| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply unit capable of attaining further power saving by reducing energy loss in a transformer at a power saving mode. SOLUTION: This power supply unit 1 always conducts a starting relay switch 21 at an ordinary-operation mode and always shuts down a triac 23 to obtain voltages V<SB>H</SB>, V<SB>B</SB>, V<SB>D</SB>for the ordinary-operation mode from a power circuit 6. At the power saving mode, on the other hand, the power supply unit 1 always shuts down the starting relay switch 21 and switches the triac 23 to obtain only the voltage V<SB>D</SB>for the power saving mode with a normal value from the power circuit 6. The switching timing is set so that it may turn on around zero cross timing for each prescribed cycle of AC power voltage V<SB>AC</SB>, based on the zero cross timing obtained from the AC power voltage V<SB>AC</SB>by means of an AC power voltage information part 7. COPYRIGHT: (C)2004,JPO
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