Patent EP0055049A1 successfully refreshed from Google Patents.
EP0055049A1
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Discharge lamp arc tubes
Assignee: EMI Group Ltd
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Filing: 1981-12-07
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Granted: —
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Expires: 2001-12-07
Abstract
Abstract An arc discharge lamp is provided using sealing compositions comprising mainly Al 2 O 3 -SiO 2 -Mg0 selected from compositions lying within the area ABCDEFGH on the undernoted ternary phase diagram and methods of using these are described. Preferred compositions include between 15 to 28% by weight of MgO and 13 to 21% by weight of A1 2 0 3 since these have lower melting points than others in the group. The sealing compositions are used to seal end closure members of alumina or cermet to ceramic arc tubes for use in discharge lamps. The compositions are selected to have linear expansion co-ef- ficients compatible with the materials of the end closures and arc tubes. The methods described give sealing times of between 3 and 4 minutes.
Inventors
- 👤 Peter Hing
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 22:59
CPC Classifications
C; C04; C04B; C04B37/00; C04B37/02; C04B37/023; C04B37/025; H; H01; H01J; H01J61/00; H01J61/02; H01J61/36; C04B2237/00; C04B2237/02; C04B2237/10; C04B2237/30; C04B2237/32; C04B2237/34; C04B2237/343; C04B2237/40; C04B2237/401; C04B2237/50; C04B2237/76; C04B2237/765
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
60 words
An arc tube for a discharge lamp said arc tube comprising an envelope of polycrystalline alumina, sapphire or a spinel and one or more end closures hermetically sealed thereto by a sealing composition wherein said sealing composition comprises . silica, alumina and magnesia in proportions such that said composition falls within the area ABCDEFG on the accompanying ternary phase diagram.
Claim 2
Dependent Claim
60 words
An arc tube for a discharge lamp said arc tube comprising an envelope of polycrystalline alumina, sapphire or a spinel and one or more end closures hermetically sealed thereto by a sealing composition wherein said sealing composition comprises . silica, alumina and magnesia in proportions such that said composition falls within the area ABCDEFG on the accompanying ternary phase diagram.
Claim 3
Dependent Claim
31 words
An arc tube for a discharge lamp according to claim 1 wherein the composition falls within the area ABCDEFG but outside the area IJKLM on the said accompanying ternary phase diagram.
Claim 4
Dependent Claim
24 words
An arc tube for a discharge lamp according to claim 1 wherein said sealing composition includes between 15 to 28% by weight of MgO.
Claim 5
Dependent Claim
26 words
An arc tube for a discharge lamp according to claim 3 wherein said sealing composition includes 13 to 21% by weight of Al 2 O 3
Claim 6
Dependent Claim
32 words
An arc tube for a discharge lamp according to claim 1 wherein said sealing composition includes up to 5% by weight of nucleating agent selected from phosphorous pentoxide, titanium, zirconia or chromia.
Claim 7
Dependent Claim
25 words
An arc tube for a discharge lamp according to claim 1 wherein said sealing composition includes up to about 5% by weight of boric oxide.
Claim 8
Dependent Claim
25 words
An arc tube for a discharge lamp according to claim 1 wherein said sealing composition includes up to 10% by weight of rare earth oxides.
Claim 9
Dependent Claim
37 words
An arc tube for a discharge lamp according to claim 1 wherein said sealing composition comprises 28.00% by weight of MgO; 20.00% by weight of A1 2 0 3 and 52.00% by weight of Si0 2 .
Claim 10
Dependent Claim
45 words
An arc tube for a discharge lamp according to claim 1 wherein said sealing composition comprises 26.67% by weight of MgO; 19.05% by weight of A1 2 0 3 ; 49.52% by weight of SiO 2 and 4.76% weight of B 2 0 3 .
Claim 11
Dependent Claim
34 words
An arc tube for a discharge lamp according to claim 1 wherein the sealing composition comprises 15.2% by weight of MgO; 42% by weight of A1203 and 42.8% by weight of Si0 2 .
Claim 12
Dependent Claim
43 words
An arc tube for a discharge lamp according to claim 1 wherein the sealing composition comprises 15.53% by weight of MgO; 36.89% by weight of A1 2 0 3 ; 44.66% by weight of SiO 2 and 2 .91% by weight of B203.
Claim 13
Dependent Claim
22 words
An arc tube for a discharge lamp according to claim 1 wherein the end closure member is made from alumina or mobium.
Claim 14
Dependent Claim
29 words
An arc tube for a discharge lamp according to claim 1 wherein said end closure is made from cermet material having a volume fraction ranging from 0.045 to 0.2.
Claim 15
Dependent Claim
23 words
An arc tube for a discharge lamp according to claim 13 wherein the cermet material comprises alumina and tungsten or alumina and molybdenum.
Claim 16
Dependent Claim
20 words
An arc tube for a discharge lamp according to any preceding claim wherein the lamp comprises a metal halide lamp.
Claim 17
Independent Claim
232 words
A method of producing an arc tube for a discharge lamp, said arc tube being a ceramic arc tube selected from polycrystalline alumina, sapphire or a spinel which method comprises the steps of forming a first end closure assembly, said end closure assembly including an end closure member and connected thereto and electrode and conducting member, applying a first sealing composition comprising silica, alumina and magnesia to said first end closure member or said arc tube, heating said first sealing composition to its softening temperature and pressing the first end closure member into contact with the arc tube or vice versa, filling the arc tube with a fill appropriate for said discharge lamp, forming a second end closure assembly, said second end closure assembly including a second end closure member and connected thereto an electrode and conducting member, applying a second sealing composition comprising silica, alumina and magnesia to said second end closure member or the other end of said arc tube, heating said second sealing composition to its softening temperature and pressing the second end closure member into contact with the other end of said arc tube or vice versa whereby said first and second end closure members with their respective electrodes and conducting members are hermetically sealed to the'arc tube and wherein the seal of the first sealing composition is visually distinguishable from the seal of the second sealing composition.
Claim 18
Independent Claim
232 words
A method of producing an arc tube for a discharge lamp, said arc tube being a ceramic arc tube selected from polycrystalline alumina, sapphire or a spinel which method comprises the steps of forming a first end closure assembly, said end closure assembly including an end closure member and connected thereto and electrode and conducting member, applying a first sealing composition comprising silica, alumina and magnesia to said first end closure member or said arc tube, heating said first sealing composition to its softening temperature and pressing the first end closure member into contact with the arc tube or vice versa, filling the arc tube with a fill appropriate for said discharge lamp, forming a second end closure assembly, said second end closure assembly including a second end closure member and connected thereto an electrode and conducting member, applying a second sealing composition comprising silica, alumina and magnesia to said second end closure member or the other end of said arc tube, heating said second sealing composition to its softening temperature and pressing the second end closure member into contact with the other end of said arc tube or vice versa whereby said first and second end closure members with their respective electrodes and conducting members are hermetically sealed to the'arc tube and wherein the seal of the first sealing composition is visually distinguishable from the seal of the second sealing composition.
Claim 19
Dependent Claim
39 words
A method of providing an arc tube according to claim 16 where said first and second sealing compositions comprising silica alumina and magnesia in such proportions that they fall within the area ABCDEFG on the accompanying ternary phase diagram.
Claim 20
Dependent Claim
25 words
A method of providing an arc tube according to claim 16 where said first sealing composition is selected from Table 2 of the accompanying specification.
Claim 21
Dependent Claim
19 words
A method of providing an arc tube according to claim 16 where said first seal has a whitish colour.
Claim 22
Dependent Claim
17 words
An arc tube whenever produced by a method according to any one of claims 16 to 20.
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GB1374063A
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