KR950005810B1 - Crt manufacturing method - Google Patents

Abstract

The method includes the steps of coating a diffused reflection and antistatic composite on the external surface of panel, and heat-treating the coated surface of panel, and heat-treating the coated surface by irradiating microwaves (12) of 0.9-10 GHz from a magnetron (8) onto the coated surface for 0.5-60 minutes in a electromagnetic shielded space by a metal plate (9), thereby forming a coating film on the external surface of panel to reduce the heat-treating time and simplify the heat-treating equipments.

Description

Method of manufacturing cathode ray tube

1 is a schematic view of a cross section of an image display portion of a cathode ray tube, which shows a state before coating the coating composition on the outer surface of the panel and before heat treatment;

2 is a schematic view of the cross section of the image display portion of the cathode ray tube, showing the state after the coating composition is applied to the outer surface of the panel and heat-treated,

3 is a schematic representation of an apparatus for heating a coating material using microwaves in accordance with the method of the present invention,

4 is a graph for illustrating a method of operating a magnetron in an embodiment of the present invention, where y is a voltage application period and x / y is a duty value.

* Explanation of symbols for main parts of the drawings

1: coating material 2: dye

3: panel 4: fluorescent film

5: aluminum deposition film 6: shadow mask

7: metal barrier 8: magnetron portion

9: metal plate 10: cathode ray tube support

11: air 12: microwave

13 exhaust port 14 gas capillary tube

The present invention relates to a method for manufacturing a cathode ray tube, and more particularly, to improve display quality by improving a heat treatment method after coating treatment performed on an outer surface of a panel for antistatic, anti-glare and / or color enhancement. It relates to a method for producing a tube.

In general, since the outer surface of the panel is a smooth glass surface, external light is reflected, and thus, the sharpness of an image such as a character or a figure appearing on the screen is difficult to see. To solve this problem, external light is diffusely reflected for proper processing such as forming an uneven pattern on the outer surface of the image portion of the apparatus. In addition, electrostatic charges are accumulated on the outer surface of the panel during or after the operation of the cathode ray tube, which causes dust to sit on the outer surface of the panel, and causes problems such as electric shock when a person contacts it. To solve this problem, a method of absorbing moisture in the air by using a silanol group and reducing the surface resistance of the outer surface of the panel by the moisture, and coating the outer surface of the panel with a liquid in which ultrafine metal or conductive oxide is dispersed This is called antistatic film.

The diffuse reflection of the external light is usually coated with a SiO ₂ material, and for the antistatic, a conductive transparent film, that is, a metal material such as SnO ² is coated. In recent years, a color layer is further included to improve the color. Doing.

In order to form the coating film, a sol-gel method using an alkoxide-based composition is used, and a spin coating method or a spray coating method is used as a coating method. During coating, the alkoxide hydrolysis reaction occurs in the coating material, so the initial coating material on the outer surface of the panel includes an inorganic polymer and water or alcohol-based organic material. In order to obtain a desired coating film component and to evaporate water or alcohol-based organic material, heat treatment is performed. The process is essential. This heat treatment step usually passes a cathode ray tube coated with a coating composition through a heating furnace which is heated by resistance heating by an electric heater or a heat source by a burner, and the entire cathode ray tube is passed through a predetermined temperature (usually 200 to 200). 300 ° C.). By heating, the alkoxide is decomposed to become an oxide, and the remaining water or organic matter is evaporated, leaving only the comb film forming component on the outer surface of the panel.

When the basic process of the sol-gel method commonly used is expressed by the chemical formula is as follows.

