KR20010084307A - shadow mask of cathode ray tube - Google Patents

Abstract

PURPOSE: A shadow mask for CRT is provided, in which reflector film having a superior reflection and heat radiation performance is employed, to thereby prevent doming of shadow mask by suppressing heating of shadow mask caused due to electron beam. CONSTITUTION: A shadow mask is characterized in that a narrow hole is formed for passage of electron beam, a reflector film is arranged at the surface opposed to an electron gun so as to prevent doming of shadow mask, and the reflector film is composed of CaWO4, MgWO4 and frit glass material. The reflector film of the shadow mask contains electron reflecting material of CaWO4 and MgWO4, and the film coated to the shadow mask contains frit with PbO, wherein the frit is contained in 40 to 70weight parts with respect to the electron reflector material.

Description

Shadow mask of cathode ray tube {shadow mask of cathode ray tube}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shadow mask for cathode ray tube, and more particularly, to a shadow mask for cathode ray tube, in which a dominant phenomenon is suppressed and an electron beam strikes a proper position of a fluorescent surface to make image quality clear.

Cathode ray tube is a kind of electron tube, it is one of the display devices that make a desired display by focusing and accelerating electrons emitted from the cathode of electron gun to make electron beam, and controlling its direction by the action of electric or magnetic field and hitting the fluorescent surface. The shadow mask is a metal perforated plate attached to the front of the fluorescent surface to perform color screening.

1 is a schematic configuration diagram of a conventional conventional cathode ray tube.

Referring to FIG. 1, the electron beam emitted from the electron gun 6 is focused and accelerated to be scanned toward the fluorescent surface. At this time, the color beam is selected through the shadow mask 4 in front of the fluorescent surface. On the other hand, about 30% of electron beams pass through the shadow mask and hit the fluorescent surface during color screening, and the remaining 70% does not pass through the shadow mask but hits the shadow mask and is converted into heat. The heat raises the temperature of the shadow mask surface resulting in thermal expansion of the shadow mask.

Due to the thermal expansion of the shadow mask as described above, the position of the shadow mask hole is changed, thereby changing the position of the electron beam passing through the hole and reaching the fluorescent film, thereby causing a color bleeding phenomenon.

Various methods have been proposed in the past to suppress the dominant phenomenon as described above.

First, a method of controlling the distance between the fluorescent film and the shadow mask by moving the shadow mask toward or away from the fluorescent surface by changing the length and welding point of the shadow mask spring is proposed. Since the correction is performed at the time point, there is a problem in that the degradation of the resolution due to the initial doming cannot be prevented.

Second, it is proposed in the US Patent No. 647,934, etc. to manufacture the material of the shadow mask made of Inva steel, which has advantages in reducing thermal expansion, but disadvantages in price and processability.

Third, a method of applying lead, borate, or the like having a small thermal expansion to the surface of a shadow mask, or a method of coating a thermal insulating material having excellent thermal insulation is known.

Finally, a method of increasing the thermal radiation rate by coating a material having excellent thermal radiation performance on the surface of the shadow mask or by blackening the mask and a method of coating an electron reflective material are known.

In the above method, the coating method of the electron reflection material or the like is commonly used, but the spraying method and the sputtering method are commonly used. The spraying method may cause clogging of the shadow mask, and also has a defect that the coating surface is not uniform. , 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. Meanwhile, in Korean Patent Publication No. 98-66424, Tungsten Oxide (WO ₃ ) or Bismuth Oxide (Bi ₂ O ₃ ) is used as electron reflecting material and 34 ~ 78% is used. A method of making a printing composition and screen printing a shadow mask has been proposed. As a result, a reduction in the dominance phenomenon and the shadow mask hole clogging caused by the spray method have been improved.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to provide a shadow mask for a cathode ray tube having an electron reflecting film which can effectively reduce the doming phenomenon by obtaining a better electron reflecting effect and a heat radiation effect.

1 is a schematic configuration diagram of a cathode ray tube

In the shadow mask for cathode ray tube according to the invention for achieving the above object, in the shadow mask for cathode ray tube having a narrow hole is formed to pass the electron beam, and provided with an electron reflecting film on the opposite surface of the electron gun in order to prevent the dominant phenomenon ,

The electron reflection layer is characterized in that the tungsten oxide oxide (CaWO ₄ ) or tungsten magnesium oxide (MgWO ₄ ) and a glass material.

The thickness of the electron reflection film according to the invention is characterized in that the coating so as to be 1 ~ 100㎛.

In addition, the electron reflection film of the shadow mask contains an electron reflection material such as tungsten calcium oxide (CaWO ₄ ) or tungsten magnesium oxide (MgWO ₄ ), and a frit containing electron oxide (PbO) in the coating film of the shadow mask is an electron reflection material It is characterized in that it contains 40 to 70 parts by weight.

The electron reflection film is formed by a screen printing method or a spray coating method.

In more detail, the electron reflecting film of the shadow mask for cathode ray tube according to the present invention, when the electron reflecting material is applied to the shadow mask by a screen printing method and heat treated, tungsten calcium oxide (CaWO ₄ ) or tungsten magnesium oxide (MgWO ₄ ) and The same electron reflecting material is contained and the frit containing lead oxide (PbO) is formed so as to form 40 to 70 parts by weight compared to the electron reflecting. It can prevent the hole of the mask to be blocked afterwards.

In the shadow mask for cathode ray tube according to the present invention as described above, the manufacturing process of the electron radiation film is as follows.

First, the organic binder is dissolved in a solvent to prepare a vehicle. Ethyl cellulose, nitro cellulose, epoxy, etc. are used as an organic binder, and butyl acetate etc. are added to solvents, such as butyl carbitol and butyl carbitol acetate, as a solvent. The viscosity of the vehicle is 3000 to 5000 cps.

Electron reflecting material is tungsten calcium oxide to the prepared vehicle as described above (CaWO ₄₎ Alternatively, tungsten, magnesium oxide was added (MgWO ₄₎ and the frit glass by mixing treated uniformly distributed in 3 the roller to prepare a screen printing composition.

The printed composition is then screen printed onto the electron gun facing surface of the annealing shadow mask to form a coating film. At this time, the thickness of a coating film shall be 1-100 micrometers. This is because the effect of electron reflection is inferior when the thickness of the coating film is 1 µm or less, and the peeling of the film occurs when it is 100 µm or more.

Then, the shadow mask on which the screen printing film is formed is dried and molded, and then blackened to stabilize. The organic matter is decomposed on the printing film disappears and thereby the frit is melted by the electron reflecting material is tungsten calcium oxide (CaWO ₄₎ or tungsten oxide magnesium (MgWO ₄₎ welded on the shadow mask adhered.

In the coating film formed as described above, the doping phenomenon is effectively suppressed because tungsten calcium oxide (CaWO ₄ ) or magnesium tungsten oxide (MgWO ₄ ) simultaneously serves as an electron reflector and a phosphor.

When explain this in more detail, at the time of electron collisions with the tungsten calcium oxide above a shadow mask (CaWO ₄₎ or tungsten oxide magnesium (MgWO ₄₎ it is to form an electron reflection film by a tungsten (W) taking place electron reflection effects, and oxidation Since tungsten calcium (CaWO ₄ ) or tungsten magnesium oxide (MgWO ₄ ) acts as a phosphor, electrons impinging on the shadow mask are converted into light energy before being converted into thermal energy, thereby effectively suppressing the doming phenomenon.

More specifically, as a phosphor, tungsten calcium oxide (CaWO ₄ ) or tungsten magnesium oxide (MgWO ₄ ) has a spinel crystal structure in which Ca ²⁺ or Mg ²⁺ is combined with WO ₄ ^2- , wherein WO ₄ ^{2 is used. -} this is the light emission center is excited at O 2P energy level of the electron in the collision with the W t _2g energy level that will cause the light emission.

In order to help the understanding of the present invention will be introduced to the correct embodiment of the present invention. However, embodiments of the present invention are not limited to the following examples.

The first embodiment is 60 parts by weight of a volatile point of 180 or more butyl carbitol solvent and a polymeric adhesive of ethyl preparing the vehicle for the cellulose is dissolved the viscosity is such that 4500cps and E reflecting member tungsten calcium oxide in the vehicle (CaWO ₄₎ that is, oxide 50 parts by weight of the frit containing lead (PbO) is mixed with the weight of the electron reflection material, and then dispersed in three rollers to prepare a screen printing composition. The composition is screen printed on the opposing gun gun surface of the shadow mask to have a thickness of 6 μm. The coating film is formed, the shadow mask is dried and then blackened at 600 ° C. to complete the manufacture of the shadow mask.

In the second embodiment, the shadow mask is manufactured in almost the same process as in the first embodiment. However, a screen was prepared by using nitrocellulose as a polymer adhesive and making a vehicle with a viscosity of 4000 cps, selecting an electron reflection material as tungsten magnesium oxide (MgWO ₄ ), and a frit containing lead oxide (PbO) at 50 parts by weight relative to the electron reflection material. A shadow mask is prepared by screen printing a printing composition onto a shadow mask.

Comparative Example for comparison with the embodiment according to the present invention, in the manufacturing process almost the same as the embodiment, except that a polymer adhesive is made of nitrocellulose to produce a vehicle, the viscosity of the vehicle is 5000cps, and the electron reflector tungsten oxide ( WO ₃ ), and the screen printing composition prepared by using a PbO-containing frit 50 parts by weight relative to the electronic reflector screen to the shadow mask to produce a shadow mask.

The chart below shows the domming characteristics of the first, second and comparative examples, and measured the maximum dominant amount at a point 12 cm from the center of the screen.

Example 1 Example 2 Comparative example Doming characteristic (㎛) 40 43 50

From the above results, it can be seen that the screen printing composition according to the present invention effectively reduces the doming phenomenon.

In addition, as another embodiment of the present invention, the same electron reflection film may be prepared by spraying a slurry made of tungsten calcium oxide (CaWO ₄ ) or magnesium tungsten oxide (MgWO ₄ ) together with water glass or an adhesive binder. .

As described above, the shadow mask according to the present invention has an effect of effectively reducing the dominant phenomenon by suppressing thermal expansion of the shadow mask by having an excellent electron reflection effect and heat radiation effect of the electron reflection film.

Claims (5)

In a shadow mask for a cathode ray tube, a narrow hole is formed to pass an electron beam, and an electron reflecting film is provided on an opposite surface of the electron gun to prevent a dope phenomenon. The electron reflecting film is a shadow mask for cathode ray tube, characterized in that consisting of tungsten calcium oxide (CaWO ₄ ) or tungsten magnesium oxide (MgWO ₄ ) and frit glass material. The method of claim 1, The shadow mask for cathode ray tube, characterized in that the coating of the thickness of the electron reflection film to 1 ~ 100㎛. The method of claim 1, The shadow mask for cathode ray tubes, characterized in that the frit containing lead oxide (PbO) in the coating film of the shadow mask is contained in 40 to 70 parts by weight compared to the electron reflection material. The method of claim 1, The electron reflection film is a shadow mask for a cathode ray tube, characterized in that formed by screen printing. The method of claim 1, The electron reflection film is a shadow mask for a cathode ray tube, characterized in that formed by a spray coating method.