| 摘要 |
PROBLEM TO BE SOLVED: To facilitate wiring work and maintenance, by connecting a main power source to a backup power source in common, installing a main power source voltage detection circuit and a power source switching circuit, and stopping the power supply to a regular operation circuit and supplying power only to an outage operation circuit when the voltage of the main power source lowers below a fixed value. SOLUTION: A main power source/backup power source 20 in which the main power source 1 and backup power source 7 are connected in common, is connected directly to a regular operation circuit 3 and an outage time operation circuit 4 of an encoder 2 through a first diode 5. A built-in battery 6 comprising the outage operation circuit 4 and a capacitor parallel with the outage time operation circuit 4 is connected to a first diode 5. A power source switching circuit 30 comprising a transistor and a main power source voltage detection circuit 31 are connected to the regular operation circuit 3. When a voltage of the main power source 1 lowers below a fixed level or the power fails, the power source switching circuit is switched by a detection signal 31a, the operation of the regular operation circuit 3 is stopped, and only the outage time operation circuit 4 is operated. |
