Ballast circuit for gas discharge lamps
AssigneeAmerican Electric Cord, Inc.
InventorChen Xiequn
Life of this patent
Estimating the term…
Abstract
A ballast circuit for a gas discharge lamp, having the capability to shift frequency after starting to reduce electromagnetic interference (EMI). Embodiments of the circuit contain an oscillator circuit that generates and supplies an oscillating signal and a time delay circuit, which generates a time delay to signal the oscillator to shift frequency. In embodiments of the circuit, the frequency shift is achieved by selecting different passive components used to generate the oscillator frequency.
Claims18
A circuit for starting and operating a gas discharge lamp, the gas discharge lamp having a natural frequency, comprising:
- a lamp driver circuit;
- an oscillator circuit connected to the lamp driver circuit, the oscillator circuit having a first frequency of operation and a second frequency of operation, wherein oscillator circuit drives the lamp driver circuit at the natural frequency when the oscillator circuit operates at the first frequency, and the oscillator circuit drives the bulb driver circuit at a frequency other than the natural frequency when the oscillator circuit operates at the second frequency;
- and
- a time-delay circuit connected to the oscillator circuit, wherein the time-delay circuit switches the oscillator circuit operation from the first frequency to the second frequency upon a pre-selected time delay from a pre-selected event.
A droplight, comprising:
- a first gas discharge lamp having a natural frequency;
- a case having a cavity adapted to emit light from the first gas discharge lamp;
- a bulb driver circuit;
- an oscillator circuit connected to the bulb driver circuit, the oscillator circuit having a first frequency of operation and a second frequency of operation, wherein oscillator circuit drives the bulb driver circuit at the natural frequency when the oscillator circuit operates at the first frequency, and the oscillator circuit drives the bulb driver circuit at a frequency other than the natural frequency when the oscillator circuit operates at the second frequency;
- and
- a time-delay circuit connected to the oscillator circuit, wherein the time-delay circuit switches the oscillator circuit operation from the first frequency to the second frequency upon a pre-selected time delay from a pre-selected event.
Dependencies are inferred from the claim text.