JPH03141015A - Magnetic head - Google Patents

Abstract

PURPOSE:To enhance the wear resistance and to improve the flatness of the sliding surface by forming both end extension part in the longitudinal direction which come into contact with a recording medium of a magnetic core chip by non-magnetic ceramics, and also, prescribing the difference of thermal expansion coefficients of these parts and the magnetic core chip. CONSTITUTION:In a magnetic head constituted by inserting and holding a magnetic core chip 3 having at least one magnetic gap by left and right holders 1, 2 made of non-magnetic ceramics from both its sides, the magnetic core chip 3 is constituted of ferrite. Extension parts 4 provided serially on both end parts in the longitudinal direction of the magnetic core chip 3 and coming into contact with a recording medium consist of the same quality as the left and the right holders 1, 2, and also, the difference of thermal expansion coefficient to the magnetic core chip 3 is set to the maximum 10 X 10<-7>(1/ deg.C). Accordingly, the part which is apt to be worn all comes to non-magnetic ceramics whose wear resistance is high, a step difference to the middle magnetic core chip 3 is not generated, and the magnetic head in which flatness of the sliding surface is satisfactory is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic head used in floppy disk drives and hard disk drives.

[Prior Art] Figure 5 shows a typical magnetic head for a floppy disk disclosed in Japanese Patent Application Laid-Open No. 63-317918, in which a magnetic core chip (3) made of ferrite is mounted in a left-hand holder made of non-magnetic ceramics. (It is sandwiched between 11 and the right holder (2) of the same quality, and these are glued together.

Figure 6 shows a magnetic head disclosed in Japanese Patent Application Laid-Open No. 61-222008, in which a hole is made in the center of an integrated holder (5) made of non-magnetic ceramics and a magnetic core chip made of ferrite is attached to the magnetic head. It is fitted into a hole and glued together.

Furthermore, FIG. 7 shows a typical hard disk magnetic head disclosed in Japanese Patent Application Laid-open No. 1-146117, which has an integrated holder made of non-magnetic ceramics as shown in FIG.
A notch is formed in a part of the end of the magnetic core 5), and a magnetic core chip (3) made of ferrite is inserted into the notch and bonded together.

By the way, in response to the recent increase in the density and transfer rate of magnetic recording devices, the flatness of the sliding surface with the recording medium has been reduced to 0.05μ.
m or less, the magnetic core chip must be made as small as possible in order to improve the efficiency of the magnetic circuit, and it is also required to have excellent wear resistance that can withstand high-speed rotation.

Comparing the abrasion resistance of ferrite and non-magnetic ceramics used in the above-mentioned magnetic head, non-magnetic ceramics such as BaTiOs and CaTiOs are generally higher, and since ferrite is easily worn out, the contact pressure shown in Fig. 1 is higher. It is better to use non-magnetic ceramics near the interference fringes (a).

[Problem to be solved by the invention] Since the conventional magnetic head is configured as described above,
In the structures shown in Fig. 5 and Fig. 7, the ferrite exposed on the sliding surface is easily worn out, and if the structure shown in Fig. 6 requires high dimensional accuracy, the cost will be high. The structure shown in the figure had problems such as an increase in the size of the magnetic circuit and a decrease in efficiency.

This invention was made in order to improve the above problems, and aims to provide a magnetic head that has high wear resistance (and good flatness of the sliding surface) and allows the efficiency of the magnetic circuit to be designed arbitrarily. purpose.

[Means for Solving the Problems] In the case of the present invention, extension portions (41 [4
1 is made of non-magnetic ceramics, and the difference in thermal expansion coefficient between this and the magnetic core chip (3) is at most 10x 1.
It is set to 0-'(1/''C).

[Function J] Since the extensions formed at both ends of the magnetic core chip in the longitudinal direction that contact the recording medium in the present invention have high wear resistance, the ferrite magnetic core chip between them is protected.

[Example] An example of the present invention will be described below. In other words, Figure 1 shows the case where the magnetic gap is located approximately at the center of the magnetic core chip in the longitudinal direction, where (1) is the left holder made of non-magnetic ceramics, (2) is the right holder made of the same material, and (3) is the right holder made of the same material. Magnetic core chip, consisting of ferrite (
4) is an extension part that is provided in series at both ends of the magnetic core chip (3) and comes into contact with the recording medium.
1 (2), and the difference in thermal expansion coefficient between the magnetic core chip (3) and the magnetic core chip (3) is at most 10x 10-'(1/'C
) is composed of non-magnetic ceramics.

Therefore, the parts where the first interference fringes (a) are formed when the optical flat is brought into contact with the sliding surface, that is, the parts that are easily worn, are all made of highly wear-resistant non-magnetic ceramics. Also, when performing blend R processing, the polishing speed is almost the same.

The flatness is good, and the level difference between the left and right holders and the magnetic core chip between them can be suppressed to 0.05 um or less.

FIG. 2 is an explanatory view of the assembly process of the embodiment shown in FIG. 1. First, the above-mentioned non-magnetic ceramic extensions (4) are integrally bonded to both ends of the magnetic core chip (3), The right holder (1) and the left holder (2) are sandwiched from both sides and laminated and bonded together. Further, the magnetic head shown in FIG. 1 is obtained through a polishing process to improve the flatness and a blend R process to form a blend R.

FIG. 3 is a perspective view showing another embodiment of the present invention, in which the magnetic gap is located near the outflow end of the magnetic head, which is a structure often employed in hard disks and large-capacity FDDs. In this case, the magnetic gap is the first interference fringe (
Since it is close to (a), particularly wear resistance and flatness are required, but there is no particular problem because it is protected by the extension part (4) made of non-magnetic ceramics.

Note that the left and right holders (1) (2) and the extensions (4) at both ends of the magnetic core chip do not necessarily need to be made of the same material.On the other hand, regarding flatness, it depends on the heat of the ferrite and non-magnetic ceramic used. It depends on the difference in expansion coefficient.

Figure 4 shows the thermal expansion coefficient and moisture resistance test (60℃).

This is the result of measuring the level difference between the magnetic core chip and the left and right sliders including the extension part after 1.72 hours (90% R) using a stylus roughness meter.The larger the difference in thermal expansion coefficient, the greater the level difference. In order to suppress the difference to 0.05 μm or less, it is necessary to set the above-mentioned difference in thermal expansion coefficient to a maximum of 10×10 (1/”C).

Table 1 shows the results of a comparison with conventional examples in terms of wear resistance and flatness.

Table 1 Fig. 1 is a perspective view showing one embodiment of the magnetic head of the present invention, Fig. 2 is an assembly process diagram thereof, Fig. 3 is a perspective view showing another embodiment of the magnetic head of Fig. 1, and Fig. 4 is a perspective view showing an embodiment of the magnetic head of the present invention. 5, 6 and 7 are perspective views showing conventional magnetic heads, and FIG. 8 is an exploded view of FIG. 7.

In the figure, (1) is the left holder, and (2) is the right boulder.
(3) is a magnetic core chip, and (4) is an extension part.

These are the numbers after the bus.

[Effects of the Invention] As described above, according to the present invention, since the extensions at both ends of the magnetic core chip in the longitudinal direction that contact the recording medium are formed of non-magnetic ceramics having the above characteristics, there is no difference in level between the magnetic core chip and the intermediate magnetic core chip. This has the effect that generation is eliminated and a magnetic head with good flatness of the sliding surface can be obtained at low cost.

[Brief explanation of the drawing]

Claims (1)

[Claims] In a magnetic head consisting of a magnetic core chip having at least one magnetic gap, and left and right holders made of non-magnetic ceramics that sandwich the magnetic core chip from both sides, the magnetic core chip is made of ferrite, and both longitudinal ends of the magnetic core chip are made of ferrite. The extension part provided in series and in contact with the recording medium is made of non-magnetic ceramics, and the difference in thermal expansion coefficient between this part and the magnetic core chip is at most 10x.
A magnetic head characterized in that the temperature is set at 10^-^7 (l/°C) to eliminate the generation of a step between the two.