US3716744A - Hermetic end seals for envelope of a metal vapor lamp - Google Patents
Hermetic end seals for envelope of a metal vapor lamp Download PDFInfo
- Publication number
- US3716744A US3716744A US00171578A US3716744DA US3716744A US 3716744 A US3716744 A US 3716744A US 00171578 A US00171578 A US 00171578A US 3716744D A US3716744D A US 3716744DA US 3716744 A US3716744 A US 3716744A
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- US
- United States
- Prior art keywords
- seal
- envelope
- metal
- cap
- stem
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/02—Details
- H01J61/36—Seals between parts of vessels; Seals for leading-in conductors; Leading-in conductors
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J5/00—Details relating to vessels or to leading-in conductors common to two or more basic types of discharge tubes or lamps
- H01J5/20—Seals between parts of vessels
- H01J5/22—Vacuum-tight joints between parts of vessel
- H01J5/26—Vacuum-tight joints between parts of vessel between insulating and conductive parts of vessel
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2893/00—Discharge tubes and lamps
- H01J2893/0033—Vacuum connection techniques applicable to discharge tubes and lamps
- H01J2893/0037—Solid sealing members other than lamp bases
- H01J2893/0041—Direct connection between insulating and metal elements, in particular via glass material
Definitions
- ABSTRACT An alkali-metal-vapor discharge lamp has an inner vitreous material hermetic seal between an electrode stem and translucent tubular envelope and an outer metal seal between a metal end cap and the envelope. The cap is also sealed to the stem which extends from the tube.
- the present invention relates to high-pressure alkalimetal vapor discharge lamps and particularly to highpressure sodium vapor lamps. More particularly, it relates to improvements in hermetic gas or vacuum tight seals which are made in manufacturing the lamps.
- the high-pressure alkali-metal-vapor discharge lamps comprise tubes of translucent polycrystalline alumina resistant to high pressure alkali-metal vapors. Such a tube is closed at its ends by pieces of refractory material also resistant to alkali-metal vapors.
- Pumping stems of refractory metal which are used as electrode supports and current leads for the electrodes, pass through the refractory material pieces.
- a refractory metal is selected among the following metals and alloys thereof: niobium, zirconium, titanium, vanadium, tantalum, and preferably niobium and its well-known alloy with zirconium (1 percent).
- the metal-alumina seal may be made either with eutectic mixtures of alumina and calcium oxide or a vitreous mixture of alumina, calcium oxide and magnesium oxide, or with active metals such as titanium, vanadium, zirconium or preferably combinations thereof.
- vitreous seal materials may become devitrified, which is another cause of leakage.
- active metal seals are used, they are made on the alumina tube end, which results in a short tight length compared with leakage line lengths, just a little longer than the tube thickness.
- a discharge impact spot may be located on a metal seal part, which can cause leaks,
- a purpose of the present invention is to provide a tight closure of the discharge area which does not present the above mentioned drawbacks.
- tight sealing of the discharge area is obtained by proper sealing of the tube and electrode stem with two end seals at each end of the tube.
- An outer end-seal is formed with a refractory metal cap sealed to the tube end by a combination of active metals and to the stem by brazing.
- An inner endseal is formed by a ring of alumina sealed to the tube and to the stem by a vitreous mixture.
- FIG. 1 shows a schematic cross-section view of one of the two ends of the discharge area before melting
- FIG. 2 shows the same elements after melting.
- FIG. 1 shows a schematic cross-section view of one end of the discharge tube before melting, the cross-section being obtained across a diametral plane.
- the gas or vacuum tight closure of the translucent polycrystalline alumina tube or envelope 1 is formed by two endseals.
- One end-seal 2 is made of a ring of highly pure alumina, which may be translucent or not.
- the other end-seal 7 is a cap made of refractory metal, preferably of niobium or niobium alloy.
- Those end-seals 2 and 7, through which the stem 4 passes, are sealed to the alumina tube 1 respectively by a ring 3 of vitreous material mainly constituted by alumina and calcium oxide, and by rings 10 of active metals such as titanium, vanadium and zirconium.
- FIG. 1 also shows the electrode 5 secured to the stem 4 by a weld 9 made by any known process.
- the hole 6 is provided for evacuating or filling the discharge area 11.
- the assemblies are heated to a high temperature, under vacuum or inertgas-filled condition, to cause melting of the various rings.
- the seals are as shown in the FIG. 2 which includes the same elements as in the FIG. 1, the same reference numbers being used in both figures.
