Patent ID: 6847131
Filing Date: 2005-01-25
Classification: G06F,H02M

Abstract:
1. A power supply device for supplying a stabilized output DC voltage to an electronic equipment having a controller for controlling said electronic equipment, said power supply, comprising: a rectification section for rectifying an input AC voltage; a primary side capacitor for smoothing an output voltage from said rectification section; a switching power supply section for receiving a DC voltage from said primary side capacitor as an input DC voltage at a primary side thereof, switching the inputted DC voltage and generating said stabilized output DC voltage at a secondary side thereof isolated from the primary side; a current detection section comprising a current detector, and a photo-coupler having a photodiode connected parallel to said current detector via a resistor and a phototransistor supplied by said stabilized output DC voltage via a resistor, wherein said current detector connected between said rectification section and said primary side of said switching power supply section detects a supply current supplied from said rectification section, and generates a voltage enough for turning on said photodiode, and wherein said phototransistor generates a synchronization signal isolated from said primary side in response to said turning on of said photodiode; and a control section monitors said synchronization signal outputted from said current detection section, generates a detection signal when said synchronization signal stops for more than a predetermined period of time, and outputs said detection signal to said controller; wherein said controller of said electronic equipment performs an operation ending process of said operation circuit in response to the detection signal from said control section.