JP5477344B2 - 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.

  Conventionally, when adjusting the focus of the 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 optical system is driven to the vicinity of the in-focus position, and then, in the vicinity of the in-focus position, the focus state of the optical system is detected by the contrast detection method. Based on the detection result by the contrast detection method, the focus adjustment optical system is A technique for driving to the in-focus position is known (for example, see Patent Document 1).

JP 2004-109690 A

  However, since the above-mentioned Patent Document 1 first performs focus detection by the phase difference detection method and subsequently performs focus detection by the contrast detection method, it may take time to adjust the focus of the optical system. It was. On the other hand, a method of simultaneously performing focus detection by the phase difference method and focus detection by the contrast detection method while driving the focus adjustment optical system is also conceivable, but in this case, the drive speed of the focus adjustment optical system is For example, if the speed is suitable for focus detection by the phase difference detection method, the focus adjustment optical system may be driven too fast, and the focus position may not be detected by the contrast detection method.

  The problem to be solved by the present invention is to provide a focus adjustment device capable of appropriately detecting a focus state.

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

[1] A focus adjustment apparatus according to a first aspect of the present invention outputs an image signal corresponding to an image obtained by imaging an image by an optical system (31, 32, 33) having a focus adjustment optical system (32). A first focus detector (222a, 222b) that detects a focus adjustment state of the optical system by a phase difference detection method, and the imaging unit when the focus adjustment optical system is driven to search. By calculating an evaluation value based on the output image signal, a second focus detection unit (221) that detects a focus adjustment state of the optical system by a contrast detection method, and detected by the first focus detection unit. A first focus drive control for controlling the focus adjustment optical system based on the focus adjustment state, and a focus adjustment optical system based on the focus adjustment state detected by the second focus detection unit. Second control to drive control Drive control and first search drive control that calculates the evaluation value by driving the focus adjustment optical system at a first speed that is lower than a predetermined speed that is a maximum speed at which a focus position can be detected by the second focus detection unit. A second search drive control for driving the focus adjustment optical system at a second speed higher than the predetermined speed and calculating the evaluation value; and driving the focus adjustment optical system at a third speed slower than the predetermined speed. third search drive control and is controllable unit (21), before Symbol the evaluation value second Go lens driving control is obtained by the first search drive control before being started to calculate the evaluation value When the second focus detection unit detects the peak of the evaluation value using the first judgment, the evaluation obtained by the second search drive control before the second focus drive control is started The second focus detection unit detects the peak of the evaluation value using the value A determination unit (21) for making a second determination when the control unit starts the third search drive control when the second determination is made by the determination unit, and the determination unit starts the first search When the determination is made, the second focus drive control is started without starting the third search drive control, and the third search drive control is before the second focus drive control is started. The first search drive control is performed after the peak of the evaluation value is detected using the evaluation value obtained in the second search drive control and before the second focus drive control is started. It is not performed after the peak of the evaluation value is detected by using the evaluation value obtained in (1) .

[2] In the invention according to the focusing device, wherein the control unit (21), in a case where the third search drive control is started, when the peak of the previous SL evaluation value is detected, the evaluation value The focus adjustment optical system (32) can be driven to a peak position.

[3] In the invention related to the focus adjustment device, the control unit (21) may perform the control based on the focus adjustment state detected by the second focus detection unit when the third search drive control is started. before second Go lens driving control is started, the first focus detection unit (222a, 222b) when the focus position is detected by, the focusing optical system to the in-focus position (32) It can be configured to be driven.

  [4] In the invention related to the focus adjusting apparatus, the first focus detection unit (222a, 222b) may be provided on a light receiving surface of the imaging unit (22).

[5] In the invention related to the focus adjusting apparatus, the fastest speed among the image plane moving speeds at which the in-focus position can be detected by the second focus detection unit (221) is stored in advance as a focus detectable speed. The control unit (21) can be configured to use the focus detectable speed as the predetermined speed .

  [6] In the invention related to the focus adjustment apparatus, when the control unit (21) cannot detect a focus position by the first focus detection unit (222a, 222b), the second focus detection unit (221). Can be configured to detect the focus state of the optical system.

[7] The focus adjustment apparatus according to the second aspect of the present invention outputs an image signal corresponding to an image obtained by capturing an image by the optical system (31, 32, 33) having the focus adjustment optical system (32). The focus adjustment of the optical system is performed by a contrast detection method by calculating an evaluation value based on the image signal output by the image pickup unit when the unit (22) and the focus adjustment optical system are driven to search. A focus detection unit (221) for detecting a state; a focus drive control for controlling the focus drive of the focus adjustment optical system based on the focus adjustment state detected by the focus detection unit; A first search drive control for calculating the evaluation value by driving the focus adjustment optical system at a first speed slower than a predetermined speed that is a maximum speed at which a focal position can be detected; and a second speed faster than the predetermined speed. The focusing optical The second search drive control for driving the lens and calculating the evaluation value and the third search drive control for calculating the evaluation value by driving the focus adjustment optical system at a third speed slower than the predetermined speed. parts (21), the first when the focus detecting unit before using the evaluation value obtained by the first search drive control before Kigoase drive control is started to detect a peak of the evaluation value Make a determination and use the evaluation value obtained by the second search drive control before the focus drive control is started to make a second determination when the focus detection unit detects the peak of the evaluation value. A determination unit, and the control unit starts the third search drive control when the second determination is made by the determination unit, and the third search when the first determination is made by the determination unit. start the focusing drive control without starting drive control, the third probe The drive control is performed before the focus drive control is started and after the peak of the evaluation value is detected using the evaluation value obtained by the second search drive control, and the focus drive is performed. It is not performed after the peak of the evaluation value is detected using the evaluation value obtained by the first search drive control before the control is started .
[8] An imaging apparatus according to the present invention includes the above-described focus adjustment apparatus.

