustment, the control unit newly acquires from the first image sensor. The imaging apparatus according to claim 6, wherein focus control is performed using the processed signal. A second determination unit for determining the luminance of the subject;
When the second determination means determines that the luminance of the subject is higher than a second predetermined value, the control means controls to perform focus detection using a signal acquired from the second image sensor. The imaging apparatus according to any one of claims 2 to 7, wherein   The second determination means determines the luminance of the subject using a signal acquired from the first image sensor, a signal acquired from the second image sensor, or a signal acquired from an AE sensor. The imaging device according to claim 8.   10. The defocus amount is determined by the first determination unit when the second determination unit determines that the luminance of the subject is equal to or lower than the second predetermined value. The imaging device described in 1.   11. The imaging apparatus according to claim 1, wherein a distance between the centroids of the pair of pupil regions is different between the first and second imaging elements.   When the distance between the centroids of the pair of pupil regions in the second image sensor is larger than the distance between the centroids of the pair of pupil regions in the first image sensor, the luminance of the subject is second 12. The control unit according to claim 11, wherein when the defocus amount is greater than a predetermined value or when the defocus amount is equal to or less than a first predetermined value, the control unit controls to perform focus detection using a signal acquired from the second image sensor. Imaging device.   In the case where the distance between the centroids of the pair of pupil regions is larger than that of the second image sensor in the first image sensor, and the defocus amount is equal to or less than a first predetermined value, the control means The imaging device according to claim 11, wherein control is performed to perform focus detection using a signal acquired from the imaging element. Each is an image sensor that can acquire an image signal for display or recording and a signal for performing phase difference type focus detection, and divides the light beam that has passed through the photographing lens into a plurality of light beams. A first image sensor that receives one of the light beams split by the light beam splitting means, and a second image sensor that receives the other of the split light beams, wherein the first and second image sensors are Each of the plurality of pixel portions has a pair of photoelectric conversion portions per pixel portion, and a pair of pupil regions that are regions on the photographing lens through which light beams received by the pair of photoelectric conversion portions respectively pass. In the focus adjustment method using an imaging device having different areas in the first and second imaging elements,
A first determination step of determining the degree of defocus;
A control step for controlling which of the signal acquired from the first image sensor and the signal acquired from the second image sensor is used for focus adjustment according to the determination result in the first determination step; A focus adjustment method for an image pickup apparatus. Each is an image sensor that can acquire an image signal for display or recording and a signal for performing phase difference type focus detection, and divides the light beam that has passed through the photographing lens into a plurality of light beams. A first image sensor that receives one of the light beams split by the light beam splitting means, and a second image sensor that receives the other of the split light beams, wherein the first and second image sensors are Each of the plurality of pixel portions has a pair of photoelectric conversion portions per pixel portion, and a pair of pupil regions that are regions on the photographing lens through which light beams received by the pair of photoelectric conversion portions respectively pass. In a program for executing a focus adjustment method using an imaging device having different areas in the first and second imaging elements,
A first determination step of determining the degree of defocus;
A control step for controlling which of the signal acquired from the first image sensor and the signal acquired from the second image sensor is used for focus adjustment according to the determination result in the first determination step; A program for executing a focus adjustment method for an imaging apparatus. Each is an image sensor that can acquire an image signal for display or recording and a signal for performing phase difference type focus detection, and divides the light beam that has passed through the photographing lens into a plurality of light beams. A first image sensor that receives one of the light beams split by the light beam splitting means, and a second image sensor that receives the other of the split light beams, wherein the first and second image sensors are Each of the plurality of pixel portions has a pair of photoelectric conversion portions per pixel portion, and a pair of pupil regions that are regions on the photographing lens through which light beams received by the pair of photoelectric conversion portions respectively pass. In a computer-readable storage medium in which a program for executing a focus adjustment method using an imaging device having different areas in the first and second imaging elements is recorded,
A first determination step of determining the degree of defocus;
A control step for controlling which of the signal acquired from the first image sensor and the signal acquired from the second image sensor is used for focus adjustment according to the determination result in the first determination step; A computer-readable storage medium having recorded thereon a program for executing the focus adjustment method of the imaging apparatus.

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