US2251062A - Hermetic seal - Google Patents
Hermetic seal Download PDFInfo
- Publication number
- US2251062A US2251062A US363190A US36319040A US2251062A US 2251062 A US2251062 A US 2251062A US 363190 A US363190 A US 363190A US 36319040 A US36319040 A US 36319040A US 2251062 A US2251062 A US 2251062A
- Authority
- US
- United States
- Prior art keywords
- foil
- seal
- vitreous
- metal
- lamp
- Prior art date
- 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
Links
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Classifications
-
- 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
- H01J5/32—Seals for leading-in conductors
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T403/00—Joints and connections
- Y10T403/47—Molded joint
- Y10T403/477—Fusion bond, e.g., weld, etc.
Definitions
- the present invention relates to hermetic, electrically conducting seals for gaseous electric discharge devices and more particularly to seals 1 such as a metal foil. fused into a vitreous body having a low coemcient of expansion.
- ent invention'pertains is slender and cylindrical in shape and the thin metal foil or strip is mounted with its largest dimension in or parallel to the longitudinal axis of the vitreous seal part.
- a pair of wires mounted in the same straight line in or parallel to the longitudinal axis of the vitreous part and passing through said .foil or strip is attached to the edge portions oi the foil in opposingpositions. Said wires terminate beyond the respective ends of the vitreous seal part. The distance between the, ends of the wires fastened to the strip is appreciable.
- Seals of this type are useful for gaseous electric discharge lamps having a quartz or hard glass envelope containing a starting'gas and a quantity of mercury the vapor of which is at a pressure of about 10 atmospheres or higher during the operation of the lamp. Lamps of this type are eflicient light sources of high intrinsic brilliancy.
- the seals of these high pressure discharge lamps I must be strong mechanically and resistant to heat to remain gas tight under high pressure.of the vapor atmwphere and thehigh temperature
- the seal usually protrudes from the envelope. Frequently the seal becomes so hot in service that the part of the metal conductor external to the seal and exposed to the oxygen containing atmosphere is oxidized. ; The oxide layer thus formed gradually creeps along the conductor and into the fused joint between the metal and the vitreous parts of the seal. The Joint then becomes pervious to gas to terminate the useful life of the lamp.
- the object of the present invention is to pro-. vide a mechanically strong. hermetic, electrically conducting seal of small size and of simple structure for high pressure, high temperature dis-' charge devices. is to provide an electrically conducting foil or strip member having a low resistance to current flow for use in hermetic seals. Still further objects and advantages of the invention will be apparent to those skilled in the art from the following detailed description thereof and from the appended claims. We have discovered that the high temperatur of the seal is due not only to the high temperature of the lamp envelope during operation of the lamp but also due to the heat developed in the metal foil. which is about 20 microns, thick,
- the heat developed in the seal is reduced and the lamp is capable of operating at higher pressures and envelopL temperatures without causing the formation of a layer oi'.,oxide on the exposed part ofthe metal conductor.
- the resistance of the foil is decreased by increasing the cross-sectional area of v the center part'thereof.
- one or more longitudinal metal strips, foils or wires are mounted on the center portion of the main foil so as to make a good electrical contact therewith.
- the auxiliary foil or' the like is welded or soldered to the main foil.
- An equivalent structure is a single foil which is thicker at the center portion thereof than at the end portiona The thin end portions of the foil both make an hermetic Joint withnthe vitreous part ofthe seal.
- Fig. 1 is a side elevational, partly sectional view of the lamp is made more complicated Another object of the invention ing therefrom and contains two electrodes which are of the self-heating type.
- Each of said electrodes 5 consists of a perforated hollow body of high melting point metal, such as tungsten, having a material of high electron emissivity, such as thorium oxide, therein. During the operation of the lamp the electrodes 5 are at an elevated, arc discharge sustaining temperature.
- Said envelope I has therein a starting gas, such as argon or neon, at a pressure of about 1 or 2 centimeters and mercury in an amount sufficient to produce an unsaturated vapor atmosphere having a pressure of about 50 atmospheres when the lamp is at operating equilibrium.
- a starting gas such as argon or neon
- each of said seals 2 comprises a metal conducting element consisting of a strip or foil 3 of high melting point metal, such as molybdenum, a metal wire 4, such as a tungsten wire, attached to said foil 3 and projecting beyond the external end of the vitreous part of the seal.
