CA1222274A - Unsaturated vapor high pressure sodium lamp getter mounting - Google Patents
Unsaturated vapor high pressure sodium lamp getter mountingInfo
- Publication number
- CA1222274A CA1222274A CA000448955A CA448955A CA1222274A CA 1222274 A CA1222274 A CA 1222274A CA 000448955 A CA000448955 A CA 000448955A CA 448955 A CA448955 A CA 448955A CA 1222274 A CA1222274 A CA 1222274A
- Authority
- CA
- Canada
- Prior art keywords
- oxygen
- arc tube
- envelope
- ceramic envelope
- getter
- 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
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/02—Details
- H01J61/24—Means for obtaining or maintaining the desired pressure within the vessel
- H01J61/26—Means for absorbing or adsorbing gas, e.g. by gettering; Means for preventing blackening of the envelope
Landscapes
- Vessels And Coating Films For Discharge Lamps (AREA)
- Discharge Lamp (AREA)
- Common Detailed Techniques For Electron Tubes Or Discharge Tubes (AREA)
Abstract
UNSATURATED VAPOR HIGH PRESSURE SODIUM LAMP GETTER MOUNTING
ABSTRACT
An unsaturated vapor type high pressure sodium lamp includes an arc tube having a tubular ceramic envelope containing a dosing of sodium, mercury and a rare gas with an electrode sealed into each end of the envelope and an oxygen-absorbing getter telescoped over or affixed to the electrode.
ABSTRACT
An unsaturated vapor type high pressure sodium lamp includes an arc tube having a tubular ceramic envelope containing a dosing of sodium, mercury and a rare gas with an electrode sealed into each end of the envelope and an oxygen-absorbing getter telescoped over or affixed to the electrode.
Description
- ~222274 UNSATURA~ED VAPOR HI~H PRESSURE SODIU~ LAMP GETTER MOUNTING
CROSS REFE~NCE TO OTHER APPLICATIONS
The following concurrently filed Canadian patent applications relate to unsaturated vapor pressure type high pressure sodium lamps and the fabrication thereof:
448,953-5; 448.916-1; 448,954-3; and 448,915-2.
TECHNICAL FIELD
This invention relates to unsaturated vapor high pressure sodium lamps and more particularly to the mounting of getters within the arc tube of an unsaturated vapor high pressure sodium lamp.
BACKGROUND ART
In the field of high pressure sodium lamp6, it i8 a common practice to provide an arc tube fill which includes a large amount of sodium and mercury in order to compensate for the undesired sodium lo~ses encountered.
These excess amounts of sodium and mercury re~ult in an amalgam at the coolest points of the arc tube which normally adjacent the electrodes at the ends of the arc tube. As a result, undesired variations in source voltage, color rendition and numerous other characteristics are encountered.
. ~`~',.'~
.
1~2%~
In an effort to eliminate or at least reduce such undesired effects, it has lon~ been known that a lamp wherein the amount of sodium and mercury employed is only that which will becom~ totally vaporized would provide the desired rasult. In other words, a high pressure sodium lamp of the unsaturated vapor type wherein sodium and mercury are introduced in only such an ~nount as to become totally vaporiæed is a highly desirable structure insofar as efficiency, cost of manufactur~ and enhanced lighting capability are concerned.
Also, it has long been recognized that a principal cause of undesired sodium loss in high presure sodium lamps is the presence of oxygen in the gas fill of the arc tube. One known att~pt to alleviate this undesired loss of sodium due to the presence of oxyg~n is set forth in a concurrently filed Canadian patent application, S~rial ~o. 448,953-5, of Philip J. White entitled ~'Unsaturated Vapor Pressure Type High Pressure Sodium Lamp", assi~ned to the Assignee of the present application. Therein, a getter in the form of a metal or metal alloy is located within an elongated ceramic arc tube with the metal oxides of the getter having a free energy of formation per mole of oxygen greater than that of sodium oxide. In effect, the getter reacts with Eree oxygen to inhibit the formation of compounds containing sodium and oxygen.
Although the above-described technique has been employed with var~ing amounts of success, it has been found that the results do leave something to be desired. ~ore specifically, it has be~n found that intimate contact between the tubular ceramic envelope of the arc tube and the oxygen-absorbing getter therein tends to cause an undesired darkening of the ceramic envelope in the area of contact with the getter material. Althou~h the exact cause of this darkening condition of the ceramimc envelope is not thoroughly understood, it is believed that a chemical reduction takes place between the getter and the aluminum envelope whereat contact therebetween is effected.
` ~-83-1-0~1 ~222274 OBJECTS AND SUMMARY OF THE INVENTION
An object of the present inYention is to provide an improved high pressure sodium lamp. Another object of the invention is to enhance the arc tube of an unsaturated vapor high pressure sodium lamp. A further object of the invention is the structure of an unsaturated vapor high pressure sodium lamp.
These and other objects, advantages and capabilities are achieved in one aspect of the invention by an arc tube having a tubular ceramic envelope with an electrode sealed into each end of the envelope, a dosing of sodium, mercury and rare gas within the envelope and an oxygen-absorb;ng getter attached to at least one of the electrodes within the ceramic envelope.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is an elevational view of a preferred form of unsaturated vapor high pressure sodium lamp; and FI6. 2 is an exploded sectional view of an electrode formed for enclosure within a ceramic envelope and having an oxygen-absor~ing getter affixed thereto.
BEST MODE FOR CARRYING OUT THE INVENTION
For a better understanding of the present invention, together with other and further objects, advantages and capabilities thereof, ,~
reference is made to the following disclosure and appended claims in conjunction with the accompanying drawings.
Referring to the drawings, FIG. 1 illustrates an unsaturated vapor high pressure sodium lamp having a hermetically sealed and evacuated glass envelope 5 formed to fit into an ordinary screw-type base member 7. A glass stem member 9 is sealed to the envelope and projects therein. Electrical conductors, 11 and 13 D-~3-1-021 ~LZ2;~274 respectively, are sealed into and pass through the stem member 9 to provide electrical connections from the interior to the exterior of the glass envelope 5.
An electrically conductive support member 15 is affixed to one 5 of the electrical conductors 11 and has a pair of crossbars 17 and 19 affixed thereto at either end. Also, a plurality of spring-like members 21 are affixed to the support member 15 and formed for contact with the glass envelope 5. Moreover, a pair of getters 23 and 25 are attached to the support member 15 and serve to insure the 10 integrity of the evacuated envelope 5.
Disposed within the glass envelope 5 and supported by the crossbars 17 and 19 is an arc tube 27. This arc tube 27, preferably of a material such as polycrystalline alumina for example, includes an electrode 29 and 31 at either end thereof. One electrode 29 is 15 affixed to and supported by the crossbar 17 while the other electrode 31 is insulatingly supported by the other crossbar 19, but electrically connected to the electrical conductor 13 passing -through the stem member 9. Heat conserving elements 33 may be wrapped about the arc tube 27 at each end thereof in the vicinity of 20 the electrodes 29 and 31 in order to reduce the heat differential thereat from the center of the arc tube 27.
Referring more specifically to FIG. 2 wherein à getter 37 is disposed within the arc tube 27 of FI5. 1, an electrode member 39 is sealed into an apertured ceramic 41 which is, in turn, sealed into 25 the end of a tubular ceramic envelope of an arc tube. Similarly, the opposite end of the tubular ceramic envelope is sealed in substantially the ~same manner.
The electrode member 39 includes a shank portion 43 which has a substantially circularly-wound cathode portion 45 telescoped 30 thereover and affixed thereto, as by welding for example. Also affixed to the shank portion 43 intermediate the cathode portion 45 and the apertured ceramic 41 is the getter 37.
Preferably, the getter 37 is in the form of a suitable substrate 47, such as nickel plated iron, and a gettering material 49, such as 35 zirconium-aluminum powder, is sintered thereto. Thera~ter, the D-~3-1-021 ~2Z~274 substrate 47 is affixed to or telescoped over the shank portion 43 of the electrode member 39. Although a preferred gettering material is a zirconiu~-aluminum alloy known as ST-101~ available from SAES
Getters, Milan, Italy, other metals are equally applicable. For example, metal alloys selected from the metal group consisting of aluminum5 titanium, scandium, cerium, lanthanum, thoriu~, zirconium, yttrium and other rare earth oxides are suitable getter;ng materials for the above-described configurations.
