Method and apparatus for starting high intensity discharge lamps
AssigneeGTE Laboratories Incorporated
InventorsCharles N. Fallier, Jr., Joseph M. Proud
Life of this patent
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Abstract
A high pressure sodium lamp, which includes a discharge tube enclosing xenon at pressures in excess of 300 torr, is reliably started by the combination of an igniter, a conductor wrapped around the discharge tube, and a switching circuit. The igniter provides periodic pulses of 2500 to 4000 volts with a duration of at least one microsecond. The switching circuit provides a high voltage pulse having an amplitude about equal to the amplitude of the periodic pulses and a duration much greater than the duration of the periodic pulses. The conductor intensifies the electric field within the discharge tube. A conventional lamp ballast provides ac power during starting and normal operation.
Claims24
A light source for use in conjunction with a lamp ballast which provides ac power and which includes an inductive output and an igniter which provides periodic pulses having an amplitude of 2500 to 4000 volts and a duration of at least one microsecond, and periodic pulses being substantially synchronized with peaks of the ac power, said light source comprising:
- a high pressure discharge lamp including a discharge tube having electrodes sealed therein at opposite ends and enclosing a noble gas or mixtures thereof having a pressure of greater than 300 torr;
- a conductor, coupled to one of said electrodes and located in close proximity to an outer surface of said discharge tube;
- and
- pulsing means, having outputs coupled to said electrodes, for generating at said outputs a high voltage pulse having an amplitude about that of said periodic pulses and a duration much greater than that of said periodic pulses,
- whereby, when said light source is coupled to the lamp ballast and to said igniter, said periodic pulses, said conductor, and said high voltage pulse are operative to initiate a discharge in said lamp.
A light source for receiving ac power from a lamp ballast which includes an inductive output, said light source comprising:
- a high pressure discharge lamp including a discharge tube having electrodes sealed therein at opposite ends;
- and
- a starting circuit for initiating discharge in said lamp, said starting circuit including
- first pulsing means, having outputs coupled to said electrodes, for generating at said outputs periodic pulses having an amplitude of 2500 to 4000 volts and a duration of at least one microsecond, said periodic pulses being substantially synchronized with peaks of the ac power,
- a conductor, coupled to one of said electrodes and located in close proximity to an outer surface of the discharge tube, and
- second pulsing means, having outputs coupled to said electrodes, for generating at said outputs a high voltage pulse having an amplitude about that of said periodic pulses and a duration much greater than that of said periodic pulses,
- whereby said periodic pulses, said conductor, and said high voltage pulse are operative to initiate a discharge in said lamp.
A light source comprising:
- a high pressure discharge lamp including a discharge tube having electrodes sealed therein at opposite ends;
- first pulsing means, having outputs coupled to said electrodes, for generating at said outputs periodic pulses having an amplitude of 2500 to 4000 volts and a duration of at least one microsecond;
- a conductor, coupled to one of said electrodes and located in close proximity to an outer surface of the discharge tube;
- second pulsing means, having outputs coupled to said electrodes, for generating at said outputs a high voltage pulse having an amplitude about that of said periodic pulses and a duration much greater than that of said periodic pulses;
- and
- lamp ballast means, coupled to said electrodes, for converting ac input power to a level and impedance suitable for operation of said discharge lamp,
- whereby said periodic pulses, said conductor, and said high voltage pulse are operative to initiate a discharge in said lamp.
A method for initiating discharge in a high pressure discharge lamp which receives ac power from a lamp ballast, said lamp comprising a discharge tube having electrodes sealed therein at opposite ends, said method comprising the steps of:
- supplying to said electrodes periodic pulses having an amplitude of 2500 to 4000 volts and a duration of at least one microsecond, said periodic pulses being substantially synchronized with peaks of the ac power;
- locating a conductor in close proximity to an outer surface of said discharge tube and coupling the conductor to one of said electrodes;
- and
- supplying to said electrodes a high voltage pulse having an amplitude about that of said periodic pulses and a duration much greater than that of said periodic pulses.
Dependencies are inferred from the claim text.