High voltage power supply device for lighting discharge tube having protection circuit and fault protection circuit
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United States of America Patent
Stats
-
Nov 25, 2003
Grant Date -
Aug 1, 2002
app pub date -
Aug 7, 2001
filing date -
Aug 15, 2000
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
Current flowing through a cold cathode tube is detected and converted to a voltage with a resistor, and is fed to a tube current control circuit. The tube current control circuit drives a drive circuit to control a voltage applied to a piezoelectric transformer. Current from a constant-current source is used to charge a fault protection capacitor. A transistor is allowed to conduct while current flows through the cold cathode tube so that a voltage is developed in a resistor, and thereby, an electric charge is prevented from being stored in the fault protection capacitor, thereby stopping the operation of a fault protection circuit.
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