JPS59215005A - magnet erase head - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic erase head for erasing magnetic tape used in magnetic recording devices such as tape recorders.

Conventional structure and its problems As magnetic recording and reproducing devices using magnetic tape become smaller and more power efficient, the erase head for erasing magnetic tape has a relatively small shape that consumes a large erasing current (power). Magnetic erasing heads, which do not require erasing current, are increasingly being used in place of large AC erasing heads, and in recent years, there has been a desire for their smaller size and higher performance.

A conventional example of this magnetic erase head will be explained with reference to FIGS. 1 to 5. 1 is a magnetic tape, 2 is a tape guide, 3 is a recording/playback head, 4 is its core, 5 is a conventional magnetic erase head, 6 is its core, and 7 to 10 are magnetized core 6 of the magnetic erase head 6. A magnetizing magnetic pole 11 is a magnetizing device for magnetizing the conventional magnet erase head 5, 12 to 16 are magnetizing windings thereof, and 16 to 19 are magnetizing yokes. The conventional magnetic erase head 6 has a core 6 having magnetized magnetic poles having different polarities adjacent to each other in the running direction (arrow) of the magnetic tape 1, as shown in FIG. 2, and as shown in FIG. The strength of the magnetized magnetic pole is configured to gradually attenuate in the running direction of the magnetic tape.

Note that a, b, c, and d in FIG. 3 are the magnetization strengths of the magnetization poles 7, 8, 9, and 10, respectively, and are the magnetization strengths of the core 6 of the conventional magnet erase head 6? , 8.9 and 1
o denotes magnetizing yokes 16 and 17 of the magnetizing device 11 shown in FIG.
．． 18 and 19 are respectively pressed and magnetized by applying a magnetizing current to the magnetizing windings 12, 13, 14, and 16 wound around the magnetizing yoke. The magnetization strength is determined by the width of the magnetizing yoke, the magnitude of the magnetizing current, and the number of turns of the magnetizing winding.

Can be controlled by wire diameter and position.

Now, as shown in FIG. 1, when the front surface of the conventional magnetic erasing head 5 is run in the direction of the arrow in order to erase the magnetic tape 1, the magnetic tape 1 is The process of demagnetization (magnetization) of the magnetic tape 1d will be explained with reference to FIG. The residual magnetic flux density is gradually attenuated to zero at the magnetized magnetic poles 8 to 10 <lK magnetization is added J]. However, in this case, changes in the magnetization strength of the magnetized magnetic pole due to variations in the magnetic properties of the core (') quality, changes in magnetization conditions, changes in the welding between the core 6 and the magnetic tape 1, etc. As shown in Fig. 5, when the magnetization of the magnetic tape 1-. by the magnetized magnetic pole 9 changes from C to C', a residual magnetic flux density e of 5,' ゛- occurs on the magnetic tape 1 after erasing, resulting in noise during playback. (erasure noise) and distortion during recording.

In order to eliminate this drawback, it is possible to increase the number of magnetized magnetic poles so that residual magnetic flux density is less likely to occur even if the magnetization changes as described above, but the conventional magnet erase head 5 Generally, magnetization is performed using a magnetization device 11 as shown in Fig. 4, so in order to prevent magnetic saturation of the magnetization yoke during magnetization, the width (thickness) cannot be made too narrow, and as a result, the magnetization The width of the magnetic pole cannot be narrowed. Unfortunately, the distance between the magnetized magnetic poles could not be narrowed due to the space of the magnetized winding and its insulation, and a sufficient number of magnetized magnetic poles could not be obtained. The magnetization strength is also greatly affected by the degree of close contact between the core of the magnet erase head and the magnetization yoke of the magnetization device during magnetization, and a stable one cannot be obtained.

Purpose of the Invention The present invention solves the above-mentioned conventional problems, and is intended to provide a magnetic erasing head for small cassette tape recorders and micro cassette recorders that is stable within a limited core width dimension in order to achieve miniaturization and high performance. 6. It is an object of the present invention to realize a multi-magnetized magnetic pole having a high magnetization strength, reduce noise during reproduction and distortion during recording, and provide a magnetic erase head.

Structure of the Invention The present invention provides at least one magnetic material having magnetic anisotropy and one or more isotropic magnetic material having no magnetic anisotropy in the thickness direction of a magnetic tape, and a magnetic material between each magnetic material. It is a magnetic erasing head whose core part is composed of a non-magnetic material interposed between the
A magnet with magnetic anisotropy in the thickness direction of the magnetic tape, (
Due to the forward direction of the moon, the magnetic tape is sufficiently magnetically saturated to obtain an erasing magnetic field that can achieve complete erasing, and the magnetization strength is changed by the isotropic magnet 1 with no magnetic anisotropy. It is configured to gradually attenuate while reversing, and realizes a pseudo AC erasing magnetic field with less noise (erasing noise) during playback and less distortion during recording. According to the present invention, stable magnetization strength can be obtained using a simple magnetization method, and multipolarization can be easily achieved in a narrow space.

