| 摘要 |
A size of a power supply circuit in a liquid crystal display device is reduced while an efficiency of the circuit is improved. The power supply circuit is formed on a TFT substrate of a liquid crystal panel and its output is provided to a vertical drive circuit. The power supply circuit is composed of a DC-DC converter that generates a positive power supply electric potential and a DC-DC converter that generates a negative power supply electric potential. The DC-DC converters are driven by a common electrode signal VCOM. The DC-DC converter that generates the positive power supply electric potential outputs VCOMHx2, and the DC-DC converter that generates the negative power supply electric potential outputs VCOMHx(-1). Thus electric potentials which are suitable to turn pixel transistors on and off are made available.
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