Claims
- 1. A ballast for a gas discharge lamp having at least one electrode extending and defining an electrically conductive path between a pair of lamp contacts, said ballast comprising:
- a) input means for receiving a source of electrical energy to power said ballast;
- b) ballast means, connected to said input means, for controlling the electrical power supplied to said gas discharge lamp, said ballast means including an isolation transformer coupled to and for electrically isolating a pair of output terminals for connection to the pair of lamp contacts of the gas discharge lamp; and
- c) safety means including means for detecting the presence of a conductive path between said output terminals, to thereby confirm the presence of the discharge lamp and the continuity of the at least one electrode between the lamp contacts, upon initial application of electrical energy to said input means, said detecting means being coupled to said ballast means such that said ballast means does not energize said gas discharge lamp and provides no electrical potential at said output terminals in the absence of a conductive path between said output terminals upon initial application of electrical energy to said input means.
- 2. A ballast according to claim 1, wherein said ballast means includes an inverter which oscillates to energize said gas discharge lamp, and said safety means includes means for preventing said inverter from oscillating until there exists a conductive path between said output terminals.
- 3. A ballast according to claim 2, wherein said input means is receptive of an AC mains voltage and further comprising:
- a power supply stage providing a DC voltage to said inverter with a magnitude substantially higher than the peak of the AC mains voltage supplied at said input means, said power supply stage being coupled to said inverter so that said power supply stage is inoperative whenever the inverter is not oscillating.
Parent Case Info
This is a continuation of application Ser. No. 08/415,020, filed on Mar. 31, 1995 now U.S. Pat. No. 5,650,694.
US Referenced Citations (4)
Continuations (1)
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Number |
Date |
Country |
Parent |
415020 |
Mar 1995 |
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