DESCRIPTION OF THE EMBODIMENTS The structure and operation of the embodiment of the present invention are shown in FIGS. 6 to 1.
This will be explained according to Figure 2.

2o is a magnetic erase head which is an embodiment of the present invention; 21 is its core; 22 is a magnet material Fl having magnetic anisotropy in the thickness direction of the magnetic tape; 1 perpendicularly magnetized magnetic pole.

23 to 27 are isotropic magnets without magnetic anisotropy (:)
The first magnetic tape is magnetized in the running direction of the magnetic tape.
This is the sixth horizontally magnetized magnetic pole. 28 is a spacer made of a non-magnetic material, 29I"i" is a partially magnetized yoke, 30 is a lower magnetized yoke, and 31 is a magnetized winding.

In FIG. 10, a indicates the magnetization strength of the first vertically magnetized magnetic pole 220, and -b indicates the N of the first horizontally magnetized magnetic pole 23, respectively.
The magnetization strengths of the poles and S poles, 10C and -c, "-d and -d, -4-e and -e1" -f and -f are the N of the 2nd to 5th horizontally magnetized magnetic poles 24 to 27, respectively. This is the magnetization strength of the pole and the south pole.

Core 21 of magnetic erase head 20 which is an embodiment of the present invention
As shown in FIGS. 6, 7, and 9, a first perpendicular adhesive made of a magnetic glue having magnetic anisotropy in the thickness direction of the magnetic tape is placed on the upstream side with respect to the running direction of the magnetic tape. A magnetic pole 22 and first to sixth horizontally magnetized magnetic poles 23 to 2 made of isotropic magnetic paste having no magnetic anisotropy are arranged on the downstream side, and a non-magnetic magnetic pole is disposed between each of the magnetized magnetic poles. Spacer 2 made of magnetic material
8. As shown in FIG. A magnet erase head 20 is placed so that the front surface of the head faces in the axial direction of the magnetizing yoke.
The first vertically magnetized magnetic pole 22 of the core 21 is magnetized, and then, as shown in FIG. The first to sixth horizontal magnetized magnetic poles are formed in the core 21 by arranging them so as to face each other and passing a magnetizing current I through the magnetized winding 31, thereby forming the magnetized magnetic poles as shown in FIGS. 9 and 10. get. In this case, during the second magnetization, a magnetizing magnetic field is also applied to the first vertically magnetized magnetic pole, but since the direction of the magnetic field and the direction of magnetic anisotropy of the magnet material H differ by 900, −・ It is not affected at all.

As shown in Figure 7 and Figure 8, the number of horizontally magnetized magnetic poles or the thickness of the spacer 28' is adjusted so that the one on the downstream side is not thicker than the one on the upstream side in the running direction of the magnetic tape. (
tl) t2>t3≧t4≧ts) By configuring
By decreasing the distance between adjacent magnetic poles downstream in the tape running direction to increase the mutual demagnetization between the magnetic poles, the polarity of the horizontally magnetized magnetic poles is reversed as shown in Figure 10. However, it is configured so that it gradually decreases.

The present invention is not limited by the thickness of the magnetizing yoke or magnetizing winding of the magnetizing device, unlike conventional magnetic erase heads.
The number of horizontally magnetized magnetic poles is determined by the number of stacked magnets, so by reducing the thickness of the magnet glue and spacer and increasing the number of stacked layers, it is possible to easily increase the number of poles even in a narrow space, while also keeping the magnetization conditions constant. Then, since the magnetization strength is determined by the thickness of the magnetic paste and the non-magnetic four-layer material, any desired magnetization strength can be stably obtained. By providing a vertically magnetized magnetic pole on the upstream side of the shunt, magnetic tape with high coercive force such as metal tape 1 o −
! A strong magnetization strength that can sufficiently magnetically saturate even a magnetic tape can be obtained, and a sufficient erasing effect, which is the basic performance of an erasing head, can be achieved.

Regarding magnetization, it is possible to magnetize a large number of magnets at once, as shown in FIG. 11(a), and the magnetizing device can be easily constructed.

FIG. 12 shows the magnetization process when the magnetic tape 1 is erased using the magnetic erase head 2o as shown in FIG. 6. 12th
As shown in the figure, even a magnetic tape with a large coercive force such as a metal tape can be magnetized (erased) to saturation with vertically magnetized magnetic poles, and by increasing the number of horizontally magnetized magnetic poles,
Even if the magnetization strength changes somewhat (broken line), the residual magnetic flux density can be stably converged to zero.

Figures 13 and 14 show the results of comparing an embodiment of the present invention with a conventional cassette tape recorder, where curve P is the embodiment, curve Q is the conventional example, and curve a
This is a system value that is independent of the fd erase head. That is, according to the present invention, the cancellation noise can be reduced by 6 to 1 odb, and the distortion rate during recording can be reduced by 3 to 6%.

