POWER SUPPLY CIRCUIT FOR FLUORESCENT DISPLAY DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a power supply circuit for a fluorescent display device in which flexibility of cut-off voltage setting is high and an input voltage is all used as a voltage for a filament with low power consumption. SOLUTION: A switch SW1 and a switch SW2 are connected in series to an input line L1 of a direct voltage (input voltage) Vi and an ground line L2. A series connected circuit of a resistor R, diode D2 and a diode D1 are connected in parallel to the switch SW1. The diode D1 is used as a fixed voltage element and the diode D2 is used as a reverse current preventive element. A capacitor C1 is connected in parallel to the diode D1. A terminal F1 for the filament is connected to a connection point PA of an anode of the diode D1 and the capacitor C1. A capacitor C2 is connected between a terminal F2 for the filament and the ground line L2. The switch SW1 and the switch SW2 are periodically turns on and off mutually in opposite directions by a control circuit 13. COPYRIGHT: (C)2005,JPO&NCIPI