JP6642531B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging device.

  2. Description of the Related Art Conventionally, there has been known an imaging apparatus that performs focus adjustment of an optical system while performing wobbling drive for finely reciprocating a focus adjustment optical system along an optical axis direction (for example, see Patent Document 1).

JP 2007-109690 A

  However, in the related art, the wobbling drive is performed more than necessary, and there are problems such as inferior usability and high power consumption.

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

[1] An imaging apparatus according to the present invention includes an imaging unit that captures an image by an optical system having a focusing optical system and outputs a signal, and an image generated by the optical system based on a signal output from the imaging unit. A detecting unit that detects a shift amount between a focus position at which the imaging unit is focused and a position of the focus adjustment optical system, and a change value of a magnification of the optical system when the focus adjustment optical system is moved. When less than a predetermined value, the position of the focus adjustment optical system is reciprocated minutely in the optical axis direction, and when the deviation is detected by the detection unit during the minute reciprocation of the focus adjustment optical system, A control unit that controls the position of the focus adjustment optical system based on the amount of displacement.
[2] In the imaging device according to the aspect of the invention, the detection unit may detect the focus position based on a contrast of an image based on a signal output from the imaging unit, and the control unit may control the optical axis direction. When the focus state of the optical system changes during the minute reciprocating movement in which the position of the focus adjustment optical system is minutely reciprocated and the amount of deviation cannot be calculated, the minute reciprocating movement is stopped and the focus is adjusted. It may be configured to move an adjusting optical system to control the position of the focus adjusting optical system to the detected focus position.
[3] In the imaging device according to the aspect of the invention, the control unit may change the defocus amount by more than a predetermined value or the focus evaluation value by more than a predetermined value during the minute reciprocating movement, and When the calculation cannot be performed, the focus adjustment optical system may be moved in one direction of the optical axis.
[4] In the imaging apparatus according to the aspect of the invention, the controller may be configured to detect the shift amount when the detector detects the shift amount while moving the focus adjustment optical system in one direction of an optical axis. May be configured to control the position of the focusing optical system based on
[5] In the imaging device according to the aspect of the invention, the control unit may be configured to detect the focus position by the detection unit while moving the focus adjustment optical system in one direction of an optical axis. It can be configured to control the position of the focus adjustment optical system to a focus position.
[6] In the imaging device of the present invention, the control unit does not detect the shift amount and the in-focus position by the detection unit while moving the focus adjustment optical system in one direction of an optical axis. And controlling the position of the focusing optical system to a predetermined position.
The imaging apparatus [7] The present invention, the control unit, after moving the focusing optical system to the focus position, the optical system when from the focus position is moved the focusing optical system If the variation value of the magnification is less than a predetermined value, the position of the focus adjustment optical system can be slightly reciprocated in the optical axis direction.
[8] In the imaging apparatus according to the aspect of the invention, when the variation value of the magnification of the optical system when the focus adjustment optical system is moved is equal to or more than a predetermined value when the focus adjustment optical system is moved, the control unit may adjust the focus adjustment optical system in the optical axis direction. When the position of the optical system changes to a standby state without being slightly reciprocated , and the focus state of the optical system changes and the shift amount is detected by the detection unit , the position of the focus adjustment optical system is changed based on the shift amount. It can be configured to control.

FIG. 1 is a block diagram illustrating 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 a portion III in FIG. FIG. 4 is a front view showing one of the imaging pixels 221 in an enlarged manner. 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 a cross-sectional view showing one of the imaging pixels 221 in an enlarged manner. FIG. 7A is an enlarged cross-sectional view of one of the focus detection pixels 222a, and FIG. 7B is an enlarged cross-sectional view of one of the focus detection pixels 222b. FIG. 8 is a sectional view taken along the line VIII-VIII in FIG. FIG. 9 is a flowchart showing an operation when the AF-F mode is selected. FIG. 10 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 when the AF-F mode is selected. FIG. 11 is a diagram illustrating the relationship between the focus lens position and time during wobbling drive. FIG. 12 is a diagram illustrating an example of a driving mode of the focus lens during wobbling driving. FIG. 13 is a flowchart showing an operation when the AF-S mode or the AF-A mode is selected. 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 when the AF-S mode is selected. FIG. 15 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 when the AF-A mode is selected.

  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 (hereinafter, simply referred to as a camera 1) of the present embodiment includes a camera body 2 and a lens barrel 3. The camera body 2 and the lens barrel 3 are detachably connected by a mount unit 4. I have.

  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 has a built-in photographing optical system including lenses 31, 32, 33, and an aperture 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 movably along the optical axis L1 of the lens barrel 3, and its position is adjusted by a focus lens drive motor 36 while its position is detected by an encoder 35.

  The specific configuration of the moving mechanism of the focus lens 32 along the optical axis L1 is not particularly limited. As an example, a rotatable 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 rotatable cylinder, and the focus lens 32 is fixed. The end of the lens frame is fitted into the helicoid groove. Then, by rotating the rotary cylinder by the focus lens drive motor 36, the focus lens 32 fixed to the lens frame moves straight along the optical axis L1.

  By rotating the rotary barrel with respect to the lens barrel 3 as described above, the focus lens 32 fixed to the lens frame moves straight in the direction of the optical axis L1, but the focus lens drive motor 36 as a drive source is driven by the lens. It is provided on the lens barrel 3. The focus lens drive motor 36 and the rotary cylinder are connected by a transmission composed of, for example, a plurality of gears. Then, when the rotary cylinder rotates in one direction, the focus lens 32 fixed to the lens frame moves straight in any direction of the optical axis L1. When the drive shaft of the focus lens drive motor 36 is driven to rotate in the reverse direction, a plurality of gears forming the transmission also rotate in the reverse direction, and the focus lens 32 moves straight in the direction opposite to 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 direction of the optical axis L1 is correlated with the rotation angle of the rotary barrel, and thus can be obtained by detecting the relative rotation angle of the rotary barrel with respect to the lens barrel 3, for example.

  As the encoder 35 of the present embodiment, an encoder that detects the rotation of a rotating disk connected to the rotation drive of the rotating cylinder with an optical sensor such as a photo interrupter and outputs a pulse signal in accordance with the number of rotations, or a fixed cylinder And a brush contact provided on the other surface of the flexible printed circuit board provided on one of the rotating cylinders and the encoder contact on the other surface thereof, and the amount of movement of the rotating cylinder (in either the rotating direction or the optical axis direction). Good) may be used which detects a change in the contact position according to the detection circuit with a detection circuit.

  The focus lens 32 can move in the direction of the optical axis L1 from the end on the camera body side (also called the closest end) to the end on the subject side (also called the infinite end) by the rotation of the rotary 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 described later via the lens control unit 37, and the focus lens drive motor 36 calculates the focus calculated based on this information. The drive position of the lens 32 is driven by being transmitted from the camera control unit 21 via the lens control unit 37.

