Patent EP0124735A1 successfully refreshed from Google Patents.
EP0124735A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Operating circuit for electric discharge lamp
Assignee: Toshiba Corp
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Filing: 1984-03-22
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Granted: —
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Expires: 2004-03-22
Abstract
Abstract There is disclosed an operating circuit for an electric discharge lamp in which a first DC operating circuit (26) for starting an electric discharge lamp (32), a second DC operating circuit (28) for making the electric discharge lamp operative by a voltage near a rated lamp voltage and by a current near a rated lamp current, and a third DC operating circuit (30) for supplying a relatively large current to the electric discharge lamp immediately after the electric discharge lamp is started and for stabilizing the lamp luminous flux in a short time. are connected in parallel. A switching circuit (62) for cutting off the first DC operating circuit after the electric discharge lamp is started is provided atthe outputterminal of the first DC operating circuit. In addition, reverse current preventing circuits (66, 68) for preventing the currents from reversely flowing from the operating circuits at higher voltages are provided at the output terminals of the second and third DC operating circuits.
Inventors
- 👤 Mitsutoshi Kimura
- 👤 Masayuki Morita
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 19:42
CPC Classifications
H; H05; H05B; H05B41/00; H05B41/14; H05B41/36; H05B41/38; H05B41/382; H05B41/388
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
248 words
Operating circuit for an electric discharge lamp characterized by comprising: first DC operating means (26) for supplying a DC output voltage higher than a rated lamp voltage to said electric discharge lamp (32) to start the electric discharge lamp and for making the electric discharge lamp operative by a current smaller than a rated lamp current; second DC operating means (28), connected in parallel to said first DC operating means, for making said electric discharge lamp operative by a voltage near the rated lamp voltage and by a current near the rated lamp current; third DC operating means (30), connected in parallel to said first and second DC operating means, for making the electric discharge lamp operative by a current larger than said rated lamp current when the electric discharge lamp has a lamp voltage lower than the rated lamp voltage; switching means (62, 64) for detecting the predetermined electrical characteristic of the electric discharge lamp after the electric discharge lamp has started, and for cutting off said first DC operating means from the electric discharge lamp; first reverse current preventing means (66), connected in series to said second DC operating means, for preventing the current from reversely flowing from said first DC operating means to said second DC operating means; and second reverse current preventing means (68), connected in series to said third DC operating means, for preventing the currents from reversely flowing from said first and second DC operating means to said third DC operating means.
Claim 2
Dependent Claim
248 words
Operating circuit for an electric discharge lamp characterized by comprising: first DC operating means (26) for supplying a DC output voltage higher than a rated lamp voltage to said electric discharge lamp (32) to start the electric discharge lamp and for making the electric discharge lamp operative by a current smaller than a rated lamp current; second DC operating means (28), connected in parallel to said first DC operating means, for making said electric discharge lamp operative by a voltage near the rated lamp voltage and by a current near the rated lamp current; third DC operating means (30), connected in parallel to said first and second DC operating means, for making the electric discharge lamp operative by a current larger than said rated lamp current when the electric discharge lamp has a lamp voltage lower than the rated lamp voltage; switching means (62, 64) for detecting the predetermined electrical characteristic of the electric discharge lamp after the electric discharge lamp has started, and for cutting off said first DC operating means from the electric discharge lamp; first reverse current preventing means (66), connected in series to said second DC operating means, for preventing the current from reversely flowing from said first DC operating means to said second DC operating means; and second reverse current preventing means (68), connected in series to said third DC operating means, for preventing the currents from reversely flowing from said first and second DC operating means to said third DC operating means.
Claim 3
Dependent Claim
34 words
Operating circuit for an electric discharge lamp according to claim 1, characterized in that said switching means (62) is a relay circuit which operates when said electric discharge lamp reaches a predetermined lamp voltage.
Claim 4
Dependent Claim
38 words
Operating circuit for an electric discharge lamp according to claim 1, characterized in that said switching means (62) is a relay circuit which operates in response to a predetermined lamp current which flows through said electric discharge lamp.
Claim 5
Dependent Claim
24 words
Operating circuit for an electric discharge lamp according to claim 1, characterized in that said first and second reverse current preventing means are diodes.
Claim 6
Dependent Claim
32 words
Operating circuit for an electric discharge lamp according to claim 1, characterized in said switching means is an electronic circuit which operates when said electric discharge lamp reaches a predetermined lamp voltage.
Claim 7
Dependent Claim
36 words
Operating circuit for an electric discharge lamp according to claim 1, characterized in said switching means is an electronic circuit which operates in response to a predetermined lamp current which flows through said electric discharge lamp.
References Cited (Backward Citations)
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