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

FIG. 1 is a block diagram showing a digital camera 1 according to this embodiment. FIG. 2 is a front view showing a focus detection position on the imaging surface of the imaging device shown in FIG. FIG. 3 is a front view schematically showing the arrangement of the focus detection pixels 222a and 222b by enlarging the III part of FIG. FIG. 4 is a front view schematically showing the arrangement of the focus detection pixels 222a and 222b by enlarging the IV part of FIG. FIG. 5 is an enlarged front view showing one of the imaging pixels 221. 6A is an enlarged front view showing one of the focus detection pixels 222a, and FIG. 6B is an enlarged front view showing one of the focus detection pixels 222b. FIG. 7 is an enlarged cross-sectional view showing one of the imaging pixels 221. 8A is an enlarged cross-sectional view showing one of the focus detection pixels 222a, and FIG. 8B is an enlarged cross-sectional view showing one of the focus detection pixels 222b. FIG. 9 is a spectral characteristic diagram showing the relative sensitivity with respect to the wavelength of each of the three imaging pixels RGB. FIG. 10 is a spectral characteristic diagram showing the relative sensitivity with respect to the wavelength of the focus detection pixel. 11 is a cross-sectional view taken along line XI-XI in FIGS. FIG. 12 is a flowchart illustrating an operation example of the camera according to the present embodiment. FIG. 13 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 first scan operation. FIG. 14 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 second scan operation and the third scan operation.

  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.

In the present embodiment, the lens control unit 37 drives the focus lens 37 at a predetermined lens driving speed in accordance with an instruction from the camera control unit 21, and outputs a driving pulse signal corresponding to the lens driving speed to the focus lens driving motor. 36. The lens control unit 37, a memory (not shown) the lens control unit 37 is provided, which stores the focus detectable maximum velocity V _max of the focusing lens 32 described later.

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

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

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

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

  The operation unit 28 is a shutter release button or an input switch for the photographer to set various operation modes of the camera 1, and switches between the auto focus mode / manual focus mode and the one shot mode / continuous mode even in the auto focus mode. It is possible to switch between the numeric modes. Here, the one-shot mode is a mode in which the position of the focus lens 32 once adjusted is fixed and photographing is performed at the focus lens position, whereas the continuous mode is a mode in which the position of the focus lens 32 is fixed. In this mode, the focus lens position is adjusted according to the subject. 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.

  2 is a front view showing an image pickup surface of the image pickup device 22, FIG. 3 is a front view schematically showing the arrangement of focus detection pixels 222a and 222b by enlarging the portion III in FIG. 2, and FIG. FIG. 4 is a front view schematically showing an arrangement of focus detection pixels 222a and 222b by enlarging the IV part of FIG.

  As shown in FIGS. 3 and 4, the imaging element 22 of the present embodiment includes 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 green pixel G, 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. 5 is an enlarged front view showing one of the imaging pixels 221, and FIG. 7 is a cross-sectional view. One imaging pixel 221 includes a microlens 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 31 by the micro lens 2211 and receives the imaging light beam.

  The color filter of this embodiment is provided between the microlens 2211 and the photoelectric conversion unit 2212. The spectral sensitivities of the color filters of the green pixel G, the red pixel R, and the blue pixel B are shown in FIG. 9, for example. It is said to be as follows. FIG. 9 is a spectral characteristic diagram showing the relative sensitivity with respect to the wavelength of each of the three imaging pixels RGB shown in FIGS. 3 and 4.

  Returning to FIG. 2, focus detection pixel arrays in which focus detection pixels 222 a and 222 b are arranged in place of the above-described imaging pixels 221 at the center of the imaging surface of the imaging element 22 and at five positions vertically and horizontally symmetrical from the center. 22a, 22b, 22c, 22d, and 22e are provided. As shown in FIGS. 3 and 4, one focus detection pixel column includes a plurality of focus detection pixels 222 a and 222 b that are adjacent to each other alternately in a horizontal row (22 a, 22 d, 22 e) or a vertical row ( 22b, 22c). 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 the like, and may be at six or more positions. It can also be arranged. In actual focus detection, the photographer manually operates the operation unit 28 from among a plurality of focus detection pixel rows 22a to 22e, and selects a desired focus detection pixel row as a focus detection position. You can also.

  6A is an enlarged front view showing one of the focus detection pixels 222a, and FIG. 8A is a cross-sectional view of the focus detection pixel 222a. FIG. 6B is an enlarged front view showing one of the focus detection pixels 222b, and FIG. 8B is a cross-sectional view of the focus detection pixel 222b. As shown in FIG. 6A, the focus detection pixel 222a includes a micro lens 2221a and a semicircular photoelectric conversion portion 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. 6B. As shown in a cross-sectional view of FIG. A photoelectric conversion unit 2222b is formed on the surface of the circuit board 2213, and a microlens 2221b is formed on the surface. The focus detection pixels 222a and 222b are alternately arranged adjacent to each other in a horizontal row or a vertical row, as shown in FIGS. 3 and 4, so that the focus detection pixel rows 22a to 22b shown in FIG. 22e is configured.

  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. FIG. 10 shows the spectral characteristics of the focus detection pixels 222a and 222b. The relative sensitivity is such that the sensitivity of the blue pixel B, the green pixel G, and the red pixel R of the imaging pixel 221 shown in FIG. The light wavelength region where the sensitivity appears is a region including the light wavelength regions of the sensitivity of the blue pixel B, the green pixel G, and the red pixel R of the imaging pixel 221 shown in FIG. However, it may be configured to include one of the same color filters as the imaging pixel 221, for example, a green filter. FIG. 10 is a spectral characteristic diagram showing the relative sensitivity with respect to the wavelength of the focus detection pixels shown in FIGS. 3 and 4.

  In addition, although the photoelectric conversion units 2222a and 2222b of the focus detection pixels 222a and 222b illustrated in FIGS. 6A and 6B are semicircular, 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. 11 is a cross-sectional view taken along the line XI-XI in FIGS. 3 and 4, and the focus detection pixels 222a-1, 222b-1, 222a-2, 222b- are arranged in the vicinity of the photographing optical axis L1 and adjacent to each other. 2 indicates that light beams AB1-1, AB2-1, AB1-2, and AB2-2 irradiated from the distance measurement pupils 341 and 342 of the exit pupil 34 are received, respectively. 11 illustrates only the focus detection pixels 222a and 222b that are located in the vicinity of the photographing optical axis L, but other focus detection pixels other than the focus detection pixels illustrated in FIG. In the same manner, the light beams emitted from the pair of distance measuring pupils 341 and 342 are respectively received.

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

  In FIG. 11, 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 341 and 342.

  As shown in FIG. 11, 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 Projected onto the exit pupil 34 separated from the lenses 2221a-1, 2221b-1, 2221a-2, 2221b-2 by the distance measurement distance D, and the projection shape forms the distance measurement pupils 341, 342.

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

  As shown in FIG. 11, the photoelectric conversion unit 2222a-1 of the focus detection pixel 222a-1 is formed on the microlens 2221a-1 by the light beam AB1-1 that passes through the distance measuring pupil 341 and goes to the microlens 2221a-1. A signal corresponding to the intensity of the image to be output is output. Similarly, the photoelectric conversion unit 2222a-2 of the focus detection pixel 222a-2 passes through the distance measuring pupil 341, and the intensity of the image formed on the microlens 2221a-2 by the light beam AB1-2 toward the microlens 2221a-2. The signal corresponding to is output.

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

  Then, a plurality of the above-described two types of focus detection pixels 222a and 222b are arranged in a straight line as shown in FIGS. 3 and 4, and the outputs of the photoelectric conversion units 2222a and 2222b of the focus detection pixels 222a and 222b are measured. By combining the output groups corresponding to the distance pupil 341 and the distance measurement pupil 342, a pair of focus detection light beams that pass through each of the distance measurement pupil 341 and the distance measurement pupil 342 are formed on the focus detection pixel row. Data on the intensity distribution of the image 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 at the detection position, that is, the defocus amount can be obtained.

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

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

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

  Next, an operation example of the camera 1 according to the present embodiment will be described. FIG. 12 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 and the shutter release button provided in the operation unit 28 is half-pressed (the first switch SW1 is turned on). In the following, a continuous mode, that is, a mode in which the focus state of the optical system is continuously detected to shoot at the focus lens position corresponding to the subject without fixing the position of the focus lens 32 is selected. The case will be described as an example.

  In step S1, the camera control unit 21 performs a defocus amount calculation process using a phase difference detection method. In the present embodiment, the defocus amount calculation process by the phase difference detection method is performed as follows. That is, first, the image sensor 22 receives a light beam from the photographing optical system, and the camera control unit 21 configures the focus detection pixels 222a and 222b constituting the five focus detection pixel rows 22a to 22e of the image sensor 22. A pair of image data corresponding to the pair of images is read out. In this case, when a specific focus detection position is selected by a manual operation of the photographer, only data from focus detection pixels corresponding to the focus detection position may be read. Then, the camera control unit 21 executes image shift detection calculation processing (correlation calculation processing) based on the read pair of image data, and images at the focus detection positions corresponding to the five focus detection pixel rows 22a to 22e. 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.

  In step S2, the camera control unit 21 determines whether 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 S3. 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 S7. In the present embodiment, even if the defocus amount can be calculated, if the reliability of the calculated defocus amount is low, it is treated that the defocus amount cannot be calculated, and the process proceeds to step S7. 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 S3, since it is determined that the defocus amount can be calculated by the phase difference detection method and it is determined that distance measurement is possible, the camera control unit 21 performs a focusing operation based on the defocus amount calculated in step S1. Is done.

  That is, in step S3, processing for driving the focus lens 32 to the in-focus position is performed based on the defocus amount calculated by the phase difference detection method. Specifically, the camera control unit 21 calculates and calculates the lens drive 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 focus lens driving motor 36 via the lens control unit 37. The focus lens drive motor 36 drives the focus lens 32 to the in-focus position based on the lens drive amount calculated by the camera control unit 21.

  In the present embodiment, the focus lens drive motor 36 is driven and the focus lens 32 is driven to the in-focus position in step S3, the process proceeds to step S4, and the camera control unit 21 controls the focus lens. It is determined whether or not 32 has been driven to the in-focus position. When the focus lens 32 is not driven to the in-focus position (step S4 = No), the process returns to step S1, and the defocus amount is calculated by the phase difference detection method while the focus lens 32 is driven to the in-focus position. (Step S1). When a new defocus amount is calculated while the focus lens 32 is driven to the in-focus position, the camera control unit 21 drives the focus lens 32 based on the new defocus amount. Let

  On the other hand, when the driving of the focus lens 32 up to the in-focus position is completed (step S4 = Yes), the process proceeds to step S5, the focus lens 32 is terminated, and then the process proceeds to step S6 to display the focus display. Is done. After the in-focus display is performed, the process returns to step S1, and this focus adjustment process is repeated. The in-focus display in step S6 is performed by the electronic viewfinder 26, for example. Further, when performing the focus display, a display for notifying the photographer that the focus operation has been performed by the phase difference detection method may be performed together.

  Thus, in this embodiment, while the defocus amount can be calculated by the phase difference detection method (step S2 = Yes), the focus lens 32 is driven based on the defocus amount calculated by the phase difference detection method. . On the other hand, when it is determined that the defocus amount cannot be calculated by the phase difference detection method, or when it is determined that the reliability of the calculated defocus amount is low (step S2 = No), the process proceeds to step S7. move on.

