Patent ID: 7312586
Filing Date: 2007-12-25
Classification: H05B,Y02B,Y10S

Abstract:
1. A ballast power supply for a high intensity discharge lamp, said ballast power supply comprising: a variable frequency voltage generating circuit for producing a regulated cyclical voltage wherein, after ignition of the lamp, said variable frequency voltage generating circuit operates to vary the frequency of the cyclical voltage over a range of frequencies with a maximum frequency of less than or equal to about 375 kHz; and a resonant circuit coupled to the variable frequency voltage generating circuit; a feedback circuit adapted to provide closed loop control using a sense signal indicative of power being supplied to the lamp; and an inhibit circuit to inhibit the sense signal for a time period following breakdown, the inhibit circuit comprising an RC network that resumes the sense signal, the time period defined by the time constant of the RC network.