JP2007033811A - Position controller, imaging device, and position control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce lens noise in automatic focusing operation in a lens driving system using a flat coil type voice coil motor for an actuator for a focusing lens of an imaging device. <P>SOLUTION: A strike sound due to chattering of a lens holding part is reduced by suppressing a motor thrust at the start/end of movement by performing control so that moving speeds at the start/end of movement are limited to less than specified upper-limit values. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for controlling a position control object.

  In recent years, in an imaging apparatus such as a consumer video camera, a reduction in size and weight for improving portability has become an important factor for improving the product merchandise. In order to reduce the size of the imaging device, it is essential to reduce the size of the lens unit, which is one of the components of the imaging device.

  In addition to a lens that is an imaging optical system, the lens unit includes several actuators such as an actuator that drives a focus adjustment lens (hereinafter also referred to as a focus lens) for performing autofocusing. Therefore, further miniaturization is required for these actuators and their peripheral drive mechanisms.

  As a lens driving actuator, a stepping motor or a linear motor called a voice coil motor has been conventionally used. A stepping motor is an actuator that generates a rotational motion. Therefore, a drive mechanism such as a drive screw or a rack for linearly driving the focus lens in the optical axis direction is required. On the other hand, the voice coil motor is an actuator that generates a linear motion. Therefore, the drive mechanism can be simplified, which is more advantageous for downsizing. For this reason, the use of a voice coil motor as a lens driving actuator has been conventionally performed (see, for example, Patent Document 1).

  Hereinafter, a lens driving mechanism using a voice coil motor will be described. FIG. 4 is a diagram schematically showing the structure of a voice coil motor conventionally used for lens driving. A drive magnet 109 is disposed inside the U-shaped yoke 110b. A drive coil 111 is arranged so as to surround the yoke 110 b so as to face the drive magnet 109. The drive magnet 109 is magnetized in the vertical direction toward the paper surface. Therefore, a vertical magnetic field is generated inside the U-shaped yoke 110b as shown in the drawing. The direction of this magnetic field is substantially parallel inside the yoke. This is because the yoke 110b has a closed structure. Further, when the drive coil 111 is energized, a thrust in the left-right direction is generated in the coil toward the paper surface. This is due to the interaction with the magnetic field in the vertical direction because the current flows in the direction perpendicular to the paper surface when the drive coil 111 is energized.

  FIG. 5 is a diagram showing a lens holding structure when the voice coil motor is used for driving a focus lens of an image pickup apparatus. Here, the optical axis of the optical system and the lens driving direction are illustrated in a direction perpendicular to the paper surface. The yoke 110b, the drive magnet 109, and the two bars 106 and 107 are fixed to a lens barrel (not shown). On the other hand, the focus lens 102 is held so as to be movable in a direction perpendicular to the paper surface with respect to the bars 106 and 107 via a sleeve portion 104 and a U groove 105 provided in the lens holding member 103. A driving coil 111 is fixed to the lens holding member 103, and the lens is driven in a direction perpendicular to the paper surface by energizing the driving coil 111.

  The above is an example of a lens driving mechanism using a voice coil motor. In recent years, a flat coil type voice coil motor using a flat yoke as shown in FIG. 6 has also been used for lens driving. It is aimed at further miniaturization. FIG. 6 schematically shows the structure of a flat coil type voice coil motor. The drive magnet 109 is disposed on a flat yoke 110a. The drive coil 111 is wound and disposed along a plane parallel to the drive magnet 109. The drive magnet 109 is magnetized in the horizontal direction in the figure, and a vertical magnetic field in the figure is generated around the drive magnet 109. However, in the vicinity of the center of the drive magnet 109, a magnetic field curved in a U shape from the N pole toward the S pole is generated. Near the end, a magnetic field is generated that spreads in the left-right direction and returns to the yoke. This is because the yoke 110a is not closed. When the drive coil 111 is energized, a thrust in the horizontal direction in the figure is generated in the coil due to the interaction with the magnetic field in the vertical direction. This is because the current flows in the direction perpendicular to the paper surface when the drive coil 111 is energized. This flat coil type voice coil motor is effective by reducing the size of the lens. This is because since the yoke is a flat plate, the actuator portion can be made thinner than the voice coil motor of the U-shaped yoke.

