JP2010107711A - Focal point control device and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that defocus is caused during a period from a releasing operation to the start of photographing in focal point control using a contrast detecting method. <P>SOLUTION: The focal point control device includes: a position detecting means 243 for detecting the position of a focus lens 230; an imaging element 110 that creates image data by exposing at predetermined timing; a focusing state determining means 140 that calculates an evaluation value for automatic focus based on the created image data, and determines the focusing state based on the evaluation value; a focus information-holding means 141 for storing a focusing position at a point of time when the focusing state is determined; and an operating means 130 for receiving an instruction of operation including the releasing operation. Based on the focusing position stored in the focusing state-holding means 141 before the releasing operation is performed, a focusing position for photographing is calculated to perform focusing control. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a focus control device used in an imaging device, and more particularly to a focus control device that responds to a time lag from a release operation to the start of shooting when shooting a moving subject.

In focus control used in a conventional camera, there is a problem that a focus shift occurs due to a time lag that occurs when the camera operates in response to a photographer's operation. As a technique corresponding to such a time lag, there is a technique disclosed in Patent Document 1. In Patent Document 1, in the phase detection method, in response to a problem of defocusing between the time from the start of distance measurement to the completion of range driving (AF time lag) or the time from release switch on to shooting (release time lag), A technique is disclosed in which data on the image plane position after a predetermined time is obtained using a plurality of defocus amount data using a high-order function expression.
JP-A-1-107224

  However, the above-described conventional method is intended for a technique capable of uniquely determining the defocus amount at a certain timing for focus control using a phase detection method.

  On the other hand, in focus control using the contrast detection method, it is necessary to move the lens position in small increments in order to find a focus position where the contrast is maximized, and the conventional method cannot be applied. In focus control using the contrast detection method, there is a problem that the focus is shifted between the release operation and the start of shooting.

  The focus control device of the present invention solves the above-mentioned problem, a focus lens that changes the focus state of a subject image by moving back and forth in the optical axis direction, and a driving unit for driving the focus lens; Position detection means for detecting the position of the focus lens or a mechanism member interlocked with the focus lens, an image sensor for generating image data by exposing at a predetermined timing, and auto-detection based on the generated image data. An evaluation value calculation means for calculating an evaluation value for focus; a focus state determination means for determining a focus state based on the evaluation value; and the position at which the focus state is determined by the focus state determination means Focusing information holding means for storing a focus position as an output of the detecting means, and operating means for receiving an operation instruction including a release operation; Based on the focus position stored in the in-focus state holding means before the release operation is performed, the position of the focus lens at the time of shooting or the mechanism member interlocked with the focus lens is calculated, and the drive means is Control means for controlling.

  With the above configuration, the accuracy of the contrast type autofocus operation can be improved even when the subject is moving.

Hereinafter, an embodiment in which a focus control apparatus of the present invention is applied to a camera will be described in detail with reference to the drawings.
(Embodiment 1)
(1. Configuration)
(1-1. Overview)
FIG. 1 is a block diagram showing a configuration of a camera system 1 according to Embodiment 1 of the present invention. The camera system 1 includes a camera body 100 and an interchangeable lens 200 that can be attached to and detached from the camera body 100. The camera system 1 can perform a contrast autofocus operation based on image data generated by the CCD image sensor 110. The present invention is an invention made to perform a contrast type autofocus operation with higher accuracy.
(1-2. Configuration of camera body)
The camera body 100 includes a CCD image sensor 110, a liquid crystal monitor 120, a camera controller 140, a body mount 150, a power source 160, and a card slot 170.

  The camera controller 140 controls the entire camera system 1 such as the CCD image sensor 110 in response to an instruction from an operation member such as the release button 130. The camera controller 140 transmits a vertical synchronization signal to the timing generator 112. In parallel with this, the camera controller 140 generates an exposure synchronization signal based on the vertical synchronization signal. The camera controller 140 periodically and repeatedly transmits the generated exposure synchronization signal to the lens controller 240 via the body mount 150 and the lens mount 250. The camera controller 140 uses the DRAM 141 as a work memory during control operations and image processing operations.

