JPS63211109A - Magnetic head - Google Patents

Abstract

PURPOSE:To decrease the electric charge by sliding contact friction of a sliding contact surface with a recording medium by embedding blocks contg. a specific material into a part of the sliding contact surface of a magnetic head. CONSTITUTION:The blocks 8 are embedded in the sliding contact surface 7 of the magnetic head in such a manner as to expose the surfaces thereof adjacently to both side edges on the upper stream side and down steam side in the tape traveling direction of the respective magnetic cores 1. The block 8 consists of a molding of a resin (e.g.: polycarbonate) packed with the powder of the material (e.g.: alpha-Fe2O3) having the electric charge order near the electric charge order of the magnetic tape. Then, the charge of the static electricity by the sliding contact friction of the sliding contact surface 8 with the recording medium is decreased and the generation of wow and flutter by the charge is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Def] The present invention relates to a magnetic head having a sliding contact surface that comes into sliding contact with a magnetic recording medium.

[Prior Art] FIG. 5 illustrates the structure of a four-channel, auto-reverse head for audio as a conventional magnetic head.

In FIG. 5, reference numeral 1 denotes a magnetic core constituting a magnetic circuit that is the main body of electromagnetic conversion of the magnetic head, and is constructed by butt-joining a pair of half-magnetic cores through a magnetic young G. Here, there are 4 channels. There will be 4 minutes. Each magnetic core 1 is fitted with a coil bobbin in which a coil (not shown) is wound and a connection terminal is implanted. Also, each magnetic core 1
A spacing plate 2 is sandwiched between them.

Reference numeral 3 denotes a shield case that houses the magnetic core I and the above-mentioned attached members and shields external noise, and tape guides 6 for guiding the R6 tape 5 are attached on both sides of the shield case.

Then, each magnetic core 1 is fitted into the shield case 3 together with the above-mentioned attached members, and the tip end surface of each magnetic core l is exposed to the opening 3a formed on the -1- plane in the figure of the case 3, and the end surface of each magnetic core l is exposed inside the case 3. A magnetic hent is constructed by casting a fixing material 4 made of resin and fixing a magnetic core I thereon. shield case 3
In the figure, the upper surface, the tip surface of the magnetic core l exposed in the opening 3a, and the surface of the fixing material 4 constitute a magnetic tape sliding surface 7 that slides into contact with the magnetic tape 5.

The fixing material 4 is generally a thermosetting resin such as an epoxy resin to which an inorganic filler such as Si02, Al103, CaCC)3 is added.

With this structure, the magnetic tape 5 runs as shown by arrow A and slides into contact with the magnetic tape sliding surface 7 to record and reproduce information.

[Problems to be Solved by the Invention] However, when such a magnetic head runs the tape in an environment of low temperature and low humidity, such as in the winter, friction between the magnetic tape 5 and the magnetic tape sliding surface 7 causes damage. Both are electrically charged, and the magnetic tape 5 sticks to the sliding contact surface 7 due to the static electricity, which may cause so-called wow-fist flutter. In particularly severe cases, tape running may become impossible and the tape may be stopped.

[Means for Solving the Problems] In order to solve these problems, according to the present invention, in a magnetic head having a sliding contact surface that comes into sliding contact with a magnetic recording medium, a charging order is changed with respect to the magnetic recording medium. A structure was adopted in which a part of the sliding contact surface was formed by blocks made of similar materials.

[Function] As is well known, even when materials with similar charge order are brought into sliding contact, there is little static electricity charging due to friction between the two. Therefore”
According to the bipedal structure, the blow is composed of a material whose charge order is similar to that of the magnetic recording medium.

As a result, static electrification due to sliding friction on the sliding surface between the recording medium and the magnetic head is reduced.

[Example] Hereinafter, details of an example of the present invention will be described with reference to FIGS. 1 to 4.

First, before giving examples, the present invention will be explained in detail.

Regarding the electrostatic charge caused by friction, which is the problem of the present invention, the positive and negative charges generated on two substances when they are brought into contact and separated are determined by the types of substances as long as the conditions are constant. There is a so-called charge order among various substances as to whether they are positively or negatively charged. It is known that when two materials are rubbed together and 12 charges are generated, the charge ε crossroads become smaller as the materials are closer in charge order, and larger as the materials are farther apart.

Therefore, in the present invention, in order to prevent charging due to sliding friction between the sliding contact surface of the magnetic hand and the magnetic recording medium, a part of the sliding contact surface is made of a material whose charging order is close to that of the recording medium. Thought.

For this reason, we first investigated materials that have a similar band order to magnetic tape. Figure 4 shows the results, and shows that the core material (permalloy) and S i 02 , CacO 3 , A
203, and the same composition as the magnetic powder of the magnetic tape. cx-Fe203, a-, which seems to have a similar electrical sequence
It shows the results of investigating the charge order of FeOOH, CrO2, etc. In addition, for each of 5i02 and below, blocks formed by molding each powder filled in an epoxy resin with the hair amount percentage shown in the figure were investigated. The charging order was determined by rubbing samples of each substance shown in the figure together in an atmosphere of 25° C., humidity and 50% RH, and measuring the positive and negative potentials of both using a static potentiometer. Items marked with a black circle in the table are magnetic materials.

In the fourth IN, the area shown by the short arrow has a charging order close to that of the magnetic tape, and an antistatic effect can be obtained. However, in order to use it in a magnetic head, it is necessary to use a non-magnetic one. Taking these into consideration, α-Fe203 or Cr is most preferable for use in preventing static electricity.
It is O2.

Next, in order to use these materials to form part of the sliding surface of the magnetic head, an attempt was made to fill the resin of the magnetic core fixing material of the magnetic head with these materials. However, for example, α-Fe20.
When the resin of the fixing material is filled with a high density so as to provide static protection, the viscosity of the fixing material increases and thixotropic properties appear, so the fixing material is poured into the shield case. It becomes impossible to do so. Also, is it 1 in terms of the amount of filling that can be cast? It has no effect on Electric Defense I.

Therefore, in the present invention, a block made of a substance having a similar charge order, specifically a block made of resin filled with powder of the above-mentioned substance, is provided on the sliding surface of the magnetic head. We decided to form part of the sliding surface.

Next, the present invention will be explained in detail.

FIG. 1 is a diagram illustrating the structure of a four-channel, auto-reverse type magnetic head for conventional audio, as described above, as an embodiment of the present invention. In this figure, parts common to those in the conventional example shown in FIG.

As shown in FIG. 1, in addition to the structure similar to the conventional example, the head of this embodiment has a magnetic tape sliding surface 7 adjacent to both edges of each magnetic core 1 on the upstream and downstream sides in the magnetic tape running direction. One block 8.8 is buried so that its surface is exposed, and this block 8.8 constitutes a part of the sliding surface 7.

And this block 8.8 is a magnetic tape as mentioned above. It is made by molding a resin filled with powder of substances that are similar in rank. - As an example α-F e 203 is 50'
R! A molded product made of polycarbonate resin filled with +l:% was used. The structure of the other parts is the same as the conventional example shown in FIG.

According to the structure of this embodiment, since the magnetic tape (blocks 8 and 8 constituting a part of the joint surface 7 have a similar charging order to the magnetic tape, the sliding contact between the circuit layer contact surface 7 and the magnetic tape is prevented). The Ii7 electric current due to friction is reduced, and the occurrence of wow and flutter due to the 412 electric current and the inability to run the tape can be prevented.

By the way, I will explain the wow and flutter generation test I conducted to see this effect and its results.

In the same test, a signal with a frequency of 3KH2 was recorded in advance for each of the head of this embodiment and the conventional head shown in Fig. 5.
- Fe203-coated cassette tape was slid in an atmosphere of 5°C and 20% RH, played back, and measured the frequency of the playback signal (note that the γ-Fe of the tape
Block 8.20:3 is a magnetic material, whereas block 8.20:3 is a magnetic material.
(α-F e2o3 used in 8 is a non-magnetic material), the reproduced output signal should originally be a 3 KHz signal, but the frequency changes when wow or flank occurs. Wow and flutter occurs when the frequency change is ±3%,
The tape running time until the occurrence of wow and flutter was investigated for both hands.

As a result, in the conventional head, wow and flutter occurred after 3 hours of running, and the tape stopped after 10 hours of running. On the other hand, in the head of this example, no wow-flutter occurred even after running for 50 hours.

Therefore, according to this embodiment, wow and flutter or tape running failure due to charging is extremely effectively prevented ((-
I was able to confirm that it is possible.

It goes without saying that the structure of the present invention is not limited to the magnetic head of the embodiment shown in FIG. 1, but can be similarly applied to other types of magnetic heads. Further, the shape, size, arrangement, number, etc. of the blocks 8 are not limited to those of the first embodiment.

For example, FIG. 2 shows an embodiment in which the above-mentioned block 8 is provided on the magnetic tape sliding surface 7 in a two-channel stereo hand. Only one is provided on one side in the track width direction.

FIG. 3 shows an embodiment in which a block 8 is provided in an audio control head for a VTR. In this case, the block 8 is formed in a large rectangular shape and has two magnetic cores.
, 1 at the center of the sliding surface 7.

It goes without saying that the types of filler material and resin for the block 8 are not limited to those described above.

[Effect of the invention] As is clear from the above explanation, A: According to the invention,
In a magnetic head having a sliding contact surface that comes into sliding contact with a magnetic recording medium, a part of the sliding contact surface is constituted by a block made of a material having a charge order similar to that of the magnetic recording medium. Sliding contact with magnetic recording media) li!
It is possible to prevent charging due to friction, to prevent the occurrence of wow and flutter caused by the band 7, or to prevent the recording medium from sliding, and to achieve the excellent effect of improving output characteristics and extending the life of the recording medium.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the structure of a magnetic head according to one embodiment of the present invention, FIGS. 2 and 3 are perspective views of magnetic heads of other different embodiments, and FIG. 4 is a perspective view showing the structure of a magnetic head according to an embodiment of the present invention. Figure 5 is a chart showing the charging order of the resin block, magnetic tape, and core material. FIG. l...Magnetic core 2...Spacer plate 3...Shield case 4...Fixing material 5...Magnetic tape
6...Tape guide 7...Magnetic tape sliding surface 8...Block 11 Applicant Canon Electronics Co., Ltd. Agent Patent attorney Kato! : [IQ″7)1:
・・１ １、： ． (-・-y number--Shizuku 1st figure 2nd figure

Claims (1)

[Scope of Claims] 1) In a magnetic head having a sliding surface that makes sliding contact with a magnetic recording medium, a part of the sliding surface is constituted by a block made of a substance having a similar charging order to that of the magnetic recording medium. A magnetic head characterized by: 2) The magnetic head according to claim 1, wherein the block is formed by molding resin filled with powder of a substance that has a similar charge order to the magnetic recording medium. 3) The magnetic head according to claim 1 or 2, characterized in that α-Fe_2O_3 is used as the material having a charge sequence close to that of the magnetic recording medium.