JP2010186137A - Focus adjustment device and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent unsuitable lock-on actuation in a focus adjustment device and an imaging apparatus incorporating the focus adjustment device. <P>SOLUTION: The focus adjustment device includes a focus detecting means for detecting a focus adjustment state of an imaging optical system; a focus adjusting means for adjusting the focus of the imaging optical system on the basis of the focus adjustment state detected by the focus detecting means; an imaging means for picking up an image formed by the imaging optical system; a recognizing means for repeatedly recognizing the position of a specific target image within an image picked up by the imaging means; and a control means for inhibiting (S302, S303) a focus adjustment from being made by the focus adjusting means, on the basis of a state when the position of the target image cannot be recognized by the recognizing means (S203). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a focus adjustment device and an imaging apparatus equipped with the focus adjustment device.

  If another subject crosses in front of the target subject, or if the subject is removed from the AF area while chasing a moving subject, the focus adjustment drive of the taking lens is prohibited for a certain period of time (AF Locking), a focus adjustment device is known that can continue to capture the subject intended by the photographer.

JP 2008-113423 A

  However, in the conventional focus adjustment apparatus described above, when the composition is changed to shoot another subject while the focus adjustment function is in an operating state, the AF lock works after the composition change if the AF lock condition is satisfied. Therefore, there is a problem that the focus adjustment may not be started immediately contrary to the intention of the photographer.

(1) The invention of claim 1 is a focus detection unit that detects a focus adjustment state of the imaging optical system, and a focus adjustment that performs focus adjustment of the imaging optical system based on the focus adjustment state detected by the focus detection unit. Means, an image pickup means for picking up an image by the imaging optical system, a recognition means for repeatedly recognizing the position of an image of a specific target in the image picked up by the image pickup means, and a position of the target image is recognized by the recognition means Control means for prohibiting the focus adjustment by the focus adjustment means based on the state when it was not possible.
(2) According to a second aspect of the present invention, in the focus adjustment apparatus according to the first aspect, the target image is captured by the imaging unit based on the history of the position of the target image repeatedly recognized by the recognition unit. Determination means for determining whether the image has disappeared within the range or moved out of the range of the image.
(3) The invention of claim 3 is the focus adjustment apparatus according to claim 2, wherein the focus detection means repeatedly detects the focus adjustment state, and the control means has a plurality of focus adjustment states that are repeatedly detected by the focus detection means. The focus adjustment by the focus adjustment unit is prohibited based on the history of the above and the focus adjustment prohibition is invalidated based on the determination result by the determination unit.
(4) According to a fourth aspect of the present invention, in the focus adjustment apparatus according to the third aspect, the control means adjusts the focus when the determination means determines that the target image has moved out of the image range. Disable prohibition.
(5) A fifth aspect of the present invention is the focus adjustment apparatus according to any one of the second to fourth aspects, wherein the determination means includes the target image among the positions of the target image repeatedly recognized by the recognition means. When the position of the target image recognized before it becomes unrecognizable is positioned at the end of the image range, it is determined that the target image has moved out of the image range.
(6) A sixth aspect of the present invention is the focus adjustment apparatus according to any one of the first to fifth aspects, wherein the imaging means receives the light beam passing through the imaging optical system and receives an image signal corresponding to the image. And a focus detection pixel that outputs a signal obtained by receiving a pair of light fluxes that pass through the imaging optical system and is arranged in the array of the plurality of imaging pixels. The focus detection means detects the focus adjustment state of the imaging optical system based on the output of the focus detection pixels.
(7) The invention of claim 7 is an imaging device including the focus adjustment device according to any one of claims 1 to 6.

  According to the present invention, even when the composition is changed in order to adjust the focus on different objects, the focus adjustment can be started immediately, and the focus adjustment intended by the photographer can be realized.

