JP2572212B2 - Shield plate for magnetic head - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield plate for a magnetic head, and more particularly, to a reduction in the thickness of a shield plate.

[Prior art] A multi-channel magnetic head has many small members such as a magnetic core constituting each magnetic head unit and a shield plate for shielding between the magnetic head units. Various methods are used for positioning and arranging the components.

As such a positioning method, a hold case is provided, a groove is formed in the hold case, and various members such as a magnetic core and a shield plate are incorporated in the groove, and fixed by an adhesive or a synthetic resin for positioning. Method. Alternatively, a member replacing the groove of the hold case (for example, US Pat.
484,564) to the bottom of the hold case,
A method of positioning by incorporating each member such as a shield plate and a magnetic core into this member. Furthermore, there is a method of pressing each member such as a shield plate and a magnetic core against a front inner wall of the hold case with a spring member or the like, and positioning with reference to the inner wall.

FIG. 4 is a front view of a conventional multi-channel magnetic head. This magnetic head is used, for example, as a magnetic head for auto-reverse of a cassette type tape recorder, and includes a forward magnetic head unit including a right channel and a left channel magnetic head unit.
FIG. 4 shows the surface of each of the magnetic head units 101 and 102, which is in sliding contact with the magnetic tape, in sliding contact with the magnetic tape. As shown in FIG. 6, a magnetic shield plate 103 made of permalloy or the like is provided between the forward magnetic head unit 101 and the reverse magnetic head unit 102,
A center shield plate assembly 106 formed by sandwiching the nonmagnetic metal plates 104 and 105 made of a copper alloy or the like provided on both sides of the magnetic shield plate 103 is provided. The reason why the magnetic shield plate 103 is formed in a sandwich shape by the nonmagnetic metal plates 104 and 105 is that the magnetic cores 110 and 111 of each magnetic head unit are
This is to prevent a magnetic short circuit. In order to prevent crosstalk between channels, shield plate assemblies 107 and 108 are also provided between the right and left channel magnetic heads of the forward magnetic head unit 101 and the reverse magnetic head unit 102.

FIG. 5 is a sectional view showing the internal structure of the multi-channel magnetic head shown in FIG. As can be seen from the figure, the central shield assembly 106 has one end surface thereof flush with the magnetic pole surfaces of the magnetic head units 101 and 102, and the other end extending downward to near the bottom of the shield case body 100. And the center shield plate assembly 10 near the pole face.
Positioning is performed by pressing leaf springs 117, 118 and the like provided on the side portion of No. 6. Further, coil bobbins 113, 114, 115 and 116 are provided at the lower ends of the magnetic cores 109, 110, 111 and 112 constituting each magnetic head unit, and coils are wound around the coil bobbins 113, 114, 115 and 116, respectively. Has been turned. This coil bobbin 113, 114, 115, 116 is almost occupied by each coil,
The central shield plate assembly 106 extends between 114 and 115, and the central shield plate assembly 106
Occupy extra spacers.

In the formation of the center shield plate assembly 106, the magnetic shield plate 103 and the nonmagnetic metal plates 104 and 105 are separately formed, aligned, and joined in a sandwich shape.

[Problems to be Solved by the Invention] By the way, as the size of the magnetic head is reduced, it becomes difficult to secure a coil winding spacer. There is a problem that the plate assembly 106 occupies and hinders the extra spacer.

In view of the above problems, an object of the present invention is to provide a shield plate for a magnetic head which secures a space for accommodating a coil having a large number of windings and which can reduce the size of the magnetic head.

[Means for Solving the Problems] To achieve the above object, the present invention provides a method in which a non-magnetic metal plate is laminated on both surfaces of a magnetic metal plate interposed between a plurality of magnetic cores wound with a coil bobbin. In the magnetic head shield plate described above, the vicinity of the coil bobbin of the shield plate is compressed, and the plate thickness at that portion is reduced.

[Operation] According to the configuration of the present invention, the vicinity of the coil bobbin of the shield plate is compressed and the thickness of the portion is formed thin, so that a sufficient spacer for installing the coil bobbin can be secured.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the internal structure of a magnetic head according to one embodiment of the present invention. The magnetic head shown in FIG.
It is housed in a shield case 1 and used as a magnetic head for auto-reverse of a cassette type tape recorder, for example, as in the conventional example. The magnetic head unit 2 for forward and the magnetic head unit 3 for reverse
have. The forward and reverse magnetic head units 2 and 3 have magnetic cores 7 and 8 constituting a left channel magnetic head unit and magnetic cores 9 and 10 constituting a right channel magnetic head unit, respectively. One end of the core is exposed from the opening of the shield case 1 to form pole faces 7a, 8a, 9a, and 10a. The magnetic pole surfaces are formed on the same surface, and constitute a magnetic tape sliding contact surface 11 on which the magnetic tape slides. Each magnetic core 7,
The other end of each magnetic core extending in the direction opposite to the magnetic tape sliding contact surface 11 of 8, 9 and 10 has coil bobbins 12, 13 and 1 respectively.
4, 15 are attached, and each of these coil bobbins 12, 13, 1
The coils are wound around 4 and 15. Leads (not shown) from each coil are connected to terminals 16 and 1 fixed to terminal plate 20.
It is connected to 7, 18, and 19 and led to the outside.

