CN102854699B - The self calibration ring of the automatic focus actuator in photographing module compensates - Google Patents
The self calibration ring of the automatic focus actuator in photographing module compensates Download PDFInfo
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Abstract
Various embodiments of the present invention relate to the actuator drive in a kind of photographing module, improve the method for speed of focusing automatically, system and the equipment of the photographing module driven by actuator more particularly, to utilizing self calibration ring to compensate.The oscillating characteristic of actuator is calibrated to during automatically focusing on control to drive the filling electric current of actuator.Actuator drive includes digital to analog converter (DAC), wave filter, current sink and self calibration module.Free oscillation frequency and damped coefficient are calibrated by self calibration module, and correspondingly, DAC produces subsequently can be by the voltage of filter by-pass, filtering or shaping.This voltage is further converted into filling electric current by current sink.Such self calibration ring compensates and makes closely to follow the trail of free oscillation, and can improve expeditiously stabilization time of lens and improve photographing module automatically focus on speed.
Description
Cross-Reference to Related Applications: the application according to 35 U.S.C. § 119 (e) require on June 29th, 2011 that submit,
It is entitled that " the self calibration ring of the automatic focus actuator in photographing module compensates (Self-Calibrated Ringing
Compensation for an Autofocus Actuator in a Camera Module) " Provisional Application serial number No.
61/502,788；And " the automatic focus actuator in photographing module that submit, entitled on June 26th, 2012
Self calibration ring compensate (Self-Calibrated Ringing Compensation for an Autofocus Actuator in a
Camera Module) " non-provisional application sequence number No.13/533, the rights and interests of 039, this provisional application and non-provisional application
Theme is incorporated herein by quoting.
Technical field
Present invention relates generally to the actuator drive in a kind of photographing module, mend more particularly, to utilizing self calibration ring
Repay improve based on voice coil motor (VCM) or other have resonance behavior actuator photographing module automatically focus on receipts
Hold back the time.Free oscillation frequency and the damped coefficient of VCM are calibrated, and for controlling to drive the filling electric current (sink of VCM
current)。
Background technology
Camera cell phone (camera phone) has become as the consumer-elcetronics devices quickly increased on market, and miniature video camera
Module (camera module) is included in these phones.Size and cost are the most most important for these photographing modules,
And the camera head of reality (camera) performance is also at high demand.Specifically, the development of photographing module is by high-resolution
The demand driving of rate.In order to most preferably utilize the resolution of increase, it is desirable to have effect and the most automatic focus on (AF) comes
Increase with pixel.Now, focusing has turned into the standard feature in most of photographing module, thereafter automatically, enabling
Realize more camera head feature, including optical zoom, shutter control and image stabilization.
Automatically focus on and depend on the lens of lens actuator dollying module rapidly to realize the ability of image focusing.Allusion quotation
The lens actuator of type can be based on digital stepper motor, piezoelectric motor, MEMS actuator or voice coil motor (VCM).
Lens actuator is different according to the lens actuator used.Such as, lens actuator produces and drives digital stepper motor
Or the voltage of piezoelectric motor or drive VCM electric current.It is current that lens actuator based on VCM is used in more than 90%
In photographing module, accordingly, it would be desirable to lens actuator produce the lens in most of latest type photographing module quickly location and
Automatically the electric current needed for focusing on.
Lens actuator based on VCM is similar relative to Microspeaker in concept with operation.Lens barrel is by line
Circle is wound around, and this coil one permanent magnet of next-door neighbour or one group of magnet are placed.Lens barrel holding is in relevant to idle by spring
Infinite focal position (that is, the stop place) place of connection.When fill electric current be injected in voice coil loudspeaker voice coil time, by the electric current in coil with
The Lorentz force generated that interacts of permanent magnet makes lens barrel move on to by the power between this Lorentz force and spring return power
The resting position that balance determines.Figure 1A illustrate the lens displacement of lens actuator based on VCM with fill electric current it
Between typical relation 100.Fill electric current and require more than threshold current, to cause any displacement from stop place.Exceed threshold value
Electric current, lens displacement has linear relationship with filling electric current, until it reaches maximum displacement.Although it is in focal position
Have a current drain, but lens actuator based on VCM be mechanically robust, antidetonation and show relatively low
The low cost solution of hysteresis.
Closed loop auto focusing method is for moving on to its focal position by the lens in photographing module based on VCM.Figure 1B figure
Show between automatic focus value (AFV) and the lens position illustrated in closed loop auto focusing method based on standard hill-climbing algorithm
Relation 150.AFV is associated with picture quality, and exemplary AFV is the contrast of image.In coarse scanning step
In, filling electric current increases with relatively large current step (current step), to allow to scan rapidly maximum displacement from zero
Lens displacement.AFV is analyzed to indicate picture quality, and specifically, AFV peak value is generally characterized.Subsequently
In close scanning step, lens are moved back into the position being associated with AFV peak value with less step, and determine at last
Position step is arranged to focal position.Focal position close to the position being associated with the AFV peak value in coarse scanning step,
And can be accurately identified in close scanning.
