JP2541902Y2 - Shield case for magnetic head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a shield case of a magnetic head used for a VTR, a tape recorder, and the like.

[Conventional technology]

Conventionally, there are three types of magnetic heads for recording, reproducing, and erasing.

FIG. 4 is an external perspective view of an example of the VTR audio / control / erase head (3).

As shown in the figure, a voice / control head (4) having a recording / reproducing function and an erasing head (5) are combined and fixed on a mounting base (13).
Among them, a shield case (1) is used for a voice / control head (4) having a recording / reproducing function in order to block external magnetic noise. Generally, a shield case is used for a recording / reproducing magnetic head.

FIG. 5 is a cross-sectional view of the shield case of the audio / control head (4) at the tape sliding surface opening. The manufacturing process will be described with reference to FIG. It is erected and fixed on the core mounting surface (14) of the core mounting plate (7). When one core (6) and the other core (6 ') are butted, a magnetic gap (8) is formed by sandwiching a titanium foil (not shown) or the like at the core butting surface on the shield case opening side. The formed core (6) and / or the other core (6 ') are provided with a wound bobbin with terminal (9). And
One core (6) and the other core (6 ') are abutted and fixed by a spring (not shown) or the like.
Then, after sealing, the center (11) and the gap (8) of the two opening portions of the shield case slide so as not to be displaced.
With the inside of one side wall of the shield case as a reference surface (12), the core mounting plate (7) is pressed against the reference surface (12) by an elastic material (not shown) such as a spring, and is attached to the shield case (1). Then, the shield case (1) is filled with an epoxy resin (10) and solidified. Thereafter, the tape sliding surface is polished with a grindstone or the like to complete the magnetic head.

If the gap between the center (11) and the gap (8) in the opening of the sliding surface of the shield case is displaced, the directivity with respect to external induction noise changes, and a noise failure occurs as a set of a VTR or the like. This is one of the important points of the magnetic head structure.

In recent years, weight reduction and miniaturization of a VTR (particularly a camera-integrated VTR) equipped with this type of magnetic head have been rapidly progressing, and further reduction in weight and size of the magnetic head is desired.

[Problems to be solved by the invention]

A large proportion of the weight of the magnetic head is a shield case made of a metallic magnetic material such as permalloy, and the weight reduction of the shield case has a great effect on the weight reduction of the magnetic head.

As a method of reducing the weight of the shield case, the thickness of the shield case may be reduced to a level at which the shield effect against external induction noise is not practically problematic.

However, when the thickness of the shield case is reduced, there are the following problems. Referring to FIGS. 6 and 7, FIG. 6 shows a conventional shield case, and FIG. 7 shows a gap when a thin shield case is used and other parts are conventional. The positional relationship between (8) and the center (11) of the opening of the sliding surface of the shield case is shown.

In the case of the conventional shield case shown in FIG. 6, which has been described in the above [Prior Art], the gap (8) and the center (11) of the shield case sliding surface opening are not displaced. As shown in FIG. 7, when the outer dimensions (W) of the shield case are the same as the conventional product and the thickness is reduced, the distance from the reference surface (12) of the shield case side wall to the center (11) of the shield case sliding surface opening portion is reduced. When the distance (L) is longer than that of the conventional product and the conventional core mounting plate (7) is used, the gap (8) and the center (11) of the shield case sliding surface opening position are misaligned. There is a problem that the directivity with respect to the external induction noise changes and a noise problem occurs as a set. There is also a method of responding by increasing the thickness of the core mounting plate (7) so as not to cause the above-mentioned displacement, but in this case, it is necessary to change the assembling facilities and jigs and tools used in the manufacturing process, resulting in a new investment. Is required, and there is a problem that causes an increase in manufacturing cost.

Another problem is that when the thickness of the shield case is reduced, the mechanical strength of the shield case itself is reduced, and when the tape sliding surface is polished with a grindstone,
There is also a problem that defective products are generated due to deformation of the shield case and the like.

[Means for solving the problem]

In order to solve the above problems, the present invention provides a core mounting plate having a core mounting surface, in which a magnetic core having a magnetic gap is fixed upright on the core mounting surface and slides on a magnetic recording medium. In a magnetic head in which the core mounting plate is accommodated in a magnetic head shield case having an opening for exposing the gap of the magnetic core to the sliding surface to be exposed, the core mounting plate is applied to the inner surface of the shield case. It is characterized in that a projection for positioning a core mounting plate to be brought into contact is provided.

