JPS5916251A - Manufacturing method for deflection yoke core - Google Patents

Abstract

PURPOSE:To remarkably reduce the dimensional allowable value and provide the characteristics that will not cause any problems in practical use by enclosing the whole surface of a ferrite sintering body core with a mixture between ferrite sintering body powder or magnetic body powder with soft magnetism and synthetic resin material by means of injection molding, etc. CONSTITUTION:An Mn-Mg-Zn ferrite core sintering body for a deflection yoke is molded by the general ferrite manufacturing method and is obtained as a sintering body (where, the dimensional volume of the sintering body is 80% of the specified final product dimensional volume. In addition, chucking during widing and grooves for positional selection are removed). Then a desired deflection yoke core is obtained by installing this ferrite sintering body core at a mold center for injection molding, filling the gap between the mold and the ferrite sintering body core with a mixture between the ferrite sintering body powder, magnetic powder (iron powder), and the epoxy resin as the bonding material all over the surface, hardening it, and taking it off from the mold.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a deflection yoke core used in televisions and the like.

In recent years, the importance of color cathode ray tubes has been expanded to industrial use due to the spread of DA and OAD. Due to this, dimensional manufacturing errors between the cathode ray tube and the deflection yoke will appear as misconvergence, and as displays are becoming more dense, it is important to improve the performance of the deflection yoke as well as the cathode ray tube. It's becoming better. Misconvergence is caused by insufficient precision of the spring wire and misalignment of the axes between the horizontal and vertical coils, among others, deformation of the magnetic core material for the deflection yoke, change in thickness, dimensional accuracy, etc. are major causes. Therefore, in order to hold a small pageant, it is necessary to improve quality, crocheting, and assembly accuracy more than ever before, and to reduce variation.

Traditionally, magnetic material (sintered powder) was mixed with a binder (usually synthetic resin) and introduced into a mold, and then the binder was hardened.Dimension tolerances are the tolerances for the dimensions of the mold. However, it is known that the magnetic permeability μ of such cores is low for most applications. Magnetic deflection yoke cores have the following major drawbacks.

In other words, since the resin portion of the core is non-ferromagnetic and exists between the magnetic particles, all the magnetic particles are separated by gaps. This reduces the effective permeability μe of the core, and this reduction is so great that the intrinsic permeability μ of the magnetic material plays only a minor role.

On the other hand, as a means to reduce misconvergence, it has been partially practical to grind the entire surface of the deflection yoke sintered core with diamond, etc., but when considering the processing cost, it is extremely expensive and large quantities are required. It is difficult to adopt it in production.

The present invention provides a sintered product for a deflection yoke obtained by a general pressing method using a mixture based on at least one of a sintered powder having soft magnetic properties or a ferromagnetic powder of metal and a binder (synthetic resin, etc.). By casting the entire surface of the body core by injection molding or the like, the present invention achieves a dimensional tolerance of ±0.1%, compared to the conventional dimensional tolerance of ±1%, and the magnetic and electrical properties are better than the conventional ones. It is an object of the present invention to provide a deflection yoke core which has characteristics comparable to those of other products and which can be manufactured at a lower cost.

Hereinafter, a detailed explanation will be given based on examples.

Example 1 For the purpose of the present invention, a Mn-Mg-Zn ferrite core sintered body for a deflection yoke was molded and sintered using a general ferrite manufacturing method (however, the dimensions of the sintered body were as large as the specified dimensions and volume of the final product). 80% of the volume.Also, the grooves for chucking and position selection during winding were removed), and then the ferrite sintered core was placed in the center of a mold for full injection molding, etc. Then, the gap between the metal mold and the ferrite sintered body core is completely filled with a mixture of ferra() sintered body powder, magnetic powder (iron powder), and epoxy resin as a binder, and the mixture is hardened and removed from the mold as desired. Obtained a deflection yoke core.

