| 摘要 |
To prevent irregular display such as bright lines or spots caused by power supply cut-off from appearing on a display screen.A switch controller is driven with a voltage VCH. During an on-state period, the switch controller divides charges in a charge carrier capacitor CC to boosting capacitors C2 to C4 to generate boosted voltages V2 to V4 each of which is higher than a source voltage VDD. A signal drive circuit and a scan drive circuit select a voltage from the voltages VDD and V1 to V4, and the selected voltages are applied to a liquid crystal display device to drive it. When the power supply is cut off, the source voltage VDD is reduced. A source voltage detector detects the voltage drop and a switch SW9 is turned to on-state. The switch controller is driven with the charges in a capacitor CG and turns switches SW1 to SW8 to on-state. Thus, the capacitors CC and C1 to C4 are discharged, and all voltages from a power source circuit are ground voltages VSS. As a result, the irregular display such as bright line or the like is prevented from occurring.
|
