JP2013015806A - Focus detector and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a focus detector capable of reducing time required for focus detection.SOLUTION: The focus detector includes: an imaging part 22 for picking up an image by an optical system and repeatedly outputting an image signal corresponding to the picked-up image at a predetermined frame rate; a pair of light-receiving sensors 22a-22j for receiving a pair of light fluxes via the optical system and repeatedly outputting a pair of light receiving signals at a cycle corresponding to the frame rate; a phase difference detection part 21 for detecting a focus state of the optical system by sequentially calculating an amount of a shift of an image plane by the optical system at multiple detection positions in the picked-up image on the basis of the pair of the light receiving signals; and a control part 21 for causing the phase difference detection part 21 to calculate a shift amount at focus detection positions where the shift amount calculation can be performed within a predetermined time determined according to the frame rate among the multiple focus detection positions and to perform focus detection on the basis of the shift amount calculated within the predetermined time under specific imaging conditions.

Description

  The present invention relates to a focus detection apparatus and an imaging apparatus.

  2. Description of the Related Art Conventionally, a focus detection device that detects a focus state of an optical system by detecting an image plane shift amount by the optical system at a plurality of focus detection positions is known. In such a focus detection device, if sufficient exposure for focus detection is not obtained at the focus detection position in the center of the object field among the plurality of focus detection positions, While detecting exposure at the focus detection position, the detection of the image plane shift amount at the focus detection position at the periphery of the object scene is performed before the detection of the image plane shift amount at the focus detection position at the center of the object scene. The technique to perform is known (for example, refer patent document 1).

JP 2003-149543 A

  However, in the prior art, the image plane displacement amount at the focus detection position at the periphery of the object scene is detected before the image plane displacement amount is detected at the focus detection position at the center area of the object field. While it is possible to prevent the time required for focus detection from increasing while extending the exposure time at the focus detection position in the center of the field, the time required for focus detection has not been shortened.

  The problem to be solved by the present invention is to provide a focus detection device capable of reducing the time required for focus detection.

  The present invention solves the above problems by the following means. In the following description, reference numerals corresponding to the drawings showing the embodiment of the present invention are given and described. However, the reference numerals are only for facilitating the understanding of the invention and are not intended to limit the invention. .

  [1] A focus detection apparatus according to the present invention captures an image by an optical system, and repeatedly outputs an image signal corresponding to the captured image at a predetermined frame rate, and the optical system. A pair of light receiving sensors (22a to 22j) that receive the pair of luminous fluxes and repeatedly output the pair of light receiving signals at a period according to the frame rate, and a plurality of light receiving sensors based on the pair of light receiving signals. A phase difference detection unit (21) for detecting a focus state of the optical system by sequentially calculating a shift amount of an image plane by the optical system at a focus detection position of the optical system, and the phase difference under a predetermined photographing condition. In a predetermined time determined according to the frame rate among the plurality of focus detection positions, the detection unit is configured to calculate the shift amount for a focus detection position where the shift amount can be calculated. The serial phase difference detecting unit, based on the deviation amount calculated within the predetermined time, a control unit for detecting the focusing state of the optical system (21), characterized in that it comprises a.

  [2] In the invention relating to the focus detection device, the control unit (21) may cause the phase difference detection unit (21) to set the frame rate among the plurality of focus detection positions under a predetermined shooting condition. The shift amount can be calculated only for the corresponding number of focus detection positions.

  [3] In the invention relating to the focus detection apparatus, the predetermined shooting conditions include that the shutter release button is fully pressed, continuous shooting is being performed, and the focus state of the optical system is in focus. The focus detection mode is a mode in which the detection of the focus state is repeated, and at least the focus detection position for performing focus detection among the plurality of focus detection positions is specified. It can be configured to be one.

  [4] In the invention related to the focus detection device, the evaluation value related to the contrast of the image by the optical system is calculated based on the image signal output from the imaging unit (22), thereby the focus of the optical system. A contrast detection unit (21) for detecting a state may be further provided, and the pair of light receiving sensors (22a to 22j) may be configured to be provided on a light receiving surface of the imaging unit.

  [5] An imaging apparatus according to the present invention includes the focus detection apparatus.

  According to the present invention, the time required for focus detection can be shortened.

FIG. 1 is a block diagram showing a camera according to the present embodiment. FIG. 2 is a front view showing a focus detection area on the imaging surface of the imaging device shown in FIG. FIG. 3 is a front view schematically showing the arrangement of the focus detection pixels 222a and 222b by enlarging the III part of FIG. FIG. 4 is an enlarged front view showing one of the imaging pixels 221. FIG. 5A is an enlarged front view showing one of the focus detection pixels 222a, and FIG. 5B is an enlarged front view showing one of the focus detection pixels 222b. FIG. 6 is an enlarged cross-sectional view showing one of the imaging pixels 221. FIG. 7A is an enlarged cross-sectional view showing one of the focus detection pixels 222a, and FIG. 7B is an enlarged cross-sectional view showing one of the focus detection pixels 222b. 8 is a cross-sectional view taken along line VIII-VIII in FIG. FIG. 9 is a flowchart illustrating an operation example of the camera according to the present embodiment. FIG. 10 is a diagram for explaining an example of a defocus amount calculation method when the defocus calculation abort flag is off. FIG. 11 is a diagram for explaining an example of a defocus amount calculation method when the defocus calculation abort flag is on. FIG. 12 is a flowchart illustrating the defocus calculation abort determination process. FIG. 13 is a table showing imaging conditions for determining whether or not to cancel the defocus amount calculation. FIG. 14 is a diagram for explaining another example of a defocus amount calculation method when the defocus calculation abort flag is off.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a main part configuration diagram showing a digital camera 1 according to an embodiment of the present invention. A digital camera 1 according to the present embodiment (hereinafter simply referred to as a camera 1) includes a camera body 2 and a lens barrel 3, and the camera body 2 and the lens barrel 3 are detachably coupled by a mount unit 4. Yes.

  The lens barrel 3 is an interchangeable lens that can be attached to and detached from the camera body 2. As shown in FIG. 1, the lens barrel 3 includes a photographic optical system including lenses 31, 32, 33 and a diaphragm 34.

  The lens 32 is a focus lens, and can adjust the focal length of the photographing optical system by moving in the direction of the optical axis L1. The focus lens 32 is provided so as to be movable along the optical axis L1 of the lens barrel 3, and its position is adjusted by the focus lens drive motor 36 while its position is detected by the encoder 35.

