DISCHARGE LAMP WITH MOUNT PROVIDING SELF CENTERING AND THERMAL EXPANSION COMPENSATION

摘要

DISCHARGE LAMP WITH MOUNT PROVIDING SELF CENTERING AND THERMAL EXPANSION COMPENSATION A high pressure sodium vapor discharge lamp having an arc tube coaxially mounted within an outer glass envelope by means including a coiled spring engaging one end of the arc tube and coaxially disposed in the partially compressed state between that end of the arc tube and a dome portion of the outer envelope. In one embodiment the dome of the outer envelope is disk-shaped and a large diameter end of the coiled spring bearing against the dome is constrained in a coaxially centered position by the sidewalls of the outer envelope. In another embodiment, the dome of the outer envelope is provided with an inwardly projecting dimple about which the coiled spring is coaxially fitted to provide self-centering of the arc tube. The partially compressed spring compensates for arc tube length variations and thermal expansion. Mount shadows are reduced by connecting the remote terminal of the arc tube to a lead-in conductor through a fine diameter helically bent wire extending through the outer envelope beyond the length of the arc tube.