DE1958486C - Process for the production of screens with several phosphorescent layers - Google Patents

Description

table deposition of each layer would provide color images.

thin, electrically conductive, transparent auxiliary 15 It has been found that cathode ray tubes

layer (12, 16, 20) is applied, which would be particularly beneficial for reproducing color images

end of the respective electrophoretic deposition saw have properties if they are used in conjunction

durigsvori? ans serves as an electrode. can be operated with screens that have multiple

2. The method according to claim 1, characterized in that ge rere, superimposed phosphorescent indicates that ao have layers on the cleaned surface. Such umbrellas usually have a glass plate serving as a screen substrate and have three layers of different colors (10) a first auxiliary layer (12) made of antimony compared to the known screens with strip-doped Tin oxide with a thickness of about or punctiform phosphorescent coating-5000 A is applied that on this layer genes a number of advantages. These advantages are best (12) as the first, green phosphorescent lights 25 also opposite arrangements for reproduction layer (14) a silver-activated zinc-cadmium from color images taken with a cathode ray tube sulfide layer with a thickness of 1μ ± Ιμ work in conjunction with shading masks, deposited electrophoretically, that on the- The advantages consist in a better dissolution ser Layer (14) a second auxiliary layer (16) made of property, in a higher contrast, as well as be-indium oxide with a strength between 400 A and 30 special in that to operate the cathode ray 500 A is applied and on this layer (16) tube only a single electron generation syeino second, blue phosphorescent luminous star is required.

Layer (18) made of silver-active zinc sulfide with E% are a number of known methods

a thickness of 2 μ ± 0.5 μ electrophoretically manufacture of cathode ray tube screens with

is deposited that on the layer (18) a 35 several contiguous, overlapping one another

Drkte, 400 A to 500 A thick auxiliary layer (20) kenden, phosphorescent layers. Should that be

made of indium oxide and on this cathode ray tube also for A ! turns with a

Plain (20) suitable as a red phosphorescent luminous high radiance, such as that for

layer (22) a 2μ ± Ο, 5μ thick europiumak cathode ray tube indicators for numbers

activated layer of yttrium vandanate or ius 40 and vectors in data processing systems from FaIi

a rare earth element is contained in another one, it turns out that the previous screen arrangements

the red phosphorus deposited electrophoretically or its manufacturing process is not completely

den and that finally the so obtained more peaceful.

layered structure for protection against harmful One of the known methods of manufacture

Ion bombardment in a manner known per se with 45 cathode ray tube screens with several phos-

A protective layer of about 1000 A made of aluminum-fluorescent layers is available under the name Se-

minium is provided. dimentations decay ren known. In this process

3. The method according to claim 2, characterized in that a suitable phosphorus silicate is identified in a that the first auxiliary layer (12) precipitated on solution, and these precipitated particles werchemischem Paths by spraying a medium under the action of gravity through sedimentation deposited from tin chloride, methanol and S mentation on the screen substrate, percent by weight of antimony trichloride based on this method is described, for example, in 42VC heated substrate, the auxiliary layers (16) of the USA. Patent 3 231 775. The said Pa- and (20), however, by means of a high-vacuum publication, also describes another known one steam processes are produced. 55 Process in which the application of the phosphor

4. The method according to claim 1, characterized in that there are gcenzschichten on the cathode ray tube screen indicates that all auxiliary layers are produced by a high vacuum vapor process. High vacuum vaporized and only after their other methods use spraying Use as an electrode when depositing the. Screening substances or a deposition process associated luminous layer from their metallic 60 of these substances from their vapors. All these conductive to the transparent state, however, have certain disadvantages, will. There is a disadvantage to the sedimentation process

5. The method according to any one of claims I in that only screens with relatively to 4, characterized in that the overall coarse grain size can be produced, none strength of all 65 applied to the substrate (10) sufficient uniformity in terms of their thickness Have layers made equal to or smaller than Ι0μ. This results in an inadequate picture, such that the phosphorescent resolution, a low contrast as well as a bad one Layers at an electron accelerating color quality. The sedimentation process to produce

Positioning of multi-layer channels for cathode ray desired resolution. Besides, here is tubes also does not have a sufficiently large luminescent layer, so that the layer thickness is not uniform Luminosity on how it results for the operation of Katho- a relatively large mi Here thickness, The beam tubes for the display of color images. By the USA should throw luminosity operated. This is uniform layer of phosphor on a support, to the fact that the inherent effectiveness is to provide this with a conductive layer and of phosphorus normally because of the electrophoretically applied to the phosphor layer extensive crushing of the phosphorus through form. It is not shown there, however, how strongly reduced to Herivfahlen appears. The shredding io position of screens for color display takes place for the purpose of a high resolution - different materials are applied to the carrier gen to get. They also require you to be able to throw umbrellas.

several layers of relatively large grain size The present invention is therefore based on the increase in acceleration voltages for the excitation, a compared to the known verbesden cathode ray, which is why the deflection-sensitive process for the production of multilayered speed of the beam is correspondingly low, locking wedge luminescent screens for cathode ray tubes ivt, due to the non-uniformity of the phosphor reproduction of colored images, to indicate that the above hues generally do not have less than half of the difficulties mentioned and that S <.horn surface for the representation of figures higher a cathode ray tube with njr one electron density available. 20 generation system is based. The one out of several The screen produced by precipitation from the vapor phase luminescent layers should be a Rejected phosphor layers have the disadvantage of high resolution and good contrast j-eringtn efficiency of the luminescent layer and generally have a good image quality. Because of the relatively low image contrast among the berries, the thickness of the individual layers should be Vimgungen a not kept low environment as multi-layer luminescent screen within the illuminance level. Furthermore, limit the range of tolerances to be controllable. thermal required for this type of production Method steps these screen types on substrate method according to the invention achieved in that the materials such as quartz. The phosphor articles required for activation of the individual luminous layers in borrowed high temperatures harbor the risk of a known manner electrophoretically on the chemical reaction of the phosphor layers are deposited under the screen substrate and that before each other. The spray-on process ultimately resembles this electrophoretic deposition of each liciie disadvantages. Overall, the layer can thus be said to be a thin, electrically conductive, transparent layer the fact that the aforementioned production auxiliary layer is applied, which during the respective process for luminous film layers for cathode 35 ligen electrophoretic deposition process as Radiation tubes for reproducing color images large electrode is used.

The mentioned method is particularly suitable for

Thickness of the various phosphor layers on the production of screens for cathode ray tubes. that create high-density graphical representations

IZs are still supposed to be possible through the French patent 40. Furthermore, the procedures I 121 286 and 1 130 176 are also suitable for the production of screens with large areas. Production of phosphorescent layers with area dimensions.

Cathode ray tubes for display before coloring The invention will be described in the following description

pictures known, in which very finely distributed, gela- explained in more detail in connection with the figures. In dene fluorescent particles on a transparent 45 means

Layer are knocked down. In the case of one the- Fig. 1 the breakdown of the overall process

In this process, the particles are accelerated by a lattice according to the principles of the present invention into a uniform electrode and thus arrive at individual process steps,

a pad provided with an adhesive. F i g. 2 is an enlarged partial cross-sectional view

Due to the structure of the electrode due to the position & rer by prepared according to the teachings of the present precipitated in phosphorescent layer IH invention ™ luminescent screen thickness is very uneven. This undesirable and

Effect can be somewhat mitigated by shifting. 3 is a graphical representation of the dependency

ben the electrode during the growth process; ability of the layer thickness of a shielding layer from the however, it cannot be avoided. For the next time, practice this shift when the field is strong If there were color images, different phospho- of 50 V / cm can be deposited by electrophoresis resecting materials is deposited one after the other.

throw gen. Because here too the individual layers in For the production of a fluorescent screen

have a different thickness is obtained. the teaching of the present invention is first when using such a manufactured 60 a transparent substrate 10, for. B. a glass plate ten screen color distortion. Also these (Fig. 2) are cleaned until a so-called »electric Layers for a given voltage of the cathode-clean «surface is present. In the following tube often too thick. In the second preferred exemplary embodiment outlined in the method Ren throw the various fluorescent mate- rials using a standard soft glass plate as the substrate door rials knocked down next to each other. The screen uses the 65 screen to be created. To clean these materials, the substrate surface is first grooved by means of a net-like cleaning process Electrode system determined. One treated in this way- detergents and treated with a honeycomb The screen provided often does not have the wetted chromic acid solution. That’s something you want to see

further treatment with ammonium bifluoride and with pure water. The substrate is then dried in a clean atmosphere.

To produce the multilayer screen, the glass substrate 10 is now first covered with a thin, transparent, conductive layer, for which tin oxide was used in the preferred embodiment. The thin, transparent, conductive layer 12 (FIG. 2) is applied to the substrate in the following way: First, a mixture of tin chloride and methanol and an ammonium trichloride solution with a proportion of 5 percent by weight is prepared. The substrate 10 is then heated to about 425 "by any known method and then the prepared solution is sprayed onto it in the presence of a water vapor atmosphere. A thin tin oxide layer is thus obtained by chemical deposition. This deposition method and the chemical reactions that occur are described in detail in U.S. Patent 2,732,313, the transparent conductive layer 12 thus obtained consists of tin oxide doped with antimony The purpose of the antimony coating is to shift the permeability of light rays from the near infrared to the visible range and at the same time the degree of conductivity The thickness of the layer 12, which is preferably maintained, is approximately 50Of) A and is checked or controlled by resistance measurements during chemical production, as is known in the art. In the present example, the tin oxide layer has a surface width rstand of 30 b ^! s 40 il and a transmittance in the visible range of about 80%. After the application of the tin oxide layer 12, the screen is washed with a detergent, wetted with chromic acid and finally washed with water.

In accordance with the present preferred exemplary embodiment of the invention, a silver-activated zinc-cadmium-sulfide layer is now applied as a first phosphor layer with a thickness of 4 μ + 1 μ by means of electrophoresis. The following suspension is prepared for this. I-inc slurry of fine particles of the phosphor used with a diameter of 1 to 2 | i, ^{ethyl alcohol containing 5 0} Ze water is suspended and \ 0 * mol / liter thorium nitrate is added. A ratio of about 3.5 mg of phosphorus to 1 ml of flux is preferably used here. The suspension is produced by mixing the ingredients mentioned. The intensive mixing takes about 30 minutes and is accomplished by means of a grinding process through tubes or vibrations. It is important to ensure that the dielectric constant of the binding agent is around 30, since this ensures a relatively high mobility of the charged phosphor particles within the binding agent, so that when performing the electrophoresis one can manage with a relatively low field strength.

F im: phosphor layer 14 with one after activation The resulting green color is electrophoretically applied to the conductive layer of the screen dejected by first the above bcschricfovnc Suspense sense in a suitable one, in the drawing not darpestvtltcn container with one inside Electrode is entered. To carry out the electrophoresis, in the preferred Exemplary embodiment, the coated substrate 10 with the negative pole of a direct current source and a

Platinum electrode connected to the positive pole of this source. The platinum electrode is preferably located 2 cm from the tin oxide layer 12. A field of about 50 V / cm is created by means of the electrodes maintain. It should be noted here that the thickness of the

ίο phosphor layer 14 of extreme importance for the successful manufacture of multilayer cathode ray tube screens. For this let us refer to the diagram in FIG. 3, the curve of which represents the link between the three parameters.

iS gives which effective control of the thickness of the Enable electrophoretically produced phosphor layer 14. These parameters are the time that Field strength and the concentration of the suspension used. It should be noted that for the

ao bene suspension at a field strength of 50 V / cm the precipitation of a 4 μ thick phosphor layer 14 on the substrate provided with the intermediate layer takes about 1.5 minutes. From later For reasons yet to be explained, it is beneficial to have a

The thickness of the phosphor layer 14 is between 3 and 5 p to choose.

After the first phosphor layer 14 in the described Electrophoretically on the first thin, conductive, transparent intermediate layer 12

is deposited from tin oxide, a second transparent, conductive intermediate layer 16 with a Thickness in a range from 400 A to 500 A is applied. In the preferred embodiment, there is the layer 16 made of indium oxide and is by means of

a vacuum evaporation process applied. For this purpose, the substrate 10 with the already layers 12 and 14 located thereon in a vacuum container and brought to a temperature of heated to about 350 'Γ. In the vacuum chamber bc-

there is an indium filament. To the for the To ensure the formation of the indium oxide required water vapor and oxygen atmosphere, oxygen and water vapor are introduced into the chamber in a metered manner, and at the same time, in-

evaporated away from the filament. The various vapors react in one for the expert known manner with each other, creating a thin indium oxide layer 16 above the first Phosphor layer 14 comes about.

The process is controlled in such a way that the layer thickness is in the order of magnitude of 400 A to 500 A already mentioned above, this value being chosen for reasons to be explained later.
It was unexpectedly found that

A second phosphor layer 18 can now be applied to the substrate 10 above the transparent conductive intermediate layer 16 in a manner that allows very careful control, the auxiliary layer 16 being used as an electrode for the electrophoretic application of the next layer. In the preferred embodiment described, a zinc sulfide layer (wall phosphorus) activated with SiI- 'έτ is deposited by electrophoresis in the following way

Beaten 5s. That the tin oxide layer 12, the layer 14 of green phosphorus and the layer 16 of indhtmnxyd The supporting substrate 10 is in turn placed in a container in which a silver-coated

Fourth zinc sulphide phosphorus in the form of a su ^ en

.ion is contained, which in the B »^ L2Sb? w the same concentrations as described above, was prepared before. The phosphor layer 18 is electrophoretically above the second Ie.J "*"" ¹ JJgJ layer 16 using an electrode, autge

brought, which about 2 cm from ^derz . ^u ^ f. ^a "^ ⁿ £ screen area is removed For this purpose, a field strength of about 50 V / cm is graded

The strength of the blue P ^ho ^ ^orsc ™, "Γ carefully within a range of 2μ ± 0.5μ

controlled. ... _iA ■

⁸ In the preferred embodiment example, elw.rdeme

further indium oxide layer 20 above the blue phosphor layer 18 in the ^ SnAeA

Bracht, as it was _{described ^^^^ ie Sc} wSt umoxydschicht 16. ^ «f« Jf ^111C ™ 20 also preferably has a start of 400 A to 500 A and serves as a gl «cM« «J * ^X ] "for the subsequent d« «'« »^ retic precipitation process · J JJ third phosphor layer made of ™ * Europium aWmej yttrium vandanite (or a" ^! F' ^ P ^ Jf ^ e es Durchdri ₌ g ^ S ^ S ^ SSS S ^ ^ display of numerical values of high g £ _h * ^ur ^ _{er vo} * _graphical representations, since the ^ ^nth _h ° ^ae _chichtei f _a ^ _{f, due to} their precise, equal-

_ao S ^^ dtofa-derobenbc ^ rubbedWeta »can be adhered to and due to the SÄ extremely fine uniform particles ^ | _{rmögeOj t cons} *

_{and B} H generally have good picture quality. White

_{it towards t} f _st i _{s a} low rate to that in the getejhm it ^ t ^ ^^ β _Kathod enstrahl _S chirme

_only relatively seldom electrical breakdowns nu ^ν «™ ⁸ J _{the phosphor8C} hinge

«» I «^ Operating voltage relatively low. Furthermore, it follows from the carefully observed thickness distribution of the various phosphorus _chic hten 14, 18 and 22 and the intermediate | ™ ^s .; _{hh color} purity without it being necessary? to have to control the tensions of the intermediate layers Γη in a known manner. It was mentioned at J ⁰ Description of the Preferred Ausführungsbeibestimmte suspensions and certain parameters, but it is clear to the

Screens for cathod Procedure «ne» on ^ nuiocmwH ^

on the third PhosphrfΛ 2 «Mt

the multilayer B «™ j ^e g ™ is

from the previous ^^^ S ^ SSi

the overall strength of ^dre * ^d "| ™" Ι, ϊϊ " _entsDr e

Process applied phosphor layers correspond to

· _Η

_np ^. _{In this case there is} indium chloride, ^r M _elhano i and antimony trichloride. It should be noted that the sheet resistance of an indium oxide layer is 150 to 200 ohms, so that the conductivity therefore remains below that of the tin oxide layer 12. Another alternative in the manufacture

14, 18 and 22 '% 7 «K

lie below. 18 kV is used as

for cathode ray tubes * ur JJJ ^ g

lung viewed as' ^nfol g% t _he fhSdin £ uneen to

voltage

dieg ^ are fulfilled. Further reasons for the S ximal voltage value depend on the

des ^ «» ΗΛ ^ ί ^ Ι ^ Ιίίί a sufficient

together. There ^ \ ^^ Zfcham pacifying method m shear

the tolerances ^ r ^the & arkeni ^ «J layers the ^el drive is. This will be done to whom

ten in the above ^^ f Another znr divorced ren is up to now

In one gender.

The phosphor layers could with a ™ ^eh ^ kie of color pictures; «irr Wj

above already ^he 7j ^ below

ma

the ver-proce-

the present

Play the three

around

one concerns a vacuum evaporation of Ind.ummetail Renut / unsuitable partial pressure / ur Her "^^ emer transparent, conductive layer of indium oxide, the vacuum evaporation of silver or aluminum metal with subsequent Gl.mmentla layers in an ambient atmosphere _{from air the} transparent layers se to make, as well as a Vakuumauidampfung of AluSüum on the substrate 10 with efaer thickness of about 1000 A. in the latter case _not fet the Aluminiumι to _χ In addition, this layer _{must be made transparent after the} rfectrophoretic application of the first phosphor layer 14 by an oxidation process in air. The same aim _{is ^{P by} applying an aqueous solution of ammonium persulfate or by anodic oxidation by means of citric acid. It should be borne in mind that a premature oxidation, which, as mentioned, can also be carried out anodically, affects the aluminum

«™» ^ * ^ ^eliciting - ^{making them} necessary for carrying out the electrophoretic process

Application of the layer 14 is unsuitable.

With regard to the preparation of the phosphorus suspensions, it is clear to the person skilled in the art that metholisobutyl ketone can also be used as a binder instead of ethyl alcohol

S096B / 348

hol is applicable. Furthermore, salts of nitric or acetic acid can be used instead of thorium nitrate with a concentration of 10 " ⁴ mol / l, which corresponds to an ionizable metal in suspension. However, it has been found that thorium nitrate has better adhesion than the salts of the above Acids, possibly due to the inclusion of hydroxides at the interface between the conductive layer and the phosphorus layer, and for this reason thorium nitrate was preferred when practicing the method of the present invention.

In the preferred embodiment according to According to the invention, the second transparent layer 16 made of indiurn oxide was applied by means of a vacuum vapor deposition process. This method was on Place a chemical deposition process such as;: used to apply the first layer 12 was chosen because the well-known chemical vapor deposition processes have the property to react chemically with the phosphorus.

However, the conductive metals such as tin, indium or titanium can also be applied by vacuum evaporation processes. This procedure was for the production of the second and the third layer used while chemical deposition methods only the application of the first, i. the layer lying directly on the glass substrate 10 were reserved. It is also known that aluminum cannot be

war can be applied by water vapor, as this oxidizes the aluminum, whereby it in the non-conductive state passes. For this reason, when vacuum evaporation of aluminum, care must be taken that no water vapor saving

tiaidruck is present in the working atmosphere. It it is therefore conceivable to also produce the first conductive layer 12 from aluminum, this being like the remaining conductive layers, as already mentioned above, only after implementation of the respective electrical

ao trophoretic deposition process is to be converted into the transparent state.

1 sheet of drawings

Claims (1)

1 2 voltage in the order of magnitude of 18 kV is still completely penetrated by the electrons. 1. Procedure for producing screen 5
men with several stacked,
phosphorescent layers more uniform
Starch for cathode ray tubes for playback
of color images, thus marked η el that the phosphor particles of the individual io The invention relates to a method for manufacturing Luminous layers in per se known white elec- Phosphorescent layers arranged trophoretically on the Schinn substrate (10) are separated and that before this electrophoretic strength for cathode ray tubes for re-