  The specific configuration of the moving mechanism along the optical axis L1 of the focus lens 32 is not particularly limited. For example, a rotating cylinder is rotatably inserted into a fixed cylinder fixed to the lens barrel 3, a helicoid groove (spiral groove) is formed on the inner peripheral surface of the rotating cylinder, and the focus lens 32 is fixed. The end of the lens frame is fitted into the helicoid groove. Then, by rotating the rotating cylinder by the focus lens drive motor 36, the focus lens 32 fixed to the lens frame moves straight along the optical axis L1.

  As described above, the focus lens 32 fixed to the lens frame by rotating the rotary cylinder with respect to the lens barrel 3 moves straight in the direction of the optical axis L1, but the focus lens drive motor 36 as the drive source is the lens. The lens barrel 3 is provided. The focus lens drive motor 36 and the rotary cylinder are connected by a transmission composed of a plurality of gears, for example, and when the drive shaft of the focus lens drive motor 36 is driven to rotate in any one direction, it is transmitted to the rotary cylinder at a predetermined gear ratio. Then, when the rotating cylinder rotates in any one direction, the focus lens 32 fixed to the lens frame moves linearly in any direction of the optical axis L1. When the drive shaft of the focus lens drive motor 36 is rotated in the reverse direction, the plurality of gears constituting the transmission also rotate in the reverse direction, and the focus lens 32 moves straight in the reverse direction of the optical axis L1. .

  The position of the focus lens 32 is detected by the encoder 35. As described above, the position of the focus lens 32 in the optical axis L1 direction correlates with the rotation angle of the rotating cylinder, and can be obtained by detecting the relative rotation angle of the rotating cylinder with respect to the lens barrel 3, for example.

  As the encoder 35 of this embodiment, an encoder that detects the rotation of a rotating disk coupled to the rotational drive of the rotating cylinder with an optical sensor such as a photo interrupter and outputs a pulse signal corresponding to the number of rotations, or a fixed cylinder And the contact point of the brush on the surface of the flexible printed wiring board provided on either one of the rotating cylinders, and the brush contact provided on the other, the amount of movement of the rotating cylinder (in either the rotational direction or the optical axis direction) A device that detects a change in the contact position according to the detection circuit using a detection circuit can be used.

  The focus lens 32 can move in the direction of the optical axis L1 from the end on the camera body side (also referred to as the closest end) to the end on the subject side (also referred to as the infinite end) by the rotation of the rotating cylinder described above. it can. Incidentally, the current position information of the focus lens 32 detected by the encoder 35 is sent to the camera control unit 21 to be described later via the lens control unit 37, and the focus lens drive motor 36 calculates the focus calculated based on this information. The driving position of the lens 32 is driven by being sent from the camera control unit 21 via the lens control unit 37.

  The diaphragm 34 is configured such that the aperture diameter around the optical axis L1 can be adjusted in order to limit the amount of light flux that passes through the photographing optical system and reaches the image sensor 22 and to adjust the blur amount. The adjustment of the aperture diameter by the diaphragm 34 is performed, for example, by sending an appropriate aperture diameter calculated in the automatic exposure mode from the camera control unit 21 via the lens control unit 37. Further, the set aperture diameter is input from the camera control unit 21 to the lens control unit 37 by a manual operation by the operation unit 28 provided in the camera body 2. The aperture diameter of the aperture 34 is detected by an aperture sensor (not shown), and the lens controller 37 recognizes the current aperture diameter.

  On the other hand, the camera body 2 is provided with an imaging element 22 that receives the light beam L1 from the photographing optical system on a planned focal plane of the photographing optical system, and a shutter 23 is provided on the front surface thereof. The image sensor 22 is composed of a device such as a CMOS, converts the received optical signal into an electrical signal, and sends it to the camera control unit 21. The captured image information sent to the camera control unit 21 is sequentially sent to the liquid crystal drive circuit 25 and displayed on the electronic viewfinder (EVF) 26 of the observation optical system, and a release button ( When (not shown) is fully pressed, the photographed image information is recorded in the memory 24 that is a recording medium. As the memory 24, any of a removable card type memory and a built-in type memory can be used. An infrared cut filter for cutting infrared light and an optical low-pass filter for preventing image aliasing noise are disposed in front of the imaging surface of the image sensor 22. Details of the structure of the image sensor 22 will be described later.

  The camera body 2 is provided with an observation optical system for observing an image picked up by the image pickup device 22. The observation optical system of the present embodiment includes an electronic viewfinder (EVF) 26 composed of a liquid crystal display element, a liquid crystal driving circuit 25 that drives the electronic viewfinder (EVF) 26, and an eyepiece lens 27. The liquid crystal drive circuit 25 reads the captured image information captured by the image sensor 22 and sent to the camera control unit 21, and drives the electronic viewfinder 26 based on the read image information. Thereby, the user can observe the current captured image through the eyepiece lens 27. Note that, instead of or in addition to the observation optical system using the optical axis L2, a liquid crystal display may be provided on the back surface of the camera body 2, and a photographed image may be displayed on the liquid crystal display.

  A camera control unit 21 is provided in the camera body 2. The camera control unit 21 is electrically connected to the lens control unit 37 through an electric signal contact unit 41 provided in the mount unit 4, receives lens information from the lens control unit 37, and defocuses to the lens control unit 37. Send information such as volume and aperture diameter. The camera control unit 21 reads out the pixel output from the image sensor 22 as described above, generates image information by performing predetermined information processing on the read out pixel output as necessary, and generates the generated image information. Is output to the liquid crystal driving circuit 25 and the memory 24 of the electronic viewfinder 26. The camera control unit 21 controls the entire camera 1 such as correction of image information from the image sensor 22 and detection of a focus adjustment state and an aperture adjustment state of the lens barrel 3.

  In addition to the above, the camera control unit 21 detects the focus state of the photographic optical system by the phase detection method and the focus state of the photographic optical system by the contrast detection method based on the pixel data read from the image sensor 22. I do. A specific focus state detection method will be described later.