  Next, driving of the focus lens in autofocus (AF) control will be described. A so-called TV-AF system is often used in autofocus control of an imaging apparatus such as a video camera or a digital camera. This TV-AF system generates a signal called an AF evaluation value from a signal obtained by extracting a predetermined high-frequency component of a captured video signal, and controls the focusing lens so that the AF evaluation value is maximized. It is. In this system, lens driving is frequently performed such that the focus lens is repeatedly driven and stopped by a minute movement amount in the optical axis direction (for example, Patent Document 2). This is to determine the direction in which the AF evaluation value increases. This will be described below.

  FIG. 7 is an example of an AF evaluation value when a normal subject image is captured. As shown in FIG. 7, the AF evaluation value increases as the focus lens approaches the in-focus position, and becomes the maximum at the in-focus position. Here, for example, in an NTSC video signal, an AF evaluation value is obtained for each image of one field generated at an interval of 1/60 seconds (1 Vsync). This is because the AF evaluation value is updated every time a video signal is generated for one screen. On the other hand, in the TV-AF method, a change in the AF evaluation value is detected while moving the focus lens in the optical axis direction, and a focus lens position (focus position) where the AF evaluation value is maximized is searched. This is because the focus position of the focus lens cannot be known in advance in the TV-AF method. That is, when the direction of the in-focus position is not known, the focus lens is driven to move by a minute distance in the optical axis direction (minute drive operation), and the direction in which the AF evaluation value increases is determined. When the direction of the in-focus position is determined by the minute driving operation, the detection of the change in the AF evaluation value is continued while the focus lens is driven at a high speed in that direction. If the focus lens is returned to the focus position where the AF evaluation value has changed from increasing to decreasing, the image can be focused by focusing on the subject. This is because the focus position where the AF evaluation value has changed from increasing to decreasing is the in-focus position. In particular, in moving image shooting, the focus of the video is maintained by repeatedly executing such focus control. This is because the subject changes from moment to moment, and the in-focus position also changes accordingly.

  In the high-speed driving of the focus lens after the direction of the in-focus position is determined as described above, if the moving speed of the lens is too high, the in-focus position greatly passes until a decrease in the AF evaluation value is detected. Sometimes. That is, after the image is once focused, it is blurred and refocused, resulting in extremely poor quality. In order to prevent this, it is necessary to control the moving speed so that the moving speed of the lens becomes an appropriate speed. When the actuator of the focus lens is a stepping motor, the moving speed of the lens can be directly controlled by controlling the drive pulse output period. However, in lens driving using a voice coil motor, it is difficult to directly control the speed. This is because lens feedback using a voice coil motor is generally position feedback control. In this regard, it is possible to perform pseudo speed control by using the following technique. That is, when the target speed of the lens is set to 10 mm / sec, for example, if the control cycle of the position control is 1 msec, the lens is moved by 10 [mm / sec] × 1 [msec] = 10 μm every control cycle. It will be good. Therefore, if the target position is sequentially updated by 10 μm every control cycle, and the position control is performed so that the lens moves to the target position each time, the average moving speed of the lens substantially coincides with the target speed. Speed control.

  Next, the operation of the lens in the minute driving operation will be described in detail below with reference to FIG. In the minute driving operation, as shown in FIG. 8, the focus lens is driven by a minute movement amount in a certain direction, and when the AF evaluation value increases, the driving direction is not changed, and when the AF evaluation value decreases, the driving direction is changed. Invert. When driving in the same direction continues for a predetermined number of times, it is assumed that the in-focus position is in that direction, and shifts to high speed driving. Here, as shown in FIG. 8, after moving the focus lens by a minute movement amount, the lens is stopped for at least 1 Vsync. Charges are accumulated in an image sensor such as a CCD or CMOS, and an AF evaluation value is generated from the video signal in the next field. This is because the AF evaluation value is obtained every one field interval (1 Vsync) as described above. The AF evaluation value is processed by a microcomputer in the next field, the direction is determined, and the next drive direction is determined. For this reason, in the minute driving operation, the focus lens moves every time the AF evaluation value is obtained.