  In step S7, the camera control unit 21 determines whether a scanning operation is being performed. 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 contrast detection method by the camera control unit 21 while the focus lens 32 is scan-driven by the focus lens drive motor 36. Calculation is performed simultaneously at a predetermined interval, whereby the detection of the in-focus position by the phase difference detection method and the in-focus position detection by the contrast detection method are performed simultaneously in parallel at the predetermined interval. is there.

  Specifically, in the scanning operation, the camera control unit 21 first sends a scan drive start command to the lens control unit 37, and the lens control unit 37 is based on the command from the camera control unit 21. 36 is driven, and the focus lens 32 is scan-driven along the optical axis L1. Note that the scan driving of the focus lens 32 may be performed from the infinite end to the close end, or may be performed from the close end to the infinite end.

  In the scanning operation, 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. Based on this, the defocus amount is calculated and the reliability of the calculated defocus amount is evaluated by the phase difference detection method, and the image pickup pixels 221 of the image pickup device 22 are driven at predetermined intervals while driving the focus lens 32. From this, the pixel output is read out, and based on this, the focus evaluation value is calculated, and thereby the focus evaluation value at different focus lens positions is acquired, and the focus position is detected by the contrast detection method.

  If it is determined in step S7 that the scan operation has not been performed, the process proceeds to step S8 to start the scan operation. On the other hand, if it is determined that the scan operation has been performed, the process proceeds to step S14. move on.

In step S8, the camera control unit 21 sets the scan speed _Vscan . Here, the scan speed V _scan refers to the drive speed of the focus lens 32 in the scan operation. In the present embodiment, the camera control unit 21 sets the scan speed V _scan to a speed suitable for focus detection by the phase difference detection method. Here, examples of the speed suitable for focus detection by the phase difference detection method include the maximum speed among the speeds at which focus detection by the phase difference detection system can be performed.

In this embodiment, the scan speed V _scan is not a speed based on the actual driving speed of the focus lens 32 but a speed based on the moving speed of the image plane (image plane moving speed) when the focus lens 32 is driven. Set as The scan speed V _scan may be set in consideration of the brightness of the subject and the maximum speed at which the focus lens 32 can be driven.

Next, in step S9, the camera control unit 21, the acquisition of focus detectable maximum velocity _{V max} is performed. In the present embodiment, focus detection is possible maximum speed V _max is the maximum speed of which can detect the speed of the focus position by the contrast detection method. Here, as described above, the focus detection by the contrast detection method is to calculate the focus evaluation value at a predetermined sampling interval while driving the focus lens 32 to scan. The sampling interval for the focus evaluation value increases as the driving speed of the focus lens 32 increases. When the driving speed of the focus lens 32 exceeds a predetermined speed, the sampling interval for the focus evaluation value becomes too large. As a result, the in-focus position cannot be detected properly. Focus detectable maximum velocity V _max is the maximum speed that can be detected in focus by contrast detection system position, the scan speed V _scan, to determine whether it is possible to detect the focus by contrast detection method positions This is the standard speed.

In the present embodiment, the maximum focus detectable speed V _max is stored in the memory of the lens control unit 37, and the camera control unit 21 is stored in the memory of the lens control unit 37 from the lens control unit 37. The maximum focus detectable speed V _max can be acquired. Further, in the present embodiment, the focus detectable maximum speed V _max is a speed based on the image plane moving speed, similar to the scan speed V _scan described above, and the camera control unit 21 receives the image plane from the lens control unit 37. A focus-detectable maximum speed V _max based on the moving speed is acquired. Note that when the aperture 34 is reduced, the depth of focus becomes deeper, and the sampling interval of the focus evaluation value at which the in-focus position can be detected may be increased. Therefore, the maximum focus detectable speed V _max corresponding to the aperture 34 is controlled by the lens control. When stored in the memory of the unit 37, the camera control unit 21 can obtain the focus detectable maximum speed V _max corresponding to the diaphragm 34.

Incidentally, the memory of the lens control unit 37, even when the focus detection is possible maximum speed V _max based on the image plane movement velocity is not stored, the focus detectable maximum velocity V _{Max_lns} is stored based on the actual driving speed of the focus lens 32 If it is, the camera control unit 21 can acquire the maximum focus detectable speed V _max based on the image plane moving speed, as will be described below. That is, the camera control unit 21 first obtains the maximum focus detectable speed V _{max — lns} based on the actual drive speed of the focus lens 32 from the lens control unit 37. Then, the camera control unit 21, the focus detectable maximum velocity V _{Max_lns} based on actual driving speed of the focus lens 32 obtained, by converting the focus detectable maximum velocity V _max based on the image plane movement velocity, the image plane A maximum focus detectable speed V _max based on the moving speed can be acquired. Specifically, the camera control unit 21 _sends an image plane movement coefficient (an image plane _associated with the driving of the focus lens 32) from the lens control unit 37 together with a focus detectable maximum speed _{Vmax_lns} based on the actual driving speed of the focus lens 32. Lens information including the moving speed / the actual driving speed of the focus lens 32), and based on the acquired lens information, the focus-detectable maximum speed _{Vmax_lns} based on the actual driving speed of the focus lens 32 is moved to the image plane. by converting the focus detectable maximum velocity V _max based on the speed, it is possible to obtain a focus detectable maximum velocity V _max based on the image plane movement velocity.

In step S10, the camera control unit 21 and the scan speed _{V scan} set in step S8, the comparison of the focus detectable maximum velocity _{V max} obtained in step S9 is performed, scan speed _{V scan} focus detectable maximum velocity V _max speeds below a is a determination is made as to whether. If it is determined that the scan speed V _scan is equal to or lower than the focus detectable maximum speed V _max (scan speed V _scan ≦ maximum focus detectable speed V _max ), the process proceeds to step S11, while the scan speed V _scan is If it is determined that the speed faster than the focus detectable maximum velocity _{V max} (scan speed _{V scan>} focus detectable maximum velocity _{V max),} the process proceeds to step S12.

