CA2042143A1 - Discharge lamp with surrounding shroud and method of making such lamp - Google Patents
Discharge lamp with surrounding shroud and method of making such lampInfo
- Publication number
- CA2042143A1 CA2042143A1 CA 2042143 CA2042143A CA2042143A1 CA 2042143 A1 CA2042143 A1 CA 2042143A1 CA 2042143 CA2042143 CA 2042143 CA 2042143 A CA2042143 A CA 2042143A CA 2042143 A1 CA2042143 A1 CA 2042143A1
- Authority
- CA
- Canada
- Prior art keywords
- shroud
- tubular
- disk
- inner envelope
- vitreous material
- 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.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
- H01J9/24—Manufacture or joining of vessels, leading-in conductors or bases
- H01J9/32—Sealing leading-in conductors
- H01J9/323—Sealing leading-in conductors into a discharge lamp or a gas-filled discharge device
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/02—Details
- H01J61/30—Vessels; Containers
- H01J61/34—Double-wall vessels or containers
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Vessels And Coating Films For Discharge Lamps (AREA)
- Manufacture Of Electron Tubes, Discharge Lamp Vessels, Lead-In Wires, And The Like (AREA)
Abstract
LD10,109 ABSTRACT
This discharge lamp includes (i) an inner envelope of vitreous material comprising a bulbous portion and two tubular portions extending from the bulbous portion and (ii) a tubular shroud of vitreous material surrounding the bulbous portion and the two tubular portions. The lamp is made by the following method. A disk-shaped enlargement is formed in each of the tubular portions by heating a localized region of the tubular portion to its softening point and then subjecting said localized region to a compressive force (i) that is abruptly applied along the length of the tubular portion and (ii) that drives the softened vitreous material radially outward into a disk formation. Then the tubular shroud is placed over the inner envelope so that each disk-shaped enlargement is positioned with its outer periphery closely adjacent the inner periphery of the surrounding tubular shroud. Then seals are formed between the outer peripheries of the disk-shaped enlargements and the surrounding shroud portions by heating each of the surrounding shroud portions to its softening point and collapsing it about the outer periphery of the associated disk-shaped enlargement.
This discharge lamp includes (i) an inner envelope of vitreous material comprising a bulbous portion and two tubular portions extending from the bulbous portion and (ii) a tubular shroud of vitreous material surrounding the bulbous portion and the two tubular portions. The lamp is made by the following method. A disk-shaped enlargement is formed in each of the tubular portions by heating a localized region of the tubular portion to its softening point and then subjecting said localized region to a compressive force (i) that is abruptly applied along the length of the tubular portion and (ii) that drives the softened vitreous material radially outward into a disk formation. Then the tubular shroud is placed over the inner envelope so that each disk-shaped enlargement is positioned with its outer periphery closely adjacent the inner periphery of the surrounding tubular shroud. Then seals are formed between the outer peripheries of the disk-shaped enlargements and the surrounding shroud portions by heating each of the surrounding shroud portions to its softening point and collapsing it about the outer periphery of the associated disk-shaped enlargement.
Description
LD10,109 DISCHARGE LAMP WITH SURROUNDING SHROUD AND
METHOD OF MAKING SyCH LAMP
CROSS-REFERENCE TO RELATED APPLICATIOM
This application is related to earliex Application S.N.157,360 Hansler et al, filed February 18, 1988, and assigned to the assignee of the present invention, which earlier application is incorporated by re~erence in the pressnt application.
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This invention relates to a discharge-type lamp that includes an inner envP}ope and a shroud joined to the inner envelope and bounding a space surrounding the inner envelope. The invention also relates to a method of making such a lamp, particularly to a method o~
joining the shroud to the envelope.
, ~ ... . . . .
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LD19,10g BACXG~OUND
In the aforesaid Application S.N. 157,360, Hansler et al there is disclosed and claimed a metal-halide type discharge lamp that includes a quartz inner envelope and a tubular glass shroud surrounding the inner envelope and spaced therefrom along a portion of the shroud length. The tubular glass shroud is sealed at predeterm~ned locations along its length to the inner envelope, and the space between the shroud and the inner envelope is evacuated or gas filled so that this space constitutes a sealed chambPr. The shroud and the sealed chamber serve a number o~ impcrtant functions, which are pointed out and discussed in tha a~oresaid application.
Generally speaking, one of these functions is to make the temperature of the inner envelope higher and more uniform, and another is to keep the shroud relatively cool in comparison to the inner envelope. The significance of th~se functions is discussed hereinafter and also in more detail in the afores~id earlier application.
The ability to accomplish the results desired from the shroud and the vacuum chambar or gas chamber depends materially upon the nature of the joints or seals .. ' :'''`
' , : : : ~
METHOD OF MAKING SyCH LAMP
CROSS-REFERENCE TO RELATED APPLICATIOM
This application is related to earliex Application S.N.157,360 Hansler et al, filed February 18, 1988, and assigned to the assignee of the present invention, which earlier application is incorporated by re~erence in the pressnt application.
,:~,~
This invention relates to a discharge-type lamp that includes an inner envP}ope and a shroud joined to the inner envelope and bounding a space surrounding the inner envelope. The invention also relates to a method of making such a lamp, particularly to a method o~
joining the shroud to the envelope.
, ~ ... . . . .
~ 2 ~ ~ ~
LD19,10g BACXG~OUND
In the aforesaid Application S.N. 157,360, Hansler et al there is disclosed and claimed a metal-halide type discharge lamp that includes a quartz inner envelope and a tubular glass shroud surrounding the inner envelope and spaced therefrom along a portion of the shroud length. The tubular glass shroud is sealed at predeterm~ned locations along its length to the inner envelope, and the space between the shroud and the inner envelope is evacuated or gas filled so that this space constitutes a sealed chambPr. The shroud and the sealed chamber serve a number o~ impcrtant functions, which are pointed out and discussed in tha a~oresaid application.
Generally speaking, one of these functions is to make the temperature of the inner envelope higher and more uniform, and another is to keep the shroud relatively cool in comparison to the inner envelope. The significance of th~se functions is discussed hereinafter and also in more detail in the afores~id earlier application.
The ability to accomplish the results desired from the shroud and the vacuum chambar or gas chamber depends materially upon the nature of the joints or seals .. ' :'''`
' , : : : ~
2~ 2~.~3 LD10,109 formed between the shroud and the inner envelope. For example, if we assume that (i) the inner envelope is of quartz and comprises an enlarged central region and tubular portions extending therefrom and (ii) the shroud is made of quartz tubing of inside diameter larger than that of the enlarged central region, which tubing i5 simply shrunk down upon these tubular portions of the inner envelope to form the two seals, then each seal will be constituted by a very thick region of quartz surroundinq a substantial length of the tubular portion.
To make such a seal requires a relatively large amount o~ heat applied for a.relatively long time, followed by a relatively long cooling period; and, as a result, the thermal characteristics of this region are susceptibla to being significantly changed by slight variations in the process of making the seals. These changes in thermal characteristics can detrimentally af~ect lamp performance. ~oreover, the large amount of heat and the relatively long times involved in making such a seal can produce conditions that weaken, and possibly crack, the tubular inner-envelope portion at the sealO
Another disadvantage of making the shroud-to-inner en~elope seals by simply shrinking down the shroud about the tubular portions of the inner env~lope, as above , ~ ~f ~ 4 ~'~
LDlo,los described r is that using this approach will usually result in each of these shroud seals being located closely adjacent one of the foil seals of the lamp.
These foil seals are used for providing a seal for the conductive inleads extending through the quartz of the inner envelope. If the shroud seal is closely adjacent the foil seal, there is an increased likelihood that the heat used for making the shroud seal will adversely affect the foil seal, possibly cracking the vitreous material in the foil seal region and possibly even causing a leak to develop in this r~gion.
Simply locating the shroud~to-inner envelope seals at locations spaced further outwardly along the tubular portions of the inner envelope from the foil seals is not a satisfactory solution to these problems because the heat for making the shroud seals can cause oxidation of the nearby conductive inleads, and, moreover, this approach results in undesirably increasing the overall length of the lamp.
OBJECTS
An object o~ this invention is to provide a discharge lamp of this general type in which a high quality seal between the inner env210pe and the surrounding shroud can be quickly made with very little . , . . . . ,:
. . . .
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LD10,109 heat.
Another object is to construct a lamp of this general type in such a manner that the inner envelope-to-shroud seals are located remote from the foil seals yet without adding materially to the overall length of the lamp.
Another object is to provide a discharge lamp of this general type in which ths inner envelope-to-shroud seals are made in such a manner that the thermal characteristics of the lamp in the region of these se~ls are relatively unaffected by slight variations in the process of making the seals.
Still another object is to provide an improved method for making a vacuum-tight seal or gas tight seal between the inner vitreous envelope of a metal halide discharge lamp and the surrounding shroud of vitreous material.
Still another object is to provide, ~or making a shroud-to-inner en~alope se~l of this type, an improved method that enables the seal to be made quickly and with very little heat.
Still another object is to make a shroud-to-innsr envelope seal by a method that results in such seal being located relatively remote from any other seals in .
- . .: .
-LDlo,109the lamp, e.g., from any foil seal at the same end of the lamp.
Another object is to provide an improved method for making a lamp of this general type that readily lends itself to being performed with automated equipment.
SUMM~RY
In carrying out our invention in one form, we provide (i) an innex envelope comprising a hollow bulbous portion and two tubular portions of vitreous material extending from the bulbous portion and (ii) a tubular shroud of vitreous material surrounding the bulbous portion and said tubular portions. In each of the tubular portions of the inner envelope, we form a disk-shaped enlargement by first heating a localized region of the tubular portion to its softening point and then subjecting this softened localized region to a compressive force (i) that is abruptly applied along the length of said tubular portion and (ii) that drives the soPtened vitreous material radially outward into a disk formation. We then place the tubular shroud over the inn~r envelope so that each o~ the disk-shaped enlargements is positioned in alignment with a predetermined portion of the shroud and with the outer periphery of the enlargement closely adjacent but ~ ' .
2, ~ 3 LD10,109 slightly spaced from the inner periphery of said predetermined shroud portion, thus forming an unsealed chamber between the shroud and the inner envelope and between the disk-shaped enlargements. We then form a first seal between the inner periphery of one of said predetermined portions of the shroud and the outer periphery of the aligned disk-shaped enlargement by heating and thereby softening said one predetermined shroud portion and then collapsing this shroud portion about the outer periphery of the aligned enlargement.