  The CCD image sensor 110 captures a subject image incident through the interchangeable lens 200 and generates image data. The generated image data is digitized by the AD converter 111. The image data digitized by the AD converter 111 is subjected to various image processing by the camera controller 140. Examples of the various image processing referred to here include gamma correction processing, white balance correction processing, scratch correction processing, YC conversion processing, electronic zoom processing, and JPEG compression processing.

  The CCD image sensor 110 operates at a timing controlled by the timing generator 112. The operation of the CCD image sensor 110 includes a still image capturing operation, a through image capturing operation, and the like. Here, the through image is an image that is not recorded on the memory card 171 after image capturing. The through image is mainly a moving image, and is displayed on the liquid crystal monitor 120 in order to determine a composition for capturing a still image.

  The liquid crystal monitor 120 displays an image indicated by the display image data image-processed by the camera controller 140. The liquid crystal monitor 120 can selectively display both moving images and still images.

  The card slot 170 can be loaded with a memory card 171. The card slot 170 controls the memory card 171 based on the control from the camera controller 140. The memory card 171 can store image data generated by image processing of the camera controller 140. For example, the memory card 171 can store a JPEG image file. The memory card 171 can output image data or an image file stored therein. The image data or image file output from the memory card 171 is subjected to image processing by the camera controller 140. For example, the camera controller 140 expands the image data or image file acquired from the memory card 171 and generates display image data.

  The power supply 160 supplies power for consumption by the camera system 1. The power source 160 may be, for example, a dry battery or a rechargeable battery. Moreover, the power supplied from the outside by the power cord may be supplied to the camera system 1.

The body mount 150 can be mechanically and electrically connected to the lens mount 250 of the interchangeable lens 200. The body mount 150 can transmit and receive data to and from the interchangeable lens 200 via the lens mount 250. The body mount 150 transmits the exposure synchronization signal received from the camera controller 140 to the lens controller 240 via the lens mount 250. Also, other control signals received from the camera controller 140 are transmitted to the lens controller 240 via the lens mount 250. The body mount 150 transmits a signal received from the lens controller 240 via the lens mount 250 to the camera controller 140. The body mount 150 supplies the power received from the power supply 160 to the entire interchangeable lens 200 via the lens mount 250.
(1-3. Configuration of interchangeable lens)
The interchangeable lens 200 includes an optical system, a lens controller 240, and a lens mount 250. The optical system of the interchangeable lens 200 includes a zoom lens 210, an OIS lens 220, and a focus lens 230.

  The zoom lens 210 is a lens for changing the magnification of a subject image formed by the optical system of the interchangeable lens 200. The zoom lens 210 is composed of one or a plurality of lenses. The drive mechanism 211 includes a zoom ring or the like that can be operated by the user, transmits the operation by the user to the zoom lens 210, and moves the zoom lens 210 along the optical axis direction of the optical system. The detector 212 detects the drive amount in the drive mechanism 211. The lens controller 240 can grasp the zoom magnification in the optical system by acquiring the detection result in the detector 212.

  The OIS lens 220 is a lens for correcting blurring of a subject image formed by the optical system of the interchangeable lens 200. The OIS lens 220 moves in a direction that cancels out the blur of the camera system 1, thereby reducing the blur of the subject image on the CCD image sensor 110. The OIS lens 220 is composed of one or a plurality of lenses. The actuator 221 drives the OIS lens 220 in a plane perpendicular to the optical axis of the optical system under the control of the OIS IC 223. The actuator 221 can be realized by a magnet and a flat coil, for example. The position detection sensor 222 is a sensor that detects the position of the OIS lens 220 in a plane perpendicular to the optical axis of the optical system. The position detection sensor 222 can be realized by a magnet and a Hall element, for example. The OIS IC 223 controls the actuator 221 based on the detection result of the position detection sensor 222 and the detection result of a shake detector such as a gyro sensor. The OIS IC 223 obtains the detection result of the shake detector from the lens controller 240. Further, the OIS IC 223 transmits a signal indicating the state of the optical image blur correction process to the lens controller 240.

  The focus lens 230 is a lens for changing the focus state of the subject image formed on the CCD image sensor 110 in the optical system. The focus lens 230 is composed of one or a plurality of lenses.

  The focus motor 233 drives the focus lens 230 to advance and retract along the optical axis of the optical system based on the control of the lens controller 240. Thereby, the focus state of the subject image formed on the CCD image sensor 110 by the optical system can be changed. In the first embodiment, the focus motor 233 can be a DC motor. However, the present invention is not limited to this, and can be realized by a stepping motor, a servo motor, an ultrasonic motor, or the like.

  The first encoder 231 and the second encoder 232 are encoders that generate signals indicating the driving state of the focus lens 230. The first encoder 231 and the second encoder 232 can be realized by, for example, a rotor and a photocoupler attached to the rotation shaft of the focus motor 233. Here, the rotor is a disk body having holes opened at predetermined intervals. The photocoupler emits detection light from one surface of the rotor and receives light from the other surface. Therefore, when the rotor rotates, the ON / OFF state of the photocoupler switches between each other. The lens controller 240 has a counter 243 provided therein, and this counter 243 counts the number of ON / OFF state switching from the photocoupler. The first encoder 231 and the second encoder 232 are out of phase. Therefore, it is possible to determine the moving direction of the focus lens 230 when the state of the first encoder 231 is switched from OFF to ON. That is, the state of the second encoder 232 when the state of the first encoder 231 is switched from OFF to ON includes an ON state and an OFF state. Therefore, when the state of the first encoder 231 is switched from OFF to ON when the state of the second encoder 232 is ON, the counter 243 determines that this is normal rotation and counts it as “+1”. When the state of the encoder 232 is OFF and the state of the first encoder 231 is switched from OFF to ON, this is determined as reverse rotation and counted as “−1”. By adding this count number, the lens controller 240 can grasp the amount of movement of the focus lens 230.

The lens controller 240 controls the entire interchangeable lens 200 such as the OIS IC 223 and the focus motor 233 based on the control signal from the camera controller 140. In addition, signals are received from the detector 212, the OIS IC 223, the first encoder 231, the second encoder 232, and the like, and transmitted to the camera controller 140. The lens controller 240 performs the transmission / reception with the camera controller 140 via the lens mount 250 and the body mount 150. The lens controller 240 uses the DRAM 241 as a work memory during control. The flash memory 242 stores a program and parameters used when the lens controller 240 is controlled.
(1-4. Correspondence with Configuration of the Present Invention)
The focus motor 233 is an example of the driving means of the present invention. The configuration including the first encoder 231, the second encoder 232, and the counter 243 is an example of the position detection unit of the present invention. The CCD image sensor 110 is an example of an image sensor of the present invention. The camera controller 140 is an example of an evaluation value calculation unit of the present invention. The camera controller 140 is an example of a focus state determination unit of the present invention. The DRAM 141 is an example of the focus information holding unit of the present invention. The release button 130 is an example of the operation means of the present invention. The camera controller 140 is an example of the control means of the present invention. The OIS IC 223 is an example of a camera shake detection unit of the present invention.
(2. Operation)
(2-1. Imaging preparation operation)
First, the operation of the camera system 1 for preparation for imaging will be described. FIG. 2 is a diagram illustrating signal transmission / reception for explaining the imaging preparation operation of the camera system 1.

  When the user turns on the power supply of the camera body 100 with the interchangeable lens 200 mounted on the camera body 100, the power supply 160 supplies power to the interchangeable lens 200 via the body mount 150 and the lens mount 250 ( S11). Next, the camera controller 140 requests authentication information of the interchangeable lens 200 from the lens controller 240 (S12). Here, the authentication information of the interchangeable lens 200 includes information regarding whether or not the interchangeable lens 200 is mounted and information regarding whether or not an accessory is mounted. The lens controller 240 responds to the lens authentication request from the camera controller 140 (S13).

