JP5862087B2 - Focus adjustment device and imaging device - Google Patents

Description

  The present invention relates to a focus adjustment device and an imaging device.

  Conventionally, when adjusting the focus of an optical system, in order to improve the focus adjustment accuracy, first, the focus state of the optical system is detected by the phase difference detection method, and the focus is determined based on the detection result by the phase difference detection method. The adjustment lens is driven to the vicinity of the focus position, and then the focus state of the optical system is detected by the contrast detection method in the vicinity of the focus position, and the focus adjustment lens is focused based on the detection result by the contrast detection method. A technique for driving to a position is known (for example, see Patent Document 1).

JP 2006-84545 A

  However, in the prior art, focus detection is first performed by the phase difference detection method, and subsequently focus detection is performed by the contrast detection method, so that there is a problem that it takes time to adjust the focus.

  The problem to be solved by the present invention is to provide a focus adjustment device capable of appropriately adjusting the focus of an optical system.

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

[1] focusing device according to the present invention, detection and imaging unit for outputting the images signals by imaging an image formed by an optical system having a focusing lens, a phase difference of the image signal output from the imaging unit a phase difference detector for a contrast detection unit for detecting the contrast of the image generated from the image signal output from the imaging unit, while moving the focusing lens, detection of the phase difference by the phase difference detection section When the contrast is detected by the contrast detection unit and the phase difference is detected by the phase difference detection unit, the focus adjustment lens is moved based on the detected phase difference, and the focus adjustment lens is driven. after the in a state where the focusing lens is stopped, the case where the detection of by that phase difference in the phase difference detecting unit has failed to be consecutively a predetermined number of times said focusing Les While moving the figure, performs detection of the contrast due to detection and the contrast detection of the phase difference by the phase difference detecting unit, when the phase difference by the phase difference detecting unit can be detected, based on the detected phase difference a control unit for moving the focusing lens, Ru comprising a.
[2] In the invention related to the focus adjustment device, the control unit performs detection of a phase difference by the phase difference detection unit and detection of contrast by the contrast detection unit while moving the focus adjustment lens. When the phase difference cannot be detected by the phase difference detection unit, the focus adjustment lens can be moved based on the contrast detected by the contrast detection unit .
[3] In the invention related to the focus adjustment apparatus, the phase difference detection unit is provided on a light receiving surface of the imaging unit, and is configured to repeatedly detect the phase difference of the image signal during imaging of the imaging unit. be able to.

[4] In the invention according to the focusing device, wherein the control unit is a moving of the focusing lens based on the phase difference, immediately before the focusing lens is stopped, the phase difference detection section If the phase difference could not be detected and the phase difference detection unit could not detect the phase difference a predetermined number of times after the focusing lens was stopped, focusing could not be performed. it can be configured to you determine that.

[5] In the invention according to the focusing device can be configured to include a notification unit for notifying the focus impossible der Rukoto.

[6] the imaging apparatus according to the present invention, Ru with the focusing device.

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

FIG. 1 is a block diagram showing a camera according to the first 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 vicinity of 22a in FIG. FIG. 4 is an enlarged front view showing one of the imaging pixels 221. FIG. 5A is an enlarged front view showing one of the focus detection pixels 222a, and FIG. 5B is an enlarged front view showing one of the focus detection pixels 222b. FIG. 6 is an enlarged cross-sectional view showing one of the imaging pixels 221. FIG. 7A is an enlarged cross-sectional view showing one of the focus detection pixels 222a, and FIG. 7B is an enlarged cross-sectional view showing one of the focus detection pixels 222b. FIG. 8 is a diagram for explaining the sizes of the focus detection pixels 222a and 222b. FIG. 9 is a diagram for explaining the size of each pixel constituting the line sensor provided in the conventional phase difference detection module. 10 is a cross-sectional view taken along line XX of FIG. FIG. 11 is a flowchart illustrating an operation example of the camera according to the present embodiment. FIG. 12 is a flowchart showing the scan operation execution process in step S116.