In step S11, the camera control unit 21 determines that the scanning operation started in step S13 described later is the first scanning operation. Here, the first scan operation is a scan speed V _scan that is equal to or lower than the maximum focus detectable speed V _max , that is, a scan speed V _scan that can detect the in-focus position by the contrast detection method, and scan driving the focus lens 32. The scanning operation is performed.

On the other hand, in step S12, the camera control unit 21 determines that the scan operation started in step S13 described later is the second scan operation. Here, the second scan operation is to perform the scan operation by scanning the focus lens 32 at a scan speed V _scan faster than the maximum focus detectable speed V _max .

In step S13, the camera controller 21 starts a scanning operation. Specifically, the camera control unit 21 first sends the scan speed V _scan to the lens control unit 37 in order to perform a scan operation at the scan speed V _scan set in step S8. Then, the lens control unit 37 generates a drive pulse signal for driving the focus lens 32 based on the scan speed V _scan sent from the camera control unit 21, and uses the generated drive pulse signal as the focus lens drive motor. By transmitting to 36, the focus lens 32 is driven at the scan speed _Vscan . Then, while driving the focus lens 32 at the scan speed V _scan , the calculation of the defocus amount by the phase difference detection method and the calculation of the focus evaluation value by the contrast detection method are simultaneously performed at predetermined intervals, thereby performing a scan operation. Execute.

  In step S14, the camera control unit 21 performs a focus evaluation value calculation process using a contrast detection method. In the present embodiment, the focus evaluation value calculation process reads out the pixel output from the imaging pixel 221 of the image sensor 22, extracts a high-frequency component of the read-out pixel output using a high-frequency transmission filter, and integrates this to extract the focus. This is done by detecting the voltage. The focus evaluation value is calculated only when the specific focus detection position is selected by a manual operation of the photographer or by 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.

  In step S15, it is determined whether or not the peak of the focus evaluation value has been detected by the contrast detection method as a result of the scanning operation performed by the camera control unit 21. When the peak of the focus evaluation value can be detected by the contrast detection method, the process proceeds to step S16. On the other hand, when the peak of the focus evaluation value cannot be detected by the contrast detection method, the process proceeds to step S23.

  If it is determined in step S15 that the peak of the focus evaluation value cannot be detected by the contrast detection method, the process proceeds to step S23, and the camera control unit 21 performs the scanning operation over the entire driveable range of the focus lens 32. A determination is made as to whether it has been broken. When the scan operation is not performed for the entire driveable range of the focus lens 32, the process returns to step S1. After returning to step S1, the defocus amount is calculated again by the phase difference detection method (step S1). If the defocus amount cannot be calculated (step S2 = No), the process proceeds to step S7. In step S7, it is determined that the scanning operation is being performed (step S7 = Yes), the process proceeds to step S14, and the focus evaluation value is calculated again (step S14). Since the peak of the focus evaluation value is detected by the contrast detection method (step S15 = Yes), it is determined again in step S23 whether the scan operation has been performed for the entire driveable range of the focus lens 32. A determination is made.

  As described above, after the scan operation is started, the defocus amount is calculated by the phase difference detection method (step S2 = Yes), the peak of the focus evaluation value is detected (step S15 = Yes), or Until the scan operation is executed for the entire driveable range of the focus lens 32 (step S23 = Yes), the defocus amount is calculated by the phase difference detection method while the focus lens 32 is driven to scan (step S1), and The scan operation is repeated, repeating the calculation of the focus evaluation value by the contrast detection method (step S14). When the defocus amount is calculated by the phase difference detection method as a result of the scanning operation (step S2 = Yes), the process proceeds to step S3, and the above-described focusing operation is performed (steps S3 to S6). On the other hand, when the peak of the focus evaluation value is detected by the contrast detection method as a result of the scanning operation (step S15 = Yes), the process proceeds to step S16.

  In step S <b> 16, the camera control unit 21 determines whether or not the focus drive for driving the focus lens 32 to the focus position detected by the contrast detection method is performed. When the focus drive is performed based on the detection result by the contrast detection method, the process proceeds to step S20. On the other hand, when the focus drive is not performed based on the detection result by the contrast detection method, step S17 is performed. Proceed to

  In step S17, the camera control unit 21 determines whether or not the scan operation being executed is the second scan operation. If it is determined that the scan operation being executed is not the second scan operation, the process proceeds to step S18 in order to perform focusing drive. On the other hand, when it is determined that the scan operation being executed is the second scan operation, the process proceeds to step S19.

If it is determined in step S17 that the scan operation being executed is not the second scan operation, the process proceeds to step S18, and in step S18, focus drive for driving the focus lens 32 to the focus position is started. For example, when the scan operation being executed is the first scan operation (step S17 = No), the focus drive is started toward the focus position detected by the first scan operation. Here, in the first scan operation, since the scan speed V _scan is a speed at which the focus position can be detected by the contrast detection method, the peak of the focus evaluation value detected by the contrast detection method is used as the focus position. It can be judged. Therefore, if the peak of the focus evaluation value is detected as a result of the scan operation (step S15 = Yes) and the scan operation being executed is not the second scan operation (step S17 = No), the scan is performed in step S18. Focus drive for driving the focus lens 32 is started at the peak (focus position) of the focus evaluation value detected by the operation. Note that the drive speed of the focus lens 32 in the focus drive can be the maximum speed among the speeds at which the focus lens 32 can be driven.

  After the in-focus driving is started in step S18, the process returns to step S1, and after defocus amount calculation (step S1) and focus evaluation value calculation (step S14) are performed by the phase difference detection method. Then, the process proceeds again to step S16, and it is determined whether or not the focusing drive is being executed. After the focus drive is started in step S18, it is determined in step S16 that the focus drive is being executed (step S16 = Yes), and the process proceeds to step S20.

