CA1194096A - Method of producing a low-pressure mercury vapour discharge lamp and low-pressure mercury vapour discharge lamp produced by means of said method - Google Patents
Method of producing a low-pressure mercury vapour discharge lamp and low-pressure mercury vapour discharge lamp produced by means of said methodInfo
- Publication number
- CA1194096A CA1194096A CA000400127A CA400127A CA1194096A CA 1194096 A CA1194096 A CA 1194096A CA 000400127 A CA000400127 A CA 000400127A CA 400127 A CA400127 A CA 400127A CA 1194096 A CA1194096 A CA 1194096A
- Authority
- CA
- Canada
- Prior art keywords
- container
- discharge vessel
- mercury
- amalgam
- alloy
- 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
- H01J61/70—Lamps with low-pressure unconstricted discharge having a cold pressure < 400 Torr
- H01J61/72—Lamps with low-pressure unconstricted discharge having a cold pressure < 400 Torr having a main light-emitting filling of easily vaporisable metal vapour, e.g. mercury
-
- 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
- H01J61/28—Means for producing, introducing, or replenishing gas or vapour during operation of the lamp
Landscapes
- Manufacture Of Electron Tubes, Discharge Lamp Vessels, Lead-In Wires, And The Like (AREA)
Abstract
ABSTRACT:
Method of producing a low-pressure mercury vapour discharge lamp having a discharge vessel, a metal or an alloy which forms an amalgam with mercury being provided in the discharge vessel before the desired gas atmosphere is established in the discharge vessel and the discharge vessel is sealed in a vacuum-tight manner, at least the metal or alloy being in a closed con-tainer which is provided near a portion of the interior wall of the discharge vessel, the container being opened after the discharge vessel has been sealed in a vacuum-tight manner, at least a portion of the metal or the alloy then leaving the container and moving to the interior wall portion located near the container.
Method of producing a low-pressure mercury vapour discharge lamp having a discharge vessel, a metal or an alloy which forms an amalgam with mercury being provided in the discharge vessel before the desired gas atmosphere is established in the discharge vessel and the discharge vessel is sealed in a vacuum-tight manner, at least the metal or alloy being in a closed con-tainer which is provided near a portion of the interior wall of the discharge vessel, the container being opened after the discharge vessel has been sealed in a vacuum-tight manner, at least a portion of the metal or the alloy then leaving the container and moving to the interior wall portion located near the container.
Description
PHN 10,009 1 1-12~1981 "Method of producing a low-pressure mercury vapour di~s-charge lamp ~nd lo~-pressure mercury vapour discharge lamp produced by means of said method".
The invention relates to a method o~ produoing a low-pressure mercury vapour discharge lamp having a discharge vessel, a-t least a metal or an alloy which forms an amalgam with mercury being disposed in -the discharge vessel before the desired gas atmosphere is established in the discharge vessel and the discharge vessel is closed in a vacuum-tight manner. Such a method is disclosed in USP 4,157,4~5 (PHN 8O57). The in~ention further relates to lamps produced by means of such a method.
In ~he prior art method an alloy of indium and bismuth (the amalgam-forming component) are pressed to form a ductile wire the end of which is thereafter heated to a temperature just above the melting point of said alloy and is sprayed onto a portion of the lamp wall According to the said Patent Specification this portion is preferably the foot o~ the stem. Such a stem carries, for example, an electrode, an au~iliary electrode, leading-in wires and similar elementsO The use of the said stems (which are o~te~
provided with an ex~aust tube) is customary in the product~
ion of low-pressu~e mercury vapour discharge lamps. The stems and accesories (such as leading-in wires, electrodes etc.) are first produced separately ~rom the other lamp components. ~he indium and bismu-th alloy is applied onto the ~oot o~ the stem before the stem is sealed in a vacuum-tight manner to the discharge vessel. Thereafter the lamp ispumped (that is to say the walls and the othe~ lamp com-ponents are outgassed, the electrodes are annealed and outgassed, the discharge vesse] is filled with the re~uired gas atmosphere etc~)~ Thereafter the discharge vessel is closed in a vacuum-tight manner by sealing the e~haust tube.
Thereafter the discharge vessel is filled with mercury, for example by heating a glass container which comprises the ; mercury and is present in the discharge vessel (see g~
PHN 1~.009 -2- 1-12-1981 G~-PS 1,267,175~. Then at least a portion of the mercury iIl combination with the amalgam-forming component ~orms an amalgam for the control o~ the mercury vapour pressure in the discharge vessel during operation of the lamp.
