Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
  • G02B7/02—Mountings, adjusting means, or light-tight connections, for optical elements for lenses
  • G02B7/04—Mountings, adjusting means, or light-tight connections, for optical elements for lenses with mechanism for focusing or varying magnification
  • G02B7/10—Mountings, adjusting means, or light-tight connections, for optical elements for lenses with mechanism for focusing or varying magnification by relative axial movement of several lenses, e.g. of varifocal objective lens
  • G02B7/102—Mountings, adjusting means, or light-tight connections, for optical elements for lenses with mechanism for focusing or varying magnification by relative axial movement of several lenses, e.g. of varifocal objective lens controlled by a microcomputer
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
  • H04N23/60—Control of cameras or camera modules
  • H04N23/69—Control of means for changing angle of the field of view, e.g. optical zoom objectives or electronic zooming
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
  • G02B7/28—Systems for automatic generation of focusing signals
  • G02B7/282—Autofocusing of zoom lenses

Definitions

• the present invention relates to a digital camera or the like, more particularly to a movement controller for moving a zoom lens and a focus lens to a designated position at a high speed, a camera apparatus, a movement control method, and a movement control program.
• a technique is disclosed in which a DC motor is decelerated to a given speed when the lens approaches a first distance (deceleration start position X) in relation to a stop target position O, under this condition, such a given speed is maintained until the lens approaches a second distance (complete stop processing start position) and the brake is applied when the lens approaches the second distance to completely stop the lens (refer to Japanese Laid-Open Patent Publication Nos . H05-257060 and 2004-317997).
• the brake since the brake is applied after deceleration to the given speed, free running distance becomes short, and precision of the stop position can be improved.
• the lens since the lens is moved at the maximum speed until deceleration to the given speed, the lens can be moved at a high speed and precisely to the designated position.
• a camera apparatus comprising: a lens unit composed of lenses and a DC motor for moving the lenses; a motor driver for outputting a drive signal for driving the DC motor according to inputted command; and a control section for controlling contents and timing of the command outputted to the motor driver in order to move the lens to a position corresponding to a zoom magnification and a focal length
• the drive signal is defined as a signal for controlling electrical power applied to a coil of the DC motor by PWM control or voltage control
• the command is defined as a command for designating an ON/OFF ratio in the PWM control or a voltage applied to the coil
• the control section sequentially specifies a current position of the lens based on a position detection signal outputted from the lens unit, and controls the contents of the command outputted in each timing until the lens reaches a stop target position so that movement speed of the lens is gradually slowed as the lens approaches the stop target position.
• a movement controller for moving a given mechanism section to a designated stop target position by a DC motor comprising: a drive control means for driving the DC motor to move the given mechanism section in the direction of the stop target position; a deceleration control means for gradually decelerating rotational speed of the DC motor when the mechanism section in transit approaches the stop target position past a first distance; and a stop control means for completely stopping the mechanism section by braking rotation of the DC motor when the mechanism section decelerated by the deceleration control means approaches the stop target position past a second distance .
• a camera apparatus for moving a lens in an imaging section in an imaging section to a designated stop target position by a DC motor comprising: a drive control means for driving the DC motor to move the lens in the direction of the stop target position; a deceleration control means for gradually decelerating rotational speed of the DC motor when the lens in transit approaches the stop target position past a first distance; and a stop controlmeans for completely stopping the lens by braking rotation of the DC motor when the lens decelerated by the deceleration control means approaches the stop target position past a second distance.
• FIG. 1 is a block diagram showing a structure of a digital camera according to an embodiment of the present invention
• FIG. 2 is a block diagram for explaining a control system in a control section (CPU)20, a motor driver 14-1, and a lens unit 11 in the digital camera of this embodiment;
• FIG .3 is a conceptual diagram showing data of a zoom tracking table stored in aprogrammemory 30 of the digital cameraaccording to this embodiment
• FIG.4 is aflowchart showing amain routine of zoomprocessing according to this embodiment.
