KR20000066137A - Shadow mask for cathode ray tube and manufacturing method of the same - Google Patents

Abstract

PURPOSE: A shadow mask having a curved surface intensity is provided to increase the mechanical strength of the shadow mask and to enhance the landing accuracy. CONSTITUTION: The cathode ray tubes comprise a phosphor screen formed on an inner surface plate of a panel portion of an evacuated envelope, a shadow mask having a multiplicity of electron beam apertures and spaced from the phosphor screen within the panel portion, an electron gun of the in-line type housed within a neck portion of the evacuated envelope, and a deflection yoke mounted around a funnel portion of the evacuated envelope. Three electron beams emitted from the electron gun are deflected by the deflection yoke and thereafter are projected onto picture elements of the corresponding colors of the phosphor screen through the electron beam apertures of the shadow mask to display a desired color image on the phosphor screen. The shadow mask manufacturing is a processes of forming a phosphor screen. The processes comprise an annealing process, a paste composition process to make ceramic coating material, a screen printing process, a drying process, a shaping process, and a blackening furnace process.

Description

Shadow mask for cathode ray tube and manufacturing method {Shadow mask for cathode ray tube and manufacturing method of the same}

The present invention relates to a shadow mask for a cathode ray tube and a method of manufacturing the same, and more particularly to a shadow mask capable of reinforcing the strength of the shadow mask to reduce deformation due to external impact and corresponding to the planarization trend of a cathode ray tube and a method of manufacturing the same. It is about.

In general, a cathode ray tube is a display device in which an image of a three-beam electron beam emitted from an electron gun collides with R, G, and B phosphors in a phosphor film screen to excite the phosphor.

To this end, the cathode ray tube includes a panel 3 which forms a fluorescent film screen 1 on the inner surface as shown in FIG. 10, an electron gun 7 that emits an electron beam 5 toward the fluorescent film screen 1, and A neck portion 9 for mounting the electron gun 7 therein; a trumpet-shaped funnel 11 connecting the panel 3 and the neck portion 9; and the fluorescent film screen 1 in parallel. And a shadow mask 13 to be mounted.

Here, the shadow mask 13 forms a plurality of beam passing apertures 13a and serves as a bridge for separating and landing three stem electron beams 5 emitted from the electron gun 7 into corresponding R, G, and B phosphors. Do it. As a result, when the shadow mask 13 deviates even a little from the reference position, the path of the electron beam 5 is displaced, which causes the color purity of the screen to be lowered, such as failing to land on the phosphor precisely or emitting another color phosphor.

However, since the shadow mask 13 is made of an extremely thin metal plate material, a domming phenomenon in which the shadow mask 13 is convexly expanded toward the panel 3 occurs due to an increase in temperature caused by the collision of the electron beam 5, or an external shock or vibration. In some cases permanent or partial permanent deformation occurs.

The permanent deformation of the shadow mask 13 tends to be more prominent in the shadow mask fabricated substantially flat. This is because the screen of the cathode ray tube is gradually flattened, so that the shadow mask is substantially flat in response to the flattened panel. It is because curvature intensity | strength falls significantly compared with the shadow mask which has a predetermined curvature in the case of manufacture.

Therefore, it is important to actively suppress the doming and permanent deformation of the shadow mask 13.

To this end, a method of coating the surface of the shadow mask 13 with an electron reflection material for preventing absorption of the electron beam 5 or a reinforcing material for reinforcing the curved strength of the shadow mask 13 has been devised.

In this regard, U. S. Patent No. 5,757, 119, previously applied, sequentially coats an insulating glass film and a conductive film on the surface of a beam passing aperture facing the fluorescent screen to improve the strength of the shadow mask and the accuracy of the electron beam landing. Described shadow masks.

However, both of the insulating glass film and the conductive film are formed by the spray method, the coating film formation by the spray method may block the aperture for beam passing, uneven size of the aperture for beam passing, and the thickness of the coating film may be uneven. Has the disadvantage.

Therefore, to overcome this, Korean Patent Application No. 95-40315 describes the formation of a coating film of a shadow mask using a screen printing method and a photoresist film.

The screen printing method refers to a method of disposing a screen mesh having a fine lattice structure on one surface of a shadow mask, applying a paste-like coating material to the surface of the screen mesh, and then printing it using a squeeze.

Therefore, the present invention is designed to solve the above problems, the object of the present invention is to strengthen the shadow mask to prevent the total or partial permanent deformation, effectively respond to the planarization trend of the cathode ray tube, and improve the landing characteristics of the electron beam The present invention provides a shadow mask for a cathode ray tube and a method of manufacturing the same.

1 is a perspective view of a shadow mask according to the present invention.

FIG. 2 is a partial cross-sectional view of the section and the panel cut along the line A-A of FIG. 1; FIG.

3 is a process flowchart showing a method of manufacturing a shadow mask according to the present invention.

4 is an enlarged view of a portion of the shadow mask.

5 to 7 are schematic views of shadow masks in a screen printing process.

8 is a partial cross-sectional view of the shadow mask after the blackening process.

Figure 9 is a graph comparing the intensity characteristics of the shadow mask according to the present invention and the prior art.

10 is a partial cutaway perspective view of a typical cathode ray tube.

In order to achieve the above object, the present invention,

A shadow mask for a cathode ray tube is provided, which includes a main body forming a plurality of beam passing apertures and a ceramic coating film fused to at least one surface of the main body to improve strength of the main body.

In addition, the present invention to achieve the above object,

In order to improve the machinability, an annealing step of introducing the main body into an annealing furnace containing high temperature hydrogen gas, a paste manufacturing step of manufacturing a coating film paste containing a ceramic material, and printing the paste on at least one surface of the main body A screen printing step, a drying step of drying the paste-printed main body, a molding step of press-processing the main body to form an effective screen portion and a skirt portion, and a blackening step of inserting a shadow mask into the blackening furnace to blacken Provided is a method of manufacturing a shadow mask for a cathode ray tube.

Here, the ceramic material is a frit material having a fusion temperature of 650 ° C. or less, and is made of SiO ₂ , PbO, BaO, or the like. A functional powder and a vehicle are mixed with such a ceramic material to prepare a paste, and then screen-printed to form a ceramic coating film.

Such a ceramic coating film enables the shadow mask to maintain sufficient curved strength even when the curved strength is greatly strengthened and manufactured to be substantially flat.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a perspective view of a shadow mask according to the present invention, and FIG. 2 illustrates a cross section and a part of a panel cut along the line A-A of FIG. 1.

As shown, the shadow mask 10 has an effective screen portion 10a that forms a plurality of beam passing apertures 2a in shape, and a skirt portion bent from four edges of the effective screen portion 10a. It is divided into (10b).

The skirt portion 10b is then welded to a mask frame (not shown) and fixedly mounted to the panel 6, and the effective screen portion 10a is arranged side by side with a predetermined distance from the fluorescent film screen 4. To separate and land three stem R, G and B electron beams emitted from an electron gun (not shown) to the corresponding R, G and B phosphors in the fluorescent film screen 4 through the beam passing aperture 2a. When the panel 6 is made flat in order to implement a planar image, the effective screen portion 10a corresponding thereto is also made substantially flat.

At this time, only about 20% of the electron beams emitted from the electron gun pass through the beam passing aperture 2a and land on the fluorescent film screen 4, so that the remaining 80% of the electron beams collide with the shadow mask 10 to cause the shadow mask. When the temperature of (10) is increased and the effective screen portion 10a is made substantially flat, the curved strength is greatly lowered, thereby causing permanent deformation in whole or in part due to external impact or vibration.

Accordingly, in order to suppress the doming phenomenon due to the temperature rise and to reinforce the strength of the effective screen portion 10a, as shown in FIG. A shadow mask 10 including a main body 2 forming a stopper 2a and a ceramic coating film 12 formed on one surface of the main body is provided.

The ceramic coating layer 12 is mainly composed of a ceramic material having a high thermal barrier effect and excellent strength characteristics. In particular, the ceramic coating film is preferably made of a frit material having a fusion temperature of 650 ° C. or lower so as to crystallize at a low melting point.

Such frit materials include SiO ₂ , PbO and BaO.

In addition, the ceramic coating layer 12 further includes a functional powder having a high reflection efficiency of the electron beam and a large thermal radiation effect.

The functional powder may be made of bismuth, bismuth oxide, WC and W oxide, or may be made of at least one of heavy metals having an atomic number of 70 or more or carbon, Mn, Mn oxide, and aluminum oxide having high thermal radiation efficiency.

As described above, the ceramic coating film 12 containing the ceramic material as a main component may be formed on both surfaces of the main body 2 as shown, and may be formed on any one surface of the main body 2 in addition to the illustrated embodiment.

As a result, the electron beam impinging on the shadow mask 10 is heat-transmitted by the ceramic coating film 12 having excellent heat shielding effect, thereby effectively suppressing the shadowing of the shadow mask 10 and effectively forming the effective screen portion 10a. ) Is reinforced by the ceramic coating film 12 having excellent strength characteristics, so that its shape can be maintained even from external shock and vibration.

3 is a process flow chart sequentially showing a method of manufacturing a shadow mask according to the present invention. Referring to this, a method of manufacturing the shadow mask according to the present invention will be described in detail as follows.

First, before the annealing process, as shown in FIG. 4, the main body 2 which consists of a substantially flat metal plate material is partially etched, and the beam passage aperture 2a is formed.

Then, the main body 2 is introduced into an annealing furnace containing high temperature hydrogen gas and annealed. The annealing softens the structure of the main body 2 by high heat and improves the mechanical processability by removing the internal stress, thereby facilitating the molding of the main body 2.

Next, a paste for the ceramic coating film is prepared. The paste is mainly composed of a ceramic material having excellent thermal barrier effect and high strength characteristics, and the paste is prepared into a paste suitable for printing by mixing the ceramic powder with an organic solvent having excellent film adhesion and chemical resistance to a cleaning liquid. Is done.

More specifically, the preparation of the paste consists of mixing 50 to 80% by weight of the ceramic powder, 5 to 30% by weight of the functional powder and the remainder of the vehicle.

At this time, the ceramic powder is preferably made of a frit material having a fusion temperature of 650 ° C. or less so that the ceramic powder may be vitrified in the subsequent fusion process, and such frit materials include SiO ₂ , PbO, and BaO powder.

The frit material is completely vitrified in the blackening process and functions to fix the ceramic coating layer firmly on the main body without disturbing the ceramic coating film.

And the functional powder is a material for the anti-doming properties, for example, to expect at least one or more of the electron reflection effect and the thermal radiation effect is used bismuth, bismuth oxide, WC and W oxide.

In addition, the functional powder may further increase the electron reflection effect by using a heavy metal of atomic number 70 or more, and as another example to improve the thermal radiation effect by using a material having a high heat radiation coefficient such as carbon, Mn, Mn oxide and aluminum oxide. Can be.

Next, the vehicle refers to a material that adjusts the viscosity and viscosity of the paste so as to enable a smooth printing of the paste. If the paste is oily, terpineol is used as a material to impart viscosity, and ethyl cellulose is used. A binder and solvents, such as butyl carbitol, can be mixed and used.

And if the paste is aqueous, the materials can be used in place of water-soluble materials.

Since the vehicle of such a composition is completely volatilized and combusted at a high temperature of 250 to 600 ° C., the functional powder in the paste is present as a ceramic coating film together with the vitrified ceramic material after the blackening process.

Next, the prepared paste is screen printed on one surface of the main body. 5 to 7, screen printing is performed by attaching a fine grid-shaped screen mesh 20 and the main body 2 to a screen printing machine, and then pasting the paste 30 to one surface of the screen mesh 20. It takes place in the process of printing.

The screen mesh 20 has a configuration in which extremely thin steel wires, such as stainless steel, polyester or nylon, are organized in a fine lattice shape, and contains a coated paste 30 to be transferred to the surface of the main body 2. It plays a role.

Next, as shown in FIG. 6, the paste 30 is apply | coated to the screen mesh 20, and the paste 30 is printed on the main body 2, pressing this using the squeeze 32. As shown in FIG. After the printing step, the paste is uniformly printed onto one surface of the main body 2, except for the beam passing aperture 2a, as shown in FIG.

At this time, an additional printing step of printing the paste 30 on the other side of the main body 2 may be further performed to print the paste 30 on both sides of the main body 2.

As such, the paste 30 containing the ceramic material is formed on the main body 2 by screen printing, and then the paste 30 is dried through a drying process. The drying process consists of putting the main body 2 for approximately 30 minutes in a drying furnace maintained at 140 to 160 ° C, for example, to completely dry the solvent contained in the paste 30.

Then, the main body 2 is put into a press molding machine and finished in a final shape having an effective screen portion 10a and a skirt portion 10b as shown in FIG.

Next, the shadow mask 10 is introduced into a blackening furnace to perform a known blackening process for forming a blackening film. The blackening film generated here serves to prevent oxidation of the shadow mask 10 in a subsequent process, to suppress heat absorption, and to prevent diffuse reflection of the exposure beam.

In this blackening process, the ceramic material of the paste 30, that is, the frit material, is completely vitrified, so that the paste 30 is completed with the ceramic coating film 12 firmly fixed on the main body as shown in FIG. Although the beam passing aperture 2a is blocked by the paste 30 in the process, the paste 30 is fused in the blackening process and moved to the outside of the beam passing aperture 2a by the inner surface tension. The clogging of the passage aperture 2a can be effectively prevented.

The ceramic coating film 12 completed through the above process is made of a vitrified ceramic material and a functional powder fixed by the ceramic material. As a result, the shadow mask 10 is not only suppressed doming but also improved in strength by the ceramic coating layer 12 having excellent heat shielding effect and having high strength characteristics, which is advantageous in manufacturing a planar cathode ray tube.

9 is a graph comparing the intensity characteristics of the shadow mask prepared according to the present invention and the shadow mask according to the prior art.

Intensity measurements consist of applying a load to a specific location of the shadow mask to measure the applied load and the depth at which the curved surface of the shadow mask changes.

More specifically, the manufactured shadow mask is welded with a mask frame to manufacture a mask assembly, and the mask assembly is fixed to be exactly horizontal, and then a load cell is applied to the center point based on the center point of the effective screen portion. Add.

The time when no load is applied is set as the reference point, and the depth at which the curved surface of the effective screen portion is lowered compared to the initial reference point is measured while increasing the load in 5g units.

At this time, a particularly important item is the critical load when the curved surface of the effective screen is suddenly turned off. The higher the critical load, the better the shadow mask's strength characteristics and the smaller the changed depth at the same load. The higher the strength characteristics.

As a result of the measurement, the shadow mask (B curve) according to the prior art without forming a ceramic coating film is rapidly changed to a depth of 4 mm when a load of 15 g is applied, and to a depth of 9 mm when a load of 20 g is applied. , And then change gradually.

However, the shadow mask (C curve) according to the present invention in which the ceramic coating film is formed has a changed depth of about 2 mm when a load of 20 g is applied, and the changed depth rapidly changes to 8 mm when a load of 25 g is applied, and then gradually increases. Indicates a change value.

Therefore, although the critical load of the shadow mask according to the prior art is 20g, the critical load of the shadow mask according to the present invention is 25g, and the changed depth at the same load as a whole is smaller than the shadow mask according to the prior art. Indicates a value.

As a result, the shadow mask according to the present invention can be seen that the strength is further improved by the ceramic coating film.

As described above, the shadow mask according to the present embodiment has sufficient strength even when the effective screen portion is substantially flat because the strength characteristics are improved, and thus, the shadow mask has more advantageous characteristics in manufacturing a flat cathode ray tube.

In addition, the excessive temperature rise is suppressed by the ceramic coating film having excellent thermal barrier effect, thereby preventing the doming phenomenon that degrades the landing characteristics of the electron beam, thereby improving the image quality of the cathode ray tube.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to the range of.

As such, the shadow mask according to the present invention can maintain sufficient strength even when the curved surface strength is greatly reinforced by the ceramic coating film containing the ceramic material as a main component, thereby making the material substantially flat. As a result, deformation due to external shock, vibration, or the like can be suppressed, and quality characteristics corresponding to the planarization trend of the cathode ray tube can be provided. In addition, the excessive temperature rise is suppressed by the ceramic coating film having excellent thermal barrier effect, thereby preventing the doming phenomenon, thereby improving the quality of the cathode ray tube.

Claims (15)

Cathode rays that are mounted in parallel with the fluorescent film screen at regular intervals and form a plurality of beam passing apertures corresponding to the phosphor pattern to separate the three-beam electron beams emitted from the electron gun into the corresponding R, G, and B phosphors. In the conventional shadow mask, The shadow mask includes: a body forming a plurality of beam passing apertures; A shadow mask for a cathode ray tube comprising a ceramic coating film fused to at least one surface of the body to improve the strength of the body. The shadow mask for a cathode ray tube according to claim 1, wherein the ceramic coating film is made of a frit material having a welding temperature of 650 ° C or lower. The shadow mask of claim 2, wherein the frit material is selected from the group consisting of SiO ₂ , PbO, and BaO. The shadow mask of claim 1, wherein the ceramic coating layer further comprises a functional powder. 5. The shadow mask of claim 4, wherein the functional powder is selected from the group consisting of bismuth, bismuth oxide, WC, and W oxide. 5. The shadow mask of claim 4, wherein the functional powder is selected from the group consisting of heavy metals having an atomic number of 70 or more. 5. The shadow mask of claim 4, wherein the functional powder is selected from the group consisting of carbon, Mn, Mn oxide, and aluminum oxide. An annealing step of putting the main body into an annealing furnace containing a high temperature hydrogen gas in order to improve machinability; A paste manufacturing process for producing a coating film paste containing a ceramic material; A screen printing process of printing the paste on at least one surface of the main body; A drying step of drying the main body on which the paste is printed; A forming step of pressing the main body to form an effective screen portion and a skirt portion; A method of manufacturing a shadow mask for a cathode ray tube, the method comprising: a blackening step of adding a shadow mask to a black furnace to blacken it. The method of manufacturing a shadow mask for a cathode ray tube according to claim 8, wherein the paste manufacturing step comprises mixing 50 to 80% by weight of ceramic powder, 5 to 30% by weight of functional powder, and the remainder of the vehicle. 10. The method of manufacturing a shadow mask for cathode ray tube according to claim 9, wherein the ceramic powder is made of a frit material having a welding temperature of 650 ° C or lower. The method of claim 10, wherein the frit material is selected from the group consisting of SiO ₂ , PbO, and BaO powders. 10. The method of claim 9, wherein the functional powder is selected from the group consisting of bismuth, bismuth oxide, WC, and W oxide. 10. The method of claim 9, wherein the functional powder is selected from the group consisting of heavy metals having atomic number of 70 or more. 10. The method of claim 9, wherein the functional powder is selected from the group consisting of carbon, Mn, Mn oxide, and aluminum oxide. The screen printing process according to claim 8, further comprising the steps of: mounting a screen mesh having a beam aperture and a screen mesh of fine lattice structure on the upper surface of the main body; Method of producing a shadow mask for a cathode ray tube comprising a printing step of applying a paste to one side of the screen mesh and printing while pressing with a squeeze.