  Next, the camera controller 140 requests the lens controller 240 to perform an initialization operation (S14). In response to this, the lens controller 240 performs initialization operations such as resetting the aperture and resetting the OIS lens 220. Then, the lens controller 240 returns to the camera controller 140 that the lens initialization operation has been completed (S15).

  Next, the camera controller 140 requests lens data from the lens controller 240 (S16). The lens data is stored in the flash memory 242. Therefore, the lens controller 240 reads the lens data from the flash memory 242 and sends it back to the camera controller 140 (S17). Here, the lens data is characteristic values unique to the interchangeable lens 200 such as a lens name, an F number, and a focal length.

  When the camera controller 140 grasps the lens data of the interchangeable lens 200 attached to the camera body 100, the camera controller 140 is ready for imaging. In this state, the camera controller 140 periodically requests lens state data indicating the state of the interchangeable lens 200 from the lens controller 240 (S18). The lens state data includes, for example, zoom magnification information by the zoom lens 210, position information of the focus lens 230, aperture value information, and the like. In response to this request, the lens controller 240 returns the requested lens state data to the camera controller 140 (S19).

  In this state, the camera system 1 can operate in a control mode in which an image indicated by the image data generated by the CCD image sensor 110 is displayed on the liquid crystal monitor 120 as a through image. This control mode is called live view mode. In the live view mode, the through image is displayed as a moving image on the liquid crystal monitor 120, so that the user can determine the composition for capturing a still image while viewing the liquid crystal monitor 120. The user can select whether to use the live view mode. In addition to the live view mode, another control mode that can be selected by the user is a control mode that guides the subject image from the interchangeable lens 200 to an optical viewfinder (not shown). In order to realize this control mode, a movable mirror or the like for guiding a subject image to an optical viewfinder (not shown) is required. A contrast method is suitable as a method of autofocus operation in the live view mode. This is because in the live view mode, the image data is constantly generated by the CCD image sensor 110, so that it is easy to perform a contrast-type autofocus operation using the image data.

When performing the contrast autofocus operation, the camera controller 140 requests contrast AF data from the lens controller 240 (S20). The contrast AF data is necessary for the contrast autofocus operation, and includes, for example, a focus drive speed, a focus shift amount, an image magnification, and contrast AF availability information.
(2-2. Contrast autofocus operation)
With the above, the contrast-type autofocus operation for the subject with movement in the camera system 1 ready for imaging will be described with reference to FIGS. 3, 4, and 5. FIG. 3 is a flowchart for explaining the autofocus operation. FIG. 4 is a timing chart for the autofocus operation. FIG. 5 is a diagram illustrating a temporal change in the position of the focus lens during the autofocus operation.

  Assume that the camera controller 140 is operating in the live view mode. In this state, the camera controller 140 periodically generates a vertical synchronization signal as shown in FIG. 4A. In parallel with this, the camera controller 140 generates an exposure synchronization signal as shown in FIG. 4C based on the vertical synchronization signal. This is because the camera controller 140 knows in advance the exposure start timing and the exposure end timing with reference to the vertical synchronization signal, so that the exposure synchronization signal can be generated. The camera controller 140 outputs a vertical synchronization signal to the timing generator 112 and outputs an exposure synchronization signal to the lens controller 240. The lens controller 240 acquires position information of the focus lens 230 in synchronization with the exposure synchronization signal. This point will be described later.

  The timing generator 112 periodically generates a readout signal of the CCD image sensor 110 and an electronic shutter drive signal as shown in FIG. 4B based on the vertical synchronization signal. The timing generator 112 drives the CCD image sensor 110 based on the readout signal and the electronic shutter drive signal.

  That is, the CCD image sensor 110 reads out pixel data generated by a large number of photoelectric conversion elements (not shown) in the CCD image sensor 110 to a vertical transfer unit (not shown) according to the read signal. In the first embodiment, the read signal and the vertical synchronization signal coincide with each other. However, this is not an essential matter for implementing the present invention. That is, the vertical synchronization signal and the readout signal may be shifted. In short, it is only necessary that the vertical synchronization signal and the readout signal are synchronized.