One o~the problems encountered in said method is that the consecutive operations during the production o:~ the lamp, during whi-ch the temperature rises to a com-paratively high value (~or e~amplc during sealing of the stem to the wall of the discharge vessel.or during the indispensable heating of components, for example out-gassing of the electrodes, activation o~ the electrodes e-t~) oxidizing of the amalgam-~orming alloy or the amalgam-~orming metal .easily occurs, a thin oxide layer -then being formed on the metal or the alloy, which during operation Of the lamp greatly impedes the absorption and release of mercury (which is necessary for a proper operation of an amalgam). In addi-tion, with the known method i-t is di~ficult to dose the quantity of tha amalgam-~orming component accurately.
The invention has for its object to.provide a me-thod o~ producing a low-pressure mercury ~apour discharge lamp which mitigates these drawbacks, wherein attack of tha amalgam-~orming alloy and the amalgam-forming metal, respectively, by oxidation is prevented ~rom occurring.
According to the invention, the method o~ pr~-ducing a low pressure mercury vapour discharge lamp is characterized in that at leas-t the amalgam-forming alloy or the amalgam-~orming metal is present in a closed con-tainer which is provided near a portion o~ the in-terior wall of the discharge vessel, which container is opened after the discharge vessel has been closed in a vacuum~
tight manner, at least a portion o~ the alloy or the metal then leaving the container ~nd moving ~o -the interior wall portion located near the container.
In the method in accordance with the invention the amalgam-~orming metal and the amalgam-~orming alloy 9 respectively are not exposed to a hot~ oxygen-containing - atmosphere, so that no o~ide layer is formed on the alloy ~9~
PHN IO.OO9 -3- 1-12-1981 and metal, respectively. Namely, during the entire pro-cedure the metal or the alloy are located in a closed con-tainer which is not opened until the discharge ~essel has been closed in a vacuum-tight manner.
An additional advantage o~ the method in acordance with the invention is -tha-t the amalgam-forming ~etal or the alloy can be applied in very accurate doses in the discharge ~essel. The ratio o~ the quanit~ of metal and alloy, respec-tively~ to the quantity of mercury in the lamp is accura-tely determined. The temperature range in which the mercury vapour ~ressure is substantially stable during operation o~ the lamp is then as wide as possible.
In this method it is not necessary that the entire content of the container moves to the wall portion located near the container. An adequate control o~ the mercury vapour pressure is obtained even if a portion o~ the content, ~or example hal~ the content, remains in the container. During operation of the lamp, the absorption and releasa o~ mercury ~rom the portion of the amalgam located in the con-tainer proceeds _ia the opening in the container wall.
Pre~erably the container is provided in a compa-ratively cool spot in the discharge vessel1 for example in a position behind the elec-trode near an end o~ the dischar-ge vessel. In one embodiment the opening is pro~idedinsuch a place in the container that a portion o~ the con-tent moves *o a posi-tion near the electrode ~or e~ample the pinch or a ring or band around the electrode). During operation of the lamp an amalgam ~hich has almost exclusi-vely a ~apour pressure-controlling function forms in the container with the mercury present in the discharge vessel, the material present in a place near the electrode being *ree ~rom mercury during operation. Only during extinguish-ing of the lamp said material absorbs some mercury whichS
however, when the lamp is switched on, is released from the amalgam in response to the rapid increase o:~ -the tempera~
ture there 7 as a result o~ which the lamp readily igni*es.
` J The `container iS 0~ such a shape and is so a~
P~IN 10.009 l~ 12-1981 positioned in the discharge vessel that the material which is released on the opening of the container moves as rapidly as possible to a discharge vessel wall portion near the container. The container consis-ts 9 for example, of glass or me-tal. In a practical embodiment the container is formed by two metal parts which are welded toge-ther, one part being provided with a recess in which the amalgam-forming ma-terial is present. The container is connec-ted to the stem or to a supply wire of an electrode by means of, for e~ample, a wire.
A container of this type metal is opsned by, for e~Yample, inductive heating~ The container then bursts open in a weak spot in the wall specially provided for that purpose. The weak spot faces, for example~ and is located at a s~all distance from the wall portion of the discharge vessel on ~hich at least the amalgam-forming component is provided. In a practical embodiment of the method the con-tainer is opened by means of a laser beam which is focused onto the wall of the container~
The mercury required for the operation of the lamp may be dosed in the discharga vessel separately from the amalgam-~orming alloy and the amalgam-forming mstal, respectively, for example by means of a glass mercury container described in the United Kingdom Patsnt Speci~
25 cation 1,267,175 mentioned already in the foregoing.
