Patent ID: 7462811
Filing Date: 2008-12-09
Classification: G01J,G02F

Abstract:
1. A circuit for detecting light comprising: a) a substrate, a light-integrating thin-film photosensor circuit formed on the substrate and a charge-accumulation circuit formed on the substrate comprised of a physical capacitor, a reset transistor for charging the physical capacitor in response to a reset signal, a photo sensor that discharges the physical capacitor in response to ambient light, and an amplifier responsive to the physical capacitor for creating a variable voltage signal, representing the accumulation of the ambient light over time; and b) a thin-film measurement circuit formed on the substrate for receiving a time measurement signal and the variable voltage signal to produce an output value representing the time required for the variable voltage signal to reach a predetermined voltage level, wherein the output value is proportional to the ambient light accumulated during the required time.