| 摘要 |
PURPOSE:To prevent the thermal breakdown of a halogen lamp for exposing originals by detecting the overheating of the halogen lamp quickly with a thermal protector in the event of a fault in a driving circuit for said lamp and interrupting the electric power to be supplied to the halogen lamp. CONSTITUTION:A halogen lamp 1 heats up of itself even if it operates on a rated voltage. When the main electrodes T1 and T2 of a triac 4 conduct on account of overlapping of external noises, etc., the lamp 1 is fully lighted and begins to evolve heat abnormally. If the working temp. of a thermal protector 3 is beforehand set, the protector 3 senses the self-heating and the atmospheric temp. sensibly, and interrupts the lamp 1, thereby stopping the electric power to be supplied to the lamp 1. When the protector is opened, the circuit is not closed until the set temp. set lower than the working temp. is attained. The thermal breakdown of the lamp is thus prevented, and the labor for changing a temperature fuse at every interruption is omitted. |
