JPS5813971B2 - Composite magnetic head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composite magnetic head, and more particularly to a composite magnetic head that has a recording/reproducing magnetic head as well as an erasing magnetic head.

Generally, in a composite magnetic head, the width of the erasing gap is set wider than the width of the recording/reproducing gap.

This is because when recording a magnetic tape, the recording track may meander as the running magnetic tape swings slightly in its width direction. This is because it needs to be made wider.

An example of such a composite magnetic head is shown in FIG. 1, in which an erasing gap 1 is provided between a central core 2 and a core 3 on the right at the same height as the central core 2. The gap 4 is formed between the center core 2 and the left core 5 having a lower height than the center core 2.

The width a of the recording/playback gap 4 is shorter than the width b of the erasing gap 1, so each core 2, 3.5 should be finished so that their bottom surfaces are the same, and then 2,
5 is fixed to the shield case I via a fixing casting resin 6 with a level difference of b-a between the upper surfaces of the shield case I.

The shield case 7 is fixed on the support plate Ia, and upper and lower tape guides 8a, 8b are arranged near the left side of the shield case 7, and the magnetic tape 9 is attached to the tape guides 8a, 8b.
The magnetic head slides in sliding contact with the front surface of the composite magnetic head and travels in the direction of the X arrow.

At this time, the portion of the magnetic tape 9 below the center line 9a is brought into contact with the gaps 4 and 1, and the magnetic track portion of the magnetic tape indicated by the width a' is subjected to erasing, recording, or reproduction processing. .

In the case of such a composite magnetic head, each core 2, 3, 5
The lower surfaces of the tape guides 8a and 4 are finished so that they are correctly placed on the same surface, and the steps b-a of the widths a and b of both gaps 1 and 4 are determined with high accuracy, and the magnetic track of the magnetic tape 9 is the distance b' to the center line 9a of the magnetic track, and the distance to the upper edge of the magnetic track, that is, the track width a'
It is necessary to achieve extremely high accuracy.

However, when a core made of oxide ferromagnetic material such as ferrite is used in such a composite magnetic head, a non-magnetic material such as non-magnetic ferrite, which has a hardness close to that of ferrite, is placed around the core. However, in reality, since there is a level difference between b and a, only the casting resin 6 is used to fill it, and as a result, a dent occurs in this part due to the difference in hardness between the core and the synthetic resin. There is a problem that dust may accumulate in these recesses or the surface of the magnetic tape may be scraped off.

On the other hand, when using an alloy core such as permalloy as a magnetic head, the top, bottom, left and right sides of each core are supported by core holding blocks.
If there is, the dimensions of the gap formed between each core and the core holding block will not be uniform, which will not only make it difficult to obtain the accuracy of this step b-a, but also the above-mentioned track width a.
Alternatively, it becomes extremely difficult to achieve precision in dimensions such as the distance b'.

An object of the present invention is to provide a composite magnetic head that completely eliminates the above-mentioned problems by skillfully utilizing a positioning block that fills the step b-a.

Hereinafter, the present invention will be specifically explained with reference to illustrated embodiments.

FIGS. 2 and 3 show a case where a composite magnetic head is constructed using a laminated core made of an alloy such as permalloy.

In FIG. 2, the center core 10 and the right core 11 are each set at the height b, and the left core 12 is a laminated core set at the height a. ing.

For the left core 12, a positioning block 13 having a thickness of dimension b-a and having the same planar shape is separately prepared.

This block 13 is made of non-magnetic material such as brass.

Each core 10, 11. 12, by first gluing the positioning block 13 onto the core 12, polishing each gap forming surface to a mirror finish, and then butting them together with a spacer made of, for example, a Be-Ou alloy between them.
As shown in FIG. 3, an erasure gap 14 and a recording/playback gap 15 are formed.

At this time, the lower surfaces of the cores 10, 11, and 12 are aligned so that they are on the same surface.

Each core 10 with a gap 14.15 formed in this way,
11 and 12 are the shield case 1 made of cast resin 16.
7 to form a composite magnetic head 18.

The shield case 1T is fixed on a support plate 17a, and upper and lower magnetic tape guides 19a and 19b are arranged on the left side of the shield case 17.

In this composite magnetic head 18, the height of the core 12 having a low height is compensated for by the positioning block 13, and the height is equal to that of the other cores 10 and 11. Gap 15 for recording and playback
, and the dimensional relationship between them and the tracks of the magnetic tape can be determined very easily and precisely, and since the resin 16 has a uniform width, no dents are formed, and it is easy to assemble with core holding blocks. Even when the cores are supported, the gaps between them and each core are uniform in width, making it very easy to achieve precision.

FIGS. 4 and 5 illustrate a case in which a composite magnetic head is constructed with a core made of an oxide ferromagnetic material such as ferrite.

In FIG. 4, the center core 20 and the right core 21 are each set to have dimensions slightly larger than the height b,
Further, the left core 22 is each formed of ferrite set to the height a.

The gap-forming surfaces of these cores 20, 21, and 22 are mirror-finished and then welded to each other with a gap-forming material such as glass or ceramic sandwiched between them to form an erasing gap 23 and a recording/playback gap 24. do.

Next, a positioning block 25 having the same planar shape as the core 22 and slightly larger than the thickness ba is prepared, and is bonded onto the core 22.

This block 25 is made of a non-magnetic material, such as non-magnetic ferrite, which has a hardness similar to that of the core material.

When the positioning block 25 is glued onto the core 22,
Next, left and right core holding blocks 26 and 27 with dimensions slightly larger than the height b are glued to the left and right sides of this combination, and then the top and bottom surfaces of this combination are polished, and the entire body is polished. The required height b is determined.

Then, upper and lower core holding blocks 28 and 29 are adhered to the upper and lower surfaces so as to cover the entire surface, thereby completing the composite magnetic head 30 (see FIG. 5).

In this composite magnetic head 30 as well, since the height of the core 22 having a low height is compensated for by the positioning block 25 having a thickness of b-a, the gap width for both erasing, recording, and playback is widened. The central core 20 due to the difference b-a
There is no difference in level between the core 22 and the left core 22, and therefore no inconvenience occurs due to this.

In addition, as a core holding block, materials with similar physical properties to the core, such as hardness or abrasion resistance, can be bonded by simply applying a thin layer of adhesive without using casting resin. Therefore, there is no risk of the head surface being dented or the magnetic tape surface being damaged.

As described above, according to the present invention, the dimensions a and b of the recording/playback gap and the erasing gap are well-accurate, and the other dimensions a' and b' and the correspondence with the tracks of the magnetic tape, etc. Furthermore, the problems of conventional products, such as the formation of wide grooves due to the step between the core and the surrounding parts, where dust accumulates, and the magnetic tape is scraped, have been completely eliminated. Many excellent effects can be obtained, such as eliminating the problem and making assembly extremely easy.

[Brief explanation of the drawing]

Figure 1 is a front view showing a conventional example of a composite magnetic head;
FIG. 3 is a developed perspective view showing the correspondence between the core and the positioning block constituting a composite magnetic head to which the present invention is applied; FIG. 3 is a front view of the composite magnetic head showing an embodiment of the present invention; FIG. 4 is an exploded perspective view showing the correspondence among a core, a positioning block, and a core holding block constituting a composite magnetic head to which the present invention is applied, and FIG. 5 shows another embodiment of the present invention. FIG. 2 is a perspective view of the composite magnetic head shown in FIG. 1 10.20...Central core, 11,21
...lateral cores of equal height to the central core, 1
2, 22... Side cores having a lower height than the central core, 14, 23... Erasing gap formed by cores 10, 11 and cores 20, 21, 15, 24...Core 10, 12 and core 2
A recording/playback gap formed by 0 and 22, and a positioning block that compensates for the height of the lower core.

Claims (1)

[Claims] 1 Place a core with the same height as the central core and a core with a lower height on both sides of the central core, and record and playback between the shorter core and the central core. An erasing gap is formed between the cores of equal height and the center core, and the lower surfaces of each of these cores are finished on the same plane. A positioning block with a thickness equivalent to the step with the core,
A composite magnetic head characterized by being placed on the upper surface of the lower core and fixed together.