Patent ID: 7068254

Claim:
A user identity authentication system comprising: a mobile information communication device; a liquid crystal display device provided in said mobile information communication device, and including a pixel portion having a plurality of pixels, each of said pixels comprising: a pixel thin film transistor having a source region, a drain region and a gate electrode; a source signal line connected to the source region; a liquid crystal element and a storage capacitor connected to the drain region; a gate signal line connected to the gate electrode; and a capacitance line connected to the storage capacitor, and an image sensor built in said liquid crystal display device, said image sensor comprising: a first thin film transistor having a first source region, a first drain region and a first gate electrode; a sensor gate signal line connected to the first gate electrode; a sensor output wiring connected to one of the first source and drain regions; a second thin film transistor having a second source region, a second drain region and a second gate electrode; a reset gate signal line connected to the second gate electrode; and a sensor power source line connected to the second drain region, wherein said image sensor reads individual information of a user, and a user's identity is authenticated based on the individual information.