JP4890753B2 - Imaging apparatus and control method thereof - Google Patents

Description

  The present invention relates to a technique for driving and stopping a zoom lens in accordance with a photographer's operation in an imaging apparatus having a zoom lens.

  With a camera with a zoom function that can drive the zoom lens and change the focal length of the lens, the photographer can shoot an image of the desired angle of view by operating an operation member such as a zoom lever. It is. In order to start and stop the zoom drive according to the photographer's operation, detection of pressing and releasing of the operation member, excitation to the motor that drives the zoom lens, detection of the zoom lens position, that is, rotation position of the motor, stop position Processing such as judgment is required. As an invention related to zoom lens drive stop means, Patent Document 1 proposes a technique for preventing a zoom unit from failing by stopping before colliding with a mechanical end even when detection of a desired stop position fails. Yes. Further, in Patent Document 2, if the zoom lens position when the zoom operation member is released is approaching within a predetermined amount from the tele end position or the wide end position, the zoom operation member is stopped after being driven to the tele end position or the wide end position. A zoom control means has been proposed.

As a stop processing method for realizing these stop means, after the zoom operation is started, the zoom position is monitored by software at regular intervals, and the operation member is released by the photographer during driving and a stop command is instructed. In this case, there is a method in which whether or not the lens has been driven to the target stop position is determined by software, and when driving to the stop position, the motor is turned off to stop the lens.
Japanese Patent Laid-Open No. 9-230213 JP-A-7-64142

  However, in the method of periodically monitoring the position by software, CPU resources are consumed more than necessary only by zoom driving, and there is a possibility that the performance of other camera operations may be reduced.

In the above-described problem, the present invention provides a driving unit that drives the lens unit to move in the optical axis direction to change the focal length, and an operation that instructs the driving unit to drive the lens unit in the tele or wide direction. And a control means capable of changing a target position when stopping the lens unit, and a target position to be stopped in the case of one of the predetermined driving directions in the tele or wide direction is set as a target. Position, and in the case of the other driving direction, a control is performed by setting a reversing position ahead of the target position to be stopped and reversing at the reversing position, while the driving means is driving in the one driving direction. when the by operation means of the drive of the stop instruction is issued, after the change to the time required for changing the target position by the driving speed and the control unit of the lens unit Said control means based on the number of pulses supplied to the driving means until the target position is changed target position, stops the lens unit can be stopped position during driving to the other driving direction of said driving means When an instruction to stop driving is issued by the operating means, the driving means reaches the reverse position corresponding to the driving speed of the lens unit, the time required for changing the target position by the control means, and the changed target position. It said control means changes the target position based on the number of pulses supplied to, Ru stopping the lens unit can be stopped position.

  In the present invention, the lens unit can be stopped at an appropriate stop position in accordance with an operation by the operator.

  Examples of the present invention will be described below.

  FIG. 1 is a block diagram of a camera 100 that is Embodiment 1 of the present invention.

  Reference numeral 0 denotes a lens barrel provided in the camera 100, which includes a lens unit such as a zoom lens 1 and a focus lens 2, and a shutter 3 having a diaphragm function. Each of the lens units such as the zoom lens 1 and the focus lens 2 moves in the optical axis direction by receiving a driving force from a motor to change the focal length of the photographing optical system or perform focus adjustment.

  Reference numeral 4 denotes an image sensor such as a CCD sensor or a CMOS sensor, and 8 denotes an A / D converter, which converts an analog signal output from the image sensor 4 into a digital signal.

  A timing generator 5 supplies a clock signal and a control signal to the image sensor 4, D / A converter 6, and A / D converter 8 under the control of the memory control 9 and the camera system control 5.

  The image display 7 is composed of TFT_LCD (thin film transistor drive type liquid crystal display, TFT: thin-film transistor, LCD: liquid crystal display), etc., and image data obtained by photographing, specific information (for example, photographing information), etc. Is displayed. Here, the display image data and the like written in the image display storage 10 are output and displayed on the image display 7 via the D / A converter 6 under the control of the memory control 9. By sequentially displaying image data generated from the output signal of the image sensor 4 on the image display 7, it is possible to realize an electronic viewfinder function.

