JP6467768B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging apparatus.

  Conventionally, when the shutter release button is pressed halfway, the focus release lens is driven based on the focus state of the optical system, and then the shutter release button is pressed halfway. In the meantime, a technique is known in which the focus state is repeatedly detected at the position of the focus adjustment lens once adjusted, and when the focus state changes, the focus adjustment lens is driven according to the changed focus state (for example, , See Patent Document 1).

JP 2012-11811 A

  However, in the prior art, when the in-focus position cannot be detected, the release operation is uniformly prohibited, so that the subject has low brightness or low contrast, such as during underwater shooting, and the in-focus position In a scene where it is difficult to detect the image, the release operation is prohibited, and there are cases where an image cannot be taken at a timing desired by the photographer.

  The present invention solves the above problems by the following means.

[1] an imaging device according to the present invention includes an imaging unit for outputting a signal by imaging an image formed by an optical system having a focusing lens, the signal based rather of the optical system focus position and the imaging unit shift amount of the imaging surface, and based rather the focus position in the contrast of the image generated on the basis of the signal, a detector for detecting at least one, the detected while changing the position of the focusing lens If the shift amount and the focus position cannot be detected by the unit, and if at least one of the luminance of the subject and the contrast of the subject is low, the contrast detected by the detection unit is changed while changing the position of the focus adjustment lens. Based on the first control for controlling the position of the focus adjustment lens and performing imaging by the imaging unit, and the detection unit while changing the position of the focus adjustment lens If you can not detect more the shift amount and the in-focus position, and a second control and the control unit selectively performs not performing imaging by the imaging unit.
[2] The imaging device includes a storage unit that stores image data based on the signal, and the control unit sets the shift amount and the in-focus position by the detection unit while changing the position of the focus adjustment lens. If it cannot be detected, the position of the focus adjustment lens is controlled based on the contrast detected by the detection unit, and the first control for storing image data in the storage unit and the position of the focus adjustment lens are changed. However, when the detection unit cannot detect the shift amount and the in-focus position, the second control that does not store image data in the storage unit is performed.
[3] In the imaging device, when the detection unit cannot detect the shift amount and the focus position while changing the position of the focus adjustment lens, the detection unit can detect the shift amount and the focus position. An informing unit for informing that there was no information is provided.
[4] The imaging device includes a selection unit capable of selecting the first control and the second control by the control unit.
[5] In the imaging device, when the detection unit cannot detect the shift amount, the control unit causes the detection unit to detect the shift amount and the in-focus position while changing the position of the focus adjustment lens. .
[6] In the imaging device, the control unit performs the first control when the shift amount and the focus position cannot be detected a predetermined number of times or more by the detection unit while changing the position of the focus adjustment lens.
[7] In the imaging apparatus according to the present invention, the control unit controls the position of the focus adjustment lens based on the shift amount or the focus position, and then changes the shift amount or the focus position. The first control is performed.

  According to the present invention, an image can be appropriately captured.

FIG. 1 is a block diagram showing a camera according to the present embodiment. FIG. 2 is a front view showing an imaging surface of the imaging device shown in FIG. FIG. 3 is a front view schematically showing the arrangement of the focus detection pixels 222a and 222b by enlarging the III part of FIG. 4A is an enlarged front view showing one of the imaging pixels 221, FIG. 4B is an enlarged front view showing one of the focus detection pixels 222a, and FIG. FIG. 4D is an enlarged front view showing one of the focus detection pixels 222b, FIG. 4D is a cross-sectional view showing one of the imaging pixels 221 in an enlarged manner, and FIG. 4E is one of the focus detection pixels 222a. FIG. 4F is an enlarged sectional view showing one of the focus detection pixels 222b. FIG. 5 is a cross-sectional view taken along the line VV in FIG. FIG. 6 is a flowchart showing the operation of the camera according to the present embodiment. FIG. 7 is a flowchart showing the second control process of step S116. FIG. 8 is a flowchart showing the first control process of step S117.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a main part configuration diagram showing a digital camera 1 according to an embodiment of the present invention. A digital camera 1 according to the present embodiment (hereinafter simply referred to as a camera 1) includes a camera body 2 and a lens barrel 3, and the camera body 2 and the lens barrel 3 are detachably coupled by a mount unit 4. Yes.

  The lens barrel 3 is an interchangeable lens that can be attached to and detached from the camera body 2. As shown in FIG. 1, the lens barrel 3 includes a photographic optical system including lenses 31, 32, 33 and a diaphragm 34.