  In step S20, the camera control unit 21 determines whether or not the focus lens 32 has been driven to the in-focus position. After starting the focus drive toward the focus position detected by the scanning operation (step S18), the focus lens 32 is driven to the focus position until the drive of the focus lens 32 to the focus position is completed. It is determined that it is not (step S20 = No), and the process returns to step S1. Until the driving of the focus lens 32 to the in-focus position is completed (step S20 = No), the defocus amount is calculated by the phase difference detection method (step S1), and the focus evaluation value is calculated by the contrast detection method (step S1). While repeating step S14), the focus drive is continued toward the focus position. On the other hand, when the driving of the focus lens 32 to the in-focus position is completed (step S20 = Yes), the process proceeds to step S21. In step S20, in addition to the case where the focus lens 32 is driven to the in-focus position, the focus lens 32 is also moved when the focus lens 32 is driven to within the depth of focus corresponding to the in-focus position. It is treated as being driven to the in-focus position, and the process proceeds to step S21.

  In step S21, since the camera control unit 21 has finished driving the focus lens 32 to the in-focus position, a process for ending the focus lens 32 is performed, and then the process proceeds to step S22 to focus. Display is performed. After the in-focus display is performed, the process returns to step S1, and this focus adjustment process is repeated. The focus display in step S22 is performed by the electronic viewfinder 26, for example. Further, when performing in-focus display, a display for notifying the photographer that the in-focus operation has been performed by the contrast detection method may be performed together.

As described above, in this embodiment, it is determined that the scan speed V _scan is equal to or lower than the focus detectable maximum speed V _max (scan speed V _scan ≦ focus detectable maximum speed V _max ) (step S10 = Yes). When it is determined that the scan operation is the first scan operation (step S11), when the peak of the focus evaluation value is detected (step S15 = Yes), the focus evaluation value detected by the first scan operation Is determined as the in-focus position, and in-focus driving for driving the focus lens 32 to the peak position (in-focus position) of the focus evaluation value is performed (step S18).

  Here, the operation of the camera 1 when the above-described first scan operation is executed will be described with reference to FIG. FIG. 13 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 first scan operation. As shown in FIG. 13, at the start of the scanning operation, the focus lens 32 is positioned at P0 shown in FIG. 13, and the focus evaluation is performed while driving the focus lens 32 from P0 from the infinity side to the close side. Get the value. When the focus lens 32 is moved to the position P1 shown in FIG. 13 and the peak position of the focus evaluation value is detected (step S15 = Yes), it is determined whether the scan operation is the second scan operation. (Step S17). Here, in the example shown in FIG. 13, since the scan operation by the first scan operation is executed (step S17 = No), the peak position of the focus evaluation value detected by the first scan operation is determined as the focus position. Then, focus drive (step S18) for driving the focus lens 32 to the focus position (position P2 in FIG. 13) is started.

On the other hand, if it is determined in step S17 that the second scan operation is being performed (step S17 = Yes), the process proceeds to step S19. In step S19, the camera control unit 21 starts the third scan operation. Here, the third scan operation is performed subsequent to the second scan operation, and the scan operation is performed in the vicinity of the peak position of the focus evaluation value detected by the second scan operation. Further, the third scan operation performs the scan operation by driving the focus lens 32 at a scan speed V _scan at which the focus position can be detected by the contrast detection method, similarly to the first scan operation described above. It is. In step S19, the camera control unit 21, the scan speed _{V scan,} from the speed (scanning speed _{V scan>} focus detectable maximum velocity _{V max)} in the second scanning operation, capable of detecting focus by contrast detection method positions The speed is changed to a speed (scan speed V _scan ≦ maximum focus detectable speed V _max ), and the third scan operation is started at the scan speed V _scan capable of detecting the in-focus position by the contrast detection method.

In step S19, after the third scan operation is started, the process returns to step S1. Also in the third scan operation, whether the defocus amount is calculated by the phase difference detection method (step S2 = Yes), whether the peak of the focus evaluation value is detected (step S15 = Yes), or the focus lens 32 Until the third scan operation is performed for the entire drivable range (step S23 = Yes), the focus lens 32 is scan-driven at the scan speed V _scan at which the focus position can be detected by the contrast detection method. A third scan operation that repeats the calculation of the defocus amount by the phase difference detection method (step S1) and the detection of the in-focus position by the contrast detection method (step S14) is executed. When the focus evaluation value peak is detected by the third scan operation (step S15 = Yes), the camera control unit 21 determines that the focus evaluation value peak detected by the third scan operation is the in-focus position. Then, the process proceeds to step S16.

  Immediately after the peak of the focus evaluation value is detected by the third scan operation, since the focus drive has not been started (step S16 = No), the process proceeds to step 17. In step S17, since the third scan operation is being performed, it is determined that the scan operation being performed is not the second scan operation (step S17 = No), and the focus evaluation performed in the third scan operation is performed. Focusing drive is started toward the peak position (focus position) of the value (step S18).

  After focusing drive is started toward the peak position of the focus evaluation value detected in the third scan operation, the process returns to step S1, the calculation of the defocus amount by the phase difference detection method (step S1), and the focus evaluation value. After the calculation (step S14) is performed, the process proceeds to step S16 again to determine whether or not the focusing drive is being performed. After the in-focus driving is started, it is determined that the in-focus driving is being performed (step S16 = Yes), and it is determined whether or not the focus lens 32 has been driven to the in-focus position (step S20). . Until the driving to the in-focus position detected in the third scan operation is completed, it is determined that the focus lens 32 has not been driven to the in-focus position (step S20 = No), and the process returns to step S1 to detect the phase difference. The focus drive continues toward the focus position detected in the third scan operation while repeating the calculation of the defocus amount by the method (step S1) and the calculation of the focus evaluation value by the contrast detection method (step S20). Is done. Then, when the driving of the focus lens 32 to the in-focus position is completed (step S20 = Yes), the focus lens 32 is driven in-focus (step S21), and the focus display is performed (step S22).