• FIG. 5 is a flowchart showing lens stop processing in zoom processing according to this embodiment
• FIGS. 6A to 6C are conceptual diagrams showing examples of target (ideal) deceleration curves for controlling a DC motor in this embodiment
• FIG.7 is a conceptual diagram showing an example of a target (ideal) deceleration curve for controlling the DC motor in this embodiment ;
• FIG. 8 is a conceptual diagram showing an example for correcting deviance from the target (ideal) deceleration curve to control the DC motor;
• FIGS. 9A and 9B are conceptual diagrams showing an example of a voltage applied of the DC motor and a position detection pulse when a control method according to this embodiment is performed.
• FIGS. 1OA and 1OB are conceptual diagrams for explaining stop position control technology of a DC motor according to a related art .
• FIG. 1 is a block diagram showing a structure of a digital camera according to an embodiment of the present invention.
• an image acquisition section 10 is composed of a lens unit 11, a shutter 12, and an LPF 13.
• the lens unit 11 is composed of a lens group in which aspheric lenses such as a zoom lens anda focus lens are stacked.
• the lens unit 11 includes a DC motor for driving the foregoing zoom lens and the foregoing focus lens.
• the shutter 12 is a so-called mechanical shutter, which is operated by a motor driver 14-1 driven by a control section 20 when a shutter button is operated.
• the LPF 13 is a crystal low pass filter which is mounted in order to prevent generation of moire.
• the motor driver 14-1 controls driving the DC motor of the lens unit 11 to move the zoom lens, to move the focus lens and the like according to the control command providedfrom the control section (CPU) 20.
• a driver 14-2 drives an imaging sensor 16.
• an analog signal processing section 15 is composed of the imaging sensor (CCD, CMOS) 16, a sampling/signal amplification processing section 17, and an A/D converter 18.
• the imaging sensor 16 images an object image (image) , and converts light intensity of each color of RGB to a current value.
• the sampling/signal amplification processing section 17 performs correlated double sampling processing for inhibiting noise and irregular color and signal amplification processing.
• the A/D converter 18 is also called analog front end, and converts a sampled and amplified analog signal to a digital signal ( converts each color of RGB and CMYG to 12 bit data, and outputs the converted data to a bus line) .
• control section (CPU) 20 controls a whole digital camera 1 (imaging apparatus) according to programs stored in an after-mentioned program memory.
• the motor driver 14-1 is controlled to drive the DC motor for driving the lens unit 11 according to zoom operation . Details of controlling the motor driver 14-1 by the control section (CPU) 20 and controlling drive of the lens unit 11 will be described later.
• a preview engine 22 performs pixel skipping processing for displaying digital data inputted via the image acquisition section 10 and the analog signal processing section 15 in a telerecording mode (also referred to as recording mode or shooting mode), or digital data stored in an image buffer 26 immediately after detecting shutter operation and digital data stored in an image memory 31 on a display section 25.
• a D/A converter 23 converts the digital data which is pixel-skipped by the preview engine 22, and outputs the converted data to a driver 24 as a subsequent stage .
• the driver 24 comprises a buffer region for temporarily storing digital data to be displayed on the display section 25 as a subsequent step , and drives the display section 25 based on a control signal inputted via a key operation section 27 and the control section 20.
• the display section 25 is composed of a color TFT liquid crystal, an STN liquid crystal or the like, and displays a preview image, image data after shooting, a setting menu and the like.
• the image buffer 26 temporarily stores digital data immediately after shooting until the digital data is inputted via the analog signal processing section 15 or a digital signal processing section 28 and transported to the digital signal processing section 28.
• a key operation section 27 is composed of a shutter button, a recording/reproduction mode selection slide switch, a menu button, and a cross key (determination is made when the center is depressed) and the like.
• the digital signal processing section 28 performs white balance processing, color processing, gradation processing, edge enhancement, conversion from RGB format to YUV format, and conversion from YUV format to JPEG format for digital data inputted via the analog signal processing section 15. Further, the digital signal processing section 28 generates an image file in accordance with the Exif specification from image data downloaded from the image acquisition section 10 and the analog signal processing section 15. An image compression/extension processing section 29 compresses and codes digital data inputted via the digital signal processing section 28 into JPEG format, or extends the JPEG format file in reproduction mode.
