Electric lamp and discharge devices: systems – Periodic switch in the supply circuit – Silicon controlled rectifier ignition
Patent
1994-08-18
1996-04-30
Gonzalez, Frank
Electric lamp and discharge devices: systems
Periodic switch in the supply circuit
Silicon controlled rectifier ignition
315241R, 315243, 315244, H05B 3702
Patent
active
055128017
ABSTRACT:
In an electronic ballast, a half-bridge inverter is powered from a DC voltage and provides a nominal 30 kHz square-wave-like inverter output voltage. The inverter output voltage is applied to a series-resonant LC circuit. Parallel-connected across the tank capacitor of this LC circuit are plural series-combinations, each consisting of an instant-start fluorescent lamp series-connected with a current-limiting capacitor. The magnitude of the high-frequency voltage present across the tank capacitor is controlled by controlling the frequency of the inverter output voltage. Prior to lamp ignition, the magnitude of the high-frequency voltage is controlled to a relatively high level, such as to provide for sufficiently forceful lamp ignition. After the lamps have fully ignited, to enhance overall efficiency, the magnitude of the high-frequency voltage is reduced to a relatively low level. This low level is too low to provide for lamp ignition but sufficiently high to permit proper lamp operation. If, subsequently, one of the lamps were to cease operating, the magnitude of the high-frequency voltage would start pulsing at a 120 Hz rate, spending about 90% of the time at the low level and 10% of the time at the high level.
REFERENCES:
patent: 4277728 (1981-07-01), Stevens
Gonzalez Frank
Ratliff Reginald A.
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