Thus, in this embodiment, it is determined that the scan speed V _scan is faster than the maximum focus detectable speed V _max (scan speed V _scan > maximum focus detectable speed V _max ) (step S10 = No). ) When it is determined that the scan operation is the second scan operation (step S12), if the peak of the focus evaluation value is detected (step S15 = Yes), the scan speed V _scan can be detected by the focus. maximum velocity V _max speeds below, i.e., is changed to a speed capable of detecting focus by the contrast detection method position, the third scanning operation is started (step S19). When the peak of the focus evaluation value is detected by the third scan operation (step S15 = Yes), the peak position of the focus evaluation value detected by the third scan operation is determined as the focus position, and the focus lens 32 Is driven to the peak position (focus position) of the focus evaluation value.

  Here, with reference to FIG. 14, the operation of the camera 1 when the above-described second scan operation and the subsequent third scan operation are executed will be described. FIG. 14 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 second scan operation and the third scan operation. As shown in FIG. 14, at the start of the scanning operation, the focus lens 32 is positioned at P0 shown in FIG. 14, and the focus evaluation is performed while driving the focus lens 32 from P0 toward the near side from P0. Get the value. When the focus lens 32 is moved to the position P1 shown in FIG. 14 and the peak position of the focus evaluation value is detected (step S15 = Yes), it is determined whether the scan operation is the second scan operation. (Step S17). Here, in the example shown in FIG. 14, since the second scan operation is executed (step S17 = Yes), as shown in FIG. 14, the scan operation by the third scan operation is performed following the second scan operation. It starts (step S19). Then, as shown in FIG. 14, when the third scan operation is executed and the peak of the focus evaluation value is detected by the third scan operation (step S15 = Yes), the scan operation by the third scan operation is detected. The peak position of the focus evaluation value thus determined is determined as the focus position, and focus drive is started up to the focus position (position P2 in FIG. 14) detected by the third scan operation (step S18).

  If the scan operation is performed in the entire driveable range of the focus lens 32, it is determined in step S23 that the scan operation has been completed for the entire driveable range of the focus lens 32, and the step Proceed to S24. In step S24, 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. Therefore, the scanning operation end processing is performed, and then in step S25. Advancing and in-focus indication is performed. Then, after the in-focus indication is performed, the process returns to step S1, and this focus adjustment process is repeated. Note that the in-focus inability display in step S25 is performed by the electronic viewfinder 26, for example.

  As described above, in the present embodiment, first, the defocus amount is calculated by the phase difference detection method, and when the defocus amount can be calculated, the focus lens 32 is based on the calculated defocus amount. Is driven to the in-focus position and the defocus amount cannot be calculated, the defocus amount is calculated by the phase difference detection method and the in-focus position is detected by the contrast detection method while the focus lens 32 is driven to scan. Perform the scan operation to be performed. As a result of executing the scanning operation, the focus lens 32 is moved using the focus detection result by the detection method in which the defocus amount can be calculated or the focus position can be detected among the phase difference detection method and the contrast detection method. Processing to drive to the in-focus position is performed. Therefore, according to the present embodiment, 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 executed, and the focus adjustment of the photographing optical system is performed by the method that can detect the focus. Compared with the conventional technique (that is, a technique in which the focus lens 32 is first driven to the vicinity of the focus position by the phase difference detection method, and then the focus position is detected by the contrast detection method near the focus position). Thus, the focus adjustment of the photographing optical system can be performed in a short time.

Further, according to the present embodiment, as a result of comparing the scan speed V _scan and the focus detectable maximum speed V _max , the scan speed V _scan is equal to or lower than the focus detectable maximum speed V _max (scan speed V _scan ≦ focus detectable maximum). Speed V _max ) (that is, when the scanning operation is the first scanning operation), the peak of the focus evaluation value is determined as the in-focus position, and in-focus driving is performed. As described above, in this embodiment, when the scan speed V _scan is a speed at which the focus position can be detected by the contrast detection method, the peak of the focus evaluation value detected by the contrast detection method is directly used as the focus position. Therefore, since the focusing drive is performed, the time required for focus adjustment can be shortened.

Furthermore, according to the present embodiment, as a result of the comparison between the scan speed V _scan and the focus detectable maximum speed V _max , the scan speed V _scan is faster than the focus detectable maximum speed V _max (scan speed V _scan > focus). If a detectable maximum velocity V _max) (i.e., when the scan operation is the second scanning operation), after the detection of the peak of the focus evaluation value by the second scanning operation, following the second scanning operation, the contrast A third scan operation is performed in which the scan operation is performed at a scan speed _Vscan that enables detection of the in-focus position by the detection method. Then, when the peak of the focus evaluation value is detected by the third scan operation, the peak position of the focus evaluation value detected by the third scan operation is determined as the focus position, and the focus drive is performed. Thus, in the present embodiment, after detecting the peak of the focus evaluation value at a faster second scanning operation of the scan velocity V _scan, scan driven with possible scan speed V _scan detection of focus by contrast detection method positions Since the third scan operation is performed, it is possible to appropriately detect the in-focus position while reducing the time required for focus adjustment.

  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 scan operation started by comparing the scan speed V _scan set in step S8 with the focus detectable maximum speed V _max is the first scan operation, or Whether the second scanning operation is performed or not is determined. For example, after the scanning operation is started (step S13), the scanning speed in the scanning operation is measured, and the measured scanning speed and the maximum focus detectable speed V _max are determined. By comparing these, it may be configured to determine whether the scan operation is the first scan operation or the second scan operation.

  In the above-described embodiment, the defocus amount is calculated by the phase difference detection method even when the peak (focus position) of the focus evaluation value is detected by the contrast detection method in the scan operation, and the defocus is calculated. When the amount can be calculated, the focus drive is performed toward the focus position detected by the phase difference detection method. However, the configuration is not particularly limited, and the contrast detection method is used. Configuration that prohibits calculation of defocus amount by phase difference detection method or focus drive to focus position detected by phase difference detection method when focus evaluation value peak (focus position) is detected by It is good.

  Further, in the above-described embodiment, as shown in FIGS. 13 and 14, when the focus position is detected by the contrast detection method, the focus lens 32 is directly driven to the focus position. In order to reduce backlash, the focus lens 32 may be once driven to a position beyond the in-focus position, and then the focus lens 32 may be returned to the in-focus position.

  In the above-described embodiment, in order to perform focus detection by the phase difference detection method simultaneously with focus detection by the contrast detection method, the image sensor 22 includes the focus detection pixels 222a and 222b. For example, using a transflective pellicle mirror, the light beam from the optical system is branched, and a part of the light beam is guided to a phase difference detection module (not shown) to detect the focus by the contrast detection method. At the same time, focus detection by the phase difference focus detection method can be performed.

  In addition, in the above-described embodiment, the description has been given by exemplifying the camera 1 that can simultaneously perform the detection of the focus state by the phase difference detection method and the detection of the focus state by the contrast detection method as the scan operation. For example, instead of detecting the focus state by the phase difference detection method, the focus state detection by the active AF method or the focus state detection by the external light passive AF method and the contrast detection are performed. It may be configured to simultaneously detect the focus state by the method.

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

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

Claims (8)

An imaging unit that outputs an image signal corresponding to an image obtained by imaging an image by an optical system having a focus adjustment optical system;
A first focus detector for detecting a focus adjustment state of the optical system by a phase difference detection method;
Secondly, a focus adjustment state of the optical system is detected by a contrast detection method by calculating an evaluation value based on the image signal output by the imaging unit when the focus adjustment optical system is driven to search. A focus detector;
Based on the first focus drive control for controlling the focus adjustment optical system based on the focus adjustment state detected by the first focus detection unit and the focus adjustment state detected by the second focus detection unit. The focus adjustment is performed at a first speed slower than a predetermined speed that is a maximum speed at which a focus position can be detected by the second focus detection unit. A first search drive control for driving the optical system to calculate the evaluation value; a second search drive control for driving the focus adjustment optical system at a second speed higher than the predetermined speed to calculate the evaluation value; A control unit capable of performing a third search drive control for driving the focus adjustment optical system at a third speed slower than a predetermined speed and calculating the evaluation value ;
A first determination when the second focus detection unit detects the peak of the evaluation value using the evaluation value obtained by the first search drive control before the previous SL second Go lens driving control is started When the second focus detection unit detects the peak of the evaluation value using the evaluation value obtained by the second search drive control before the second focusing drive control is started, a second determination is made. And a determination unit for
The control unit starts the third search drive control when the second determination is made by the determination unit, and does not start the third search drive control when the first determination is made by the determination unit. Starting the second focusing drive control ;
The third search drive control is performed before the second focus drive control is started and after a peak of the evaluation value is detected using the evaluation value obtained by the second search drive control. The second focus drive control is not started and after the peak of the evaluation value is detected using the evaluation value obtained by the first search drive control. Focusing device. The focus adjustment apparatus according to claim 1,
When the third search drive control is started and the peak of the evaluation value is detected, the control unit drives the focus adjustment optical system to a position where the evaluation value reaches a peak. Focus adjustment device characterized. The focusing apparatus according to claim 1 or 2,
When the third search drive control is started, the control unit performs the second focusing drive control before starting the second focus drive control based on the focus adjustment state detected by the second focus detection unit. A focus adjustment device that drives the focus adjustment optical system to the focus position when the focus position is detected by a single focus detection unit. In the focus adjustment apparatus according to any one of claims 1 to 3,
The focus adjustment apparatus, wherein the first focus detection unit is provided on a light receiving surface of the imaging unit. In the focus adjustment apparatus according to any one of claims 1 to 4,
Among the image plane moving speeds at which the in-focus position can be detected by the second focus detection unit, the storage unit further stores in advance the fastest speed as a focus detectable speed,
The control unit uses the focus detectable speed as the predetermined speed. In the focus adjustment apparatus in any one of Claims 1-5,
The control unit causes the second focus detection unit to detect a focus state of the optical system when an in-focus position cannot be detected by the first focus detection unit. An imaging unit that outputs an image signal corresponding to an image obtained by imaging an image by an optical system having a focus adjustment optical system;
Focus detection for detecting a focus adjustment state of the optical system by a contrast detection method by calculating an evaluation value based on the image signal output by the imaging unit when the focus adjustment optical system is driven to search And
Focus drive control for controlling the focus drive of the focus adjustment optical system based on the focus adjustment state detected by the focus detector, and a predetermined speed that is the maximum speed at which the focus position can be detected by the focus detector A first search drive control for driving the focus adjustment optical system at a slower first speed to calculate the evaluation value; and driving the focus adjustment optical system at a second speed higher than the predetermined speed to obtain the evaluation value. A control unit capable of performing second search drive control to calculate and third search drive control to drive the focus adjustment optical system at a third speed slower than the predetermined speed and calculate the evaluation value ;
A first determination when the focus detection unit detects the peak of the evaluation value using the evaluation value obtained by the first search drive control before the previous Kigoase drive control is started, the alloy A determination unit configured to make a second determination when the focus detection unit detects a peak of the evaluation value using the evaluation value obtained by the second search drive control before the focus drive control is started. ,
The control unit starts the third search drive control when the second determination is made by the determination unit, and does not start the third search drive control when the first determination is made by the determination unit. Start the focus drive control ,
The third search drive control is performed before the focus drive control is started and after the peak of the evaluation value is detected using the evaluation value obtained by the second search drive control, The focus adjustment device is not performed after the peak of the evaluation value is detected using the evaluation value obtained by the first search drive control before the focus drive control is started. . An imaging apparatus comprising the focus adjustment apparatus according to claim 1.

Images