US3569775A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for starting and operating electric discharge devices
Assignee: Unisys Corp
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Filing: 1968-08-29
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Granted: 1971-03-09
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Expires: 1988-08-29
Abstract
Abstract A transistor drives a fluorescent discharge lamp with unidirectional current. By suitably pulsing and controlling the current, various lighting effects are obtained. An impedance element conducts current so as to keep the fluorescent lamp in a fired condition whenever the transistor is not driving current. After firing the fluorescent lamp, a ballast coil in a starting circuit is short-circuited, resulting in minimum DC loss in the starting circuit during normal operation.
Inventors
- 👤 Charles P Halsted
- 👤 Daniel J Soltz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 09:50
CPC Classifications
H; H05; H05B; H05B41/00; H05B41/14; H05B41/36; H05B41/38
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
214 words
Apparatus comprising an electric discharge device having first and second filaments, means for heating said first filament, a transistor having one of its electrodes connected to said second filament and another of its electrodes coupled to a point of reference potential, a starting circuit operable to be connected between said first filament and said point of reference potential and then to be disconnected in the process of applying a starting firing potential between said filaments to enable said transistor to drive unidirectional current through said electric discharge device, and an impedance element shunted across said electrodes and effective to conduct a current flowing through said electric discharge device for keeping said electric discharge device in a fired condition whenever said transistor is not driving current, and wherein said starting circuit comprises a ballast coil and a switching device, said ballast coil having one terminal connected to said first filament and another terminal connected to a voltage source, and said switching device being operable to a first condition to connect said first filament and said one terminal to said point of reference potential to build up energy in said ballast coil and to a second condition to permit discharge of said energy for firing said electric discharge device and to short circuit said ballast coil.
Claim 2
Dependent Claim
214 words
Apparatus comprising an electric discharge device having first and second filaments, means for heating said first filament, a transistor having one of its electrodes connected to said second filament and another of its electrodes coupled to a point of reference potential, a starting circuit operable to be connected between said first filament and said point of reference potential and then to be disconnected in the process of applying a starting firing potential between said filaments to enable said transistor to drive unidirectional current through said electric discharge device, and an impedance element shunted across said electrodes and effective to conduct a current flowing through said electric discharge device for keeping said electric discharge device in a fired condition whenever said transistor is not driving current, and wherein said starting circuit comprises a ballast coil and a switching device, said ballast coil having one terminal connected to said first filament and another terminal connected to a voltage source, and said switching device being operable to a first condition to connect said first filament and said one terminal to said point of reference potential to build up energy in said ballast coil and to a second condition to permit discharge of said energy for firing said electric discharge device and to short circuit said ballast coil.
Claim 3
Dependent Claim
14 words
Apparatus according to claim 1 wherein said electric discharge device is a fluorescent lamp.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-03-08 | 1974-09-07 | 1975-03-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-08 | 1978-09-07 | 1979-03-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-08 | 1982-09-07 | 1983-03-09 | $7700.00 | Window Closed / Lapsed |