High-intensity discharge lamp

摘要

A high-intensity discharge lamp includes an arc tube having a pair of main electrodes, a starting circuit having a thermally-actuated switch for disconnecting the starting circuit, and an outer tube for containing the arc tube and the starting circuit, and the lamp is lighted by means of a reactance ballast. The thermally-actuated switch includes an envelope bulb that covers contacts of the thermally-actuated switch. Thereby, occurrence of sustained arc discharge in the outer tube is prevented in the case of a starting failure or a break-off of the arc tube at the end of the lamp's life.