JPS593363Y2 - erase head - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an erasing head in a magnetic recording device.

An erasing head based on a method of creating a pseudo alternating current erasing magnetic field in the running direction of a magnetic recording medium using a permanent magnet has been published.

As a method of obtaining an AC erasing magnetic field, for example, as shown in the conventional example shown in Fig. 1, the positional relationship between the head and the medium is such that the distance between the medium and the head increases as the medium travels in order to obtain a monotonically decreasing reversal magnetic field. There are ways to maintain this.

In the figure, 1a indicates an erasing head made of a permanent magnet material such as barium ferrite, 2a and 2b are magnet plates, and 3a and 3b indicate the direction and magnitude of magnetization.

4 is the medium facing surface of the erasing head 1a. 5 is a magnetic recording medium consisting of a magnetic recording tape to be erased, and 6 is its head facing surface.

The medium 5 runs in the direction of the arrow 7.

In order to obtain a monotonically decreasing reversal magnetic field, the medium traveling system and head position are regulated so that the traveling medium 5 and the medium facing surface 4 of the erasing head form a predetermined angle θ.

However, in the configuration of the conventional example, the distance d between the medium facing surface 4 of the head 1a and the head facing surface 6 of the medium 5 increases as the medium travels, that is, the air flow on the surface of the medium Since this method forms an expansion gap, a suction force acts on the medium, which has the disadvantage that the distance d fluctuates.

In addition, the distance d depends on the delicate positional relationship between the medium 5 and the head 1a, and the distance d depends on the delicate positional relationship between the medium 5 and the head 1a.
There was also a problem with the reproducibility of the movement back and forth.

This is particularly noticeable when the medium travels at high speeds of several meters per second.

As a preliminary step to this invention, in order to eliminate the above-mentioned drawbacks of the conventional technology, by bonding a non-magnetic spacer to the front surface of the head, stable erasing with good reproducibility can be achieved.
We devised a head structure that can easily realize an optimal erase magnetic field corresponding to the magnetic properties of the medium and the magnetic properties of the permanent magnet plate, that is, a monotonically decreasing erase magnetic field distribution.

Hereinafter, the erasing head that led to this invention will be explained with reference to the drawings.

In FIG. 2, 1b is an erase head, 2a and 2b are magnet plates each magnetized in a single direction (2a and 2b are opposite to each other), and 3a and 3b indicate the direction and magnitude of their magnetization.

Reference numeral 8 denotes a media-side end surface of the magnet plate, 9 a wedge-shaped spacer piece made of a non-magnetic material such as ceramic or glass bonded thereon, and 4 a medium-facing surface.

FIG. 3 shows the intensity distribution of the magnetic field component Hx in the X direction shown in FIG. 2, which effectively acts on erasing on the medium facing surface 4 of the erasing head.

During the erasing process, the medium travels in contact with the medium facing surface 4 of the head, so there is no attraction force generated as in the case of FIG. Since it is determined by the spacer piece 9, there is no fluctuation, and the third
Stable erasing can be performed with good reproducibility using the erasing magnetic field shown in the figure.

Further, when ceramic such as alumina, glass, or the like is used as the spacer piece 9, the magnet plate 2a.

Regardless of the material of 2b, it is possible to obtain an erasing head with good wear resistance and suitable for high-speed running.

However, in the erase head shown in FIG. 2, the spacer piece 9 is made of one block;
Since the permanent magnet 1b consisting of one block with one side of the same shape as the one side is glued, there is no versatility at all.
In order to manufacture an erase head with a demagnetizing field curve suitable for different magnetic recording devices, the spacer pieces and permanent magnets must be newly designed, and the spacer pieces and permanent magnets must be different from each other. Since it consists of one block and its bonding surface is nearly parallel to the running direction of the magnetic medium, there is a drawback that the spacer pieces tend to peel off due to the force applied to the erasing head when the magnetic medium runs.

This invention was made with the aim of improving such drawbacks, and by laminating the plates with a spacer and a permanent magnet for each polarity, it provides versatility.
This paper proposes an erasing head whose spacer does not easily peel off.

