GB1571194A - Internal protective coating for incandescent lamps - Google Patents
Internal protective coating for incandescent lamps Download PDFInfo
- Publication number
- GB1571194A GB1571194A GB104576A GB104576A GB1571194A GB 1571194 A GB1571194 A GB 1571194A GB 104576 A GB104576 A GB 104576A GB 104576 A GB104576 A GB 104576A GB 1571194 A GB1571194 A GB 1571194A
- Authority
- GB
- United Kingdom
- Prior art keywords
- lamp
- coating
- methanol
- halogen
- envelope
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01K—ELECTRIC INCANDESCENT LAMPS
- H01K1/00—Details
- H01K1/28—Envelopes; Vessels
- H01K1/32—Envelopes; Vessels provided with coatings on the walls; Vessels or coatings thereon characterised by the material thereof
Description
(54) INTERNAL PROTECTIVE COATING FOR INCANDESCENT
LAMPS
(71) We, THORN LIGHTING LIMI
TED, of Thorn House, Upper Saint Martin's
Lane, London, WC2H 9ED and IMPERIAL
CHEMICAL INDUSTRIES LIMITED, of
Imperial Chemical House, Millbank, London SWlP 3JF, both British Campaniles, do hereby declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to electric incandescent lamps, and more especially to incandescent lamps operating by a halogen cycle.
In any incandescent tungsten filament lamp containing a reactive fill such as halogen or halide, the choice of material for the internal components and envelope is usually very restricted. For lamps having iodine, bromine or chlorine in the fill the envelope is preferably fused quartz or a high silica content glass and the lead-in wire, filament supports, internal reflectors, shields and other internal components are substantially composed of molybdenum or tungsten. If less expensive, common materials such as nickel, iron, copper, aluminium and alloys containing these are used they react with the halogens to form halides which can cause filament embrittlement, and/ or a halogen deficiency, both resulting in severely reduced filament life.Also, if soft glass, such as soda lime silicate, is used for the envelope, apart from the obvious difficult ties of the low softening temperature and high water content, the alkali metals can react with the halogen or halides, again reducing filament life.
In operation, tungsten-halogen lamps normally contain a non-reactive gas filling such as N2, Ar, Kr or Xe together with iodine, bromine or chlorine vapour which combines with the evaporated tungsten escaping from the incandescent filament. An equilibrium concentration is attained by the gaseous species within the lamp between the tem- perature limits defined by the incandescent filament and coldest spot one lamp envelope. The cold spot temperature must be sufficiently high to prevent any tungsten halide from condensing, and provided that this condition is met a continuous tungsten transport cycle operates which keeps the envelope free from tungsten. The minimum envelope temperature depends upon the halogen or halogens taking part in the cycle.However, the maximum envelope temperature is usually well above the acceptable limit for soft glass, and for this reason tungsten-halogen lamp envelopes are usually made from vitreous fused silica or high silica content glasses.
The return of tungsten to the filament does not in itself increase filament life since tungsten iodides, bromides and chlorides dissociate well below normal filament operating temperatures. Radiochernical tracers have shown that evaporated tungsten is redistributed during the life of the lamp so that the cooler parts of the filament collect tungsten at a greater rate than the hotter parts. Filament failure usually occurs quite normally by the subsequent burn-out of a 'hot spot'. The improvement in life of tungsten-halogen lamps in comparison with conventional incandescent lamps is for quite a different reason. The absence of envelope blackening coupled with the requirement for a welldefined minimum envelope temperature dictates that the enevlope must be substantially smaller than that of a conventional counterpart.In fact, tungsten-halogen lamp envelopes are usually small and mechanically strong and in consequence can be safely gas-filled to several atmospheres pressure. This increased gas filling pressure accounts for the gain in life.
