JP5493470B2 - Focus adjustment device and imaging device provided with the same - Google Patents

Description

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

  2. Description of the Related Art Conventionally, as an imaging apparatus such as a digital camera, an imaging apparatus capable of automatic focus adjustment provided with a focus adjustment lens and a focus adjustment apparatus that performs focus adjustment of an optical system by driving the focus adjustment lens. It has been known. In such an imaging apparatus capable of automatic focus adjustment, a technique for performing focus adjustment by tracking a moving subject when the subject to be focused is a moving subject is disclosed (for example, patents). Reference 1).

JP 2000-66086 A

  However, in the related art, when the photographer changes the composition while the focus adjustment device is activated, and the focus detection result changes greatly, the driving of the focus adjustment lens is prohibited. The focus state cannot be satisfactorily adjusted after the composition is changed, such as when the control is performed or the focus state cannot be detected and the focus adjustment lens is not driven. was there.

  The problem to be solved by the present invention is to provide a focus adjustment device and an image pickup apparatus including the focus adjustment device that can adjust the focus state appropriately even when the photographer changes the composition.

  The present invention solves the above problems by the following means. In addition, although the code | symbol corresponding to drawing which shows embodiment of this invention is attached | subjected and demonstrated, this code | symbol is only for making an understanding of invention easy, and is not the meaning which limits invention.

[1] A focus adjusting apparatus according to the invention includes focus detection means (161, 162) for detecting a focus state of an optical system , drive control means (212) for driving and controlling the optical system, and image formation by the optical system. Of these, it is determined that the recognition means (170) for recognizing an image of a specific object and the focus detection means cannot detect the focus state , and the recognition result by the recognition means is determined to be reliable. When the focus control unit detects the focus state by the focus detection unit while driving the optical system by the drive control unit , the recognition is performed when the focus state cannot be detected by the focus detection unit. When it is not determined by the means that the recognition of the image of the specific object is impossible, or when it is not determined that the recognition result by the recognition means is reliable, the drive control means And control means for controlling the serial optical system so as not to drive (170), characterized by having a.

[2] In the invention related to the focus adjusting apparatus, the focus detection means (161, 162) can be configured to detect the focus state of the optical system by a phase difference detection method .

  [3] In the invention related to the focus adjustment apparatus, the control unit (170) determines a criterion for determining the reliability of the recognition result by the recognition unit (170). It can be configured to be higher than a criterion for determining that recognition is impossible.

  [4] In the invention relating to the focus adjusting device, the control means (170) is configured to detect the focus detection means (161) when the recognition means (170) makes it impossible to recognize the image of the specific object. , 162) can be configured to be initialized.

[ 5 ] In the invention related to the focus adjusting apparatus, the control means (170) cannot detect the focus state of the optical system by the focus detection means (161, 162), and the recognition means (170). When the image of the specific object can be recognized, the adjustment by the focus adjustment unit (212) can be prohibited.

[ 6 ] An imaging apparatus according to the present invention includes the focus adjustment apparatus according to the above invention and an imaging means (110) for capturing an image by the optical system.

[ 7 ] In the invention related to the imaging apparatus, when the imaging unit (110) is capable of continuously capturing the image, and the control unit (170) is continuously capturing the image, The adjustment by the adjusting means (212) can be prohibited.

  According to this invention, even when the photographer changes the composition, it is possible to adjust the focus state appropriately.

FIG. 1 is a block diagram showing a single-lens reflex digital camera 1 according to this embodiment. FIG. 2 is a diagram showing the focus detection module shown in FIG. FIG. 3 is a diagram illustrating an arrangement example of a plurality of focus detection areas set in the photographing screen of the photographing optical system. FIG. 4 is a flowchart (part 1) illustrating the operation of the camera 1 according to the first embodiment. FIG. 5 is a flowchart (part 2) illustrating the operation of the camera 1 according to the first embodiment. FIG. 6 is a flowchart showing the operation of the camera 1 according to the second embodiment. FIG. 7 is a flowchart showing the operation of the camera 1 according to the third embodiment.

<< First Embodiment >>
First, a first embodiment of the present invention will be described.
In the following, an embodiment in which the present invention is applied to a single-lens reflex digital camera will be described with reference to the drawings. However, the present invention can also be applied to other imaging devices such as a silver salt film camera.

  FIG. 1 is a block diagram showing a single-lens reflex digital camera 1 according to the present embodiment. The illustration and description of a general configuration of the camera other than the configuration relating to the focus adjustment device and the imaging device of the present invention are partially omitted. To do.