  The lens 32 is a focus lens, and can adjust the focal length of the photographing optical system by moving in the direction of the optical axis L1. The focus lens 32 is provided so as to be movable along the optical axis L1 of the lens barrel 3, and its position is adjusted by the focus lens drive motor 36 while its position is detected by the encoder 35.

  Information on the current position of the focus lens 32 detected by the encoder 35 is sent to the camera control unit 21 to be described later via the lens control unit 37, and the focus lens driving motor 36 calculates the focus lens 32 calculated based on this information. Are driven by being sent from the camera control unit 21 via the lens control unit 37.

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

  On the other hand, the camera body 2 is provided with an imaging element 22 that receives the light beam L1 from the photographing optical system on a planned focal plane of the photographing optical system, and a shutter 23 is provided on the front surface thereof. The image sensor 22 is composed of a device such as a CCD or CMOS, converts the received optical signal into an electrical signal, and sends it to the camera control unit 21. The captured image information sent to the camera control unit 21 is sequentially sent to the liquid crystal drive circuit 25 and displayed on the electronic viewfinder (EVF) 26 of the observation optical system, and a release button ( When (not shown) is fully pressed, the photographed image information is recorded in the camera memory 24 which is a recording medium. The camera memory 24 can be either a removable card type memory or a built-in memory.

  The camera body 2 is provided with an observation optical system for observing an image picked up by the image pickup device 22. The observation optical system of the present embodiment includes an electronic viewfinder (EVF) 26 composed of a liquid crystal display element, a liquid crystal driving circuit 25 that drives the electronic viewfinder (EVF) 26, and an eyepiece lens 27. The liquid crystal drive circuit 25 reads the captured image information captured by the image sensor 22 and sent to the camera control unit 21, and drives the electronic viewfinder 26 based on the read image information. Thereby, the user can observe the current captured image through the eyepiece lens 27. Note that, instead of or in addition to the observation optical system using the optical axis L2, a liquid crystal display may be provided on the back surface of the camera body 2, and a photographed image may be displayed on the liquid crystal display.

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

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

  The operation unit 28 is an input switch for the photographer to set various operation modes of the camera 1 such as a shutter release button. The operation unit 28 switches among the shooting modes, the auto focus mode / manual focus mode, and the auto focus mode. The AF-S mode / AF-C mode / AF-A mode can be switched. Various modes set by the operation unit 28 are sent to the camera control unit 21, and the operation of the entire camera 1 is controlled by the camera control unit 21. The shutter release button includes a first switch SW1 that is turned on when the button is half-pressed and a second switch SW2 that is turned on when the button is fully pressed.

  Here, the AF-S mode means that after the shutter release button is half-pressed, the focus lens 32 is driven based on the focus detection result to perform the focus drive, and the position of the focus lens 32 adjusted once is set. This is a mode in which the subject is fixed and photographed at the focus lens position. The AF-S mode is a mode in which focusing accuracy is emphasized, and is selected, for example, when shooting a stationary subject. In the AF-C mode, after the shutter release button is half-pressed, the focus lens 32 is driven based on the focus detection result to perform in-focus driving, and then the shutter release button is half-pressed. While the operation is continued, the focus state is repeatedly detected, and when the focus state changes, the focus lens 32 is driven in accordance with the changed focus state. In the AF-C mode, the image plane position of the subject is predicted based on the temporal change in the image plane position of the moving subject, and the prediction drive that drives the focus lens 32 according to the predicted image plane position of the subject. Is done. As described above, the AF-C mode is a mode in which followability to a subject is emphasized, and is selected, for example, when a subject that is a moving object is photographed. The AF-A mode is a mode in which the AF-S mode and the AF-C mode are automatically switched to adjust the focus of the optical system. The focus is adjusted by the AF-S mode to focus on the subject. After that, when the subject starts to move, the focus adjustment is performed in the AF-C mode.

  In the present embodiment, the shooting mode can be set by operating the operation unit 28. In the present embodiment, a shooting mode including an underwater shooting mode suitable for underwater shooting, an auto shooting mode, and a manual shooting mode can be selected. Information on the shooting mode set by the operation unit 28 is transmitted to the camera control unit 21.

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

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

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

  The unit pixel group 223 may be arranged in a dense hexagonal lattice arrangement other than the dense square lattice shown in the figure. Further, the configuration and arrangement of the color filters are not limited to this, and an arrangement of complementary color filters (green: G, yellow: Ye, magenta: Mg, cyan: Cy) can also be adopted.

  4A is an enlarged front view showing one of the imaging pixels 221 and FIG. 4D is a cross-sectional view. One imaging pixel 221 includes a microlens 2211, a photoelectric conversion unit 2212, and a color filter (not shown), and on the surface of the semiconductor circuit substrate 2213 of the imaging element 22 as shown in the cross-sectional view of FIG. A photoelectric conversion portion 2212 is built, and a microlens 2211 is formed on the surface thereof. The photoelectric conversion unit 2212 is configured to receive an imaging light beam that passes through an exit pupil (for example, F1.0) of the photographing optical system by the micro lens 2211, and receives the imaging light beam.

  In addition, focus detection pixel rows 22a, 22b, and 22c in which focus detection pixels 222a and 222b are arranged in place of the above-described imaging pixels 221 at the center of the image pickup surface of the image pickup element 22 and three positions that are symmetrical from the center. Is provided. As shown in FIG. 3, one focus detection pixel column includes a plurality of focus detection pixels 222 a and 222 b that are alternately arranged adjacent to each other in a horizontal row (22 a, 22 c, 22 c). Yes. In the present embodiment, the focus detection pixels 222a and 222b are densely arranged without providing a gap at the position of the green pixel G and the blue pixel B of the image pickup pixel 221 arranged in the Bayer array.

  Note that the positions of the focus detection pixel rows 22a to 22c shown in FIG. 2 are not limited to the illustrated positions, and may be any one or two, or may be arranged at four or more positions. it can. In actual focus detection, a photographer manually operates the operation unit 28 from among a plurality of focus detection pixel rows 22a to 22c, and selects a desired focus detection pixel row as a focus detection area. You can also.

  4B is an enlarged front view of one of the focus detection pixels 222a, and FIG. 4E is a cross-sectional view of the focus detection pixel 222a. 4C is an enlarged front view showing one of the focus detection pixels 222b, and FIG. 4F is a cross-sectional view of the focus detection pixel 222b. As shown in FIG. 4B, the focus detection pixel 222a includes a micro lens 2221a and a semicircular photoelectric conversion unit 2222a. As shown in the cross-sectional view of FIG. A photoelectric conversion portion 2222a is formed on the surface of the semiconductor circuit substrate 2213, and a micro lens 2221a is formed on the surface. The focus detection pixel 222b includes a micro lens 2221b and a photoelectric conversion unit 2222b as shown in FIG. 4C, and a semiconductor of the image sensor 22 as shown in the cross-sectional view of FIG. A photoelectric conversion unit 2222b is formed on the surface of the circuit board 2213, and a microlens 2221b is formed on the surface. Then, as shown in FIG. 3, these focus detection pixels 222a and 222b are alternately arranged adjacent to each other in a horizontal row, thereby forming focus detection pixel rows 22a to 22c shown in FIG.

  The photoelectric conversion units 2222a and 2222b of the focus detection pixels 222a and 222b have such a shape that the microlenses 2221a and 2221b receive a light beam that passes through a predetermined region (eg, F2.8) of the exit pupil of the photographing optical system. Is done. Further, the focus detection pixels 222a and 222b are not provided with color filters, and their spectral characteristics are the total of the spectral characteristics of a photodiode that performs photoelectric conversion and the spectral characteristics of an infrared cut filter (not shown). ing. However, it may be configured to include one of the same color filters as the imaging pixel 221, for example, a green filter.

  In addition, although the photoelectric conversion units 2222a and 2222b of the focus detection pixels 222a and 222b illustrated in FIGS. 4B and 4C have a semicircular shape, the shape of the photoelectric conversion units 2222a and 2222b is not limited thereto. Other shapes such as an elliptical shape, a rectangular shape, and a polygonal shape can also be used.

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

  FIG. 5 is a cross-sectional view taken along the line V-V in FIG. 3. The focus detection pixels 222 a-1, 222 b-1, 222 a-2, and 222 b-2 that are arranged in the vicinity of the photographing optical axis L 1 and adjacent to each other are It shows that light beams AB1-1, AB2-1, AB1-2, and AB2-2 irradiated from the distance measuring pupils 351 and 352 of the exit pupil 350 are received. In FIG. 5, only the focus detection pixels 222 a and 222 b that are located in the vicinity of the photographing optical axis L <b> 1 are illustrated, but other focus detection pixels other than the focus detection pixels illustrated in FIG. 5 are illustrated. In the same manner, the light beams emitted from the pair of distance measuring pupils 351 and 352 are respectively received.