- the end-seal cap 7 may be sealed to the stem 4 by a seal 8 made according to any known process such as brazing, either before the ring melting operation, or at the same time.
- the area 12 between the two seals is preferably evacuated or filled with an inert gas.
- FIG. 2 shows that, after melting, the ring 3 is shaped as shown by 3 and forms a tight hermetic seal between the end-seal 2 and the tube 1, on the one hand, and between the end-seal 2 and the stem 4, on the other hand.
- the rings 10 are then shaped as shown by 10 and form a tight seal between the tube 1 and the end-seal cap 7.
- the seal temperature is lowered during operation which results in less severe thermal shocks during the life-time of the lamp
- the seal is not in contact with alkali-metal vapor because the area 12 is evacuated or filled with inert gas, which reduces the risk of corrosion;
- the invention may also be utilized in any case where alumina-metal seals are in contact with alkali-metal vapors.
- a seal for a vapor discharge lamp comprising:
- said first seal includes a ring of alumina and a vitreous mixture hermetically sealing said ring to said stem and envelope.
- said second seal includes a ring of refractory metals selected from the group consisting of titanium, vanadium and zirconium.
- said envelope is of poly-crystalline alumina and said vitreous sealing mixture includes a eutectic mixture of alumina and calcium oxide.
Landscapes
- Vessels And Coating Films For Discharge Lamps (AREA)
Abstract
An alkali-metal-vapor discharge lamp has an inner vitreous material hermetic seal between an electrode stem and translucent tubular envelope and an outer metal seal between a metal end cap and the envelope. The cap is also sealed to the stem which extends from the tube.
Description
United States Patent Delembre et al.
[ 1 Feb. 13, 1973 HERMETIC END SEALS FOR ENVELOPE OF A METAL VAPOR LAMP Inventors:
Assignee:
Filed:
Appl. No.:
Andre Emile Delembre, Asineres, France; Georges Roger Jarrige, deceased, late of Bagneux, France; by Jeanine Jarrige, administratrix, Germain Sucy-en-Brie; Dat Nhiep Nguyen, Chatenay-Malabrey, both of France ITT Industries, Inc., New York, N.Y. by said Delembre and Nguyen Aug. 13,1971
Foreign Application Priority Data Aug. 27, 1970- France .703l286 U.S. Cl.
Primary Examiner-Palmer C. Demeo Attorney-C. Cornell Remsen, Jr. et al.
[57] ABSTRACT An alkali-metal-vapor discharge lamp has an inner vitreous material hermetic seal between an electrode stem and translucent tubular envelope and an outer metal seal between a metal end cap and the envelope. The cap is also sealed to the stem which extends from the tube.
6 Claims, 2 Drawing Figures PATENTED FEB] 31975 Inventors ANDRE E. DELEMBRE GEORGES R. JARR/GE I By AT N. Nam/5 MA Horney HERM ETIC END SEALS FOR ENVELOPE OF A METAL VAPOR LAMP BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to high-pressure alkalimetal vapor discharge lamps and particularly to highpressure sodium vapor lamps. More particularly, it relates to improvements in hermetic gas or vacuum tight seals which are made in manufacturing the lamps.
2. Description of the Prior Art The high-pressure alkali-metal-vapor discharge lamps comprise tubes of translucent polycrystalline alumina resistant to high pressure alkali-metal vapors. Such a tube is closed at its ends by pieces of refractory material also resistant to alkali-metal vapors. Pumping stems of refractory metal, which are used as electrode supports and current leads for the electrodes, pass through the refractory material pieces. Such a refractory metal is selected among the following metals and alloys thereof: niobium, zirconium, titanium, vanadium, tantalum, and preferably niobium and its well-known alloy with zirconium (1 percent).
Whatever refractory metal the end-seal is made of, the metal-alumina seal may be made either with eutectic mixtures of alumina and calcium oxide or a vitreous mixture of alumina, calcium oxide and magnesium oxide, or with active metals such as titanium, vanadium, zirconium or preferably combinations thereof.
If vitreous mixtures are used, their adherence to metal parts is weak, which may result in gas leakage from the discharge area to the outside during lamp life. In addition, due to high temperature and alkali-metal vapors, vitreous seal materials may become devitrified, which is another cause of leakage.
If active metal seals are used, they are made on the alumina tube end, which results in a short tight length compared with leakage line lengths, just a little longer than the tube thickness. In addition, at the start, with the pressure being low, a discharge impact spot may be located on a metal seal part, which can cause leaks,
SUMMARY OF THE INVENTION Therefore, a purpose of the present invention is to provide a tight closure of the discharge area which does not present the above mentioned drawbacks.
According to the invention, tight sealing of the discharge area is obtained by proper sealing of the tube and electrode stem with two end seals at each end of the tube. An outer end-seal is formed with a refractory metal cap sealed to the tube end by a combination of active metals and to the stem by brazing. An inner endseal is formed by a ring of alumina sealed to the tube and to the stem by a vitreous mixture.
Other purposes, features and advantages of the present invention will appear from the following description of a specific embodiment made in conjunction with the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a schematic cross-section view of one of the two ends of the discharge area before melting, and
FIG. 2 shows the same elements after melting.
DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a schematic cross-section view of one end of the discharge tube before melting, the cross-section being obtained across a diametral plane. The gas or vacuum tight closure of the translucent polycrystalline alumina tube or envelope 1 is formed by two endseals. One end-seal 2 is made of a ring of highly pure alumina, which may be translucent or not. The other end-seal 7 is a cap made of refractory metal, preferably of niobium or niobium alloy. Those end-seals 2 and 7, through which the stem 4 passes, are sealed to the alumina tube 1 respectively by a ring 3 of vitreous material mainly constituted by alumina and calcium oxide, and by rings 10 of active metals such as titanium, vanadium and zirconium.
FIG. 1 also shows the electrode 5 secured to the stem 4 by a weld 9 made by any known process. The hole 6 is provided for evacuating or filling the discharge area 11. When the above mentioned elements have been located at each end of the tube 1, the assemblies are heated to a high temperature, under vacuum or inertgas-filled condition, to cause melting of the various rings. After having melted the rings, the seals are as shown in the FIG. 2 which includes the same elements as in the FIG. 1, the same reference numbers being used in both figures. It will be noted that the end-seal cap 7 may be sealed to the stem 4 by a seal 8 made according to any known process such as brazing, either before the ring melting operation, or at the same time. The area 12 between the two seals is preferably evacuated or filled with an inert gas.
FIG. 2 shows that, after melting, the ring 3 is shaped as shown by 3 and forms a tight hermetic seal between the end-seal 2 and the tube 1, on the one hand, and between the end-seal 2 and the stem 4, on the other hand. In a like manner, the rings 10 are then shaped as shown by 10 and form a tight seal between the tube 1 and the end-seal cap 7.
The advantages of the new seals are as follows:
1. Since the first seal is made with vitreous material, risks of hazardous arcing on the seal 10 (FIG. 2) are suppressed.
. If, after operation of a certain time, a devitrification phenomenon occurs for the seal 3 (FIG. 2), a tight seal is provided by the seal 10, (FIG. 2). However, the life-time of the seal 10 is longer than that which would be obtained if the end-seal 2 was not present. This is due to the fact that:
a. the seal temperature is lowered during operation which results in less severe thermal shocks during the life-time of the lamp;
. the seal is not in contact with alkali-metal vapor because the area 12 is evacuated or filled with inert gas, which reduces the risk of corrosion; and
c. there is no arcing on the seal.
The invention may also be utilized in any case where alumina-metal seals are in contact with alkali-metal vapors.
While the present invention has been described with respect to a specific embodiment, it is clear that the device is not limited to this example and that it can be modified or changed without departing from the scope of the invention as set forth in the appended claims.
What is claimed is:
1. A seal for a vapor discharge lamp comprising:
a tubular envelope of translucent vitreous material,
an electrode within one end of said envelope and having a stem extending out of said envelope,
a first seal of vitreous material between said stem and envelope,
a metal end cap at the outer end of said envelope,
said stem extending through said cap,
a second seal of refractory metal between said cap and said envelope, and
a further seal between said cap and stem.
2. The device of claim 1 wherein said first seal includes a ring of alumina and a vitreous mixture hermetically sealing said ring to said stem and envelope.
3. The device of claim 2 wherein said second seal includes a ring of refractory metals selected from the group consisting of titanium, vanadium and zirconium.
4. The device of claim 3 wherein said cap is of niobium and said further seal includes a brazing metal.
5. The device of claim 3 wherein said lamp includes an alk'ali-metal-vapor and the area between said first seal and metal cap is filled with an inert gas.
6. The device of claim 3 wherein said envelope is of poly-crystalline alumina and said vitreous sealing mixture includes a eutectic mixture of alumina and calcium oxide.