Here, it is desirable to drive and stop the lens so that the movement of the lens is completed within 1 Vsync. This is due to the following reason. That is, in the AF control as described above, after the movement of the focus lens is completed, at least the 1Vsync lens is stopped to generate an AF evaluation value, and the next drive direction is determined. Here, when the movement of the focus lens extends over a plurality of Vsyncs, since the driving direction of the focus lens cannot be determined while waiting for the lens movement to be completed, the AF control cycle is extended. As described above, since the number of continuous driving times in the same direction is used in the transition from the minute driving operation to the high speed driving, the transition to the high speed driving becomes slow when the AF control period is extended, and the focus state is shifted from the blurred state. This is because the product performance deteriorates, for example, the time required for the process becomes longer.
JP-A-10-164417 JP-A-10-051677 (FIG. 13)

  The prior art relating to the flat coil type voice coil motor for miniaturizing the lens and the minute driving operation of the focus lens in the imaging apparatus such as a video camera or a digital camera have been described above. However, when a flat coil type voice coil motor is used as an actuator for a focus lens and the lens is finely driven by autofocus control, there is a problem in that a rattling noise is generated from the lens. This noise is particularly noticeable when the focus lens is near the end of the movable range. When such noise is generated, not only the quality of the product is impaired, but also the product performance is significantly impaired, for example, the noise is superimposed on the audio of the video signal recorded by the imaging device.

  An object of the present invention is to suppress the generated noise and to make the lens unit and thus the image pickup apparatus compact.

  In order to achieve the above object, the technical idea of the present invention is to control the position of the position control object by controlling the thrust of the driving means that drives the position control object based on the position of the position control object, The movement target position of the position control object is updated between the start of movement of the position control object and the stop of movement.

  As described above, according to the present invention, it is possible to suppress noise generated at the start and end of the movement of the position control object, and to realize downsizing of the lens unit, and thus the imaging device, It is possible to ensure both product performance and quality related to lens driving noise.

  Embodiments using the position control technique of the present invention will be described below.

(Configuration of position control device)
FIG. 1 is a diagram illustrating a configuration of position control of a focus control lens (focus lens) of an imaging apparatus.

  First, components related to position control of the focus lens 102 which is a position control object in the present embodiment will be described. In addition to the focus lens 102, the lens unit 101 is generally provided with a fixed lens, a movable lens for zooming, a diaphragm mechanism, and the like, but the illustration is omitted for simplicity.

  The focus lens 102 is held by a lens holding member 103, and the lens holding member 103 is provided with a hollow sleeve 104 and a U groove 105. The sleeve 104 and the U groove 105 are slidable along the sleeve bar 106 and the U groove bar 107 in the optical axis direction (left-right direction in the figure), respectively. The sleeve bar 106 and the U-groove bar 107 are fixed to the lens barrel 108. With the above mechanism, the focus lens 102 is held in a state in which it can move in the optical axis direction with respect to the lens barrel 108.

  A driving magnet 109 and a flat plate yoke 110a are fixed to the lens barrel 108. On the other hand, a drive coil 111 is fixed to the lens holding member 103. The drive magnet 109, the drive coil 111, and the yoke 110a are combined to form a flat coil type voice coil motor. As a result, when a current is passed through the drive coil 111, the focus lens 102 is linearly driven in the optical axis direction.

  A scale 112 is fixed to the lens holding member 103, and a position sensor 113 is fixed to the lens barrel 108. The position of the focus lens 102 can be detected by detecting a predetermined magnetic pattern, optical pattern, or the like on the scale 112 by the position sensor 113. This is because the relative position of the position sensor 113 and the scale 112 changes as the focus lens 102 moves in the optical axis direction.

  A position detection signal output from the position sensor 113 is input to the camera / AF microcomputer 114. The camera / AF microcomputer 114 is a microcomputer that performs lens position control, autofocus control, and the like. The camera / AF microcomputer 114 executes the TV-AF control calculation based on a signal from an AF signal processing circuit 115 described later, and calculates a target position for moving the focus lens every time an AF evaluation value is obtained. . The camera / AF microcomputer 114 performs a position feedback control calculation for matching the target position with the position of the focus lens 102 obtained from the output of the position sensor 113. Further, the camera / AF microcomputer 114 outputs a drive signal to the voice coil motor drive circuit 116. The voice coil motor drive circuit 116 causes a current to flow through the drive coil 111 in response to a drive signal from the camera / AF microcomputer 114. As a result, the voice coil motor drive circuit 116 drives the focus lens 102 to move it to the target position.

(Components of imaging function and AF control)
Next, components related to the imaging function and autofocus control of the imaging apparatus according to the present embodiment will be described.

