JP2019095808A - Imaging apparatus - Google Patents

Abstract

To provide an imaging apparatus capable of reducing the time from the half-pressing of a release button to the driving of a focus lens.SOLUTION: The imaging apparatus includes an imaging part which captures an image by an optical system having a focus adjustment optical system 32 and outputs a signal, a detection part which detects the focusing position of the focus adjustment optical system 32 where the image by the optical system is focused on the imaging part on the basis of the signal outputted from the imaging part, a position control part which controls the position of the focus adjustment optical system 32, and an operation part which is operated to control the position of the focus adjustment optical system 32 to the focusing position by the position control part. When the operation part is operated, the position control part controls the position of the focus adjustment optical system 32 on the basis of the focusing position detected by the detection part up to movement to the focusing position from the start of the movement of the focus adjustment optical system 32.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an imaging device.

  Conventionally, there is known a focusing device which detects a focusing state of an optical system after a release button is pressed halfway. In such a focusing device, there is known a technique for performing exposure control when the output level of an image signal used for focus detection is not within a predetermined range in order to appropriately detect the focus state of the optical system ( For example, Patent Document 1).

JP-A-4-157411

  However, in the prior art, when detecting the focus state of the optical system, if the output level of the image signal used for focus detection is not within the predetermined range, the exposure control is uniformly performed, so the release button There is a case where it takes time until the focus lens is driven after half-pressing.

  The problem to be solved by the present invention is to provide an imaging device capable of shortening the time from when the release button is pressed halfway to when the focus lens is driven.

  The present invention solves the above-mentioned subject by the following solution means. Although the following description will be made with reference to the reference numerals corresponding to the drawings showing the embodiments of the present invention, these reference numerals are for the purpose of facilitating the understanding of the present invention and are not intended to limit the present invention. .

[1] An image pickup apparatus according to the present invention is an image pickup section for picking up an image by an optical system having a focusing optical system and outputting a signal, and an image by the optical system based on a signal outputted from the image pickup section. A detection unit that detects the in-focus position of the focusing optical system that focuses on the imaging unit; a position control unit that controls the position of the focusing optical system; and And an operation unit operated to control the position to the in-focus position, and the position control unit is configured to start the movement of the focusing optical system after the operation unit is operated. The position of the focusing optical system is controlled based on the in-focus position detected by the detection unit before moving to the in-focus position.
[2] In the invention according to the above imaging apparatus, when the operation unit is operated, the position control unit moves the focusing optical system to the in-focus position detected by the detection unit until the operation unit is operated. The movement of the system is started, and the position of the focusing optical system is controlled based on the in-focus position detected by the detection unit from the start of the movement of the focusing optical system to the movement to the in-focus position. Can be configured to
[3] In the invention relating to the image pickup apparatus described above, the image pickup section for picking up an image by an optical system having a focusing optical system and outputting a signal is provided, and the detection section is based on the signal output from the image pickup section. A shift amount between the focusing position of the focusing optical system and the focusing optical system is detected, and the position control unit detects the position of the focusing optical system based on the shift amount detected by the detection unit. It can be configured to control.
[4] In the invention according to the above-mentioned imaging device, the position control unit is operated until the operation unit is operated if the displacement amount detected by the detection unit is reliable before the operation unit is operated. The position of the focusing optical system can be controlled based on the detected displacement amount.
[5] In the invention relating to the above imaging device, the position control unit operates the operation unit when the displacement amount detected by the detection unit is not reliable before the operation unit is operated. The position of the focusing optical system can be controlled based on the amount of displacement detected by the detection unit until the movement of the focusing optical system is started.
[6] In the invention relating to the imaging device, the position control unit does not have reliability in the displacement amount detected by the detection unit before the operation unit is operated, and the signal output from the imaging unit When the size of is within a predetermined range, the focus adjustment optical system can be moved to detect the in-focus position by the detection unit.
[7] In the invention relating to the above imaging apparatus, when the operation unit is operated, the position control unit starts moving the focusing optical system until the detection unit moves to the in-focus position. And an exposure control unit that performs exposure control for detecting the in-focus position.
[8] In the invention relating to the above imaging apparatus, the exposure control unit performs exposure control for capturing an image to be displayed on the display unit until the operation unit is operated, and the position control unit performs the focus control. The exposure control for detecting the in-focus position can be performed by the detection unit from the start of the movement of the adjustment optical system to the movement to the in-focus position.

  According to the present invention, it is possible to shorten the time from when the release button is pressed halfway to when the focus lens is driven.

FIG. 1 is a block diagram showing a camera according to the present 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 an arrangement of the focus detection pixels 222a and 222b by enlarging a portion III of 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 sectional view showing one of the focus detection pixels 222a, and FIG. 7B is an enlarged sectional view showing one of the focus detection pixels 222b. FIG. 8 is a cross-sectional view taken along the line VIII-VIII in FIG. FIG. 9 is a flowchart showing an operation example of the camera according to the present embodiment. FIG. 10 is a flowchart showing the scan operation execution process of step S113. FIG. 11 is a diagram for explaining an operation example of the camera according to the present embodiment. FIG. 12 is a diagram for explaining an operation example of the camera according to the present embodiment.

  Hereinafter, embodiments of the present invention will be described based on the drawings.

  FIG. 1 is a main part configuration diagram showing a digital camera 1 according to an embodiment of the present invention. The digital camera 1 (hereinafter simply referred to as the camera 1) of the present embodiment is composed of 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 There is.

  The lens barrel 3 is an interchangeable lens that is detachable from the camera body 2. As shown in FIG. 1, the lens barrel 3 incorporates a photographing optical system including lenses 31, 32, 33 and a diaphragm 34.

  The lens 32 is a focus lens, and can move in the direction of the optical axis L1 to adjust the focal length of the imaging optical system. 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 rotary cylinder is rotatably inserted into a fixed cylinder fixed to the lens barrel 3, and a helicoid groove (helical groove) is formed on the inner peripheral surface of the rotary cylinder, and the focus lens 32 is fixed. The end of the lens frame is fitted in 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 rectilinearly along the optical axis L1.

  As described above, the focus lens 32 fixed to the lens frame moves rectilinearly in the direction of the optical axis L1 by rotating the rotary cylinder with respect to the lens barrel 3, but the focus lens drive motor 36 as its drive source is a lens The lens barrel 3 is provided. The focus lens drive motor 36 and the rotary cylinder are connected by, for example, a transmission composed of a plurality of gears, and when the drive shaft of the focus lens drive motor 36 is rotationally driven in either direction, it is transmitted to the rotary cylinder with a predetermined gear ratio. Then, when the rotary cylinder rotates in any one direction, the focus lens 32 fixed to the lens frame moves rectilinearly 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, the gears constituting the transmission also rotate in the reverse direction, and the focus lens 32 moves rectilinearly 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 cylinder, and therefore can be determined by detecting the relative rotation angle of the rotary cylinder with respect to the lens barrel 3, for example.