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

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

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

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

  The specific configuration of the moving mechanism along the optical axis L1 of the focus lens 32 is not particularly limited. For example, a rotating cylinder is rotatably inserted into a fixed cylinder fixed to the lens barrel 3, a helicoid groove (spiral groove) is formed on the inner peripheral surface of the rotating cylinder, and the focus lens 32 is fixed. The end of the lens frame is fitted into the helicoid groove. Then, by rotating the rotary cylinder by the focus lens drive motor 36, the focus lens 32 fixed to the lens frame moves straight along the optical axis L1.

  As described above, the focus lens 32 fixed to the lens frame by rotating the rotary cylinder with respect to the lens barrel 3 moves straight in the direction of the optical axis L1, but the focus lens drive motor 36 as the drive source is the lens. The lens barrel 3 is provided. The focus lens drive motor 36 and the rotary cylinder are connected by a transmission composed of a plurality of gears, for example, and when the drive shaft of the focus lens drive motor 36 is driven to rotate in any one direction, it is transmitted to the rotary cylinder at a predetermined gear ratio. Then, when the rotating cylinder rotates in any one direction, the focus lens 32 fixed to the lens frame moves linearly in any direction of the optical axis L1. When the drive shaft of the focus lens drive motor 36 is rotated in the reverse direction, the plurality of gears constituting the transmission also rotate in the reverse direction, and the focus lens 32 moves straight in the reverse direction of the optical axis L1. .

  The position of the focus lens 32 is detected by the encoder 35. As described above, the position of the focus lens 32 in the optical axis L1 direction correlates with the rotation angle of the rotating cylinder, and can be obtained by detecting the relative rotation angle of the rotating cylinder with respect to the lens barrel 3, for example.

  As the encoder 35 of this embodiment, an encoder that detects the rotation of a rotating disk coupled to the rotational drive of the rotating cylinder with an optical sensor such as a photo interrupter and outputs a pulse signal corresponding to the number of rotations, or a fixed cylinder And the contact point of the brush on the surface of the flexible printed wiring board provided on either one of the rotating cylinders, and the brush contact provided on the other, the amount of movement of the rotating cylinder (in either the rotational direction or the optical axis direction) A device that detects a change in the contact position according to the detection circuit using a detection circuit can be used.

  The focus lens 32 moves in the direction of the optical axis L <b> 1 from the end on the camera body side (also referred to as the closest end) to the end on the subject side (also referred to as the infinity end) by the rotation of the rotating cylinder described above. Can do. Incidentally, the current position information of the focus lens 32 detected by the encoder 35 is sent to the camera control unit 21 to be described later via the lens control unit 37, and the focus lens drive motor 36 calculates the focus calculated based on this information. The driving position of the lens 32 is driven by being sent from the camera control unit 21 via the lens control unit 37.

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

  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 memory 24 that is a recording medium. As the memory 24, any of a removable card type memory and a built-in type memory can be used. An infrared cut filter for cutting infrared light and an optical low-pass filter for preventing image aliasing noise are disposed in front of the imaging surface of the image sensor 22. Details of the structure of the image sensor 22 will be described later.

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

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

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

  The operation unit 28 is a shutter release button or an input switch for the user to set various operation modes of the camera 1, and can switch between an autofocus mode and a manual focus mode. Various modes set by the operation unit 28 are sent to the camera control unit 21, and the operation of the entire camera 1 is controlled by the camera control unit 21. The shutter release button includes a first switch SW1 that is turned on when the button is half-pressed and a second switch SW2 that is turned on when the button is fully pressed.

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

  FIG. 2 is a front view showing the imaging surface of the imaging element 22, and FIG. 3 is a front view schematically showing the arrangement of the focus detection pixels 222a and 222b by enlarging the vicinity of the focus detection pixel row 22a in FIG.

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

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

  FIG. 4 is an enlarged front view showing one of the imaging pixels 221, and FIG. 6 is a cross-sectional view. One imaging pixel 221 includes a micro lens 2211, a photoelectric conversion unit 2212, and a color filter (not shown), and a photoelectric conversion unit is formed on the surface of the semiconductor circuit substrate 2213 of the image sensor 22 as shown in the cross-sectional view of FIG. 2212 is built in and a microlens 2211 is formed on the surface. The photoelectric conversion unit 2212 is configured to receive an imaging light beam that passes through an exit pupil (for example, F1.0) of the photographing optical system by the micro lens 2211, and receives the imaging light beam.