  The operation unit 28 is a shutter release button or an input switch for the photographer to set various operation modes of the camera 1, and switches between the auto focus mode / manual focus mode and the one shot mode / continuity even in the auto focus mode. It is possible to switch between the numeric modes. Here, the one-shot mode is a mode in which the position of the focus lens 32 once adjusted is fixed and photographing is performed at the focus lens position, whereas the continuous mode is a mode in which the position of the focus lens 32 is fixed. In this mode, the focus lens position is adjusted according to the subject. The operation unit 28 can also switch the AF area mode, that is, the single area AF mode / auto area AF mode. The single AF mode is a mode in which focus detection is performed in the focus detection area selected by the photographer, while the auto area AF mode is a mode in which the focus detection area is selected and focused by the camera 1. . Various modes set by the operation unit 28 are sent to the camera control unit 21, and the operation of the entire camera 1 is controlled by the camera control unit 21. The shutter release button includes a first switch SW1 that is turned on when the button is half-pressed and a second switch SW2 that is turned on when the button is fully pressed.

  Next, the image sensor 22 according to the present embodiment will be described.

  FIG. 2 is a front view showing the imaging surface of the image sensor 22, and FIG. 3 is a front view schematically showing the arrangement of the focus detection pixels 222a and 222b by enlarging the III part of FIG.

  As shown in FIG. 3, the imaging element 22 of the present embodiment includes a green pixel G having a color filter in which a plurality of imaging pixels 221 are two-dimensionally arranged on the plane of the imaging surface and transmit a green wavelength region. A red pixel R having a color filter that transmits a red wavelength region and a blue pixel B having a color filter that transmits a blue wavelength region are arranged in a so-called Bayer Arrangement. That is, in four adjacent pixel groups 223 (dense square lattice arrangement), two green pixels are arranged on one diagonal line, and one red pixel and one blue pixel are arranged on the other diagonal line. The image sensor 22 is configured by repeatedly arranging the pixel group 223 on the imaging surface of the image sensor 22 in a two-dimensional manner with the Bayer array pixel group 223 as a unit.

  The unit pixel group 223 may be arranged in a dense hexagonal lattice arrangement other than the dense square lattice shown in the figure. Further, the configuration and arrangement of the color filters are not limited to this, and an arrangement of complementary color filters (green: G, yellow: Ye, magenta: Mg, cyan: Cy) can also be adopted.

  FIG. 4 is an enlarged front view showing one of the imaging pixels 221, and FIG. 6 is a cross-sectional view. One imaging pixel 221 includes a micro lens 2211, a photoelectric conversion unit 2212, and a color filter (not shown), and a photoelectric conversion unit is formed on the surface of the semiconductor circuit substrate 2213 of the image sensor 22 as shown in the cross-sectional view of FIG. 2212 is built in and a microlens 2211 is formed on the surface. The photoelectric conversion unit 2212 is configured to receive an imaging light beam that passes through an exit pupil (for example, F1.0) of the photographing optical system by the micro lens 2211, and receives the imaging light beam.

  Further, the imaging element 22 is provided with focus detection pixel rows 22a to 22j in which focus detection pixels 222a and 222b are arranged in place of the imaging pixel 221 described above. As shown in FIG. 3, one focus detection pixel column is configured by a plurality of focus detection pixels 222a and 222b being alternately arranged adjacent to each other in a horizontal row (22a to 22j). In the present embodiment, the focus detection pixels 222a and 222b are densely arranged without providing a gap at the position of the green pixel G and the blue pixel B of the image pickup pixel 221 arranged in the Bayer array.

  Note that the positions of the focus detection pixel rows 22a to 22j shown in FIG. 2 are not limited to the illustrated positions, and can be arranged at seven or less positions, or can be arranged at nine or more positions. . In actual focus detection, the photographer manually operates the operation unit 28 from among a plurality of focus detection pixel rows 22a to 22j, and selects a desired focus detection pixel row as a focus detection position. You can also.

  FIG. 5A is an enlarged front view showing one of the focus detection pixels 222a, and FIG. 7A is a cross-sectional view of the focus detection pixel 222a. FIG. 5B is an enlarged front view showing one of the focus detection pixels 222b, and FIG. 7B is a cross-sectional view of the focus detection pixel 222b. As shown in FIG. 5A, the focus detection pixel 222a includes a micro lens 2221a and a semicircular photoelectric conversion unit 2222a. As shown in the cross-sectional view of FIG. A photoelectric conversion portion 2222a is formed on the surface of the semiconductor circuit substrate 2213, and a micro lens 2221a is formed on the surface. The focus detection pixel 222b includes a micro lens 2221b and a photoelectric conversion unit 2222b as shown in FIG. 5B, and a semiconductor of the image sensor 22 as shown in a cross-sectional view of FIG. 7B. A photoelectric conversion unit 2222b is formed on the surface of the circuit board 2213, and a microlens 2221b is formed on the surface. These focus detection pixels 222a and 222b are alternately arranged adjacent to each other in a horizontal row as shown in FIG. 3, thereby forming focus detection pixel rows 22a to 22j shown in FIG.

  The photoelectric conversion units 2222a and 2222b of the focus detection pixels 222a and 222b have such a shape that the microlenses 2221a and 2221b receive a light beam that passes through a predetermined region (eg, F2.8) of the exit pupil of the photographing optical system. Is done. Further, the focus detection pixels 222a and 222b are not provided with color filters, and their spectral characteristics are the total of the spectral characteristics of a photodiode that performs photoelectric conversion and the spectral characteristics of an infrared cut filter (not shown). ing. However, it may be configured to include one of the same color filters as the imaging pixel 221, for example, a green filter.

  In addition, although the photoelectric conversion units 2222a and 2222b of the focus detection pixels 222a and 222b illustrated in FIGS. 5A and 5B have a semicircular shape, the shapes of the photoelectric conversion units 2222a and 2222b are not limited thereto. Other shapes such as an elliptical shape, a rectangular shape, and a polygonal shape can also be used.

  Here, a so-called phase difference detection method for detecting the focus state of the photographing optical system based on the pixel outputs of the focus detection pixels 222a and 222b described above will be described.

  FIG. 8 is a cross-sectional view taken along the line VIII-VIII in FIG. 3. The focus detection pixels 222 a-1, 222 b-1, 222 a-2, and 222 b-2 that are arranged in the vicinity of the photographing optical axis L 1 and adjacent to each other are It shows that light beams AB1-1, AB2-1, AB1-2, and AB2-2 irradiated from the distance measuring pupils 341 and 342 of the exit pupil 34 are received, respectively. 8 illustrates only the focus detection pixels 222a and 222b that are located in the vicinity of the photographing optical axis L1, but other focus detection pixels other than the focus detection pixels illustrated in FIG. 8 are illustrated. In the same manner, the light beams emitted from the pair of distance measuring pupils 341 and 342 are respectively received.

