DE1043522B - Process for the production of storage screens for cathode ray tubes - Google Patents

Description

The invention relates to a method for the production of storage screens for cathode ray tubes, in which a metal wire grid is used as a carrier for the storage layer.

The known screens for storage tubes generally consist of a thin layer of insulating material (with a thickness of about 0.5 μ ) which is metallized on one side and is supported by a highly transparent metal wire grid with very fine meshes (about 20 meshes per millimeter).

It is known that reading the electrical recorded on the screen of the storage tube Signals can occur very often one after the other during a period of time called the decay time will.

With the known umbrellas, it is practically impossible to reduce the decay time of the umbrellas during manufacture to be determined precisely in advance or to keep it at a constant value.

The aim of the invention is therefore to create ao a process for the production of such screens, with which the decay time in the production of Set to a desired value in advance and this value with a value that is sufficient in practice Accuracy can be maintained.

In the method according to the invention, measures are used in part, which per se in the Manufacture of screens for cathode ray tubes are known. So it is known in the manufacture of screens to cover a metal wire grid with an organic membrane, one surface of which is then provided with a metal coating. Other manufacturing processes use organic Skins are formed, which are then destroyed by heat treatment.

Using these measures, the manufacturing method according to the invention is characterized in that the metal wire mesh covered in a known manner with an organic membrane is, however, the organic substance forming the pellicle with activating impurities is mixed that on the side of the membrane facing the grid, an insulating layer is applied is, while the metal coating in a known manner on the opposite side of the cuticle is applied, and that the organic cuticle is then carried out in a manner known per se Heat treatment is destroyed, but the impurities partially transform the insulating layer into one convert semiconducting layer, which is in imperfect contact with the metal coating.

The decay time of the screens constructed in this way depends on the amount of impurities introduced away. By appropriate measurement of this amount can

for the production of storage screens
for cathode ray tubes

Applicant:

Compagnie Generale de Telegraphie
sans FiI, Paris

Representative: Dipl.-Ing. E. Prinz, patent attorney,
Munich-Pasing, Bodenseestr. 3 a

Claimed priority:
France, June 8, 1955

Francis Boulet and Roger Rigot, Paris,
have been named as inventors

influence the cooldown time during production as desired and keep it constant.

Collodion is expediently used to form the organic membrane. The impurities the z. B. can consist of magnesium, sulfur, zinc oxide or a soluble zinc salt, are added to the collodion in a ratio of about 1: 10,000. They convert the insulating layer of the The grid is partially converted into a semiconducting layer, thus creating an intermediate zone between the insulating layer and the metal layer, which determines the decay time of the finished screen.

The storage screen produced according to the method described thus contains a semiconducting intermediate layer between the metal layer and the insulating layer, which is therefore not in perfect contact exhibit.

Further details emerge from the description of an exemplary embodiment on the basis of Drawing. Herein shows

Fig. 1 shows the greatly enlarged section through the screen before the heat treatment and

Fig. 2 shows the structure of the finished screen in a schematic manner.

Fig. 1 shows a thin collodion membrane 1 of constant thickness. This can be known, for example Way can be generated by placing in a water bath in which there is a grid 2, drops a drop of collodion and lifts the grille to bring it into contact with the one on top of the Collodion membranes formed on the water surface

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bring. The collodion membrane is brought onto the grid without being completely stretched between the wire mesh. The collodion used contains activating impurities, e.g. B. traces of zinc naphthenate. An aluminum layer 3 is then deposited in a suitable manner, for example by means of vacuum vapor deposition, on the free surface of the collodion membrane and a zinc sulfide layer 4 on the surface of the collodion membrane in contact with the grid 2. The zinc sulfide layer is very loose, as indicated in FIG. 1. In the example described, the layer 3 has a thickness of approximately V20 μ and the layer 4 has a thickness of approximately% μ, with a grid of 20 meshes per millimeter.

Then the whole thing is heated for several hours, for example to about 400 ° C, so that the Collodion is destroyed with the exception of the impurities.

Fig. 2 shows schematically the structure obtained in this way. The intermediate layer 1 actually has no sharply defined boundaries, and the layer thicknesses shown have nothing to do with the actual thicknesses to do. As a result of the activation of the zinc sulfide by the impurities contained in the collodion were, zone 1 forms an imperfect contact area with asymmetrical conductivity between zones 3 and 4. The existence of this imperfect contact lends this remarkable value favorable properties compared to the known storage screens. The afterglow period is with the individual pieces in a production series and even with several production series constant. aside from that higher acceleration voltages than usual can be used. These range from 2500 to 12000VoIt.

Claims (8)

Patent claims: 1. Process for the production of storage screens for cathode ray tubes, in which as A metal wire grid is used as a carrier for the storage layer, characterized in that the metal wire mesh is covered with an organic membrane in a manner known per se, however, the organic substance forming the pellicle with activating impurities is mixed that on the side of the membrane facing the grid an insulating layer is applied, while the metal coating in a known manner on the opposite Side of the cuticle is applied, and that the organic cuticle is then known per se Way is destroyed by heat treatment, however, the impurities the insulating layer partially convert into a semiconducting layer that is in imperfect contact with the metal coating. 2. The method according to claim 1, characterized in that for the formation of the organic membrane Collodion is used. 3. The method according to claim 1 or 2, characterized in that as impurities magnesium, Sulfur, zinc oxide or a soluble zinc salt is used. 4. The method according to claim 3, characterized in that the impurities the Material of the organic membrane can be added in a ratio of about 1: 10Ό0Ο. 5. The method according to claim 1, characterized in that that the metal coating is produced by vacuum evaporation. 6. The method according to claim 1 or 5, characterized in that the metal coating is aluminum is used. 7. The method according to claim 1, characterized in that the insulating layer made of zinc sulfide, Magnesium fluoride or silicon monoxide is formed. 8. The method according to claim 1, characterized in that the heat treatment at 400 ° C is done for several hours. Considered publications:
German Patent No. 893 292;
British Patent No. 661 162. 1 sheet of drawings