  Under the control of the camera system control 15, the memory control 9 performs data input / output control with respect to the timing generator 5, D / A conversion 6, A / D conversion 8, image display storage 10, and image processing 11.

  An image processing unit 11 performs predetermined pixel interpolation processing and color conversion processing on data from the A / D conversion 8 or the memory control 9. Thereby, image data is generated.

  The camera system control 15 controls the exposure control 12, the distance measurement control 13, and the zoom control 14 in accordance with operations performed from the operation unit 20.

  The camera system control 15 calculates an exposure value (aperture value and shutter speed) based on the luminance information obtained by the image processing in the image processing 11, and the aperture function via the exposure control 12 based on the calculation result. The drive of the shutter 3 provided with is controlled. Thereby, AE (automatic exposure) control is performed.

  Further, the camera system control 15 controls the driving of the focus lens 2 via the distance measurement control 13 based on the focus adjustment information (contrast detection value) of the photographing optical system obtained by the image processing in the image processing 11. Thereby, AF (autofocus) control or the like is performed.

  Similarly, the camera system control 15 drives the zoom lens 1 via the zoom drive 14 based on the operation amount and operation direction of an operation switch (zoom lever or zoom button) for instructing zooming in the operation unit 20. Control.

  The memory 16 includes a work area for the camera system control 15, a volatile area used as a temporary storage area for captured still images and moving images, and a nonvolatile area for storing design values necessary for driving the camera. . The storage capacity of the memory 16 is sufficient to store a predetermined number of still images and a moving image for a predetermined time. In the case of continuous shooting or panoramic shooting for continuously shooting a plurality of still images. In addition, high-speed and large-volume image writing is possible.

  The power source 17 is composed of a battery detection circuit, a DC-DC converter, a switch circuit for switching a block to be energized, etc., and detects the presence / absence of a battery, the type of battery, the remaining battery level, and the like. Based on a command from the system control 15, the DC-DC converter is controlled, and a voltage and a current are supplied to each unit including a recording medium for a necessary power source for a necessary period.

  An interface (I / F) 18 is an interface with a recording medium such as a memory card or a hard disk. The recording 19 is a recording device for storing image data and the like on a recording medium, and can be accessed with the camera system control 15 via the I / F 18.

  FIG. 2 is a block diagram illustrating a camera system that implements the zoom control of the present embodiment.

  The motor 201 is a DC motor or the like, and is an actuator that drives the zoom lens 200 disposed in the lens barrel via a power transmission mechanism. The position detection circuit 202 is a pulse encoder attached to the drive shaft of the motor 201 as a rotary encoder, and the light of the LED is pulsed by a photo interrupter (PI) composed of a light-emitting diode (LED) and a phototransistor. A signal received by the phototransistor by transmitting or shielding the plate is output as an H output or an L output. By counting this output by the counter 209, the rotation angle of the motor can be detected. Furthermore, it is possible to detect the direction of rotation by installing two PIs in a rotational circle equidistant from the rotation center of the pulse plate and at a position where the phase of the output signal is shifted by ¼ period. FIG. 3 is a diagram showing the relationship between the rotation direction of the motor and the encoder output. Two PI outputs are encoder A phase and encoder B phase, and when the motor rotates forward, PI output is (A phase, B phase) = (L, L) → (H, L) → (H, H) → If the PI is installed so that it changes as (L, H) → (L, L) →..., The output will be (A phase, B phase) = (L, L) → (L, H) when the motor reverses. → (H, H) → (H, L) → (L, L) →. The counter 209 can detect the rotation angle of the motor, that is, the zoom lens position by counting up when rotating forward and counting down when rotating backward.

  The motor driver circuit 203 includes a bridge circuit that determines the rotation direction of the motor, a speed control circuit, and the like. A drive signal is output to the motor 201 so as to drive the motor in the rotational direction and rotational speed commanded by the drive sequence control 210 via the serial communication (SIO) 204. An example of a bridge circuit that controls the rotation of the motor is an H-bridge circuit. FIG. 4 is a diagram illustrating an H-bridge circuit. Assuming that the direction of rotation in which the motor rotates when current flows from point A to point B is forward, the motor rotates in the forward direction when SW1 is in the on state and SW2 is in the off state. When SW1 is off and SW2 is on, the motor rotates in the reverse direction. When SW1 and SW2 are on, points A and B are short-circuited, and the rotating motor stops after rotating due to inertia. In addition, it is possible to perform speed control by performing PWM control (PWM: Pulse Width Modulation) on SW1 or SW2 so that the encoder pulse period of the input encoder and the encoder pulse period of the target speed become the same period. It is.

  The zoom control 205 is configured by a calculation device such as a CPU, hardware such as a counter circuit and a pulse generation circuit that are peripheral devices thereof, and software that operates on a calculation device in which a drive sequence is programmed.

  The stop counter value setting 208 sets a counter value for generating a stop signal so as to stop at the target zoom lens position. The target zoom lens position will be described later. The set stop counter value and the counter value of the counter 209 are compared by the counter comparator 207, and if they match, the stop signal generator 206 is instructed to output a stop signal. At the same time, it notifies the drive sequence control 210 implemented by software that the counter values match with the hardware interrupt signal. The stop signal generator 206 is constituted by a pulse generation circuit. When the stop signal output is H, the motor driver circuit 203 can output a control output to the motor 201. When the set stop counter value matches the counter, and the H → L falling signal is generated from the stop signal generator 206, the motor driver circuit 203 turns on the SW1 and SW2 of the H-bridge circuit and turns on the short brake. multiply. As a result, the motor 201 stops, and the zoom lens 200 driven by the motor 201 also stops.

  FIG. 5 is a diagram showing the A and B phase waveforms, the drive current waveform, and the stop signal waveform of the encoder that are generated when the motor is driven. FIG. 5 shows each waveform state when the initial state is rotated in the forward direction from the stopped state, stopped, and further rotated in the reverse direction. In order to perform normal rotation from the stopped state, the drive sequence control 210 instructs the motor driver circuit 203 via the SIO 204 in the rotation direction, and issues a rotation start command. During forward rotation, a positive drive current is generated in the direction from point A to point B in FIG. When the zoom lens reaches the target position, the stop signal generator 206 changes the stop signal from H to L, and the motor driver circuit turns on SW1 and SW2 of the H-bridge circuit in FIG. 4 at the timing when this input signal is generated. To do. Next, at the timing of starting reverse rotation, the stop signal is changed from L to H so that the motor driver circuit 203 can drive the motor. When a reverse rotation start command is issued via the SIO 204 as in the normal rotation, a minus drive current is generated and the motor starts to reverse. In the encoder output at this time, the phases of the A phase and the B phase are inverted by 180 ° with respect to the forward rotation.

  Here, a target position for stopping the zoom lens will be described.

  As described above, in order to start and stop zoom driving according to the operation of the photographer, detection of pressing and releasing of the operation member, excitation to the motor that drives the zoom lens, zoom lens position, that is, rotation position of the motor Processing such as detection and stop position determination is necessary. As a stop processing method for realizing such stop control, after zoom operation is started, the zoom position is monitored by software at regular intervals, and the operation member is being driven. Is released by the photographer and a stop command is instructed, it is determined by software whether or not it has been driven to the target stop position, and when it is driven to the stop position, the motor is turned off to stop the lens. However, in the method of periodically monitoring the position by software, CPU resources are consumed more than necessary only by zoom driving, and there is a possibility that the performance of other camera operations may be reduced. Therefore, the software has a plurality of target positions to be stopped, and it is only possible to set the stop target position and rewrite the target position during driving, and the motor drive pulse count and the set target position have been reached. The processing for giving the motor excitation stop command is performed by a dedicated arithmetic unit, and when the stop target position is reached, the software is notified by a hardware interrupt.

  In such a camera system, when a stop command is generated while the zoom lens is being driven and is to be stopped, the determined stop position is rewritten as another target position. At this time, when another target position to be rewritten is close to the current position, the target position to be rewritten may be passed during the rewriting process by software, and the motor may not be stopped. Furthermore, there is a possibility that the zoom lens continues to be driven until it reaches the mechanical end position, and is broken by an impact hitting the end. Therefore, in this embodiment, processing when a zoom lever as described later is pressed is performed.