  The encoder 35 according to the present embodiment detects a rotation of a rotating disk connected to the rotational drive of the rotating cylinder by an optical sensor such as a photo interrupter and outputs a pulse signal according to the number of rotations, or a fixed cylinder The encoder contacts on the surface of the flexible printed wiring board provided on either one of the rotating cylinder and the brush contact on the other are brought into contact with each other, and the moving amount of the rotating cylinder (in either the rotational direction or the optical axis direction) It is possible to use one that detects a change in the contact position according to (a) by 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 referred to as the near end) to the end on the subject side (also referred to as the infinite end) by 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 based on this information. The drive position of the lens 32 is driven by being sent from the camera control unit 21 via the lens control unit 37.

  The aperture 34 is configured to adjust the aperture diameter centered on the optical axis L1 in order to limit the light amount of the light flux passing through the imaging optical system and reaching the imaging device 22 and to adjust the blur amount. Adjustment of the aperture diameter by the aperture stop 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. Further, the set aperture diameter is input from the camera control unit 21 to the lens control unit 37 by the manual operation by the operation unit 28 provided in the camera body 2. The aperture diameter of the diaphragm 34 is detected by a diaphragm aperture sensor (not shown), and the lens controller 37 recognizes the current aperture diameter.

  On the other hand, in the camera body 2, an imaging element 22 for receiving the light flux L1 from the imaging optical system is provided on a planned focal plane of the imaging optical system, and a shutter 23 is provided on the front surface thereof. The imaging device 22 is configured of a device such as a CCD or a CMOS, converts the received light signal into an electric signal, and sends it to the camera control unit 21. The photographed 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 the release button (provided in the operation unit 28) When the full depression (not shown) is performed, the photographed image information is recorded in the memory 24 which is a recording medium. The memory 24 can use any of a removable card type memory and a built-in type memory. An infrared cut filter for cutting infrared light and an optical low pass filter for preventing aliasing noise of an image are disposed in front of the imaging surface of the image sensor 22. Details of the structure of the imaging device 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 by the electric signal contact unit 41 provided in the mount unit 4, receives lens information from the lens control unit 37, and defocuses the lens control unit 37. Send information such as the amount and aperture diameter. In addition, as described above, the camera control unit 21 reads out the pixel output from the imaging device 22 and generates image information by performing predetermined information processing on the read out pixel output as necessary, and the generated image information Are output to the liquid crystal drive circuit 25 and the memory 24 of the electronic viewfinder 26. Further, the camera control unit 21 controls the entire camera 1 such as correction of image information from the image pickup device 22 and detection of a focusing state of the lens barrel 3, an aperture adjusting state, and the like.

  Further, in addition to the above, the camera control unit 21 detects the focus state of the photographing optical system by the phase detection method based on the pixel data read from the imaging device 22 and detects the focus state of the photographing optical system by the contrast detection method. 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, in the auto focus mode / manual focus mode switching or in the auto focus mode, the one shot mode / conty It is possible to switch the nuisance mode. Here, while the one-shot mode is a mode in which the position of the focus lens 32 adjusted once is fixed and shooting is performed at that focus lens position, in the continuous mode, the position of the focus lens 32 is fixed. In this mode, the focus lens position is adjusted according to the subject. In addition, the operation unit 28 can also switch between the still image shooting mode / moving image shooting mode. The 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. Further, the shutter release button includes a first switch SW1 which is turned on when the button is half pressed, and a second switch SW2 which is turned on when the button is fully pressed.

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

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

  As shown in FIG. 3, in the imaging device 22 of the present embodiment, a plurality of imaging pixels 221 are two-dimensionally arranged on a plane of an imaging surface, and a green pixel G having a color filter transmitting a green wavelength region And 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 what is called a Bayer arrangement. That is, two green pixels are arranged on one diagonal line in adjacent four pixel groups 223 (a dense square lattice array), and one red pixel and one blue pixel are arranged on the other diagonal line. The imaging element 22 is configured by repeatedly arranging the pixel group 223 two-dimensionally on the imaging surface of the imaging element 22 in units of the pixel group 223 in which the Bayer arrangement is performed.

  The arrangement of the unit pixel groups 223 may be, for example, a close hexagonal lattice arrangement, as well as the close square lattice shown in the drawing. Further, the configuration and arrangement of the color filter are not limited to this, and an arrangement of complementary color filters (green: G, yellow: Ye, magenta: Mg, cyan: Cy) can also be adopted.

  FIG. 4 is an enlarged front view showing one of the imaging pixels 221, and FIG. 6 is a sectional view. One imaging pixel 221 includes a microlens 2211, a photoelectric conversion unit 2212, and a color filter (not shown), and as shown in the cross-sectional view of FIG. 6, the photoelectric conversion unit is formed on the surface of the semiconductor circuit substrate 2213 of the imaging device 22. 2212 is fabricated, and a microlens 2211 is formed on the surface. 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 by the microlens 2211 and receives the imaging light flux.

  In addition, focus detection pixel arrays 22a, 22b, and 22c in which focus detection pixels 222a and 222b are arranged instead of the imaging pixels 221 described above at the center of the imaging surface of the imaging element 22 and at three positions symmetrical with respect to the center. Is provided. Then, as shown in FIG. 3, in one focus detection pixel row, a plurality of focus detection pixels 222a and 222b are arranged adjacent to each other and alternately arranged in one horizontal row (22a, 22c, 22c). There is. 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 pixel 221 in Bayer arrangement.

  The positions of the focus detection pixel arrays 22a to 22c shown in FIG. 2 are not limited to the illustrated positions, but may be one or two, or may be disposed at four or more positions. it can. Further, at the time of actual focus detection, the photographer selects a desired focus detection pixel row as a focus detection position by manually operating the operation unit 28 from among the plurality of arranged focus detection pixel rows 22a to 22c. It can also be done.

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

  The photoelectric conversion units 2222a and 2222b of the focus detection pixels 222a and 222b have shapes that receive light beams passing through a predetermined area (for example, F2.8) of the exit pupil of the photographing optical system by the micro lenses 2221a and 2221b. Be done. Further, no color filter is provided in the focus detection pixels 222a and 222b, and the spectral characteristics thereof are obtained by integrating the spectral characteristics of the photodiode performing photoelectric conversion and the spectral characteristics of the infrared cut filter (not shown). ing. However, one of the same color filters as the imaging pixel 221, for example, a green filter may be provided.

