| 摘要 |
PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device capable of detecting non-mounting of a discharge lamp with reliability. SOLUTION: When fluorescent lamps FL1, FL2 are properly mounted, a current flows through a circulation circuit 28. A voltage V2 is generated at a resistance R18. Since a Zener diode ZD1 maintains a reverse-blocking state, a gate voltage of a field-effect transistor Q3 is applied as it is to maintain the ON/OFF state. An inverter circuit 25 thus continues the operation. When the fluorescent lamp FL1 is not properly mounted, a circulation circuit 27 is not formed and a voltage V1 is generated at the resistance R18. The Zener diode ZD1 is turned on, and then transistors Q4, Q5 are turned on so as not to turn on the field-effect transistor Q3. Oscillation of the inverter circuit 25 is thereby stopped. COPYRIGHT: (C)2005,JPO&NCIPI |