Additionally, alternative methods of containing a getter material within the ceramic envelope of the arc tube and separated therefrom are appropriate. For example, a small tab containing a gettering material could be affixed to the electrode or alternatively, the getter material could be applied to the wound cathode portion 45 of the electrode member 39. Obviously, other configurations of a similar nature are appropriate to the structure so long as the gettering material is separated from the ceramic envelope of the arc tube.
While there has been shown and described what is at present considered the preferred embodiments of the invention, it will be - ~o obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention as defined by the appended claims.
CROSS REFE~NCE TO OTHER APPLICATIONS
The following concurrently filed Canadian patent applications relate to unsaturated vapor pressure type high pressure sodium lamps and the fabrication thereof:
448,953-5; 448.916-1; 448,954-3; and 448,915-2.
TECHNICAL FIELD
This invention relates to unsaturated vapor high pressure sodium lamps and more particularly to the mounting of getters within the arc tube of an unsaturated vapor high pressure sodium lamp.
BACKGROUND ART
In the field of high pressure sodium lamp6, it i8 a common practice to provide an arc tube fill which includes a large amount of sodium and mercury in order to compensate for the undesired sodium lo~ses encountered.
These excess amounts of sodium and mercury re~ult in an amalgam at the coolest points of the arc tube which normally adjacent the electrodes at the ends of the arc tube. As a result, undesired variations in source voltage, color rendition and numerous other characteristics are encountered.
. ~`~',.'~
.
1~2%~
In an effort to eliminate or at least reduce such undesired effects, it has lon~ been known that a lamp wherein the amount of sodium and mercury employed is only that which will becom~ totally vaporized would provide the desired rasult. In other words, a high pressure sodium lamp of the unsaturated vapor type wherein sodium and mercury are introduced in only such an ~nount as to become totally vaporiæed is a highly desirable structure insofar as efficiency, cost of manufactur~ and enhanced lighting capability are concerned.
Also, it has long been recognized that a principal cause of undesired sodium loss in high presure sodium lamps is the presence of oxygen in the gas fill of the arc tube. One known att~pt to alleviate this undesired loss of sodium due to the presence of oxyg~n is set forth in a concurrently filed Canadian patent application, S~rial ~o. 448,953-5, of Philip J. White entitled ~'Unsaturated Vapor Pressure Type High Pressure Sodium Lamp", assi~ned to the Assignee of the present application. Therein, a getter in the form of a metal or metal alloy is located within an elongated ceramic arc tube with the metal oxides of the getter having a free energy of formation per mole of oxygen greater than that of sodium oxide. In effect, the getter reacts with Eree oxygen to inhibit the formation of compounds containing sodium and oxygen.
Although the above-described technique has been employed with var~ing amounts of success, it has been found that the results do leave something to be desired. ~ore specifically, it has be~n found that intimate contact between the tubular ceramic envelope of the arc tube and the oxygen-absorbing getter therein tends to cause an undesired darkening of the ceramic envelope in the area of contact with the getter material. Althou~h the exact cause of this darkening condition of the ceramimc envelope is not thoroughly understood, it is believed that a chemical reduction takes place between the getter and the aluminum envelope whereat contact therebetween is effected.
` ~-83-1-0~1 ~222274 OBJECTS AND SUMMARY OF THE INVENTION
An object of the present inYention is to provide an improved high pressure sodium lamp. Another object of the invention is to enhance the arc tube of an unsaturated vapor high pressure sodium lamp. A further object of the invention is the structure of an unsaturated vapor high pressure sodium lamp.
These and other objects, advantages and capabilities are achieved in one aspect of the invention by an arc tube having a tubular ceramic envelope with an electrode sealed into each end of the envelope, a dosing of sodium, mercury and rare gas within the envelope and an oxygen-absorb;ng getter attached to at least one of the electrodes within the ceramic envelope.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is an elevational view of a preferred form of unsaturated vapor high pressure sodium lamp; and FI6. 2 is an exploded sectional view of an electrode formed for enclosure within a ceramic envelope and having an oxygen-absor~ing getter affixed thereto.
BEST MODE FOR CARRYING OUT THE INVENTION
For a better understanding of the present invention, together with other and further objects, advantages and capabilities thereof, ,~
reference is made to the following disclosure and appended claims in conjunction with the accompanying drawings.
Referring to the drawings, FIG. 1 illustrates an unsaturated vapor high pressure sodium lamp having a hermetically sealed and evacuated glass envelope 5 formed to fit into an ordinary screw-type base member 7. A glass stem member 9 is sealed to the envelope and projects therein. Electrical conductors, 11 and 13 D-~3-1-021 ~LZ2;~274 respectively, are sealed into and pass through the stem member 9 to provide electrical connections from the interior to the exterior of the glass envelope 5.
An electrically conductive support member 15 is affixed to one 5 of the electrical conductors 11 and has a pair of crossbars 17 and 19 affixed thereto at either end. Also, a plurality of spring-like members 21 are affixed to the support member 15 and formed for contact with the glass envelope 5. Moreover, a pair of getters 23 and 25 are attached to the support member 15 and serve to insure the 10 integrity of the evacuated envelope 5.
Disposed within the glass envelope 5 and supported by the crossbars 17 and 19 is an arc tube 27. This arc tube 27, preferably of a material such as polycrystalline alumina for example, includes an electrode 29 and 31 at either end thereof. One electrode 29 is 15 affixed to and supported by the crossbar 17 while the other electrode 31 is insulatingly supported by the other crossbar 19, but electrically connected to the electrical conductor 13 passing -through the stem member 9. Heat conserving elements 33 may be wrapped about the arc tube 27 at each end thereof in the vicinity of 20 the electrodes 29 and 31 in order to reduce the heat differential thereat from the center of the arc tube 27.
Referring more specifically to FIG. 2 wherein à getter 37 is disposed within the arc tube 27 of FI5. 1, an electrode member 39 is sealed into an apertured ceramic 41 which is, in turn, sealed into 25 the end of a tubular ceramic envelope of an arc tube. Similarly, the opposite end of the tubular ceramic envelope is sealed in substantially the ~same manner.
The electrode member 39 includes a shank portion 43 which has a substantially circularly-wound cathode portion 45 telescoped 30 thereover and affixed thereto, as by welding for example. Also affixed to the shank portion 43 intermediate the cathode portion 45 and the apertured ceramic 41 is the getter 37.
Preferably, the getter 37 is in the form of a suitable substrate 47, such as nickel plated iron, and a gettering material 49, such as 35 zirconium-aluminum powder, is sintered thereto. Thera~ter, the D-~3-1-021 ~2Z~274 substrate 47 is affixed to or telescoped over the shank portion 43 of the electrode member 39. Although a preferred gettering material is a zirconiu~-aluminum alloy known as ST-101~ available from SAES
Getters, Milan, Italy, other metals are equally applicable. For example, metal alloys selected from the metal group consisting of aluminum5 titanium, scandium, cerium, lanthanum, thoriu~, zirconium, yttrium and other rare earth oxides are suitable getter;ng materials for the above-described configurations.
Additionally, alternative methods of containing a getter material within the ceramic envelope of the arc tube and separated therefrom are appropriate. For example, a small tab containing a gettering material could be affixed to the electrode or alternatively, the getter material could be applied to the wound cathode portion 45 of the electrode member 39. Obviously, other configurations of a similar nature are appropriate to the structure so long as the gettering material is separated from the ceramic envelope of the arc tube.
While there has been shown and described what is at present considered the preferred embodiments of the invention, it will be - ~o obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention as defined by the appended claims.
Claims (10)
1. In a high pressure sodium lamp of the unsaturated vapor type, an arc tube comprising:
a tubular ceramic envelope;
a dosing of sodium, mercury and a rare gas within said ceramic envelope;
an electrode sealed into each end of said ceramic envelope; and an oxygen-absorbing getter located within said ceramic envelope and in contact with said dosing and contiguous to at least one of said electrodes.
a tubular ceramic envelope;
a dosing of sodium, mercury and a rare gas within said ceramic envelope;
an electrode sealed into each end of said ceramic envelope; and an oxygen-absorbing getter located within said ceramic envelope and in contact with said dosing and contiguous to at least one of said electrodes.
2. The arc tube of Claim 1 wherein said oxygen-absorbing getter is located within and spaced from said tubular ceramic envelope.
3. The arc tube of Claim 1 wherein said oxygen-absorbing getter is affixed to a substrate-which is affixed to one of said electrodes within said tubular ceramic envelope.
4. The arc tube of Claim 1 wherein said oxygen-absorbing getter is in the form of a metal powder sintered onto a substrate attached to one of said pair of electrodes within said tubular ceramic envelope.
5. The arc tube of Claim 1 wherein said oxygen-absorbing getter selected from a group consisting of aluminum, titanium, scandium, hafnium, cerium, lanthanum, thorium, yttrium and zirconium.
6. The arc tube of Claim 1 wherein sodium and mercury of said dosing within said tubular envelope are in the form of an amalgam decomposable within said lamp to provide said mercury and said sodium and oxygen which is absorbed by said oxygen-absorbing getter.
7. The arc tube of Claim 1 wherein said tubular ceramic envelope is in the form of a tubular polycrystalline aluminum envelope
8. In an unsaturated type high pressure sodium lamp having a tubular ceramic envelope containing a dosing of sodium, mercury and rare gas with an electrode member sealed into each end of the tubular ceramic envelope, the improvement comprising an oxygen-absorbing getter affixed to at least one of said electrode members.
9. The improvement of claim 8 wherein said oxygen-absorbing getter is spaced from said tubular ceramic envelope.
10. The improvement of Claim 8 wherein said oxygen-absorbing getter is in the form of a zirconium-aluminum alloy sintered to a substrate and contiguous to at least one of said electrode members.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US47389783A | 1983-03-10 | 1983-03-10 | |
| US473,897 | 1983-03-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1222274A true CA1222274A (en) | 1987-05-26 |
Family
ID=23881474
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000448955A Expired CA1222274A (en) | 1983-03-10 | 1984-03-06 | Unsaturated vapor high pressure sodium lamp getter mounting |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0119082B1 (en) |
| JP (1) | JPS59169051A (en) |
| AU (1) | AU578602B2 (en) |
| CA (1) | CA1222274A (en) |
| DE (1) | DE3475853D1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB8623296D0 (en) * | 1986-09-27 | 1986-10-29 | Emi Plc Thorn | Hydrogen getter |
| US5434472A (en) * | 1992-04-15 | 1995-07-18 | United States Philips Corporation | High-pressure sodium discharge lamp with getter |
| DE4325679A1 (en) * | 1993-07-30 | 1995-02-02 | Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh | Electric lamp with halogen filling |
| US20070096649A1 (en) * | 2005-10-28 | 2007-05-03 | Roels Timothy J | Electrode-mounted getter |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1211176A (en) * | 1967-02-16 | 1970-11-04 | Gen Electric | High-pressure sodium vapor lamp |
| US3453477A (en) * | 1967-02-16 | 1969-07-01 | Gen Electric | Alumina-ceramic sodium vapor lamp |
| US3485343A (en) * | 1967-08-28 | 1969-12-23 | Gen Electric | Oxygen getter for high pressure sodium vapor lamp |
| NL7315641A (en) * | 1973-11-15 | 1975-05-20 | Philips Nv | HIGH PRESSURE GAS DISCHARGE LAMP. |
| US4075530A (en) * | 1976-04-21 | 1978-02-21 | Japan Storage Battery Company Limited | High pressure sodium vapor lamp of unsaturated vapor pressure type |
| NL7611137A (en) * | 1976-10-08 | 1978-04-11 | Philips Nv | HIGH PRESSURE DISCHARGE LAMP. |
| CA1214196A (en) * | 1983-02-14 | 1986-11-18 | Jack M. Strok | Color rendition high pressure sodium arc tubes having an oxygen getter |
-
1984
- 1984-03-06 CA CA000448955A patent/CA1222274A/en not_active Expired
- 1984-03-09 AU AU25477/84A patent/AU578602B2/en not_active Ceased
- 1984-03-09 EP EP84301610A patent/EP0119082B1/en not_active Expired
- 1984-03-09 JP JP59044158A patent/JPS59169051A/en active Pending
- 1984-03-09 DE DE8484301610T patent/DE3475853D1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| EP0119082A3 (en) | 1985-06-19 |
| AU578602B2 (en) | 1988-11-03 |
| EP0119082A2 (en) | 1984-09-19 |
| JPS59169051A (en) | 1984-09-22 |
| EP0119082B1 (en) | 1988-12-28 |
| AU2547784A (en) | 1984-09-13 |
| DE3475853D1 (en) | 1989-02-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |