KR100205138B1 - Cathode-ray tube - Google Patents

Abstract

In order to reduce the doming phenomenon, when the screen of the shadow mask electron gun surface is coated with a material that is expected to have a dominant reduction effect, the binder is coated in the shadow mask printing paste composition to form a uniform coating surface. It effectively suppresses the domming phenomenon, which is the thermal deformation caused by the electron beam collision, and has the effect of low thermal expansion, electron reflection and thermal radiation, and the process is simple and easy to work, which can substantially solve the problems caused by the conventional spray method. Will be.

Description

Paste composition for color-brown tube shadow mask printing

[Industrial use]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paste composition for printing a color brown tube shadow mask, and more particularly, a doming phenomenon by using a binder as a curable resin in a paste composition for coating the surface of the shadow mask electron gun using a screen printer method. The present invention relates to a paste composition for printing a color brown tube shadow mask, which has been removed to improve color purity and quality of the color brown tube.

[Prior art]

In general, a color picture tube (CPT) is composed of a bulb composed of a panel, a funnel, and a neck. An electron gun is installed in the neck, and a red, green, and blue fluorescent film is coated on the inner surface of the panel, and a shadow mask having a color screening function is disposed at a distance from the fluorescent film. The shadow mask is assigned to land three electron beams emitted from the electron gun to the red, green and blue fluorescent films applied to the inner surface of the panel. The shadow mask having an aperture 35 through which the electron beam passes is bounded by a frame 17, which is interposed inside the panel via a bimetal contact spring 19. It is installed. The shadow mask installed inside the color-brown tube is made of pure iron A-K (Aluminum-Killed) steel, which has a coefficient of thermal expansion of about 11.7 × 10 ^-6 / K. When the color brown tube is operated, the electron source of the electron beam generated by the electron gun 27 of FIG. 1 passes through the aperture 35 of the shadow mask toward the panel in front of the screen and lands on the fluorescent film to obtain a desired image. However, during operation of a color-brown tube with a shadow mask, only a small part of the electron beam passes through the hole of the shadow mask and about 80% of the electrons are blocked by the shadow mask installed at the front of the panel on the way to the panel. Therefore, since most of the kinetic energy of the electrons collided with the shadow mask is converted into thermal energy, the temperature of the shadow mask itself is increased to about 80 to 90 ° C. As a result, by inducing thermal expansion in the shadow mask 13 is transformed into the expanded shadow mask 15 as shown in Figure 1, this phenomenon is called doming (doming). Moreover, when a large amount of electrons collide locally with the shadow mask, the temperature compensation on the shadow mask surface is not performed fast enough, so that the shadow mask is locally localized. Due to the dominant phenomenon, the path 23 of the electron beam is changed as the position of the hole is changed to H2 through the hole H1, which is each hole on the shadow mask. At this time, P1, which is the fluorescent screen pixel of the panel, emits light by the initial electron beam path, but the light emitting position is changed by moving to P2 due to the above result. This phenomenon occurs more at the periphery than at the center of the screen. As the color CRT becomes large and flat, the color purity of the screen is deteriorated, and the larger the coefficient of thermal expansion of the shadow mask is, the more remarkable. This deteriorates the color purity of the color CRT and, as a result, causes the quality to deteriorate.

The technical methods for reducing the above dominant phenomenon are as follows.

First, in order to prevent heat from being transferred to the shadow mask, a method of coating an insulating film on the surface of the shadow mask is used. The surface of the shadow mask is coated with a thermal insulating material having excellent thermal insulation to prevent the heat transferred by the beam to the shadow mask. The coating is mainly performed using a ceramic-based material having a low thermal expansion rate.

Second, a material having a low coefficient of thermal expansion is coated on the shadow mask surface. It is a method of forming a low thermal expansion layer by applying a lead borate and a ceramic having a small thermal expansion mule on the surface of the shadow mask, followed by high temperature heat treatment.

