KR100548808B1 - Long life halogen cycle incandescent lamp and glass envelope composition - Google Patents

Abstract

Long life halogen cycle incandescent lamps (30) for operation above 85 v. The lamp comprises a transparent glass envelope 34 with a tungsten filament 45 sealed therein; A pair of electrical lead wires 42, 44 connecting the filaments and extending out of the envelope for connection with a supply voltage of at least 85 v; And a filling gas in the envelope containing halogen, which is at least 3 atmospheres pressure. The envelope is essentially, in weight percent,> 58 to about 64% SiO ₂ , about 14 to about 17% Al ₂ O ₃ ; 5-component alkaline earth alumino having a composition consisting of 0 to about 1% B ₂ O ₃ , 1 to about 6% MgO, about 6 to about 12% CaO, about 7 to about 17% BaO, and 0 to about 1.5% ZrO ₂ Made of silicate glass.

Halogen Lamp, Alkaline Earth Aluminosilicate Glass

Description

LONG LIFE HALOGEN CYCLE INCANDESCENT LAMP AND GLASS ENVELOPE COMPOSITION}

This application is incorporated by reference in U.S. Provisional Application No. 60 / 058,712, filed Sep. 12, 1997; 08 / 948,565, filed October 10, 1997; And German application 197 47 355.5, filed October 27, 1997.

The present invention relates to a lamp, more particularly to an incandescent halogen lamp. More specifically, the present invention relates to glass for envelopes of halogen lamps.

Lamps operating by tungsten-halogen cycles are known. In operation, tungsten-halogen lamps contain non-reactive fillers, such as neon, nitrogen, argon, krypton or xenon or combinations thereof, with halogens, typically bromine, which combine with evaporated tungsten leaving the incandescent filaments. An equilibrium concentration is achieved by the gas species in the lamp between the temperature limits defined by the incandescent filament and the lowest temperature point in the lamp envelope. The cold spot temperature must be high enough to prevent the tungsten halide from condensing, and if these conditions are met, a continuous transport cycle is run to ensure that the envelope is free of tungsten.

Many hard glasses, such as aluminosilicates, have been used with tungsten halogen lamps with varying degrees of success. Such glass includes Corning Incorporated no. 1720, 1724, and 1725; Glass no. Available from Schott. 8252 and 8253; No. Available from General Electric. There is 180.

1720, 1724 and 8252 glass have been successfully used in low voltage applications (ie 12 v), such as automotive headlamps operating at wall temperatures below 500 ° C .; However, for line voltage applications, ie, voltages above 85 v, with wall temperatures much higher than 500 ° C., these glasses have proved unusable due to good sealing inability to maintain. This condition is due to the structural compaction of the glass during operation. Compressed glass will create stresses that may exceed the breaking strength of the glass, ultimately breaking the lamp seal.

Other glasses such as 1725, 180, and 8253, all of which have substantially higher glass strain points, while at lower wall temperatures generated by reduced envelope sizes and larger voltages, i.e., voltages above 85 v. Usable) is not broken from compression but ultimately from blackening caused by tungsten deposition on the inner bulb wall, which subsequently causes non-passive lamp failure, ie the lamp capsule explodes. Ideally, lamp breakage should be passive, ie passive by breaking the filament. Typically, the halogen gas used is HBr or CH ₃ Br. As noted above, the concentration of bromine (or other halogen) is important for the halogen cycle control by tungsten. The glasses listed above work well initially, but after a period of time, the alkaline earth cations react with the precursor walls, depleting bromine from the halogen cycle. The reaction products are typically BaBr ₂ and CaBr ₂ , which appear as white haze inside the lamp envelope surface. Halogen lamps are typically designed with this reaction as a limiting factor in lamp performance.

It has been proposed to reduce the alkaline earth reaction with bromine by applying a silica barrier coating on the inner surface of the lamp envelope (see US Pat. No. 5,473,226, assigned to the assignee of the present invention); However, this solution is expensive and not completely effective.

