Vertical driving pulse crosstalk elimination method in continuous transfer mode

Abstract

The invention belongs to the technical field of photoelectrons, and relates to a method for eliminating vertical driving pulse crosstalk in a continuous transfer mode, which comprises the following steps of: 1, adjusting rising and falling edge time tr and tf of CI; 2, fixing the sequential relationship between the CR and the RST and the TCK and the SCK, and adjusting the sequential relationship between the rising and falling edges of the CI and the rising and falling edges of the CR and the RST; step 3, acquiring an image and detecting whether the image has vertical crosstalk stripes, and if so, executing step 4; otherwise, the tr and tf of the CI and the sequential relation between the rising and falling edges of the CI and the CR and the RST are solidified; 4, if the tr and tf of the CI and the time interval between the rising and falling edges of the CI and the CR and the RST reach the maximum time interval, returning to the step 1; otherwise, returning to the step 2; by adjusting tr and tf of the CI and the sequential relation between rising and falling edges of the CI and CR and RST, crosstalk of the CI to the read signal in the continuous transfer mode is eliminated.

Description

Technical Field

[0001] The invention belongs to the field of optoelectronic technology and relates to a method for eliminating vertical drive pulse crosstalk in a continuous transfer mode. Background Art

[0002] TDI CCD (Time Delayed and Integration Charge Coupled Device) can convert photon signals into electronic signals, and then display the image in combination with digital image processing technology. It has many advantages such as high signal-to-noise ratio, large dynamic range, and high reliability. It is widely used in push-broom satellite ground imaging and high-speed target detection.

[0003] The traditional vertical drive timing of TDI CCD is burst mode. Under this drive timing, the MTF in the push-scan direction is low, but the vertical edge will not interfere with the charge packet readout. In order to improve the dynamic MTF of push-scan TDI CCD satellite imaging and reduce image shift, the continuous transfer mode was invented. The continuous transfer mode can effectively improve the dynamic push-scan transfer function of TDI CCD, and perform horizontal transfer and charge packet readout while the vertical pulse action.

[0004] However, the vertical drive pulse will cause disturbance to the CCD device substrate when it jumps at the rising and falling edges. The disturbance will affect the CCD amplifier readout through the substrate, causing crosstalk in the readout signal, which is manifested as vertical stripes on the image. Summary of the invention

[0005] In order to solve the above-mentioned prior art problems, the present invention adopts a method for eliminating vertical drive pulse crosstalk in a continuous transfer mode. The continuous transfer timing signal of the TDI CCD module includes: a vertical drive pulse CI x , horizontal drive pulse CR x , reset pulse RST, transfer clock pulse TCK and vertical merge pulse SCK, the crosstalk elimination method includes:

[0006] Step 1: Adjust the rising edge time t of the vertical drive pulse r and falling edge time t f To time interval t i ; i is the number of iterations of step 1;

[0007] Step 2: In the TDI CCD module continuous transfer mode, fix the timing relationship between the horizontal drive pulse, reset pulse, transfer clock pulse TCK, and vertical merge pulse SCK, and set the vertical drive pulse CI x The rising and falling edges of the horizontal drive pulse CR x , the time interval between the reset pulses RST is adjusted to ji ×k; where k is the unit time interval, j i is the number of iterations of step 2 at the i-th iteration of step 1;

[0008] Step 3: Collect the image output by the TDI CCD module and detect whether there are vertical crosstalk stripes in the image. If yes, execute step 4; otherwise, solidify the vertical drive pulse CI x The rising edge time and falling edge time of the vertical drive pulse CI x The rising and falling edges of the horizontal drive pulse CR x , the time interval between the reset pulses RST;

[0009] Step 4: If the vertical drive pulse CI x The rising and falling edges of the horizontal drive pulse CR x , if the time interval between the reset pulses RST reaches the maximum time interval, return to step 1; otherwise, return to step 2.

