| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-pressure sodium lamp, in which a small-sized and inexpensive ballast can be utilized and which can be surely restarted at the time of instantaneous interruption to service, and provide a high-pressure sodium lamp lighting device and a lighting system. SOLUTION: A high-presure sodium lamp 1 includes an outer tube 4, a pair of light emitting tubes 5a, 5b, a starter 6 and a base 7. The pair of light emitting tubes 5a, 5b are connected in parallel with each other in the outer tube 4. Proximity conductors 9a, 9b are fixed to the corresponding light emitting tubes 5a, 5b. The starter 6 is provided with a thermally actuated switch and a heater, and connected in parallel with the light emitting tubes 5a, 5b. When an instantaneous interruption to service is generated, since the light emitting tube 5a, which has been lighted till the generation of interruption to service, is extinguished, the high-pressure sodium lamp 1 is extinguished. Temperature of the thermally actuated switch of the starter 6 is raised and the switch is in an opened state, but since a bimetal is adjusted for re-setting after two or three minutes, high-voltage is generated after two or three minutes. |
