Westinghouse Electric Corporation

North American Philips Lighting Corp.

North American Philips Electric Corp.

Ranbir S Bhalla

Robert Tracy Elms

Vernon L Plagge

Jose E Tallet

Sintering aids are disclosed which improve the sintering of emission materials in high pressure discharge lamps. The sintering aid is Nb.sub.2 O.sub.5 or Ta.sub.2 O.sub.5 or a mixture thereof along with an alkaline earth oxide with is mixed in the amount of 2 to 15 weight percent sintering aid with 98 to 85 weight percent electron emissive material.

High intensity vapor discharge lamp with sintering aids for electrode

High-pressure-sodium HID lamps characteristically display an increasing operating voltage throughout life. The industry has established operating standards as a trapezoidal figure on a graph wherein lamp wattage is plotted on the axis of ordinates and lamp voltage is plotted on the axis of abscissas. The parallel trapezoid sides represent minimum permissible and maximum permissible operating lamp wattages and the remaining sides of the trapezoidal figure are two lines of sharply rising positive slope which represent minimum permissible and maximum permissible lamp voltages. The lamp-life operating characteristics are describable by a curve which enters into the trapezoid through the line representing minimum lamp voltages and which exits from the trapezoid through the line representing maximum lamp voltages. To minimize lamp voltage variations throughout normally anticipated life, the lamp is initially operated for a relatively short period of time until the operating voltage is a predetermined value and the wattage consumption is relatively high as compared to the minimum value. Thereafter, the lamp is operated so that the operating characteristic curve of lamp wattage consumption versus increasing lamp operating voltage displays a slope which is negative in nature and which does not exceed an operating wattage drop of about 1.5 percent per one volt increase in lamp operating voltage. Thereafter, the lamp is operated in such manner that the characteristic operating curve ultimately exits from the trapezoidal figure proximate the lower right-hand portion thereof.

Method of operating HID sodium lamp to minimize lamp voltage variation

An arc tube for a high-pressure sodium (HPS) discharge lamp having an extended seal path to reduce leakage therethrough. The extended seal path is provided by a monolithic arc tube body having circular apertures in the ends thereof of a substantially smaller diameter than the diameter of the arc tube body and a skirted end cap having refractory metal tubulation extending centrally therethrough mounted on each end of the arc tube body. A glassy sealing frit is interposed between the entire interior surface of the end cap and that portion of the refractory metal tubulation extending through the circular aperture in the arc tube ends.

Arc tube construction

For HID lamps, and particularly high-pressure mercury or sodium-mercury HID lamps, the electron-emissive material portion of the lamp electrodes is Ba.sub.3 CaM.sub.2 O.sub.9 wherein M is niobium, tantalum or any combinations thereof. The specified material is highly emissive, very refractory, and essentially completely non-reactive with respect to moisture.

HID Lamp electrode comprising barium-calcium niobate or tantalate

An improved arc tube end seal and the method of forming that seal in a high pressure sodium discharge lamp is disclosed. The method includes precoating the refractory metal end cap with a slurry of a mixture of refractory metal powder and powdered metallic silicon and baking the end cap prior to accomplishing the bonding of the end cap to the arc tube with a conventional sealing frit.

Arc discharge tube end seal

A high-pressure sodium vapor discharge lamp of improved color including in combination a specified arc length to power input, a predetermined sodium to mercury amalgam ratio, heat shields surrounding each end of the arc tube and an improved end cap to arc tube seal, which combine to increase the sodium vapor pressure and provide a lamp of greatly improved color.

Color high-pressure sodium vapor lamp

An improved composite emission material for use in the electrodes of high intensity (HID) lamps comprising a reacted mixture of barium zirconate and strontium zirconate wherein the ratio of barium to strontium is from between 9:1 to 1:1 and is preferably 4:1. The improved emission material has a lower vapor pressure, higher melting point and a reduced processing time as compared to prior art emission materials.

HID Lamp emission material

An improved arc tube end seal and the method of forming that seal in a high pressure sodium discharge lamp is disclosed. The method includes precoating the refractory metal end cap with a slurry of metallic silicon and baking the end cap prior to accomplishing the bonding of the end cap to the arc tube with a conventional sealing frit.

Method of forming arc tube end seal

For HID lamps, and particularly high-pressure mercury or sodium-mercury HID lamps, the electron-emissive material portion of the lamp electrodes is M.sub.3 M'.sub.2 M'O.sub.9 wherein M is alkaline-earth metal and at least principally comprises barium; M' is yttrium, a lanthanoid series metal, or any mixtures thereof; and M' is tungsten, molybdenum, or mixtures thereof. The specified material is very stable and highly emissive.

HID lamp electrode comprising barium (yttrium or rare earth metal)

Sintering aids are disclosed which inprove the sintering of emission materials in high pressure discharge lamps. The sintering aid is a eutectic composition of at least one of barium oxide-tungsten oxide (BaO--WO.sub.3), calcium oxide-tungsten oxide (CaO--WO.sub.3), or strontium oxide-tungsten oxide (SrO--WO.sub.4)and is mixed with the emission material in quantities of about 2 to 50 wt.% sintering aid and 50 to 98% emission material. Preferably, the sintering aid is present at between about 5 and 10 wt.%.

For HID lamps, and particularly high-pressure sodium-mercury HID lamps, the electron-emissive material portion of the lamp electrodes is a solid solution of dibarium calcium tungstate and dibarium calcium molybdate wherein the molar ratio of tungstate to molybdate is from 9:1 to 1:9. Emissive properties of the electrode are good and vapor pressure of emissive material is low.

Growing community of inventors

West Paterson, NJ, United States of America

Ranbir S Bhalla