Design Of Dynamic Image Display Control System Oriented To Grating Light Modulator Array

Grating light modulator is a kind of MEMS-based optical modulator which can be used for digital projection display. Because the technology of device research is still at a preliminary stage, a design of control circuit system is an important part of the research which can be used to verify and test effect of projection display. Projection display principle of grating light modulator is analyzed in this paper. In accordance with the gray levels method of grating light modulator, a display control system for the small (16×16) passive and active grating light modulator array is proposed. The system can be used for displaying different effect monochrome dynamic image,which can reach 16 gray levels.Communication theory between PC application and USB device is analyzed and discussed. The application software is designed on PC using Visual C++ language. It can produce dynamic image data of text, graphics and graded gray,and show that in the application interface. After format conversing, the dynamic image data is packaged and transmitted to the development board, which have a USB controller through a USB cable.The digital control circuit (4 grade monochrome gray) of the passive and active grating light modulator array (16×16) is designed, using the Altera Cyclone FPGA chip (EP1C6Q240C8) as a hardware development platform,and Verilog HDL as hardware description language. The control circuit includes FPGA to USB interface module, barrel shifter format conversion module, dual ports RAM ping-pong operation controller module, binary pulse width modulation control circuit for passive device and binary field pulse width modulation circuit for active device.Cross effect of the passive grating light modulator is analyzed. In view of passive grating light modulator array (16×16), driving circuit of adjustable bias witch can inhibit cross effect is designed. As the display method of line by line scan and the graying principle of passive grating light modulator array with LED array are similar, the testing circuit board of LED array instead of passive grating light modulator array is designed. The entire control system is tested by circuit board of LED array. Test platform for single pixel of the grating light modulator array is established. Testing experiment of single pixel like operating voltage, pull-in voltage and frequency of square wave driving voltage is done. At last, test platform of grating light modulator dynamic projection display system is established. Dynamic image projection display experiment for the control system is done. As the result of the test shows that the system is stable, reliable, and convenient to handle. It provides a strong technical support for testing dynamic display of grating light modulator.