[Hydrolysis reaction]

M (OR) _Z + H ₂ O → M (OR) _Z-1 OH + ROH

[Condensation reaction]

M (OR) _Z-1 OH + M (OR) _Z → (RO) _Z-1 MOM (OR) _Z-1 + H ₂ O

2M (OR) _Z-1 OH-(RO) _Z-1 M -OM (OR) _Z-1 + H ₂ O

(Wherein M (OR) _Z is a metal alkoxide, R is an alkyl group (C _n H _{2n + 1} ) and M is a metal. See CJ Brnker et al., Thin Solid Films, 20, 97-108, (1991). )

In the above formula, the material hardened before the heat treatment is a mixture of (RO) _Z-1 MOM (OR0) _Z-1 , ROH, and H ₂ O, and ROH and H ₂ O are evaporated by a heating process and (RO) _Z -MOM (OR) _Z-1 decomposes to become an oxide of the MOM phase.

By the way, the coating film obtained through the heating process is not completely obtained as M-0-M phase of the coating material is crystallized according to the above mechanism, and most of the coating film is obtained in an amorphous state. Hardness and conductivity are inferior in comparison. In order to solve this problem, when the heating temperature is increased, gas is released from inside the cathode ray tube, and the problem of vacuum degree decreases or glass breakage due to stress is more seriously accompanied. It is not preferable because the salt is decomposed or the effect is lowered under the conditions. In view of such conflicting conditions, industrially, the heating temperature range of 200 to 300 ° C. is adopted as an appropriate line.

However, even in the above temperature range, the vacuum degree in the cathode ray tube is still lowered due to the release of adsorption gas, thereby deteriorating the characteristics of the electron emission system and the electron gun. This is a problem that remains even though the exhaust process is carried out with heating, since a small amount of residual adsorption gas components are re-emitted in the heat treatment process of the coating material, which is a factor that lowers the quality of the cathode ray tube as a whole. Moreover, there also exists a problem that breakage of glass arises by the soft stress difference by heating. Moreover, not only a suitable heating furnace is required for continuous production under thermal conditions, but also it takes 3 to 4 hours to heat up slowly to prevent breakage or to cool down slowly after heat treatment, which is a major obstacle to mass production. It becomes a huge energy loss and requires a new treatment method.

On the other hand, the microwave (wave) is an electromagnetic wave (electromagnetlc wave) having a frequency range of 0.3 to 300GHz, a wavelength of 1mm to 1m, and has a characteristic that the degree of transmission, absorption or reflection occurs depending on the type of material and temperature . Microwave heating is widely used as a food cooking means, and industrially, it has been tried as a drying and sintering method in the field of ceramics, and is in a state of practical use. The correlations associated with the properties of materials in these microwave heating methods are different for different researchers, but they are all homomorphic and depend on the material's relative dielectric constant, dielectric loss (tan∂ or loss tangent), and frequency (or wavelength). Related. Representative relations are as follows.

P = σ | E | ² = 2πfε ₀ ε _{r '} tanδ ｜ E ｜ ²

Where P is the microwave power absorbed per unit volume (W / ㎡), σ is the total effective conductivity (s / m), E is the magnitude of the internal electric field (V / m), f is frequency (GHz), and ε ₀ vacuum Permittivity at, ε _r 'is the relative dielectric constant and tanδ is the loss tangent)

In the above formula, f, ε _{r '} , tanδ and E are interdependent, and E is difficult to apply because it changes according to the size, shape, and sample position of the material, but the correlation between absorption power and dielectric and microwave characteristics of the material The meaning is unknown. In addition, the electric field is absorbed and attenuated by the material while microwaves penetrate and propagate in the material. As a parameter representing this phenomenon, the penetration distance D is a depth at which the power of the microwave penetrating the material is reduced in half and is expressed by the following equation.

(Λ ₀ represents the wavelength in free space)

The object of the present invention is that the liquid coating material is applied to the panel outer surface of the cathode ray tube as described above, followed by a heat treatment, and a trace amount of the residual adsorption gas component is re-released in the heat treatment process of the coating material, so that the cathode ray tube The purpose of the present invention is to solve the problem of lowering the degree of vacuum and deteriorating characteristics of the electron emission system and the electron gun, and to provide a method of manufacturing a cathode ray tube having improved quality by using the microwaves for heat treatment of a coating material.

In the present invention in order to achieve the above object, in the method for manufacturing a cathode ray tube comprising a step of coating a diffused reflection and antistatic coating composition of the external light on the outer surface of the cathode ray tube, the heat treatment to produce a coating film, the heat treatment The process is carried out by irradiating microwaves by the operation of a magnetron to the outer surface of the panel coated with the coating composition of the cathode ray tube in a space electromagnetically shielded by a metal plate. do.

In particular, the frequency of the microwave is preferably from 0.9 to 10GHz, the voltage application period of the magnetron for generating the microwave is preferably 0.1 to 30 seconds, the duty value is 0.1 to 0.5.

In addition, the coating composition for diffuse reflection and / or antistatic of the external light may further include a dye for improving the color of the cathode ray tube.

By utilizing the correlation between the characteristics of the microwave and the material, the present inventors measured the dielectric properties of the cathode ray tube image display material. Depending on the components contained, the dielectric properties of the coating material are about 4 to 10 times larger (the relative dielectric constant of the panel: 10-20, the dielectric constant of the coating material: 80-100), and the microwave can be selectively heated. It has been conceived that heat treatment of the coating material is possible. That is, conventionally, the entire cathode ray tube is heated because the cathode ray tube is passed through a heating furnace to heat and dry the coating material. However, according to the method of the present invention, only the coating material on the upper part of the panel which needs heat treatment can be selectively heated. It is possible to save time and energy while achieving excellent heating effect.

1 and 2 are schematic diagrams of the cross section of the image display portion of the cathode ray tube, which are applied to the outer surface of the panel according to a conventional method before the heat treatment (FIG. 1) and after the heat treatment (FIG. 2). Show the appearance. As shown in FIG. 1 and FIG. 2, the cathode ray tube generally includes an aluminum vapor deposition film 5 spaced at a predetermined interval on the surface of the shadow mask 6 side of the fluorescent film 4 in order to increase luminance outside the fluorescent film 4. It is provided to induce light reflection.

Here, when the coating composition is applied to the outer surface of the panel and then irradiated with microwaves for heat treatment of the coating material (1), depending on the wavelength, intensity and application method of the microwave, in some cases the aluminum deposition film (5) dropping out With the development, cracking of the fluorescent film 4 occurs, and in the case of treatment for a long time, not only the coating material but also the temperature of the panel 3 may increase, and the coating material is locally heated according to the microwave irradiation method, and thus the panel 3 Accompanied by glass breakage of) may occur.

3 is a schematic view showing the cathode ray tube panel outer surface heating apparatus of the present invention, wherein the microwaves 12 are irradiated from the magnetron portion 8 on the upper portion of the panel 3. The lower portion of the cathode ray tube, except for the panel portion, is covered by a metal plate 9, and an exhaust port 13 is provided for gas exhaust inside the chamber. The exhaust port 13 is provided with a capillary tube 14 for gas collection to determine the process time, the gas collected through this is analyzed by a quadrupole mass spectrometer. The process was terminated at the point where almost no organic matter and moisture was detected in the gas. According to the method of the present invention, it was found that it takes from about 1 minute to about 60 minutes.

Hereinafter, embodiments of the present invention and the results will be described. Coating materials and process conditions are shown in Table 1 and the results are shown in Table 2.

TABLE 1

TABLE 2

In the application method of the coating liquid, the raw material composition was mixed and coated in the same manner as in the prior art, or each raw material composition solution was applied, and the heat treatment was repeatedly applied. Depending on the type of the liquid, the difference in properties is small in the method of the present invention. Did not do it.

The process time was determined by the tendency to detect the gas or moisture of the organic component evaporated from the coating material of the panel, and after a few seconds to several tens of seconds depending on the conditions to provide a heat treatment effect even after the organic gas or moisture is rapidly reduced. In the condition that the damage of the fluorescent film is suspected, only the panel part was carried out for the observation of the film on the back side after the process. In some processes, heat treatment was performed by arbitrarily setting a time regardless of the gas release characteristics to observe the temperature rise of the panel surface and whether the panel was cracked. In this case, a symbol (*) is indicated beside the number of the embodiment.

