A compensation circuit is necessary in each pixel of the organic light‐emitting diode (OLED) display to reduce the mura resulting from the nonuniform characteristics of the low‐temperature polycrystalline silicon thin‐film transistor (TFT). Recently, the mura becomes severe as the frame rate, display resolution, and the OLED efficacy improve. The low‐gray mura for the OLED current far below 1 nA is easily noticed, which is a critical issue of the high‐end mobile OLED display. We report the correlation between the deviation of OLED current due to the nonuniform TFT characteristics and the compensation time by in‐depth analysis employing the SPICE simulation of two well‐known pixel circuits. We have found that the compensation effect improves as the compensation time increases for low gray‐level current. On the contrary, the compensation effect deteriorates, and the deviation of OLED current intensifies for high gray‐level current as the compensation time increases too much. The quantitative analysis shows that the optimal compensation time depends on the targeted OLED current level and that the compensation effect is highest when the compensation time is such that the current of the driving TFT at the end of compensation period is several times smaller than the targeted OLED current during the light‐emitting period.

中文翻译：

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补偿时间与有机LED像素电路电流偏差的相关性

在有机发光二极管（OLED）显示器的每个像素中都必须有一个补偿电路，以减小由低温多晶硅薄膜晶体管（TFT）的不均匀特性引起的色斑。最近，随着帧速率，显示分辨率和OLED效率的提高，mura变得越来越严重。OLED电流远低于1 nA的低灰斑容易引起注意，这是高端移动OLED显示器的关键问题。我们通过使用两个著名像素电路的SPICE仿真进行深入分析，报告了由于TFT特性不均匀导致的OLED电流偏差与补偿时间之间的相关性。我们发现，对于低灰度电流，补偿效果随着补偿时间的增加而提高。反之，随着补偿时间增加太多，补偿效果变差，并且对于高灰度级电流，OLED电流的偏差会加剧。定量分析表明，最佳补偿时间取决于目标OLED电流水平，并且当补偿时间使得在补偿周期结束时驱动TFT的电流比目标OLED小几倍时，补偿效果最高。发光期间的电流。