  Further, on the imaging surface of the imaging element 22, five focus detection pixel rows 22a to 22e in which focus detection pixels 222a and 222b are arranged instead of the above-described imaging pixel 221 are provided. As shown in FIG. 3, one focus detection pixel column is configured by a plurality of focus detection pixels 222 a and 222 b being alternately arranged adjacent to each other in a horizontal row. In the present embodiment, the focus detection pixels 222a and 222b are densely arranged without providing a gap at the position of the green pixel G and the blue pixel B of the image pickup pixel 221 arranged in the Bayer array.

  Note that the positions of the focus detection pixel rows 22a to 22e shown in FIG. 2 are not limited to the illustrated positions, and may be any one, two, three, or four locations, and more than six locations. It can also be arranged at the position. FIG. 3 shows an example in which the focus detection pixel array is configured by 16 focus detection pixels 222a and 222b, but the number of focus detection pixels configuring the focus detection pixel array is limited to this example. Is not to be done.

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

  Here, as shown in FIG. 8, the focus detection pixels 222a and 222b are required to have substantially the same size as the imaging pixel 221 because of the structure thereof. Both the width L1 and the lateral width L2 are normally set to a size of about 10 μm or less. On the other hand, in the conventional line sensor (phase difference detection sensor) provided in the phase difference detection module, as shown in FIG. 9, there is no particular limitation on the size thereof, so the size of each pixel 50a of the line sensor 50 is large. In general, the vertical width L3 is set to about several hundred μm, and the horizontal width L4 is set to about several tens μm to several hundred μm. That is, the size of each pixel 50a of the conventional line sensor 50 is several hundreds μm × several tens μm to several hundreds μm, whereas the focus detection pixels 222a and 222b are set to a size of 10 μm square or less. Yes. FIG. 8 is a diagram for explaining the pixel sizes of the focus detection pixels 222a and 222b, and FIG. 9 shows the size of each pixel constituting the line sensor provided in the conventional phase difference detection module. It is a figure for demonstrating this.

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

  In addition, although the photoelectric conversion units 2222a and 2222b of the focus detection pixels 222a and 222b illustrated in FIGS. 5A and 5B have a semicircular shape, the shapes of the photoelectric conversion units 2222a and 2222b are not limited thereto. Other shapes such as an elliptical shape, a rectangular shape, and a polygonal shape can also be used.

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

  FIG. 10 is a cross-sectional view taken along the line XX in FIG. 3. The focus detection pixels 222 a-1, 222 b-1, 222 a-2, and 222 b-2 arranged in the vicinity of the photographing optical axis L 1 are adjacent to each other. It shows that light beams AB1-1, AB2-1, AB1-2, and AB2-2 irradiated from the distance measuring pupils 341 and 342 of the exit pupil 34 are received, respectively. 10 illustrates only the focus detection pixels 222a and 222b that are located in the vicinity of the photographing optical axis L1, but other focus detection pixels other than the focus detection pixels illustrated in FIG. 10 are illustrated. In the same manner, the light beams emitted from the pair of distance measuring pupils 341 and 342 are respectively received.

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

  In FIG. 10, the arrangement direction of the focus detection pixels 222a-1, 222b-1, 222a-2, and 222b-2 coincides with the arrangement direction of the pair of distance measuring pupils 341 and 342.

  Further, as shown in FIG. 10, 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 34 separated from the lenses 2221a-1, 2221b-1, 2221a-2, 2221b-2 by the distance measurement distance D, and the projection shape forms the distance measurement pupils 341, 342.

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

  As shown in FIG. 10, 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 341 and goes to the microlens 2221a-1. A signal corresponding to the intensity of the image to be output is output. Similarly, the photoelectric conversion unit 2222a-2 of the focus detection pixel 222a-2 passes through the distance measuring pupil 341, and the intensity of the image formed on the microlens 2221a-2 by the light beam AB1-2 toward the microlens 2221a-2. The signal corresponding to is output.

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

  Then, a plurality of the above-described two 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 row by the focus detection light fluxes that pass through each of the distance measurement pupil 341 and the distance measurement pupil 342. Data on the distribution is obtained. Then, by applying an image shift detection calculation process such as a correlation calculation process or a phase difference detection process to the intensity distribution data, an image shift amount by a so-called phase difference detection method can be detected.

