Method and system for driving a plasma-based light source

• US 20050134198A1
• Filed: 11/24/2004
• Published: 06/23/2005
• Est. Priority Date: 11/25/2003
• Status: Active Grant

• Current Assignee: PureSpectrum Incorporated
• Original Assignee: Transworld Lighting, Inc.
• Inventors: King, Ray, Smallwood, Robert C., Crandall, Earl F.
• Granted Patent: US 7,514,879 B2
• Time in Patent Office: Days
• US Class Current: 315/291
• CPC Class Codes: H05B 41/2821 by means of a single-switch converter or a parallel push-pull converter in the final stage H05B41/285 takes precedence

Abstract

A gas discharge lamp is driven with a constant current square wave from a current transformer where the number of volt-microseconds are designed such that at the start of each square wave, the voltage rises to the required ionization potential for the lamp, while the plasma has not yet started to conduct. As soon as the lamp ionizes the gas within the lamp and current flows, the voltage drops and current flows at the desired level. The current level is set to prevent the input of excessive power pulses into the lamp, to reduce the creation of infrared photons. In addition, the plasma is driven at this current level almost continuously (with reversing polarity), which does not allow the plasma time to cool down. Consequently, the lamp becomes a more efficient light emitter, thereby requiring less energy to achieve the same light output.

Claims

1. A method of driving a plasma-based light source, comprising the following steps:

applying a constant current square wave to plasma in the light source; and

maintaining a current level of the constant current square wave to obtain a temperature of the plasma that maximizes the release of light in the visible and UV light spectrums.

2. A system for driving a plasma-based light source, comprising:

a switching circuit that applies a constant current square wave to plasma in the light source; and

a current source that maintains the current level of the constant current square wave at a level to obtain a temperature of the plasma that maximizes the release of light in the visible and UV light spectrums.

3. The system of claim 2, wherein said switching circuit comprises a push-pull circuit.

4. The system of claim 2, wherein said current source includes a pulse-width modulated synchronous buck converter.

5. The system of claim 2, further including a current sensor for providing current feedback information from said switching circuit to said switching circuit to maintain a constant current level.

6. A system for driving a plasma-based light source, comprising:

means for applying a constant current square wave to plasma in the plasma-based light source; and

means for providing the sufficient ignition voltage to ionize the plasma in the plasma-based light source.