  Here, the exit pupil 34 is an image set at a distance D in front of the microlenses 2221a and 2221b of the focus detection pixels 222a and 222b arranged on the planned focal plane of the photographing optical system. The distance D is a value uniquely determined according to the curvature and refractive index of the microlens, the distance between the microlens and the photoelectric conversion unit, and the distance D is referred to as a distance measurement pupil distance. The distance measurement pupils 341 and 342 are images of the photoelectric conversion units 2222a and 2222b respectively projected by the micro lenses 2221a and 2221b of the focus detection pixels 222a and 222b.

  In FIG. 8, the arrangement direction of the focus detection pixels 222a-1, 222b-1, 222a-2, 222b-2 coincides with the arrangement direction of the pair of distance measuring pupils 341, 342.

  As shown in FIG. 8, the microlenses 2221a-1, 2221b-1, 2221a-2, and 2221b-2 of the focus detection pixels 222a-1, 222b-1, 222a-2, and 222b-2 are photographic optical systems. Near the planned focal plane. The shapes of the photoelectric conversion units 2222a-1, 2222b-1, 2222a-2, 2222b-2 arranged behind the micro lenses 2221a-1, 2221b-1, 2221a-2, 2221b-2 are the same as the micro lenses 2221a-1, 2221b-1, 2221a-2, 2221b-2. Projected onto the exit pupil 34 separated from the lenses 2221a-1, 2221b-1, 2221a-2, 2221b-2 by the distance measurement distance D, and the projection shape forms the distance measurement pupils 341, 342.

  In other words, on the exit pupil 34 at the distance measurement distance D, the microlens and the photoelectric conversion unit in each focus detection pixel so that the projection shapes (the distance measurement pupils 341 and 342) of the photoelectric conversion unit of each focus detection pixel match. Is determined, and the projection direction of the photoelectric conversion unit in each focus detection pixel is thereby determined.

  As shown in FIG. 8, the photoelectric conversion unit 2222a-1 of the focus detection pixel 222a-1 is formed on the microlens 2221a-1 by the light beam AB1-1 that passes through the distance measuring pupil 341 and goes to the microlens 2221a-1. A signal corresponding to the intensity of the image to be output is output. Similarly, the photoelectric conversion unit 2222a-2 of the focus detection pixel 222a-2 passes through the distance measuring pupil 341, and the intensity of the image formed on the microlens 2221a-2 by the light beam AB1-2 toward the microlens 2221a-2. The signal corresponding to is output.

  Further, the photoelectric conversion unit 2222b-1 of the focus detection pixel 222b-1 passes through the distance measuring pupil 342, and the intensity of the image formed on the microlens 2221b-1 by the light beam AB2-1 directed to the microlens 2221b-1. Output the corresponding signal. Similarly, the photoelectric conversion unit 2222b-2 of the focus detection pixel 222b-2 passes through the distance measuring pupil 342, and the intensity of the image formed on the microlens 2221b-2 by the light beam AB2-2 toward the microlens 2221b-2. The signal corresponding to is output.

  Then, a plurality of the above-described two types of focus detection pixels 222a and 222b are arranged in a straight line as shown in FIG. 3, and the outputs of the photoelectric conversion units 2222a and 2222b of the focus detection pixels 222a and 222b are converted into the distance measurement pupil 341, respectively. Of the pair of images formed on the focus detection pixel row by the focus detection light fluxes that pass through each of the distance measurement pupil 341 and the distance measurement pupil 342. Data on the distribution is obtained. Then, by applying an image shift detection calculation process such as a correlation calculation process or a phase difference detection process to the intensity distribution data, an image shift amount by a so-called phase difference detection method can be detected.

  Then, a conversion calculation is performed on the obtained image shift amount according to the center-of-gravity interval of the pair of distance measuring pupils, thereby obtaining a current focal plane with respect to the planned focal plane (the focal point corresponding to the position of the microlens array on the planned focal plane). The deviation of the focal plane at the detection position, that is, the defocus amount can be obtained.

  The calculation of the image shift amount by the phase difference detection method and the calculation of the defocus amount based thereon are executed by the camera control unit 21.

  Further, the camera control unit 21 reads the output of the imaging pixel 221 of the imaging element 22 and calculates a focus evaluation value based on the read pixel output. This focus evaluation value can be obtained, for example, by extracting a high-frequency component of an image output from the imaging pixel 221 of the image sensor 22 using a high-frequency transmission filter and integrating the extracted high-frequency components to detect a focus voltage. It can also be obtained by extracting high-frequency components using two high-frequency transmission filters having different cutoff frequencies and integrating them to detect the focus voltage.

  Then, the camera control unit 21 sends a control signal to the lens control unit 37 to drive the focus lens 32 at a predetermined sampling interval (distance) to obtain a focus evaluation value at each position, and the focus evaluation value is maximum. The focus detection by the contrast detection method is performed in which the position of the focus lens 32 is determined as the in-focus position. Note that this in-focus position is obtained when, for example, when the focus evaluation value is calculated while driving the focus lens 32, the focus evaluation value rises twice and then moves down twice. Can be obtained by performing an operation such as interpolation using the focus evaluation value.

  Next, an operation example of the camera 1 according to the present embodiment will be described. FIG. 9 is a flowchart showing an operation example of the camera 1 according to the present embodiment. The following operation is started, for example, when the camera 1 is turned on.

  First, in step S101, generation of a through image by the camera control unit 21 and display of a through image by the electronic viewfinder 26 of the observation optical system are started. Specifically, an exposure operation is performed by the imaging element 22, and pixel data of the imaging pixel 221 is read by the camera control unit 21. Then, the camera control unit 21 generates a through image based on the read data, and the generated through image is sent to the liquid crystal drive circuit 25 and displayed on the electronic viewfinder 26 of the observation optical system. As a result, the user can view the moving image of the subject through the eyepiece lens 27. Note that the generation of the through image and the display of the through image are repeatedly executed at a predetermined frame rate.