  Although the photoelectric conversion units 2222a and 2222b of the focus detection pixels 222a and 222b shown in FIGS. 5A and 5B are semicircular, the shape of the photoelectric conversion units 2222a and 2222b is not limited thereto. And other shapes, for example, an oval shape, a rectangular shape, and a polygonal shape.

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

  FIG. 8 is a cross-sectional view taken along the line VIII-VIII in FIG. 3 and is disposed in the vicinity of the photographing optical axis L1 and the focus detection pixels 222a-1, 222b-1, 222a-2, 222b-2 adjacent to each other are It shows that light beams AB1-1, AB2-1, AB1-2, and AB2-2 emitted from the focusing pupils 341 and 342 of the exit pupil 34 are respectively received. Although FIG. 8 illustrates only one of the plurality of focus detection pixels 222a and 222b located in the vicinity of the photographing optical axis L1, other focus detection pixels other than the focus detection pixels shown in FIG. 8 are shown. Similarly, the light beams emitted from the pair of distance measuring pupils 341 and 342 are also received.

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

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

  Further, as shown in FIG. 8, the microlenses 2221a-1, 2221b-1, 2221a-2, 2221b-2 of the focus detection pixels 222a-1, 222b-1, 222a-2, 222b-2 have a photographing optical system. It is placed near the planned focal plane of. 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, 2221a-2, 2221b-2 is The light is 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 projected shapes form distance measurement pupils 341, 342.

  That is, on the exit pupil 34 located at the distance measurement distance D, the micro lens and photoelectric conversion portion in each focus detection pixel are matched so that the projection shapes (distance measurement pupils 341 and 342) of the photoelectric conversion portion in each focus detection pixel match. The relative positional relationship of is determined, whereby the projection direction of the photoelectric conversion unit at 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 which passes through the distance measurement pupil 341 and is directed to the microlens 2221a-1. Output a signal corresponding to the intensity of the image being Similarly, the photoelectric conversion unit 2222a-2 of the focus detection pixel 222a-2 passes through the distance measurement 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 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 measurement pupil 342, and the intensity of the image formed on the microlens 2221b-2 by the light beam AB2-2 directed to the microlens 2221b-2. Output a signal corresponding to

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

  Then, a conversion operation according to the distance between the center of gravity of the pair of distance measuring pupils is performed on the obtained image shift amount to obtain a current focal plane with respect to the planned focal plane The deviation of the focal plane at the detection position, that is, the defocus amount can be determined.

  The calculation of the image shift amount by the phase difference detection method and the calculation of the defocus amount based on this 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 the focus evaluation value based on the read pixel output. The focus evaluation value can be obtained, for example, by extracting a high frequency component of the image output from the imaging pixel 221 of the image sensor 22 using a high frequency transmission filter and integrating the same to detect a focus voltage. Alternatively, high-frequency components can be extracted by using two high-frequency transmission filters having different cutoff frequencies, and integration can be performed 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 to obtain the position of the focus lens 32 as the in-focus position. It should be noted that, for example, when the focus evaluation value is calculated while driving the focus lens 32, the in-focus position is further lowered twice after the focus evaluation value rises twice. It can obtain | require by performing calculations, such as an interpolation method, using the focus evaluation value of.

  Next, an operation example of the camera 1 according to the present embodiment will be described. FIG. 9 is a flowchart showing an operation example of the camera 1 according to the present embodiment. The following operation is started when the power of the camera 1 is turned on. Also, in the following, the still image shooting mode is selected, and a scene in which the one-shot mode, that is, the mode in which the position of the focus lens 32 adjusted once is fixed and shooting at that focus lens position is selected. To illustrate.

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

  In step S102, the camera control unit 21 starts exposure control for through image generation. Specifically, the camera control unit 21 calculates the luminance value Bv of the entire imaging screen based on the output of the imaging device 22, and based on the calculated luminance value Bv of the entire imaging screen, the appropriate exposure over the entire imaging screen The exposure conditions such as the light reception sensitivity Sv, the exposure time Tv, and the aperture Av are set so that Further, the camera control unit 21 stores the calculated brightness value Bv in the memory 24. The luminance value Bv stored in the memory 24 is used when performing exposure control for focus detection in step S110 or step S117 described later. Although exposure control at the time of through image generation is repeatedly performed at a predetermined interval, the interval at which exposure control for through image generation is performed is longer than the interval at which through image generation and through image display are repeated. can do. For example, exposure control for through image generation can be performed once while generation of the through image and display of the through image are repeated three times.

  In step S103, the camera control unit 21 starts the process of calculating the defocus amount according to 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, light reception from the photographing optical system is performed by the imaging device 22, and the focus detection pixels 222 a and 222 b constituting the three focus detection pixel arrays 22 a to 22 c of the imaging device 22 by the camera control unit 21. From this, 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 the manual operation of the photographer, only data from focus detection pixels corresponding to the focus detection position may be read out. 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 focus detection positions corresponding to the three focus detection pixel arrays 22a to 22c. The shift amount is calculated, and the image shift amount is converted into the defocus amount.

  In step S103, the camera control unit 21 evaluates the reliability of the calculated defocus amount. In the present embodiment, the camera control unit 21 measures the reliability of the defocus amount as “high”, “middle”, “low”, and “reliability” based on, for example, the matching degree or the contrast of a pair of image data. "I can not measure distance." For example, when the degree of coincidence of the pair of image data is high and the reliability of the defocus amount is equal to or greater than the first determination value, the camera control unit 21 evaluates the reliability of the defocus amount as “high”. If the reliability of the defocus amount is less than the first determination value and greater than or equal to a second determination value smaller than the first determination value, the reliability of the defocus amount is "medium". Evaluate. Furthermore, when the reliability of the defocus amount is less than the second determination value and greater than or equal to a third determination value smaller than the second determination value, the camera control unit 21 determines the defocus amount. The reliability of the defocus amount is evaluated as "low", and when the reliability of the defocus amount is less than the third determination value, the reliability of the defocus amount is evaluated as "impossible to measure distance". The defocus amount and the reliability of the defocus amount thus obtained are stored in the memory 24 as history data of the defocus amount.

  Note that the process of calculating the defocus amount according to such a phase difference detection method is repeatedly performed at predetermined intervals while the operation of the camera 1 is performed.

  In step S104, the camera control unit 21 determines whether the shutter release button provided on the operation unit 28 has been half-pressed (the first switch SW1 is turned on). If the shutter release button is pressed halfway, the process proceeds to step S105. On the other hand, if the shutter release button has not been pressed halfway, step S104 is repeated until the shutter release button is pressed halfway. That is, generation and display of a through image, exposure control for through image generation, calculation of the defocus amount, and evaluation of the reliability of the defocus amount are repeatedly performed until the shutter release button is pressed halfway.

