Power supply circuit for driving liquid crystal display
AssigneeNEC Corporation
InventorKiyoshi Miyazaki
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Abstract
A drive power supply circuit for driving liquid crystal display of the present invention generates necessary levels in an LCD drive power supply circuit that generates drive levels for LCDs in an LCD controller/driver IC by means of switching connection to capacitors in a constant manner or in synchronism with the timing of LCD driving. It allows reduction in number of the components such as amplifiers for level generation and external capacitors, which in turn reduces current consumption of the entire system, chip areas, and mounting areas.
Claims13
A power supply circuit for driving liquid crystal display adapted to generate two or more drive voltages having intermediate voltage levels with respect to a peak voltage level, the intermediate voltage levels being classified into a first group of levels and a second group of levels, said power supply circuit for driving liquid crystal display comprising:
- an amplifier having a voltage follower configuration;
- one or more capacitors connected to the amplifier, said capacitors and said amplifier being provided for each level of the first group of levels to generate a level in cooperation with each other for the first group of levels;
- and
- switching means controlled at a predetermined timing to select a predetermined one of said capacitors to generate a level with a discharge voltage of the capacitor and the peak voltage level for the second group of levels.
A power supply circuit for driving liquid crystal display adapted to generate four drive voltages having intermediate voltage levels with respect to a peak voltage level, said power supply circuit for driving liquid crystal display comprising two amplifiers each having a voltage follower configuration, two capacitors, and two switching means, the four intermediate voltage levels being classified into a first group of levels and a second group of levels, wherein:
- said amplifiers and said capacitors generate a level for the two levels of the first group of levels, and
- said switching means controlled at a predetermined timing selects a predetermined one of said capacitors to generate a level with a discharge voltage of the capacitor and the peak voltage level for the two levels of the second group of levels.
A power supply circuit for driving liquid crystal display adapted to generate four drive voltages having intermediate voltage levels with respect to a peak voltage level, said power supply circuit comprising one amplifier having a voltage follower configuration, three capacitors, and three or four switching means, the four intermediate voltage levels being classified into a first group of levels and a second group of levels, wherein:
- said amplifiers and said capacitors generate a level for the one level of the first group of levels, and
- said switching means controlled at a predetermined timing selects a predetermined one of said capacitors to generate a level with a discharge voltage of the capacitor and the peak voltage level for the remaining three levels of the second group of levels.
Dependencies are inferred from the claim text.