Claims
- 1. An apparatus for starting and operating a high intensity discharge lamp comprising:
- a pair of input terminals for supplying a high frequency voltage to the apparatus,
- a pair of output terminals for connection to a high intensity discharge lamp,
- means including a step-up transformer for coupling said input terminals to said output terminals, and
- a voltage multiplier circuit coupled to a primary winding of said step-up transformer, said voltage multiplier circuit comprising:
- a relatively resistance free impedance means,
- a first capacitor and a first rectifier element connected in a first series circuit with said impedance means to said primary winding,
- a second capacitor and a second rectifier element connected in a second series circuit with said impedance means to said primary winding, and
- a voltage responsive switching device connected in a further closed loop series circuit with the second capacitor and said primary winding, whereby when said second capacitor is charged to the breakdown voltage of the switching device the switching device turns on to provide a rapid discharge path for the second capacitor via said primary winding thereby to induce a high voltage pulse in a secondary winding of the transformer for igniting a discharge lamp connected to said output terminals.
- 2. An apparatus as claimed in claim 1 wherein said switching device comprises a two-terminal semiconductor device through which substantially all discharge current of said second capacitor flows.
- 3. An apparatus as claimed in claim 1 wherein,
- said step-up transformer comprises an autotransformer connected between a first one of said input terminals and one of said output terminals,
- said first series circuit is connected between a tap point on the winding of said autotransformer and a second one of said input terminals, and
- said second series circuit is connected between an end terminal on said winding closest to said one output terminal and said second one of the input terminals.
- 4. An apparatus as claimed in claim 3 wherein said first and second rectifier elements are oppositely polarized as viewed from a common terminal of said impedance means.
- 5. An apparatus as claimed in claim 1 wherein said impedance means comprises an inductor and said step-up transformer has a step-up turns ratio which is at most 8 to 1.
- 6. An apparatus as claimed in claim 1 wherein said second and first capacitors have capacitance values of C.sub.1 and C.sub.2, respectively, and wherein C.sub.1 >>C.sub.2.
- 7. An apparatus as claimed in claim 1 wherein,
- said step-up transformer comprises an autotransformer connected between a first one of said input terminals and one of said output terminals and having a tap point connected to said voltage multiplier circuit, said autotransformer having a winding with an inductance value sufficient to provide a current limiting ballast function for a connected discharge lamp in the normal operating condition of the lamp.
- 8. An apparatus as claimed in claim 1 wherein said switching device comprises a two-terminal semiconductor device having a breakdown voltage that is higher than the operating voltage of a connected discharge lamp thereby to inhibit generation of voltage ignition pulses when a discharge lamp is in normal operation.
- 9. An apparatus as claimed on claim 1 wherein said impedance means comprises an inductor having a winding magnetically coupled to a winding of said step-up transformer.
- 10. An apparatus as claimed in claim 9 wherein said step-up transformer comprises an autotransformer connected between a first one of said input terminals and one of said output terminals and having a tap point that divides a winding thereof into first and second winding sections between the tap point and said first input terminal and said first output terminal, respectively, said first winding section and said inductor winding being wound on a common magnetic core with opposite polarities.
- 11. An apparatus as claimed in claim 9 wherein said switching device comprises a two-terminal semiconductor device and said first and second rectifier elements are oppositely polarized as viewed from a common terminal of said inductor.
- 12. An apparatus as claimed in claim 1 wherein said primary winding and said second capacitor together provide a resonant discharge circuit for the second capacitor in the RF frequency range.
- 13. An apparatus as claimed in claim 1 wherein said input terminals are adapted to be connected to a high frequency transistor inverter and said output terminals are adapted to be connected to a metal halide discharge lamp.
- 14. An apparatus as claimed in claim 1 wherein said first capacitor is part of a common charge path for the second capacitor and provides primary control of the charge rate of the second capacitor.
- 15. An apparatus for starting and operating a high intensity discharge lamp comprising:
- a pair of input terminals for supplying a high frequency voltage to the apparatus,
- a pair of output terminals for connection to a high intensity discharge lamp,
- means including a step-up transformer for coupling said input terminals to said output terminals, and
- a voltage multiplier circuit coupled to a primary winding of said step-up transformer, said voltage multiplier circuit comprising:
- a relatively resistance-free impedance means,
- a first voltage doubler circuit coupled in series with said impedance means between a first terminal of said primary winding and one of said input terminals,
- a second voltage doubler circuit coupled in series with said impedance means between a second terminal of said primary winding and said one input terminal, said first voltage doubler circuit including a first capacitor coupled to said first terminal of the primary winding,
- said second voltage doubler circuit including a second capacitor coupled to said second terminal of said primary winding, and
- a voltage responsive switching device coupling said first and second capacitors and said primary winding in a closed loop circuit whereby when said first and second capacitors are charged to the breakdown voltage of the switching device the switching device turns on to provide a rapid discharge path for the first and second capacitors via said primary winding thereby to induce a high voltage pulse in a secondary winding of the transformer for igniting a discharge lamp connected to said output terminals.
- 16. An apparatus as claimed in claim 15 wherein said first voltage doubler circuit further comprises:
- a first rectifier element and a third capacitor connected in a first series circuit with said first capacitor and said impedance means between said first terminal of the primary winding and said one input terminal, and
- a second rectifier element connected in parallel with a series combination of the first capacitor and the first rectifier element,
- and wherein the second voltage doubler circuit comprises:
- a third rectifier element and a fourth capacitor connected in a second series circuit with said second capacitor and said impedance means between said second terminal of the primary winding and said one input terminal, and
- a fourth rectifier element connected in parallel with a series combination of the second capacitor and the third rectifier element.
- 17. An apparatus as claimed in claim 16 wherein said first and second rectifier elements are oppositely polarized as viewed from a common terminal of said impedance means and likewise for said third and fourth rectifier elements.
- 18. An apparatus as claimed in claim 17 wherein said first and third rectifier elements and said second and fourth rectifier elements, respectively, are oppositely polarized as viewed from said common terminal of said impedance means.
- 19. A switching arrangement for starting a high-pressure discharge lamp comprising a first supply source connection point for connection to a supply source and a first lamp connection point for connection to the high-pressure discharge lamp, an electrical inductor connected between said first supply source connection point and said first lamp connection point, the switching arrangement further comprising a first and a second branch each including a diode and each connected to the inductor, one branch of which is connected to a tap point on the inductor, the two diodes being interconnected by a third branch including a semiconductor switch in a manner such that the third branch is connected at one end directly both to the inductor and the diode of the second branch, wherein the first branch includes a first capacitor connected between the inductor and the third branch and the relevant diode, means connecting the first and the second branch via a common impedance to a second supply source connection pint, said common impedance including a further inductor and a second capacitor, and means coupling a second lamp connection point to said second supply source connection point.
Priority Claims (1)
Number |
Date |
Country |
Kind |
8800952 |
Apr 1988 |
NLX |
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Parent Case Info
This is a continuation-in-part application of U.S. application 334,658, filed Apr. 6, 1989, abandoned.
US Referenced Citations (2)
Foreign Referenced Citations (1)
Number |
Date |
Country |
0195248 |
Sep 1986 |
EPX |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
334658 |
Apr 1989 |
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