JPS599830A - Formation process for external conductive film of cathode-ray tube - Google Patents

Abstract

PURPOSE:To offer a formation process for the external conductive film of a chathode-ray tube which is suitable for mass production, by forming a graphite layer by means of a printing process on an adhesive film which contracts when hardened, then by sticking the graphite layer cut and formed in desired shape to the desired position of the external surface of the cathode-ray tube. CONSTITUTION:A graphite layer is formed by means of a printing process, for instance, on a polyvinyl acetate film whose material is selected from adhesives which contract when hardened; thereafter, the graphite layer of desired shape which is made, for instance, by punching it with a press is heated in the state in contact with the desired external position of a cathode-ray tube 1. After that, said layer is returned back to an ordinary temperature and a conductive film 2 composed of said graphite layer is stuck thereon. The graphite layer having a constant thickness and shape can be easily formed on the film by means of the printing process. When the film contracts during hardening process, said graphite film which was a plane at first is tightly stuck onto the usually curved external surface of the cathode-ray tube without generating creases nor wrinkles.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a conductive film on the outside of a cathode ray tube, which is suitable for mass production.

Conventionally, a suspension of graphite such as polyvinyl acetate (7) was sprayed onto the outside surface of a cathode ray tube using a spray gun. In areas where a film should not be formed (e.g. around the anode terminal), the cover was sprayed with the cover closed, but the graphite liquid may get around the cut in the cover, or the cover may be attached or removed.
There were various problems, such as the need to remove graphite from the cover.

An object of the present invention is to provide a method for forming a conductive film on the outside of a cathode ray tube, which is free from the above-mentioned problems and is suitable for mass production.

In order to achieve the above object, in the present invention, a graphite layer is formed by a printing method on a film of an adhesive, such as polyvinyl acetate, which shrinks when cured, and then a desired shape K, for example, is punched out with a press, is formed on the outside of the cathode ray tube. After heating (in the case of polyvinyl acetate, it may be exposed to hot air) while in contact with a desired portion of the graphite layer, the conductive film made of the graphite layer was returned to room temperature and heated to adhere the conductive film made of the graphite layer. According to the printing method, a graphite layer having a constant thickness and shape can be formed on the film. Furthermore, when the film shrinks during curing, the graphite film, which was initially flat, is tightly adhered to the generally curved outer surface of the cathode ray tube without wrinkles or the like. (If a thin metal foil or the like is used as the conductive film, wrinkles will inevitably occur.) Figure 1 shows the graphite layer formed on the adhesive film.
A punched conductive film 2 having a desired shape is shown. Currently, adhesives processed into films of a predetermined thickness are easily available. FIG. 2 shows a state in which the conductive film 2 made of the graphite layer is adhered to a desired position on the outer surface of the cathode ray tube 1. As shown in FIG.

In this way, the insulation defects that tend to occur around the anode terminal and other areas due to the graphite liquid flowing around in the conventional tin ray gun coating method can be completely eliminated.

As explained above, the present invention requires complicated operations such as attaching and detaching the cover and cleaning the cover with graphite adhering to it, and is prone to insulation failure accidents. All processes are suitable for mass production, greatly improving productivity.

[Brief explanation of the drawings] Fig. 1 shows a conductive film formed by forming a graphite layer on an adhesive film and punching it into a desired shape, and Fig. 2 shows a state in which the conductive film is adhered to the outside of a cathode ray tube. FIG. 1... Braun tube, 2... Conductive film. Agent Patent Attorney Usui 1) Li, Happiness. , ・ ´vo. , 1 li' = (-J"

Claims (1)

[Claims] 1. A graphite layer is formed by a printing method on an adhesive film that shrinks when cured, and then cut and molded into a desired shape. A method for forming a conductive film on the outside of a cathode ray tube, which comprises heating and then returning to room temperature to adhere a conductive film made of the graphite layer to a desired portion of the outer surface of the cathode ray tube. 2. The method for forming an external conductive film on a cathode ray tube according to claim 1, wherein polyvinyl acetate is used as the adhesive that shrinks during curing, and the method is heated with hot air.