JPH0658403U - Multi-element magnetic head - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a multi-element magnetic head in which noise entering from the outside is prevented from entering the core. [Structure] A plurality of magnetic cores 2 are provided, and a magnetic shield plate 3 is arranged between the plurality of magnetic cores 2.
A multi-element magnetic head housed in a magnetic core 2-1 disposed on the outermost side of the plurality of magnetic cores 2;
Magnetic shield plates 6a and 6b are further arranged between 2-4 and the shield case 1.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a magnetic head for recording or reproducing information on a magnetic recording medium, and more particularly to a multi-element magnetic head.

[0002]

[Prior art]

 FIG. 4 shows an example of a conventional multi-element magnetic head (hereinafter referred to as head). FIG. 4A is a view of the head as seen from the recording medium contact surface side, and FIG. 4B is a partial cross-sectional view of the inside of the head. In the head 10 shown here, with the left and right magnetic circuit forming cores 12a 1 and 12b joined together, the core 12 into which the bobbin 15 1 having the electromagnetic conversion coil wire 16 wound is inserted into the core holders 14a and 14b. It is attached and housed in a magnetic shield case 11 to prevent external noise. A magnetic shield plate 13 is arranged between the tracks.

[0003]

[Problems that the device is trying to solve]

 With the advances in electronics, there are many sources of noise around the head as described above. In the head 10 shown in the above-mentioned conventional example, noise that enters from the outside of the head 10 cannot be blocked only by the shield case 11, and even penetrates into the core 12. This noise is reproduced as a noise signal by the coil wire 16, and when it is applied to the reproduced signal, it is output as a sound from the speaker, and the noise is mixed into the normal signal.

In view of the above problems, the present invention has an object to provide a multi-element magnetic head in which noise that enters from the outside does not enter the core.

[0005]

[Means for Solving the Problems]

 In order to solve the conventional problems and achieve the above object, the present invention has a plurality of magnetic cores, a magnetic shield plate is arranged between the plurality of magnetic cores, and the magnetic shield plates are housed in a shield case. In the multi-element magnetic head, the magnetic shield plate is further arranged between the outermost magnetic core of the plurality of magnetic cores and the shield case.

[0006]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a view showing an embodiment of the present invention, and FIGS. 1 (a) and 1 (b) are views seen from different directions, and are partially shown in section. 1 is a shield case to prevent external noise. Reference numeral 2 is a magnetic core for forming a magnetic circuit, and in this embodiment, four magnetic cores 2-1, 2-2, 2-3, 2-4 are provided. 3 (3-1, 3-2, 3-3) are magnetic shield plates arranged between the four cores 2 to prevent magnetic leakage. Reference numerals 4a and 4b denote core holders for holding and fixing the magnetic core 2 and the magnetic shield plate 3, respectively. Numeral 5 is a bobbin around which a coil wire for converting a magnetic flux passing through the magnetic circuit into a current is wound, and is inserted in each core 2. Reference numerals 6a and 6b denote magnetic shield plates for preventing external noise from entering the core, which are formed of permalloy and are arranged between the shield case 1 and the outermost cores 2-1 and 2-4. Has been done. The magnetic shield plates 6a and 6b are also fixed to the core holders 4a and 4b similar to the core 2 by means such as welding and adhesion. Alternatively, holes (not shown) may be provided in the magnetic shield plates 6a, 6b, and protrusions (not shown) may be provided in the core holders 4a, 4b to fit and fix the holes and protrusions. After the above-mentioned members except the shield case 1 are integrally assembled, they are housed in the shield case 1 as shown by the arrows in FIGS. 1 (a) and 1 (b).

A head in which a coil wire wound around a bobbin 5 as shown in FIG. 1 is arranged at the bottom of a core 2, that is, a so-called back winding head is shown in FIG. The magnetic field in the axial direction of the core 5) is most likely to enter as noise, but the core 2-2 arranged on the inner side has the other cores 2-1 and 2-3 and the shield plates 3-1 and 3-1 on the outer side. Since 3-2 is arranged, the influence of noise is smaller than that of the outermost cores 2-1 and 4-4. Similarly, since the core 2-3 also has the other cores 2-2, 2-4 and the shielding plates 3-2, 3-3 on the outer side thereof, the influence of noise affects the outermost cores 2-1 and 2-. Less than 4

Therefore, in order to prevent noise from entering the outermost cores 2-1 and 4-4, as described above, in the present embodiment, the shield case 1 and the outermost core 2-1 are arranged. , 2-4 are arranged between the magnetic shield plates 6a and 6b. With this configuration, noise that attempts to enter the outermost cores 2-1 and 4-4 is bypassed to the magnetic shield plates 6a and 6b together with the shield plates 3-1 and 3-3 to prevent the intrusion. It is possible. In the present embodiment, the magnetic shield plates 6a, 6b as well as the shield plates 3-1, 3-2, 3-3 are projected from the respective cores 2 in the AA direction of FIG. 1B. Since it is formed, noise tends to be directed toward the shield plate 3 and the magnetic shield plates 6a and 6b.

FIG. 2 shows external induction noise frequency data of an example in which the head having the above-described structure is applied to the cassette 4ch reproducing head. As is clear from the results shown in this figure, the improvement effect was observed in the wide frequency band of 31.5 Hz to 10 kHz in which this measurement was performed, and the improvement effect was observed particularly in the band of 1 kHz or more, which is likely to cause a hearing problem. Is big. More specifically, in the band of 2 kHz or higher, the noise channel difference between the outer channel and the inner channel was improved to about 1/2 as compared with the conventional head.

