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1. (WO1985004545) BALLAST AND CONTROL UNIT FOR ELECTRIC DISCHARGE LAMP
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I CLAIM:
1. An electronic ballast and control unit for use in connecting electric discharge lamps to a power source, said unit comprising:
(a) input means for connecting to said power source;
(b) output means for connecting to at least one said lamp;
(c) heater means for supplying heater voltage to said lamp;
(d) lamp current sensing means for sensing a flow of current through said lamp; and
(e) heater control means responsive to said lamp current sensing means for turning said heater means off in response to a flow of current through said lamp.
2. The unit of Claim 1 wherein said heater control means will turn said heater means off in response to sensing at least a minimum threshold level flow of current through said lamp.
3. The unit of Claim 1 wherein a delay period is provided following a sensing of a flow of current through said lamp by said lamp current sensing means before said heater control means turns said heater means off.
4. A ballast and control unit for use in
connecting at least two series connected electric discharge lamps to a power source, said unit
comprising:
(a) input means for connection to said power source;
(b) output means for connection to said lamps;

(c) lamp current sensing means for sensing a flow of current through said lamps;
(d) starting circuit means for selectively disconnecting power from all but one of said lamps such that all of said power becomes applied to said lamp to facilitate starting said lamps, said starting circuit means being responsive to said lamp current sensing means such that said starting circuit means will be disabled when at least a threshold amount of current flows through said lamps.
5. The unit of Claim 4 wherein said starting circuit means alternates between disconnecting power from all but one of said lamps such that all of said power becomes applied to said lamp, and connecting power to all of said lamps such that all of said power becomes applied to all of said lamps.
6. The unit of Claim 5 wherein said starting circuit means is responsive to the cyclical nature of input power as provided through said input means such that the alternation of applying power to first one of said lamps and then all of said lamps occurs in coordination with said cyclical changes of power input.
7. A ballast and control unit for use in
connecting at least one electric discharge lamp to a power source, said ballast comprising:
(a) input means for connection to said power source;
(b) output means for connection to at least one said lamp;
(c) lamp sensing means for sensing when said lamp becomes electrically disconnected and for producing a disconnection signal in response thereto.

8. Theunit of Claim 7 and further including current limit means responsive to said disconnection signal for limiting a magnitude of current that can flow through said output means when said disconnection signal is present.
9. The unit of Claim 8 wherein said current limit means so limits said output means by limiting total available voltage to said output means.
10. The unit of Claim 7 wherein said lamp sensing means senses heater current.

AMENDED CLAIMS
[received by the International Bureau on 26 August 1985 (26.08.85);
original claims 2 and 3 cancelled; claim 1 amended, other claims renumbered (2 pages)]
1. (as amended) An electronic ballast and control unit for use in connecting electric discharge lamps to a power source, said unit comprising:
(a) input means for connecting to said power source;
(b) output means for connecting to at least one said lamp;
(c) heater means for supplying heater voltage to said lamp;
(d) lamp current sensing means for sensing a flow of current through said lamp; and
(e) heater control means responsive to said lamp current sensing means for turning said heater means off, following a delay period, in response to sensing at least a minimum threshold level flow of current through said lamp.
2. (previously claim 4) A ballast and control unit for use in connecting at least two series connected electric discharge lamps to a power source, said unit comprising:
(a) input means for connection to said power source;
(b) output means for connection to said lamps;
(c) lamp current sensing means for sensing a flow of current through said lamps;
(d) starting circuit means for selectively disconnecting power from all but one of said lamps such that all of said power becomes applied to said lamp to facilitate starting said lamps, said starting circuit means being responsive to said lamp current sensing means such that said starting circuit means will be disabled when at least a threshold amount of current flows through said lamps.
3. (previously claim 5) The unit of Claim 2 wherein said starting circuit means alternates between disconnecting power from all but one of said lamps such that all of said power becomes applied to said lamp, and connecting power to all of said lamps such that all of said power becomes applied to all of said lamps.
4. (previously claim 6) The unit of Claim 3 wherein said starting circuit means is responsive to the cyclical nature of input power as provided through said input means such that the alternation of applying power to first one of said lamps and then all of said lamps occurs in coordination with said cyclical changes of power input.
5. (previously claim 7) A ballast and control unit for use in connecting at least one electric
discharge lamp to a power source, said ballast
comprising:
(a) input means for connection to said power source;
(b) output means for connection to at least one said lamp;
(c) lamp sensing means for sensing when said lam becomes electrically disconnected and for producing a disconnection signal in response thereto.
6. (previously claim 8) The unit of Claim 5 and further including current limit means responsive to said disconnection signal for limiting a magnitude of current that can flow through said output means when said disconnection signal is present.
7. (previously claim 9) The unit of Claim 6 wherein said current limit means so limits said output means by limiting total available voltage to said output means.
8. (previously claim 10) The unit of Claim 5 wherein said lamp sensing means senses heater current.