JP2013037101A - Focus detector and imaging apparatus - Google Patents

Abstract

A focus detection apparatus capable of appropriately performing focus detection of an optical system is provided.
An image pickup unit that picks up images by optical systems 31, 32, and 33 having a focus adjusting optical system and outputs an image signal; and a deviation amount of an image plane provided by a light receiving surface of the image pickup unit by the optical system. A phase difference detection unit that repeatedly detects the contrast, a contrast detection unit that detects a focus state of the optical system based on an image signal output from the imaging unit, and a focus adjustment optical system 32 in the optical axis direction of the optical system. As a result of the drive unit 36 to be driven and the phase difference detection unit detecting the focus state of the optical system, the reliability of the deviation amount detected by the phase difference detection unit is continuously determined a predetermined number of times. Scan driving that causes the phase difference detection unit and the contrast detection unit to detect the focus state of the optical system while driving the focus adjustment optical system in a predetermined direction when the driving unit is less than one threshold. And a control unit 21 to execute.
[Selection] Figure 1

Description

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

  Conventionally, when adjusting the focus of an optical system, in order to improve the focus adjustment accuracy, first, the focus state of the optical system is detected by the phase difference detection method, and the focus is determined based on the detection result by the phase difference detection method. The adjustment lens is driven to the vicinity of the focus position, and then the focus state of the optical system is detected by the contrast detection method in the vicinity of the focus position, and the focus adjustment lens is focused based on the detection result by the contrast detection method. A technique for driving to a position is known (for example, see Patent Document 1).

JP 2006-84545 A

  However, in the prior art, focus detection is first performed by the phase difference detection method, and subsequently focus detection is performed by the contrast detection method. Therefore, there is a problem that it takes time to detect the focus.

  The problem to be solved by the present invention is to provide a focus detection apparatus capable of appropriately performing focus detection of an optical system.

  The present invention solves the above problems by the following means. In the following description, the reference numerals corresponding to the drawings showing the embodiments of the present invention are used for explanation, but these reference numerals are only for facilitating the understanding of the present invention and are not intended to limit the invention. Absent.

  [1] A focus detection apparatus according to a first aspect of the present invention captures an image by an optical system (31, 32, 33) having a focus adjustment optical system, and outputs an image signal corresponding to the captured image. And (22) and a light receiving surface of the imaging unit, and repeatedly detecting the amount of deviation of the image plane by the optical system using a phase difference during imaging of the image by the imaging unit. By calculating an evaluation value related to the contrast of the image by the optical system based on the image signal output from the phase difference detection unit (222a, 222b) for detecting the focus state of the system and the imaging unit, the optical A contrast detection unit (221) for detecting a focus state of the system; a drive unit (36) for driving the focus adjustment optical system (32) in the optical axis direction of the optical system; System focus state detection As a result, when the reliability of the deviation amount detected by the phase difference detection unit is continuously less than a predetermined first threshold for a predetermined number of times, the driving unit is provided with the focus adjustment optical system. And a control unit (21) that performs scan driving that causes the phase difference detection unit and the contrast detection unit to detect the focus state of the optical system while driving in the direction of.

  [2] In the focus detection apparatus of the present invention, when the reliability of the shift amount is less than the first threshold value, a focus position exists in the optical axis direction based on the shift amount. It can be configured to be a threshold that can only determine the direction.

  [3] In the focus detection apparatus of the present invention, when the control unit (21) detects a deviation amount whose reliability is equal to or greater than a predetermined second threshold value by the phase difference detection unit during the scan driving. Can be configured to cause the drive unit (36) to drive the focus adjustment optical system (32) based on the shift amount.

  [4] The focus detection apparatus of the present invention may be configured such that the second threshold value is higher than the first threshold value.

  [5] The focus detection apparatus of the present invention can be configured such that the second threshold value is lower than the first threshold value.

  [6] A focus detection apparatus according to a second aspect of the present invention captures an image by an optical system (31, 32, 33) having a focus adjustment optical system, and outputs an image signal corresponding to the captured image. And (22) and a light receiving surface of the imaging unit, and repeatedly detecting the amount of deviation of the image plane by the optical system using a phase difference during imaging of the image by the imaging unit. By calculating an evaluation value related to the contrast of the image by the optical system based on the image signal output from the phase difference detection unit (222a, 222b) for detecting the focus state of the system and the imaging unit, the optical A contrast detection unit (221) for detecting a focus state of the system; a drive unit (36) for driving the focus adjustment optical system (32) in the optical axis direction of the optical system; System focus state detection As a result of performing, among the first predetermined number of deviation amounts continuously detected by the phase difference detection unit, the number of deviation amounts whose reliability is less than a predetermined first threshold is the second predetermined number. Scan driving that causes the phase difference detection unit and the contrast detection unit to detect the focus state of the optical system while causing the drive unit to drive the focus adjustment optical system in a predetermined direction. And a control unit (21) for executing the above.

