JP2013257406A - Imaging device and control method for the same as well as lens unit and control method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an interchangeable lens system with an object detection section and an auto-focusing section separately installed at a cameral side and a lens side respectively to perform auto-focusing using a change in a size of an object.SOLUTION: An imaging device with an interchangeable lens unit which has an imaging optical system including a focus lens and controls drive of the focus lens on the basis of information transmitted from the imaging device comprises: imaging means which generates an imaging signal through photoelectric conversion of an object image taken by the imaging optical system with an imaging element; detection means which identifies a region of the specific object image on the basis of the imaging signal and detects a size of the specific object image; acquisition means which acquires a focus signal on the basis of a high-frequency component of the imaging signal corresponding to a focus detection region; and control means which transmits information on the focus signal and the size of the specific object image detected by the detection means to the lens unit mounted on the imaging device.

Description

  The present invention relates to an image pickup apparatus in which a lens unit can be exchanged, and a lens unit attached to the image pickup apparatus.

  As a method of performing focus adjustment with a camera, the sharpness of the screen is detected from the image pickup signal obtained by photoelectrically converting the subject image with an image pickup device or the like, and the focus lens position is set so as to maximize the AF evaluation value. A control method (TVAF method) is known. As the AF evaluation value of the TVAF method, the level of the high-frequency component of the image signal extracted by a band-pass filter in a certain band is generally used. FIG. 2 shows an example of a change in the AF evaluation value of the TVAF method with respect to the focus lens position. When a normal subject image is photographed, the AF evaluation value increases as the focus is adjusted as shown in FIG. 2, and the point where the level is maximum is the in-focus position.

  Patent Document 1 shows an example in which this type of automatic focus adjustment method is used for a video camera in which the lens unit can be replaced. The focus signal is transferred from the video camera body to the lens unit, and control of the automatic focus adjustment is performed by the lens. It is disclosed to have on the unit side. By having auto focus adjustment control on the lens unit side, it is possible to determine the optimum responsiveness etc. for each lens unit no matter what lens unit is attached to the camera, and it is optimal for all detachable lens units Performance can be achieved.

  On the other hand, a specific subject such as a person's face is detected from an image included in the image pickup signal output from the image sensor, and auto-focusing is performed on the detected subject, and auto change is performed using a change in the size of the subject. Some improve focus performance. In Patent Document 2, a distance to a subject is calculated based on the size of a feature area of the subject such as a face, and a temporal change of the subject distance is predicted, so that control is performed to focus on the subject at the time of imaging. It is disclosed.

Japanese Patent Laid-Open No. 9-9130 JP 2008-276214 A

  Here, in Patent Document 2, subject detection and focusing control are performed in the camera. On the other hand, in the interchangeable lens system disclosed in Patent Document 1, the autofocus unit is in the lens unit. Therefore, in Patent Literature 1, focusing control cannot be performed in the camera as in Patent Literature 2, based on the size of the subject detected by the camera unit.

  An object of the present invention is to enable focus control using a change in the size of a subject even in an interchangeable lens system in which a subject detection unit is separated on the camera side and an autofocus unit is separated on the lens side.

  In view of the above problems, the first aspect of the present invention is an imaging apparatus that includes a photographic optical system including a focus lens, and that is detachable from a lens unit that controls driving of the focus lens based on information transmitted from the imaging apparatus. An imaging means for photoelectrically converting an object image obtained by the imaging optical system with an image sensor to generate an imaging signal; a specific object image area is specified based on the imaging signal; and the size of the specific object image Detection means for detecting a focus signal, an acquisition means for acquiring a focus signal based on a high-frequency component of the imaging signal corresponding to a focus detection area, and a size of the specific subject image detected by the focus signal and the detection means And control means for transmitting information on the length to the mounted lens unit.

  According to a second aspect of the present invention, there is provided a lens unit that can be attached to an image pickup apparatus having an image pickup means for generating an image pickup signal, a photographing optical system including a focus lens, a drive means for driving the focus lens, and the image pickup Lens-side control means for receiving information from the apparatus and controlling the drive means based on the information, and the information received from the imaging apparatus is a focus signal based on the imaging signal generated by the imaging means. This is information relating to the size of a specific subject image detected by the imaging apparatus.

  According to the present invention, even in an interchangeable lens system in which the subject detection unit is separated on the camera side and the autofocus unit is separated on the lens side, it is possible to perform focusing control using a change in the size of the subject.

The video camera according to the first embodiment of the present invention The figure explaining a TVAF signal The figure explaining the TVAF frame at the time of subject detection TVAF flowchart of the first embodiment of the present invention The flowchart which shows the process in the micro drive of the 1st Embodiment of this invention. The flowchart which shows the process in the micro drive of the 1st Embodiment of this invention. The figure explaining the micro drive of the 1st Embodiment of this invention The figure explaining the accumulation | storage timing of a CMOS sensor Timing chart of processing of camera microcomputer and lens microcomputer of first embodiment of the present invention Flow chart of mountain climbing drive according to the first embodiment of the present invention Diagram explaining hill-climbing drive Flowchart of camera processing according to the second embodiment of the present invention The flowchart which shows the process in the micro drive of the 2nd Embodiment of this invention. The flowchart which shows the process in the micro drive of the 2nd Embodiment of this invention.