Spring-loaded (spring-loaded) VCM system is modeled as damped harmonic oscillator, therefore, is automatically focusing on
During each lens locator step in journey, at lens before target location settles out, lens position with cross punching and
Oscillating phase associates.Fig. 2 illustrates and is associated with that driven by step filling electric current, lens actuator based on VCM
The exemplary timing chart 200 of lens position.When current step puts on VCM, lens barrel moves from its stop place,
Cross and be flushed to peak, vibrate with its free oscillation frequency, and settle out in object lens position.Such mistake is rushed
-vibration-stable process may take up to the stabilization time of 100-200 millisecond (that is, 5-10 cycle of oscillation), completes
Closed loop automatically focus in each lens locator step.May not being suitable for this stabilization time can be to focus on the most automatically
Rate capture rest image and the most of latest type photographing module of frame of video.
Summary of the invention
Various embodiments of the present invention relate to the actuator drive in a kind of photographing module, more particularly, to utilizing certainly
Calibration ring compensate improve the method for speed that automatically focuses on of photographing module based on voice coil motor (VCM), system and
Equipment.Free oscillation frequency and the damped coefficient of VCM are calibrated, and are used for during automatically focusing on controlling to drive
The filling electric current of VCM.
An aspect of of the present present invention be include digital to analog converter (DAC), wave filter, current sink (current sink) with
And the VCM driver of resonance calibration module.DAC produces subsequently can be by the voltage of filter by-pass, filtering or shaping.
This Control of Voltage current sink produces and fills electric current.In response to free oscillation, self calibration module is used for during calibrating freedom
Frequency of oscillation and damped coefficient are calibrated, and thereafter, produce filter control signal according to the parameter that these are calibrated, with
Lens control wave filter during location.
Another aspect of the present invention is self calibration ring compensation method, and the method includes: produces and causes free-running filling electric current；
Measure free oscillation frequency and damped coefficient, to determine filter control signal；And VCM driver configuration is produced
Compensate free-running second and fill electric current.Such self calibration ring compensates and makes can closely follow the trail of free oscillation, and permissible
Improve expeditiously lens stabilization time and improve photographing module automatically focus on speed.
Particularly unique feature of the present invention and advantage are integrally described in this " summary of the invention " part；But, additional spy
Levy, advantage and embodiment are presented in this article, or general to this area of these supplementary features, advantage and embodiment
For logical technical staff, would is that significantly on the basis of reading the accompanying drawing of the present invention, specification and claims.Cause
This, it should be appreciated that the scope of the present invention should be by particular disclosed in this " summary of the invention " part
Restriction.
Accompanying drawing explanation
Will be with reference to embodiment of the present invention, the example of embodiment of the present invention can be illustrated in the accompanying drawings.These
Accompanying drawing is intended to exemplary rather than restrictive.Although the present invention in the context of these embodiments by integrally
Describe, it should be appreciated that be not intended to be limited to the scope of the present invention these particular.
Figure 1A illustrates the typical relation between the lens displacement of lens actuator based on VCM and filling electric current.
Figure 1B illustrates the automatic focus value (AFV) climbed the mountain in the closed loop auto focusing method controlled based on standard with saturating
Relation between mirror position.
Fig. 2 illustrates and fills lens position that electric current drives, that lens actuator based on VCM is associated with by step
Exemplary timing chart.
Fig. 3 illustrates the block diagram of the photographing module according to various embodiments of the present invention.
Fig. 4 A illustrates the exemplary self calibration being incorporated to self calibration ring compensation according to various embodiments of the present invention
VCM driver.
Fig. 4 B illustrates the block diagram of the self calibration module according to various embodiments of the present invention.
Fig. 4 C illustrates the back-EMF signal according to various embodiments of the present invention and treated back-EMF signal
Exemplary time domain plot.
Fig. 5 A and Fig. 5 B illustrate the described wave filter according to various embodiments of the present invention in free oscillation frequency
Filtered fills electric current convert signals and the exemplary time domain plot of corresponding frequency response.
Fig. 6 illustrates some the exemplary filling electric currents compensated for ring according to various embodiments of the present invention.
Fig. 7 illustrates the example between the oscillation stability time according to various embodiments of the present invention and filter constants
Property rely on curve.
Fig. 8 illustrate according in the photographing module of various embodiments of the present invention self calibration ring compensate exemplary
Method.
Fig. 9 A illustrates the actuator drive being loaded with AF actuator 902 according to various embodiments of the present invention
Block diagram.
Fig. 9 B illustrates the self calibration ring according to the AF actuator in the photographing module of various embodiments of the present invention
The illustrative methods compensated.