  Incident light from the subject passes through the focus lens 102 and forms an image on the image sensor 117. The image sensor 117 is a photoelectric conversion element such as a CCD or a CMOS, and converts a subject image into an electric signal. The electric signal is read and amplified by the CDS / AGC circuit 118 and input to the camera signal processing circuit 119. The camera signal processing circuit 119 performs predetermined video signal processing, and converts the input signal into a signal corresponding to the recording device 120 and the monitor device 121. The recording device 120 records the subject image on a recording medium (magnetic tape, optical disk, semiconductor memory, etc.). The monitor device 121 displays a subject image on an electronic viewfinder, a liquid crystal panel, or the like.

  On the other hand, the output of the CDS / AGC circuit 117 is input to the AF signal processing circuit 115, and an AF evaluation value signal used for focus detection is extracted. The AF evaluation value signal is input to the camera / AF microcomputer 114 as described above and used for TV-AF control calculation. The lens position control process executed according to this result is as described above.

(Noise generation mechanism)
Here, the noise generation mechanism described above will be examined. FIG. 9 is a diagram showing a state where the drive coil 111 is in the vicinity of the end of the movable range of the lens that is the position control target in the flat coil type voice coil motor. At this time, one end of the drive coil 111 is located near the center of the drive magnet 109, and the other end of the coil is located near the end of the drive magnet 109. Near the center and end of the drive magnet 109, the direction of the magnetic field is inclined from the vertical direction. This is because the flat coil type voice coil motor does not have a closed yoke 110a as described above. If a current is passed through the drive coil at this time, a thrust slightly inclined upward with respect to the left-right direction is generated as shown in FIG. This is because when a leftward thrust is generated toward the paper surface, the thrust is generated in a direction perpendicular to the magnetic field. That is, in addition to the thrust component in the left and right direction, which is the movable direction of the lens, a thrust component in the direction in which the drive coil is separated from the drive magnet is generated. Similarly, when the direction of the current is reversed to generate a rightward thrust in the figure, a thrust component is generated in a direction in which the drive coil approaches the drive magnet, contrary to the above.

  FIG. 10 is a diagram schematically showing a lens holding structure when a flat coil type voice coil motor is used for driving a focus lens of an imaging apparatus. FIG. 10 illustrates the optical axis and the lens driving direction of the optical system in a direction perpendicular to the paper surface. As in the case of the voice coil motor using the U-shaped yoke described with reference to FIGS. 4 and 5, the yoke 110a, the drive magnet 109, and the two bars 106 and 107 are fixed to a lens barrel (not shown). Yes. Therefore, the lens is held so as to be movable in the direction perpendicular to the paper surface with respect to the bar via the sleeve portion 104 and the U groove 105 provided in the lens holding member 103.

  A driving coil 111 is fixed to the lens holding member 103. Here, when the lens is near the end of the movable range as described above and a thrust component in the direction in which the drive coil 111 moves away from the drive magnet 109 is generated, a rightward force in the drawing is applied to the coil fixing portion of the lens holding member. Join. This rightward force causes the lens holding member 103 to rotate counterclockwise about the sleeve position. This is because backlash of several μm is provided between the sleeve 104 and the U groove 105 and the bars 106 and 107 so as to be slidable. For this reason, for example, when the lens is suddenly driven from a state in which the lens is stopped (a state in which no thrust is generated in the coil) or suddenly stopped during the driving, the inner wall of the U groove 105 is caused by the rotational motion described above. And the bar 107 collide, and a noise called a beating sound is generated.

  As described above, in the minute drive operation of AF control, the focus lens moves each time an AF evaluation value is obtained, and the lens is moved and stopped so that the movement of the lens is completed within 1 Vsync. FIG. 11 is a diagram illustrating a temporal change in the lens position control target and actual lens movement during the minute driving operation. As shown in FIG. 11, the control target of the lens position is switched from the A position to the B position when the microcomputer determines the moving direction and the moving amount, thereby driving the lens so that the lens moves to the B position. C in the figure is when the lens starts to be driven, and the lens starts to move due to a sudden thrust applied from the state where the lens is stopped. In addition, D in the drawing is a point in time when driving for a minute movement amount is completed, and the lens is stopped due to a sudden thrust applied in the reverse direction from the state where the lens is moving. At the time of these C and D, the above-mentioned beating sound is generated and becomes a rattling noise. The above is the mechanism of noise generation in the flat coil type voice coil motor.

  Note that a voice coil motor using a U-shaped yoke hardly generates components other than the direction of the optical axis of the thrust, and has a structure that is advantageous for the generation of a tapping sound. This is because the voice coil motor using the U-shaped yoke has a structure in which the yoke is closed as described above, and the direction of the magnetic field is substantially parallel inside the yoke.