  The drive sequence control 210 performs control so that the zoom lens is driven in accordance with a determined sequence in accordance with an operation by the zoom operation unit 213. When a tele switch or a wide switch of the zoom lever of the zoom operation unit 213 is pressed, the camera system control 211 responds to the switch pressed from the target position of the zoom lens stored in the nonvolatile area of the memory 212. The tele end position or the wide end position is designated as the target position, and a drive command is issued to the drive sequence control 210. Here, the target positions stored in the memory 212 include pulse positions at the wide end position and the tele end position, and a plurality of middle positions at which the lens focal lengths are equally spaced between the wide position and the tele position. Has been. The drive sequence control 210 sets a stop counter value so that the zoom lens is driven to a designated target position, and then instructs the motor driver circuit 203 to rotate the motor to rotate the motor. When the switch as the operation means pressed by the photographer is released before reaching the target position, the drive sequence control 210 determines whether or not a stop position deviation correction operation described later is necessary, and stops according to the stop sequence. Process.

  FIG. 6 is a flowchart illustrating a process when the zoom lever is pressed in the first embodiment of the present invention. After starting the camera, the camera system control 211 monitors whether or not the zoom lever of the zoom operation unit 213 has been pressed as the process of step S001. When it is detected that the zoom lever is turned on, the process proceeds to step S002, and it is determined which of the tele switch and the wide switch has been pressed. If the wide switch has been pressed, the stop target position is set to the wide end position as a process in step S003, and a command for driving in the wide direction is issued to the drive sequence control 210. Similarly, when the tele switch is pressed, a drive command in the tele direction is issued with the tele end position as the target position as the process of step S004. The drive sequence control 210 starts driving the motor in response to the drive command (step S005). By setting the target position at the start of startup to the wide end position or the tele end position, the zoom lens can be operated at the wide end position or the tele end position even when the target position is not rewritten during driving. There is no risk of driving until it stops and collides with the mechanical end.

  After the motor starts driving, it is monitored by the determination processing in step S006 and step S007 that the zoom lever is continuously pressed until the stop target position (in this case, the wide end position or the tele end position) is reached. If the zoom lever is released before reaching the target position, the process proceeds to (1). When the zoom lever is reached without reaching the target position, the driving of the motor is stopped in step S008. At this time, the zoom is in the wide or tele state.

  FIG. 7 is a flowchart illustrating a process when the zoom lever is released while the zoom lens is being driven according to the first exemplary embodiment of the present invention. When it is determined in step S006 that the zoom lever is in the OFF state, first, in step S009, the driving speed at the time of driving is acquired. In step S010, the target position rewriting time calculated in advance by the software is acquired. The number of pulses driven by the zoom during rewriting of the target position can be obtained from the acquired driving speed and rewriting time. For example, in a system that requires 10 msec for the target position rewriting process, when the motor is driven at 800 pps, the zoom lens is advanced by 800 pps × 10 msec = 8 pulses when the stop position is issued and the target position is rewritten. It becomes.

  Next, in step S011, the drive sequence control 210 acquires the current zoom lens position by acquiring the value of the counter 209. In step S012, a stop position candidate to be stopped next is acquired from the current position and the traveling direction. Here, the stop position candidates are stop target positions that pass next when proceeding in the direction of travel from the current position in the zoom lens stop target positions stored in the memory 212. In step S013, it is determined whether the stop position candidate is a wide position, a tele position, or a middle position. In the case of the wide position or the tele position, since it is the target position set before driving in step S003 and step S004, the driving is continued until the stop position is reached without rewriting the target position. If the stop position candidate is the middle position, it is determined in step S014 whether the target position can be changed. If the pulse difference between the current position and the stop position candidate is larger than the number of pulses that are driven while the target position is changed, it is determined that the pulse can be changed, and the target position is changed in step S015. If the pulse difference is small, it is determined that the change is impossible, the process returns to step S011 again, the next stop position candidate is reacquired, the same determination is performed, and then the stop position is determined. After waiting for driving to the stop target position in step S016, the process returns to (2) in FIG. 6, and the drive of the motor is stopped in step S008.

