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EP 0 599 581 B1 |
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EUROPEAN PATENT SPECIFICATION |
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Mention of the grant of the patent: |
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24.04.1996 Bulletin 1996/17 |
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Date of filing: 22.11.1993 |
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Starting source and method of fabrication
Zündungsquelle und Herstellungsverfahren derselben
Source d'amorçage et son procédé de fabrication
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Designated Contracting States: |
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BE DE FR GB NL |
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Priority: |
20.11.1992 US 979140 25.11.1992 US 982209
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Date of publication of application: |
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01.06.1994 Bulletin 1994/22 |
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Proprietor: FLOWIL INTERNATIONAL LIGHTING (HOLDING) B.V. |
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NL-1077 ZX Amsterdam (NL) |
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Inventors: |
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- Zaslavsky, Gregory
Marblehead, MA 01945 (US)
- Nortrup, Edward H.
Bedford,
New Hampshire 03110 (US)
- Lima, Joseph V.
Salem,
MA 01970 (US)
- Parrott, Richard A.
Merrimack,
New Hampshire 03054 (US)
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Representative: Butler, Michael John |
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FRANK B. DEHN & CO.
Imperial House
15-19 Kingsway London, WC2B 6UZ London, WC2B 6UZ (GB) |
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References cited: :
EP-A- 0 313 027
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US-A- 5 248 273
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Note: Within nine months from the publication of the mention of the grant of the European
patent, any person may give notice to the European Patent Office of opposition to
the European patent
granted. Notice of opposition shall be filed in a written reasoned statement. It shall
not be deemed to
have been filed until the opposition fee has been paid. (Art. 99(1) European Patent
Convention).
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[0001] This invention relates to a starting source for an arc discharge lamp, and to a method
of manufacture thereof.
[0002] High pressure metal halide arc discharge lamps typically comprise an arc tube which
encloses an ionisable fill material and two electrodes at opposing ends of the tube.
To reduce the time it takes to start the lamp, a starter electrode may be disposed
inside the arc tube near one of the main electrodes, as shown in US-A-3,900,761. A
discharge can be initiated between the starter electrode and one of the main electrodes
at a voltage that is much lower than the voltage required to ignite an arc between
the two main electrodes. The ultraviolet radiation and plasma from this discharge
enhance discharge formation in the arc tube between the two main electrodes.
[0003] US-A-4,818,915 discloses a starting source which is separate from the arc tube and
that typically has a borosilicate glass envelope enclosing an ionizable fill material
and a single electrode. The single electrode additionally has a getter which removes
certain gases when the envelope heats and outgasses. These gases, particularly oxygen,
hydrogen, and nitrogen, contaminate the fill material. When energized, the starting
source produces ultraviolet radiation which illuminates the path between the main
electrodes within the arc tube, thus decreasing the time for generating a high intensity
arc discharge.
[0004] The use of a getter increases the number of components in the starting source, limits
how small the starting source can be made, and limits the operation of the starting
source to a particular temperature range. With a getter, the starting source is sensitive
to location within the lamp because of outgassing and the getter temperature range.
Because of these size and location requirements, a starting source with a getter cannot
be used for all applications, such as double-ended lamps which have a small diameter
outer envelope.
[0005] A typical process for making a starting source begins with fabricating an electrode
assembly which is inserted into a tube. The electrode assembly typically has a number
of welded parts. As described in US-A-4,818,915 an electrode assembly includes an
electrode which is welded to a lead for coupling electrical energy and which may additionally
support a getter. Since the parts are welded, it can be difficult to produce these
starting sources with an automated system. Electrode assemblies are fabricated first,
then manually loaded onto trays.
[0006] Viewed from one aspect there is provided a starting source for an arc discharge lamp
comprising an envelope having a seal and an interior region which contains a fill
material for supporting an ultraviolet emitting discharge, an electrode in the interior
region and a lead for carrying electrical energy to the electrode,
characterised in that the electrode comprises a conductive ribbon which extends from the seal into the
interior region of the envelope.
[0007] Viewed from another aspect there is provided a method of making a starting source
for an arc discharge lamp comprising the steps of forming an envelope having an interior
region, providing an electrode in the interior region, providing a lead for carrying
electrical energy to the electrode, providing a fill material in the interior region
for supporting an ultraviolet emitting discharge, and closing the envelope with a
seal,
characterised in that the electrode comprises a conductive ribbon which extends from the seal into the
interior region of the envelope.
[0008] Preferred embodiments of the present invention may provide a starting source for
an arc discharge lamp which comprises a sealed ultraviolet transmissive envelope enclosing
a fill material which supports an ultraviolet emitting discharge. The sealed envelope
has a seal and an interior region. A conductive ribbon extends from the press seal
into the interior region of the envelope. A wire lead carries electrical energy to
the conductive ribbon.
[0009] In preferred embodiments, the fill material comprises argon, and the conductive ribbon
comprises molybdenum.
[0010] Preferred embodiments of the present invention may further provide a method for making
an ultraviolet radiation starting source for an arc discharge lamp comprises passing
a gaseous fill material through a tube which has a first end, a second end, and an
interior region; inserting conductive a ribbon and a wire lead into first end; forming
a first press seal at the first end so that the ribbon extends into the interior region
of the tube and the wire lead extends to the exterior of the sealed tube; pumping
from the second end of the tube to create a desired pressure within the tube; and
forming a second seal at the second end of the tube to produce a sealed envelope enclosing
the fill material and the ribbon.
[0011] In preferred embodiments, the seal forming steps each comprise forming a press seal.
They may also comprise the steps of obtaining a remaining portion of the tube after
the second seal has been formed and after the sealed envelope is removed, introducing
a molybdenum ribbon and a wire lead into an open end of the remaining portion, and
forming a seal at the open end to form a second sealed envelope.
[0012] In yet further preferred embodiments the present invention may provide a metal vapour
arc discharge lamp comprising a sealed arc tube which encloses a first fill material
and two electrodes; an ultraviolet radiation starting source comprising an ultraviolet-transmissive
sealed envelope, a second fill material within the sealed envelope, a molybdenum ribbon
extending from a seal into the interior region of the sealed envelope, and a wire
lead for carrying electrical energy to the ribbon; an outer light-transmissive envelope
enclosing the arc tube and the UV source; and a means for coupling electrical energy
to the two electrodes of the arc tube and to the UV source.
[0013] Also in preferred embodiments of the present invention, the ribbon and the wire lead
may each be mounted on a spool and inserted into the tube by rotating each spool by
a predetermined amount. After the seal is formed, the ribbon and wire are cut external
to the tube. The method may further comprise vacuum pumping to create a desired pressure
and forming a second seal at a second end of the tube to form a sealed envelope. After
formation of a seal, the ribbon and the wire lead are in non-bonded contact with each
other over a portion of the length of the ribbon.
[0014] In other preferred embodiments, the present invention provides a method for making
a starting source for an arc discharge lamp that comprises the steps of providing
an ultraviolettransmissive tube having an opening, inserting a conductive ribbon and
wire lead into the opening, the ribbon and the wire lead not being attached to each
other prior to formation of a seal at or near the opening in the tube, and forming
a seal at or near the opening of the tube such that the tube material urges the ribbon
and the wire lead together into electrical connection.
[0015] Further preferred methods of the present invention provide a system for producing
a starting source in which the ribbon and the wire lead may be inserted into the tube
without welding or other bonding, thus, eliminating electrode preassembly. The ribbon
and the wire lead can be fed manually or automatically. Such a method makes it easier
to produce starting sources with an automated system.
Fig. 1 shows a cross-sectional view of a prior art metal halide lamp,
Figs. 2(a)-2(d) illustrate the steps to produce a according to an embodiment of the
present invention,
Figs. 3(a)-3(c) illustrate the steps to produce a according to another embodiment
of the present invention, and
Fig. 4 is a pictorial representation of an apparatus for producing a starting source
according to an embodiment of the present invention.
[0016] A prior art metal halide arc discharge lamp 10 is shown in Fig. 1. A sealed envelope
12 encloses a cylindrical quartz sleeve 14. The sleeve 14 surrounds an arc tube 16
which encloses two electrodes 18 located at opposite ends of the arc tube and a fill
material, e.g., a combination of mercury, metal halides, and argon. Each electrode
is coupled to a molybdenum ribbon 20 which is enclosed within a seal 22 that hermetically
seals the arc tube. Electrical energy is coupled from a lamp base 28 through a lamp
stem 30 and leads 32 and 26 to the electrodes 18 in the arc tube 16.
[0017] A starting source 24 has a sealed envelope 34 that encloses an electrode 25. The
electrode 25 is coupled to the lead 26, and is capacitively coupled to the lead 32
which may include a conductor that is helically wrapped around the envelope 34. A
typical starting source is about 4.0 mm in diameter and 15.0 to 20.0 mm in overall
length. Other details relating to the prior art starting source 24 are discussed in
US-A-4,818,915.
[0018] Figs. 2(a)-2(d) represent the steps to produce a starting source according to a preferred
embodiment of the present invention. Referring to Fig. 2(a), a molybdenum ribbon 40
and a nickel wire 42 are positioned at a lower end 46 of a cylindrical quartz tube
44. The ribbon and wire are placed together, without being bonded to each other, and
are inserted into the lower end 46 of tube 44. When inserted, the ribbon 40 extends
further into the interior of the tube 44 than the wire 42, as shown in Fig. 2(b).
The ribbon 40 has sharp edges which are produced by rollers. These edges provide high
electric field concentration, which results in reliable breakdown.
[0019] A fill material, such as argon, can be introduced into an upper end 48 of the tube
and flows downwardly through the tube and out the lower end 46. A seal 50 may be formed
in the lower portion of the tube 44 by heating the tube and pressing the lower end
together (Fig. 2(c)), a technique well known in the art. Referring to Fig. 2(d), coupled
to the tube at upper end 48 is a vacuum system 56 which reduces the pressure in the
tube down to a desired level, such as 666-2666 Pa (5-20 Torr). The vacuum system 56
may be coupled to the tube after the first seal is pressed, or it may be coupled during
the entire process and activated only when needed to reduce pressure. A second seal
58, (shown as part of the remaining tube in Fig. 2(d)) is formed at the upper end
of tube 44.
[0020] The resulting starting source 60 comprises a sealed envelope 62 which encloses a
fill material 64, typically argon, and a strip 66 of molybdenum ribbon which is hermetically
sealed within the envelope 62. The wire 42 is located in a portion of the seal area
so as to maintain electrical contact with the ribbon 40, but is outside the interior
of the sealed envelope 62. A second seal 72 closes one end of a remaining portion
70 of tube 44.
[0021] Referring to Fig. 3(a), a second molybdenum ribbon 76, and a wire 78 are positioned
at an open end 80 of a dome 74, which corresponds to remaining portion 70. The vacuum
system is temporarily removed, and the ribbon and wire are positioned in the interior
82 of dome 74. The vacuum system 56 reduces the pressure within dome 74 (Fig. 3(b)),
and seal 84 is formed at the lower end of the dome (Fig. 3(c)). This process results
in a second starting source similar to starting source 60.
[0022] Referring to Fig. 4, an automatic feeding system 90 includes molybdenum ribbon spool
92 and wire spool 94. These spools hold lengths of ribbon 96 and wire 98, and feed
predetermined lengths them together into quartz tube 100 when they are rotated a desired
amount. The quartz tube 100 may be positioned with its upper end in an exhaust tube
102 (part of the vacuum system). Adjacent to a lower end of the tube are press feet
104 which can form a seal. In operation, the spools feed the ribbon and wire into
the tube, press feet 104 form a seal as represented in Figs. 2(c) and 3(c), and the
ribbon and wire are cut below the seal. The interior of the tube 100 is then pumped,
and a seal is formed at the upper end to finish the starting source. The ribbon and
the wire are unattached prior to formation of a seal. After formation of a seal, the
tube material may urge the wire and the ribbon into contact, thereby forming a reliable
electrical connection without requiring welding or other bonding techniques. Another
tube is loaded into exhaust tube 102 and the procedure is repeated. The wire and ribbon
are fed without using adhesives or other bonding techniques, such as welding or soldering.
[0023] The resulting starting sources have been produced with dimensions of about 2.5 mm
in diameter and about 10.0 mm long. The molybdenum ribbon is preferably about 0.02
mm to 0.03 mm thick, 1.0 mm wide, and about 4.0 to 7.0 mm long, of which about 2.0
mm to 3.0 mm is within the envelope. The wire has been described as nickel, but other
conductors, such as tungsten or molybdenum may be used, depending on the temperature
of the starter electrode and the lamp. The fill material may be substantially only
argon, or may include other materials, such as mercury. The tube may be quartz, Vycor,
or some other high temperature alumina silicate glass.
[0024] Life tests have been performed on samples in which the ribbon and wire were manually
fed into the tube without being bonded together. These samples were 25.0 mm in length
and 4.0 mm in diameter and had a fill pressure of 666-1333 Pa (5-10 Torr). Four samples
were tested in an air oven for accelerated testing. For 500 hours, the oven was set
to 250°C, and for the next 3864 hours the oven was set to 340°C. No apparent deterioration
has been detected. In another test, five 100 watt metal halide lamps were made with
starting sources as described above. The lamps reached 1560 hours of operation. The
starting characteristics were checked every 500 hours. The seals of the starting sources
remained hermetic, and the discharge was sufficient to provide instant starting.
[0025] A starting source of the present invention may be relatively inexpensive and easy
to produce compared to prior art starting sources. The conductive ribbon is used in
the seal to create a hermetic seal, and as an electrode. The source may be produced
so that the only materials within the envelope are the gaseous fill material and the
molybdenum ribbon. Fewer parts are necessary, no getter is used, no mercury is needed,
and the starting source can be made smaller than prior art devices.
[0026] Embodiments of the present invention should provide a simplified method for fabricating
a starting source which has fewer components than prior art devices, and which may
operate under a broad range of conditions.
1. A starting source for an arc discharge lamp comprising an envelope (44;74;100) having
a seal (50;84) and an interior region which contains a fill material for supporting
an ultraviolet emitting discharge, an electrode (66;76;96) in the interior region
and a lead (42;78;98) for carrying electrical energy to the electrode, characterised in that the electrode comprises a conductive ribbon (40,66;76;96) which extends from the
seal (50;84) into the interior region of the envelope (44;74;100).
2. A starting source as claimed in claim 1, characterised in that the ribbon (40,66;76;96) comprises molybdenum.
3. A starting source as claimed in claim 1 or 2, characterised in that the fill material comprises argon.
4. A starting source as claimed in claim 1, 2 or 3, characterised in that the interior region is not provided with a getter.
5. A starting source as claimed in any preceding claim, characterised in that the lead (42;78) is held in electrical contact against the ribbon (40,66;76) within
the area of the seal (50;84).
6. A starting source as claimed in claim 5, characterised in that the lead (42;78) does not extend into the interior region.
7. An arc discharge lamp characterised in that it is provided with a starting source as claimed in any preceding claim.
8. A method of making a starting source for an arc discharge lamp comprising the steps
of forming an envelope (44;74;100) having an interior region, providing an electrode
(66;76;96) in the interior region, providing a lead (42;78;98) for carrying electrical
energy to the electrode, providing a fill material in the interior region for supporting
an ultraviolet emitting discharge, and closing the envelope with a seal (50;84), characterised in that the electrode (66;76;96) comprises a conductive ribbon which extends from the seal
(50;84) into the interior region of the envelope (44;74;100).
9. A method as claimed in claim 8, characterised in that the ribbon (40,66;76;96) and the lead are placed in contact and the seal (50;84)
is formed around them, so that they form an electrical connection.
10. A method as claimed in claim 8 or 9, characterised in that the ribbon (40,66;76;96) and the lead (42;78;98) are supplied separately as lengths
which are cut into desired sections.
11. A method as claimed in claim 8, 9 or 10, characterised by the steps of providing a tube (44;100) to form the envelope, passing the fill material
through a tube, inserting the ribbon (40,66;76;96) and the lead (42;78;98) into the
tube at one end, forming said seal (50;84) at said one end around the ribbon and lead,
pumping from the other end (48) of the tube (44;100) to create a desired pressure
within the tube, and forming a second seal (58) at the end of the tube (62).
12. A method as claimed in claim 11, characterised in that after the second seal has been formed, the envelope is removed and a remaining portion
(70) of the tube (44;100) is used to make a further starting source.
1. Zündquelle für eine Bogenentladungslampe, die eine Hülle (44; 74; 100) mit einer Dichtung
(50; 84) und einen Innenbereich umfaßt, der ein Füllmaterial zum Unterstützen einer
ultraviolettemittierenden Entladung, eine Elektrode (66; 76; 96) im Innenbereich und
eine Zuleitung (42; 78; 98) zum Zuführen von elektrischer Energie zu der Elektrode
enthält,
dadurch gekennzeichnet, daß die Elektrode ein leitendes Band (40, 66; 76; 96) umfaßt,
das sich von der Dichtung (50; 84) in den Innenbereich der Hülle (44; 74; 100) erstreckt.
2. Zündquelle nach Anspruch 1,
dadurch gekennzeichnet, daß das Band (40, 66; 76; 96) Molybdän enthält.
3. Zündquelle nach Anspruch 1 oder 2,
dadurch gekennzeichnet, daß das Füllmaterial Argon enthält.
4. Zündquelle nach Anspruch 1, 2 oder 3,
dadurch gekennzeichnet, daß der Innenbereich nicht mit einem Getter versehen ist.
5. Zündquelle nach einem der vorhergehenden Ansprüche,
dadurch gekennzeichnet, daß die Zuleitung (42; 78) im Bereich der Dichtung (50; 84)
in elektrischem Kontakt gegen das Band (40, 66; 76) gehalten ist.
6. Zündquelle nach Anspruch 5,
dadurch gekennzeichnet, daß sich die Zuleitung (42; 78) nicht in den Innenbereich
erstreckt.
7. Bogenentladungslampe,
dadurch gekennzeichnet, daß sie mit einer Zündquelle nach einem der vorhergehenden
Ansprüche versehen ist.
8. Verfahren zur Herstellung einer Zündquelle für eine Bogenentladungslampe, das folgende
Schritte umfaßt: Bilden einer Hülle (44; 74; 100) mit einem Innenbereich, Vorsehen
einer Elektrode (66; 76; 96) in dem Innenbereich, Vorsehen einer Zuleitung (42; 78;
98) zum Zuführen von elektrischer Energie zur Elektrode, Vorsehen eines Füllmaterials
in dem Innenbereich zum Unterstützen einer ultraviolettemittierenden Entladung, und
Abschließen der Hülle mit einer Dichtung (50; 84),
dadurch gekennzeichnet, daß die Elektrode (66; 76; 96) ein leitendes Band umfaßt,
das sich von der Dichtung (50; 84) in den Innenbereich der Hülle (44; 74; 100) erstreckt.
9. Verfahren nach Anspruch 8,
dadurch gekennzeichnet, daß das Band (40, 66; 76; 96) und die Zuleitung in Kontakt
miteinander versetzt werden und die Dichtung (50; 84) um sie herum ausgebildet wird,
so daß sie eine elektrische Verbindung bilden.
10. Verfahren nach Anspruch 8 oder 9,
dadurch gekennzeichnet, daß das Band (40, 66; 76; 96) und die Zuleitung (42; 78; 98)
separat als Längen zugeführt werden, die in gewünschte Abschnitte geschnitten werden.
11. Verfahren nach Anspruch 8, 9 oder 10,
gekennzeichnet durch die folgenden Schritte: Vorsehen einer Röhre (44; 100) zum Bilden
der Hülle, Hindurchführen des Füllmaterials durch eine Röhre, Einsetzen des Bandes
(40, 66; 76; 96) und der Zuleitung (42; 78; 98) in die Röhre an einem Ende, Bilden
der Dichtung (50; 84) an dem einen Ende und um das Band und die Zuführung, Abpumpen
am anderen Ende (48) der Röhre (44; 100), um einen gewünschten Druck innerhalb der
Röhre zu erzeugen, und Bilden einer zweiten Dichtung (58) an dem Röhrenende (62).
12. Verfahren nach Anspruch 11,
dadurch gekennzeichnet, daß die Hülle, nachdem die zweite Dichtung gebildet wurde,
entfernt wird und ein verbleibender Abschnitt (70) der Röhre (44; 100) dazu verwendet
wird, eine weitere Zündquelle herzustellen.
1. Source d'amorçage pour une lampe à décharge en arc comprenant une ampoule (44; 74;
100) présentant un scellement (50; 84) et une région intérieure qui contient un matériau
de remplissage pour maintenir une décharge émettant dans l'ultraviolet, une électrode
(66; 76; 96) dans la région intérieure et un conducteur (42; 78; 98) pour transporter
l'énergie électrique jusqu'à l'électrode, caractérisée en ce que l'électrode comprend un ruban conducteur (40, 66; 76; 96) qui fait saillie depuis
le scellement (50; 84) dans la région intérieure de l'ampoule (44; 74; 100).
2. Source d'amorçage selon la revendication 1, caractérisé en que le ruban (40, 66; 76; 96) comprend du molybdène.
3. Source d'amorçage selon la revendication 1 ou 2, caractérisée en ce que le matériau de remplissage comprend de l'argon.
4. Source d'amorçage selon la revendication 1, 2 ou 3, caractérisée en ce que la région intérieure ne comprend pas de getter.
5. Source d'amorçage selon l'une quelconque des revendications précédentes caractérisée en ce que le conducteur (42; 78) est maintenu en contact électrique avec le ruban (40, 66;
76) à l'intérieur de la zone du scellement (50; 84).
6. Source d'amorçage selon la revendication 5, caractérisée en ce que le conducteur (42; 78) ne fait pas saillie dans la région intérieure.
7. Lampe à décharge en arc caractérisée en ce qu'elle comprend une source d'amorçage selon l'une quelconque des revendications précédentes.
8. Procédé de réalisation d'une source d'amorçage pour une lampe à décharge en arc, comprenant
les étapes suivantes :
former une ampoule (44; 74; 100) présentant une région intérieure,
disposer une électrode (66; 76; 96) dans la région intérieure,
disposer un conducteur (42; 78; 98) destiné à transporter l'énergie électrique jusqu'à
l'électrode,
disposer un matériau de remplissage dans la région intérieure pour maintenir une décharge
émettant dans l'ultraviolet, et
refermer l'ampoule avec un scellement (50; 84),
caractérisé en ce que l'électrode (66; 76; 96) comprend un ruban conducteur qui fait saillie du scellement
(50; 84) dans la région intérieure de l'ampoule (44; 74; 100).
9. Procédé selon la revendication 8, caractérisé en ce que le ruban (40, 66; 76; 96) et le conducteur sont placés en contact, et que le scellement
(50; 84) est formé autour d'eux, de manière à assurer une connexion électrique.
10. Procédé selon la revendication 8 ou 9, caractérisé en ce que le ruban (40, 66; 76; 96) et le conducteur (42; 78; 98) sont apportés séparément
à des longueurs où ils sont coupés en des longueurs souhaitées.
11. Procédé selon la revendication 9, 9 ou 10,
caractérisé par les étapes suivantes :
prendre un tube (44; 100) pour former l'ampoule,
introduire le matériau de remplissage dans le tube,
insérer le ruban (40, 66; 76; 96) et le conducteur (42; 78; 98) à l'intérieur du tube
à une extrémité,
former le dit scellement (50; 84) à la dite une extrémité autour du ruban et du conducteur,
pomper à partir de l'autre extrémité (48) du tube (44; 100) pour créer une pression
désirée à l'intérieur du tube, et
faire un deuxième scellement (58) à l'extrémité du tube (62).
12. Procédé selon la revendication 11, caractérisé en ce que, après que le deuxième scellement ait été formé, l'ampoule est ôtée et une partie
restante (70) du tube (44; 100) est utilisée pour réaliser une autre source d'amorçage.