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

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

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

  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 example of the operation of the camera 1 according to this embodiment will be described with reference to FIG. FIG. 11 is a flowchart illustrating an operation example of the camera 1 according to the present embodiment. The following operation is started, for example, when the camera 1 is turned on.

  First, in step S101, 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). When the first switch SW1 is turned on, the process proceeds to step S102. On the other hand, if the first switch SW1 is not turned on, step S101 is repeated until the first switch SW1 is turned on.

  In step S102, 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 the focus detection pixels 222a and 222b constituting the five focus detection pixel rows 22a to 22e of the image sensor 22. In this case, when a specific focus detection area is selected by a photographer's manual operation, only data from focus detection pixels corresponding to the focus detection area may be read. Then, the camera control unit 21 executes image shift detection calculation processing (correlation calculation processing) based on the read pair of image data, and in the focus detection areas respectively corresponding to the five focus detection pixel rows 22a to 22e. An image shift amount is calculated, and the image shift amount is converted into a defocus amount. In addition, the camera control unit 21 evaluates the reliability of the calculated defocus amount based on the matching degree and contrast of the pair of image data. Note that the calculation of the defocus amount by the phase difference detection method and the evaluation of the reliability of the defocus amount are repeatedly performed at predetermined intervals.

  In step S103, the camera control unit 21 determines whether 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 S104. 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 S116. 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 S116. Let's go ahead. In the present embodiment, for example, when the subject has a low contrast, the subject is an ultra-low brightness subject, or the subject is an ultra-high brightness subject, it is determined that the reliability of the defocus amount is low. .

  In step S104, since the defocus amount has been detected, the camera control unit 21 performs a scanning operation prohibition process. Specifically, the camera control unit 21 sends a scan operation prohibition command to the lens control unit 37, and the scan operation is prohibited. The scan operation will be described later.

  In step S105, the camera control unit 21 calculates the lens driving amount necessary to drive the focus lens 32 to the in-focus position based on the calculated defocus amount, and the calculated lens driving amount. Is sent to the focus lens drive motor 36 via the lens control unit 37. In subsequent step S106, the focus lens driving motor 36 starts driving the focus lens 32 based on the lens driving amount calculated in step S105. In the present embodiment, after the focus lens 32 starts to be driven in step S106, the defocus amount is repeatedly calculated at a predetermined interval, and as a result, a new defocus amount is calculated. The focus lens 32 is driven based on the newly calculated defocus amount.

  In step S107, the camera control unit 21 performs in-focus determination. Specifically, the camera control unit 21 determines whether or not the calculated absolute value of the defocus amount is equal to or smaller than a predetermined value, and when the calculated absolute value of the defocus amount is equal to or smaller than the predetermined value. Determines that the focus state of the optical system is an in-focus state, and proceeds to step S108. On the other hand, if the calculated absolute value of the defocus amount is greater than a predetermined value, the optical system is in focus. It is determined that there is not, and the process waits in step S107. Note that after the defocus amount is calculated, the camera control unit 21 repeatedly calculates the defocus amount while the focus lens 32 is driven toward the in-focus position, and the newly calculated defocus is calculated. If the absolute value of the amount is larger than the predetermined value, it is determined that the subject is not in focus, and the focus determination in step S107 is repeated, and the newly calculated absolute value of the defocus amount is equal to or smaller than the predetermined value. If it is, the focus is determined and the process proceeds to step S108. In the subsequent step S108, focus display is performed. Note that the focus display in step S108 is performed by the electronic viewfinder 26, for example.

  In step S109, the camera control unit 21 determines whether or not the focus lens 32 is stopped. For example, when the driving of the focus lens 32 to the in-focus position is completed and the focus lens 32 is stopped, the process proceeds to step S110, while the focus lens 32 is driven toward the in-focus position. If so, the process waits in step S109.

  In step S110, the camera control unit 21 sets n, which is a predetermined parameter, to 0. In the subsequent step S111, the camera control unit 21 determines whether or not a new defocus amount can be calculated while the focus lens 32 is stopped. In the present embodiment, the defocus amount is repeatedly calculated even when the focus lens 32 is stopped, and the defocus amount can be newly calculated while the focus lens 32 is stopped. In step S105, the lens driving amount is calculated based on the newly calculated defocus amount, and the focus lens 32 is driven to a new in-focus position. On the other hand, if the defocus amount cannot be calculated, the process proceeds to step S112.

