Patent ID: 6252357
Filing Date: 2001-06-26
Classification: H05B,Y02B

Abstract:
A self-ballasted fluorescent lamp comprising:a fluorescent arc tube having a U-shaped portion and a pair of electrodes located at each end of the fluorescent arc tube;a vessel having a base, said vessel supporting both ends of the fluorescent arc tube; anda ballast power supply including a plurality of inverter circuit parts which are mounted on a printed circuit board, the printed circuit board attaching in the vessel so that ends of the fluorescent arc tube may be covered, the ballast power supply providing high frequency power to the fluorescent arc tube, the inverter circuit parts including a self-destruct switch element located near the ends of the fluorescent arc tube so as to receive heat from the pair of electrodes, the switch element self-destructs when its temperature exceeds a predetermined threshold, the ballast power supply being arranged such that when the switch element self destructs, power to the fluorescent arc tube is shut off,wherein said inverter circuit parts include a half-bridge inverter circuit, said half-bridge inverter circuit accommodated in the base, which operates the fluorescent arc tube, and has two switch elements, one of which has a rated current that is less than the other, the smaller rated current switch element being the self-destructing one that is destroyed by over-current at the end of life of the fluorescent arc tube, thereby disabling the inverter circuit and removing power from the fluorescent arc tube at the end of its life.