| 摘要 |
PROBLEM TO BE SOLVED: To provide nurse call equipment which enables the lifetime of a back light to be extended by changing the luminance of the back light of a liquid crystal panel in accordance with the illuminance around the installation place. SOLUTION: An illuminance detecting optical sensor 36 for each of corridor lamps 11, 12,... with a liquid crystal panel monitors illuminance around the entrance/exit of a hospital ward being in the periphery of the place where a corresponding corridor lamp is installed, and an analog switch 37 is turned on and the current value of an AC current supplied from a DC-AC inverter unit 38 to a back light 35 of a liquid crystal panel 34 is reduced to (automatically) dim the back light when low illuminance is detected by the illuminance detecting optical sensor, for example, at night, so that the lifetime of the back light can be extended. COPYRIGHT: (C)2004,JPO
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