  8 and 9 are diagrams showing a stoppable range (region) in the first embodiment of the present invention. FIG. 8 shows a stoppable range (region) when driving from the wide position toward the tele position, and FIG. 9 shows a stoppable range (region) when driving from the tele position toward the wide position. The retracted position, the wide position, the middle position, and the tele position where the lens before starting the camera is retracted are denoted as S, W, M1 to M3, and T, respectively. When driving in the tele direction, the number of pulses to be driven during the target position changing process from the target stop position to be stopped next to the wide position side is the stop impossible range (area) (FIG. 8). Similarly, when driving in the wide direction, a stop impossible range (area) is made by the number of pulses driven during the target position changing process from the target stop position to the tele position side (FIG. 9). For example, if the wide position (W) is 1000 pulses, the middle 1 position (M1) is 1050 pulses, and the number of operation pulses when changing the target position is 8 pulses, when driving from the wide position to the tele direction, the wide positions 1000 to 1050- The range up to 8 = 1042 is the M1 stoppable range (area), and when the zoom lever is released during that period, it is possible to stop at M1. If the zoom lens position when the zoom lever is released is within the stop impossible range (area), the zoom lens stops after driving to the next stop target position.

  FIG. 10 is a diagram illustrating a stoppable range (region) that accompanies the stop position correction operation according to the first embodiment of the present invention. Stop position correction operation is the same pulse position when driving in the wide direction and when driving in the tele direction due to backlash of the gear that transmits the driving force of the motor to the zoom lens. The physical position of the zoom lens may deviate from when it stops. In order to eliminate the deviation, a driving operation for stopping the motor from one side (either the wide side or the tele side) with respect to one lens target position is a so-called shift operation. For example, when driving the zoom lens, as shown in FIG. 9 when driving in the wide direction, as shown in FIG. 10 when driving in the tele direction, the motor is once driven to a pulse position exceeding the target position as shown in FIG. By stopping in the direction, the zoom lens is always stopped from the wide direction at the middle position. This allows the zoom lens to stop at the same physical position regardless of the driving direction. In the case of the driving direction (direction in which either the wide side or the tele side is set in advance) accompanied by such an operation of correcting the stop position, reversal of a stopable range (area) is started. Up to the position where the target position as described above can be changed with respect to the position.

  By doing as described above, it is possible to stop the lens unit at an appropriate position in accordance with an operation by the operator. Further, even when there is a side-by-side operation, the lens unit can be stopped at an appropriate position in the same manner.

  Another object of the present invention is to supply a storage medium storing software program codes for realizing the functions of the above-described embodiments to a system or apparatus, and the computer (or CPU or MPU) of the system or apparatus stores the storage medium. Needless to say, this can also be achieved by reading and executing the program code stored in.

  In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the program code itself and the storage medium storing the program code constitute the present invention.

  As a storage medium for supplying the program code, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

  Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS (basic system or operating system) running on the computer based on the instruction of the program code. Needless to say, a case where the function of the above-described embodiment is realized by performing part or all of the actual processing and the processing is included.

  Further, after the program code read from the storage medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function is determined based on the instruction of the program code. It goes without saying that the CPU or the like provided in the expansion board or function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.

1 is a block diagram of a camera 100 that is Embodiment 1 of the present invention. FIG. It is a block diagram explaining the camera system which implement | achieves the zoom control means of this invention. It is a figure which shows the relationship between the rotation direction of a motor, and an encoder output. It is a figure which shows the H-bridge circuit which controls the rotation direction of a motor. It is a figure which shows the control signal group produced at the time of a motor drive. It is a figure which shows the flowchart of a process when the zoom lever in Example 1 of this invention is pressed down. It is a figure which shows the flowchart of a process when a zoom lever is open | released during the zoom lens drive in Example 1 of this invention. It is a figure which shows the stop possible range (area | region) when driving in the tele direction in Example 1 of this invention. It is a figure which shows the stop possible range (area | region) when driving in the wide direction in Example 1 of this invention. It is a figure which shows the stop possible range (area | region) accompanying the stop position correction | amendment operation | movement in Example 1 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 0 Lens barrel 1 Zoom lens 2 Focus lens 3 Shutter with aperture function 4 Image sensor 5 Timing generator 6 D conversion 7 Image display 8 AD conversion 9 Memory control 10 Image display storage 11 Image processing 12 Exposure control 13 Distance control 14 Zoom control calculator 15 Camera system control 16 Memory 17 Power supply 18 Interface (I / F)
DESCRIPTION OF SYMBOLS 19 Recording 20 Operation part 100 Camera 200 Zoom lens 201 Motor 202 Position detection circuit 203 Motor driver circuit 204 Serial communication (SIO)
205 Zoom Control 206 Stop Signal Generator 207 Counter Comparator 208 Stop Counter Value Setting 209 Counter 210 Drive Sequence Control 211 Camera System Control 212 Memory 213 Zoom Operation Unit

