JP2993696B2 - Cathode ray tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides a simple and reliable electrical connection between a transparent conductive film formed on the outer surface of a glass bulb panel and a grounding member for a long period of time. The present invention relates to a cathode ray tube which can be maintained in a state.

2. Description of the Related Art A high anode voltage is applied to a fluorescent surface formed on the inner surface of a panel of a glass bulb of a cathode ray tube. When the anode voltage is applied or the voltage application is interrupted, an electrostatic charge is induced on the outer surface of the panel opposite to the fluorescent screen across the panel glass wall, and the potential becomes high. Normally, glass is a fairly good insulator, so the charge induced as described above does not readily neutralize unless special measures are taken, and remains for a while after induction, and is left to the operator. Problems such as electric shock may occur.

As a countermeasure for such a problem, a transparent conductive film is conventionally formed on the outer surface of the bulb panel, and the transparent conductive film is formed on the outside of the panel skirt of the color cathode ray tube near the fusion portion between the panel and the funnel. It is electrically connected to a tightening reinforcing band for preventing implosion (usually, this band is used as a grounding member with a mounting bracket for mounting a color cathode ray tube to a device to be used), and the outer surface of the panel is charged. The discharged charge is quickly discharged by the grounding member.

A conductive film is formed on the inner and outer surfaces of the funnel of the valve,
A capacitor having a funnel glass wall as a dielectric and a conductive film on the inner and outer surfaces as an electrode is incorporated in a rectifier circuit that generates a high anode voltage, and is used as a smoothing capacitor.
In this case, the exterior conductive film of the funnel is, of course, electrically connected to the ground member on the equipment side of the cathode ray tube for use. Therefore, in the case of a monochromatic display tube or the like in which the panel and the funnel are formed as an integral glass bulb and the reinforcing band is not used, the transparent conductive film on the outer surface of the panel is formed by
It may be connected to the exterior conductive film on the outer surface of the funnel.

[Problems to be Solved by the Invention] The electrical connection between the transparent conductive film formed on the outer surface of the panel of the cathode ray tube as described above and the ground member such as the reinforcing band or the outer conductive film is good for a long time. It is not always easy to work in such a state that it is maintained. Therefore, various methods have been conventionally proposed. For example, JP-A-63-43246 discloses that a transparent or translucent conductive film applied to a panel surface is extended to an outer surface of a panel skirt, and a conductive adhesive tape is wound around the outer periphery thereof. Describes tightening with a reinforcing band. Further, JP-A-63-269438 discloses that a conductive anti-glare film formed on a panel surface is extended to a tightening portion of a reinforcing band of a panel skirt, and the anti-glare film and the reinforcing band It is described that a conductive member such as a conductive tape is interposed therebetween and tightened by a reinforcing band. In either method, when the outside of the panel skirt is tightened with the reinforcing band, the shrink-fitting method is used, and the conductive tape contacts the reinforcing band heated to a high temperature of about 500 ° C and is burned, resulting in electrical connection. Has been difficult to maintain satisfactorily over a long period of time.

The present invention provides a cathode ray tube which does not have the above-described problems and which can maintain an excellent electrical connection between the transparent conductive film formed on the outer surface of the glass panel of the cathode ray tube and the grounding member for a long period of time. The purpose is to provide a tube.

Means for Solving the Problems In order to achieve the above object, in the present invention, the outer surface of a glass bulb panel is covered with a transparent conductive film, and this conductive film is electrically connected to a grounding member. In a cathode ray tube that is used as a base, a conductive metal tape is used as a base material, and one side of the conductive pressure sensitive adhesive tape is impregnated with epoxy resin on the side opposite to the adhesive side. By using a composite tape covered with another tape based on a polyester nonwoven fabric, the electrical connection between the transparent conductive film on the outer surface of the panel and the grounding member is brought into close contact with the adhesive surface of the composite tape on the outside. After coating, the epoxy resin was thermally cured to ensure that the electrical connection between the transparent conductive film and the ground member was maintained.

