Circuit designs and control techniques for high frequency electronic ballasts for high intensity discharge lamps
First Claim
1. An electronic high intensity discharge lamp ballast, comprising:
- an inverter circuit and a resonant circuit, wherein at least one ignition capacitor is provided directly between the resonant circuit and the lamp, and said at least one ignition capacitor is immediately across the lamp, and wherein two ignition capacitors are provided in parallel with each other, a first of said ignition capacitors being located physically proximate to said inverter circuit and said resonant circuit, and a second of said ignition capacitors being located proximate the lamp and separated from the first ignition capacitor by a cable.
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Accused Products
Abstract
The present invention provides an electronic ballast for a high intensity discharge lamp such as a metal halide lamp. The ballast includes an inverter and a resonant circuit with an ignition capacitor between the resonant circuit and the lamp. The ignition capacitor serves to provide the necessary start-up energy and also serves to provide a low impedance discharge path. A single ignition capacitor may be sufficient, but if a long cable is used to connect the lamp to the ballast, then two ignition capacitors in parallel at opposite ends of the cable may be used. The ballast further provides means for monitoring and controlling lamp power by monitoring a nominally constant dc link voltage, and means for detecting short-circuit and open circuit conditions. A retrial mechanism is provided in the event of the lamp failing to ignite that includes a temporary disabling of the inverter in order to keep the rms lamp voltage low.
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Citations
13 Claims
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1. An electronic high intensity discharge lamp ballast, comprising:
- an inverter circuit and a resonant circuit, wherein at least one ignition capacitor is provided directly between the resonant circuit and the lamp, and said at least one ignition capacitor is immediately across the lamp, and wherein two ignition capacitors are provided in parallel with each other, a first of said ignition capacitors being located physically proximate to said inverter circuit and said resonant circuit, and a second of said ignition capacitors being located proximate the lamp and separated from the first ignition capacitor by a cable.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
Specification