  Here, the exit pupil 350 is an image set at a distance D in front of the microlenses 2221a and 2221b of the focus detection pixels 222a and 222b arranged on the planned focal plane of the photographing optical system. The distance D is a value uniquely determined according to the curvature and refractive index of the microlens, the distance between the microlens and the photoelectric conversion unit, and the distance D is referred to as a distance measurement pupil distance. The distance measurement pupils 351 and 352 are images of the photoelectric conversion units 2222a and 2222b respectively projected by the micro lenses 2221a and 2221b of the focus detection pixels 222a and 222b.

  In FIG. 5, 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 measuring pupils 351 and 352.

  As shown in FIG. 5, the microlenses 2221a-1, 2221b-1, 2221a-2, and 2221b-2 of the focus detection pixels 222a-1, 222b-1, 222a-2, and 222b-2 are photographic optical systems. Near the planned focal plane. The shapes of the photoelectric conversion units 2222a-1, 2222b-1, 2222a-2, 2222b-2 arranged behind the micro lenses 2221a-1, 2221b-1, 2221a-2, 2221b-2 are the same as the micro lenses 2221a-1, 2221b-1, 2221a-2, 2221b-2. Projected onto the exit pupil 350 that is separated from the lenses 2221 a-1, 2221 b-1, 2221 a-2, and 2221 b-2 by a distance measurement distance D, and the projection shape forms distance measurement pupils 351 and 352.

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

  As shown in FIG. 5, the photoelectric conversion unit 2222a-1 of the focus detection pixel 222a-1 is formed on the microlens 2221a-1 by a light beam AB1-1 that passes through the distance measuring pupil 351 and goes to the microlens 2221a-1. A signal corresponding to the intensity of the image to be output is output. Similarly, the photoelectric conversion unit 2222a-2 of the focus detection pixel 222a-2 passes through the distance measuring pupil 351, and the intensity of the image formed on the microlens 2221a-2 by the light beam AB1-2 toward the microlens 2221a-2. The signal corresponding to is output.

  Further, the photoelectric conversion unit 2222b-1 of the focus detection pixel 222b-1 passes through the distance measuring pupil 352, and the intensity of the image formed on the microlens 2221b-1 by the light beam AB2-1 directed to the microlens 2221b-1. Output the corresponding signal. Similarly, the photoelectric conversion unit 2222b-2 of the focus detection pixel 222b-2 passes through the distance measuring pupil 352, and the intensity of the image formed on the microlens 2221b-2 by the light beam AB2-2 toward the microlens 2221b-2. The signal corresponding to is output.

  Then, a plurality of the above-described two kinds of focus detection pixels 222a and 222b are arranged in a straight line as shown in FIG. Of the pair of images formed on the focus detection pixel array by the focus detection light fluxes passing through each of the distance measurement pupil 351 and the distance measurement pupil 352. Data on the distribution is obtained. The intensity distribution data is subjected to an image shift detection calculation process such as a correlation calculation process or a phase difference detection process to detect an image shift amount by a so-called phase difference detection method.

  Then, a conversion calculation is performed on the obtained image shift amount according to the center-of-gravity interval of the pair of distance measuring pupils, thereby obtaining a current focal plane with respect to the planned focal plane (the focal point corresponding to the position of the microlens array on the planned focal plane) The deviation of the focal plane in the detection area), that is, the defocus amount can be obtained.

  The calculation of the image shift amount, the calculation of the defocus amount, and the focus drive by these phase difference detection methods are executed by the camera control unit 21.

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

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

  Next, an operation example of the camera 1 according to the present embodiment will be described with reference to FIG. In the following, an operation example of the camera 1 when the AF-A mode is set as the autofocus mode will be described. FIG. 6 is a flowchart showing the operation of the camera 1 in the AF-F mode according to this embodiment.

  First, in step S101, the camera control unit 21 starts a defocus amount calculation process using a phase difference detection method. In the present embodiment, the calculation process of the defocus amount by the phase difference detection method is performed as follows. That is, first, the camera control unit 21 reads a pair of image data corresponding to a pair of images from each of the focus detection pixels 222a and 222b constituting the three focus detection pixel rows 22a to 22c of the image sensor 22. Then, the camera control unit 21 performs image shift detection calculation processing (correlation calculation processing) based on the read pair of image data, and images at the focus detection positions corresponding to the three focus detection pixel rows 22a to 22c. The shift amount is calculated, and the image shift amount is converted into a defocus amount. Further, the camera control unit 21 evaluates the reliability of the calculated defocus amount. Note that the reliability of the defocus amount is evaluated based on, for example, the degree of coincidence and contrast of a pair of image data. The defocus amount calculation process using such a phase difference detection method is repeatedly executed at predetermined intervals.