Detailed description of the invention
In the following description, for purposes of illustration, for providing the understanding of the present invention, detail is elaborated.So
And, would is that to one skilled in the art it is evident that the present invention can also be put into practice without these details.Ability
Skilled artisan will appreciate that of territory, the embodiment of invention described below can in every way and use various
Structure realizes.Those skilled in the art is it will further be appreciated that additional amendment, application and embodiment are in the present invention
In the range of, as the additional fields that the present invention can provide use.Therefore, embodiments described below is this
The exemplary illustration of bright specific embodiments, and it is intended to the present invention that avoids confusion.
Description is quoted for " embodiment " or " embodiment " and means to combine what this embodiment described
Special characteristic, structure, characteristic or function are included at least one embodiment of the present invention.Each ground in description
The phrase " in one embodiment " of side's appearance, " in embodiments " etc. need not all refer to same embodiment.
Additionally, connection between parts or between method step is not limited to the connection being directly realized by accompanying drawing.On the contrary,
Without departing from the teachings of the present invention, the connection between the parts illustrated in accompanying drawing or between method step can
To be modified or to change by adding intermediate member or method step betwixt.
Load lensed voice coil motor (VCM) and form the mechanical oscillating system that can vibrate with free oscillation frequency.This
The free-running free oscillation frequency of sample depend on VCM coil rigidity, load lensed VCM gross mass and
The damped coefficient of VCM.Free oscillation frequency is different for loading lensed each specific VCM, specifically,
The change of damped coefficient (such as, gaseous environment) can also cause the skew of free oscillation frequency.
In the case of step fills electric current (Fig. 2), the free oscillation of VCM is easily by the filling electricity being in free oscillation frequency
Stream causes, and reaches peak value at different frequency even if filling electric current in a frequency domain and has decayed to slightly in this free oscillation frequency
Degree.Free-running amplitude and both of which stabilization time are directly associated in the amplitude of this free oscillation frequency with filling electric current.For
Realize quickly automatically focusing on speed, need suppression or reduce free oscillation, and method for optimizing be to reduce free oscillation frequency
Filling electric current at rate, therefore, compensates the free oscillation (that is, ring) at free oscillation frequency.
High efficiency ring compensation method is based preferably on the accurate alignment of free oscillation frequency, because free oscillation frequency exists
Difference between VCM, and due to aging effect, even for same VCM, drift about the most in time.The present invention's is various
Embodiment relates to self calibration ring compensation method, and the method reduces the free oscillation of VCM, and allows in photographing module
Automatic focusing in fast automatic focusing convergence time.
Fig. 3 illustrates the block diagram 300 of the photographing module according to various embodiments of the present invention.Photographing module
300 include that lens 302, shutter 304, voice coil motor (VCM) 306, self calibration VCM driver 308, VCM are controlled
Device 310 processed, image processing processor 312 and image sensor array 314.Photographing module 300 is by VCM 306
Free oscillation frequency carry out calibration and compensate to be incorporated to self calibration ring, and produce the filling electric current 316 through overcompensation, this filling
Electric current 316 reduces in this free oscillation frequency, in order to reduce the free oscillation being associated of VCM 304.
Lens 302 couple with shutter 304 and VCM 306.Specifically, lens 302 attach to VCM 306.Lens
302 receive light during exposure period and before exposure period 304, and VCM 306 drives in automatic focusing
Lens 302 move back and forth and stop in focal position.For each lens locator step in automatic focusing,
VCM 306 and lens 302 experienced free oscillation before settling out at lens position.
VCM 306 couples with self calibration VCM driver 308, and self calibration VCM driver 308 produces and drives VCM 306
Filling electric current 316.The filling electric current 316 being injected into VCM coil works together with permanent magnet, to produce Lorentz force, and
And along VCM coil mobile lens 302.Step fill electric current generally be generated to drive VCM 306, but, with due to
The relatively long stabilization time being loaded with the free oscillation of the VCM 306 of lens 302 and cause is associated.The present invention's
In various embodiments, step fills electric current and still may be used for triggering free oscillation and make can be to being loaded with lens 302
The free oscillation frequency of VCM 306 is calibrated.
One skilled in the art will appreciate that the filling electric current in addition to step fills electric current can be used for free oscillation frequency is carried out school
Standard, but step fills electric current and can have simplest form, and be easily achieved.In one embodiment, one it is in
Determine the sinusoidal electric current that fills of frequency for free oscillation frequency is calibrated.Current amplitude can be fixing, and sinusoidal filling electricity
The frequency of stream changes over a frequency range, and causes the filling electric current of the oscillation amplitude of maximum to be associated with free oscillation frequency.
Self calibration VCM driver 308 couples with VCM controller 310, and receives electricity from VCM controller 310
Flow control signals 318.In the various embodiments of the present invention, VCM controller 310 can also be included in self calibration VCM
In driver 308.Current controling signal 318 at least includes the current amplitude data for limiting the amplitude filling electric current 316.
In certain embodiments, the current controling signal 318 built-in integrated circuit (I by standard2C) bus is at self calibration VCM
Transmit between driver 308 and VCM driver controller 310, this I2C bus uses two bidirectional lines (serial datas
Line (SDA) and serial clock (SCL)).
In certain embodiments, VCM 306 also includes wave filter, and this wave filter changes filling electric current distribution in the time domain
To reduce free oscillation.Resonance and damped coefficient calibration process are used for producing filter control signal.In one embodiment,
Filter control signal is disabled simply makes filter by-pass, carries out free oscillation frequency so that output step fills electric current
Calibration.In another embodiment, filter control signal is enabled to suppress or reduce filling electricity during automatic focusing
Flow the amplitude at free oscillation frequency in a frequency domain.
Photographing module 300 includes another image processing path, and this image processing path includes lens 302, imageing sensor 314
With image-signal processor 312.Image is projected on image sensor array 314 by lens 302, image sensor array
314 produce raw video signal 320 from this image.In one embodiment, image sensor array 314 includes multiple
CCD (charge-coupled image sensor) sensor.Image-signal processor 312 couples with image sensor array 314.Original regard
Frequently signal is further magnified in image-signal processor 312, nurses one's health and be converted to digital form.
In certain embodiments, images above processes path for providing about when lens 302 to VCM controller 310
The feedback information of picture quality when being actuated to lens position under the control filling electric current.Picture quality can use picture quality
Parameter (such as picture contrast) carrys out quantization signifying.In one embodiment, step fills electric current and is generated to driving VCM
306, and picture contrast is by image-signal processor 312 real-time tracing.VCM controller 310 is coupled to receive reality
Time picture contrast.Time period between two contrast peak values is for obtaining the free-running free oscillation of VCM 306
Frequency.Therefore, VCM controller 310 can produce electric current control letter according to the time period between two contrast peak values
Number, and in automatic focusing subsequently, this current controling signal is used for controlling self calibration VCM driver 308 and produces
The raw filling electric current reduced at this free oscillation frequency.
In another embodiment, in automatic focusing, image quality parameter is produced by image-signal processor 312,
And it is used for determining whether filling current step completes by VCM controller 310.In fig. ib, automatic focusing includes
Three steps, coarse scanning, close scanning and finally position, these steps each include multiple lens locator step,
Being each associated with filling electric current conveying and lens location in these lens locator steps.Therefore, image quality parameter etc.
It is same as the automatic focus value previously presented in fig. ib.In one embodiment, stable when the change of image quality parameter
Time below a certain value, it is believed that a sub-steps completes, and lens can be moved on to next lens position.Automatically focusing on
At the end of process, focal position is associated with optimal image quality parameter.In one embodiment, focal position is with whole
Hi-vision contrast during individual automatic focusing is associated.
Fig. 4 A illustrates the self calibration VCM being incorporated to self calibration ring compensation according to various embodiments of the present invention
The block diagram 400 of driver.VCM driver 400 include digital to analog converter (DAC) 406, wave filter 408,
Current sink 410 and self calibration module 430.VCM driver 400 receives electric current from VCM driver controller and controls
Signal 404, these current controling signals include the current amplitude data being associated with object lens position.This VCM drives
The free oscillation frequency of VCM motor 306 and damped coefficient that are loaded with lens 302 are calibrated by device 400, and root
Filling electric current is produced according to the parameter of current controling signal and/or these calibrations.
DAC 406 is coupled to receive current controling signal, and produces filling voltage (sink according to current amplitude data
vo1tage).Wave filter 408 couples with DAC 406, and receives filling voltage and filter control signal.Real at some
Executing in scheme, wave filter 408 is digital filter, and can be directly coupled and be sent to by current controling signal
Receive and process current controling signal before DAC 406.
In the various embodiments of the present invention, wave filter 408 can include multiple signal transformation circuit, each signal shaping
Circuit can individually be adjusted.Wave filter 408 configures according to filter control signal, therefore, based on corresponding filtering
It is distributed and filling voltage or current controling signal are filtered.Specifically, the filling voltage quilt of gained in a certain frequency range
Suppression or reduction, and this certain frequency range covering free oscillation frequency.
In one embodiment, wave filter 408 includes that one or more can being enabled according to filter control signal are joined
Put.In a certain embodiment, wave filter 408 includes band elimination filter, and a certain frequency band is near free oscillation frequency
It is prevented from.The frequency band being prevented from can be adjusted according to filter control signal.In a certain embodiment, FILTER TO CONTROL
Signal can make filter by-pass, and is produced without step filling voltage after filtering.
Current sink 410 couples with wave filter 408, and is converted to filling voltage be further used for driving VCM 306
In the filling electric current of VCM coil 402.In a frequency domain, current sink 410 behaves like and has far above free oscillation
The low pass filter of the cut-off frequency of frequency.As a result, fill electric current and adapt to the band resistance near free oscillation frequency, and cause adding
It is loaded with the free oscillation of the reduction of the VCM 306 of lens 302.
