CA1232317A - Electric discharge lamp with thermal switch - Google Patents
Electric discharge lamp with thermal switchInfo
- Publication number
- CA1232317A CA1232317A CA000451395A CA451395A CA1232317A CA 1232317 A CA1232317 A CA 1232317A CA 000451395 A CA000451395 A CA 000451395A CA 451395 A CA451395 A CA 451395A CA 1232317 A CA1232317 A CA 1232317A
- Authority
- CA
- Canada
- Prior art keywords
- pair
- conductive members
- spring
- affixed
- electrically conductive
- 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
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
- H05B41/02—Details
- H05B41/04—Starting switches
- H05B41/06—Starting switches thermal only
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/02—Details
- H01J61/56—One or more circuit elements structurally associated with the lamp
Landscapes
- Discharge Lamps And Accessories Thereof (AREA)
- Thermally Actuated Switches (AREA)
Abstract
ELECTRIC DISCHARGE LAMP WITH THERMAL SWITCH
ABSTRACT
An electric discharge lamp has an arc tube within an outer gas filled glass envelope and a thermal switching means is located within the outer envelope. The thermal switching means has a silica support with a pair of electrical conductors affixed thereto and a bimetal strip and a spring-like member are affixed to at least one of the electrical conductors, and upon application of heat the bimetal strip and spring-like member are flexed to short-circuit the electrical conductors and remove any D.C. potential between the main electrode and the starting electrode minimizing electrolysis.
ABSTRACT
An electric discharge lamp has an arc tube within an outer gas filled glass envelope and a thermal switching means is located within the outer envelope. The thermal switching means has a silica support with a pair of electrical conductors affixed thereto and a bimetal strip and a spring-like member are affixed to at least one of the electrical conductors, and upon application of heat the bimetal strip and spring-like member are flexed to short-circuit the electrical conductors and remove any D.C. potential between the main electrode and the starting electrode minimizing electrolysis.
Description
D-24,428 ~ 2~3 ~ ,~t ELECTRIC DISCHARGE LAHP WITH TliERMAl SWITCH
TEC~NICAL FIELD
Thi¢ invention relates to electrlc discharge lamps and more particularly to electric dlcharge larnps havin~ a rlormally open thermal switch therein and to normally open thermal swltches having swltch distortion inhlbitin~ capabilities.
BACKGROUND ART
~ lectric discharKe lamps such as metal halide lamps which include mercury, the metals of various halides and particularly sodium iodide undesirsbly Qre sub~ect to electrolysis betweeD the usual starter electrodes and the electrode immediately adjacent thereto. ~oreover, any DC potentlal e~isting betwe~n the above-mentioned electrodes undesirably increases electrolytic activity and especially 50 aB operational temperatures lncreasa.
lS Generally, the metal halide lamps include a sealed ~las~
envelope wlth a fused sillca arc tube disposed withln the sealed glass envelope. For some time, the outer glass envelope w~s evacuated whereupon a thermal switch was sub~ected to a temperature which wns determined by lamp wattage and substantially independent of lamp orientation or position of operation. Thus, a simple thermal switch could be lncorporated into the outer elass envelope anA accommodate temperature variations encou~tered while employing commercially available bimetal materials.
However, better performance and other desirable features and consideratlons led to the use of a gas fill withln the outer ~lass envelope. Accordin~ly, the variable of convective heating was added to lnmp wattage in determining the operatiD~ temperatures of a thermal or bimetal type switch. Horeover, li~hting fixture mnnufacturers, in recent years, are deslgning systems to widen the beam spread o~ avallable lamps and have utili~ed the co~cept oP -~ "~
D-24,428 3~
moving the lamp further into the reflector cavity of ihe fi~ture.
As a result, the temperature of the larnp components and of the thermal swltch associated with the lamp has been~increased.
Unfortunately, such increased temperatures tend tp stress the bim~talllc material of avallable thermal switches beyond the elastlc llmit ~7hereupon premanent deformation of the thermal switch undesirably results. Thus, thermal switch failure permits the previously-mentioned electrolysis to take place and results in failure o~ the dischar~e lamp.