  In step S102, the camera control unit 21 starts a focus evaluation value calculation process. In the present embodiment, the focus evaluation value calculation process reads out the pixel output of the imaging pixel 221 of the imaging device 22, extracts a high-frequency component of the read-out pixel output using a high-frequency transmission filter, integrates it, and focuses on it. This is done by detecting the voltage. The focus evaluation value calculation process is repeatedly executed at predetermined intervals.

  In step S103, the camera control unit 21 determines whether or not the shutter release button provided in the operation unit 28 is half-pressed (the first switch SW1 is turned on). If the first switch SW1 is turned on, the process proceeds to step S104. On the other hand, if the first switch SW1 is not turned on, step S103 is repeated until the first switch SW1 is turned on. That is, the defocus amount calculation process and the focus evaluation value calculation process by the phase difference detection method are repeatedly executed until the first switch SW1 is turned on.

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

  If it is determined in step S104 that the defocus amount has been calculated and it is determined that distance measurement is possible, the process proceeds to step S109, and the focus lens is calculated based on the defocus amount calculated by the phase difference detection method in step S101. A process of driving 32 to the in-focus position is performed. Specifically, the camera control unit 21 calculates and calculates the lens driving amount necessary to drive the focus lens 32 to the in-focus position from the defocus amount calculated by the phase difference detection method. The lens driving amount is sent to the lens driving motor 36 via the lens control unit 37. Then, the lens driving motor 36 drives the focus lens 32 to the in-focus position based on the lens driving amount calculated by the camera control unit 21.

  In the present embodiment, the camera control unit 21 repeatedly calculates the defocus amount by the phase difference detection method while the lens driving motor 36 is driven and the focus lens 32 is driven to the in-focus position. As a result, when a new defocus amount is calculated, the camera control unit 21 drives the focus lens 32 based on the new defocus amount.

  When the driving of the focus lens 32 to the in-focus position is completed, the process proceeds to step S110, and in-focus display is performed. The in-focus display is performed by the electronic viewfinder 26, for example. Further, when performing the focus display in step S110, a display for notifying the user that the focus operation has been performed by the phase difference detection method may be performed together.

  On the other hand, if it is determined in step S104 that the defocus amount cannot be calculated, or if it is determined that the reliability of the calculated defocus amount is low, the process proceeds to step S105. In step S105, the camera control unit 21 performs a scan operation start process. In the scan operation of this embodiment, the focus lens drive motor 36 scans the focus lens 32, and the camera control unit 21 calculates a defocus amount and a focus evaluation value by a phase difference detection method. Thus, 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.

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

  Then, while driving the focus lens 32, the camera control unit 21 reads out a pair of image data corresponding to the pair of images from the focus detection pixels 222a and 222b of the image sensor 22 at predetermined intervals. The phase difference detection method calculates the defocus amount, evaluates the reliability of the calculated defocus amount, and drives the focus lens 32 to drive the pixel output from the imaging pixel 221 of the imaging element 22 at a predetermined interval. Reading is performed, and based on this, a focus evaluation value is calculated, thereby acquiring a focus evaluation value at a different focus lens position, thereby detecting a focus position by a contrast detection method.

  In step S106, it is determined whether or not the defocus amount has been calculated by the phase difference detection method as a result of the scanning operation performed by the camera control unit 21. If the defocus amount can be calculated, 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 S107. In step S106, similarly to step S104 described above, even when the defocus amount can be calculated, the defocus amount cannot be calculated if the reliability of the calculated defocus amount is low. It is assumed that the process proceeds to step S107.

  In step S107, the camera control unit 21 determines whether or not the in-focus position has been detected by the contrast detection method as a result of the scanning operation. In the present embodiment, the camera control unit 21 determines the peak position of the focus evaluation value as the in-focus position when the peak size of the focus evaluation value calculated by the contrast detection method is equal to or greater than the predetermined determination value S1. Detect as. If the in-focus position can be detected by the contrast detection method, the process proceeds to step S111. If the in-focus position cannot be detected, the process proceeds to step S108.