We form a second seal between the inner periphery of the other o~ said predetermined shroud portions and the outer periphery of the disk-shaped enlargement aligned therewith.
In one embodiment of the invention, we evacuate the above-defined chamber to a hard vacuum. In another embodiment, we fill the chamber with a suitable gaseous filler.
In still another e~bodiment, w~ provide the above-defined disk-shaped enlarqement in only one of the tubular portions of the inner envelope, omitting the disk-shaped enlargement from the other tubular portion and forming a conventional seal between the other tubular portion and the surrounding portion o~ the shroud aligned therewith.
, , ~ ~ L~ 3 LD10,109 BRIEF DESCRIPTION OF FIGURES
For a better understanding of the invention, reference may be had to the following detailed description taken in connection with accompanying drawings, wherein:
Fig. 1 is a sectional view of a metal-halide disrharge lamp embodying one form of the present invention. This lamp comprises an inner envelope of vitreous material and a tubular shroud of vitreous material surrounding the inner envelope.
Fig. 2 is a schematic illustration of one st~p used in making the inner envelope portion of the lamp of Fig. 1.
Fig. 3 shows the inner envelope portion of Fig. 2 after the fabrication steps depicted in Fig. 2 have been completed.
Fig. 4 illustrates the manufacture of an arc tube incorporating the inner envelope of Fig. 3.
Fig. 5 illustrates so~e of the method steps that are used for incorporating the shroud of Fig. 1 into the metal-halide lamp.
Fig. 6 is a sectional view of a metal-halide lamp embodying a modified ~orm of the invention.
Fig. 7 is a sectional view of a vehirle , , :
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LD10,109 head lamp that utilizes as its light source the lamp of Figs. 1-5.
Fig. 8 is a simplified sectional view of another modified form of the invention.
DETAILED DESC~IPTION OF EMOBIDMENTS
Referring now to Fig. 1, there ic shown a metal-halide type of discharge lamp 10 that comprises an inner envelope i2 of a light-transmitting vitreous material, preferably quartz. The inner envelope 12 comprises a bulbous central portion 14 and two tubular portions 16 and 18 integral with the central portion 14 and projecting in opposite directions therefrom.
Surrounding the inner envelope 12 is a tubular shroud 20, also of a Yitreous material, preferably quartz. This shroud 20 has an enlarged central portion 22 disposed about the central portion 14 of the inner envelope. Projecting from this enlarged central portion 22 are two tubular portions 24 and 26 respectively surrounding the tubular por~ions 16 and 18 o~ the inner envelope. Joining the shroud 20 to the inner envelop~
are two disk members 30 and 32 also of ~uartz. As will be explained in more detail, these disk mem~ers 30 and 32 are integral with the tubular portions 16 and 18 of the inner envelope and are joined at their respective - ~
. ~ .
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LD10,109outer peripheries to the surrounding regions of the shroud 20 to form vacuum-tight annular seals 33 and 35 between the disk members and the shroud.
The tubular shroud 20 is spaced from the inner envelope 12 in the region between the two disk members and 32, thus providing a sealed chamber 36 surrounding the inner envelope 12 and having an exterior wall defined by shroud 20 and end walls defined by disk members 30 and 32. In one form of this invention, this sealed cha~ber 36 is ev~cuated to a hard vacuum during fabrication of the lamp in a manner that will soon be described~ Preferably, thi~ chamber includes a suitable getter 38 that is used in a conventional manner to assist in maintaininq the hard YacuUm in the chamber.
Within the inner envelope 12 are two spaced-apart electrodes 40 and 42 between which an electric arc is developed in a conventional manner to ser~e as a light source. The electrodes are preferably of tungsten or a mixture of tungsten and ~%-3% thorium oxide~ The electrodes include rod portions 44 and 46, respectively, that extend outwardly from the gap between the electrodes into the tubular portions 16 and 18 of the inner envelope. At the outer end of rod portion 44 there is a foil member 47, preferably of molybdenum, ! . . -;: .
20 ~21d~
LD10,109 joined to the rod portion 44; and extending outwardly from the foil member there is an inlead 48, preferably of molybdenum, that is joined at its inner end to the foil member. The foil member 47, the inlead 48, and the rod portion 44 of the electrode are of a conventional form, and they are joined together in a conventional manner. The surrounding vitreous material o~ the envelope portion 16, while hot and softened, is collapsed about the foil, rod, and inlead structure in a conventional manner (such as disclosed, ~or ex~mple, in U.S. Patent 4,891,551 - Ahlgren et al) to form a leak-proof seal between the foil member and th~ surrounding vitreous material. At the opposite, or right-hand, end of the arc tube there is a foil member 52 joined to an inlead 50 and to the rod portion 46 of electrode 42.
These components are of the same fo~m and composition as those at the left-hand end of the arc tube and are mounted within the surrounding vitreous material in the same way, a seal being present between the foil m mber and the surrounding vitreous material. The above-described inleads 48 and 50 and their associated foil members s~rve in a conventional manner to carry electric current to and from the arc, or discharge, that is present between the electrodes when the lamp is on.
' . .
LD10,109 In one embodiment of the invention, the central portion 14 of the inner envelope 12 contains a fill containing mercury, a metal halide, and in some cases xenon gas. The operating pressure of the fill is in the range of about 2 to about 65 atmospheres. This fill is dsscribed in more detail and is claimed in the aforesaid Application S.N. 157,360. Typically, one of the principal components of the fill is sodium iodine.
As further pointed in Application S.N. 157,360, the evacuated chamber 36 acts to produce an improved wall temperature of the inner envelope 12 by substantially eliminating the effects of gas conduction and convection in th~ region surrounding the inner envrlope. The presence o~ the evacuated chamber makes this wall temperature higher and more uniform. This results in more metal halide being vaporized and maintained in the arcing region, which improves the ef~iciency of the lamp and the color of the emitted light. In metal-halide lamp~ operating at low frequency, there is a catephoresis effect that tends to sweep the metal halides into th~ end regions of the bulb (1~, but in the illustrated lamp this effect is largely cancelled out by the higher temperatures produced in these end .
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LD10,109 regions by the presenc~ of the evacuated chamber 36 and its thermal insulating effect.
This thermal insulating effect enables us, through proper choice of the size of the shroud, to operate a shroud of reasonable size at a sufficiently low temperature that its electronic conductivity remains very low. Maintaining thi~ low electronic conductivity allows any sodium ions which diffuse through the inner envelope and evaporate to settle on the inside wall of the shroud without being electrically neutralized by wall conduction. It is believed that this enables the settled sodium ions to produce a strong electrical field which opposes the motion of subsequent migrating sodium ions, thereby reducing any further related sodium loss.
For the evacuated chamber 36 to function consistently in the desired manner summarized above, it is important to construct the joints between the outer shroud (20) and the tubular portions (16 and 18) of the inner Pnvelope in such a manner that the thermal characteristics o~ the la~p in the region of these joints are consistent and predictable from one lamp to another. If these joints had required for their fabrication high heat inputs maintained for long times, then small variations in the process for making the~
' ' . ~
~ .~ V ~ f J ~ 3 LD10,109 co~lld produce undesirable large variations in the thermal characteristics of these regions of the lamp.
We have developed a method for making these joints which can be performed with relatively little heat applied for relatively short times, thus materially reducing these undesirable variations.
The first step in our method is illustrated in Fig. 2, where the tubular blank 60 from which the inner envelope is formed is shown mounted within a convent-ional glass lathe schematically illustrated at 61. This lathe comprises a headstock 62 and a collet chuck 64 for mounting the left~hand end of the tubular blank on the headstock so that the left-hand end is fixed again~t axial motion but i5 rotatable about the central longitudinal axis 66 of the blank 60. The lathe further comprises a tailstock 72 and a collet chuck 73 for mounting the right-hand end of the blank 60. During lathe operation, the tailstock and the heads~ock are rotatably driven in synchrsnism about a common longitudinal axis coinciding'with axis 66 by the same drive mechanism, ~hereby rotating the blank 60 about its longitudinal axis 66. In a conventional manner, the tails~ock is alss sui~ably mounted for selective movement parallel to this longitudinal axis 66, as indicated by the arrow 79.
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LD10,109 Positioned adjacen~ the left-hand tubular portion 16 of the blank 60 is a burner 80 that is adapted to develop a flame 82 that can be directed as shown against an axially -localized region ~3 of the tubular portion 16. While the blank 60 is being slowly turned about its axis 66 by the lathe, the flame 82 heats the axially~
localiæed region 83 about the entire periphery of the tubular portion 83 until the quartz in this region 83 has reached its softening point. The tailstock remains stationary during such heating; but when the quartz in region 83 is sufficiently softened, the tailstock is abruptly moved a short distance to the lPft, as indicated by arrow 79. This abrupt leftward motion causes compressive force to be applied to the softened region 83 in a direction along the axis 66, and such force has the effect of driving the softened quartz in this region 83 radially outward about the entire periphery of the tubular portion 16, thereby producing the disk formation shown at 30 in Fig. 3. These heating and force-applying steps (so~etimes rsferred to herein as an upsetting op~ration~ can be readily controlled to consistently produce a disk formation of a pred~termined outer diameter and a predetermined thickness along the length of axis 66.
, LD10,109 The operations of the immediately-prsceding paragraph are repeated with the burner in a position 86 sAown in Fig. 2, thereby producing a second disk-shaped enlargement, shown at 32 in Fig. 3. The outer diameter of the disk-shaped enlargements 30 and 32 should not exceed the outer diameter of the arc chamber 14 so that the diameter of the shroud tube, which is later slipped over the arc chamber, may be minimized.
A~ a next step, the two electrodes 40 and 42 and their inlead structures are installed by first suitably positioning each of these electrodes and inlead structures as shown in Fig. 4. Then the surrounding quartz (in region 90) is heated to its softening point and is collapsed about the conductive structure. The result is a sturdy mount for the inlead and the electrode and a good leak-proof seal between the foil memb~r 47 or 52 and the surrounding quartz. This sealing of the foil member and mounting of the electr~des and inleads is a conventional operation, which is disclosed in grea~e~ detail in the aforesaid U.S. Patent 4,8~1,551 - Ahlgren et al, assigned to the assignee of the present invention. Th~ fill, described hereinabove, that is present in the arc chamber 14 of the lamp assembly of Fig. 1 is installed in a .
LD10,109 conventional manner after one of the foil seals is made as above described but before the other foil seal is made.
As a next step, the tubular shroud 20 is installed as shown in Fig. 5. This shroud is positioned about the inner envelope of Fig. 4 so that predetermined portions 92 and 94 thereof are in alignment with the disk-shaped enlargements 30 and 32, respectively. Each of the disk-shaped enlargements has been fo~med by the operation of FigO 2 in such a manner that its outer diameter is almost, but not quite, as large as the internal diameter of the shroud 20 in the aligned regions 92 or 94.
Accordingly, there is a small clearance space about the outer periphery of each of the enlargements that allows the shroud 20 to be readily positioned in the desired position shown.
After the shroud 20 has been so positioned, the region 92 of the shroud is heated by flame 95 derived ~rom a ring-~ype burner 95 that surrounds the region 32.
After a relatively short time, the quartz of region 92 reaches its softening point and begins to contract under the influence o~ surface tension. This causes the softened region 92 to collapse about the outer periphery of the aligned disk-shaped enlargement 30, which, because of its proximity, has also been heated by flame LD10,109 9S. When the softened shroud region 92 collapses about the outer periphery of the disk-shaped enlargement 30, an excellent seal is formed between shroud region 92 and the enlargement 30 ahout the entire outer periphery of the enlargement.
After the first seal is made at 92, the space 36 between the shroud 20 and the inner envelope 12 and between the disk-shaped enlargements 30 and 32 i~
evacuated. This is done by evacuating this space 36 with a suitable vacuum pump (not shown), which draws the contents of this space out through tAe small clearance space 97 surrounding the other disk-shaped enlargement 32. (The intake o~ the pump is connected in a conventional manner between the tubular portion 18 of the inner envelope and the surrounding tubular portion 26 of the shroud in a location above the enlargement 32.) While such evacuation is taking place, the walls of space 36 are suitably heated to help drive off absorbed gases. In a preferred form of the evacuation proce s, we alternately pump the space 36 and flush it with an inert gas, such as argon or nitrogen. The flushing gas is introduced through the clearance space 97 in the intervals between the pumping periods.
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LD10,109 After space 36 has been evacuated in this manner to a hard vacuum, a seal is made between the outer periphery of the disk-shaped enlargement 32 and the surrounding region 94 of the shroud 20. This seal is made in essentially the same manner as was used for makin~ the first seal (at 92). More specifically, the shroud region 94 is heated to soften it, thereby causing it to collapse about the outer periphery of the disk-shaped enlargement and form a seal therewith. Because a vacuum is then present in the chamber 36 and also in the region above enlargement 32, there is a pressure differential on opposite sides of the shroud wall which promotes such collapse of the shroud about disk-shaped enlargement 32.
To assure that a hard vacuum is developed and maintained within the chamber 36, we provide, in one form of the invention, a suitable getter 38 within chamber 36. This getter is introduced, preferably, before the shroud is assembled over the inner envelope.
In one form of the invention,~the getter comprises chips of zirconium-titanium alloy dispersed about the inner wall of the shroud This material is a good getter for hydrogen.
The locations (83 and 86 of Fig. 2~ chosen ~or forming the disk-shaped ~nlargements 30 and 32 are such , . . .
, . . . . .
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rd O '~ 2 ~ 3 LD10,109 that the enlargements ~o not interfere with sealing the foils 47 and 52 within the tubular portions 16 and 18 of the inner envelope 12. More specifically, the chosen locations 83 and 86 are spaced axially outward from the location of the foils. But this axial spacing is kept sufficiently small so that the presence of the enlargements does not add materially to the overall length of the shrouded lamp.
A significant feature of our shroud-to-inner envelope seals is that each seal is relatively remote ~rom the foil seal at the same end o~ the envelope. In this respect, note in.Fig. 1 that the shroud-to-inner envelope seal at each end of ths lamp is located radially-outward of the foil seal at the same end of the lamp by a distance approximately equal to the radial dimension R of the associated disk-shaped enlargement 30 or 32. This remoteness of the shroud seal from the foil seal is advantageous because it materially reduces the chances that the foil seal will b~ detrimentally affected by the heak involved in making the shroud seal.
It should also be noted that this remoteness between the two seals is achieved without materially increasing the overall length of the lamp since much of the separation between the two seals is in a radial direction rather , ~ . , , ~2~ ~3 LDl0,109 than an axial direction. Some axial separation is, however,required so that the foil seal is located outside the axial boundaries of the associated disk-shaped enlargement.
Another significant advantage of our shroud-to-inner envelope seals is that they can be made with relatively little heat applied for only a short ti~e.
In this respect, it should be noted that because the disk-shaped enlar~ements 30 and 32 extend radially outward almost completely to the inner periphery of the tubular form of the shroud, as best shown in Fig. 5, only a slight displacement of the shroud radially inwardly is required in order to move the shroud material into contact with the portion of the inner envelope to which it sealed. B~cause the amount of this displace~ent is so small, very little heat and time is required to effect it, and thus the chances are substantially reduced that the lamp matrrial in the vicinity of such seal will be detrimentally affected by the heat of the s~al-making operation. This reduced heating cooperates with the remoteness features of the immediately-preceding paragraph further to protect the foil seals from any detrimental effects of the shroud-sealing operation.
, ~?Jl~
LD10,109 Moreover, because we are able to make the shroud-to-inner envelope seals without requiring large amounts of heat and time, we have found that the process parameters are not critical. Minor variations in these parameters can be tolerated without significantly affecting the quality or characteristics oP the resulting seal and the nearby lamp material. '7 Another significant advantage of our lamp and our method of making it is that the lamp can be readily and quickly made with automated equipmsnt. For example, formation of the disk-shaped enlargements (30 and 32) is effected with the simple heating and force-application steps depicted in Fig. 2. Such steps are readily performed on the same machine (lathe 61~ that was used for forming the bulbous central portion 14 of the inner envelope, which central portion 14 is pxeferably formed in a conventional manner ~y heating the starting tubular blank in this region and blowing the heat-softened quartz radially outward. Wh~le the blank is on this same machine and in the same position, the disk-shaped enlargements 30 and 32 are introduced, as above described. In addition, the seals between the shroud and the inner envelope are made by simple and brieP
heating operations (Fig.5), which cause the heat , , : . ~ . `
2 ~3 1 ~
LDla~lo9 softened regions of the shroud to collapse the short distances required to effect high-quality seals to the disk-shaped enlargements 30 and 32.
While the embodiment of Figs. 1-5 includes disk-shaped enlargements (30 and 32) provided at both ends of the lamp for making the shroud-to-inner envelope seals, some of the advantages of our invention can still be realized if an enlargement of this character is provided only at one end of the lamp. At the other end of such a lamp, the seal between the shroud and the inner envelope can be made in a conventional manner, for example, by allowing the heat-softened portion of the tubular shroud to shrink down to the tuhular portion of the inner envelope that it seals to. Such a lamp is illustrated in Fig. 6, where this conventional seal, designated 100, is shown at the left-hand end of the lamp. To facilitate the making of seal 100, the tubular portion 24 of the shroud on the let hand end of the shroud is made only slightly larger than the left-hand-end tubular portion 16 of the inner env~lope. The shroud is then slipped onto the inner envelope from the left hand end of the inner envelope 50 that the larger diameter end of the shroud slips over the bulbous portion 14 of the inner envelope and the disk enlargement 32. Then the seal 100 is made in a conventional manner.
,: ~ , , ` :
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~'' ?d 1 4 3 LD10,109 One type of lamp where the approach of Fig. 6 is useful is one in which a surface of the shroud is coated with a reflective material to form a reflector which can be located close to the lamp. Such reflective material is indicated at 102 in Fig. 6. At the right-hand side of this lamp the shroud-to-inner envelope seal is the same as in Fig. 1. At the left-hand side of the lamp, the conventional seal 100 of the immediately-preceding paragraph is present.
In a preferred embodiment of the lamp, the inner envelope and the shroud are both of identical quartz~
But our invention in its broader aspects contemplates the use of other vitreous material capable of withstanding the high temperatures developed by operation of the arc tube. It is usually very desirable to use the same material for the shroud and the inner envelope to avoid cracking or sealing problems that might arise because of differ nt coefficients of thermal expansion of two different fusedotogether materials.
But minor differences in the'two materials can often be tolerated. For example, in another embodiment of our invention, we utilize for the shroud quartz which has been heated with a high electric field applied thereto to remove any traces of sodium which can increase '' , . ~`
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, 2~'-.L~
LD10,109 electronic conductivity. Such high resistance quarkz is available from General Electric Company as its sodium-free quartz. This high resistance quartz can be sealed to an inner envelope of ordinary quartz without encountering significant problems of differential thermal expansion. The presence of such high resistance quartz in the shroud is believed to help block sodium loss through the inn~r envelope.
The lamps described hereinabove are especially suited for forward lighting applications in a vehicle, such as an automobile, truck, bus, van or tractor. The aforesaid Application S.N. 157,360 - Hansler et al discloges several different ways in which a lamp of this general type is utilized for such forward lighting, and the present lamps are utilizable in the sam~ ways. For example, referring to Fig. 7 o~ the present application, our lamp is shown at 10 within an automobile headlamp 110~ This headlamp comprises a reflector 112, a lens member 114 at the front of the reflector, and lamp 10 in the space between the reflec~or and the lens.
The reflector 112 has a rear section 118 having mounted thereon a connector 120 with rearwardly-projecting prongs 122 and 124 capable of being connected to an external electrical source of the vehicle. The reflector 112 has a focal point 126 on the axis 128 of , ~
26 2 ~
LDlo,109 the headlamp. The light source 10 is predeterminedly positioned within the reflector 112 so that its mid-portion approximately coincides with the focal point 126 of the reflector. In the embodiment illustrated in Fig.
7, the light source 10 is oriented with its longitudinal axis extending vertically and in a transverse manner relative to the axis 128 of the headlamp.
In one embodiment, the reflector 112 has a parabolic shape with a focal length in the range of about 6 mm to about 35 mm, with a preferred range of about 8 mm to about 30 mm. The lens 114, which is suitably mated to the front portion of,the reflector, is of a transparent material, such as glass or a suitable plastic. The lens has a rear face preferably formed of prism members.
The light source 10 is connected to the rear section of the reflector 112 by means of rel tively heavy support wires 134 and 136 each having one end connected to one of the inleads 48 or 50 of the light source and its other end connected to one of the prongs 122 or 124. The light source 10 is energized via an electrical circuit that extends in series through the prongs and the support wires.
While in the lamps described hereinabove, the chamber 36 between ~he inner envelope and the shroud is ~J ~ 3 LD10,109 evacuated to a hard vacuum, it should be un~erstood that our invention in its broader aspects comprehends lamps of essentially the same structure as shown in Figs. 1 and 6 except including in the chamber 36 a gas having appropriate properties. For example, in certain lamps it is desirable that a predetermined portion of the heat developed by operation of the arcing tube be transferred across the chamber 36 by conduction or convection rather than primarily by radiation, as when a hard vacuum is present. With this consideration in mind, the chamber 36 can be filled with one of the fsllowing gases or mixtures thereof: argon, krypton, xenon, nitrogen, air, helium, and hydrogen. Typical charging pressures are in the range of 0 to 1500 torr.
While in making the lamp of Fig. 1 we prefer to evacuate (or fill) the chamber 36 through one of the seal locations (e.g.,35) before a seal is made at this location, our invention in its broader aspects comprehends the use of a separate sealable tube (such as shown in Fig. 8 at 105~ extending into this chamber through which the cha~ber may be evacuated and/or filled. When such a separate tube i5 used, we complete the seals at 33 and 35 before evacuting (or filling~ the chamber through the separate tube. Then the separate tube 105 is pinched off or otherwise sealed in a , 2 ~ 3 LD10,109 conventional manner to seal the chamber 36.
While we prefer to form the disk-shaped enlargements 30 and 32 before the electrodes 40, 42 and their inlead structures are incorporated in the arc tube, the invention in its broader aspects contemplates forming these enlargements after the ele~trod2s and their inlead structures are incorporated and before the shroud 20 is installedO
~ hile we have shown and described partic~lar embodiments of our invention, it will be obvious to those skilled in the art ~hat various change and modifications may be made without departing from our invention in its broader aspects; and we, therefore, intend herein to cover all such changes and modifications as fall within the true spirit and scope of our in~ention.
, ' , ~ ', ' ~. : .,
To make such a seal requires a relatively large amount o~ heat applied for a.relatively long time, followed by a relatively long cooling period; and, as a result, the thermal characteristics of this region are susceptibla to being significantly changed by slight variations in the process of making the seals. These changes in thermal characteristics can detrimentally af~ect lamp performance. ~oreover, the large amount of heat and the relatively long times involved in making such a seal can produce conditions that weaken, and possibly crack, the tubular inner-envelope portion at the sealO
Another disadvantage of making the shroud-to-inner en~elope seals by simply shrinking down the shroud about the tubular portions of the inner env~lope, as above , ~ ~f ~ 4 ~'~
LDlo,los described r is that using this approach will usually result in each of these shroud seals being located closely adjacent one of the foil seals of the lamp.
These foil seals are used for providing a seal for the conductive inleads extending through the quartz of the inner envelope. If the shroud seal is closely adjacent the foil seal, there is an increased likelihood that the heat used for making the shroud seal will adversely affect the foil seal, possibly cracking the vitreous material in the foil seal region and possibly even causing a leak to develop in this r~gion.
Simply locating the shroud~to-inner envelope seals at locations spaced further outwardly along the tubular portions of the inner envelope from the foil seals is not a satisfactory solution to these problems because the heat for making the shroud seals can cause oxidation of the nearby conductive inleads, and, moreover, this approach results in undesirably increasing the overall length of the lamp.
OBJECTS
An object o~ this invention is to provide a discharge lamp of this general type in which a high quality seal between the inner env210pe and the surrounding shroud can be quickly made with very little . , . . . . ,:
. . . .
:. -...
;~
LD10,109 heat.
Another object is to construct a lamp of this general type in such a manner that the inner envelope-to-shroud seals are located remote from the foil seals yet without adding materially to the overall length of the lamp.
Another object is to provide a discharge lamp of this general type in which ths inner envelope-to-shroud seals are made in such a manner that the thermal characteristics of the lamp in the region of these se~ls are relatively unaffected by slight variations in the process of making the seals.
Still another object is to provide an improved method for making a vacuum-tight seal or gas tight seal between the inner vitreous envelope of a metal halide discharge lamp and the surrounding shroud of vitreous material.
Still another object is to provide, ~or making a shroud-to-inner en~alope se~l of this type, an improved method that enables the seal to be made quickly and with very little heat.
Still another object is to make a shroud-to-innsr envelope seal by a method that results in such seal being located relatively remote from any other seals in .
- . .: .
-LDlo,109the lamp, e.g., from any foil seal at the same end of the lamp.
Another object is to provide an improved method for making a lamp of this general type that readily lends itself to being performed with automated equipment.
SUMM~RY
In carrying out our invention in one form, we provide (i) an innex envelope comprising a hollow bulbous portion and two tubular portions of vitreous material extending from the bulbous portion and (ii) a tubular shroud of vitreous material surrounding the bulbous portion and said tubular portions. In each of the tubular portions of the inner envelope, we form a disk-shaped enlargement by first heating a localized region of the tubular portion to its softening point and then subjecting this softened localized region to a compressive force (i) that is abruptly applied along the length of said tubular portion and (ii) that drives the soPtened vitreous material radially outward into a disk formation. We then place the tubular shroud over the inn~r envelope so that each o~ the disk-shaped enlargements is positioned in alignment with a predetermined portion of the shroud and with the outer periphery of the enlargement closely adjacent but ~ ' .
2, ~ 3 LD10,109 slightly spaced from the inner periphery of said predetermined shroud portion, thus forming an unsealed chamber between the shroud and the inner envelope and between the disk-shaped enlargements. We then form a first seal between the inner periphery of one of said predetermined portions of the shroud and the outer periphery of the aligned disk-shaped enlargement by heating and thereby softening said one predetermined shroud portion and then collapsing this shroud portion about the outer periphery of the aligned enlargement.
We form a second seal between the inner periphery of the other o~ said predetermined shroud portions and the outer periphery of the disk-shaped enlargement aligned therewith.
In one embodiment of the invention, we evacuate the above-defined chamber to a hard vacuum. In another embodiment, we fill the chamber with a suitable gaseous filler.
In still another e~bodiment, w~ provide the above-defined disk-shaped enlarqement in only one of the tubular portions of the inner envelope, omitting the disk-shaped enlargement from the other tubular portion and forming a conventional seal between the other tubular portion and the surrounding portion o~ the shroud aligned therewith.
, , ~ ~ L~ 3 LD10,109 BRIEF DESCRIPTION OF FIGURES
For a better understanding of the invention, reference may be had to the following detailed description taken in connection with accompanying drawings, wherein:
Fig. 1 is a sectional view of a metal-halide disrharge lamp embodying one form of the present invention. This lamp comprises an inner envelope of vitreous material and a tubular shroud of vitreous material surrounding the inner envelope.
Fig. 2 is a schematic illustration of one st~p used in making the inner envelope portion of the lamp of Fig. 1.
Fig. 3 shows the inner envelope portion of Fig. 2 after the fabrication steps depicted in Fig. 2 have been completed.
Fig. 4 illustrates the manufacture of an arc tube incorporating the inner envelope of Fig. 3.
Fig. 5 illustrates so~e of the method steps that are used for incorporating the shroud of Fig. 1 into the metal-halide lamp.
Fig. 6 is a sectional view of a metal-halide lamp embodying a modified ~orm of the invention.
Fig. 7 is a sectional view of a vehirle , , :
9 ~ L ,~
LD10,109 head lamp that utilizes as its light source the lamp of Figs. 1-5.
Fig. 8 is a simplified sectional view of another modified form of the invention.
DETAILED DESC~IPTION OF EMOBIDMENTS
Referring now to Fig. 1, there ic shown a metal-halide type of discharge lamp 10 that comprises an inner envelope i2 of a light-transmitting vitreous material, preferably quartz. The inner envelope 12 comprises a bulbous central portion 14 and two tubular portions 16 and 18 integral with the central portion 14 and projecting in opposite directions therefrom.
Surrounding the inner envelope 12 is a tubular shroud 20, also of a Yitreous material, preferably quartz. This shroud 20 has an enlarged central portion 22 disposed about the central portion 14 of the inner envelope. Projecting from this enlarged central portion 22 are two tubular portions 24 and 26 respectively surrounding the tubular por~ions 16 and 18 o~ the inner envelope. Joining the shroud 20 to the inner envelop~
are two disk members 30 and 32 also of ~uartz. As will be explained in more detail, these disk mem~ers 30 and 32 are integral with the tubular portions 16 and 18 of the inner envelope and are joined at their respective - ~
. ~ .
-r~ r~
LD10,109outer peripheries to the surrounding regions of the shroud 20 to form vacuum-tight annular seals 33 and 35 between the disk members and the shroud.
The tubular shroud 20 is spaced from the inner envelope 12 in the region between the two disk members and 32, thus providing a sealed chamber 36 surrounding the inner envelope 12 and having an exterior wall defined by shroud 20 and end walls defined by disk members 30 and 32. In one form of this invention, this sealed cha~ber 36 is ev~cuated to a hard vacuum during fabrication of the lamp in a manner that will soon be described~ Preferably, thi~ chamber includes a suitable getter 38 that is used in a conventional manner to assist in maintaininq the hard YacuUm in the chamber.
Within the inner envelope 12 are two spaced-apart electrodes 40 and 42 between which an electric arc is developed in a conventional manner to ser~e as a light source. The electrodes are preferably of tungsten or a mixture of tungsten and ~%-3% thorium oxide~ The electrodes include rod portions 44 and 46, respectively, that extend outwardly from the gap between the electrodes into the tubular portions 16 and 18 of the inner envelope. At the outer end of rod portion 44 there is a foil member 47, preferably of molybdenum, ! . . -;: .
20 ~21d~
LD10,109 joined to the rod portion 44; and extending outwardly from the foil member there is an inlead 48, preferably of molybdenum, that is joined at its inner end to the foil member. The foil member 47, the inlead 48, and the rod portion 44 of the electrode are of a conventional form, and they are joined together in a conventional manner. The surrounding vitreous material o~ the envelope portion 16, while hot and softened, is collapsed about the foil, rod, and inlead structure in a conventional manner (such as disclosed, ~or ex~mple, in U.S. Patent 4,891,551 - Ahlgren et al) to form a leak-proof seal between the foil member and th~ surrounding vitreous material. At the opposite, or right-hand, end of the arc tube there is a foil member 52 joined to an inlead 50 and to the rod portion 46 of electrode 42.
These components are of the same fo~m and composition as those at the left-hand end of the arc tube and are mounted within the surrounding vitreous material in the same way, a seal being present between the foil m mber and the surrounding vitreous material. The above-described inleads 48 and 50 and their associated foil members s~rve in a conventional manner to carry electric current to and from the arc, or discharge, that is present between the electrodes when the lamp is on.
' . .
LD10,109 In one embodiment of the invention, the central portion 14 of the inner envelope 12 contains a fill containing mercury, a metal halide, and in some cases xenon gas. The operating pressure of the fill is in the range of about 2 to about 65 atmospheres. This fill is dsscribed in more detail and is claimed in the aforesaid Application S.N. 157,360. Typically, one of the principal components of the fill is sodium iodine.
As further pointed in Application S.N. 157,360, the evacuated chamber 36 acts to produce an improved wall temperature of the inner envelope 12 by substantially eliminating the effects of gas conduction and convection in th~ region surrounding the inner envrlope. The presence o~ the evacuated chamber makes this wall temperature higher and more uniform. This results in more metal halide being vaporized and maintained in the arcing region, which improves the ef~iciency of the lamp and the color of the emitted light. In metal-halide lamp~ operating at low frequency, there is a catephoresis effect that tends to sweep the metal halides into th~ end regions of the bulb (1~, but in the illustrated lamp this effect is largely cancelled out by the higher temperatures produced in these end .
, ,:
, ~ V ~
LD10,109 regions by the presenc~ of the evacuated chamber 36 and its thermal insulating effect.
This thermal insulating effect enables us, through proper choice of the size of the shroud, to operate a shroud of reasonable size at a sufficiently low temperature that its electronic conductivity remains very low. Maintaining thi~ low electronic conductivity allows any sodium ions which diffuse through the inner envelope and evaporate to settle on the inside wall of the shroud without being electrically neutralized by wall conduction. It is believed that this enables the settled sodium ions to produce a strong electrical field which opposes the motion of subsequent migrating sodium ions, thereby reducing any further related sodium loss.
For the evacuated chamber 36 to function consistently in the desired manner summarized above, it is important to construct the joints between the outer shroud (20) and the tubular portions (16 and 18) of the inner Pnvelope in such a manner that the thermal characteristics o~ the la~p in the region of these joints are consistent and predictable from one lamp to another. If these joints had required for their fabrication high heat inputs maintained for long times, then small variations in the process for making the~
' ' . ~
~ .~ V ~ f J ~ 3 LD10,109 co~lld produce undesirable large variations in the thermal characteristics of these regions of the lamp.
We have developed a method for making these joints which can be performed with relatively little heat applied for relatively short times, thus materially reducing these undesirable variations.
The first step in our method is illustrated in Fig. 2, where the tubular blank 60 from which the inner envelope is formed is shown mounted within a convent-ional glass lathe schematically illustrated at 61. This lathe comprises a headstock 62 and a collet chuck 64 for mounting the left~hand end of the tubular blank on the headstock so that the left-hand end is fixed again~t axial motion but i5 rotatable about the central longitudinal axis 66 of the blank 60. The lathe further comprises a tailstock 72 and a collet chuck 73 for mounting the right-hand end of the blank 60. During lathe operation, the tailstock and the heads~ock are rotatably driven in synchrsnism about a common longitudinal axis coinciding'with axis 66 by the same drive mechanism, ~hereby rotating the blank 60 about its longitudinal axis 66. In a conventional manner, the tails~ock is alss sui~ably mounted for selective movement parallel to this longitudinal axis 66, as indicated by the arrow 79.
:
- ' , ~ Q ~
LD10,109 Positioned adjacen~ the left-hand tubular portion 16 of the blank 60 is a burner 80 that is adapted to develop a flame 82 that can be directed as shown against an axially -localized region ~3 of the tubular portion 16. While the blank 60 is being slowly turned about its axis 66 by the lathe, the flame 82 heats the axially~
localiæed region 83 about the entire periphery of the tubular portion 83 until the quartz in this region 83 has reached its softening point. The tailstock remains stationary during such heating; but when the quartz in region 83 is sufficiently softened, the tailstock is abruptly moved a short distance to the lPft, as indicated by arrow 79. This abrupt leftward motion causes compressive force to be applied to the softened region 83 in a direction along the axis 66, and such force has the effect of driving the softened quartz in this region 83 radially outward about the entire periphery of the tubular portion 16, thereby producing the disk formation shown at 30 in Fig. 3. These heating and force-applying steps (so~etimes rsferred to herein as an upsetting op~ration~ can be readily controlled to consistently produce a disk formation of a pred~termined outer diameter and a predetermined thickness along the length of axis 66.
, LD10,109 The operations of the immediately-prsceding paragraph are repeated with the burner in a position 86 sAown in Fig. 2, thereby producing a second disk-shaped enlargement, shown at 32 in Fig. 3. The outer diameter of the disk-shaped enlargements 30 and 32 should not exceed the outer diameter of the arc chamber 14 so that the diameter of the shroud tube, which is later slipped over the arc chamber, may be minimized.
A~ a next step, the two electrodes 40 and 42 and their inlead structures are installed by first suitably positioning each of these electrodes and inlead structures as shown in Fig. 4. Then the surrounding quartz (in region 90) is heated to its softening point and is collapsed about the conductive structure. The result is a sturdy mount for the inlead and the electrode and a good leak-proof seal between the foil memb~r 47 or 52 and the surrounding quartz. This sealing of the foil member and mounting of the electr~des and inleads is a conventional operation, which is disclosed in grea~e~ detail in the aforesaid U.S. Patent 4,8~1,551 - Ahlgren et al, assigned to the assignee of the present invention. Th~ fill, described hereinabove, that is present in the arc chamber 14 of the lamp assembly of Fig. 1 is installed in a .
LD10,109 conventional manner after one of the foil seals is made as above described but before the other foil seal is made.
As a next step, the tubular shroud 20 is installed as shown in Fig. 5. This shroud is positioned about the inner envelope of Fig. 4 so that predetermined portions 92 and 94 thereof are in alignment with the disk-shaped enlargements 30 and 32, respectively. Each of the disk-shaped enlargements has been fo~med by the operation of FigO 2 in such a manner that its outer diameter is almost, but not quite, as large as the internal diameter of the shroud 20 in the aligned regions 92 or 94.
Accordingly, there is a small clearance space about the outer periphery of each of the enlargements that allows the shroud 20 to be readily positioned in the desired position shown.
After the shroud 20 has been so positioned, the region 92 of the shroud is heated by flame 95 derived ~rom a ring-~ype burner 95 that surrounds the region 32.
After a relatively short time, the quartz of region 92 reaches its softening point and begins to contract under the influence o~ surface tension. This causes the softened region 92 to collapse about the outer periphery of the aligned disk-shaped enlargement 30, which, because of its proximity, has also been heated by flame LD10,109 9S. When the softened shroud region 92 collapses about the outer periphery of the disk-shaped enlargement 30, an excellent seal is formed between shroud region 92 and the enlargement 30 ahout the entire outer periphery of the enlargement.
After the first seal is made at 92, the space 36 between the shroud 20 and the inner envelope 12 and between the disk-shaped enlargements 30 and 32 i~
evacuated. This is done by evacuating this space 36 with a suitable vacuum pump (not shown), which draws the contents of this space out through tAe small clearance space 97 surrounding the other disk-shaped enlargement 32. (The intake o~ the pump is connected in a conventional manner between the tubular portion 18 of the inner envelope and the surrounding tubular portion 26 of the shroud in a location above the enlargement 32.) While such evacuation is taking place, the walls of space 36 are suitably heated to help drive off absorbed gases. In a preferred form of the evacuation proce s, we alternately pump the space 36 and flush it with an inert gas, such as argon or nitrogen. The flushing gas is introduced through the clearance space 97 in the intervals between the pumping periods.
, ~ ~
~ i3 '~ c3~
LD10,109 After space 36 has been evacuated in this manner to a hard vacuum, a seal is made between the outer periphery of the disk-shaped enlargement 32 and the surrounding region 94 of the shroud 20. This seal is made in essentially the same manner as was used for makin~ the first seal (at 92). More specifically, the shroud region 94 is heated to soften it, thereby causing it to collapse about the outer periphery of the disk-shaped enlargement and form a seal therewith. Because a vacuum is then present in the chamber 36 and also in the region above enlargement 32, there is a pressure differential on opposite sides of the shroud wall which promotes such collapse of the shroud about disk-shaped enlargement 32.
To assure that a hard vacuum is developed and maintained within the chamber 36, we provide, in one form of the invention, a suitable getter 38 within chamber 36. This getter is introduced, preferably, before the shroud is assembled over the inner envelope.
In one form of the invention,~the getter comprises chips of zirconium-titanium alloy dispersed about the inner wall of the shroud This material is a good getter for hydrogen.
The locations (83 and 86 of Fig. 2~ chosen ~or forming the disk-shaped ~nlargements 30 and 32 are such , . . .
, . . . . .
, ,,: , :
~, .
rd O '~ 2 ~ 3 LD10,109 that the enlargements ~o not interfere with sealing the foils 47 and 52 within the tubular portions 16 and 18 of the inner envelope 12. More specifically, the chosen locations 83 and 86 are spaced axially outward from the location of the foils. But this axial spacing is kept sufficiently small so that the presence of the enlargements does not add materially to the overall length of the shrouded lamp.
A significant feature of our shroud-to-inner envelope seals is that each seal is relatively remote ~rom the foil seal at the same end o~ the envelope. In this respect, note in.Fig. 1 that the shroud-to-inner envelope seal at each end of ths lamp is located radially-outward of the foil seal at the same end of the lamp by a distance approximately equal to the radial dimension R of the associated disk-shaped enlargement 30 or 32. This remoteness of the shroud seal from the foil seal is advantageous because it materially reduces the chances that the foil seal will b~ detrimentally affected by the heak involved in making the shroud seal.
It should also be noted that this remoteness between the two seals is achieved without materially increasing the overall length of the lamp since much of the separation between the two seals is in a radial direction rather , ~ . , , ~2~ ~3 LDl0,109 than an axial direction. Some axial separation is, however,required so that the foil seal is located outside the axial boundaries of the associated disk-shaped enlargement.
Another significant advantage of our shroud-to-inner envelope seals is that they can be made with relatively little heat applied for only a short ti~e.
In this respect, it should be noted that because the disk-shaped enlar~ements 30 and 32 extend radially outward almost completely to the inner periphery of the tubular form of the shroud, as best shown in Fig. 5, only a slight displacement of the shroud radially inwardly is required in order to move the shroud material into contact with the portion of the inner envelope to which it sealed. B~cause the amount of this displace~ent is so small, very little heat and time is required to effect it, and thus the chances are substantially reduced that the lamp matrrial in the vicinity of such seal will be detrimentally affected by the heat of the s~al-making operation. This reduced heating cooperates with the remoteness features of the immediately-preceding paragraph further to protect the foil seals from any detrimental effects of the shroud-sealing operation.
, ~?Jl~
LD10,109 Moreover, because we are able to make the shroud-to-inner envelope seals without requiring large amounts of heat and time, we have found that the process parameters are not critical. Minor variations in these parameters can be tolerated without significantly affecting the quality or characteristics oP the resulting seal and the nearby lamp material. '7 Another significant advantage of our lamp and our method of making it is that the lamp can be readily and quickly made with automated equipmsnt. For example, formation of the disk-shaped enlargements (30 and 32) is effected with the simple heating and force-application steps depicted in Fig. 2. Such steps are readily performed on the same machine (lathe 61~ that was used for forming the bulbous central portion 14 of the inner envelope, which central portion 14 is pxeferably formed in a conventional manner ~y heating the starting tubular blank in this region and blowing the heat-softened quartz radially outward. Wh~le the blank is on this same machine and in the same position, the disk-shaped enlargements 30 and 32 are introduced, as above described. In addition, the seals between the shroud and the inner envelope are made by simple and brieP
heating operations (Fig.5), which cause the heat , , : . ~ . `
2 ~3 1 ~
LDla~lo9 softened regions of the shroud to collapse the short distances required to effect high-quality seals to the disk-shaped enlargements 30 and 32.
While the embodiment of Figs. 1-5 includes disk-shaped enlargements (30 and 32) provided at both ends of the lamp for making the shroud-to-inner envelope seals, some of the advantages of our invention can still be realized if an enlargement of this character is provided only at one end of the lamp. At the other end of such a lamp, the seal between the shroud and the inner envelope can be made in a conventional manner, for example, by allowing the heat-softened portion of the tubular shroud to shrink down to the tuhular portion of the inner envelope that it seals to. Such a lamp is illustrated in Fig. 6, where this conventional seal, designated 100, is shown at the left-hand end of the lamp. To facilitate the making of seal 100, the tubular portion 24 of the shroud on the let hand end of the shroud is made only slightly larger than the left-hand-end tubular portion 16 of the inner env~lope. The shroud is then slipped onto the inner envelope from the left hand end of the inner envelope 50 that the larger diameter end of the shroud slips over the bulbous portion 14 of the inner envelope and the disk enlargement 32. Then the seal 100 is made in a conventional manner.
,: ~ , , ` :
.
~'' ?d 1 4 3 LD10,109 One type of lamp where the approach of Fig. 6 is useful is one in which a surface of the shroud is coated with a reflective material to form a reflector which can be located close to the lamp. Such reflective material is indicated at 102 in Fig. 6. At the right-hand side of this lamp the shroud-to-inner envelope seal is the same as in Fig. 1. At the left-hand side of the lamp, the conventional seal 100 of the immediately-preceding paragraph is present.
In a preferred embodiment of the lamp, the inner envelope and the shroud are both of identical quartz~
But our invention in its broader aspects contemplates the use of other vitreous material capable of withstanding the high temperatures developed by operation of the arc tube. It is usually very desirable to use the same material for the shroud and the inner envelope to avoid cracking or sealing problems that might arise because of differ nt coefficients of thermal expansion of two different fusedotogether materials.
But minor differences in the'two materials can often be tolerated. For example, in another embodiment of our invention, we utilize for the shroud quartz which has been heated with a high electric field applied thereto to remove any traces of sodium which can increase '' , . ~`
.', ' ':
, 2~'-.L~
LD10,109 electronic conductivity. Such high resistance quarkz is available from General Electric Company as its sodium-free quartz. This high resistance quartz can be sealed to an inner envelope of ordinary quartz without encountering significant problems of differential thermal expansion. The presence of such high resistance quartz in the shroud is believed to help block sodium loss through the inn~r envelope.
The lamps described hereinabove are especially suited for forward lighting applications in a vehicle, such as an automobile, truck, bus, van or tractor. The aforesaid Application S.N. 157,360 - Hansler et al discloges several different ways in which a lamp of this general type is utilized for such forward lighting, and the present lamps are utilizable in the sam~ ways. For example, referring to Fig. 7 o~ the present application, our lamp is shown at 10 within an automobile headlamp 110~ This headlamp comprises a reflector 112, a lens member 114 at the front of the reflector, and lamp 10 in the space between the reflec~or and the lens.
The reflector 112 has a rear section 118 having mounted thereon a connector 120 with rearwardly-projecting prongs 122 and 124 capable of being connected to an external electrical source of the vehicle. The reflector 112 has a focal point 126 on the axis 128 of , ~
26 2 ~
LDlo,109 the headlamp. The light source 10 is predeterminedly positioned within the reflector 112 so that its mid-portion approximately coincides with the focal point 126 of the reflector. In the embodiment illustrated in Fig.
7, the light source 10 is oriented with its longitudinal axis extending vertically and in a transverse manner relative to the axis 128 of the headlamp.
In one embodiment, the reflector 112 has a parabolic shape with a focal length in the range of about 6 mm to about 35 mm, with a preferred range of about 8 mm to about 30 mm. The lens 114, which is suitably mated to the front portion of,the reflector, is of a transparent material, such as glass or a suitable plastic. The lens has a rear face preferably formed of prism members.
The light source 10 is connected to the rear section of the reflector 112 by means of rel tively heavy support wires 134 and 136 each having one end connected to one of the inleads 48 or 50 of the light source and its other end connected to one of the prongs 122 or 124. The light source 10 is energized via an electrical circuit that extends in series through the prongs and the support wires.
While in the lamps described hereinabove, the chamber 36 between ~he inner envelope and the shroud is ~J ~ 3 LD10,109 evacuated to a hard vacuum, it should be un~erstood that our invention in its broader aspects comprehends lamps of essentially the same structure as shown in Figs. 1 and 6 except including in the chamber 36 a gas having appropriate properties. For example, in certain lamps it is desirable that a predetermined portion of the heat developed by operation of the arcing tube be transferred across the chamber 36 by conduction or convection rather than primarily by radiation, as when a hard vacuum is present. With this consideration in mind, the chamber 36 can be filled with one of the fsllowing gases or mixtures thereof: argon, krypton, xenon, nitrogen, air, helium, and hydrogen. Typical charging pressures are in the range of 0 to 1500 torr.
While in making the lamp of Fig. 1 we prefer to evacuate (or fill) the chamber 36 through one of the seal locations (e.g.,35) before a seal is made at this location, our invention in its broader aspects comprehends the use of a separate sealable tube (such as shown in Fig. 8 at 105~ extending into this chamber through which the cha~ber may be evacuated and/or filled. When such a separate tube i5 used, we complete the seals at 33 and 35 before evacuting (or filling~ the chamber through the separate tube. Then the separate tube 105 is pinched off or otherwise sealed in a , 2 ~ 3 LD10,109 conventional manner to seal the chamber 36.
While we prefer to form the disk-shaped enlargements 30 and 32 before the electrodes 40, 42 and their inlead structures are incorporated in the arc tube, the invention in its broader aspects contemplates forming these enlargements after the ele~trod2s and their inlead structures are incorporated and before the shroud 20 is installedO
~ hile we have shown and described partic~lar embodiments of our invention, it will be obvious to those skilled in the art ~hat various change and modifications may be made without departing from our invention in its broader aspects; and we, therefore, intend herein to cover all such changes and modifications as fall within the true spirit and scope of our in~ention.
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Claims (27)
1. A method of making a discharge lamp that comprises (i) an inner envelope comprising a hollow bulbous portion of vitreous material and two tubular portions of vitreous material joined to and extending in opposite directions from said bulbous portion and (ii) a tubular shroud of vitreous material surrounding said bulbous portion and said tubular portions, the method comprising:
(a) forming a disk-shaped enlargement in each of said tubular portions by heating a localized region of the tubular portion to its softening point and then subjecting said softened localized region to a compressive force (i) that is abruptly applied along the length of said tubular portion and (ii) that drives the softened vitreous material radially outward into a disk formation, (b) placing said tubular shroud over said inner envelope so that each of said disk-shaped enlargements is positioned in alignment with a predetermined portion of said shroud and with the outer periphery of the enlargement closely adjacent but slightly spaced from the inner periphery of said predetermined shroud portion, thereby forming an unsealed chamber between said shroud and said inner envelope and between said LD10,109 disk-shaped enlargements, (c) forming a first seal between the inner periphery of one of said predetermined portions of the shroud and the outer periphery of the disk-shaped enlargement aligned therewith by heating and thereby softening said one predetermined shroud portion and then collapsing said one predetermined shroud portion about the outer periphery of said aligned enlargement, (d) forming a second seal between the inner periphery of the other of said predetermined shroud portions and the outer periphery of the disk-shaped enlargement aligned therewith.
(a) forming a disk-shaped enlargement in each of said tubular portions by heating a localized region of the tubular portion to its softening point and then subjecting said softened localized region to a compressive force (i) that is abruptly applied along the length of said tubular portion and (ii) that drives the softened vitreous material radially outward into a disk formation, (b) placing said tubular shroud over said inner envelope so that each of said disk-shaped enlargements is positioned in alignment with a predetermined portion of said shroud and with the outer periphery of the enlargement closely adjacent but slightly spaced from the inner periphery of said predetermined shroud portion, thereby forming an unsealed chamber between said shroud and said inner envelope and between said LD10,109 disk-shaped enlargements, (c) forming a first seal between the inner periphery of one of said predetermined portions of the shroud and the outer periphery of the disk-shaped enlargement aligned therewith by heating and thereby softening said one predetermined shroud portion and then collapsing said one predetermined shroud portion about the outer periphery of said aligned enlargement, (d) forming a second seal between the inner periphery of the other of said predetermined shroud portions and the outer periphery of the disk-shaped enlargement aligned therewith.
2. A method as defined in claim 2 and further comprising the step of evacuating said chamber.
3. The method of claim 2 in which the evacuation step is carried out by causing flow to occur through a clearance space present between the outer periphery of said other disk shaped enlargement and the inner periphery of the other of said predetermined shroud portions before said second seal is formed.
LD10,109
LD10,109
4. A method as defined in claim 1 and further comprising the step of filling said chamber with a gaseous fill.
5. The method of claim 4 in which said filling step is carried out by causing flow to occur through a clearance space present between the outer periphery of said other disk-shaped enlargement and the inner periphery of the other of said predetermined shroud portions before said second seal is formed.
6. The method of claim 1 in which said second seal is formed by heating and thereby softening said other predetermined shroud portion and then collapsing said other predetermined shroud portion about the outer periphery of said other enlargement.
7. A method of making a discharge lamp that comprises (i) an inner envelope comprising a hollow bulbous portion of vitreous material and two tubular portions of vitreous material joined to and extending in opposite directions from said bulbous portion and (ii) a tubular shroud of vitreous material surrounding said bulbous portion and said tubular portions, the method comprising:
LD10,109 (a) forming a disk-shaped enlargement in one of said tubular portions by heating a localized region of the tubular portion to its softening point and then subjecting said softened localized region to a compressive force (i) that is abruptly-applied along the length of said tubular portion and (ii) that drives the softened vitreous material radially outward into a disk formation, (b) placing said tubular shroud over said inner envelope so that disk-shaped enlargement is positioned in alignment with a first predetermined portion of said shroud and with the outer periphery of the enlargement closely adjacent but slightly spaced from the inner periphery of said first predetermined shroud portion, and (c) forming a joint between the inner periphery of said first predetermined portion of the shroud and the outer periphery of the disk-shaped enlargement aligned therewith by heating and thereby softening said first predetermined shroud portion and then collapsing said first predetermined shroud portion about the outer periphery of said aligned enlargement.
LD10,109
LD10,109 (a) forming a disk-shaped enlargement in one of said tubular portions by heating a localized region of the tubular portion to its softening point and then subjecting said softened localized region to a compressive force (i) that is abruptly-applied along the length of said tubular portion and (ii) that drives the softened vitreous material radially outward into a disk formation, (b) placing said tubular shroud over said inner envelope so that disk-shaped enlargement is positioned in alignment with a first predetermined portion of said shroud and with the outer periphery of the enlargement closely adjacent but slightly spaced from the inner periphery of said first predetermined shroud portion, and (c) forming a joint between the inner periphery of said first predetermined portion of the shroud and the outer periphery of the disk-shaped enlargement aligned therewith by heating and thereby softening said first predetermined shroud portion and then collapsing said first predetermined shroud portion about the outer periphery of said aligned enlargement.
LD10,109
8. A method as defined in claim 7 in which said tubular shroud when placed over said inner envelope includes a second predetermined portion surrounding the other of said tubular portions of said inner envelope, the method further comprising forming a second joint between said second predetermined shroud portion and said other tubular portion of said inner envelope.
9. The method of claim 8 in which said two joints constitute seals for a chamber located between said shroud and said inner envelope and between said disk-shaped enlargement and said second joint, the method further comprising the step of evacuating said chamber.
10. The method of claim 8 in which said two joints constitute seals for a chamber located between said shroud and said inner envelope and between said disk-shaped enlargement and said second joint, the method further comprising the step of filling said chamber with a gaseous fill.
11. A metal-halide discharge lamp comprising:
(a) an inner envelope comprising:
(a1) a hollow bulbous portion of vitreous material containing a fill including a metal halide, LD10,109 (a2) two tubular portions of vitreous material joined to and extending in opposite directions from said bulbous portions, (a3) a disk-shaped enlargement on each of said tubular portions of the same vitreous material as the associated tubular portion projecting radially outward from said associated tubular portion and integral therewith, (b) a tubular shroud of vitreous material surrounding said inner envelope and having predetermined portions respectively surrounding and aligned with said disk-shaped enlargements, said predetermined shroud portions being collapsed about the outer periphery of the disk-shaped enlargement, and in which:
(c) said shroud constitutes an outer wall and said disk-shaped enlargements constitute end walls of a chamber surrounding the tubular portions and the bulbous portion of said inner envelope.
(a) an inner envelope comprising:
(a1) a hollow bulbous portion of vitreous material containing a fill including a metal halide, LD10,109 (a2) two tubular portions of vitreous material joined to and extending in opposite directions from said bulbous portions, (a3) a disk-shaped enlargement on each of said tubular portions of the same vitreous material as the associated tubular portion projecting radially outward from said associated tubular portion and integral therewith, (b) a tubular shroud of vitreous material surrounding said inner envelope and having predetermined portions respectively surrounding and aligned with said disk-shaped enlargements, said predetermined shroud portions being collapsed about the outer periphery of the disk-shaped enlargement, and in which:
(c) said shroud constitutes an outer wall and said disk-shaped enlargements constitute end walls of a chamber surrounding the tubular portions and the bulbous portion of said inner envelope.
12. A lamp as defined in claim 11 and further comprising:
(a) a pair of spaced-apart electrodes within said bulbous portion of said inner envelope, said electrodes having rod portions respectively extending from said LD10,109 bulbous portion into said tubular portions of the inner envelope and supported by the vitreous material of said tubular portions, (b) two conductive inleads respectively projecting into said tubular portions of the inner envelope from outside the inner envelope, (c) a foil member within each tubular portion of the inner envelope electrically connecting the associated inlead and the associated electrode rod portion, the vitreous material of said tubular portion being sealed to said foil member therein to form a foil seal, and in which:
(d) said disk-shaped enlargements are located axially outward of said foil seals.
(a) a pair of spaced-apart electrodes within said bulbous portion of said inner envelope, said electrodes having rod portions respectively extending from said LD10,109 bulbous portion into said tubular portions of the inner envelope and supported by the vitreous material of said tubular portions, (b) two conductive inleads respectively projecting into said tubular portions of the inner envelope from outside the inner envelope, (c) a foil member within each tubular portion of the inner envelope electrically connecting the associated inlead and the associated electrode rod portion, the vitreous material of said tubular portion being sealed to said foil member therein to form a foil seal, and in which:
(d) said disk-shaped enlargements are located axially outward of said foil seals.
13. The lamp of claim 11 in which each of said disk-shaped enlargements is the product of an upsetting operation performed on its associated tubular member, the upsetting operating comprising heating a localized region of the tubular portion to its softening point and then subjecting said softened localized region to a compressive force (i) that is abruptly applied along the length of said tubular portion and (ii) that drives the softened vitreous material radially outward into a disk formation.
LD10,109
LD10,109
14. The lamp of claim 12 in which each of said disk-shaped enlargements is the product of an upsetting operation performed on its associated tubular member, the upsetting operating comprising heating a localized region of the tubular portion to its softening point and then subjecting said softened localized region to a compressive force (i) that is abruptly applied along the length of said tubular portion and (ii) that drives the softened vitreous material radially outward into a disk formation.
15. The lamp of claim 11 in which said inner envelope and said shroud are of quartz, the quartz of said shroud having a substantially lower electronic conductivity than that of the inner envelope.
16. The lamp of claim 11 in which:
(a) said fill includes a sodium halide, and (b) said shroud is sufficiently large that the shroud temperature remains low enough during lamp operation to substantially prevent sodium loss from the inner envelope.
(a) said fill includes a sodium halide, and (b) said shroud is sufficiently large that the shroud temperature remains low enough during lamp operation to substantially prevent sodium loss from the inner envelope.
17. A metal-halide discharge lamp comprising:
(a) an inner envelope comprising:
LD10,109 (a1) a hollow bulbous portion of vitreous material containing a fill including a metal-halide, (a2) two tubular portions of vitreous material joined to and extending in opposite directions from said bulbous portion, (a3) a disk-shaped enlargement on one of said tubular portions of the same vitreous material as said one tubular portion projecting radially outward from said one tubular portion and integral therewith, (b) a tubular shroud of vitreous material surrounding said inner envelope and having a predetermined portion surrounding and aligned with said disk-shaped enlargement, said predetermined shroud portion being collapsed about the outer periphery of the disk-shaped enlargement aligned therewith and forming a seal with the outer periphery of said disk-shaped enlargement, and in which:
(c) said shroud constitutes an outer wall and said disk-shaped enlargement constitutes an end wall of a chamber surrounding the tubular portions and the bulbous portion of said inner envelope.
LD10,109
(a) an inner envelope comprising:
LD10,109 (a1) a hollow bulbous portion of vitreous material containing a fill including a metal-halide, (a2) two tubular portions of vitreous material joined to and extending in opposite directions from said bulbous portion, (a3) a disk-shaped enlargement on one of said tubular portions of the same vitreous material as said one tubular portion projecting radially outward from said one tubular portion and integral therewith, (b) a tubular shroud of vitreous material surrounding said inner envelope and having a predetermined portion surrounding and aligned with said disk-shaped enlargement, said predetermined shroud portion being collapsed about the outer periphery of the disk-shaped enlargement aligned therewith and forming a seal with the outer periphery of said disk-shaped enlargement, and in which:
(c) said shroud constitutes an outer wall and said disk-shaped enlargement constitutes an end wall of a chamber surrounding the tubular portions and the bulbous portion of said inner envelope.
LD10,109
18. A lamp as defined in claim 17 and further comprising:
(a) a pair of spaced-apart electrodes within said bulbous portion of said inner envelope, said electrodes having rod portions respectively extending from said bulbous portion into said tubular portions of the inner envelope and supported by the vitreous material of said tubular portions, (b) two conductive inleads respectively projecting into said tubular portions of the inner envelope from outside the inner envelope, (c) a foil member within each tubular portion of the inner envelope electrically connecting the associated inlead and the associated electrode rod portion, the vitreous material of said tubular portion being sealed to said foil member therein to form a foil seal, and in which:
(d) said disk-shaped enlargement on said one tubular portion of the inner envelope is located axially outward of said foil seal in said one tubular portion.
(a) a pair of spaced-apart electrodes within said bulbous portion of said inner envelope, said electrodes having rod portions respectively extending from said bulbous portion into said tubular portions of the inner envelope and supported by the vitreous material of said tubular portions, (b) two conductive inleads respectively projecting into said tubular portions of the inner envelope from outside the inner envelope, (c) a foil member within each tubular portion of the inner envelope electrically connecting the associated inlead and the associated electrode rod portion, the vitreous material of said tubular portion being sealed to said foil member therein to form a foil seal, and in which:
(d) said disk-shaped enlargement on said one tubular portion of the inner envelope is located axially outward of said foil seal in said one tubular portion.
19. The lamp of claim 17 in which said disk-shaped enlargement is the product of an upsetting operation performed on its associated tubular member, LD10,109 the upsetting operating comprising heating a localized region of the tubular portion to its softening point and then subjecting said softened localized region to a compressive force (i) that is abruptly applied along the length of said tubular portion and (ii) that drives the softened vitreous material radially outward into a disk formation.
20. The lamp of claim 18 in which said disk-shaped enlargement is the product of an upsetting operation performed on its associated tubular member, the upsetting operation comprising heating a localized region of the tubular portion to its softening point and then subjecting said softened localized region to a compressive force (i) that is abruptly applied along the length of said tubular portion and (ii) that drives the softened vitreous material radially outward into a disk formation.
21. The lamp of claim 17 in which said inner envelope and said shroud are of quartz, the quartz of said shroud having a substantially lower electronic conductivity than that of the inner envelope.
LD10,109
LD10,109
22. The lamp of claim 17 in which:
(a) said fill includes a sodium halide, and (b) said shroud is sufficiently large that the shroud temperature remains low enough during lamp operation to substantially prevent sodium loss from the inner envelope.
(a) said fill includes a sodium halide, and (b) said shroud is sufficiently large that the shroud temperature remains low enough during lamp operation to substantially prevent sodium loss from the inner envelope.
23. A metal-halide discharge lamp comprising:
(a) an inner envelope comprising:
(a1) a hollow bulbous portion of vitreous material containing a fill including a metal-halide, (a2) two tubular portions of vitreous material joined to and extending in opposite directions from said bulbous portion, (a3) a disk-shaped enlargement on one of said tubular portions of the same vitreous material as said one tubular portion projecting radially outward from said one tubular portion and intergral therewith, and (b) a tubular shroud of vitreous material surrounding said inner envelope and having a predetermined portion surrounding and aligned with said disk-shaped enlargement, said predetermined shroud portion being collapsed about the outer periphery of the disk-shaped enlargement aligned therewith and forming a LD10,109 joint with the outer periphery of said disk-shaped enlargement.
(a) an inner envelope comprising:
(a1) a hollow bulbous portion of vitreous material containing a fill including a metal-halide, (a2) two tubular portions of vitreous material joined to and extending in opposite directions from said bulbous portion, (a3) a disk-shaped enlargement on one of said tubular portions of the same vitreous material as said one tubular portion projecting radially outward from said one tubular portion and intergral therewith, and (b) a tubular shroud of vitreous material surrounding said inner envelope and having a predetermined portion surrounding and aligned with said disk-shaped enlargement, said predetermined shroud portion being collapsed about the outer periphery of the disk-shaped enlargement aligned therewith and forming a LD10,109 joint with the outer periphery of said disk-shaped enlargement.
24. A vehicle headlamp comprising:
(a) a reflector, (b) a lens at the front of the reflector, and (c) a lamp as defined in claim 11 mounted in a position between said reflector and said lens.
(a) a reflector, (b) a lens at the front of the reflector, and (c) a lamp as defined in claim 11 mounted in a position between said reflector and said lens.
25. A vehicle headlamp comprising:
(a) a reflector, (b) a lens at the front of the reflector, and (c) a lamp as defined in claim 17 mounted in a position between said reflector and said lens.
(a) a reflector, (b) a lens at the front of the reflector, and (c) a lamp as defined in claim 17 mounted in a position between said reflector and said lens.
26. A vehicle headlamp comprising:
(a) a reflector, (b) a lens at the front of the reflector, and (c) a lamp as defined in claim 23 mounted in a position between said reflector and said lens.
(a) a reflector, (b) a lens at the front of the reflector, and (c) a lamp as defined in claim 23 mounted in a position between said reflector and said lens.
27. The invention as defined in any of the preceding claims including any further features of novelty disclosed.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US54457190A | 1990-06-27 | 1990-06-27 | |
| US544,571 | 1990-06-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2042143A1 true CA2042143A1 (en) | 1991-12-28 |
Family
ID=24172730
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2042143 Abandoned CA2042143A1 (en) | 1990-06-27 | 1991-05-09 | Discharge lamp with surrounding shroud and method of making such lamp |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0465083A3 (en) |
| JP (1) | JPH04229942A (en) |
| CA (1) | CA2042143A1 (en) |
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| US7112116B2 (en) | 2003-06-05 | 2006-09-26 | Patent-Treuhand-Gesellschaft für elektrisch Glühlampen mbH | Process for producing an electric lamp with outer bulb |
| US7221098B2 (en) | 2003-06-05 | 2007-05-22 | Patent-Treuhand-Gesellschaft für elektrische Glülampen mbH | Electric lamp with outer bulb and associated support body |
| US7253562B2 (en) | 2003-06-05 | 2007-08-07 | Patent-Treuhand-Gesellschaft fur electrische Glühlampen mbH | Lamp which is closed on two sides |
| US7358673B2 (en) | 2004-07-30 | 2008-04-15 | Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH | Electric lamp which is closed on two sides |
| US7514873B2 (en) | 2005-05-02 | 2009-04-07 | Osram Gesellschaft Mit Beschraenkter Haftung | Electric lamp having an outer bulb |
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| EP0570068B1 (en) * | 1992-05-11 | 1997-08-06 | Koninklijke Philips Electronics N.V. | Capped high-pressure discharge lamp |
| US5388034A (en) * | 1992-09-16 | 1995-02-07 | General Electric Company | Vehicle headlamp comprising a discharge lamp including an inner envelope and a surrounding shroud |
| US5253153A (en) * | 1992-09-16 | 1993-10-12 | General Electric Company | Vehicle headlamp comprising a metal-halide discharge lamp including an inner envelope and a surrounding shroud |
| DE9302382U1 (en) * | 1993-02-18 | 1993-04-15 | Patent-Treuhand-Gesellschaft Fuer Elektrische Gluehlampen Mbh, 8000 Muenchen, De | |
| DE4317369A1 (en) * | 1993-05-25 | 1994-12-01 | Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh | High-pressure discharge lamp and manufacturing method for a high-pressure discharge lamp |
| JPH0773851A (en) * | 1993-09-01 | 1995-03-17 | Agency Of Ind Science & Technol | Discharge lamp |
| JPH08162007A (en) * | 1994-12-06 | 1996-06-21 | Koito Mfg Co Ltd | Discharge lamp device |
| US5576598A (en) * | 1995-08-31 | 1996-11-19 | Osram Sylvania Inc. | Lamp with glass sleeve and method of making same |
| JP3777088B2 (en) * | 2000-11-24 | 2006-05-24 | 株式会社小糸製作所 | Arc tube for discharge lamp and manufacturing method thereof |
| US7097528B2 (en) | 2002-12-27 | 2006-08-29 | Matsushita Electric Industrial Co., Ltd. | Method for producing a high pressure discharge lamp, with sealing portion having first and second glass members |
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| US7038384B2 (en) | 2003-01-14 | 2006-05-02 | Matsushita Electric Industrial Co., Ltd. | High pressure discharge lamp, method for producing the same and lamp unit |
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| DE102004056452A1 (en) * | 2004-11-23 | 2006-05-24 | Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH | Electric lamp, e.g. to act as a metal halogenide lamp, has an outer bulb with a vacuum-sealed longitudinally extended inner bulb with a means of lighting |
| DE102004056453A1 (en) | 2004-11-23 | 2006-05-24 | Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH | Electric lamp with outer bulb |
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| JP4878984B2 (en) * | 2006-10-24 | 2012-02-15 | ハリソン東芝ライティング株式会社 | Discharge lamp and discharge lamp manufacturing method |
| EP1975975A1 (en) | 2007-03-30 | 2008-10-01 | Patent-Treuhand-Gesellschaft Für Elektrische Glühlampen mbH | Construction unit for an electrical light with external pistons |
| JP5186823B2 (en) * | 2007-07-17 | 2013-04-24 | ウシオ電機株式会社 | High pressure discharge lamp and light irradiation device using high pressure discharge lamp |
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| DE102010002397A1 (en) * | 2010-02-26 | 2011-09-01 | Osram Gesellschaft mit beschränkter Haftung | High pressure discharge lamp |
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| US3867661A (en) * | 1973-10-19 | 1975-02-18 | Us Navy | Quick warm-up lamp |
| NL8101723A (en) * | 1981-04-08 | 1982-11-01 | Philips Nv | HIGH PRESSURE MERCURY DISCHARGE LAMP. 080481 HIGH PRESSURE DISCHARGE LAMP. |
| US4891555A (en) * | 1985-11-15 | 1990-01-02 | General Electric Company | Metal vapor discharge lamps |
| US4935668A (en) * | 1988-02-18 | 1990-06-19 | General Electric Company | Metal halide lamp having vacuum shroud for improved performance |
| DE3813421A1 (en) * | 1988-04-21 | 1989-11-02 | Philips Patentverwaltung | HIGH PRESSURE MERCURY VAPOR DISCHARGE LAMP |
-
1991
- 1991-05-09 CA CA 2042143 patent/CA2042143A1/en not_active Abandoned
- 1991-06-25 EP EP19910305715 patent/EP0465083A3/en not_active Withdrawn
- 1991-06-25 JP JP17888191A patent/JPH04229942A/en active Granted
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7112116B2 (en) | 2003-06-05 | 2006-09-26 | Patent-Treuhand-Gesellschaft für elektrisch Glühlampen mbH | Process for producing an electric lamp with outer bulb |
| US7221098B2 (en) | 2003-06-05 | 2007-05-22 | Patent-Treuhand-Gesellschaft für elektrische Glülampen mbH | Electric lamp with outer bulb and associated support body |
| US7253562B2 (en) | 2003-06-05 | 2007-08-07 | Patent-Treuhand-Gesellschaft fur electrische Glühlampen mbH | Lamp which is closed on two sides |
| US7745999B2 (en) | 2003-06-05 | 2010-06-29 | Osram Gesellschaft Mit Beschraenkter Haftung | Lamp which is closed on two sides |
| US7358673B2 (en) | 2004-07-30 | 2008-04-15 | Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH | Electric lamp which is closed on two sides |
| US7514873B2 (en) | 2005-05-02 | 2009-04-07 | Osram Gesellschaft Mit Beschraenkter Haftung | Electric lamp having an outer bulb |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0465083A2 (en) | 1992-01-08 |
| JPH04229942A (en) | 1992-08-19 |
| JPH0565978B2 (en) | 1993-09-20 |
| EP0465083A3 (en) | 1993-01-20 |
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