JP5891667B2 - Focus adjustment device and imaging device provided with the same - Google Patents

Description

  The present invention relates to a focus adjustment apparatus and an imaging apparatus including the same.

  2. Description of the Related Art Conventionally, a technique for detecting a focal state of an optical system by detecting a shift amount of an image plane by the optical system using a phase difference is known (see, for example, Patent Document 1).

JP 2002-277724 A

  However, in the related art, there are cases where the focus state of the optical system cannot be detected when it is difficult to detect the focus state of the optical system using the phase difference, such as when shooting a low-luminance subject.

  The problem to be solved by the present invention is to provide a focus adjustment device that can appropriately detect the focus state of an optical system.

  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] focusing device according to the present invention includes a first detector for detecting the defocus using the phase difference, and a second detector for detecting a focus evaluation value, the detected by the first detector A first focus position is calculated using defocus, a second focus position is calculated using the focus evaluation value detected by the second detector, and the first focus position and the second focus position are calculated. A calculation unit that calculates a third in-focus position using the focal position; and a control unit that performs control to move the focus lens to the third in-focus position calculated by the calculation unit.

  According to the present invention, it is possible to appropriately detect the focus state of the optical system.

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 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 showing the operation of the camera 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.

  In addition, the lens control unit 37 stores data for setting a scan driving range of the focus lens 32, that is, data for setting the scan range, in a scan operation described later in a memory included in the lens control unit 37 as scan range data. Yes. Specifically, the lens control unit 37 stores, as scan range data, the number of pulses corresponding to the lens drive amount necessary for the focus lens 32 to scan and drive a predetermined scan range. For example, when the entire range in which the focus lens 32 can be driven is set as the scan range, the lens control unit 37 is necessary for the focus lens 32 to scan and drive the entire range in which the focus lens 32 can be driven. The number of pulses corresponding to the lens driving amount can be stored as scan range data. For example, when the predetermined range near the current lens position of the focus lens 32 is set as the scan range, the lens control unit 37 sets the predetermined range near the current lens position of the focus lens 32 to the focus lens 32. The number of pulses corresponding to the lens driving amount necessary for scanning driving can be stored as scanning range data.

  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. 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 an input switch for a photographer to set various operation modes of the camera 1, such as a shutter release button, and can switch between an auto focus mode and a manual focus mode. 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 device 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.

  In addition, focus detection pixel rows 22a, 22b, and 22c in which focus detection pixels 222a and 222b are arranged in place of the above-described imaging pixels 221 at the center of the image pickup surface of the image pickup element 22 and three positions that are symmetrical from the center. Is provided. As shown in FIG. 3, one focus detection pixel column includes a plurality of focus detection pixels 222 a and 222 b that are alternately arranged adjacent to each other in a horizontal row (22 a, 22 c, 22 c). Yes. 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 22c shown in FIG. 2 are not limited to the illustrated positions, and may be any one or two, or may be arranged at four or more positions. it can. In actual focus detection, a photographer manually operates the operation unit 28 from among a plurality of focus detection pixel rows 22a to 22c, and selects a desired focus detection pixel row as a focus detection area. 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. 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.

  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 shape of the photoelectric conversion units 2222a and 2222b is 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 351 and 352 of the exit pupil 350 are received. 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 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. 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 351, 352.

  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 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. 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 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 focal plane corresponding to the current focal plane (the position corresponding to the position of the microlens array on the planned focal plane) The deviation of the focal plane in the detection area), 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 imaging element 22 using a high-frequency transmission filter. It can also be obtained by extracting high-frequency components using two high-frequency transmission filters having different cutoff frequencies.

  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 the operation of the camera 1 according to this embodiment. The following operation is started when the camera 1 is turned on.

  First, in step S101, 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 each of the focus detection pixels 222a and 222b constituting the three focus detection pixel rows 22a to 22c of the image sensor 22. 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 three focus detection pixel rows 22a to 22c. 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 calculated 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 calculation process using such a phase difference detection method is repeatedly executed at predetermined intervals.

  In step S102, 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 calculation process is repeatedly executed at predetermined intervals.

  In step S103, 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 S104. On the other hand, if the first switch SW1 is not turned on, step S103 is repeated until the first switch SW1 is turned on. That is, the defocus amount calculation process by the phase difference detection method and the focus evaluation value calculation process by the contrast detection method are repeatedly executed until the first switch SW1 is turned on.

  In step S104, the camera control unit 21 determines whether or not the defocus amount can be calculated 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 S113. 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 S105. In the present embodiment, even when the defocus amount can be calculated, even when the reliability of the calculated defocus amount is low, it is treated that the defocus amount cannot be calculated, and the process returns to step S105. Let's go ahead. In the present embodiment, for example, when the subject has a low contrast, the subject is an ultra-low brightness subject, or the subject is an ultra-high brightness subject, it is determined that the reliability of the defocus amount is low. .

  In step S104, the above determination is performed using the result of the most recent defocus amount calculation process. However, the defocus amount is continuously calculated in the most recent predetermined number of defocus amount calculation processes. If not, or if the reliability of the defocus amount is low continuously, it is determined that distance measurement is impossible, and the process proceeds to step S105. Conversely, in the defocus amount calculation process of the most recent predetermined number of times. If the defocus amount is calculated even once, it may be determined that distance measurement is possible and the process proceeds to step S113.

  If it is determined in step S104 that the defocus amount has been calculated and it is determined that distance measurement is possible, the process proceeds to step S113, and focusing driving based on the defocus amount calculated by the phase difference detection method is performed. Specifically, the camera control unit 21 calculates and 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. 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 calculates the defocus amount by the phase difference detection method 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 is calculated, the camera control unit 21 drives the focus lens 32 based on the new defocus amount.

  On the other hand, if it is determined in step S104 that the defocus amount cannot be calculated by the phase difference detection method, the process proceeds to step S105, and the scan operation is executed in steps S105 to S109. Here, the scan operation refers to the calculation of the defocus amount by the phase difference detection method and the focus evaluation value by the camera control unit 21 while the focus lens 32 is scan-driven in the predetermined scan range by the focus lens drive motor 36. This calculation is performed simultaneously at predetermined intervals, 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, first, in step S105, the camera control unit 21 acquires scan range data. The scan range data is data for setting a range in which the focus lens 32 is scan-driven in a scan operation, that is, a scan range. In the present embodiment, as the scan range data, the number of pulses corresponding to the lens driving amount necessary for the focus lens 32 to scan and drive the predetermined scan range is stored in the memory provided in the lens control unit 37, and the step In S <b> 105, the camera control unit 21 acquires such scan range data from the lens control unit 37.

  In step S106, the camera control unit 21 sets a scan range based on the scan range data acquired in step S105. For example, the camera control unit 21 can acquire, as scan range data, the number of pulses corresponding to the lens driving amount necessary for the focus lens 32 to drive the entire range in which the focus lens 32 can be driven, In this case, the entire range in which the focus lens 32 can be driven can be set as the scan range based on the scan range data. In addition, for example, when the scan operation is performed again after driving the focus lens 32 to the in-focus position, the camera control unit 21 determines the in-focus position near the current lens position of the focus lens 32. A range that can be detected (for example, a range in which focus evaluation values can be acquired at five lens positions), and the number of pulses corresponding to the lens driving amount necessary for driving the focus lens 32 as scan range data. In this case, based on this scan range data, a range in which the in-focus position near the current lens position of the focus lens 32 can be detected can be set as the scan range.

  In step S107, the camera control unit 21 starts a scan operation so as to execute the scan operation for the entire scan range set in step S106.

  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 set In the scan range, the focus 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.

  Before starting the scanning operation, wobbling driving for reciprocally driving the focus lens 32 in the optical axis direction may be performed. In this case, while performing wobbling driving, focus detection by the phase difference detection method and focus detection by the contrast detection method are simultaneously performed, and if the focus state can be detected by any one of the focus detection methods, the detected focus is detected. The focus lens 32 may be driven in focus based on the detection result. Further, in this case, the reliability of the defocus amount calculated by the phase difference detection method during the wobbling drive can be determined, and the reliability of the defocus amount can detect the in-focus position based on the focus detection result. Even if it is not as high as possible, if there is enough reliability to determine the direction in which the in-focus position exists, determine the direction in which the in-focus position exists based on the calculated defocus amount, A configuration may be adopted in which scan driving is started in the determined direction.

  In step S108, the camera control unit 21 determines whether or not a scan operation has been performed for the entire scan range set in step S106. In this embodiment, even when the defocus amount can be calculated by the phase difference detection method or the in-focus position can be detected by the contrast detection method during execution of the scan operation, the scan operation is not terminated. A scan operation is performed for the entire scan range set in step S106. Therefore, if it is determined in step S108 that the scan operation is not performed for the entire scan range, the process waits in step S108, and the focus lens 32 is held until the scan operation is completed for the entire scan range. While performing scanning driving, a scanning operation is continuously performed in which the calculation of the defocus amount 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. When the scan operation is performed for the entire scan range, the process proceeds to step S109. After the scan operation is completed in step S109, the process proceeds to step S110.

  In step S110, the camera control unit 21 compares the reliability of the defocus amount calculated by the phase difference detection method in the scanning operation with the reliability of the in-focus position detected by the contrast detection method in the scanning operation. Is called. Note that the reliability of the focus position detected by the contrast detection method is, for example, the magnitude of the focus evaluation value calculated for detecting the focus position or the vicinity of the peak position (focus position) of the focus evaluation value. Evaluation can be made based on the inclination of the peak of the focus evaluation value.

  As a result of the comparison in step S110, it is determined that the reliability of the defocus amount calculated by the phase difference detection method in the scanning operation is higher than the reliability of the in-focus position detected by the contrast detection method in the scanning operation. If YES in step S111, the flow advances to step S111. On the other hand, the reliability of the in-focus position detected by the contrast detection method in the scanning operation is higher than the reliability of the defocus amount calculated by the phase difference detection method in the scanning operation. If it is determined, the process proceeds to step S112. If the defocus amount cannot be calculated by the phase difference detection method in the scanning operation, the process proceeds to step S112.

  In step S111, since it is determined that the reliability of the defocus amount calculated by the phase difference detection method in the scanning operation is higher than the reliability of the in-focus position detected by the contrast detection method in the scanning operation, the camera As in step S113, the control unit 21 performs focus driving for driving the focus lens 32 to the focus position based on the defocus amount calculated by the phase difference detection method.

  On the other hand, if the reliability of the in-focus position detected by the contrast detection method in the scanning operation is higher than the reliability of the defocus amount calculated by the phase difference detection method in the scanning operation, the process proceeds to step S112, and the camera The control unit 21 performs focusing driving for driving the focus lens 32 to the in-focus position based on the in-focus position detected by the contrast detection method. If the in-focus position cannot be detected by the phase difference detection method, and if the in-focus position cannot be detected by the contrast detection method, the focus lens 32 is driven to a predetermined lens position, and then the in-focus display is performed. It is good also as a structure.

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

  As described above, the camera 1 according to the present embodiment performs a scan operation in which focus detection by the phase difference detection method and focus detection by the contrast detection method are simultaneously performed while driving the focus lens 32 in the entire predetermined scan range. Run about. Then, based on the focus detection result by the phase difference detection method and the focus detection result by the contrast detection method when the scan operation is performed for the entire area of the predetermined scan range, the focus position is detected, The focus of the optical system is adjusted by driving the detected focus position. As described above, according to the present embodiment, since focus detection by the phase difference detection method and focus detection by the contrast detection method are performed simultaneously, it is difficult to detect the focus state of the photographing optical system by the phase difference detection method ( For example, when shooting a subject with the same reflectivity and different colors, or shooting a low-luminance subject, or when it is difficult to detect the focus state of the photographic optical system using a contrast detection method (for example, the luminance is low). In either case of photographing a subject, the focus detection of the photographing optical system can be performed appropriately.

  Further, according to the present embodiment, when the defocus amount can be calculated by the phase difference detection method and the in-focus position can be detected by the contrast detection method as a result of executing the scanning operation for the entire predetermined scan range. Compare the reliability of the defocus amount calculated by the phase difference detection method with the reliability of the in-focus position detected by the contrast detection method, and adjust the focus based on the more reliable focus detection result I do. Thus, according to the present embodiment, the focus detection results obtained by the phase difference detection method and the contrast detection method can be compared, and the focus adjustment can be performed based on the more reliable focus detection result. Compared to performing focus adjustment based only on the focus detection result obtained by either one of the phase difference detection method and the contrast detection method, false focusing can be effectively prevented, and the optical system Focus adjustment can be performed with higher accuracy.

  Furthermore, in this embodiment, by performing scan driving over the entire predetermined scan range, for example, even when a plurality of lens positions (peak positions) at which the focus evaluation value peaks are detected by the contrast detection method, Since the peak position of the focus evaluation value corresponding to the focal position can be appropriately selected, false focusing can be prevented more effectively, and the focus adjustment of the optical system can be performed more appropriately.

  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 focus detection result by the phase difference detection method and the contrast detection method is obtained as a result of performing the scanning operation for the entire scan range, the focus detection result by the phase difference detection method, Of the focus detection results by the contrast detection method, the configuration in which the focus lens 32 is driven based on the more reliable focus detection result is illustrated, but the configuration is not limited to this configuration. For example, in step S106 As a result of performing the scanning operation over the entire set scan range, when the defocus amount can be calculated by the phase difference detection method and the in-focus position can be detected by the contrast detection method, it is calculated by the phase difference detection method. The focus position obtained based on the defocus amount and the focus detected by the contrast detection method The average position of the positions may be a focusing lens 32 as a configuration for driving the focus. Alternatively, the defocus amount calculated by the phase difference detection method is calculated with respect to the focus position obtained based on the defocus amount calculated by the phase difference detection method and the focus position detected by the contrast detection method. The focus position detected by the reliability and contrast detection method is weighted according to the reliability, and the focus position is set to the average position of the focus position based on the weighted defocus amount and the focus position detected by the contrast detection method. The lens 32 may be driven.

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

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 (8)

A first detector that detects defocus using a phase difference ;
A second detection unit for detecting a focus evaluation value ;
A first focus position is calculated using the defocus detected by the first detection unit, a second focus position is calculated using the focus evaluation value detected by the second detection unit, and A calculation unit that calculates a third focus position using the first focus position and the second focus position;
And a control unit that performs control to move the focus lens to the third in-focus position calculated by the calculation unit. The focus adjustment device according to claim 1, comprising:
The calculation unit calculates the first in-focus position using the defocus detected by the first detection unit when the focus lens is moving, and when the focus lens is moving A focus adjustment device that calculates the second focus position using the focus evaluation value detected by the second detection unit. The focus adjusting apparatus according to claim 1 or 2,
When the focus position is not calculated by the calculation unit using the defocus detected by the first detection unit, the control unit performs scan control to move the focus lens,
The calculation unit calculates the first in-focus position using the defocus detected by the first detection unit when the scan control is performed by the control unit, and the scan control is performed by the control unit. A focus adjustment device that calculates the second focus position using the focus evaluation value detected by the second detection unit when the second focus is detected. The focus adjustment device according to any one of claims 1 to 3,
The control unit uses the defocus detected by the first detection unit when the scan control is performed by the control unit after moving the focus lens over the entire range of the scan control range. A focus adjustment device that calculates a first in-focus position and calculates the second in-focus position using the focus evaluation value detected by the second detection unit when the scan control is performed by the control unit. . The focus adjustment device according to any one of claims 1 to 4, wherein:
The said calculating part is a focus adjustment apparatus which calculates the average position of a said 1st focusing position and a said 2nd focusing position as a said 3rd focusing position. The focus adjustment device according to any one of claims 1 to 4, wherein:
The calculation unit performs weighting determined using the reliability of detection by the first detection unit and the reliability of detection by the second detection unit on the first focus position and the second focus position. A focus adjustment device that calculates a position based on the weighted first focus position and the second focus position as the third focus position. The focus adjustment device according to any one of claims 1 to 6 ,
An imaging unit having a plurality of imaging pixels and a plurality of focus detection pixels;
The first detection unit detects the defocus based on a signal output from the focus detection pixel,
The second detection unit, based on the signal output from the imaging pixels, detect focus point adjuster the focus evaluation value. An imaging apparatus comprising the focus adjustment apparatus according to any one of claims 1 to 7 .

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