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

  According to the present invention, focus detection of an optical system can be performed appropriately.

FIG. 1 is a block diagram showing a camera according to the present embodiment. FIG. 2 is a front view showing an 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 vicinity of the focus detection pixel row 22a 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. FIG. 8 is a diagram for explaining the sizes of the focus detection pixels 222a and 222b. FIG. 9 is a diagram for explaining the size of each pixel constituting the line sensor provided in the conventional phase difference detection module. 10 is a cross-sectional view taken along line XX of FIG. FIG. 11 is a flowchart showing the operation of the camera according to the present embodiment. FIG. 12 is a diagram illustrating the relationship between the focus lens position and the focus evaluation value and the relationship between the focus lens position and time in the search operation according to the present embodiment.

  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.

  The lens control unit 37 is electrically connected to the camera control unit 21 by an electric signal contact unit 41 provided on the mount unit 4, and is driven by the focus lens 32 and opened by the diaphragm 34 based on a command from the camera control unit 21. In addition to adjusting the aperture, lens information such as the position of the focus lens 32 and the aperture diameter of the diaphragm 34 is transmitted to the camera control unit 21.

  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 CCD or 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 camera memory 24 which is a recording medium. The camera memory 24 can be either a removable card type memory or a built-in memory. 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. Are output to the liquid crystal drive circuit 25 and the camera 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 an input switch for a photographer to set various operation modes of the camera 1 such as a shutter release button and a moving image shooting start switch. The operation unit 28 switches between an auto focus mode / manual focus mode and an auto focus mode. In particular, the one-shot mode / continuous mode can be switched. 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 imaging element 22, and FIG. 3 is a front view schematically showing the arrangement of the focus detection pixels 222a and 222b by enlarging the vicinity of the focus detection pixel row 22a in 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, on the imaging surface of the imaging element 22, five focus detection pixel rows 22a to 22e in which focus detection pixels 222a and 222b are arranged instead of the above-described imaging pixel 221 are provided. As shown in FIG. 3, one focus detection pixel column is configured by a plurality of focus detection pixels 222 a and 222 b being alternately arranged adjacent to each other in a horizontal row. 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 22e shown in FIG. 2 are not limited to the illustrated positions, and may be any one, two, three, or four locations, and more than six locations. It can also be arranged at the position. FIG. 3 shows an example in which the focus detection pixel array is configured by 16 focus detection pixels 222a and 222b, but the number of focus detection pixels configuring the focus detection pixel array is limited to this example. Is not to be done.

  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. Then, as shown in FIG. 3, these focus detection pixels 222a and 222b are alternately arranged adjacent to each other in a horizontal row, thereby forming focus detection pixel rows 22a to 22c shown in FIG.

  Here, as shown in FIG. 8, the focus detection pixels 222a and 222b are required to have substantially the same size as the imaging pixel 221 because of the structure thereof. Both the width L1 and the lateral width L2 are normally set to a size of about 10 μm or less. On the other hand, in the conventional line sensor (phase difference detection sensor) provided in the phase difference detection module, as shown in FIG. 9, there is no particular limitation on the size thereof, so the size of each pixel 50a of the line sensor 50 is large. In general, the vertical width L3 is set to about several hundred μm, and the horizontal width L4 is set to about several tens μm to several hundred μm. That is, the size of each pixel 50a of the conventional line sensor 50 is several hundreds μm × several tens μm to several hundreds μm, whereas the focus detection pixels 222a and 222b are set to a size of 10 μm square or less. Yes. FIG. 8 is a diagram for explaining the pixel sizes of the focus detection pixels 222a and 222b, and FIG. 9 shows the size of each pixel constituting the line sensor provided in the conventional phase difference detection module. It is a figure for demonstrating this.

  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. 10 is a cross-sectional view taken along the line XX in FIG. 3. The focus detection pixels 222 a-1, 222 b-1, 222 a-2, and 222 b-2 arranged in the vicinity of the photographing optical axis L 1 are adjacent to each other. It shows that light beams AB1-1, AB2-1, AB1-2, and AB2-2 irradiated from the distance measuring pupils 351 and 352 of the exit pupil 350 are received. 10 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. 10 are illustrated. In the same manner, the light beams emitted from the pair of distance measuring pupils 351 and 352 are respectively received.

  Here, the exit pupil 350 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 351 and 352 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. 10, the arrangement direction of the focus detection pixels 222a-1, 222b-1, 222a-2, and 222b-2 coincides with the arrangement direction of the pair of distance measurement pupils 351 and 352.

  Further, as shown in FIG. 10, 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 350 that is separated from the lenses 2221 a-1, 2221 b-1, 2221 a-2, and 2221 b-2 by a distance measurement distance D, and the projection shape forms distance measurement pupils 351 and 352.

  That is, the microlens and the photoelectric conversion unit in each focus detection pixel so that the projection shapes (distance measurement pupils 351 and 352) of the focus detection pixels coincide on the exit pupil 350 at the distance D. Is determined, and the projection direction of the photoelectric conversion unit in each focus detection pixel is thereby determined.

  As shown in FIG. 10, the photoelectric conversion unit 2222a-1 of the focus detection pixel 222a-1 is formed on the microlens 2221a-1 by a light beam AB1-1 that passes through the distance measuring pupil 351 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 351, 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 352, 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 352, 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 used as the distance measurement pupil 351. Of the pair of images formed on the focus detection pixel array by the focus detection light fluxes passing through each of the distance measurement pupil 351 and the distance measurement pupil 352. 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 by, for example, extracting a high frequency component of an image output from the imaging pixel 221 of the imaging element 22 using a high frequency transmission filter and integrating the extracted high frequency component. It can also be obtained by extracting high-frequency components using two high-frequency transmission filters having different cutoff frequencies and integrating them.

  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 example of the operation of the camera 1 in the present embodiment will be described along the flowchart shown in FIG. In the following, for example, an operation example in the case where still image shooting is performed by the camera 1 will be described below. The following operation is started when the camera 1 is turned on.

  First, in step S1, 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 predetermined intervals.

  In step S2, the camera control unit 21 starts defocus amount detection processing by the phase difference detection method. In the present embodiment, the defocus amount detection processing 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 five focus detection pixel rows 22a to 22d of the image sensor 22. In this case, when a specific focus detection position is selected by a user's manual operation, only data from focus detection pixels corresponding to the focus detection position may be read. Then, the camera control unit 21 performs image shift detection calculation processing (correlation calculation processing) based on the read pair of image data, and images at the focus detection positions corresponding to the five focus detection pixel rows 22a to 22d. The shift amount is calculated, and the image shift amount is converted into a defocus amount. Further, the camera control unit 21 evaluates the reliability of the detected defocus amount. Note that the reliability of the defocus amount is evaluated based on, for example, the degree of coincidence and contrast of a pair of image data. The defocus amount detection process using such a phase difference detection method is repeatedly executed at predetermined intervals.

  In the present embodiment, the camera control unit 21 performs the defocus amount detection process by the phase difference detection method, in addition to the detection of the defocus amount, the reliability of the detected defocus amount. An evaluation is also performed. In other words, in the present embodiment, the camera control unit 21 sets the reliability of the detected defocus amount to “high”, “medium”, “low” based on, for example, the matching degree or contrast of a pair of image data. ”And“ impossible range finding ”.

  Specifically, the camera control unit 21 uses the three determination values of the first determination value, the second determination value, and the third determination value to evaluate the reliability of the defocus amount. The reliability of the defocus amount is evaluated using these three determination values stored in advance in the memory.

  If the reliability of the defocus amount is equal to or higher than the first determination value, the first determination value is adjusted based on the defocus amount so that the defocus amount after the focus adjustment is It is set to a value that can be determined to be within the depth range. Therefore, for example, when the reliability of the defocus amount is equal to or higher than the first determination value, the camera control unit 21 focuses the subject by driving the focus lens 32 based on the defocus amount. The reliability of such a defocus amount is evaluated as “high”. Further, when the reliability of the defocus amount is less than the first determination value and is equal to or greater than a second determination value described later, the camera control unit 21 determines the focus lens based on the defocus amount. By driving the lens 32, the subject can be focused with a relatively high probability, and even when the subject cannot be focused, the lens position of the focus lens 32 after focus adjustment is determined to be in the vicinity of the focused position. The position can be set to such a position, and the reliability of such a defocus amount is evaluated as “medium”.

  Further, the second determination value is a value lower than the first determination value, and when the reliability of the defocus amount is less than the second determination value, the in-focus position is based on the defocus amount, The value is set so that it can be determined whether the optical axis direction is on the infinity side or the close side. Further, the third determination value is a value lower than the first determination value and the second determination value, and when the reliability of the defocus amount is less than the third determination value, the direction in which the in-focus position exists. Is set to a value that cannot be determined. Therefore, when the reliability of the defocus amount is less than the second determination value and greater than or equal to the third determination value, the camera control unit 21 determines that the in-focus position is based on this defocus amount. It is determined that it is possible to determine whether it exists on the infinity side or the close side in the optical axis direction, and the reliability of such a defocus amount is evaluated as “low”. Further, when the reliability of the defocus amount is less than the third determination value, the camera control unit 21 evaluates the reliability of the defocus amount as “distance cannot be measured”.

  Note that the detection of the defocus amount and the evaluation of the reliability of the defocus amount are repeatedly performed at predetermined intervals while the operation of the camera 1 is being performed. Further, the defocus amount and the reliability of the defocus amount obtained in this way are stored in the memory 24 as defocus amount history data.

  In step S <b> 3, the camera control unit 21 starts a focus evaluation value calculation process. In the present embodiment, the focus evaluation value calculation process is performed by reading out the pixel output of the imaging pixel 221 of the imaging element 22, extracting a high-frequency component of the read-out pixel output using a high-frequency transmission filter, and accumulating these. Done. The focus evaluation value is calculated only when the specific focus detection position is selected by the user's manual operation or the subject recognition mode, and only the pixel output of the imaging pixel 221 corresponding to the selected focus detection position. It is good also as a structure which reads. The focus evaluation value calculation process is repeatedly executed at predetermined intervals.

  In step S4, 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 S5. On the other hand, if the first switch SW1 is not turned on, step S4 is repeated until the first switch SW1 is turned on. That is, until the first switch SW1 is turned on, the through image generation / display, the defocus amount detection process by the phase difference detection method, and the focus evaluation value calculation process are repeatedly executed.

  In step S <b> 5, the camera control unit 21 determines whether or not a defocus amount whose reliability is “high” or “medium” is detected by the defocus amount detection process using the phase difference detection method. That is, it is determined whether or not a defocus amount whose reliability value is equal to or greater than the second determination value described above is detected. If the defocus amount with the reliability “high” or “medium” is detected, the process proceeds to step S13. On the other hand, the defocus amount with the reliability “high” or “medium” cannot be detected. If, in other words, only the defocus amount whose reliability is “low” or “distance cannot be measured” is detected, the process proceeds to step S6. Note that whether or not a defocus amount having a reliability of “high” or “medium” has been detected by the phase difference detection method is determined as a result of the defocus amount detection process after the first switch SW1 is turned on. Alternatively, the result of the defocus amount detection process immediately before the first switch SW1 is turned on may be used.

  In step S5, if it is determined that a defocus amount with a reliability of “high” or “medium” has been detected, the process proceeds to step S13, where the matching based on the defocus amount detected by the phase difference detection method is performed. A focusing operation is performed. Specifically, in step S13, processing for driving the focus lens 32 to the in-focus position is performed based on the defocus amount detected by the phase difference detection method. Specifically, 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 detected by the phase difference detection method. The lens driving amount is sent to the lens driving motor 36 via the lens control unit 37. Then, the lens driving motor 36 drives the focus lens 32 to the in-focus position based on the lens driving amount calculated by the camera control unit 21.

  In the present embodiment, the camera control unit 21 repeatedly detects the defocus amount by the phase difference detection method even while the lens driving motor 36 is driven and the focus lens 32 is driven to the in-focus position. As a result, when a new defocus amount (a defocus amount whose reliability is “high” or “medium”) is detected, the camera control unit 21 performs the following operation based on the new defocus amount. The focus lens 32 is driven.

  In step S13, the camera control unit 21 performs a scanning operation prohibition process as well as a process of driving the focus lens 32 to the in-focus position. Specifically, the camera control unit 21 sends a scan operation prohibition command to the lens control unit 37, and the scan operation is prohibited. The scan operation will be described later.

  When the driving of the focus lens 32 to the in-focus position is completed, the process proceeds to step S15.

  On the other hand, if the defocus amount having the reliability “high” or “medium” is not detected in step S5, the process proceeds to step S6. In step S6, the camera control unit 21 uses the phase difference detection method. By the defocus amount detection process, it is determined whether or not a defocus amount having a reliability of “low” or “distance cannot be measured” has been continuously detected a predetermined number of times α. That is, it is determined whether or not the defocus amount whose reliability value is less than the above-described second determination value has been detected a predetermined number of times. When a defocus amount with a reliability of “low” or “incapable of ranging” is detected continuously a predetermined number of times, that is, when the reliability is “high” or “medium” continuously a predetermined number of times If a certain defocus amount is not detected, the process proceeds to step S7, and a scanning operation described later is executed. On the other hand, if a defocus amount with a reliability of “low” or “incapable of ranging” is detected, but is not continuous a predetermined number of times α, the process returns to step S5 and the reliability is “high” or “ The determination whether or not the defocus amount “medium” is detected is repeatedly executed. If a defocus amount with a reliability of “high” or “medium” is detected, the process proceeds to step S13, and the focus lens 32 is driven to the in-focus position based on the detected defocus amount. On the other hand, when the defocus amount having the reliability of “low” or “unranging” is continuously detected a predetermined number of times as a result of repeatedly performing the operations of steps S5 and S6, In step S7, a scan operation described later is executed.

  The predetermined number α is not particularly limited. For example, the predetermined number α is a value that can sufficiently eliminate the influence of variations in reliability and the influence of camera shake by the photographer in the defocus amount detection processing by the phase difference detection method. Can be set to In other words, in a situation where the defocus amount, which is originally “high” or “medium”, can be detected, the reliability is affected by the effects of variations in reliability and the effects of camera shake by the photographer. When a defocus amount with low or inability to measure distance is detected, it is determined that the defocus amount with high or medium reliability cannot be detected by mistake. The predetermined number of times α can be set to a value that can prevent this. For example, the predetermined number α can be set to preferably 5 or more, more preferably about 5 to 10.

  If the defocus amount with the reliability of “low” or “incapable distance measurement” is detected continuously a predetermined number of times α, the process proceeds to step S7. In step S7, the camera control unit 21 performs the scan operation. Start processing is performed. In the scanning operation of the present embodiment, the focus lens drive motor 36 scans the focus lens 32 at a predetermined driving speed, and the camera control unit 21 detects the defocus amount by the phase difference detection method and performs focus evaluation. The calculation of the value is performed simultaneously at a predetermined interval, whereby 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 performed simultaneously at the predetermined interval. .

  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 at a predetermined driving speed. The driving speed of the focus lens 32 when performing the scanning operation is not particularly limited. For example, the driving speed is suitable for detecting the defocus amount by the phase difference detection method, specifically, the phase difference detection method. The maximum speed that can detect the defocus amount, or a speed that is slower than the maximum speed among the speeds that can detect the defocus amount by the phase difference detection method (for example, speed error or detection error). The maximum speed among the speeds in consideration of the above and the like. Further, 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. In this case, the infinity end position is set to a predetermined position (infinity-side soft limit position) that is closer to the mechanical limit position determined by the structure of the lens barrel 3. Similarly, the closest end position is also set to a predetermined position (closest side soft limit position) on the infinity side of the mechanical limit position determined by the structure of the lens barrel 3.

  The camera control unit 21 reads 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 a predetermined interval while driving the focus lens 32 at a predetermined driving speed. Based on this, the defocus amount is detected and the reliability of the detected defocus amount is evaluated by the phase difference detection method, and the focus lens 32 is driven at a predetermined driving speed and imaged at a predetermined interval. The pixel output is read out from the imaging pixel 221 of the element 22, and based on this, a focus evaluation value is calculated, thereby acquiring a focus evaluation value at a different focus lens position. Perform detection.

  In step S8, as a result of the scanning operation performed by the camera control unit 21, a defocus amount whose reliability is “high” by the phase difference detection method, that is, a defocus amount whose reliability is equal to or higher than the first determination value described above. If the focus amount is detected, the process proceeds to step S13. On the other hand, if the defocus amount with high reliability cannot be detected, the process proceeds to step S9.

  In step S9, the camera control unit 21 determines whether or not the in-focus position has been detected by the contrast detection method as a result of the scanning operation. If the in-focus position can be detected by the contrast detection method, the process proceeds to step S14. If the in-focus position cannot be detected, the process proceeds to step S10.

  In step S <b> 10, 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 on the entire driveable range of the focus lens 32, the process returns to step S8, and the steps S8 to S10 are repeated, so that the scan lens, that is, the focus lens 32 is moved at a predetermined drive speed. While driving, the operation of simultaneously executing the detection of the defocus amount by the phase difference detection method and the detection of the in-focus position by the contrast detection method at a predetermined interval is continuously performed. On the other hand, if the scan operation has been completed for the entire driveable range of the focus lens 32, the process proceeds to step S11.

  As a result of executing the scanning operation, when it is determined in step S8 that the defocus amount with high reliability can be detected by the phase difference detection method, the scanning operation is stopped, and the process proceeds to step S13. In the same manner as described above, a focusing operation based on the defocus amount detected by the phase difference detection method is performed. When the driving of the focus lens 32 to the in-focus position is completed, the process proceeds to step S15.

  As a result of executing the scanning operation, when it is determined in step S9 that the in-focus position has been detected by the contrast detection method, the scanning operation is stopped, and the process proceeds to step S14 where the detection is performed by the contrast detection method. A focusing operation based on the focusing position is performed. That is, in step S14, 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. Here, FIG. 12 is a diagram showing the relationship between the focus lens position and the focus evaluation value and the relationship between the focus lens position and time when the in-focus position is detected by the contrast detection method as a result of the scanning operation. Show. As shown in FIG. 12, at the start of the scanning operation, the focus lens 32 is positioned at P0 shown in FIG. 12, and the focus lens 32 is driven at a predetermined drive speed from P0 toward the near side from P0. The focus evaluation value is acquired. When the focus lens 32 is moved to the position P1 shown in FIG. 12 and the peak position (focus position) of the focus evaluation value is detected (step S9 = Yes), the scanning operation is stopped, Focus drive (step S14) for driving the focus lens 32 to the focus position (position P2 in FIG. 12) is performed. Further, when performing in-focus driving, the camera control unit 21 stops the scanning operation and performs a scanning operation prohibiting process.

  In the present embodiment, when it is determined in step S9 that the in-focus position has been detected by the contrast detection method, the focus lens 32 is driven to the in-focus position based on the detection result by the contrast detection method. In other words, until the drive of the focus lens 32 to the in-focus position is completed, the drive of the focus lens 32 based on the focus detection result by the phase difference detection method is prohibited. That is, after it is determined that the in-focus position can be detected by the contrast detection method, even when the defocus amount can be detected by the phase difference detection method, the focus lens 32 is driven based on the result of the phase difference detection method. Is prohibited. Thereby, the hunting phenomenon of the focus lens 32 can be suppressed.

  When the driving of the focus lens 32 to the in-focus position is completed, the process proceeds to step S15.

  In the scanning operation of the present embodiment, the above-described steps S8 to S10 are repeatedly executed to detect the defocus amount by the phase difference detection method while the focus lens 32 is scan-driven at a predetermined driving speed. And the detection of the in-focus position by the contrast detection method is simultaneously executed at predetermined intervals. As a result of repeatedly executing steps S8 to S10 described above, it was possible to detect the defocus amount or the in-focus position where the reliability was “high” first in the phase difference detection method and the contrast detection method. The focus lens 32 is driven to the in-focus position using the focus detection result by the detection method. Further, as described above, in the scanning operation of the present embodiment, after determining whether or not the defocus amount with high reliability can be detected by the phase difference detection method (step S8), the contrast detection method By determining whether or not the in-focus position has been detected by (step S9), it is possible to detect and focus the defocus amount with high reliability at the same time in the phase difference detection method and the contrast detection method. When the focus position can be detected, the focus detection result by the phase difference detection method is used with priority over the focus detection result by the contrast detection method.

  Therefore, according to the present embodiment, when it is difficult to detect the focus state of the photographing optical system by the phase difference detection method (for example, when photographing a subject having a different reflectance and a different color, or photographing a low-luminance subject) The focus detection of the photographic optical system is appropriately performed in both cases where it is difficult to detect the focus state of the photographic optical system using a contrast detection method (for example, when shooting a subject with low brightness). Can do. In addition, according to the present embodiment, the defocus amount detection by the phase difference detection method and the in-focus position detection by the contrast detection method are simultaneously performed, and the focus of the photographing optical system is detected by the method in which the focus detection can be performed first. Compared with the conventional technique (that is, a technique in which the focus lens 32 is driven to the vicinity of the in-focus position by the phase difference detection method and then the in-focus position is detected in the vicinity of the in-focus position by the contrast detection method). Thus, the focus adjustment of the photographing optical system can be performed in a short time.

  On the other hand, if it is determined in step S10 that the scan operation has been completed for the predetermined drive range, the process proceeds to step S11. In step S11, 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 that the scanning operation end processing is performed, and then in step S12 Advancing and out-of-focus processing is performed. As the out-of-focus process, for example, a display indicating out-of-focus is displayed on the electronic viewfinder 26 and the focus lens 32 is driven to a predetermined position.

  If the focus lens 32 is driven to the in-focus position based on the results of the phase difference detection method or the contrast detection method in steps S13 and S14, the process proceeds to step S15 after the drive of the focus lens 32 is completed. Then, it is determined whether or not the shutter release button provided in the operation unit 28 is fully pressed (the second switch SW2 is turned on). If the shutter release button is fully pressed (the second switch SW2 is turned on), the process proceeds to step S16, where the subject image is shot (main shooting), and the process returns to step S1. On the other hand, if the shutter release button is not fully pressed (the second switch SW2 is turned on), the process proceeds to step S17.

  In step S <b> 17, after the focus lens 32 is driven to the in-focus position by the camera control unit 21, the defocus whose reliability is “high” or “medium” by the phase difference detection method at the current lens position. A determination is made whether an amount has been detected. If the defocus amount with the reliability “high” or “medium” is detected, the process proceeds to step S19. On the other hand, when the defocus amount with the reliability “high” or “medium” cannot be detected, that is, when the defocus amount with the reliability “low” or “range measurement impossible” is detected. Advances to step S18.

  In step S18, as in step S6 described above, the camera control unit 21 uses the phase difference detection method to determine a defocus amount whose reliability is “low” or “incapable of distance measurement” a predetermined number of times α times. A determination is made as to whether or not they have been continuously detected. When the defocus amount whose reliability is “low” or “range measurement impossible” is continuously detected a predetermined number of times α, the process returns to step S7, and the above-described scanning operation is executed again. On the other hand, when the defocus amount with the reliability of “low” or “incapable of ranging” is detected, but is not continuous a predetermined number of times α, the process returns to step S18 and the reliability is “high” or “ The determination whether or not the defocus amount “medium” is detected is repeatedly executed. When a defocus amount with a reliability of “high” or “medium” is detected, the process proceeds to step S19, while the operations of steps S17 and S18 are repeatedly executed. As a result, the reliability is “low”. Alternatively, when the defocus amount that is “distance cannot be measured” is continuously detected a predetermined number of times α, the process returns to step S7 and the above-described scanning operation is executed again.

  In step S17, when a defocus amount with a reliability of “high” or “medium” is detected by the phase difference detection method, the process proceeds to step S19, and in step S19, the focus state of the optical system has changed. A determination is made whether or not. Specifically, when the value of the defocus amount by the phase difference detection method is equal to or greater than a predetermined value (for example, when the value of the defocus amount exceeds the depth of field), the optical system It can be determined that the focus state has changed. If it is determined in step S19 that the focus state of the optical system has changed, the process returns to step S13, and processing for driving the focus lens 32 is performed based on the latest detected defocus amount. On the other hand, if it is determined that the focus state of the optical system has not changed, the process returns to step S15, and the processes of steps S15 to S19 are repeated.

  As described above, the camera 1 according to this embodiment operates.

  In the present embodiment, even when a defocus amount having a reliability of “low” or “incapable of ranging” is detected by the phase difference detection method, the scan operation is not immediately performed, and the reliability is “low”. "" Or "distance cannot be measured" shifts to the scanning operation only when the defocus amount is detected a predetermined number of times in succession. Therefore, according to the present embodiment, in a situation where the defocus amount, which is originally “high” or “medium”, can be detected, the influence of the reliability variation, or by the photographer When a defocus amount with low reliability or inability to measure distance is detected due to the effects of camera shake, the defocus amount with high or medium reliability is erroneously detected. By determining that the scene cannot be detected and shifting to the scan operation, it is possible to effectively prevent a problem that the scan operation is frequently executed. In particular, if the scanning operation is frequently executed, hunting may occur between the focusing drive of the focus lens 32 based on the detection result by the phase difference detection method and the scanning driving of the focus lens 32 by the scanning operation. On the other hand, according to the present embodiment, occurrence of such a problem can be effectively prevented.

  In addition, in the present embodiment, after the defocus amount having the reliability of “low” or “distance cannot be measured” is continuously detected a predetermined number of times α and the process shifts to the scanning operation, the reliability is “high”. Unless the defocus amount is detected, the focus lens 32 is not driven based on the defocus amount detected by the phase difference detection method. That is, after the shift to the scanning operation, even if a defocus amount with a medium reliability is detected, the focus lens 32 is focused based on the defocus amount detected by the phase difference detection method. Avoid driving. Thereby, according to the present embodiment, it is possible to further improve the focus detection accuracy by the scanning operation. In particular, when a defocus amount with a reliability of “low” or “incapable of distance measurement” is continuously detected a predetermined number of times α, it is difficult to detect the focus state of the photographing optical system by the phase difference detection method. In this way, the reliability is “high” during the scanning operation. Only when the defocus amount is detected, the focus lens 32 is driven based on the defocus amount detected by the phase difference detection method, so that the phase difference detection method is used. The occurrence of false detection can be effectively prevented.

  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, the focus lens 32 is focused on the basis of the defocus amount detected by the phase difference detection method unless the defocus amount with high reliability is detected during the scan operation. Although the driving is not performed, the focus lens 32 is driven based on the detected defocus amount even when the reliability is “medium” or “low” in addition to the reliability “high”. It is good also as a structure which performs. In particular, during the scanning operation, since the focus lens 32 is driven and the defocus amount is detected by the phase difference detection method, the defocus amount is detected while the focus lens 32 is stopped. Compared to the case, the defocus amount obtained tends to be less reliable. That is, for example, when the focus lens 32 is stopped, even when the reliability of the defocus amount is “high”, if the focus lens 32 is driven, the reliability of the defocus amount is “low”. Therefore, even in such a case, the focus adjustment of the photographing optical system can be performed by performing the focusing drive of the focus lens 32 based on the detected defocus amount. Can be executed in a short time.

  Further, in the above-described embodiment, the configuration is such that when the defocus amount whose reliability is “low” or “distance cannot be measured” is continuously detected a predetermined number of times α, the scan operation is started. The number of defocus amounts whose reliability is “low” or “incapable of ranging” among the defocus amounts detected continuously β times a predetermined number of times is a predetermined number γ (γ <β) or more. In addition, it may be configured to shift to a scanning operation. That is, as an example, a configuration that shifts to a scanning operation when a defocus amount of 8 or more out of 10 defocus amounts detected continuously is reliability “low” or “range measurement impossible” It can be.

  Further, in the above-described embodiment, when the defocus amount having the reliability of “low” or “distance cannot be measured” is continuously detected a predetermined number of times α, before the shift to the scanning operation, the focus lens 32. While performing the wobbling drive, a wobbling operation for simultaneously performing detection of the in-focus position by the phase difference detection method and in-focus position detection by the contrast detection method may be executed. In this case, as a result of executing the wobbling operation, when a defocus amount with high reliability is detected by the phase difference detection method, the detection is performed without shifting to the scanning operation. Based on the defocus amount, the focus lens 32 can be driven to the in-focus position, and when the in-focus position can be detected by the contrast detection method as a result of executing the wobbling operation, the operation proceeds to the scan operation. The focus lens 32 can be driven to focus at the in-focus position detected by the contrast detection method. In this case, the scan driving direction of the focus lens 32 when executing the scan operation can be determined based on the focus detection results of the phase difference detection method and the contrast detection method in the wobbling operation. In other words, when the focus detection by the phase difference detection method or the contrast detection method when the wobbling operation is executed, it can be determined that the in-focus position exists on the infinity side from the current lens position (for example, in the contrast detection method) When the focus evaluation value increases toward the infinity side), the driving direction of the focus lens 32 during the scanning operation may be changed from the current lens position to the infinity direction. it can. Alternatively, when the focus detection by the phase difference detection method or the contrast detection method when the wobbling operation is executed, it can be determined that the in-focus position is closer to the current lens position (for example, in the contrast detection method, When the focus evaluation value increases toward the close side), the driving direction of the focus lens 32 when performing the scanning operation can be changed from the current lens position to the close direction.

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

Claims (7)

An imaging unit that captures an image by an optical system having a focus adjustment optical system and outputs an image signal corresponding to the captured image;
The focus state of the optical system is detected by repeatedly detecting the amount of displacement of the image plane by the optical system using the phase difference during imaging of the image by the imaging unit. A phase difference detector that
A contrast detection unit that detects 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;
A drive unit that drives the focus adjustment optical system in the optical axis direction of the optical system;
As a result of causing the phase difference detection unit to detect the focus state of the optical system, the reliability of the deviation amount detected by the phase difference detection unit was continuously less than a predetermined first threshold value a predetermined number of times. In this case, the control for executing the scan driving for causing the phase difference detection unit and the contrast detection unit to detect the focus state of the optical system while causing the drive unit to drive the focus adjustment optical system in a predetermined direction. And a focus detection device. The focus detection apparatus according to claim 1,
The first threshold value is a threshold value such that when the reliability of the deviation amount is less than the first threshold value, the direction in which the in-focus position exists in the optical axis direction can be determined based on the deviation amount. A focus detection apparatus. The focus detection apparatus according to claim 1 or 2,
When the phase difference detection unit detects a deviation amount having a reliability equal to or higher than a predetermined second threshold during the scan driving, the control unit causes the driving unit to determine the deviation amount based on the deviation amount. A focus detection apparatus, wherein the focus adjustment optical system is driven to focus. The focus detection apparatus according to claim 3,
The focus detection apparatus, wherein the second threshold value is higher than the first threshold value. The focus detection apparatus according to claim 3,
The focus detection apparatus according to claim 1, wherein the second threshold value is lower than the first threshold value. An imaging unit that captures an image by an optical system having a focus adjustment optical system and outputs an image signal corresponding to the captured image;
The focus state of the optical system is detected by repeatedly detecting the amount of displacement of the image plane by the optical system using the phase difference during imaging of the image by the imaging unit. A phase difference detector that
A contrast detection unit that detects 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;
A drive unit that drives the focus adjustment optical system in the optical axis direction of the optical system;
As a result of causing the phase difference detection unit to detect the focus state of the optical system, the reliability of the first predetermined number of deviations continuously detected by the phase difference detection unit is predetermined. When the number of deviation amounts less than the threshold is equal to or greater than a second predetermined number, the phase difference detection unit and the contrast detection are performed while the drive unit drives the focus adjustment optical system in a predetermined direction. And a control unit that executes scan driving for causing the unit to detect the focus state of the optical system.   The imaging device provided with the focus detection apparatus in any one of Claims 1-6.

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