| 摘要 |
PURPOSE:To provide possibility of sensing any abnormality at the time of dimming by furnishing an abnormality sensing control means, which increases its sensitivity with deepening of the dimming and stops operation of an inverter in the event of abnormality. CONSTITUTION:An abnormality sensing control circuit 6 is composed of an abnormality sensing part 7 to sense abnormality in an inverter 1 or a lamp l, a reference setting part 8 to set the reference voltage in accordance with dim signal, a comparator part 9 to compare the output of the abnormality sensing part 7 with the reference voltage set by this reference setting part 8, and a control part 10 to control operation of the inverter 1 with the output of this comparator part 9. The reference voltage of the comparator circuit 9 is set in accordance with dim signal. Because the sensitivity for abnormality sensing of this abnormality sensing control circuit 6 increases with deepening of the dimming, the dropped portion of the power supplied from a power supply AC at the time of dimming can be compensated by raising this sensitivity. This permits abnormality sensing at the time of dimming in the same manner as in full lighting. |