  In step S102, the camera control unit 21 starts a defocus amount calculation process using a phase difference detection method. In the present embodiment, the calculation process of the defocus amount by the phase difference detection method is performed as follows. That is, first, the camera control unit 21 reads a pair of image data corresponding to a pair of images from the focus detection pixels 222a and 222b constituting the eight focus detection pixel rows 22a to 22j of the image sensor 22. Then, the camera control unit 21 executes image shift detection calculation processing (correlation calculation processing) based on the read pair of image data, and images in the focus detection areas corresponding to the eight focus detection pixel rows 22a to 22j. The shift amount is calculated, and the image shift amount is converted into a defocus amount.

  In this embodiment, the camera control unit 21 repeatedly reads out a pair of image data from the image sensor 22 at a predetermined cycle according to the frame rate of the through image, for example, and based on the read-out pair of image data. Repeatedly calculates the defocus amount.

  Here, FIG. 10 is a diagram for explaining an example of a defocus amount calculation method according to the present embodiment. In FIG. 10, charge accumulation, image data transfer, and defocus amount calculation are shown in time series. The numbers 1 to 8 in the calculation of the defocus amount in FIG. 10 indicate the calculation of the defocus amounts in the eight focus detection areas corresponding to the focus detection pixel rows 22a to 22j shown in FIG. (The same applies to FIGS. 11 and 14 described later).

  For example, in the example shown in FIG. 10, accumulation of electric charge according to incident light is started at time t1, and transfer of image data according to the electric charge accumulated from time t1 is started at time t2. Further, at time t2, charge accumulation for the next frame is started, and transfer of image data corresponding to the charge accumulated from time t2 is started at time t4. Similarly, charge accumulation is started at times t4, t5, t6, and t9, and image data transfer corresponding to the accumulated charges is started at times t5, t6, t9, and t10, respectively. As described above, in this embodiment, charge accumulation and image data transfer are repeatedly executed at a predetermined cycle.

  In the present embodiment, the calculation of the defocus amount is also repeatedly performed. For example, in the example shown in FIG. 10, the transfer of the image data started at time t2 is completed at time t3, and the calculation of the defocus amount is started based on the transferred image data from time t3. In the example shown in FIG. 10, the defocus amounts in the eight focus detection areas corresponding to the focus detection pixel rows 22a to 22j shown in FIG. 2 are sequentially calculated. As a result, the calculation of the focus detection area started at time t3 is performed. The process ends at time t7. When the calculation of the defocus amount is completed, the calculation of the defocus amount is newly started from time t8 based on the image data transferred after the calculation of the defocus amount.

  Further, in the present embodiment, as shown in FIG. 10, in addition to the defocus amount calculation processing for sequentially calculating the defocus amounts in all the focus detection areas, as shown in FIG. An arithmetic process for calculating the defocus amount based on all the image data transferred from the image sensor 22 is also performed by terminating the calculation of the defocus amount within a time determined according to the frame rate. For example, in the following, referring to FIG. 11, within the time of one frame at the frame rate of the image sensor 22 (from the completion of image data transfer to the completion of image data transfer of the next frame A description will be given of an operation example in which the calculation of the defocus amount is terminated within the time). FIG. 11 is a diagram for explaining another example of the defocus amount calculation method according to the present embodiment.

  That is, in the example shown in FIG. 11, as in the example shown in FIG. 10, charge accumulation and image data transfer are repeatedly performed at a predetermined cycle. However, in the example shown in FIG. 11, for example, transfer of image data is started at time t11, and calculation of the defocus amount is started based on the transferred image data at time t12. When the transfer of the frame image data is completed, the defocus amount calculation process started at time t12 is interrupted in the middle of the defocus amount calculation in the fourth focus detection area, and as a result, transferred at time t12. Only the defocus amounts in the three focus detection areas are calculated based on the image data thus obtained. Similarly, the calculation of the defocus amount is started at time t14 based on the image data that has been transferred at time t13. When transfer of the next image data is completed at time t16, the calculation starts at time t14. The calculation processing of the defocus amount is aborted in the middle, and the calculation of the defocus amount based on the newly transferred image data is started from time t16. Similarly, the calculation of the defocus amount started from time t16 is also aborted at time t17 when the transfer of the next image data is completed, and the calculation of the defocus amount started from time t17 is also the transfer of the next image data. Is terminated at time t18.

  As described above, in the example illustrated in FIG. 11, the defocus amount calculation is stopped halfway, and the defocus amount calculation is performed only for the number of focus detection areas corresponding to the frame rate of the image sensor 22. The defocus amount can be calculated based on all image data transferred from the image data 22. For this reason, for example, when a focus detection area corresponding to a specific subject is specified in a scene where a specific subject is tracked, transfer is performed by preferentially calculating the defocus amount in the focus detection area corresponding to the specific subject. The focus state in the focus detection area corresponding to the specific subject can be detected on the basis of all the image data.

  In the present embodiment, the calculation of the defocus amount may be stopped within the time determined according to the frame rate of the image sensor 22, and the number of focus detection areas where the defocus amount can be calculated is limited to a certain number. do not have to. For example, when there is variation in the time for calculating the defocus amount for each focus detection area, the defocus amount is determined according to the frame rate of the image sensor 22 when calculating the defocus amount. A determination may be made as to whether or not the defocus amount can be calculated within the time, and if it is determined that the defocus amount cannot be calculated within the time, the calculation of the defocus amount may be terminated.

  As described above, in this embodiment, as shown in FIG. 10, the process of calculating the defocus amount in all the focus detection areas and the defocus amount in the focus detection area are cut off halfway as shown in FIG. As a result, it is possible to execute a process of calculating the defocus amount for all the image data transferred from the image sensor 22. In the present embodiment, the camera control unit 21 determines which defocus amount calculation process is performed according to the shooting conditions. Here, FIG. 12 is a flowchart showing a defocus calculation abort determination process for determining whether or not to cancel the defocus amount calculation. FIG. 13 shows whether or not the defocus amount calculation is interrupted halfway. It is a table which shows the imaging conditions for determination. In the following, the defocus calculation abort determination process will be described with reference to FIGS. 12 and 13. This defocus calculation abort determination process is repeatedly performed by the camera control unit 21 independently of the operation of the camera 1 shown in FIG.

  As shown in FIG. 12, first, in step S201, the camera control unit 21 determines whether or not the one-shot mode is set in the autofocus mode. If the one-shot mode is set, the process proceeds to step S202, and the defocus calculation abort flag is set to OFF. As a result, when the one-shot mode is set, as shown in FIG. 10, the defocus amount is calculated in all focus detection areas, so that an image focused on the subject can be captured. It will be possible.

