Control circuit design of novel partial gating detector by liquid crystal

摘要

A novel imaging system has been designed in order to enhance the dynamic range of image intensifier, and make itimage normally at high illumination based on the principle of liquid crystal for partial gating detection. This system ismade up of lens, HTPS TFT-LCD (proximity to the image intensifier), photometric CCD, main CCD and control circuit.Under the high illumination environment, main control chip FPGA extract the output signals of photometric CCD asfeedback signals, and get the environmental absolute intensity after some algorithm processing. Then the chip renews thecolor signals' value of YUV formats. Lastly, the HTPS TFT-LCD drive board receives the processed color signal,controls the transmittance of every pixel on the HTPS TFT-LCD. So the ultra bright partial of image can be weakened.Under the normal or weak light condition, LCD will be moved away by mechanical devices because its transmittance isabout 30%. This paper gives the control principle and structure of the system and puts forward the CCD' photometricprinciple.