DE1462853A1 - Method for producing a picture display screen for a cathode ray tube for displaying color pictures - Google Patents

Description

Dr. P. Rossbaeh Patent attorney

Applicant: NV PHiUPS ' BLOEIUMPENFAHHa 1 462853

File: PHN- 1138

September 27, 1966

N.V.Philips • Gloeilampenfabrieken, Eindhoven / Holland

"Method of manufacturing a picture display screen for a cathode ray tube for displaying color pictures ¹¹

The invention relates to a method of manufacturing a display screen for a cathode ray tube Reproduction of color images, in which a luminescent layer is applied to the window using a photosensitive binder, which layer consists of at least two in nearly two Strip-shaped surfaces present with electron excitation in different colors luminescent substances and with the these surfaces by almost strip-shaped surfaces of a surface that does not light up in visible light when excited by electrons and no light-permeable substance are separated, after which a metallic, electron-permeable layer is applied to the luminous layer is applied, which is provided using a photosensitive binder with almost strip-shaped surfaces of a substance that emits an index signal when excited by electrons and in which these surfaces are the position of part of the surfaces dee in the case of electron excitation, ingest a substance that does not light up in visible light and does not allow light to pass through

The preparation of the different surfaces is effected using a photoempfindliohen binder, ie a substance which * no longer dissolves upon exposure to so-called "curing radiation ¹ in a particular solvent, and in each case those part" are irradiated with the on which the concerning · Fabric should be present This can be done in different ways

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On the one hand, the substance to be applied can be in a solution of the photosensitive binder, which is usually also a sensitizer contains, to be suspended »The suspension is spread on the support and dried afterwards, the hardening Radiation directed at those places where the surfaces of the desired material are to be created. This creates the binder insoluble in those places, namely in a solvent which need not be the same as the solvent, in which the binding agent had previously been dissolved · After that, the binding agent and the fabric of the unexposed areas are duroh Washing with a solvent removes “After these process steps are then certain areas of the desired Fabric-covered carrier emerged

On the other hand, it is possible not to suspend the substance to be applied in the solution of the photosensitive binder In this case, only the binder layer is exposed.In the exposed areas, the binder becomes insoluble, and it becomes if the exposure doesn't take too long, a bit sticky as soon as it is wetted with a solvent

There are now two methods to apply the substance in question possible «With one, the unexposed parts are washed away from the binder layer with a solvent, whereby the exposed parts get a little sticky, Danaoh will ütsr the sticky parts of the binder spread a suspension of the toffee to be applied in any suitable medium « Grains of the material then adhere to the sticky parts. Rinsing can remove the grains from the remaining areas will·

In the other method, the locally exposed binder layer is applied spread a suspension of the substance to be applied in any suitable medium that the exposed Parts of the binder layer a little sticky maoht and then dried *

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By rinsing with a solvent for the unbeliohtete Binder, all unexposed binders and the grains on them are simultaneously removed while the grains remain on the exposed sticky parts · Although in these two cases the grains of the substance to be applied on sticky binders, the granular layer formed is usually not dense enough, so that it is in most Cases it is necessary to repeat the whole procedure

The desired division of the almost strip-shaped areas is achieved in all of the methods mentioned so far by using, for example, a point-shaped radiation source and interposing it This source and the exposure to be exposed a mask is arranged in which there are parts permeable to the radiation through which the desired areas can be exposed. Another possibility for achieving the desired division is to use an illuminated mask Lens to be imaged on the Sohioht to be exposed "

In the case of these display tubes described, the almost strip-shaped areas of the material which does not light up in visible light when electrons are excited and does not allow light to pass through are usually attached.These areas are hereinafter referred to as double strips.The double strips normally also have the property that they are not reflective. As a result of these properties of the substance, a suspension of this substance in a solution of the photosensitive binder does not or almost does not allow the curing radiation to endure. If, as is usually the case, the irradiation takes place on the side facing away from the fl ^r M carrier, then the process must be applied when applying these surfaces in which the binder is cut sticky at certain points on which the grains of the substance are made · In order to ensure that these areas actually do not allow light to pass through, it is advisable to repeat the process for sufficient coverage.

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After the se almost strip-shaped surfaces have been attached are, the gaps are successively provided with the substances that light up in different colors when electrons are excited. It is common to apply three fabrics, which are red, green or blue luminescent Because these substances cause the hardening radiation usually let through enough, in these cases the luminescent substance can be suspended in a solution of the photosensitive binder. The hardening of the binder is necessary in all these cases not limited to exactly the space between the already existing surfaces of the intermediate strips stay, it may also, seen from the window, extend partially behind the surfaces, and this is done in particular to to ensure that the space is actually filled

The almost strip-shaped areas of the substance that emits an index signal when excited by electrons, which are referred to below as index stripes, are attached using a photosensitive binder.The index signal can be obtained in various ways ₀ If the substance consists of secondary emission material, an electron current is generated when electrons are excited which is collected on a collecting electrode. In another case, the substance has the property that when electrons are excited it emits radiation which is captured in a photo cell. The signals obtained are used to coordinate the momentary modulation of the electron beam In this case, the substance to be applied is suspended in a solution of the photosensitive binder. These surfaces take the place of a part of the surface of the substance which does not shine in visible light when excited by electrons. This means that eioh. the index stripes are located on the other side of the metal, electron-permeable layer than in part of the intermediate stripes at least not with

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achieve enough energy the width may well be smaller, if only care is taken that there is enough material to generate the desired signal, which emits an index signal when electrons are excited «

A number of masks are used in these various operations, namely a mask with a pattern that corresponds to the Between them, masks with patterns that match the for each of the luminescent substances to be hardened parts of the binder correspond, or a single such mask, each occupying a different position in relation to the window, and one Mask with a pattern that matches the index strips · Difficulties are in getting the masks to match exactly a must and must always be in a precisely defined position in relation to the window and any lens during exposure · With regard to electron optics, it is mostly It is desirable that the luminescent strips in some places are not straight but rather curved and that the width of the luminescent strips are not the same everywhere · therefore must the masks have a very intricate structure

The invention now creates a method that eliminates these sewing parts because the same mask is always present. According to the invention goes with the application of the almost strip-shaped surfaces The substances that light up in different colors when the electrons are excited and the substances that give an index signal when the electrons are excited the photosensitive binder curing radiation through a partially covered mask, which is not in the application of the almost strip-shaped surfaces of the electron excitation visible light shining and no light transmitting material has been used «

The masking of the mask is adapted to the surfaces to be attached « If the image reproduction contains three luminescent · substances »eo are used in the application of the nahesu strip-shaped surfaces from each of these substances each of three consecutive

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the radiation-permeable parts of the mask covered «This can E.g. through an additional mask.In this additional mask, the radiation-permeable parts do not need to be attached with great accuracy, since it is sufficient if the mask is designed in such a way that, on the one hand, only radiation is allowed through that goes through one of three successive radiation-permeable parts of the mask that is always present, and on the other hand no parts of this radiation are blocked Of course, this also applies to a different number of luminescent substances «For covering during the application of the The same applies to index strips. Pur a certain execution the index stripes, apart from a rather narrow stripe that runs almost parallel to the edge of the effective display screen, are at the position of every second intermediate stripe, and the additional mask is adapted to this fact here no high accuracy requirements need to be placed on the additional mask «

Sa the index strips the place of part of the intermediate strips occupy the always present mask during exposure for the index strips the same position in relation to the window and Take the lens, if any, as you did during the exposure for the intermediate strips. This is not readily possible during the exposure for the various luminescent strips, because the curing radiation is just parts of the binder layer that are located between the intermediate strips on the pen «,. find, must harden. The desired adjustment can now be made in various ways. It is possible to refer to the window to move to the always present mask over a distance · that of the distance between the center of an intermediate strip and that of an adjacent space is the same. It is also possible to move the mask over this distance. If the illuminated mask is imaged with the aid of a lens, it is all also possible to bring about an optical shift in which the arrangement remains mechanically unchanged, which is of course preferable · For this purpose, a plane-parallel glass or quartz plate is used, which is

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and index strips are parallel to the mask, but when the fluorescent strips are applied at a small angle around an Aohst parallel to the radial line in the middle of the mask The thickness of the plate and the angle through which it is rotated during the application of the fluorescent strips depend on the unexpected displacement at the position of the window ab · In general, the curing radiation therefore passes through a plane-parallel plate, which is applied during the application the almost strip-like surfaces of the electron excitation not in visible light on shining and no light through- · lassenden substance, and in the application of the almost strip-shaped surfaces of the substance, which emits an index signal when excited by electrons, assumes the same position and in the application of the almost strip-shaped surfaces of the electron excitation in different colors illuminating substances in relation to that lag

When the fluorescent strips of the first color are attached » so when applying the next strips of Leuohtstoffträger The arrangement can be changed in such a way that the curing radiation just hits the other part lying between the intermediate strips. This can be done by shifting the window with respect to the always present mask and the additional mask. Be however, it is preferable to leave the lag of the window unchanged to la sen · There are still two possibilities · In one case, dl « Additional mask shifted in relation to the mask that is always present in such a way that the curing radiation always passes through parts of the existing mask goes that in the previous case or in the verigen

Ilen were covered by the additional mask · In the other case is there for the application of the strips every luminesziereadea Btof * ' fee ei »individual additional marks«

Since a dl · lumineezlerenden stripes partly behind the Ewi » may be located eohtnetreifen and are "lon thought · AUOH wtrden, »eetlmen, on the one hand, the distinctive vellum \

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the mask, which was used in the application of all strips surfaces of the image display base is used, the location the shape and width of the double and index stripes and on the other hand, determine the radio-opaque parts this mask shows the position, shape and width of the parts of the fluorescent trelves that are in contact with the window » This must be taken into account when designing the mask. »The width of the hardened parts of each of the binder layers is not only determined by the radiation-permeable part. the mask, but also by the way in which the material to be applied is applied, namely whether it is in a solution of the photosensitive binder is suspended or whether only the binder layer is exposed and the substance to be applied only in a later stage the sticky parts should adhere, and, if also slightly, by the exposure time · If the substance to be applied is suspended in a solution of the photosensitive binder, the particles cause it in this Substance a certain scattering of the curing radiation, whereby the cured part of the binder layer is broadened Compared to the case where the substance is not suspended in the solution. The influence of the exposure time is larger when the illuminated mask is imaged on the layer to be exposed with the aid of an objective than when in the arrangement the mask is close to the binding agent base » If the illuminated mask is imaged on the sole to be exposed with the help of an objective and if the radially permeable parts of the mask are as wide as the If the material to be applied is suspended in the solution of the photosensitive binder, the exposed parts of the binder are always wider than the unexposed parts at what time wider, that depends on the exposure time · If the · substance to be applied · is not suspended in the 'solution' dl exposed parts of the binder are usually about wider than unexposed parts. By choosing the

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clearing time, they can also be the same width and possibly even a little narrower · As already described, the binder is insoluble in the exposed areas, but if the exposure is not continued for too long, it will become a little sticky as soon as it is wetted with a solvent. Must to maintain the desired width "; nevertheless a longer exposure time was used a thicker binder layer must be used «

The method will now be described as an example with reference to the exposure arrangements shown schematically and not to scale in the drawing

Figure 1 the attachment of the intermediate layers, Figure 2 the attachment of the strips of the first phosphor8 » Figure 3 the attachment of the strips of the second phosphor and Figure 4 the attachment of the index strips

In the figures, 1 is part of the window, 2 is the part that is always present Mask that is illuminated by a radiation source, not shown, 3 a schematically shown lens with which the illuminated mask is imaged on the layer to be exposed on the window and 4 a plane-parallel glass plate with a A bead of about 1 µm, which the hardening radiation can tolerate The mask 2 consists of a glass plate 5 with almost strip-shaped surfaces 11, 13, 15, 17, 19, 21, 23, 25, 27, 29 and 31, which do not let the curing radiation through · These have a width of a little more than 37 microns in the center of the mask. at the image act the radiation-permeable parts 12, 14, 16, 18, 20, 22, 24, 26, 28 and 30, the one in the middle of the mask Width of a little less than 37 microns, as an object «

The inside of the glass window 1 is first covered with an aqueous polyvinyl alcohol solution that contains a Biohromat, s "B" Ammonium dichromate, contains as a sensitizer * After drying

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is this layer exposed to the influence of the hardening radiation ' namely according to the arrangement shown in Figure 1! in the "hurry radiation source, not shown, the mask 2, and the lens

3 are firmly arranged in relation to each other and the window 1 is arranged in such a way that it can again assume the same position in relation to the elements mentioned during further processing »For the sake of simplicity, only the hardened parts 41, 42, 43, 44, 45 of the binder layer are , 46, 47, 48, 49 and 50 are shown. However, the window 1 with these cured parts only upon washing away the unexposed portions with a solvent _β This treatment is, of course, outside of the exposure array so that actually the figure illustrates not only a step of the process. The same applies to Figures 2, 3 and

4 to. The curing radiation goes through the plane-parallel glass plate 4, which is arranged parallel to the mask 2. Optically, the arrangement is set up in such a way that an enlargement of occurs · Furthermore, the exposure time is chosen such that, despite the fact that the radiation-permeable parts of the mask are narrower in the middle than the radiopaque ones Parts, due to the broadening that occurs, the hardened parts of the binder layer on the window in the middle almost as well are as wide as the uncured parts such that the hardened parts in the center of the window are about 200 microns wide to have. After the unexposed parts have been washed away from the binder layer, as a result of which the exposed parts have become somewhat sticky, the window is filled with a suspension of iron oxide powder in a dilute solution of polyvinyl alcohol in water. These black powder particles adhere to the nearly strip-shaped sticky binder layer parts. This whole The process is repeated to ensure that the intermediate strips actually do not let any light through «

Then the inside of the glass window 1 with the ones located on it black binder strips 41, 42, 43, 44, 45, 46, 47f 48, 49 and 50 with an aqueous solution of polyvinyl alcohol that a biohromat, e.g., ammonium biohromat, is used as a sensitive

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and in which the first luminescent substance, for example green luminescent β zinc-gadmium sulfide activated with silver, is suspended In the arrangement shown in FIG. 1, the mask 6 is attached to the side of the mask 2, which is not shown, facing the radiation source The surface 61 ensures that the hardening radiation cannot reach the radiation-permeable parts 12 and 14 of the mask 2, the same applies to the surface 62 in relation to the files 18 and 20, for the surface 63 in relation to the parts 24 and 26 and for the surface 64 with respect to the part 30. On the other hand, the mask 6 allows the radiation which is incident on the radiation-permeable parts 16, 22 and 28 of the mask e 2 is directed, unhindered by · In the imaging that takes place in the arrangement shown in FIG τοη 3 ° 10 ^f rotated to ensure that with the same arrangement of the window 1 in relation to the radiation source, not shown, the mask 2 and the lens 3, as indicated in Figure 1, parts of the binder layer that are between the intermediate layers , are irradiated · For the sake of clarity, only the hardened parts 65, 66, 67 and 68 are shown in the binder layer. As already mentioned, the double stripes in the middle of the window are almost flat ·· wide like 'the parts lying on the double stripes and they have a width · τοη about 200 microns The middle layer creates a hardening of the hardened part, because the phosphor is in the binder area. Although the radiation sources 16, 42, and 28 in the putty of the mask a width ve * somethingjrjHif · * al · 97 Micron have and dl I magnification de * , M ^ l ^ mß ^^ mm the g ^ hardness ** divides

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Width of a little more than 200 microns and their edges rest on the adjacent intermediate layers. After that, the unexposed Parts of the binder layer with the lamp inside * fabric waxed away

Then the inside of the glass window 1 with the ones on it black binder strips 41, 42, 43, 44, 45, 46, 47, 48, 49 and 50 and the binder strips 65, 66, 67 and 68 with the first luminescent material present therein covered with an aqueous polyvinyl alcohol solution containing a biohromat, e.g. ammonium dichromate, contains as a sensitizer and in which the second fluorescent substance, e.g. blue luminescent, activated with silver Zinc sulfide, is suspended. After drying this layer becomes exposed to the influence of the curing radiation in accordance with the arrangement shown in FIG The mask 7 is attached to the side of the mask 2 facing the radiation source. The mask 7 consists of a glass plate 70 with thereon almost strip-shaped surfaces 71, 72, 73 and 74, which do not let the hardening radiation through »The surface 71 ensures that the curing radiation cannot reach the radiation-permeable part 12 of the mask 2. The same goes for that Surface 74 in relation to parts 16 and 18, for surface 73 in relation to parts 22 and 24, and for surface 74 in relation to FIG the parts 28 and 30. On the other hand, the mask 7 allows radiation which is incident on the radiation-permeable parts 14, 20 and 26 of the mask 2 is directed, duroh unhindered. In the illustration that appears in the arrangement shown in Figure 3 takes place, the radiation-permeable Parts 14, 20 and 26 act as objects. Otherwise, the arrangement is the same as that of FIG. The mask 7 can be a special mask, but it is also possible to use the mask 6 EU and use this for the arrangement according to FIG. 3 to shift the relevant distance, in the case described 74 microns, from the binder layer are again for the sake of simplicity only the hardened parts 75; 76 and 77 shown. For the same reason, as described in relation to Figure 2, there are Edges of the hardened parts 75, 76 and 77 on the adjacent

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Intermediate strips · Then the unexposed parts of the Bindmitteleohioht with the Leuohtetoff contained therein washed away

The binding agent with the third phosphor is then applied in a corresponding manner. In a known manner, a metal, electron-permeable layer attached, e.g. by vapor deposition of aluminum on one attached organic film · The hardened binder parts with the third Leuohtetoff are in Figure 4 with 101, 102, 103 and 104 indicated, and the aluminum layer with 105 · The organic film is not shown «

The aluminum layer 105 is covered with an aqueous polyvinyl alcohol solution which contains a biohromat, ζ · Β · ammonium blood ohromat, as a sensitizer, and in which a substance is suspended which gives an index signal when excited by electrons, for example calcium aluminum silicate activated with cerium, which at Electron excitation Ultraviolet radiation emitted with a maximum of 3900 % · After drying, this «layer is exposed to the influence of the curing radiation, in accordance with the arrangement shown in FIG The mask θ consists of a glass plate 80 with almost strip-shaped surfaces 81, 82, 83, 84 and 85t which the hardening radiation does not let through The surface 81 ensures that the hardening radiation cannot reach the radiation-permeable part 14 of the mask 2 the same applies to the surface 82 with respect to the part 18, for the surface 83 with respect to the Part 22, for the surface 84 in relation to the part 26 and for surface 85 in relation to the part 30 "On the other hand, the mask 8 transmits the radiation, the radiation-resistant part" 12, 16, 20 "24 and 28 of the mask 2 is directed, unhindered by · With the AbMIdUBg ₉ dl · with the arrangement shown in

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tion takes place, the radiation-permeable parts 12, 16, 20, 24 and 28 are effective as an object. The plane-parallel plate 4 is in this case again arranged parallel to the mask 2, exactly as in the arrangement according to FIG Part of the intermediate layer. Of the binder layer, only the hardened parts 111, 112, 113, 114 and 115 are shown for the sake of simplicity. In this illustration of the radiation-permeable parts 12, 16, 20, 24 and 28, a broadening of the hardened parts occurs in the binder layer because the substance to be applied is located in the binder layer. The radiation-permeable parts 12, 16, 20, 24 and 28 have a width of slightly less than 27 microns in the middle of the window and the magnification of the arrangement is -τη · The exposure time is now chosen such that the width of the hardened parts 111, 112, 113, 114 and 115 in the middle of the window is about 200 microns * Then the unexposed parts of the binder layer are washed away

Finally, the screen formed in this way is heated, whereby the organic substance present, namely the binding agent and the organic film to be baked out

Claim t

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Claims (1)

1 · Method of manufacturing a display screen for a cathode ray tube for displaying color images on the window using a photosensitive binder a luminescent layer is applied, which consists of at least two in almost strip-shaped surfaces when electrons are excited there are substances that light up in different colors and where these surfaces are almost strip-shaped Areas of a substance that does not light up in visible light and does not allow light to pass through when excited by electrons are separated are, after which a metallic, electron-permeable layer is applied to the luminous layer, which using of a photosensitive binder with almost strip-shaped Areas of a substance that emits an index signal when excited by electrons is provided and in which these areas the Position of part of the surfaces of the area that does not light up in visible light and does not allow light to pass through when electrons are excited Ingesting substance, characterized in that during the application of the almost strip-shaped surfaces the electron excitation in different colors that light up and the substances that emit an index signal when electrons are excited, those of the photo-sensitive Binder-curing radiation goes through a partially covered mask, which is almost strip-shaped when applied Areas of the substance that does not light up in visible light and does not allow light to pass through when excited by electrons are used has been· 2 «A method according to claim 1, characterized in that the hoarding radiation Dafi each duroh a plane-parallel flat · goes άβ at der'Auftragung nearly strip-shaped surfaces dee not illuminated in visible light and no light transmitting and emitting upon electron excitation, a Indexeignal in electron excitation substance assumes the glelohe position and in the application of almost β tr ti f enf örmigen Fläohen d§r at bran "troneiianreguftf in terichiedgntn color luminescing substances i" ß * 16 ·. 8098107.1024; - In relation to that position parallel to a small angle around an axis to the radiation-transparent line in the middle of the mask is rotated 809810/1024