Claims (5)
1. A seal for a vapor discharge lamp comprising: a tubular envelope of translucent vitreous material, an electrode within one end of said envelope and having a stem extending out of said envelope, a first seal of vitreous material between said stem and envelope, a metal end cap at the outer end of said envelope, said stem extending through said cap, a second seal of refractory metal between said cap and said envelope, and a further seal between said cap and stem.
2. The device of claim 1 wherein said first seal includes a ring of alumina and a vitreous mixture hermetically sealing said ring to said stem and envelope.
3. The device of claim 2 wherein said second seal incluDes a ring of refractory metals selected from the group consisting of titanium, vanadium and zirconium.
4. The device of claim 3 wherein said cap is of niobium and said further seal includes a brazing metal.
5. The device of claim 3 wherein said lamp includes an alkali-metal-vapor and the area between said first seal and metal cap is filled with an inert gas.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR7031286A FR2102865A5 (en) | 1970-08-27 | 1970-08-27 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3716744A true US3716744A (en) | 1973-02-13 |
Family
ID=9060614
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US00171578A Expired - Lifetime US3716744A (en) | 1970-08-27 | 1971-08-13 | Hermetic end seals for envelope of a metal vapor lamp |
Country Status (2)
Country | Link |
---|---|
US (1) | US3716744A (en) |
FR (1) | FR2102865A5 (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2405335A1 (en) * | 1973-02-16 | 1974-08-22 | Philips Nv | HIGH PRESSURE DISCHARGE LAMP |
US3832588A (en) * | 1972-09-25 | 1974-08-27 | Gen Electric | Ceramic discharge lamp having metal end cap |
US3916242A (en) * | 1974-07-30 | 1975-10-28 | Us Army | Electrode seal and electrode mount for alkali-metal vapor lamps |
EP0052843A1 (en) * | 1980-11-21 | 1982-06-02 | GTE Laboratories Incorporated | Vacuum-tight assembly |
EP0052844A1 (en) * | 1980-11-21 | 1982-06-02 | GTE Laboratories Incorporated | Vacuum-tight assembly |
US5620349A (en) * | 1991-12-11 | 1997-04-15 | Osram Sylvania Inc. | Method for amalgam relocation in an arc discharge tube |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3363133A (en) * | 1966-02-28 | 1968-01-09 | Sylvania Electric Prod | Electric discharge device having polycrystalline alumina end caps |
US3448319A (en) * | 1966-10-31 | 1969-06-03 | Gen Electric | Niobium end seal |
US3473071A (en) * | 1965-10-25 | 1969-10-14 | Gen Electric Co Ltd | Electric discharge lamps |
-
1970
- 1970-08-27 FR FR7031286A patent/FR2102865A5/fr not_active Expired
-
1971
- 1971-08-13 US US00171578A patent/US3716744A/en not_active Expired - Lifetime
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3473071A (en) * | 1965-10-25 | 1969-10-14 | Gen Electric Co Ltd | Electric discharge lamps |
US3363133A (en) * | 1966-02-28 | 1968-01-09 | Sylvania Electric Prod | Electric discharge device having polycrystalline alumina end caps |
US3448319A (en) * | 1966-10-31 | 1969-06-03 | Gen Electric | Niobium end seal |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3832588A (en) * | 1972-09-25 | 1974-08-27 | Gen Electric | Ceramic discharge lamp having metal end cap |
DE2405335A1 (en) * | 1973-02-16 | 1974-08-22 | Philips Nv | HIGH PRESSURE DISCHARGE LAMP |
US3916242A (en) * | 1974-07-30 | 1975-10-28 | Us Army | Electrode seal and electrode mount for alkali-metal vapor lamps |
EP0052843A1 (en) * | 1980-11-21 | 1982-06-02 | GTE Laboratories Incorporated | Vacuum-tight assembly |
EP0052844A1 (en) * | 1980-11-21 | 1982-06-02 | GTE Laboratories Incorporated | Vacuum-tight assembly |
US5620349A (en) * | 1991-12-11 | 1997-04-15 | Osram Sylvania Inc. | Method for amalgam relocation in an arc discharge tube |
US6100634A (en) * | 1991-12-11 | 2000-08-08 | Gte Products Corporation | Method for amalgam relocation in an arc discharge tube |
Also Published As
Publication number | Publication date |
---|---|
FR2102865A5 (en) | 1972-04-07 |
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