Patent ID: 6633271
Filing Date: 2003-10-14
Classification: G09G

Abstract:
A liquid crystal driving integrated circuit (1) for generating a liquid crystal driving voltage that drives a liquid crystal panel to present a display from respective connection points of a plurality of serially connected resistor elements forming a first resistor, wherein a reference voltage applied to one end of said first resistor is variable so as to adjust display contrast of said liquid crystal panel, said circuit comprising:a second resistor formed by a plurality of serially connected resistor elements and connected to a power supply; a reference voltage generation circuit having a selection circuit for deriving one of voltages at respective connection points of said plurality of resistor elements forming said second resistor, and generating said reference voltage based on an output from said selection circuit; a holding circuit for holding control data provided from an external source to control said selection circuit, said holding circuit includes a shift register (13) for holding control data formed by serially connecting first and second bit strings, a clock generation circuit (14) for generating a clock signal based on said first bit string, and a latch circuit (15-18) for latching said second bit string in accordance with said clock signal and supplying said bit string to said decoding circuit; and a decoding circuit (19) for decoding the control data held in said holding circuit and generating a control signal for operating said selection circuit.