If a glass can be developed that uses 85 V or higher power to eliminate or significantly reduce the combined effect of glass material and halogen in the lamp, thus improving lamp performance (through increased lumen maintenance) and lifetime; That is, it would be an advance in the art if it could be extended beyond 2500 hours without a substantial drop in light output.

Accordingly, it is an object of the present invention to obviate the disadvantages of the prior art.

Another object of the present invention is to enhance the performance of halogen cycle lamps.

Another object of the present invention is to provide a glass for a tungsten halogen lamp that delivers the above results and is economical to manufacture.

This object is, in one aspect of the invention, a transparent glass envelope in which a tungsten filament is sealed therein; A pair of electrical leads connecting the filaments and extending out of the envelope for connection with a supply voltage of at least 85 v; And a long life halogen cycle incandescent lamp for operation at 85 v or greater, comprising a gas filling in an envelope containing halogen, which is at least 3 atm pressure. The envelope is essentially in weight percent of composition,> 58 to about 64% SiO ₂ , about 14 to about 17.5% Al ₂ O ₃ ; 0 to about 1% B ₂ O ₃ , 1 to about 7% MgO, about 5.5 to about 14% CaO, about 6 to about 17% BaO, 0 to about 8% SrO, and 0 to about 1.5% ZrO ₂ It is made of alkaline earth aluminosilicate glass. Trace amounts of other compounds such as CeO ₂ , or TiO ₂ may be present in amounts up to 1% by weight. In a preferred aspect of the invention, the envelope is, by weight, 59 to about 61% SiO ₂ , about 15.3 to about 17.2% Al ₂ O ₃ ; About 0.3 to about 0.5% B ₂ O ₃ , 1 to about 6.5% MgO, about 5.9 to about 13.5% CaO, about> 6.5 to about 9.5% BaO, 0 to about 8% SrO, about 0.05 to about 1% ZrO ₂ Aluminosilicate glass with reduced affinity to halogen, including from about 0 to about 0.3% CeO ₂ , and from about 0 to about 0.5% TiO ₂ .

The figure is a sectional view of a tungsten halogen lamp utilizing the present invention.

Best mode for carrying out the invention

To assist in the understanding of the present invention, along with other and further objects, advantages and capabilities of the present invention, the following description and appended claims are taken in conjunction with the foregoing drawings.

Referring now to more detailed drawings, there is shown a ramp 30 having a longitudinal axis L and comprising an outer envelope 32 and an inner envelope 34, a frame assembly 36, and a base 38. Has been shown. The outer envelope 32 has a neck 40. The inner envelope 34 is a tungsten halogen incandescent capsule with a filament 45 in which the filaments are connected with electrical leads 42, 44, which lead to a body 34 for connection with a supply voltage source of 85 v or greater. Extend to the outside In this case, the capsule 34 is fixed to the frame 36.

Capsule 34 is made from the glass of the present invention and contains a gaseous fill consisting of an inert gas and a halogen. In a preferred embodiment of the invention, the fill comprises 95% Kr, about 5% N ₂ and 0.10% HBr and is at a pressure of 3 to 8 atmospheres.

The aluminosilicate glass of the capsule 34 consists essentially of, in weight percent,> 58 to about 64% SiO ₂ , about 14 to about 17.5% Al ₂ O ₃ ; 0 to about 1% B ₂ O ₃ , about 1 to about 7% MgO, about 5.5 to about 14% CaO, about 6 to about 17% BaO, 0 to about 8% SrO, and 0 to about 1.5% ZrO ₂ Is done. In a preferred embodiment of the present invention, boron oxide and zirconium oxide will be removed because there is no known effect on lamp operation; However, traces may be necessary to assist in the melting process. It may also be advisable to include trace amounts of zinc oxide for liquidus control, and trace amounts of CeO ₂ and / or TiO ₂ for UV absorbing edge control. Up to 2 wt.% Br may be added to the glass suitable for use in the tanning lamp. This amount corresponds to up to approximately 0.6% by weight in the finished glass, based on the volatility of the compound used (eg BaBr ₂ ).

Some of the glasses of the present invention were tested for bromine depletion for prior art glasses in the following manner. Glass no. Loading into capsule glass tubing formed from 8253, 180, 1725, 1724, 1720 and various compositions of the inventive glass. The compositions of these glasses are shown in Table 1.

1720 1724 8252 1725 180 8253 Oxide Corning Corning Schott Corning GE Schott SiO ₂ 60.63 57.2 60 63.4 62.1 61.9 Al ₂ O ₃ 16.22 16.3 14.5 14.5 14.3 16.2 B ₂ O ₃ 5.02 4.35 4.5 0.05 0 0.34 MgO 8.17 5.79 2.0 0.2 0 0.05 CaO 9.45 8.03 10.0 11.2 6.5 12.5 BaO 8.07 9.0 10.4 16.8 7.7 SrO 0 0.2 0.2 0.1 Na ₂ O 0.51 0.038 0.03 0.02 0.08 K ₂ O 0.024 0.02 0.01 0.01 ZrO ₂ 0.16 0 0 1.1 Fe ₂ O ₃ 0.048 0.041 0.033 0.031 TiO ₂ 0.21 BaO / CaO [mol] 0.37 0.33 0.34 0.95 0.22 MgO / CaO [mol] 1.20 1.00 0.28 Mole% RO 23.0 22.4 19.2 18.3 16.1 18.5 Physical properties Softening Point [℃] 915 926 940 993 1020 1000 Annealing Point [℃] 712 726 725 778 786 783 Strain point [℃] 668 674 716 733 733 Thermal Expansion 23-300C [x10 ^-7 / C] 42 44 46 45 43 45 Density [g / cc] 2.52 2.56 2.63 2.72 2.68 2.62

The quartz reaction vessel is emptied and refilled and sealed with a gas consisting of about 80% Kr, 19% N and 1% HBr at a pressure of 1 atmosphere. The reaction vessel is placed in an isothermal section of the oven and heated at 610 ° C. for 500 hours. After cooling, the reaction vessel is opened, the test glass tubing is removed and one end capped and filled with deionized water. The opposite end is then capped and the capsule tubing is heated to 100 ° C. for 1 hour to dissolve the water soluble reactant formed on the inner surface of the capsule cylinder. The water content of each capsule tube is then analyzed for bromine, calcium, magnesium, barium, strontium (one of the glass samples has a small amount of CaO replaced by SrO), sodium. The results are shown in Table 2.

                         Concentration in initial solution (millimoles / liter) Explanation Br Ba Ca Mg Sr Na 8253, CaO partially substituted with SrO 0.390 0.036 0.083 0.000 0.062 0.019 GE180, Production Composition 0.388 0.109 0.060 0.000 0.004 0.007 8253, ZrO ₂ and B ₂ O ₃ missing 0.348 0.023 0.146 0.000 0.001 0.010 8253D, production composition 0.319 0.020 0.135 0.000 0.002 0.011 8253, no ZrO ₂ 0.229 0.018 0.124 0.000 0.001 0.007 8253, low alkali production glass 0.189 0.008 0.061 0.000 0.000 0.006 1725, production composition 0.154 0.032 0.099 0.000 0.002 0.012 1724, Lab Melt 0.035 0.007 0.008 0.001 0.000 0.003 8253, partial substitution of CaO with MgO 0.034 0.007 0.009 0.001 0.000 0.003 1724, production composition 0.030 0.006 0.007 0.001 0.000 0.003 1720, production composition [0.5 wt. Alkali] 0.012 0.000 0.006 0.001 0.000 0.005 8253D, no HBr treatment [control] 0.002 0.000 0.004 0.000 0.000 0.002

One of the glasses of the present invention is shown in Table 2 as "8253, partial substitution of CaO with MgO." It can be seen that this glass had much less bromine reaction than that of other high temperature glass under the same test conditions. Low temperature glass, ie 1720 and 1724, also had low bromine contamination as expected from use in low voltage applications; However, as noted above, these glasses cannot be used for high voltage applications because they cause structural compression and ultimately result in non-passive lamp breakage when cracking occurs at the inner glass-lead wire contact surfaces. This is because of the low glass strain point.

Other glasses of the present invention are prepared as follows;

Alkali-lack variants such as silica sand, aluminum oxide, magnesium carbonate, calcium carbonate and barium carbonate, and zirconium sand are used in the production of the example glass, respectively. If necessary, cerium oxide and barium bromide may be added. The well homogenized mixture is melted in-lab, at Pt / Rh crucible, 1600-1650 ° C., and refined to homogenize. The glass is drawn vertically in a laboratory drawer. There was no collapsible small crystal in the glass. Table 3 shows Examples (A5) and Comparative Examples (V1) of glass according to one aspect of the present invention, together with their composition (% by weight based on oxide) and essential properties.

The reboiling temperature is indicated along with the transformation temperature (Tg). The reboiling temperature is the temperature at which the visible inorganic bubble glass sample at room temperature suddenly exhibits bubble formation at the contact surface with the metal (sample holder, Mo). The higher this reboiling temperature, the less the glass tends towards bubble formation when sealed to Mo. In the comparative example, the upper cooling point (UCP) is shown instead of Tg.                 

High performance tungsten-halogen lamps are made from glass tubes in a conventional manner for lamp testing. They are operated continuously at a bulb temperature of 700 ° C. The period before blackening occurs inside the glass bulb is measured. The value for A5 is also good enough. In the case of V1, bulb bulge occurred.

A5 V1 SiO ₂ 60.7 56.8 Al ₂ O ₃ 16.5 16.4 B ₂ O ₃ 0.3 4.7 MgO 5.7 5.8 CaO 7.8 7.8 SrO - - BaO 8.0 8.0 ZrO ₂ 1.0 - CeO ₂ - - Br ^- - - Na ₂ O 0.011 0.028 K ₂ O 0.006 0.018 H ₂ O (% by weight) 0.01 0.017 20/300 [10 ^-8 / K] 4.37 4.52 Tg [℃] 781 721 (UCP) Reboiling Temperature [℃] 1490 n.d.

In addition, it is preferable that the sum of alkali-earth oxides (RO) is not 21 wt% or less and not 24 wt% or more. Outside this range both thermal expansion and viscosity were found to deviate from the desired value.

In addition, the weight ratio ((CaO + SrO + MgO) / BaO) between the sum of CaO, SrO and MgO on the one hand and BaO on the other hand is 1.45 to 1.75. Preferably, it is 1.65-1.75.

In addition, it is assumed that the weight ratio of MgO: CaO is important; Thus, MgO / CaO will always be greater than zero, preferably less than about 0.8; Otherwise, the crystallization stability of the glass will not be suitable for tube drawing.

Tricomponent mixed alkaline earth oxides (BaO, CaO, MgO) rather than the bicomponent alkaline earth oxide (BaO, CaO) systems used in prior art glass used for high voltage lamps, namely GE 180, Corning 1725 or Schott 8253. It is assumed that the advantages of the present invention arise because of the slower ion transport in the case of). Also important in the glass making of the present invention is the elimination of alkali contamination or a reduction to an absolute minimum, ie the presence of sodium, lithium and / or potassium should be kept below 0.05% by weight. Thus, there is an obvious advantage over the prior art, i.e. in the absence of bromine reaction products on the inner surface of lamps operating under halogen cycles, thus a five-component alumino-silicate system (SiO) which allows longer operation under better retention. ₂ , Al ₂ O ₃ , BaO, CaO, MgO) are provided by the present invention. In addition, non-passive breakage is reduced or eliminated as the lamp burns cleanly until a normal end of life is achieved.

While what has now been illustrated and described as what is believed to be the preferred embodiments of the invention, it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined by the appended claims.

Claims (22)

Transparent glass envelopes in which tungsten filaments are sealed; A pair of electrical leads connecting the filaments and extending out of the envelope for connection with a supply voltage of at least 85 v; And a filling gas in the envelope, including halogen, at a pressure of at least 3 atmospheres, The envelope is essentially, in weight percent,> 58-64% SiO ₂ , 14-17.5% Al ₂ O ₃ ; Has a composition consisting of 0-1% B ₂ O ₃ , 1-7% MgO, 5.5-14% CaO, 6-17% BaO, 0-8% SrO, and 0-1.5% ZrO ₂ (CaO + SrO + MgO A long life halogen cycle incandescent lamp for operation at 85 v or greater, made of alkaline earth aluminosilicate glass having a weight ratio of 1.45 / BaO of 1.45 to 1.75. The lamp of claim 1 wherein the halogen is bromine. The lamp of claim 1, wherein the pressure is about 8 atmospheres or less. 4. The lamp of claim 3 wherein the lamp, when in operation, has a wall temperature of at least 500 ° C. 5. The lamp of claim 4 wherein the envelope composition comprises trace amounts of ZnO for liquidus control. 6. The lamp of claim 5 wherein the fill gas comprises an inert gas. 7. The lamp of claim 6, wherein the halogen is bromine. By weight,> 58 to 64% SiO ₂ , 14 to 17.5% Al ₂ O ₃ ; 0 to 1% B ₂ O ₃ , 1 to 7% MgO, 5.5 to 14% CaO, 6 to 17% BaO, and 0 to 8% SrO and the weight ratio of (CaO + SrO + MgO) / BaO is from 1.45 to Aluminosilicate glass with reduced affinity for halogen, which is 1.75. The glass of claim 8, wherein the composition has a B ₂ O ₃ of 1% or less. 10. The glass of claim 9, wherein the composition has ZrO ₂ of 1.5% or less. The glass of claim 10, wherein traces of ZnO replace traces of CaO for liquidus control. Essentially, by weight percent based on oxide,> 58 to 64% SiO ₂ , 14 to 17.5% Al ₂ O ₃ ; Consisting of 0 to 1% B ₂ O ₃ , 1 to 7% MgO, 5.5 to 14% CaO, 6 to 17% BaO, 0 to 1.5% ZrO ₂ and 0 to about 8% SrO (CaO + SrO + MgO) Alkali-to aluminosilicate glass, wherein the weight ratio of / BaO is 1.45 to 1.75. 13. The glass of claim 12, wherein the sum of alkali-earth oxides is not less than 21% by weight and not greater than 24% by weight. delete 13. The glass of claim 12, wherein the weight ratio is from 1.65 to 1.75. 13. The glass of claim 12, wherein the glass has an alkali oxide content of <0.03% by weight and a water content of <0.02% by weight. The lamp of claim 1, wherein B ₂ O ₃ is present in an amount of 0.2 to 0.7 wt%. The lamp of claim 1 wherein the amount of ZrO ₂ is from 0.05 to 1 weight percent. By weight,> 58 to 64% SiO ₂ , 14 to 17.5% Al ₂ O ₃ ; 0-1% B ₂ O ₃ , 1-7% MgO, 5.5-14% CaO, 6-17% BaO, 0-8% SrO, 0-1.5% ZrO ₂ , 0-0.3% CeO ₂ , and 0- Aluminosilicate glass with reduced affinity for halogen, comprising 0.5% TiO _{2 and} having a weight ratio of (CaO + SrO + MgO) / BaO of 1.45 to 1.75. By weight, 59-61% SiO ₂ , 15.3-17.2% Al ₂ O ₃ ; 0.3-0.05% B ₂ O ₃ , 1-6.5% MgO, 5.9-13.5% CaO,> 6.5-9.5% BaO, 0-8% SrO, 0.05-1% ZrO ₂ , 0-0.3% CeO ₂ , and 0 Aluminosilicate glass with reduced affinity for halogen, comprising from 0.5% TiO _{2 and} having a weight ratio of (CaO + SrO + MgO) / BaO of 1.45 to 1.75. By weight, 60.7% SiO ₂ , 16.5% Al ₂ O ₃ ; Reduced affinity to halogen, including 0.3% B ₂ O ₃ , 5.7% MgO, 7.8% CaO, 8% BaO, 1% ZrO ₂ , 0-0.3% CeO ₂ , and 0-0.5% TiO ₂ Aluminosilicate glass. The lamp of claim 1, wherein the envelope also comprises> 0 to about 8% SrO.

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