| 摘要 |
PURPOSE:To improve the starting characteristic and avoid hazard in lighting-up by furnishing a grounding changeover control means for a reflex plate, grounding at the time of starting, and releasing the grounding during lighting-up. CONSTITUTION:An AC power supply 11 is rectified by a whole-wave rectifier circuit 12, and a capacitor C4 is gradually charged through a resistance R1. The charging voltage of this capacitor C4 is divided by resistances R2, R3 to provide a base voltage for a transistor Q2. As the base voltage becomes higher, the transistor Q2 is turned on, and a switching transistor Q1 in a transistor inverter is oscillated, and a discharge lamp 13 is started and lit. At this time, a control relay Ry18 of a grounding changeover control means 19 in parallel connection with the capacitor C4 is turned off, and the contact 17 is in closed state, and a reflex plate 15 is grounded. During lighting-up after completion of the start, the resistance of the capacitor C4 is raised sufficiently, and the Ry18 is turned on while the contact 17 turned off, and thus grounding of the reflex plate 15 is released. Thus the discharge lamp can be lighted with good starting characteristic, and during lighting-up there is no hazard for electric shock, etc. |