Third, shadow masks formed of invar material of Fe-Ni alloy having a thermal expansion coefficient of 1/10 of AK steel are described in US Pat. No. 4,665,338 and US Pat. No. 4,420,366. Since the price is very high, there is a problem of raising the manufacturing cost of the product.

Fourth, the heat radiation rate of the shadow mask is increased. It is a method of increasing the emissivity by coating a material on the shadow mask surface or blackening the material having excellent thermal radiation coefficient such as carbon, manganese (Mn), manganese oxide, aluminum oxide, black pigment.

Fifth, there is a method to reduce the doming phenomenon by adding a separate film on the shadow mask surface. This method is to coat electron reflecting material, and it is heated by beam by applying electron reflection film with heavy metals such as lead (Pb), bismuth (Bi), tungsten (W) on the side of electron gun of shadow mask as aqueous suspension. As a result, US Patent No. 4,442,376 and Korean Patent Publication No. 85-1589 are proposed by N. V. Philips, and a method of forming an electron reflection film by spray method and European Patent No. 139,379 propose a method of forming a low thermal expansion layer. It is. However, the above-described methods have a problem in that it is difficult to apply them to actual products because the film forming operation is technically difficult. Moreover, although each shadow mask including the above-mentioned films slightly reduces the doming phenomenon, the effect is negligible.

On the other hand, as a practical method for coating a material corresponding to the desired effect of the above-described method on the shadow mask surface is often used a spray (spray) method. In this case, the solution is mostly prepared with an aqueous suspension and sprayed onto the shadow mask surface through a nozzle. In addition, in order to spray, the above materials must be made of an aqueous suspension or the like, and therefore, these materials must be manufactured so as to conform to the spray method. However, this process often blocks some holes in the shadow mask surface even if the spray method is finely controlled, and the coating surface is not uniform. If even one hole of the mask is blocked, the product is treated as a defect, which is a very serious problem.

As another method of coating, a deposition method using a target material as a source and a shadow mask as a target may be used. This method has a thin coating layer and increases the price due to deposition equipment. There is a disadvantage.

On the other hand, the method of coating by the screen printing method has already been filed in Korea Patent Application No. 95-40315, and the basic method for the paste manufacturing material has been filed in the Republic of Korea Patent Application No. 96-3360. Korean Patent Application No. 96-3360 discloses a dry state in a heat-drying furnace at about 150 ° C. In this case, a large amount of heat is consumed and the solvents in the wet components evaporate into the air, which adversely affects the surrounding environment.

The present invention has been made to solve the above problems of the prior art, an object of the present invention is to uniformly when coating a screen printing method on the surface of the shadow mask electron gun side expected to reduce the dominant phenomenon to reduce the dominant phenomenon The present invention relates to a color CRT shadow mask printing paste composition which can be easily carried out to form one coating surface, and also has a low heat consumption, prevents solvents from evaporating into the air, and is inexpensive.

1 is an explanatory diagram schematically showing a dominant phenomenon of a color brown tube.

2 is a cross-sectional view showing a coated cross section of the electron gun side in the shadow mask surface of the color-brown tube.

Figure 3 is a plan view of the screen of the color-brown tube according to an embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings *

11 Fluorescent surface of the panel 13 Mask shape before doming

15 Mask Shape after Doming 17 Frames

19 Support Spring 21 Electron Beam Path Before Doming

23 Electron Beam Path after Doming 25 Centerline 27 Electron Source

31 Coating layer 33 No study 35 Aperture

S screen C, D measuring point

[Means for solving the problem]

The present invention has the following configuration to achieve the above object of the present invention.

In the present invention, in a shadow mask printing paste composition comprising frit, powder and a binder, the binder provides a shadow mask printing paste composition which is an ultraviolet curable resin.

It is preferable that the said frit is 0.7-10 weight%, the powder is 60-87 weight%, the binder is 12-32 weight%, and ultraviolet curable resin is 230 nm-400 nm in an ultraviolet absorption wavelength range.