VCM driver 400 uses self calibration module 430 rather than the figure picture element provided by image-signal processor 312
Amount parameter identifies free oscillation frequency and corresponding filter control signal.Self calibration module is coupled to receive back-EMF
Signal, this back-EMF signal can extract from VCM coil 402, and be associated with lens position/displacement.In freedom
In the duration of oscillation, back-EMF signal shows decay and is stabilized to the electric oscillation of a certain voltage levvl.Therefore, self calibration module 430
For processing back-EMF signal, identifying free oscillation frequency and damped coefficient and produce filter control signal.
During free-running self calibration, wave filter 408 is bypassed, so that step fills electric current and can be injected into VCM
Coil 402.Filter control signal subsequently by self calibration module 430 according to calibration parameter identification.In automatically gathering subsequently
During Jiao, this filter control signal may be used for so that the configuration of a certain wave filter can suppress or reduce free oscillation frequency
The filling electric current at place.
Fig. 4 B illustrates the block diagram 430 of the self calibration module according to various embodiments of the present invention.Self-correcting
Quasi-mode block 430 includes gain stage 432, low pass filter 434, base line restorer (restorer) 436, zero-crossing detector
416, duration of oscillation section circuit 418, peak detector 420 and antihunt circuit 422.
It is anti-that gain stage 432, low pass filter 424 and base line restorer 436 are initially used in conditioning self calibration module 430
EMF signal.Fig. 4 C illustrate the back-EMF signal according to various embodiments of the present invention and treated instead
The exemplary timing chart 480 and 490 of EMF signal.Back-EMF signal 480 is associated with lens position, and shows to decline
Subtract and be stabilized to the electric oscillation of baseline voltage.Base line restorer 436 removes the input produced by the steady-state current flowing through VCM
Offset (off-set) voltage.Gain stage 432 reference baseline voltage amplification back-EMF signal.Low pass filter 434 is for right
Back-EMF signal is filtered removing high-frequency noise.
Zero-crossing detector 416 and duration of oscillation section circuit 418 form path 460, to believe according to treated back-EMF
Number free oscillation frequency determine filter control signal.Zero-crossing detector 416 detect treated EMF signal across
More moment during null value (that is, ground).Duration of oscillation section circuit 418 is subsequently used in and determines duration of oscillation section, and produces
The filter control signal being associated with duration of oscillation section and corresponding free oscillation frequency.
Peak detector 420 and antihunt circuit 422 form path 470, to determine that FILTER TO CONTROL is believed according to damped coefficient
Number.Peak detector 420 detects its amplitude when back-EMF signal reaches peak value.Antihunt circuit 422 is subsequently by these
The amplitude of peak value is compared to determine the damped coefficient of actuator.In a certain embodiment, if amplitude is at continuous peak value
Between be remarkably decreased, then damped coefficient is big, in this embodiment it is not even necessary to wave filter.As a result, path 460 and 470 is respectively used to determine
The frequency of wave filter 408 and power.
Fig. 5 A illustrates showing of the filling electric current reduced at free oscillation frequency according to various embodiments of the present invention
Example sequential chart 500, Fig. 5 B illustrates the respective frequencies response filling electric current according to various embodiments of the present invention
550.The free oscillation frequency of VCM 306 is first calibrated for, and in frequency fOSCPlace is identified.Use wave filter 408
Subsequently in free oscillation frequency f filling electric currentOSCNeighbouring generation stops.In certain embodiments, electric current is filled when application step
Time, lens may spend 5-10 free period to settle out in object lens position, and in fig. 5,
Self calibration ring compensates and reduced punching, and lens position can be settled out within less than a cycle of oscillation.
If those skilled in the art is it will be appreciated that the free oscillation of lens decays to be examined by image-signal processor 312
Below the threshold amplitude measured, if or the amplitude of back-EMF signal that is associated be down to below insignificant threshold voltage,
Then lens position is considered as to settle out in target location.
It will be appreciated by those skilled in the art that, ring compensates the filling electric current being not limited in Fig. 5 A and Fig. 5 B, and interchangeable
Filling electric current can also be according to filter control signal for reducing punching and improving free-running stabilization time.Fig. 6 figure
Show and illustrate some the exemplary filling electric currents compensated for ring according to various embodiments of the present invention.These fill electric current bag
Include double step and fill electric current 602, double slanted filling electric current 604, single slope current 606 and low pass filling electric current 608.Various electric currents are whole
Shape configuration can be incorporated in wave filter 408, to carry out filling electric current shaping and to produce these exemplary filling electric currents.With this
Mode, wave filter 408 is used as current shaping module.
Fill electric current 602-608 in start time from zero current or electric current I0Initial, and at moment TVCMTMRise to electric current
I1.Zero current is associated with unlimited distance focus, and electric current I0It is associated with initial lens position.Electric current 602 is filled in double steps
In, I by a small margin01It is enabled in start time, and rises to target filling electric current I with VCMTM time delay1.Double
Slope fills in electric current 604, continuous application two-part piecewise linearity electric current.First electric current in start time from electric current I0It is initial,
And at moment TVCMTM/ 2 with electric current I0+AVCMA*TVCMTM/ 2 terminate, wherein, and AVCMAIt is that electric current increases speed.
Second electric current is at moment TVCMTM/ 2 terminate to initiate from the first electric current, and at moment TVCMTMWith electric current I1Terminate.Monocline
Slope electric current 606 includes single current linearity range, and this section initiateed from zero in start time, and at moment TVCMTMReach electricity
Stream I1.Low pass fills electric current 608 and utilizes gauss low frequency filter to be shaped based on built-in 64 word look-up tables.
Parameter TVCMTMCharacterize electric current 602-608 and reach target filling electric current I1Time.Filling electric current 602-608 can be by filtering
Signal transformation circuit in ripple device 408 produces, therefore, and parameter TVCMTMFilter constants or power with wave filter 408
It is associated.Less TVCMTMMore sharp-pointed electric current transformation is generally associated with bigger filter constants.Fig. 7 illustrates
Illustrate between the oscillation stability time according to various embodiments of the present invention and general filter constants exemplary depends on
Rely curve 700.This dependence curve 700 is associated with single slope curve 606.Best region 702 is identified as at wave filter
Constant α1With α2Between, and in best region 702, oscillation stability time is at low value TsettlePlace is suppressed.Bigger
Or less filter constants makes increase stabilization time, and ratio may be easily caused when simple step filling electric current is not utilized
The stabilization time that stabilization time of situation during wave filter is even worse.In certain embodiments, the width of best region 702 is
The +/-10% of the amplitude of center-filter constant or the amplitude less than center-filter constant.Filter control signal is used for root
Wave filter 408 is configured according to filter constants.Filter control signal is preferably updated frequently, even if so that when certainly
During by oscilator drift, wave filter 408 is also maintained in best region 702.
The self calibration that Fig. 8 illustrates according to the VCM driver in the photographing module of various embodiments of the present invention shakes
The illustrative methods 800 that bell compensates.In step 802, produce the first filling electric current, and this first filling electric current is transported to VCM
Coil 402.First fills electric current is associated with the VCM 306 being loaded with lens 302 for mobile lens 302 and causing
Free oscillation.In one embodiment, the first filling electric current is the step current connected in start time, and is not related to
Filtering or current shaping are preferably to keep free oscillation.In another embodiment, the first filling electric current is sine-wave current,
And frequency changes, to cause various mechanical response.
In step 804, during free oscillation, measure free oscillation frequency and damped coefficient, and come according to the two parameter
Determine filter control signal.In the various embodiments of the present invention, these parameters can be processed by monitor image signal
The quality of the image that device 312 is caught or produce by following the trail of the signal of telecommunication being associated with lens position.Step 802 and
804 are associated with the self-calibration mode of photographing module.
In step 806, filter control signal is used VCM driver configuration to be produced during lens position fixing process
Compensate free-running second and fill electric current.Lens position fixing process can be the sub-step in automatic focusing.An enforcement
In scheme, band elimination filter may be used for carrying out electric current shaping, and the free oscillation that current sink output is in a frequency domain
There is at frequency the amplitude of reduction.In the various embodiments of the present invention, interchangeable current shaping method can be used for
Compensate from free-running ring.Exemplary filling electric current includes that double step, double slanted, monocline slope, low pass fill electric current
602-608, and each filling electric current can realize by configuring wave filter.Filter constants can include a best region,
This best region is effectively suppressed from free-running ring/reduces.Step 806 and the lens in photographing module
Station-keeping mode is associated.
Self-calibration mode can be realized continually, really to protect the compensation of the accurate ring during the life-span of photographing module.One
In individual embodiment, before photographing module dispatches from the factory, it is possible to use self-calibration mode.In certain embodiments, take the photograph every time
As module powers on, or when smart phone is switched to image pickup mode every time, just use this pattern.Calibrate based on constant, shake
Bell compensates and is maintained at enough levels, and makes photographing module can have fast automatic focusing convergence time.
It would be recognized by those skilled in the art that self calibration ring compensates and can be applicable to other lenses actuator (the most digital step
Enter motor, piezoelectric motor or MEMS actuator) in.These lens actuators can be driven by voltage.Therefore, freely
Frequency of oscillation and damped coefficient are calibrated to adjust filtering or the voltage shaping of voltage, therefore, reduce free oscillation.Lens
To be modified to stabilization time make it possible to realize fast automatic focusing convergence time.
The actuator being loaded with AF actuator 902 that Fig. 9 A illustrates according to various embodiments of the present invention drives
The block diagram 900 of device.Actuator drive 900 includes digital to analog converter (DAC) 906, wave filter 908 and self-correcting quasi-mode
Block 930.Actuator drive 900 receives amplitude control signal 904, and these amplitude control signal include and object lens position
Put the current amplitude data being associated.DAC 906 and wave filter 908 produce the voltage signal driving actuator 902.In order to
Driving VCM, as described in illustrated in Fig. 4 A, actuator drive 900 can also include producing from voltage signal filling electric current
Current sink.Inverted signal is associated with lens position, and self calibration module 930 produces wave filter control from this inverted signal
Signal processed.Wave filter 908 is configured to voltage signal is carried out shaping and suppresses/reduce by filter control signal
Free oscillation during mirror location.
The self calibration that Fig. 9 B illustrates according to the AF actuator in the photographing module of various embodiments of the present invention shakes
The illustrative methods 950 that bell compensates.In step 952, produce the first signal driving AF actuator.This first signal can
To be voltage or electric current.In step 954, measurement free oscillation frequency and damped coefficient during free oscillation, and according to
The two parameter determines filter control signal.In step 956, the first control signal is used actuator drive to be joined
Put and produce the free-running secondary signal of compensation.
Although the present invention is easily formed various amendment and replaceable form, its specific embodiment be illustrated the most in the accompanying drawings and
It is described in detail in this article.It is to be understood, however, that the invention is not restricted to particular forms disclosed, just the opposite
, the present invention falls into all modifications of scope of the following claims, equivalents and alternative forms by containing.
Claims (20)
1. driving a driver for automatic focus actuator in photographing module, described driver includes:
Signal generator, described signal generator receives output control signal, and described signal generator produces the first signal, institute
State output control signal to be associated with the target location of described automatic focus actuator；
Self calibration module, described self calibration module couples with described automatic focus actuator, and described self calibration module is to freely shaking
Swing characteristic and carry out calibrating and producing the filter control signal of correspondence；
Wave filter, described wave filter couples with described signal generator and described self calibration module, and described wave filter is configured to
Secondary signal is produced from described first signal according to described filter control signal；And
Wherein, described secondary signal is coupled to described automatic focus actuator is driven into described target location, described shooting
The lens of module attach to described automatic focus actuator, and when described automatic focus actuator is controlled in described target
When position settles out, described filter control signal is associated with the free oscillation of reduction.
2. driver as claimed in claim 1, also includes:
Current sink, described current sink couples with described wave filter, and described current sink produces from described secondary signal
Raw filling electric current, described automatic focus actuator is driven into described target location by described filling electric current.
3. driver as claimed in claim 2, wherein said filling electric current initiates and according to CURRENT DISTRIBUTION from initial current
Reach target current, the group of described CURRENT DISTRIBUTION choosing free herein below composition: double step currents, double slanted electric current, monocline
Slope electric current and low galvanization.
4. driver as claimed in claim 2, wherein said filling electric current is as single slope current from initial current linearly
Increase to target current, and described wave filter is configured and constantly adjustment is maintained in best region, so that described
Automatically it is kept the stabilization time of focus actuator.
5. driver as claimed in claim 1, wherein said automatic oscillating characteristic includes free oscillation frequency and damping system
Number.
6. driver as claimed in claim 1, wherein said self calibration module is caused from described automatic focusing by monitoring
Described free oscillation characteristic is calibrated by the feedback signal of dynamic device, described feedback signal and the position of described lens and displacement
It is associated.
7. driver as claimed in claim 1, wherein said signal generator is described output control signal to be converted to
The digital to analog converter (DAC) of described first signal, described first signal is analog voltage.
8. driver as claimed in claim 1, wherein carries out school when described self calibration module to described free oscillation characteristic
On time, described wave filter is bypassed by described first signal, so that step current absorber can drive described automatic Focus Actuator
Device.
9. driver as claimed in claim 1, wherein said target location and the sub-steps in automatic focusing
Being associated, described automatic focusing includes coarse scanning, close scanning and finally positions.
10. driver as claimed in claim 1, wherein said wave filter is with the freedom by described self calibration modular calibration
Band elimination filter centered by frequency of oscillation.
The method that self calibration ring in automatic focus actuator in 11. 1 kinds of photographing modules compensates, described method include with
Lower step:
Producing the first signal, described first signal causes the free oscillation in described automatic focus actuator；
Measure free oscillation characteristic to determine filter control signal；
Producing secondary signal according to described filter control signal, described secondary signal is coupled to described automatic Focus Actuator
Device is driven into target location, and the lens of described photographing module attach to described automatic focus actuator；And
Wherein, it is controlled to the described FILTER TO CONTROL when described target location settles out when described automatic focus actuator
Signal is associated with the free oscillation of reduction.
12. methods as claimed in claim 11, wherein, the step of the described secondary signal of described generation also includes following step
Rapid:
Initial signal is produced from the output control signal being associated with the target location of described automatic focus actuator；
Wave filter is configured according to described filter control signal；And
It is filtered producing described secondary signal to described initial signal.
13. methods as claimed in claim 12, wherein said secondary signal is converted into filling electric current, described filling electric current from
Initial current initiates, and reaches target current according to CURRENT DISTRIBUTION, the group of described CURRENT DISTRIBUTION choosing free herein below composition:
Double step currents, double slanted electric current, single slope current and low galvanization.
14. methods as claimed in claim 11, wherein said free oscillation characteristic includes free oscillation frequency and damping system
Number.
15. methods as claimed in claim 11, wherein by monitoring the feedback signal from described automatic focus actuator
Calibrating described free oscillation characteristic, described feedback signal is associated with position and the displacement of described lens.
The driver of 16. 1 kinds of voice coil motors driven in photographing module (VCM), described driver includes:
Digital to analog converter (DAC), described DAC receives current controling signal, and described DAC produces the first voltage, institute
Stating current controling signal to be associated with the target location of described VCM, the lens of described photographing module attach to described VCM；
Self calibration module, described self calibration module couples with described VCM, described self calibration module to described VCM from
Carried out calibrating and producing the filter control signal of correspondence by oscillating characteristic；
Wave filter, described wave filter couples with described DAC and described self calibration module, and described wave filter is configured to basis
Described filter control signal produces the second voltage from described first voltage；And
Current sink, described current sink couples with described wave filter, and described current sink produces from described second voltage
Life fills electric current and described VCM is driven into described target location, is wherein controlled in described target as described VCM
When position settles out, described filter control signal is associated with the free oscillation of reduction.
17. drivers as claimed in claim 16, wherein said filling electric current is linear from initial current as single slope current
Increase to target current, and described wave filter is configured and constantly adjusts and is maintained in best region so that
The stabilization time of VCM is kept.
18. drivers as claimed in claim 16, wherein said free oscillation characteristic includes free oscillation frequency and damping
Coefficient.
19. drivers as claimed in claim 16, wherein said self calibration module is by monitoring from described VCM's
Described free oscillation characteristic is calibrated by feedback signal, and described feedback signal is associated with position and the displacement of described lens.
20. drivers as claimed in claim 16, are wherein carried out described free oscillation characteristic when described self calibration module
During calibration, described wave filter is bypassed by described first signal, so that step current absorber can drive described VCM.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US201161502788P | 2011-06-29 | 2011-06-29 | |
| US61/502,788 | 2011-06-29 | ||
| US13/533,039 US8964102B2 (en) | 2011-06-29 | 2012-06-26 | Self-calibrated ringing compensation for an autofocus actuator in a camera module |
| US13/533,039 | 2012-06-26 |
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| CN102854699A CN102854699A (en) | 2013-01-02 |
| CN102854699B true CN102854699B (en) | 2016-11-16 |
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| CN201210226888.1A Active CN102854699B (en) | 2011-06-29 | 2012-06-29 | The self calibration ring of the automatic focus actuator in photographing module compensates |
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| CN103345037A (en) * | 2013-07-04 | 2013-10-09 | 聚辰半导体(上海)有限公司 | Reshaping signal control method of camera voice coil motor actuator |
| US9513456B2 (en) * | 2014-06-20 | 2016-12-06 | Texas Instruments Incorporated | Lens driver circuit with ringing compensation |
| US9716833B2 (en) * | 2014-09-02 | 2017-07-25 | Qualcomm Incorporated | Actuator ring characteristic measurement method |
| KR101783832B1 (en) * | 2015-04-27 | 2017-10-10 | 주식회사 동운아나텍 | Apparatus for driving voice coil actuator of camera and method thereof |
| CN107040175A (en) * | 2016-02-04 | 2017-08-11 | 西安中兴新软件有限责任公司 | Voice coil motor starts control method and device, camera module |
| CN105785707B (en) * | 2016-05-24 | 2018-11-02 | 昆山丘钛微电子科技有限公司 | VCM integrated performance test methods and system |
| US9964732B1 (en) * | 2017-05-15 | 2018-05-08 | Semiconductor Components Industries, Llc | Methods and apparatus for actuator control |
| CN109981869B (en) * | 2017-12-27 | 2020-10-02 | 宁波舜宇光电信息有限公司 | Method and test equipment for measuring oscillation period of lens actuator based on image technology |
| KR102561934B1 (en) * | 2018-03-14 | 2023-08-01 | 삼성전기주식회사 | Actuator of camera module |
| CN111082715B (en) * | 2019-12-31 | 2021-08-31 | 普冉半导体(上海)股份有限公司 | Voice coil motor driver drive current segmentation control circuit |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US6577343B2 (en) * | 1996-12-03 | 2003-06-10 | Canon Kabushiki Kaisha | Image pickup apparatus with lens control apparatus and focusing lens control |
| CN101616262B (en) * | 2005-02-07 | 2012-07-25 | 松下电器产业株式会社 | Imaging device |
| US7768878B2 (en) * | 2005-07-12 | 2010-08-03 | Hewlett-Packard Development Company, L.P. | Actuator calibration using a focus error signal |
| US7769281B1 (en) * | 2006-07-18 | 2010-08-03 | Siimpel Corporation | Stage with built-in damping |
| JP5330718B2 (en) * | 2008-03-19 | 2013-10-30 | シャープ株式会社 | Camera system, voice coil motor driving device, and voice coil motor driving method |
| CN101930150B (en) * | 2009-06-18 | 2012-01-04 | 三洋电机株式会社 | Focus control circuit |
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