Effects of the Invention The present invention provides at least one magnetic material having magnetic anisotropy and one or more isotropic magnetic material having no magnetic anisotropy in the thickness direction of the magnetic tape, and between each magnet HFI. A non-magnetic material is interposed between the core portion and a magnetizing magnetic field is applied in the thickness direction of the magnetic tape to magnetize the magnetic material having magnetic anisotropy in the thickness direction of the magnetic tape. At the same time, a magnetizing magnetic field is applied in the running direction of the magnetic tape to magnetize isotropic magnet material that has a high degree of magnetic anisotropy. This is to realize a magnetic erase head that can obtain the following characteristics.

Furthermore, an isotropic magnet material without magnetic anisotropy is placed downstream with respect to the running direction of the magnetic tape, and a magnet material with magnetic anisotropy is placed in the thickness direction of the magnetic tape with respect to the running direction of the magnetic tape. By installing one or more devices on the upstream side, a strong magnetic field for erasing the magnetic tape as it runs is applied, and then an alternating magnetic field for zero erasing is applied.
(This is to realize a magnetic erase head configured as shown in FIG.

A plurality of isotropic magnets having no magnetic anisotropy are placed on the downstream side with respect to the running direction of the twisted magnetic tape. Arrange the tape so that the thickness of the tape is not greater on the downstream side than on the upstream side in the running direction of the magnetic tape.
An alternating box in which the distance between magnetized magnetic poles is not larger on the downstream side than on the upstream side with respect to the running direction of the magnetic tape, and the mutual demagnetization between the magnetic poles is used to gradually attenuate in the running direction of the magnetic tape. The present invention provides a magnetic erasing head that can stably obtain a magnetic field, thereby realizing zero erasing with less noise and distortion.

[Brief explanation of the drawing]

Figure 1 is a perspective view showing the magnetic tape running state of a conventional magnetic erase head, Figure 2 is a perspective view showing the magnetized state of the conventional magnetic erase head, and Figure 3 is the magnetization strength of the conventional magnetic erase head. Figure 4 is a perspective view of the magnetizing device of a conventional magnetic erase head, page 513 is a characteristic diagram showing the magnetization process when erasing a magnetic tape with a conventional magnetic erase head, Figure 6 7 is a perspective view showing the running state of the magnetic tape of a magnetic erase head according to an embodiment of the present invention, FIG. 7 is a perspective view showing the magnetized state of this embodiment, and FIG. 8 is a perspective view of another embodiment. , FIG. 9 is a top view showing in detail the magnetized state of the core of this example, FIG. 10 is a characteristic diagram showing the magnetization strength of this example, and FIG. FIG. 12 is a characteristic diagram showing the magnetization process when a magnetic tape is erased as shown in FIG. 6 using this embodiment, and FIG. 13 is a front view showing the magnetizing device of the conventional magnetic erasing head and this embodiment. Fig. 14 is a characteristic diagram comparing the erasing noise of the magnetic erasing head of the example, and a characteristic diagram comparing the distortion rate during recording of the conventional example and the present example. 22...Thickness direction of the magnetic tape Magnet material having magnetic anisotropy, 23-27... Isotropic magnet material having no magnetic anisotropy, 28... Non-magnetic material. Name of agent: Patent attorney Toshio Nakao and 1 other person 28 No. 5 @ Us Fig. 6 Fig. 1 Kyou;

Claims (4)

[Claims] (1) At least one magnetic material with magnetic anisotropy and one or more isotropic magnetic material without magnetic anisotropy are provided in the thickness direction of the magnetic tape, and a non-magnetic material is provided between each magnetic material. What is claimed is: 1. A magnetic erasing head characterized in that a core portion is constructed by interposing (2) Place an isotropic magnet material without magnetic anisotropy on the downstream side in the running direction of the magnetic tape, and place a magnet material with magnetic anisotropy in the thickness direction of the magnetic tape in the running direction of the magnetic tape. 2. The magnetic erasing head according to claim 1, wherein at least one magnetic erasing head is disposed on the upstream side of the magnetic erasing head. (3) A plurality of isotropic magnet materials that do not have magnetic anisotropy are placed downstream with respect to the running direction of the magnetic tape, and the thickness of the magnet materials that are close to each other is The magnetic erase head according to claim 1 or 2, characterized in that the magnetic erase head (21:'a) is arranged such that the downstream side is not louder than the upstream side. (4) Non-magnetic materials interposed between a plurality of isotropic magnet materials having no magnetic anisotropy placed downstream at l~ with respect to the running direction of the magnetic tape, and non-magnetic materials placed close to each other. 3. The magnetic erase head according to claim 1, wherein the magnetic erase head is arranged such that the thickness of the magnetic erase head on the downstream side is not larger than that on the upstream side with respect to the running direction of the magnetic tape.