Method of Controlling an Electronic Dimming Ballast During Low Temperature Conditions
First Claim
1. A method of driving a gas discharge lamp comprising the steps of:
- generating a high-frequency output voltage having an operating frequency;
adjusting the operating frequency so as to control an intensity of the lamp between a minimum intensity and a maximum intensity;
generating a temperature control signal representative of a lamp temperature of the lamp;
determining if the lamp temperature of the lamp is below a cold temperature threshold; and
increasing the minimum intensity of the lamp if the lamp temperature of the lamp is below the cold temperature threshold.
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Accused Products
Abstract
An electronic ballast circuit for driving a gas discharge lamp is operable to control the lamp to avoid flicking and flashing of the intensity of the lamp during low temperature conditions. The ballast circuit includes an inverter circuit for receiving a DC bus voltage and for generating a high-frequency output voltage, a resonant tank circuit for receiving the high-frequency output voltage and generating a sinusoidal voltage for driving said lamp, and a control circuit operatively coupled to the inverter circuit for adjusting an intensity of the lamp between a minimum intensity and a maximum intensity. The control circuit receives a control signal representative of a lamp temperature of the lamp, and increases the minimum intensity of the lamp if the lamp temperature of the lamp drops below a cold temperature threshold. In addition, the ballast circuit may also include a temperature sensing circuit operable to generate the control signal representative of the lamp temperature of the lamp.
10 Citations
17 Claims
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1. A method of driving a gas discharge lamp comprising the steps of:
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generating a high-frequency output voltage having an operating frequency; adjusting the operating frequency so as to control an intensity of the lamp between a minimum intensity and a maximum intensity; generating a temperature control signal representative of a lamp temperature of the lamp; determining if the lamp temperature of the lamp is below a cold temperature threshold; and increasing the minimum intensity of the lamp if the lamp temperature of the lamp is below the cold temperature threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An electronic ballast circuit for driving a gas discharge lamp, the ballast circuit comprising:
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an inverter circuit for receiving a DC bus voltage and for generating a high-frequency output voltage; a resonant tank circuit for receiving the high-frequency output voltage and generating a sinusoidal voltage for driving said lamp; and a control circuit operatively coupled to the inverter circuit for adjusting an intensity of the lamp between a minimum intensity and a maximum intensity, the control circuit operable to receive a control signal representative of a lamp temperature of the lamp, the control circuit operable to increase the minimum intensity of the lamp if the lamp temperature of the lamp drops below a cold temperature threshold. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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Specification