JPH0335403A - Magnetic head - Google Patents

Abstract

PURPOSE:To prevent dust pickup and to stabilize electromagnetic conversion characteristics by providing hollow grooves to prevent the sliding contact of a perpendicular part with a recording medium on a recording medium sliding surface and forming a parallel part by using a resin having hollow holes on the sliding surface. CONSTITUTION:A hollow granular material 5 having 1 to 200mum bore is packed into an epoxy resin 4 and is used as a resin for fixing. After this resin is cast into a shielding case 2 and is cured, the sliding surface side of the magnetic head is ground to form the fine hollow holes on the sliding surface. The growth of the dust sticking to the part parallel with the medium sliding direction is, therefore, stopped by the hollow holes. Further, the fixing material in the part perpendicular to the sliding direction is removed by grinding to from the hollow grooves 6 perpendicular to the sliding direction. The resin for fixing existing at the end of magnetic cores 1a, 1b parallel with a gap G does not, therefore, come into sliding contact with a magnetic tape 3. The pickup of the dust is obviated in this way in spite of the long-time sliding and the deterioration of electromagnetic conversion characteristics and the generation of stick-slip are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic head, and more particularly to a magnetic head in which magnetic cores abutted across a magnetic gap are fixed within a shield case with a fixing resin.

[Conventional technology]

Conventionally, in magnetic heads of the type in which the magnetic core is fixed to the shield case using a fixing resin, as a countermeasure against dust adhering to the head sliding surface from the magnetic tape, a fixing device that exposes minute recesses on the sliding surface is used. Structures in which the fixing resin is formed in resin, and structures in which grooves are provided substantially parallel to the gap to prevent the fixing resin from coming into contact with the magnetic tape are known.

Fig. 3 is an external perspective view of a conventional magnetic head with concave holes formed on the surface of the fixing resin, and Fig. 4 shows the magnetic head of Fig. 3 in a Y-
A sectional view taken along the dashed line Y', and FIG. 5 is an enlarged view of the main part of FIG. 4.

In the figure, 1a and lb are half magnetic cores butted together via a magnetic gear G, 2 is a shield case, 3 is a magnetic tape, and 4 is a fixing resin. As shown in FIG. 5, a hollow chamber 5 is provided in the resin 4, and on the medium sliding surface 7, this hollow chamber 5 becomes a recessed hole. 8 is a terminal of the magnetic head, and 9 is a winding. By providing the recessed holes on the medium sliding surface 7 in this manner, the growth of attached dust can be suppressed.

6th r1! J is parallel to the gap (perpendicular to the media sliding direction)
FIG. 2 is an external perspective view showing the structure of a conventional magnetic head in which grooves are provided. Components in the figure that are similar to those in FIG. 3 are given the same numbers. Reference numeral 6 indicates a groove provided on the medium sliding surface, and the groove 6 prevents the fixing resin 4 at the ends of the cores la and lb from coming into sliding contact with the magnetic tape 3, and prevents dust from entering the resin 4 in this area. This suppresses the adhesion of dust and the growth of dust in this area.

[Problem that the invention is trying to solve] However,
In the conventional example shown in FIG. 3, dust consisting of magnetic powder, binder, etc. that has peeled off from the magnetic tape 3 adheres to the fixing resin 4 at a position far from the gear G where the pressure of the tape 3 is weak. gradually grows until it reaches gear G, which has the strongest compression force, increasing spacing loss and causing so-called tape squeal due to stick slip.

As shown in FIGS. 4 and 5, the magnetic core 1 and the magnetic tape 3 are configured to gradually separate from each other at a constant angle .theta. due to the contour effect. Therefore, the pressure force of the magnetic tape 3 is maximum near the gap, and becomes zero from the point where the tape separates from the fixing resin 4. According to detailed experiments,
The thin part of the fixing resin shown in Figure 5 has fewer recesses, but
Because the depth is very shallow and the contact force is weak, dirt is dropped and easily fills the shallow depression, and eventually the dirt attached there grows to the position of gear knob G. was confirmed.

In addition, the width dimension of the magnetic core is generally 3,72tO,0
6, whereas the width of the magnetic tape 3 is 3. It has become a s1w theory. Therefore, in the magnetic head shown in FIG. 6 as well, the magnetic tape 3 and the fixing resin 4 come into contact with each other over a nominal width of 0.09 mm on the sliding surface of the magnetic head. Although this contact is minute, it has been confirmed that once dust adheres to this position, it gradually increases and extends to the vicinity of the gap, eventually causing spacing loss and tape squeal.

Against this background, it is an object of the present invention to provide a magnetic head that can effectively prevent dust from adhering to the sliding surface of a recording medium and provide stable electromagnetic conversion characteristics.

[Means for solving problems]

For this purpose, according to the present invention, the magnetic cores which are abutted across a magnetic gap are fixed by a fixing resin having a portion parallel to the sliding direction of the medium and a portion perpendicular to the sliding direction of the recording medium on the recording medium sliding surface side. A magnetic head fixed in a shield case, wherein a concave groove is provided on the recording medium sliding surface to prevent the vertical portion from coming into sliding contact with the recording medium, and the parallel portion is placed on the sliding surface. It was made of resin with recessed holes.

[Effect]

According to the magnetic head configured as described above, since a recess is provided in the surface of the parallel portion by the hollow chamber, the growth of dust adhering to this portion is stopped by the recess. Therefore, even when the magnetic recording medium is slid for a long time, there is very little dust adhesion, especially from the resin parts where dust tends to stick.
By eliminating the migration of dust as it grows to the magnetic core, where dust is difficult to adhere to, it is possible to prevent deterioration of electromagnetic conversion characteristics and the occurrence of stick-slip phenomena even when the magnetic recording medium is slid for a long time.

〔Example〕

Hereinafter, specific examples will be explained.

FIG. 1 is an external perspective view of a magnetic head as an embodiment of the present invention, and FIG. 2 is an x-x
' This is an enlarged view of the main part of the cross section.

In these figures, 1a and lb are half magnetic cores, 2 is a shield case, and 4 is a fixing resin made of epoxy resin. A hollow chamber 5 is provided in the resin 4.

The hollow chamber 5 is a hollow fine particle, the thickness of which is set to several percent of the diameter, and the outer diameter and inner diameter are approximately equal. These fine particles dispersed in liquid epoxy are cast around a magnetic core, hardened, and then ground, thereby exposing the fractured surfaces of the hollow fine particles 5 and forming concave holes on the surface. The part of the resin 4 next to the core that contacts the gear G (the central part in Figure 2) comes into sliding contact with the magnetic tape, but the part parallel to the gear G, that is, the end position of the magnetic cores la and lb (medium sliding surface) The fixing resin in the portion perpendicular to the magnetic tape 3 is configured to not come into sliding contact with the magnetic tape 3 due to the groove 6.

The method for forming the recessed hole is to use an epoxy resin filled with hollow granular material 5 as the fixing resin as described above, and after hardening it in the shield case, grind the sliding surface side of the magnetic head. By this, fine recesses can be formed on the sliding surface. Further, by removing the fixing material in the portion perpendicular to the medium sliding direction by grinding, a groove perpendicular to the medium sliding direction can be formed.

Further, the hollow granular material 5 to be filled is a balloon made of plastic, ceramics, glass, etc., and the inner diameter of the particles 5 is 1 μm to 200 μm.

Further, the filling of the epoxy resin is uniformly dispersed, and the amount of filling is determined so that the ratio of the area occupied by the recessed holes to the sliding surface is 20% or more.

In other words, the size of this recessed hole and the ratio of the recessed hole in the fixing resin that forms the sliding surface with the magnetic tape are values that can suppress the growth of attached dust, and the diameter is μm. It is necessary that 20% or more of particles with a diameter of ~200 μm are uniformly dispersed.

If the diameter is less than 1 μm, it is too small and the growth of dust cannot be suppressed, and if the diameter is 20011 m or more, the tape is pushed into the concave part of the cassette tape where the pad presses the magnetic tape against the magnetic head, and the magnetic powder on the tape is The tape will peel off at the edges of the recessed portion, which will shorten the life of the tape. If the proportion of the concave portions of 1 μm to 200 μm in the fixing resin is not 20% or more, the effect of suppressing the growth of dust will not be sufficiently exhibited.

In addition, the epoxy resin is filled with not only hollow particles but also other inorganic fillers. It is also possible to use it in combination with solid granular materials such as SiO2 and CCO3.

Next, test results will be explained in order to clarify the difference in effectiveness between this embodiment and the conventional example. First, a magnetic head having a structure roughly shown in FIG. 1 was fabricated as the magnetic head of this example. An average particle size of 50 μm is added to the epoxy resin as a fixing resin.
A glass balloon with a specific gravity of 0.4 was added so that the area ratio of the concave portion on the sliding surface was 50%. As Conventional Example 1, a fixing resin used to create a magnetic head having the structure shown in FIG. 3 had the same composition as the magnetic head of the embodiment.

Furthermore, as Conventional Example 2, a magnetic head with a tank bottom as shown in FIG. 6 was created. As the resin for fixing this head, an epoxy resin in which 50% of Si02, which is generally used solid particles, was added was used.

These magnetic heads were placed in an atmosphere with a temperature of 55°C and a humidity of 50% RH as an accelerated test to evaluate dust buildup, and the magnetic tape was run to determine the time at which tape squeal occurred and changes in playback frequency characteristics (10 KHz/315 Hz) every 50 hours. was measured.

The test was conducted on five samples for each sample, and the average value X and standard deviation S of the results are shown in Table 1.

As is clear from Table 1, in the magnetic head of this example, the time until tape squeal occurs is 3 times longer than that of the conventional example.
It can be seen that the improvement is more than double, and that the deterioration of the reproduction frequency is extremely small.

In other words, in the magnetic head of this embodiment, there is little dust adhesion, and even if it does adhere, the adhesion area is small, so that it is peeled off by the magnetic tape before it grows much. For this reason, the deterioration of the reproduction frequency does not increase over time and occasionally recovers, whereas in the conventional example, dust gradually grows and eventually becomes unmeasurable.

In the above example, a method was shown in which hollow granular material was added to the fixing resin at right angles to the gap on the sliding surface of the magnetic head and beside the magnetic core, and a concave hole was formed by grinding. In this method, for example, fine holes may be made in this area by irradiation with a laser beam, or a substance that is easily etched may be added to the resin in advance, and the substance may be removed by etching after the sliding surface is formed. Even if a fine hole is formed, a concave hole can be formed in the same way, and the same effect can be obtained by appropriately selecting the diameter of the concave hole and the area occupied within the sliding surface.

Further, magnetic heads to which the present invention can be applied include various heads for audio, VTR, computers, etc., and are applicable to various magnetic heads that record and reproduce information by sliding on a magnetic recording medium. It is possible.

〔Effect of the invention〕

As explained above, according to the present invention, even when used for a long time, dust etc. do not adhere to the vicinity of the gap, there is little deterioration of electromagnetic conversion characteristics, and stick-slip phenomenon is prevented. It is possible to obtain a magnetic head with no magnetic head.

[Brief explanation of drawings]

FIG. 1 is an external perspective view of a magnetic head as an embodiment of the present invention, FIG. 2 is a sectional view of a main part of the magnetic head shown in FIG. 1, and FIG. 3 is an external perspective view showing an example of a conventional magnetic head. 4 is a cross-sectional view of the magnetic head shown in FIG. 3, FIG. 5 is an enlarged view of a main part of the cross-section shown in FIG. 4, and FIG. 6 is an external perspective view showing another example of the conventional magnetic head. In the figure, 1a and lb are the magnetic core half-closed, 2 is the shield case,
3 is a magnetic tape, 4 is a fixing resin, 5 is a hollow chamber for forming a recessed hole, 6 is a recessed groove, and 7 is a recording medium sliding surface. 2nd concave

Claims (1)

[Claims] A magnetic head in which magnetic cores abutted across a magnetic gap are fixed in a shield case by a fixing resin having a portion parallel to the sliding direction of the medium and a portion perpendicular to the sliding direction of the medium on the recording medium sliding surface side, The recording medium sliding surface has a groove that prevents the vertical portion from coming into sliding contact with the recording medium,
A magnetic head characterized in that the parallel portion is formed of resin having a recessed hole on the sliding surface.