  On the other hand, if it is determined in step S201 that the continuous mode is set, the process proceeds to step S203. In step S203, whether or not the camera control unit 21 has set an auto area AF mode for automatically specifying a focus detection area for performing focus detection from among a plurality of focus detection areas among the AF area modes. Judgment is made. When the auto area AF mode is set, the process proceeds to step S204. On the other hand, when the single area AF mode in which the photographer specifies the focus detection area for performing focus detection is set, step S205 is performed. Proceed to

  In step S204, the camera control unit 21 determines whether or not a focus detection area for performing focus detection is actually specified. Here, in the present embodiment, when the auto area AF mode is set and the focus detection area for performing focus detection is not specified, the defocus amount calculation is performed in all focus detection areas. And a focus detection area for performing focus detection is specified based on the calculated defocus amount distribution in each focus detection area. Therefore, when the auto area AF mode is set (step S203 = Yes) and the focus detection area for performing focus detection is not specified (step S204 = No), the process proceeds to step S202, and FIG. As shown, the defocus calculation abort flag is set to OFF in order to calculate the defocus amount in all focus detection areas.

  On the other hand, when the continuous mode is set (step S201 = No), the focus detection area for performing focus detection in the single area AF mode is specified by the photographer (step S203 = No). Alternatively, when the focus detection area for performing focus detection is automatically specified by the auto area AF mode (step S203 = Yes, step S204 = Yes), the process proceeds to step S205. In step S205, the camera control unit 21 calculates the defocus amount for all the transferred image data in the specified focus detection area and the surrounding focus detection areas, so that the defocus calculation abort flag is turned on. Set to

  In this way, the defocus calculation abort determination process according to the present embodiment is performed, and the defocus calculation abort flag for aborting the defocus amount computation is set. That is, in the present embodiment, as shown in FIG. 13, the defocus calculation abort flag is set to OFF under the shooting condition in which the one-shot mode is set, and as shown in FIG. In the AF area), a defocus amount calculation (Def calculation) is performed.

  Further, as shown in FIG. 13, when the continuous mode is set, the auto area AF is set when the shooting condition in which the single area AF mode is set or when the continuous mode is set. In the shooting conditions in which the focus detection area for performing focus detection is actually specified in the mode, the defocus calculation abort flag is set to ON, and as shown in FIG. The defocus amount calculation (Def calculation) is terminated halfway.

  Furthermore, in the present embodiment, as shown in FIG. 13, when the continuous mode is set, in the shooting conditions in which the focus detection area for performing focus detection is not specified in the auto area AF mode, The defocus calculation abort flag is set to OFF, and the defocus amount calculation (Def calculation) is performed in all focus detection areas (AF areas) as shown in FIG.

  Next, returning to FIG. 9, in step S <b> 103, the camera control unit 21 starts a focus evaluation value calculation process. In the present embodiment, the focus evaluation value calculation process reads out the pixel output of the imaging pixel 221 of the imaging device 22, extracts a high-frequency component of the read-out pixel output using a high-frequency transmission filter, integrates it, and focuses This is done by detecting the voltage. The focus evaluation value calculation process is repeatedly executed at predetermined intervals.

  In step S104, the camera control unit 21 determines whether or not the shutter release button provided in the operation unit 28 is half-pressed (the first switch SW1 is turned on). If the first switch SW1 is turned on, the process proceeds to step S105. On the other hand, if the first switch SW1 is not turned on, step S104 is repeated until the first switch SW1 is turned on. That is, the defocus amount calculation process and the focus evaluation value calculation process by the phase difference detection method are repeatedly executed until the first switch SW1 is turned on.

  In step S105, as in step S102, it is determined whether or not the defocus amount has been calculated in the focus detection area for performing focus detection by the phase difference detection method. If the defocus amount can be calculated, it is determined that distance measurement is possible, and the process proceeds to step S110. On the other hand, if the defocus amount cannot be calculated, it is determined that distance measurement is impossible, and the process proceeds to step S106.

  If it is determined in step S105 that the defocus amount has been calculated and it is determined that distance measurement is possible, the process proceeds to step S110, and a focusing operation is performed based on the defocus amount calculated by the phase difference detection method. It is. Specifically, first, the camera control unit 21 calculates the lens driving amount necessary to drive the focus lens 32 to the in-focus position from the defocus amount calculated by the phase difference detection method. Here, when the defocus amount calculation abort flag is set to OFF, and the defocus amount can be calculated in all eight focus detection areas, for example, as shown in FIG. Based on the distribution of defocus amounts calculated in the eight focus detection areas, a focus detection area for performing focus detection is specified, and the focus lens 32 is adjusted based on the defocus amount in the specified focus detection areas. The lens drive amount required to drive to the in-focus position is calculated. In addition, when the defocus amount calculation abort flag is set to ON and the calculation of the defocus amount in the focus detection area is interrupted in the middle, the camera control unit 21 determines the defocus amount ( In the example shown in FIG. 11, a focus detection area for performing focus detection is identified based on the distribution of defocus amounts in three focus detection areas), and based on the defocus amounts in the identified focus detection area, The lens driving amount necessary to drive the focus lens 32 to the in-focus position is calculated.

  Then, the calculated lens driving amount is sent to the lens driving motor 36 via the lens control unit 37, whereby the lens driving motor 36 is based on the lens driving amount calculated by the camera control unit 21. The focus lens 32 is driven to the in-focus position. When the focus lens 32 is driven to the in-focus position, the process proceeds to step S113.

  On the other hand, if it is determined in step S105 that the defocus amount cannot be calculated in the focus detection area for performing focus detection by the phase difference detection method, the process proceeds to step S106, and the camera control unit 21 Scanning start processing is performed. In the scan operation of this embodiment, the focus lens drive motor 36 scans the focus lens 32, and the camera control unit 21 calculates a defocus amount and a focus evaluation value by a phase difference detection method. Thus, the detection of the in-focus position by the phase difference detection method and the detection of the in-focus position by the contrast detection method are simultaneously performed at predetermined intervals.

  Specifically, the camera control unit 21 sends a scan drive start command to the lens control unit 37, and the lens control unit 37 drives the focus lens drive motor 36 based on the command from the camera control unit 21 to focus. The lens 32 is scan-driven along the optical axis L1. Note that the scan driving of the focus lens 32 is performed from the infinity end position toward the close end position, or from the close end position toward the infinity end position.