Cross-sectional view showing the configuration of a single-lens reflex digital camera of an embodiment The flowchart which shows the focus adjustment control program of one Embodiment Flowchart showing tracking lock-on execution setting subroutine Flowchart showing AF / tracking lock-on execution setting subroutine A shooting screen using a photometric element in which pixels are arranged in a square of 18 pixels in a horizontal direction and 12 pixels in a vertical direction, a tracking subject region (a region indicated by hatching in the figure) and a plurality of AF areas (in the drawing) Figure showing the area indicated by the dashed rectangle inside) Flow chart showing a focus adjustment control program of a reference example

  The focus adjustment state of the photographic lens (in this embodiment, the defocus amount) is detected in a plurality of focus detection areas set in the photographic screen, and the photographic lens is focused based on the defocus amount in one of the areas. The automatic focus adjustment (AF) function to be driven and the image of the subject to be tracked in the photographed image are stored as a template image (reference image). A focus adjustment device that includes an image tracking function that repeatedly recognizes (tracks) a subject to be tracked while searching for a position (template matching), and that adjusts the focus of the photographing lens using the AF function and the image tracking function, and the focus adjustment device One embodiment of an image pickup apparatus (single-lens reflex digital camera) equipped with a camera will be described.

  FIG. 1 is a cross-sectional view illustrating a configuration of a single-lens reflex digital camera according to an embodiment. The photographing lens 1 includes a focusing lens, a zooming lens, a diaphragm, and the like, and forms a subject image on the imaging surface. The quick return mirror 2 is a mirror that selectively guides the light flux from the subject to the image sensor 6 or the viewfinder, and the center portion is a half mirror. Before photographing, the quick return mirror 2 is set in the photographing optical path as shown, the subject light is reflected and guided to the viewfinder, and part of the subject light that has passed through the half mirror part reflects the sub mirror 7. It is guided to the focus detection unit of the phase difference detection method. On the other hand, at the time of shooting, the quick return mirror 2 is retracted from the shooting optical path, and the subject light is guided to the image sensor 6.

  A subject image is formed on the finder screen 3 by the photographing lens 1 and is visually recognized by the photographer through the pentaprism 4 and the eyepiece lens 5. The image sensor 6 is composed of a CCD, and converts the subject image formed on the light receiving surface by the photographing lens 1 into an image signal and outputs it. Note that the image sensor 6 may be configured by CMOS, CID, or the like. In addition, an infrared cut filter for cutting infrared light and an optical low-pass filter for preventing image aliasing noise are arranged on the front surface of the image sensor 6, but these are not shown in FIG. 1. . The sub mirror 7 reflects the subject light transmitted through the central half mirror part of the quick return mirror 2 before photographing and guides it to the focus detection part. At the time of shooting, the sub mirror 7 is retracted from the shooting optical path together with the quick return mirror 2.

  Part of the subject light transmitted through the central half mirror part of the quick return mirror 2 before photographing is guided to a focus detection optical system (not shown) via the sub mirror 7. The focus detection optical system separates the subject light for focus detection into a pair of light beams by a mask (not shown), and a pair of phase difference AF (Auto Focus) detection elements 8 on a pair of CCD line sensors (not shown). Reimage the image. The phase difference AF detection element 8 outputs a focus detection signal corresponding to a pair of images indicating the focus adjustment state of the photographing lens 1.

  On the other hand, the subject image formed on the finder screen 3 before photographing is guided to the photometry element 16 via the pentaprism 4 and the photometry lens 15, and the subject image is formed on the light receiving surface of the photometry element 16. The photometry element 16 includes a plurality of pixels (photoelectric conversion elements) arranged in a matrix (for example, a square arrangement of n horizontal and m vertical). Each pixel is divided into three parts, and these parts are provided with primary color filters of red R, green G, and blue B, respectively. As a result, the RGB signal of the subject image can be output for each pixel. The photometry element 16 outputs an image signal corresponding to the subject image, and image tracking control and exposure calculation control, which will be described later, are performed based on the image signal.

  The control device 18 includes a microcomputer (not shown) and peripheral components such as a memory and an A / D converter. The control device 18 includes a device built in the camera and an image sensor 6, a phase difference AF detector 8, and the like in the form of a microcomputer software. Control of the photometric element 16 and various calculations, various sequence control of the camera, and the like are performed. The control device 18 controls the image sensor 6 to perform charge accumulation, readout of the captured image, various processing of the captured image, recording of the captured image, display of the captured image, and the like.