Additionally, the above-mentioned overheatiD~ of the thermal switch presents no problem with regard to defor~qtion when a s~itch is used which is normally closed and opens as the temperature is increased. However, for normally open swltches which close as the temperature increases such permanent deformatlon of the switch i~ a problem. Therein, contact closure imposes a restraint in movement of the bimetal material, and this restraint may cause a permanent deformation which prevents return of the swltch to a normally open condltion and eventually results in lamp failure.
O~JECTS AND SU~MARY OF THE INVENTION
An object of the present invention is to provlde an lmproved electric dischar~e lamp. Another object of the invention is to enhance the response capability ko increased temperature variations in an electrlc dischar~e lamp. Still another object of the invention is to provlde an lmproved thermal switch applicable for use in an electric discharge lamp. A further object o~ the inventlon is to provide a thermal switch of enhanced capability to respond to variations in operational temperatures.
These and other objects, advanta~es and capabilities are achieved ln one aspect of the inventlon by an electrlc dlschar~e lamp havin~ an arc tube with an electrode and an adjacent startlng electrode sealed therein with the arc tube disposed within a ~as filled envelope and a thermal switch external to the arc tube and internal to the envelope. The switch has a pair of electrical D-24,428 :~ ~3;~3~7 -;
conductive members afFixed to Q slllca support m~mber ~nd B blm~tal strip arld n sprin~-lik2 member are affi~ed to one of said palr of contuctive members and opcrativ~ to short-circult the pair of conductive members.
In snother aspect of the invention a thermal switch har a pair of electrical conductors attached to a silica support ~ember and a bimetal strip and sprlng-like member are afflxed to at least one of ! the electr~cal conductors in a manner to short-clrcuit the palr of electrical conductors upon application of heat thereto ln an amount sufficient to reach the closure temperature of the switch. Ths sprin~-like member fle~es to prevent permanent deformation of the bimetal upon application of an increased temperaturQ.
BRIEF DESCRIPTION OF THE DRAWINGS
.; .
FIG. l is an elevatlonal view of a metal halide lamp havin~ one embodiment of a thermal sw~tch of the invention therein;
FIG. 2 is an enlarged perspectlve view of a thermal switch of ; the invention; and FIG. 3 is a~ enlar~ed perspective view of an alternative embodiment of a thermal switch of the inventlon.
BEST MODE FOR CARRYING OUT THE INYENTION
For a better understandin~ of the present invention, together with other and further objects, advanta~es and capablllties thereof, reference is made to tha followln~ dlsclosure and appended claims in con~unction with the accompanyin~ drawin~s.
Referrin~ to FIG. l of the drawin~s, 8 metal halide lamp 5 includes an outer glass en~elope 7 having a bul~ed substantial}y tubular confi~uration with a neck portion 9 closed by a stem member ll hermetically sealed thereto. A pair of e~ectrlcally conductiv~
leads 13 and lS are sealed into and pass throu~h the stem member ll and are electrically connected to the contacts of a screw-in base member l7.
D-24,428 Dlsposed within the Duter ~lass envelope 7 i8 a fused silica arc tube 19. The arc tube 19 has electrode~ 21 and 23 sealed into opposite ends thereof and a startin~ electrode 25 is sealed snto one end of the arc tube 19 and positioned adjacent one of the electrodes 21. The electrodes 21 and 23 snd the startlng electrode 25 each have an electrical conductive member, 27, 29 and 31 respectlvely9 electrically connected thereto and passing through the sealed arc tube 19.
A first cage-like mounting member 33 ls sffixed to one end of the arc tube 19 and includes a pair of spring-clips 35 and 37 thereon which contact the outer glass envelope 7 and serve to support the arc tube 19 therein. The electrical conductive member 29 connected to the electrode 23 is also connected by a curved wire 39 to one of the electrlcally conductlve leads 13 sealed into the stem member ll affi~ed to the outer glass envelope 7.