  Then, in the subsequent steps S105 to S108, it is determined whether the reliability of the defocus amount calculated before the half depression of the shutter release button is "high" or "medium".

  Specifically, first, in step S105, the camera control unit 21 sets a predetermined parameter n to zero. Then, in step S106, the history data of the defocus amount stored in step S103 is referred to, and the defocus amount and the reliability of the defocus amount calculated before the half-press of the shutter release button is determined according to the parameter n. A determination is made as to whether the defocus amount and the reliability of the defocus amount are "high" or "medium". For example, when the parameter n is set to 0, the camera control unit 21 reads the defocus amount calculated immediately before the shutter release button is half-pressed and the reliability of the defocus amount, and the shutter release is performed. It is determined whether the reliability of the defocus amount calculated immediately before the button is half-pressed is "high" or "medium". In addition, when the parameter n is set to 1, the camera control unit 21 calculates the defocus amount and the defocus amount calculated one before the defocus amount calculated immediately before the shutter release button is half-depressed. The reliability of the focus amount is read, and it is determined whether the reliability of the read defocus amount is “high” or “medium”. Similarly, as the value of n increases, the camera control unit 21 goes back in the past and calculates the defocus amount n times before the defocus amount calculated immediately before the shutter release button is half-depressed. Determine whether the reliability is "high" or "medium".

  When it is determined in step S106 that the reliability of the defocus amount calculated n times before the defocus amount immediately before the shutter release button is half pressed is “high” or “medium”, step The process advances to step S114, and if it is determined that the reliability of the defocus amount calculated n times before the defocus amount immediately before the shutter release button is not “high” or “medium”, the process proceeds to step It progresses to S107.

  In step S107, the camera control unit 21 determines whether the value of the parameter n is less than a predetermined number. If the value of n is less than the predetermined number, the process proceeds to step S108, 1 is added to the value of n, and then the process returns to step S106 to half-press the shutter release button using n set in step S108. It is determined whether the reliability of the defocus amount calculated n times before the previous defocus amount is “high” or “medium”. On the other hand, if it is determined in step S107 that the value of n is equal to or greater than the predetermined number, the process proceeds to step S109.

  As described above, in steps S106 to S108, the reliability of the defocus amount calculated before the half depression of the shutter release button is determined retroactively by a predetermined number in order from the newly calculated defocus amount. If it is determined that the reliability of the defocus amount calculated before the shutter release button is half pressed is "high" or "medium", the process proceeds to step S114, while the shutter release button is half pressed If it is determined that the reliability of the defocus amount previously calculated is not "high" or "medium", the process proceeds to step S109.

  In step S114, since the reliability of the defocus amount calculated before the shutter release button is half pressed is determined to be “high” or “medium”, the camera control unit 21 determines that the reliability is “high”. Or, based on the defocus amount before the shutter release button is half-pressed determined to be “medium”, calculation of the lens driving amount necessary to drive the focus lens 32 to the in-focus position is performed. The calculated lens drive amount is sent to the focus lens drive motor 36 via the lens control unit 37. Next, in step S115, the focus lens drive motor 36 drives the focus lens 32 based on the lens drive amount calculated in step S114.

  Further, as described above, the calculation of the defocus amount and the evaluation of the reliability of the defocus amount started in step S102 are repeatedly performed at predetermined intervals even after the shutter release button is pressed halfway. Therefore, when the reliability of the defocus amount newly calculated after the shutter release button is half-pressed is “high” or “medium”, the camera control unit 21 determines the focus lens based on the defocus amount. The lens drive amount of 32 is newly calculated, and the focus lens 32 is driven based on the newly calculated lens drive amount. The calculation of the lens drive amount is repeatedly performed at predetermined intervals until focusing lock (processing for prohibiting the drive of the focus lens 32) is performed in step S119 described later.

  In step S116, the camera control unit 21 determines whether exposure control for focus detection, which will be described later, is started. If it is determined that the exposure control for focus detection is started, the process proceeds to step S118. If it is determined that the exposure control for focus detection is not started, the exposure control for focus detection is performed. In order to start, the process proceeds to step S117. For example, when it is determined that the reliability of the defocus amount calculated before the shutter release button is half-pressed in step S106 described above is “high” or “medium”, exposure control for focus detection is performed. Since driving of the focus lens 32 is started without being stopped, it is determined in step S116 that the exposure control for focus detection has not been started, and the process proceeds to step S117.

  In step S117, the camera control unit 21 starts exposure control for focus detection in order to set the output levels of the focus detection pixels 222a and 222b within the range of a predetermined output level. Specifically, the camera control unit 21 calculates the luminance value SpotBv in a predetermined area including the focus detection pixel rows 22a to 22c shown in FIG. 2 based on the output of the imaging device 22, and the calculated luminance value SpotBv and The difference between the luminance value Bv of the entire photographed screen calculated in step S102 is calculated as ΔBv. Furthermore, the camera control unit 21 corrects the calculated ΔBv to obtain ΔBv ′ so as to obtain an exposure suitable for focus detection (for example, an exposure one step brighter than the appropriate exposure), and obtains ΔBv ′ based on the corrected ΔBv ′. The exposure conditions such as the light reception sensitivity Sv, the exposure time Tv, and the aperture Av are calculated. Then, the camera control unit 21 changes the exposure condition for through image generation set in step S102 to the exposure condition for focus detection calculated in step S109.

  Also, after changing to the exposure condition for focus detection, the camera control unit 21 for focus detection at a predetermined interval so that the output levels of the focus detection pixels 222a and 222b fall within the range of the predetermined output level. Repeat the exposure control of. Specifically, for example, based on the outputs of the focus detection pixels 222a and 222b, the camera control unit 21 sets the output level of the focus detection pixels 222a and 222b to a range of output levels suitable for focus detection by the phase difference detection method. The exposure conditions such as the light reception sensitivity Sv, the exposure time Tv, and the aperture Av are repeatedly set at predetermined intervals so as to be inside. The interval at which exposure control for focus detection is performed may be longer than the interval at which image data is output from the focus detection pixels 222a and 222b. For example, the output from the focus detection pixels 222a and 222b is 3 During the cycle, exposure control for focus detection can be performed once. Further, in exposure control for focus detection, it is preferable to change the light receiving sensitivity Sv and the exposure time Tv in preference to the aperture Av, and the focus detection pixel can be obtained simply by changing the light receiving sensitivity Sv and the exposure time Tv. When the output levels 222a and 222b can not be set within the predetermined output level range, the diaphragm Av can be changed in addition to the light receiving sensitivity Sv and the exposure time Tv. By changing the light receiving sensitivity Sv and the exposure time Tv in preference to the aperture Av as described above, the aperture value is changed along with the change of the aperture Av, and as a result, an error occurs in the distance measurement result. Can be effectively prevented. When the exposure for focus detection is changed to an exposure brighter than the proper exposure, the through image displayed at the time of focus detection may be bright. In such a case, You may control so that brightness may become dark.