  Further, the CCD image sensor 110 performs an electronic shutter operation according to the electronic shutter drive signal. Thereby, the CCD image sensor 110 can sweep out unnecessary charges to the outside. The electronic shutter drive signal is composed of a group of a plurality of signals that are periodically transmitted within a short time. For example, 10 signals are transmitted as a group. The CCD image sensor 110 performs one electronic shutter operation on one signal while a group of electronic shutter drive signals are transmitted. If the number of signals included in the group of electronic shutter drive signals is increased, the charge accumulated in the CCD image sensor 110 can be surely swept out. However, the driving method of the CCD image sensor 110 becomes complicated.

  Therefore, the CCD image sensor 110 sweeps out the electric charge by the electronic shutter drive signal and reads out the pixel data to the vertical transfer unit (not shown) by the read signal, so that from the last signal of the group of electronic shutter drive signals to the vertical synchronization signal. During the period, an exposure operation is performed for the image data for the through image (see FIG. 4C).

  In the above state, the camera controller 140 monitors whether or not the release button 130 is half-pressed. In FIG. 4, it is assumed that the release button 130 is half-pressed at time t1. Then, as shown in FIG. 4D, the camera controller 140 transmits an AF start command to the lens controller 240. The AF start command is a command indicating that the contrast autofocus operation is started.

  The camera controller 140 transmits a hill climbing start point movement command to the lens controller 240 at time t2. This command indicates to which position the focus lens 230 is moved when the contrast-type autofocus operation is started, and in which direction the focus lens 230 is moved during detection of the AF evaluation value. In response to this, the lens controller 240 controls the focus motor 233. The focus motor 233 moves the focus lens 230 to the position indicated by the hill-climbing start point movement command under the control of the lens controller 240 (S301).

  Next, the camera controller 140 transmits a hill climbing start command to the lens controller 240 at time t3 (S302). The lens controller 240 starts periodic transmission of the position information of the focus lens 230.

  In this period, as shown in FIG. 4G, the lens controller 240 drives the focus motor 233 in accordance with an instruction from the camera controller 140, and the number of pulses of the counter 243 when the exposure synchronization signal is switched from OFF to ON. And the number of pulses of the counter 243 when the exposure synchronization signal is switched from ON to OFF are sequentially stored in the DRAM 241 (S303).

  Next, the camera controller 140 periodically transmits a lens position information acquisition command to the lens controller 240. In response to this, the lens controller 240 transmits the number of pulses stored in the DRAM 241 to the camera controller 140 in a state associated with the exposure synchronization signal (S304).

  On the other hand, the CCD image sensor 110 is exposed during the exposure period and transmits the generated image data to the camera controller 140 via the AD converter 111 (S305).

  The camera controller 140 calculates an evaluation value for autofocus operation (hereinafter referred to as an AF evaluation value for convenience) based on the received image data. Specifically, a method for obtaining an AF evaluation value by obtaining a luminance signal from image data generated by the CCD image sensor 110 and integrating high-frequency components in the screen of the luminance signal is known. The calculated AF evaluation value is stored in the DRAM 141 in a state associated with the exposure synchronization signal. The lens position information acquired from the lens controller 240 is also associated with the exposure synchronization signal. Therefore, the camera controller 140 can store the AF evaluation value in association with the lens position information (S306). For example, the AF evaluation value calculated using the image data exposed in the period b in FIG. 4C is associated with the average value of the position of the focus lens 230 at time t4 and the position of the focus lens 230 at time t5. Saved. In this way, the AF evaluation value calculated using the image data exposed in the period b in FIG. 4C is stored in the DRAM 141 at time t6.

  Next, the camera controller 140 monitors whether or not the in-focus point has been extracted based on the AF evaluation value stored in the DRAM 141 (S307). Specifically, the position of the focus lens 230 at which the AF evaluation value is a maximum value is extracted as a focal point. If the focal point cannot be extracted, the process returns to step S303. Then, the operations from step S303 to step S306 are repeated until the focal point can be extracted.

  In step S307, when the camera controller 140 can extract the focal point, the camera controller 140 stores the focal point position and the focusing time in another area on the DRAM 141 as focusing information. Also, the moving body speed is calculated using the focus information that has already been stored. A method for calculating the moving body speed will be described later.

