Variable arc electronic ballast with continuous cathode heating
First Claim
1. A power conversion and control system for providing variable arc control of a lighting system comprising at least one lamp unit comprising at least one fluorescent gas discharge lamp including electrodes to be heated during the operation of the lamp, said system being powered from a commercial AC power source, and said system comprising means for converting AC power from said AC power source into converted DC power, a first DC to AC power converting means for converting said converted DC power into AC power for providing a variable arc drive for said lamps, sensor means for sensing a parameter related to the arc current flowing in said lamps and for producing a corresponding output, and a second, separate DC to AC power converting means for converting said converted DC power into AC power for supplying said first power converting means and for, responsive to the output of said sensing means, providing, at all times that the lamp is ignited, a heating voltage for said electrodes of a continuously variable value proportional to said parameter such that as the arc current flow decreases, the heating voltage for said electrodes increases.
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Accused Products
Abstract
A fluorescent lighting control system providing automatic and/or manual adjustability of the arc current(s) in one or more fluorescent lamps to permit operation of the lamps at less than rated wattage, and its concomitant luminous flux, in interior building spaces where full light output of the installed lamp(s) is rarely required particularly when daylight components are present. The goal(s) of this invention is to provide means to reduce wasteful electrical consumption in buildings and thereby reduce operating costs and gain the attendant benefit of dampening the increasing need for more electrical generation with its concomitant environmental pollution problem.
58 Citations
17 Claims
- 1. A power conversion and control system for providing variable arc control of a lighting system comprising at least one lamp unit comprising at least one fluorescent gas discharge lamp including electrodes to be heated during the operation of the lamp, said system being powered from a commercial AC power source, and said system comprising means for converting AC power from said AC power source into converted DC power, a first DC to AC power converting means for converting said converted DC power into AC power for providing a variable arc drive for said lamps, sensor means for sensing a parameter related to the arc current flowing in said lamps and for producing a corresponding output, and a second, separate DC to AC power converting means for converting said converted DC power into AC power for supplying said first power converting means and for, responsive to the output of said sensing means, providing, at all times that the lamp is ignited, a heating voltage for said electrodes of a continuously variable value proportional to said parameter such that as the arc current flow decreases, the heating voltage for said electrodes increases.
- 11. A power conversion and control system for providing variable arc control of a lighting system comprising at least one lamp unit comprising at least one fluorescent gas discharge lamp, said system comprising converter means for converting AC power from an AC source into DC power and switching means for controlling application of said DC power to at least one lamp unit, said switching means including first and second oppositely switching electronic switches having conducting and non-conducting states and control means for inhibiting turning on of one switch from the non-conducting state thereof, after the other, previously conducting switch has been turned off, until the voltage on the one switch approaches substantially zero volts, said system further comprising a protect inductor connected in shunt with said at least one lamp for providing a closed circuit path when said at least one lamp is effectively out of circuit so that stored energy is discharged thereby protecting said electronic switches.
Specification