<First Embodiment>
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of an embodiment of the present invention. In the figure, a lens unit 117 is detachably attached to a camera unit 118 to constitute a so-called interchangeable lens system.

  First, the configuration of the photographing optical system in the lens unit 117 that can be attached to the camera unit 118 will be described. The light from the subject passes through the photographing optical system including the first lens group 101, the second lens group 102, the aperture 103, the third lens group 104, and the fourth lens group 105 in the lens unit 117. The image is formed on the image sensor 106 such as a CMOS sensor in the camera unit. The first lens group 101 and the third lens group 104 are fixed. The second lens group 102 is movable in the optical axis direction and has a zooming function. The fourth lens group 105 is movable in the optical axis direction, and has both a focus adjustment function and a competition function for correcting the movement of the focal plane due to zooming (hereinafter referred to as a focus lens). In FIG. 1, each of the lens groups 101 to 105 is illustrated as a single lens, but may be configured from a plurality of lenses.

  The image sensor 106 in the camera unit is a photoelectric conversion element constituted by a CMOS sensor or the like. The subject image formed on the image sensor 106 constituting a part of the image pickup means is photoelectrically converted and amplified to an optimum level by an amplifier 107 constituting a part of the image pickup means, and then processed as a camera signal as an image pickup signal. Input to the circuit 108. The image sensor 106 accumulates charges in synchronization with the V synchronization signal (vertical synchronization signal) output from the signal generation circuit 120.

  The camera signal processing circuit 108 performs various types of image processing on the imaging signal from the amplifier 107 to generate an image signal. A monitor 109 constituted by an LCD or the like displays an image signal from the camera signal processing circuit 108. The recording unit 110 records the image signal from the camera signal processing circuit 108 on a recording medium such as a semiconductor memory.

  The subject detection unit 119 performs a known subject detection process on the image signal output from the camera signal processing circuit 108 to identify a subject area in the shooting screen, and detects a feature amount such as the position and size of the subject. The detection result is transmitted to the camera microcomputer 116. Here, the size of the subject is detected as the number of pixels on the image sensor 106 corresponding to the subject region.

As subject detection processing, many techniques for detecting a face area of a person in a shooting screen are known. Examples of the face detection processing method include the following.
-A method for extracting a skin color region from the gradation color of each pixel represented by image data and detecting a face with a matching degree with a face contour plate prepared in advance-Using known pattern recognition technology, Method for performing face detection by extracting facial feature points such as nose, mouth, etc. In addition, based on instructions from the camera microcomputer 116, subject detection is performed on an image whose size is reduced by thinning out pixels as a detection area from the camera signal processing circuit 108. You may output to the part 119. Further, based on an instruction from the camera microcomputer 116, an image obtained by cutting a part of the shooting screen as a detection area may be output from the camera signal processing circuit 108 to the subject detection unit 119.

  In the present invention, the subject detection processing method is not limited to the method described above, and the subject may not be a human face. Furthermore, the photographer may be provided with a subject designating unit (not shown) for designating a subject, and the subject region may be specified using a known pattern matching technique from the luminance information and color information of the image signal of the designated subject. .

  The TVAF gate 113 passes only the signal of the region used for focus detection out of the output signals of all the pixels from the amplifier 107. The TVAF signal processing circuit 114 extracts a high-frequency component from the signal that has passed through the TVAF gate 113 and generates a TVAF evaluation value signal (focus signal). The TVAF evaluation value signal is output to the camera microcomputer 116. The TVAF evaluation value signal represents the sharpness (contrast state) of the video generated based on the image pickup signal from the image pickup means, but the sharpness changes depending on the focus state of the image pickup optical system. As shown in FIG. 2, the signal represents the focus state of the imaging optical system.

  FIG. 3 shows a TVAF frame (focus detection area) at the time of subject detection. In the figure, a TVAF frame is set for a human face. The camera microcomputer 116 as the camera-side control means controls the operation of the entire camera, and sets the TVAF frame based on a predetermined ratio and the output of the subject detection unit with respect to the imaging screen as shown in FIG. The TVAF gate 113 is controlled. The TVAF evaluation value signal is generated based on an image signal from an area on the image sensor 106 corresponding to the TVAF frame. Further, the camera microcomputer 116 determines the size of the subject area based on the TVAF evaluation value signal acquired from the TVAF signal processing circuit 114 and the number of pixels on the image sensor corresponding to the subject area acquired from the subject detection unit 119. Information is generated and transmitted to the lens microcomputer 115. Since the total number of pixels of the image sensor varies from camera to camera, the camera microcomputer 116 normalizes the number of pixels on the image sensor corresponding to the subject area with the number of pixels on the entire imaging screen. The number of pixels of the entire photographing screen here corresponds to the number of effective pixels of the image sensor 106, but is not necessarily limited thereto, and may be determined in advance between the camera and the lens. The camera microcomputer 116 calculates the ratio of the number of pixels in the subject area to the number of pixels in the entire shooting screen, and transmits it to the camera microcomputer 116 as information about the size of the subject area. As described above, when an image obtained by thinning out pixels and reducing the size is used for subject detection, the number of pixels in the subject area received from the subject detection unit 119 is the same as the pixels in the entire shooting screen. Normalize by number.

