Patent ID: 7253391

Claim:
An optical sensor device comprising: an optical sensor element; and a current mirror circuit comprising at least first, second, and third thin film transistors, wherein a first electrode of the optical sensor element is electrically connected to each of a first region of the first thin film transistor and a gate of the first thin film transistor, wherein a second electrode of the optical sensor element is electrically connected to each of a first region of the second thin film transistor, a first region of the third thin film transistor, and a terminal, wherein a second region of the first thin film transistor is electrically connected to each of a second region of the second thin film transistor and a second region of the third thin film transistor, wherein the gate of the first thin film transistor is electrically connected to each of a gate of the second thin film transistor and a gate of the third thin film transistor, wherein each gate length of the first, second, and third thin film transistor are equal, wherein each channel width of the first, second, and third thin film transistor are equal, wherein the amount of current flowing into the terminal is pronortional to the number of thin film transistors in the current mirror circuit, and wherein the optical sensor element and the current mirror circuit are formed over a substrate.