JPH09219153A - Applying method of conductive paint in cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a breakdown voltage level in a high voltage conductive area by preventing fall-off of paint on a funnel inside surface. SOLUTION: First conductive paint containing an adhesive material component to enhance an adhesive property with a funnel surface, is applied (P4) to a high voltage conductive area between an anode terminal and a high voltage connector contact point part separate from the anode terminal, and afterward, second conductive paint having resistivity lower than the first conductive paint is applied (P6) to a prescribed area of a funnel inside surface containing the high voltage conductive area.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a cathode ray tube (CR)
T: Cathode-Ray Tube), and more particularly to a method of applying a conductive paint such as carbon slurry to the inner surface of a funnel which is a component of a cathode ray tube.

[0002]

2. Description of the Related Art FIG. 4 is a side sectional view showing a configuration example of a cathode ray tube mounted on a color image receiver or the like. The cathode ray tube 1 shown in FIG. 4 is mainly composed of a glass panel 2 and a funnel 3.
And the sealing edges S of each other.
The E is abutted and integrally joined by a low melting point solder glass or the like. The funnel 3 is divided into a cone portion 4 and a neck portion 5, of which the anode portion (conductive pin) 6 for applying a high voltage is applied to the cone portion 4.
Is provided, and an electron gun 7 which is a source of an electron beam is incorporated in the neck portion 5.

On the other hand, on the inner surface of the panel 2, color phosphors of R (red), G (green) and B (blue) which are the three primary colors of light are regularly arranged, whereby the phosphor screen 8 of a predetermined pattern is formed. Are formed. Further, inside the panel 2, a color selection mechanism is built in which a color selection mask 10 (aperture grill, shadow mask, etc.) is stretched on the front surface of the metal frame 9. The metal frame 9 is mounted inside the panel via spring structure supports 11 fixed to its four sides (or three sides). A high-voltage connector 12 is attached to the metal frame 9, and one end of the high-voltage connector 12 is in contact with the inner surface of the funnel 3 with an appropriate spring property. On the other hand, in the funnel 3, the cone portion 4
A conductive coating 13 for electrically connecting the anode terminal 6 and the high-voltage connector 12 is formed on the inner surface of the. As a result, the high-voltage current applied to the anode terminal 6 flows from the conductive film 13 to the high-voltage connector 12 to the color selection mechanism (9, 11) to the phosphor screen 8. Further, in the neck portion 5 as well, a conductive coating 14 for establishing electrical connection between the anode terminal 6 and the electron gun 7 is formed, whereby a high voltage current applied to the anode terminal 6 passes through the conductive coating 14 to the electron gun 7. Is also flowing.

By the way, as a method for applying the conductive paint (13a, 14a) for forming a film on the inner surface of the funnel 3, mainly a spray method and a brush method are widely known. The spray method sprays conductive paint in the form of a mist from the tip of the nozzle, and in this method, a wide area can be applied in a short time regardless of the shape of the application surface, but applicable paints. It has the drawbacks that the properties of (slurry) are limited and that the coating thickness tends to vary. On the other hand, the brush method applies conductive paint using an applicator attached to the end of the robot arm. In this method, paints of various properties can be applied, but on the other hand, equipment costs are high. It has drawbacks such as complicated equipment, large equipment, long index time, and easy entry of brush streaks.

Therefore, in the prior art, since the coating area is wide and the shape is complicated especially in the cone portion 4 in the funnel 3, the spray method which is overwhelmingly advantageous in terms of cost and the like is adopted, and the neck portion is adopted. For No. 5, a brush method in which the application range of the paint is wide was adopted because the application area is narrow and the shape is simple.

[0006]

However, when the spray method is adopted for the cone portion 4, the coating material applicable to the cone portion 4 is limited to the one having poor adhesion to the funnel surface. In addition, in order to guarantee the withstand voltage level between the anode terminal 6 and the high-voltage connector 12, it is necessary to control the film thickness between them to be a certain level or more. Then, the film thickness of the entire cone portion 4 has to be managed thickly. However, if the paint with poor adhesion is applied thickly, the paint is likely to peel off from the funnel surface. Then, the peeled paint particles cause an electric discharge.

