CN102123254A - Time sequence control method for decreasing multiphase TDI CCD (Trandport Driver Interface Charge Coupled Device) image motion - Google Patents

Abstract

The invention relates to a time sequence control method for decreasing multiphase TDI CCD (Trandport Driver Interface Charge Coupled Device) image motion, relating to a time sequence control method of a time-delay integral charge-coupled device and solving the problems that image motion is generated due to the discreteness of charge transfer motion and imaging quality is decreased in the application process of the traditional multiphase TDI CCD. The time sequence control method comprises the steps: in a line transfer period, driving a photosensitive image element array and a dark image element array by adopting charge transfer signals CI1, CI2, CI3 and CI4 in the same line, dividing a charge transfer process of one cycle into 2n time slots at equal intervals, and driving the last line of the dark image element array by adopting single time sequence signals LCI1, LCI2, LCI3 and LCI4; and transferring charges of the last line of the dark image element array into a horizontal shift register through a transmission gate in a line transfer cycle, and reading the charges in the horizontal shift register by a charge reading circuit. The invention improves the imaging quality of a camera.

Description

Reduce the sequential control method of leggy TDI CCD image drift

Technical field

The present invention relates to a kind of sequential control method of time delay integration charge coupled device, be specifically related to a kind of remotely sensed image system that is applicable to, can reduce the sequential control method of leggy time delay integration charge coupled device image drift.

Background technology

Time delay integration charge coupled device (Time Delay Integration Charge Coupled Device, the multirow light-sensitive element is to same scenery multiexposure, multiple exposure when TDI CCD) photographing, under the situation of low-light (level), also can obtain the image of high s/n ratio, solved the problem of little relative aperture, long-focus camera exposure deficiency, therefore obtained using widely in Aeronautics and Astronautics remotely sensed image field.Leggy TDI CCD electric charge transfer movement disperses in the real work, and translational speed is uneven, and the motion of scenery picture point is continuous, has also produced image drift thus, has reduced the image quality of remotely sensed image system.

Fig. 1 is the structural representation of known four phase place TDI CCD, mainly comprises photosensitive pixel array 1, dark pixel array 2, transmission lock 3, horizontal shifting register 4 and electric charge reading circuit 5.