  Thereafter, the camera controller 140 sends a range moving direction reversal command to the lens controller 240. The lens moving direction reversal command is a command for reversing the moving direction of the focus lens 230 from the previous moving direction. The lens controller 240 drives the focus motor 233 in accordance with the moving direction reversal command to reverse the moving direction of the focus lens 230. Thereafter, the camera controller 140 repeats the operations from step S303 to step S309 until the full press of the release button 130 is detected.

  The movement of the focus lens 230 at this time will be described in more detail with reference to FIG. In FIG. 5, the focus lens 230 starts mountain climbing from the lens position p1 at time t11. The camera controller 140 sequentially stores AF evaluation values in association with lens position information. When the camera controller 140 moves to the lens position p3 and time t13, the camera controller 140 detects that the AF evaluation value is the maximum value at the lens position p2, and stores the position p2 and time t12 of the focus lens 230 as the focal point. . Thereafter, the lens controller 240 receives the moving direction inversion command from the camera controller 140 and moves the focus lens 230 in the reverse direction. The camera controller 140 detects that the AF evaluation value becomes a maximum value at the lens position p4 at the lens position p5 and time t15, and stores the position p4 and time t14 of the focus lens 230 as a focal point. In this way, the camera controller 140 moves the focus lens 230 while sequentially reversing and extracts the focal point.

  Next, a method for detecting the moving body speed will be described. The camera controller 140 extracts and stores the lens position p6 and time t16 of the focus lens 230 as a focal point at the lens position p7 and time t17. At this time, the moving body speed v2 at the focal point p2 is calculated from the inclination using the lens position p2, the time t12, the lens position p6, and the time t16, and is stored on the DRAM 141 together with the focusing information of the focal point p2. .

  Here, the camera controller 140 calculates the moving body speed using the adjacent focal point obtained by moving the focus lens 230 in the same direction, but the present invention is not limited to this, and the moving direction is not limited thereto. Regardless, the moving object speed may be obtained by using two adjacent focal points.

  Next, processing after the release button 130 is fully pressed will be described. The camera controller 140 monitors whether or not the release button 130 has been fully pressed, and when it is detected, the camera controller 140 uses the focus information on the DRAM 141 to predict the focus position during actual shooting (S311).

  A method in which the camera controller 140 predicts the in-focus position using the in-focus information will be described with reference to FIG. In FIG. 6, it is assumed that the release button 130 is fully pressed at time t27. The camera controller 140 predicts the moving body speed after the release button 130 is fully pressed using the moving body speed at the focal point held on the DRAM 141. As a method for calculating the predicted moving body speed v, the average value of the moving body speeds at the focal point shown below is used.

v = (v1 + v2 + v3 + v4 + v5 + v6) / 6
Here, when calculating the predicted moving body speed v, the average value of the six in-focus points is taken out of the in-focus moving body speeds immediately before the release button 130 is fully pressed, but it is not necessary to be 6. Any number is acceptable. Moreover, although the predicted moving body speed was calculated | required by the average value of the moving body speed of the last in-focus, you may calculate | require using another arithmetic expression.

  The camera controller 140 obtains the moving object predicted in-focus position p28 by the following equation using the moving object speed v obtained in this way. Here, td (= t28-t27) is a shutter time lag, which is the time required from when the release button 130 is fully pressed until shooting starts. td is a value uniquely determined in the camera system 1 in which the camera body 100 and the interchangeable lens 200 are combined.

p28 = p27 + v × td
The camera controller 140 transmits a focus position movement command to the lens controller 240 in order to move the focus lens 230 to the moving object predicted focus position p28 thus obtained. The focus position movement command is a command indicating from which direction to which position the focus lens 230 is moved. The lens controller 240 drives the focus motor 233 according to the focus position movement command. When the movement to the in-focus point is completed, the camera controller 140 starts exposure and shoots the subject. Image data generated by the image processing of the camera controller 140 is stored in the memory card 171.

