JP2012128343A - Camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve focusing accuracy of a camera.SOLUTION: The camera comprises: selection means 101 configured to select an arbitrary focus detection area from a plurality of focus detection areas within a photographic image plane; focus detection means 108 arranged in each of the plurality of focus detection areas, having sensor lines including a plurality of light receiving sensors arranged at a plurality of different positions in the focus detection areas, and configured to detect a focus adjustment state of a photographic optical system based on a phase difference of an image obtained from the sensor line corresponding to the focus detection area selected by the selection means 101; scene recognition means 102 configured to recognize a photographic scene based on image information on an imaging sensor 229; and control means 101 configured to select a sensor used for phase difference detection from the plurality of positional sensor lines corresponding the focus detection area selected by the selection means 101 and to control the focus detection means 108 so as to detect the focus adjustment state by using a signal from the selected light receiving sensor.

Description

  The present invention relates to a camera.

  A so-called image sensor phase difference AF (autofocus) technique for detecting a focus adjustment state based on a signal from a focus detection pixel array arranged in the image sensor is known (see Patent Document 1). The focus detection pixel column has a predetermined position and length.

JP 2007-279212 A

  In the prior art, focus detection calculation is performed using signals from all the pixels in the length direction of the focus detection pixel row. Therefore, if signals from pixels that do not receive the light flux from the main subject are included, focusing accuracy is included. There was a problem that could not be raised.

  A camera according to the present invention is arranged in each of a plurality of focus detection areas, a selection unit that selects an arbitrary focus detection area from a plurality of focus detection areas provided in association with a plurality of areas in a shooting screen, respectively. And a sensor array including a plurality of light receiving sensors disposed at a plurality of different positions in each focus detection area, and the phase difference of an image due to a pair of pupil-divided light beams is selected by a selection unit. Based on the image information acquired by the focus detection means that detects using the sensor array corresponding to the selected focus detection area and detects the focus adjustment state of the imaging optical system based on the phase difference, Used for phase difference detection from a plurality of sensor rows at a plurality of positions corresponding to the focus detection area selected by the selection means based on the scene recognition means for recognizing the photographic scene and the recognition result by the scene recognition means Select the light receiving sensor location, characterized in that it comprises a control means for controlling the focus detection means to detect the focusing state using a signal from the selected light-receiving sensor.

  In the camera according to the present invention, the focusing accuracy can be increased.

It is a figure explaining the principal part structure of the single-lens reflex electronic camera carrying the focus detection apparatus by one embodiment of this invention. It is a figure explaining the principal part structure of the single-lens reflex electronic camera carrying the focus detection apparatus by one embodiment of this invention. It is a figure which illustrates the external appearance of an electronic camera. It is a block diagram explaining the structure of an electronic camera. It is a front view which shows the detailed structure of an image pick-up element. It is sectional drawing to which only the pixel for imaging was expanded. It is sectional drawing to which only the pixel for focus detection was expanded. It is a figure explaining the pupil division type phase difference detection method by image sensor AF. It is a figure which illustrates arrangement | positioning of nine ranging areas. It is a figure explaining a scene recognition area. It is the figure which showed the ranging area and the scene recognition area in an overlapping manner. It is a figure explaining the example which image | photographs a person. It is a figure which shows a ranging area, the block which comprises this ranging area, and a corresponding scene recognition area. It is a flowchart explaining the flow of the process which determines the data used for a defocus amount calculation.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 and FIG. 2 are diagrams for explaining the main configuration of a single-lens reflex electronic camera equipped with a focus detection device according to an embodiment of the present invention. 1 and 2, a photographic lens barrel 202 that is detachably attached to the camera body 201 is attached.

  Light from the subject enters the camera body 201 through the photographing optical system 210 and the diaphragm 211 of the photographing lens barrel 202. The subject light incident on the camera body 201 is bent toward the upper finder by a transflective quick return mirror (hereinafter referred to as a mirror) 203 in the mirror-down state illustrated in FIG. To form an image. Further, the subject light transmitted through the mirror 203 is guided to the image sensor 212 and forms a subject image on the imaging surface. The image sensor 212 is configured by a CMOS image sensor or the like provided with a plurality of photoelectric conversion elements corresponding to pixels.

  The subject light imaged on the diffusion screen 206 is further incident on the pentaprism 221. The pentaprism 221 guides incident subject light to the eyepiece optical system 223. The photographer observes the subject image through the viewfinder through the eyepiece optical system 223 from the viewfinder eyepiece window 41 (FIG. 3).