  The single-lens reflex digital camera 1 (hereinafter simply referred to as the camera 1) of the present embodiment includes a camera body 100 and a lens barrel 200, and the camera body 100 and the lens barrel 200 are detachable via a mount portion. Is bound to. In the camera 1 of the present embodiment, the lens barrel 200 is replaceable depending on the purpose of shooting.

  The lens barrel 200 incorporates a photographing optical system including lenses 211, 212, 213 and a diaphragm 220.

  The focus lens 212 is provided so as to be movable along the optical axis L1 of the lens barrel 200, and its position is adjusted by the focus lens drive motor 230 while its position is detected by the encoder 260.

  The specific configuration of the moving mechanism along the optical axis L1 of the focus lens 212 is not particularly limited. For example, a rotating cylinder is rotatably inserted into a fixed cylinder fixed to the lens barrel 200, a helicoid groove (spiral groove) is formed on the inner peripheral surface of the rotating cylinder, and the focus lens 212 is fixed. The end of the lens frame is fitted into the helicoid groove. Then, by rotating the rotating cylinder by the focus lens drive motor 230, the focus lens 212 fixed to the lens frame moves straight along the optical axis L1. The lens barrel 200 is provided with lenses 211 and 213 other than the focus lens 212. Here, the embodiment will be described by taking the focus lens 212 as an example.

  As described above, the focus lens 212 fixed to the lens frame by rotating the rotating cylinder with respect to the lens barrel 200 moves straight in the direction of the optical axis L1, but the focus lens drive motor 230 as the drive source is the lens. The lens barrel 200 is provided. The focus lens drive motor 230 and the rotating cylinder are connected by, for example, a transmission including a plurality of gears. When the drive shaft of the focus lens driving motor 230 is driven to rotate in any one direction, it is transmitted to the rotating cylinder at a predetermined gear ratio. Then, when the rotating cylinder rotates in any one direction, the focus lens 212 fixed to the lens frame moves straight in any direction of the optical axis L1. When the drive shaft of the focus lens drive motor 230 is rotated in the reverse direction, the plurality of gears constituting the transmission also rotate in the reverse direction, and the focus lens 212 moves straight in the reverse direction of the optical axis L1. .

  The position of the focus lens 212 is detected by the encoder 260. As described above, the position of the focus lens 212 in the direction of the optical axis L1 correlates with the rotation angle of the rotating cylinder, and can be obtained, for example, by detecting the relative rotation angle of the rotating cylinder with respect to the lens barrel 200.

  As the encoder 260 of the present 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 212 moves in the direction of the optical axis L1 from the end portion (also referred to as the closest end) on the camera body 100 side to the end portion (also referred to as the infinite end) on the subject side by the rotation of the rotating cylinder described above. Can do. Incidentally, the current position information of the focus lens 212 detected by the encoder 260 is sent to the camera control unit 170 described later via the lens control unit 250. Then, the drive amount Δd of the focus lens 212 calculated based on this information is sent from the lens drive control unit 165 via the lens control unit 250, and based on this, the focus lens drive motor 230 is driven.

  The aperture 220 has an aperture diameter centered on the optical axis L1 in order to limit the amount of light flux that passes through the imaging optical system and reaches the image sensor 110 provided in the camera body 100 and adjusts the amount of blur. It is configured to be adjustable. The adjustment of the aperture diameter by the diaphragm 220 is performed, for example, by sending an appropriate aperture diameter calculated in the automatic exposure mode from the camera control unit 170 via the lens control unit 250. Further, the set aperture diameter is input from the camera control unit 170 to the lens control unit 250 by a manual operation by the operation unit 150 provided in the camera body 100. The aperture diameter of the aperture 220 is detected by an aperture sensor (not shown), and the lens controller 250 recognizes the current aperture diameter.

  On the other hand, the camera body 100 includes a mirror system 120 for guiding the light flux from the subject to the image sensor 110, the finder 135, the photometric sensor 137, and the focus detection module 161. The mirror system 120 includes a quick return mirror 121 that rotates by a predetermined angle between the observation position and the photographing position of the subject around the rotation axis 123, and the quick return mirror 121 that is pivotally supported by the quick return mirror 121. And a sub mirror 122 that rotates in accordance with the rotation. In FIG. 1, a state where the mirror system 120 is at the observation position of the subject is indicated by a solid line, and a state where the mirror system 120 is at the photographing position of the subject is indicated by a two-dot chain line.

  The mirror system 120 is inserted on the optical path of the optical axis L1 in the state where the subject is in the observation position, while rotating so as to retract from the optical path of the optical axis L1 in the state where the subject is in the photographing position.