  In step S112, the camera control unit 21 adds 1 to the parameter n, and then in the subsequent step S113, the camera control unit 21 determines whether the parameter n is a predetermined number or more (for example, 5 or more). Is done. If it is determined that the parameter n is equal to or greater than the predetermined number, the process proceeds to step S115, and the out-of-focus display is performed. The out-of-focus display is performed by the electronic viewfinder 26, for example.

  On the other hand, if it is determined in step S113 that the parameter n is less than the predetermined number, the process proceeds to step S114 where the shutter release button is half-pressed (the first switch SW1 is turned on) by the camera control unit 21. A determination is made whether or not the state is continuing. If it is determined in step S114 that the first switch SW1 is on, the process returns to step S111 to determine whether or not a new defocus amount has been calculated. On the other hand, in step S114, When it is determined that the first switch SW1 is off, the operation of the camera 1 is terminated.

  As described above, in the present embodiment, after the focus lens 32 is driven to the in-focus position, the focus lens 32 is stopped (step S109 = Yes), and the defocus amount is repeatedly detected and the defocus is performed. As a result of performing the amount detection a predetermined number of times, if the defocus amount cannot be detected once (step S111 = No, step S113 = Yes), out-of-focus display is performed (step S115). On the other hand, when the focus lens 32 is stopped, the calculation of the defocus amount is repeatedly performed, and the defocus amount can be detected before the defocus amount is detected a predetermined number of times (step S111 = Yes). The focus lens 32 is driven based on the newly calculated defocus amount.

  On the other hand, if the defocus amount cannot be calculated in step S103, it is determined that distance measurement is impossible, and the process proceeds to step S116. In step S116, the camera control unit 21 performs a scan operation execution process for executing a scan operation. Here, the scan operation is a predetermined calculation of the defocus amount and the focus evaluation value by the phase difference detection method by the camera control unit 21 while the focus lens 32 is scan-driven by the focus lens drive motor 36. 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. In the following, the scan operation execution process according to the present embodiment will be described with reference to FIG. FIG. 12 is a flowchart showing a scan operation execution process according to the present embodiment.

  First, in step S201, the camera control unit 21 performs a scan operation start process. 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. 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 may be performed from the close end to the infinite 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. 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 the present embodiment, the camera control unit 21 calculates the defocus amount and calculates the focus evaluation value while performing the wobbling drive that causes the focus lens 32 to reciprocate slightly in the optical axis direction before performing the scan drive. And the driving direction of the focus lens 33 in the scan driving can be determined based on the result.

  In step S202, 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, it is determined that distance measurement is possible and the process proceeds to step S205. On the other hand, if the defocus amount cannot be calculated, it is determined that distance measurement is not possible and the process proceeds to step S203. . In step S202, even if the defocus amount can be calculated, if the reliability of the calculated defocus amount is low, the defocus amount cannot be calculated, and the process proceeds to step S203. I will do it.

  In step S203, it is determined whether the in-focus position has been detected by the contrast detection method as a result of the scanning operation performed by the camera control unit 21. If the in-focus position can be detected by the contrast detection method, the process proceeds to step S210. If the in-focus position cannot be detected, the process proceeds to step S204.

  In step S <b> 204, the camera control unit 21 determines whether the scan operation has been performed for 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 S202, and steps S202 to S204 are repeated to perform the scan operation, that is, while the focus lens 32 is scan-driven. 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 S215.

  If it is determined in step S202 that the defocus amount can be calculated by the phase difference detection method in step S202, the process proceeds to step S205. In steps S205 to S209, the calculation is performed by the phase difference detection method. A focusing operation is performed based on the defocus amount.

  That is, first, in step S205, the camera control unit 21 performs a scan operation stop process, and then proceeds to step S206. The camera control unit 21 performs a scan operation prohibition process.

  In step S207, the lens driving amount necessary to drive the focus lens 32 to the in-focus position is calculated from the defocus amount calculated by the phase difference detection method in step S202, and the calculated lens is calculated. The 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.

