| 摘要 |
PROBLEM TO BE SOLVED: To provide an encoder for fully taking time until voltage drop failure is detected after detecting a voltage drop alarm of a backup power supply and exchanging the battery of a backup power supply with a time margin. SOLUTION: In the encoder having the backup power supply for supplying power to the encoder when the main power supply of the encoder is off, the backup power supply includes two systems of batteries comprising main and sub batteries, supplies power to the encoder from the main battery after the power supply of the encoder is changed from the main power supply to the backup power supply, and changes the battery for supplying power to the encoder from the main battery to the sub battery, when the voltage level of the main battery drops to a prescribed voltage level requiring the change of the battery. COPYRIGHT: (C)2010,JPO&INPIT
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