DE1012700B - Process for applying emission-capable layers on carriers for directly or indirectly heated cathodes of electrical discharge vessels - Google Patents

Description

GERMAN

The invention relates to a method for applying thin, emissive layers to substrates for directly or indirectly heated cathodes of electrical discharge vessels.

In the previously used manufacturing process of cathodes is either a coating that can be made emissive on certain Surface parts of a conductor sprayed on, such. B. in the production of indirectly heated Cathodes, or such a coating, is electrophoretically applied to an electrode, e.g. B. a heating wire, deposited, whereupon certain parts of the coating to establish a connection of the Electrode with the contact pins of the vessel can be removed. However, these methods are suitable does not do well using automatic machines nor does it provide electrode covers uniform thickness. When manufacturing coated cathode sleeves, it is common to use the uncoated To put the pods individually in parallel rows in a rack, with the parallel rows Rods is provided. The rods are placed que-r over the sleeves and encompass their ends so that these parts are covered against the subsequent spraying ·. In the case of the electrophoretic Coating, in which a wire is slowly passed through a carbonate mixture, changes the Density of the mixture from time to time so that the layer produced is not uniform. Cathodes were also made by spraying a rigid, smooth surface such as B. glass, with emissive Material, peeling off the film produced from the glass and applying it to a metal body, like a spiral made of tantalum wire. Because of the thickness and rigidity of the glass, however, it is at This method does not allow a compact supply of coating material to be produced is ready for transfer to other surfaces.

These disadvantages are when you leave the Application of thin, emissive layers on supports for directly or indirectly heated cathodes electrical discharge vessels according to the invention avoided in that on the smooth surface a flexible base, the emission material interspersed with binders and plasticizers in this way is applied so that the resulting film is removable from the substrate, and that this emission layer either from the substrate directly or in a state detached from this base is applied to the emission layer carrier.

Figure 1 is a diagram of a strip of coated material, one layer of which is to be coated a cathode sleeve is to be used;

Fig. 2 is a diagram of a with a contact

Method of application
emissive layers on carrier

for directly or indirectly heated
Cathodes of electrical discharge vessels

Applicant:

Sylvania Electric Products Inc.,
New York, NY (V. St. A.)

Representative: Dr. W. Beil, lawyer,
Frankfurt / M.-Höchst, Antoniterstr. 36

Claimed priority:
V. St. v. America August 31, 1964

Donald R. Kerstetter and Ernest S. Wennin,

Emporium, Pa. (V. St. Α.),
have been named as inventors

flag-fitted cathode sleeve to be coated;

Fig. 3 shows a coated strip or a cut piece of the strip and a Cathode sleeve in the position in which the wrapping takes place;

Fig. 4 shows the finished cathode on the carrier, shortly after the layer is around the Has wound cathode;

Figure 5 is a section through the sleeve and backing of the sheet;

Fig. 6 shows the wrapped cathode alone;
Fig. 7 shows the support of the layer alone;

Figures 8 and 9 show the base and the layer used for coating the sleeve beforehand from one another have been separated;

Fig. 10 shows the sleeve lying on the sheet before it is wrapped around the sleeve;

11 shows the application of the method to a thread-like cathode;

Figure 12 shows a finished, coated thread; Fig. 13 shows the coated thread in a bent Form ready for installation in an electronic device.

To explain the implementation of the method, two types of cathodes have been chosen, one indirect heated cathode and a directly heated cathode.

709 588/232

For carrying out the method according to the invention first a flat surface is provided on highly polished thin and made of a may be made flexible metal, gekalandertem paper or other similar material from which a sprayed layer feingepuh ^r ertes material contains, can be easily peeled off, such as by partially curving the backing at the peel line. In a preferred embodiment of the invention and 3-ethyl-propyl acetate, which is known under the name "pentacetate".

After completion of the layer structure, it can be cut into strips, like the one in 1, and then cut into pieces or sheets 16 by slitting the strip at 18 will. The film 12 on the sheet is applied to a cathode portion such as that shown in FIG round cathode sleeve, applied, although also quite

calendered paper is flexible and square or differently shaped sleeves are just as good

Thickness equal to that of ordinary writing paper is used. This can be done in the coated state be of any size and then cut into pieces or leaves. In the drawing is the Backing shown as a strip of calendered paper 10 carrying layer 12. One advantage of this The embodiment is that the coated base is rolled up and stored for later use can be. The layer consists of reversible elements. The sleeve is a component known in electron tube technology and is here as a Nickel tube shown, which has a pressed bead 22 to determine the location of the cathode in a insulating disc and a contact tab 24 for electrical connection of the cathode sleeve with a Has tube terminal. The width of the blade is equal to the circumference of the tubular cathode sleeve or slightly smaller than this, and the length of the

a material capable of emitting electrons, such as the sheet, is dimensioned in such a way that the desired height of the

Carbonates of strontium, barium and calcium, the is held in a binder that contains enough plasticizer to prevent the Allow layer without breaking. The coating can be in the form of a film or strip by spraying the flexible base. The layer material can also be brushed, pressed on, rolled or in any other way applied to the strip, the manufacturers of films Cathode sleeve is covered. The sheet can optionally be made according to the size and shape of a flat cathode surface can be cut as a cathode button in an electron tube.

The application of the film to the emission support can be carried out in the following way: The cathode sleeve 20 is in a solution moistened, which partially dissolves the binder of the coating layer. If the binder is nitrocellulose,

is common. The layer and the base are so 30 can then be used as a solvent "pentacetate" provide that the pad can easily be removed from the. The emission layer support is then on Layer can be peeled off, this being placed as an intact the long center line of the sheet in such a way that Film remains. The best results are obtained with a suitable length of the sleeve on both sides of the coating Using a film with two layers ended part of the sleeve is in place. As well as the different ones Poetry. This is obtained in such a way that the sleeve comes into contact with the film 12, If you first have a carrier as described above, both side parts of the film ends leave the lower part a preparation of the following composition and quickly wrap around the sleeve (cf. coated: 1250 g of a joint precipitation of three Fig. 4). The solvent evidently has such a carbonate, 1.025 1 binder, 0.700 1 solvent, continued, sufficient liquefying effect under the name "pentacetate" the bottom 40 the binder in the film, so that the following

Surface tension causes the wrapping. In the case of a flat surface, the touch causes an at one point between the film and the surface, the entire surface is glued to the film.

specified composition is known.

The dried film is then covered with a second layer of lesser density than the underlying sprayed on layer, the density of the

second film by changing the spray ratios 45 In another embodiment of the method is controlled, as by changing the ratio (see. Figs. 8, 9 and 10) the film 12 is first of from air to mixture. In general, the second has peeled off the pad 10, e.g. B. by means of a Layer, although it has a lower density, the thin blade, with the base 10 so · far same composition as the first layer. is bent back as it is for the relief of the

The three carbonates are preferably required in the following 50 handling, and those with the

Solventized sleeve 20 is placed on top of the film 12, which is then wrapped around the sleeve. In a further embodiment of the invention, the sleeve 20 is opened in the dry state placed the film 12 and placed the liquid solvent on the film immediately next to the sleeve, thereby wrapping the film around the sleeve. The wrapping goes on so quickly that the

added to the ratio:

Barium carbonate .. 57.2 percent by weight 38.8

S trontium - carbonate
Calcium carbonate ..

4.0

The composition of the binder can be one of the following depending on the flexibility desired be the following:

a) 5 g dry ethyl cellulose, viscosity 184 until the eye can hardly follow the process, but it can

20OcP, ethoxy content 48%, dissolved in 100 ecm of a 60 by using a less effective solution

solvent consisting of 53% toluene and 47% ethanol;

b) 5% dry ethyl cellulose, dissolved in 100 ecm a solvent consisting of 80% toluene and 20% ethanol;

c) 3.33 g dry nitrocellulose, dissolved in 100 ecm a solvent consisting of 50% toluene (nitration quality), 25% ethyl acetate and 25% a mixture of N-amyl acetate, 2-methyl-butyl agent or fines less soluble binder can be slowed down.

Another embodiment of the invention is shown in FIGS. Here is a flat band or a strip of heating wire 30 across two separate sheets 32, 34 of film of the above described Composition laid. In this case too, the solvent is applied in such a way that the two leaves are spaced from each other around the

acetate, 3-methyl-butyl acetate, 4-methyl-butyl acetate 70 wrap heating wire tape. The heating tape is then in

The suitable shape shown in Fig. 13 is bent and can be used as a directly heated cathode in an electronic Device can be used. The wire can of course also have a U-shaped cross-section, without changing anything in the way of working.

The advantage of using a flexible base is not just the ability to do this Coated material to be rolled up for storage and the films to be easily peeled off the sheets, but rather also in the fact that the coated roll can be unrolled in automatic machines, the Film is peeled off and fed to a cutter while the backing is bent backwards and fed to a take-up roll.

Claims (4)

PATENT CLAIMS: 1. Process for applying thin emissive layers to supports for direct or indirectly heated cathodes of electrical discharge vessels, characterized in that on the smooth surface of a flexible base interspersed with binders and plasticizers Emission material is applied in such a way that the resulting film from the base is removable, and that this emission layer either directly from the base or in one of this base is applied to the emission layer carrier in the detached state. 2. The method according to claim 1, characterized in that for the adhesion of the emission layer on the carrier this is wetted with a solvent for the binder and brought into contact with the emission layer, so that the Film wraps around the carrier. 3. The method according to claim 1 or 2, characterized in that the emission layer with or without underlays consists of a strip that is cut into pieces that are dimensioned for the respective cathode is divided. 4. The method according to claim 1 to 3, characterized in that a heating wire in the form of a flat strip (30) over two separate sheets (32, 34) of the flexible, the emissive layer load-bearing base is placed, the solvent is brought into action on it and the with the emission layer coated heating wire is bent into a hairpin shape. 1 sheet of drawings © 709 '589/232 7.57