  The control device 18 includes an AF-CCD control unit 9, a defocus calculation unit 10, a focus area position determination unit 11, a lens drive amount calculation unit 12, and a lens drive control unit 13. The AF-CCD control unit 9 controls the phase difference AF detection element 8 to appropriately detect the CCD line sensor for AF (not shown, hereinafter referred to as AF sensor) set corresponding to a plurality of AF areas in the photographing screen. The gain signal and accumulation time are controlled, and the charge signal (focus detection signal) accumulated in the AF area (focus area) where focus detection is performed is read. The defocus calculation unit 10 calculates a defocus amount indicating the focus adjustment state of the photographing lens 1 based on the focus detection signal read from the phase difference AF detection element 8 by the AF-CCD control unit 9. The focus area position determination unit 11 determines an AF area for focusing the photographing lens 1 from a plurality of AF areas in the photographing screen. In this specification, the single point AF mode will be described as an example. The lens driving amount calculation unit 12 calculates a lens target position that is a driving target of the focusing lens based on the calculation result of the defocus amount. Here, the lens target position is a position where the defocus amount becomes 0 when the focusing lens is driven there. The lens drive control unit 13 includes an actuator that drives the focusing lens, and drives the focusing lens to a target position to adjust the focus of the photographing lens 1.

  Further, the control device 18 controls the photometric element 16, reads out the image signal of the subject image from the photometric element 16, and performs image tracking control and exposure calculation control based on the image signal. In the image tracking control, an image of a subject to be tracked in an image captured by the photometry element 16 is stored as a template image (reference image), and at least one of color information and luminance information is repeatedly captured in the image. An AF area (hereinafter referred to as a focus area) for performing template matching for searching for the position of a subject recognition area that is the same as or similar to the template image and searching for an AF area in the subject area to adjust the focus of the photographic lens 1. It is determined whether or not to adopt. Then, a target position for driving a focusing lens (not shown) of the photographing lens 1 is calculated based on the defocus amount detected in the in-focus area of the determination result.

  The operation member 17 includes various switches for operating the camera, such as an AF area selection switch, a shooting mode selection switch, a shutter button half-press switch, and a full-press switch.

  Here, before describing the focus adjustment control of one embodiment, a lock-on function in the conventional focus adjustment control will be described as a reference example. FIG. 6 is a flowchart showing a focus adjustment control program of a reference example. This control program is a control program after the focus adjustment control is started and the subject to be imaged is captured. In step 1, charge accumulation control is performed by setting the signal amplification gain and accumulation time of the phase difference AF detection element 8. In step 2, a focus detection signal (charge accumulation signal) of the AF area is read from the phase difference AF detection element 8, and in step 3 the defocus amount is calculated based on the focus detection signal.

  In step 4, it is determined whether or not the focus can be detected based on the calculation result of the defocus amount. If the focus can be detected, the process proceeds to step 5; If focus detection is possible, the lens drive amount to the in-focus position is calculated based on the defocus amount in step 5. In subsequent step 6, the defocus amount detected in the current focus detection is compared with the defocus amount detected in the previous focus detection, and the subject captured in the AF area in the current focus detection is captured in the previous focus detection. It is determined whether or not the subject is the same as the subject. When the defocus amount detected by the previous and current focus detections satisfies the specified reliability, and the difference between the previous and current defocus amounts is within the predetermined value, the subject is the same and exceeds the predetermined value. Are not the same subject. If the subject captured in the AF area in the previous and current focus detections is the same, the process proceeds to step 7 to drive the focusing lens by the lens drive amount of the calculation result.

  On the other hand, if it is determined in step 4 that focus detection is impossible, or if it is determined in step 6 that the subject in the AF area in the previous and current focus detection is not the same, lens driving is temporarily prohibited in step 8. “Lock-on” for (AF lock) is started, and counting of the lock-on time is started. If the lock-on has already started, the lock-on and the lock-on time are continuously counted. In step 9, it is determined whether or not the lock-on time has exceeded a predetermined time. If not, the process returns to step 1 to repeat the above-described processing. When the lock-on time exceeds the predetermined time, the process proceeds to step 10 where AF control data is initialized in order to resume lens driving.

  As described above, the lock-on function in the conventional focus adjustment control allows the subject that is temporarily aimed from the AF area when another subject crosses the target subject or when chasing a moving subject. This function is effective when the camera has been removed, and can continue to capture the target subject. However, with the above-described conventional lock-on function, any of the conditions (the lock-on condition) when it is determined that the focus detection is impossible or when it is determined that the subject detected by the previous focus detection and the previous focus detection is not the same. If the photographer changes the composition to adjust the focus on a different subject, the above lock-on condition is satisfied. If it is satisfied, the lock-on function will work, and until the lock-on is released after a predetermined time, focus adjustment will not be started against the photographer's will.

  In order to solve such a problem, the following lock-on is performed in the focus adjustment control of one embodiment. The lock-on in the above-described conventional focus adjustment control is determined to be executed or not executed based on the focus detection result by the automatic focus adjustment (AF) function. On the other hand, the lock-on in the focus adjustment control according to the embodiment is based on the focus detection result by the automatic focus adjustment (AF) function described above and the subject tracking result by the image tracking function described above. Decide on execution. In this specification, the lock-on based on the focus detection result by the automatic focus adjustment (AF) function is called “AF lock-on”, and the lock-on based on the subject tracking result by the image tracking function is called “tracking lock-on”.

  FIG. 2 is a flowchart showing a focus adjustment control program according to an embodiment. This control program is a control program after the focus adjustment control is started and the subject to be imaged is captured. In step 101, charge accumulation control is performed by setting the signal amplification gain and accumulation time of the phase difference AF detection element 8. In step 102, the photometric element 10 captures an image, searches the captured image for a subject recognition area similar to a template image stored in advance, and acquires subject recognition information, that is, subject tracking results. Note that the template image is an image of a portion of the image that is first designated by the photographer using the AF area selection switch. In step 103, the focus detection signal (charge accumulation signal) of the AF area is read from the phase difference AF detection element 8, and in step 104, the defocus amount is calculated based on the focus detection signal.

  In step 105, it is determined whether or not focus detection is possible based on the defocus amount calculation result. If focus detection is possible, the process proceeds to step 106. If not, the process proceeds to step 109. If focus detection is possible, the lens drive amount to the in-focus position is calculated based on the defocus amount in step 106. In step 107, the defocus amount detected in the current focus detection is compared with the defocus amount detected in the previous focus detection, and the subject captured in the AF area in the current focus detection is captured in the previous focus detection. It is determined whether or not the subject is the same as the subject. If the defocus amounts detected by the previous and current focus detections satisfy the predetermined reliability and the difference between the previous and current defocus amounts is within a predetermined value, the same subject is selected. If it is the same subject, the process proceeds to step 108; otherwise, the process proceeds to step 109.

  If the previous and current subjects captured in the AF area are the same, the tracking lock-on execution setting subroutine shown in FIG. 3 is executed in step 108, and lock-on based on the subject tracking result by the image tracking function described above, that is, tracking is performed. Sets whether to perform lock on. Since it is determined in step 107 that the previous subject and the current subject captured in the AF area are the same, here, lock-on based on the focus detection result by the automatic focus adjustment (AF) function described above, that is, AF lock-on is performed. Does not execute. Details of the tracking lock-on execution setting process shown in FIG. 3 will be described later.

  If it is determined in step 105 that focus detection is impossible, or if it is determined in step 107 that the subjects in the AF area in the previous and current focus detections are not the same, the AF / tracking lock-on shown in FIG. An execution setting subroutine is executed to set whether or not to perform lock-on based on the focus detection result by the automatic focus adjustment (AF) function and the subject tracking result by the image tracking function. Details of the AF / tracking lock-on execution setting process shown in FIG. 4 will be described later.

  In step 110 after execution of AF lock-on or tracking lock-on, or after non-execution thereof, the focusing lens is driven by the defocus amount of the calculation result or scan drive is performed.

  With reference to the subroutine shown in FIG. 3, the tracking lock-on execution setting based on the subject tracking result by the image tracking function will be described. In step 201, it is determined whether or not the subject to be tracked has disappeared as a result of the current image tracking. The image of the subject to be tracked in the captured image is stored as a template image (reference image), and the tracking target is searched while searching for the position of an image that is the same as or similar to the template image among images repeatedly captured by the photometric element 16. In the image tracking function for tracking the subject, if no image satisfying a predetermined similarity condition with respect to the template image cannot be detected in the captured image, the process proceeds to step 202 because the subject to be tracked has disappeared.

  On the other hand, if an image satisfying a predetermined similarity condition with respect to the template image is detected in the image picked up this time, the process proceeds to step 205 because the subject to be tracked has not disappeared. If the tracking subject has not disappeared, the lock-on based on the image tracking result, that is, the tracking lock-on is not executed in step 205, and the process returns to step 110 in FIG. If it is determined in step 201 that the tracking target subject has disappeared, it is determined in step 202 whether or not the subject recognition information determined to have disappeared is reliable. If there is no reliability, the process proceeds to step 205 and returns to step 110 in FIG. 2 without executing tracking lock-on.

  If the tracking subject disappearance determination is reliable, the process proceeds to step 203, and it is determined whether the tracked subject has disappeared in the shooting screen or whether the tracking subject has disappeared because the tracking subject has left the shooting screen. If the subject that was being tracked is off the shooting screen due to the composition change by the photographer, the photographer is paying attention to the new subject as a subject to be photographed, or the camera is turned to find a new subject. In such a case, it is desirable that the focus adjustment for the new subject that the photographer pays attention can be started immediately without locking on. On the other hand, if the subject that has been tracked does not appear to have gone out of the shooting screen and has disappeared within the shooting screen, for example, when another subject is about to pass in front of the tracking subject, The tracking subject may be removed from the AF area. In such a case, it is desirable that lock-on is executed so that the tracking subject can be continuously captured.

  Whether the tracking subject has disappeared in the shooting screen or whether the tracking subject has moved out of the shooting screen is determined as follows. FIG. 5 shows a shooting screen by the photometry element 16 in which pixels are arranged in a square of 18 pixels in a horizontal direction and 12 pixels in a vertical direction, a tracking subject region (a region indicated by hatching in the drawing) of the image tracking result in the shooting screen, and a plurality of pixels. AF area (area indicated by a broken-line rectangle in the figure). Basically, when the coordinate (x0, y0) that is the reference of the tracking subject area in the previous image tracking process is not at the end of the shooting screen, and the tracking subject disappears in the current image tracking process, Assume disappearance in the shooting screen. On the other hand, if the coordinate (x0, y0) that is the reference of the tracking subject area in the previous image tracking process is at the end position of the shooting screen and the tracking subject disappears in the current image tracking process, the photographer It is assumed that it disappears outside the shooting screen due to composition change.

  As another determination method, instead of the coordinates (x0, y0) serving as the reference of the tracking subject area, any outer side of the tracking subject area (hatched area indicated by hatching in FIG. 5) may be used as a reference. In other words, if any of the outer sides of the tracking subject area is not at the end of the shooting screen in the previous image tracking process and the tracking subject disappears in the current image tracking process, it is regarded as disappearance in the shooting screen. . On the other hand, if the outer periphery of one of the tracking subject areas is located at the edge of the shooting screen in the previous image tracking process and the tracking subject disappears in the current image tracking process, the photographer changes the composition. It is assumed to disappear outside the shooting screen.

  When determining whether the tracking subject disappears in the shooting screen or disappears from the shooting screen, the turn speed when the photographer changes the composition and the repetition time interval of the image tracking calculation are important factors. Therefore, the determination may be performed in consideration of the movement history of the position of the tracking subject area in the shooting screen in each image tracking process. For example, when the image tracking calculation repetition time interval is shorter than a predetermined time, that is, when the image tracking calculation cycle is fast and the moving speed of the tracking subject area in the shooting screen is higher than the predetermined speed, the previous time and the current time described above are used. Judgment is performed based on the subject tracking result. However, when the image tracking calculation cycle is slow and the moving speed of the tracking subject area in the shooting screen is high, the determination is performed based on the previous and current subject tracking results.

  In the latter case, for example, paying attention to the movement of the reference point or outer periphery of the subject tracking area in the shooting screen, the previous tracking subject disappeared this time even though it was at a position that was not the end of the shooting screen the previous time and the previous time. In this case, if the reference point or the outer edge is at a position that is not the end of the shooting screen, the previous time it moved to the end of the shooting screen, and the tracking subject disappeared this time , And disappearing outside the shooting screen. Also, if the reference point or the outer edge was at the edge of the shooting screen last time, but it was detected at a position other than the edge of the shooting screen last time, and the tracking subject disappears this time, And disappear.

  Note that the position as the end of the shooting screen may be a position corresponding to one pixel at the end of the shooting screen, or may be a band-like region occupied by a plurality of pixels at the end of the shooting screen. Further, the determination method of disappearance in the shooting screen or disappearance outside the shooting screen is not limited to the above-described method, and determination based on the movement history of the tracking subject area for a longer period considering various factors, etc. Many determination methods can be employed.

  If it is determined in step 203 that the tracking subject has disappeared in the shooting screen, the process proceeds to step 206. In this case, since the subject in the AF area is determined to be the same based on the previous and current focus detection results by the automatic focus adjustment (AF) function, AF lock-on is not executed. However, since it is determined that the tracking subject has disappeared in the shooting screen based on the subject tracking result up to this time by the image tracking function, tracking lock-on is executed and lens driving for a predetermined time is prohibited. Thereafter, the process returns to step 110 in FIG.

  If it is determined in step 203 that the tracking subject has disappeared outside the shooting screen, the process proceeds to step 204, where it is determined whether the focal length f of the zoom lens of the shooting lens 1 is 300 mm or more. The telephoto lens has a larger range of movement on the image plane, so when changing the composition, the focus detection range in the AF function is easily exceeded and lock-on conditions are easily applied. Do not execute lock-on during telephoto shooting. . If the focal length f is 300 mm or more, the process proceeds to step 205, tracking lock-on is not executed, and the process returns to step 110 in FIG. In step 110 of FIG. 2, the focusing lens of the photographing lens 1 is immediately driven according to the lens driving amount of the calculation result. On the other hand, when the focal length f is less than 300 mm, the process proceeds to step 206, tracking lock-on is executed, and lens driving for a predetermined time is prohibited. Thereafter, the process returns to step 110 in FIG.

  Next, with reference to a subroutine shown in FIG. 4, execution setting of AF lock-on based on the focus detection result by the automatic focus adjustment (AF) function and tracking lock-on based on the subject tracking result by the image tracking function will be described. Note that the processing in steps 201 to 204 is the same as the processing described in FIG.

  As a result of focus detection by the automatic focus adjustment (AF) function, is it determined that focus detection is impossible (step 105 in FIG. 2), or even if focus detection is possible, the subject in the AF area in the previous and current focus detection is the same 2 or when it is determined that the same determination is not reliable (step 107 in FIG. 2), and as a result of subject tracking by the image tracking function, the tracking subject is not lost or lost. If the subject recognition information is not reliable, AF lock-on is executed in step 301. In this case, after lens driving is prohibited for a predetermined time, the process returns to step 110 in FIG.

  As a result of focus detection by the automatic focus adjustment (AF) function, is it determined that focus detection is impossible (step 105 in FIG. 2), or even if focus detection is possible, the subject in the AF area in the previous and current focus detection is the same Or when it is determined that the same determination is not reliable (step 107 in FIG. 2), and it is determined that the tracking subject disappears from the shooting screen as a result of subject tracking by the image tracking function. In step 302, it is determined that the composition has been changed by the photographer, and neither AF lock-on nor tracking lock-on is executed in step 302. In the lock-on in the conventional focus adjustment control, the lock-on is applied because the lock-on condition for focus detection by the automatic focus adjustment (AF) function is satisfied. However, as a result of subject tracking by the image tracking function, it has been confirmed that the tracking subject has disappeared outside the shooting screen. Therefore, in this embodiment, it is determined that the composition has been changed by the photographer, and lock-on is not performed. In subsequent step 304, since the photographer has changed the composition, it is necessary to reset and restart the automatic focus adjustment function. For this purpose, scan driving of the photographing lens 1 is executed to search for a new subject.

  As a result of focus detection by the automatic focus adjustment (AF) function, is it determined that focus detection is impossible (step 105 in FIG. 2), or even if focus detection is possible, the subject in the AF area in the previous and current focus detection is the same Or when it is determined that the same determination is not reliable (step 107 in FIG. 2), and further, as a result of subject tracking by the image tracking function, the disappearance of the tracking subject in the shooting screen is determined. In step 303, AF lock-on and tracking lock-on are executed. In this case, both the focus detection lock-on condition by the automatic focus adjustment (AF) function and the subject tracking result lock-on condition by the image tracking function are satisfied, and after the lens driving is prohibited for a predetermined time, Return to step 110 of step 2.