Claims (6)

Driving means for driving the lens unit to move in the optical axis direction to change the focal length, operating means for instructing to drive the lens unit in the tele or wide direction by the driving means, and stopping the lens unit Control means capable of changing the target position when
In the case of one of the predetermined driving directions in the tele or wide direction, the position to be stopped is set as the target position, and in the case of the other driving direction, the reverse position is set ahead of the target position to be stopped. In the control to reverse at the reversal position,
When the driving means is instructed to stop driving while the driving means is driven in the one driving direction, the driving speed of the lens unit, the time required for changing the target position by the control means, and after the change The control means changes the target position based on the number of pulses supplied to the driving means until the target position , and stops the lens unit at a stoppable position ,
When an instruction to stop driving is issued by the operating means while the driving means is driven in the other driving direction, the time required for changing the driving speed of the lens unit and the target position by the control means and after the change an imaging device said control means based on the number of pulses supplied to the drive means to the reversing position corresponding to the target position by changing a target position, characterized Rukoto stops the lens unit can be stopped position of .   The imaging apparatus according to claim 1, wherein the first target position set when an instruction to start driving is generated by the operation means is a tele end position or a wide end position.   There are a plurality of target positions at which the lens unit stops in the zoom area between the tele end position and the wide end position, and after the start of driving by the operating means, the driving stop is instructed by the operating means. 3. The imaging apparatus according to claim 1, wherein the imaging apparatus stops at a position closest to a position where the lens unit can be stopped among the plurality of target positions. 4.   3. When driving stop is instructed by the operating means, if the stop position that can be stopped is a tele end position or a wide end position, the operation means stops at a first target position. The imaging device described in 1. Driving means for driving the lens unit to move in the optical axis direction, operating means for instructing to drive the lens unit by the driving means, and control means for changing the target position when stopping the lens unit And
In the case of one of the predetermined driving directions in the tele or wide direction, the position to be stopped is set as the target position, and in the case of the other driving direction, the reverse position is set ahead of the target position to be stopped. In the control to reverse at the reversal position,
When the driving means is instructed to stop driving while the driving means is driven in the one driving direction, the driving speed of the lens unit, the time required for changing the target position by the control means, and after the change The control means changes the target position based on the number of pulses supplied to the driving means until the target position , and stops the lens unit at a stoppable position,
When an instruction to stop driving is issued by the operating means while the driving means is driven in the other driving direction, the time required for changing the driving speed of the lens unit and the target position by the control means and after the change an imaging device said control means based on the number of pulses supplied to the drive means to the reversing position corresponding to the target position by changing a target position, characterized Rukoto stops the lens unit can be stopped position of . Driving means for driving the lens unit to move in the optical axis direction, operating means for instructing to drive the lens unit by the driving means, and control means for changing the target position when stopping the lens unit A method of controlling an imaging apparatus comprising:
In the case of one of the predetermined driving directions of the tele or wide direction, the position to be stopped is set as a target position, and in the case of the other driving direction, a reverse position is set ahead of the target position to be stopped. Reversing control at the reversing position,
When the driving means is instructed to stop driving while the driving means is driven in the one driving direction, the driving speed of the lens unit, the time required for changing the target position by the control means, and after the change The control means changes the target position based on the number of pulses supplied to the driving means until the target position , and stops the lens unit at a stoppable position ,
When an instruction to stop driving is issued by the operating means while the driving means is driven in the other driving direction, the time required for changing the driving speed of the lens unit and the target position by the control means and after the change control method by the control means based on the number of pulses supplied to the drive means to the reversing position changes the target position, characterized Rukoto stops the lens unit can be stopped position corresponding to the target position .

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