Inverter control method for electronic ballasts
First Claim
1. A method of controlling an inverter in an electronic ballast for powering at least one gas discharge lamp, wherein the lamp has a pair of filaments and the inverter is operable to drive a resonant output circuit at a drive frequency, the method comprising the steps of:
- (A) preheating the lamp filaments by setting the drive frequency at a preheat frequency for a predetermined preheating period;
(B) shifting the drive frequency from the preheat frequency to an operating frequency;
(C) powering the lamp by maintaining the drive frequency at the operating frequency in response to ignition and normal operation of the lamp within a predetermined ignition period, followed by continued normal operation of the lamp after ignition;
(D) repeating the steps of preheating the lamp filaments and shifting the drive frequency up to a predetermined number of times in response to each of;
(i) failure of the lamp to ignite and operate normally within the predetermined ignition period when both lamp filaments are intact and properly connected to the ballast; and
(ii) failure of the lamp to continue to operate normally after igniting; and
(E) protecting the inverter by setting the drive frequency to the preheat frequency in response to each of;
(i) removal of the lamp; and
(ii) failure of the lamp to ignite and operate normally within the predetermined ignition period after the step of repeating has been carried out the predetermined number of times.
3 Assignments
0 Petitions
Accused Products
Abstract
A method (100) of controlling an inverter in an electronic ballast for at least one gas discharge lamp protects the inverter from damage due to lamp fault conditions, and provides enhanced noise immunity and multiple ignition attempts for low-temperature lamp starting. The method (100) includes repeating a filament preheating step and a frequency shifting step up to a predetermined number of times in order to facilitate lamp ignition under low-temperature conditions and to verify the legitimacy of a detected lamp fault.
69 Citations
18 Claims
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1. A method of controlling an inverter in an electronic ballast for powering at least one gas discharge lamp, wherein the lamp has a pair of filaments and the inverter is operable to drive a resonant output circuit at a drive frequency, the method comprising the steps of:
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(A) preheating the lamp filaments by setting the drive frequency at a preheat frequency for a predetermined preheating period; (B) shifting the drive frequency from the preheat frequency to an operating frequency; (C) powering the lamp by maintaining the drive frequency at the operating frequency in response to ignition and normal operation of the lamp within a predetermined ignition period, followed by continued normal operation of the lamp after ignition; (D) repeating the steps of preheating the lamp filaments and shifting the drive frequency up to a predetermined number of times in response to each of; (i) failure of the lamp to ignite and operate normally within the predetermined ignition period when both lamp filaments are intact and properly connected to the ballast; and (ii) failure of the lamp to continue to operate normally after igniting; and (E) protecting the inverter by setting the drive frequency to the preheat frequency in response to each of; (i) removal of the lamp; and (ii) failure of the lamp to ignite and operate normally within the predetermined ignition period after the step of repeating has been carried out the predetermined number of times. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of controlling an inverter in an electronic ballast for powering at least two gas discharge lamps, wherein each lamp has a pair of filaments and the inverter is operable to drive a resonant output circuit at a drive frequency, the method comprising the steps of:
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(A) preheating the lamp filaments by setting the drive frequency at a preheat frequency for a predetermined preheating period; (B) shifting the drive frequency from the preheat frequency to an operating frequency; (C) powering the lamps by maintaining the drive frequency at the operating frequency in response to ignition and normal operation of all of the lamps within a predetermined ignition period, followed by continued normal operation of all of the lamps after ignition; (D) repeating the steps of preheating the lamp filaments and shifting the drive frequency up to a predetermined number of times in response to each of; (i) failure of at least one of the lamps to ignite and operate normally within the predetermined ignition period when all lamp filaments are intact and properly connected to the ballast; and (ii) failure of at least one of the lamps to continue to operate normally after igniting; (E) protecting the inverter by setting the drive frequency to the preheat frequency in response to at least one of the lamps failing to ignite and operate normally within the predetermined ignition period after the step of repeating has been carried out the predetermined number of times. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A method of controlling an inverter in an electronic ballast for powering at least two gas discharge lamps, wherein each lamp has a pair of filaments, the inverter is operable to drive a resonant output circuit at a drive frequency, the inverter includes a timer and a counter having a count, the method comprising the steps of:
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(A) preheating the lamp filaments by setting the drive frequency at a preheat frequency for a predetermined preheating period; (B) shifting the drive frequency from the preheat frequency to an operating frequency; (C) powering the lamps by maintaining the drive frequency at the operating frequency in response to ignition and normal operation of all of the lamps within a predetermined ignition period, followed by continued normal operation of all of the lamps after ignition; (D) repeating the steps of preheating the lamp filaments and shifting the drive frequency up to a predetermined number of times in response to each of; (i) failure of at least one of the lamps to ignite and operate normally within the predetermined ignition period when all lamp filaments are intact and properly connected to the ballast; and (ii) failure of at least one of the lamps to continue to operate normally after igniting; (E) protecting the inverter by setting the drive frequency to the preheat frequency in response to at least one of the lamps failing to ignite and operate normally within the predetermined ignition period after the step of repeating has been carried out the predetermined number of times, and then maintaining the drive frequency at the preheat frequency until at least such time as all failed lamps are replaced with functional lamps or the power to the ballast is removed; (F) incrementing the count by one upon completion of the step of preheating the lamp filaments; (G) determining if the count has reached a predetermined count limit and, in response to the count reaching the predetermined count limit, carrying out the step of protecting the inverter; (H) initializing the counter in response to each of; (i) initial application of power to the ballast; (ii) cycling of the power applied to the ballast; (iii) disconnection of at least one of the lamps from the ballast; and (iv) ignition and normal operation of all of the lamps within the predetermined ignition period; and (I) initializing the timer in response to each of; (i) initial application of power to the ballast; (ii) cycling of the power applied to the ballast; (iii) disconnection of at least one of the lamps from the ballast; (iv) failure of at least one of the lamps to ignite and operate normally within the predetermined ignition period; and (v) failure of at least one of the lamps to continue to operate normally after igniting.
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Specification