A second ca~e-like mounting member 40 is affixed to the opposite end of the arc tube 19 and also includes a pair of spring-cllps bl and 43 thereon which contact the outer glass envelope 7 and serve to more rigidly support the arc tube 19 therein. The second ca~e-like mounting member 40 ls affi~ed to the other elsctric~lly conductive lead 15 sealed into and passin~ throu~h the stem member ll affixed to the outer ~lass envelope 7. Th~ electrlcal conductive member 27 connected to the electrode 21 is also connected to the other electrically conductive lead 15 by way of the second ca~e-llke mountin~ member 40. Also, the starting electrode ?5 is connected by way of an electrical conductive member 31 to a resistor 45 whlch is, in turn, connected to the electrically conductive lead 13 sealed into the stem member 11.
Addltionally and importantly, a thermal switching means 47 1 spaced from the arc tube 19 and affixed to the second ca~e~ e mounting member 40. The thermal switchin~ means 47 is of a conf~uration such that location thereof at a relati~ely cool or lower temperature within the outer glass envelope 7 ls attalnable wlthout other deleterious effect. In other words, increases in lamp temperature by as much as a hundred degrees dua to the US2 of wide beam fixtures wherein the lamp is moved furth~r into the fi~ture and D-24,428 3.~ Y,~ ~
universal burnln~ posltions of the l~mp have necessitated mov~ment o~ the thermal swltchin~ means 47 from the usual location on the ele~tricnl coDduct~ve members 27 and 31 to ~ location more remot~
from:the arc tube 19. Thus, remotely locRtin~ the thermal swltching ; 5 means 47 tends to reduce overstressln~ of the blmetallic material o~
the switchin~ means 47 beyond the elastlc limit thereof ne~atln~ any permanent deformation of the switchin~ means 47 or malfunctioning of the lamp 5 due to such deformatlon.
As to the thermal switching means 47, FIG. 2 illustrates a preferred embodiment thereof ~hich includes a pair of electrical conductors 49 and 51 embedded in a silica support member 5~. The on~ electrlcal conductor 49 includes an outwardly e~tending portlon 55 which is formed to provide for attachment of the support member 53 to an adjacent structure at a desired location relatively remote from the arc tube, 19 of FIG. 1, such as the second ca~e-like moun~in~ member, 40 of FIG. 1. Also affixed to one 49 of the palr of electrical conductors 49 and 51 is a bimetal strip 57 preferably extendin~ In a directlon normal to the plane o~ the support member 53. ~oreover, the bimetal strip 47 preferably has a notched end portlon 59 which will be explained hereinafter.
The second one 51 of the pair of electrical conductors 49 and 51 is preferably formed to provide a sprin~-like member 61 extendln~
substantially parallel to and spaced from the bimetal strip 57. In this manner, the bimetal strip 57 as well as the spring-like member 61 ~re individually adjustable whereby compensation for variations in temperature due to differin~ locations of the thermal switchlng means 47 is readily effected.
As to operation, the arc tube 19 of a metal halidè lamp for example normally has a fill which includes mercury and halides of various metals including sodium. Also, the outer ~lass envelope 7 lncludes a fill of an inactiva ~as~ such as nltro~en for example.
The thermal switchin~ means 47 is in the form of a normally-open (N/O~ s~iteh at room temperature. Moreover, the closure tempersture of the thermal switchin~ means 47 is dependent upon numerous factors, such as the placement of the switchin~ means 47 within the ~ ~3~
envelope 7~ the gas fill and the desl~n of the switchin~ means 47.
Common thermostats practic~l for lamp use ha~e been found to be satisfactory to the present application.
Initlally current flow to ~he electrode 21 ~nd startiD~
electrode 25 is effacted ~ith the therm~l switching means 47 at room temperature. As the temperature increases, the bimetal strip flexes i causing the pair o~ electrical conductors 49 and 51 to short-; circuit. Thereupon, any electrolysis inducin~ D.C. potential ' between electrode 21 and starting electrode ~5 is eliminated. Also, ! l0 it can be seen that the notched end portion 59 of the bimetal strip 57 is formed to accommodate the sprin~-like member 61 whereupon imprGved electrical connection therebetween is effected. HoreoYer, the flexible spring-like member 61 readily flexes whenever the bimetal strip 57 flexes. In this manner, distortion of the bimetal strip 57 due to an excessive increase in temperature is prohiblted.