  The quick return mirror 121 is composed of a half mirror, and in a state where the subject is at the observation position, the quick return mirror 121 reflects a part of the light flux (optical axes L2 and L3) from the subject (optical axis L1). Then, the light is guided to the finder 135 and the photometric sensor 137, and a part of the light beam (optical axis L4) is transmitted and guided to the sub mirror 122. On the other hand, the sub mirror 122 is configured by a total reflection mirror, and guides the light beam (optical axis L4) transmitted through the quick return mirror 121 to the focus detection module 161.

  Therefore, when the mirror system 120 is at the observation position, the light flux (optical axis L1) from the subject is guided to the finder 135, the photometric sensor 137, and the focus detection module 161, and the subject is observed by the photographer and exposure calculation is performed. And the focus adjustment state of the focus lens 212 is detected. When the photographer fully presses a release button (not shown), the mirror system 120 is rotated to the photographing position, and all the light flux (optical axis L1) from the subject is guided to the image sensor 110, and the photographed image data is illustrated. Do not save to memory.

  The light flux from the subject reflected by the quick return mirror 121 forms an image on a focusing screen 131 disposed on a surface optically equivalent to the image sensor 110 and can be observed through the pentaprism 133 and the eyepiece lens 134. It has become. At this time, the transmissive liquid crystal display 132 superimposes and displays a focus detection area mark on the subject image on the focusing screen 131 and relates to shooting such as the shutter speed, aperture value, and number of shots in an area outside the subject image. Display information. As a result, the photographer can observe the subject, its background, and photographing related information through the finder 135 in the photographing preparation state.

  The photometric sensor 137 is composed of a two-dimensional color CCD image sensor or the like, and divides the photographing screen into a plurality of regions and outputs a photometric signal corresponding to the luminance of each region in order to calculate an exposure value at the time of photographing. The photometric sensor 137 also serves as an image sensor for recognizing a subject, converts a subject image formed on the focusing screen 131 by a photographing optical system into an electrical signal, and outputs an image signal. A signal detected by the photometric sensor 137 is output to the camera control unit 170 and used for automatic exposure control and subject recognition processing.

  The focus detection module 161 is a focus detection element for executing automatic focusing control by a phase difference detection method using subject light, and the imaging surface of the imaging element 110 of the light beam (optical axis L4) reflected by the sub-mirror 122. It is fixed at an optically equivalent position.

  FIG. 2 is a diagram illustrating a configuration example of the focus detection module 161 illustrated in FIG. The focus detection module 161 of this embodiment includes a condenser lens 161a, a diaphragm mask 161b in which a pair of openings are formed, a pair of re-imaging lenses 161c, and a pair of line sensors 161d, and the exit pupils of the focus lens 212 are different. The focus adjustment state is detected by obtaining a phase shift of a pair of image signals obtained by receiving a pair of light beams passing through the pair of regions by a line sensor 161d by a known correlation calculation.

  As shown in FIG. 2, when the subject P is imaged on the equivalent surface (scheduled imaging surface) 161e of the image sensor 110, a focused state is achieved. However, the focus lens 212 moves in the direction of the optical axis L1, and the result is reached. If the image point shifts from the equivalent surface 161e toward the subject (referred to as a front pin) or shifts toward the camera body 100 (referred to as a rear pin), a focus shift state occurs.

  When the imaging point of the subject P is shifted from the equivalent surface 161e toward the subject, the interval W between the pair of image signals detected by the pair of line sensors 161d becomes shorter than the interval W in the focused state, and vice versa. If the imaging point of the subject image P is shifted to the camera body 100 side, the interval W between the pair of image signals detected by the pair of line sensors 161d becomes longer than the interval W in the focused state.

  That is, in the in-focus state, the image signals detected by the pair of line sensors 161d overlap with the center of the line sensor, but in the out-of-focus state, each image signal is shifted from the center of the line sensor, that is, the phase difference is increased. Therefore, focusing is performed by moving the focus lens 212 by an amount corresponding to the phase difference (deviation amount).

  Here, FIG. 3 shows an arrangement example of a plurality of focus detection areas set in the photographing screen 50 of the photographing optical system. As shown in FIG. 3, a plurality of focus detection areas AFP are set in the shooting screen 50 of the shooting optical system. In this embodiment, the focus detection module 161 corresponds to each focus detection area AFP. A plurality of line sensors 161d are provided so that an image signal in each focus detection area AFP can be acquired. In this embodiment, as indicated by AFP1 to AFP31 in FIG. 3, 31 focus detection areas AFP are provided, and each position corresponds to a predetermined position in the imaging range of the image sensor 110. The number and arrangement of the focus detection areas AFP are not limited to the mode shown in FIG.

