| 摘要 |
PURPOSE: To lessen and lighten an electronic ballast by transforming a pulse signal from a pulse width modulation special chip, turning on/off an FET ele ment for a switching regulator and feedbacking a detected current. CONSTITUTION: A signal supplied from a commercial power source 100 through a transformer T1 is supplied through the first bridge circuit BG1 to a switching regulator 104. Pulse transformers T3, T4 driven by a pulse width modulator 108 are used to supply a rectangular wave signal to a high-voltage discharge lighting circuit 106, while alternating turning on FET switching elements Q1, Q2, Q3, Q4. Voltage supplied to the circuit 106 is boosted up to four times with the opeartion of a diode and a capacitor. In the circuit 106, the voltage of a current-detecting resistor R14 is divided by resistors 4, 5 and the capacitor C8 to keep a supplied current constant and then supplied to a pulse width modulation special chip so as to keep an output current at a constant value. |