  Part of the subject light incident on the pentaprism 221 is bent upward by the prism 25 and forms a subject image on the imaging surface of the scene recognition sensor 229 via the lens 227. The scene recognition sensor 229 is configured by a CMOS image sensor having a plurality of photoelectric conversion elements corresponding to pixels. The number of pixels of the scene recognition sensor 229 is smaller than the number of pixels of the image sensor 212. Thereby, the resolution of the image acquired by the scene recognition sensor 229 is lower than the resolution of the image acquired by the image sensor 212.

  After the release, the mirror 203 is rotated to the mirror-up position illustrated in FIG. 2, and all subject light is guided to the image sensor 212 via the mechanical shutter 205, and forms a subject image on the imaging surface. The image sensor 212 captures a subject image formed on the imaging surface, and outputs a photoelectric conversion signal corresponding to the brightness of the subject image. An optical low-pass filter 213 is provided on the imaging surface side of the imaging element 212.

  The lens driving mechanism 214 drives the focus adjustment lens constituting the photographing optical system 210 to advance and retract in the optical axis direction. The drive direction and drive amount of the focus adjustment lens are instructed from the camera body 201 side. In order to simplify the drawing, the photographing optical system 210 is represented as a single lens.

  The mirror-down state in FIG. 1 is a shooting preparation state in which the photographer can observe the subject image via the eyepiece optical system 223. The mirror-up state in FIG. 2 is a state at the time of photographing in which all subject light is guided to the image sensor 212. In the present embodiment, focus detection (referred to as image sensor phase difference AF) is possible based on an output signal from the image sensor 212 in both the mirror down state and the mirror up state.

  FIG. 3 is a diagram illustrating an appearance of the electronic camera. In FIG. 3, a main switch SW1, a release button SW2, and a monochrome liquid crystal monitor 31 are provided on the upper surface of the electronic camera. On the back of the electronic camera, a cancel switch SW3, a mode switch SW4, a left selection switch SW5, a right selection switch SW6, an upper selection switch SW7, a lower selection switch SW8, a confirmation switch SW9, and a deletion switch SW10, A command dial 45, a color liquid crystal monitor 61, and a viewfinder eyepiece window 41 are provided.

  FIG. 4 is a block diagram illustrating the configuration of the electronic camera described above. The electronic camera is controlled by the microcomputer 101. The main switch SW1 outputs an operation signal for instructing power on / off of the electronic camera. The release switch outputs a signal instructing to start shooting in conjunction with the pressing operation of the release button SW2.

  The cancel switch SW3 outputs an operation signal indicating operation cancellation. The mode switch SW4 outputs an operation signal for switching the operation mode of the electronic camera, that is, the photographing mode and the reproduction mode.

  The left selection switch SW5, right selection switch SW6, upper selection switch SW7, and lower selection switch SW8 each output an operation signal indicating the selection direction. The confirmation switch SW9 outputs an operation signal indicating operation confirmation. The deletion switch SW10 outputs an operation signal indicating a deletion instruction. The switch SW11 and the switch SW12 output an operation signal according to the rotation operation of the command dial 45.

  The lens barrel 202 includes a CPU in the lens barrel, and communicates with the microcomputer 101. The CPU in the lens barrel drives and controls the lens driving mechanism 214 (FIGS. 1 and 2) in accordance with an instruction from the microcomputer 101, and moves the focus adjustment lens (210) forward and backward.

  The imaging processing circuit 107 performs predetermined image processing on the image data output from the imaging element 212. Image processing includes γ conversion processing and white balance adjustment processing.

  The image sensor AF circuit 108 performs an image shift detection calculation process (correlation process, phase difference detection process) based on an output signal from a predetermined pixel of the image sensor 212, so-called pupil division type phase difference detection method (micro lens). Method) to detect an image shift amount of a pair of images. Further, the deviation (defocus amount) of the current image plane with respect to the planned focal plane is calculated by multiplying the image shift amount by a predetermined conversion coefficient. Then, the movement direction and movement amount of the focus adjustment lens are calculated according to the defocus amount. Details of the image shift detection calculation process will be described later.

  The photometric calculation circuit 109 performs photometric calculation based on the pixel output signal from the scene recognition sensor 229. The scene recognition processing unit 102 detects luminance and color for each scene recognition area based on a pixel output signal for each predetermined area (referred to as a scene recognition area) of the scene recognition sensor 229. For example, the luminance is obtained from the signal of the G color component, and the color is detected from the signal ratio of the R color component and the B color component.

  The driver circuit 103 drives the mechanical shutter 205 in response to a command from the microcomputer 101. The driver circuit 104 drives the aperture mechanism 214 in response to a command from the microcomputer 101. When the diaphragm mechanism 214 moves a diaphragm drive lever (not shown), the aperture of the diaphragm 211 on the lens barrel 202 side changes. The driver circuit 105 drives the mirror mechanism 215 in response to a command from the microcomputer 101. The mirror mechanism 215 drives the mirror 203 up or down.