In addition, in the present invention, after forming a photoresist on the screen mesh fixed to the frame and applying a paste composition to the screen mesh and placing a shadow mask made of AK steel under the screen mesh, the coating layer 31 is applied. In the manufacturing method of the shadow mask for color-brown tubes including the printing process to form and the forming process which presses the said shadow mask, and forms a skirt part and a bead, The said paste composition is 0.7-10 weight% frit and 60-87 Provided are a method for producing a shadow mask for a color brown tube, comprising a weight% powder and a 12 to 32 weight% UV curable resin binder.

The powder is preferably selected from the group consisting of bismuth, bismuth oxide, tungsten, tungsten oxide, carbon, manganese, manganese oxide, black pigment and aluminum oxide.

The paste composition is preferably 0.7-10 wt% of the frit and 60-99.9 wt% of the composition of the powder in the final composition after blackening.

The paste composition basically includes frit powder which melts in the shadow mask blackening process of the CRT manufacturing process and a vehicle which has a constant viscosity and viscosity, and when it is desired to reduce dominance through an electron reflection effect. When heavy metal powders such as bismuth and tungsten are mixed and the effect of thermal emissivity is expected, powders having a large thermal radiation coefficient such as carbon, manganese, manganese oxide, aluminum oxide or black pigment are mixed. To achieve the effect, paste is prepared by mixing only frit powder itself.

The binder serves to control the viscosity and viscosity of the paste or to combine the powder to enable smooth printing. Only the ultraviolet curable resin can be used alone, and if necessary, some solvent such as butyl carbitol is mixed. It can also be used.

The binder completes its function by being completely volatilized and ashed in the blackening process in the range of 250 to 600 ° C.

The powder is a material which is expected to be dommed. For example, when it is desired to expect at least one of the electron reflection effect and the thermal radiation effect, a powder such as bismuth, bismuth oxide, tungsten, or tungsten oxide is used. If desired, heavy metals with an atomic number of 70 or more are used. For the thermal radiation effect only, carbon, manganese and manganese oxides, black pigments, aluminum oxides and the like are used.

The frit is completely vitrified in the blackening process performed at a temperature of 250 to 600 ° C. after printing on the shadow mask, thereby bonding the powders together so that they are not scattered, and furthermore, firmly attaching them on the shadow mask. Do it.

In addition, in one embodiment of the present invention, the binder is a material that gives the paste viscosity and viscosity to enable printing and allows the remaining powder components to adhere firmly to the shadowmask surface until blackening. They then complete their function by completely quenching in the blackening process, which is part of the CRT manufacturing process.

The film state after screen printing according to the present invention is a moist state, and the Korean Patent Application No. 96-3360, which has been previously filed, is dried through a heat-drying furnace at about 150 ° C., in which case a large amount of heat is consumed and a moist component. Heavy solvents evaporate into the air, which adversely affects the surrounding environment. However, since the binder used in the present invention is a method of curing by irradiating ultraviolet light, it can be cured very quickly without evaporation of the solvent depending on the degree of ultraviolet irradiation. In order to smoothly apply the present invention, a device capable of irradiating ultraviolet rays to a printed shadow mask surface is required, but a conventional heat drying apparatus is not required.

The following presents a preferred embodiment to aid the understanding of the present invention. However, the following examples are merely provided to more easily understand the present invention, and the present invention is not limited to the following examples.

EXAMPLE

Representative Example

BEST MODE Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

2 shows a cutaway cross-sectional view of a portion of the shadow mask. The upper surface of Figure 2 means the shadow mask portion of the side on which the electron gun is mounted. The shadow mask has a plurality of apertures 35 formed to allow electron beams to pass through, and a void 33 formed between these apertures 35. The shadow mask body is made of AK steel and a coating layer 31 having a predetermined thickness is formed on one surface on which the electron beam is incident from the shadow mask.

The screen printing process for manufacturing the shadow mask is as follows.