FIG. 4 shows an embodiment of this invention, in which each magnetic plate 2
Non-magnetic block pieces 9 made of ceramic or glass are firmly bonded to a and 2b by a method such as glass bonding before the magnet plates 2a and 2b are bonded to each other.

Each bonding plate 2a, 2b is made by welding a non-magnetic ceramic block such as barium titanate to a permanent magnet material block before magnetization using glass or the like at high temperature, and then slicing it into a plate shape as shown in Fig. 4. A method such as magnetization in a single direction in a magnetic field may be used, or slicing may be performed after magnetization.

Next, the positions of the plurality of magnet plates 2a and 2b are shifted and fixed together so that the end faces of the magnet plates are on the curves shown by the broken lines B and B' in the figure, and the tips of the non-magnetic members are then fixed together by the broken lines shown in the figure. The medium facing surface is formed by removing unnecessary nonmagnetic members by grinding, polishing, or other methods.

The erasing head according to an embodiment of the invention shown in FIG. 4 has the same advantages as those described in FIG. 2, but also has the following advantages.

That is, since there is one block for each polarity, the optimum demagnetizing field distribution curve is set according to the magnetic properties of the medium and the magnetic properties of the magnet plate material, and the curve B in FIG.
As shown in B', you can easily obtain the ideal demagnetizing field by selecting the desired demagnetizing field curve for each product and aligning the magnet plates accordingly. It has the advantage that the spacer pieces are difficult to peel off because they are laminated with bonded plates in which the pieces are firmly joined.

In the above embodiments, the medium facing surface 4 has been described as being a single plane, but it may have a cylindrical curved shape or other shapes depending on the medium running system.

Further, although the case where five magnetic plates 2a and 2b constitute the head has been described, it is clear that the above effects can be obtained regardless of the number of magnetic plates.

It is generally known that erasing efficiency increases as the number of magnetic field reversals increases.

Although the above embodiments have described the case where a plurality of magnet plates are directly bonded to each other, it is also possible to laminate each magnet plate through a non-magnetic material layer such as a glass, ceramic, brass, resin plate, or non-magnetic adhesive layer. It is clear that the above effects can be obtained in any case.

As described above, according to this invention, since a plurality of magnet plates each provided with a spacer member are stacked, it is possible to reproducibly and stably obtain a reversal magnetic field that monotonically decreases as the medium travels. can.

Further, by using a wear-resistant material such as ceramic as the spacer material, an erasing head with excellent wear resistance can be obtained regardless of the mechanical properties of the magnet material.

Furthermore, it is possible to easily realize an erasing magnetic field distribution that corresponds to the magnetic characteristics of the medium and the magnet plate, and more effective erasing can be performed.

Further, since the magnet plate and the spacer portion are firmly bonded by glass bonding or the like, there is an advantage that an erasing head which is excellent in practical use without head clogging or peeling at the bonded portion can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a conventional erasing head made of a permanent magnet, and FIG. 2 is a perspective view showing the previous erasing head that led to this invention.
FIG. 3 is a diagram showing the distribution of the erase magnetic field intensity according to the one shown in FIG. 2, and FIG. 4 is a perspective view showing an embodiment of this invention. In the figure, lb and IC are erase heads, 2a and 2b are magnet plates, 4 is a medium facing surface, and 9 is a non-magnetic spacer piece. Note that the reference numerals in the middle of each figure indicate the same or corresponding parts.

Claims (2)

[Scope of utility model registration request] (1) A plurality of plate-shaped non-magnetic spacers integrally bonded to one polarity side of a permanent magnet are stacked so that adjacent polarities are different, and the permanent magnet and the non-magnetic spacer are An erasing head characterized in that the distance between the joint surface of the magnetic recording medium and the magnetic recording medium gradually increases in the direction of movement of the magnetic recording medium. (2) The erasing head according to claim 1, which is a registered utility model, characterized in that a permanent magnet and a non-magnetic spacer are bonded together by glass bonding to form a plate.