[Action]

By offset-forming the projection on the inner surface of the shield case, the distance from the reference surface of the inner surface to the center of the opening of the shield case sliding surface can be kept constant. Also, the mechanical strength is improved.

〔Example〕

Hereinafter, embodiments of the present invention will be described. FIG. 1 is a perspective view of an outer appearance of a shield case according to an embodiment of the present invention, and has a projection for a core attachment positioning portion for bringing a core attachment plate into contact with an inner surface of the shield case. FIG. 2 is a cross-sectional view at the opening of the sliding surface of the shield case of the above embodiment.

The thickness of the conventional shield case shown in FIG.
Assuming that the outer width (W) is 60 mm and the outer width (W) is 5.50 mm, the distance (L) from the reference surface (12) of the shield case side wall to the center (11) of the shield case sliding surface opening is: It becomes 2.15 mm from the formula [1].

On the other hand, as shown in FIG. 7, the thickness of the shield case is, for example, 0.45 mm, and the outer width (W) is 5.50 mm, which is the same as the conventional case.
If there is no offset, the distance (L) from the reference plane (12) on the side wall to the center (11) of the opening on the sliding surface of the shield case is From equation [2], it is 2.30 mm. Therefore, when there is no offset as shown in FIG. 7, the gap (8) of 0.15 mm and the center (11) of the opening of the sliding surface of the shield case are shifted. Therefore, as in the embodiment of the present invention shown in FIG. 8, a core mounting plate positioning projection (2) is provided on the inner side surface of the shield case, and the reference surface (12) is offset-formed with a dimension of 0.15 mm. The distance from the reference surface (12) to the center of the shield case sliding surface opening (11) is 2.15 mm, the same as the conventional product, and the gap (8) and the center (11) of the shield case sliding surface opening are misaligned. Does not occur.

Regarding the above offset processing, after the conventional shield case processing is completed, even if offset processing is added,
There is no problem if it is performed simultaneously with the conventional processing.

Regarding the shape of the protrusion (2), whether it is rectangular as shown in FIG. 1 or elliptical as shown in FIG. 3, the core mounting plate (7), that is, the magnetic core is formed on the shield case reference surface (1).
Any shape can be used as long as it is pressed against 2) and positioning is performed stably.

There is no problem with the offset on either one side (reference surface side) or both sides of the shield case side surface.

〔effect〕

As described above, according to the present invention, even if the thickness of the shield case is reduced, other conventional parts, assembling equipment, jigs and tools constituting the magnetic head can be used, and the mechanical strength of the shield case can be used. The magnetic head can be reduced in weight in a state in which the magnetic head has been improved, so that an inexpensive magnetic head can be provided which suppresses manufacturing costs and has no problems in characteristics and quality.

[Brief description of the drawings]

FIG. 1 is a perspective view of an outer appearance of a shield case for a magnetic head according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view showing the structure of the shield case of the embodiment of the present invention, and FIG. 3 is a second embodiment of the present invention. Figure 4 is a perspective view of the external appearance of the shield case.
FIG. 5 is a cross-sectional view of a sound / control head, FIG. 6 is a cross-sectional view showing the positional relationship of a magnetic head in a conventional shield case, and FIG. 7 is only a change in the thickness of the shield case. FIG. 8 is a cross-sectional view showing the positional relationship of the magnetic head in the shield case of the present invention. DESCRIPTION OF SYMBOLS 1 ... Magnetic head shield case, 2 ... Projection, 6 ... Magnetic core, 7 ... Core mounting plate, 8 ... Gap

Claims (1)

(57) [Scope of request for utility model registration] A magnetic core having a magnetic gap formed on a core mounting plate having a core mounting surface is fixed upright on the core mounting surface, and a magnetic core is mounted on a sliding surface sliding on a magnetic recording medium. In a magnetic head in which the core mounting plate is accommodated in a magnetic head shield case having an opening facing the gap, an inner surface of the shield case is in contact with the core mounting plate for positioning the core mounting plate. A magnetic head comprising a projection.