A screening process is performed to form a photoresist on the screen mesh. In this process, a screen mesh made of stainless steel, polyester or nylon is mounted on a frame and the entire surface of the screen mesh is mounted. After the photoresist is applied, the photoresist is dried, exposed through a shadow mask, and then etched and dried again to form a photoresist at a portion corresponding to the aperture 35 of the shadow mask.

The screen mesh formed as described above is mounted on a screen printing machine, and the paste composition is uniformly applied on the upper side of the screen mesh. Subsequently, a flat shadow mask is disposed below the screen mesh and the paste is moved in one direction while being pressed with a squeegee to print the coating layer 31 on the non-perforated portion 33 of the shadow mask.

The flat shadow mask in which the printing process is completed forms the skirt portion and the beads in the shadow mask through the forming process again.

Example 1

Manufacture paste composition for shadow mask printing

Paste 9.4 wt% frit, 25 wt% UV curable resin as a binder, and 65.6 wt% bismuth oxide were pasted to prepare a paste composition for shadow mask printing.

Shadow Mask Manufacturing

A screen mesh made of stainless steel, polyester, or nylon is mounted on the frame, and photoresist is applied to the entire surface of the screen mesh, followed by drying to form a photoresist on the screen mesh. The photoresist was formed at the portion corresponding to the aperture 35 of the shadow mask by exposing through light, etching and drying it. The screen mesh formed as described above is mounted on a screen printing machine, and the paste composition is uniformly applied on the upper side of the screen mesh. A flat shadow mask was disposed below the screen mesh and the paste was moved in one direction while pressing the paste with a squeegee to print the coating layer 31 on the non-perforated part 33 of the shadow mask. The flat shadow mask in which the printing process is completed is wet. Irradiated and cured by ultraviolet rays 230 mm to 400 mm for about 5 minutes, the skirt portion and the beads are formed on the shadow mask through the forming process.

Comparative example

The same procedure as in the above example was performed except that 23 wt% of a vehicle in which ethyl cellulose and butyl carbitol were mixed as a binder material, 51.4 wt% of bismuth oxide, and 25.6 wt% of frit were used as the paste composition. To produce a shadow mask.

The UV curable resin according to the present invention was pasted into bismuth oxide (Bi ₂ O ₃ ) powder and frit, and then applied to a 25 "AK shadow mask by screen printing. Doming reductions measured at measuring point C and measuring point D at (L1 = L / 3) were compared with before application.

Doming Reduction (μm) Example 35 to 45 Comparative example 40-50

The color-brown tube shadow mask fabricated using the shadow mask printing paste composition according to the present invention not only effectively suppresses the dominant phenomenon, which is thermal deformation due to electron beam collision, but also the drying rate of curing is very fast by using the ultraviolet curable resin in the binder, Compared with the paste containing the conventional solvents, there is no need for a heat drying apparatus to remove it, and these solvents are evaporated to the surroundings, eliminating the factors causing environmental pollution.

Claims (5)

Frit; Powder; A binder; A paste composition for shadow mask printing, wherein the binder is an ultraviolet curable resin. The paste composition of claim 1, wherein the frit is 0.7 to 10 wt%, the powder is 60 to 87 wt%, and the binder is 12 to 32 wt% as an ultraviolet curable resin. A plate making step of forming a photoresist on the screen mesh fixed to the frame; Applying a paste composition to the screen mesh; A printing process of forming a coating layer after arranging a shadow mask made of AK steel under the screen mesh; Forming the skirt portion and the beads by pressing the shadow mask; In the method for producing a shadow mask for color brown tube containing, the paste composition comprises a shadow for color brown tube containing 0.7 to 10% by weight of frit, 60 to 87% by weight of powder and 12 to 32% by weight of UV-curable resin binder Method of manufacturing a mask. The method of claim 3, wherein the powder is selected from the group consisting of bismuth, bismuth oxide, tungsten, tungsten oxide, carbon, manganese, manganese oxide, black pigment and aluminum oxide. 4. The method according to claim 3, wherein the paste composition has a composition of 0.7 to 10% by weight of frit and a composition of 60 to 99.3% by weight of powder in the final composition after blackening.

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