US3700960A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Metal halide lamp system
Assignee: General Electric Co
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Filing: 1971-09-23
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Granted: 1972-10-24
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Expires: 1991-09-23
Abstract
Abstract A major difficulty with long linear metal halide type lamps is nonuniformity of light output along the axis of the lamp. The extent of nonuniformity increases with the number of metals included in the lamp filling and the factors primarily responsible for it are cataphoresis and thermal gradients. The cataphoretic effect is the stronger and the nonuniformity may be overcome by supplying a DC component to the discharge current and controlling its polarity and magnitude. In one system, the lamp is operated from a DC power supply through a control circuit using semi-conductors for polarity reversing switches wherein the time of current flow in one polarity is determined by the direction and degree of unbalance of the spectral output.
Inventors
- 👤 William H Lake
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 21:03
CPC Classifications
H; H05; H05B; H05B41/00; H05B41/14; H05B41/36; H05B41/38; H05B41/39; H05B41/392; H05B41/3921; H05B41/3922; G; G03; G03B; G03B27/00; G03B27/72; G03B27/73
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
81 words
A circuit for overcoming nonuniformity of radiant output along the length of an elongated metal vapor discharge lamp of a kind subject to electrophoretic effects, comprising: a source of electric current and means for connecting the lamp across said source, sensing means responsive to unbalance in spectral output between the ends of said lamp, and control means responsive to said sensing means and providing current through said lamp with a dc component proportioned to create an electrophoretic effect overcoming said unbalance.
Claim 2
Dependent Claim
81 words
A circuit for overcoming nonuniformity of radiant output along the length of an elongated metal vapor discharge lamp of a kind subject to electrophoretic effects, comprising: a source of electric current and means for connecting the lamp across said source, sensing means responsive to unbalance in spectral output between the ends of said lamp, and control means responsive to said sensing means and providing current through said lamp with a dc component proportioned to create an electrophoretic effect overcoming said unbalance.
Claim 3
Dependent Claim
24 words
A lamp as in claim 1 wherein said control means provides cyclic reversals of current through said lamp in addition to said dc component.
Claim 4
Dependent Claim
24 words
A circuit as in claim 1 wherein said sensing means comprises a pair of radiation sensors optically coupled to opposite ends of said lamp.
Claim 5
Dependent Claim
32 words
A circuit as in claim 1 wherein said source provides a controlled dc current and said means for connecting the lamp across said source comprises semiconductor switches controlled by said control means.
Claim 6
Dependent Claim
49 words
A circuit as in claim 1 wherein said source provides a controlled dc current and said means for connecting the lamp across said source comprises a bridge circuit including four semi-conductor switches controlled by said control means in pairs to determine the direction of current flow through said lamps.
Claim 7
Dependent Claim
66 words
A circuit as in claim 1 wherein said sensing means comprises a pair of radiation sensors optically coupled to opposite ends of said lamp, said source provides a controlled dc current, and said means for connecting the lamp across said source comprises a bridge circuit including four semiconductor switches controlled by said control means in pairs to determine the direction of current flow through said lamps.
Claim 8
Dependent Claim
143 words
A circuit for overcoming nonuniformity of radiant output along the length of an elongated metal vapor lamp of a kind subject to electrophoretic effects, comprising: a source of controlled electric dc current, a bridge circuit comprising four semiconductor switches, said source being connected across one diagonal of said bridge, terminals for connecting said lamp across the other diagonal of said bridge, a pair of radiation sensors optically coupled to opposite ends of said lamp and responsive to the unbalance in spectral output therefrom, control means cyclically turning ''''on'''' and ''''off'''' opposite pairs of said switches in order to provide alternating current flow from said source through said lamp, said control means being responsive to the signals from said sensors by varying the time of current flow in any one polarity in accordance with the direction and degree of unbalance in the spectral output.
Claim 9
Dependent Claim
143 words
A circuit for overcoming nonuniformity of radiant output along the length of an elongated metal vapor lamp of a kind subject to electrophoretic effects, comprising: a source of controlled electric dc current, a bridge circuit comprising four semiconductor switches, said source being connected across one diagonal of said bridge, terminals for connecting said lamp across the other diagonal of said bridge, a pair of radiation sensors optically coupled to opposite ends of said lamp and responsive to the unbalance in spectral output therefrom, control means cyclically turning ''''on'''' and ''''off'''' opposite pairs of said switches in order to provide alternating current flow from said source through said lamp, said control means being responsive to the signals from said sensors by varying the time of current flow in any one polarity in accordance with the direction and degree of unbalance in the spectral output.
Claim 10
Dependent Claim
52 words
A circuit as in claim 7 wherein said control means comprises an ac source and an operational amplifier, said operational amplifier providing a square wave output reversing at the frequency of said ac source with a ratio of time duration in opposite polarities following the degree of unbalance in the spectral output.
Claim 11
Dependent Claim
50 words
A circuit as in claim 7 wherein each of the four switches comprises two transistors connected emitter to base with common collectors in the darlington mode, and diodes connecting the bases of said transistors to said control means in order to achieve fast removal of stored carriers at turn off.
Claim 12
Dependent Claim
96 words
A circuit as in claim 7 wherein said control means comprises an ac source and an operational amplifier, said operational amplifier providing a square wave output reversing at the frequency of said ac source with a ratio of time duration in opposite polarities following the degree of unbalance in the spectral output, and each of the four switches comprises two transistors connected emitter to base with common collectors in the darlington mode, and diodes connecting the bases of said transistors to said control means in order to achieve fast removal of stored carriers at turn off.
References Cited (Backward Citations)
US2749501A
Cited
US3431427A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-10-24 | 1976-04-24 | 1976-10-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-24 | 1980-04-24 | 1980-10-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-24 | 1984-04-24 | 1984-10-24 | $7700.00 | Window Closed / Lapsed |