CN1635780A - Linear array CCD optical integral time self-adaptive control method and apparatus - Google Patents
Linear array CCD optical integral time self-adaptive control method and apparatus Download PDFInfo
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Abstract
A line scan CCD optical integration time self-adaptive control method, which contains 1, estimating line scan CCD corresponded optical integration time according to relative parameter of line scan CCD output signal, 2, controlling line scan CCD driving time sequence generator according to estimated optical integration time and generating the driving pulse sequence needed in CCD normal work, said driving pulse sequence containing integration pulse sequence, transferring pulse sequence and reset pulse sequence, 3, line scan CCD output adjusted optical integration time signal by driving of pulse sequence, preprocessing and calculating said signal to extract correlation parameter of line scan CCD output signal, 4, comparing the correlation parameter of extracted CCD line scan output signal with preset threshold value, when the value is exceeds the threshold value, adjusting again by step 1, 2, 3, until the parameter is in preset threshold value range, 5, automatically completing adjustment of optical integration time.
Description
Technical field
The present invention relates to a kind of the line array CCD optical-integral-time be carried out Method of Adaptive Control and device.
Background technology
CCD is widely used at aspects such as non-cpntact measurement, image sensing and storages.Line array CCD has characteristics such as the pixel number is many, pixel dimension is little, speed is fast, splicing is ripe, certainty of measurement is high, price is low.As the TCD1500C that Toshiba Corp produces, effectively the pixel number is 5340, pixel dimension 7 μ m * 7 μ m, maximum operation frequency 20MHz.Because These characteristics, line array CCD is easy to realize the high-acruracy survey and the location of one dimension size.
In the actual measuring system, whether the dynamic range of image and CCD dynamic range are mated and will be produced very big influence to the certainty of measurement of system.Under the certain condition of optical-integral-time,, and then cause the ccd output signal distortion if intensity of illumination crosses and can cause by force that the photosensitive unit integral charge is saturated to be overflowed; If intensity of illumination is too small, will cause the signal to noise ratio of ccd output signal less, be unfavorable for the extraction of useful signal.Though prior art solves to a certain extent to some extent to this problem, all there is the deficiency of self.In measuring dynamically, in real time, because the luminous intensity change at random of target or background and often can't effectively being controlled, allow time of measuring shorter simultaneously, thereby prior art is difficult to adapt to dynamically, Testing requirement in real time.Simultaneously, when the output signal of system requirements CCD reflected original image information preferably, prior art also was difficult to meet the demands.
At application number is 01116570.7, discloses in the patent of invention people for people such as Deng Zhonghan a kind ofly in the certain exposure cycle of optical-integral-time each pixel repeatedly to be sampled, to judge the saturation of this pixel.Reached the best saturated upper limit in case judge the output signal of this pixel, the signal value of storage this moment is not then just carrying out record from the follow-up digital image signal of this pixel.Though this invention has realized the adjusting of optical-integral-time to a certain extent, also there are many tangible deficiencies, specific as follows:
1 this invention is the regulative mode of in the certain exposure cycle of optical-integral-time the pixel output signal repeatedly being sampled owing to what adopt, thereby the optical-integral-time adjustable range is limited, and maximum is no more than the given optical-integral-time of this exposure cycle.This given optical-integral-time can not be controlled automatically with target or environment change of luminous intensity, thereby this invention will be no longer suitable when dynamic range of images is big;
2 should invent because the optical-integral-time of exposure cycle is certain, thereby can only effectively regulate over-exposed in the exposure cycle, then inoperative to under-exposure;
3 these inventions will all be carried out saturation to each pixel or each zone and judge, the signal when latching optimum exposure all is controlled at the saturated level of closing on the output amplitude of each pixel.Because the saturation value of each pixel is identical among the same CCD, thereby this method easily causes the serious distortion of ccd output signal, can't reflect the information of original image;
4 these inventions judge that this will cause the hardware circuit complexity, and hardware process speed is had higher requirement owing to will carry out saturation to each pixel.Authorize people's such as Degi United States Patent (USP) the 5th, 479, disclose for No. 207 and a kind ofly controlled the method for line array CCD optical-integral-time by insert shifting pulse number, but this invention how to relate to according to the variation of target and background luminance to optical-integral-time do not carry out automatically, adjusting fast.This invention is by a previously selected reference object is exposed, the manual adjustments optical-integral-time reaches the requirement of expection up to the amplitude of output signal, the optical-integral-time of this moment both had been the calibration value of system's optical-integral-time, and system's this calibration value in the course of work after this remains unchanged.There is following drawback in this invention:
1) optical-integral-time intensity of illumination according to reference object before system's operate as normal is demarcated in advance, and optical-integral-time remains unchanged in the course of work after this, thereby this system can not regulate optical-integral-time according to the change of intensity automatically according to target or background luminescence in the course of the work;
2) nominal light will delay the reaction speed of system the time of integration in advance, makes system can not satisfy real-time Testing requirement;
3) being used for the target luminous intensity that optical-integral-time demarcates should be complementary with the actual measurement target, otherwise the time for exposure that sets with inaccurate, can not reach the purpose of optimizing ccd output signal.Thereby when target luminous intensity change at random, can't select the reference object of suitable luminous intensity and carry out the demarcation of optical-integral-time, thereby can't reach its intended purposes.
Application number is 00106442.8, invents in the patent that artificial Chen Yan becomes and discloses the method that a kind of power-on time by control power supply illumination apparatus is controlled the photosensitive unit optical-integral-time.The limitation of this method is: owing to adopted the controlled target fluorescent lifetime to control the method for the optical-integral-time of photosensitive unit, thereby when the fluorescent lifetime of measuring object is uncontrollable, then inapplicable.
Summary of the invention
The invention solves background technology in measuring dynamically, in real time, when the luminous intensity change at random of target or background and can't effectively be controlled the technical problem that allows Measuring Time will no longer be suitable for more in short-term simultaneously.
Technical solution of the present invention is: its special character is: above-mentioned
A kind of line array CCD optical-integral-time self-adaptation control method, it is characterized in that: this method comprises
1], estimates the pairing optical-integral-time of line array CCD according to the relevant parameter of line array CCD output signal;
2] utilize the optical-integral-time that estimates, the control line array CCD drives timing sequencer, produces the required driving pulse sequence of line array CCD operate as normal, and described driving pulse sequence comprises the integrated pulse sequence, shifts pulse train and reset pulse sequence;
3] line array CCD output optical-integral-time signal through overregulating under the driving pulse sequence drives after preliminary treatment, extracts the relevant parameter of line array CCD output signal with this signal once more by calculating;
4] relevant parameter and the pre-set threshold with the line array CCD output signal extracted compares, when exceeding threshold range, through 1], 2], 3] optical-integral-time is regulated once more, fall into the pre-set threshold scope up to parameter value;
5] the automatic adjusting of optical-integral-time is finished.
2 line array CCD optical-integral-time self-adaptation control methods according to claim 1 is characterized in that: the estimation of described optical-integral-time is to realize by A/D converting unit and a slice CPLD device (CPLD); It is by realizing in a slice CPLD device (CPLD) that described control line array CCD drives timing sequencer.
3 line array CCD optical-integral-time self-adaptation control methods according to claim 1 and 2 is characterized in that: the required driving pulse sequence of described generation line array CCD operate as normal by required each the road signal of CCD all by under optical-integral-time control to input clock count, frequency division produces; Described counting, frequency division adopt a basic counter, and after the value of counter arrived the optical-integral-time designated value, a frame end resetted each road signal, and receives the new time of integration, begins the generation of a new frame signal.
4 line array CCD optical-integral-time self-adaptation control methods according to claim 3 is characterized in that: the relevant parameter of described line array CCD output signal be ccd output signal amplitude or with pairing optical-integral-time of this amplitude or ccd output signal binaryzation after the square-wave signal width that obtains.
5 line array CCD optical-integral-time self-adaptation control methods according to claim 4 is characterized in that: described ccd output signal binaryzation is that ccd output signal [101,102,103] and threshold level [104] are compared; The calculating of the relevant parameter of described line array CCD output signal is finished by processor, and this processor is microcomputer, single-chip microcomputer, DSP or CPLD device.
6 line array CCD optical-integral-time self-adaptation control methods according to claim 4, it is characterized in that: the relevant parameter of described extraction line array CCD output signal is to utilize when threshold level 104 1 timings, under different optical-integral-times, square wave the width that correspondence is different of ccd output signal through being obtained after the binary conversion treatment, the time of integration is long, and then width is wide, lack the then narrow characteristic of width the time of integration, according to known square width value and corresponding optical-integral-time thereof, estimate that the square width value of sening as an envoy to reaches the pairing optical-integral-time of desired extent.
7 line array CCD optical-integral-time self-adaptation control methods according to claim 6, it is characterized in that: described relevant parameter and pre-set threshold with the line array CCD output signal extracted compares: the relevant parameter of line array CCD output signal is the width of square wave, with the width of this square wave and predefined width threshold value relatively:
1] when square width during less than threshold value lower limit 108 (as square wave 105), gives fixed step size, increase optical-integral-time by given step-length;
2] when the square width of output signal correspondence during greater than upper limit width 109 (as square wave 107), then by reducing optical-integral-time to fixed step size;
3] up to when the square width of output signal correspondence is between upper and lower limit width 109,108 (as square wave 106), optical-integral-time is constant.
8 line array CCD optical-integral-time self-adaptation control methods according to claim 7 is characterized in that: the width of described square wave is to be extracted from data latches 402 by single-chip microcomputer 403; Described square width is during less than threshold value lower limit 108 (as square wave 105), increase optical-integral-time by given step-length, be after by single-chip microcomputer 403 this width value and the thresholding width lower limit that sets in advance being compared, by computation of table lookup, increase the time of integration and send data latches 402 storages by certain step-length; Described square width is during greater than upper threshold 109 (as square wave 105), reduce optical-integral-time by given step-length, be after by single-chip microcomputer 403 this width value and the thresholding width upper limit that sets in advance being compared, by computation of table lookup, reduce optical-integral-time and send data latches 402 storages by certain step-length; The square width of described output signal correspondence is between upper and lower limit width 109,108 time (as square wave 106), optical-integral-time is constant, be by single-chip microcomputer 403 this width value and the thresholding width upper limit that sets in advance to be compared the back to determine, and through data latches 402 outputs.
9 line array CCD optical-integral-time self-adaptation control methods according to claim 6 is characterized in that: described relevant parameter and pre-set threshold with the line array CCD output signal extracted compares and comprises
1], makes CCD drive timing sequencer 704 and produce the required driving pulse sequence of line array CCD chip 201 operate as normal, the beginning operate as normal to system intialization initial light time of integration;
2] optical-integral-time computing unit 702 sequential read learnt from else's experience that Signal Pretreatment and A/D converting unit 701 are anticipated and digitlization after signal 705;
3] digital signal that order reads in 702 pairs of steps 902 of optical-integral-time computing unit is judged.In case the output signal amplitude of finding a certain pixel greater than the pre-set threshold upper limit, then stops step 903 and carry out step 904.If the output signal amplitude of CCD one frame all is lower than the threshold value lower limit, the maximum amplitude that then latchs this frame output signal enters step 905;
4] system's optical-integral-time is set to minimum, makes CCD drive timing sequencer 704 generations and has the CCD driving pulse sequence of new optical-integral-time, and line array CCD chip 201 is exported new signal under the effect of this driving pulse sequence;
5] amplitude peak value and the pre-set threshold lower limit that latchs in 702 pairs of steps 903 of the computing unit time of integration compares, when above-mentioned maximum amplitude greater than threshold value under in limited time, then show suitable needn't the adjusting time of integration, enter step 907, otherwise, enter step 906;
6] carrying out optical-integral-time calculates;
7] constant to optical-integral-time, keep optical-integral-time;
8] new optical-integral-time is transmitted back to CCD and drives timing sequencer 704, generation has the line array CCD driving pulse sequence of new optical-integral-time, drives new light integration period of line array CCD chip 201 beginnings.
10 1 kinds of devices of realizing above-mentioned line array CCD optical-integral-time self-adaptation control method is characterized in that: it comprises that CCD drives timing sequencer 204, and the output of described CCD driving timing sequencer 204 connects the input of line array CCD chip 20 1; The input of the output termination ccd output signal pretreatment unit 202 of described line array CCD chip 201; The input of the output termination optical-integral-time computing unit 203 of described ccd output signal pretreatment unit 202; The output termination CCD of described optical-integral-time computing unit 203 drives the input of timing sequencer 204.
11 line array CCD optical-integral-time adaptive controllers according to claim 10 is characterized in that: described ccd output signal pretreatment unit comprises [202 internal structure block diagram]
Sampling holder 301, low pass filter 302, operational amplifier 303, comparator 304, threshold level regulon 305.
12 according to claim 9 or 10 described line array CCD optical-integral-time adaptive controllers, and it is characterized in that: described optical-integral-time computing unit comprises [203 internal structures]
13 line array CCD optical-integral-time adaptive controllers according to claim 11, it is characterized in that: described A/D converting unit comprises
Described ccd output signal pretreatment unit 202 is ccd signal preliminary treatment and A/D converting unit 701;
Described optical-integral-time computing unit 203 is an optical-integral-time computing module 702;
Described CCD drives timing sequencer 204 and drives timing sequencer 704 for CCD;
Signal Pretreatment and A/D converting unit control-signals generator 703: under the effect of the control signal 707 that is produced, signal 806 is carried out processing such as correlated-double-sampling, A/D conversion.803 pairs of input signals of correlated-double-sampling module 806 carry out correlated-double-sampling and handle the signal 807 that the acquisition noise is further suppressed; Signal 807 is transformed to digital signal 705 outputs through A/D modular converter 804.The single chip integrated CCD front end signal preprocessed chip TLC8188 that adopts TI company to produce in the present embodiment finishes correlated-double-sampling and A/D conversion process.
The present invention has the following advantages:
The present invention has provided a kind of brand-new optical-integral-time Automatic adjustment method.This method can make the line array CCD optical-integral-time be regulated automatically with environment and target change of luminous intensity, thereby makes the line array CCD measuring system under the condition that the luminous intensity of target or background can't effectively be controlled its output signal be optimized in measuring dynamically, in real time.
This relation of 1 utilization of the present invention " the line array CCD optical-integral-time is directly proportional within the specific limits with line array CCD output signal amplitude ", optical-integral-time by the control line array CCD comes the line array CCD output signal is optimized, thereby has overcome the defective that prior art can not effectively be worked under target and the uncontrollable condition of background luminance;
2 the present invention are according to the variation of target and background luminance, by certain algorithm real-time calculate suitable optical-integral-time, and utilize new optical-integral-time that system is controlled, thereby can make system's variation of fast adaptation environment and target automatically, overcome prior art and can't adapt to fast Testing requirement in real time;
3 the present invention all regulate at equal pace to the pairing output signal amplitude of each pixel, thereby the picture signal that promptly guarantees output has higher signal to noise ratio to guarantee that again image is undistorted, have overcome the defective that prior art may cause image fault;
4 the present invention can carry out regulating on a large scale automatically to optical-integral-time according to measurement requirement, thereby make system adapt to target and background luminance changes on a large scale, have overcome the little shortcoming of prior art optical-integral-time adjustable range.
In sum, the present invention can make the line array CCD measuring system in measuring dynamically, in real time, when target and background luminance wide variation and can't effectively be controlled, allow Measuring Time more simultaneously at random, still can guarantee to carry out at a high speed, accurately measure.
Description of drawings
Fig. 1 is the optical-integral-time Principles of Regulation figure in the embodiment of the invention one;
Fig. 2 is that the system of first embodiment of the invention forms block diagram;
Fig. 3 is ccd output signal pretreatment unit 202 internal structure block diagrams in the first embodiment of the invention;
Fig. 4 is optical-integral-time computing unit 203 internal structure block diagrams in the first embodiment of the invention;
Fig. 5 is the required driving pulse sequence chart of line array CCD chip 201 operate as normal;
Fig. 6 regulates flow chart automatically for the optical-integral-time in the first embodiment of the invention;
Fig. 7 is that the system of second embodiment of the invention forms block diagram;
Fig. 8 is ccd output signal preliminary treatment and an A/D converting unit internal structure block diagram in the embodiment of the invention two;
Fig. 9 is the optical-integral-time automatic control flow chart figure in the second embodiment of the invention;
Figure 10 (a) be line array CCD without optical-integral-time regulate, the image of output during overexposure;
Figure 10 (b) be line array CCD without optical-integral-time regulate, output image when under-exposed;
Figure 10 (c) is the output image of line array CCD after regulating through optical-integral-time.
Embodiment
The present invention utilizes intensity of illumination one regularly, the amplitude of line array CCD output signal and optical-integral-time this relation that is directly proportional within the specific limits, according to the amplitude of ccd output signal or parameter and the pairing optical-integral-time thereof directly related with amplitude, as to width of the square-wave signal that obtains after the ccd output signal binaryzation etc., estimate the desired pairing optical-integral-time of line array CCD output signal parameter value.The new optical-integral-time control line array CCD that utilization estimates drives timing sequencer and produces the required integrated pulse sequence of line array CCD operate as normal, shifts pulse train, reset pulse sequence.Line array CCD is the signal of output optical-integral-time through overregulating under above-mentioned driving pulse sequence control, and the signal of newly exporting is carried out extracting the above-mentioned parameter value once more by certain algorithm after the preliminary treatment.Parameter value and the pre-set threshold extracted are compared, when exceeding threshold range, then need optical-integral-time is carried out above-mentioned adjusting once more, fall in the threshold range up to the above-mentioned parameter value.Can realize regulating optical-integral-time automatically by said method according to the variation of target or background luminance.The calculating of optical-integral-time is finished by processor, and this processor device can be microcomputer, single-chip microcomputer, DSP, also can be by the CPLD device programming is obtained.
Fig. 1 is the optical-integral-time auto-adaptive control theory figure of the embodiment of the invention one.When one timing of target intensity of illumination, line array CCD output signal amplitude is directly proportional with optical-integral-time within the specific limits.System is with the theoretical foundation of this characteristic as the adaptive control of line array CCD optical-integral-time.Output signal 101,102, the 103 pairing optical-integral-times of line array CCD reduce successively.By relatively line array CCD output signal 101,102,103 being carried out binary conversion treatment with threshold level 104, its corresponding waveform is respectively 107,106,105 after binary conversion treatment.When threshold level 104 1 timings, under different optical-integral-times, square wave the width that correspondence is different of ccd output signal through being obtained after the binary conversion treatment, the time of integration is long, and then width is wide, and vice versa.Utilize the relation between its corresponding square width after above-mentioned optical-integral-time, line array CCD output signal amplitude and the binaryzation, can estimate according to known square width value and corresponding optical-integral-time thereof and will make the square width value reach the pairing optical-integral-time of desired extent, thereby realize adaptive control optical-integral-time.The specific implementation method is: line array CCD is started working under the effect with the driving pulse sequence that presets optical-integral-time during system start-up, and the output signal of line array CCD is carried out binary conversion treatment, obtains to have the square-wave signal of certain width.With the width of this square wave and predefined width threshold value relatively, when square width during less than threshold value lower limit 108 (as square wave 105), then increase optical-integral-time by certain step-length; When the square width of output signal correspondence during greater than upper limit width 109 (as square wave 107), then reduce optical-integral-time by certain step-length; When the square width of output signal correspondence is between upper and lower limit width 109,108 (as square wave 106), optical-integral-time is constant.New optical-integral-time is sent into line array CCD drive timing sequencer, line array CCD is exported new signal under the effect of the driving pulse sequence with new optical-integral-time, new output signal is done above-mentioned processing again up to square width is controlled in the threshold range, thereby make the line array CCD optical-integral-time be able to adaptive control.
Fig. 2 is that the system of the embodiment of the invention one forms block diagram.Line array CCD chip 201 is converted to the signal of telecommunication 205 outputs with picture signal under the effect of the driving pulse sequence signal 208 that CCD driving timing sequencer 204 is produced, see Fig. 5; Signal 205 enters ccd output signal pretreatment unit 202, obtains signal to noise ratio and satisfy the square-wave signal 206 that optical-integral-time computing unit 203 requires after over-sampling maintenance, noise reduction, amplification, binary conversion treatment; The width of 203 pairs of inputs of optical-integral-time computing unit square-wave signal 206 is judged, if square width exceeds the pre-set threshold scope, then optical-integral-time computing unit 203 utilizes the algorithm of tabling look-up according to certain step-size change optical-integral-time and with signal 207 outputs; CCD drives timing sequencer 204 and produces each required drive signal 208 driven CCD chip 201 of CCD chip 201 operate as normal work under the control of optical-integral-time signal 207, meets design requirement until the output signal of CCD chip 201.
Fig. 3 is ccd output signal pretreatment unit 202 internal structure block diagrams.The output signal 205 of line array CCD chip 201 enters the analog signal pretreatment unit that is made of sampling holder 301, low pass filter 302, operational amplifier 303 successively, after over-sampling maintenance, noise reduction, processing and amplifying, obtain the analog signal 307 that signal to noise ratio is improved, signal 307 is sent into comparator 304, the comparative level 309 that is provided with passing threshold level adjustment unit 305 compares, and the analog signal of line array CCD output is carried out as shown in Figure 1 binary conversion treatment.Through after the binary conversion treatment, the analog signal 205 of CCD output is transformed into the square-wave signal 206 with certain width value and goes forward side by side into optical-integral-time computing unit 203 from this unit output.
Fig. 4 is the internal structure of optical-integral-time computing unit 203.The output signal 206 of ccd output signal pretreatment unit 202 enters counting unit 401, this unit is counted the square-wave signal 206 of input under the control of the control signal 408 that single-chip microcomputer 403 sends, enabling counting device when the rising edge of square-wave signal arrives, when arriving, the trailing edge of square-wave signal stops counting, the count value of this moment square width value of ascending the throne.After counting finished, single-chip microcomputer 403 latched the square width value signal 405 of counting unit 401 outputs via signal 407 control data latchs 402; Simultaneously single-chip microcomputer extracts the square-wave signal width value that latchs in the data latches 402 through signal 407, and the optical-integral-time that makes new advances by computation of table lookup.New optical-integral-time enters CCD via signal 207 and drives timing sequencer 204, produces the required drive signal 208 of line array CCD chip 201 operate as normal under its control, as shown in Figure 5.
Fig. 5 is the waveform of each required driving pulse of line array CCD chip 201 operate as normal and mutual relation.Wherein Φ SH is a light integrated pulse sequence 501, in order to the length of control optical-integral-time; Φ 1 is for shifting pulse train 502, in order to integral charge serial from shift register is shifted out; Φ RS is a reset pulse sequence 503, resets in order to each photosensitive unit to line array CCD chip 201.In conjunction with the phase relation between Φ SH, Φ 1, Φ RS, the generation of controlling Φ 1 by Φ SH can realize the CCD driving pulse sequence that optical-integral-time is controlled.
The concrete grammar that the controlled line array CCD driving pulse sequence of optical-integral-time realizes is: under the control of the optical-integral-time 207 that optical-integral-time computing unit 203 provides, CCD sequential logic generator 204 produces light integrated pulse sequence 501, shifts the generation of pulse train 502 with 501 controls of time integrated pulse sequence.When light integrated pulse sequence 501 was high level, transfer pulse train 502 quit work and remains on high level; When the trailing edge of light integrated pulse sequence 501 arrives, shift pulse train 502 and start working by given phase relation and frequency, when arriving, light integrated pulse sequence 501 rising edges quit work.Frequency and phase place work that reset pulse sequence 503 is fixed with relative transfer pulse train 502 all the time are not subjected to the influence of light integrated pulse sequence 501.Can realize the line array CCD driving pulse sequence that the time of integration is controlled by said method.
Fig. 6 regulates flow chart automatically for the optical-integral-time in the embodiment of the invention one.
Step 601: single-chip microcomputer 403 extracts the square width value that data latches 402 latchs;
Step 602: single-chip microcomputer 403 compares this width value and the thresholding width upper limit that sets in advance.When width greater than upper threshold execution in step 603 then, otherwise execution in step 604;
Step 603: single-chip microcomputer 403 reduces the time of integration by computation of table lookup by certain step-length;
Step 604: single-chip microcomputer 403 compares this width value and the thresholding width lower limit that sets in advance.When width less than upper threshold execution in step 605 then; Otherwise execution in step 606;
Step 605: single-chip microcomputer 403 increases the time of integration and send data latches 402 storages by certain step-length by computation of table lookup;
Step 606: keep original time of integration constant;
Step 607: the new optical-integral-time 207 to CCD of single-chip microcomputer 403 control data latchs 402 outputs drives in the sequential logic generator 204.
Under new optical-integral-time control, CCD drives timing sequencer 204 and produces new CCD driving pulse sequence driving line array CCD chip 201 work.Ccd output signal under the new driving pulse sequence control is carried out aforesaid every processing once more, and the square-wave signal width after binaryzation falls in the given threshold range.
At embodiments of the invention two are the optical-integral-time adaptive control systems that are based upon on the optical-integral-time fundamentals of forecasting.As shown in Figure 7, optical-integral-time computing unit 702 in the system, CCD drive timing sequencer 708, Signal Pretreatment and A/D converting unit control-signals generator and all realize in a slice CPLD device (CPLD), make that system configuration is more compact, reliability is higher.System in the present embodiment has the high-speed parallel data-handling capacity, the system that takies is soft, hardware resource is few, and system can satisfy dynamically, real-time Testing requirement thereby make.
The optical-integral-time auto-adaptive control theory that adopts among the embodiment two is as follows:
According to CCD light integral charge formula
Q
IP＝ηqΔ
neoAT
C (1)
In the formula: η is the quantum efficiency of material; Q is an electronic charge; Δ
NeoPhoton stream speed for incident light; A is the light-receiving area of photosensitive unit; T
CBe optical-integral-time.By (1) formula as can be seen, after CCD determined, for each pixel, η, q and A were constant, under the constant prerequisite of illumination condition, and Δ
NeoAlso be constant, so Q
IPWith T
CLinear; Again because Q
IPWith the output amplitude of the corresponding pixel of CCD is linear relationship, so T
CWith output amplitude also be linear dependence, that is:
U∝T
C (2)
In the formula: U is the ccd output signal amplitude.So under identical illumination condition, following formula is set up:
In the formula: T
C1, T
C2Be optical-integral-time, U
1, U
2Be respectively T
C1, T
C2Pairing signal output amplitude.
The precondition of being set up by (3) formula and formula can draw to draw a conclusion: in the range of linearity of CCD, under the constant prerequisite of illumination condition, if the optical-integral-time T of known present frame
C1And corresponding output signal amplitude U
1, can obtain the output signal amplitude U that will obtain to expect according to following formula
2The optical-integral-time T that should provide
C2:
When the CCD high speed operation, usually the operating frequency of the relative CCD of rate of change of incident intensity can be considered and changes more continuously, thereby can be similar to think that incident intensity does not change in the time range of the CCD of high speed operation one or two frame, thereby can be similar to the photon stream speed Δ of thinking at this time period incident light
NeoBe constant.Thereby change under the relatively slow condition (4) formula at CCD high speed operation, incident intensity and set up, can be used as the theoretical foundation of the automatic adjustment algorithm of optical-integral-time.
Fig. 7 is that the system of the embodiment of the invention two forms block diagram.In the present embodiment, line array CCD chip 201 output image signal 205 under the effect of the CCD driving pulse sequence signal 208 that CCD driving timing sequencer 704 is produced.Picture signal 205 enters ccd signal preliminary treatment and A/D converting unit 701 (the internal structure block diagram as shown in Figure 8).The signal 806 that picture signal 205 at first is improved through the processing output signal-to-noise ratio of low pass filter 801, operational amplifier 802 in ccd output signal preliminary treatment and A/D converting unit 701 inside.Under the effect of the control signal 707 that Signal Pretreatment and A/D converting unit control-signals generator 704 are produced, signal 806 is carried out processing such as correlated-double-sampling, A/D conversion subsequently.803 pairs of input signals of correlated-double-sampling module 806 carry out correlated-double-sampling and handle the signal 807 that the acquisition noise is further suppressed; Signal 807 is transformed to digital signal 705 outputs through A/D modular converter 804.The single chip integrated CCD front end signal preprocessed chip TLC8188 that adopts TI company to produce in the present embodiment finishes correlated-double-sampling and A/D conversion process.
The digital signal 705 of Signal Pretreatment and 701 outputs of A/D converting unit enters optical-integral-time computing module 702, combination drives the original optical-integral-time that extracts the timing sequencer 704 via signal 706 from CCD in this module, finish optical-integral-time automatic control flow chart shown in Figure 9, calculate the optical-integral-time that makes new advances.Calculate the long-pending time of the new light that obtains and send into CCD driving timing sequencer 704 via signal 706, produce the required driving pulse sequence 208 of line array CCD chip 201 operate as normal, and the required coherent signal 708 of Signal Pretreatment unit controls signal generator 703.Under the effect of signal 708, Signal Pretreatment unit controls signal generator 703 produces the required control signal 707 of Signal Pretreatment and A/D converting unit 701.Line array CCD chip 201 begins a new exposure cycle under the effect of new driving pulse sequence 208.
The method that the controlled CCD driving pulse sequence of optical-integral-time realizes in the present embodiment is: required each the road signal of CCD all by under optical-integral-time control to input clock count, means such as frequency division produce.System adopts a basic counter, after the value of counter arrives the optical-integral-time designated value, one frame end, system resets each road signal, and receive the new time of integration, begin the generation of a new frame signal, thereby realize the Based Intelligent Control of the optical-integral-time of CCD drive signal, the CCD driving pulse sequence that is produced as shown in Figure 5.Detailed method is seen the 5th, 479, No. 207 United States Patent (USP)s authorizing people such as Degi.
Fig. 9 is the embodiment of the invention two optical-integral-time automatic control flow chart figure.
Step 901: to system intialization initial light time of integration, make CCD drive timing sequencer 704 and produce the required driving pulse sequence of line array CCD chip 201 operate as normal, make it begin operate as normal;
Step 902: optical-integral-time computing unit 702 sequential read learnt from else's experience that Signal Pretreatment and A/D converting unit 701 are anticipated and digitlization after signal 705;
Step 903: the digital signal that order reads in 702 pairs of steps 902 of optical-integral-time computing unit is judged.In case the output signal amplitude of finding a certain pixel greater than the pre-set threshold upper limit, then stops step 903 and carry out step 904.If the output signal amplitude of CCD one frame all is lower than the threshold value lower limit, the maximum amplitude that then latchs this frame output signal enters step 905;
Step 904: system's optical-integral-time is set to minimum, makes CCD drive timing sequencer 704 generations and has the CCD driving pulse sequence of new optical-integral-time, and line array CCD chip 201 is exported new signal under the effect of this driving pulse sequence;
Step 905: the amplitude peak value and the pre-set threshold lower limit that latch in 702 pairs of steps 903 of the computing unit time of integration compare, when above-mentioned maximum amplitude greater than threshold value under in limited time, then show suitable needn't the adjusting time of integration, enter step 907, otherwise show that the output signal amplitude is too small, signal to noise ratio is little, so enter step 906;
Step 906: the represented optical-integral-time of perfect (4) is as new optical-integral-time;
Step 907: optical-integral-time is constant, keeps original optical-integral-time.
At last new optical-integral-time is transmitted back to CCD and drives timing sequencer 704, generation has the line array CCD driving pulse sequence of new optical-integral-time, drives new light integration period of line array CCD chip 201 beginnings.
According to this flow process, in the adjustable range of system, at most only need the time of two frames, output signal can be adjusted within the comparatively desirable scope.Thereby overcome in the conventional control method, owing to the prediction that lacks optical-integral-time, and the repeatedly adjusting repeatedly that may occur that causes, the shortcoming that the response speed of system is slow.Can significantly shorten system to the response time that intensity of illumination changes by this flow process, strengthen the adaptive capacity of system environment.This flow process is by to the CPLD programming simultaneously, has hardware to realize that the system data processing speed is apparently higher than microprocessors such as single-chip microcomputers fully.
Handling forward and backward ccd output signal waveform through this embodiment 1, embodiment 2 described optical-integral-time adaptive control systems can be by the oscilloscope Direct observation, concrete waveform as shown in figure 10: wherein Figure 10 (a) is the image of line array CCD output during overexposure when regulating without optical-integral-time; Figure 10 (b) is line array CCD output image when under-exposed when regulating without optical-integral-time; Figure 10 (c) is the output image after the situation shown in Figure 10 (a), Figure 10 (b) is regulated through the line array CCD optical-integral-time.
Claims (10)
1 one kinds of line array CCD optical-integral-time self-adaptation control methods, it is characterized in that: this method comprises
1), estimates the pairing optical-integral-time of line array CCD according to the relevant parameter of line array CCD output signal;
2) utilize the optical-integral-time that estimates, the control line array CCD drives timing sequencer, produces the required driving pulse sequence of line array CCD operate as normal, and described driving pulse sequence comprises the integrated pulse sequence, shifts pulse train and reset pulse sequence;
3) line array CCD output optical-integral-time signal through overregulating under the driving pulse sequence drives after preliminary treatment, extracts the relevant parameter of line array CCD output signal with this signal once more by calculating;
4) relevant parameter and the pre-set threshold with the line array CCD output signal extracted compares, when exceeding threshold range, through 1), 2), 3) optical-integral-time is regulated once more, fall into the pre-set threshold scope up to parameter value;
5) the automatic adjusting of optical-integral-time is finished.
2 line array CCD optical-integral-time self-adaptation control methods according to claim 1 is characterized in that: the estimation of described optical-integral-time is to realize by A/D converting unit and a slice CPLD device; It is by realizing in a slice CPLD device that described control line array CCD drives timing sequencer.
3 line array CCD optical-integral-time self-adaptation control methods according to claim 1 and 2 is characterized in that: the required driving pulse sequence of described generation line array CCD operate as normal by required each the road signal of CCD all by under optical-integral-time control to input clock count, frequency division produces; Described counting, frequency division adopt a basic counter, and after the value of counter arrived the optical-integral-time designated value, a frame end resetted each road signal, and receives the new time of integration, begins the generation of a new frame signal.
4 line array CCD optical-integral-time self-adaptation control methods according to claim 3 is characterized in that: the relevant parameter of described line array CCD output signal be ccd output signal amplitude or with pairing optical-integral-time of this amplitude or ccd output signal binaryzation after the square-wave signal width that obtains.
5 line array CCD optical-integral-time self-adaptation control methods according to claim 4 is characterized in that: described ccd output signal binaryzation is that ccd output signal and threshold level are compared; The calculating of the relevant parameter of described line array CCD output signal is finished by processor, and this processor is microcomputer, single-chip microcomputer, DSP or CPLD device.
6 line array CCD optical-integral-time self-adaptation control methods according to claim 4, it is characterized in that: the relevant parameter of described extraction line array CCD output signal is to utilize when threshold level one timing, under different optical-integral-times, square wave the width that correspondence is different of ccd output signal through being obtained after the binary conversion treatment, the time of integration is long, and then width is wide, lack the then narrow characteristic of width the time of integration, according to known square width value and corresponding optical-integral-time thereof, estimate that the square width value of sening as an envoy to reaches the pairing optical-integral-time of desired extent.
7 line array CCD optical-integral-time self-adaptation control methods according to claim 4, it is characterized in that: described relevant parameter and pre-set threshold when comparing with the line array CCD output signal extracted, the relevant parameter of described line array CCD output signal adopts the width of square wave, is width and the comparison of predefined width threshold value with this square wave:
1) when square width less than threshold value under in limited time, give fixed step size, increase optical-integral-time by given step-length;
2) when the square width of output signal correspondence during greater than upper limit width, then by reducing optical-integral-time to fixed step size;
3) up to when the square width of output signal correspondence is between the upper and lower limit width, optical-integral-time is constant.
8 line array CCD optical-integral-time self-adaptation control methods according to claim 7, it is characterized in that: the width of described square wave is to be extracted from data latches by single-chip microcomputer; Described square width is less than prescribing a time limit under the threshold value, increase optical-integral-time by given step-length, be after by single-chip microcomputer this width value and the thresholding width lower limit that sets in advance being compared,, to increase the time of integration and send data latch stores by certain step-length by computation of table lookup; Described square width is during greater than upper threshold, reduce optical-integral-time by given step-length, be after by single-chip microcomputer this width value and the thresholding width upper limit that sets in advance being compared,, to reduce optical-integral-time and send data latch stores by certain step-length by computation of table lookup; The square width of described output signal correspondence is between the upper and lower limit width time, and optical-integral-time is constant, is by single-chip microcomputer this width value and the thresholding width upper limit that sets in advance to be compared the back to determine, and exports through data latches.
9 line array CCD optical-integral-time self-adaptation control methods according to claim 6 is characterized in that: described relevant parameter and pre-set threshold with the line array CCD output signal extracted compares and comprises
1), makes CCD drive timing sequencer 704 and produce the required driving pulse sequence of 201 operate as normal of line array CCD core, the beginning operate as normal to system intialization initial light time of integration;
2) optical-integral-time computing unit 702 sequential read learnt from else's experience that Signal Pretreatment and A/D converting unit 701 are anticipated and digitlization after signal 705;
3) digital signal that order reads in 702 pairs of steps 902 of optical-integral-time computing unit is judged; When the output signal amplitude of a certain pixel greater than the pre-set threshold upper limit, then stop step 903, carry out step 904; If the output signal amplitude of CCD one frame all is lower than the threshold value lower limit, the maximum amplitude that then latchs this frame output signal enters step 905;
4) system's optical-integral-time is set to minimum, makes CCD drive timing sequencer 704 generations and has the CCD driving pulse sequence of new optical-integral-time, and line array CCD chip 201 is exported new signal under the effect of this driving pulse sequence;
5) amplitude peak value and the pre-set threshold lower limit that latchs in 702 pairs of steps 903 of the computing unit time of integration compares, when above-mentioned maximum amplitude greater than threshold value under in limited time, then show suitable needn't the adjusting time of integration, enter step 907, otherwise, enter step 906;
6) carrying out optical-integral-time calculates;
7) constant to optical-integral-time, keep optical-integral-time;
8) new optical-integral-time is transmitted back to CCD and drives timing sequencer 704, generation has the line array CCD driving pulse sequence of new optical-integral-time, drives new light integration period of line array CCD chip 201 beginnings.
10 1 kinds of devices of realizing above-mentioned line array CCD optical-integral-time self-adaptation control method is characterized in that: it comprises that CCD drives timing sequencer 204, and the output of described CCD driving timing sequencer 204 connects the input of line array CCD chip 201; The input of the output termination ccd output signal pretreatment unit 202 of described line array CCD chip 201; The input of the output termination optical-integral-time computing unit 203 of described ccd output signal pretreatment unit 202; The output termination CCD of described optical-integral-time computing unit 203 drives the input of timing sequencer 204.
Described ccd output signal pretreatment unit comprises sampling holder 301; Described ccd output signal pretreatment unit comprises [202 internal structure block diagram]; Sampling holder 301, low pass filter 302, operational amplifier 303, comparator 304, threshold level regulon 305;
Described optical-integral-time computing unit [203 internal structure :] comprises counting unit, and described counting unit 401 and data latches all are connected to the I/O end of single-chip microcomputer 403; The terminal count output of described counting unit 401 connects the data input pin of data latches 402.
Described A/D converting unit comprises the ccd output signal pretreatment unit, and described ccd output signal pretreatment unit 202 is ccd signal preliminary treatment and A/D converting unit 701; Described optical-integral-time computing unit 203 is an optical-integral-time computing module 702; Described CCD drives timing sequencer 204 and drives timing sequencer 704 for CCD.
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