  Further, the camera microcomputer 116 determines whether or not the calculated ratio has changed more than a predetermined value compared to the previously detected value. If the ratio has increased / decreased more than the predetermined value, the subject has become larger / smaller. If this is not the case, information indicating that the size has not changed may be sent. In this case, the camera microcomputer 116 uses information indicating whether the size of the subject is “large”, “small”, or “no change” as the information about the size of the subject area instead of the ratio information as described above. It transmits to the microcomputer 115.

  Note that the camera microcomputer 116 may transmit the number of pixels corresponding to the subject area to the lens microcomputer 115 as information about the size of the subject area. In this case, the camera microcomputer 116 needs to transmit to the lens microcomputer 115 information on the number of pixels on the image sensor 106 of the entire shooting screen. As a result, a change in the ratio of the number of pixels in the subject area to the number of pixels in the entire photographing screen can be calculated in the lens microcomputer 115.

  The zoom drive source 111 is a drive source for moving the variable magnification lens 102. The focus drive source 112 is a drive source for moving the focus lens 105. The zoom drive source 111 and the focus drive source 112 are configured by actuators such as a stepping motor, a DC motor, a vibration motor, and a voice coil motor.

  The lens microcomputer 115 as the lens-side control means performs focus control (hereinafter referred to as TVAF control) in the TVAF method. The lens microcomputer 115 receives the TVAF evaluation value from the camera microcomputer 116, controls the focus drive source 112 based on the TVAF evaluation value, and performs focusing by moving the focus lens 105 in the optical axis direction.

  Next, TVAF control performed by the lens microcomputer 115 will be described with reference to FIGS. The TVAF control shown in FIG. 4 is executed according to a computer program stored in the lens microcomputer 115.

  Step 401 indicates the start of processing. In Step 402, the lens microcomputer 115 performs a minute driving operation and determines in which direction the in-focus point is in focus. The detailed description of the minute driving will be given in FIG.

  In Step 403, it is determined whether or not the focus is determined by the minute drive in Step 402. If the focus is determined, the process proceeds to Step 407 to perform focus stop / restart determination processing. If the focus is not determined, the process proceeds to Step 404.

  In Step 404, the lens microcomputer 115 climbs and drives the focus lens 105 at a predetermined speed in the direction determined in Step 402, and searches for a focus lens position where the TVAF evaluation value reaches a peak. The detailed operation of the hill climbing drive will be described later with reference to FIG.

  In Step 405, the lens microcomputer 115 returns the focus lens 105 to the focus lens position where the TVAF evaluation value during the hill-climbing driving operation is the peak.

  In Step 406, the lens microcomputer 115 determines whether or not the TVAF evaluation value has returned to the peak focus lens position. If the TVAF evaluation value has returned to the peak focus lens position, the process returns to Step 402 to perform the minute driving operation again. If it has not returned to the peak focus lens position, the process returns to Step 405 to continue the operation of returning to the peak focus lens position.

  Next, focus stop / restart determination processing from Step 407 will be described. In Step 407, the lens microcomputer 115 determines whether or not there is a communication request from the camera microcomputer 116. If there is a communication request, the process proceeds to Step 408. If there is no communication request, the lens microcomputer 115 waits in Step 407.

  In Step 408, the lens microcomputer 115 communicates with the camera microcomputer 116 to acquire a TVAF evaluation value and the like. Communication between the camera microcomputer 116 and the lens microcomputer 115 is performed at a timing synchronized with the V synchronization signal.

  In Step 409, the lens microcomputer 115 moves the focus lens 105 to the in-focus position determined to be in focus based on the TVAF evaluation value.

  In Step 410, it is determined whether or not the focus position has been moved. If the focus position has been moved, the process proceeds to Step 411. If not, the process returns to Step 407.

  In Step 411, the TVAF evaluation value at the in-focus position is held.

  In Step 412, the lens microcomputer 115 determines whether or not there is a communication request from the camera microcomputer 116. If there is a communication request, the process proceeds to Step 413. If there is no communication request, the lens microcomputer 115 waits in Step 412.

  In Step 413, the lens microcomputer 115 communicates with the camera microcomputer 116 to acquire a TVAF evaluation value and the like.

  In Step 414, the lens microcomputer 115 compares the TVAF evaluation value held in Step 411 with the latest TVAF evaluation value acquired in Step 413, and determines whether the variation of the TVAF evaluation value is large. If the TVAF evaluation value fluctuates greatly, it is determined that the subject has changed, and the process proceeds to step 402 to resume the minute driving operation. If the TVAF evaluation value does not fluctuate, the process returns to step 412.