The temperature of the panel surface and the heat treatment effect of the coated area are theoretically difficult to be combined. However, as a result of the comparison, the temperature of the panel surface is not very high due to the difference in dielectric properties and heat capacity of the panel and the coating layer (about 25-105 ° C). In fact, the heating temperature effect of the actual coating layer is expected to reach several hundred degrees. In this example, the temperature of the coating layer and the panel temperature were not measured separately. As in the present embodiment, the heat treatment effect after coating shows the same or more characteristics as the conventional case where the ordinary heating temperature is several hundred degrees, but the increase in the temperature of the panel portion is suppressed as described above, because of the difference in dielectric properties of each material. The negative temperature rise is large, but it is thought that the temperature of each part is canceled by the difference in the density capacity due to this size difference, so that the temperature rise of the entire closed board is suppressed.

The indications of the effects shown in Table 2 are compared with the general characteristics of the cathode ray tube obtained by heating to a temperature of 200 ° C. according to a conventional method; Excellent, ○; Similar, Δ; Somewhat problematic and ×; It is marked as bad, which is devised by the present inventors arbitrarily.

As shown in the results of Table 2, at the same output, the lower the frequency of the irradiated microwave, the greater the effect of the fluorescent film or the temperature rise of the panel glass, and the higher the frequency, the better the heat treatment effect, but the process time was too short and difficult to control. .

In the case of continuously irradiating the microwaves as shown in the present embodiment, the panel temperature is too fast to rise, which may cause the panel to break, and due to stress differences with the cathode ray tube funnel, cracks may occur in the panel side part. There was a case. It was found that by intermittently irradiating the microwaves rather than continuously irradiating it, an excessively fast temperature rise can be suppressed and a homogeneous characteristic can be obtained.

4 is a graph showing a method of operating a magnetron in an embodiment of the present invention. In the graph, y means voltage application period and x / y means duty, and the voltage application period is preferably about 1 to 30 seconds depending on the frequency of microwaves. When the duty is 0.1 to 0.5, excellent film characteristics (adhesiveness, charge decay rate, color sense) , Anti-glare, etc.) was obtained.

As described above, according to the cathode ray tube manufacturing method of the present invention, the time required for the heat treatment process after application of the coating liquid is reduced to within several minutes to several tens of minutes in the existing 3-4 hours, and is equivalent to or better than the coating film obtained according to the conventional method. A coating film having characteristics can be obtained.

In addition, in terms of equipment, the investment cost is large because a large-scale heating furnace is required in the conventional method, but according to the present invention, the required equipment is simplified with a simple metal structure, a microwave generator, etc. In addition to savings, it is possible to obtain an effect of producing a coating film having excellent characteristics.

Claims (5)

In the method of manufacturing a cathode ray tube comprising the step of coating the diffuse reflection and antistatic coating composition of the outer pores on the surface of the panel of the cathode ray tube, and then heat-treating it to prepare a coating film, the heat treatment heat treatment step is electromagnetic shielding by metal panes Method of manufacturing a cathode ray tube, characterized in that carried out by irradiating microwaves by the operation of the magnetron on the outer surface of the panel coated with the coating composition of the cathode ray tube in the space. The method of manufacturing a cathode ray tube according to claim 1, wherein the microwave has a frequency of 0.9 to 10 GHz. The method of manufacturing a cathode ray tube according to claim 1, wherein a voltage application period of the magnetron for generating microwaves is 0.1 to 30 seconds, and a duty value is 0.1 to 0.5. The method of manufacturing a cathode ray tube according to claim 1, wherein the microwave irradiation time is 0.5 to 60 minutes. The method of claim 1, wherein the coating composition further comprises a dye.