Electric lamp and discharge devices: systems – Periodic switch in the supply circuit – Periodic switch in the primary circuit of the supply...
Patent
1983-06-21
1986-04-08
DeMeo, Palmer C.
Electric lamp and discharge devices: systems
Periodic switch in the supply circuit
Periodic switch in the primary circuit of the supply...
315287, 315DIG7, 363 56, 363 74, H05B 3702, H05B 3904, H05B 4136
Patent
active
045815623
ABSTRACT:
Subject invention relates to an inverter-type electronic fluorescent lamp ballast wherein a series-resonant LC circuit connected across the inverter's output is used for matching the inverter's operating characteristics to those of the fluorescent lamp. The fluorescent lamp, combined with a Varistor, is connected in parallel with the tank-capacitor of this LC circuit. Thus, the starting voltage provided for the lamp is limited by the voltage-clamping-effect of the Varistor; and before the fluorescent lamp starts, all the output current from the ballast flows through this Varistor. After the lamp has started, however, the ballast output current shifts away from the Varistor and over to the lamp--leaving only a negligible amount of current to flow through the Varistor on a continuous basis. The essential aspect of subject invention relates to using the current flowing through the Varistor--with the help of an isolating current transformer--for providing heating power to the lamp cathodes. That way, the starting of the fluorescent lamp is accomplished in a normal rapid-start or trigger-start fashion; but, after the lamp has started, the power provided to the cathodes diminishes to a negligible level. Consequently, without the use of overt switching means, etc., subject ballast gains the efficiency-advantage associated with removing the cathode heating power after the lamp has started.
REFERENCES:
patent: 4286194 (1981-08-01), Sherman
patent: 4370600 (1983-01-01), Zansky
patent: 4375608 (1983-03-01), Kohler
patent: 4378514 (1983-03-01), Collins
patent: 4461980 (1984-07-01), Nilssen
DeMeo Palmer C.
Oen William L.
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