Pm-oled With A Constant Current Source Driver Circuit

Since 1987, C.W.TANG in Kodak Corp (USA) developed a new kind of organic light-emitting device (OLED) with low drive voltage and high efficiency, OLED has received much attention in the FPD field. With so many excellent virtues , OlED has the potential to dominate the display market in the near future. This thesis mainly discusses the design of driving circuit and the constant current source for OLED. Firstly, the concepts and theories about the mechanisms of organic electro-luminescence were introduced. Then we analyzed the relationship between the luminance and the density of current of OLED as well as the voltage-current characteristic of OLED. Some recent research on the driving circuit design for the PM-OLED was showed. And some kind of driving IC was presented in this thesis too. The BJT-constant current source that we designed consists of transistors and resistors . And this current source relys on feed back techniques to achieve regulation. Some measures were taken to improve its stability and temperature characteristics correspondingly. Experiments have been done to test this BJT-constant current source. After the analysis of the large amount of data ,we discussed the effect of BJT's Vbe on the output current IL, and how the resistors'temperature characteristic affect the stability of the constant current source. Then we evaluated the temperature characteristics of the constant current source. The precision of this constant current source was about 3%. Finally , we design the driving circuit for OLED,including the design of the column driver and the row driver. The constant current sources have been proved efficient in wiping out the cross talk which had been caused by the voltage drops along the column (ITO anode) of OLED. The display quality thus have been improved effectively.