  As described above, in the autofocus operation for a moving subject, it is assumed that the moving body speed of the subject after the release operation is predicted using the focus information stored before shooting, and the subject moves at the predicted moving body speed. By focusing on the position after the movement, it is possible to focus with high accuracy.

In the first embodiment, the autofocus operation is started after the release button 130 is half-pressed. However, the present invention is not limited to this. Regardless of the operation of the release button 130, the autofocus operation is always performed on the subject. The present invention can also be applied to a form that performs a focus operation.
(Embodiment 2)
As described above, in the first embodiment, a description has been given of a mode in which an autofocus operation is performed on a subject with movement after the release button 130 is half-pressed. However, in the second embodiment, an autofocus operation is performed. A case where camera shake occurs during the course will be described. The camera system according to Embodiment 2 of the present invention has the same configuration as that of the camera system 1 according to Embodiment 1, and will be described below with reference to the block diagram shown in FIG.

  FIG. 7 is a diagram illustrating a temporal change in the position of the focus lens when a camera shake occurs during the contrast-type autofocus operation of the camera system 1 according to the second embodiment.

  When the camera controller 140 detects half-pressing of the release button 130, the camera controller 140 performs the autofocus operation shown in S303 to S309 in FIG. 3 described in the first embodiment, and stores the extracted focus information on the DRAM 141. When the lens controller 240 is notified from the OIS IC 223 that a camera shake exceeding the correctable amount has occurred, the lens controller 240 notifies the camera controller 140 of the fact. When the camera controller 140 detects a camera shake at time t31 by this notification, the autofocus operation shown in S303 to S309 in FIG. Further, the focus information stored on the DRAM 141 is erased.

  In this way, when camera shake exceeding the correctable amount occurs, by stopping the autofocus operation, it is possible to stop the useless focusing operation in a situation where the focus control is difficult, and to reduce battery consumption, It is possible to avoid extracting an erroneous in-focus point. Further, by erasing the focus information on the RAM 141, when the autofocus operation is started again after the camera shake is settled, the focus information with different shooting conditions before the occurrence of the camera shake is used, and the focus by the incorrect moving object prediction is used. Calculation of the position can be avoided.

Thereafter, when the lens controller 240 is notified by the OIS IC 223 that the camera shake has settled and correction is possible, the lens controller 240 notifies the camera controller 140 of this fact. When the camera controller 140 detects that the camera shake has been settled by this notification, the autofocus operation indicated by S303 to S309 in FIG. The subsequent photographing operation is the same as that of the first embodiment, and the description thereof is omitted.
(Other embodiments)
As described above, Embodiments 1 and 2 have been described as embodiments of the present invention. However, the present invention is not limited to these. Therefore, other embodiments of the present invention will be described collectively in this section.

  In the first and second embodiments of the present invention, the configuration including the zoom lens 210 and the OIS lens 220 is illustrated, but these are not essential configurations of the present invention. In other words, the present invention can be applied to a camera system equipped with a single focus lens that does not have a zoom function, and can also be applied to a camera system equipped with an interchangeable lens that does not have a camera shake correction function. It is. In a camera system equipped with an interchangeable lens that does not have a camera shake correction function, camera shake can be detected using motion detection means or the like.

  In the first and second embodiments of the present invention, the camera body that does not include the movable mirror is illustrated, but the present invention is not limited to this. For example, a movable mirror may be provided in the camera body, or a prism for separating the subject image may be provided. Moreover, the structure provided with a movable mirror not in a camera body but in an adapter may be sufficient. In a camera system consisting of a camera body with a movable mirror, the shutter time lag is larger than a camera system consisting of a camera body without a movable mirror because the movable mirror is retracted after the release operation and shooting starts. .

  In the first and second embodiments, the description has been made using the interchangeable lens camera system. However, the present invention is not limited to this, and can be applied to a camera in which a camera body and a lens are integrated.

  In Embodiments 1 and 2 of the present invention, the position of the focus lens 230 is not detected directly, but is detected indirectly by detecting the rotation angle of the rotation shaft of the focus motor 233. As described above, in the present invention, the position of the focus lens 230 may be detected directly, or may be detected indirectly by detecting the position of the mechanism member interlocked with the focus lens 230. For example, how many pulses of the drive output of the focus motor 233 are sent may be managed by software or a dedicated IC, and used as position detection means. In short, it is only necessary that the position of the focus lens can be specified as a result.

  In Embodiments 1 and 2 of the present invention, a camera system not equipped with a phase difference detection sensor has been exemplified. However, the present invention is not limited to such an embodiment. A phase difference detection sensor may be mounted so that a phase difference type autofocus operation and a contrast type autofocus operation can be selectively executed. In this case, the present invention is applicable when a contrast type autofocus operation is being performed.

  In Embodiment 1 of the present invention, the exposure synchronization signal of the CCD image sensor 110 is used as the timing signal of the present invention. However, the present invention is not limited to this. For example, a vertical synchronization signal and an electronic shutter drive signal for the CCD image sensor 110 may be transmitted to the lens controller 240 as timing signals. Thereby, since the camera controller 140 does not need to transmit an exposure synchronization signal, control can be facilitated. However, in this case, it is necessary to notify the lens controller 240 of the specifications of the electronic shutter drive signal (such as the transmission interval and the number of transmissions within one group) in advance. The lens controller 240 reads the pulse value of the counter 243 based on the electronic shutter drive signal and the vertical synchronization signal according to the notified specification.

  The present invention can be applied to an interchangeable lens camera system. Specifically, it can be applied to a digital still camera or a movie.

1 is a block diagram showing a configuration of a camera system according to Embodiments 1 and 2 of the present invention. The figure for demonstrating the imaging preparation operation | movement of the camera system which concerns on Embodiment 1 and 2 of this invention Flowchart for explaining the contrast-type autofocus operation of the camera system according to Embodiment 1 of the present invention. Timing chart for explaining the contrast-type autofocus operation of the camera system according to Embodiment 1 of the present invention. The figure showing the time change of the lens position of the focus lens which concerns on Embodiment 1 of this invention. The figure explaining the moving body prediction of the focus position of the focus lens which concerns on Embodiment 1 of this invention. The figure showing the time change of the lens position of the focus lens which concerns on Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Camera system 100 Camera body 110 CCD image sensor 112 Timing generator 130 Release button 140 Camera controller 200 Interchangeable lens 230 Focus lens 231 1st encoder 232 2nd encoder 233 Focus motor 240 Lens controller

Claims (5)

A focus lens that changes the focus state of the subject image by moving back and forth in the direction of the optical axis;
Driving means for driving the focus lens;
Position detecting means for detecting a position of the focus lens or a mechanism member interlocked with the focus lens;
An image sensor that generates image data by exposing at a predetermined timing;
An evaluation value calculating means for calculating an evaluation value for autofocus based on the generated image data;
In-focus state determination means for determining an in-focus state based on the evaluation value;
In-focus information holding means for storing a focus position that is an output of the position detecting means at the time when the in-focus state is determined by the in-focus state determining means;
An operation means for receiving an operation instruction including a release operation;
Based on the focus position stored in the in-focus state holding means before the release operation is performed, the position of the focus lens at the time of shooting or the mechanism member linked to the focus lens is calculated, and the drive means is Control means for controlling;
A focus control device. The control means calculates the moving body speed of the subject from the release operation to photographing based on the focus position of the in-focus state holding means, and based on the moving body speed, the mechanism member interlocked with the focus lens or the focus lens The focus control device according to claim 1, wherein the position of the focus control device is calculated. The control unit calculates a moving body speed at the focus position of the in-focus state holding unit, and calculates the moving body speed of the subject from the release operation to photographing by averaging the calculated moving body speeds. The focus control device described. Provided with a camera shake detecting means for detecting camera shake,
The control means controls the stop or restart of the evaluation value calculation means and the focus state determination means based on the detection result by the camera shake detection means,
The focus control apparatus according to claim 1, wherein the focus position stored in the focus information holding unit is deleted. An imaging device comprising the focus control device according to claim 1.

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