  Then, when the focus lens 32 is driven to the in-focus position, the process proceeds to step S118, the in-focus display is performed, and then the process proceeds to step S119 to perform in-focus lock (processing for inhibiting the drive of the focus lens 32). Be The in-focus display in step S118 is performed by, for example, the electronic viewfinder 26. When the in-focus display is performed, a display may be performed to notify the user that the in-focus operation has been performed by the phase difference detection method.

  As described above, in the present embodiment, when it is determined that the reliability of the defocus amount calculated before the shutter release button is half-pressed is “high” or “medium”, exposure control for focus detection is performed. The drive amount of the focus lens 32 is calculated based on the defocus amount calculated before the shutter release button is half-pressed, and the focus lens 32 is driven. Then, after driving of the focus lens 32 is started, exposure control for focus detection is started, whereby exposure control for focus detection is repeated until the focus lens 32 is driven to the in-focus position. The lens drive is performed based on the defocus amount calculated under the exposure condition changed by the exposure control for focus detection.

  If it is determined in steps S106 to S108 that the reliability of the defocus amount calculated before the half depression of the shutter release button is not "high" or "medium", the process proceeds to step S109. In step S109, the camera control unit 21 determines whether the output levels of the focus detection pixels 222a and 222b are within the range of a predetermined output level. For example, when the output level of the focus detection pixels 222a and 222b is within the range of the output level suitable for focus detection, the camera control unit 21 determines that the output level of the focus detection pixels 222a and 222b is a predetermined output level. It can be determined that it is within the range of If it is determined that the output level of the focus detection pixels 222a and 222b is within the range of the predetermined output level, the process proceeds to step S113, while the output level of the focus detection pixels 222a and 222b is the predetermined output level. If it is determined that it is not within the range, the process proceeds to step S110 to perform exposure control for focus detection.

  In step S110, as in the case of step S117 described above, the camera control unit 21 starts exposure control for focus detection. Then, in step S111, the camera control unit 21 determines whether the reliability of the defocus amount calculated under the exposure condition changed by the exposure control for focus detection is “high” or “medium”. To be done. If it is determined that the reliability of the defocus amount calculated under the exposure condition changed by the exposure control for focus detection is "high" or "medium", the process proceeds to step S114, while the focus detection If it is determined that the reliability of the defocus amount calculated under the exposure condition changed by the exposure control is not "high" or "medium", the process proceeds to step S112.

  In step S112, the camera control unit 21 determines whether the output level of the focus detection pixels 222a and 222b after the start of the exposure control for focus detection is within the range of a predetermined output level. . If it is determined that the output levels of the focus detection pixels 222a and 222b are within the predetermined range, the process proceeds to step S113, and the output levels of the focus detection pixels 222a and 222b are not within the range of the predetermined output level. If it is determined, the process returns to step S111, and exposure control for focus detection and the focus in steps S111 and S112 until the output levels of the focus detection pixels 222a and 222b fall within the predetermined output level range. The determination of the reliability of the defocus amount calculated under the exposure condition changed by the exposure control for detection is repeatedly performed.

  In step S113, the camera control unit 21 performs a scan operation execution process for executing a scan operation. Here, with the scan operation, while the focus lens drive motor 36 scans and drives the focus lens 32, the camera control unit 21 determines the calculation of the defocus amount by the phase difference detection method and the calculation of the focus evaluation value. At the same time, the detection of the in-focus position by the phase difference detection method and the detection of the in-focus position by the contrast detection method are simultaneously performed at predetermined intervals. In the following, the scan operation execution process according to the present embodiment will be described with reference to FIG. FIG. 10 is a flowchart showing a scan operation execution process according to the present embodiment.

  First, in step S201, the camera control unit 21 performs processing for starting a scanning operation. Specifically, the camera control unit 21 sends a scan drive start command to the lens control unit 37, and the lens control unit 37 drives the focus lens drive motor 36 based on the command from the camera control unit 21 to perform focusing. The lens 32 is scan driven along the optical axis L1. The direction in which the scan drive is performed is not particularly limited, and the scan drive of the focus lens 32 may be performed from the infinite end to the close end, or even from the close end to the infinity end. Good.

  Then, while driving the focus lens 32, the camera control unit 21 reads out a pair of image data corresponding to the pair of images from the focus detection pixels 222a and 222b of the image sensor 22 at predetermined intervals. While the defocus amount is calculated and the reliability of the calculated defocus amount is evaluated by the phase difference detection method, the pixel output of the imaging pixel 221 of the imaging element 22 is performed at predetermined intervals while driving the focus lens 32. Based on this read out, the focus evaluation value is calculated, and the focus evaluation value at different focus lens positions is acquired, thereby detecting the in-focus position by the contrast detection method.

  In step S202, in order to prevent the exposure from being changed while detecting the in-focus position by the contrast detection method, AE lock (processing to prohibit the change of the exposure condition) is performed. Then, in step S203, as a result of the scan operation being performed by the camera control unit 21, it is determined whether or not the defocus amount has been 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 S206. On the other hand, if the defocus amount can not be calculated, it is determined that the distance measurement is impossible, and the process proceeds to step S204. . In step S203, even when the defocus amount can be calculated, the defocus amount is calculated when the reliability of the calculated defocus amount is evaluated as "low" or "impossible to measure distance". It treats as what was not able to be done, and decides to advance to step S204.

  In step S204, as a result of performing the scan operation, the camera control unit 21 determines whether the in-focus position has been detected by the contrast detection method. If the in-focus position can be detected by the contrast detection method, the process proceeds to step S211. If the in-focus position can not be detected, the process proceeds to step S205.

  In step S205, the camera control unit 21 determines whether the scan operation has been performed on the entire drivable range of the focus lens 32 or not. When the scan operation is not performed for the entire drivable range of the focus lens 32, the process returns to step S203, and the steps S203 to S205 are repeated to perform the scan operation, that is, to drive the focus lens 32 while scanning. The operation of simultaneously executing 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 at predetermined intervals is continued. On the other hand, if execution of the scan operation has been completed for the entire drivable range of the focus lens 32, the process proceeds to step S215.

  When it is determined in step S203 that the defocus amount can be calculated by the phase difference detection method as a result of executing the scan operation, the process proceeds to step S206, and calculation is performed by the phase difference detection method in steps S206 to S210. A focusing operation is performed on the basis of the defocus amount.

  That is, first, in step S206, the camera control unit 21 performs stop processing of the scan operation, and then, in step S207, the camera control unit 21 performs scan operation prohibition processing.

  Then, in step S208, the lens drive amount necessary for driving the focus lens 32 to the in-focus position is calculated from the defocus amount calculated by the phase difference detection method in step S203, and the lens calculated. The 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, the control unit 21 repeatedly calculates the defocus amount by the phase difference detection method while driving the lens drive motor 36 and driving the focus lens 32 to the in-focus position. 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.

  Then, when the drive of the focus lens 32 to the in-focus position is completed, the process proceeds to step S209, the in-focus display is performed, and then the process proceeds to step S210. It takes place. The in-focus display in step S209 is performed by, for example, the electronic viewfinder 26. When the in-focus display is performed, a display may be performed to notify the user that the in-focus operation has been performed by the phase difference detection method.

  If it is determined in step S204 that the in-focus position has been detected by the contrast detection method as a result of performing the scan operation, the process proceeds to step S211, and the contrast detection method is detected in steps S211 to S214. The drive operation of the focus lens 32 is performed based on the in-focus position.

  That is, first, in step S211, the camera control unit 21 performs a process for stopping the scan operation, and then the process proceeds to step S212, and the camera control unit 21 performs a scan operation prohibition process as in step S207 described above. Be

  Then, the process proceeds to step S213, and lens drive processing for driving the focus lens 32 to the in-focus position is performed based on the in-focus position detected by the contrast detection method. When driving the focus lens 32 to the in-focus position based on the detection result by the contrast detection method, focusing by the phase difference detection method is completed until the drive of the focus lens 32 to the in-focus position is completed. It is preferable to prohibit the driving of the focus lens 32 based on the detection result. Thereby, the hunting phenomenon of the focus lens 32 can be suppressed.

  Then, when the drive of the focus lens 32 to the in-focus position is completed, the process proceeds to step S214, the in-focus display is performed, and then the process proceeds to step S210, and the in-focus lock (process for inhibiting the drive of the focus lens 32) It takes place. The in-focus display in step S214 is performed by, for example, the electronic viewfinder 26. When the in-focus display is performed, a display may be performed to notify the user that the in-focus operation has been performed by the contrast detection method.

  In the scan operation of the present embodiment, the above-described steps S203 to S205 are repeatedly performed to calculate the defocus amount by the phase difference detection method while performing scan drive of the focus lens 32, and to combine by the contrast detection method. Detection of the in-focus position is simultaneously performed at predetermined intervals. Then, as a result of repeatedly executing steps S203 to S205 described above, of the phase difference detection method and the contrast detection method, the focus detection result by the detection method in which the defocus amount can be calculated first or the in-focus position can be detected is Processing is performed to drive the focus lens 32 to the in-focus position. Further, as described above, in the scan operation of the present embodiment, after determining whether the defocus amount has been calculated by the phase difference detection method (step S203), the in-focus position can be detected by the contrast detection method. If the defocus amount can be calculated and the in-focus position can be detected at the same time by the phase difference detection method and the contrast detection method by performing the determination (step S204), whether the focus is determined by the phase difference detection method The detection result is adopted in preference to the focus detection result by the contrast detection method.

  On the other hand, if it is determined in step S205 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 S215. In step S215, as a result of performing the scan operation, focus detection can not be performed by any of the phase difference detection method and the contrast detection method, so the scan operation end processing is performed, and then in step S216. The process advances and the in-focus indication is displayed. The out-of-focus indication is performed, for example, by the electronic viewfinder 26.

  Then, the process proceeds to step S217, and the camera control unit 21 determines whether or not the state where the shutter release button is half pressed (the first switch SW1 is turned on) continues. If the shutter release button is half-pressed, the process proceeds to step S218. If the shutter release button is not half-pressed, the process proceeds to step S220.

  If it is determined in step S217 that the shutter release button is half-pressed, the process proceeds to step S218, and the defocus amount can be calculated by the phase difference detection method as in step S203 described above. A determination is made. As a result, when it is determined that the defocus amount has been calculated, the process proceeds to step S219, and after processing for turning off the in-focus display is performed, the process proceeds to step S207, and the phase difference is increased in steps S207 to S210. A focusing operation is performed based on the defocus amount calculated by the detection method. On the other hand, when it is determined that the defocus amount can not be calculated, the process returns to step S217, and while the state where the shutter release button is half-pressed continues, steps S217 and S218 are repeatedly executed. In this case, since the focus lens 32 is stopped, focus detection by the contrast detection method is not performed, and only focus detection by the phase difference detection method is performed.

  On the other hand, when it is determined in step S217 that the shutter release button has not been half-pressed, the process proceeds to step S220, and processing for turning off the in-focus state is performed.

  As described above, the scan operation execution process of step S113 is performed. Then, after the scan operation execution process of step S113 is finished, the operation of the camera 1 is also finished.

  Subsequently, an operation example of the camera 1 according to the present embodiment will be described based on FIG. FIG. 11 is a diagram for explaining an operation example of the camera 1 according to the present embodiment, and illustrates a scene in which the reliability of the defocus amount before the shutter release button is pressed halfway is “high” or “medium”. doing. In FIG. 11, the reliability of the defocus amount evaluated as “high” or “medium” is represented by “o” (the same applies to FIG. 12). Further, in FIG. 11, the horizontal axis indicates time, and illustrates a scene in which the shutter release button is half-pressed at time t6. For example, when the power of the camera 1 is turned on, generation and display of a through image are started (step S101). Thus, as shown in FIG. 11, first, at time t1, accumulation of charges according to incident light is started, and at time t2, transfer of image data according to the amount of accumulated charges is started. Then, at time t3, the transfer of the image data is completed, and the exposure calculation for generating the through image and the calculation of the defocus amount are started (steps S102 and S103). Thus, at time t4, exposure control for through image generation based on the result of the exposure calculation is performed, and at time t5, calculation of the defocus amount and evaluation of the reliability of the defocus amount are performed. Such accumulation of charge, transfer of image data, exposure control for through image generation, calculation of defocus amount, and evaluation of reliability of defocus amount are repeated at predetermined intervals as shown in FIG. It will be.

  When the shutter release button is pressed halfway at time t6 (step S104 = Yes), first, the defocus amount (the defocus amount calculated at time t5) calculated immediately before the shutter release button is pressed halfway It is determined whether the reliability is "high" or "medium" (steps S105 and S106). Here, in the example shown in FIG. 11, since the reliability of the defocus amount (the defocus amount calculated at time t5) calculated immediately before the half depression of the shutter release button is “high” or “medium” ( Step S106 = Yes), calculation of the lens drive amount of the focus lens 32 is started based on the defocus amount (the defocus amount calculated at time t5) calculated immediately before the shutter release button is half-pressed (step S106) S114). As a result, at time t7, the lens driving amount is calculated based on the defocus amount (the defocus amount calculated at time t5) calculated immediately before pressing the shutter release button halfway, and the lens driving amount is calculated based on the calculated lens driving amount. Then, the drive of the focus lens 32 is instructed, and the drive of the focus lens 32 is started (step S115).