(Lens position control during micro drive operation)
Next, lens position control during a minute driving operation in autofocus control will be described. FIG. 2 is a diagram illustrating a temporal change in the lens position control target and actual lens movement during the minute driving operation. As shown in FIG. 2, in this embodiment, when the camera / AF microcomputer 114 determines the movement direction and movement amount, the lens position moves so as to move from the A position to the B position at a target speed below a predetermined upper limit value. Be controlled. The method of performing pseudo speed control in lens driving by position control using a voice coil motor is as described above. C and D in the figure are the start and end of movement of the lens, respectively. Since the target position is gradually changed by the pseudo speed control, a sudden thrust is suppressed from being applied. Thereby, it is possible to suppress a beating sound caused by a sudden thrust applied at the start and end of the movement of the lens in the flat coil type voice coil motor, which was a problem of the prior art. As the target speed is decreased, the thrust change becomes more gradual, and the noise suppression effect becomes more prominent. Here, the upper limit value of the target speed may be set to 10 mm / sec. This is because it has been confirmed that if the target speed is set to 10 mm / sec or less, the noise during minute driving is sufficiently reduced, and there is no problem in product performance and quality.

  As described above, the noise suppression effect increases as the upper limit of the target speed is decreased. On the other hand, if it is set too late and it takes 1 Vsync or more to move from the A position to the B position, the AF control cycle is extended as much as waiting for the movement of the lens, and focusing is delayed. In this regard, in the technique disclosed in the present application, the movement amount at the time of micro driving in the autofocus operation is about 100 μm at the maximum. At this time, if the movement speed is 10 mm / sec, the time required for the movement is as follows. Is 10 msec. Even if the lens position stabilization time after the movement is completed (time until the overshoot with respect to the target position converges), the movement can be completed sufficiently within 1 Vsync, and it can be confirmed that there is no problem in product performance in this respect as well. Yes. This is because 1Vsync of an NTSC video signal is 1/60 seconds = 16.7 msec.

  From the above, by limiting the target speed to a predetermined upper limit value (10 mm / sec in the above embodiment) at the start / end of movement of the focus lens, noise can be reduced without affecting the autofocus performance. It can be reduced and the performance and quality required for the product can be realized.

  Hereinafter, a second embodiment of the position control device of the present invention will be described. Since the configuration is the same as that of the first embodiment, a description thereof will be omitted.

  In the first embodiment, the target speed is limited from the start of movement of the focus lens to the end of movement. However, as described in the noise generation mechanism in the minute driving operation, the beating sound is generated when the movement of the focus lens starts and ends. Therefore, while the focus lens is moving, even if there is no restriction on the target speed, almost no beating sound is generated. Therefore, in this embodiment, the target speed is limited only at the start and end of the movement of the focus lens, and is not set during the movement, so that the time required for the movement of the focus lens is shortened. Drive control is performed. By performing such control, the movement speed at the start and end of movement is made slower to increase the noise reduction effect, and the movement is completed within 1 Vsync even when the movement distance is longer. Can do.

  As described above, there is no problem in the control technique of the first embodiment. However, in different products, conditions such as the ease of noise generation, the maximum moving distance, and the noise level required for the product. In such a case, the drive control as in this embodiment is effective.

(Lens position control during micro drive operation)
FIG. 3 is a diagram illustrating a temporal change in the actual lens movement and a lens position control target during a minute driving operation according to the second embodiment of the present invention. As shown in FIG. 3, in this embodiment, the lens position control target is from the point A when the focus lens starts to move to the point B after a predetermined time (for example, 3 msec), and before the predetermined time from the end of the movement. It is driven at a predetermined target speed upper limit value (for example, 5 mm / sec) only between the time point C and the time point D at the end of movement. On the other hand, driving is performed at a faster target speed from time B to time C. Since the necessary moving distance is known from the calculation result of the camera / AF microcomputer 114, the target speed from time B to time C for completing the movement within 1 Vsync can be obtained as follows. That is, since the target speed for 3 msec from time A to time B is limited to 5 mm / sec, the movement amount during that time is 5 [mm / sec] × 3 [msec] = 15 μm. The amount of movement from time C to time D is also 15 μm. If the required moving distance is 120 μm, if it is attempted to complete the movement from the start of movement to the end of movement in 10 msec in consideration of the lens stabilization time, the time from time B to time C is 10 msec− (3 msec × 2 ) = 4 msec and the moving distance is 120 μm− (15 μm × 2) = 90 μm, and therefore, the moving may be performed at a speed of 90 [μm] / 4 [msec] = 22.5 [mm / sec]. That is, if the target speed is limited to 5 mm / sec until 3 msec from the start of movement, then set to 22.5 mm / sec until 7 msec elapses, and then limited again to 5 mm / sec until reaching the target position, FIG. Such lens operation can be realized. If the movement distance is 50 μm or less, the target speed is limited to 5 mm / sec from the start of movement to the end of movement as in the first embodiment. This is because if the moving distance is 50 μm or less, it can reach within 10 msec at a moving speed of 5 mm / sec.