  The external interface 113 is an interface circuit that outputs (transmits) data in the electronic camera to an external device such as a personal computer or another electronic camera, and inputs (receives) data from the external device. Examples of the external interface 113 include RS232C, USB, and IEEE1394.

  The display control unit 110 generates a drive signal for the color liquid crystal monitor 61 according to a command from the microcomputer 101. The color liquid crystal monitor 61 displays images and operation menus. The display control unit 111 generates a drive signal for the monochrome liquid crystal monitor 31 according to a command from the microcomputer 101. The monochrome liquid crystal monitor 31 displays shooting information such as the number of frames and shooting conditions.

  The memory card 119 is a recording medium that can be attached to and detached from the electronic camera via the card connector 117. Image data and audio data are recorded in the memory card 119. The driver circuit 106 drives and controls the ranging area irradiation device 115 in accordance with a command from the microcomputer 101. The distance measurement area irradiation device 115 emits distance measurement auxiliary light to illuminate the subject when necessary at the time of imaging element phase difference AF.

  The image storage memory 121 temporarily stores image data during the above-described image processing, compression processing and decompression processing described later. The compression / decompression circuit 123 compresses the image data by a predetermined method such as JPEG, or decompresses the compressed image data. The memory 125 is used as a work area for the microcomputer 101. The timer 127 measures the time designated by the microcomputer 101 and outputs a time-up signal. The battery 129 supplies power to each unit in the electronic camera.

<Image sensor phase difference AF processing>
An AF (automatic focus adjustment) process performed by the image sensor AF circuit 108 will be described in detail. The image sensor 212 of the present embodiment has focus detection pixels (referred to as focus detection pixels). The image sensor 212 is the same as the image sensor described in Japanese Patent Application Laid-Open No. 2007-279312. The image sensor AF circuit 108 performs focus detection processing by performing phase difference detection calculation using pixel output data from the focus detection pixels.

  FIG. 5 is a front view showing a detailed configuration of the image sensor 212. In the imaging element 212, imaging pixels 310 are two-dimensionally arranged. In addition, focus detection pixels 311 are arranged in a portion corresponding to a distance measurement area described later. In the example of FIG. 5, focus detection pixel rows are arranged in the horizontal direction substantially at the center of the imaging surface. FIG. 6 is an enlarged cross-sectional view of only the imaging pixels, and FIG. 7 is an enlarged cross-sectional view of only the focus detection pixels.

  In FIG. 6, the imaging pixel 310 includes a microlens 10 and an imaging photoelectric conversion unit 11. The microlens 10 is disposed in front of the photoelectric conversion unit 11 (on the left side in FIG. 6), and the photoelectric conversion unit 11 is formed on a semiconductor circuit substrate (not shown) in the image sensor 212.

  In FIG. 7, the focus detection pixel 311 includes a microlens 10 and a pair of photoelectric conversion units 12 and photoelectric conversion units 13 for focus detection. The photoelectric conversion units 12 and 13 are arranged symmetrically with respect to the center of the microlens 10. The microlens 10 is disposed in front of the photoelectric conversion units 12 and 13 (on the left side in FIG. 7), and the photoelectric conversion units 12 and 13 are formed on the same semiconductor circuit substrate as the photoelectric conversion unit 11 of the imaging pixel 310. The microlens 10 is disposed in the vicinity of the focal plane of the photographic optical system 210.

  FIG. 8 is a diagram for explaining a pupil division type phase difference detection method using the image sensor AF. A part of the focus detection pixel 311 (microlenses 50 and 60 and two pairs of photoelectric conversion units 52, 53, 62, and 63). ). The exit pupil 90 is an exit pupil that is projected at a distance d4 forward (left side in FIG. 8) from the microlenses 50 and 60 disposed at the focal plane position of the photographing optical system 210. The distance d4 is a distance determined according to the curvature and refractive index of the microlens 10 (50, 60), the distance between the microlens 10 (50, 60) and the photoelectric conversion units 12, 13, and the like. Called pupil distance.