  Next, the minute driving operation will be described with reference to FIGS. The minute driving operation control shown in FIGS. 5 and 6 is executed according to a computer program stored in the lens microcomputer 115.

  Step 501 indicates the start of processing.

  In Step 502, the lens microcomputer 115 determines whether or not there is a communication request from the camera microcomputer 116. If there is a communication request, the process proceeds to Step 503. If there is no communication request, the lens microcomputer 115 waits in Step 502.

  In Step 503, the lens microcomputer 115 communicates with the camera microcomputer 116, and acquires a TVAF evaluation value, information on the size of the subject area described above, and the like. Also, information on the allowable circle of confusion δ and the F value is acquired.

  In Step 504, the lens microcomputer 115 obtains the driving cycle and driving delay time of the focus lens 105 based on the information acquired from the camera microcomputer 116. The drive delay time is a time for adjusting the accumulation time and the focus lens drive phase so that the focus lens 105 is stopped during the charge accumulation in the region corresponding to the TVAF frame. In this embodiment, the driving cycle is 2V and the driving delay time is 1 / 2V.

  In Step 505, the lens microcomputer 115 determines whether or not the current Mode is 0. If it is 0, the lens microcomputer 115 proceeds to Step 506 and performs processing at the focus lens position on the near side described later. If Mode is not 0, the process proceeds to Step 511.

<Processing at the closest focus lens position>
In Step 506, the lens microcomputer 115 stores the TVAF evaluation value captured in Step 503 as the TVAF evaluation value on the infinity side (because it is based on the sensor output accumulated when the focus lens is on the infinity side).

  In Step 507, Mode is added (when it becomes 4 or more, it is returned to 0), and the process proceeds to Step 508.

<Common processing>
In Step 508, if the direction determined to be the in-focus direction is continuously A a predetermined number of times, the process proceeds to Step 531; otherwise, the process proceeds to Step 509.

  In Step 509, if the subject is continuously moving in the same direction, the process proceeds to Step 531; otherwise, the process proceeds to Step 510.

  In Step 510, if the focus lens repeats the reciprocation in the same area a predetermined number of times B, the process proceeds to Step 532. If the focus lens does not repeat the reciprocation a predetermined number of times B in the same area, the process returns to Step 502.

  In Step 531, it is determined that the direction can be determined, the process proceeds to Step 534, the process is terminated, and the process proceeds to Step 403 in FIG.

  In Step 532, the lens microcomputer 115 calculates the focus position from the past lens position. In Step 533, assuming that the in-focus state has been determined, the process proceeds to Step 534, where the processing is terminated, and the process proceeds to Step 403 in FIG. 4.

  In Step 511, it is determined whether the current Mode is 1, and if it is 1, the process proceeds to Step 512 to perform a process of driving the focus lens 105 described below indefinitely. If Mode is not 1, the process proceeds to Step 520.

<Process to drive the focus lens infinitely>
In Step 512, the lens microcomputer 115 calculates the vibration amplitude and the center movement amplitude. The vibration amplitude here corresponds to the amount of movement of the focus lens 105 from the vibration center position in the closest direction (or infinite direction). The center movement amplitude corresponds to the amount of movement of the vibration center position. On the basis of the depth of focus determined from the permissible circle of confusion δ acquired from the camera microcomputer 116 and the F value in Step 503, the amplitude is reduced when the depth is shallow, and the amplitude is increased when the depth is deep.

  In Step 513, the lens microcomputer 115 determines whether or not the subject is moving in the same direction based on the information about the size of the subject area acquired in Step 503. The determination is performed, for example, by detecting whether the ratio of the number of pixels in the subject area to the number of pixels in the entire shooting screen has increased continuously for a predetermined number of times or continuously decreased for a predetermined number of times. If it is determined in step 513 that the subject is moving in the same direction, the process proceeds to step 514, and the vibration amplitude / center movement amplitude is increased to improve the response. In Step 514, the vibration amplitude / center movement amplitude is increased regardless of whether the subject is moving to the infinite side or the close side. When the subject moves to the infinity side, the infinity side TVAF evaluation value based on the charge accumulation when the focus lens 105 is stopped on the infinity side is increased by increasing the vibration amplitude / center movement amplitude. Become. Therefore, when determining whether or not the center movement is necessary using the infinite side TVAF evaluation value, the center movement to the infinite side is easy and the center movement to the closest side is difficult. On the other hand, when the subject is moving to the closest side, by increasing the vibration amplitude / center movement amplitude, the infinite TVAF evaluation value based on the charge accumulation when the focus lens 105 is stopped on the infinite side after moving is obtained. Smaller. For this reason, when determining whether or not the center movement is necessary using the infinite side TVAF evaluation value, it becomes easy to move the center to the closest side and it is difficult to move the center to the infinite side.

  In Step 515, the infinite TVAF evaluation value in Mode = 0 described above is compared with a close-side TVAF evaluation value in Mode = 2 described later. If the infinite-side TVAF evaluation value is larger than the close-side TVAF evaluation value, the process proceeds to Step 516. If the infinite TVAF evaluation value is smaller than the closest TVAF evaluation value, the process proceeds to Step 517.

In Step 516, the drive amplitude is changed to
Drive amplitude = vibration amplitude + center movement amplitude.

In Step 517, the drive amplitude is changed to
Drive amplitude = vibration amplitude.

  In Step 518, the lens microcomputer 115 controls the focus drive source 112 so as to drive the focus lens 105 in the infinite direction with the drive amplitude determined in Step 516 or Step 517.

  In Step 519, Mode is added (when it becomes 4 or more, it is returned to 0), and the process proceeds to Step 508. Step 508 and subsequent steps are as described above.

  In Step 520, it is determined whether the current Mode is 2, and if it is 2, the process proceeds to Step 521 to perform processing at an infinite focus lens position described later. If Mode is not 2, the process proceeds to Step 523.

<Processing at infinite focus lens position>
In Step 521, the TVAF evaluation value captured in Step 503 is stored as the TVAF evaluation value on the near side (because it is based on the sensor output accumulated when the focus lens is on the close side).

  In Step 522, Mode is added (when it becomes 4 or more, it is returned to 0), and the process proceeds to Step 508. Step 508 and subsequent steps are as described above.

<Process to drive the focus lens close>
In Step 523, the lens microcomputer 115 calculates the vibration amplitude and the center movement amplitude. On the basis of the depth of focus determined from the permissible circle of confusion δ acquired from the camera microcomputer 116 and the F value in Step 503, the amplitude is reduced when the depth is shallow, and the amplitude is increased when the depth is deep.

  In Step 524, the lens microcomputer 115 determines whether or not the subject is moving in the same direction based on the size information of the subject area acquired in Step 503. If it is determined in Step 524 that the subject is moving in the same direction, the process proceeds to Step 525, and the vibration amplitude / center movement amplitude is increased in order to improve the responsiveness. In Step 525, the vibration amplitude / center movement amplitude is increased regardless of whether the subject is moving to the infinite side or the close side. When the subject is moving to the near side, the vibration amplitude / center movement amplitude is increased, so that the near side TVAF evaluation value based on the charge accumulation when the focus lens 105 is stopped on the near side is increased. Become. For this reason, when determining whether or not the center movement is necessary using the near-side TVAF evaluation value, it becomes easy to move the center to the near side and difficult to move to the infinite side. On the other hand, when the subject is moving to the infinite side, by increasing the vibration amplitude / center movement amplitude, the near side TVAF evaluation value based on the charge accumulation when the focus lens 105 is stopped on the near side after moving is obtained. Smaller. For this reason, when determining whether or not the center movement is necessary using the near side TVAF evaluation value, it becomes easy to move the center to the infinite side and it is difficult to move the center to the near side.

  In Step 526, the infinite TVAF evaluation value in Mode = 1 is compared with the close TVAF evaluation value in Mode = 3. If the close TVAF evaluation value is larger than the infinite TVAF evaluation value, the process proceeds to Step 527. If the near side TVAF evaluation value is smaller than the infinite side TVAF evaluation value, the process proceeds to Step 528.

In Step 527, the drive amplitude is changed to
Drive amplitude = vibration amplitude + center movement amplitude.

In Step 528, the drive amplitude is changed to
Drive amplitude = vibration amplitude.

  In Step 529, the lens microcomputer 115 controls the focus driving source 112 to drive the focus lens 105 in the infinite direction with the amplitude determined in Step 527 or Step 528.

  In Step 530, Mode is added (when it becomes 4 or more, it is returned to 0), and the process proceeds to Step 508. Step 508 and subsequent steps are as described above.

  In FIGS. 5 and 6, the description is given on the assumption that the zooming operation by the movement of the zoom lens 102 is not performed. In consideration of the zooming operation, in Steps 513 and 524, the lens microcomputer 115 determines whether the subject is moving in the same direction based on the information about the size of the subject area acquired in Step 503 and the position of the zoom lens 102. To do. Alternatively, the position of the variable power lens 102 is detected at the timing synchronized with the V synchronization signal, and when the position of the variable power lens 102 changes, it is not determined whether or not the subject is moving in the same direction. Alternatively, the determination result may be invalidated. Further, in the case of a lens whose angle of view greatly varies with the movement of the focus lens 105, it is determined whether or not the subject is moving in the same direction in consideration of the influence on the size change of the subject due to the focus movement.

  FIG. 7 shows the time course of the focus lens operation. Here, the horizontal axis represents time, the downwardly convex period at the top is the V synchronization signal, the lower diamond represents the accumulation time of the CMOS sensor, and the lower EVx represents the TVAF evaluation value obtained at that timing. The CMOS sensor performs charge accumulation in a predetermined period of a V synchronization period that is a cycle of a V synchronization signal (vertical synchronization signal) generated by the signal generation circuit 120. Furthermore, the arrow below that indicates that the TVAF evaluation value is communicated from the camera microcomputer 116 to the lens microcomputer 115. The bottom is the focus lens position.

