JP2579628B2 - Magnetic head - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic head having a sliding contact surface that slides on a magnetic recording medium.

[Prior Art] FIG. 5 illustrates the structure of a 4-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 which is a main component of the electromagnetic conversion of the magnetic head, and is formed by joining a pair of magnetic core halves through a magnetic gap G, and here, 4 Four channels are provided. A coil bobbin around which a coil (not shown) is wound and connection terminals are implanted is fitted to each magnetic core 1. A spacing plate 2 is sandwiched between the magnetic cores 1.

Reference numeral 3 denotes a shield case for accommodating the magnetic core 1 and the attached members and shielding external noise. Tape guides 6 for guiding the magnetic tape 5 are provided on both sides of the shield case.

Then, each magnetic core 1 is fitted into the shield case 3 together with the accessory member, and the tip end surface of each magnetic core 1 is exposed through an opening 3a formed in the upper surface of the case 3 in the drawing.
A fixing material 4 made of resin is cast therein and the magnetic core 1 is fixed to form a magnetic head. The top surface of the shield case 3 in the drawing, the front end surface of the magnetic core 1 exposed in the opening 3a thereof, and the surface of the fixing member 4 constitute a magnetic tape sliding contact surface 7 in sliding contact with the magnetic tape 5.

The fixing member 4 is generally made of a thermosetting resin such as an epoxy resin to which an inorganic filler such as SiO ₂ , Al ₂ O ₃ , or CaCO ₃ is added.

With such a structure, the magnetic tape 5 travels as shown by the arrow A, and slides on the magnetic tape sliding surface 7 to record and reproduce information.

[Problems to be Solved by the Invention] However, in such a magnetic head, particularly when the tape is run in a low-temperature, low-humidity use environment such as in winter, friction between the magnetic tape 5 and the magnetic tape sliding contact surface 7 causes. Both are charged, and the static electricity may cause the magnetic tape 5 to adhere to the sliding contact surface 7, which may cause so-called wow and flutter. In particular, when the state becomes severe, the tape may not be able to run and may stop.

[Means for Solving the Problems] According to the present invention, there is provided a magnetic head having a sliding contact surface which is in sliding contact with a magnetic recording medium. A structure in which a part of the sliding contact surface is constituted by a block made of a material having a similar charging sequence was adopted.

[Operation] As is well known, even if materials having similar charging sequences are brought into sliding contact with each other, there is little static charge due to friction between the two. Therefore, according to the above structure, the static charge due to the sliding friction on the sliding surface between the recording medium and the magnetic head is reduced through the block made of a material having a similar charging sequence to the magnetic powder of the magnetic recording medium. Become.

Embodiment An embodiment of the present invention will be described below in detail with reference to FIGS.

 First, the principle of the present invention will be described before the embodiment.

With respect to the electrostatic charge caused by friction, which is a problem of the present invention, the positive and negative charges generated on the two substances when they come into contact with and separated from each other are determined depending on the type of the substances as long as the conditions are constant. There is an order between various substances, that is, a so-called charging order. And 2
It is known that when two substances are charged by friction, the amount of charge is smaller for substances having a closer charging order and larger for substances which are farther.

Therefore, in the present invention, in order to prevent charging due to sliding friction between the sliding surface of the magnetic head and the magnetic recording medium, a part of the sliding surface is made of a substance whose charging sequence is close to the magnetic powder of the recording medium. I thought.

For this reason, first, a substance having a similar charging order to the magnetic powder of the magnetic tape was examined. FIG. 4 shows the result.
The result of examining the charging sequence of α-Fe ₂ O ₃ , α-FeOOH or CrO ₂ , which is considered to have a similar charging sequence with the same composition as the magnetic powder of the magnetic tape, is shown. In addition, about each of these, the block which formed what filled each powder with the weight% of the figure in an epoxy resin in the figure was investigated. The charging order is as follows.
Rubbing was performed in an atmosphere of 50% RH, and the positive and negative potentials of both were measured by an electrostatic potentiometer. Those marked with black circles in the table are magnetic materials.

In FIG. 4, the charging sequence is close to the magnetic powder of the magnetic tape, and an antistatic effect is obtained. However, in order to use it for a magnetic head, it is necessary to use a non-magnetic one among them. In consideration of these, α-Fe ₂ O ₃ or CrO ₂ is most preferably used for the above antistatic.

Next, in order to form a part of the sliding surface of the magnetic head using these, it was attempted to fill them with resin of a magnetic core fixing material of the magnetic head. However, for example, when α-Fe ₂ O ₃ is filled at a high density so that the resin of the fixing material can be prevented from being charged, the viscosity of the fixing material increases and thixotropic properties appear, so the fixing material is used in a shield case. Casting becomes impossible. Also, there is no antistatic effect when the filling amount allows casting.

Therefore, in the present invention, a block formed of a material having a similar charging sequence, specifically, a block formed by molding a resin filled with a powder of the material is provided on the sliding surface of the magnetic head,
This block forms a part of the sliding contact surface.

 Next, examples of the present invention will be described.

FIG. 1 illustrates the structure of a 4-channel, auto-reverse magnetic head for audio of the same type as the conventional example described above as an embodiment of the present invention. In this figure, parts common to FIG. 5 of the conventional example are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 1, in the head of this embodiment, in addition to the same structure as the conventional example, the magnetic tape sliding contact surface 7 is adjacent to both side edges of the magnetic core 1 on the upstream side and the downstream side of the magnetic tape running direction in the running direction of the magnetic tape. Then, the blocks 8, 8 are embedded so that their surfaces are exposed, and the blocks 8, 8 constitute a part of the sliding contact surface 7.

The blocks 8, 8 are formed by molding a resin filled with a magnetic powder of a magnetic tape and a powder of a substance having a similar charging sequence as described above. As an example, a molded product of a polycarbonate resin filled with 50% by weight of α-Fe ₂ O ₃ was used. The structure of other parts is the same as that of the conventional example shown in FIG.

According to the structure of this embodiment, since the magnetic powder of the magnetic tape and the charging sequence are close to each other for the blocks 8 and 8 constituting a part of the magnetic tape sliding contact surface 7, the sliding contact surface 7 and the magnetic tape are The electrification due to the sliding friction is reduced, and the occurrence of wow and flutter and the inability to run the tape due to the electrification can be prevented.

By the way, wow
The flutter generation test and its results will be described.

In this test, a signal having a frequency of 3 KHz was recorded in advance for each of the head of this embodiment and the conventional head of FIG.
Fe ₂ O ₃ coated cassette tape at a temperature of 5 ° C and a humidity of 20% RH
And the reproduction was carried out, and the frequency of the reproduction signal was measured. (Note that while γ-Fe ₂ O ₃ of the tape is a magnetic material, the α-Fe ₂ O
₃ is a non-magnetic material). The playback output signal should be a 3KHz signal, but the frequency changes when wow and flutter is played. When the change in frequency became ± 3%, wow and flutter was generated, and the tape running time until wow and flutter was generated was examined for both heads.

As a result, with the conventional head, wow and
Flutter occurred and the tape stopped after running for 10 hours. On the other hand, in the head of this embodiment, wow and flutter did not occur even after running for 50 hours.

From this, it was confirmed that according to this example, wow / flutter or tape running failure due to charging can be prevented very effectively.

It should be noted that such a structure of the present invention is not limited to the magnetic head of the embodiment shown in FIG. 1, but can be applied to other types of magnetic heads. Further, the shape, size, arrangement and number 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 contact surface 7 in a two-channel stereo head. In this case, the block 8 has a rectangular shape shorter than that of the first embodiment, and Is provided only 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 a sliding contact surface is formed between the two magnetic cores 1, 1. 7 is provided at the center.

Needless to say, the types of the filling material and the resin of the block 8 are not limited to those described above.

[Effects of the Invention] As is apparent from the above description, according to the present invention, in a magnetic head having a sliding contact surface that is in sliding contact with a magnetic recording medium, a substance having a charge sequence close to magnetic powder of the magnetic recording medium. A part of the sliding contact surface is constituted by the block composed of the magnetic recording medium, thereby preventing electrification due to sliding friction between the sliding contact surface and the magnetic recording medium, and generating wow and flutter due to the electrification or sliding the recording medium. It can prevent inability to run
An excellent effect of improving the output characteristics and extending the service life can be obtained.

[Brief description of the drawings]

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 different embodiments, and FIG. 4 is a magnetic powder of a magnetic tape. Table diagram showing the charging order of a material whose charging order is close to,
FIG. 5 is a perspective view showing the structure of a conventional magnetic head. DESCRIPTION OF SYMBOLS 1 ... Magnetic core, 2 ... Spacing plate 3 ... Shield case, 4 ... Fixing material 5 ... Magnetic tape, 6 ... Tape guide 7 ... Magnetic tape sliding contact surface 8 ... Block

Claims (3)

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