EP0245568A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Transient control circuit for fluorescent lamp systems
Assignee: Individual
•
Filing: 1986-05-13
•
Granted: —
•
Expires: 2006-05-13
Abstract
Abstract A method and apparatus are provided for operating a fluorescent lamp illumination control system which comprises an AC voltage source for supplying power to an electrical load comprising a standard transformer-ballast unit driving a fluorescent lamp or lamps which have externally heated cathodes, and a power controller, which includes a capacitive synchronous switch formed by an electronic switch and shunt capacitor, for controlling the "on" time of the lamp or lamps to thereby vary the luminance output thereof to values less than the nominal rated value. The invention provides heating of the lamp cathodes prior to arc ignition, provides arc ignition at a lower arc current level than that for full-on operation, and provides for subsequently gradually increasing the arc current after the arc is struck to a value providing the desired illumination level.
Inventors
- 👤 Don F. Widmayer
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 15:16
CPC Classifications
H; H05; H05B; H05B41/00; H05B41/14; H05B41/36; H05B41/38; H05B41/39; H05B41/392; H05B41/3921; H05B41/3924; Y; Y10; Y10S; Y10S315/00; Y10S315/07
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
190 words
A system for controlling the A.C. power supplied from an A.C. source to an electrical load comprising at least one transformer ballast and at least one fluorescent lamp driven by said transformer ballast and including externally heated cathodes, said system including a switch connected between the A.C. source and the load, a power controller for controlling switching of said switch in timed relation to the A.C. source voltage wave so as to control the power supplied to the load, a capacitor connected in shunt across said switch, and control means, connected to said power controller, for responsive to energization of the system, controlling the switching operation of the switch provided by said power controller so as to initially limit the arc current supplied to the load and thereby provide for ignition of the arc of the at least one fluorescent lamp at an arc current level less than that provided during full on operating conditions while still providing heating of said externally heated cathodes prior to the ignition of said arc and to thereafter provide gradually increasing arc current up to a predetermined value which produces the desired illumination level.
Claim 2
Independent Claim
190 words
A system for controlling the A.C. power supplied from an A.C. source to an electrical load comprising at least one transformer ballast and at least one fluorescent lamp driven by said transformer ballast and including externally heated cathodes, said system including a switch connected between the A.C. source and the load, a power controller for controlling switching of said switch in timed relation to the A.C. source voltage wave so as to control the power supplied to the load, a capacitor connected in shunt across said switch, and control means, connected to said power controller, for responsive to energization of the system, controlling the switching operation of the switch provided by said power controller so as to initially limit the arc current supplied to the load and thereby provide for ignition of the arc of the at least one fluorescent lamp at an arc current level less than that provided during full on operating conditions while still providing heating of said externally heated cathodes prior to the ignition of said arc and to thereafter provide gradually increasing arc current up to a predetermined value which produces the desired illumination level.
Claim 3
Dependent Claim
71 words
A system as claimed in Claim 1 wherein said power controller comprises a control circuit for producing a square wave output for controlling switching of said switch and said control means initially inhibits the square wave output of said control circuit and thereafter controls the duration of the square wave pulses produced by said control circuit so as to provide a gradual increase in the duration of said pulses with time.
Claim 4
Dependent Claim
34 words
A system as claimed in Claim 2 wherein said control circuit includes an operational amplifier and said control means comprises means for supplying a gradually increasing voltage to one input of said operational amplifier.
Claim 5
Dependent Claim
32 words
A system as claimed in Claim 3 wherein said voltage supplying means comprises a resistor-capacitor circuit and said gradually increasing voltage is produced by charging of the capacitor of the resistor-capacitor circuit.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.