  In order to describe the accumulation time of the CMOS sensor, driving of the CMOS sensor will be described with reference to FIG. In FIG. 8, the left shows the imaging surface and scanning lines. The right shows the accumulation time and transfer time for each scanning line. Since the CMOS sensor is called a rolling shutter and releases the shutter for each scanning line, the storage time and transfer time are different between the upper part and the lower part of the screen as shown in the figure. This accumulation time is represented by a diamond in FIG.

  As shown in FIG. 7, the TVAF evaluation value is monitored while the focus lens 105 is moved close and infinite, and the focus lens 105 is moved in the in-focus direction. Here, it is necessary to obtain a TVAF evaluation value from an imaging signal generated based on the electric charge accumulated in the CMOS sensor while the focus lens 105 is positioned on the close / infinite side. Therefore, the timing for stopping the focus lens 105 is matched with the accumulation time of the CMOS sensor. Although it is not necessary to stop the focus lens 105 to the close / infinite side during the entire accumulation time of the CMOS sensor, it is necessary to stop during the charge accumulation of the scanning lines in the TVAF frame. As shown in FIG. 3, when the TVAF frame is set small with respect to the imaging screen, the focus lens 105 may be stopped during the charge accumulation in the region on the CMOS sensor corresponding to the TVAF frame. Here, the TVAF evaluation value EV3 for the charge accumulated in the CMOS sensor during the accumulation time 3 is communicated to the lens microcomputer 115 at time T3, and the TVAF evaluation value EV5 for the charge accumulated in the CMOS sensor during the accumulation time 5 is obtained. Captured at time T5. At time T6, the TVAF evaluation values EV3 and EV5 are compared. If EV5> EV3, the vibration center is moved, and if EV3> EV5, the vibration center is not moved. In this way, the in-focus direction is determined and the in-focus is determined.

  Next, processing timings of the camera microcomputer 116 and the lens microcomputer 115 will be described with reference to FIG. In FIG. 9, the horizontal axis represents time, and shows processing of the camera microcomputer 116 within 1 V and processing of the lens microcomputer 115. First, immediately after the V synchronization signal is output, the camera microcomputer 116 acquires a TVAF evaluation value. Next, communication between camera lenses is performed. In this communication, the camera microcomputer 116 transmits information about the TVAF evaluation value and the size of the subject area acquired from the subject detection unit 119 to the lens microcomputer 115. Based on the received information, the lens microcomputer 115 calculates a target position for fine driving shown in FIG. 7 and a driving delay time for phase adjustment with the accumulation time. The lens microcomputer 115 waits based on the calculated drive delay time, and then performs lens drive processing to actually drive the focus lens 105. Note that the communication timing between the camera lenses is not necessarily limited to the timing shown in FIG. 9, but may be any timing that is synchronized with the V synchronization signal.

  Next, the hill-climbing driving operation will be described with reference to FIG. The hill-climbing driving operation is an operation for driving the focus lens 105 in the direction in which the TVAF evaluation value is increased while acquiring the TVAF evaluation value, and detecting the focus lens position where the TVAF evaluation value is maximized.

  Step 901 indicates the start of processing.

  In Step 902, the lens microcomputer 115 determines whether or not there is a communication request from the camera microcomputer 116. If there is a communication request, the process proceeds to Step 903. If there is no communication request, the lens microcomputer 115 waits in Step 902.

  In Step 903, the lens microcomputer 115 communicates with the camera microcomputer 116, and acquires information for determining the TVAF evaluation value, the TVAF evaluation value generation delay time that is a feature of the present invention, and other driving timings of the focus lens 105.

  In Step 904, the lens microcomputer 115 sets a hill-climbing driving speed. On the basis of the depth of focus determined from the allowable circle of confusion δ acquired from the camera microcomputer 116 and the F value, the amplitude is decreased when the depth is shallow, and is increased when the depth is deep.

  In Step 905, it is determined whether or not the TVAF evaluation value fetched in Step 903 is smaller than a predetermined amount than the previous TVAF evaluation value. If not smaller, the process proceeds to Step 906, and if smaller, the process proceeds to Step 911. Here, the predetermined amount is a value determined in consideration of the S / N of the TVAF evaluation value, and is set to a value equal to or larger than the fluctuation range of the TVAF evaluation value when the subject is fixed and the focus lens is fixed. By setting the predetermined amount in this way, it is possible to suppress the influence due to the variation of the TVAF evaluation value and perform hill-climbing driving in the correct direction.

  In Step 906, the lens microcomputer 115 determines whether or not the focus lens 105 has reached the infinite end. The infinity end is the position closest to the infinity of the focus lens stroke determined by design. If it has reached the infinite end, the process proceeds to Step 907. If not reached, proceed to Step 908.

  In Step 908, the lens microcomputer 115 determines whether or not the focus lens 105 has reached the closest end. The closest end is the position closest to the focus lens stroke determined by design. If the close end has been reached, go to Step 909. If not reached, proceed to Step 910.

  In Steps 907 and 909, a flag for storing the inverted end is set, and the process proceeds to Step 913. The focus lens 105 is inverted in the reverse direction to continue the hill-climbing drive.

