GB2085650A - High-pressure discharge lamp - Google Patents
High-pressure discharge lamp Download PDFInfo
- Publication number
- GB2085650A GB2085650A GB8127644A GB8127644A GB2085650A GB 2085650 A GB2085650 A GB 2085650A GB 8127644 A GB8127644 A GB 8127644A GB 8127644 A GB8127644 A GB 8127644A GB 2085650 A GB2085650 A GB 2085650A
- Authority
- GB
- United Kingdom
- Prior art keywords
- envelope
- discharge lamp
- lamp
- discharge
- pressure discharge
- 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.)
- Withdrawn
Links
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims abstract description 18
- 229910052708 sodium Inorganic materials 0.000 claims abstract description 18
- 239000011734 sodium Substances 0.000 claims abstract description 18
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 16
- 239000010955 niobium Substances 0.000 claims description 6
- 239000007789 gas Substances 0.000 claims description 5
- 229910052758 niobium Inorganic materials 0.000 claims description 5
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 claims description 5
- 239000000463 material Substances 0.000 claims 3
- 239000011521 glass Substances 0.000 abstract description 4
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- 238000005336 cracking Methods 0.000 description 4
- 239000004568 cement Substances 0.000 description 3
- 239000000919 ceramic Substances 0.000 description 3
- MJGFBOZCAJSGQW-UHFFFAOYSA-N mercury sodium Chemical compound [Na].[Hg] MJGFBOZCAJSGQW-UHFFFAOYSA-N 0.000 description 3
- 229910001507 metal halide Inorganic materials 0.000 description 3
- 150000005309 metal halides Chemical class 0.000 description 3
- 229910001023 sodium amalgam Inorganic materials 0.000 description 3
- 229910000497 Amalgam Inorganic materials 0.000 description 2
- 230000032683 aging Effects 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005286 illumination Methods 0.000 description 2
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 2
- 229910052754 neon Inorganic materials 0.000 description 2
- GKAOGPIIYCISHV-UHFFFAOYSA-N neon atom Chemical compound [Ne] GKAOGPIIYCISHV-UHFFFAOYSA-N 0.000 description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000008034 disappearance Effects 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- 229910052724 xenon Inorganic materials 0.000 description 1
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/02—Details
- H01J61/36—Seals between parts of vessels; Seals for leading-in conductors; Leading-in conductors
Landscapes
- Vessels And Coating Films For Discharge Lamps (AREA)
Abstract
A high-pressure discharge lamp has an alumina arc tube (2) mounted within an outer glass jacket, wherein inner diameter of the arc tube 2 is greatest at an intermediate portion and reduces progressively towards the opposite ends of the envelope, and tubular feed-throughs 8, 10, each supporting an electrode 16, 17, are directly sealed at the ends of the arc tube. As shown, the gradual reduction in inner diameter may extend over the whole length of the alumina envelope, Fig. 2, or an intermediate constant diameter region, Fig. 5, may be provided. Preferred relative dimensions are discussed and a number of specific examples given. The lamp may include sodium in the filling and the arrangement allows a short rise time while reducing loss of sodium. <IMAGE>
Description
SPECIFICATION
High-pressure discharge lamp
BACKGROUND OF THE INVENTION
The present invention relates to a high-pressure discharge lamp.
High-pressure sodium lamps and metal halide lamps have been widely used for exterior
illumination. As compared with the high-pressure mercury-vapor lamp which has been almost
exclusively used for exterior illumination and with the metal halide lamp, the lamp efficacy of the high
pressure sodium lamp is about 2 times and 1.5 times, respectively. Therefore, the increasing use of 'high-pressure sodium lamps will be expected because of their energy-saving properties.
In general, the conventional high-pressure sodium lamp has a translucent alumina discharge or arc
tube. The discharge or arc tube is in general straight and has its ends sealed with alumina end caps -which are bonded to the tube with a ceramic cement. A feed-through such as a niobium tube with an
electrode attached to the leading end thereof is extended through the end cap and bonded thereto with
a ceramic cement. The discharge or arc tube is filled with sodium amalgam and a starting rare gas such
as a penning gas consisting of neon and argon and is mounted within an outer glass jacket provided
with a base.
The vapor pressure within the discharge or arc tube is dependent upon the temperature at the
coldest point behind the electrode at the end of the tube. In the case of the prior art high-pressure
discharge lamp, the heat capacity of the end portion of the discharge or arc tube is relatively high so that
the temperature rise at the coldest point becomes slow. As a result, the rise time, one of the lamp
characteristics, becomes longer. In addition, the thermal loss from the end portions of the discharge or
arc tube is so high that the lamp efficacy is lowered.
Furthermore, because of the difference in heat capacity between the end cap and the end portion
of the alumina discharge or arc tube which seals the end cap, the end portions are easily susceptible to
cracking.
Moreover, the conventional high-pressure discharge lamp has the aging problem that sodium is
lost through the gaps between the end caps and the ends of the discharge or arc tube. In order to solve
this problem, there has been proposed to extend the sealed end portions of the discharge or arc tube
that is, the end portions sealed with the end caps. However, the increase in length of the end cap results
in the increase in the heat capacity and consequently the difference in heat capacity between the sealed
end portion of the discharge or arc tube and the end cap is further enhanced so that the end portions of
the tube are more easily susceptible to cracking. As a result, it is impossible to extend the sealed end
portions of the discharge or act tube beyond a certain extent.
SUMMARY OF THE INVENTION
One of the objects of the present invention is, therefore, to provide a high-pressure discharge lamp
which has a short rise time.
Another object of the present invention is to provide a high-pressure discharge lamp which has a
high lamp efficacy.
A further object of the present invention is to provide a high-pressure discharge lamp whose high
initial lamp efficacy show a minimum decrease in its service life.
A yet another object of the present invention is to provide a high-pressure discharge lamp in which
cracking of the sealed end portions of an alumina discharge or arc tube can be substantially eliminated.
A still another object of the present invention is to provide a high-pressure discharge lamp in
which the loss or disappearance of sodium from the discharge or arc tube can be substantially
eliminated.
According to one aspect of the present invention the inner diameter of the discharge or arc tube of
a high-pressure discharge lamp is largest at the center that is, the midpoint between the ends of the
tube and is reduced at the ends. The ends of the discharge or arc tube are directly sealed with feed
throughs each supporting an electrode at the leading or inner end thereof.
The above and other objects, effects and features of the present invention will become more
apparent from the description of preferred embodiments thereof taken in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a front view of a first embodiment of the present invention;
Fig. 2 is a sectional view of a discharge or arc tube thereof;
Fig. 3 shows the rise time characteristic curves of the first embodiment and a conventional high
pressure discharge lamp;
Fig. 4 is a front view of a second embodiment of the present invention;
Fig. 5 is a sectional view of a discharge or arc tube thereof;
Fig. 6 shows the rise time characteristic curve of the second embodiment and a conventional high
pressure discharge lamp for the sake of comparison; and
Fig. 7 shows the life performance curves of the second embodiment and a conventional high pressure discharge lamp for the sake of comparison.
Same reference numerals are used to designate similar parts throughout the figures.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The inventors conducted extensive studies and experiments in the attempt of solving the above
described problems encountered in the prior art high-pressure discharge lamp and found out that when,
instead of the conventional straight alumina discharge or arc tube, a discharge or arc tube is employed whose inner diameter is largest at the center and is reduced at the ends thereof, the above-described objects of the present invention can be attained.
In Fig. 1 is shown a first embodiment of the present invention that is, a high-pressure sodium lamp having a discharge or arc tube 2 mounted within an outer jacket 1 which is made of glass and evacuated as with the conventional discharge lamp. Within the outer jacket 1 the discharge or arc tube 2 is supported by supporting leads 3 and 4, tube supports 5 and 6 and an insulating rod 7. One end of the lower tube support 5 is welded to the supporting lead 3 and the other end thereof supports one or lower end of the insulating rod 7. The other or upper end of the insulating rod 7 is loosely fitted into a feed-through 8 which is electrically connected to the supporting lead 3 through a lead wire 9. One end of the upper tube support 6 is welded to the supporting lead 4 and the other end thereof to a feedthrough 10.
The supporting leads 3 and 4 are extended through a glass stem 11 and are connected to a shell 13 and a base contact 14, respectively.
Referring next to Fig. 2, the construction of the discharge or arc tube 2 will be described in detail.
The discharge or arc tube 2 comprises an alumina tube or envelope 1 5 and the feed-throughs or niobium tubes 8 and 10 which are fitted into the ends of the alumina tube or envelope 15 and airtightly bonded thereto with ceramic cement. The alumina tube or envelope 1 5 has the largest inner diameter at the midpoint between the ends or the center thereof and the inner diameter is gradually reduced toward the ends. Electrodes or tungsten coils 1 6 and 1 7 are supported at the leading ends of the feed-throughs 8 and 10. The discharge or arc tube 2 is filled with sodium amalgam (about 78 mol % of sodium) 18 and xenon or a penning gas consisting of neon and argon.
With a 1 50-W lamp of the type as shown in Fig. 2 and with the wall loading of about 18 W/cm2 (that is, the input divided by the inner surface area of the discharge or arc tube between the electrodes) the variation of the lamp voltage after starting was investigated. The results are shown in Fig. 3.
According to the present invention, the rise time is considerabiy shortened as indicated by the curve A.
The curve B indicates the rise characteristic of a conventional discharge lamp which has the same ratings and in which the end caps are attached to the ends of a straight alumina-ceramic tube. The rapid rise of the lamp voltage means that the luminous flux and other characteristic curves rise rapidly.
The experiments also showed that as compared with the conventional discharge lamp, the lamp efficacy of the discharge lamp of the present invention is increased by about 6% with the same wall loading. More specifically, in the case of the conventional 1 50-W lamp with the wall loading of about 18 W/cm2, its lamp efficacy is 52 Im/W, but the lamp efficacy of the corresponding discharge lamp in accordance with the present invention is increased to about 55 Im/W (at the color temperature of about 2500 K). The increase in lamp efficacy can be attributed to the decrease in loss by thermal conduction between the center to the ends of the discharge or arc tube.
The dimensions and lamp efficacy of the discharge lamps of the present invention are listed below.
dimensions in mm lamp lamp efficacy watts d 8, Cb, I in Im/W 50 17 6.0 4.0 6 37 150 31 10.0 6.5 6 55 250 43 12.0 7.5 6 58 400 58 15.0 9.5 6 61
Remarks: 1. For d, c' e and I, see Fig. 2.
2. The wall loading is about 18 W/cm2.
3. The average color temperature is 2500 K.
The conventional alumina-ceramic discharge or arc tube has the problems that sodium is lost at
the ends of the tube and that the tube itself is damaged, but the present invention can completely avoid
these problems. More specifically, even when the sealed length I (See Fig. 2) of the feed-through 8 is
increased, the heat capacity of the sealed portion will not be increased opposed to the conventional
discharge or arc tube. As a result, the length I can be increased to such an extent (in excess of about
3 mm) that the loss of sodium can be avoided. In addition, the wall thickness of the niobium tube or
feed-through 8 can be decreased so that the difference in coefficient of thermal expansion between
niobium and alumina can be minimized and consequently the alumina discharge or arc tube 1 5 can be
prevented from being damaged at its ends.
With the conventional discharge or arc tube, thermally insulating films such as metal films must be
coated at the ends of the tube in order to attain a higher degree of color rendition, but according to the
present invention a higher degree of color rendition can be attained without the thermal insulating films.
In the experiments, the center diameter 07c and the end diameter (Pe (See Fig. 2) are varied in order
to investigate the luminance distribution. When (pe is extremely smaller than 7c the absorption layers of
vaporized sodium become extremely thin at the ends of the tube so that the color temperature become
more reddish at the ends of the tube than at the center. Therefore, it must be avoided to make (Pe extremely small than vc. The experimental results show that it is preferable that (Pe > = 0.6 fez A second embodiment as shown in Fig. 4 has a discharge or arc lamp 20 as shown in Fig. 5.The
discharge or arc lamp 20 has an alumina envelope 21 whose inner diameter is uniform through the
discharge portion but reduced at the ends. Therefore, as compared with the conventional discharge or
arc tube, the heat capacity of the end portion of the tube which has the coldest point is decreased so that the coldest-point temperature rises rapidly when the lamp is started and consequently the rise time
is shortened as shown in Fig. 6. In Fig. 6 the curve C shows the characteristic of the second
embodiment of the present invention and the curve B, that of the conventional lamp.
The movement of sodium amalgam is observed when the lamp is turned on and after it is turned
off while the heat capacity that is, the volume Q' of the reduced-diameter or sealed-end portion of the discharge or arc tube is varied. In order to vary 0', the length I' and wall thickness t' of the sealed-end
portion (See Fig. 5) are varied. It is found out that if O' is less than two times the volume 0 of the
discharge space with a length of I, amalgam can be always maintained at the coldest. That is, if Q' 2.or, O0 amalgam can be prevented from moving toward the electrode even after the discharge lamp has been turned off. As a result, the phenomenon that it takes a long time before the arc spot is stabilized when the discharge lamp is turned on again can be substantially eliminated.Same is true for the discharge or arc tube as shown in Fig. 2. Thus, as compared with the conventional discharge lamp, the discharge lamp in accordance with the present invention has the advantageous life performance that the rise in lamp voltage due to the aging can be reduced or minimized as shown in Fig. 7.
In Fig. 5, P and t denote the inner diameter and wall thickness, respectively, of the large-diameter portion of the discharge or arc tube and ' denotes the inner diameter of the sealed-end or reduceddiameter portion thereof. Then, Q=7r1(t2+t)and
0' = 7r I'(t'2 + ' t').
The curve D in Fig. 7 shows the life performance of a 400-W lamp in which the distance
between the electrodes is 82 mm; ç = 7.6 mm; t = 0.78 mm; I' = 6 mm; ' = 4.1 mm and t' = 1.2 mm.
Q and Q' are 123.2 mm3 and 119.8 mm3, respectively. The curve E in Fig. 7 shows that of a 400-W lamp of the corresponding conventional type.
It is further found out that if the wall loading is same, the high-pressure sodium lamp of the type
having the discharge or arc tube as shown in Fig. 4 has the lamp efficacy about 4% higher than the
corresponding conventional discharge lamp. For instance, when the wall loading is about 18 W/cm2 and the lamp watts are 1 50 W, the lamp efficacy of the conventional lamp is 52 Im/W while that of the discharge lamp of the present invention is 54 Im/W (at the color temperature of about 2500 K). The increase in lamp efficacy can be attributed to the decrease in loss by thermal conduction from the center portion to the ends of the discharge or arc tube as with the first embodiment.
As described previously in conjunction with the first embodiment, even when the length I' of the sealed end is increased, the heat capacity of the sealed end will not increase. As a result, the length I' can be increased to such an extent that the loss of sodium can be avoided during lamp life. In addition, since the difference in heat capacity or coefficient of thermal expansion between the envelope 21 and the feed-through 8 can be minimized, cracking of the sealed ends can be substantially avoided.
It is apparent that in addition to the high-pressure sodium lamp, the present invention can be equally applied to other discharge lamps such as metal halide lamps. The inventors fabricated a discharge lamp as shown in Fig. 4 except that the discharge tube 20 is filled with the mixture of Nal, Sic13 and Sc and mercury as a buffer gas. in order to prevent the feed-throughs from being attacked by halogen elements or compounds, the inside wall surfaces exposed to the discharge space are coated with metallic molybdenum. The effects are substantially similar to those described above.
Claims (8)
1. A high-pressure discharge lamp of the type in which an envelope of a discharge or arc tube is made of alumina, electrode means each comprising a feed-through with an electrode attached to the leading end thereof are disposed at the ends of said envelope, and said envelope is filled with at least one or more light-emitting materials and one or more starting rare gases, CHARACTERIZED in that the inner diameters of the ends of the said envelope are less than that of the center thereof and are gradually reduced toward the ends thereof; and tubular feed-throughs each with an electrode attached to the leading end thereof are directly sealed at the ends of said envelope.
2. A high-pressure discharge lamp as set forth in Claim 1 further CHARACTERIZED in that said light-emitting material is sodium.
3. A high-pressure discharge lamp as set forth in Claim 1 further CHARACTERIZED in that each of said feed-throughs comprises a niobium tube.
4. A high-pressure discharge lamp as set forth in Claim 1 further CHARACTERIZED in that the inner diameter of said envelope is gradually reduced with distance away from the center thereof; and said light-emitting material is sodium.
5. A high-pressure discharge lamp as set forth in Claim 1 further CHARACTERIZED in that said envelope is such that its inner diameter remains uniform in the portion thereof which defines the discharge space and is reduced toward the ends thereof.
6. A high-pressure discharge lamp as set forth in Claim 4 or 5 further CHARACTERIZED in that the volume of the end portion of said envelope which seals said feed-through is less than two times the volume of the portion of said envelope which defines the discharge space, said two portions being same in length.
7. A high-pressure discharge lamp substantially as hereinbefore described, with reference to
Figures 1 to 3 of the accompanying drawings.
8. A high-pressure discharge lamp substantially as hereinbefore described with reference to
Figures 4 to 7 of the accompanying drawings.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12978280A JPS5753061A (en) | 1980-09-17 | 1980-09-17 | High-pressure vapor discharge lamp |
| JP12978080A JPS5753059A (en) | 1980-09-17 | 1980-09-17 | High pressure sodium vapor lamp |
| JP12978180A JPS5753060A (en) | 1980-09-17 | 1980-09-17 | Halide lamp |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2085650A true GB2085650A (en) | 1982-04-28 |
Family
ID=27315994
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8127644A Withdrawn GB2085650A (en) | 1980-09-17 | 1981-09-11 | High-pressure discharge lamp |
Country Status (2)
| Country | Link |
|---|---|
| DE (1) | DE3137076A1 (en) |
| GB (1) | GB2085650A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0581423A1 (en) * | 1992-06-03 | 1994-02-02 | General Electric Company | Universal burn metal halide lamp |
| EP0841687A3 (en) * | 1996-11-07 | 1998-06-17 | Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH | Ceramic discharge vessel |
| EP1001452A4 (en) * | 1998-05-27 | 2004-10-20 | Ngk Insulators Ltd | Light emitting container for high-pressure discharge lamp and manufacturing method thereof |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4724361A (en) * | 1984-12-14 | 1988-02-09 | Matsushita Electric Works, Ltd. | High pressure discharge lamp |
-
1981
- 1981-09-11 GB GB8127644A patent/GB2085650A/en not_active Withdrawn
- 1981-09-17 DE DE19813137076 patent/DE3137076A1/en not_active Ceased
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0581423A1 (en) * | 1992-06-03 | 1994-02-02 | General Electric Company | Universal burn metal halide lamp |
| EP0841687A3 (en) * | 1996-11-07 | 1998-06-17 | Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH | Ceramic discharge vessel |
| US5936351A (en) * | 1996-11-07 | 1999-08-10 | Osram Sylvania Inc. | Ceramic discharge vessel |
| CN1102798C (en) * | 1996-11-07 | 2003-03-05 | 电灯专利信托有限公司 | Ceramic discharge lamp vessel |
| EP1001452A4 (en) * | 1998-05-27 | 2004-10-20 | Ngk Insulators Ltd | Light emitting container for high-pressure discharge lamp and manufacturing method thereof |
| US7041240B2 (en) | 1998-05-27 | 2006-05-09 | Ngk Insulators, Ltd. | Method of manufacturing a high pressure discharge lamp vessel |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3137076A1 (en) | 1982-04-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |