一种支持OLED亮度补偿的电流型PWM像素驱动电路

OLED(organic light-emitting diode,OLED)微显示器长时间工作在高对比度、高亮度的状态下,OLED像素衰退不一致,发光亮度衰退也不一致,会产生残影现象。因此,提出了一种改进的电流型PWM像素驱动电路,保持了对OLED像素衰退补偿效果,同时可以读出OLED阳极电压,计算得到OLED衰退信息,以便于对OLED亮度衰退进行有效的补偿。文章中分析了改进的电流型PWM驱动电路结构,及其对OLED衰退补偿和亮度补偿的原理。通过模拟仿真,得到几个影响OLED衰退补偿效果的关键参数。当OLED像素衰退电阻R_oled小于40 MΩ时,该电流型PWM驱动电路电流衰退度与传统2T1C驱动电路相比,只为其衰退度的50%。

Current PWM pixel driving circuit with OLED luminance compensation

OLED microdisplay will suffer the pixel degradation and the luminance degradation after working in the high light and high contrast ratio state for a long time, which induces the ghost phenomenon. Therefore, this article proposes an improved current PWM pixel driving circuit which make compensations for the OLED pixel degradation. At the same time, the proposed circuit can also read the anode voltage of the OLED pixel, so the degree of the OLED degradation can be calculated and the luminance degradation can be compensated. This paper analyses the circuit structure and the compensation principle on the OLED degradation and luminance degradation. The key parameters which affect the OLED degradation compensation are obtained by the simulations. The experiment results show that the ratio of the OLED degradation of the proposed current PWM driving circuit is only 50% of the traditional 2T1C driving circuit when the difference of pixel degradation is less than 40 MΩ.