JPS5880122A - Magnetic head - Google Patents

Abstract

PURPOSE:To prevent the squeak of a tape, by covering the contact part between a magnetic tape and a magnetic head with exclusion of a magnetic core which has a contact with the tape with a material which has a smaller heat expansion coefficient than the magnetic core and has the lubricity. CONSTITUTION:The magnetic cores 1a-1d and 1'a-1'd are formed to face an opening part 6 of a shielding case 2 and then put together in a body with a fixing material 3. The material 3 has a smaller heat expansion coefficient than the magnetic cores and has the lubricity. For instance, as the material 3, one of graphite, MOS2, talc, carbon fluoride, boron nitride, etc. is used with addition of 1-50wt% resin in case ''Permalloy '', Sendust or ferrite is used for the magnetic core.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic head, and more particularly to a magnetic head in which the contact portion between a magnetic core and a magnetic recording medium is improved.

When a magnetic recording medium such as a magnetic tape runs in contact with a magnetic head, tape running noise called so-called tape squeal occurs. This tape squeal is caused by the fact that the magnetic layer of the magnetic tape comes into contact with the fixing material for fixing the magnetic core that faces the opening of the magnetic case, and the friction causes uneven tape running.

For example, an auto-reverse cassette deck for automobiles has a magnetic
A 4-channel magnetic head with four permalloy cores with a radius of 1ONM on the sliding surface was attached, and the results of experiments were conducted while varying the operating environment using a C90 cassette tape for normal position, as shown in Figure 1 (a). ),
Shown in (b). The experiment shown in Figure 1 (aL (b)
5%) and 65°C (humidity 65 to 70 degrees), and the time until tape squeal occurred was measured using experimental design method C2.

As a result, with a risk rate of 1%, as shown in Figure 1 (a),
It can be seen that the higher the temperature, the faster the tape squeal occurs. The contribution rate of temperature to the squeal at this time is 8
2.0%, and the contribution rate of humidity was 1.49 cm.

On the other hand, when we conducted a different experiment using a C90 cassette tape for normal position, which was different from the one used in the experiment shown in Figure 1(a), we found that
As shown in b), it was again confirmed that the higher the temperature, the earlier the tape squeal occurred at the risk factor of 1. At this time, the contribution rate of temperature to tape squeal was 966%, and the contribution rate of humidity was 0.92%.

From the results of these experiments, it has been found that tape squeal is more likely to occur at high temperatures.The reason why tape squeal is more likely to occur at high temperatures is that the magnetic layer of the magnetic tape softens at high temperatures, causing a problem with the magnetic head. One reason is that the adhesion of the contact surface increases, frictional resistance increases, and the tape runs smoothly.

In addition, since the magnetic core is generally fixed to the shield case (thermosetting resin is used near the magnetic core,
Its thermal expansion coefficient is 30X10-6~5000-6de
', and the permalloy used for the magnetic core is 10-
Because it is larger compared to 6-16 cut 0-0-6de',
This thermosetting resin comes into contact with the magnetic tape, softens, and has higher adhesion than the magnetic core.

Therefore, although not shown in the figure, we conducted another experiment in which the contact surface of the magnetic tape was made of only permalloy, and the magnetic tape was cured at 55°C using a thermosetting device.
When we measured the time until tape squeal occurred in a 50% humidity environment, the tape squeal occurred in about 1 hour with the thermosetting resin only, and the tape squeal occurred even after 130 hours of running with the permalloy only. There was no.

Therefore, it can be seen that the occurrence of tape squeal depends on the temperature (2) and also on the frictional resistance between the magnetic layer of the magnetic tape and the thermosetting resin that fixes the core at the contact surface between the magnetic tape and the magnetic head. 0 The present invention has been made to eliminate the above-mentioned conventional drawbacks, and an object of the present invention is to provide a magnetic head configured so that tape squeal does not occur.

In order to achieve the above object, the present invention uses a material that has a coefficient of thermal expansion smaller than that of the magnetic core and has lubricating properties for the part where the magnetic tape and the magnetic head come into contact, leaving the magnetic core in contact with the magnetic tape. We adopted a structure covered with

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 2 and FIGS. 3(a) and 3(b) illustrate an embodiment of the present invention, and are a front view and an A-N of FIG.
Cross section 1. The cross-sectional view taken along line B-B' in FIG. 2 is shown. In the drawings, reference numerals 18 to ld and l'a to 1'd indicate magnetic cores, which face the opening 6 of the shield case 2. These magnetic cores 1a to 1d and l'a to I'd are fixed members 3
(In this embodiment, the inside of the opening 6 is entirely covered except for the magnetic cores 1al, 1d, and 1'a to 1'd.

As shown in FIGS. 3(a) and 3(b), contact between the magnetic tape 5 and the magnetic cores 1a to 1d, 1'a to 1'd occurs because the magnetic tape 5 faces the opening 6. It is for the core.

Therefore, the parts of the gap 4 of the magnetic cores 1a to 1d11'a to 1'd that are required to come into contact with the left and right magnetic tapes 5 are left over and covered using the fixing material 3. In a) and (b), what is indicated by the reference numeral 7 is a tape pad.

By the way, the material exemplified as the fixing material 3 needs to have a coefficient of thermal expansion smaller than that of the magnetic core and have lubricating properties. For example, the coefficient of thermal expansion of the magnetic core is approximately 11~12X10-6deg-1y for noni-malloy, approximately 14-16x10-'deg-' for high-hardness permalloy, approximately 13-18x10-'deg-' for sendust, and approximately 14-16x10-'deg-' for Sendust, It is about 9 to 12 x 10-6 deg-'.The materials exemplified as the fixing material 3 include materials with smaller thermal expansion than these materials, such as Graphi (GRAPH), MoS2
It is preferable to use a small amount of talc, fluorocarbon, boron nitride, etc. and add 1 to 50 inches of resin (weight ratio). For example, graphite has a coefficient of thermal expansion of 0.6 to 5.3.
It is known as a friction reducing agent and a lubricant. FIG. 4 is a graph similar to FIGS. 1(a) and (b). In Fig. 4, a mixture of graphite with a trace amount of resin, that is, an epoxy resin with a weight ratio of 20 cm as a binder, and covering the vicinity of the magnetic cores 18 to ld and l'a to I'd exhibits characteristic 8, and compared to the conventional The sample covered only with thermosetting resin exhibited characteristic 9. Figure 4 shows measurements taken under the same conditions as in Figure 1 (at, (bl).As can be seen from Figure 4, the conventional product no longer chirps or bleeps in about 25 hours at a temperature of 45°C. However, there was no tape squeal in the Laffite case until 160 hours had passed.

In other words, when the magnetic tape runs (see Figure 3(b)), the area where the magnetic tape and the magnetic head come into contact is focused only on the magnetic core, and the area around it has a small coefficient of thermal expansion and is lubricated. Since the magnetic tape comes into contact with a magnetic substance, the adhesion of this area to the magnetic tape is significantly reduced, and an increase in frictional resistance can be significantly suppressed, thereby eliminating the occurrence of tape squeal.

As is clear from the above description, according to the present invention, the coefficient of thermal expansion is smaller than that of the core over the entire surface of the opening, excluding the magnetic core that faces the opening of the shield case of the magnetic head, and the magnetic core has lubricity. Since it uses a structure covered with a substance, it has the excellent effect of eliminating uneven running of the magnetic head and completely eliminating tape squeal.

[Brief explanation of the drawing]

Figures 1 (al and b) are graph diagrams of a conventional example explaining the relationship between temperature and time until tape squeal occurs; Figure 2 is a front view explaining an embodiment of the present invention; Figure 3 (a
)t (b) is a vertical side view and a cross-sectional plan view of FIG. 2, and FIG. 4 is a graph diagram comparing the example of the present invention and the conventional example regarding temperature and tape squeal. la~ld, t'a~l' d-magnetic core 2...
Shield case 3... Fixing material 4... Gap 5... Magnetic tape 6... Opening 45 55 65 (@C) Electron 45 55 65 ('C)m Fig. 2 Fig. 3 ((1 ) Figure 3(b) 1″a 3 4 1CI Figure 14 Procedural Amendment (November 27, 1980 Dear Commissioner of the Patent Office 1, Indication of Case 1982 Patent Application No. 175590 2,
Name of the invention: Magnetic head 3. Relationship with the case of the person making the amendment: Name of patent applicant: Canon Electronics Co., Ltd. 4, Agent.
Telephone: 03 (268) 2481 @) 6, Detailed explanation of the invention in the specification to be amended 7, Contents of the amendment

Claims (1)

[Claims] A magnetic head (2) in which a magnetic core and a magnetic recording medium are in contact with a part of an opening provided in a case of the magnetic head.
A magnetic head characterized in that substantially the entire surface of the opening, except for the magnetic core facing the opening, is covered with a material that has a lower heating rate than the magnetic core and has lubricating properties.