  In step S <b> 108, the camera control unit 21 determines whether or not the scan operation has been performed over the entire driveable range of the focus lens 32. If the scan operation is not performed for the entire driveable range of the focus lens 32, the process returns to step S106, and steps S106 to S108 are repeated to perform the scan operation, that is, while the focus lens 32 is driven to scan. 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 continuously performed. On the other hand, if the scan operation has been completed for the entire driveable range of the focus lens 32, the process proceeds to step S113.

  As a result of executing the scanning operation, if it is determined in step S106 that the defocus amount can be calculated by the phase difference detection method, the scanning operation is stopped, and then the process proceeds to step S109. In the same manner as described above, when the focusing operation based on the defocus amount detected by the phase difference detection method is performed and the driving of the focus lens 32 to the in-focus position is completed, the process proceeds to step S110, and the in-focus display is performed. Is called.

  As a result of executing the scanning operation, when it is determined in step S107 that the in-focus position has been detected by the contrast detection method, the scanning operation is stopped, and the process proceeds to step S111, where it is detected by the contrast detection method. A focusing operation based on the focusing position is performed. In other words, in step S111, a focus drive process for driving the focus lens 32 to the focus position (the peak position of the focus evaluation value) detected by the contrast detection method is performed. When the driving of the focus lens 32 to the in-focus position is completed, the process proceeds to step S112, and in-focus display is performed. The in-focus display is performed by the electronic viewfinder 26, for example. Further, when performing in-focus display in step S112, a display for notifying the user that the in-focus operation has been performed by the contrast detection method may be performed together.

  On the other hand, if it is determined in step S108 that the scan operation has been completed for the entire driveable range of the focus lens 32, the process proceeds to step S113. In step S113, 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, and thus the scanning operation end processing is performed. Then, the process proceeds to step S114. Advancing and in-focus indication is performed. The in-focus indication is performed by the electronic viewfinder 26, for example.

  In step S115, it is determined whether the underwater shooting mode is set as the shooting mode. If a shooting mode other than the underwater shooting mode, such as an auto shooting mode or a manual shooting mode, is set, the process proceeds to step S116 and second control processing (details will be described later) is performed. On the other hand, if the underwater shooting mode is set, the process proceeds to step S117, and a first control process (details will be described later) is performed.

  Here, FIG. 7 is a flowchart showing the second control processing of step S116. First, in step S201, the camera control unit 21 determines whether or not the focus state of the optical system is a focused state. For example, when the camera control unit 21 drives the focus lens 32 to the in-focus position based on the defocus amount detected by the phase difference detection method in step S109, or the detection is performed by the contrast detection method in step S111. When the focus lens 32 is driven to the focused position, it is determined that the focus state of the optical system is the focused state, and the process proceeds to step S202. On the other hand, when it is determined in step S108 that the in-focus position cannot be detected, the camera control unit 21 determines that the focus state of the optical system is not the in-focus state, and proceeds to step S205, and in step S205, The release operation is prohibited by the camera control unit 21. As a result, image capturing is prohibited until the release operation is permitted in step S202 described later.

  On the other hand, when it is determined that the focus state of the optical system is the in-focus state (step S201 = Yes), the process proceeds to step S202. In step S202, the release operation is permitted by the camera control unit 21.

  In subsequent step S203, it is determined whether or not the shutter release button has been fully pressed (second switch SW2 is turned on). When the second switch SW2 is turned on, the process proceeds to step S204, and in step S204, the subject image is taken by the camera control unit 21. On the other hand, if the second switch SW2 is not turned on in step S203, the process proceeds to step S207.

  If the release operation is prohibited because it is not in focus (step S201 = No, step S205), the process proceeds to step S206. In step S206, since it is determined that the subject is not in focus, a message indicating that the subject is out of focus is displayed, and then the process proceeds to step S207.

  In step S207, the camera control unit 21 determines whether or not the focus state of the optical system has changed. For example, when the defocus amount that is repeatedly calculated by the camera control unit 21 changes by a predetermined value or more, or when the defocus amount cannot be calculated, or the focus evaluation value that is also repeatedly calculated by the camera control unit 21 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 S103 shown in FIG. 6, and the operation for driving the focus lens 32 to the in-focus position is performed again. On the other hand, if the focus state of the optical system has not changed, the process returns to step S201, and the focus lens 32 is changed until the focus state of the optical system becomes a focused state or the focus state of the optical system changes. Waits while stopped at the current lens position.

  As described above, in the present embodiment, when a shooting mode other than the underwater shooting mode such as the auto shooting mode or the manual shooting mode is set, when it is determined that the focus state of the optical system is not the in-focus state. The release operation is prohibited, and the out-of-focus display is performed. Accordingly, it is possible to effectively prevent an image that is not in focus on the subject from being shot in a shooting mode other than the underwater shooting mode.

