Synaptics Incorporated
Dithering a clock used to update a display to mitigate display artifacts

Abstract:

A display device can use clock dithering to spread the frequency spectrum of the clock signal (and the signals derived therefrom) to mitigate interference with other components or systems in a host device. However, dithering the clock signal can introduce display artifacts into the display device. For example, lines or rows in the display may flicker, the brightness of display lines may be non-uniform, or color shifts in displayed pixels. To reduce display artifacts, the embodiments herein synchronize clock dithering to a display update event. That is, the display device varies a parameter of clock dithering so that the dithering is synchronized to the display update event. In another embodiment, the clock dithering is set according to the rate at which display lines or sub-pixels are updated. In another embodiment, clock dithering is synchronized to a display frame update period.