US 4,791,334 AGranted

Metal-halide lamp having heat redistribution means

AssigneeGTE Products Corporation

InventorsWilliam M. Keeffe, Zeya Krasko, Robert Karlotski, James C. Morris

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Abstract

An improved metal-halide arc discharge lamp includes an arc tube having a substantially cylindrical body surrounded laterally by a substantially cylindrical heat-conserving sleeve within an evacuated outer envelope. The ratio of the outer radius of the arc tube divided by the inner radius of the sleeve falls within an optimum range of approximately 0.54 to approximately 0.68, and preferably within a range of approximately 0.60 to approximately 0.63. A lamp constructed in accordance with the invention exhibits improved luminous efficacy and color rendering in comparison to prior art counterparts. The improved performance is believed to be attributable to the more nearly isothermal operation of the arc tube for a given wall loading.

Claims10

Dependent claims

In a metal-halide arc discharge lamp having:

(a) a hermetically sealed outer envelope having a longitudinal axis;
(b) an arc tube mounted within said outer envelope, said arc tube having a substantially cylindrical body about said longitudinal axis and at least one end, said body enclosing an interior containing a gaseous fill and a metal-halide additive, said body having an outer radius, r;
(c) a substantially cylindrical light-transmissive enclosure mounted within said outer envelope about said longitudinal axis and surrounding said arc tube, said enclosure having an inner radius, R;
(d) a vacuum within said outer envelope;
and
(e) means for mounting said arc tube and said enclosure;
the improvement comprising in combination:
(f) the ratio r/R being greater than approximately 0.60 and less than approximately 0.63.

5 more elements

Dependencies are inferred from the claim text.