| 摘要 |
PROBLEM TO BE SOLVED: To prevent impression of a voltage to a lamp in an emitterless state by furnishing a current shutoff part in a resonance circuit connecting the lamp with a high frequency lighting device, and breaking electrically the connection by this current shutoff part when abnormal temp. is detected in the neighborhood of a lamp electrode. SOLUTION: A lamp 10 has first lamp electrodes 10a and 10b and second lamp electrodes 10c and 10d, which are respectively connected electrically through filaments 10e and 10f, and these lamp electrodes 10a-10d are concentrated in one place by a glass tube corresponding to a discharge tube and surrounded by a base on which a socket is fitted. One end of a coil L2 of a resonance circuit 9 is connected with a high frequency oscillation part 8 through a capacitor C4 for cutting AC component while the other end is connected with a lamp electrode 10a. One end of a capacitor C3 for resonance is connected with the lamp electrode 10b while the other end is connected with the lamp electrode 10d, and the lamp electrode 10c is connected with the high frequency oscillation part 8 through a current shutoff part 11 formed of a thermal fuse. |