  Returning to FIG. 1, the AF-CCD control unit 162 controls the gain and accumulation time of the line sensor 161 d of the focus detection module 161 in the autofocus mode, and a plurality of pairs of line sensors provided in the focus detection module 161. The image signal detected at 161d is read in correspondence with each focus detection area AFP and output to the defocus calculation unit 163.

  The defocus calculation unit 163 converts the shift amount of the image signal corresponding to each focus detection area AFP sent from the AF-CCD control unit 162 into a defocus amount, and outputs this to the lens drive amount calculation unit 164. .

  Based on the defocus amount sent from the defocus calculation unit 163, the lens drive amount calculation unit 164 calculates a lens drive amount Δd corresponding to the defocus amount, and outputs this to the lens drive control unit 165. .

  Based on the lens drive amount Δd sent from the lens drive amount calculation unit 164, the lens drive control unit 165 sends a drive command to the focus lens drive motor 230 via the lens control unit 250, and the lens drive amount Δd. Only the focus lens 212 is moved.

  The image sensor 110 is provided on the optical axis L1 of the light beam from the subject of the camera body 100 and at a position that is a planned focal plane of the photographing optical system including the lenses 211, 212, and 213, and a shutter 111 is provided on the front surface thereof. Is provided. The image sensor 110 is a two-dimensional array of a plurality of photoelectric conversion elements, and can be constituted by a two-dimensional CCD image sensor, a MOS sensor, a CID, or the like. The electrical image signal photoelectrically converted by the image sensor 110 is subjected to image processing by the camera control unit 170 and then stored in a memory (not shown). Note that the memory for storing the photographed image can be constituted by a built-in memory or a card-type memory.

  The operation unit 150 includes a shutter release button and an input switch for the photographer to set various operation modes of the camera 1, and selects a continuous shooting mode, switching between an automatic exposure mode / manual exposure mode, Switching between autofocus mode / manual focus mode and setting of a subject recognition mode for recognizing a specific subject can be performed even in the autofocus mode. The shutter release button switch 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. The shutter release button switches SW1 and SW2 and various modes set by the operation unit 150 are transmitted to the camera control unit 170.

  The camera body 100 is provided with a camera control unit 170. The camera control unit 170 includes a microprocessor and peripheral components such as a memory, and is electrically connected to the lens control unit 250. The lens control unit 250 receives lens information including information on the focus adjustment range of the lens barrel 200. And information such as a defocus amount and an aperture control signal is transmitted to the lens control unit 250. The camera control unit 170 reads out image information from the image sensor 110 as described above, performs predetermined information processing as necessary, and outputs the information to a memory (not shown). Furthermore, when the subject recognition mode is selected by the operation unit 150, the camera control unit 170 receives an image signal from the photometric sensor 137 and exists in the shooting screen 50 based on the received image signal. Subject recognition processing for detecting a specific subject is performed. In addition to these, the camera control unit 170 controls the entire camera 1 such as correction of captured image information and detection of a focus adjustment state and an aperture adjustment state of the lens barrel 200.

  Next, an operation example of the camera 1 according to this embodiment will be described. 4 and 5 are flowcharts showing the operation of the camera 1 according to the present embodiment. Hereinafter, a case where the subject recognition mode is selected via the operation unit 150 will be described as an example.

  First, in step S101, the camera control unit 170 determines whether the photographer has pressed the shutter release button halfway (the first switch SW1 is turned on). If the first switch SW1 is turned on, the process proceeds to step S102. If the first switch SW1 is not turned on, the process waits in step S101.

  In step S102, the AF-CCD control unit 162 adjusts the gain of the line sensor 161d of the focus detection module 161, and charges are accumulated by the line sensor 161d.

  In step S103, the camera control unit 170 receives an image signal for subject recognition from the photometric sensor 137, and performs subject recognition processing. The subject recognition method is not particularly limited and may be a known method. For example, template matching is performed using a template image of a person's face, and the person's face is selected from the shooting screen 50 of the shooting optical system. There is a method of recognizing and detecting a specific subject.

  In step S104, the AF-CCD control unit 162 reads out the signal information accumulated by the line sensor 161d in correspondence with each focus detection area AFP set in the imaging screen 50, and outputs it to the defocus calculation unit 163. .

