| 摘要 |
PURPOSE: An electronic ballast including cathode preheating current control circuit is provided to control a cathode preheating current of a fluorescent lamp filament by lowering a resonance voltage on both ends of a resonance condenser connected with a lamp. CONSTITUTION: A rectification unit(200) rectifies an AC(alternating current) signal into a DC(direct current) signal. A lighting unit(600) oscillates the voltage permitted from the rectification unit(200) to a resonance frequency and turns on a lamp. An inverter unit(400) receives the voltage rectified in the rectification unit(200) and gives rise to the resonance of the lighting unit(600). A starting circuit unit(300) performs an initial starting of the inverter unit(400). A switching element(Q3) has access to one of the trigger elements(Q1,Q2) of the inverter unit(400). A constant voltage diode(D11) has access to a control tab of the switching element(Q3). A cathode preheating current control circuit unit(500) has access to a secondary or a third winding(T2,T3) of a drive transformer, and the junction point consists of a voltage dividing resistance(R7,R8) connected to the constant voltage diode(D11).
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