Patent ID: 6091198
Filing Date: 2000-07-18
Classification: H04N

Abstract:
A cathode-ray tube video device for being connected to a power source and having a first normal operating state and at least a second reduced power operating state, the device comprising:a switching power supply having a first continuous operating state corresponding to the normal operating state of the device and at least one second operating state having a pulse train corresponding to the second reduced power operating state of the device wherein said switching power supply comprises:a filter circuit;a transformer having a primary winding;a plurality of secondary windings;an auxiliary winding which controls said electrically actuated switch through said filter circuit;a demagnetizing coil for demagnetizing the cathode-ray tube;an electrically actuated switch for coupling said demagnetizing means to the power source, said switch being closed to demagnetize the cathode-ray tube during the first normal operating state and being opened during the second reduced power operating state, wherein said electrically actuated switch comprises a TRIAC, a terminal connected to said demagnetizing coil and a control terminal connected to said filter circuit, and having a control terminal receiving an electrical signal from said filter circuit to change the TRIAC into conduction during the first normal operating state;a thermistor having a positive temperature coefficient and one end connected to a source of power and the other end connected to said demagnetizing coil;a diode rectifier bridge;an integrated circuit connected to said diode rectifier bridge for controlling current in the primary winding of the transformer to maintain constant voltages of the plurality of secondary windings;wherein said filter circuit comprisesa low pass filter for filtering the voltage applied by the auxiliary winding,a rectifying diode and at least one capacitor connected to said low pass filter for rectifying and smoothing the signal received from the low pass filter, anda resistive divider circuit connected to said rectifying diode and capacitor and the TRIAC and configured for allowing ""burst-mode"" and continuous mode operation.