CA1040412A - Low pressure mercury vapour discharge lamp - Google Patents
Low pressure mercury vapour discharge lampInfo
- Publication number
- CA1040412A CA1040412A CA217,099A CA217099A CA1040412A CA 1040412 A CA1040412 A CA 1040412A CA 217099 A CA217099 A CA 217099A CA 1040412 A CA1040412 A CA 1040412A
- Authority
- CA
- Canada
- Prior art keywords
- activated
- coating
- low pressure
- pressure mercury
- discharge lamp
- 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
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70008—Production of exposure light, i.e. light sources
- G03F7/70016—Production of exposure light, i.e. light sources by discharge lamps
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
- C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
- C09K11/66—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing germanium, tin or lead
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
- C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
- C09K11/74—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing arsenic, antimony or bismuth
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
- C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
- C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
- C09K11/7783—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing two or more rare earth metals one of which being europium
- C09K11/7784—Chalcogenides
- C09K11/7787—Oxides
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/02—Details
- H01J61/38—Devices for influencing the colour or wavelength of the light
- H01J61/42—Devices for influencing the colour or wavelength of the light by transforming the wavelength of the light by luminescence
- H01J61/44—Devices characterised by the luminescent material
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Plasma & Fusion (AREA)
- General Physics & Mathematics (AREA)
- Vessels And Coating Films For Discharge Lamps (AREA)
- Luminescent Compositions (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
A low pressure mercury vapour discharge lamp particularly intended for illuminating photolithographic rooms. In addition to a high l??inous flux the lamp has a satisfactory colour rendition. The lamp is provided with an absorption coating for ultraviolet and blue radiation and furthermore with a luminescent coating comprising at least three luminescent materials.
A low pressure mercury vapour discharge lamp particularly intended for illuminating photolithographic rooms. In addition to a high l??inous flux the lamp has a satisfactory colour rendition. The lamp is provided with an absorption coating for ultraviolet and blue radiation and furthermore with a luminescent coating comprising at least three luminescent materials.
Description
``" 104~)41Z
"Low pressure mercury vapour discharge lamp".
The invention relates to a low pressure mercury vapour discharge lamp having a satisfactory colour ren-dition~ provided with a glass envelope whose inner side is coated with two superposed coatings, the first coating provided directly on the glass envelope comprising an ultraviolet and blue radiation absorbing material and ab-sorbing the 436 nm mercury line for at least 70% and mainly passing visible radiation at wavelengths of more than 480 nm, the second coating being a luminescent coating provided on the first coating on the discharge side. Par-ticularly the invention relates to such a lamp intended for illuminsting photolithbgraphy rooms.
In , for example~ samiconductor technology so-called photolithographic processes are used on a large ` scale. In these processes a certain pattern is provided on a substrate by coating the substrate with a photo-resist whereafter the substrate thus coated is exposed through a mask with radiation to which the said resist is sensitive. The resist then hardens at the areas which are exposed. Subsequently the unexposed resist can be removed and the desired pattern can be provided on the substrate, for example, by etching.
Most photoresists used in the technique harden under the influence of eledtromagnetic radiation having certain wavelengths. The extent of hardening of the photo-j~' ", .
;
. ,~ ., -2_ ' ::
104~41Z
,, resist as a function of the wavelength of the incident radiation is indicated by a sensitivity curve. The maximum of this sensitivity curve is in the blue or near ultra-violet part of the spectrum for most photoresists. It is evident that in the illumination of the rooms where the said photolithographic processes are carried out light sources are to be used which do not comprise radiation or comprise as little as possible radiation to which;the photoresist is sensitive. So ar lamps emitting yellow light have been used insuch rooms, such as low pressure sodium vapour discharge lamps or low pressure mercury vapo~r ~ discharge lamps, the latter being provided with a lumines-- cent material and a coating having a strong absorption in the blue part of the spectrum.~
The said known lamps satisfactorily meet the requirement of a low intenslty of the emittèd blue and near ultraviolet rsdiation. However, they have a number of considerable drawbacks. The low pressure sodlum vapour discharge lamps have a very poor rendition of the colours of the ob~ects illuminated by the lamp. In addition the use of this lamp may involve relatively high installation costs. The low pressure mercury vapour discharge lamps of the above-mentioned type have the drawback of a much lower luminous flux as compared with the sodium vapour discharge lamps. Furthermore a ppor colour rendition is ; obtained by these lamps. A low pressure mercury vapour discharge lamp used up till now for the said purpose has a luminescent coating of antimony and manganese-activated r ~ ~
_3_ .
.~ :
' ~04C)412 calcium halophosphate and an absorption coating comprising a yellow pigment known under the name of nickel titanate (titanium dioxide with some % by weight of nickel oxide and antimony pentoxide). The absorption coating which in addition to nickel titanate may comprise an inert white material such as barium sulphate is chosen to be such that the requirement of passing the 436 nm mercury line for not more than 30 % is met for illumination of photo-lithographic rooms. This known lamp (40 W type) has a luminous flux of approximately S0 lm/W and has the following C.I.E. colour rendering indices: Ra=44~ Rg = -130, R13 = 37, R14 (average of the colour rendering indices for 14 test colours) = 26.
.~
Also in low pressure mercury vapour discharge lamps having a satisfactory colour rendition and intended for general illumination purposes it i:s known to use a blue and near ultraviolet radiation absorbing coating located between the luminescent coating and the gtass envelope of the lamp. These lamps might be made suitable for illumination of photolithographic rooms by making the absorption coating thicker. The requirement of not passing more than 30% of the 436 nm mercury line can then be satisfied. It is true that an improved colour rendition is obtained with lamps mod-ified in this manner, but this considerably goes to the ex-, ~;
pense of the luminous flux emitted by the lamp. These lamps ' 25 have therefore been found to be less suitable in practice.
., .
' The object of the invention is to provide a , ~
low pressure mercury vapour discharge lamp which does not '`"' . , .
: ~, P~ 7306 24-10~ 74 ~' ' - .
104~412 .
emit sub~tantially any ultraviolet radiation and very little blue radiation and with which both a high luminou~ flux and a satisfactory ~olour rendition is obtained. "Satisfactory colour rendition" i9 understood to mean -in this description ; 5 and in the Claims an average colour rendering index R of at least 80.
A low pressure mercury vapour discharge lamp .having a sati~factory colour rendition according to the invention i9 provided with a glass envelope whose inner side i~ coated with two ~uperposed coat~ngs, the first coating directly provided on the glass en~elope comprising a material absorbing ultraviolet and blue radiation and absorbing the 436 nm mercury line ~or at least 70% and mainly passing ~lsible radiation at wavelengths of more than 480 mn, the second coating being a luminescent coating provided on the ~lrot coating on the discharge side, and is charactcrized ln that the second coating comprise~ at least three luminescent materia~ the first of which is a material activated by tri-; ~alent europium, the second is a green emitting terb.ium-ac-tivated material and the third is chosen from the group o~
; alkaline earth metal disilicates activated by bivalent euro-pium and alkaline earth metal aluminates or alkaline earth ; l metal magnesium aluminates activated by bivalent europium ~or by bivalent europium and by bivalent manganese and having the hesagonal ~errito structure.
A low pressure mercury vapour discharge lamp ~- according to th- invention has an absorption coating for - ultraviolet and blue radiation likewi~e as the known lampa.
-5- `
~ -` '. ~.
104~41Z
This absorption coating is chosen to be such that at least 70% of the blue mercury line at 436 nm is absorbed and that the visible radiation at wavelengths of more than 480 nm is mainly passed (that is to say, for at least 70/0). A
satisfactory colour rendition (R ~80) is obtained with the lamp if at least one luminescent material from each of the three above-mentioned groups is used in the luminescent coating provided on the absorption coating. A result of the absence of ultraviolet and deep-blue radiation is that the colour temperature of the radiation emitted by a lamp accord-ing to the invention is low, for example, 2S00 K. A lamp according to the invention may therefore be used very ad-vantageously for general illumination purposes in those cases where such a low colour temperature is desired. The lamps accortlng to the lnvention are particularly suitable for lllumlnatlng rooms where photolithographic processes are performed. It has been found that the lamps ln such rooms can be used without any danger of unwanted influence on the photoreslsts conventlonally used. In addition a luminous ` 20 flux is obtained with these lamps which is considerably hlgher than that of the known yellow emltting low pressure mercury vapour discharge lamps (for example, 30% or more).
Thls increase in the luminous flux is accompanied by a drastic improvement of their colour rendition.
~ A lamp according to the invention whose first ; (absorbing) coating comprises at least a material of the group nickel-titanate (t`itanium dioxide with nickel oxide ; and antimony pentoxide), manganese-activated magnesium arsenate ``
~ PHN 7306 1~14041Z
mixed with titanium dioxide and manganese-activated magnesium germanate mixed with titanium dioxide is preferably chosen.
These known pigments have very suitable absorption properties for the envisaged object which properties are also maintained during operation of the lamp for a long time. The extent of absorption may be regulated in the said pigments by mixing them with an inert white material such as barium sulphate.
For the first luminescent material a compound activated by trivalent europium is used. Examples of such red luminescing materials are the vanadates, phosphate-~nadates or phosphate borate vanadates of yttrium, gadolinium or lanthanum and the oxysulphides of oxyhalides of yttrium or lanthanum. An oxide of at least one of the elements yttrium, lanthanum, gadolinium and lutetium activated by trivalent, europium is preferably used in a lamp according to the in-vention because the highest luminous fluxes are obtained with these red luminescing materials.
.
The second luminescent material in a lamp ac-cording to the invention is a terbium-activated green luminescing material, that is to say at least 75% of the visible radiation emitted by the material is found in the spectrum between 530 . .
~ and 560 nm. Suitable materials are, for example, the terbium-: i activated alkaline earth metal tungstates. However, terbium-~ 25 activated cerium aluminate is preferred, particularly cerium `~ mangesium aluminate Applicants Canadian Patent 895,779 - issued March 21, 1972 and application 184,492 - filed November 3, 1972.
An optimum colour rendition combined with a high luminous flux ~9~
10404~Z
is obtained with these materials.
A lamp according to the invention comprises as a third luminescent material a material from the group of the alkaline earth metal disilicates activated by bivalent europium (see Canadian Patent 895,779) and the alkaline earth metal aluminates (see Canadian Patent 895,779 and ap-` plication 184,492) or alkaline earth metal magnesium alum-; inates (see Canadian patent application 184,492) activatedby bivalent europium or by bivalent europium and bivalent man-ganese and having a hexagonal ferrite structure. Preferably a strontium magnesium a luminate activated by bivalent eur-opium or by bivalent europium and bivalent manganese is used as a third luminescent material because these are the most efficient materials of the said group.
The invention will now be further described with reference to a drawing and a number of examples and measure-ments.
In the drawing Fig. 1 diagrammatically shows partly in a cross-section a low pressure mercury vapour ~' 20 discharge lamp according to the invention and - I Fig. 2 shows the spectral energy distribution of the radiation emitted by a lamp according to the in-vention.
In Fig. 1, 1 is the cylindrical glass envelope ;,, 25 of a low pressure mercury vapour discharge lamp according to the invention. Electrodes 2 and 3 are placed at the .
.~, , ~ - 8 -A~
104~4~2 ends of the lamp between which the discharge is maintained during operation. The envelope I is coated on the inner side with an absorption coating 5 which absorbs the 436 nm mercury line generated in the low pressure mercury vapour discharge for at least 70%. A luminescent coating 4 consisting of a combination of luminescent materials according to the invention is provided on the coating 5 on the discharge side of this coating. The lamp is of the 40 W type.
The following examples 1 to 6 all relate to lamps of the type described with reference to Fig. 1. For all examples these spplies that the luminescent coating com-prises a total of 4 gms of the mixture of luminescent materials mentioned in each example and that the absorption coating absorb,s 75Z of the 436 nm mercury line.
Absorption coating: 3 gms of manganese activated magnesium ; arsenate mixed with lOY. by weight of titanium dioxide. Pirst ~, luminescent material: yttrium phosphate vanadate activated ,. .
by trivalent europium in a quantity of 64% by weight of the -~ 20 total quantity of luminescent materials (4gms). Second luminescent material: terbium activated strontium tungstate ~, in which in addition to terbium, sodium is also built in for ,. :, ~, charge compensation (30% by weight). mird luminescent . .
material: strontium magnesium aluminate activated by bivalent europium defined by the formula Sr5E~0 5Mg6A155094 (6% by w~ight).
~` EXAMPLE 2 ~::
Absorption coating: see Example 1.
:''' _9_ Pl~ 73~
; ~ , 104~41Z
~irst~luminescent material: yttrium oxide activated by trivalent europium (56% by weight).
Second luminescent material~ see Example 1 (34% by weight).
Third luminescent material: see Example 1 (9~ by weight).
EXA~LE 3.
Absorption coating: see Example 1.
Flrst luminescent material: see Example 2 (55~ by weight).
Second lumine~cent material: see Example 1 (18~ by wei~ht).
Third luminescent material: barium strontium disilicate activated by bivalent europium (27~ by weight).
EXA~LE 4.
Absorption coating: a mixture of 10~ by weight o~ nickel titallate and 90~ by weight of barium sulphate.
First luminescent matorial: see Example 2 (58% by weight).
Second luminescent material: terbi~n activated ceri~m ~agnesium ~luminate defined by the formula CeO 70Tbo 30MgA11119 (31%
by wel~t).
Third luminescent material: seo Ex~mple 1 (11% by weight).
EXA~LE 5 Absorption coating: see Example 4 First luminescent material: see Example 2 (55~ by woight) Second luminescent material: see Example, 4 (15~ by weight).
Third luminescent material: see Example 3 (30% by weight).
EXAMPLE 6.
~;25 Absorption coating: see Example 4 First luminescont material: see Example 1(62~ by weight.
Second l~uninescent material: see Fxample 1(19~ by weight) Third luminescent material: see Example 3 (19% by weight).
- -10_ ~ .
p}~ 730G
2l~10--197!1 , , 1~)4~41Z
or the lamp~ according to Examples 1 to 6 the luminous flux L0 in lm/W was measured a~ter 100 operating hours, the general colour rendering index Ra (average value of the colour rendering indices for 8 test colours), Rg (rendering index for deep red colours), R13 (rendering index for skin colour) and finally the mean value of 14 rendering indices R14. The measurements are summar~zed in the ~ollowing table. ~or the purpose of comparison the table includes in . Example A the meaisurements o~ the kno~n yellow emitting low pressure mercury vapour discharge lamps. These known lamps have a. nickel titanate-containing absor.ption coating (~5 absorption Or the 436 nm mercury line) and a luminescent.
~. coating of antimony and manganese activated calcium j halophosphate (warm white).
, : l S ~ ____ TA~EL
~, Xxample A . 1 . 2 3 4 5 6 ; LO(lm/W) 50 ~7 65 64 65 68 58 , ~. . .
~ . . Ra 44 . 84 87 83 88 84 80 i ,.................................................................... ..
,~ R9 .-130 ~ 70 -2 7 .18 19 77 , ,~. . .
i~ 20 Rl 3 37 72 86 82 85 81 69 ,Fig. 2 shows the spectral energy distribution-of ,. .the lamp according to the invention mentioned in Example 4 in the form Or a graph. The wavelength is plotted in nm on the horlzontal axis and the emitted radiation energy E is plotted in arbitrary units on the vertical axis. The reference Hg in the graph denotes the visisble mercury lines emitted by the la~p .
, .
.. .. .
"Low pressure mercury vapour discharge lamp".
The invention relates to a low pressure mercury vapour discharge lamp having a satisfactory colour ren-dition~ provided with a glass envelope whose inner side is coated with two superposed coatings, the first coating provided directly on the glass envelope comprising an ultraviolet and blue radiation absorbing material and ab-sorbing the 436 nm mercury line for at least 70% and mainly passing visible radiation at wavelengths of more than 480 nm, the second coating being a luminescent coating provided on the first coating on the discharge side. Par-ticularly the invention relates to such a lamp intended for illuminsting photolithbgraphy rooms.
In , for example~ samiconductor technology so-called photolithographic processes are used on a large ` scale. In these processes a certain pattern is provided on a substrate by coating the substrate with a photo-resist whereafter the substrate thus coated is exposed through a mask with radiation to which the said resist is sensitive. The resist then hardens at the areas which are exposed. Subsequently the unexposed resist can be removed and the desired pattern can be provided on the substrate, for example, by etching.
Most photoresists used in the technique harden under the influence of eledtromagnetic radiation having certain wavelengths. The extent of hardening of the photo-j~' ", .
;
. ,~ ., -2_ ' ::
104~41Z
,, resist as a function of the wavelength of the incident radiation is indicated by a sensitivity curve. The maximum of this sensitivity curve is in the blue or near ultra-violet part of the spectrum for most photoresists. It is evident that in the illumination of the rooms where the said photolithographic processes are carried out light sources are to be used which do not comprise radiation or comprise as little as possible radiation to which;the photoresist is sensitive. So ar lamps emitting yellow light have been used insuch rooms, such as low pressure sodium vapour discharge lamps or low pressure mercury vapo~r ~ discharge lamps, the latter being provided with a lumines-- cent material and a coating having a strong absorption in the blue part of the spectrum.~
The said known lamps satisfactorily meet the requirement of a low intenslty of the emittèd blue and near ultraviolet rsdiation. However, they have a number of considerable drawbacks. The low pressure sodlum vapour discharge lamps have a very poor rendition of the colours of the ob~ects illuminated by the lamp. In addition the use of this lamp may involve relatively high installation costs. The low pressure mercury vapour discharge lamps of the above-mentioned type have the drawback of a much lower luminous flux as compared with the sodium vapour discharge lamps. Furthermore a ppor colour rendition is ; obtained by these lamps. A low pressure mercury vapour discharge lamp used up till now for the said purpose has a luminescent coating of antimony and manganese-activated r ~ ~
_3_ .
.~ :
' ~04C)412 calcium halophosphate and an absorption coating comprising a yellow pigment known under the name of nickel titanate (titanium dioxide with some % by weight of nickel oxide and antimony pentoxide). The absorption coating which in addition to nickel titanate may comprise an inert white material such as barium sulphate is chosen to be such that the requirement of passing the 436 nm mercury line for not more than 30 % is met for illumination of photo-lithographic rooms. This known lamp (40 W type) has a luminous flux of approximately S0 lm/W and has the following C.I.E. colour rendering indices: Ra=44~ Rg = -130, R13 = 37, R14 (average of the colour rendering indices for 14 test colours) = 26.
.~
Also in low pressure mercury vapour discharge lamps having a satisfactory colour rendition and intended for general illumination purposes it i:s known to use a blue and near ultraviolet radiation absorbing coating located between the luminescent coating and the gtass envelope of the lamp. These lamps might be made suitable for illumination of photolithographic rooms by making the absorption coating thicker. The requirement of not passing more than 30% of the 436 nm mercury line can then be satisfied. It is true that an improved colour rendition is obtained with lamps mod-ified in this manner, but this considerably goes to the ex-, ~;
pense of the luminous flux emitted by the lamp. These lamps ' 25 have therefore been found to be less suitable in practice.
., .
' The object of the invention is to provide a , ~
low pressure mercury vapour discharge lamp which does not '`"' . , .
: ~, P~ 7306 24-10~ 74 ~' ' - .
104~412 .
emit sub~tantially any ultraviolet radiation and very little blue radiation and with which both a high luminou~ flux and a satisfactory ~olour rendition is obtained. "Satisfactory colour rendition" i9 understood to mean -in this description ; 5 and in the Claims an average colour rendering index R of at least 80.
A low pressure mercury vapour discharge lamp .having a sati~factory colour rendition according to the invention i9 provided with a glass envelope whose inner side i~ coated with two ~uperposed coat~ngs, the first coating directly provided on the glass en~elope comprising a material absorbing ultraviolet and blue radiation and absorbing the 436 nm mercury line ~or at least 70% and mainly passing ~lsible radiation at wavelengths of more than 480 mn, the second coating being a luminescent coating provided on the ~lrot coating on the discharge side, and is charactcrized ln that the second coating comprise~ at least three luminescent materia~ the first of which is a material activated by tri-; ~alent europium, the second is a green emitting terb.ium-ac-tivated material and the third is chosen from the group o~
; alkaline earth metal disilicates activated by bivalent euro-pium and alkaline earth metal aluminates or alkaline earth ; l metal magnesium aluminates activated by bivalent europium ~or by bivalent europium and by bivalent manganese and having the hesagonal ~errito structure.
A low pressure mercury vapour discharge lamp ~- according to th- invention has an absorption coating for - ultraviolet and blue radiation likewi~e as the known lampa.
-5- `
~ -` '. ~.
104~41Z
This absorption coating is chosen to be such that at least 70% of the blue mercury line at 436 nm is absorbed and that the visible radiation at wavelengths of more than 480 nm is mainly passed (that is to say, for at least 70/0). A
satisfactory colour rendition (R ~80) is obtained with the lamp if at least one luminescent material from each of the three above-mentioned groups is used in the luminescent coating provided on the absorption coating. A result of the absence of ultraviolet and deep-blue radiation is that the colour temperature of the radiation emitted by a lamp accord-ing to the invention is low, for example, 2S00 K. A lamp according to the invention may therefore be used very ad-vantageously for general illumination purposes in those cases where such a low colour temperature is desired. The lamps accortlng to the lnvention are particularly suitable for lllumlnatlng rooms where photolithographic processes are performed. It has been found that the lamps ln such rooms can be used without any danger of unwanted influence on the photoreslsts conventlonally used. In addition a luminous ` 20 flux is obtained with these lamps which is considerably hlgher than that of the known yellow emltting low pressure mercury vapour discharge lamps (for example, 30% or more).
Thls increase in the luminous flux is accompanied by a drastic improvement of their colour rendition.
~ A lamp according to the invention whose first ; (absorbing) coating comprises at least a material of the group nickel-titanate (t`itanium dioxide with nickel oxide ; and antimony pentoxide), manganese-activated magnesium arsenate ``
~ PHN 7306 1~14041Z
mixed with titanium dioxide and manganese-activated magnesium germanate mixed with titanium dioxide is preferably chosen.
These known pigments have very suitable absorption properties for the envisaged object which properties are also maintained during operation of the lamp for a long time. The extent of absorption may be regulated in the said pigments by mixing them with an inert white material such as barium sulphate.
For the first luminescent material a compound activated by trivalent europium is used. Examples of such red luminescing materials are the vanadates, phosphate-~nadates or phosphate borate vanadates of yttrium, gadolinium or lanthanum and the oxysulphides of oxyhalides of yttrium or lanthanum. An oxide of at least one of the elements yttrium, lanthanum, gadolinium and lutetium activated by trivalent, europium is preferably used in a lamp according to the in-vention because the highest luminous fluxes are obtained with these red luminescing materials.
.
The second luminescent material in a lamp ac-cording to the invention is a terbium-activated green luminescing material, that is to say at least 75% of the visible radiation emitted by the material is found in the spectrum between 530 . .
~ and 560 nm. Suitable materials are, for example, the terbium-: i activated alkaline earth metal tungstates. However, terbium-~ 25 activated cerium aluminate is preferred, particularly cerium `~ mangesium aluminate Applicants Canadian Patent 895,779 - issued March 21, 1972 and application 184,492 - filed November 3, 1972.
An optimum colour rendition combined with a high luminous flux ~9~
10404~Z
is obtained with these materials.
A lamp according to the invention comprises as a third luminescent material a material from the group of the alkaline earth metal disilicates activated by bivalent europium (see Canadian Patent 895,779) and the alkaline earth metal aluminates (see Canadian Patent 895,779 and ap-` plication 184,492) or alkaline earth metal magnesium alum-; inates (see Canadian patent application 184,492) activatedby bivalent europium or by bivalent europium and bivalent man-ganese and having a hexagonal ferrite structure. Preferably a strontium magnesium a luminate activated by bivalent eur-opium or by bivalent europium and bivalent manganese is used as a third luminescent material because these are the most efficient materials of the said group.
The invention will now be further described with reference to a drawing and a number of examples and measure-ments.
In the drawing Fig. 1 diagrammatically shows partly in a cross-section a low pressure mercury vapour ~' 20 discharge lamp according to the invention and - I Fig. 2 shows the spectral energy distribution of the radiation emitted by a lamp according to the in-vention.
In Fig. 1, 1 is the cylindrical glass envelope ;,, 25 of a low pressure mercury vapour discharge lamp according to the invention. Electrodes 2 and 3 are placed at the .
.~, , ~ - 8 -A~
104~4~2 ends of the lamp between which the discharge is maintained during operation. The envelope I is coated on the inner side with an absorption coating 5 which absorbs the 436 nm mercury line generated in the low pressure mercury vapour discharge for at least 70%. A luminescent coating 4 consisting of a combination of luminescent materials according to the invention is provided on the coating 5 on the discharge side of this coating. The lamp is of the 40 W type.
The following examples 1 to 6 all relate to lamps of the type described with reference to Fig. 1. For all examples these spplies that the luminescent coating com-prises a total of 4 gms of the mixture of luminescent materials mentioned in each example and that the absorption coating absorb,s 75Z of the 436 nm mercury line.
Absorption coating: 3 gms of manganese activated magnesium ; arsenate mixed with lOY. by weight of titanium dioxide. Pirst ~, luminescent material: yttrium phosphate vanadate activated ,. .
by trivalent europium in a quantity of 64% by weight of the -~ 20 total quantity of luminescent materials (4gms). Second luminescent material: terbium activated strontium tungstate ~, in which in addition to terbium, sodium is also built in for ,. :, ~, charge compensation (30% by weight). mird luminescent . .
material: strontium magnesium aluminate activated by bivalent europium defined by the formula Sr5E~0 5Mg6A155094 (6% by w~ight).
~` EXAMPLE 2 ~::
Absorption coating: see Example 1.
:''' _9_ Pl~ 73~
; ~ , 104~41Z
~irst~luminescent material: yttrium oxide activated by trivalent europium (56% by weight).
Second luminescent material~ see Example 1 (34% by weight).
Third luminescent material: see Example 1 (9~ by weight).
EXA~LE 3.
Absorption coating: see Example 1.
Flrst luminescent material: see Example 2 (55~ by weight).
Second lumine~cent material: see Example 1 (18~ by wei~ht).
Third luminescent material: barium strontium disilicate activated by bivalent europium (27~ by weight).
EXA~LE 4.
Absorption coating: a mixture of 10~ by weight o~ nickel titallate and 90~ by weight of barium sulphate.
First luminescent matorial: see Example 2 (58% by weight).
Second luminescent material: terbi~n activated ceri~m ~agnesium ~luminate defined by the formula CeO 70Tbo 30MgA11119 (31%
by wel~t).
Third luminescent material: seo Ex~mple 1 (11% by weight).
EXA~LE 5 Absorption coating: see Example 4 First luminescent material: see Example 2 (55~ by woight) Second luminescent material: see Example, 4 (15~ by weight).
Third luminescent material: see Example 3 (30% by weight).
EXAMPLE 6.
~;25 Absorption coating: see Example 4 First luminescont material: see Example 1(62~ by weight.
Second l~uninescent material: see Fxample 1(19~ by weight) Third luminescent material: see Example 3 (19% by weight).
- -10_ ~ .
p}~ 730G
2l~10--197!1 , , 1~)4~41Z
or the lamp~ according to Examples 1 to 6 the luminous flux L0 in lm/W was measured a~ter 100 operating hours, the general colour rendering index Ra (average value of the colour rendering indices for 8 test colours), Rg (rendering index for deep red colours), R13 (rendering index for skin colour) and finally the mean value of 14 rendering indices R14. The measurements are summar~zed in the ~ollowing table. ~or the purpose of comparison the table includes in . Example A the meaisurements o~ the kno~n yellow emitting low pressure mercury vapour discharge lamps. These known lamps have a. nickel titanate-containing absor.ption coating (~5 absorption Or the 436 nm mercury line) and a luminescent.
~. coating of antimony and manganese activated calcium j halophosphate (warm white).
, : l S ~ ____ TA~EL
~, Xxample A . 1 . 2 3 4 5 6 ; LO(lm/W) 50 ~7 65 64 65 68 58 , ~. . .
~ . . Ra 44 . 84 87 83 88 84 80 i ,.................................................................... ..
,~ R9 .-130 ~ 70 -2 7 .18 19 77 , ,~. . .
i~ 20 Rl 3 37 72 86 82 85 81 69 ,Fig. 2 shows the spectral energy distribution-of ,. .the lamp according to the invention mentioned in Example 4 in the form Or a graph. The wavelength is plotted in nm on the horlzontal axis and the emitted radiation energy E is plotted in arbitrary units on the vertical axis. The reference Hg in the graph denotes the visisble mercury lines emitted by the la~p .
, .
.. .. .
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A low pressure mercury vapour discharge lamp having a satisfactory colour rendition, provided with a glass envelope whose inner side is coated with two super-posed coatings, the first coating directly provided on the glass envelope comprising a material absorbing ultraviolet and blue radiation and absorbing the 436 nm mercury line for at least 70% andmainly passing visible radiation at wavelengths of more than 480 nm, the second coating being a luminescent coating provided on the first coating on the discharge side, characterized in that the second coating comprises at least three luminescent materials, the first being a material activated by trivalent europium, the second being a green emitting terbium-activated material and the third material being chosen from the group of alkaline earth metal disilicates activated by bivalent europium and the alkaline earthmetal aluminates or alkaline earth metal magnesium aluminates activated by bivalent europium or by bivalent europium and bivalent manganese and having the hexagonal ferrite structure.
2. A low pressure mercury vapour discharge lamp as claimed in Claim 1, characterized in that the first coating comprises at least a material of the group nickel titanate, manganese activated magnesium arsenate mixed with titanium dioxide and manganese activated magnesium germanate mixed with titanium dioxide.
3. A low pressure mercury vapour discharge lamp as claimed in Claim 1 or 2, characterized in that the first luminescent material is an oxide of at least one of the elements yttrium, lanthanum, gadolinium and lutetium act-ivated by trivalent europium.
4. A low pressure mercury vapour discharge lamp as claimed in Claim 1 or 2, characterized in that the second luminescent material is a terbium activated cerium aluminate or cerium magnesium aluminate.
5. A low pressure mercury vapour discharge lamp as claimed in Claim 1 or 2, characterized in that the third luminescent material is strontium magnesium aluminate act-ivated by bivalent europium or by bivalent europium and bivalent manganese.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL7400223A NL7400223A (en) | 1974-01-08 | 1974-01-08 | LOW-PRESSURE MERCURY DISCHARGE LAMP. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1040412A true CA1040412A (en) | 1978-10-17 |
Family
ID=19820527
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA217,099A Expired CA1040412A (en) | 1974-01-08 | 1974-12-30 | Low pressure mercury vapour discharge lamp |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS50100875A (en) |
| BE (1) | BE824131A (en) |
| CA (1) | CA1040412A (en) |
| DE (1) | DE2460813C2 (en) |
| FR (1) | FR2257144B1 (en) |
| GB (1) | GB1482301A (en) |
| IT (1) | IT1028207B (en) |
| NL (1) | NL7400223A (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL7604308A (en) * | 1976-04-23 | 1977-10-25 | Philips Nv | LOW-PRESSURE MERCURY DISCHARGE LAMP. |
| NL182998C (en) * | 1977-05-06 | 1988-06-16 | Philips Nv | LOW-PRESSURE MERCURY DISCHARGE LAMP. |
| GB2271117A (en) * | 1992-10-02 | 1994-04-06 | Mass Technology | Low pressure mercury vapour lamp and luminescent materials therefor |
| EP1538659A3 (en) * | 2003-06-11 | 2005-06-29 | Fan, Szu Min | Casing structure with yellow light passing surface and its manufacture method |
| US7550910B2 (en) * | 2005-11-08 | 2009-06-23 | General Electric Company | Fluorescent lamp with barrier layer containing pigment particles |
| US20090153016A1 (en) * | 2007-12-17 | 2009-06-18 | General Electric Company | Colored fluorescent lamp |
| DE102008017606A1 (en) * | 2008-04-08 | 2009-10-15 | Litec-Lll Gmbh | Low-pressure gas discharge lamp for influencing the body's melatonin balance |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL148443B (en) * | 1964-12-10 | 1976-01-15 | Philips Nv | LOW-PRESSURE MERCURY DISCHARGE LAMP. |
| NL6717185A (en) * | 1967-12-16 | 1969-06-18 | ||
| BE749569A (en) * | 1969-05-23 | 1970-10-27 | Gen Electric | LUMINESCENT ALKALINOTERROUS TUNGSTATE MATERIALS ACTIVATED BY TERBIUM |
-
1974
- 1974-01-08 NL NL7400223A patent/NL7400223A/en unknown
- 1974-12-21 DE DE2460813A patent/DE2460813C2/en not_active Expired
- 1974-12-30 CA CA217,099A patent/CA1040412A/en not_active Expired
-
1975
- 1975-01-03 GB GB195/75A patent/GB1482301A/en not_active Expired
- 1975-01-03 IT IT19056/75A patent/IT1028207B/en active
- 1975-01-06 FR FR7500223A patent/FR2257144B1/fr not_active Expired
- 1975-01-06 BE BE152170A patent/BE824131A/en not_active IP Right Cessation
- 1975-01-06 JP JP50000144A patent/JPS50100875A/ja active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPS50100875A (en) | 1975-08-09 |
| DE2460813A1 (en) | 1975-07-17 |
| BE824131A (en) | 1975-07-07 |
| DE2460813C2 (en) | 1984-11-29 |
| GB1482301A (en) | 1977-08-10 |
| FR2257144B1 (en) | 1978-11-03 |
| IT1028207B (en) | 1979-01-30 |
| NL7400223A (en) | 1975-07-10 |
| FR2257144A1 (en) | 1975-08-01 |
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