  The aperture 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 reaching the image sensor 22 through the above-described imaging optical system and to adjust the amount of blur. The adjustment of the aperture diameter by the diaphragm 34 is performed, for example, by transmitting an appropriate aperture diameter calculated in the automatic exposure mode from the camera control unit 21 via the lens control unit 37. The set aperture diameter is input from the camera control unit 21 to the lens control unit 37 by manual operation of the operation unit 28 provided in the camera body 2. The aperture diameter of the aperture 34 is detected by an aperture sensor (not shown), and the lens controller 37 recognizes the current aperture diameter.

  The lens memory 38 is a memory that stores various types of lens information such as information on the shooting distance of the lens barrel 3 and the driving speed of the focus lens 32. Further, the lens memory 38 stores a magnification change table indicating a relationship between a focal length and a photographing distance of the photographing optical system, and a magnification change of the image by the photographing optical system with respect to a unit movement amount of the focus lens 32 in the optical axis L1 direction. are doing.

  The lens control unit 37 is electrically connected to the camera control unit 21 by an electric signal contact unit 41 provided on the mount unit 4, and based on a command from the camera control unit 21, drives the focus lens 32 and controls the focus 34. Adjustment of the aperture diameter and the like are performed, and lens information such as the position of the focus lens 32 and the aperture diameter of the diaphragm 34 are transmitted to the camera control unit 21. Further, the lens control unit 37 refers to the magnification change table stored in the lens memory 38, and compares the image by the photographing optical system with respect to the unit movement amount of the focus lens 32 in the optical axis L1 direction at the current position of the focus lens 32. Is transmitted to the camera control unit 21.

  On the other hand, the camera body 2 is provided with an image pickup device 22 for receiving the light beam L1 from the photographing optical system on a planned focal plane of the photographing optical system, and a shutter 23 on the front surface thereof. The imaging element 22 is configured by a device such as a CCD or a CMOS, converts a received light signal into an electric signal, and sends the electric signal to the camera control unit 21. The captured image information transmitted to the camera control unit 21 is sequentially transmitted to the liquid crystal drive circuit 25 and displayed on an electronic viewfinder (EVF) 26 of the observation optical system, and a release button ( When (not shown) is fully pressed, the captured image information is recorded in the camera memory 24 which is a recording medium. As the camera memory 24, any of a removable card type memory and a built-in type memory can be used. Details of the structure of the imaging element 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 according to the present embodiment includes an electronic viewfinder (EVF) 26 including a liquid crystal display element, a liquid crystal drive circuit 25 that drives the electronic viewfinder (EVF), and an eyepiece 27. The liquid crystal drive circuit 25 reads the captured image information captured by the image sensor 22 and transmitted to the camera control unit 21, and drives the electronic viewfinder 26 based on the information. Thereby, the user can observe the current captured image through the eyepiece 27. In addition, instead of or in addition to the above-mentioned observation optical system using the optical axis L2, a liquid crystal display may be provided on the back of the camera body 2 or the like, and a captured image may be displayed on the liquid crystal display.

  The camera body 2 is provided with a camera control unit 21. The camera control unit 21 is electrically connected to the lens control unit 37 by an electric signal contact unit 41 provided on the mount unit 4, receives lens information from the lens control unit 37, and defocuses the lens control unit 37. Information such as the amount and aperture diameter is transmitted. In addition, 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 drive circuit 25 and the camera memory 24 of the electronic viewfinder 26. The camera control unit 21 also controls the entire camera 1 such as correcting image information from the image sensor 22 and detecting a focus adjustment state and an aperture adjustment state of the lens barrel 3.

  Further, in addition to the above, the camera control unit 21 detects the focus state of the imaging optical system by the phase detection method and the focus state of the imaging 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 the photographer to set various operation modes of the camera 1 such as a shutter release button and a moving image shooting start button, and switches between an auto focus mode / manual focus mode and an auto focus mode. Above all, switching between AF-S mode / AF-A mode / AF-F mode can be performed. The various modes set by the operation unit 28 are transmitted 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.

  Here, the AF-S mode means that after the shutter release button is half-pressed, the focus lens 32 is driven to perform focusing driving based on the focus detection result, and the position of the focus lens 32 once adjusted is adjusted. In this mode, the image is fixed and the image is taken at the focus lens position. Note that the AF-S mode is a mode suitable for still image shooting, and is usually selected when still image shooting is performed. In the AF-A mode, after the shutter release button is half-pressed, focusing driving is performed by driving the focus lens 32 based on the focus detection result, and thereafter, the shutter release button is half-pressed. In this mode, the focus state is repeatedly detected while the focus state is changed, and when the focus state is changed, scan driving of the focus lens 32 is performed. The AF-A mode is a mode suitable for shooting a still image, and is usually selected when shooting a still image. Further, in the AF-F mode, the focusing drive is performed by driving the focus lens 32 based on the focus detection result irrespective of the presence or absence of the operation of the shutter release button. If the state has changed, this is a mode in which scan driving of the focus lens 32 is performed. The AF-F mode is a mode suitable for shooting a moving image, and is usually selected when shooting a moving image.

  Further, in the present embodiment, a configuration may be employed in which a switch for switching between one-shot mode and continuous mode is provided as a switch for switching between auto focus modes. In this case, when the one-shot mode is selected by the photographer, the AF-S mode is set. When the continuous mode is selected by the photographer, the photographing mode is set to the still mode. When the image capturing mode is set, the AF-A mode is set. When the image capturing mode is the moving image capturing mode, the AF-F mode is set.

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

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

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

  The arrangement of the unit pixel groups 223 may be, for example, a dense hexagonal lattice arrangement other than the illustrated dense square lattice. 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 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 microlens 2211, a photoelectric conversion unit 2212, and a color filter (not shown). As shown in the cross-sectional view of FIG. 2212 are formed, and a micro lens 2211 is formed on the surface thereof. The photoelectric conversion unit 2212 is shaped so as to receive the imaging light flux passing through the exit pupil (for example, F1.0) of the imaging optical system 31 by the micro lens 2211, and receives the imaging light flux.

  Further, on the imaging surface of the imaging element 22, instead of the imaging pixel 221, focus detection pixel rows 22a to 22e in which focus detection pixels 222a and 222b are arranged are provided. As shown in FIG. 3, one focus detection pixel row is configured such that a plurality of focus detection pixels 222 a and 222 b are alternately arranged adjacent to each other in a horizontal row. In the present embodiment, the focus detection pixels 222a and 222b are densely arranged without providing a gap at the positions of the green pixel G and the blue pixel B of the imaging pixels 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, but may be any one, two, three, or four places, and six or more places. It can also be arranged at the position. FIG. 3 shows an example in which a focus detection pixel row is formed by 16 focus detection pixels 222a and 222b, but the number of focus detection pixels forming a focus detection pixel row is not limited to this example. It is not something to be done.

