针对LED显示屏播放运动画面时的动态假轮廓问题, 提出了集中式门控脉宽调制法.该方法在原有门控脉宽调制技术的基础上, 将PWM周期中的小数场固定于周期的中间, 然后计算整数权重位对应的子场数并将其紧邻小数场实现.分析和实验表明, 集中式脉宽调制法具有与线性PWM相似的点亮时间函数, 能够将任意两灰度级间DFC指标的均值从GPWM方式下的0.6降到0.2以下.在有效消除DFC的同时又保持了GPWM的高刷新频率与高灰度级, 从而明显改善图像的显示质量.同时算法实现简单, 不需要额外的硬件支持.

Aimed at the problem of dynamic false contour in LED display when playing the motion images, a novel of PWM method named concentrated gated pulse width modulation was proposed. Based on the GPWM, the approach fixes the decimal subfields on the center of one PWM period, and then figures out the number of subfields corresponding to the integer weight bits, and locate them near the decimal subfields. Theoretical analysis and experiments show that CGPWM has the similar lighting function with linear PWM, and consequently reduces the average DFC values between any two gray levels from 0.6 under the control of GPWM to 0.2. CGPWM can eliminate DFC effectively while maintaining high refresh frequency and rich gray levels, and thus improve the image quality greatly. Furthermore, the processing to implement CGPWM is simple without extra hardware.