Research Of The Way To Control The OLED Gray-Scale And Its Hardware Implementation

As the new research focus in the information display field, OLED driving circuit is of great significance, and the gray scale is an important parameter to judge the display quality. According to the gray-scale characteristic of the organic light emitting display(OLED), this paper puts forward the method of self-turn-off PWM gray-scale control, and on this based puts forward the method of Sub-frame gray-scale control based on the memory. Using the digital circuit design flow, powerful EDA tools and Verilog HDL language, Implemented scheme of the system is put forward, furthermore, the system is designed, simulated and the FPGA is implemented. The main work and achievements are listed as follows:1) Self-turn-off pulse-width modulation for OLED gray-scale controlling. According to the gray-scale characteristic of the organic light emitting display(OLED), this paper puts forward the method of self-turn-off PWM gray-scale control based on the memory, which controls the pixels' working condition being on or off separately. Implemented scheme of the system is put forward, furthermore, the system is designed, simulated and the FPGA is implemented. Comparing with the conventional method based on comparators, the new method has a few advantages as follows. It not only achieves the same duty cycle and scanning efficiency, but also could decrease the use of system hardware resource, especially in chip area. On the basis of these, it improves performance/cost ratio.2) Sub-frame gray-scale PM-OLED Control System based on memory. Putting forward the method of Sub-frame gray-scale control based on the memory, which controls the pixels' storage and display. Implemented scheme of the system is put forward, furthermore, the system is designed, simulated and the FPGA is implemented. FPGA is an efficient and flexible device for designing all kinds of digital circuit. 3) Using FPGA as the hardware circuit design and development platform, and using ROM and RAM which embedded in FPGA to simplify the design and greatly reduce the complexity of hardware circuit design. In addition, using Verilog HDL to achieve the entire system RTL code, and in line with the drive circuit to complete the all system. Finally, using this system as the drive of the 20*20 green PM-OLED, it could display 16 gray-scale correctly.Through the different levels of simulation and practical test to verify this paper presents Self-turn-off Pulse-width Modulation for OLED Gray-Scale Controlling and Sub-frame gray-scale PM-OLED Control System based on memory, and can display gray-scale image correctly in the OLED.