JPH07315918A - Magnetic oxide material and deflection yoke core - Google Patents

Abstract

PURPOSE:To obtain a magnetic oxide material controlled in permeability decreasing phenomenon attending the attainment of high frequency and having sufficiently high resistivity, small loss and a sufficiently high Curie point. CONSTITUTION:This magnetic oxide material consists of, by mol, 47-50.5%, in total of 43-49.5% (expressed in terms of Fe2O3) iron and 0.01-7.5% (expressed in terms of Mn2O3) manganese, 21-41% (expressed in terms of MgO) magnesium and 10 to <22% (expressed in terms of ZnO) zinc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic core material, and more particularly to an oxide magnetic material relating to a magnetic core material such as a deflection yoke core for a cathode ray tube (CRT).

[0002]

2. Description of the Related Art In recent years, consumer televisions are shifting to high definition, and there is a strong demand for higher definition in personal computer displays. Deflection yoke cores used for these need to cope with higher frequencies and larger currents, but in this case, the loss of the core becomes large, which causes a problem of heat generation. For the electromagnetic characteristics required of the deflection yoke core, it is important to keep this loss small. Therefore, the Curie point is sufficiently high (140 ° C
Above) is necessary. If the core has a small specific resistance, vertical stripes are generated on the CRT screen due to the ringing phenomenon. Therefore, a core having a specific resistance of 10 ⁶ Ω · cm or more is used. In the case of a ring type coil, it is important that the core has a large specific resistance in order to improve insulation between windings.

Usually, MgZn type ferrite is used for the deflection yoke core in terms of cost reduction. Since MgZn ferrite has a small specific resistance, MnMgZn ferrite added with Mn ₂ O ₃ is widely used to increase the resistance. However, the addition of Mn ₂ O ₃ causes a gradual decrease in magnetic permeability as the frequency increases. This permeability is 35
Although it is required to be 0 or more, this gradual decrease phenomenon is very problematic because it is necessary to obtain a stable magnetic permeability at any frequency.

As an oxide magnetic material which is a MgZn type ferrite material used at high frequency, Japanese Patent Laid-Open No. 64-72925.
And Japanese Patent Application Laid-Open No. 1-301524 are proposed,
Since the amount of ZnO is too large, the Curie point becomes too low and they are not suitable as the deflection yoke core material.

[0005]

The present invention has been made under these circumstances, and suppresses the phenomenon of gradual decrease of magnetic permeability due to high frequency, sufficiently large specific resistance, low loss and Curie point. The object of the present invention is to provide an oxide magnetic material having a sufficiently high value.

[0006]

The above objects are achieved by the present invention described in (1) to (3) below.

(1) Iron and manganese are Fe ₂ respectively
O _3, Mn ₂ O ₃ in terms of in _{Fe 2 O 3 + Mn 2 O} 3 is from 47 to 5
0.5 mol%, magnesium is 21 to 4 in terms of MgO
An oxide magnetic material, characterized in that the composition range is 1 mol% and 10 to 22 mol% of zinc (not including 22) in terms of ZnO.

(2) Iron is 43 to 49 in terms of Fe ₂ O ₃ .
5 mol%, manganese 0.01 to _{7 in} terms of Mn ₂ O ₃ .
The oxide magnetic material according to (1), which has a composition range of 5 mol%.

(3) A deflection yoke core using the oxide magnetic material according to (1) or (2).

[0010]

[Operations and effects] The gradual decrease in magnetic permeability with increasing frequency is a so-called relaxation phenomenon, which is caused by the movement of electrons on the Fe-poor side and the movement of cations on the Fe-rich side. Therefore, it is important to control the oxide composition to the stoichiometric composition. The present invention is based on the findings shown above, by suppressing the amount of Fe ₂ O ₃ and Mn ₂ O ₃ to suppress the gradual decrease of the magnetic permeability due to high frequency, the specific resistance is sufficiently large, Moreover, it is possible to obtain an oxide magnetic material having a low loss and a sufficiently high Curie point.
Further, the deflection yoke core using the magnetic material of the present invention is usually 1
It is used in the band from 0 kHz to 100 kHz.

[0011]

Specific Structure The specific structure of the present invention will be described in detail below.

In the oxide magnetic material of the present invention, iron and manganese are converted into Fe ₂ O ₃ and Mn ₂ O ₃ , respectively, and Fe ₂ O ₃ + Mn.
₂ O ₃ is 47 to 50.5 mol%, preferably 49 to 5
0.3 mol%, magnesium is 21 to 4 in terms of MgO
1 mol%, preferably 25-35 mol%, zinc is Z
10 to 22 mol% in terms of nO, preferably 15 to 2
It consists of a composition range of 1.5 mol%.

