Implementation of pseudo PWM pulse to adjust brightness of LEDs in video displays

摘要

Huge outdoor video displays are widely used in modern cities. They are often composed of a huge number of pixels that in each of them three color LEDs exist. An image is produced on the display by adjusting the brightness of the LEDs. Adjusting the brightness of thousands of LEDs constitutes the main part of these video displays price. Therefore the simplification of this task is crucial market competition. The most common method of adjusting the brightness is using PWM signals where a PWM controller for each LED is required. In this paper a novel method which inspired from the original PWM method is proposed to do the task by simple and low cost circuits. The proposed method is implemented and the results show significant saving compared to typical video displays.