FIG. 1 shows a schematic cross-sectional view of the deflection yoke core obtained by this example. The deflection yoke core thus obtained has a position setting during winding that is different from a fired body and has less deformation, so the winding accuracy is improved, and the time adjustment for taking the cathode ray tube is easier, which significantly improves productivity and reduces misconvergence. It is something that can be made smaller.

Example 2 A MnZn 7-type sintered body for the deflection yoke of the present invention was obtained by a general ferrite manufacturing method (the dimensional volume of the sintered body was 60% of the dimensional volume of M desired). (In addition, the chucking and position setting grooves for @ lines have been removed). For this sintered core,
Injection molding was carried out using the same process as in Example 1. However, as a magnetic material for injection, MnMg21, which has high resistance,
A mixture of n-ferrite sintered powder and synthetic resin was used. The resulting deflection yoke was as desired.

Example 3 For the deflection yoke of the present invention, a MnMgZn-based seven-layer lycore sintered body was produced by a general ferrite manufacturing method.

The dimensional volume of this sintered body was 70% of the desired final deflection yoke core dimensional volume. Also, grooves for chucking and position setting during winding have been eliminated.

The obtained ferrite sintered core is placed in the center of an injection mold, and then a mixture of ferrite sintered powder and polyester resin as a binder is poured into the gap between the mold and the ferrite sintered core. After filling the entire surface, it was cured and removed from the mold to obtain a desired deflection yoke core. Table 1 shows the properties of products obtained by varying the mixing ratio of the magnetic material powder as a soft magnetic mixture and the polyester resin as a binder, and the electrical characteristics of the deflection yoke core in the open magnetic path. .

The results obtained from Examples 1 to 3 in Table 1 are only examples of the present invention, and the soft magnetic material is not limited to querite powder, and various forms of iron powder available on the market can be used. It has been found that good results can be obtained with a metal powder having a . Further, the organic binder which is the binder may be either thermoplastic or thermosetting. It is preferable that these resins have substantially the same thermal expansion as the ferrite sintered body. It is good to select it in a timely manner according to the molding method.

The mixing ratio of magnetic powder and binder is within a certain range (288~
9:1), the lower limit being determined by the magnetic properties of the mixture and the upper limit being determined by the moldability of the mixture and the mechanical properties of the final product, the deflection yoke core.

Table 2 shows the degree of deformation and dimensional accuracy of the deflection yoke core obtained by the present invention. Compared to the conventional deflection Meek core made of sintered ferrite, the deviation is significantly improved, and there is no deterioration in characteristics, so it has great industrial advantages as a magnetic core for graphics, monitors, and displays.

As detailed above in Table 2, the present invention is characterized in that the entire surface of a ferrite sintered core obtained by a general ferrite manufacturing method is coated with a ferrite sintered powder or a magnetic powder having soft magnetism and a synthetic resin. A method for manufacturing a deflection yoke core for high M applications that can significantly reduce the dimensional tolerance by injection molding a mixture with materials, has characteristics that pose no problem in practical use, and can be manufactured at low cost. This is what we provide.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of an embodiment according to the present invention. 1: Near ferrite sintered body, 2=Mixture of ferrite sintered body powder, magnetic powder, and epoxy resin. Agent Hiroshi Kajihara 2q.

Claims (1)

[Claims] 1. In a method for manufacturing a deflection yoke core, a core made of a ferrite sintered body is placed approximately at the center of a mold,
A method for manufacturing a deflection yoke core, comprising filling a gap between the mold and the ferrite sintered core with a mixture of soft magnetic powder and a synthetic resin material. 2. Claim 1 provides that one or more of ferrite sintered powder or metal magnetic powder having soft magnetism and a synthetic resin material are used in the gap between the mold and the ferrite sintered core. A method for manufacturing a deflection yoke core characterized by filling the core with. 3. The method for manufacturing a deflection yoke core according to claim 1, wherein the volume of the ferrite sintered body occupies 60% or more of the press-formed deflection yoke core.