In the above composition range, iron is Fe ₂
O ₃ 43~49.5mol% in terms of the preferred 45.
0 to 49.0 mol%, and manganese is calculated to be Mn ₂ O _{3 in an} amount of 0.1
01-7.5 mol%, preferably 1.3-4.0 mo
1% composition range.

The deflection yoke core is obtained by mixing and molding these, and then sintering.

The reasons for limiting the oxide composition are as follows.

In order to have a high resistance, a low loss and to suppress the gradual decrease of the magnetic permeability, it is necessary to be within the range of the amount of Fe ₂ O ₃ + Mn ₂ O ₃ shown above. Fe ₂ O ₃ + Mn ₂ O ₃ amount is 47
If it is less than mol%, the loss becomes large, and there is a concern that the power consumption of the deflection circuit is wasted and the temperature rises. Also 50.
If it exceeds 5 mol%, the magnetic permeability gradually decreases.

If the Fe ₂ O ₃ content is less than 43 mol%, the Curie point becomes too low, and if it exceeds 49.5 mol%, the resistance becomes low.

If Mn ₂ O ₃ is less than 0.01 mol%, the loss becomes large, and if it exceeds 7.5 mol%, abnormal grain growth of oxide crystals is promoted, and the loss becomes large.

Since the stoichiometric composition of Fe ₂ O ₃ + Mn ₂ O _{3 is} the primary factor that determines the loss and the gradual suppression of magnetic permeability, MgO and ZnO play a complementary role in maintaining their proportions. Fulfill However, regarding the Curie point, ZnO
Since there is a large degree of dependence on the amount, it is necessary to control the upper limit of ZnO to less than 22 mol% for practical purposes.

The raw materials for iron, manganese, magnesium and zinc are not particularly limited as long as they are oxides after the reaction, and in addition to oxides, simple metals, carbonates, hydroxides, halides, etc. can be selected according to the reaction conditions. Can be used arbitrarily.

[0021]

EXAMPLES Fe ₂ O ₃ , Mn ₂ O ₃ and MgO as starting materials
And ZnO were weighed and blended so as to have the composition shown in Table 1, and mixed in a ball mill for 15 hours. These mixed powders were calcined at 900 ° C. for 3 hours and then pulverized with a ball mill for 15 hours. To the ferrite powder thus obtained, 10% by weight of a polyvinyl alcohol solution was added and granulated, and 1 ton /
An annular sample was formed with a pressure of cm ² .

The electromagnetic characteristics of the samples obtained by firing these samples at 1300 ° C. for 3 hours in the air were measured. The results are shown in Table 1. In addition, it was confirmed by X-ray diffraction that this sample had a substantially perfect ferrite phase.

[0023]

[Table 1]

The magnetic permeability is gradually reduced (rate of change) by (10 k
(Permeability of Hz−permeability of 100 kHz) / 10 permeability value of 10 kHz, and core loss is a value measured at 50 mT and 64 kHz.

In Table 1, samples marked with * (F
To J) are included in the scope of the present invention. In these samples, the magnetic permeability is sufficiently high and the magnetic permeability gradually decreases.
Further, the loss is small, and it is understood that the Curie point and the specific resistance are practically sufficient. On the other hand, other samples have various problems. When the Fe ₂ O ₃ content is low, the Curie point is low (A, B). When Mn ₂ O ₃ is small,
Core loss increases (C). When Fe ₂ O ₃ + Mn ₂ O ₃ is less than the range, the core loss is large (D, E), and when it exceeds the range, the magnetic permeability is gradually decreased (K, L). It is obvious that all of these are not practical. Also Z
If the amount of nO is too large, the Curie point becomes extremely low (M), which is also not suitable for practical use.

A deflection yoke core was prepared using the oxide magnetic material of the present invention, and its electromagnetic characteristics were measured.
Very good properties were obtained.

[0027]

According to the present invention, by controlling the composition of Fe ₂ O ₃ + Mn ₂ O ₃ , the core loss is sufficiently low, the gradual decrease of the magnetic permeability due to the high frequency can be suppressed, and the Curie point and the specific resistance are sufficient. It is possible to provide a high oxide magnetic material.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01J 29/76 A

Claims (3)

[Claims] 1. Iron and manganese are Fe ₂ O ₃ and M, respectively.
Fe ₂ O ₃ + Mn ₂ O ₃ is 47 to 50.5 mo in terms of n ₂ O _3.
1%, magnesium is 21 to 41 mol in terms of MgO
%, Zinc is 10 to 22 in terms of ZnO (22 is not included)
An oxide magnetic material having a composition range of mol%. 2. Iron is 43-49.5 mo in terms of Fe ₂ O _3.
1%, manganese is 0.01 to 7.5 mo in terms of Mn ₂ O _3.
The oxide magnetic material according to claim 1, having a composition range of 1%. 3. A deflection yoke core using the oxide magnetic material according to claim 1.