Specifically, in the case of a color cathode ray tube,
In the case of a monochromatic display tube that does not use a reinforcing band or a reinforcing band that tightens the outer surface of a panel skirt in the vicinity of a fusion portion between a panel and a funnel, it refers to an outer conductive film on the outer surface of the funnel.

[Operation] In the case of the conventional method, the reason for deteriorating the electrical connection state of the connection portion between the transparent conductive film on the outer surface of the panel and the grounding member is that the reinforcing band is tightened by shrink fitting. At this time, the conductive member interposed between the band and the transparent conductive film is burned by the reinforcing band heated to a high temperature. In the present invention, after the reinforcing band tightening work is completed by various methods including shrink fitting, the side where the conductive adhesive tape of the composite tape is exposed is brought into close contact with both the conductive film and the ground member, Since the outside of the place where the transparent conductive film and the grounding member are to be electrically connected is covered with the composite tape, the temperature of the reinforcing band has already been considerably reduced, and the temperature between the transparent conductive film and the grounding member has been reduced. The conductive adhesive tape for ensuring electrical contact can be prevented from being burned out by the reinforcing band. Further, the epoxy resin impregnated in the polyester non-woven fabric on the outer side of the composite tape is heated to be hardened. However, the heating temperature at this time is not a problem because it is extremely lower than the shrink fitting temperature of the reinforcing band. Further, since the nonwoven fabric outside the cured composite tape does not allow the atmosphere to pass through, the metal which is the base material of the conductive adhesive tape is prevented from being oxidized. In addition, it is needless to say that a mechanical protection function is provided. Therefore, according to the present invention, the electrical connection between the transparent conductive film on the outer surface of the glass panel of the cathode ray tube and the grounding member is maintained in a good state for a long period of time. On the other hand, as shown in FIG. 2, the connecting portion between the transparent conductive film on the outer surface of the panel and the grounding member is externally connected only by the conductive adhesive tape without using the composite tape according to the present invention. If covered, there is no danger of the conductive member being burned out by the high-temperature reinforcing band, but during a long period of use, the metal substrate of the conductive tape may be oxidized by the atmosphere or may be damaged by being hit by a hard object. Or the electrical connection state may be degraded.

FIG. 3 is a side view of a general cathode ray tube. In the figure, 1 is a panel of a glass bulb, 2 is a funnel of the bulb, 3 is a reinforcing band, and 3 is an exterior conductive film.

The outer surface of the panel 1 is covered with a transparent conductive film, so-called ITO film or the like. Instead of the ITO film, etc., a mixture of alcoholic silica gel and a surface-curable resin, which is referred to in JP-A-63-269438, was applied by spraying and dried, and had fine irregularities on the surface. Alternatively, a transparent conductive film having both antiglare properties and conductivity may be used. When the panel surface is charged, the voltage of the panel surface may be as high as several tens of kV, but the charge amount is very small, so the surface resistance of the transparent conductive film formed on the panel surface is 10 ⁶ It may be about 10 ¹⁶ Ω. Panel 1
If the transparent conductive film formed on the outer surface of the device is not grounded, when the anode voltage required to operate the cathode ray tube is turned on or off, if a human body, for example, a finger touches the portion, several hundred μA to several hundreds A current of about 10 mA flows instantaneously to the human body. When this current reaches several tens of mA, the finger feels painful. That is, it receives an electric shock. This electric shock can cause even greater secondary disasters. Therefore, the transparent conductive film on the panel surface must be electrically connected to the ground member without fail.
As shown in FIG. 2, the electrical connection portion may be connected to the transparent conductive film 5 on the outer surface of the panel and the reinforcing band 3 without depending on the present invention.
When the outside of the connection portion is covered only with a conductive adhesive tape 6 made of a metal conductor such as copper or iron or aluminum and a powder of a conductive substance is contained in an adhesive, the transparent conductive film 5 The charged electric charge flows to the reinforcing band 3 through the conductive adhesive tape 6 and may show a good conductive state at the beginning of coating, but during a long period of use, the metal substrate may oxidize or the adhesive may become dirty. The adhesive strength is reduced and peeling off, or the object is hit by another object and mechanically damaged, causing the conductivity of the electrical connection to decrease, and finally causing electric shock to the human body due to charging of the panel surface Cannot be prevented.

FIG. 1 is a view showing one embodiment of the present invention. In this embodiment, a polyester non-woven fabric tape 7 impregnated with epoxy resin on the surface of the conductive adhesive tape 6 opposite to the adhesive surface.
The composite tape coated with the above is used, and the adhesive surface of the conductive adhesive tape 6 exposed on one side of the tape is brought into close contact with both the transparent conductive film 5 and the reinforcing band 3 formed on the outer surface of the panel. Cover the outside of the connection. Here, as the conductive adhesive tape 6, a No. 1181 tape manufactured by Sumitomo 3M Limited is used. Spray and apply a mixture of alcoholic silica gel and surface hardening resin to the outer surface of the panel,
A transparent conductive film 5 which has been heated and dried to a temperature of about ° C., has fine irregularities on the surface, and has both antiglare properties and conductivity is formed. When the surface temperature of the panel is cooled to 40 to 60 ° C., as shown in FIG. 1, conductive adhesive tapes 6 are applied to a total of four locations on each of the long axis and the short axis of the display surface. A polyester non-woven tape 7 (No. 10 tape manufactured by Sumitomo 3M Limited) impregnated with an epoxy resin is applied to a simple roller while applying a pressure of 500 to 1000 g. In this case, the epoxy resin and the polyester resin cause a condensation action by heating at 40 to 60 ° C., and when the temperature returns to room temperature, the tape itself is completely cured by the epoxy resin. Therefore, the conductive adhesive tape 6 is completely covered with the nonwoven fabric tape 7, and as described above, there are no problems such as surface oxidation of the conductive adhesive tape 6, deterioration of electric resistance, damage, breakage, etc. The electrical connection between the conductive film 5 and the reinforcing band 3 can be maintained in a good state for a long time. In order to simplify the operation of attaching the nonwoven fabric tape 7 to the conductive adhesive tape 6, a tape in which these are combined in advance may be used. This composite tape is No.H made by Sumitomo 3M
It is called M-1081 tape.

[Effects of the Invention] As described above, according to the present invention, the electrical connection between the transparent conductive film formed on the outer surface of the panel and the grounding member such as the reinforcing band is maintained in a good state for a long period of time. And the reliability of the antistatic effect is improved.

[Brief description of the drawings]

FIG. 1 is a plan view of one embodiment of the present invention, FIG. 2 is a plan view showing a conventional example in which a connection portion between a conductive film and a reinforcing band on a panel surface is covered only with a conductive adhesive tape, and FIG. It is a side view of a general color cathode ray tube. 1 ... panel, 2 ... funnel, 3 ... reinforcement band,
4 ... exterior conductive film, 5 ... transparent conductive film, 6 ... conductive adhesive tape, 7 ... polyester non-woven fabric tape.

Claims (5)

(57) [Claims] 1. A conductive film is formed on an outer surface of a panel, and a panel skirt portion is tightened by a reinforcing band attached by shrink-fitting. The conductive film and the reinforcing band are electrically conductive. A cathode ray tube electrically connected by an adhesive tape, wherein the conductive adhesive tape has an outer surface of a connection portion between the conductive film and the reinforcing band covered with another tape. 2. The cathode ray tube according to claim 1, wherein said another tape entirely covers said conductive adhesive tape. 3. The cathode ray tube according to claim 1, wherein said another tape is a polyester non-woven fabric tape impregnated with an epoxy resin. 4. The cathode ray tube according to claim 1, wherein said another tape is thermoset. 5. A composite tape comprising said conductive pressure-sensitive adhesive tape and said separate tape, wherein said composite tape is made of a conductive metal as a base material, one side of which is made of a conductive pressure-sensitive adhesive and has an opposite side. 2. The cathode ray tube according to claim 1, wherein the side surface is covered with another tape made of a polyester nonwoven fabric impregnated with an epoxy resin.