| 摘要 |
PURPOSE: To provide an electronic ballast useful for controlling a gas discharge lamp. CONSTITUTION: An electronic ballast connected between a power source 2 and a lamp 4 controls power supplied to the lamp 4. An inverter 14 generates a cyclic waveform at a controlled frequency. A resonance circuit 16 connected to the inverter 14 is tuned so as to generate an output voltage by resonating at a fixed frequency. A coupling capacitor C2 connected between the circuit 16 and the lamp 4 supplies the output voltage Vλ of the circuit 16 to the lamp 4. A controller 22 presets an operation frequency of the inverter 14 near a resonance frequency of the circuit 16 and responds to a fixed preset value control voltage and the voltage Vλ. The circuit 16, being tuned, increases a voltage from the inverter 14 to a level enough for the lamp 4 to operate in a glow mode. The capacitor C2 and the circuit 16 each have an appropriate impedance and maintain a power flow to the lamp 4 enough for the lamp 4 to operate in the glow mode, then an arc mode, and a steady state mode. |
