North American Philips Corporation

Daniel H Brownell

Raghu Ramaiah

Dale E Work

Nancy Tillman

A single-ended electric lamp having an alkali-halide containing light source which produces ultraviolet radiation and is supported within an outer envelope by metallic support structure having an elongate support rod extending past the arc tube. A tubular cover extends over a length L1 of the support rod and the remainder of the support structure remains uncovered. A screen is interposed between the light source and an uncovered portion of the metal support structure to prevent ultra-violet radiation emitted from said light source from directly impinging on said uncovered portion. Preferably, a plurality of screens are arranged within the outer envelope to block the line of sight from the light source to any uncovered portion of the metal support structure and to reduce the quantity of reflected ultraviolet radiation reflected off the inner surface of the arc tube which impinges on uncovered portions of the metal support structure. The tubular cover and the interposed screens are comprised of a material substantially opaque to ultraviolet radiation and having a high photoelectric work function. The interposed screen(s) further reduce the production of photoelectrons and substantially reduce the voltage rise of the arc tube over the life of the lamp.

Electric lamp having screens for reducing photo electron emission

The luminous efficacy and color rendering index of a metal halide lamp containing sodium iodide and scandium iodide is increased, and the color correlated temperature is decreased, by the addition of critical amounts of thallium iodide and lithium iodide.

Growing community of inventors

Hornell, NY, United States of America

Daniel H Brownell