  FIG. 5A is an enlarged front view showing one of the focus detection pixels 222a, and FIG. 7A is a cross-sectional view of the focus detection pixel 222a. FIG. 5B is an enlarged front view showing one of the focus detection pixels 222b, and FIG. 7B is a cross-sectional view of the focus detection pixel 222b. As shown in FIG. 5A, the focus detection pixel 222a includes a microlens 2221a and a semi-circular photoelectric conversion unit 2222a. As shown in the cross-sectional view of FIG. The photoelectric conversion unit 2222a is formed on the surface of the semiconductor circuit board 2213, and the microlens 2221a is formed on the surface. Further, the focus detection pixel 222b includes a microlens 2221b and a photoelectric conversion unit 2222b as shown in FIG. 5B, and as shown in a cross-sectional view of FIG. A photoelectric conversion unit 2222b is formed on a surface of the circuit board 2213, and a micro lens 2221b is formed on the surface. Then, as shown in FIG. 3, the focus detection pixels 222a and 222b are arranged adjacent to each other and alternately in a horizontal line, thereby forming the focus detection pixel columns 22a to 22e shown in FIG.

  The photoelectric conversion units 2222a and 2222b of the focus detection pixels 222a and 222b have a shape such that the microlenses 2221a and 2221b receive a light beam that passes through a predetermined area (for example, F2.8) of the exit pupil of the imaging optical system. Is done. Further, the focus detection pixels 222a and 222b are not provided with a color filter, and their spectral characteristics are obtained by integrating 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.

  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.

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

  FIG. 8 is a cross-sectional view taken along the line VIII-VIII in FIG. 3. Focus detection pixels 222 a-1, 222 b-1, 222 a-2, and 222 b-2 arranged near the imaging optical axis L 1 and adjacent to each other This shows that the light beams AB1-1, AB2-1, AB1-2, and AB2-2 emitted from the distance measurement pupils 341 and 342 of the exit pupil 34 are received, respectively. Note that FIG. 8 illustrates only one of the plurality of focus detection pixels 222a and 222b located in the vicinity of the imaging optical axis L1, but other focus detection pixels other than the focus detection pixels illustrated in FIG. Similarly, is configured to receive light beams emitted from the pair of distance measurement pupils 341 and 342, respectively.

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

  In FIG. 8, the arrangement direction of the focus detection pixels 222 a-1, 222 b-1, 222 a-2, and 222 b-2 matches the arrangement direction of the pair of ranging pupils 341 and 342.

  As shown in FIG. 8, the microlenses 2221a-1, 2221b-1, 2221a-2, and 2221b-2 of the focus detection pixels 222a-1, 222b-1, 222a-2, and 222b-2 are provided by an imaging optical system. Are arranged in the vicinity of the predetermined focal plane. The shape of each of the photoelectric conversion units 2222a-1, 2222b-1, 2222a-2, 2222b-2 disposed behind the microlenses 2221a-1, 2221b-1, 1221a-2, 2221b-2 has the shape of each microlens. The light is projected onto the exit pupil 34 at a distance D from the lenses 2221 a-1, 2221 b-1, 2221 a-2, and 2221 b-2, and the projected shape forms the distance measurement pupils 341 and 342.

  That is, on the exit pupil 34 at the distance measurement distance D, the microlens and the photoelectric conversion unit in each focus detection pixel are set so that the projection shapes (ranging pupils 341 and 342) of the photoelectric conversion units of each focus detection pixel match. Are determined, and the projection direction of the photoelectric conversion unit in each focus detection pixel is 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 passing through the distance measurement pupil 341 and traveling 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 ranging pupil 341 and the intensity of the image formed on the microlens 2221a-2 by the light beam AB1-2 directed to the microlens 2221a-2. Output a signal corresponding to.

  Further, the photoelectric conversion unit 2222b-1 of the focus detection pixel 222b-1 passes through the distance measurement pupil 342 and reduces the intensity of an image formed on the microlens 2221b-1 by the light beam AB2-1 directed to the microlens 2221b-1. Outputs the corresponding signal. Similarly, the photoelectric conversion unit 2222b-2 of the focus detection pixel 222b-2 passes through the distance measurement pupil 342, and the intensity of an image formed on the microlens 2221b-2 by the light flux AB2-2 directed to the microlens 2221b-2. Output a signal corresponding to.

  Then, a plurality of the two types of focus detection pixels 222a and 222b described above are linearly arranged as shown in FIG. 3, and the outputs of the photoelectric conversion units 2222a and 2222b of each focus detection pixel 222a and 222b are output to the ranging pupil 341. And the focus detection pupil 342, the focus detection light flux passing through each of the focus pupil 341 and the focus pupil 342 forms the intensity of a pair of images formed on the focus detection pixel row. Data on the distribution is obtained. Then, by subjecting the intensity distribution data to image shift detection calculation processing such as correlation calculation processing or phase difference detection processing, it is possible to detect an image shift amount by a so-called phase difference detection method.

  Then, the obtained image shift amount is subjected to a conversion operation in accordance with the distance between the centers of gravity of the pair of ranging pupils, so that the current focal plane with respect to the planned focal plane (focus 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 on the image shift amount are performed by the camera control unit 21.

  Further, the camera control unit 21 reads out the output of the image pickup pixel 221 of the image pickup device 22 and calculates a focus evaluation value based on the read out pixel output. The 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, integrating the extracted components, and detecting a focus voltage. Alternatively, it can be obtained by extracting a high-frequency component using two high-frequency transmission filters having different cutoff frequencies, integrating them, and detecting a 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), obtains a focus evaluation value at each position, and determines that the focus evaluation value is maximum. Then, focus detection is performed by a contrast detection method in which the position of the focus lens 32 is determined as the focus position. Note that, when the focus evaluation value is calculated while driving the focus lens 32, for example, when the focus evaluation value rises twice and then further falls two times, the in-focus position is changed. Can be obtained by performing an operation such as an interpolation method using the focus evaluation value.

  Here, FIG. 2 shows the first area and the second area in the photographing screen in correspondence with the image sensor 22 (the area surrounded by the dashed line shown in FIG. One area, and an outer area located around the first area is a second area). The first area in the photographing screen corresponds to an area including the focus detection pixel rows 22a to 22e of the image sensor 22, and the focus state of the optical system can be changed by the phase difference detection method and the contrast detection method. This is an area that can be detected. In addition, the second region in the photographing screen is a region that is located around the first region in the photographing screen and does not include the focus detection pixel columns 22a to 22e of the image sensor 22, as shown in FIG. This is an area where the focus state of the optical system can be detected only by the contrast detection method. Therefore, in the present embodiment, as shown in FIG. 2, when the focus detection area AFP for performing focus detection exists in the first area in the shooting screen, as shown in FIG. The focus state can be detected by the method and the contrast detection method. On the other hand, when the focus detection area AFP exists in the second area of the shooting screen, the focus state can be detected by the contrast detection method. .

  Next, an operation example of the camera 1 according to the present embodiment will be described. First, in the present embodiment, an operation example when the AF-F mode, which is a mode suitable for capturing a moving image, is selected will be described. FIG. 9 is a flowchart showing an operation when the AF-F mode is selected. Note that the AF-F mode is usually a mode selected when shooting a moving image, and therefore, a case where the AF-F mode is selected at the time of shooting a moving image will be specifically described below. The following operation is started when, for example, the power of the camera 1 is turned on and the moving image shooting start button is turned on.

  First, in step S101, the camera control unit 21 starts a defocus amount calculation process by the phase difference detection method. In the present embodiment, the process of calculating the defocus amount by the phase difference detection method is performed as follows. That is, first, the camera control unit 21 reads out a pair of image data corresponding to a pair of images from each of the focus detection pixels 222a and 222b included in the five focus detection pixel columns 22a to 22e of the image sensor 22. Then, the camera control unit 21 performs an image shift detection calculation process (correlation calculation process) based on the pair of read image data, and performs image shift detection at the focus detection positions corresponding to the five focus detection pixel columns 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. The evaluation of the reliability of the defocus amount is performed based on, for example, the degree of coincidence and contrast between a pair of image data. The process of calculating the defocus amount by 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 is calculated by reading the pixel output of the imaging pixel 221 of the imaging element 22, extracting the high-frequency component of the read pixel output using a high-frequency transmission filter, integrating the extracted high-frequency components, and integrating the focus. This is performed by detecting the voltage. The calculation process of the focus evaluation value is repeatedly executed at predetermined intervals.

  Next, in step S103, the camera control unit 21 starts tracking calculation processing for tracking the subject. In the present embodiment, first, a template image corresponding to a specific subject to be tracked specified by a user's manual operation or subject recognition processing by the camera control unit 21 is generated. Then, an area having a degree of coincidence with the generated template image that is equal to or greater than a predetermined value is searched, areas having a degree of coincidence that is equal to or more than a predetermined value are sequentially extracted, and the extracted area is referred to as a focus detection area AFP (for example, see FIG. 2). ). Note that the tracking calculation processing is repeatedly executed at predetermined intervals.

  In step S104, the camera control unit 21 determines by the phase difference detection method whether or not the defocus amount has been calculated in the focus detection area AFP set based on the tracking calculation processing. If the defocus amount has been calculated, it is determined that distance measurement is possible, and the process proceeds to step S109. 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. Note that, in the present embodiment, even when the defocus amount can be calculated in the focus detection area AFP set based on the tracking calculation processing, or when the reliability of the calculated defocus amount is low, the defocus amount is not changed. It is assumed that the focus amount cannot be calculated, and the process proceeds to step S105. In the present embodiment, for example, when the contrast of the subject is low, when the subject is an ultra-low luminance subject, or when the subject is an ultra-high luminance subject, it is determined that the reliability of the defocus amount is low. . When the focus detection area AFP set based on the tracking calculation processing is located in the first area shown in FIG. 2, the focus state of the optical system can be detected by the phase difference detection method. When the focus detection area AFP is located in the second area shown in FIG. 2, the focus state of the optical system cannot be detected by the phase difference detection method. In this case, the defocus amount cannot be calculated. Then, the process proceeds to step S105.

  In step S104, the above determination is made using the result of the most recent one defocus amount calculation process. However, in the last predetermined number of defocus amount calculation processes, the defocus amount is continuously calculated. If it is not possible, 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 latest predetermined number of times, Alternatively, if the defocus amount is calculated even once, it may be determined that distance measurement is possible and the process proceeds to step S109.

  In step S104, when it is determined that the defocus amount in the focus detection area AFP has been calculated and it is determined that the distance measurement is possible, the process proceeds to step S109, where the defocus amount is calculated based on the defocus amount calculated by the phase difference detection method. A focusing operation is performed. Specifically, in step S109, a process of driving the focus lens 32 to the in-focus position is performed based on the defocus amount calculated by the phase difference detection method in step S101. Specifically, the camera control unit 21 calculates a lens drive amount required to drive the focus lens 32 to the in-focus position from the defocus amount calculated by the phase difference detection method, and calculates the calculated amount. The lens drive amount is sent to the lens drive motor 36 via the lens control unit 37. Then, the 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, even while the lens drive motor 36 is driven and the focus lens 32 is driven to the in-focus position, the control unit 21 repeatedly calculates the defocus amount by the phase difference detection method. As a result, when a new defocus amount is calculated, the control unit 21 drives the focus lens 32 based on the new defocus amount.

  When the focus lens 32 is driven to the in-focus position, the process proceeds to step S110, in which the focus lens 32 is stopped at the in-focus position, and proceeds to step S111 to determine whether the focus state of the optical system has changed. Is performed. For example, when the defocus amount by the phase difference detection method repeatedly calculated by the camera control unit 21 changes by a predetermined value or more, or when the defocus amount cannot be calculated, or when the defocus amount is similarly calculated by the camera control unit 21 repeatedly. When the focus evaluation value changes by a predetermined value or more, it can be determined that the focus state of the optical system has changed. If it is determined that the focus state of the optical system has changed, the process returns to step S104, and the operation for driving the focus lens 32 to the focus position is performed again. On the other hand, if the focus state of the optical system has not changed, a predetermined end operation, for example, a power-off operation of the camera 1 or an end operation of moving image shooting is performed (step S112), or the focus of the optical system is changed. Until the state is changed (step S111), the focus lens 32 stands by while being stopped at the current lens position.

  On the other hand, if it is determined in step S104 that the defocus amount cannot be calculated in the focus detection area AFP by the phase difference detection method, the process proceeds to step S105, and the camera control unit 21 starts the scanning operation. Is performed. In the scanning operation of the present embodiment, the calculation of the defocus amount and the calculation of the focus evaluation value by the phase difference detection method are performed by the camera control unit 21 while the focus lens drive motor 36 scans and drives the focus lens 32. This is an operation in which the detection of the focus position by the phase difference detection method and the detection of the focus position by the contrast detection method are simultaneously performed at predetermined intervals.

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

  Then, 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 while driving the focus lens 32, and based on this, The phase difference detection method is used to calculate the defocus amount and evaluate the reliability of the calculated defocus amount. At the same time, while driving the focus lens 32, the pixel output from the imaging pixel 221 of the imaging element 22 is determined at predetermined intervals. Reading is performed, a focus evaluation value is calculated based on the readout, and a focus evaluation value at a different focus lens position is thereby obtained, thereby detecting a focus position by a contrast detection method. In this embodiment, when the focus detection area AFP set based on the tracking calculation processing is located in the first area shown in FIG. 2, the focus state detection of the optical system by the phase difference detection method is performed. On the other hand, when the focus detection area AFP is located in the second area shown in FIG. 2, the focus state of the optical system cannot be detected by the phase difference detection method. Therefore, when the focus detection area AFP is located in the second area shown in FIG. 2, in the scanning operation of the present embodiment, the focus position is not detected by the phase difference detection method, and the contrast detection method is not performed. Only the focus position is detected.

  In step S106, as a result of the scanning operation performed by the camera control unit 21, it is determined whether or not the defocus amount in the focus detection area AFP has been calculated by the phase difference detection method. If the amount of defocus can be calculated, it is determined that distance measurement is possible, and the process proceeds to step S109. If the amount of defocus is not calculated, it is determined that distance measurement is not possible and the process proceeds to step S107. . In step S106, similarly to step S104 described above, even if the defocus amount can be calculated, if the calculated defocus amount has low reliability, the defocus amount cannot be calculated. And proceeds to step S107. Note that when the focus detection area AFP is located in the second area shown in FIG. 2, the focus state of the optical system cannot be detected by the phase difference detection method. The process proceeds to step S107 on the premise that it could not be performed.

  In step S107, as a result of the scanning operation performed by the camera control unit 21, it is determined whether or not the in-focus position in the focus detection area AFP has been detected by the contrast detection method. If the in-focus position in the focus detection area AFP can be detected by the contrast detection method, the process proceeds to step S113. If the in-focus position cannot be detected, the process proceeds to step S108.

  In step S108, the camera control unit 21 determines whether the scanning operation has been performed over the entire drivable range of the focus lens 32, that is, over the entire range from the infinity end position to the close end position. If the scanning operation has not been performed for the entire drivable range of the focus lens 32, the process returns to step S106, and the steps S106 to S108 are repeated to perform the scanning operation, that is, the phase difference while driving the focus lens 32. The operation of simultaneously executing the calculation of the defocus amount by the detection method and the detection of the focus position by the contrast detection method at predetermined intervals is continuously performed. On the other hand, if the execution of the scan operation has been completed for the entire drivable range of the focus lens 32, the process proceeds to step S118.

  Then, as a result of executing the scanning operation, when it is determined in step S106 that the defocus amount has been calculated by the phase difference detection method, the scanning operation is stopped, and the process proceeds to step S109. A focusing operation is performed based on the defocus amount calculated by the phase difference detection method. When the drive of the focus lens 32 to the in-focus position is completed, if the focus state of the optical system has not changed, a predetermined end operation is performed (step S112), or the focus state of the optical system is changed. Is changed (step S111), the focus lens 32 stands by at the current lens position and stands by (step S110).

  If it is determined in step S107 that the in-focus position has been detected by the contrast detection method as a result of performing the scanning operation, the scanning operation is stopped, the process proceeds to step S113, and the detection is performed by the contrast detection method. A focusing operation is performed based on the focusing position. That is, in step S113, a focus driving process of driving the focus lens 32 to the focus position based on the focus position detected by the contrast detection method is performed. Here, FIG. 10 is a diagram showing the relationship between the focus lens position and the focus evaluation value and the relationship between the focus lens position and time when the focus position is detected by the contrast detection method as a result of the scanning operation. Show. In FIG. 10, a change in the focus evaluation value with respect to the position of the focus lens 32 is indicated by a solid line. As shown in FIG. 10, at the start of the scanning operation, the focus lens 32 is located at P0 shown in FIG. 10. From P0, the focus lens 32 is driven from the infinity side to the close side, and the focus evaluation is performed. Get the value. Then, when the focus lens 32 is moved to the position P1 shown in FIG. 10 and the peak position (focus position) of the focus evaluation value is detected (Step S107 = Yes), the scanning operation is stopped. Focus driving (step S113) for driving the focus lens 32 to a focus position (the position P2 in FIG. 10) is performed.

  In the present embodiment, it is determined in step S107 that the in-focus position has been detected by the contrast detection method, and when the focus lens 32 is driven to the in-focus position based on the detection result by the contrast detection method. The driving of the focus lens 32 based on the focus detection result by the phase difference detection method is prohibited until the driving of the focus lens 32 to the in-focus position is completed. That is, after it is determined that the focus position has been detected by the contrast detection method, even if the defocus amount can be calculated by the phase difference detection method, the driving of the focus lens 32 based on the result of the phase difference detection method is performed. Ban. Thereby, the hunting phenomenon of the focus lens 32 can be suppressed.

  In the scanning operation of the present embodiment, the above-described steps S106 to S108 are repeatedly performed to calculate the defocus amount by the phase difference detection method and to calculate the defocus amount by the contrast detection method while scanning the focus lens 32. The detection of the focus position is simultaneously performed at a predetermined interval. Then, as a result of repeatedly executing the above-described steps S106 to S108, the focus detection result by the detection method that can calculate the defocus amount first or detect the in-focus position out of the phase difference detection method and the contrast detection method is obtained. Then, a process of driving the focus lens 32 to the in-focus position is performed. Further, as described above, in the scanning operation of the present embodiment, after determining whether or not the defocus amount has been calculated by the phase difference detection method (Step S106), the focus position can be detected by the contrast detection method. (Step S107), when the phase difference detection method and the contrast detection method can calculate the defocus amount and detect the in-focus position at the same time, focus by the phase difference detection method The detection result is adopted prior to the focus detection result by the contrast detection method.

  When the driving of the focus lens 32 to the in-focus position is completed, the process proceeds to step S114, and it is determined whether the wobbling drive of the focus lens 32 is possible. Specifically, the camera control unit 21 acquires information on a change in magnification of an image by the photographing optical system with respect to a unit movement amount of the focus lens 32 in the optical axis L1 direction at the current position of the focus lens 32, and acquires the acquired information. It is determined whether or not the change in the angle of view when the wobbling drive of the focus lens 32 is equal to or less than a predetermined value, and if the change in the angle of view is equal to or less than the predetermined value, It is determined that wobbling drive is possible. If it is determined that the wobbling drive of the focus lens 32 is possible, the process proceeds to step S115, and the wobbling drive is started. On the other hand, when it is determined that the wobbling drive of the focus lens 32 is not possible, the process proceeds to step S110 described above, and whether the focus state has changed while the focus lens 32 is stopped at the current lens position, and It is determined whether or not a predetermined end operation has been performed (steps S110 to S112).

  In step S115, a drive signal for wobbling the focus lens 32 is transmitted from the camera control unit 21 to the lens control unit 37, and the lens control unit 37 controls the driving of the lens drive motor 36 to perform focusing. In the vicinity of the position, wobbling drive for finely reciprocating the focus lens 32 is performed. FIG. 11 is a diagram illustrating the relationship between the position of the focus lens 32 and time during wobbling drive. As shown in FIG. 11, in the wobbling drive, the focus lens 32 is alternately driven with a drive width w toward the closest position and the infinity position with the center position as the center. At the position, the calculation of the focus evaluation value is repeatedly acquired. Then, the average value of the focus evaluation values at the closest position and the average value of the focus evaluation values at the infinity position are compared, and it is determined that the in-focus position has a larger average value. Then, based on such determination, as shown in FIG. 12, the wobbling drive position is corrected to correct the out-of-focus. Specifically, in the example shown in FIG. 12, the following scene is illustrated and illustrated. That is, during the time t1 to t2, the focus evaluation values at the close position and the infinity position are obtained and calculated while performing the wobbling drive of the focus lens 32. As a result, the focus evaluation value at the infinity position is obtained. It is determined that the average value is larger, the wobbling drive position is corrected to the infinity side and the wobbling drive is performed during the time t3 to t4, and the wobbling drive position is corrected to the closest side during the time t5 to t6. An example is shown in which the wobbling drive is performed and the wobbling drive position is further corrected to the nearest side from time t7 to t8, and the wobbling drive is performed.

  Then, when the wobbling drive is started, the process proceeds to step S116, and it is determined whether or not the focus state of the optical system has changed. For example, when the defocus amount by the phase difference detection method repeatedly calculated by the camera control unit 21 changes by a predetermined value or more, or when the defocus amount cannot be calculated, or when the defocus amount is similarly calculated by the camera control unit 21 repeatedly. When the focus evaluation value changes by a predetermined value or more, it can be determined that the focus state of the optical system has changed. If it is determined that the focus state of the optical system has changed, the process returns to step S104, and the operation for driving the focus lens 32 to the focus position is performed again. In this case, in step S104, it is determined whether or not the defocus amount can be calculated by the phase difference detection method based on the calculation result of the defocus amount by the phase difference detection method during the wobbling drive. If the defocus amount can be calculated, the process proceeds to step S109, and the focusing drive of the focus lens is performed based on the defocus amount calculated during the wobbling drive. On the other hand, when the focus state of the optical system has not changed, a predetermined end operation, for example, a power-off operation of the camera 1 or an end operation of moving image shooting is performed (step S117), or the focus of the optical system is changed. Until the state is changed (step S116), the focus lens 32 stands by while wobbling.

  Then, during the wobbling drive of the focus lens 32, for example, as shown in FIG. 10, if the focus position changes from P2 to P3, the process returns to step S104, and the defocusing is performed during the wobbling drive. If the amount can be calculated, the process proceeds to step S109, and the focusing drive of the focus lens is performed based on the defocus amount calculated during the wobbling drive. On the other hand, when the defocus amount cannot be calculated, as shown in FIG. 10, scan drive of the focus lens 32 (steps S106 to S108) is performed, and as a result of the scan drive, the focus position is determined by the contrast detection method. If it is detected (step S107 = Yes), the focusing drive is performed based on the result (step S113). In FIG. 10, the relationship between the focus lens position and the focus evaluation value when the focus position is detected by the contrast detection method as a result of scan driving when the AF-F mode is selected. , And the relationship between the focus lens position and time.

  That is, in the present embodiment, when the AF-F mode is set, the focus state can be detected by the phase difference detection method (Step S104 = Yes, Step S106 = Yes), and the focus by the phase difference detection method After the focusing drive based on the detection result (step S109), the apparatus waits until the focus state changes or a predetermined end operation is performed with the focus lens 32 stopped (steps S110 to S112). ). On the other hand, in the present embodiment, the focus state can be detected by the contrast detection method (step S107 = Yes), and after the focus driving based on the focus detection result by the contrast detection method (step S113), the focus lens 32 is wobbled. While driving, it waits until the focus state changes or a predetermined end operation is performed (steps S115 to S117).

  On the other hand, if it is determined in step S108 that the execution of the scanning operation has been completed for the entire drivable range of the focus lens 32, the process proceeds to step S118. In step S118, as a result of performing the scan operation, the focus detection could not be performed by any of the phase difference detection method and the contrast detection method. Therefore, the scan operation was terminated, and the focus lens 32 was set in advance. Processing for driving to a predetermined position is performed.

  When the focus lens 32 is driven to the predetermined position, the process proceeds to step S119, in which the focus lens 32 is stopped at the predetermined position, and the process proceeds to step S120 to determine whether the focus state of the optical system has changed. Is determined. For example, when the defocus amount by the phase difference detection method repeatedly calculated by the camera control unit 21 changes by a predetermined value or more, or when the defocus amount cannot be calculated, or when the defocus amount is similarly calculated by the camera control unit 21 repeatedly. When the focus evaluation value changes by a predetermined value or more, it can be determined that the focus state of the optical system has changed. If it is determined that the focus state of the optical system has changed, the process returns to step S104, and the operation for driving the focus lens 32 to the focus position is performed again. On the other hand, if the focus state of the optical system has not changed, a predetermined end operation, for example, a power-off operation of the camera 1 or an end operation of moving image shooting is performed (step S121), or the focus of the optical system is changed. Until the state is changed (Step S120), the focus lens 32 stands by while being stopped at the current lens position.

  That is, in the present embodiment, when the AF-F mode is set, if the focus state cannot be detected and the scanning operation is terminated (step S118), the focus detection result by the phase difference detection method is used. As in the case where the focusing drive is performed based on the condition (2), with the focus lens 32 stopped, the process waits until the focus state changes or a predetermined end operation is performed (steps S110 to S112).

  In the present embodiment, when the AF-F mode, which is a mode suitable for capturing a moving image, is selected, the operation is performed as described above.

  Next, an operation example when the AF-S mode or the AF-A mode, which is a mode suitable for still image shooting, is selected will be described. FIG. 13 is a flowchart showing an operation when the AF-S mode or the AF-A mode is selected. The following operation is started, for example, when the power of the camera 1 is turned on.

  First, in steps S201 to S203, similarly to steps S101 to S103 in FIG. 9 described above, a process of calculating a defocus amount by a phase difference detection method (step S201), a process of calculating a focus evaluation value (step S202), and A process for starting a tracking calculation process (step S203) for tracking a subject is performed.

  Then, the process proceeds to step S204. In step S204, the camera control unit 21 determines whether or not the shutter release button provided on the operation unit 28 is half-pressed (the first switch SW1 is turned on). If the first switch SW1 has been turned on, the process proceeds to step S205. On the other hand, if the first switch SW1 is not turned on, step S204 is repeated until the first switch SW1 is turned on. That is, until the first switch SW1 is turned on, the defocus amount calculation processing, the focus evaluation value calculation processing, and the tracking calculation processing by the phase difference detection method are repeatedly executed.

  In step S205, similarly to step 104 of FIG. 9 described above, it is determined whether or not the defocus amount has been calculated in the focus detection area AFP set based on the tracking calculation processing by the phase difference detection method. It is. If the defocus amount has been calculated, it is determined that distance measurement is possible, and the process proceeds to step S210. 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 S206.

  In step S205, when it is determined that the defocus amount in the focus detection area AFP has been calculated and it is determined that the distance measurement is possible, the process proceeds to step S210, and the phase difference is determined in the same manner as in step S109 in FIG. A focusing operation is performed based on the defocus amount calculated by the detection method. When the focus lens 32 is driven to the in-focus position, the process proceeds to step S213.

  On the other hand, if it is determined in step S205 that the defocus amount cannot be calculated in the focus detection area AFP by the phase difference detection method, the process proceeds to step S206, and the camera control unit 21 starts the scanning operation. Then, in steps S207 to S209, a scanning operation is performed in the same manner as in steps S106 to S108 in FIG. 9 described above.

  Then, as a result of the scanning operation, if the defocus amount in the focus detection area AFP can be calculated by the phase difference detection method (step S207 = Yes), the process proceeds to step S210, and the calculation is performed by the phase difference detection method. A focusing operation is performed based on the set defocus amount. If the in-focus position in the focus detection area AFP can be detected by the contrast detection method as a result of performing the scanning operation (step S208 = Yes), the process proceeds to step S211 and proceeds to step S113 in FIG. Similarly, a focusing operation is performed based on the focusing position detected by the contrast detection method.

  On the other hand, if it is determined in step S209 that the execution of the scan operation has been completed for the entire drivable range of the focus lens 32, the process proceeds to step S212. In step S212, as a result of the scanning operation, focus detection could not be performed by any of the phase difference detection method and the contrast detection method, so the scanning operation was terminated and the focus lens 32 was set in advance. Processing for driving to a predetermined position is performed.

  Then, in step S210, the focus lens 32 is driven to the focus position based on the defocus amount calculated by the phase difference detection method, and then in step S211 based on the focus position detected by the contrast detection method. After the focus lens 32 is driven to the in-focus position, or after the process of driving the focus lens 32 to a predetermined position in step S212, the process proceeds to step S213, and the auto focus mode is set to AF. It is determined whether the mode is set to the -S mode. When the AF-S mode is set, the process proceeds to step S214. When the AF-A mode is set instead of the AF-S mode, the process proceeds to step S216.

  If the AF-S mode has been set, the process proceeds to step S214, and in step S214, focus lock for fixing the focus lens 32 to the current lens position is performed. Then, in step S215, it is determined whether or not the shutter release button provided on the operation unit 28 is fully pressed (the second switch SW2 is turned on). When the second switch SW2 is turned on, the process proceeds to step S215. Proceeding to S219, shooting of a subject image is performed. On the other hand, if the second switch SW2 is not turned on, the control waits until the second switch SW2 is turned on with the focus lens 32 fixed at the current lens position.

  FIG. 14 shows the relationship between the focus lens position and the focus evaluation value and the focus when the focus position is detected by the contrast detection method as a result of scan driving when the AF-S mode is selected. 4 shows a relationship between a lens position and time. As shown in FIG. 14, when the AF-S mode is selected, the focus position is detected by the contrast detection method as a result of the scan drive, and when the focus drive is performed based on this, In order to perform focus lock for fixing the focus lens 32 to the current lens position, even if the focus position subsequently changes from P2 to P3 shown in FIG. 14, the focus lens 32 is driven by the first scan drive. Position will be maintained.

  On the other hand, if the AF-A mode is set, the process proceeds to step S216, in which the focus lens 32 is stopped at the in-focus position, and the process proceeds to step S217 to determine whether the focus state of the optical system has changed. Is determined. For example, when the defocus amount by the phase difference detection method repeatedly calculated by the camera control unit 21 changes by a predetermined value or more, or when the defocus amount cannot be calculated, or when the defocus amount is similarly calculated by the camera control unit 21 repeatedly. When the focus evaluation value changes by a predetermined value or more, it can be determined that the focus state of the optical system has changed. If it is determined that the focus state of the optical system has changed, the process returns to step S204. If the first switch SW1 is in the ON state, the above-described processes of steps S205 to S212 are performed again. Then, an operation for driving the focus lens 32 to the in-focus position is performed. On the other hand, if the focus state of the optical system has not changed, the focus lens 32 is turned on until the second switch SW2 is turned on (step S218) or until the focus state of the optical system changes (step S217). Stand by while stopping at the current lens position.

  FIG. 15 shows the relationship between the focus lens position and the focus evaluation value, and the focus when the focus position is detected by the contrast detection method as a result of scan driving when the AF-A mode is selected. 4 shows a relationship between a lens position and time. As shown in FIG. 15, when the AF-A mode is selected, the focus position is detected by the contrast detection method as a result of the scan drive, and when the focus drive is performed based on this, With the focus lens 32 stopped at the current lens position, the process waits until the second switch SW2 is turned on (step S218) or the focus state of the optical system changes (step S217). Then, when the in-focus position changes from P2 to P3 as shown in FIG. 15 while the focus lens 32 is in a standby state with the focus lens 32 stopped, the process returns to step S204 and the first switch SW1 Is turned on, and if the defocus amount can be calculated, the process proceeds to step S210, where the focus lens is driven for focusing based on the defocus amount calculated during the wobbling drive. It will be. On the other hand, if the defocus amount cannot be calculated, as shown in FIG. 15, the scan drive of the focus lens 32 (steps S207 to S209) is performed, and as a result of the scan drive, the focus position is determined by the contrast detection method. If the detection is successful (step S208 = Yes), the focusing drive is performed based on the result (step S211).

  In the present embodiment, when the AF-S mode or the AF-A mode, which is a mode suitable for still image shooting, is selected, the operation is performed as described above.

  In the present embodiment, when the AF-F mode, which is a mode suitable for moving image shooting, is selected, as a result of scan driving, the focus state can be detected by the contrast detection method, and the focus detection by the contrast detection method can be performed. After the focusing drive based on the result, while the focus lens 32 is being wobbled, it waits until the focus state changes or a predetermined end operation is performed. On the other hand, in the present embodiment, when the AF-A mode, which is a mode suitable for still image shooting, is selected, the focus driving is performed based on the focus detection result by the contrast detection method. In a state in which the focus lens 32 is stopped at the in-focus position without wobbling driving the lens 32, the apparatus waits until the focus state changes or a predetermined end operation is performed. Therefore, according to the present embodiment, when the AF-F mode, which is a mode suitable for shooting a moving image, is selected, the focus lens 32 is driven by wobbling, and the mode suitable for shooting a still image is set. When a certain AF-A mode is selected, the wobbling drive of the focus lens 32 is not performed, so that the focusing accuracy can be improved both when shooting a moving image and when shooting a still image. Can be used with good feeling. In particular, when the AF-F mode, which is a mode suitable for moving image shooting, is selected, the focus lens 32 is driven by wobbling, so that when the focus is slightly shifted during moving image shooting, such a minute Defocus can be effectively corrected. When the AF-A mode, which is a mode suitable for still image shooting, is selected, the wobbling drive of the focus lens 32 is not performed, so that the occurrence of out-of-focus due to the wobbling drive is effective during still image shooting. Can be prevented. As described above, in the present embodiment, the focus adjustment of the optical system can be appropriately performed.