• a program memory 30 stores various programs to be loaded into the control section 20, an EV value in a best shot function, color correction information and the like.
• the program memory 30 holds a zoom tracking table 30-1 in which a stop position of the zoom lens, a focal length, an F value and a position of the focus lens, etc. in the lens unit 11 are set. Details of the zoom tracking table 30-1 will be described later.
• An image memory 31 stores image data temporarily stored in the image buffer 26 and digital data converted in various file formats.
• a card I/F 32 controls data exchange between an external recording medium 33 and an imaging apparatus main body.
• the external recording medium 33 is a removable recording medium such as a CompactFlash (registered trademark) , a memory stick, and an SD card.
• An external connection use I/F 34 is composed of a slot for USB connector or the like .
• the external connection use I/F 34 is connected to a personal computer or the like, and is used for transferring shot image data.
• a battery 35 is composed of a disposable primary battery, a rechargeable secondary battery or the like. The battery 35 supplies electrical power for driving the foregoing respective components .
• the control section (CPU) 20 controls operation of the motor driver 14-1 by sending a serial transfer clock, serial transfer data, and a serial data latch via a serial communication control line. Further, the control section (CPU) 20 controls a signal outputted from the motor driver 14-1 to the lens unit 11 in the OFF (high impedance) state by lowering an output ON/OFF control line to "L" level, for example.
• the control section (CPU) 20 can control operation of the motor driver 14-1 by using the foregoing output ON/OFF control line instead of the foregoing serial communication control line in performing stop processing of the DC motor in order to decrease frequent serial transfer. Further, the control section (CPU) 20 calculates a current position and speed of the lens unit (zoom lens and focus lens) 11 according to zoom position detection pulse information from an encoder included in the DC motor of the lens unit 11.
• the motor driver 14-1 supplies motor + side output and motor - side output to the lens unit 11 to drive the DC motor of the lens unit (zoom lens and focus lens) 11 according to the serial transfer clock, the serial transfer data, the serial data latch, or the output ON/OFF control from the control section (CPU) 20.
• the lens unit 11 drives the DC motor according to the motor + side output to move the lens to the TELE side; and drives the DC motor according to the motor - side output to move the lens to the WIDE side.
• the DC motor of the lens unit 11 comprises the encoder as described above, and sends the zoom position detection pulse information to the control section (CPU) 20 by its rotation.
• zoom stop positions are previously set. That is, unique determination is possible so that when the zoom position is "WIDE,” the zoom stop position is A [pulse], when the zoom position is "WIDE+1,” the zoom stop position is B [pulse]... when the zoom position is 11 TELE-I,” the zoom stop position is C [pulse], and when the zoom position is "TELE,” the zoom stop position is D [pulse] . Further other parameters such as a focal length [mm] , an F value [F_No] and a focus address [pulse] are specified for every zoom position.
• the control section (CPU) 20 acquires a zoom lens stop position , that is , a stop target position O from the zoom tracking table 30-1 according to zoom operation, controls drive of the DC motor by using an after-mentioned target (ideal) deceleration curve, and moves the zoom lens to the foregoing stop target position O.
• the control section (CPU) 20 acquires a stop position of a focus lens, that is, a focus address from the zoom tracking table 30-1 according to zoom operation and an object distance, controls drive of the DC motor by using the after-mentioned deceleration curve so as to set the focus address as the stop target position 0 in the focus lens, and moves the focus lens to the foregoing stop target position 0.
• FIGS. 4 and 5 are flowcharts for explaining operation of the digital camera 1.
• FIG.4 is a flowchart showing a main routine of zoom processing .
• FIG .5 is a flowchart showing lens stop processing in the zoom processing.
• Step SlO a current object distance is acquired
• Step S12 driving the DC motor corresponding to the zoom lens
• Step S12 a zoom magnification is determined according to zoom operation
• Step S14 a zoom lens position corresponding to the zoom magnification that is defined as a target stop position of the zoom lens is acquired from the tracking table 30-1 (Step S16) .
