GB2165081A - Magnetic head - Google Patents

Abstract

A magnetic head includes a magnetic core (13), insulative coatings (18) on at least those side surfaces (22) of the magnetic core (13) which face the central opening (16), and coils (19) wound around the magnetic core (13) and extending through said opening (16) with the insulative coatings (18) interposed between the coils (19) and the core surfaces (22). <IMAGE>

Description

SPECIFICATION Magnetic head Background of the invention The present invention relates to a magnetic head, and more particularly to a coil attachment structure for a magnetic head.

Conventional magnetic heads include those which have a coil wound directly on a magnetic head core for use in VTRs, for example.

Such a prior magnetic head is of a construction as shown in Figures 1 and 2 of the accompanying drawings. A magnetic head core (hereinafter referred to as a "core") 1 has a centrally open structure with a central opening 2 for forming a closed magnetic path therethrough when recording and reproducing signals on and from a magnetic recording medium (not shown). The core 1 has a gap 3 defined in its front end (upper end as shown in Figure 1) for recording and reproducing signals on and from the magnetic recording medium, with a glass layer 4 being fused in the gap 3. Coils 6 are wound directly on laterally spaced arms (hereinafter referred to as "coil winding portions") 5 of the core 1.

Since each of the coil winding portions 5 has corners 7, coatings on the coils 6 are liable to be damaged by the corners 7, resulting in electric contact between the coils 6 and the core 1. An attempt has been made to eliminate such a problem by removing the corners 7 to round the core 1.

However, the rounding process is tedious and time-consuming because it requires fine machining steps.

Summary of the invention It is an object of the present invention to provide a magnetic head which can be manufactured with ease and has coils protected against damage to their coatings.

According to the present invention, there is provided a magnetic head comprising a magnetic core having an opening to define a magnetic path, insulative coatings on at least side surfaces of the magnetic core which face the opening, and coils wound around the magnetic core and extending through said opening with the insulative coatings interposed therebetween.

The above and other objects, features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.

Brief decription of the drawings Figure 1 is a plan view of a conventional magnetic head; Figure 2 is an enlarged cross-sectional view taken along line A-A of Figure 1; Figure 3 is a plan view of a magnetic head according to the present invention, with coils being shown in phantom; and Figure 4 is an enlarged cross-sectional view taken along line B-B of Figure 3.

Description of the preferred embodiment As shown in Figure 3, a first core member 9 of a substantially C shape and a second core member 10 of a substantially reversed-C shape are made of a metal material or a magnetic material of high permeability such as single-crystal ferrite. Each of the first and second core members 9, 10 has a recessed step 8 defining a core arm or coil winding portion 11 on which a coil 19 is wound. The first and second core members 9, 10 are joined through end surfaces 12 to provide a magnetic head core (hereinafter referred to as a "core") 13. The first and second core members 9, 10 have recesses 20, respectively, opening toward each other, so that they jointly define a central opening 16. The core 13 has a gap 14 defined in a front end (upper end as shown in Figure 3) for recording and reproducing signals on and from a magnetic recording medium (not shown).A glass layer 15 is fused in the gap 14 to give the gap 14 a predetermined clearance. As illustrated in Figure 4, the recessed steps 8 and the recesses 20 have side surfaces 21, 22 covered with glass coatings 18 on which the coils 19 are wound.

The glass layer 14 and the glass coatings 18 are simultaneously applied when the first and second core members 9, 10 are joined together. More specifically, a predetermined amount of glass is applied to surfaces of the first and second core members 9, 10 which define the gap 14, the side surfaces 21 of the recessed steps 8, and the side surfaces 22 of the recesses 20. Then, the core members 9, 10 are combined together and placed in a high-temperature furnace (not shown) in which the combined core members 9, 10 are rotated. The melted glass is uniformly filled in the glass 14 to form the glass layer 15. At the same time, the uniform glass layers 18 are formed on the side surfaces 21, 22 due to rotation of the core members 9, 10. The assembled core 13 is then taken out of the high-temperature furnace, and the coils 19 are wound thereon to complete a magnetic head as shown in Figure 3.

The glass coatings 18 on the core 13 have smooth surfaces and prevent corners 17 of the core 13 from directly contacting the cores 19, which are therefore protected from damage to their coatings. The danger of the coils 19 and the core 13 contacting each other is greatly reduced or eliminated.

In the above embodiment, the glass layer 15 and the glass coatings 18 are made of glass of the same composition and formed in the same process. However, the glass layer 15 may be made of glass of a high-melting point, and the glass coatings 18 may be made of glass of a low-melting point. With such an alternative, the glass layer 15 is first formed, and then the glass coatings 18 are formed at a temperature lower than the temperature at which the glass layer 15 is formed. This modification can also fabricate the magnetic head as illustrated in Figure 3.

Where there are no recessed steps 18 in the coil winding portions 11 of the core 13 shown in Figure 3, the glass coatings 18 are applied only to the side surfaces of the coil winding portions 11 which face the central opening 16 to prevent the coatings of the coils 19 from being damaged.

While in the foregoing embodiment the coatings 18 are described as being made of glass, they may be made of an insulative material such as synthetic resin for preventing damage to the coatings of the coils 19.

With the arrangement of the present invention, insulative coatings are applied to at least side surfaces of a magnetic core which face a central opening for forming a closed magnetic path for magnetic recording and reproduction, and coils are wound on the magnetic core with the insulative coatings interposed therebetween. The coils are therefore prevented by the insulative coatings from damage to the coatings of the coils. The magnetic core can easily be manufactured and can automatically be assembled by a machine since the core is simple in construction and the danger of damage to coil coatings is reduced even if no special care is taken when winding the coils.

Although a certain preferred embodiment has been shown and described, it should be understood that many changes and modifications may be made therein without departing from the scope of the appended claims.

Claims (4)

1. A magnetic head comprising: (a) a magnetic core having an opening to define a magnetic path; (b) insulative coatings on at least side surfaces of said magnetic core which face said opening; and (c) coils wound around said magnetic core and extending through said opening with said insulative coatings interposed therebetween.

2. A magnetic head according to claim 1, wherein said magnetic core has recesses opening into said opening and defined by said side surfaces.

3. A magnetic head according to claim 1, wherein said magnetic core has second side surfaces facing away from said opening, including second insulative coatings on said second side surfaces, said coils being wound around said magnetic core with said second insulative coatings interposed therebetween.

4. A magnetic head substantially as hereinbefore described, with reference to Figures 3 and 4 of the accompanying drawings.