KR19990046861A - Method for manufacturing shadow mask for cathode ray tube and shadow mask for cathode ray tube manufactured by the method - Google Patents

Abstract

The present invention relates to a shadow mask manufacturing method for a cathode ray tube having excellent strength, and to a shadow mask manufactured by the method. The crystal size is about ASTM # 9 to # 11, which is much higher in strength than the conventional shadow mask, and is excellent in vibration resistance and impact resistance.

Description

Method for manufacturing shadow mask for cathode ray tube and shadow mask for cathode ray tube manufactured by the method

Industrial use field

The present invention relates to a method for manufacturing a shadow mask for a cathode ray tube and a shadow mask for a cathode ray tube manufactured by the method. It is about a mask.

Prior art

The shadow mask is a dichroic structure used for color television or color monitor.

The basic structure of a color television or color monitor is a cathode ray tube. A cathode ray tube is an apparatus in which an electron beam emitted from an electron gun collides with a phosphor on an inner surface of a panel to obtain an image. The shadow mask mounted on the cathode ray tube matches the three electron beams from the electron gun to the red, green, and blue phosphor dots, respectively. Therefore, if the position of the shadow mask is slightly out of the original position, the path of the electron beam is shifted, causing unwanted phosphor to emit light. In particular, a phenomenon in which the shadow mask is resonated by vibrations from outside or sound waves generated from a speaker, etc., causes problems such as screen shake and color purity degradation. In addition, local deformation of the shadow mask due to impact from the outside deteriorates the quality of the cathode ray tube.

Hereinafter, the resonance phenomenon and the local deformation of the shadow mask due to external vibrations or negative waves and impacts will be described in more detail.

The electron beam emitted from the electron gun passes through the hole of the shadow mask and lands on the fluorescent surface formed on the inner surface of the panel to emit the phosphor. However, when the cathode ray tube is affected by vibration from the outside or a sound wave generated from a speaker mounted on the cathode ray tube, the shadow mask vibrates up, down, left and right, and the hole of the shadow mask is out of its original position. As a result, the electron beam does not pass through the hole of the shadow mask accurately and is mislanded on the fluorescent surface. In addition, when the cathode ray tube is impacted by a drop or the like, permanent deformation occurs locally in the shadow mask. In the deformation part of the shadow mask, the hole is out of its original position. Therefore, the electron beam does not accurately pass through the hole of the shadow mask and cannot land correctly on the fluorescent surface formed on the inner surface of the panel. As a result of the above phenomenon, problems such as screen shaking and a decrease in color purity occur, resulting in a deterioration of the quality of the cathode ray tube.

The above phenomena occur because the strength of the shadow mask is weak and easily affected by vibrations, sound waves, and impacts from the outside. Therefore, in order to solve this problem, various methods for improving the intensity of the shadow mask have been proposed. For example, Japanese Patent Laid-Open No. 62-223950 attempts to improve the strength by forming a plating layer on the shadow mask surface. However, in this case, there is a disadvantage in that the hole size of the shadow mask is reduced. Further, Japanese Patent Laid-Open No. 56-121257 and Japanese Patent Laid-Open No. Hei 1-276542 tried to improve the strength by heat-treating the molded shadow mask, but the effect was not sufficient.

In order to solve the above problems, an object of the present invention is to provide a shadow mask manufacturing method for a cathode ray tube that can improve the strength of the shadow mask.

Another object of the present invention is to provide a shadow mask for cathode ray tube manufactured by the above method, and to provide a shadow mask for cathode ray tube having excellent strength and impact resistance and vibration resistance.

In order to achieve the above object of the present invention, the present invention provides a cathode ray tube comprising a step of heating a shadow mask of a metal or alloy material to a recrystallization temperature of the metal or alloy and a step of quenching the shadow mask. Provided is a method of making a shadow mask.

The present invention also provides a shadow mask for cathode ray tubes made of a metal or alloy having a grain size of ASTM # 9 to # 11.

Hereinafter, the present invention will be described in more detail.

In the case of metal or alloy materials, the strength increases as the crystal size decreases. It is well known by the Hall-Petch equation of Equation 1 below.

[Equation 1]

σ _y = σ _o + kd ^-1/2

In the above formula, σ _y is yield stress, σ _o is a friction stress that hinders the movement of dislocation, k is a constant measuring the crystal size in which dislocation is integrated, and d is the diameter of the crystal.

As can be seen from the above equation, the size of the crystal must be small in order to increase the yield stress, that is, the strength. In light of this fact, the present invention is to increase the strength of the shadow mask by reducing the crystal size of the metal or alloy material forming the shadow mask.

The following describes the application of the above principles to the present invention in more detail.

Generally, shadow masks for cathode ray tubes are employed in cathode ray tubes immediately after molding from metal or alloy materials. However, in the present invention, after a shadow mask is formed of a metal or alloy material, the shadow mask is heated to the recrystallization temperature of the metal or alloy constituting the shadow mask. Here, it is preferable to use aluminum killed steel or invar steel as the metal or alloy used as the material of the shadow mask. In the case of aluminum-kilted steel, since the recrystallization temperature is 350-450 degreeC, it is preferable to heat to 350-500 degreeC, More preferably, it heats to 450-500 degreeC. Invar steel is preferably heated to 600 to 700 ° C, more preferably 650 to 700 ° C, because the recrystallization temperature is 600 to 650 ° C. At this time, it is preferable to perform a heating process under a reducing atmosphere in order to prevent oxidation of the metal or alloy material. As a method of creating a reducing atmosphere, a reducing gas such as hydrogen, argon or nitrogen is injected into a heat treatment furnace.

Raising the temperature of the metal or alloy to the recrystallization temperature causes new nucleation within the metal or alloy. However, if the shadow mask is kept at this temperature, the nucleus grows and the crystal becomes coarse. Therefore, the shadow mask must be quenched before the crystal size grows, ie when nucleation begins, so that the nucleus no longer grows. As the quenching method, there are various methods such as water cooling, air cooling, and gas cooling. In this case, in order to minimize the undesirable effects on the metal or alloy material constituting the shadow mask, cooling by a gas that injects air or liquid nitrogen into a gas state is preferable, rather than water cooling.

In the case of the shadow mask manufactured by the shadow mask manufacturing method of the present invention, the crystal size corresponds to ASTM # 9 to # 11. That is, on the electron microscopic photograph of 100 times magnification taken organization of the shadow mask of the present invention, the number of crystals present in the area of 1in ² is that 180-1400.

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 1

The shadow mask, which was formed of aluminum-kilted steel, was put into a heat treatment furnace. The atmosphere of this heat treatment furnace was injected with argon gas and kept in a reducing atmosphere. The temperature of the heat treatment furnace was raised to 450 ° C., which is the recrystallization temperature range of the aluminum killed steel. At this time, the shadow mask was quenched to room temperature immediately by injecting liquid nitrogen through a nozzle connected to the heat treatment furnace.

Comparative Example 1

The shadow mask was molded from aluminum killed steel.

The shadow masks of Example 1 and Comparative Example 1 described above were polished and etched. Subsequently, the tissue of the shadow mask was observed with an electron microscope, and then photographed with a camera to obtain an electron microscope photograph with a magnification of 100 times. On this 100-fold magnification electron microscope, the number of crystals present in an area of 1 in ² of 1 inch each in width and length was counted, and the results are shown in Table 1.

material Decision count Crystal size number Example 1 Aluminum killed steel 256 ASTM # 9 Comparative Example 1 Aluminum killed steel 32 ASTM # 6

The number of crystals in Table 1 described above is the number of crystals present in 1 in ² on an electron micrograph at 100 times magnification. In the present invention, a method for determining the crystal size number by ASTM (American Society for Testing and Materials) was used as a method for measuring the size of the crystal.

As shown in Table 1, the shadow mask according to the present invention has a crystal size equivalent to ASTM # 9, but the conventional shadow mask of Comparative Example 1 has a crystal size corresponding to ASTM # 6. This result proves that the shadow mask of Example 1 according to the present invention is superior in strength to the conventional shadow mask.

As described above, after the shadow mask formed of the metal or alloy material is raised to the recrystallization temperature of the metal or alloy, the quenched shadow mask is about 20% stronger than the conventional shadow mask which is adopted in the cathode ray tube immediately after molding. By increasing the degree, the impact resistance and vibration resistance are excellent, so that it is easy to handle and transport.

Claims (5)

Heating a shadow mask of a shaped metal or alloy material to a recrystallization temperature of the metal or alloy; And A shadow mask manufacturing method for cathode ray tubes, the step of quenching the shadow mask. The method of claim 1, wherein the heating process is performed under a reducing atmosphere. The method of claim 1, wherein the quenching process is an air cooling or gas cooling process. The method of claim 1, wherein the metal or alloy is aluminum-kilted steel or Invar steel. Shadow mask for cathode ray tubes made of metal or alloy with grain size ASTM # 9 to # 11.