  In step S105, the defocus calculation unit 163 calculates an image shift amount by the phase difference detection method for each focus detection area AFP set in the shooting screen 50 of the shooting optical system, and defocuses each focus detection area. A focus amount df is calculated. The calculated defocus amount df is output to the camera control unit 170 and the lens drive amount calculation unit 164.

  In step S106, the camera control unit 170 determines whether or not the focus state can be detected from the defocus amount calculation result in step S105. Here, the determination of whether or not the focus state can be detected is performed based on, for example, the following criteria. That is, for example, when the subject existing in the shooting screen 50 has low contrast, the reliability between the pair of data based on the sensor signals detected by the pair of line sensors 161d is lowered, and as a result The focus adjustment accuracy will be reduced. Therefore, in this embodiment, in such a case, it is determined that the focus state cannot be detected, and the process proceeds to step S107. On the other hand, in other cases, it is determined that the focus state can be detected, and the process proceeds to step S108.

  In step S107, a so-called scan operation (search drive) is performed. Specifically, first, the camera control unit 170 sends a drive command to the focus lens drive motor 230 via the lens control unit 250, and the focus lens 212 is moved. Note that the amount of movement of the focus lens 212 at this time may be a predetermined amount. Next, at the lens position after the focus lens 212 is moved, charges are accumulated by the line sensor 161d in the same manner as in step S102, and the signal information accumulated in the line sensor 161d is accumulated in the same manner as in steps S104 and S105. The readout and the defocus amount df are calculated, and it is determined whether or not the focus state can be detected as in step S106. In the scanning operation in step S107, the focus lens 212 is moved, the electric charge is accumulated by the line sensor 161d, the accumulated signal information is read, and the defocus amount df is calculated until it is determined that the focus state can be detected. The determination of whether or not the focus state can be detected is repeatedly executed. If it is determined that the focus state can be detected, the process returns to step S102. As a result of the scanning operation in step S107, the lens position of the focus lens 212 has moved to the end of the driving range (the near end or the infinity end) without determining that the focus state can be detected. Is determined, the out-of-focus process is performed, and the operation end process according to the present embodiment is performed. Note that the out-of-focus processing includes, for example, stopping the focus lens 212 and displaying a warning to notify the user that the in-focus position could not be detected.

  On the other hand, if it is determined in step S106 that the focus state can be detected, the process proceeds to step S108. In step S108, each focus detection area AFP set in the shooting screen 50 based on the defocus amount df calculated by the defocus calculation unit 163 by the camera control unit 170 and the result of the subject recognition process in step S103. Of these, processing for determining a focus detection area AFP to be used for focus adjustment is performed. In the present embodiment, among the focus detection areas AFP in which the specific subject is detected by the subject recognition process in step S103, an appropriate area as the focus detection area for use in focus adjustment (for example, the focus detection area in which the specific subject is detected). The area located closest to the AFP) is selected as the focus detection area.

  In step S109, the lens driving amount calculation unit 164 calculates a lens driving amount Δd corresponding to the defocus amount of the focus detection area to be used for the focus adjustment determined in step S108, and this is calculated as a lens driving control unit 165. Output to.

  In step S110, the lens drive control unit 165 sends a drive command to the focus lens drive motor 230 via the lens control unit 250 based on the lens drive amount Δd calculated in step S109. A move is made.

  Then, proceeding to FIG. 5, in step S111 shown in FIG. 5, the camera control unit 170 determines whether or not the photographer has fully pressed the shutter release button (the second switch SW2 is turned on). If the switch SW2 is turned on, the process proceeds to step S125. In step S125, the image sensor 110 captures a subject image, and signals corresponding to the plurality of photoelectric conversion elements provided in the image sensor 110 are transmitted to the sensor control unit 151. Thereafter, step S101 is performed. Return to. On the other hand, if the second switch SW2 is not turned on, the process proceeds to step S112.

  In step S112, it is determined whether or not the first switch SW1 is off. When the first switch SW1 is off, the focus adjustment control is terminated, and the process returns to step S101. On the other hand, if the first switch SW1 remains on, the process proceeds to step S113.

  In steps S113 to S116, similarly to steps S102 to S104 described above, the AF-CCD control unit 162 adjusts the gain of the line sensor 161d, the line sensor 161d accumulates charges (step S113), and the camera control unit 170. , Subject recognition processing (step S114) based on the image signal for subject recognition from the photometric sensor 137, readout of signal information accumulated by the line sensor 161d by the AF-CCD control unit 162 (step S115), defocusing The calculation unit 163 calculates the defocus amount df of each focus detection area (step S116).