In the present embodiment, the magnetic shield plate disposed between the shield case and the outermost core is divided into two bodies in consideration of the directionality of noise intrusion, cost, etc. If formed by, the shield characteristics will be further improved. The two magnetic shield plates may be integrated with each other by connecting arbitrary portions.

As a method of integration, as shown in FIG. 3 (a), a structure in which the portions 6c and 6d contacting the inside of the tape running surface of the shield case are connected, and FIG. As shown, there is a configuration in which only the protruding portion of the terminal on the terminal protruding surface 6e is formed into a shape escaped by the hole 6f and connected. In particular, if the connection is made at the terminal protruding surface, the influence of noise from the rear part of the head can be greatly reduced, and the induced noise characteristic is further improved by about 3 dB.

Further, as shown in FIG. 3 (c), a shield plate may be formed so as to cover the side surface of the head, and as shown in FIG. 3 (d), as shown in FIG. 3 (b). The shape shown and the shape shown in FIG. 3C may be combined.

Further, as shown in FIG. 3 (e), the shield plate 6 has a shape similar to that of the shield case 1 (FIG. 1) and is substantially in close contact with the inside of the shield case 1. The shield plate is arranged in all directions except the rear part, and the noise blocking effect can be maximized.

Further, as shown in FIG. 3F, the shield plates 6a-1 and 6a-2 and the shield plates 6b-1 and 6b-2 are laminated with a plurality of magnetic materials of the same kind. Alternatively, by using a laminated structure in which a magnetic material and a non-magnetic material are laminated, it is possible to improve the high-frequency characteristics of noise blocking and to provide excellent induction noise characteristics for high-frequency noise. .

Further, as shown in FIGS. 3 (g) and 3 (h), a part of the shield plates 6a, 6b is extended so as to project from the terminal projecting surface, and the ground terminals 7a, 6b It can also be used as 7b. With this structure, it is possible to eliminate the ground terminal, which was previously required as a separate component, and it is possible to supply an inexpensive magnetic head with excellent noise characteristics.

Further, in the present embodiment, the tip of the magnetic shield plate is formed by bending at a slight angle in consideration of noise sneaking in, the shape of the shield case, etc., but a bent portion should be provided. It may be formed without.

As a method of attaching the shield plate, a method of adhering it to the core holder, a method of fixing it to the core holder by fitting, a method of fixing it to the shield case in advance by welding or the like can be considered.

Further, as shown in FIG. 3 (i), elastic portions 8a, 8b are formed on a part of the shield plates 6a, 6b so that they can be inserted into the shield case 1 (FIG. 1). Then, the leaf spring used to crimp the core holder and the shield case is not used, and the cost can be reduced.

As the material of the shield plate, the above-mentioned permalloy material is the most general, but it is also the same as long as it is the material used for the magnetic core such as amorphous, ferrite, sendust and the magnetic shield plate. The noise suppression effect of is obtained.

[0021]

[Effect of device]

 As is clear from the above description, according to the configuration of the present invention, the magnetic shield plate is arranged between the shield case and the outermost core, so that the intrusion of external inductive noise into the core can be significantly reduced. You can

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of the present invention, which is shown in FIG.
(B) is the figure which looked at each from a different direction,
It is shown in a partial cross section.

FIG. 2 is a graph showing external induction noise frequency data of an embodiment when the head having the structure according to the present invention is applied to a cassette 4ch reproducing head.

FIG. 3 is a view showing various examples of the structure of the shield plate in the embodiment of the present invention, FIG. 3 (a) is a view showing the connection on the tape running side, and FIG. 3 (b) is a terminal protruding side. FIG. 3 (c) is a view showing the head side surface extended, FIG. 3 (d) is a view showing the terminal projection side connecting and extending to the head side surface, and FIG. -Rudoke-
FIG. 3 (f) shows a laminar structure, and FIG. 3 (g) shows a partially extended ground terminal. FIG. 3 (h) is a diagram showing a partly extended ground terminal, and FIG. 3 (i) is a diagram showing a partly elastic structure.

4A and 4B are views showing a conventional example, in which FIG. 4A is a view of a head as seen from a recording medium contact surface side, and FIG.

[Explanation of symbols]

 1 shield case 2 magnetic core 3 magnetic shield plate 4a core holder 4b core holder 5 bobbin 6a magnetic shield plate 6b magnetic shield plate 7a earth terminal 7b earth terminal 8a elastic portion of magnetic shield plate 8b elastic portion of magnetic shield plate

Claims (7)

[Scope of utility model registration request] 1. A multi-element magnetic head having a plurality of magnetic cores, wherein a magnetic shield plate is arranged between the plurality of magnetic cores and housed in a shield case. A multi-element magnetic head characterized in that a magnetic shield plate is further arranged between the outermost magnetic core and the shield case. 2. The multi-element magnetic head according to claim 1, wherein the magnetic shield plates are connected on the magnetic tape running side to have an integral structure. 3. The multi-element magnetic head according to claim 1, wherein a part of the shield plate is arranged so as to project from the shield case on the exposed side of the terminal. 4. The shield plate according to claim 1, wherein:
A multi-element magnetic head characterized in that the terminals are connected on the exposed side to form a one-piece structure. 5. The seam according to claim 1 or 4,
A multi-element magnetic head characterized in that the shield plate is further arranged in a plane parallel to the gap between the magnetic core and the shield case. 6. The shield plate according to claim 1, wherein:
It has a shape similar to the shield case, and this shield
A multi-element magnetic head, characterized in that the outside of the shield plate is formed so as to substantially contact the inside of the shield case. 7. The shield plate according to claim 1, wherein:
A multi-element magnetic head having a structure in which a plurality of sheets are superposed.