US 6,661,402 B1Granted

Liquid crystal driver circuit and LCD having fast data write capability

AssigneeHitachi, Ltd.

InventorsHiroyuki Nitta, Kazuyoshi Kawabe, Satoru Tsunekawa, Hirobumi Koshi

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Abstract

A fast-write, high picture-quality LCD (Liquid Crystal Display) compatible with a high-resolution, large-sized liquid crystal panel. An output amplifier circuit of a liquid crystal driver circuit includes an amplifier configuration, which functions as an amplifier that amplifies the predetermined gray-scale voltage for output and as an amplifier that buffers the predetermined gray-scale voltage and outputs with no amplification, and a circuit for switching the above two types of amplifiers. In each horizontal period, a liquid crystal panel is driven by the amplified output for a predetermined period and by the buffered output for the rest of the period. A pre-charge control circuit is provided to check whether the gray-scale voltage is to be amplified depending upon display data.

Claims17

Dependent claims

The LCD comprising:

a liquid crystal panel having data lines, scan lines, and pixels arranged in a matrix;
a scanning circuit selecting scan lines to which a voltage is to be applied;
and
a data driver circuit providing a liquid crystal application voltage corresponding to display data to said data lines of said liquid crystal panel, said data driver circuit comprising:
a positive-polarity DAC circuit generating a positive-polarity liquid crystal application voltage corresponding to said display data;
a negative-polarity DAC circuit generating a negative-polarity liquid crystal application voltage corresponding to said display data;
a positive-polarity amplifier circuit amplifying said positive-polarity liquid crystal application voltage at an amplification factor higher than one;
and
a negative-polarity amplifier circuit amplifying said negative-polarity liquid crystal application voltage at an amplification factor higher than one, wherein said data driver circuit switches between conditions based on a value of the display data, one of said conditions being such that both a driving voltage higher than the liquid crystal application voltage and the liquid crystal application voltage corresponding to the display data are output when the alternately switching polarity is positive and the other being such that both a driving voltage lower than the liquid crystal application voltage and the liquid crystal application voltage corresponding to the display data are output when the alternately switching polarity negative.

6 more elements

A date driver circuit including an output amplifier for applying a liquid crystal application voltage corresponding to display data to a liquid crystal panel, wherein said data driver circuit comprises;

a positive-polarity DAC circuit generating a positive-polarity liquid crystal application voltage corresponding to said display data;
a negative-polarity DAC circuit generating a negative-polarity liquid crystal application voltage corresponding to said display data;
a positive-polarity amplifier circuit amplifying said positive-polarity liquid crystal application voltage at an amplification factor higher than one;
and
a negative-polarity amplifier circuit amplifying said negative-polarity liquid crystal application voltage at an amplification factor higher than one a liquid crystal panel having data lines, scan lines, and pixels arranged in a matrix;
a scanning circuit selecting scan lines to which a voltage Is to be applied;
and
a data driver circuit providing a liquid crystal application voltage corresponding to display data to said data lines of said liquid crystal panel,
said data driver circuit comprising:
a positive-polarity DAC circuit generating a positive-polarity liquid crystal application voltage corresponding to said display data;
a negative-polarity DAC circuit generating a negative-polarity liquid crystal application voltage corresponding to said display data;
a positive-polarity amplifier circuit amplifying said positive-polarity liquid crystal application voltage at an amplification factor higher than one;
and
a negative-polarity amplifier circuit amplifying said negative-polarity liquid crystal application voltage at an amplification factor higher than one, wherein said data driver circuit switches between conditions based on a value of the display data, one of said conditions being such that both a driving voltage higher than the liquid crystal application voltage and the liquid crystal application voltage corresponding to the display data are output when the alternately switching polarity is positive and the other being such that both a driving voltage lower than the liquid crystal application voltage and the liquid crystal application voltage corresponding to the display data are output when the alternately switching polarity is negative.

11 more elements

A crystal display (LCD) a liquid crystal panel having data lines, scan lines, and pixels arranged in a matrix;

a scanning circuit selecting scan lines to which a voltage is to be applied;
and
a data driver circuit providing a liquid crystal application voltage corresponding to display data to said data lines of said liquid crystal panel,
said data driver circuit comprising:
a positive-polarity DAC circuit generating a positive-polarity liquid crystal application voltage corresponding to said display data;
a negative-polarity DAC circuit generating a negative-polarity liquid crystal application voltage corresponding to said display data;
a positive-polarity amplifier circuit amplifying said positive-polarity liquid crystal application voltage at an amplification factor higher than one;
and
a negative-polarity amplifier circuit amplifying said negative-polarity liquid crystal application voltage at an amplification factor higher than one
wherein said data driver circuit further comprises a selection circuit which selects whether said positive-polarity amplifier circuit and said negative-polarity amplifier circuit amplify said liquid crystal application voltage equal to or higher than one amplification factor.

7 more elements

Dependencies are inferred from the claim text.