  Then, when the driving of the focus lens 32 to the in-focus position is completed, the process proceeds to step S208, in-focus display is performed, and in the subsequent step S209, the camera control unit 21 determines that in-focus. The focus display in step S208 is performed by the electronic viewfinder 26, for example. Further, when performing the focus display, a display for notifying the user that the focus operation has been performed by the phase difference detection method may be performed together. Further, when the driving of the focus lens 32 to the in-focus position is completed, the focus lens 32 is stopped.

  As a result of executing the scanning operation, if it is determined in step S203 that the in-focus position has been detected by the contrast detection method, the process proceeds to step S210, and is detected by the contrast detection method in steps S210 to S214. Based on the in-focus position, the focus lens 32 is driven.

  That is, first, in step S210, the camera control unit 21 performs a scan operation stop process, and then proceeds to step S211. As in step S206 described above, the camera control unit 21 performs a scan operation prohibition process. Done.

  Then, the process proceeds to step S212, and a lens driving process 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, the focus 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.

  When the driving of the focus lens 32 to the in-focus position is completed, the process proceeds to step S213, and in-focus display is performed. The in-focus display in step S213 is performed by the electronic viewfinder 26, for example. Further, when performing the in-focus display, a display for notifying the user that the in-focus operation has been performed by the contrast detection method may be performed together. When the driving of the focus lens 32 to the in-focus position is completed, the process proceeds to step S214, and in step S214, the camera control unit 21 determines that the focus is achieved. Note that when the driving of the focus lens 32 to the in-focus position is completed, the focus lens 32 is stopped.

  In the scanning operation of the present embodiment, the above-described steps S202 to S204 are repeatedly executed, so that the focus lens 32 is driven to scan, and the defocus amount is calculated by the phase difference detection method and the contrast detection method is used. The detection of the focal position is simultaneously performed at a predetermined interval. As a result of repeatedly executing steps S202 to S204 described above, the focus detection result obtained by the detection method in which the defocus amount can be calculated or the in-focus position can be detected first among the phase difference detection method and the contrast detection method. The focus lens 32 is used to drive to the in-focus position. Further, as described above, in the scanning operation of this embodiment, after determining whether or not the defocus amount can be calculated by the phase difference detection method (step S202), the in-focus position can be detected by the contrast detection method. If the phase difference detection method and the contrast detection method can calculate the defocus amount and detect the in-focus position at the same time by determining whether or not the focus position has been detected, the focus by the phase difference detection method is determined. 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 S204 that the scan operation has been completed for the entire driveable range of the focus lens 32, the process proceeds to step S215. In step S215, as a result of performing the scanning operation, focus detection could not be performed by any of the phase difference detection method and the contrast detection method, so that the scanning operation end processing is performed, and then in step S216 Advancing and out-of-focus display is performed. The out-of-focus display is performed by the electronic viewfinder 26, for example. In step S217, the camera control unit 21 determines that focusing cannot be performed.

  Then, after the scan operation execution process in step S116 is completed, the process proceeds to step S117, and the camera control unit 21 determines whether or not the camera is in focus based on the focus determination result in the scan operation execution process. Done. In the scan operation execution process, if it is determined that the focus is achieved, the process proceeds to step S110. On the other hand, if it is determined that the focus is not possible, the operation of the camera 1 is terminated.

  As described above, according to the present embodiment, the calculation of the defocus amount by the phase difference detection method and the detection of the in-focus position by the contrast detection method are simultaneously performed, and the imaging optical is obtained by the method in which the focus detection can be performed first. In order to adjust the focus of the system, the focus lens 32 is first driven to the vicinity of the focus position by the phase difference detection method, and then the focus position is detected by the contrast detection method near the focus position. Compared with the technology), the focus adjustment of the photographing optical system can be performed in a short time.