  As described above, according to the present embodiment, the movement speed at the start and end of movement is further slowed to increase the noise reduction effect, and the movement is completed within 1 Vsync even when the movement distance is longer. And the scope of application of the present invention can be broadened.

  As described above, as described in the first and second embodiments, according to the technology disclosed by the present application, it is possible to suppress noise generated due to the movement of the position control object.

It is the figure which showed the structure at the time of applying the position control apparatus of this invention to the position control of the focus control lens (focus lens) of an imaging device. It is the figure which showed the time change of the control target of the lens position at the time of a micro drive operation | movement in the 1st Embodiment of this invention, and the actual lens movement. It is the figure which showed the time change of the control target of the lens position at the time of micro drive operation, and the actual lens movement in the 2nd Embodiment of this invention. It is the figure which showed roughly the structure of the voice coil motor using a U-shaped yoke. It is the figure which showed the lens holding structure at the time of applying the voice coil motor using a U-shaped yoke to the drive of the focus lens of an imaging device. It is the figure which showed the structure of the flat coil type voice coil motor schematically. It is an example of AF evaluation value at the time of image | photographing a normal to-be-photographed object image. It is the figure which showed the lens operation | movement at the time of a micro drive operation | movement in the focusing control of TV-AF system. In a flat coil type voice coil motor, it is the figure which showed the state which has a drive coil near the end of a movable range. It is the figure which showed the lens holding structure at the time of applying a flat coil type voice coil motor to the drive of the focus lens of an imaging device. It is the figure which showed the time change of the control target of the lens position at the time of a micro drive operation in the prior art, and the actual lens movement.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Lens unit 102 Focus lens 103 Lens holding member 104 Sleeve 105 U groove 106 Sleeve bar 107 U groove bar 108 Lens barrel 109 Drive magnet 110a, 110b Yoke 111 Drive coil 112 Scale 113 Position sensor 114 Camera / AF microcomputer 115 AF signal processing Circuit 116 Voice coil motor drive circuit 117 Imaging device 118 CDS / AGC circuit 119 Camera signal processing circuit 120 Recording device 121 Monitor device

Claims (10)

Driving means for driving the position control object;
The position of the position control object is controlled by controlling the thrust of the driving means based on the position of the position control object, and the movement of the position control object between the start of movement of the position control object and the stop of movement. And a position control means for updating the target position.   The target position for moving the position control target object is that the average moving speed of the position control target object at the start or end of the movement of the position control target object reaches a predetermined value. The position control apparatus according to claim 1, wherein calculation is performed so as not to perform the operation.   The position control device according to claim 1, wherein the driving unit is a flat coil type voice coil motor including a driving magnet, a driving coil, and a flat yoke.   The position control device according to claim 1, wherein the position control object is a lens of an imaging device.   The position control apparatus according to claim 4, wherein the lens is a focus adjustment lens.   The imaging device includes: an imaging element that converts incident light from an imaging optical system into an electrical signal; a signal processing unit that generates a video signal from an output signal of the imaging element; and an in-focus state of an image from the output of the signal processing unit The in-focus state detecting means for detecting the in-focus state, and performing the in-focus control by controlling the position of the position control object based on the information of the in-focus state detecting means. Position control device.   The position control device according to claim 5, wherein the focus state detection unit detects a focus state of a video from a high frequency component of a video signal.   The position control device according to claim 6, wherein the imaging device moves the focus adjustment lens within one cycle of a vertical synchronization signal of a video signal.   An image pickup apparatus comprising: the position control unit according to any one of claims 1 to 8; and a recording unit that records a signal imaged through a position control target controlled by the position control unit. The position of the position control object is controlled by controlling the thrust of the driving means that drives the position control object based on the position of the position control object, and between the start of movement of the position control object and the stop of movement. A position control method comprising: updating a movement target position of a position control object.

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