| 摘要 |
PURPOSE:To supply power to a secondary side of an insulating transformer for a predetermined time even if short power interruption occurs by discharging an electric storage element for delaying a control signal to a switching controller when a power supply from a power supply source is interrupted. CONSTITUTION:An AC input is supplied to primary, secondary insulating transformers 39 via a filter 40, a rectifier 41 and a smoothing circuit 42, and switched by an FET 43. A delay circuit 35 for delaying a control signal of this switching is provided. The circuit 35 has a time constant between resistors 48, 61 and a capacitor 62 of an electric storage element, and sets the constant by altering resistance values of the resistors 48, 61 and an electric capacity of the capacitor 62. A discharge circuit 64 is provided, charge stored in the capacitor 62 is immediately discharged even when a short interruption of an AC input occurs, and when the AC input is again recovered, the constant is altered to supply power to the secondary side. Accordingly, an erroneous operation of the system can be prevented. |