  In step S117, the camera control unit 170 determines whether the focus state can be detected from the defocus amount calculation result in step S116, as in step S106. If it is determined that the focus state can be detected, the process proceeds to step S118. On the other hand, if it is determined that the focus state cannot be detected, the process proceeds to step S121.

  In step S118, the camera control unit 170 uses the defocus amount df calculated by the defocus calculation unit 163 and the result of the subject recognition process in step S114 to set each focus detection area AFP set in the shooting screen 50. Of these, processing for determining a focus detection area AFP to be used for focus adjustment is performed. In the present embodiment, in the subject recognition process in step S114, if it is determined that the specific subject remains at the same position as in the previous process, the focus detection area AFP used for focus adjustment is used as the previous focus detection area AFP. The focus detection area AFP selected at the time of processing is used. On the other hand, in the subject recognition processing in step S114, when it is determined that the specific subject has moved in the shooting screen 50 since the previous processing, the focus detection area corresponding to the position after the specific subject has moved is It is selected as a focus detection area for focus adjustment.

  Next, in steps S119 to S120, as in steps S109 to S110, the lens drive amount calculation unit 164 calculates the lens drive amount Δd (step S119), and the lens drive control unit 165 drives the focus lens 212 (steps). After S120) is performed, the process returns to step S111 to determine whether or not the second switch SW2 is turned on.

  On the other hand, if it is determined in step S117 that the focus state cannot be detected, the process proceeds to step S121. In step S121, a specific subject captured in the focus detection area AFP to be used for the focus adjustment determined in step S108 based on the subject recognition processing result in step S114 by the camera control unit 170 is captured by the photographing screen of the photographing optical system. A determination is made as to whether or not it has disappeared from within 50 (whether or not it is unrecognizable within the shooting screen 50). In the present embodiment, the reliability of the subject recognition process in step S114 is equal to or higher than the predetermined level L1, and the specific subject cannot be detected at all in the shooting screen 50, or the reliability of the subject recognition process is the predetermined level L1. The specific subject disappears from the photographing screen 50 when the above-mentioned and the coincidence or similarity between the specific subject recognized in the previous processing and the specific subject recognized in the current processing is low. Can be determined. If it is determined that the specific subject has disappeared, the process proceeds to step S122. On the other hand, when it is determined that the specific subject has not disappeared (when the specific subject can be detected in the shooting screen 50), the process proceeds to step S124.

  In step S122, the camera control unit 170 determines whether or not the reliability of the subject recognition process in the determination that the specific subject has disappeared in step S121 is equal to or higher than a predetermined level L2. In this case, it is assumed that the predetermined level L2 in step S122 is higher than the predetermined level L1 in step S121 (L2> L1). Thereby, the accuracy of the determination of the disappearance of the specific subject in step S121 can be made higher. When the reliability of subject recognition is equal to or higher than the predetermined level L2, a specific subject that has existed in the photographing screen 50 due to a composition change by the photographer or the like while the first switch SW1 is on ( While the release button is half-pressed, it is determined that it has disappeared from the shooting screen 50, and the process proceeds to step S123. On the other hand, when the reliability of subject recognition is less than the predetermined level L2, the process proceeds to step S124.

  In step S123, a so-called scan operation (search drive) is performed as in step S107 described above. If it is determined that the focus state can be detected as a result of the scanning operation, the process returns to step S111.

On the other hand, in step S121, if it is determined that the specific object is not lost, and, if the reliability of the object recognition processing in step S114 is determined to be below a predetermined level L2 in step S122, the step In step S 124, a signal for prohibiting driving of the focus lens 212 is transmitted from the camera control unit 170 to the lens control unit 250. Then, the lens control unit 250 stops the focus lens drive motor 230 based on the signal, thereby stopping the drive of the focus lens 212 and returning to step S111.

  The camera 1 of this embodiment operates as described above.

  In the above-described embodiment, it is determined in step S121 that the specific subject has disappeared, and in step S122, it is determined that the reliability of the subject recognition process is equal to or higher than the predetermined level L2. In this case, in step S123, the control is performed so as to perform the scanning operation. However, the camera control unit 170 is configured to control the lens driving control unit 165 and the lens control unit 250 to send a signal indicating that the scanning operation is permitted. In this way, it is possible to simply set the state in which the scanning operation is possible.

  According to the present embodiment, the focus state cannot be detected in the shooting screen 50, and the specific subject that has been recognized before the previous processing is no longer recognized (when it can be determined that it has disappeared). 2 is configured to perform a scan operation (a focus state detection operation by the focus detection module 161, the AF-CCD control unit 162, and the defocus calculation unit 163, and a focus adjustment operation by moving the focus lens 212) (or scan). Operation is permitted). In particular, in this embodiment, when a specific subject that has been recognized before the previous processing is no longer recognized (when it can be determined that it has disappeared), it is determined that the composition has been changed by the photographer, and thus scanning is performed. The operation is performed (or the scanning operation is permitted). Thus, for example, when the photographer changes the composition while the release button is half-pressed (while the first switch SW1 is on), the responsiveness of the focus lens 212 is improved. As a result, the focus adjustment after the composition change can be performed satisfactorily.

<< Second Embodiment >>
Next, a second embodiment of the present invention will be described. The second embodiment of the present invention is the same as the first embodiment except that the camera 1 of the first embodiment described above operates as described below.

  In the following, the operation of the second embodiment will be described. FIG. 6 is a flowchart for explaining the operation of the camera 1 according to the second embodiment. Note that the flowchart shown in FIG. 6 corresponds to a flowchart following the flowchart shown in FIG. 4 in the first embodiment. In the second embodiment, in the flowchart shown in FIG. 6, it is determined in step S121 that the specific subject has disappeared, and in step S122, the reliability of the subject recognition process is a predetermined level L2. If it is determined as above, the process proceeds to step S123 ′. In step S123 ′, the accumulated data of the line sensor 161d of the focus detection module 161 is initialized, and then the process proceeds to step S123 to perform the scan operation. Except for the execution, the operation is the same as in the first embodiment.

  In the flowchart shown in FIG. 6, the case where the accumulated data of the line sensor 161d of the focus detection module 161 is initialized prior to the scanning operation is illustrated. However, the initialization of the accumulated data of the line sensor 161d is performed by scanning. For example, the configuration may be such that the line sensor 161d is initialized after the scanning operation is performed.

  Also in the second embodiment, as in the first embodiment, control is performed such that the scan operation is performed in step S123. However, the camera control unit 170 scans the lens drive control unit 165 and the lens control unit 250. A mode may be adopted in which a signal indicating that the operation is permitted is sent and the scanning operation is simply enabled.

  According to 2nd Embodiment, in addition to the effect in 1st Embodiment, there exist the following effects. That is, according to the second embodiment, when the focus state cannot be detected, and when the specific subject recognized before the previous process is no longer recognized in the shooting screen 50 (determined as lost). In addition to the scan operation (or permission of the scan operation), the accumulated data of the line sensor 161d of the focus detection module 161 is initialized. Therefore, for example, when the composition is changed by the photographer while the release button is half-pressed, after the composition change, the line sensor 161d quickly obtains luminance information corresponding to the subject after the composition change. It can be performed. That is, it is possible to promptly respond to composition changes. As a result, the focus adjustment after the composition change can be performed better.

<< Third Embodiment >>
Next, a third embodiment of the present invention will be described. The third embodiment of the present invention is the same as the first embodiment except that the camera 1 of the first embodiment described above operates as described below.

  In the following, the operation of the third embodiment will be described. FIG. 7 is a flowchart for explaining the operation of the camera 1 according to the third embodiment. Note that the flowchart shown in FIG. 7 corresponds to a flowchart following the flowchart shown in FIG. 4 in the first embodiment.

  That is, in the third embodiment, the steps S101 to S110 shown in FIG. 4 are executed as in the first embodiment, and the steps S111 to S116 shown in FIG. 7 are executed as in the first embodiment. Executed.

  And in 3rd Embodiment, unlike 1st Embodiment, after calculating the defocus amount df of each focus detection area by the defocus calculating part 163 in step S116, it progresses to step S201 and is shown in FIG. Similarly to step S121, the disappearance determination of the specific subject is performed. That is, in the third embodiment, the disappearance determination of the specific subject is performed before determining whether or not the focus state can be detected (corresponding to step S117 shown in FIG. 5).

  If it is determined in step S201 that the specific subject has disappeared from the shooting screen 50 as a result of the determination of the disappearance of the specific subject, the process proceeds to step S206, and the same as step S122 shown in FIG. In step S201, it is determined whether or not the reliability of the subject recognition process is equal to or higher than the predetermined level L2 in the determination that the specific subject has disappeared. As a result, when it is determined that the reliability of the subject recognition process is equal to or higher than the predetermined level L2, the process proceeds to step S207, the line sensor 161d of the focus detection module 161 is initialized, and the process returns to step S111. On the other hand, if the reliability of the subject recognition process is less than the predetermined level L2, the process proceeds to step S202.