Preferably, in the method in accordance with -the invention, the mercury required for the operation of the lamp is placed together with the said amalgam-forming component in the container and provided on the wall of the discharge 3~ vessel. No additional step for the separa-te dosing of the mercury is then required. A fur-ther advantage in this em-bodiment is -that the container holding the amagam opens rapidly when being heated as a res~lt of the mercury vapour pressure which rapidly increases as a function o~ -tem-perature. The mutual ratio of the elements which are partof the arnalgam may moreover be determined very accurately, so that a proper opera-tion of the amalgam during operation of -the lamp is obtained.
PHN 10.009 -5- 1-12-1981 The amalgam may be composed o~ mercury and a metal, such as indium, tin, or lead or alternatively o~
mercury and an alloy 9 such as an alloy o~ indium and bismuthO In a practical embodiment of the method in accord-ance with the invention a mi~ture o~ an alloy o~ indiumand mercury is ~irst placed together with bismuth in a closed metal container, a spherical bismuth member being positioned on a ductile tablet o~ the indium and mercury alloy. The spherical members and the tablets can be mass-produced in a simple way. 1~hen the spherical bismu-th member is positioned in the holder it is enveloped substan-tially wholly by the ductile mass o~ the indium and mercury alloy~
The spherical member and the ductile mass are therea~-ter heated ~or some time~ which results in a proper mi~ing ~ the said elements. The holder is o~ such a shape that the amalgam is tightly enclosed and unwanted trapping o~
gas is avoidedO It has ~een found that the said elements can be eas-ly positioned in the container in a mechanized process.
In low-pres-sure mercury vapour discharge lamps produced by means o~ the method the mercury vapour pres-sure remains reasonably stable over a wide temperature range around 6 x ~0 3 Torr ~o.8 Pascal). Lamps o~ this t~pe, having an amalgam, are, ~or e~ample, suitable ~or use in places where the ambient te.nperature is high.
In addition, the me-thod can be used with great . advantage in small discharge lamps~ for e~ample in lamps having a shape as described in DE-OS 2,940,563-(P~IN 92l~2).
In this type o~ lamp -the temperature in -the discharge vessel is rather high during operation~ T'n3 pre~ence a~ outer envelope reduces the heat discharge ~rom the discharge vessel.
An opening o~ the container is per~ormed, as mentioned in the ~oregoing, wholly separately ~rom the ~urther operations on the lamp, it is optionally possible to market discharge vessels which are closed in a vacuum-tight manner, but which still include a closed container.
This container may then be opened later at a suitable P~IN IO.OO9 -6~ 12-1981 moment~ *or example by the buyer of these "lamps". This operation is namely so simple (particularly if high-*re-quency inductive hea-ting or a converging laser beam is used) that a buyer can per~orm these operations without elaborate equipment. ~ll -this has the advan-tage that during trans-portation of the "lamps" the amalgam-*orming metal or the amalgam-forming alloy cannot become detached from the lamp wall; should these "lamps" containing amalgams break during transportation no mercury vapour can be released into the environment. The invention -there*ore also relates to discharge vessels o* -this type.
The invention will now be further described by-way o* e~ample with reference to a drawing in which Fig. 1 shows an embodiment o* a low-pressure mer-cury vapour discharge lamp produced by means o* a method in accordance with the invention and Fig. 2 shows one end, partly in cross-sectional view, o* a discharge vessel containing a container still to be opened.
In ~i-g. 1 reference numeral I denotes the wall o~ a tubular discharge vessel o* a low-pressure mercury vapour discharge lamp, stems 2 and 3 with electrodes ~ and 5~ respectively being provided one at each end. The interior wall of the discharge vessel is coated with a 25 luminescent layer 6 consisting, *or example 9 of a mixture o* trivalent europium-activated yttrium-oxide and tri~
valent terbium-activated cerium magnesium aluminate~ A
metal wire 7, which is connec-ted -to a metal container 8 located behind the elec-trodes is welded to one o* the 30 current supply wires of electrode 4. The wall portion near said container (the *oot 9 of the stem 2~ is provided with an amalgam. Said amalgam is applied by means o* a methocl in accordance with the inventionO The amalgam is provided in a cool spot, w~ich is advantageous ~or the 35 con-trol of the mercury vapour pressura in the discharge vessel, behind the electrode 4.
During the production o* the lamp the in-terior wall o* a tube is ~irst coated by means o* a known method "~
PIIN 10.009 - 7_ 1-12 - I981 wi-tn a luminescent layer, whereafter the stems are connected in a vacuum-tight manner to the wall o~ the tube. ~aid s-tems~have a closed metal con-tainer 8 which conta;ns an amalgam. Thereafter the discharge vessel is exhausted (by means of an exhaust tube 10 connected to one of the stems), the rare gas atmosphere is established and the discharge vessel is closed in a vacuum-tigh-t manner by sealing the exhaust tube. Not until thereafter is the metal con-tainer 8 opened by directing a focussed laser beam onto the wall of the con;tainer so as to make an opening therein. At least a portion of the amalgam leaves the container through the opening as a syrupy liquid and moves to the foot 9 of the stem, where it adheres.
Fig. 2 shows one end of a discharge vessel at the moment at which all operations on the lamps except the release of the amalgarn have been finished. Said amalgam is in the container 8 which is still in the closed condition.
The container 8 is formed by two sheet metal portions 8a and 8b (for example consisting of iron or nickel) which are welded together, 8b having been provided with a recess in which an amalgam 11 consisting of indium, bismuth and mercury is provided. The amalgam is obtained by heating a small sphere of bismuth which is enclosed by a quantity of a ductile alloy of indium and mercury~ It has been found that the bismuth is then very rapidly absorbed by the alloy and ~orms a homogeneous/somewhat liquid compound. The metal portions 8a and 8b fi-t around arnalgam 11 in such a way that no unwanted gasses are trapped in the container~ The container 8 is opened by means of a laser arranged ou-tside the discharge vessel. An opening is drilled in a portion 12 of 8a by ~ocussing the laser beam. The -temperature then in-craases to such a value that a portion of the amalgarn flows from the contair~er 8.
In a practical embodiment, the wall portion 9 wh~re a portion of the amalgam arrives is located at only a few mm (~or example 2mm) ~rom portion 12. The use of a converging laser beam to form the opening has the advantage that the further portions (~or exarnple 1 and 2) o~ the PHN 10.009 ~ 12-1981 glass wall of -the disoharge vessel are not attacked by the laser light. Moreover~ the energy of the laser light can be concentrated such -that even amalgam-~orming com-ponents having a low vapour pressure (such as indium or bismuth) become syrupy when -the opening is formed.
In an alternative embodiment the container is inductively hea-ted, a wecik spot having been provided in the container wall ~lere -the container is opened.
A practical embodiment o~ a lamp shown in ~ig. 1 produced by means of a method in accordance with the in-vention contained 26.8 mg Bi, 13.2 mg In and 3.0 mg Hg (in wt.7b 62.30/o Bi~ 30.7%' In, 7% Hg). The container was formed of two metal portions which are welded together and one o~ ~hich is provided with a recess, An opening (diameter 0.~7 mmj was formed in the container ~y means o~ a pulsed Nd-YAG laser (pulse energy appro~imately 2 J).
~t an applied power o~ 13 W -the lamp (having argon, 267 Pa, as rare gas filling~ had a luminous flux of approxima~
tely 900 Lumen.
The invention relates to a method o~ produoing a low-pressure mercury vapour discharge lamp having a discharge vessel, a-t least a metal or an alloy which forms an amalgam with mercury being disposed in -the discharge vessel before the desired gas atmosphere is established in the discharge vessel and the discharge vessel is closed in a vacuum-tight manner. Such a method is disclosed in USP 4,157,4~5 (PHN 8O57). The in~ention further relates to lamps produced by means of such a method.
In ~he prior art method an alloy of indium and bismuth (the amalgam-forming component) are pressed to form a ductile wire the end of which is thereafter heated to a temperature just above the melting point of said alloy and is sprayed onto a portion of the lamp wall According to the said Patent Specification this portion is preferably the foot o~ the stem. Such a stem carries, for example, an electrode, an au~iliary electrode, leading-in wires and similar elementsO The use of the said stems (which are o~te~
provided with an ex~aust tube) is customary in the product~
ion of low-pressu~e mercury vapour discharge lamps. The stems and accesories (such as leading-in wires, electrodes etc.) are first produced separately ~rom the other lamp components. ~he indium and bismu-th alloy is applied onto the ~oot o~ the stem before the stem is sealed in a vacuum-tight manner to the discharge vessel. Thereafter the lamp ispumped (that is to say the walls and the othe~ lamp com-ponents are outgassed, the electrodes are annealed and outgassed, the discharge vesse] is filled with the re~uired gas atmosphere etc~)~ Thereafter the discharge vessel is closed in a vacuum-tight manner by sealing the e~haust tube.
