KR100240488B1 - Cathode ray tube - Google Patents

Abstract

The present invention discloses a novel method for manufacturing an impregnated cathode and a manufacturing apparatus for implementing the same.

Conventionally, since the cathode is formed by impregnating the cathode material after pressing the pellet and welding the cap to the inner sleeve, the process is complicated and the electron emission efficiency is deteriorated.

In the present invention, by pressing the pellet inside the cap to form the cap and the pellet integrally, the cap assembly process and the welding heat input accordingly are omitted, thereby achieving the reduction of the karate and the electron emission efficiency of the cathode.

Description

Method and apparatus for manufacturing impregnated cathode

1 is a cross-sectional view showing the configuration of the impregnated cathode.

2a to 2d are sequential cross-sectional views showing a conventional method for manufacturing an impregnated cathode.

3a to 3d are sequential cross-sectional views showing a method of manufacturing an impregnated cathode according to the present invention.

4 is a cross-sectional view showing an impregnated cathode prepared according to the present invention.

* Explanation of symbols for main parts of the drawings

K: (impregnated) cathode P: pellet

P ': temporary molded body C: cap

10: die 11: cavity

20: punch 21, 22: first and second punches

30: stripper

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode type cathode of a CRT, and more particularly to a manufacturing method and apparatus thereof.

The cathode ray tube, which is a main application field of the present invention, forms a electron beam by focusing and accelerating thermal electrons generated at the cathode by a plurality of control electrodes, and deflecting the electron beam. By selectively emitting each part of the device, a device is configured to scan and display an image. Here, a configuration of a cathode serving as a hot electron emission source is shown in FIG. 1, in which a heater H is accommodated inside an inner sleeve I and a cathode for emitting electrons thereon. A cap C containing a pellet of material P is installed (this is the case for an impregnated cathode and for a cathode the cap is coated with a cathode material).

The inner sleeve (I) is made of a thin metal ribbon on an outer sleeve (O) supported by a support (S) on the strap (A) to prevent heat dissipation and consequent heat loss. ribon; B).

On the other hand, the heater (H) is generally composed of a double winding coil, the coating layer (D) is formed on the surface by electrodeposition, etc., the lead (L) is connected to the heater tab (T) Connected to an external circuit.

An impregnated cathode, also called a storage cathode, impregnates a cathode material in a porous sintered body formed by tungsten or the like to form pellets (P) to support the inner sleeve (I).

The manufacturing process of such an impregnated cathode was manufactured in the same manner as in FIG.

In FIG. 2A, a punch 20 for pressing is placed on a die 10 in which a cavity 11 of the same diameter as the pellet P is formed, and a stripper under the cavity 11 is located. stripper 30) is located.

After inserting the raw material powder T such as tungsten into the cavity 11 of the die 10, the punch 20 is lowered and the porous body of the pellet P is formed, so that the stripper 30 rises and pellets. (P) is separated from the die 10.

Then, a pellet P as shown in FIG. 2B is formed. The pellet P is impregnated with a negative electrode material, and then welded to the cylindrical cap C as shown in FIG. 2C by welding, and the cap ( The cathode K is formed by covering C) on the inner sleeve I.

However, during welding, a considerable amount of high heat flows into the pellets P, and the tungsten and cathode materials in the pellets P cannot be oxidized. In the conventional method, the welding is repeated twice, so that the temperature distribution in the pellets P Non-uniform electron emission causes a problem that the electron emission efficiency is lowered.

In addition, the pellet (P) is only 2.3mm in diameter, so assembling the fine pellet (P) to the cap (C), and then to assemble it on the inner sleeve (I) is very laborious. This is a cumbersome task.

Accordingly, an object of the present invention is to provide a method of manufacturing an impregnated cathode, which is easy to manufacture and prevents a decrease in electron emission efficiency.

Another object of the present invention is to provide an apparatus suitable for the implementation of such a method.

The method for producing an impregnated cathode, which achieves the object of the present invention, is characterized in that the pellet is integrally formed with the cap by press molding in the cup during press molding of the pellet.

Such specific features and advantages of the present invention will become more apparent from the following description of the manufacturing apparatus with reference to the accompanying drawings.

In the manufacturing apparatus shown in FIG. 3, the punch 20 is located on the die 10 having the cavity 11 of the diameter of the pellet P, as in the conventional manufacturing apparatus shown in FIG. The punch 20 supports the first punch 21 for molding the pellets P, and the cap C when the pellets P and the pellets C are temporarily held around the first punch 21. The second punch 22 is formed.

Meanwhile, the stripper 30 supporting the lower portion of the cavity 11 does not merely discharge the formed pellets P from the die 10, but has a third coupling the pellets P into the cap C. Play the role of a punch.

That is, the manufacturing apparatus shown in FIG. 3 implements the method of the present invention in which the pellet P is molded in the cap C, thereby forming the cap C and the pellet P integrally. After forming by forming the pseudo-form (P ') by the secondary molding, the pseudo-form (P') is entered into the cap (C) and secondary molding to implement a method of integrally combining the cap (C) and pellets (P). do.

This method requires a high compression ratio of about 10: 1 to form porous pellets (P) by pressing only tungsten powder without forming other binder components when forming pellets (P). This is because the cap (C) has a high probability of being crushed or burst at such a compression ratio.

Therefore, when the pseudo-molded product (P ') is primary molded to a size, for example, several percent thicker than the final pellet (P) thickness, and then enters into the cap (C) to secondary mold to the thickness of the pellet (P) cap ( The pellet P can be pressed into the cap C without being deformed or damaged by C) so that it can be combined in a customized form.

This process will be described through the angle of FIG.

When the raw material powder T such as tungsten is accommodated in the cavity 11 of the die 10 in FIG. 3a, the first punch 21 is lowered in FIG. 3b to remove the tungsten powder T in the cavity 11. Pressurization is carried out to mold the molded product P '. The thickness of this pseudo molded object P 'should just be a size larger than the final thickness of pellet P as mentioned above.

Then, in FIG. 3C, the second punch 22 descends and the cap C, which is temporarily supported on the outer circumference of the first punch 21, is brought into contact with and supported on the die 10.

In this case, the cap C may be lowered at the same time as the first punch 21 is lowered, and the second punch 22 may be subsequently lowered to support the upper end of the cap C.

Then, as shown in FIG. 3D, the stripper 30 is raised to press-form the pseudo-molded object P 'with the first punch 21 to form the pellet P at the end of the cap C. As shown in FIG.

At this time, since the pseudo-molded product P 'has a thickness slightly larger than that of the pellet P, when it is pressed to have a thickness of the pellets P, the pseudo-molded product P' is intended to expand in the radial direction, so that the pellets (C) in the cap (C) eventually. P) comes into a tight fit state and molding of the pellets P integrally formed with the cap C is completed as shown in FIG.

Thus, according to the present invention, the process of assembling the pellets (P) to the cap (C) is not only omitted, but also the welding work in this process is not necessary, so that the thermal effect is reduced, and the present invention reduces the airborne production of the impregnated cathode. And it has a big effect on the stable maintenance of electron emission efficiency.

Claims (3)

In the method of manufacturing an impregnated cathode in which a pellet of a porous material is formed by press-molding a material powder, the cathode material is impregnated therein, and then assembled into a cap to be bonded to the inner sleeve of the cathode, wherein the pellet is press-molded within the cap. And the pellet is integrally formed with the cap. The method according to claim 1, wherein the raw material powder is first molded into a cauldron having a size slightly larger than that of the pellet, and then the cauldron is secondly molded into the size of the pellet while the cauldron enters into the cap. Method for producing an impregnated cathode, characterized in that. An apparatus for producing an impregnated cathode, comprising: a die having a cavity having a pellet diameter into which a raw material powder is put; a punch for pressing the raw material powder of the cavity to form the pellet; and a stripper supporting a lower portion of the cavity. A punch having a first punch for molding the pellets, and a second punch positioned on an outer circumference of the first punch to support one end of the cap, wherein the stripper is first molded by the first punch. The apparatus for manufacturing an impregnated cathode, characterized in that the pellet is integrally formed with the cap by entering the inside of the cap and secondary molding between the first punch.