| 摘要 |
PROBLEM TO BE SOLVED: To generate reference voltage matched with the temperature characteristic of a liquid crystal Vop in a wide temperature range and to drive the liquid crystal based on the reference voltage. SOLUTION: Constant voltage power supplies 11A, 11B respectively generate constant voltages having respectively different temperature characteristics. The temperature characteristic of constant voltage generated from the constant voltage power supply 11A almost coincides with the average change rate of voltage against a temperature change on the low temperature side of the liquid crystal Vop and the temperature characteristic of constant voltage generated from the constant voltage power supply 11B almost coincides with the average change rate of voltage against a temperature change on the high temperature side of the liquid crystal Vop. A comparator 13 compares the output voltage of the constant voltage power supply 11A with that of the constant voltage power supply 11B and analog switches 14A, 14B are complementarily turned on or off on the basis of the compared result. Consequently the constant voltage power supply 11A or the constant voltage power supply 11B is selected and constant voltage outputted from the selected constant voltage power supply 11A or 11B is outputted as reference voltage. COPYRIGHT: (C)2006,JPO&NCIPI
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