Patent ID: 7009593

Claim:
A liquid crystal display device used by a main system, comprising: a digitizer for producing signals indicative of a location by an external input and driven according to a first clock generated by a first clock generator; a liquid crystal display device for displaying a predetermined information according to the signal from the digitizer, the liquid crystal display device having first and second substrates with a liquid crystal layer interposed therebetween, and data and gate lines; and a printed circuit board having a drive circuit for controlling the digitizer and the liquid crystal display, wherein the drive circuit including: a power supply for supplying a voltage to the LCD panel and the digitizer; a clock generator for producing clock signals to drive the LCD device and the digitizer; an analog to digital (A/D) converter for converting analog signals to digital signals; a gamma circuit for correcting gamma characteristics of the LCD device; a first input/output (I/O) unit for conveying analog signals from the digitizer to the A/D converter and conveying signals from the controller to the digitizer; a second input/output (I/O) unit for transferring digital signals in the form of x-y coordinate values from the A/D converter to the main system; data and gate drivers driven by the clock generator; and a controller for controlling all components of the drive circuit.