JPS6331850B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic head used for guard bandless high-density recording in a video tape recorder, and a manufacturing method thereof, and more particularly to a magnetic head capable of improving crosstalk and a manufacturing method thereof.

Recent home video tape recorders utilize the gap azimuth loss of the magnetic head for high-density recording, and record on magnetic tape without guard bands. However, in this case, there is a problem in which adjacent and adjacent crosstalk cannot be ignored, depending on the tape running accuracy and head shape.

FIG. 1 is a front view showing an example of a conventional magnetic head. In the figure, 1 is a tape sliding surface, 2 is a groove, and 3 is a gap. In order to obtain wear resistance, the thickness T _C of the tape sliding surface 1 is approximately three times the track width W ₁ . Note that the groove 2 is filled with glass, which is a non-magnetic material.

FIG. 2 is an explanatory diagram illustrating a method of manufacturing the conventional magnetic head shown in FIG. 1. This method is
First, a groove having a semicircular tip is formed in each of the cores 1a and 1b using a high-speed rotating grindstone shaped into a predetermined shape. In this case, the machining pitch A has a dimension equal to twice the thickness B of the grindstone plus a predetermined track width _W1 and a dummy track width _W2 . Then, non-magnetic material SiO ₂ is generated on the gap 3 forming surfaces of the cores 1a, 1b by known means, and further, these cores 1a,
1b are butted together and groove 2 is formed by glass bonding.
The cores 1a and 1b are then filled with glass to form a block. Next, in order to create a predetermined gap azimuth, the gap-formed block is tilted by the azimuth, and the track width is cut using a peripheral slicer or wire saw having a blade thickness of S.
Cut leaving W ₁ . The shaded portion in FIG. 2 is the portion to be removed by cutting. In this way, the magnetic head shown in FIG. 1 is obtained.

By the way, in the conventional magnetic head manufactured in this way, a part of the line 4 of the groove 2 and the gap 3
are parallel to each other, and this causes the problem of adjacent and adjacent crosstalk (in particular, the influence of adjacent adjacent is large).

As a method for manufacturing a magnetic head that improves this crosstalk, a method illustrated in FIG. 3 has been proposed. This method uses a grindstone with a thickness of C = W ₂ + 2B and a trapezoidal shape.
A groove 2 is formed therein. The shaded part is the part to be removed by cutting. According to this method, the gap 3 and the line 4 forming the edge of the groove 2 are never parallel to each other. However, in this method, the width of the groove 2 (the thickness of the grinding wheel C)
(equivalent to) is more than twice as large as in the conventional method described above, and therefore, there is a problem that it is very difficult for the glass to enter when filling with glass. Furthermore, in this method, when forming a gap, the stress applied to the track width W ₁ increases by more than three times, making cracks more likely to occur, and the magnetic properties of the material inevitably deteriorate due to these stresses and cracks. There are problems that lead to a decrease in head manufacturing yield and deterioration in head performance.

The present invention has been made in view of the above-mentioned actual situation in the prior art, and its object is to provide a magnetic head and its manufacture that improves crosstalk and does not cause a decrease in manufacturing yield or deterioration of head performance. The purpose is to provide a method.

Hereinafter, the present invention will be explained in detail based on the drawings. FIG. 4 is a schematic diagram showing an embodiment of the magnetic head of the present invention;
FIG. 5 is an explanatory diagram illustrating a method of manufacturing the magnetic head shown in FIG. 4.

In FIG. 4, 1 is a tape sliding surface, 2 is a groove filled with non-magnetic glass, and 3 is a gap. The thickness T _C of the tape sliding surface 1 is approximately three times the track width W ₁ . The line forming the edge of the groove 2 is composed of a plurality of compound circular arcs and outer lines 4a and 4b synthesized by including two parallel straight lines, and does not have a line portion parallel to the gap.

The magnetic head shown in FIG. 4 is manufactured as follows. That is, as shown in FIG. 5, first, a groove 2a having a semicircular tip is formed in each of the cores 1a and 1b using a grindstone having a thickness of B. As shown in FIG. The machining pitch A at this time is a dimension that is twice the thickness B of the grindstone plus the track width _W1 and the dummy track width _W2 . In other words, at a position where the track width W ₁ is secured, a groove 2a having a width corresponding to the thickness B of the grinding wheel and a length l ₁ is machined, and then at a position where a dummy track width W ₂ is secured. , has a width corresponding to the thickness B of the grindstone and a length similar to the above.
l Machining the groove 2a of ₁ . Thereafter, a plurality of grooves 2a are formed in each of the cores 1a and 1b using the processing pitch A in the same manner. Next, grooves 2a are formed in the cores 1a and 1b using a grindstone having a thickness D smaller than the thickness B of the grindstone described above.
Next, another groove 2b having a semicircular tip is machined. This groove 2b has a width corresponding to the thickness D of the grindstone, and its length _l2 is larger than the length _l1 of the groove 2a. Note that one groove 2b is formed along each adjacent edge of the two grooves 2a provided in one pitch A. After that, non-magnetic material SiO ₂ is generated on the gap forming surfaces of the cores 1a and 1b, and then these cores 1a and 1b are butted together, and the grooves 2a and 2b, that is, the groove 2, are filled with glass by glass bonding to integrate them. , block. Next, in order to create a predetermined gap azimuth, this gap-formed block is tilted by the azimuth and cut using a peripheral type slicer or a wire saw having a blade thickness S. The shaded part is the part to be removed by cutting. In this way, the magnetic head shown in FIG. 4 is obtained.

In addition, in the above, each groove 2 of the cores 1a and 1b
Although it has been described that the grooves 2b having a width smaller than the width of the groove 2a are machined one by one in Fig. a, the present invention is not limited to this, and a plurality of grooves may be machined into the groove 2a.

However, in this case as well, the width of each of the plurality of grooves is smaller than the width of the groove 2a, and the length thereof is made larger than the length of the groove 2a. The concave groove 2 can also be formed by using a full-form grindstone to form curved or straight curves 4a and 4b in one process. Further, in order to prevent stress during glass filling, it is preferable to make the surface area of the groove 2 as small as possible, and the above embodiment is suitable for this purpose.

As described above, in the magnetic head of the present invention, since the line portion forming the edge of the groove 2 and the gap are not parallel, adjacent and adjacent crosstalk can be reduced. effective. The inventor has confirmed that this crosstalk can be improved by more than 6 dB compared to the conventional magnetic head shown in FIG. Furthermore, in the manufacturing method of the present invention, the width of the groove does not need to be expanded as in the conventional manufacturing method shown in FIG. 3, but can be kept at the same width as in the case shown in FIG. 2. At the same time, since the dummy track width _W2 is not lost, there is no possibility of glass filling failure or cracks due to increased stress during glass bonding, which can lead to lower manufacturing yields and lower head performance. It has an unprecedented effect.

[Brief explanation of drawings]

FIG. 1 is a front view showing an example of a conventional magnetic head, FIG. 2 is an explanatory diagram illustrating a method of manufacturing the conventional magnetic head shown in FIG. 1, and FIG. 3 is a manufacturing method of another conventional magnetic head. An explanatory diagram illustrating a method of
FIG. 4 is a schematic diagram showing one embodiment of the magnetic head of the present invention, and FIG. 5 is an explanatory diagram illustrating a method for manufacturing the magnetic head shown in FIG. 4. 1... Tape sliding surface, 1a, 1b... Core, 2
...Concave groove, 2a, 2b...Groove, 3...Gap,
4a, 4b...Curve, A...Processing pitch, B...
Thickness, C...Thickness, D...Thickness, T _C ...Thickness,
W ₁ ... Track width, W ₂ ... Dummy track width,
l ₁ , l ₂ ... Length.

Claims (1)

[Claims] 1. In a magnetic head for guard bandless high-density recording in a video tape recorder, which is provided with a concave groove that regulates a track width that is point symmetrical with respect to a gap, a surface on which the magnetic head slides against a medium. The outer shape of the groove formed on the top is composed of a plurality of compound circular arcs and two parallel straight lines, and the outer shape has no part parallel to the gap line. Head. 2. A magnetic head having a surface perpendicular to the joining surfaces of a pair of cores as a sliding surface with the medium, a line where the sliding surface and the joining surface intersect as a gap, and a groove having a point symmetrical with respect to the gap. In the manufacturing method, A: Machining pitch W ₁ : Track width W ₂ : Dummy track width B: Grinding width (concave groove width) D: Grinding width, where D<B/2 l ₁ , l ₂ : Grinding length, where l When ₁ < l ₂ , the sliding surface of the core has a track width W ₁
and dummy track width W ₂ are left alternately to grind the length.
l ₁ , the first process of machining an elliptical grinding groove with a grinding width B in the longitudinal direction at a machining pitch A, and grinding an ellipse with a grinding length l ₂ and a grinding width D on both sides with a dummy track width W ₂ in between. a second step of machining the groove to overlap the grinding groove of the first step; and tilting by a predetermined azimuth,
A method for manufacturing a magnetic head, characterized in that forming the groove includes a third step of removing the longitudinal dimension S such that S>B+W ₂ with respect to the dummy track width W ₂ .