KR20020029545A - Shadow mask of colour crt - Google Patents

Abstract

PURPOSE: A shadow mask of a color cathode ray tube is provided to reduce doming phenomena and improve image quality by forming an electron reflecting film having desirable heat radiating characteristic and heat conducting characteristic on a surface of a shadow mask. CONSTITUTION: A shadow mask of a color cathode ray tube comprises an electron reflecting film at the surface of the shadow mask. The electron reflecting film is formed by a water solution of pH 2-4 having P, Mn, Bi, Ni and Fe ions of mixture weight 10 wt%. Adhesion such as PVA(poly vinyl alcohol) of 1% of weight of the mixture ion is solved into the water solution. Then, a procedure of applying the solution by a spray and drying at 100°C is repeated three times to form a film of 5 microns on the front side and the rear side of the shadow mask. The shadow mask having the films is molded and blacked in a black furnace at 600°C for 15 minutes. The water solution may be made to hydrides by hydrolysis and mixed with the PVA.

Description

Shadow mask of color cathode ray tube {SHADOW MASK OF COLOUR CRT}

The present invention relates to a shadow mask of a color cathode ray tube, and is particularly suitable for improving color purity by forming an electron reflection film having low thermal expansion and excellent thermal conductivity on the surface of the shadow mask to prevent mis-landing with an electron beam on the screen by suppressing doming phenomenon. It's about shadow masks.

In the color cathode ray tube, as shown in Fig. 1, a panel 1 having a fluorescent film 3 formed on its inner side and a funnel 2 coated with conductive graphite on its inner side are sealed with fusion glass. The neck portion 4 of (2) is equipped with an electron gun 6 for generating three electron beams 5 corresponding to three colors of pixels.

The shadow mask 7, which is a color screening electrode in which a plurality of slot or dot-shaped holes are arranged, is supported by the frame 8 at a position opposite to the fluorescent film 3. The outer peripheral surface of the funnel is equipped with a deflection yoke 9 for deflecting the electron beam from side to side.

Inner shield (10) which shields the geomagnetic shield behind the frame when viewed from the panel to prevent the electron beam from being deflected due to the influence of geomagnetism when the electron beam passes through the hole of the shadow mask and reaches the fluorescent film. ) Is attached.

In the cathode ray tube configured as described above, when an image signal is input to the electron gun 6, hot electrons are emitted from the cathode of the electron gun, and the emitted electrons are accelerated and focused toward the panel by the voltage applied from each electrode of the electron gun. . At this time, the path of the electron beam 5 is adjusted by the magnetic field of the magnet mounted on the neck of the panel, and the adjusted electron beam is scanned on the inner surface of the panel by the deflection yoke 9, about 20% of the deflected electron beam. Color sorting is performed while passing through the hole (Hole) of the shadow mask 7 and the selected electron beam 5 impinges on the fluorescent film 3 of the inner surface of the panel to reproduce the image signal.

Meanwhile, the remaining 80% of the electron beam collides with the surface of the shadow mask to cause a temperature increase, and thus, the shadow mask is thermally expanded, thereby swelling the surface of the shadow mask, thereby changing the landing position of the electron beam. As the phenomenon occurs, mislanding increases, resulting in a decrease in color purity.

In order to solve such a problem, conventionally, the shadow mask is compensated by changing the length of the shadow mask and the welding point to move the shadow mask toward or away from the fluorescent film to adjust the distance between the fluorescent film and the shadow mask. Was intended.

However, the compensation of the shadowing of the shadow mask as described above is performed at the time when the shadow mask is thermally expanded and the dope is completed, there is a problem that can not prevent the degradation of the resolution due to the initial doming.

In order to prevent the doming phenomenon as described above, it is conventionally disclosed in the US Patent Nos. 674,934, 4,528,246 and Japanese Patent Laid-Open No. 59-15861 to manufacture a material of a shadow mask from Invar steel. As described above, when the material of the shadow mask is made of Inva steel, there is an advantage that the thermal expansion of the shadow mask can be reduced, but the price is not economical due to the high price, and the mechanical workability is very poor, so the annealing process temperature is very high, above 900 ° C. There is a problem that the process is complicated, such as the need to heat the mold when forming the shadow mask.

As a method for reducing thermal expansion of the shadow mask, a method of applying a material such as lead or borate having low thermal expansion to the surface of the shadow mask is known from European Patent No. 0139379. As another method of preventing the ming phenomenon, thermal insulation with excellent thermal insulation Methods of coating materials are known. This method is to prevent the heat heated by the electron beam from being transferred to the shadow mask. In this case, a ceramic material is mainly used as the heat insulating material.

In another method, a method of increasing heat radiation by coating a material having excellent thermal radiation on the surface of a shadow mask or by blackening the shadow mask, and according to Korean Patent No. 86-1598, which is patented in Korea by Philips A method of applying an aqueous suspension containing an electron reflecting material to the surface of an electron gun is known.

In another method, a material such as a thermal insulation material, a thermal radiation material, or an electron reflection material is coated on a shadow mask or electron gun surface by a conventional method such as a spray method or a sputtering method.

However, even when the spray process is finely controlled, some of the shadow mask holes are often clogged and the coating surface formed by this method is not uniform. And the sputtering method has a problem that the thickness of the coating layer is thin, the deposition equipment is expensive and the production efficiency is low.

In Korean Patent Laid-Open Publication Nos. 97-29973 and 97-63326, 98-66424, 98-66425, 98-71999 and European Patent WO97-29504, 30-78% of WO ₃ or Bi ₂ O ₃ is used as the electron reflecting material, By developing a screen printing composition using carbon, manganese oxide, and aluminum oxide as a material and screen printing on a shadow mask, it is possible to reduce the doming, form a uniform film, and improve the clogging phenomenon. However, it is considered that there is much room to be achieved through the development of a new electronic reflective material in improving the doming property than using the conventional method while being different from the existing patent as described above.

The present invention solves the above-mentioned problems and, unlike the prior patents, forms an electron reflection film having excellent thermal radiation and thermal conductivity on the surface of the shadow mask, thereby obtaining a shadow mask having improved image quality due to the reduction of the doming phenomenon. There is this.

1 is a structural diagram of a color cathode ray tube

Figure 2a is a cross-sectional picture of a composite membrane according to the present invention

Figure 2b is a surface photograph of the composite membrane according to the present invention

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

7: shadow mask

The present invention for achieving the above object is 1 to 10% by weight of iron (Fe), 14 to 40% by weight of manganese (Mn), bismuth (Bi) when the electronic reflective material is applied to the shadow mask surface 100% by weight ) 9 to 26% by weight, nickel (Ni) 2 to 8% by weight and the remainder is composed of phosphorus (P).

Phosphorus (P) in the above composition serves as a binder as a glass glass component in the electron reflection film as a main component, and also serves to suppress thermal expansion of the shadow mask.

In addition, manganese (Mn) makes the color of the electron-vacant film black, thereby causing heat radiation and heat conduction to remove heat from the shadow mask.

Bismuth (Bi) acts as an electron reflection to help the backscattering of electrons effectively when electrons emitted from the electron gun hit the shadow mask surface.

Iron (Fe) and nickel (Ni) improve the bond strength of heat transfer and electron reflecting film as auxiliary components and suppress thermal expansion.

In forming the electron reflection film using the above composition, after adjusting the pH of the aqueous solution of phosphorus (P), manganese (Mn), bismuth (Bi), nickel (Ni) and iron (Fe) salts to 2-4, polyvinyl A small amount of an adhesive such as alcohol (PVA) is added, sprayed after dissolution, and dried at 100 ° C. several times.

Alternatively, the mixed aqueous solution of the composition is hydrolyzed to form a hydrate, and the hydrates of the respective elements are mixed with polyvinyl alcohol (PVA), and then applied by a spray method and dried.

In another method, when the shadow mask is immersed in a mixed aqueous solution having the same composition as above and heated to 80 to 90 ° C., the material is hydrolyzed in water and reacts with oxygen in the water to form a film on the shadow mask surface. have.

Alternatively, the same mixed salt may be dissolved in alcohol, sprayed or hydrated, spray applied, or immersed in a shadow mask to hydrolyze the solution to react with oxygen in the solution to form a composite membrane.

When the film is formed by immersing the shadow mask as described above, the shadow mask surface is in an unstable state in a chemical reaction, thereby forming an electron reflection film by the precipitation reaction on the surface. At this time, phosphorus (P), manganese (Mn), bismuth (Bi), nickel (Ni), and iron (Fe) ions react with each other to form hydrates outside the shadow mask to form hydrates. If it is attached to the side of the shadow mask hole will cause clogging, so when immersed to form a film should be careful not to stick the baggage by bringing a fine mesh close to the front and back of the shadow mask.

When the film is formed in the same manner as described above and molded and subjected to a blackening process at 600 ° C., phosphorus (P) in the hydrate is oxidized, and manganese (Mn), bismuth (Bi), nickel (Ni), iron (Fe) ions and the like. Combine to form a rigid membrane. Application to the shadow mask is done on both front and back or on the opposing side of the gun. The material is preferably applied to both the front and back of the shadow mask because of its excellent thermal expansion and thermal radiation.

Through the blackening process, polyvinyl alcohol (PVA) is decomposed and disappeared, and a solid composite film is formed on the shadow mask surface to have a function of heat transfer, electron reflection, and thermal expansion.

In the present invention, the thickness of the electron reflection film is preferably 1 to 10 탆. At this time, when the film thickness is within 1 μm, the electron reflection function is deteriorated.

The following is described according to the embodiment.

Example 1

Polyvinyl alcohol (PVA) after adjusting the pH of the aqueous solution in which the mixed weight of phosphorus (P), manganese (Mn), bismuth (Bi), nickel (Ni), iron (Fe) ions is 10% by weight A small amount of adhesive, such as 1% of the mixed ions, was dissolved, sprayed and dried at 100 ° C. three times to form a 5 μm film on the front and back of the shadow mask, and then a shadow mask was formed and blackened at 600 ° C. Blackening treatment was performed in the furnace for 15 minutes to form a cathode ray tube. 2A and 2B illustrate cross-sectional photographs of the composite membrane and surface photographs of the composite membrane according to the present invention.

Example 2

Hydrolyze the mixed aqueous solution of 10% by weight of phosphorus (P), manganese (Mn), bismuth (Bi), nickel (Ni), and iron (Fe) ions to form hydrates, such as polyvinyl alcohol (PVA) A small amount of the adhesive was added to 1% of the mixed ion weight, dissolved, spray-coated and dried, and then AK shadow masks were formed and blackened in a black furnace at 600 ° C. for 15 minutes to form a cathode ray tube.

Example 3

An AK shadow mask was immersed in a mixed aqueous solution containing 10% by weight of phosphorus (P), manganese (Mn), bismuth (Bi), nickel (Ni), and iron (Fe) ions, and heated to 80 to 90 ° C. After the deposition treatment for minutes, washed, dried and molded and blackened for 15 minutes in a black furnace at 600 ℃ to make a cathode ray tube.

Comparative Example 1

The AK shadow mask was molded and blackened for 15 minutes in a blackening furnace at 600 ° C. to produce a cathode ray tube.

Comparative Example 2

After dispersing Bi ₂ O ₃ in water, water glass was added and stirred to prepare a Bi ₂ O ₃ suspension. After the phosphor coating was finished, the AK shadow mask was separated from the panel to which the frame was attached, and then a suspension of Bi ₂ O ₃ was spray-coated onto the opposing side of the electron gun of the shadow mask, and the color cathode ray tube was manufactured by bonding the suspension to the panel.

The shadowing masks prepared using the examples and the comparative examples were evaluated for the domming characteristics of the color cathode ray tubes. The evaluation point evaluated the maximum dominant amount at the point 12 cm from the center of the screen.

Doming effect (D.E = Doming Effect) was calculated according to the following equation.

DE = Miss Blended _(Uncoated) -Miss Blended _(Coated) / Miss Blended _(Uncoated)

Mislending _(uncoated) : Mislending that occurs when using shadow mask without electron reflection film.

Mis-Lending _(Coating) : Mis-rendering that occurs when using a shadow mask with an electron reflection film.

Doming evaluation results according to the above formula is shown in (Table 1).

Example Comparative Example One 2 3 One 2 Doming characteristic (㎛) 45 39 35 95 60 Doming effect (%) 53 59 63 0 37

As described above, the present invention is applied to the shadow mask surface by applying an electron reflection film composed of phosphorus (P), manganese (Mn), bismuth (Bi), nickel (Ni), iron (Fe) excellent in thermal radiation and thermal conductivity As a result, the image quality is improved due to the reduction of the dominant phenomenon.

Claims (1)

100% by weight of the electron reflecting material applied to the shadow mask surface, 1 to 10% by weight of iron (Fe), 14 to 40% by weight of manganese (Mn), 9 to 26% by weight of bismuth (Bi), nickel (Ni) 2 Shadow mask of a color cathode ray tube, characterized in that it is -8% by weight, and the rest is composed of phosphorus (P).