Compact high-pressure discharge lamp with a fill including cadmium and lithium halide

US4686419A · kind A · utility

Assignee

• Patent-Treuhand-Gesellschaft fur elektrische Gluhlampen mbH · DE

Inventors

• Werner Block · Taufkirchen, DE
• Wolfgang Pabst · Munich, DE
• Manfred Pilsak · Munich, DE

Key dates

• Filing date: Feb 13, 1986
• Grant date: Aug 11, 1987
• Expiry date: Feb 13, 2006

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01J61/827
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

A metal halide high-pressure discharge lamp has a discharge vessel of comt construction, with a fill of mercury, at least one noble gas, typically argon, and a metal halide, with an excess of halogen. The halogen component of the metal halide is formed by iodine and/or bromine. An average light density in excess of 30 ksb, with a specific arc power of between 400 to 5000 W/cm is obtained over an average lifetime of 250 hours with a color rendering index Ra of at least 85 by utilizing cadmium and lithium as the metal component in the metal halide of the fill. Preferably, holmium also is used as a metal for the metal halide, the fill including between 0.1 and 5 mg cadmium, up to 0.05 mg lithium, and 0.05 to 1 mg holmium in a preferred form, halogen and bromine being present in a mol relation of between 0.5 to 2 within the discharge vessel. The excess halogen may be up to about 35 micromol per cubic centimeter of volume of the discharge vessel. The lamp is particularly suitable for optical projection systems, for example for combination with a reflector (13).