  At Step 910, the lens microcomputer 115 climbs and drives the focus lens 105 in the previous forward direction at the speed determined at Step 904, proceeds to Step 902, and ends the current process.

  In Step 911, if the TVAF evaluation value has not decreased beyond the peak, the process proceeds to Step 912. If the TVAF evaluation value has decreased beyond the peak, the process proceeds to Step 914 to end the hill-climbing drive, proceeds to Step 915, ends the process, and proceeds to Step 405 in FIG.

  In Step 912, it is determined whether or not it has been continuously reduced by a predetermined number of times. If it has been continuously reduced, the process proceeds to Step 913, and if it has not been continuously decreased, the process proceeds to Step 910.

  In Step 910, the focus lens 105 is hill-climbed and driven in the previous forward direction at the speed determined in Step 904, and the process proceeds to Step 902 to end the current process.

  In Step 913, the focus lens 105 is hill-climbed at the speed determined in Step 904 in the opposite direction to the previous time, and the process proceeds to Step 902 to end the current process.

  FIG. 11 shows the movement of the focus lens 105 during the hill-climbing driving operation. Here, in the state of A, since the AF evaluation value decreases beyond the peak, the hill-climbing driving operation is terminated because there is an in-focus point, and the operation shifts to the minute driving operation. On the other hand, in the state of B, since the AF evaluation value does not have a peak and decreases, the driving direction is reversed and the hill-climbing driving operation is continued.

  During the hill-climbing driving operation, the lens microcomputer 115 acquires subject area size information for each 1V. Here, it may be determined whether the subject is moving in the same direction based on the acquired size information of the subject region, and the hill-climbing driving speed may be changed according to the determination result. For example, when it is determined that the subject is moving in the close direction while the focus lens 105 is moving from the infinity side to the close side, the moving speed of the focus lens is increased. That is, when the hill-climbing movement direction of the focus lens 105 is the same as the direction in which the subject is moving, increasing the moving speed of the focus lens 105 can cause the evaluation value peak position to be reached because the subject is moving. The delay can be reduced.

  As described above, the lens microcomputer 115 controls the TVAF evaluation value to always be maximized by moving the focus lens 105 while repeating the restart determination → micro drive → mountain climbing drive → micro drive → restart determination. Keep in focus.

  As described above, in this embodiment, in the interchangeable lens autofocus system in which the subject detection unit and the autofocus unit are separated, data (information) on the size of the subject is sent from the camera to the lens. Thereby, the interchangeable lens can perform autofocus using a change in the size of the subject in accordance with lens characteristics such as actuator performance. For example, in the case of a lens whose angle of view greatly varies with the movement of the focus lens as the lens characteristics, the movement direction of the subject is determined in consideration of the influence on the size change of the subject due to the focus movement.

  As described above, even in a system that performs autofocus using an interchangeable lens, by enabling autofocus using the size of the subject, it is possible to realize autofocus that quickly follows the movement of the subject.

<Second Embodiment>
Hereinafter, a second embodiment of the present invention will be described. The configuration of the example of the present invention is the same as that shown in FIG. 1 as in the first embodiment. In this configuration, the data on the subject size is analyzed by the camera microcomputer 116, and an AF operation change command (drive command) corresponding to the analysis result is sent from the camera microcomputer 116 to the lens microcomputer 115.

  FIG. 12 shows the processing of the camera microcomputer 116. In this embodiment, the camera microcomputer 116 analyzes the change in the size of the subject, and transmits an autofocus process corresponding to the change to the lens microcomputer 115. Step 1101 indicates the start of processing. In Step 1102, the camera microcomputer 116 acquires the subject detection result from the subject detection unit 119. In Step 1103, the camera microcomputer 116 sets a TVAF frame according to the subject detection result acquired in Step 1102. In Step 1104, the camera microcomputer 116 acquires a TVAF evaluation value from the TVAF signal processing circuit 114. In Step 1105, the camera microcomputer 116 determines whether the subject is moving in one direction. If it is determined that it is moving in one direction, the process proceeds to Step 1106. If not, the process proceeds to Step 1109 and the TVAF evaluation value is communicated to the lens microcomputer 115, and the process is terminated.

  In Step 1106, the camera microcomputer 116 determines whether the subject continues to move in one direction. If it is determined that the movement in one direction continues, the process proceeds to Step 1107 to communicate the hill climbing command and the hill climbing direction to the lens microcomputer 115. Otherwise, the process proceeds to Step 1108 to communicate an amplitude addition command to the lens microcomputer 115. Thereafter, the process proceeds to Step 1109, and the TVAF evaluation value is communicated to the lens microcomputer 115 to finish the process.

  Next, processing in the lens microcomputer 115 will be described. The flowchart of TVAF is the same as FIG. 4 of the first embodiment. FIG. 13 and FIG. 14 show processing corresponding to FIG. 5 and FIG. 6 of the first embodiment. Here, the process of changing the autofocus process by analyzing the change in the size of the subject in the lens microcomputer 115 last time is changed according to the instruction of the camera microcomputer 116. Only Step 1201, Step 1202, and Step 1203 are different, and the lens microcomputer 115 changes the autofocus control in accordance with a command from the camera microcomputer 116 determined in FIG.