  The optical axis 91 is the optical axis of the photographing optical system 210. The distance measurement pupil 92 is a distance measurement pupil corresponding to the microlenses 50 and 60 and the photoelectric conversion units 52 and 62, and the distance measurement pupil 93 is a distance measurement pupil corresponding to the microlenses 50 and 60 and the photoelectric conversion units 53 and 63. It is a pupil. The two pairs of focus detection subject light beams 72, 73, 82, 83 that have passed through the pair of distance measuring pupil regions 92, 93 pass through the microlenses 50, 60, respectively, and two pairs of photoelectric conversion units 52, 53, 62,. 63 is reached. In FIG. 8, a focus detection pixel 311 (microlens 50 and a pair of photoelectric conversion units 52 and 53) on the optical axis 91 and a focus detection pixel 311 (microlens 60 and a pair of photoelectric conversions) outside the optical axis 91 are shown. The conversion units 62 and 63) are schematically illustrated, but also in the other focus detection pixels 311, the focus detection light beams coming from the pair of distance measurement pupils to the micro lenses are received by the pair of photoelectric conversion units, respectively. To do. Note that the arrangement direction (horizontal direction in FIG. 5) of the focus detection pixels 311 is made to coincide with the division direction (vertical direction in FIG. 8) of the pair of distance measurement pupils.

  By having the above-described configuration, the focus detection pixels are each incident with a pupil-divided light beam as described in Japanese Patent Application Laid-Open No. 2007-279312. Specifically, the photoelectric conversion units 12 and 13 receive only light beams that have passed through one half of the microlens 10. For example, only the light flux (referred to as the A component) from the distance measuring pupil 92 enters the photoelectric conversion units 52 and 62. On the other hand, only the luminous flux (referred to as B component) from the distance measuring pupil 93 is incident on the photoelectric conversion units 53 and 63.

  As a result, the pixel output (A component data string) obtained from the photoelectric conversion units 52, 62,... Where the A component light beam is incident is an image of the light beam incident from the distance measuring pupil 92 of the photographing optical system 210. The pixel output (B component data string) obtained from the photoelectric conversion units 53, 63,... Into which the B component light beam is incident represents an image of the light beam incident from the distance measuring pupil 93.

  A pair of subject images composed of a subject image by the A component and a subject image by the B component approach each other in the so-called front pin state in which the photographing optical system 210 forms a sharp image of the subject before the planned focal plane, and conversely the planned focus. In a so-called rear pin state in which a sharp image of the subject is connected behind the surface, they move away from each other. The pair of images relatively coincide with each other in a focused state that connects a sharp image of the subject on the planned focal plane. Therefore, the focus adjustment state of the photographing optical system 210, that is, the defocus amount can be obtained by obtaining the relative positional deviation amount of the pair of images.

  The image sensor AF circuit 108 shifts the relative positional relationship between the A component data string and the B component data string, and an image shift amount (referred to as a shift amount) between the two data strings and the A component data string. And the B component data string are calculated. The calculation for obtaining the shift amount that minimizes the correlation value (the smaller the correlation value, the higher the correlation between the two data strings) is by a known phase difference detection calculation.

  The image sensor AF circuit 108 obtains the defocus amount by multiplying the shift amount that minimizes the correlation value by a predetermined coefficient. Note that the defocus amount differs for each distance measurement area. The defocus amount detection accuracy depends on the image shift amount detection pitch and the arrangement pitch of the microlenses 10. The image sensor AF circuit 108 calculates the moving direction and moving amount of the focus adjustment lens (210) based on the defocus amount.

<Range of ranging area>
A ranging area (focus detection position) set on the focal plane of the photographing optical system 210 will be described with reference to FIGS. FIG. 9 is a diagram illustrating the arrangement of the distance measurement areas 401 to 409 when nine distance measurement areas 401 to 409 are set in the region 400 corresponding to the focal plane of the photographing optical system 210. Each of the ranging areas 401 to 409 is composed of three blocks (a, b, c from the top when the ranging area is vertically long, and a, b, c from the left when the ranging area is horizontally long). Composed. The distance measuring area 401 will be described as an example. The distance measuring area 401 is composed of a block 401a, a block 401b, and a block 401c in order from the top.

  In the present embodiment, when the microcomputer 101 is in a distance measurement mode in which a user designates a distance measurement area, the operation from the left selection switch SW5, the right selection switch SW6, the upper selection switch SW7, and the lower selection switch SW8. In response to the signal, the microcomputer 101 selects any one of the ranging areas 401 to 409. Then, the microcomputer 101 determines a block to be used for the distance measurement calculation from a plurality of blocks included in the selected one distance measurement area. For example, when the ranging area 401 is selected, a block to be used for ranging calculation is determined from the blocks 401a to 401c.