  In the above-described embodiment, a single-lens reflex digital camera has been described as an example. However, the present invention detects a focus adjustment state of a photographing lens in a plurality of focus detection areas set in a photographing screen. An automatic focus adjustment (AF) function that drives the photographic lens to focus based on the defocus amount of the area, and the image of the subject to be tracked in the photographic image is stored as a template image (reference image), and repeated imaging is performed. The image tracking function that tracks the subject to be tracked while searching for the position of the image that is the same or similar to the template image (template matching) in the captured image, and the focus adjustment of the taking lens by the AF function and the image tracking function Suitable for any kind of focus adjustment device and image pickup device as long as the focus adjustment device performs the image adjustment and the image pickup device equipped with the focus adjustment device. It can be.

  In the above-described embodiment, the example in which the image tracking function is realized using the image captured by the photometric element 16 used for exposure control has been described. However, the image tracking function is performed using the image captured by the image capturing element 6 for image acquisition. May be realized. In addition, the image sensor used for the image tracking function includes an image sensor that outputs an image signal and a focus detection signal, in which focus detection pixels that receive a pair of light beams passing through the photographing lens are arranged in the array of the image pickup pixels. It may be used. In this case, the phase difference AF detection element 8 and the focus detection optical system (not shown) described above are not necessary.

  In the above-described embodiments and their modifications, all combinations of the embodiments and the modifications are possible.

  According to the above-described embodiment and its modification, is the composition changed by the photographer depending on how the subject of interest disappears, or has another subject entered or crossed in front of the subject of interest? It is determined whether the photographer has removed the subject of interest from the AF area, and in the case of composition change, even if the lock-on condition based on the focus detection result by the automatic focus adjustment (AF) function is satisfied Lock-on is prohibited. As a result, when the subject is crossed or the AF area is removed, it is possible to reliably lock on and continue to capture the subject of interest, and in the case of a composition change, lens driving is started immediately. The lens operation intended by the photographer can be realized.

DESCRIPTION OF SYMBOLS 1; Shooting lens, 8; Phase difference AF detection element, 10; Defocus calculation part, 12; Lens drive amount calculation part, 13; Lens drive control part, 16; Photometry element, 18;

Claims (7)

Focus detection means for detecting the focus adjustment state of the imaging optical system;
Focus adjusting means for adjusting the focus of the imaging optical system based on the focus adjustment state detected by the focus detecting means;
Imaging means for capturing an image by the imaging optical system;
A recognizing unit that repeatedly recognizes a position of an image of a specific target in an image captured by the imaging unit;
A focus adjustment apparatus comprising: control means for prohibiting focus adjustment by the focus adjustment means based on a state when the position of the target image cannot be recognized by the recognition means. The focus adjustment apparatus according to claim 1,
Whether the target image has disappeared within the range of the image captured by the imaging unit or moved out of the range of the image based on the history of the position of the target image that is repeatedly recognized by the recognition unit A focus adjustment apparatus comprising a determination unit that determines whether or not. The focusing apparatus according to claim 2, wherein
The focus detection means repeatedly detects the focus adjustment state,
The control unit prohibits the focus adjustment by the focus adjustment unit based on a plurality of the history of the focus adjustment state repeatedly detected by the focus detection unit, and performs the focus adjustment based on the determination result by the determination unit. A focusing device characterized by invalidating the prohibition. The focus adjustment apparatus according to claim 3.
The focus adjustment apparatus, wherein the control unit invalidates the prohibition of the focus adjustment when the determination unit determines that the target image has moved out of the range of the image. In the focus adjustment apparatus as described in any one of Claims 2-4,
The determination unit is configured such that, among the positions of the target image repeatedly recognized by the recognition unit, the position of the target image recognized before the target image cannot be recognized is positioned at an end of the range of the image. In this case, it is determined that the target image has moved out of the range of the image. In the focus adjustment apparatus according to any one of claims 1 to 5,
The imaging means is arranged in a plurality of imaging pixels that receive a light beam passing through the imaging optical system and output an image signal corresponding to the image, and an array of the imaging pixels. A focus detection pixel that outputs a signal obtained by receiving a pair of light beams passing through the image optical system;
The focus adjustment device, wherein the focus detection unit detects a focus adjustment state of the imaging optical system based on an output of the focus detection pixel.   An imaging apparatus comprising the focus adjustment apparatus according to claim 1.

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