  In the present embodiment, after the focus lens 32 is driven to the in-focus position, the defocus amount is repeatedly detected while the focus lens 32 is stopped, and the defocus amount is detected a predetermined number of times. As a result, when the defocus amount cannot be detected even once, it is determined that the distance measurement is impossible, and the out-of-focus display is performed. On the other hand, when the focus lens 32 is stopped, the defocus amount is repeatedly detected, and if the defocus amount can be detected before the defocus amount is detected a predetermined number of times, it is newly detected. The focus lens 32 is driven based on the defocus amount. Thus, in the present embodiment, after the focus lens 32 is driven to the in-focus position, the defocus amount cannot be detected once due to, for example, composition blur, even though the subject has not moved in the optical axis direction. It is possible to effectively prevent the out-of-focus display from being performed immediately. In particular, in the present embodiment, when the defocus amount is detected after the focus lens 32 is driven to the in-focus position and the defocus amount is detected a predetermined number of times, the newly detected defocus is detected. Since the focus lens 32 can be driven to the in-focus position based on the amount, the subject can be properly focused.

  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, after the focus lens 32 is driven to the in-focus position, the defocus amount is repeatedly detected in a state where the focus lens 32 is stopped. As a result, the defocus amount is determined a predetermined number of times. In the case where it is impossible to detect continuously, it is determined that focusing cannot be performed and the in-focus display is performed. However, the configuration is not limited to this configuration. For example, the focus lens 32 is driven to the focusing position. During this time, the detection of the defocus amount is repeatedly performed. As a result, the detection result of the defocus amount immediately before the focus lens 32 stops becomes impossible to measure the distance, and after the focus lens 32 stops, the defocus amount becomes a predetermined value. A configuration may be adopted in which it is determined that focusing cannot be performed and in-focus display is performed when the detection cannot be performed consecutively.

  In the above-described embodiment, when the defocus amount is newly calculated in step S111 after the focus lens 32 is stopped, the focus lens 32 is driven based on the newly calculated defocus amount. However, the present invention is not limited to this configuration. For example, when a new defocus amount is calculated in step S111, it is determined whether or not the newly calculated defocus amount is equal to or greater than a predetermined value. The focus lens 32 may be driven based on the defocus amount only when the newly calculated defocus amount is equal to or greater than a predetermined value.

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

DESCRIPTION OF SYMBOLS 1 ... Digital camera 2 ... Camera body 21 ... Camera control part 22 ... Imaging device 221 ... Imaging pixel 222a, 222b ... Focus detection pixel 24 ... Memory 28 ... Operation part 3 ... Lens barrel 32 ... Focus lens 36 ... Focus lens drive motor 37 ... Lens control unit

Claims (6)

An imaging unit for outputting the images signals by imaging an image formed by an optical system having a focusing lens,
A phase difference detection unit for detecting a phase difference of the image signal output from the imaging unit;
A contrast detection unit for detecting a contrast of an image generated from the image signal output from the imaging unit;
When the phase difference detection unit detects the phase difference and the contrast detection unit detects the contrast while moving the focus adjustment lens, and the phase difference detection unit detects the phase difference, the detected phase difference is detected. the focusing lens is moved, said after the focusing lens is driven, in a state in which the focusing lens is stopped, detection of by that phase difference in the phase difference detecting unit is predetermined number of times consecutively, based on If the phase difference detection unit detects the phase difference and the contrast detection unit detects the phase difference while moving the focus adjustment lens, the phase difference detection unit can detect the phase difference. , based on the detected phase difference, the focusing lens with that focal point adjuster and a control unit for moving the. The focus adjustment apparatus according to claim 1,
The control unit detects the phase difference by the phase difference detection unit and the contrast by the contrast detection unit while moving the focus adjustment lens, and the phase difference detection unit cannot detect the phase difference. A focus adjustment device that moves the focus adjustment lens based on the contrast detected by the contrast detection unit. The focusing apparatus according to claim 1 or 2,
The phase difference detection unit is provided on a light receiving surface of the imaging unit, and repeatedly detects a phase difference of the image signal during imaging of the imaging unit. In the focus adjustment apparatus according to any one of claims 1 to 3 ,
Wherein the control unit is a moving of the focusing lens based on the phase difference, immediately before the focusing lens is stopped by the phase difference detecting unit to a case can not detect the phase difference, and , after stopping of the focusing lens, wherein when the detection of the phase difference failed to be the predetermined number of times consecutively, the by the phase difference detecting section, to that focus point adjuster considered not focus. The focus adjustment apparatus according to claim 4 .
Focusing device comprising a notifying unit for notifying the focus impossible der Rukoto. The imaging device provided with the focus adjustment apparatus as described in any one of Claims 1-5 .

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