GB2159318A

GB2159318A - Floating magnetic head

Info

Publication number: GB2159318A
Application number: GB08512698A
Authority: GB
Inventors: Hideo Sato; Shingo Takahashi
Original assignee: Alps Electric Co Ltd
Current assignee: Alps Alpine Co Ltd
Priority date: 1984-05-25
Filing date: 1985-05-20
Publication date: 1985-11-27
Also published as: KR900006052Y1; GB8512698D0; JPS60192117U; JPH0240573Y2; GB2159318B; KR850009659U

Abstract

A floating magnetic head has a core holder (2) having a recess (4) and a coil slot (5) extending transversely across the recess (4). A magnetic core (7) having a gap (8) is inserted in said recess (4) and a coil (9) is wound around a portion of said magnetic core (7) which is disposed in said coil slot (5). The magnetic core (7) has a reference surface (A) extending parallel to a gapped surface. The magnetic core (7) is mounted in said recess so that said reference surface is exposed to view in said coil slot (5). By using the reference surface (A) the depth of the gap (7) in the core can be accurately determined after both the holder (2) and the core (7) have been ground down. <IMAGE>

Description

SPECIFICATION Floating magnetic head The present invention relates to a floating magnetic head for use in a magnetic disc drive, for example.

There have been known various floating magnetic heads which, in use, float about 0.3 to 0.5 tim above the surface of a magnetic recording medium (such for example as a magnetic disk).

Fig. 3 of the accompanying drawings illustrates one such floating magnetic head. The floating magnetic head, generally indicated at 1, comprises a core holder 2 of a nonmagnetic material such as ceramics, and a pair of rails 3 on the core holder 2. The core holder 2 has a recess 4 in which a magnetic core is inserted, a coil slot 5 extending perpendicularly to the recess 4, and a notch 6 in which a load applying device (not shown) is mounted.

The core holder 2 has a surface on which the rails 3 are disposed, that is, an upper surface as shown in Fig. 3 positioned in confronting relation to a magnetic recording medium. A magnetic core 7, as shown in Fig. 4, is made of a magnetic material and has an air gap 8 having a gap depth D. In assembly, the magnetic core 7 is inserted in the recess 4 with the gap 8 facing toward one of the rails 3, and then is fixed to the core holder 7 as by melting the glass. To prevent the magnetic recording medium from being damaged or injured by the magnetic core 7, the gapped surface of the magnetic core 7 and the rail 3 are ground down so as to lie flush with each other after the magnetic core 7 has been fixed to the core holder 2.A coil 9 is wound through the slot 5 around a portion of the magnetic core 7 which is positioned in the coil slot 5, the coil 9 being composed of a prescribed number of terms such as 15 to 30 turns.

It is known that the gap depth D as well as a gap length of the magnetic core is related to sensitivity, the tendency being that the smaller the gap depth D, the better the sensitivitiy.

Since the gap depth D greatly affects the magnetic head sensitivity, it is necessary to measure the gap depth D in the completed magnetic head as shown in Fig. 3 when analyzing the reliability of the magnetic head.

However, the gap is concealed within the recess 4 in the completed magnetic head.

Therefore, it is difficult to measure the dimension of the finished gap depth accurately from the exterior after the magnetic core 7 has been inserted in the recess 4 and the core 7 and the rail 3 have been ground. It would be possible to measure the gap depth D in advance before the magnetic core 7 is inserted in the recess 4, and determine an approximate dimension of the gap depth in the ground magnetic head from the measured gap depth D. However, the relative positions of the magnetic core 7 and the core holder 2 as they are fixed would be varied, and the rail 3 and the gapped surface of the magnetic core 7 would not be ground to a constant depth due to the varied relative positions. As a consequence, the gap depth as determined after it has been finished would not be accurate.

The present invention provides a floating magnetic head which allows the dimension of a gap depth to be easily measured after a magnetic core has been assembled in a core holder.

According to the present invention, there is provided a magnetic head including a magnetic core having a reference surface parallel to a gapped surface, and a core holder having a recess, the magnetic core being fixed to the magnetic core so that the reference surface is exposed in a coil slot in the core holder.

According to the present invention there is further provided a floating magnetic head wherein a recess and a coil slot extending transversely across the recess are defined in a core holder, a magnetic core having a gap is inserted in said recess, and a coil is wound around a portion of said magnetic core which is disposed in said coil slot, characterised in that said magnetic core has a reference surface parallel to a gapped surface, and in that said magnetic core is fixedly mounted in said recess so that said reference surface is exposed to view in said slot.

A floating magnetic head embodying the present invention will now be described with reference to the accompanying diagrammatic drawings in which: Figure 1 is a side elevational view of a floating magnetic head of the present invention; Figure 2 is a side elevational view of a magnetic core prior to being inserted in the floating magnetic head shown in Fig. 1; Figure 3 is a perspective view of a previously proposed floating magnetic head; and Figure 4 is a side elevation of the magnetic core of Fig. 3.

The magnetic core 7 shown in Fig. 2 is basically of the same construction as that of the conventional magnetic core (see Fig. 4), and has a window 10 for positioning a coil therein, the window 10 has a bottom serving as a reference surface A parallel to a gapped surface. The magnetic core 7 has a measured dimension I, between the reference surface A and a gap depth D.

In assembly, the magnetic core 7 is inserted in a recess 4 in a core holder 2, and fixed to the core holder 2 as by glass melting. At this time, the reference surface A is positioned so as to project from the bottom of a coil slot 5.

Thereafer, the rail 3 of the core holder 2 and the gapped surface of the magnetic core 7 are ground down until they lie flush with each other, and a coil (not shown) is wound through the coil slot 5 around the magnetic core 7, whereupon the magnetic head is com pleted. Designated at Dt in Fig. 1 is a gap depth in the completed magnetic head. The gap depth D, cannot directly be measured from the exterior since the gap depth D, is made slightly smaller than the gap depth D (Fig. 2) prior to assembly when the parts are ground.To solve this problem, a dimension 12 from the reference surface A of the magnetic core 7 as viewed through the coil slot 5 to the ground rail 3 (which lies flush with the gapped surface) is measured, and the dimen sion 11 measured earlier is substracted from the dimension 12: D = 12 - Ii to determine the gap depth D,.

The dimension of the gap depth D, thus calculated is highly accurate since both the dimensions Ii, 12 are measurable. Conse quently, the dimensional accuracy of the gap depth in the magnetic head can be increased.

With the arrangement of the embodiment described in Figs. 1 and 2, the gap depth can accurately be measured dimensionally by sub jecting actual measurements to an arithmetic operation in the magnetic head which has been completed by assembling the magnetic core in the core holder and grinding the gapped surface. Therefore, the dimensional accuracy of the gap depth can be increased to improve the reliability of the magnetic head.

Claims

1. A floating magnetic head wherein a recess and a coil slot extending transversely across the recess are defined in a core holder, a magnetic core having a gap is inserted in said recess, and a coil is wound around a portion of said magnetic core which is dis posed in said coil slot, characterised in that said magnetic core has a reference surface parallel to a gapped surface and in that said magnetic core is fixedly mounted in said re cess so that said referene surface is exposed to view in said coil slot.

2. A magnetic head comprising a mag netic core with an air gap and having a reference surface extending parallel to a gapped surface, and a core holder having a recess traversed by a coil slot, the magnetic core being accommodated in the recess and fixed to the magnetic core so that the refer ence surface is exposed to view in the coil slot of the core holder.

3. A magnetic head substantially as herein before described, with reference to Figs. 1 and 2 of the accompanying drawings.