Power supply apparatus for fluorescent lamp
OwnerKen Hashimotoinventor
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Abstract
A power supply apparatus for a fluorescent lamp comprises an inverter circuit for converting AC line power to a high-frequency drive voltage having a square waveform, this high-frequency drive voltage being applied to a fluorescent lamp through an inductor and a capacitor connected in series to form a series-resonance circuit which provides a ballast impedance after ignition of the fluorescent lamp has been achieved. A sufficiently high voltage to ensure reliable ignition of the fluorescent lamp is ensured by a ringing oscillation which is produced across another capacitor, connected across the lamp, when the fluorescent lamp is in the high-impedance state prior to ignition.
Claims3
A power supply apparatus for a fluorescent lamp, comprising:
- inverter means coupled to a source of AC line power, for converting said AC line power to a high-frequency drive voltage having a substantially square waveform, produced from first and second outputs thereof;
- an inductor and a first capacitor connected in series between said inverter means and a first filament of said fluorescent lamp, for supplying said high-frequency drive voltage to said fluorescent lamp, with the capacitance of said first capacitor and the inductance of said inductor forming a series resonant circuit whose frequency of resonance is higher than but less than twice the value of the frequency of said high-frequency drive voltage, and;
- a second capacitor connected between an output terminal of said inductor and a second filament of said fluorescent lamp, with the capacitance value of said second capacitor being lower than that of said first capacitor.
Dependencies are inferred from the claim text.