  Further, in the present embodiment, when the wobbling drive of the focus lens 32 is performed when the AF-F mode, which is a mode suitable for capturing a moving image, is selected, the unit movement of the focus lens 32 in the optical axis L1 direction is performed. Information on the magnification change of the image by the photographing optical system with respect to the amount, and based on the acquired information, when the change in the angle of view when the focus lens 32 is driven by wobbling is equal to or less than a predetermined value, the focus lens Since the wobbling drive is performed on the 32, it is possible to appropriately suppress a change in the angle of view when the wobbling drive is performed.

  Further, in the present embodiment, when the AF-F mode, which is a mode suitable for moving image shooting, is selected, the defocus amount can be calculated by the phase difference detection method, and the defocus amount calculated by the phase difference detection method can be calculated. When the focus lens 32 is driven to the focus position based on the focus amount, the defocus amount can be calculated by the phase difference detection method even after the focus lens 32 is driven to the focus position. Since the possibility is high, the wobbling drive of the focus lens 32 is not performed. As a result, it is possible to prevent a change in the angle of view due to the wobbling drive, and it is possible to suppress power consumption accompanying the wobbling drive.

  In addition, in the present embodiment, when the AF-F mode, which is a mode suitable for moving image shooting, is selected, and when the focus state cannot be detected by either the phase difference detection method or the contrast detection method, Does not perform the wobbling drive of the focus lens 32 because it is unlikely that the direction in which the focus position exists can be detected even if the wobbling drive of the focus lens 32 is performed. As a result, it is possible to prevent a change in the angle of view due to the wobbling drive, and it is possible to suppress power consumption accompanying the wobbling drive.

  The embodiments described above are described for facilitating the understanding of the present invention, and are 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 wobbling drive of the focus lens 32 is performed, the camera control unit 21 uses the lens control unit 37 to control the unit moving amount of the focus lens 32 in the direction of the optical axis L1 by the imaging optical system. Although the configuration is such that the information on the magnification change of the image is obtained and the camera control unit 21 determines whether or not to perform the wobbling drive of the focus lens 32 based on the obtained information. Information on whether or not wobbling is possible is stored for each lens position of the lens 32, and using this information, the camera control unit 21 determines whether or not to perform wobbling driving of the focus lens 32. It may be configured. Alternatively, the camera control unit 21 previously stores information on whether or not wobbling is possible for each type of lens barrel, and based on the information on the lens type transmitted from the lens control unit 37, the camera control unit The configuration may be such that 21 determines whether to perform wobbling drive of the focus lens 32.

  Further, in the above-described embodiment, when the AF-F mode, which is a mode suitable for moving image shooting, is selected, and when the focus state cannot be detected in any of the phase difference detection method and the contrast detection method, Has a configuration in which the wobbling drive of the focus lens 32 is not performed. For example, when the camera control unit 21 is configured to have a function of setting a scene mode, and a specific scene mode is set, In any of the phase difference detection method and the contrast detection method, the wobbling drive of the focus lens 32 may be performed even when the focus state cannot be detected. For example, in a case where a scene mode such as a landscape mode in which a distant view is often taken is set, such a scene is set because an in-focus position often exists at or near the infinity position. In either case, if the focus state cannot be detected in any of the phase difference detection method and the contrast detection method, the focus lens 32 is driven to the infinity position and the wobbling drive is performed near the infinity position. It may be configured. Alternatively, in a case where a scene mode, such as a person mode, in which shooting is frequently performed at a predetermined shooting distance is set, such a scene is set because an in-focus position often exists at a predetermined shooting distance. If the focus state cannot be detected in either of the phase difference detection method and the contrast detection method, the focus lens 32 is driven to a position corresponding to a predetermined shooting distance, and It may be configured to perform wobbling drive.

DESCRIPTION OF SYMBOLS 1 ... Digital camera 2 ... Camera main body 21 ... Camera control part 22 ... Imaging element 221 ... Imaging pixel 222a, 222b ... Focus detection pixel 3 ... Lens barrel 32 ... Focus lens 36 ... Focus lens drive motor 37 ... Lens control part 38 ... Lens memory

Claims (8)

An imaging unit that captures an image by an optical system having a focusing optical system and outputs a signal,
Based on a signal output from the imaging unit, a detection unit that detects a shift amount between a focus position where an image by the optical system is focused on the imaging unit and a position of the focus adjustment optical system,
When the variation value of the magnification of the optical system when the focus adjusting optical system is moved is less than a predetermined value, the position of the focus adjusting optical system is slightly reciprocated in the optical axis direction, and the focus adjusting optical system is moved. When a shift amount is detected by the detection unit during the minute reciprocating movement of, a control unit that controls the position of the focus adjustment optical system based on the shift amount,
An imaging device comprising: The imaging device according to claim 1,
The detection unit can detect the in-focus position based on a contrast of an image based on a signal output from the imaging unit,
The control unit, during a minute reciprocating movement to reciprocate the position of the focus adjustment optical system minutely in the optical axis direction, when the focus state of the optical system changes and the shift amount cannot be calculated, When the focus adjustment position is detected by the detection unit by stopping the minute reciprocating movement and moving the focus adjustment optical system, the imaging to control the position of the focus adjustment optical system to the detected focus position apparatus. The imaging device according to claim 2,
The controller may be configured to perform one of the optical axes when the defocus amount changes by a predetermined value or more or the focus evaluation value changes by a predetermined value or more during the minute reciprocating movement and the shift amount cannot be calculated. An imaging device for moving the focusing optical system in a direction. The imaging device according to claim 3,
The control unit, when moving the focus adjustment optical system in one direction of the optical axis, when the shift amount is detected by the detection unit, the position of the focus adjustment optical system based on the shift amount. An imaging device that controls the camera. The imaging device according to claim 3, wherein
The control unit, while moving the focus adjustment optical system in one direction of the optical axis, when the detection unit detects the focus position, the position of the focus adjustment optical system to the focus position An imaging device that controls the camera. The imaging device according to any one of claims 3 to 5,
The control unit is configured to move the focus adjustment optical system to a predetermined position if the detection unit does not detect the shift amount and the in-focus position while moving the focus adjustment optical system in one direction of the optical axis. An imaging device that controls the position of the system. The imaging device according to any one of claims 1 to 6,
Wherein, after moving the focusing optical system to the focus position, the variation value of the magnification of the optical system when the from-focus position by moving the focusing optical system is less than a predetermined value There is an image pickup apparatus that slightly reciprocates the position of the focus adjustment optical system in the optical axis direction. The imaging device according to any one of claims 1 to 7,
The control unit does not reciprocate the position of the focus adjustment optical system minutely in the optical axis direction when the change value of the magnification of the optical system when the focus adjustment optical system is moved is equal to or more than a predetermined value. An imaging apparatus configured to control a position of the focus adjustment optical system based on the shift amount when the focus state of the optical system changes and the detection unit detects the shift amount.

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