  Then, while driving the focus lens 32, the camera control unit 21 reads out a pair of image data corresponding to the pair of images from the focus detection pixels 222a and 222b of the image sensor 22 at predetermined intervals. The phase difference detection method calculates the defocus amount, evaluates the reliability of the calculated defocus amount, and drives the focus lens 32 to drive the pixel output from the imaging pixel 221 of the imaging element 22 at a predetermined interval. Reading is performed, and based on this, a focus evaluation value is calculated, thereby acquiring a focus evaluation value at a different focus lens position, thereby detecting a focus position by a contrast detection method.

  Note that, as described above, the camera control unit 21 also performs the defocus calculation set in the defocus calculation abort determination process shown in FIG. 12 when calculating the defocus amount by the phase difference detection method in the scan operation. Based on the abort flag, the defocus amount is calculated.

  In step S107, it is determined whether the defocus amount in the focus detection area can be calculated by the phase difference detection method as a result of the scanning operation performed by the camera control unit 21. If the defocus amount can be calculated, it is determined that distance measurement is possible and the process proceeds to step S110. On the other hand, if the defocus amount cannot be calculated, it is determined that distance measurement is not possible and the process proceeds to step S108. . In step S107, as in step S105 described above, even when the defocus amount can be calculated, the defocus amount cannot be calculated if the reliability of the calculated defocus amount is low. It is assumed that the process proceeds to step S108.

  In step S108, it is determined whether or not the in-focus position in the focus detection area has been detected by the contrast detection method as a result of the scanning operation performed by the camera control unit 21. If the in-focus position can be detected by the contrast detection method, the process proceeds to step S111. If the in-focus position cannot be detected, the process proceeds to step S109.

  In step S <b> 109, the camera control unit 21 determines whether or not the scan operation has been performed for the entire range in which the focus lens 32 can be driven, that is, for the entire region between the infinity end position and the closest end position. When the scan operation is not performed for the entire driveable range of the focus lens 32, the process returns to step S107, and steps S107 to S109 are repeated to thereby perform the scan operation, that is, the phase difference while driving the focus lens 32. The operation of simultaneously executing the calculation of the defocus amount by the detection method and the detection of the in-focus position by the contrast detection method at predetermined intervals is continuously performed. On the other hand, when the execution of the scan operation is completed for the entire driveable range of the focus lens 32, the process proceeds to step S112.

  As a result of executing the scanning operation, if it is determined in step S107 that the defocus amount can be calculated by the phase difference detection method, the scanning operation is stopped, and the process proceeds to step S110. A focusing operation based on the defocus amount calculated by the phase difference detection method is performed.

  As a result of executing the scanning operation, if it is determined in step S108 that the in-focus position has been detected by the contrast detection method, the scanning operation is stopped, and the process proceeds to step S111, where it is detected by the contrast detection method. A focusing operation based on the focusing position is performed. That is, in step S111, a focus drive process for driving the focus lens 32 to the focus position is performed based on the focus position detected by the contrast detection method.

  On the other hand, if it is determined in step S109 that the scan operation has been completed for the entire driveable range of the focus lens 32, the process proceeds to step S112. In step S112, as a result of performing the scanning operation, focus detection could not be performed by any of the phase difference detection method and the contrast detection method, so the scanning operation was terminated and the focus lens 32 was determined in advance. A process of driving to a predetermined position is performed.

  In step S110, the focus lens 32 is driven to the in-focus position based on the defocus amount calculated by the phase difference detection method, and in step S111, based on the in-focus position detected by the contrast detection method. After the focus lens 32 is driven to the in-focus position, or after the process for driving the focus lens 32 to a predetermined position in step S112 is performed, the process proceeds to step S113, and the camera control unit 21 performs the process. Then, it is determined whether or not the autofocus mode is set to the one-shot mode. If the one-shot mode is set, the process proceeds to step S114. If the continuous mode is set instead of the one-shot mode, the process proceeds to step S116.

  If the one-shot mode is set, the process proceeds to step S114, and a focus lock for fixing the focus lens 32 at the current lens position is performed. In step S115, it is determined whether or not the shutter release button provided in the operation unit 28 has been fully pressed (the second switch SW2 is turned on). If the second switch SW2 is not turned on, While the focus lens 32 is fixed at the current lens position, the process waits until the second switch SW2 is turned on. On the other hand, when the second switch SW2 is turned on, the process proceeds to step S119 to shoot a subject image. .

  Further, in this embodiment, when the defocus amount is calculated by the phase difference detection method when the shutter release button is fully pressed (the second switch SW2 is turned on), all focus detections are performed. Without waiting for the calculation of the defocus amount in the area to end, the calculation of the defocus amount is interrupted halfway and the process proceeds to the subject image main photographing process. For example, when the shutter release button is fully pressed and the image sensor 22 enters a photographing mode for photographing a subject image, the camera control unit 21 aborts the calculation of the defocus amount halfway and shoots the subject image. You can move on to processing. As a result, the time lag from when the shutter release button is fully pressed to when the actual shooting of the subject image is started can be shortened.

  On the other hand, if it is determined in step S113 that the continuous mode has been set, the process proceeds to step S116, the focus lens 32 is stopped at the in-focus position, and the process proceeds to step S117. A determination is made whether the focus state has changed. For example, when the defocus amount by the phase difference detection method repeatedly calculated by the camera control unit 21 changes by a predetermined value or more, or when the defocus amount cannot be calculated, or is also repeatedly calculated by the camera control unit 21. When the focus evaluation value is changed by a predetermined value or more, it can be determined that the focus state of the optical system has changed. If it is determined that the focus state of the optical system has changed, the process returns to step S104. If the first switch SW1 is turned on, the processes of steps S105 to S112 are performed again as described above. Then, an operation for driving the focus lens 32 to the in-focus position is performed. On the other hand, when the focus state of the optical system has not changed, the focus lens 32 is moved until the second switch SW2 is turned on (step S118) or until the focus state of the optical system changes (step S117). When the second lens switch SW2 is turned on while being stopped at the current lens position (step S118 = Yes), a subject image is shot.