  Next, the first control process in step S117 will be described. As shown in FIG. 6, when the underwater shooting mode is selected as the shooting mode in step S115, the process proceeds to step S117, and the first control process is performed.

  FIG. 8 is a flowchart showing the first control process of step S117. As shown in FIG. 8, first, in step S301, as in step S201, it is determined whether or not the focus state of the optical system is a focused state. When it is determined that the focus state of the optical system is the in-focus state, the process proceeds to step S302, and the release operation is permitted by the camera control unit 21. On the other hand, if it is determined that the focus state of the optical system is not the in-focus state, the process proceeds to step S303.

  In step S303, since it is determined that the focus state of the optical system is not the in-focus state, the camera control unit 21 uses the focus lens in the scan operation based on the results of the scan operations in steps S106 to S108 shown in FIG. Within the driving range 32, the lens position at which the focus evaluation value is maximized is detected, and the process of driving the focus lens 32 to the lens position at which the focus evaluation value is maximized is performed. In step S304, the camera control unit 21 displays that the camera is out of focus. In subsequent step S305, the camera control unit 21 permits the release operation.

  After the release operation is permitted in step S302 or step S305, in step S306, it is determined whether the second switch SW2 is turned on as in step S203. When the second switch SW2 is turned on, the process proceeds to step S307, and in step S307, a subject image is taken. On the other hand, if the second switch SW2 is not turned on in step S306, the process proceeds to step S308, and similarly to step S207, it is determined whether or not 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 S103 shown in FIG. 6, and the operation for driving the focus lens 32 to the in-focus position is performed again. If the focus state has not changed, the process returns to step S301. As a result, the focus lens 32 stands by at the current lens position until the focus state of the optical system becomes an in-focus state or the focus state of the optical system changes.

  As described above, when the shooting mode is the underwater shooting mode, when it is determined that the in-focus state is not achieved (step S301 = No), the focus lens 32 is driven to the lens position having the largest focus evaluation value, The release operation is permitted after the out-of-focus display. This makes it difficult to detect the in-focus position by scanning driving when underwater photography, such as when the subject's brightness is low due to deep water depth, or when the subject being photographed is a subject with low contrast, such as fish. Even in this case, since the release operation is permitted at the lens position having the largest focus evaluation value, it is possible to appropriately capture an image at a timing desired by the photographer.

  As described above, in the present embodiment, when the shooting mode is other than the underwater shooting mode, when it is determined that the subject is not in focus, the release operation is prohibited, for example, to focus on the subject. It is possible to effectively prevent an image that has not been taken. On the other hand, when the shooting mode is the underwater shooting mode and the focus lens 32 is determined to be out of focus, the focus lens 32 is driven to the lens position with the largest focus evaluation value, and the in-focus display is performed. When the underwater shooting is permitted, the in-focus position cannot be detected by scan drive, such as when the subject's brightness is low due to the deep water depth or when the contrast of the subject such as fish is low. However, since the release operation is permitted in a state where the focus lens 32 is driven to the lens position where the focus evaluation value is maximized, an image can be appropriately captured at a timing desired by the photographer. As described above, in this embodiment, by controlling the release operation according to the shooting conditions, the photographer can be caused to take an image at an appropriate timing according to the shooting conditions.

  In particular, in the present embodiment, in focus detection by the contrast detection method, the peak position of the focus evaluation value having a peak size equal to or greater than the predetermined determination value S1 is detected as the in-focus position, but the shooting mode is underwater shooting. In the mode, the focus lens 32 is driven to the lens position having the largest focus evaluation value, and the release operation is permitted. Thereby, even if the magnitude of the peak of the focus evaluation value at the lens position where the peak of the focus evaluation value is the highest is less than the determination value S1 in the focus detection of the contrast detection method, the relative viewpoint of the focus evaluation value Since the in-focus position can be detected appropriately, an image in focus on the subject can be suitably captured.

  The embodiment described above is described for facilitating the understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  For example, in the above-described embodiment, the scene in which the AF-A mode is set as the autofocus mode has been described as an example. However, the present invention is not limited to this configuration. For example, the AF-S mode or the AF-C mode is used. Alternatively, the present invention can also be applied to scenes where other modes are set.

  In the above-described embodiment, the configuration in which the first control process is performed when the underwater shooting mode is set as the shooting mode is illustrated. However, the configuration is not limited to this configuration. For example, instead of the underwater shooting mode, Alternatively, the first control process may be performed when the night scene shooting mode is set in addition to the underwater shooting mode. The night view shooting mode may include a night view portrait shooting mode.

  Furthermore, in the above-described embodiment, the configuration in which the first control process is performed when the underwater shooting mode is set as the shooting mode is illustrated. However, the configuration is not limited to this configuration. When the focus state of the optical system cannot be detected continuously more than a predetermined number of times as a result of repeated pressing operations, the subject brightness is less than a predetermined value, or the subject contrast is less than a predetermined value In addition, the first control process may be performed.

  In the above-described embodiment, the configuration is such that the release operation is permitted after the focus lens 32 is driven to the lens position having the largest focus evaluation value when it is determined in the first control process that the focus state is not achieved. Although illustrated, the present invention is not limited to this configuration. For example, a release operation may be permitted while the focus lens 32 is driven to a lens position having the largest focus evaluation value. In this case, it is preferable that the release operation is permitted when the distance from the lens position of the focus lens 32 to the lens position having the largest focus evaluation value becomes a certain distance.

  Furthermore, in the above-described embodiment, the configuration in which the first control process is performed when the underwater shooting mode is selected as the shooting mode is not limited to this configuration. For example, the camera 1 includes a water pressure gauge, The configuration may be such that the first control processing is performed when the water pressure becomes a predetermined value or more, or when a housing for underwater photography is attached.

  In addition, in the above-described embodiment, when the AF-A mode is set as the focus adjustment mode, the second control process is performed when the underwater shooting mode is not set, and the underwater shooting mode is set. In this case, the configuration in which the first control process is performed has been illustrated. For example, when a focus adjustment mode other than the AF-A mode (for example, AF-S mode, AF-C mode) is set, the underwater shooting mode is set. Regardless of whether it is set, the second control process can be performed.

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

DESCRIPTION OF SYMBOLS 1 ... Digital camera 2 ... Camera body 21 ... Camera control part 22 ... Imaging device 28 ... Operation part 3 ... Lens barrel 32 ... Focus lens 36 ... Focus lens drive motor 37 ... Lens control part

Claims (7)

An imaging unit that captures an image by an optical system having a focus adjustment lens and outputs a signal;
Shift amount between the imaging surface of the imaging section based rather focus position of the optical system to the signal, and based rather the focus position in the contrast of the image generated on the basis of the signal, at least one A detection unit to detect;
When the shift amount and the in-focus position cannot be detected by the detection unit while changing the position of the focus adjustment lens, and when at least one of the luminance of the subject and the contrast of the subject is low, the position of the focus adjustment lens is changed. Based on the contrast detected by the detection unit while changing, a first control for controlling the position of the focus adjustment lens to perform imaging by the imaging unit, and the detection unit while changing the position of the focus adjustment lens And a control unit that selectively performs second control in which imaging by the imaging unit is not performed when the shift amount and the in-focus position cannot be detected. The imaging device according to claim 1,
A storage unit for storing image data based on the signal;
If the detection unit cannot detect the shift amount and the in-focus position while changing the position of the focus adjustment lens, the control unit determines the position of the focus adjustment lens based on the contrast detected by the detection unit. The first control for controlling and storing the image data in the storage unit, and when the detection unit cannot detect the shift amount and the in-focus position while changing the position of the focus adjustment lens, the storage unit An imaging apparatus that performs the second control without storing image data. The imaging device according to claim 1 or 2,
When the detection unit cannot detect the shift amount and the in-focus position while changing the position of the focus adjustment lens, the notification unit notifies that the shift amount and the focus position cannot be detected by the detection unit. An imaging apparatus comprising: In the imaging device in any one of Claims 1-3,
An imaging apparatus comprising: a selection unit capable of selecting the first control and the second control by the control unit. In the imaging device according to any one of claims 1 to 4,
When the detection unit cannot detect the shift amount, the control unit causes the detection unit to detect the shift amount and the in-focus position while changing the position of the focus adjustment lens. An imaging apparatus according to any one of claims 1 to 5,
The control unit is configured to perform the first control when the shift amount and the focus position cannot be detected more than a predetermined number of times by the detection unit while changing the position of the focus adjustment lens. The imaging apparatus according to any one of claims 1 to 6,
An image pickup apparatus that performs the first control when the shift amount or the focus position changes after the control unit controls the position of the focus adjustment lens based on the shift amount or the focus position.

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