AlternatiYely, the thermal s~itching means 47 may be of a fo~m, illustrnted in FIG. 3, having a glass bridge member 63 with a palr of electrical conductors 65 and 67 affi~ed thereto. One electricQl conductor 55 is ~ormed with an outwardly extending portion 69 whereby attachment of the switching means 47 may be effected. Also, the one electrical conductor 65 has an upstandln~ portion 71 adjacent the other one 67 of the pair of electrical conductors 6S
and 67. The other electrical conductor 67 has a bimetal strip 73 affi~ed thereto with a flexible spring-like member 75 attached to the bimetal stip 73 at the end thereof 77 most distant from the brid~e member 63. Also, the other electrical conductor 67 is formed for connection to an electrode.
Again, a normally-open (N/O) switching condit~on ls in effect at room temperature. However, an increase irl temperature causes the j 30 bimetal strip 73 to fle~ in one direction whereupon the spring~ e member 75 is flexed in the opposite dirertion. As result~ the spring-like mamber 75 contacts the upstanding portion 71 of the one electrical conductor 65. Thus, the electrlcal conductors 65 and 67 are short-circuited, and any electrolysis inducin~ D.C. potentlal between the electrode and the startin~ electrode of an electrlc dischar~e lamp is eliminated.
D-24,428 ~oreover, the sprin~-like mc~ber 75 permits fle~in~ of the bimet~l strip 73 without permanent deformatlon of the bim~tal strlp 73 even thou~h subjected to excessive temperature excursions.
While there has been sh~wn and described what is at present considered the preferred embodiments of the invention, it ~ill be obvious to those skilled in the art that various chan~es and modlfications may be made therein without departing from the invention as defined by the appended claims.
TEC~NICAL FIELD
Thi¢ invention relates to electrlc discharge lamps and more particularly to electric dlcharge larnps havin~ a rlormally open thermal switch therein and to normally open thermal swltches having swltch distortion inhlbitin~ capabilities.
BACKGROUND ART
~ lectric discharKe lamps such as metal halide lamps which include mercury, the metals of various halides and particularly sodium iodide undesirsbly Qre sub~ect to electrolysis betweeD the usual starter electrodes and the electrode immediately adjacent thereto. ~oreover, any DC potentlal e~isting betwe~n the above-mentioned electrodes undesirably increases electrolytic activity and especially 50 aB operational temperatures lncreasa.
lS Generally, the metal halide lamps include a sealed ~las~
envelope wlth a fused sillca arc tube disposed withln the sealed glass envelope. For some time, the outer glass envelope w~s evacuated whereupon a thermal switch was sub~ected to a temperature which wns determined by lamp wattage and substantially independent of lamp orientation or position of operation. Thus, a simple thermal switch could be lncorporated into the outer elass envelope anA accommodate temperature variations encou~tered while employing commercially available bimetal materials.
However, better performance and other desirable features and consideratlons led to the use of a gas fill withln the outer ~lass envelope. Accordin~ly, the variable of convective heating was added to lnmp wattage in determining the operatiD~ temperatures of a thermal or bimetal type switch. Horeover, li~hting fixture mnnufacturers, in recent years, are deslgning systems to widen the beam spread o~ avallable lamps and have utili~ed the co~cept oP -~ "~
D-24,428 3~
moving the lamp further into the reflector cavity of ihe fi~ture.
As a result, the temperature of the larnp components and of the thermal swltch associated with the lamp has been~increased.
Unfortunately, such increased temperatures tend tp stress the bim~talllc material of avallable thermal switches beyond the elastlc llmit ~7hereupon premanent deformation of the thermal switch undesirably results. Thus, thermal switch failure permits the previously-mentioned electrolysis to take place and results in failure o~ the dischar~e lamp.
Additionally, the above-mentioned overheatiD~ of the thermal switch presents no problem with regard to defor~qtion when a s~itch is used which is normally closed and opens as the temperature is increased. However, for normally open swltches which close as the temperature increases such permanent deformatlon of the switch i~ a problem. Therein, contact closure imposes a restraint in movement of the bimetal material, and this restraint may cause a permanent deformation which prevents return of the swltch to a normally open condltion and eventually results in lamp failure.
O~JECTS AND SU~MARY OF THE INVENTION
An object of the present invention is to provlde an lmproved electric dischar~e lamp. Another object of the invention is to enhance the response capability ko increased temperature variations in an electrlc dischar~e lamp. Still another object of the invention is to provlde an lmproved thermal switch applicable for use in an electric discharge lamp. A further object o~ the inventlon is to provide a thermal switch of enhanced capability to respond to variations in operational temperatures.
These and other objects, advanta~es and capabilities are achieved ln one aspect of the inventlon by an electrlc dlschar~e lamp havin~ an arc tube with an electrode and an adjacent startlng electrode sealed therein with the arc tube disposed within a ~as filled envelope and a thermal switch external to the arc tube and internal to the envelope. The switch has a pair of electrical D-24,428 :~ ~3;~3~7 -;
conductive members afFixed to Q slllca support m~mber ~nd B blm~tal strip arld n sprin~-lik2 member are affi~ed to one of said palr of contuctive members and opcrativ~ to short-circult the pair of conductive members.
In snother aspect of the invention a thermal switch har a pair of electrical conductors attached to a silica support ~ember and a bimetal strip and sprlng-like member are afflxed to at least one of ! the electr~cal conductors in a manner to short-clrcuit the palr of electrical conductors upon application of heat thereto ln an amount sufficient to reach the closure temperature of the switch. Ths sprin~-like member fle~es to prevent permanent deformation of the bimetal upon application of an increased temperaturQ.
BRIEF DESCRIPTION OF THE DRAWINGS
.; .
FIG. l is an elevatlonal view of a metal halide lamp havin~ one embodiment of a thermal sw~tch of the invention therein;
FIG. 2 is an enlarged perspectlve view of a thermal switch of ; the invention; and FIG. 3 is a~ enlar~ed perspective view of an alternative embodiment of a thermal switch of the inventlon.
BEST MODE FOR CARRYING OUT THE INYENTION
For a better understandin~ of the present invention, together with other and further objects, advanta~es and capablllties thereof, reference is made to tha followln~ dlsclosure and appended claims in con~unction with the accompanyin~ drawin~s.
Referrin~ to FIG. l of the drawin~s, 8 metal halide lamp 5 includes an outer glass en~elope 7 having a bul~ed substantial}y tubular confi~uration with a neck portion 9 closed by a stem member ll hermetically sealed thereto. A pair of e~ectrlcally conductiv~
leads 13 and lS are sealed into and pass throu~h the stem member ll and are electrically connected to the contacts of a screw-in base member l7.
D-24,428 Dlsposed within the Duter ~lass envelope 7 i8 a fused silica arc tube 19. The arc tube 19 has electrode~ 21 and 23 sealed into opposite ends thereof and a startin~ electrode 25 is sealed snto one end of the arc tube 19 and positioned adjacent one of the electrodes 21. The electrodes 21 and 23 snd the startlng electrode 25 each have an electrical conductive member, 27, 29 and 31 respectlvely9 electrically connected thereto and passing through the sealed arc tube 19.
A first cage-like mounting member 33 ls sffixed to one end of the arc tube 19 and includes a pair of spring-clips 35 and 37 thereon which contact the outer glass envelope 7 and serve to support the arc tube 19 therein. The electrical conductive member 29 connected to the electrode 23 is also connected by a curved wire 39 to one of the electrlcally conductlve leads 13 sealed into the stem member ll affi~ed to the outer glass envelope 7.
A second ca~e-like mounting member 40 is affixed to the opposite end of the arc tube 19 and also includes a pair of spring-cllps bl and 43 thereon which contact the outer glass envelope 7 and serve to more rigidly support the arc tube 19 therein. The second ca~e-like mounting member 40 ls affi~ed to the other elsctric~lly conductive lead 15 sealed into and passin~ throu~h the stem member ll affixed to the outer ~lass envelope 7. Th~ electrlcal conductive member 27 connected to the electrode 21 is also connected to the other electrically conductive lead 15 by way of the second ca~e-llke mountin~ member 40. Also, the starting electrode ?5 is connected by way of an electrical conductive member 31 to a resistor 45 whlch is, in turn, connected to the electrically conductive lead 13 sealed into the stem member 11.
Addltionally and importantly, a thermal switching means 47 1 spaced from the arc tube 19 and affixed to the second ca~e~ e mounting member 40. The thermal switchin~ means 47 is of a conf~uration such that location thereof at a relati~ely cool or lower temperature within the outer glass envelope 7 ls attalnable wlthout other deleterious effect. In other words, increases in lamp temperature by as much as a hundred degrees dua to the US2 of wide beam fixtures wherein the lamp is moved furth~r into the fi~ture and D-24,428 3.~ Y,~ ~
universal burnln~ posltions of the l~mp have necessitated mov~ment o~ the thermal swltchin~ means 47 from the usual location on the ele~tricnl coDduct~ve members 27 and 31 to ~ location more remot~
from:the arc tube 19. Thus, remotely locRtin~ the thermal swltching ; 5 means 47 tends to reduce overstressln~ of the blmetallic material o~
the switchin~ means 47 beyond the elastlc limit thereof ne~atln~ any permanent deformation of the switchin~ means 47 or malfunctioning of the lamp 5 due to such deformatlon.
As to the thermal switching means 47, FIG. 2 illustrates a preferred embodiment thereof ~hich includes a pair of electrical conductors 49 and 51 embedded in a silica support member 5~. The on~ electrlcal conductor 49 includes an outwardly e~tending portlon 55 which is formed to provide for attachment of the support member 53 to an adjacent structure at a desired location relatively remote from the arc tube, 19 of FIG. 1, such as the second ca~e-like moun~in~ member, 40 of FIG. 1. Also affixed to one 49 of the palr of electrical conductors 49 and 51 is a bimetal strip 57 preferably extendin~ In a directlon normal to the plane o~ the support member 53. ~oreover, the bimetal strip 47 preferably has a notched end portlon 59 which will be explained hereinafter.
The second one 51 of the pair of electrical conductors 49 and 51 is preferably formed to provide a sprin~-like member 61 extendln~
substantially parallel to and spaced from the bimetal strip 57. In this manner, the bimetal strip 57 as well as the spring-like member 61 ~re individually adjustable whereby compensation for variations in temperature due to differin~ locations of the thermal switchlng means 47 is readily effected.
As to operation, the arc tube 19 of a metal halidè lamp for example normally has a fill which includes mercury and halides of various metals including sodium. Also, the outer ~lass envelope 7 lncludes a fill of an inactiva ~as~ such as nltro~en for example.
The thermal switchin~ means 47 is in the form of a normally-open (N/O~ s~iteh at room temperature. Moreover, the closure tempersture of the thermal switchin~ means 47 is dependent upon numerous factors, such as the placement of the switchin~ means 47 within the ~ ~3~
envelope 7~ the gas fill and the desl~n of the switchin~ means 47.
Common thermostats practic~l for lamp use ha~e been found to be satisfactory to the present application.
Initlally current flow to ~he electrode 21 ~nd startiD~
electrode 25 is effacted ~ith the therm~l switching means 47 at room temperature. As the temperature increases, the bimetal strip flexes i causing the pair o~ electrical conductors 49 and 51 to short-; circuit. Thereupon, any electrolysis inducin~ D.C. potential ' between electrode 21 and starting electrode ~5 is eliminated. Also, ! l0 it can be seen that the notched end portion 59 of the bimetal strip 57 is formed to accommodate the sprin~-like member 61 whereupon imprGved electrical connection therebetween is effected. HoreoYer, the flexible spring-like member 61 readily flexes whenever the bimetal strip 57 flexes. In this manner, distortion of the bimetal strip 57 due to an excessive increase in temperature is prohiblted.
AlternatiYely, the thermal s~itching means 47 may be of a fo~m, illustrnted in FIG. 3, having a glass bridge member 63 with a palr of electrical conductors 65 and 67 affi~ed thereto. One electricQl conductor 55 is ~ormed with an outwardly extending portion 69 whereby attachment of the switching means 47 may be effected. Also, the one electrical conductor 65 has an upstandln~ portion 71 adjacent the other one 67 of the pair of electrical conductors 6S
and 67. The other electrical conductor 67 has a bimetal strip 73 affi~ed thereto with a flexible spring-like member 75 attached to the bimetal stip 73 at the end thereof 77 most distant from the brid~e member 63. Also, the other electrical conductor 67 is formed for connection to an electrode.
Again, a normally-open (N/O) switching condit~on ls in effect at room temperature. However, an increase irl temperature causes the j 30 bimetal strip 73 to fle~ in one direction whereupon the spring~ e member 75 is flexed in the opposite dirertion. As result~ the spring-like mamber 75 contacts the upstanding portion 71 of the one electrical conductor 65. Thus, the electrlcal conductors 65 and 67 are short-circuited, and any electrolysis inducin~ D.C. potentlal between the electrode and the startin~ electrode of an electrlc dischar~e lamp is eliminated.
D-24,428 ~oreover, the sprin~-like mc~ber 75 permits fle~in~ of the bimet~l strip 73 without permanent deformatlon of the bim~tal strlp 73 even thou~h subjected to excessive temperature excursions.
While there has been sh~wn and described what is at present considered the preferred embodiments of the invention, it ~ill be obvious to those skilled in the art that various chan~es and modlfications may be made therein without departing from the invention as defined by the appended claims.
Claims (12)
1. An electric discharge lamp comprising:
a gas filled outer glass envelope having a pair of electrically conductive leads sealed therein and passing therethrough;
an arc tube within said outer glass envelope having an electrode sealed into opposite ends thereof and a starting electrode adjacent one of said electrodes, said arc tube having an ionizable fill and subject to electrolysis under electrical stress at high temperatures; and thermal switching means internal of said outer glass envelope and external of said arc tube and in the form of a pair of electrical conductive members embedded in a silica support member with one of said pair of electrical conductive members connected to an electrode and the other one to said starting electrode adjacent thereto and a parallel extending bimetal strip and spring-like member affixed to at least one of said pair of electrical conductive members and formed to short-circuit said pair of electrical conductive members and said electrode and adjacent starting electrode upon application of heat to said bimetal.
a gas filled outer glass envelope having a pair of electrically conductive leads sealed therein and passing therethrough;
an arc tube within said outer glass envelope having an electrode sealed into opposite ends thereof and a starting electrode adjacent one of said electrodes, said arc tube having an ionizable fill and subject to electrolysis under electrical stress at high temperatures; and thermal switching means internal of said outer glass envelope and external of said arc tube and in the form of a pair of electrical conductive members embedded in a silica support member with one of said pair of electrical conductive members connected to an electrode and the other one to said starting electrode adjacent thereto and a parallel extending bimetal strip and spring-like member affixed to at least one of said pair of electrical conductive members and formed to short-circuit said pair of electrical conductive members and said electrode and adjacent starting electrode upon application of heat to said bimetal.
2. The electric discharge lamp of Claim 1 wherein said thermal switching means is affixed to one of said pair of electrically conductive leads and spaced from said arc tube.
3. The electric discharge lamp of Claim 1 wherein said bimetal strip and said spring-like members are each affixed to a separate one of said pair of electrical conductive members whereby precise adjustment of the gap therebetween is provided.
4. The electric discharge lamp of Claim 1 wherein said bimetal strip and said spring-like member are affixed to one of said pair of electrical conductive members and formed to electrically contact the other one of said pair of electrical conductive members upon application of heat thereto.
5. The electric discharge lamp of Claim 1 wherein said bimetal strip has a notch at one end thereof and said notched end of said bimetal contacts said spring-like member upon application of heat to said bimetal strip.
6. The electric discharge lamp of Claim 1 wherein one of said pair of electrical conductive members is formed to include said spring-like member.
7. A normally open thermal switch for use with temperature excursions beyond normal closure temperatures thereof comprising:
a silica support member;
a pair of electrically conductive members affixed to said silica support member; and a bimetal strip and a spring-like member affixed to at least one of said pair of electrically conductive members affixed to said silica support member and formed to short-circuit said pair of electrically conductive members upon heating to a switch closure temperature and to distort said spring-like member upon heating to a temperature greater than said switch closure temperature.
a silica support member;
a pair of electrically conductive members affixed to said silica support member; and a bimetal strip and a spring-like member affixed to at least one of said pair of electrically conductive members affixed to said silica support member and formed to short-circuit said pair of electrically conductive members upon heating to a switch closure temperature and to distort said spring-like member upon heating to a temperature greater than said switch closure temperature.
8. The normally open thermal switch of Claim 7 wherein said bimetal strip and said spring-like member are each affixed to a separate one of said pair of electrically conductive members whereby precise adjustment of a gap therebetween is provided.
9. The normally open thermal switch of Claim 7 wherein said bimetal strip is affixed to one of said pair of electrically conductive members and the other one of said electrically conductive member is formed to provide said spring-like members extending substantially parallel to said bimetal strip.
10. The normally open thermal switch of Claim 7 wherein said bimetal switch has a notched end portion formed to contact said spring-like member upon heating to a switch closure temperature and to bend said spring-like member at temperatures greater than said switch closure temperature.
11. The normally open thermal switch of Claim 7 wherein at least one of said pair of electrically conductive members is formed for supporting and attaching said thermal switch.
12. The normally open thermal switch of Claim 7 wherein each of said pair of electrically conductive members includes a substantially U-shaped configuration embedded in said silica support member.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US48962383A | 1983-04-28 | 1983-04-28 | |
| US489,623 | 1990-03-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1232317A true CA1232317A (en) | 1988-02-02 |
Family
ID=23944598
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000451395A Expired CA1232317A (en) | 1983-04-28 | 1984-04-05 | Electric discharge lamp with thermal switch |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0124368B1 (en) |
| CA (1) | CA1232317A (en) |
| DE (1) | DE3480821D1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4659965A (en) * | 1983-11-16 | 1987-04-21 | Gte Products Corporation | High pressure discharge lamp with thermal switch |
| US5004949A (en) * | 1988-05-31 | 1991-04-02 | North American Philips Corporation | Fluorescent lamp with grounded electrode guard |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3619710A (en) * | 1969-10-29 | 1971-11-09 | Sylvania Electric Prod | High-pressure electric discharge lamp having electrolysis-preventing means |
| US3965387A (en) * | 1974-06-24 | 1976-06-22 | General Electric Company | Electric lamp and thermal switch therefore |
| US4355261A (en) * | 1980-12-15 | 1982-10-19 | Gte Products Corporation | Discharge lamp with integral starter |
| US4360758A (en) * | 1981-01-23 | 1982-11-23 | Westinghouse Electric Corp. | High-intensity-discharge lamp of the mercury-metal halide type which efficiently illuminates objects with excellent color appearance |
| US4445073A (en) * | 1982-03-22 | 1984-04-24 | Gte Products Corporation | Intimate contact starting aid for arc lamps |
-
1984
- 1984-04-05 CA CA000451395A patent/CA1232317A/en not_active Expired
- 1984-04-27 DE DE8484302857T patent/DE3480821D1/en not_active Expired - Fee Related
- 1984-04-27 EP EP19840302857 patent/EP0124368B1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| EP0124368A1 (en) | 1984-11-07 |
| EP0124368B1 (en) | 1989-12-20 |
| DE3480821D1 (en) | 1990-01-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |