DE2248878A1 - METHOD OF MAKING A STRIPED CATHODE TUBE SCREEN - Google Patents

Description

Dipl.-Ing. H. MITSCHERLICH 8 MONKS 22.

Dipl.-Ing. K. GUNSCHMÄNN! 2TS ?, "

Dr. rer. not. W. KORBER PATENT LAWYERS

Dipl.-Ing. J. SCH ^ iDT-; IV £ R5 5.1o.1972

SONY CORPORATION. -

7-35 Kitashinagawa 6 Chome
Shinagawa-ku
Tokyo, Japan

Patent application

Method of making a striped cathode ray tube display

The invention relates to cathode ray tubes for displaying color images, and is more particularly related a photographic process for the creation of Lichtschluk- ■ Stripes on the fluorescent screen of a cathode ray tube to display colored pictures.

For color television tubes where the fluorescent Screen is divided into surface elements, which consist of a fluorescent material, the light in the primary colors sends out, and in which the surface elements are distributed within the surface of the screen according to a regular pattern are, it is theoretically possible to design the surface elements so that they adjoin one another. When the beam selector, which is usually a shadow mask, right on top of the screen and the electron gun assembly is aligned, the electrons come, which are intended for only one of the sets of surface elements ^, which correspond to a certain color, with these surface elements to the effect, while other surface elements, the should not be excited electronically, should not be exposed to the action of electrons. However, it is difficult

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ORtOlNAL INSPECTED

to achieve a completely precise alignment of the various parts of a color television tube with one another, and therefore have other arrangements were introduced to prevent electrons from exciting a phosphor, which is light that is not the right color.

In a known method of preventing such Shift in color value, each surface element emitting light is surrounded by a border made of a light-absorbing one Material, e.g. made of graphite. Of course, such light-absorbing borders take up part of the area that is used for the Generating light could be used, but there is nothing wrong with this, as long as the remaining usable, Sufficient light emitting area to achieve sufficient brightness of the image.

Since the fluorescent screens of color television tubes are usually made using a photographic process are produced, in which the screen successively consisting of the different phosphors surface elements When applied in the correct arrangement, it is desirable to manufacture the light-absorbing barrier as well to enable photographic means. The surface elements that emit light are made of a fluorescent material usually produced by a photosensitive material, usually a photographic resist, exposed to an image produced by passing light from predetermined starting points through the drop mask to be used in question tube. The final image is practically a negative the shadow mask, because the phosphors are only caused within areas that correspond to the openings of the shadow mask, to adhere to the substrate, which is usually a glass end wall.

The light-absorbing material must be arranged within areas that positively reproduce the shadow mask correspond, apart from that it is to achieve the

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beneficial effect of the light-emitting material 'required is to give the light-emitting surfaces a width that is greater than the true width of the shadow of the corresponding part of the mask. Such an effect can be achieved by designing the perforated mask so that its openings are narrower than they will be in the finished tube and by using the mask with the narrowed openings during the optical exposure processes in preparation for the Application of the phosphors used on the screen. Thereafter, the light-absorbing material is caused to be inside to deposit the borders that surround the surfaces made of the phosphor on the screen, whereupon the Shadow mask is re-etched to enlarge its openings.

However, in this Machetching of the shadow mask, it is difficult to enlarge the openings without changing their shape in any way. There is also the risk that the thickness of the shadow mask changes in a non-uniform manner, so that the shadow mask is deformed. These two phenomena then lead to the electron beams not striking the correct parts of the screen.

The size of the surface elements that are exposed can also be regulated by adjusting the intensity of the the photographic covering means falling light accordingly regulates.

The invention is now based on the object of creating a method that enables a light-absorbing Apply material to the screen of a color television tube using a direct optical shielding process, but in such a way that the surface elements resulting from the light-emitting material have a larger one Width obtained as the opaque surface elements of the shadow mask that are used in the method for producing a Image is used optically.

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According to the invention strips are made of a light-absorbing Material on the screen of a color television tube "produced with the help of a photographic process, which works with a direct shielding of the light that falls through a striped mask that becomes a component of the screen of the color television tube. The mask is first illuminated from predetermined points, a shadow image on a layer of a photosensitive material on the support structure for the screen to create. The mask and the screen are arranged essentially parallel to one another, and the light sources are so far away that the silhouette contains stripes that are essentially the same width as the opaque strips of mask material. However, the light sources are to some extent compared to the Points offset to a side that is the origin points correspond to the electron beams. This offset is sufficient to achieve that one edge of each shadow strip of the correct location of one edge of each of the final strips of light absorbing material on the finished screen. However, the width of each of the shadow stripes is not as great as it is for the stripes from the light-absorbing one Material is required.

After the photographic resist has been exposed, it is developed, and the unexposed stripes Surfaces are removed by washing. A light-absorbing coating is then placed over the screen Material placed on the screen within the uncoated areas between adjacent exposed Strip stuck. The exposed photographic masking agent is then dissolved so that together with it all of the excess light-absorbing material is removed, and that consisting of the light-absorbing material Streaks remain within the areas that were the original Shadows match the mask.

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The screen provided with these stripes is coated again with a photographic masking agent and then again using the same set of light sources exposed, but the light sources become during this second exposure or the second set of exposures arranged slightly differently, so that the shadows created in the second exposure make up the original stripes do not exactly overlap the light-absorbing material. The photographic masking agent is developed again, and the unexposed parts are washed off, so that streaks remain from the photographic masking agent, one edge of which overlaps an edge of each of the strips of the light-absorbing material on the screen. The overlapped edge of each of these strips is the edge that will be the on the finished screen is in the right position. The exposed and developed area is coated again with the light-absorbing material, see above that it sticks to the clean surfaces of the screen and the second edge of each of the original strips from the light-absorbing Material overlaps. Well? the exposed photographic resist is dissolved so that it is simultaneously the light-absorbing material applied as a coating is removed. This leaves streaks from the light-absorbing Back material »that are wider than the original stripes and have edges away from each other that are accurate are arranged as desired in the finished color television tube. After that, strips of phosphors can be used Emit light with the right colors, in the form of coatings on the surfaces between adjacent strips from the light-absorbing material are applied in such a way that they overlap these adjacent strips.

In a modified method according to the invention, the screen, which is covered with a layer of a photographic Covering agent has been coated, exposed to light falling through a shadow mask, but plants this light continues along paths that are on the screen

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overlap, but with the exception of shadow areas that the Position of every third strip of the light-absorbing material correspond to the finished screen. The unexposed one Part of the photographic resist is washed away on the exposed strips of the resist and those therebetween lying strip-shaped surfaces becomes a layer arranged from the light-absorbing material, the exposed masking agent is dissolved, and the entire process is repeated, but this shifts the light sources to create shadows that resemble a second set of light-absorbing Stripes match. The process is now repeated again, the light sources being relocated again so that shadows are created which correspond to a third set of strips of the light-absorbing material.

The invention and advantageous details of the invention are shown below with reference to schematic drawings Embodiments explained in more detail. It shows:

Fig. 1 with parts 1A to 11, the steps of a method for producing light-absorbing strips for the screen of a color television tube;

2 and 3, in partial sections, a color screen and a mask during exposure when producing light-absorbing stripes on a screen;

4 with the parts 4A to 4M the steps of a further method for producing light-absorbing strips on the screen of a color television tube; and

Fig. 5 to 7 in partial sections through a color screen and a mask, the optical exposure, which in the Implementation of the method according to FIGS. 4A to 4M is effected at predetermined times.

In the following, that in FIGS. 1A to 11 and FIG Fig. 2 and 3 illustrated method for producing strips of light-absorbing material is described.

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The first step in this process of creating light-absorbing streaks on a screen for a Color television tube is shown in fig. "1A, where you can get a Glass plate 1 recognizes on whose one layer 2 of a photosensitive photographic masking agent, e.g. Polyvinyl alcohol or the like., Has been applied.

The second step of this process "is to that the layer 2 of the covering means is exposed to an optical image of a mask 4, which is in the same color television tube is to be used as a mask, the relative arrangement of the glass plate 1 and the mask 4 can be seen from Mg. The mask 4 becomes substantially parallel to the glass plate 1 and in the same Arranged position that they occupy opposite the glass plate at a later point in time in the finished color television tube target. On the mask 4 is light coming from three predetermined points, guided so that the light through in the mask formed slot-shaped openings 5 falls. The light sources are arranged so that on the light-sensitive Cover material 2 a sharp shadow image of the mask 4 is created. The light falls depending on the position of the light sources along different paths through each opening 5. A central light beam 3G falls at least in the middle of the Mask, but not exactly at right angles to the mask through the relevant opening 5 and meets the top of the cover means 2 on. The area struck by the light beam 3G essentially corresponds to the area that will later be with coated with a phosphor that emits green light when excited by an electron beam. The two other light rays 3R and 3B also fall through each of the openings 5, but along paths opposite to that Beam 3G trajectories are inclined at different angles and oppositely ·. Here, the light rays are 3R and 3B, however, are arranged so that they strike surfaces opposite to the surface struck by beam 3G in both directions Pages are offset by the same distance. Since all rays pass through the

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the same openings fall and the mask 4 essentially is arranged parallel to the glass plate 1, the rays 3R, 3G and 3B illuminate the photographic cover means 2 strips, all of which have the same width W.

The rays 3R> 3G and 3B can be generated by three separate light sources suitable for exposing a light-sensitive material are switched on at the same time used in making the screens of color television tubes, or by using a single light source used as a radiation source and sequentially arranges them at three different corresponding points. In any case the radiation must reach the layer 2 from the cover means that it is in the manner described under three different angles of the correct size falls through the openings 5.

The next step in the process is for the exposed photosensitive resist 2 to develop will. Here, the unexposed strips are washed off, so that, according to FIG. 1B, open areas 2a between the strips which consist of the exposed photosensitive material 2 remain.

In Fig. 1, the vertical lines running through parts 1A to 11 denote the intervals at which the stripes are to be produced on the screen of a color television tube. These distances are also referred to as division and correspond to the distance T shown in FIG Side adjacent vertical line is separated by a distance which is designated in Fig. 1B with (T + W _p ) / 2. The significance of this distance is that the total width of each of the finished light-emitting strips as shown in FIG. 11 corresponds to the distance Wp. As soon as this point has been reached in the procedure, the position of the left is

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The edge of each of these light-emitting strips is set, and the left, edge of each of these strips is on top of it its right side adjacent vertical line separated by a distance equal to the sum of half of T (Fig. 11) and half of Wp. From Mg. 1B is however, it can be seen that the gaps 2a between adjacent strips 2 are eccentric to those indicated by the perpendicular lines designated boundary lines are arranged.

The next step in the method shown in Figure 1C is that on the entire top of the exposed photographic covering means 2 and the free areas the glass plate 1 within the gaps 2a a layer of a 'light-absorbing material 6 is applied. as light-absorbing material 6, a liquid mixture of graphite and water can be used. After the Applied mixture, the photographic masking agent 2 is removed with the aid of hydrogen peroxide (HpOp) so that only strips 6 of the light-absorbing material remain on the glass plate 1 according to FIG. 1D.

Now the whole process is repeated; this begins with the application of a further layer 7 of a photographic masking agent, as shown in FIG. 1E, which covers the exposed parts of the glass plate 1 and the upper surfaces of the strips 6 of the light-absorbing material. This second coating of resist is then exposed to light falling at a second set of angles through the openings 5 of the mask 4, as shown in FIG. The difference between the angles at which propagate the light beams of Figure 2 and the angles at which 3 propagate as shown in FIG light beams 8R, 8G and ^8B,.. Selected so that the beams 3R> 3G and 3B according to 2 are inclined generally to the left, while beams 8R, 8G and 8B are inclined generally to the right. In the arrangement according to FIG. 3, the beams are preferably by the same magnitude, but in comparison with the arrangement according to FIG. 2, preferably in the opposite direction

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Inclined direction. Furthermore, the width W of the strips exposed to the light rays 8R, 8G and 8B is the same as ^[ the width W in FIG. 2. The exposed photosensitive material 7, as shown in FIG light-absorbing material partially overlaps. .

The next step is that the photosensitive material 7 is developed, 30 that according to Fig. 1F openings 7a arise. The width of these openings is of course equal to the width of each of the strips 6 from the light-absorbing material, because both types of elements were opaque as shadow images of the same Parts of the mask generated.

Another light-absorbing material y applied, at least to the openings 7a, but in practice the material 9 can also be that which is still present cover photographic masking material 7. The light-absorbing material on the photographic cover means is superfluous and is washed off if the covering agent is used in the next step of the process as before Hydrogen peroxide is washed off. When this has been done, only the strips remain on the glass plate 1 as shown in FIG. 1H 6 and 9 back from the light-absorbing material. Since these strips merge into one another, they can according to FIG. 1H collectively referred to as strip 10. It can be seen that the strips 10 are now symmetrical to the vertical delimitation lines are arranged and of course have a greater width than the original strips 6 alone.

With the aid of known photographic processes it is now possible to produce strips of light-emitting phosphors for the desired colors in the manner shown in FIG. 11 on the exposed surfaces of the glass plate to arrange. These light-emitting strips are labeled 11R (red), 11G (green) and 11B (blue) in FIG. 1. Further

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has Mg. 11 appoint that the total width of each of the strips. 10 from the light-absorbing material is equal to T / iL ·, and that, as mentioned, the width of the strips 11R, 11G and 11B, which can actually emit light is equal to Wp.

In its final form shown in Fig. 11 is the Screen "ready to be excited by electron beams passing through the same mask 4 as in Figs. Thus, the width of the electron beams that actually hit the screen is the same as that Width W of light beams 3R, 3G and 3B in Fig. 2. These Width W is greater than the width Wp of Fig. 11 ", i.e., Wp is less than W and W is equal to or less than the expression (T + Wp) / 2.

In the following, with reference to Fig. ..4A to 4M and Fig. 5 to 7 a further method according to the invention is described.

According to this modified method, a surface becomes a glass plate 31 coated with a layer 32 of a photographic resist. Then the covering agent through a mask 33 of the type shown in FIG. exposed to the action of light rays passing through Slit-shaped openings 34 of the mask fall and form separate bundles of rays 35 and 36.

In contrast to the exposure arrangement according to FIGS. 2 and 3, the exposure according to FIG. 5 requires only two light sources, which are arranged in such a way that the beams 35 and 36 falling through the openings 34 each overlap in zones, whose position according to FIG. 5 corresponds to the later position of that phosphor which emits red light. From still Of greater importance is the fact that a strip, which overlaps the zones which later emit green and blue light, is in the shadow of opaque parts of the mask 33 lies and "is not struck by either the bundle of rays 35 or by the bundle of rays 36. This is

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not a direct shadow of the opaque parts of the mask, and therefore you can get this strip so wide train as it is necessary for the production of the light-absorbing strips.

After the cover means 32 has been exposed »is it develops, and the parts that were in shadow areas are washed off to form the open areas 52a, as shown in FIG. 4B to form which have the same width as the light-emitting strips required in this arrangement.

The next step of this method is that, as shown in FIG. 4C, a light emitting material 37 at least on the open areas or zones, 32a, but normally is applied to the entire surface. The remaining photographic masking agent 32 is then dissolved, so that the excess material 37 is also removed and, according to FIG. 4D, only the light-absorbing strips 37 'remain.

According to Fig. 4D, the strips 37 'have the correct width, but their number corresponds to only a third of the required number of such strips. Therefore, everyone has to be up to now The process steps described are repeated twice so that you get the correct number of light-absorbing strips receives.

According to FIG. 4E, the entire area is used in the next work step again with a layer 38 of a photographic Covering means coated. This covering means is then exposed, but the light must of course change Zones fall as in the first described part of the procedure. The second exposure process is shown in Fig. 6; here the two light sources will be like this before exposure offset that their beams 39 and 40 overlap within another set of zones, and that shadows remain within strip-shaped zones, the ones Overlap zones which later emit red or green light.

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The next step of the process is shown in FIG. 4Ϊ in that the -exposed photographic masking agent developed and the covering means within strip-shaped Zones is washed off, so that gaps 38a arise. Now the whole area or at least the zones 38a are applied a layer of a light-absorbing material 41 is applied, as shown in Fig. 4G-, and then the photographic masking means 38 removed, so that only the light-absorbing strips 37 'and 41' remain as shown in FIG. 4H.

The process steps mentioned must now be repeated a third time / in order to produce the further strips that are still required from the light-absorbing material. For this purpose, as shown in FIG. 41, the entire surface is covered again with a photographic covering agent 42, and this covering agent is exposed to light which, as shown in FIG. 7, falls onto the covering agent from other points. The light passes through the openings 34 of the mask 33 in such a way that strip-shaped shadow zones arise which overlap sections of the screen which later emit blue or red light. The sets of angles at which the bundles of rays 43 and 44 are incident differ from the sets of angles characteristic of the bundles of rays 35 and 36 according to FIG. 5 and from the sets of angles characteristic of the bundles of rays 39 and 40 according to FIG Angles, but these angles are not entirely different from those previously used. More precisely, the bundles of rays 43 fall on the same surfaces as the bundles of rays, el, 35 * -. Naph, -Fig .. 5 ,,,. ■ and the bundles of rays, 44, hit the same surfaces like the bundle of rays, 4.0 according to Fig. 6. Thus, it is not: necessary for the light source η.,. to generate this bundle of rays. .provide as many positions as one might initially assume. ■ <-. .. ■ · -, - ■

After exposure, the photographic masking agent becomes 42 developed so that the strip-shaped shown in Fig. 4J Openings 42a arise. Then the whole

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Area according to Pig. 4K coated again with the light-absorbing material 45, whereupon the photographic masking agent is removed, so that finally a complete set of light-absorbing strips 31 ', 41' and 45 'is obtained, as can be seen in FIG. 4L. Now, as shown in FIG. 4M, strips 46R, 46G and 46B made of the relevant phosphors can be applied in such a way that they overlap the light-absorbing strips 37 ', 41' and 45 '.

If the second method just described is used, it is necessary, for example in accordance with Fig. 4B, one at a time To expose strips of the barrier layer formed by the photographic masking means 32, the width of which is somewhat smaller is three times the distance T indicated in Figure 4M. The width of each strip of photographic resist 32 remaining after exposure and development is half that on each side of such a stripe Distance W-g less. Around a strip of the covering means 32 To expose with the correct width, the width W of each of the beams 35 and 36 of FIG. 5 and the corresponding The bundles of rays according to FIGS. 6 and 7 correspond to at least half the width of such an exposed strip. On the other hand, the width of each of the beams 35 and 36 cannot be greater than the total width of such an exposed one Strip of the photographic masking agent. If the same terms are used as before, corresponds to the total width of the exposed strip of the masking means 32 according to FIG. 4B corresponds to the expression 3T - Wg / 2. However, there the width T is equal to the sum of W-n and Wp, results for the Width of the strip of covering means 32 the expression 2T + Wp. This expression denotes the maximum width W of each the bundles of rays 35 and 36 in the event that the bundles of rays completely overlap.

The minimum width W of each of the bundles of rays 35 and results in the case that there is no overlap as follows; _{5T w}

~ 2 -

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The following expression can be derived from this expression!

The full expression is therefore as follows:

T + - | - ^ W ^ 2T + W _p

Claims ;

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INSPECTED

Claims (7)

PATENT FRUITS 11 A method for producing a striped screen for a cathode ray tube for displaying colored images , characterized in that a coating of a photographic covering agent is applied to a surface of a supporting base, that this coating is applied a first time through a shadow mask having several slits between opaque strips is exposed so that the light strikes the cover means along a first set of paths running at a first set of angles; Covering means has been removed, is coated with a liohtschluekenden material, that the photographic covering means is removed from the surface, so that first strips of the light-absorbing material remain on the surface, that the surface is again covered with a photographic cover km means that the second coating of the masking agent is exposed by a second exposure operation to the action of light rays which fall through the slots of the mask at a different set of angles than in the first exposure operation, so that other stripe-shaped zones on the surface Shadows of the opaque parts of the mask are left behind, that the masking agent that has remained unexposed is removed from the surface bearing the second coating, that a layer of a light-absorbing material is applied to those surfaces from which the last-mentioned masking agent that has remained unexposed has been removed, and that the remaining exposed photographic resist is removed. 2. The method according to claim 1, characterized in that g β k t η η that the second treatment process causes that the other strip-shaped zones make up the first strip 309816/0795 overlap the light-absorbing material so that the total width the strip of light-absorbing material after removal of the remaining exposed photographic material Covering means is greater than the width of the shadow of the opaque strips of the shadow mask. 3. The method according to claim 1, characterized in that g e k e η η, that the radiation is directed through the slots of the mask along three different sets of angles so that it falls on three sets of strip-like zones of equal width, separated by evenly spacing are separated, and that the trajectories of the middle set are essentially in the middle, but not exactly in the right At an angle to the surface so that the first strips are displaced in a lateral direction by an amount which is smaller than its width. 4. The method according to claim 3> characterized by g e .- \ k e η η, that the other set of angles causes each "of the various stripe-shaped zones in the opposite sideways direction by an amount less than your width. 5. The method according to claim 4 »characterized in that the other set of angles is the first Set of angles opposite is equal. 6. The method according to claim 1, characterized in that the radiation for the first exposure process the surface is reached along two sets of orbits, and that the bundles of rays are on the surface at least partially overlap a first set of points, 7. The method naoh claim 6, characterized in that the radiation for the second exposure process the surface along two other sets of orbits reaches the point where the bundles of rays appear on the surface a second set of points that overlap the area 309816/0795 a third time with a photographic concealer is covered that a third exposure process is carried out in which the radiation along a third Pair of sets of orbits so that the bundles of rays on the surface are at a third set of Points overlap, and in the shadow of the mask a third set of stripe-shaped zones remains, that in the Shaded parts of the last applied coating are removed, that a layer of a light-absorbing Material is applied to those parts of the surface from which the last applied topcoat has been removed and that the remaining parts of the latter material are removed. The patent attorney: 309816/0735