[0010] The time interval t0 is equal to the period T of the horizontal drive pulse, t i <t i-1 .

[0011] Time interval

[0012] Unit time interval Wherein, T is the period of the horizontal driving pulse, and N is a custom parameter.

[0013] The maximum time interval is (N-1)×k.

[0014] Beneficial effects:

[0015] The present invention can avoid crosstalk of the vertical drive pulse rising edge and falling edge on the readout signal by adjusting the vertical drive pulse rising edge and falling edge time and the timing relationship between the vertical drive pulse rising edge and falling edge and the horizontal drive pulse and reset pulse. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of a continuous transfer timing provided by an embodiment of the present invention;

[0017] Figure 2 A flowchart of a method for eliminating vertical drive pulse crosstalk in a continuous transfer mode provided by an embodiment of the present invention;

[0018] Figure 3 An image containing crosstalk stripes provided by an embodiment of the present invention;

[0019] Figure 4 An image without crosstalk stripes after implementation provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] The present invention adopts a method for eliminating vertical drive pulse crosstalk in a continuous transfer mode, including: a TDI CCD module, a controller and an acquisition system; Figure 1 As shown, the continuous transfer timing signal of the TDI CCD module includes: vertical drive pulse CI x (CI1, CI2, CI3, CI4), horizontal drive pulse CR x (CR1_L_L / R_P, CR2_L_L / R_P, CR3_L_L / R_P, CR4_L_L / R_P, CR1_R_L / R_P, CR2_R_L / R_P, CR3_R_L / R_P, CR4_R_L / R_P), reset pulse RST (RST_L / R_P), transfer clock pulse TCK (vertical to horizontal transfer gate) and vertical merge pulse SCK (vertical merge gate).

[0022] like Figure 2 As shown, the vertical drive pulse crosstalk elimination method specifically includes:

[0023] Step 1: Adjust the rising edge time t of the vertical drive pulse r and falling edge time t f To time interval t i ; i is the number of iterations of step 1;

[0024] Step 2: In the TDI CCD module continuous transfer mode, fix the horizontal drive pulse CR x , the timing relationship between the reset pulse RST and the transfer clock pulse TCK and the fixed horizontal drive pulse CR x , the timing relationship between the reset pulse RST and the vertical merge pulse SCK, the vertical drive pulse CI x The rising and falling edges of the horizontal drive pulse CR x The time interval t is adjusted to j i ×k and the vertical drive pulse CI x The time interval t between the rising and falling edges of the reset pulse RST is also adjusted to j i ×k; where k is the unit time interval, j iis the number of iterations of step 2 at the i-th iteration of step 1;

[0025] Step 3: Collect the image output by the TDI CCD module and detect whether there are vertical crosstalk stripes in the image. If yes, Figure 3 If the result is as shown, then execute step 4; otherwise, Figure 4 As shown, the solidified vertical drive pulse CI x The rising edge time and falling edge time of the vertical drive pulse CI x The rising and falling edges of the horizontal drive pulse CR x The time interval between the vertical drive pulses CI x The time interval between the rising and falling edges of the reset pulse RST;

[0026] Step 4: If the vertical drive pulse CI x The rising and falling edges of the horizontal drive pulse CR x The time interval between the vertical drive pulses CI x If the time interval between the rising edge and falling edge of and the reset pulse RST reaches the maximum time interval, return to step 1; otherwise, return to step 2.

[0027] Step 1 The initial time interval t0 of the 0th iteration is equal to the period T of the horizontal drive pulse, t i <t i-1 ,

[0028] Unit time interval The maximum time interval is (N-1)×k, wherein T is the period of the horizontal driving pulse, and N is a parameter. Preferably, N is 8.

[0029] The TDI CCD module includes: TDI CCD, power conversion module, FPGA timing logic generation and control module, horizontal drive pulse generation module, vertical drive pulse generation module, CCD signal processing module, communication and image sending module; the power conversion module is used to provide a stable power supply; the FPGA timing logic generation and control module is used to generate and control various timing signals; the horizontal drive pulse generation module generates horizontal drive pulses; the vertical drive pulse generation module generates vertical drive pulses; the CCD signal processing module is used to process the signals output by the TDI CCD; the communication and image sending module is used to send image data.

[0030] The TDI CCD module has the ability to drive the TDI CCD to work according to control instructions, digitize the analog signals output by the TDI CCD and send image digital signals; the controller is connected to the TDI CCD module to control the continuous transfer timing signals of the TDI CCD module; the acquisition system is connected to the TDI CCD module to acquire the images output by the TDI CCD module.

[0031] The vertical driving pulse will cause disturbance to the CCD device substrate when it jumps at the rising and falling edges, and the disturbance will affect the CCD amplifier readout through the substrate; the function of the CCD amplifier is to convert the charge packet in the CCD horizontal register into a voltage signal, and if the substrate is disturbed at this time, it will affect the conversion gain of the amplifier; the crosstalk of the vertical driving pulse on the readout signal is manifested as vertical stripes appearing in the image; the CCD amplifier readout includes three time periods: reset pulse start, reset level establishment, and signal level establishment; the present invention ensures that the disturbance only occurs in the reset pulse start time period by adjusting the rising and falling edge time of the vertical driving pulse and the timing relationship between the vertical driving pulse edge and the horizontal driving pulse and reset pulse timing, and at this time the amplifier only performs reset and does not perform voltage conversion readout of the effective charge packet, thereby avoiding the crosstalk of the vertical driving pulse on the readout signal.

[0032] The above embodiments further illustrate the purpose, technical solutions and advantages of the present invention in detail. It should be understood that the above embodiments are only preferred implementation modes of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made to the present invention within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for eliminating vertical drive pulse crosstalk in a continuous transfer mode, comprising a TDICCD module, wherein the continuous transfer timing signal of the TDI CCD module comprises: A vertical driving pulse, a horizontal driving pulse, a reset pulse, a transfer clock pulse and a vertical merging pulse, wherein the crosstalk elimination method comprises: Step 1: Adjust the rising edge time t of the vertical drive pulse r and falling edge time t f To time interval t i ; i is the number of iterations of step 1; Step 2: In the continuous transfer mode of the TDI CCD module, the timing relationship between the horizontal drive pulse, the reset pulse, the transfer clock pulse, and the vertical merge pulse is fixed, and the time interval between the rising and falling edges of the vertical drive pulse and the horizontal drive pulse and the reset pulse is adjusted to j. i ×k; where k is the unit time interval, j i is the number of iterations of step 2 at the i-th iteration of step 1; Step 3, collect the image output by the TDI CCD module, and detect whether there are vertical crosstalk stripes in the image, if yes, execute step 4; otherwise, solidify the rising edge time and falling edge time of the vertical driving pulse and the time interval between the rising edge and falling edge of the vertical driving pulse and the horizontal driving pulse and the reset pulse; Step 4: If the time interval between the rising edge and the falling edge of the vertical driving pulse and the horizontal driving pulse and the reset pulse reaches the maximum time interval, return to step 1; otherwise, return to step 2.

2. The method for eliminating vertical drive pulse crosstalk in a continuous transfer mode according to claim 1, characterized in that: The time interval t0 is equal to the period T of the horizontal drive pulse, t i <t i-1 .

3. The method for eliminating vertical drive pulse crosstalk in a continuous transfer mode according to claim 2, characterized in that: Time interval 4. The method for eliminating vertical drive pulse crosstalk in a continuous transfer mode according to claim 1, characterized in that: Unit time interval Wherein, T is the period of the horizontal driving pulse, and N is a custom parameter.

5. The method for eliminating vertical drive pulse crosstalk in a continuous transfer mode according to claim 1, characterized in that: The maximum time interval is (N-1)×k.

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