In a field emission panel, the driving voltage is still a little high. Therefore, only a few driving chips with high voltage can be used. However, the clock frequency of these high voltage chips is normally not high enough. Thus, the image quality has to be decreased with the normal driving method. For example, we use only 5 bit data to display the video image in a FED panel. As we known, the 8 bit data can give 256 grey scales. If only 5 bit data are used, a few information of the video image will be lostIn this paper, the error diffusion method is used to improve the image quality in a FED. The tradition algorithm of error diffusion is Floyd-Stenberg Algorithm [1]. But there is still serious flicker in the picture just using die Floyd-Stenberg Algorithm to deal with the rounding error. Combining with the concrete applying on the FED panel drive circuit, some improvement on the error diffusion have been obtained in this paper. The rounding error not only diffuses to the frame just scanning, but also to the next frame. 3/4 of the rounding error diffuses to the frame just scanning, 1/4 to the next frame, as shows in picture 1.Picture 2 shows how to realize the improved error diffusion. We can realize it with four main modules: 1) Row FIFO, 2) Frame FIFO, 3) FIFO Control Module, 4) Error Diffusion Adder. The first row, the first column and the last column are specially dealt with "bypass" without considering the error diffusion, because they do not have the full round pixels. It could be clearly seen from the timing wave in picture 3.In this paper, we use ALTERA ACEX1K100 FPGA as the error diffusion circuit. It can be simply realized RGB (each 5 bit) by using three same circuits to deal with RGB signal respectively. Using the improved error diffusion drive circuit, only 5 bit data can achieve nearly 256 gray scales high quality picture.
展开▼
