Patent ID: 7411360
Filing Date: 2008-08-12
Classification: H05B,Y10S

Abstract:
1. A controller for an inverter that powers a fluorescent lamp, the controller comprising: a first input terminal configured to receive a voltage feedback signal indicative of an AC output voltage provided to the fluorescent lamp; a second input terminal configured to receive a current feedback signal indicative of an AC lamp current conducted by the fluorescent lamp, wherein the fluorescent lamp is considered lit when a predetermined number of consecutive periodic cycles in the AC lamp current exceed a predefined amplitude and is otherwise considered unlit during a strike mode to ignite the fluorescent lamp; an output terminal configured to provide a driving signal to a switching circuit that generates the AC output voltage from a DC input source; a strike circuit configured to generate a timing signal based on the voltage feedback signal and the current feedback signal to control a frequency of the driving signal, wherein the timing signal varies the frequency of the driving signal to increase the AC output voltage when the voltage feedback signal indicates that the AC output voltage is less than a predefined striking level and the fluorescent lamp is considered unlit, holds the frequency of the driving signal at a substantially constant strike frequency associated with the AC output voltage reaching the predefined striking level while the fluorescent lamp is considered unlit, and shifts the frequency of the driving signal to a normal operating frequency that is different from the substantially constant strike frequency when the fluorescent lamp is considered lit; and a driver circuit configured to generate the driving signal based at least in part on the timing signal.