Active pixel sensor and method for making same

摘要

A touch panel includes a plurality of active pixel sensors arranged in an array to sense a touch event. Each sensor element includes a photo-sensing element coupled to a single amplifier. The sensor element is arranged to provide a sensing voltage indicative of a light level received by the photo-sensor in a sensing period. The sensing voltage is amplified by the amplifier into an output voltage in the sensing period. Following the sensing period, the output voltage and the sensing voltage are reset to a predetermined voltage level. Following the reset period, the photo-sensor as well as the amplifier is disabled for a period so that the sensing level is caused to drop below the predetermined voltage level.