  As described above, in this embodiment, in the interchangeable lens type autofocus system in which the subject detection unit and the autofocus unit are separated, a change in autofocus control is sent from the camera to the lens based on the size data of the subject. As a result, it is possible to perform autofocus using a change in the size of the subject, and it is possible to realize autofocus that quickly follows the movement of the subject.

DESCRIPTION OF SYMBOLS 105 Focus lens 106 Image pick-up element 108 Camera signal processing circuit 109 Monitor apparatus 112 Focus drive source 113 TVAF gate 114 TVAF signal processing circuit 115 Lens microcomputer 116 Camera microcomputer 117 Lens unit 118 Camera unit 119 Subject detection part 120 Signal generation circuit

Claims (13)

An imaging apparatus comprising a photographic optical system including a focus lens and detachable from a lens unit that controls driving of the focus lens based on information transmitted from the imaging apparatus,
Imaging means for photoelectrically converting a subject image by the imaging optical system with an imaging element to generate an imaging signal;
Detecting means for specifying a region of a specific subject image based on the imaging signal and detecting the size of the specific subject image;
An acquisition means for acquiring a focus signal based on a high-frequency component of the imaging signal corresponding to a focus detection region;
An image pickup apparatus comprising: a control unit that transmits information about the size of the specific subject image detected by the focus signal and the detection unit to a mounted lens unit. The imaging means is means for accumulating charges in synchronization with a vertical synchronization signal,
The imaging apparatus according to claim 1, wherein the focus unit and information on the size of the specific subject image are transmitted to the lens unit in synchronization with the vertical synchronization signal.   The information related to the size of the specific subject image is a value obtained by normalizing the number of pixels on the image sensor corresponding to the specific subject image with the number of pixels on the image sensor corresponding to the entire shooting screen. The imaging apparatus according to claim 1 or 2, wherein   The information related to the size of the specific subject image is information indicating whether the size of the specific subject image is larger, smaller, or unchanged than the previous time. Item 3. The imaging device according to Item 1 or 2.   The control means is such that a value obtained by normalizing the number of pixels on the image sensor corresponding to the specific subject image with the number of pixels on the image sensor corresponding to the entire shooting screen is larger than a predetermined value compared to the previous time. The image pickup apparatus according to claim 4, wherein information relating to a size of the specific subject image is generated based on whether or not the change has occurred greatly.   The control means transmits the number of pixels on the imaging device corresponding to the specific subject image to the lens unit as information relating to the size of the specific subject image, and the imaging corresponding to the entire photographing screen. The imaging apparatus according to claim 1, wherein the number of pixels on the element is transmitted to the lens unit. A lens unit that can be attached to an image pickup apparatus having an image pickup means for generating an image pickup signal,
A taking optical system including a focus lens;
Driving means for driving the focus lens;
Lens-side control means for receiving information from the imaging device and controlling the driving means based on the information;
The lens unit characterized in that the information received from the imaging device is a focus signal based on the imaging signal generated by the imaging means and information on the size of a specific subject image detected by the imaging device.   The lens unit according to claim 7, wherein the lens-side control unit determines whether or not the subject is moving in the same direction based on the received information regarding the size of the specific subject image. .   9. The lens-side control unit adds the amplitude of the minute driving operation when it is determined that the subject is moving in the same direction during the minute driving operation of the focus lens. The lens unit described.   When the lens-side control means performs control to drive the focus lens in a direction in which the focus signal increases while receiving the focus signal from the imaging device, the subject is in the same direction as the drive direction of the focus lens. The lens unit according to claim 8 or 9, wherein when it is determined that the lens is moving, the driving speed of the focus lens is increased. The imaging means is means for accumulating charges in synchronization with a vertical synchronization signal,
The lens unit according to claim 8, wherein the lens-side control unit receives information from the imaging unit in synchronization with the vertical synchronization signal. A lens unit that includes a photographic optical system including a focus lens and that controls driving of the focus lens based on information transmitted from an imaging device can be attached and detached, and a subject image obtained by the photographic optical system is photoelectrically converted by an image sensor. A method for controlling an imaging apparatus including an imaging means for generating a signal,
Detecting a specific subject image region based on the imaging signal and detecting the size of the specific subject image;
An acquisition step of acquiring a focus signal based on a high-frequency component of the imaging signal corresponding to a focus detection region;
And a control step of transmitting information relating to the focus signal and the size of the specific subject image detected in the detection step to a mounted lens unit. A method of controlling a lens unit that can be mounted on an imaging device including an imaging unit that generates an imaging signal and includes a photographing optical system including a focus lens,
A driving step of driving the focus lens;
Receiving information from the imaging device, and controlling the driving of the focus lens based on the information,
The information received from the imaging device is a focus signal based on an imaging signal generated by the imaging means and information on the size of a specific subject image detected by the imaging device. Control method.

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