  Furthermore, in the present embodiment, since the reliability of the defocus amount (the defocus amount calculated at time t5) calculated immediately before the shutter release button is half pressed is “high” or “medium”, the focus lens 32 is It is determined that the exposure control for focus detection before driving is not necessary, and the drive of the focus lens 32 is started without performing the exposure control for focus detection at time t7 (step S115).

  Further, in the example shown in FIG. 11, since the exposure control for focus detection is not performed until the drive of the focus lens 32 is started (step S116 = No), after the drive of the focus lens 32 is started At time t8, exposure control for focus detection is started (step S117). For example, at time t8, the output level of the focus detection pixels 222a and 222b is the focus based on the luminance in the predetermined area including the focus detection pixel rows 22a to 22c among the photometry results of the exposure calculation obtained at time t4. Exposure conditions such as the light reception sensitivity Sv and the exposure time Tv are changed so as to fall within a predetermined output level range suitable for detection. Further, the exposure condition changed by the exposure control for focus detection at time t8 is reflected in the accumulation of charges started after time t9. Therefore, from time t9, charge accumulation starts under the changed exposure condition at time t8, and at time t11, image data based on the charge accumulated under the changed exposure condition at time t8 is transferred, and at time t12 The defocus amount is calculated based on the image data obtained under the changed exposure condition at time t8. As a result, at time t13, the lens drive amount is calculated based on the defocus amount calculated under the focus detection exposure condition changed at time t8, and the lens drive calculated under the focus detection exposure condition The focus lens 32 is driven based on the amount. Similarly, at times t10, t14 and t15, exposure control for focus detection is repeatedly performed, whereby the output levels of the focus detection pixels 222a and 222b fall within the range of predetermined output levels suitable for focus detection. Be done.

  FIG. 12 is a view for explaining an operation example of the camera 1 according to the present embodiment, in which the reliability of the defocus amount before the shutter release button is pressed halfway is “low” or “distance measurement impossible” It illustrates a certain scene. In FIG. 12, the reliability of the defocus amount evaluated as “low” or “impossible to measure distance” is indicated by “x”. Further, in FIG. 12, the horizontal axis indicates time, and illustrates a scene in which the shutter release button is half-pressed at time t27. In the example shown in FIG. 12, accumulation of charges corresponding to incident light is started at time t21, transfer of image data corresponding to stored charges is started at time t22, and transferred image is performed at time t23. Based on the data, the exposure calculation for generating the through image and the calculation of the defocus amount are started (steps S102 and S103). Thus, at time t24, exposure control for changing the exposure condition is performed based on the calculation result of the exposure calculation for through image generation, and at time t25, calculation of the defocus amount and reliability of the defocus amount Evaluation is performed. In the example illustrated in FIG. 12, such accumulation of charge, transfer of image data, exposure control for through image generation, calculation of defocus amount, and evaluation of reliability of defocus amount are repeatedly performed. The defocus amount is calculated at times t25 and t26 before time t27 at which the shutter release button is pressed halfway.

  When the shutter release button is pressed halfway at time t27 (step S104 = Yes), first, the defocus amount immediately before the shutter release button is pressed halfway, that is, the reliability of the defocus amount calculated at time t26. Is determined (steps S105 and S106). Here, in the example shown in FIG. 12, the reliability of the defocus amount (the defocus amount calculated at time t26) calculated immediately before the shutter release button is half pressed is not “high” or “medium”. (Step S106 = No), the defocus amount calculated immediately before the defocus amount immediately before the shutter release button is half-pressed (the defocus amount calculated at time t26) (the defocus amount calculated at time t25) Reliability) is determined. However, in the example shown in FIG. 12, the reliability of the defocus amount (the defocus amount calculated at time t25) calculated one before the defocus amount immediately before the shutter release button being half pressed is also "high". Or, since it is not "middle" (step S106 = No), the focus lens 32 is driven based on the defocus amount calculated after half-pressing the shutter release button.

  That is, in the example shown in FIG. 12, since the reliability of the defocus amount calculated before pressing the shutter release button halfway is not "high" or "medium", first, the output level of the focus detection pixels 222a and 222b is A determination is made as to whether it is within the range of a predetermined output level (step S109). If the output levels of the focus detection pixels 222a and 222b are not within the predetermined output level range (step S109 = No), at time t28, for focus detection based on the photometry result in the exposure calculation at time t24. Exposure control is started (step S110). Note that exposure control for focus detection is repeatedly performed at predetermined intervals after the start of exposure control for focus detection, and is performed at times t29, t32, and t35 in the example illustrated in FIG.

  The exposure condition set at time t29 is reflected in the charge accumulation started after time t30, and from time t30 charge accumulation is started under the exposure condition set at time t29. Thereby, at time t31, transfer of image data based on the charge stored under the exposure condition set at time t29 is performed, and at time t33 based on the image data obtained under the exposure condition set at time t29. The defocus amount is calculated. In the example shown in FIG. 12, since the reliability of the defocus amount calculated at time t33 is determined to be “high” or “medium” (step S111 = Yes), the output levels of the focus detection pixels 222a and 222b are The drive amount of the focus lens 32 is calculated based on the defocus amount calculated at time t33 regardless of whether it is within the predetermined output level range (step S114). As a result, at time t34, Driving of the focus lens 32 is started (step S116).

  In the example shown in FIG. 12, the reliability of the defocus amount calculated at time t33 is determined to be “high” or “medium”, but for example, the reliability of the defocus amount calculated at time t33 Is not "high" or "medium" (step S111 = No), and it is determined that the output levels of the focus detection pixels 222a and 222b are within the predetermined output level range (step S112 =). Yes), the scan operation will be performed.

  As described above, in the present embodiment, when the reliability of the defocus amount calculated before the shutter release button is half-pressed is “high” or “medium”, as shown in FIG. The drive of the focus lens 32 is started based on the defocus amount calculated before half-pressing of. Thus, in the present embodiment, the focus lens 32 is pressed after the shutter release button is pressed halfway as compared to the case where the focus lens 32 is driven based on the defocus amount calculated after the shutter release button is pressed halfway. The time until the drive is driven can be shortened.

  Further, in the present embodiment, as shown in FIG. 11, when the reliability of the defocus amount calculated before the shutter release button is half-pressed is “high” or “medium”, the focus lens 32 is driven. It is determined that the previous exposure control for focus detection is unnecessary, and the drive of the focus lens 32 is started without performing the exposure control for focus detection. Thus, after the shutter release button is pressed halfway, exposure control for focus detection is performed until drive of the focus lens 32 is started, and the focus detection pixel 222a is exposed under the exposure condition changed by the exposure control for focus detection. , 222b, and the series of processing time for calculating the defocus amount based on the acquired image data can be omitted. Therefore, compared to the case where exposure control for focus adjustment is performed before driving the focus lens 32, the time from when the shutter release button is pressed halfway to when the focus lens 32 is driven can be further shortened. it can.

  Furthermore, in the present embodiment, the exposure for through image generation is performed so that the output levels of the focus detection pixels 222a and 222b become the range of the predetermined output level suitable for focus detection after the drive of the focus lens 32 is started. The condition is changed to the exposure condition for focus detection, and thereafter, the exposure control for focus detection is repeated. As a result, in the present embodiment, the S / N of the outputs of the focus detection pixels 222a and 222b can be improved, and as a result, the variation in the defocus amount can be reduced and the calculation accuracy of the defocus amount can be improved. .

  The embodiments described above are described to facilitate the understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents that fall within the technical scope of the present invention.

  For example, in the embodiment described above, although the lens drive amount of the focus lens 32 is calculated after the shutter release button is pressed halfway, the lens drive amount is calculated before the shutter release button is pressed halfway. It is good also as composition to keep. As a result, since the time for calculating the lens drive amount of the focus lens 32 can be omitted after the shutter release button is pressed halfway, the process until the focus lens 32 is driven after the shutter release button is pressed halfway The time can be further shortened. Even when the drive amount of the focus lens 32 is calculated before the shutter release button is pressed halfway, the drive of the focus lens 32 before the shutter release button is pressed halfway is prohibited. .

  In the above-described embodiment, the reliability of the defocus amount calculated before the shutter release button is pressed halfway is judged in order from the newly calculated defocus amount, and the reliability is “high” or “medium”. The lens drive amount is calculated on the basis of the defocus amount which is “”. However, the present invention is not limited to this configuration. For example, among the defocus amounts calculated before half depression of the shutter release button The lens drive amount may be calculated based on the defocus amount with the highest degree of performance.

  Furthermore, in the embodiment described above, whether or not to perform exposure control for focus detection based on the defocus amount calculated before the shutter release button is pressed halfway when the shutter release button is pressed halfway For example, when a button for activating the focus adjustment of the optical system is provided separately from the shutter release button, for example, before the button for activating the focus adjustment is pressed. The defocus amount is calculated from the above, and when the button for activating focus adjustment is pressed, for focus detection based on the defocus amount calculated before the button for activating focus adjustment is pressed. It may be determined whether or not to perform the exposure control.

  In addition, in the above-described embodiment, the reliability of the defocus amount calculated before the defocus amount immediately before the half depression of the shutter release button is retroactively determined by a predetermined number, but this configuration For example, the reliability of the defocus amount calculated up to a predetermined time (for example, 0.1 seconds) before the defocus amount immediately before the shutter release button being half-pressed is determined retroactively. It is good also as composition.

  In the embodiment described above, the focus detection pixels 222a and 222b of the image sensor 22 illustrate the configuration for detecting the focus state by the phase difference detection method, but the present invention is not limited to this configuration. A focus detection module for detecting a focus state by a method may be provided independently of the imaging device 22.

  Furthermore, in steps S109 and S112 in the above-described embodiment, the scan operation is performed when the output levels of the focus detection pixels 222a and 222b fall within the range of a predetermined output level. For example, the output levels of the focus detection pixels 222a and 222b fall within the range of a predetermined output level suitable for focus detection by the phase difference detection method, and the output level of the imaging pixel 221 is by the contrast detection method. The scanning operation may be performed when the predetermined output level range suitable for focus detection is reached.

  The camera 1 according to 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 mobile phones. May be

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 24 memory 28 operation part 3 lens barrel 32 focus lens 36 focus lens drive motor 37: Lens control unit

Claims (8)

An imaging unit that captures an image by an optical system having a focusing optical system and outputs a signal;
A detection unit that detects an in-focus position of the focusing optical system at which an image by the optical system focuses on the imaging unit based on a signal output from the imaging unit;
A position control unit that controls the position of the focusing optical system;
And an operation unit operated to control the position of the focusing optical system to the in-focus position by the position control unit.
The position control unit is configured to move the focusing optical system based on the in-focus position detected by the detection unit after the movement of the focusing optical system is started when the operation unit is operated. An imaging device that controls the position of a focusing optical system. In the imaging device according to claim 1,
When the operation unit is operated, the position control unit starts moving the focusing optical system to the in-focus position detected by the detection unit until the operation unit is operated, and the focus adjustment optical system An imaging apparatus that controls the position of the focusing optical system based on the in-focus position detected by the detection unit from when the system is started to move to the in-focus position. In the imaging device according to claim 1 or 2,
An imaging unit that captures an image by an optical system having a focusing optical system and outputs a signal;
The detection unit detects an amount of deviation between the in-focus position of the focusing optical system and the focusing optical system based on the signal output from the imaging unit.
The image pickup apparatus, wherein the position control unit controls the position of the focusing optical system based on the displacement amount detected by the detection unit. In the imaging device according to claim 3,
When the displacement amount detected by the detection unit is reliable before the operation unit is operated, the position control unit may perform the displacement control based on the displacement amount detected before the operation unit is operated. An imaging device that controls the position of a focusing optical system. In the imaging device according to claim 3 or 4,
If the displacement amount detected by the detection unit is not reliable before the operation unit is operated, the position control unit starts moving the focusing optical system after the operation unit is operated. An imaging device that controls the position of the focusing optical system based on the amount of displacement detected by the detection unit until then. In the imaging device according to any one of claims 3 to 5,
The position control unit is not reliable in the displacement amount detected by the detection unit until the operation unit is operated, and the magnitude of the signal output from the imaging unit is within a predetermined range. An imaging device for moving the focusing optical system to detect a focusing position by the detection unit. The imaging device according to any one of claims 1 to 6.
Exposure control for detecting the in-focus position by the detection unit from when the movement of the focusing optical system is started by the position control unit when the operation unit is operated to when the movement to the in-focus position is performed And an exposure control unit that performs the image processing. In the imaging device according to claim 7,
A display unit configured to display an image based on the signal output from the imaging unit;
The exposure control unit performs exposure control for capturing an image to be displayed on the display unit until the operation unit is operated, and the movement of the focusing optical system is started by the position control unit. An imaging apparatus that performs exposure control for detecting the in-focus position by the detection unit before moving to the in-focus position.

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