The present invention has been made to solve the above problems, and an object thereof is to prevent the paint from falling off on the inner surface of the funnel and improve the withstand voltage level in the high voltage conductive region. It is an object of the present invention to provide a method for applying a conductive paint in a cathode ray tube capable of achieving the above.

[0008]

A method of applying a conductive coating material for a cathode ray tube according to the present invention comprises applying two kinds of conductive coating materials having different compositions to the inner surface of a funnel of a cathode ray tube having an anode terminal. First, a high-voltage conductive region between the anode terminal and the high-voltage connector contact portion separated from the anode terminal is coated with a first conductive coating material containing an adhesive material component for enhancing the adhesiveness to the funnel surface. To do. After that, a desired conductive coating film is obtained by applying a second conductive paint having a resistivity lower than that of the first conductive paint to a predetermined area on the inner surface of the funnel including the above-mentioned high-voltage conductive area. .

In the above-mentioned method of applying the conductive coating material, first of all, as the first application step, the first step of containing the adhesive material component is performed.
By applying the conductive paint of 1. to the high-voltage conductive region, the adhesion of the conductive paint to the funnel surface is enhanced, and at the same time, the conductivity in the high-voltage conductive region is guaranteed. In the second application step, the second conductive coating material is applied to a predetermined area on the inner surface of the funnel including the high-voltage conductive area, so that the film resistance in the high-voltage conductive area is reduced.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a process flow diagram for explaining a method for applying a conductive coating material according to the present invention, which shows a series of processing procedures in a funnel process. In the present embodiment, the processing procedure in the funnel process will be described according to the process flow chart shown in FIG. 1 while quoting the reference numerals of the respective parts shown in FIG.

First, in the process flow chart shown in FIG. 1, the funnel 3 formed in a predetermined shape in advance is put into the funnel process by a dedicated carrier (process: P1). Next, in order to prevent coating unevenness in the coating process described later, the funnel 3 is cleaned as a pretreatment (P2). In this cleaning process, the cleaning liquid is sprayed onto the inner surface of the funnel to remove impurities such as oil and dust adhering thereto. Further, after spraying the cleaning liquid, rinsing with pure water, draining with air blow, and drying with warm air are performed.

Subsequently, the conductive paint 14a is applied to the neck portion 5 of the funnel 3 (P3). In this application process, an applicator (for example, sponge) attached to the tip of the arm of the robot is impregnated with carbon slurry that is the conductive paint 14a, and the carbon slurry is applied to the neck portion 5 by the movement of the robot arm. The application area in the neck portion 5 is defined from the boundary portion with the cone portion 4 to the insertion end of the electron gun 7, and conduction with the electron gun 7 is achieved by the high pressure spring 7a attached to the gun body. It is designed to be used.

Next, in the cone portion 4 of the funnel 3, as shown in FIG. 2A, in the high voltage conductive region between the anode terminal 6 and the contact portion S of the high voltage connector 12 separated from the anode terminal 6. Then, a conductive paint 15a having the following composition is applied as the first conductive paint. That is,
The conductive paint 15a contains, for example, carbon carbide containing water, water glass (binder), water, and a dispersant, and silicon carbide as an adhesive material component for enhancing the adhesion to the funnel surface (glass surface). ing. By the way, the conductive paint 15a containing the adhesive material component is not suitable for the spray method because it damages the spray nozzle that performs high-pressure injection, and therefore the robot is not suitable for the high-voltage conductive area as in the case of the neck portion 5. The conductive paint 15a was applied by the arm. However, in the case of this coating process, even if the brush method by the robot is adopted, the high-voltage conductive region of the cone portion 4 is small in area and has a simple shape, so that a small and simple robot can sufficiently cope with it. Also, the coating index is extremely short.

In the process flow chart shown in FIG. 1, the cone portion 4 is applied after the application to the neck portion 5, but this order may be reversed, and the conductivity used in both processes may be reversed. When the paints 15a and 14a have the same composition, a common robot can be used.

In this way, the neck portion 5 of the funnel 3 is
After applying the conductive paints 14a and 15a to the cone portion 4 and the cone portion 4, the conductive paint 14 is applied by using a heating lamp or a heater.
a and 15a are dried (P5). As a result, a conductive coating film of the conductive paint 14a is formed on the neck portion 5,
A conductive coating is formed on the cone portion 4 with the conductive coating material 15a. In this case, the high-voltage conductive area of the cone portion 4 (area between the anode terminal 6 and the contact portion S of the high-voltage connector 12)
Since a conductive coating material (carbon slurry) 15a containing silicon carbide is applied to this, a conductive coating film having high adhesive strength to the funnel surface can be formed.

Subsequently, as shown in FIG. 2B, a conductive coating material 15b having the following composition is applied as a second conductive coating material to the entire area of the cone portion 4 including the above-mentioned high-voltage conductive area on the inner surface of the funnel. Yes (P6). That is, the conductive paint 15b is, for example, a carbon slurry composed of carbon, water glass (binder), water, and a dispersant, that is, a carbon slurry that does not contain silicon carbide as the above-mentioned adhesive material component. Here, since silicon carbide functions to increase the resistivity of the coating material (coating) itself, the resistivity of the conductive coating material 15b used in this process is lower than that of the conductive coating material 15a.

Here, in the present embodiment, when the conductive paint 15b is applied, the conductivity in the high-voltage conductive region is sufficiently ensured by the conductive film formed by the conductive paint 15a, so that the quality is improved. The film thickness of the conductive paint 15b is set to be thin within the allowable range. Further, since the conductive coating material 15b does not contain an adhesive material component (silicon carbide) unsuitable for high-pressure injection, the conductive coating material 15b is applied to the cone portion 4 by a spray method.

Then, the conductive paint 15b applied to the cone portion 4 is dried by the same means as the process P5 (S7). As a result, in the high-voltage conductive region of the cone portion 4, a conductive coating film composed of two types of conductive coating materials 15a and 15b having different compositions is formed.

Subsequently, the same conductive coating material 14a as that described above is applied to the neck portion 5 in an overlapping manner (P8). In this coating process, the conductive paint 14a is applied again on the first applied conductive paint 14a to make the film thickness in the neck portion 15 uniform, thereby stabilizing the film resistance and discharging current. The purpose is to strengthen the suppression of.

After that, the conductive paint (14a, 15)
The quality inspection of the funnel 3 that has undergone the coating process of a, 15b) is performed (P9). In this inspection process, for example, as a visual inspection, the conductive paint 14a is not scattered in an unnecessary portion (such as a mounting position of the electron gun 7), or the conductive paint is traced to the coating area defined by the neck portion 5. 14a
Is properly applied, and the seal edge SE of the funnel 3 is inspected for dirt.
If necessary, the conductive paint 15a1 on the cone portion 4
The coating resistance between the anode terminal 6 and the high-voltage connector contact portion 12a is measured in order to grasp and control the coating state of 5b. By the way, the film resistance obtained by this measurement is
Since it depends on the coating state (mainly the coating thickness) of the conductive paints 15a and 15b applied to the cone portion 4, the conductive paint is managed by controlling the film resistance within a certain range. The coating state of 15a and 15b can be managed alternatively.

Next, the seal engine SE of the funnel 3
A frit slurry made of a low melting point solder glass or the like is applied to (P10), and then the frit slurry is dried by a heater or the like (P11). At this time, simultaneously with the drying of the frit slurry, the semi-dry conductive coating material 14a applied in the coating process P8 is also dried. The funnel 3 processed by the above procedure is sent to the next process, and is matched with the panel 2 there.

As described above, in this embodiment, in the coating process: P4, the conductive coating material 15a containing the adhesive material component such as silicon carbide is coated on the high-voltage conductive region of the cone portion 4, and the subsequent coating process: P6. , The conductive coating 15a is applied to the entire area of the cone portion 4 including the high-voltage conductive area.
Since the conductive paint 15b having a resistivity lower than that of the conductive paint 15a, 1a in the high-voltage conductive region is applied.
As the adhesive property of 5b is enhanced, the conductivity in the high-voltage conductive region is surely guaranteed by the conductive paint 15a of the base. Therefore, the coating thickness of the conductive paint 15b on the inner surface of the funnel 3 does not need to be set thicker in consideration of the film thickness variation in the spray method as in the conventional case.

As a combination of the two kinds of conductive paints 15a and 15b applied to the cone portion 4 of the funnel 3, as shown in FIG. 3, both are carbon slurries containing silicon carbide (SiC carbon). When the conductive coating material applied first is a carbon slurry containing silicon carbide (SiC carbon) and the conductive coating material applied thereafter is a carbon slurry without silicon carbide (C carbon), and both are silicon carbide free. There are three possible cases of the carbon slurry (C carbon).

Of these, in the first case (SiC carbon + SiC carbon), the adhesion to the funnel surface is very good, but due to the characteristics of the slurry, the cone portion 4 has a complicated shape and a large area. The efficient spray method cannot be adopted, and the film resistance itself becomes too high. The last case (C carbon + C
In the case of carbon), since the same conductive paint as in the conventional case is simply applied twice, the adhesiveness of the paint to the funnel surface is poor and the paint is easily peeled off. Therefore, as in the case of the present embodiment, a carbon slurry containing silicon carbide (SiC carbon) is applied to the underlayer to enhance adhesion with the funnel surface, and a carbon slurry without silicon carbide (C carbon) is applied to the upper layer. Therefore, it can be said that it is most preferable to reduce the film resistance in the high voltage conductive region.

[0025]

As described above, according to the present invention, in the first coating step, the first conductive layer containing the adhesive material component is formed in the high-voltage conductive region between the anode terminal and the high-voltage connector contact portion. A conductive coating material, and in a second step thereafter, apply a second conductive coating material having a resistivity lower than that of the first conductive coating material to a predetermined area of the inner surface of the funnel including the high voltage conductive area. Therefore, the adhesiveness of the conductive paint in the high-voltage conductive region is improved, and the conductivity in the high-voltage conductive region is surely guaranteed by the conductive paint as the base. This makes it possible to set the coating thickness of the second conductive paint on the inner surface of the funnel to be thin,
It is possible to prevent electric discharge due to peeling of the paint, and significantly improve the withstand voltage level in the high-voltage conductive region. Further, in the second coating step, since the conductive coating material suitable for the spray method can be adopted, it becomes possible to form the conductive coating film excellent in quality and pressure resistance characteristics on the inner surface of the funnel at an extremely low cost.

[Brief description of drawings]

FIG. 1 is a process flow chart for explaining a method for applying a conductive paint according to the present invention.

FIG. 2 is a schematic diagram illustrating a procedure for applying a conductive coating material in a funnel process.

FIG. 3 is a comparative diagram of a combination of conductive paints.

FIG. 4 is a side sectional view showing a configuration example of a cathode ray tube.

[Explanation of symbols]

1 cathode ray tube 3 funnel 4 cone part
5 Neck part 6 Anode terminal 12 High voltage connector S High voltage connector contact part

Claims (3)

[Claims] 1. A method for applying a conductive paint in a cathode ray tube, wherein two kinds of conductive paints having different compositions are applied to an inner surface of a funnel of a cathode ray tube provided with an anode terminal, the anode terminal and the anode terminal. A first coating step of applying a first conductive coating material containing an adhesive material component for enhancing the adhesiveness to the funnel surface to a high voltage conductive region separated from the high voltage connector contact portion. A second applying step of applying a second conductive paint having a resistivity lower than that of the first conductive paint to a predetermined area of the inner surface of the funnel including the high-voltage conductive area. A method for applying a conductive paint to a cathode ray tube. 2. The method of applying a conductive paint in a cathode ray tube according to claim 1, wherein in the first applying step, a conductive paint containing silicon carbide as the adhesive material component is applied. 3. The method of applying a conductive paint in a cathode ray tube according to claim 1, wherein in the second applying step, the second conductive paint is applied by a spray method.