- a similar metal wire 8 is attached to the opposite end of the foil 3 and terminates in the space defined by the envelope I where it supports the electrode 5.
- the foil 3 is about 15 microns thick and is reinforced at the central portion thereof by a strip 6 of high melting point metal, such as molybdenum. We prefer to weld the reinforcing strip 6 to the foil 3 but it is possible to accomplish the objects of the invention by bringing the foil 3 and the strip 6 into contact with each other.
- the strip 6 increases the cross-sectional area of this part of the conducting element and substantially decreases the electrical resistance thereof to minimize the amount of electrical energy transformed into heat by said foil 3.
- The-molybdenum foil 3 shown in Fig. 2 of the drawing is similar to those illustrated in Fig. 1 except that in this embodiment the foil 3 has a plurality of longitudinal strips I which are arranged in a staggered, overlapping pattern with a substantial distance between the strip I.
- the hermetic juncture between the foil 3 and the vitreous part of the seal is located at the end portions of the foil 3 extending beyond the'strips I and the portions of the foil 3 not covered by the strips 1.
- a thicker molybdenum foil such as a foil having a thickness of about 20 microns, is used, when desired.
- seals comprising comparatively thick foils it is desirable to apply a relatively high pressure to the vitreous part of the seal when in a softened condition to force it into intimate contact with the foil.
- the greater cross-sect onal area at the center portion of the foil is desirable since this structure permits the use of higher current densities in the arc discharge and the use of comparatively narrow foils.
- a hermetic, electrically conducting seal comprising a vitreous element having a low coefficient of expansion and an electrically conducting element fused into'said vitreous element, said vitreous element being an elongated cylindrical body, said conducting element being a thin, fiat, elongated metal member mounted with its greatest dimension in the direction of the longitudinal axis of said vitreous element, another element of electrically conducting material mounted on the center portion of said first mentioned conducting element to decrease the electrical resistance of said center portion, the edge portion of said first mentioned conducting element forming a hermetic joint with said vitreous element.
- said element consisting of a thin, elongated metal foil having a plurality of elongated strips mounted adjacent the center portion thereof in a staggered, overlapping pattern to minimize the heat generated in said foil by the passage of electrical energy therethrough and a pair of wires secured in opposing positions to the edge portion of said foil.
Landscapes
- Vessels And Coating Films For Discharge Lamps (AREA)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE2251062X | 1939-10-14 |
Publications (1)
Publication Number | Publication Date |
---|---|
US2251062A true US2251062A (en) | 1941-07-29 |
Family
ID=7992361
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US363190A Expired - Lifetime US2251062A (en) | 1939-10-14 | 1940-10-28 | Hermetic seal |
Country Status (2)
Country | Link |
---|---|
US (1) | US2251062A (lv) |
NL (1) | NL57687C (lv) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2515337A (en) * | 1947-06-24 | 1950-07-18 | Bell Telephone Labor Inc | Metal to glass seal and method of producing same |
US2760310A (en) * | 1951-01-13 | 1956-08-28 | Gen Electric | Quartz-to-metal seal |
US2816398A (en) * | 1952-02-23 | 1957-12-17 | Gen Electric | Apparatus for manufacture of a quartzto-metal foil press seal |
US2844919A (en) * | 1951-03-21 | 1958-07-29 | Gen Electric | Quartz-to-metal foil press seal |
DE102009048432A1 (de) * | 2009-10-06 | 2011-04-07 | Osram Gesellschaft mit beschränkter Haftung | Gasentladungslampe |
-
0
- NL NL57687D patent/NL57687C/xx active
-
1940
- 1940-10-28 US US363190A patent/US2251062A/en not_active Expired - Lifetime
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2515337A (en) * | 1947-06-24 | 1950-07-18 | Bell Telephone Labor Inc | Metal to glass seal and method of producing same |
US2760310A (en) * | 1951-01-13 | 1956-08-28 | Gen Electric | Quartz-to-metal seal |
US2844919A (en) * | 1951-03-21 | 1958-07-29 | Gen Electric | Quartz-to-metal foil press seal |
US2816398A (en) * | 1952-02-23 | 1957-12-17 | Gen Electric | Apparatus for manufacture of a quartzto-metal foil press seal |
DE102009048432A1 (de) * | 2009-10-06 | 2011-04-07 | Osram Gesellschaft mit beschränkter Haftung | Gasentladungslampe |
Also Published As
Publication number | Publication date |
---|---|
NL57687C (lv) |
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