Photosensitive pixel array 1 is identical with dark pixel array 2 electric charge branch modes, and Fig. 2 is that the electric charge of four phase place TDI CCD vertical direction shifts schematic diagram, and described vertical direction comprises photosensitive pixel array 1 and dark pixel array 2; First pixel position is the capable j row of i, and second pixel position is the capable j row of i+1.Four each pixel of phase place TDI CCD are by four phase signal CI1, CI2, CI3, CI4 control, and Fig. 3 is the sequential operation figure of Fig. 2 correspondence.At T1 in the cycle, CI1 is a low level, CI2, CI3, CI4 are high level, under CI2, CI3, CI4, form a depletion layer like this, electric charge remains under this surface, CI1 becomes the electromotive force barrier layer, and electric charge is maintained under CI2, CI3, the CI4, and electronics is moved to gesture well under phase place CI2, CI3, the CI4 along silicon face fully by the gesture well under phase place CI2, the CI3 when T8, T1 phse conversion; At T2 in the cycle, CI1, CI2 are low level, CI3, CI4 are high level, CI3, CI4 form a depletion layer down, electric charge remains under this surface, CI1, CI2 become the electromotive force barrier layer, and electric charge is maintained under CI3, the CI4, and electronics is moved to gesture well under phase place CI3, the CI4 along silicon face fully by the gesture well under phase place CI2, CI3, the CI4 when T1, T2 phse conversion; At T3 in the cycle, CI2 is a low level, CI3, CI4, CI1 are high level, form a depletion layer under CI3, CI4, the CI1 phase place, electric charge remains under this surface, CI2 becomes the electromotive force barrier layer, and electric charge is maintained under CI3, CI4, the CI1, and electronics is moved to gesture well under phase place CI3, CI4, the CI1 along silicon face fully by the gesture well under phase place CI3, the CI4 when T2, T3 phse conversion; At T4 in the cycle, CI2, CI3 are low level, CI4, CI1 are high level, form a depletion layer under CI4, the CI1 phase place, electric charge remains under this surface, CI2, CI3 become the electromotive force barrier layer, and electric charge is maintained under CI4, the CI1, and electronics is moved to gesture well under phase place CI4, the CI1 along silicon face fully by the gesture well under phase place CI3, CI4, the CI1 when T3, T4 phse conversion; At T5 in the cycle, CI3 is a low level, CI4, CI1, CI2 are high level, form a depletion layer under CI4, CI1, the CI2 phase place, electric charge remains under this surface, CI3 becomes the electromotive force barrier layer, and electric charge is maintained under CI4, CI1, the CI2, and electronics is moved to gesture well under phase place CI4, CI1, the CI2 along silicon face fully by the gesture well under phase place CI4, the CI1 when T4, T5 phse conversion; At T6 in the cycle, CI3, CI4 are low level, CI1, CI2 are high level, form a depletion layer under CI1, the CI2 phase place, electric charge remains under this surface, CI3, CI4 become the electromotive force barrier layer, and electric charge is maintained under CI1, the CI2, and electronics is moved to gesture well under phase place CI1, the CI2 along silicon face fully by the gesture well under phase place CI4, CI1, the CI2 when T5, T6 phse conversion; At T7 in the cycle, CI4 is a low level, CI1, CI2, CI3 are high level, form a depletion layer under CI1, CI2, the CI3 phase place, electric charge remains under this surface, CI4 becomes the electromotive force barrier layer, and electric charge is maintained under CI1, CI2, the CI3, and electronics is moved to gesture well under phase place CI1, CI2, the CI3 along silicon face fully by the gesture well under phase place CI1, the CI2 when T6, T7 phse conversion; At T8 in the cycle, CI4, CI1 are low level, CI2, CI3 are high level, form a depletion layer under CI2, the CI3 phase place, electric charge remains under this surface, CI4, CI1 become the electromotive force barrier layer, and electric charge is maintained under CI2, the CI3, and electronics is moved to gesture well under phase place CI2, the CI3 along silicon face fully by the gesture well under phase place CI1, CI2, the CI3 when T7, T8 phse conversion.A capable migration period comprises 8 phse conversion processes, i.e. T1, T2, T3, T4, T5, T6, T7, T8, and total time is t1.

According to above-mentioned charge transfer method, after the photosensitive pixel of first row is finished exposure, the electric charge of collecting is transferred in second row, after the photosensitive pixel of second row is finished exposure, transfer to the electric charge and the first capable electric charge that comes that shifts that one's own profession collects in the third line in the lump, by that analogy, up to finishing the capable exposure of N.Opto-electronic conversion does not take place in dark pixel array 2, therefore the electric charge that produces in photosensitive pixel array 1 exposure is transferred in the horizontal shifting register 4 through the capable dark pixel array 2 of M, transmission lock 3, horizontal shifting register 4 is read through J electric charge reading circuit 5 under the driving of CR1, CR2, CR3, CR4.

In the time period t 3 that horizontal shifting register 4 electric charges are read, TDI CCD in the ranks electric charge shifts and need stop, and obviously is longer than T2～T8 time cycle as the T1 time cycle among Fig. 3.The general shared time of T1 generally accounts for more than 80% of delegation's charge transfer time, this moment is at (T1, T2) image drift that produces in the migration period is 0.8b, at (T3, T4), (T5, T6), (T7, T8) three pairs of interior image drifts that produce of migration period are 0.067b, this causes total image drift amount of generation in the TDI CCD time for exposure excessive, thereby reduces the image quality of remote sensing camera.This image drift is by the inherent working method decision of TDI CCD, can not eliminate by structure, the working method of remote sensing camera.

Summary of the invention

The present invention for solve existing leggy TDI CCD in application process owing to the discreteness of electric charge transfer movement produces image drift, the problem of the image quality that has reduced simultaneously provides a kind of sequential control method that reduces leggy TDI CCD image drift.

Reduce the sequential control method of leggy TDI CCD image drift, this method is realized by following steps:

In step 1, the migration period of being expert at, photosensitive pixel array adopts the same CI1 of charge transfer signal in the ranks, CI2, CI3, CI4 to drive with dark pixel array, the charge transfer process of one-period is divided into 2n equally spaced time period, and described n is a TDI CCD number of phases;

The last row of step 2, described dark pixel array adopts independent clock signal LCI1, LCI2, LCI3, LCI4 to drive; The last of dark pixel array transferred to electric charge in the horizontal shifting register through the transmission lock in capable migration period time of being expert at;

Electric charge in step 3, the electric charge reading circuit reading horizontal shift register, realization reduces the sequencing control of leggy TDICCD image drift.

Operation principle of the present invention: TDI CCD of the present invention is by photosensitive pixel array, dark pixel array, the transmission lock, horizontal shifting register and electric charge reading circuit, in a capable migration period, photosensitive pixel array adopts the same CI1 of charge transfer signal in the ranks with dark pixel array (removing the last row), CI2, CI3, CI4 drives, the charge transfer process of one-period has been divided into 2n equally spaced time period, n is the TDICCD number of phases, and the electric charge that collects through the photosensitive pixel array of this kind sequential driving mode is transferred to the row second from the bottom of dark pixel array; The last row of described dark pixel array adopts independent clock signal LCI1, LCI2, LCI3, LCI4 to drive; The last row of dark pixel array is transferred to electric charge in the horizontal shifting register at 20% row migration period in time fully; The time that the translational shifting that can supply water register electric charge is read accounts for 80% of a capable migration period, at this moment between in, the electric charge that horizontal shifting register will be is wherein read via the electric charge reading circuit.So, control signal transmits the work period of sequential and replacement sequential, in the time for exposure, the image drift that the discrete transfer of continuous motion of scenery picture point and TDI CCD electric charge causes during exposure is b/n to the maximum, b is a pixel dimension, that this has reduced leggy TDI CCD because the discrete inhomogeneous image drift that causes of transfer movement speed of electric charge, and finally improve the image quality of remote sensing camera.

Beneficial effect of the present invention: the present invention is by the time sequential routine of control TDI CCD, the image drift that relative motion causes between scenery picture point and the photosensitive medium when having reduced leggy TDI CCD exposure, relative motion when also having reduced simultaneously exposure between scenery picture point and the photosensitive medium, scenery picture point of the method for the invention and the maximum image drift between the photosensitive medium reduce to b/n, b is a pixel dimension, improves the image quality of remote sensing camera.

Description of drawings

Fig. 1 is existing four phase place TDI CCD structural representations;

Fig. 2 shifts schematic diagram for existing four phase place TDI CCD electric charges;

Fig. 3 is existing four phase place TDI CCD sequential operation figure;

Fig. 4 is a TDI CCD structural representation of the present invention;

Fig. 5 is that TDI CCD electric charge of the present invention shifts schematic diagram;

Fig. 6 is TDI CCD sequential operation figure of the present invention.

Among the figure: 1, photosensitive pixel array, 2, dark pixel array, 3, the transmission valve, 4, horizontal shifting register, 5, the electric charge reading circuit.

Embodiment

Embodiment one, in conjunction with Fig. 4 present embodiment is described, reduces the sequential control method of leggy TDI CCD image drift, this method is realized by following steps:

In step 1, the migration period of being expert at, photosensitive pixel array 1 adopts the same CI1 of charge transfer signal in the ranks, CI2, CI3, CI4 to drive with dark pixel array 2, the charge transfer process of one-period is divided into 2n equally spaced time period, and described n is a TDI CCD number of phases;

The last row of step 2, described dark pixel array 2 adopts independent clock signal LCI1, LCI2, LCI3, LCI4 to drive; The last of dark pixel array 2 transferred to electric charge in the horizontal shifting register 4 through transmission lock 3 in capable migration period time of being expert at;

Electric charge in step 3, the electric charge reading circuit 5 reading horizontal shift registers 4, realization reduces the sequencing control of leggy TDI CCD image drift.

The time of described photosensitive pixel array 1 each phase transition of present embodiment is identical, and the image drift that produces in described each electric charge migration period is

B pixel dimension in the formula, described b is a positive integer.

Embodiment two, in conjunction with Fig. 4 to Fig. 6 present embodiment is described, present embodiment is the embodiment of the sequential control method of embodiment one described minimizing leggy TDI CCD image drift:

With four phase place TDI CCD is example: the last rank of dark pixel array are by independent sequential drive signal control among the present invention, be respectively LCI1, LCI2, LCI3, LCI4, in conjunction with Fig. 4, it is identical to rank the sequential operation order mutually for capable photosensitive pixel array 1 of the N among Fig. 4 and capable dark pixel array 2 sequential operations of M-1 and existing four, promptly comprise T1～T8 totally 8 state conversion process, difference is that the time that takies of each state is equal, that is:

$\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="HDA0000055597540000011.png,HDA0000055597540000041.png"\; state="\{\{state\}\}">T</figure-callout>}1=\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="HDA0000055597540000011.png,HDA0000055597540000041.png"\; state="\{\{state\}\}">T</figure-callout>}2=\mathrm{<figure-callout\; id="3"\; label="T"\; filenames="HDA0000055597540000011.png,HDA0000055597540000041.png"\; state="\{\{state\}\}">T</figure-callout>}3=\mathrm{<figure-callout\; id="4"\; label="T"\; filenames="HDA0000055597540000011.png,HDA0000055597540000041.png"\; state="\{\{state\}\}">T</figure-callout>}4=\mathrm{<figure-callout\; id="5"\; label="T"\; filenames="HDA0000055597540000041.png"\; state="\{\{state\}\}">T</figure-callout>}5=T6=T7=T8=\frac{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="HDA0000055597540000011.png,HDA0000055597540000041.png"\; state="\{\{state\}\}">t</figure-callout>}1}{8}$

Capable capable in conjunction with Fig. 5, sequential operation figure is in conjunction with Fig. 6 to horizontal shifting register 4 transfers to the capable conversion of M and M for M-1 in the dark pixel array 2, and wherein the T1 cycle is made up of T1_1, T1_2, T1_3, T1_4.In the whole cycle, phase place CI1 was a low level during the M-1 of dark pixel array 2 was capable at T1, and phase place CI2, CI3, CI4 are high level, and CI2, CI3, CI4 form a depletion layer down, and electric charge remains under this surface always; M for dark pixel array is capable, be divided into four sequential operations in cycle again at T1, be respectively T1_1, T1_2, T1_3, T1_4, in the T1_1 time period, LCI1, LCI2 is a low level, LCI3, LCI4, TCK is a high level, transmission valve 3 is open-minded, at T8, during the T1_1 phse conversion M-1 capable in electronics along silicon face by phase place CI2, gesture well under the CI3 is moved to phase place CI2 fully, CI3, gesture well under the CI4, during M is capable electronics along silicon face by phase place LCI2, LCI3, gesture well under the LCI4 is moved to phase place LCI3 fully, in the gesture well and horizontal shifting register 4 under the LCI4; In the T1_2 time period, LCI1, LCI2, LCI3 are low level, and LCI4, TCK are high level, and electronics is moved to by the gesture well under the phase LCI3 in the gesture well and horizontal shifting register 4 under the phase place LCI4 fully along silicon face when T1_1, T1_2 phse conversion; In the T1_3 time period, LCI1, LCI2, LCI3, LCI4 are low level, TCK is a high level, electronics is moved in the phase place horizontal shifting register 4 by the gesture well under the phase place LCI4 fully along silicon face when T1_2, T1_3 phse conversion, in the T1_4 time period, LCI1, LCI2, LCI3, LCI4, TCK are low level, and the defeated valve of biographies cuts out, and the electric charge of the capable gesture well of M stored is transferred to horizontal shifting register fully.

At T2 in the cycle, CI1, CI2, TCK are low level, CI3, CI4, LCI1, LCI2, LCI3, LCI4 are high level, and electronics is moved to gesture well under gesture well under M-1 line phase CI3, the CI4 and the capable LCI1 of M, LCI2, LCI3, the LCI4 along silicon face by the gesture well under the M-1 line phase CI2 when T1_4, T2 phse conversion; In cycle, CI2, TCK are low level at T3, and CI1, CI3, CI4, LCI1, LCI2, LCI3, LCI4 are high level, and electronics is moved to gesture well under the M-1 line phase CI1 along silicon face by the gesture well under the M-2 line phase when T2, T3 phse conversion; At T4 in the cycle, CI2, CI3, TCK are low level, CI1, CI4, LCI1, LCI2, LCI3, LCI4 are high level, and electronics is moved to gesture well under gesture well under the M-1 line phase CI4 and the capable LCI1 of M, LCI2, LCI3, the LCI4 along silicon face by the gesture well under the M-1 line phase CI3 when T3, T4 phse conversion; In cycle, CI3, TCK are low level at T5, and CI1, CI2, CI4, LCI1, LCI2, LCI3, LCI4 are high level, and electronics is moved to gesture well under M-1 line phase CI1, the CI2 along silicon face by the gesture well under the M-2 line phase when T4, T5 phse conversion; At T6 in the cycle, CI3, CI4, TCK are low level, CI1, CI2, LCI1, LCI2, LCI3, LCI4 are high level, when T5, T6 phse conversion electronics along silicon face by the gesture well under the capable LCI1 of the gesture well under M-1 line phase CI4 migration M, LCI2, LCI3, the LCI4; At T7 in the cycle, CI4, TCK are low level, CI1, CI2, CI3, LCI1, LCI2, LCI3, LCI4 are high level, when T6, T7 phse conversion electronics along silicon face by M-1 the gesture well under capable CI1, the CI2 phase place move to gesture well under M-1 line phase CI1, CI2, the CI3; At T8 in the cycle, CI1, CI4, LCI1, TCK are low level, CI2, CI3, LCI2, LCI3, LCI4 are high level, when T7, T8 phse conversion electronics along silicon face by M-1 the gesture well under capable CI1, CI2, the CI3 phase place move to gesture well under M-1 line phase CI2, the CI3, simultaneously electronics is moved to gesture well under M line phase LCI2, LCI3, the LCI4 along silicon face by the gesture well under the capable LCI1 of M, LCI2, LCI3, the LCI4 phase place.

The time of described photosensitive pixel array 1 each phase transition of present embodiment is identical, and simultaneously, the image drift that produces in each electric charge migration period is

And adopt independent sequential drive signal at dark pixel array 2 the last row, reserved for 80% row migration period time, satisfy the demand that TDI CCD electric charge is read for horizontal shifting register.

Claims (2)

1. reduce the sequential control method of leggy TDI CCD image drift, it is characterized in that this method is realized by following steps:

In step 1, the migration period of being expert at, photosensitive pixel array (1) adopts the same CI1 of charge transfer signal in the ranks, CI2, CI3, CI4 to drive with dark pixel array (2), the charge transfer process of one-period is divided into 2n equally spaced time period, and described n is a TDI CCD number of phases;

The last row of step 2, described dark pixel array (2) adopts independent clock signal LCI1, LCI2, LCI3, LCI4 to drive; The last of dark pixel array (2) transferred to electric charge in the horizontal shifting register (4) through transmission lock (3) in capable migration period time of being expert at;

Electric charge in step 3, electric charge reading circuit (5) the reading horizontal shift register (4), realization reduce the sequencing control of leggy TDI CCD image drift.

2. the sequential control method of minimizing leggy TDI CCD according to claim 1 image drift is characterized in that the time of each phase transition of described photosensitive pixel array (1) is identical, and the image drift that produces in described each electric charge migration period is

B is a pixel dimension in the formula, and described b is a positive integer.

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