  On the other hand, if it is determined in step S201 that the specific subject has not disappeared from the shooting screen 50 as a result of the determination of the disappearance of the specific subject, the process proceeds to step S202, and the same as step S117 shown in FIG. Then, it is determined whether or not the focus state can be detected. As a result, when it is determined that the focus state can be detected, in steps S203 to S205, the focus detection area for focus adjustment is determined (steps S118 to S120 shown in FIG. 5). After step S203), the lens drive amount Δd is calculated (step S204), and the focus lens 212 is driven by the lens drive controller 165 (step S205), the process returns to step S111, and the second switch SW2 is turned on. Whether or not is to be determined. Alternatively, if it is determined that the focus state cannot be detected, the focus lens 212 is stopped in the same manner as in step S124 shown in FIG. 5, and the process returns to step S111.

  As described above, in the third embodiment, the focus detection unit that detects the focus state of the optical system, the focus adjustment unit that adjusts the focus state of the optical system, and the image of a specific target among the images by the optical system. And a focus adjustment device that initializes the focus detection unit when the recognition unit cannot recognize the image of the specific object.

  And according to such 3rd Embodiment, when the specific subject recognized before the previous process is no longer recognized in the photographing screen 50 (when it can be determined that it has disappeared), the focus detection module 161 The accumulated data of the line sensor 161d is initialized. Therefore, according to the third embodiment, for example, when the composition is changed by the photographer while the release button is half pressed, after the composition change, the line sensor 161d promptly changes the composition. Luminance information corresponding to the subject can be acquired. That is, it is possible to promptly respond to composition changes. As a result, the focus adjustment after the composition change can be performed satisfactorily.

  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 first embodiment and the second embodiment described above, when the continuous shooting mode is selected via the operation unit 150 and continuous shooting is performed, the scanning operation (step S123) Alternatively, the scanning operation may not be permitted, and instead, the driving of the focus lens 212 may be temporarily prohibited. With such a configuration, in situations where it is not desirable to drive the focus lens 212, such as during continuous shooting, while the focus lens 212 can be limited, the shooting can be performed while the release button is pressed halfway. When the composition is changed by a person, the focus adjustment after the composition change can be improved.

DESCRIPTION OF SYMBOLS 1 ... Single-lens reflex digital camera 100 ... Camera body 110 ... Image pick-up element 150 ... Operation part 161 ... Focus detection module 162 ... AF-CCD control part 163 ... Defocus calculation part 164 ... Lens drive amount calculation part 165 ... Lens drive amount control part DESCRIPTION OF SYMBOLS 170 ... Camera control part 200 ... Lens barrel 212 ... Focus lens 230 ... Focus lens drive motor 250 ... Lens control part

Claims (7)

Focus detection means for detecting the focus state of the optical system;
Drive control means for driving and controlling the optical system;
Recognizing means for recognizing an image of a specific object among the images by the optical system;
When the focus state cannot be detected by the focus detection unit, the recognition unit determines that the image of the specific object cannot be recognized , and the recognition result by the recognition unit is reliable. When it is determined that there is a control to detect the focus state by the focus detection means while driving the optical system by the drive control means ,
When it is impossible to detect the focus state by the focus detection unit, the recognition unit does not determine that the image of the specific object is not recognized, or the recognition result by the recognition unit is reliable. And a control means for controlling the optical system not to be driven by the drive control means when it is not determined that there is a focus adjustment device. The focus adjustment apparatus according to claim 1,
The focus adjustment device, wherein the focus detection unit detects a focus state of the optical system by a phase difference detection method. The focusing apparatus according to claim 1 or 2 ,
The control unit sets a determination criterion for determining reliability of a recognition result by the recognition unit to be higher than a determination criterion for determining that the recognition unit cannot recognize an image of a specific target. Focus adjustment device. The focus adjustment apparatus according to any one of claims 1 to 3,
The focus adjustment apparatus, wherein the control means initializes the focus detection means when the recognition means cannot recognize the image of the specific object. In the focus adjustment apparatus of any one of Claim 1 to 4 ,
The control means prohibits adjustment by the focus adjustment means when the focus detection means cannot detect the focus state of the optical system and the recognition means can recognize the image of the specific object. A focusing device characterized by that. A focusing device according to any one of claims 1 to 5, an imaging apparatus characterized by comprising an imaging means for capturing an image formed by the optical system. The imaging device according to claim 6 ,
The imaging means can continuously shoot the image,
The image pickup apparatus, wherein the control unit prohibits adjustment by the focus adjustment unit when the image is being continuously shot.

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