JPH0216411Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field of the Invention The present invention relates to the structure of a magnetic head, and particularly relates to the structure of a magnetic head, in which one recording signal in the running direction of a magnetic recording medium is magnetized and recorded in two magnetic bands with polarities in opposite phases. A magnetic recording and reproducing method (hereinafter referred to as a recording and reproducing method) that extracts the magnetic flux density difference between two recorded bands at the same point at the time of recording as one reproduction output.
The present invention relates to a magnetic head suitable for.

Prior Art and Problems In principle, the recording/reproducing system consists of a first core 1 having magnetic pole tips a and b, and a second core 2 having magnetic pole tips c and d, as shown in FIG. This uses magnetic heads which are combined into a ring shape and have two magnetic gaps 3 and 4 formed between two pairs of opposing magnetic pole tips. This magnetic head is formed so that its two sets of magnetic tips a to d are in contact with the surface of the magnetic recording medium 5 at the same time, and the portion away from the magnetic gap is curved upward. When recording using such a magnetic head, each magnetic head must be aligned so that the straight line connecting the magnetic gaps 3 and 4 is perpendicular to the running direction 6 of the recording medium 5, as shown in the figure. The magnetic tips a to d are set in contact with the recording medium. A signal current and a bias current are passed through the signal coil 9 wound around the first core 1 and the bias coil 10 wound around the second core 2, respectively, to move the recording medium 5. As a result, as shown in the figure, the same signals are magnetically recorded at the same time in two bands 7 and 8 on the recording medium with opposite polarities as represented by N-S and SN, respectively. In addition, during magnetic reproduction, the two sets of pole tips a to d of the magnetic head are set on the two magnetically recorded bands 7 and 8 so that they simultaneously contact the two bands 7 and 8 at the same time, By moving the recording medium 5 along the running direction, changes in the magnetic flux distribution existing in two bands are detected at the twin magnetic poles a and b of the first core and extracted as one reproduction output. A detailed explanation of the recording/reproducing system is described in, for example, Japanese Patent Publication No. 57-21763.

By the way, during reproduction, the area between the magnetic tips a and b of the first coil 1 forms part of the magnetic loop via the recording medium 5, so the magnetic resistance of that part is lowered to improve the reproduction characteristics. Therefore, it is desirable that the distance between the magnetic pole tips a and b be as short as possible. Therefore, in view of this problem and with the aim of making the magnetic head more compact, the present inventor fabricated a prototype magnetic head having a structure as shown in FIG. 2, for example.

In FIG. 2, 20 is a first
The core piece 21 is a second core piece having a magnetic pole tip b, and the first and second core pieces 20 and 21 are as follows:
They are laminated on a substrate 19 with non-magnetic signal guard spacers 22 on the magnetic pole tips a and b and a magnetic short spacer 23 on the other end, forming the first core 1 in FIG. do. Further, 24 is a third core piece having a magnetic pole tip c, and 25 is a fourth core piece having a magnetic pole tip d. A non-magnetic signal guard spacer 26 is placed on one end, and a magnetic short spacer 27 is placed on the other end to form the second core 2 shown in FIG. First core piece 20, second core piece 21, and third core piece 2
4 and the fourth core piece 25 have the same shape, and the coil 29 utilizes the space 28 surrounded by the first and second core pieces 20, 21, the signal guard spacer 22, and the short spacer 23. It is wound around one core piece 20. According to the magnetic head having the structure shown in FIG. 2, the signal guard spacer 22,
It is possible to adjust the reproduction sensitivity by changing the thickness of the space 23, and in fact, by changing the thickness of the space 28.
In experiments in which the inner core was set to 0.5 mm to secure the coil space and the thickness of the signal guard spacers 22 and 26 was set to 0.3 mm, sufficient reproduction sensitivity was obtained. However, recording sensitivity, on the contrary, decreased. For this reason, recording is carried out using a magnetic head with a ring structure as shown in Fig. 1, and the magnetic head shown in Fig. 2 must be used only for reproduction. It has been difficult to use a magnetic head for both recording and reproduction.

Purpose of the invention The present invention is an improvement over these conventional drawbacks, and aims to improve the recording sensitivity of a bipolar magnetic head with a laminated structure as shown in Figure 2, so that it can be used for both recording and reproduction. purpose.

Principle of the Idea The reason why the recording sensitivity decreases in the magnetic head having the structure shown in FIG. 2 is thought to be based on the following reasons. That is, in the structure of FIG. 2, the first core piece 20
Because the second core piece 21 is located very close to the part where the coil 29 of the first core piece 20 is wound, there is a
The magnetic flux leaking to the core piece 21 cannot be ignored, and the magnetic flux flowing to the magnetic pole tips a and c is extremely reduced. To prevent this, you can increase the distance between both coil pieces, but as mentioned above, the signal guard spacer 2
If the thickness of the coils 2 and 26 is increased, the reproduction sensitivity will be reduced, and if the distance is increased only in the vicinity of the winding portion of the coil, the shape of the core piece will become complicated.
Therefore, in the present invention, the above object is achieved by adopting a structure as described later in which the center portions of the core pieces 20 and 21 are spaced apart in the left-right direction.

Embodiment of the invention FIG. 3 is an external perspective view of an embodiment of the invention, and FIG. 4 is an exploded view thereof. In this embodiment, it is possible to record and reproduce stereo signals using two magnetic heads according to the present invention.

In FIGS. 3 and 4, 30 is a first core piece having a magnetic pole tip a, 31 is a second core piece having a magnetic pole tip b, and a non-magnetic signal guard is provided on the magnetic pole tips a and b sides. Laminated with a spacer 32 in between and a magnetic short spacer 33 on the other end,
It constitutes a first core. Further, 35 is a third core piece having a magnetic pole tip c, and 36 is a fourth core piece having a magnetic pole tip d. They are laminated with magnetic short spacers 38 interposed on their sides to form a second core. First core piece 3
The signal coil 39 is wound around the center of the first core piece 30. Similarly, the third core piece 35 and the fourth core piece 36 are shaped so that they do not overlap in their central parts, and a bias coil 40 is wound around the central part of the third core piece 35. It is passed around.

The first core and the second core are attached to one side of the shield plate 34 and used for recording and reproducing one channel signal of the stereo signal. On the other surface of the shield plate 34, a magnetic head having a structure similar to that described above is provided for recording and reproducing the other channel signal. That is, a first core piece 30' having a magnetic pole tip a' and around which a signal coil 39' is wound, a second core piece 31' having a magnetic pole tip b', a signal guard spacer 32', and a short spacer. A first core is formed at 33', has a pole tip c', and has a bias coil 40'.
A second core is formed by a third core piece 35' wound with a magnetic pole d', a fourth core piece 36' having a magnetic pole tip d', a signal guard spacer 37', and a short spacer 38'.

Since this embodiment has such a structure, the thickness of the signal guard spacers 32 and 37 can be changed, for example.
Even if the reproduction sensitivity is increased by making the first core piece 30 as thin as 0.2 mm, the part of the first core piece 30 where the signal coil 39 is wound is sufficiently far away from the second core piece 31. It is possible to reduce the magnetic flux leaking through the second core piece 31 from the vicinity of the part of the core piece 30 around which the signal coil 39 is wound (magnetic flux that does not pass through the magnetic pole tips a and b), and the signal coil It becomes possible to sufficiently supply the magnetic flux generated at 39 to the magnetic pole tips a and b. This point is the bias coil 40
The same holds true for the above, and therefore it is possible to increase the recording sensitivity. The dimensions of the recording track are as follows: The OGB (Audio Guard Band) that separates the left and right stereo signal tracks is 0.3 mm in accordance with the standard, and the left and right signal track width of 0.6 mm is further divided into two. Therefore, if the signal guard spacer of a bipolar head is made 0.2mm thick, each track will be 0.2mm wide.

Although two magnetic heads of the present invention were used in the above embodiments, only one is sufficient for recording and reproducing monaural signals. Alternatively, the bias coils 40, 40' may be omitted, and the bias current may be superimposed on the signal coils 39, 39'. Furthermore, if you want to simplify the configuration, use the corresponding dual magnetic pole structure.
It is also possible to get by with just a core with a thickness of about 0.6mm.
Further, it is also possible to configure the coils wound around the first core piece 30 and the third core piece 35 to be wound around the second core piece 31 and the fourth core piece 36.
In addition, when winding a coil around the first core piece 30 and the third core piece 35, it is preferable to reduce the thickness of the portion of the shield plate 34 indicated by the broken line because the coil space increases accordingly.

Further, in a configuration in which a coil is not wound around the third core piece 35, the second core can have a structure similar to that shown in FIG. 2.

Effects of the invention As explained above, according to the invention, a core piece around which a coil is wound and a core piece that is combined with this core piece to form one core are placed at the center of each other when stacked. Since the shape is such that the parts do not overlap, it is possible to reduce the leakage magnetic flux of the coil wound in the center, and it is possible to increase the recording sensitivity. Furthermore, since there is no overlapping portion, there is an advantage that the coil space can be sufficiently wide.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the principle of the recording/reproducing system, FIG. 2 is an external perspective view of a conventional magnetic head, FIG. 3 is an external perspective view of an embodiment of the present invention, and FIG. 4 is an exploded view thereof. 30 is a first core piece, 31 is a second core piece, 3
2, 37 are signal guard spacers, 33, 38
is a short spacer, 35 is a third core piece, 36
is the fourth core piece.

Claims (1)

[Scope of utility model registration request] A first core piece 30 having a magnetic pole tip a and a magnetic pole tip b
A first core formed by laminating a second core piece 31 having a magnetic material with a non-magnetic signal guard spacer 32 on the magnetic pole tips a and b side and a magnetic short spacer 33 on the other end side, A third core piece 35 having a magnetic pole tip c and a fourth core piece 36 having a magnetic pole tip d.
A second core is formed by laminating the magnetic poles with a non-magnetic signal guard spacer 37 on the pole tips c and d and a magnetic short spacer 38 on the other end,
Two core pieces are arranged to face each other so as to form a magnetic gap, and both core pieces constituting at least one of the first core and the second core are processed into a shape having no overlapping portion in the center thereof. A magnetic head characterized in that a coil is wound around the center of one of the core pieces.