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Publication numberUS3809944 A
Publication typeGrant
Publication dateMay 7, 1974
Filing dateAug 25, 1972
Priority dateAug 28, 1971
Also published asCA958753A, CA958753A1, DE2238927A1
Publication numberUS 3809944 A, US 3809944A, US-A-3809944, US3809944 A, US3809944A
InventorsJongerius H, Van Der Wolf R
Original AssigneePhilips Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Low-pressure mercury vapour discharge lamp
US 3809944 A
Abstract
An aperture lamp, especially for phototype purposes in which the glass in the aperture is coated with a conducting transparent coating having a resistance of between 5 and 200 kOhms. This coating does not only reduce blackening of the glass in the aperture but also decreases the ignition voltage considerably.
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Description  (OCR text may contain errors)

United States Patent [19 Jongerius et al.

[111 3,809,944 [451 May 7,1974

LOW-PRESSURE MERCURY VAPOUR DISCHARGE LAMP Inventors: Hermanus Maria Jongerius; Rein Willemse Van Der Wolf, both of v Emmasingel, Eindhoven,

Netherlands Assignee: U.S. Phillips Corporation, New York, NY.

Filed: Aug. 25, 1972 Appl. No.: 283,843

Foreign Application Priority Data Aug. 28, 197i Netherlandsw- 7111885 US. Cl. 313/227, 313/225 Int. Cl. HOIj 61/20 Field of Search 313/227, 225

[56] References Cited I UNITED STATES PATENTS 3,067,356 12/1962 Ray 313/227 Primary Examiner -fierman Karl Saalbach Assistant Examiner-Darwin R. Hostetter Attorney, Agent, or Fi rm-Frank R. Trifari 57 ABSTRACT An aperture lamp, especially for phototype purposes in which the glass in the aperture is coated with a conducting transparent coating having a resistance of between 5 and 200 kOhms. This coating does not only reduce blackening of the glass in the aperture but also decreases the ignition voltage considerably.

7 Claims, 4 Drawing Figures LOW-PRESSURE MERCURY VAPOUR DISCHARGE LAMP The invention relates to a low-pressure mercury vapour discharge lamp having a cylindrical glass envelope which includes means for generating a discharge and whose inner side is coated with a layer of luminescent material.

Lamps of the kind described above are known in many embodiments. They are used, inter alia, for general illumination, advertisement purposes and in phototype apparatus. In many cases lamps for phototype apparatus are not coated with the luminescent material over the entire inner circumference of the envelope. A longitudinal aperture in the luminescent coating in lamps of this kind through which a large part of the generated radiation emerges is often provided in order to have a strong directed radiation. The invention relates to the above-described aperture lamps which are particularly used for phototype apparatus.

In order to increase the radiation oflight through the aperture it is ensured in special lamps that the radiation from the luminescent coating is reflected into the direction of the aperture. This object is achieved, for example, by using a relatively thick luminescent coating or by providing a special reflection coating between the envelope and the luminescent coating. In the firstmentioned embodiment part of the thick luminescent coating serves for generating the radiation and part serves for the reflecting thereof. When a separate reflection coatingis used, it generally consists of titanium dioxide.

As described above the aperture is completely free from luminescent material and from reflecting material possibly present. It has been found that the glass in the aperture which is exposed to the direct influence of the discharge blackens after a given number of operating hours. As a result the radiation is of course inhibited. Particularly when the lamps have a high power in order to generate a strong radiation this blackening occurs quickly and to a strong extent. it has been known to obviate this blackening by coating the glass in the aperture with a transparent layer of aluminium oxide, silicon oxide or titanium dioxide.

As is known given auxiliary means are required for igniting low-pressure mercury vapour discharge lamps. These auxiliary means may consist of, for example, the provision of internal or external ignition stips made of widely divergent materials which are provided either on the glass or on the luminescent coating. It is also known to provide a transparent semiconducting layer for lamps without an aperture between the entire luminescent coating and the glass wall. Such a layer consists preferably of tin oxide which is rendered semiconducting by a given treatment, so-called doping. Known doping means. are phosphorus, antimony, fluorine, oxygen and indium.

A further material having semiconducting properties is indium oxide with given doping materials, for example, tin. Such a material is used for a different purpose in sodium vapour discharge lamps but has not yet been proposed for low-pressure mercury vapour discharge lamps.

An object of the invention is to solve at the same time the problem of ignition and the problem ofblackening of the glass in the aperture. This is achieved by coating the glass in the aperture on the inner side with a transparent layer which, measured from end to end, has a resistance of between 5 and 200 kOhm and preferably between 20 and kOhm.

Particularly, conducting tin oxide or conducting in dium oxide is suitable as a material for coating the glass in the aperture.

In order to facilitate ignition even more, the conducting coating may be connected at one end to an emitter electrode.

The conducting coating may be provided in the aperture in different manners. The material of the coating may be sprayed on, it may be provided from a solution or it may be spread out with the aid of a pencil-like pin. This operation may beperformed prior to or after the luminescent coating and the reflection coating possibly present have been provided. It is particularly simple to provide the material when conducting material is not only provided in the aperture but over the entire circumference of the envelope. In fact, the entire envelope may then first be coated on the inner side with the conducting material, whereafter the possible reflection coating and subsequently the luminescent coating may be provided.

It has surprisingly been found that in lamps according to the invention there is no stain formation as is known for lamps without an aperture which are coated over the entire envelope circumference with semiconducting tin oxide.

Alternatively, the reflection coating may first be provided and subsequently the entireinner circumference may be coated with the semiconducting. material, for example, by spraying. The material is then directly located on the glass in the aperture and outside the aperture between the reflection coating and the luminescent coating.

The invention will now be described with reference to a drawing.

In the drawing FIG. 1 is a perspective view of a lamp according to the invention.

FIG. 2 shows an enlarged cross-section through the centre of the lamp. 7

FIGS. 3 and' 4 illustrate other embodiments of the lamp in cross-section.

In the Figures, 1 denotes the glass envelope of the lamp. A reflection coating 2 consisting of fine-grained Ti0 is provided on the inner side of this glass enve-.

lope, which coating supports on its inner side the luminescent coating 3, for example, consisting of willemite. A longitudinal aperture 4 is recessed both inthe reflection coating 2 and in the luminescent coating. The glass in the aperture is coated with a transparent coating of conducting tin oxide 5 obtained by spraying on a. mixture of tin chloride, ethyl alcohol and a slight quantity of hydrofluoric acid. This spraying on was effected at a glass envelope temperature .of approximately 600 C in such a manner that the resistance of the coating in the finished lamp measured from end to end was 30 to 50 kOhm.

For comparison of the ignition properties and the loss of light due to blackening of the aperture, lamps were also made without any coating of the glass in the aperture and lamps with a coating of transparent titanium dioxide on the glass in the aperture.

The table below shows that for lamps according to the invention the decline in the luminous flux due to blackening of the aperture is much smaller than for lamps with uncoated glass and is of the same order as for lamps having a coating of titanium dioxide in the aperture. The ignition voltage for lamps according to the invention is, however, much lower than in the two such a part of the circumference that a longitudinal aperture is free from said luminescent material, the glass 7 in the aperture being coated on the inner side with a transparent coating of a material reducing attack and Comparative lamps both lat room temperature and at 5 blackening of the glass, the transparent coating, mea- Apart from the Coating of the aperture the lamps sured from end to end, having a resistance of between were completely identical. The internal diameter was 5 and 200 o 24 mms and the length between the electrodes was 425 2 A ]Ow preSsu1-e mercury vapour discharge lamp mms. Thewldth of the aperture was 7 mms in all lamps. having a Cylindrical glass envelope which includes The l In the measurlhg arrangement was 400 means for generating a discharge and whose inner side The hght meesuremeht was effected h cehlre of a is coated with a coating of luminescent material over m by il a Step s"? an P h h h Qd 3 such a part of the circumference that a longitudinal aph e apehture an y measurmg t e em erture is free from said luminescent material, a coating lght m arbmary i consisting of titanium dioxide being provided between i TABLE Ignition Ignition vgggae gggae Light output after 11 hours a a in volts in volts 0 100 300 500' 760 Lamp with uneoated aperture 230 280 12.8 12.8 10.6 9.4 8.5 7.2 Lamp with aperture with T102." 230 280 12.9 13.3 12.0 11.7 10.9 10.8 Lamp with aperture with snot." 135 150 11.4 12.5 11.4 11.3 10.6 10.3

If an indium oxide layer'instead ofa transparent conthe glass envelope and the luminescent coating, which ducting tin oxide layer s pro i use i ma f, for titanium dioxide coating reflects the radiation prox mp a p y g Solution which contains indium duced in the luminescent coating satisfactorily, the chloride and a small quantity of tin chloride as a doping glass i h aperture b i t d on th inner id i h mfnerlal in h y e Theleompar'atlve results a transparent coating ofa material reducing attackand tamed therewith do not essentially deviate from the rebl i f h gklss, h transparent Coating, Suits Show" in the aheve'mehtiehed lahlesured from end to end having a resistance of between Although in the drawing a straight lamp having an ap- 5 and 200 o erture is shown the invention may of course also be 3. A lowmressure mercury vapour discharge [amp as used for aperture lamps havmg a bent Shape for exam claimed in claim 2 wherein the transparent coating, glgg elg -l d measured from end to end, has a resistance of between 1 ustrates a ow pressure mercury vapour 18- 20 and 100 kohms charge lamp wherein the transparent coating extends 4. A low pressm.e mercury vapour discharge lamp as, gzl gs t ge gl zl sz g't z'i l g ligz fagir g z gliifg zgg zg; claimed in claim 2 wherein the transparent coating in the aperture consists of conducting tin oxide. coating, layer 2 1s lagain the reflective layer and layer 5. A low pressure mercury vapour discharge lamp as 3 i g l f ayer' h claimed in claim 2 wherein the transparent coating in l n i l g T ZZ FZZZ A g 40 theaperture consists of conducting indium oxide. IS 8 w 5 e f of the eff/e10 e 6. A low-pressure mercury vapour discharge lamp as ten S 8 en l erenc p claimed in claim 1, wherein the transparent coating exthe portion present outside the aperture being located tends over the entire circumference of the envelope between the reflection coating and the luminescent and en a es the lass at all areas coating. Layer 2 represents the reflective coating and g g g 7. A low-pressure mercury vapour discharge lamp as layer 3 the luminescent coating.

What is Claimed claimed in claim 2, wherein the transparent coating exl. A low-pressure mercury vapour discharge lamp tinds f the enme g gl of l ep di having a cylindrical glass envelope which includes a i T g g e f e zg T ocdtet means for generating a discharge and whose inner side 5 e C re CC coa mg e ummescen is coated with a coating of luminescent material over C03

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3067356 *Apr 6, 1960Dec 4, 1962Sylvania Electric ProdFluorescent lamp
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3963954 *Nov 25, 1974Jun 15, 1976Gte Sylvania IncorporatedFluorescent lamp having indium oxide conductive coating and a protective coating therefor
US3967153 *Nov 25, 1974Jun 29, 1976Gte Sylvania IncorporatedFluorescent lamp having electrically conductive coating and a protective coating therefor
US4064291 *Oct 26, 1976Dec 20, 1977U.S. Philips CorporationSpray-coating method of window forming in tubular lamp
US4070570 *Jun 29, 1976Jan 24, 1978General Energy Development CorporationLighting apparatus
US4265950 *Nov 27, 1979May 5, 1981Westinghouse Electric Corp.Phosphor-coating composition and method for electric discharge lamp
US4661890 *Mar 28, 1986Apr 28, 1987Kabushiki Kaisha ToshibaLamp unit
US5801482 *Aug 17, 1995Sep 1, 1998U.S. Phillips CorporationLow-pressure mercury vapor discharge lamp
US6932664 *Feb 19, 2002Aug 23, 2005Fujitsu LimitedGas discharge tube and method for forming electron emission layer in gas discharge tube
US7208203 *Aug 18, 2003Apr 24, 2007Fujitsu LimitedMethod for forming metal oxide film and method for forming secondary electron emission film in gas discharge tube
US7378797Dec 16, 2005May 27, 2008General Electric CompanyFluorescent lamp with conductive coating
US20030025451 *Feb 19, 2002Feb 6, 2003Fujitsu LimitedGas discharge tube and method for forming electron emission layer in gas discharge tube
US20040033319 *Aug 18, 2003Feb 19, 2004Fujitsu LimitedMethod for forming metal oxide film and method for forming secondary electron emission film in gas discharge tube
US20070138960 *Dec 16, 2005Jun 21, 2007General Electric CompanyFluorescent lamp with conductive coating
CN100419945CApr 8, 2003Sep 17, 2008通用电气公司Fluorescent lamp
DE2644821A1 *Oct 5, 1976Apr 14, 1977Gte Sylvania IncLeuchtstofflampe mit reflektorschicht
WO2002037533A2 *Oct 24, 2001May 10, 2002General Electric CompanyNovel materials and methods for application of conducting members on arc tubes
WO2002037533A3 *Oct 24, 2001Dec 31, 2003Gen ElectricNovel materials and methods for application of conducting members on arc tubes
Classifications
U.S. Classification313/485, 313/488
International ClassificationH01J61/24, H01J61/54, H01J61/26, H01J61/35
Cooperative ClassificationH01J61/35, H01J61/545, H01J61/26
European ClassificationH01J61/26, H01J61/35, H01J61/54B