| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a lighting device for a discharge lamp with high reliability which detects the end of lifetime of a fluorescent lamp accurately even at the lower limit area of light control regardless of the light control level of the fluorescent lamp, and controls the discharge lamp lighting device into a protection mode. <P>SOLUTION: The lighting device for the discharge lamp has a DC power supply circuit (rectification smoothing circuit 1) to produce DC voltage from an AC power supply Vs, a high frequency conversion circuit 2 which has switching elements Q1, Q2 and an LC series resonance circuit (inductor L1 and capacitor C4) and converts the DC voltage into a high frequency voltage to supply to the fluorescent lamp FL, and a means (current transformer CT) to detect the current flowing to the fluorescent lamp FL. When the current value flowing to the fluorescent lamp FL exceeds a prescribed value, the high frequency conversion circuit 2 is made to stop oscillation. <P>COPYRIGHT: (C)2010,JPO&INPIT |