Thereafter the discharge vessel is filled with mercury, for example by heating a glass container which comprises the ; mercury and is present in the discharge vessel (see g~
PHN 1~.009 -2- 1-12-1981 G~-PS 1,267,175~. Then at least a portion of the mercury iIl combination with the amalgam-forming component ~orms an amalgam for the control o~ the mercury vapour pressure in the discharge vessel during operation of the lamp.
One o~the problems encountered in said method is that the consecutive operations during the production o:~ the lamp, during whi-ch the temperature rises to a com-paratively high value (~or e~amplc during sealing of the stem to the wall of the discharge vessel.or during the indispensable heating of components, for example out-gassing of the electrodes, activation o~ the electrodes e-t~) oxidizing of the amalgam-~orming alloy or the amalgam-~orming metal .easily occurs, a thin oxide layer -then being formed on the metal or the alloy, which during operation Of the lamp greatly impedes the absorption and release of mercury (which is necessary for a proper operation of an amalgam). In addi-tion, with the known method i-t is di~ficult to dose the quantity of tha amalgam-~orming component accurately.
The invention has for its object to.provide a me-thod o~ producing a low-pressure mercury ~apour discharge lamp which mitigates these drawbacks, wherein attack of tha amalgam-~orming alloy and the amalgam-forming metal, respectively, by oxidation is prevented ~rom occurring.
According to the invention, the method o~ pr~-ducing a low pressure mercury vapour discharge lamp is characterized in that at leas-t the amalgam-forming alloy or the amalgam-~orming metal is present in a closed con-tainer which is provided near a portion o~ the in-terior wall of the discharge vessel, which container is opened after the discharge vessel has been closed in a vacuum~
tight manner, at least a portion o~ the alloy or the metal then leaving the container ~nd moving ~o -the interior wall portion located near the container.
In the method in accordance with the invention the amalgam-~orming metal and the amalgam-~orming alloy 9 respectively are not exposed to a hot~ oxygen-containing - atmosphere, so that no o~ide layer is formed on the alloy ~9~
PHN IO.OO9 -3- 1-12-1981 and metal, respectively. Namely, during the entire pro-cedure the metal or the alloy are located in a closed con-tainer which is not opened until the discharge ~essel has been closed in a vacuum-tight manner.
An additional advantage o~ the method in acordance with the invention is -tha-t the amalgam-forming ~etal or the alloy can be applied in very accurate doses in the discharge ~essel. The ratio o~ the quanit~ of metal and alloy, respec-tively~ to the quantity of mercury in the lamp is accura-tely determined. The temperature range in which the mercury vapour ~ressure is substantially stable during operation o~ the lamp is then as wide as possible.
In this method it is not necessary that the entire content of the container moves to the wall portion located near the container. An adequate control o~ the mercury vapour pressure is obtained even if a portion o~ the content, ~or example hal~ the content, remains in the container. During operation of the lamp, the absorption and releasa o~ mercury ~rom the portion of the amalgam located in the con-tainer proceeds _ia the opening in the container wall.
Pre~erably the container is provided in a compa-ratively cool spot in the discharge vessel1 for example in a position behind the elec-trode near an end o~ the dischar-ge vessel. In one embodiment the opening is pro~idedinsuch a place in the container that a portion o~ the con-tent moves *o a posi-tion near the electrode ~or e~ample the pinch or a ring or band around the electrode). During operation of the lamp an amalgam ~hich has almost exclusi-vely a ~apour pressure-controlling function forms in the container with the mercury present in the discharge vessel, the material present in a place near the electrode being *ree ~rom mercury during operation. Only during extinguish-ing of the lamp said material absorbs some mercury whichS
however, when the lamp is switched on, is released from the amalgam in response to the rapid increase o:~ -the tempera~
ture there 7 as a result o~ which the lamp readily igni*es.
` J The `container iS 0~ such a shape and is so a~
P~IN 10.009 l~ 12-1981 positioned in the discharge vessel that the material which is released on the opening of the container moves as rapidly as possible to a discharge vessel wall portion near the container. The container consis-ts 9 for example, of glass or me-tal. In a practical embodiment the container is formed by two metal parts which are welded toge-ther, one part being provided with a recess in which the amalgam-forming ma-terial is present. The container is connec-ted to the stem or to a supply wire of an electrode by means of, for e~ample, a wire.
A container of this type metal is opsned by, for e~Yample, inductive heating~ The container then bursts open in a weak spot in the wall specially provided for that purpose. The weak spot faces, for example~ and is located at a s~all distance from the wall portion of the discharge vessel on ~hich at least the amalgam-forming component is provided. In a practical embodiment of the method the con-tainer is opened by means of a laser beam which is focused onto the wall of the container~
The mercury required for the operation of the lamp may be dosed in the discharga vessel separately from the amalgam-~orming alloy and the amalgam-forming mstal, respectively, for example by means of a glass mercury container described in the United Kingdom Patsnt Speci~
25 cation 1,267,175 mentioned already in the foregoing.
Preferably, in the method in accordance with -the invention, the mercury required for the operation of the lamp is placed together with the said amalgam-forming component in the container and provided on the wall of the discharge 3~ vessel. No additional step for the separa-te dosing of the mercury is then required. A fur-ther advantage in this em-bodiment is -that the container holding the amagam opens rapidly when being heated as a res~lt of the mercury vapour pressure which rapidly increases as a function o~ -tem-perature. The mutual ratio of the elements which are partof the arnalgam may moreover be determined very accurately, so that a proper opera-tion of the amalgam during operation of -the lamp is obtained.
PHN 10.009 -5- 1-12-1981 The amalgam may be composed o~ mercury and a metal, such as indium, tin, or lead or alternatively o~
mercury and an alloy 9 such as an alloy o~ indium and bismuthO In a practical embodiment of the method in accord-ance with the invention a mi~ture o~ an alloy o~ indiumand mercury is ~irst placed together with bismuth in a closed metal container, a spherical bismuth member being positioned on a ductile tablet o~ the indium and mercury alloy. The spherical members and the tablets can be mass-produced in a simple way. 1~hen the spherical bismu-th member is positioned in the holder it is enveloped substan-tially wholly by the ductile mass o~ the indium and mercury alloy~
The spherical member and the ductile mass are therea~-ter heated ~or some time~ which results in a proper mi~ing ~ the said elements. The holder is o~ such a shape that the amalgam is tightly enclosed and unwanted trapping o~
gas is avoidedO It has ~een found that the said elements can be eas-ly positioned in the container in a mechanized process.
In low-pres-sure mercury vapour discharge lamps produced by means o~ the method the mercury vapour pres-sure remains reasonably stable over a wide temperature range around 6 x ~0 3 Torr ~o.8 Pascal). Lamps o~ this t~pe, having an amalgam, are, ~or e~ample, suitable ~or use in places where the ambient te.nperature is high.
In addition, the me-thod can be used with great . advantage in small discharge lamps~ for e~ample in lamps having a shape as described in DE-OS 2,940,563-(P~IN 92l~2).
In this type o~ lamp -the temperature in -the discharge vessel is rather high during operation~ T'n3 pre~ence a~ outer envelope reduces the heat discharge ~rom the discharge vessel.
An opening o~ the container is per~ormed, as mentioned in the ~oregoing, wholly separately ~rom the ~urther operations on the lamp, it is optionally possible to market discharge vessels which are closed in a vacuum-tight manner, but which still include a closed container.
This container may then be opened later at a suitable P~IN IO.OO9 -6~ 12-1981 moment~ *or example by the buyer of these "lamps". This operation is namely so simple (particularly if high-*re-quency inductive hea-ting or a converging laser beam is used) that a buyer can per~orm these operations without elaborate equipment. ~ll -this has the advan-tage that during trans-portation of the "lamps" the amalgam-*orming metal or the amalgam-forming alloy cannot become detached from the lamp wall; should these "lamps" containing amalgams break during transportation no mercury vapour can be released into the environment. The invention -there*ore also relates to discharge vessels o* -this type.
The invention will now be further described by-way o* e~ample with reference to a drawing in which Fig. 1 shows an embodiment o* a low-pressure mer-cury vapour discharge lamp produced by means o* a method in accordance with the invention and Fig. 2 shows one end, partly in cross-sectional view, o* a discharge vessel containing a container still to be opened.
In ~i-g. 1 reference numeral I denotes the wall o~ a tubular discharge vessel o* a low-pressure mercury vapour discharge lamp, stems 2 and 3 with electrodes ~ and 5~ respectively being provided one at each end. The interior wall of the discharge vessel is coated with a 25 luminescent layer 6 consisting, *or example 9 of a mixture o* trivalent europium-activated yttrium-oxide and tri~
valent terbium-activated cerium magnesium aluminate~ A
metal wire 7, which is connec-ted -to a metal container 8 located behind the elec-trodes is welded to one o* the 30 current supply wires of electrode 4. The wall portion near said container (the *oot 9 of the stem 2~ is provided with an amalgam. Said amalgam is applied by means o* a methocl in accordance with the inventionO The amalgam is provided in a cool spot, w~ich is advantageous ~or the 35 con-trol of the mercury vapour pressura in the discharge vessel, behind the electrode 4.
During the production o* the lamp the in-terior wall o* a tube is ~irst coated by means o* a known method "~
PIIN 10.009 - 7_ 1-12 - I981 wi-tn a luminescent layer, whereafter the stems are connected in a vacuum-tight manner to the wall o~ the tube. ~aid s-tems~have a closed metal con-tainer 8 which conta;ns an amalgam. Thereafter the discharge vessel is exhausted (by means of an exhaust tube 10 connected to one of the stems), the rare gas atmosphere is established and the discharge vessel is closed in a vacuum-tigh-t manner by sealing the exhaust tube. Not until thereafter is the metal con-tainer 8 opened by directing a focussed laser beam onto the wall of the con;tainer so as to make an opening therein. At least a portion of the amalgam leaves the container through the opening as a syrupy liquid and moves to the foot 9 of the stem, where it adheres.
Fig. 2 shows one end of a discharge vessel at the moment at which all operations on the lamps except the release of the amalgarn have been finished. Said amalgam is in the container 8 which is still in the closed condition.
The container 8 is formed by two sheet metal portions 8a and 8b (for example consisting of iron or nickel) which are welded together, 8b having been provided with a recess in which an amalgam 11 consisting of indium, bismuth and mercury is provided. The amalgam is obtained by heating a small sphere of bismuth which is enclosed by a quantity of a ductile alloy of indium and mercury~ It has been found that the bismuth is then very rapidly absorbed by the alloy and ~orms a homogeneous/somewhat liquid compound. The metal portions 8a and 8b fi-t around arnalgam 11 in such a way that no unwanted gasses are trapped in the container~ The container 8 is opened by means of a laser arranged ou-tside the discharge vessel. An opening is drilled in a portion 12 of 8a by ~ocussing the laser beam. The -temperature then in-craases to such a value that a portion of the amalgarn flows from the contair~er 8.
In a practical embodiment, the wall portion 9 wh~re a portion of the amalgam arrives is located at only a few mm (~or example 2mm) ~rom portion 12. The use of a converging laser beam to form the opening has the advantage that the further portions (~or exarnple 1 and 2) o~ the PHN 10.009 ~ 12-1981 glass wall of -the disoharge vessel are not attacked by the laser light. Moreover~ the energy of the laser light can be concentrated such -that even amalgam-~orming com-ponents having a low vapour pressure (such as indium or bismuth) become syrupy when -the opening is formed.
In an alternative embodiment the container is inductively hea-ted, a wecik spot having been provided in the container wall ~lere -the container is opened.
A practical embodiment o~ a lamp shown in ~ig. 1 produced by means of a method in accordance with the in-vention contained 26.8 mg Bi, 13.2 mg In and 3.0 mg Hg (in wt.7b 62.30/o Bi~ 30.7%' In, 7% Hg). The container was formed of two metal portions which are welded together and one o~ ~hich is provided with a recess, An opening (diameter 0.~7 mmj was formed in the container ~y means o~ a pulsed Nd-YAG laser (pulse energy appro~imately 2 J).
~t an applied power o~ 13 W -the lamp (having argon, 267 Pa, as rare gas filling~ had a luminous flux of approxima~
tely 900 Lumen.
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of producing a low-pressure mercury vapour discharge lamp having a tubular discharge vessel, at least a metal or an alloy which forms an amalgam with mercury being disposed in the discharge vessel before the desired gas atmosphere is established in the discharge vessel and the discharge vessel is closed in a vacuum-tight manner, characterized in that the metal or the alloy is present in a closed container which is provided close to a portion of the interior wall of the discharge vessel behind an electrode near an end of said vessel, which con-tainer is opened after the discharge vessel has been closed in a vacuum-tight manner, at least a portion of the metal or the alloy then leaving the container and moving to said wall portion close to the container, the mercury being introduced in the discharge vessel after the closing step of said vessel.
2. A method as claimed in Claim 1, characterized in that the container also contains mercury.
3. A method as claimed in Claim 1, characterized in that the container is filled with an amalgam consisting of indium, bismuth and mercury.
4. A method as claimed in Claim 3, characterized in that the amalgam is formed by heating a spherical member of bismuth and a quantity of a ductile alloy of indium and mercury.
5. A method as claimed in Claim 1 or 4, character-ized in that the container is opened by means of a laser beam focussed onto the wall of the container.
6. A method as claimed in Claim 1 or 4, character-ized in that the holder is made of metal and is inductively heated, a weak spot having been provided in the container wall where the container is opened.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL8101885 | 1981-04-16 | ||
| NL8101885A NL8101885A (en) | 1981-04-16 | 1981-04-16 | METHOD FOR MANUFACTURING A LOW-PRESSURE MERCURY DISCHARGE LAMP AND LOW-PRESSURE MERCURY DISCHARGE LAMP Manufactured by that method. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1194096A true CA1194096A (en) | 1985-09-24 |
Family
ID=19837367
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000400127A Expired CA1194096A (en) | 1981-04-16 | 1982-03-31 | Method of producing a low-pressure mercury vapour discharge lamp and low-pressure mercury vapour discharge lamp produced by means of said method |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0063393B1 (en) |
| JP (1) | JPS57180040A (en) |
| CA (1) | CA1194096A (en) |
| DE (1) | DE3271746D1 (en) |
| NL (1) | NL8101885A (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5274305A (en) * | 1991-12-04 | 1993-12-28 | Gte Products Corporation | Low pressure mercury discharge lamp with thermostatic control of mercury vapor pressure |
| US5374871A (en) * | 1992-07-21 | 1994-12-20 | General Electric Company | Annular dosing capsule for electric discharge lamp and method of dosing the lamp using the capsule |
| GB9424262D0 (en) * | 1994-12-01 | 1995-01-18 | Masonlite Ltd | Apparatus for providing radiation |
| GB2295721B (en) * | 1994-12-01 | 1998-11-11 | Masonlite Ltd | Apparatus for providing radiation |
| US7625258B2 (en) | 2006-03-16 | 2009-12-01 | E.G.L. Company Inc. | Lamp electrode and method for delivering mercury |
| DE102006052025A1 (en) | 2006-11-03 | 2008-05-08 | Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH | mercury source |
| KR20100017694A (en) | 2007-05-09 | 2010-02-16 | 코닌클리즈케 필립스 일렉트로닉스 엔.브이. | Low-pressure mercury vapor discharge lamp with amalgam capsule having amalgam chamber |
| RU2465081C1 (en) * | 2011-06-24 | 2012-10-27 | Открытое акционерное общество Акционерная холдинговая компания "Всероссийский научно-исследовательский и проектно-конструкторский институт металлургического машиностроения имени академика Целикова" (ОАО АХК "ВНИИМЕТМАШ") | Method of making cold-rolled sheets from aluminium and its alloys |
| JP7072786B2 (en) * | 2017-09-29 | 2022-05-23 | 岩崎電気株式会社 | Low-pressure mercury lamp and its manufacturing method |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB967685A (en) * | 1962-03-28 | 1964-08-26 | Hivac Ltd | Improvements in or relating to gas discharge tubes |
| GB1419099A (en) * | 1972-08-11 | 1975-12-24 | Thorn Electrical Ind Ltd | Manufacturing electric devices having sealed envelopes |
| JPS5045476A (en) * | 1973-08-29 | 1975-04-23 | ||
| AR206705A1 (en) * | 1974-03-21 | 1976-08-13 | Philips Nv | METHOD OF MANUFACTURING A MERCURY VAPOR DISCHARGE LAMP AND A LAMP MADE BY SUCH METHOD |
| US3860852A (en) * | 1974-04-04 | 1975-01-14 | Gte Sylvania Inc | Fluorescent lamp containing amalgam-forming material |
| NL183687C (en) * | 1978-10-11 | 1988-12-16 | Philips Nv | LOW-PRESSURE MERCURY DISCHARGE LAMP. |
| JPH0354430B2 (en) * | 1980-10-22 | 1991-08-20 |
-
1981
- 1981-04-16 NL NL8101885A patent/NL8101885A/en not_active Application Discontinuation
-
1982
- 1982-03-31 DE DE8282200395T patent/DE3271746D1/en not_active Expired
- 1982-03-31 CA CA000400127A patent/CA1194096A/en not_active Expired
- 1982-03-31 EP EP82200395A patent/EP0063393B1/en not_active Expired
- 1982-04-14 JP JP6120682A patent/JPS57180040A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPS57180040A (en) | 1982-11-05 |
| EP0063393A1 (en) | 1982-10-27 |
| DE3271746D1 (en) | 1986-07-24 |
| NL8101885A (en) | 1982-11-16 |
| EP0063393B1 (en) | 1986-06-18 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |