Nec Corporation

Nec Electronics Corporation

Nobuo Shimizu

Yasuhiro Kosaka

A horizontal driver in a LCD driver includes a D/A converter having a PROM decoder block and an NROM decoder block for driving a LCD panel in a dot reversible driving scheme. Each data line receives alternately a gray-scale signal having a positive polarity generated by a PROM decoder and a gray-scale signal having a negative polarity generated by an NROM decoder, and an odd-numbered data line and an even-numbered data line receive gray-scale signals having opposite polarities. The order of the decoders is matched by a switching block with the order of the data lines by switching the display data and the gray-scale signals.

Driver unit for driving an active matrix LCD device in a dot reversible driving scheme

An output circuit of a liquid crystal display driver has a first operational amplifier fast in potential rise and slow in potential decay and a second operational amplifier fast in potential decay and slow in potential rise both serving as voltage followers, and the first operational amplifier and the second operational amplifier are alternately connected to a data line of a liquid crystal display panel so as to alternate the potential level on the data line between a positive range and a negative range with respect to a reference voltage level on a common electrode of the pixels at changes of horizontal periods, wherein a reset circuit is connected to the first and second operational amplifiers so as to forcibly reset the non-inverted nodes and the output nodes to the reference voltage level in each transient period between the horizontal periods, thereby eliminating undershoot and overshoot due to the slow potential change from the potential waveform on the data line.

Growing community of inventors

Shiga, Japan

Nobuo Shimizu