  As described above, the camera 1 according to the present embodiment actually has a focus detection area for performing focus detection in the auto area AF mode when the continuous mode is set as shown in FIG. 11 or when the continuous mode is set and the shooting condition is set to the single area AF mode, as shown in FIG. Then, the calculation of the defocus amount is stopped, and the process of calculating the defocus amount is repeatedly executed based on the newly transferred image data. Thereby, in this embodiment, the time required for focus detection can be reduced even when the defocus amount is calculated for all the image data transferred from the image sensor 22. In the present embodiment, the calculation of the defocus amount can be performed for all image data transferred from the image sensor 22 by stopping the calculation of the defocus amount at the focus detection position. In a scene where the user follows the subject, the followability to the specific subject can be improved.

  Furthermore, in the present embodiment, as shown in FIG. 13, under the shooting conditions in which the one-shot mode is set, the defocus amount is calculated in all the focus detection areas, so that the subject is in focus. Can be appropriately imaged. In addition, when the continuous mode is set, calculation of the defocus amount in all the focus detection areas under the shooting conditions in which the focus detection area for performing focus detection is not specified in the auto area AF mode. By performing the above, it is possible to appropriately specify a focus detection area for performing focus detection.

  The embodiment described above is described for facilitating the understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  For example, in the above-described embodiment, when the defocus calculation abort flag is OFF, as shown in FIG. 10, after the calculation of the defocus amount at all focus detection positions is completed, the calculation of the defocus amount is completed. The configuration of repeating the calculation of the defocus amount by newly performing the calculation of the defocus amount using the image data transferred after the completion is illustrated, but the configuration is not limited to this configuration. For example, FIG. As illustrated, when the defocus amount calculation is completed, the defocus amount calculation may be continuously performed using the latest image data that has already been transferred. For example, in the example shown in FIG. 14, since the calculation of the defocus amount started at time t21 ends at time t23, the image data transferred at time t22 that has already been transferred at time t23 is used. From the time t23, the calculation of the defocus amount is newly started. Similarly, since the calculation of the defocus amount started at time t23 ends at time t25, the image data transferred at time t24 that has already been transferred at time t25 is used to start defocusing from time t25. The calculation of the focus amount is newly started. In this way, in the example shown in FIG. 14, after the defocus amount calculation is completed, the defocus amount calculation can be newly started without waiting for the completion of the transfer of the image data. Compared to the example shown, the focus state of the optical system can be detected based on more image data. FIG. 14 is a diagram for explaining another example of the defocus amount calculation method when the defocus calculation abort flag is off.

  Further, in the above-described embodiment, a case where single-shot shooting of a still image is illustrated, but for example, when continuous shooting is performed, the defocus calculation abort flag is set to ON and the defocus amount calculation is in progress. It can also be set as the structure cut off by. Thereby, a still image can be appropriately captured at a predetermined interval.

  Furthermore, in the above-described embodiment, the configuration for calculating the defocus amount in each focus detection area is illustrated for each focus detection area. However, the configuration is not exemplified in this configuration, and for example, in one focus detection area. It is good also as a structure which divides | segments into several blocks and calculates a defocus amount for every block.

  Further, in the above-described embodiment, when the shutter release button is fully pressed, the calculation of the defocus amount is interrupted halfway and the main image capturing is performed. However, the present invention is not limited to this configuration. For example, when the focus priority mode (the mode in which the subject image is actually captured only when the focus state of the optical system is the in-focus state) is set, the focus state of the optical system becomes the in-focus state. The calculation of the defocus amount continues until the release priority mode (the mode that performs the actual shooting of the subject image regardless of whether the focus state of the optical system is the in-focus state) is set. A configuration may be adopted in which the calculation of the focus amount is discontinued and the process proceeds to the main photographing of the subject image.

  In the above-described embodiment, the imaging element 22 includes the imaging pixel 221 and the focus detection pixels 222a and 222b, and the focus detection pixels 222a and 222b included in the imaging element 22 perform focus detection by the phase difference detection method. However, the present invention is not limited to this configuration, and a focus detection module for performing focus detection by the phase difference detection method may be provided independently of the image sensor 22.

  The camera 1 of the above-described embodiment is not particularly limited. For example, the present invention is applied to other optical devices such as a digital video camera, a single-lens reflex digital camera, a lens-integrated digital camera, and a camera for a mobile phone. May be.

DESCRIPTION OF SYMBOLS 1 ... Digital camera 2 ... Camera body 21 ... Camera control part 22 ... Imaging device 221 ... Imaging pixel 222a, 222b ... Focus detection pixel 24 ... Memory 28 ... Operation part 3 ... Lens barrel 32 ... Focus lens 36 ... Focus lens drive motor 37 ... Lens control unit

Claims (5)

An imaging unit that captures an image by the optical system and repeatedly outputs an image signal corresponding to the captured image at a predetermined frame rate;
A pair of light receiving sensors that receive a pair of light fluxes via the optical system and repeatedly output a pair of light receiving signals at a period according to the frame rate;
A phase difference detection unit for detecting a focus state of the optical system by sequentially calculating a shift amount of an image plane by the optical system at a plurality of focus detection positions in a photographing screen based on the pair of light reception signals; ,
Under a predetermined photographing condition, the phase difference detection unit has the focus detection position that can calculate the shift amount within a predetermined time determined according to the frame rate among the plurality of focus detection positions. A control unit that calculates a shift amount, and causes the phase difference detection unit to detect a focus state of the optical system based on the shift amount calculated within the predetermined time. Focus detection device. The focus detection apparatus according to claim 1,
The control unit performs the calculation of the amount of deviation only for the number of focus detection positions corresponding to the frame rate, out of the plurality of focus detection positions, to the phase difference detection unit under predetermined imaging conditions. A focus detection device. The focus detection apparatus according to claim 1 or 2,
The predetermined shooting conditions are that the shutter release button is fully pressed, continuous shooting is being performed, and the focus state is repeatedly detected even after the focus state of the optical system is brought into focus. A focus detection device, wherein the focus detection position is at least one of the plurality of focus detection positions and the focus detection position for performing focus detection is specified from the plurality of focus detection positions. . The focus detection apparatus according to claim 1,
A contrast detection unit for detecting a focus state of the optical system by calculating an evaluation value related to the contrast of the image by the optical system based on the image signal output by the imaging unit;
The pair of light receiving sensors are provided on a light receiving surface of the imaging unit.   An imaging device provided with the focus detection apparatus in any one of Claims 1-4.

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