  When the microcomputer 101 is in a distance measurement mode for tracking the main subject on the shooting screen, the microcomputer 101 selects any one of the distance measurement areas 401 to 409 according to the position of the tracking target. Then, the microcomputer 101 determines a block to be used for the distance measurement calculation from a plurality of blocks included in the selected one distance measurement area. Switching between a ranging mode that accepts a ranging area designation operation by the user and a ranging mode that selects a ranging area by tracking the main subject is configured to be performed according to an operation signal from the mode switch SW4. The

  FIG. 10 is a diagram for explaining a scene recognition area which is a unit area in which the scene recognition processing unit 102 detects luminance and color (performs scene recognition). In FIG. 10, in a region 500 corresponding to the focal plane of the photographing optical system 210, for example, a total of 117 scene recognition areas 501 to 617 in 13 horizontal rows and 9 vertical rows are provided. The scene recognition processing unit 102 recognizes luminance and color representing each scene recognition area based on signals from pixels included in each scene recognition area.

  FIG. 11 is a diagram in which the ranging area of FIG. 9 and the scene recognition area of FIG. 10 are overlapped. In this embodiment, each block constituting the distance measurement area is configured to overlap with a separate scene recognition area. As shown in FIG. 11, the unit area of the “ranging area” selected by the user operation or the tracking process is larger than the unit area of the “block” used for the ranging calculation.

  FIG. 12 is a diagram illustrating an example of photographing a person. For example, the distance measurement area 402 is selected in the distance measurement mode in which the user designates the distance measurement area. According to FIG. 12, the distance measurement area 402 includes a “face” of a person, but also includes “neck” and “chest” in addition to “face”. If the defocus amount is calculated using all the output signals from the focus detection pixels corresponding to the blocks 402a to 402c constituting the distance measuring area 402, it is difficult to accurately focus only on the “face”. is there. The reason for this will be described with reference to FIG. FIG. 13 is a diagram showing a distance measurement area 402, blocks 402a to 402c constituting the distance measurement area 402, and corresponding scene recognition areas 543, 556, and 569.

  Since the block 402a corresponds to the “face”, when the defocus amount is calculated using the output signal from the focus detection pixel corresponding to the block 402a, the defocus amount is calculated for the “face”. Further, since the block 402b corresponds to the “neck”, when the defocus amount is calculated using the output signal from the focus detection pixel corresponding to the block 402b, the defocus amount is calculated for the “neck”. Further, since the block 402c corresponds to “chest”, when the defocus amount is calculated using the output signal from the focus detection pixel corresponding to the block 402c, the defocus amount is calculated for “chest”. Accordingly, when all the output signals from the focus detection pixels corresponding to the blocks 402a to 402c are used, focusing is performed based on the average value of the three defocus amounts, so only the “face” is selected. It is difficult to focus accurately on.

  The scene recognition processing unit 102 recognizes the luminance / skin color corresponding to “face” in the scene recognition area 543, and recognizes the luminance / color of “neck” and “chest” in the scene recognition areas 556 and 569, respectively. In the example of FIGS. 12 and 13, the skin color is recognized in the scene recognition area 543, but the skin color is not recognized in the scene recognition areas 556 and 569. Therefore, since the microcomputer 101 preferentially employs the defocus amount based on the skin color area, only the output signal from the focus detection pixel corresponding to the block 402a overlapping the scene recognition area 543 in which the skin color is recognized. Is used to calculate the defocus amount. This is because in the case of portrait photography, the skin color area is likely to be the main part of the subject. Thereby, the “face” can be accurately focused. As a method for recognizing “face”, a known pattern matching method may be used.

  A flow of processing (processing for determining data used for defocus amount calculation) executed by the microcomputer 101 will be described with reference to a flowchart illustrated in FIG. For example, when the release button SW2 is half-pressed, the microcomputer 101 starts the processing shown in FIG.

  In step S101 of FIG. 14, the microcomputer 101 causes the scene recognition sensor 229 to acquire an image and proceeds to step S103. In step S103, the microcomputer 101 recognizes one selected distance measuring area and proceeds to step S104. As described above, one ranging area may be selected according to an operation signal from each of the selection switches SW5, SW6, SW7, and SW8, and may be selected according to the position of the tracking target on the shooting screen. is there.

  In step S104, the microcomputer 101 reads out an imaging signal from the pixels corresponding to the blocks a to c among the focus detection pixels included in the imaging element 212 for one selected ranging area, and proceeds to step S105. Go forward (capture distance measurement data).

  In step S105, the microcomputer 101 determines a main subject using the selected distance measurement area and analysis information (luminance, color) by the scene recognition processing unit 102, and the process proceeds to step S107. For example, when a skin color is detected in a scene recognition area that overlaps a block constituting the selected distance measurement area, the area where the skin color is detected is determined as the main subject. If the distance measurement area is selected according to the position of the tracking target on the shooting screen, the process corresponding to step S105 is performed in a known tracking process, so S105 is skipped.

  In step S107, the microcomputer 101 determines whether the block a is on (overlaps) the main subject. If the microcomputer 101 is on the main subject (for example, a skin color is detected in the scene recognition area overlapping with the block a), the microcomputer 101 makes an affirmative decision in step S107 and proceeds to step S121. If the microcomputer 101 is not on the main subject (for example, no skin color is detected in the scene recognition area overlapping with the block a), the microcomputer 101 makes an affirmative decision in step S107 and proceeds to step S109.

  In step S109, the microcomputer 101 determines whether the block b is on (overlaps) the main subject. If the microcomputer 101 is on the main subject (for example, a skin color is detected in a scene recognition area overlapping with the block b), the microcomputer 101 makes an affirmative decision in step S109 and proceeds to step S123. If the microcomputer 101 is not on the main subject (for example, no skin color is detected in the scene recognition area overlapping with the block b), the microcomputer 101 makes an affirmative determination in step S109 and proceeds to step S111.

  In step S111, the microcomputer 101 determines whether the block c is on (overlaps) the main subject. If the microcomputer 101 is on the main subject (for example, a skin color is detected in a scene recognition area overlapping with the block c), the microcomputer 101 makes an affirmative decision in step S111 and proceeds to step S125. If the microcomputer 101 is not on the main subject (for example, no skin color is detected in the scene recognition area overlapping with the block c), the microcomputer 101 makes an affirmative determination in step S111 and proceeds to step S113.

  In step S121, which proceeds when an affirmative determination is made in step S107, the microcomputer 101 converts the distance measurement data acquired from the focus detection pixels corresponding to the block a in the distance measurement area into data for calculating the defocus amount. Determine and proceed to step S109.

  In step S123, which proceeds when an affirmative determination is made in step S109, the microcomputer 101 converts the distance measurement data acquired from the focus detection pixels corresponding to the block b in the distance measurement area into data for calculating the defocus amount. Determine and proceed to step S111.

  In step S125, which proceeds when an affirmative determination is made in step S111, the microcomputer 101 converts the distance measurement data acquired from the focus detection pixels corresponding to the block c in the distance measurement area into data for calculating the defocus amount. Determine and proceed to step S113.

  In step S113, the microcomputer 101 determines the distance measurement data acquired from the focus detection pixels corresponding to any one of the block a, the block b, and the block c as data for calculating the defocus amount. Determine whether or not. If the microcomputer 101 has determined the corresponding distance measurement data as data for calculating the defocus amount, the microcomputer 101 makes an affirmative decision in step S113 and proceeds to step S117. If the microcomputer 101 has not determined the corresponding distance measurement data as the defocus amount calculation data, the microcomputer 101 makes a negative determination in step S113 and proceeds to step S115.

  In step S117, the microcomputer 101 sends an instruction to the image sensor AF circuit 108, calculates a defocus amount using the determined distance measurement data (range measurement calculation), and ends the process of FIG. When the microcomputer 101 transmits information indicating the movement direction and amount of movement of the focus adjustment lens (210) calculated by the image sensor AF circuit 108 to the CPU in the lens barrel 202, the CPU in the lens barrel 202 moves to the focus adjustment lens. (210) is moved, and a series of AF processing ends.

  In step S115, which proceeds when a negative determination is made in step S113, the microcomputer 101 performs distance measurement acquired from focus detection pixels corresponding to all blocks a, b, and c in the distance measurement area. The data is determined as defocus amount calculation data, and the process proceeds to step S117.

  When the image sensor phase difference AF is performed in the mirror down state, the light beam transmitted through the mirror 203 is captured by the image sensor 212. On the other hand, when imaging element phase difference AF is performed in the mirror-up state, a light beam that does not pass through the mirror 203 is incident on the imaging element 212. For this reason, a difference occurs in the optical path length to the image sensor 212 when the mirror is down and when the mirror is up.

  In this embodiment, in order to suppress the error due to the optical path difference, offset information is prepared based on the optical path difference calculated in advance using the thickness and the refractive index of the mirror 203, and the image sensor AF circuit 108 performs the defocusing. When the focus amount is calculated, correction is performed using the offset information.