• Step S18 the target stop position of the zoom lens is designated and the lens stop processing is executed. Details of the lens stop processing will be described later.
• a focus lens position corresponding to the zoom magnification and the object distance that is defined as a target stop position of the focus lens (focus address) is acquired from the tracking table 30-1 (Step S20), and driving the DC motor corresponding to the focus lens is started (Step S22).
• the target stop position of the focus lens is designated, and the lens stop processing is executed (Step S24).
• the lens stop processing first, information on a stop target lens and the target stop position is acquired (Step S30).
• the stop target lens means the zoom lens or the focus lens.
• the target stop position thereof is obtained in the foregoing Step S18 or the foregoing Step S24.
• a current state (absolute position, elapsed time, and movement speed) of the stop target lens is calculated based on count values of a clocking timer and a pulse for position detection (lens position detection pulse information) (StepS32). Since the fact that an absolute position of the stop target lens is specified based on a sensor detecting a reference position of the stop target lens and a signal from a sensor detecting movement of the stop target lens or rotation of the DC motor (lens position detection pulse information) and the technology for calculating elapsed time, movement speed of the stop target lens and the like by using a count value of the clocking timer are well known, and thus, details thereof will be omitted.
• a target (ideal) state indicated by the target (ideal) deceleration curve and the calculated current state are compared (Step S34).
• examples of the target (ideal) deceleration curve are shown in FIGS. 6A to 6C and FIG. 7.
• the horizontal axis represents aremaining distance ( remaining pulse number) from the stop target position O
• the vertical axis represents movement speed of the stop target lens .
• a deceleration start position X for starting deceleration of the stop target lens, a complete stop processing start position P for starting complete stop processing by braking the stop target lens, and movement speed of the stop target lens in the course thereof are specified.
• the speed is decreased at a constant acceleration from the deceleration start position X to the target stop position O, and the stop target lens can be stopped more speedy and more precisely with less vibration and noise.
• the stop target lens in the initial stage of deceleration start, the stop target lens is braked and the speed is immediatelydeceleratedat themaximumacceleration , the state thereof is detected and then the speed is decelerated with a constant acceleration from such a state to the target stop position. Therefore, the stop target lens can be stopped speedier while the precision is maintained.
• the acceleration in the initial stage of deceleration is moderately changed so that vibration and noise can be further inhibited.
• the horizontal axis represents a drive processing time T
• the vertical axis represents a remaining pulse number x to the stop target position.
• a deceleration processing start pulse number indicating time to start deceleration of the stop target lens is specified.
• the target (ideal) deceleration curve can be specified by the relation between the remaining distance (remaining pulse number) in relation to the target stop position O and the elapsed time, can be specified by the relation between the remaining distance (remaining pulse number) in relation to the target stop position and the movement speed, or can be specified by other methods.
• the shape of the target (ideal) deceleration curve can be changed according to the purpose such as giving priority to speed, precision, or smoothness. Otherwise, the shape of the target (ideal) deceleration curve can be selected by a user from a plurality of choices.
• specific values indicated by the target (ideal) deceleration curve can be calculated by a calculation formula corresponding to the shape of the curve in each case, or these specific values can be stored in the table in advance.
• stop target lens when the stop target lens is located still far from the stop target position, there is no risk that the stop target lens is not able to be stopped at the stop target position even if the movement speed is relatively fast. In this case, if the movement speed is excessively slow, the elapsed time to the stop target position becomes long. Meanwhile, when the stop target lens is located more close to the stop target position, the stop target lens is not able to be stopped at the stop target position unless the movement speed is slowed. Therefore, at least just before the stop target lens reaches the stop target position, stop processing is performed in accordance with the gradual deceleration curve in which as the stop target lens graduallyapproaches the stop target position , themovement speed is gradually slowed. Thereby, elapsed time to stop the stop target lens can be shortened, and precision of the stop position can be improved.
• the stop processing is performed in accordance with the gradual deceleration curve in which the acceleration in decelerating the movement speed of the stop target lens is not excessively high. Therefore, smooth stop processing can be performed so that vibration and noise in deceleration are not large.
• Step S36 After comparison between the target (ideal) state indicated by the target (ideal) deceleration curve and the calculated current state in Step S34, whether or not the stop target lens is in the range of complete stop processing (between P and O) is judged (Step S36).
• Step S38 when the stop target lens is not in the range of complete stop processing, that is when the stop target lens has not reached the complete stop processing start position P yet, whether or not the stop target lens is in the range of deceleration processing (between X and P) is judged (Step S38) .
• Step S40 the stop target lens is judged not to have reached the deceleration start position X, and the current drive state is maintained (Step S40). Then, the flow is returned to Step S40.
• Step S42 deviance of the current state from the deceleration curve is verified, and whether or not deceleration is lacked, whether or not deceleration is excessive, and whether or not deceleration is appropriate are Judged ( Step S42 ) .
• Step S44 when the deviation shows deceleration lack, a command is sent to the motor driver 14-1 to increase the ON ratio of PWM drive or the voltage applied by a given amount. Otherwise , when the deviation shows excessive deceleration, a command is sent to the motor driver 14-1 to decrease the ON ratio of PWM drive or the voltage applied by a given amount.
• adjustment may be made only by the ON ratio of PWM drive or only by the voltage applied, or by the both. Further, in the initial stage of deceleration, adjustment may be made mainly by the ON ratio of PWM drive, on the other hand, in the final stage of deceleration, adjustment may be made mainly by the voltage applied. Further, deceleration may be adjusted by using the output ON/OFF control line instead of the serial communication control line. For example, when the target (ideal) deceleration curve shown in FIG.
• intermittent stop processing time represents OFF time in PWM drive
• intermittent drive processing time represents ON time in PWM drive.
• a drive voltage corresponds to the foregoing voltage applied.
• Step S48 when the deviation is appropriate or when the foregoing control is finished, the flow is returned to Step S32, and the foregoing processing steps are repeated until the stop target lens enters in the range of complete stop processing. Then, when the stop target lens enters in the range of complete stop processing, for example, when the stop target lens reaches thecomplete stopprocessing start positionP afterdeceleration, command is sent to the motor driver 14-1 to brake the DC motor, and the complete stop processing is executed (Step S48).
• output from the motor driver 14-1 is controlled in the OFF (impedance) state by using the output ON/OFF control line.
• deceleration in the OFF (high impedance) state is deceleration more moderate than deceleration at "L" level.
• FIG. 9A shows an example of change of the voltage applied to the DC motor by the control method according to this embodiment.
• FIG. 9B is a conceptual diagram showing an example of lens position detection pulse from the lens unit 11.
• FIG. 9A shows a case where adjustment is made by both the ON ratio of PWM drive and the voltage applied.
• normal drive is made by supplying a given voltage applied to the deceleration start position X.
• the ON ratio of PWM drive is gradually reduced, and the voltage applied is gradually reduced.
• the stop target lens is completely stopped by setting the voltage applied to "0. " Further whether the stop target lens reaches the deceleration start position X or the complete stop processing start position P may be found by calculation based on the count value of pulse for position detection (lens position detection pulse information) shown in FIG. 9B and the counting timer as described above.
• the movement control program for moving a given mechanism section which is an embodiment of the present invention, is stored in a memory (for example, a ROM, etc.) of the apparatus (for example, a camera apparatus) as the computer program product.
• a memory for example, a ROM, etc.
• the apparatus for example, a camera apparatus
• the movement control program recorded on a recording medium the program should also be included in the scope of protection. In that case, a recording medium, on which the movement control program is recorded, should be protected.

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• Optics & Photonics (AREA)
• Multimedia (AREA)
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• 2005
  • 2005-06-17 JP JP2005177425A patent/JP5079989B2/ja not_active Expired - Fee Related
• 2006
  • 2006-05-30 WO PCT/JP2006/311176 patent/WO2006134790A1/en not_active Ceased
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