Between the magnetic core 9 of the forward magnetic head unit 2 and the magnetic core 8 of the reverse magnetic head unit 3, for example, a central shield plate 21 made of a magnetic material such as permalloy is provided. This central shield plate 21
One end thereof is disposed so as to form the same surface as the magnetic tape sliding contact surface 11, and the other end on the opposite side extends close to the terminal plate 20, whereby the space between the magnetic cores 8 and 9 and the magnetic cores 8 and The coils between the coils 9 are magnetically shielded. In the vicinity of the magnetic tape sliding contact surface 11 of the shield plate 21, non-magnetic spacers 22a and 22b for forming a predetermined space between the central shield plate 21 and the magnetic cores 8 and 9 facing each other are provided. The central shield plate 21 is provided so as to sandwich the central shield plate 21, and the central shield plate assembly 4 and the nonmagnetic spacers 22a and 22b constitute the central shield plate assembly 4. The nonmagnetic spacers 22a and 22b are formed of, for example, a copper alloy, nickel silver, beryllium copper, titanium copper alloy, or the like. The non-magnetic spacers 22a and 22b are provided with a predetermined interval between the adjacent magnetic cores 8 and 9 to prevent a magnetic short circuit, and define a positional interval between the magnetic cores 8 and 9. I have.

Further, non-magnetic metal plates are provided on both sides of the magnetic metal between the left and right channel magnetic cores 7 and 9 and between 8 and 10 which constitute the forward and reverse magnetic head units 2 and 3, respectively. Shield plates 5 and 6 stacked in a sandwich shape are provided, respectively, to prevent crosstalk between channels.

As described above, each member such as the magnetic core, the shield plate, and the coil bobbin that constitute the magnetic head is a hold case 23.
And is assembled in the shield case 1 and is filled with a synthetic resin and fixed.

FIG. 2 shows the central shield plate 21 and the non-magnetic spacer.
It is a perspective view which shows 22a and 22b. Non-magnetic metal plate 31 described later
When a and 31b are relatively soft, the shield plate 21 is configured so that the vicinity of the coil bobbins 13 and 14 is compressed, and the plate thickness at that portion is reduced. As a result, the space occupied by the non-magnetic spacers 22a and 22b other than the vicinity of the magnetic tape sliding contact surface 11 is secured on both sides of the center shield plate 21, and the coil is wound using this space. The number of times can be increased. Therefore, even when the magnetic head is formed thin and small, the number of turns of the coil can be increased without limiting the space as compared with the conventional case.

Next, a method of manufacturing the center shield plate assembly 4 will be described. FIG. 3 shows a conceptual diagram from a metal plate to a shield plate assembly 4. Magnetic metal plate 30 and non-magnetic metal plate 31 used as materials for shield plate assembly
a and 31b are supplied as hoop materials, for example, each with a thickness of 0.2 mm, and are laminated with both surfaces of the magnetic metal plate 30 sandwiched between the non-magnetic metal plates 31a and 31b so as to have the same structure as the central shield plate assembly 4. I do. In the figure, 33 is a guide roller, 34 is a welding machine or rolling machine, 35 is a press machine, and the laminated metal plate 32
For example, by laser welding, spot welding, pressure bonding using a resin or the like, and the non-magnetic metal plates 31a and 31b are joined to the magnetic metal plate 30.
Fixed to Then, it suffices to perform the extraction and press working to compress the non-magnetic metal plates 31a and 32b by the space to be taken in the vicinity of the coil bobbin.

[Effects] As described above, according to the present invention, a shield for a magnetic head in which a non-magnetic metal plate is laminated on both surfaces of a magnetic metal plate interposed between a plurality of magnetic cores wound with a coil bobbin. In the plate, the vicinity of the coil bobbin of the shield plate is compressed, and the thickness of the portion is reduced, so that a sufficient space for installing the coil bobbin can be secured. Therefore, the coil can be wound more times, and a high-performance and highly reliable magnetic head can be obtained. In addition, even when the magnetic head is thin and small, the number of turns of the coil is not limited, and the coil can be wound. It can be wound appropriately. Furthermore, by arbitrarily setting the pressure at the time of compression, a shield plate having an arbitrary thickness can be formed, and it is possible to immediately cope with coil bobbins of various shapes and sizes.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the internal structure of a magnetic head for another channel showing one embodiment of the present invention, FIG. 2 is a perspective view of a shield plate of the present invention used in the magnetic head of FIG. FIG. 3 is a conceptual diagram showing a process of forming a shield plate from materials, and FIG.
5 and 5 are a front view and a sectional view, respectively, of a conventional magnetic head, and FIG. 6 is a perspective view of a shield plate used at that time. 1 Shield case 2, 3 Magnetic head unit 4 Shield plate (or shield plate assembly) 11 Magnetic tape sliding contact surface or magnetic pole surface 21 Central shield plate 22a, 22b Nonmagnetic Spacer 23 … Hold case 30… Magnetic metal plate 31a, 31b… Non-magnetic metal plate 33… Guide roller 34… Welding machine or rolling machine 35… Breathing machine

Claims (1)

(57) [Claims] 1. A magnetic head shield plate in which a non-magnetic metal plate is laminated on both sides of a magnetic metal plate interposed between a plurality of magnetic cores around which a coil bobbin is wound. A shield plate for a magnetic head, wherein the shield plate is compressed and the thickness of the portion is reduced.