If filament 'hot spots' could be healed or prevented a further extension in filament life would be possible. This is feasible with a tungsten-fluorine transport cycle because in this case the most stable tungsten fluoride dissociates at a temperature above 30000C, and tungsten is returned to the incandescent filament surface. Again, this has been substantiated by radiochesucal tracer experiments, which show that tungsten vapour returned from the region of the envelope is evenly distributed along the incandescent part of the filament.Technological difficulties have prevented the further development of tungstenfluorine lamps, the principal problem being that free fluorine reacts rapidly with solid tungsten below about 2000"C, the cold parts of the filament,the lead wires and the supports being rapidly eroded, and that the fluorides formed (e.g. tungsten fluorides) react with the silica contained in the envelope material to form SiF depositing tungsten on the tube wall. This uses up the free fluorine in a very short time. Various methods have been proposed for protecting the envelope and tungsten components but these have been unsuccessful because of the inability to produce a continuous thin layer of protective material free from pin-holes and minor defects.
In our Patents Nos. 1,456,242 and
1,463,056 we describe the use of glassy coatings of metal phosphates or arsenates as protective coatings for the internal surfaces of halogen-containing electric lamps, and describe a process for the formation of defect-free coatirigs by deposition of a solution of compounds of the metal and phosphorus or arsenic, followed by evaporation of the solvent and baking of the resulting layer.
United States Patent No. 3,067,356 describes a fluorescent lamp having an internal barrier layer of, inter alia, aluminium oxide intended to reduce darkening of the lamp by
reaction of mercury in the gas fill with alkali in the glass of the lamp tube. Not only is the use of this coating different from that required for this invention, but the layer in the Patent referred to is formed by applying the particulate oxide in a lacquer vehicle, followed by drying and baking, and such a layer does not provide effective protection against a highly
reactive gas such as fluorine.
The present invention now provides an
alternative or improved protective layer for the exposed internal surfaces of incandescent lamps which tend to react with the fill in the
lamp envelope, particularly where this in
cludes a halogen, and more especially fluorine
or a fluorine-containing compound.
In accordance with this invention the internal surface of the envelope of a halogen
cycle incandescent lamp, and preferably also
the exposed surfaces of internal components
(which tend to react with the fill in the
envelope during operation of the lamp), are
coated with a continuous imperforate layer
substantially consisting of a metal oxide
resistant to halogen attack and derived from - a compound of the said metal deposited on such surfaces from solution.
Further in accordance with this invention
there is provided a method of making a halo
gen cycle incandescent lamp which comprises
coating at least those portions of the internal
surface of the envelope and the exposed sur
faces of internal components which tend to
react with halogen during operation of the
lamp with a solution of a metal compound
capable of generating on being heated a
halogen-resistant oxide of the metal, and
heating the resulting coating to form on the
surface a continous imperforate coating of the
said oxide.
The preferred metal oxide for the formation
of the coating is aluminium oxide, but other
halogen-resistant oxides, more especially of
polyvalent or transition metals such as cerium,
thorium and yttrium, and others of the lan
thanide series, may be used. Aluminium~ oxide
has an especial advantage in that coatings
formed thereby are both colourless and trans
parent. The coatings are preferably formed
from solutions of halides of the metals in
polar organic solvents such as methanol.
Preferred solvents for the preparation of
the coating solution are oxygencontaining
organic solvents such as alcohols, esters,
ketones, aldehydes, nitro-compounds and
ethers, or mixtures thereof. Particularly pre
ferred are aliphatic alcohols, especially lower
molecular weight alcohols containing 1 to 4
carbon atoms, for example methanol, ethanol,
n- or isopropanol or substituted alcohols such
as methoxy- or ethoxy-ethanol. A wide variety
of compounds of the metals can be used, pro
vided they are soluble in the chosen solvent
and generate on being heated the desired
oxide without substantial contamination by
other elements. Simple inorganic salts of the
metals are preferred, especially the halides,
but organic salts such as acetates may also be
used. The salt may form in solution a com
plex with molecules of the solvent.
The coated surfaces in the lamps of this
invention may include the internal surface of
the envelope, the filament tails or lead-in
wires or the filament supports, depending on
the nature of the fill gas employed and on the
materials from which the envelope and the
internal components are fabricated. Part or
all of the filament or filaments may be
initially provided with a coating, for example
where the coating technique according to the
invention cannot conveniently avoid this, but
the coating on the filament will be removed
when the filament is heated to incandescence.
The protective coatings provided in accor
dance with this invention may be applied to
conventional materials used for the fabrication
of lamp components, for example to protect
them from highly reactive fill substances, or
they may enable cheaper and more readily available materials to be substituted for con ventionally used materials without unacceptable loss in performance or life.
The oxide coating must be continuous and free from pin-holes or other defect or imperfection which might cause it to break down during operation of the lamp. Suitable coatings are glass-like in appearance but may have a micro-crystalline structure. They preferably have a thickness in the range 0.001 1 micron. Alternatively, the coating weight may be 0.2 - 1000 microgram per cm2.
In one preferred method of making lamps according to this invention, the desired portions of the internal surface of the envelope and the surfaces of internal components which are exposed in the finished lamp are coated either separately or after assembly with an organic solvent solution of an aluminium compound or complex capable of generating aluminium oxide, and subsequently heated to evaporate the solvent and cure the composition to form a defect-free aluminium oxide coating. It has been found valuable in the production of defect-free coatings to allow the applied liquid coating composition to drain thoroughly and thereafter to bake initially at a relatively low temperature to remove the solvent and subsequently at a controlled higher temperature to complete the formation of the protective coating.The preferred baking temperatures vary with the particular composition employed to generate the aluminium oxide, but can be determined by experiment.
One example of this technique will now be described with reference to the drawing accompanying the Provisional Specification which shows diagrammatically a tungsten 'halogen lamp assembly in the course of manufacture.
As shown in the drawing, a 12V. 55W.
tungsten-halogen lamp, of the type commonly used in projector and motor vehicle lighting applications, comprises a fused quartz envelope 1 in which is sealed a tungsten filament 2 supported on filament tails or lead-in wires 3 and is provided with an exhaust tube 4.
The lamp is to be provided with an aluminium oxide barrier layer covering the inside surface of the envelope 1, the filament 2 and filament tails 3.
A liquid coating composition capable of generating the aluminium oxide is dispensed from a hypodermic syringe through the lamp exhaust tube 4 by inserting the needle of the syringe, discharging the liquid composition and then almost immediately drawing it back into the syringe, leaving only a thin layer adhering to the inside surfaces of the lamp suucture. At this stage the lamp is inverted to drain, and then heated in a vacuum or suitably inert atmosphere, for example at approximately 100"C for an hour in the case of a methanolic composition. The aluminium oxide coating is finally formed by baking at a higher temperature, for example at 500 C in a vacuum or suitably inert atmosphere for about 5 minutes. The final bake can be effectively incorporated in subsequent lamp processing.
The initial heating cycle is chosen to substantially remove the solvent and the time, temperature and atmosphere will depend upon the solvent selected. The temperature of the
subsequent bake depends on the particular
formulation used, but will in general be below 1000 C.
The lamp is then processed in the normal manner for tungsten-halogen lamps. When the filament is first energised the aluminium oxide layer on the incandescent filament surface and part of the filament tail adjacent to the filament is removed, leaving a protective barrier on the envelope surface and cold parts of the filament tails or lead-in wires.
In accordance with one aspect of this invention it has been found that when such lamps are provided with a fluorine-containing fill they can be operated with less or even substantially no attack on the filament tails, the filament or the envelope surface by fluorine or fluorides. The fluorine can be added as the element, or more conveniently as WF6 within the pressure range of 1 to 10 Torr, or as NF, or SIF6 or a solid such as NF4SbF6, NFAsFF, XeF,SbiF,, XeF4^AsFa, TcFi,SbFs or SeF4SbFs. Solids may also be added in solution in suitable solvents as disclosed in the specification of our Patent No. 1,236,174.
An alternative source of fluorine is described in our copending Application No.
1046/76 (Serial No. 1,571,195), namely a soluble fluoro-carbon polymer, which can be metered into the lamp envelope in solution in, for example, a fluorinated organic solvent.
In accordance with another aspect of this invention, cheaper or more easily obtainable or workable materials are used for the envelope or internal components of halogen cycle lamps by providing on the exposed surfaces of such parts of the structure a coating of aluminium oxide as described above.
In certain established tungsten-halogen lamps (e.g. twin filament car lamps) a molybdenum frame or wires is or are used both as lead-in conductors and as a member to carry a molybdenum (or tungsten) shield.
There is some evidence to suggest that there is a limited chemical reaction between these components and the fill, and in such a case it is advantageous to coat them with a halogenor halide- resistant layer of the aluminium oxide. However, as an alternative, the refractory metal in these components can be replaced by a less expensive and easier to work metal, such as iron or nickel, coated with the aforementioned layer.
A further possibility is to use a glass envelope coated with a halogen- or halide-resis
tant layer of aluminium oxide in place of the fused quartz conventionally employed for such envelopes. This may involve a direct replacement of fused quartz by a hard glass, such as borosilicate or aluminosilicate, or the use of inexpensive soda-lime silicate soft glass. In the latter case the envelope dimensions should be carefully chosen so that the hottest part is below the glass strain temperature and the coldest part is above the well-established minimum for the particular tungsten-halogen cycle to function. This also would reduce material and manufacturing costs. It should be noted that aluminosilicate glass is used for the envelope material of certain tungstenhalogen lamps but cannot be considered as a replacement for fused quartz.It will thus be apparent that individual components or all the internal surfaces within the lamp may be coated.
The following are specific examples of the practical application of the present invention and the production of tungsten-halogen lamps.
Example 1
A liquid aluminium oxide coating composition was prepared by dissolving anhydrous aluminium chloride (3.95 g.) in methanol (396.05 g.). A tungsten filament lamp assembly was coated internally with this composition by the technique described above and the coated assembly thoroughly drained, heated at 100"C in vacuo for one hour, and baked at 500"C for 5 minutes also in vacua. The lamp was subsequently filled with 3i atm.
argon and 4 Torr WF,; and finished in the usual way.
The lamp was rated at 12V. 100W. in operation and was successfully run at a filament temperature of 32000 C for more than 25 hours without breakdown of the coating. In contrast, similar lamps without the coating of this invention showed extremely rapid loss of fluorine due to reaction with the lamp components and had a useful life of only a few minutes.
Example 2
Lamps were made as described in Example 1 except that 4 Torr of SF6 was used instead of the WF,;. The lamp was equally successful.
Example 3
Lamps were made as described in Example 1, except that the coating composition consisted of 3.5 g. cerium chloride (CeCl,) dissolved in 96.5 g. methanol, any precipitate separating out being filtered off before use.
The lamps were baked at 6000C for 5 minutes in uacuo and showed similar performance.
Examples 4 to 10
The following are further examples of coating compositions employing different metals, which may be used for the purposes of this invention:
Example 4: 6.2 g. Ce(NO,)s.6H2O dissolved
in 93.8 g. methanol (and filtered).
Example 5: 4.4 g. SnCl4, anhydrous, dis
solved in 95.6 g. methanol.
Example 6: 5.9 g. SnCl.5H20 dissolved
in 94.1 g. methanol.
Example 7: 7.0 g. ZrOCI2.8H2O dissolved
in 93.0 g. methanol.
Example 8: 3.9 g. Sn(NO,)3 hydrate, dis
solved in 96.1 g. methanol.
Example 9: 4.4 g. YC1, hydrate, dissolved
in 95.6 g. methanol.
Example 10: 3.2 g. ThCl4 hydrate, dissolved
in 96.8 g. methanol.
The saks used were of technical grade.
In the case of Example 4 some precipitate formed on standing and this was filtered off.
In the other Examples no filtration was necessary.
WHAT WE CLAIM IS:
1. A halogen cycle incandescent lamp having a protective coating preventing reaction between the internal surface of the lamp envelope and a gas fill containing halogen therein, wherein the coating is a continuous imperforate layer substantially consisting of a metal oxide resistant to halogen attack and derived from a compound of the said metal deposited on such surface from solution.
2. A lamp according to claim 1, in which the said coating substantially consists of aluminium oxide.
3. A lamp according to claim 1 or 2, in which the coating has a thickness in the range 0.001 to 1 micron.
4. A lamp according to claim 1 or 2, in which the coating has a weight of 0.2 to 1000 migrograms per cm2.
5. A lamp according to any of claims 1 to 4, in which the metal oxide coating extends to the exposed surfaces of internal components of the lamp.
6. A method of making a halogen cycle incandescent lamp which comprises coating at least those portions of the intemal surface of the envelope and the exposed surfaces of internal components which tend to react with halogen during operation of the lamp with a solution of a metal compound capable of generating on being heated a halogen-resistant oxide of the metal, and heating the resulting coating to form on the surface a continuous imperforate coating of the said oxide.
7. A method according to claim 6, in which the surface is coated with a solution of a halide of the said metal in a polar organic solvent.
8. A method according to claim 6 or 7, in which the surface is coated with a solution of a compound or complex of aluminium.
9. A method according to claim 6, 7 or 8, in which the metal compound is dissolved in
methanol.
10. A method according to any of claims 6
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (13)
1. A halogen cycle incandescent lamp having a protective coating preventing reaction between the internal surface of the lamp envelope and a gas fill containing halogen therein, wherein the coating is a continuous imperforate layer substantially consisting of a metal oxide resistant to halogen attack and derived from a compound of the said metal deposited on such surface from solution.
2. A lamp according to claim 1, in which the said coating substantially consists of aluminium oxide.
3. A lamp according to claim 1 or 2, in which the coating has a thickness in the range 0.001 to 1 micron.
4. A lamp according to claim 1 or 2, in which the coating has a weight of 0.2 to 1000 migrograms per cm2.
5. A lamp according to any of claims 1 to 4, in which the metal oxide coating extends to the exposed surfaces of internal components of the lamp.
6. A method of making a halogen cycle incandescent lamp which comprises coating at least those portions of the intemal surface of the envelope and the exposed surfaces of internal components which tend to react with halogen during operation of the lamp with a solution of a metal compound capable of generating on being heated a halogen-resistant oxide of the metal, and heating the resulting coating to form on the surface a continuous imperforate coating of the said oxide.
7. A method according to claim 6, in which the surface is coated with a solution of a halide of the said metal in a polar organic solvent.
8. A method according to claim 6 or 7, in which the surface is coated with a solution of a compound or complex of aluminium.
9. A method according to claim 6, 7 or 8, in which the metal compound is dissolved in
methanol.
10. A method according to any of claims 6
to 9, in which the solution is applied in a thickness corresponding to a coating weight of 0.2 to 1000 micrograms per cm2.
11. A method according to any of claims 6 to 10, in which the coated surface is heated to evaporate the solvent and is subsequently baked at a controlled higher temperature to complete the formation of the oxide coating.
12. A halogen cycle lamp having a protective coating of metal oxide on the internal surface of the lamp envelope substantially as described with reference to any one of the
Examples herein.
13. A method of forming a protective metal oxide coating on the internal surface of a lamp envelope substantially as described in any one of the Examples herein.
Priority Applications (13)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB104576A GB1571194A (en) | 1976-01-12 | 1976-01-12 | Internal protective coating for incandescent lamps |
NL7700150A NL185881C (en) | 1976-01-12 | 1977-01-07 | METHOD FOR MAKING A BULB WITH HALOGENIC GAS FILLING |
CA269,431A CA1097991A (en) | 1976-01-12 | 1977-01-11 | Metal oxide coating in halogen incandescent lamps |
IT1916677A IT1075605B (en) | 1976-01-12 | 1977-01-11 | ELECTRIC INCANDESCENT BULB OPERATING BY A HALOGEN CYCLE |
FR7700792A FR2337939A1 (en) | 1976-01-12 | 1977-01-12 | INCANDESCENT LAMP CONTAINING AN INTERNAL COATING FOR PROTECTION AGAINST HALOGENS, AND METHOD OF MANUFACTURING |
SE7700252A SE437743B (en) | 1976-01-12 | 1977-01-12 | GLAMP LAMP AND PROCEDURE FOR THE PREPARATION OF A SUGAR |
AU21269/77A AU507484B2 (en) | 1976-01-12 | 1977-01-12 | Incandescent lamp |
IE5277A IE44478B1 (en) | 1976-01-12 | 1977-01-12 | Internal protective coating for incandescent lamps |
LU76555A LU76555A1 (en) | 1976-01-12 | 1977-01-12 | |
DE19772701051 DE2701051A1 (en) | 1976-01-12 | 1977-01-12 | LIGHT BULB AND METHOD FOR PROTECTING YOUR INTERIOR SURFACES |
DK11577A DK11577A (en) | 1976-01-12 | 1977-01-12 | ELECTRIC LAMP AND PROCEDURE FOR PROTECTING INTERIOR SURFACES THEREOF |
JP281177A JPS52101881A (en) | 1976-01-12 | 1977-01-12 | Incandescent lamp and method of manufacture thereof |
BE174002A BE850296A (en) | 1976-01-12 | 1977-01-12 | INCANDESCENT ELECTRIC LAMPS |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB104576A GB1571194A (en) | 1976-01-12 | 1976-01-12 | Internal protective coating for incandescent lamps |
Publications (1)
Publication Number | Publication Date |
---|---|
GB1571194A true GB1571194A (en) | 1980-07-09 |
Family
ID=9715212
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB104576A Expired GB1571194A (en) | 1976-01-12 | 1976-01-12 | Internal protective coating for incandescent lamps |
Country Status (13)
Country | Link |
---|---|
JP (1) | JPS52101881A (en) |
AU (1) | AU507484B2 (en) |
BE (1) | BE850296A (en) |
CA (1) | CA1097991A (en) |
DE (1) | DE2701051A1 (en) |
DK (1) | DK11577A (en) |
FR (1) | FR2337939A1 (en) |
GB (1) | GB1571194A (en) |
IE (1) | IE44478B1 (en) |
IT (1) | IT1075605B (en) |
LU (1) | LU76555A1 (en) |
NL (1) | NL185881C (en) |
SE (1) | SE437743B (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2128805A (en) * | 1982-09-28 | 1984-05-02 | Tokyo Shibaura Electric Co | Incandescent lamp |
GB2169619A (en) * | 1984-11-15 | 1986-07-16 | Atomic Energy Authority Uk | Light scattering coatings |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DD143980A1 (en) * | 1979-07-13 | 1980-09-17 | Hasso Meinert | LIGHT BULB WITH A FLUOR CIRCULAR PROCESS |
DE3139294A1 (en) * | 1981-10-02 | 1983-04-21 | Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH, 8000 München | HALOGEN BULB AND METHOD FOR PROTECTING YOUR INTERIOR SURFACE |
DE102008061776A1 (en) | 2008-12-11 | 2010-06-17 | Osram Gesellschaft mit beschränkter Haftung | halogen bulb |
DE102010042557A1 (en) | 2009-10-21 | 2011-04-28 | Osram Gesellschaft mit beschränkter Haftung | halogen bulb |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
AT175628B (en) * | 1950-07-12 | 1953-07-25 | Egyesuelt Izzolampa | Incandescent lamp and process for making same |
FR1139217A (en) * | 1954-02-26 | 1957-06-26 | Philips Nv | Incandescent lamp |
FR1375567A (en) * | 1963-11-27 | 1964-10-16 | Philips Nv | Gas-filled incandescent lamp |
HU162781B (en) * | 1971-12-22 | 1973-04-28 |
-
1976
- 1976-01-12 GB GB104576A patent/GB1571194A/en not_active Expired
-
1977
- 1977-01-07 NL NL7700150A patent/NL185881C/en not_active IP Right Cessation
- 1977-01-11 IT IT1916677A patent/IT1075605B/en active
- 1977-01-11 CA CA269,431A patent/CA1097991A/en not_active Expired
- 1977-01-12 IE IE5277A patent/IE44478B1/en unknown
- 1977-01-12 BE BE174002A patent/BE850296A/en not_active IP Right Cessation
- 1977-01-12 SE SE7700252A patent/SE437743B/en not_active IP Right Cessation
- 1977-01-12 DE DE19772701051 patent/DE2701051A1/en active Granted
- 1977-01-12 FR FR7700792A patent/FR2337939A1/en active Granted
- 1977-01-12 LU LU76555A patent/LU76555A1/xx unknown
- 1977-01-12 DK DK11577A patent/DK11577A/en not_active Application Discontinuation
- 1977-01-12 AU AU21269/77A patent/AU507484B2/en not_active Expired
- 1977-01-12 JP JP281177A patent/JPS52101881A/en active Pending
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2128805A (en) * | 1982-09-28 | 1984-05-02 | Tokyo Shibaura Electric Co | Incandescent lamp |
US4524410A (en) * | 1982-09-28 | 1985-06-18 | Tokyo Shibaura Denki Kabushiki Kaisha | Incandescent lamp with film of alternately stacked layers |
GB2169619A (en) * | 1984-11-15 | 1986-07-16 | Atomic Energy Authority Uk | Light scattering coatings |
Also Published As
Publication number | Publication date |
---|---|
IT1075605B (en) | 1985-04-22 |
SE437743B (en) | 1985-03-11 |
IE44478B1 (en) | 1981-12-16 |
DE2701051C2 (en) | 1988-08-11 |
DE2701051A1 (en) | 1977-07-21 |
JPS52101881A (en) | 1977-08-26 |
FR2337939B1 (en) | 1980-09-05 |
FR2337939A1 (en) | 1977-08-05 |
AU2126977A (en) | 1978-07-20 |
DK11577A (en) | 1977-07-13 |
IE44478L (en) | 1977-07-12 |
CA1097991A (en) | 1981-03-24 |
AU507484B2 (en) | 1980-02-14 |
NL7700150A (en) | 1977-07-14 |
SE7700252L (en) | 1977-07-13 |
NL185881C (en) | 1990-08-01 |
BE850296A (en) | 1977-07-12 |
NL185881B (en) | 1990-03-01 |
LU76555A1 (en) | 1977-06-17 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US4256988A (en) | Incandescent halogen lamp with protective envelope coating | |
US4047067A (en) | Sodium halide discharge lamp with an alumina silicate barrier zone in fused silica envelope | |
US3842304A (en) | High-pressure gas discharge lamp | |
US4983001A (en) | Optical interference film having high and low refractive index layers inter-layer connection of which is strengthened | |
US3521110A (en) | Mercury-metallic halide vapor lamp with regenerative cycle | |
US3900754A (en) | Electric discharge lamp | |
KR0130879B1 (en) | Protective metal silicate coating for a metal halide arc | |
US20030042856A1 (en) | High pressure discharge lamp and method for producing the same | |
US5473226A (en) | Incandescent lamp having hardglass envelope with internal barrier layer | |
GB1571194A (en) | Internal protective coating for incandescent lamps | |
US3984590A (en) | Electric discharge lamp | |
JPS6298556A (en) | Electric lamp | |
JPH11509514A (en) | Glass compositions suitable for use in fluorescent lamps, lamp vessels made from glass of said compositions, and fluorescent lamps comprising glass lamp vessels of said composition | |
US3902091A (en) | Incandescent lamp | |
US3538373A (en) | Electric incandescent lamp containing a reactive carrier gas which comprises hydrogen and bromine and/or chlorine and hydrogen | |
US3982046A (en) | Incandescent lamps | |
US4024425A (en) | Metal halide lamps | |
US3263113A (en) | Tungsten filament lamp comprising hexafluoride gas at partial pressure not exceeding 10 torrs | |
US3821585A (en) | Tungsten halogen incandescent lamp with group iva metal getter and method of manufacture | |
US3412277A (en) | Incandescent lamp with addition of fluorine compounds to the operating gas filling | |
US3219868A (en) | Articles of fused silica | |
US4225635A (en) | Method for applying reacted boron oxide layer to vitreous silica substrate | |
US4508991A (en) | Halogen cycle incandescent lamp and method for the protection of its inner surface | |
US5098326A (en) | Method for applying a protective coating to a high-intensity metal halide discharge lamp | |
US3006783A (en) | Method of applying light-diffusing layers to glass surfaces and glass objects |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PS | Patent sealed | ||
PCNP | Patent ceased through non-payment of renewal fee |