According to the embodiment described above, the following operational effects can be obtained.
(1) The camera includes a microcomputer 101 that selects an arbitrary distance measurement area from a plurality of distance measurement areas 401 to 409 provided in association with a plurality of areas in the shooting screen, and a plurality of distance measurement areas 401, respectively. Focus detection pixel arrays including a plurality of focus detection pixels 311 disposed in each of the plurality of blocks a, b, and c in each of the distance measurement areas 401 to 409. And detecting a phase difference of an image by a pair of luminous fluxes that are divided into pupils using focus detection pixel rows corresponding to the ranging areas 401 to 409 selected by the microcomputer 101, and based on the phase difference. Based on image information acquired by the image sensor AF circuit 108 and the image sensor 212 for detecting the focus adjustment state of the photographing optical system 210 and the scene recognition sensor 229, A scene recognition processing unit 102 for recognizing a scene, and a plurality of blocks a of a pixel row for focus detection corresponding to the ranging areas 401 to 409 selected by the microcomputer 101 based on a recognition result by the scene recognition processing unit 102; The focus detection pixel 311 of the block used for phase difference detection is selected from the focus detection pixel rows b and c, and the focus adjustment state is detected using the signal from the selected focus detection pixel 311. And the microcomputer 101 for controlling the image sensor AF circuit 108 and the image sensor 212.

  According to the above configuration, each of the ranging areas 401 to 409 includes a plurality of blocks a, b, and c, and arbitrary selection is performed in units of the ranging area, and the focus detection pixel 311 used for the phase difference calculation after that is selected in the scene. Further, selection is made in units of blocks based on the recognition result by the recognition processing unit 102. As a result, it is easy to select the distance measurement area because it is only necessary to roughly select the focus detection pixel 311 used for the phase difference calculation, and the focus accuracy of the camera can be improved because the selection of the focus detection pixel 311 can be performed accurately based on scene recognition. .

(2) The scene recognition processing unit 102 specifies the specific position of the main subject in the distance measurement area selected by the microcomputer 101, and the microcomputer 101 detects the focus detection pixel arrays of the plurality of blocks a, b, and c. Since the focus detection pixels of the block corresponding to the specific position are selected for phase difference detection, the focus detection pixels 311 used for the phase difference calculation can be selected with high accuracy.

(3) The scene recognition processing unit 102 specifies a specific position having a predetermined color in the distance measurement area selected by the microcomputer 101, and the microcomputer 101 detects focus detection pixels of a plurality of blocks a, b, and c. Since the focus detection pixel of the block corresponding to the specific position is selected for phase difference detection from the column, the focus detection pixel 311 used for the phase difference calculation can be selected with high accuracy.

(4) When the specific position is not specified by the scene recognition processing unit 102, the microcomputer 101 detects the focus of a plurality of blocks a, b, and c corresponding to the distance measurement area selected by the microcomputer 101. Since the focus detection pixels constituting the pixel row are selected for phase difference detection, the distance measurement area can be widely used.

(5) Since the focus detection pixel array is partially included as the focus detection pixel array in the imaging image sensor 212, the focus detection sensor having the focus detection pixel array is included in the imaging image sensor. Compared with the case where it is provided separately, the camera can have a simple configuration.

(6) Since the size of the ranging areas 401 to 409 is configured to be larger than the size of the minimum light receiving area of the scene recognition sensor 229 that acquires image information used for scene recognition, the focus detection pixel 311 used for the phase difference calculation is selected. It can be done accurately based on scene recognition.

(Modification 1)
In the above description, the case where the image sensor phase difference AF is performed has been described as an example. However, the present invention can also be applied to a case where a light receiving element that receives a light beam for phase difference detection is provided in addition to the imaging element 212 for photographing. .

(Modification 2)
In the above embodiment, an example has been described in which one of the plurality of blocks a, b, and c constituting the ranging areas 401 to 409 overlaps with one scene recognition area. Instead, the size of the scene recognition area may be further finely configured so that one of the blocks a, b, and c overlaps with a plurality of scene recognition areas. In this case, the microcomputer 101 has a case where most of a plurality of scene recognition areas overlapping a certain block overlap with a main part of a subject (for example, skin color is detected in 70% or more of the plurality of scene recognition areas). In addition, the distance measurement data fetched from the focus detection pixel 311 corresponding to the block is determined as data for defocus amount calculation.

(Modification 3)
Moreover, you may provide a ranging area smaller than the ranging areas 401-409 illustrated by the said embodiment. However, the size of the scene recognition area is also reduced in accordance with the size of the distance measurement area so that one of a plurality of blocks a, b, and c constituting the distance measurement area overlaps at least one scene recognition area. Keep this in mind.

(Modification 4)
A subject image is picked up by a scene recognition sensor 229 provided in the viewfinder section, and brightness and color are detected for each scene recognition area based on a pixel output signal from the scene recognition sensor 229. In addition, a subject image may be picked up by the image pickup device 212, and the luminance and color in each scene recognition area may be detected based on the pixel output signal from the image pickup device 212.

(Modification 5)
The present invention may be configured to be applied only when a stationary subject or a subject moving within the shooting screen moves slowly. Whether or not the subject is stationary is determined by whether or not there is a change in luminance and color detected in each scene recognition area every predetermined time. In addition, whether or not the movement of the subject is slower than a predetermined speed depends on whether the same color and the distance on the photographing screen where the luminance is detected (the same color) when the luminance and color are detected in each scene recognition area every predetermined time. And the interval of the scene recognition area where the luminance is detected).

  The microcomputer 101 in a case where a moving object whose moving speed of the subject is faster than a predetermined speed is to be detected is fetched from the focus detection pixels 311 corresponding to all of the blocks a, b, and c in the ranging area. The measured distance data is determined as defocus amount calculation data. When the subject moves faster than the scene recognition processing speed, even if one of the blocks a, b, and c in the selected distance measurement area is selected, it moves to another block at the next moment There is a high possibility that In such a case, it is preferable to use a wide ranging area by using all the blocks a to c.

(Modification 6)
For the reason described in the fifth modification, the present invention may be applied only when the shooting mode is a mode other than the sport mode. When the shooting mode is the sport mode, the microcomputer 101 defocuses the distance measurement data acquired from the focus detection pixels 311 corresponding to all blocks a, b, and c in the distance measurement area. It is determined as the calculation data. In the sports mode in which there is a high possibility that the shooting target moves faster than the scene recognition processing speed, even if one of the blocks a, b, and c in the selected ranging area is selected, the next There is a high possibility of moving to another block at the moment. In such a case, it is preferable to use the distance measuring area widely by using all the blocks a to c in the selected distance measuring area.

(Modification 7)
In addition to the modified example 6, in the case of a sports mode in which there is a high possibility that the shooting target moves faster than the scene recognition processing speed, not only the block a, the block b, and the block c in the selected ranging area Further, distance measurement data captured from focus detection pixels corresponding to blocks in the adjacent distance measurement area may be determined as defocus amount calculation data. An accurate distance measurement calculation can be performed by performing a distance measurement calculation including a block in an adjacent distance measurement area.

  The above description is merely an example, and is not limited to the configuration of the above embodiment.

DESCRIPTION OF SYMBOLS 101 ... Microcomputer 108 ... Image pick-up element AF circuit 109 ... Photometry calculating circuit 201 ... Camera body 202 ... Lens barrel 203 ... Main mirror 205 ... Mechanical shutter 210 ... Shooting optical system 212 ... Image pick-up element 229 ... Scene recognition sensors 401-409 ... Ranging area

Claims (8)

A selection means for selecting an arbitrary focus detection area from a plurality of focus detection areas respectively provided in association with a plurality of areas in the photographing screen;
A pair of sensor arrays including a plurality of light receiving sensors arranged in each of the plurality of focus detection areas and arranged at a plurality of different positions in each focus detection area, and divided into pupils A focus detection unit that detects a phase difference of an image due to a light beam by using the sensor array corresponding to the focus detection region selected by the selection unit, and detects a focus adjustment state of the photographing optical system based on the phase difference; ,
Scene recognition means for recognizing a photographic scene based on image information acquired by an imaging sensor;
Based on the recognition result by the scene recognition unit, the light receiving sensor at the position used for the phase difference detection is selected from the sensor rows at the plurality of positions corresponding to the focus detection region selected by the selection unit, and the selection is performed. Control means for controlling the focus detection means to detect the focus adjustment state using a signal from the received light sensor;
A camera comprising: The camera of claim 1,
The camera according to claim 1, wherein the image sensor is a photographing image sensor. The camera according to claim 1 or 2,
The scene recognizing unit identifies a specific position of the main subject within the focus detection area selected by the selecting unit;
The control means selects a light receiving sensor at a position corresponding to the specific position from among the sensor rows at the plurality of positions for detecting the phase difference. The camera according to claim 1 or 2,
The scene recognizing unit identifies a specific position having a predetermined color in the focus detection area selected by the selecting unit,
The control means selects a light receiving sensor at a position corresponding to the specific position from among the sensor rows at the plurality of positions for detecting the phase difference. The camera according to claim 3 or 4,
When the specific position is not specified by the scene recognizing unit, the control unit selects all the light receiving sensors that constitute the sensor rows at the plurality of positions corresponding to the focus detection area selected by the selecting unit. A camera that is selected for phase difference detection. In the camera according to any one of claims 1 to 5,
The camera, wherein the sensor array is partially included as a focus detection pixel array in a photographing image sensor. In the camera according to any one of claims 1 to 5,
The camera, wherein the plurality of sensor arrays are configured separately from the imaging element for photographing. In the camera according to any one of claims 1 to 7,
The size of the focus detection area is larger than the size of the minimum light receiving area of an image sensor that acquires image information used for the scene recognition.

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