JPS6322362B2 - - Google Patents

Description

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

Conventional configuration and its problems Small size of magnetic recording and reproducing device using magnetic tape
As the erasure head for erasing magnetic tape is becoming more energy efficient, the use of magnetic erase heads that do not require an erasing current has changed from the relatively large AC erasing head that consumes a large erasing current (power). In recent years, there has been a desire for smaller size and higher performance.

A conventional example of this magnet erasing 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, 7-1
0 is a magnetized magnetic pole magnetized to the core 6 of the magnet erasing head 5, 11 is a magnetizing device for magnetizing the conventional magnet erasing head 5, 12 to 15 are magnetizing windings thereof, 1
6 to 19 are magnetizing yokes. The conventional magnet erasing head 5 has a core 6 in which the polarities of adjacent magnetized magnetic poles are different 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 magnetic poles 7, 8, 9, and 10, respectively, and are the magnetization strengths of the magnetization magnetic poles 7, 8, 9, and 10 of the core 6 of the conventional magnet erase head 5. 10 is pressed against the magnetizing yokes 16, 17, 18 and 19 of the magnetizing device 11 shown in FIG. It is magnetized by flowing it. The magnetization strength is determined by the width of the magnetization yoke, the magnitude of the magnetization current, the number of turns of the magnetization winding,
Can be controlled by wire diameter and position.

Now, as shown in FIG. 1, when the front surface of a conventional magnetic erase head 5 is run in the direction of the arrow in order to erase the magnetic tape 1, the magnetic tape 1 is demagnetized by the core 6 of the magnetic erase head 5. The process of magnetization will be explained with reference to FIG. magnetic tape 1
is the magnetized magnetic pole 7 magnetized with the magnetization strength a of the core 6
After being magnetized to saturation at , reverse magnetization is applied to the magnetized magnetic poles 8 to 10, which gradually attenuates so that the residual magnetic flux density becomes zero. However, in this case, the fifth
As shown in the figure, 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 is generated in the magnetic tape 1 after erasure, resulting in noise during playback (erasure noise) and distortion during recording. cause the rate.

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. Further, the distance between the magnetized magnetic poles cannot be narrowed due to the space of the magnetized winding and its insulation, making it impossible to obtain a sufficient number of magnetized magnetic poles. 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, making it difficult to obtain a stable magnetization strength.

Purpose of the invention The present invention solves the above-mentioned conventional problems.
In order to achieve miniaturization and high performance as a magnet erase head for small cassette tape recorders and micro cassette recorders, we have achieved a large number of magnetized magnetic poles with stable magnetization strength within a limited core width dimension, reducing noise during playback. The object of the present invention is to provide a magnet erasing head that reduces distortion during recording and recording.

Structure of the Invention The present invention provides one or more magnetic materials having magnetic anisotropy and one or more isotropic magnetic materials having no magnetic anisotropy in the running direction of a magnetic tape, and also provides non-contact between each magnetic material. This is a magnetic erase head with a core made up of a magnetic material, and the front surface is made of an isotropic magnet material with no magnetic anisotropy, which saturates the magnetic tape sufficiently to achieve complete erasure. In addition to obtaining a magnetic field, it is constructed so that the magnetization strength is gradually attenuated while the polarity is reversed using a magnet material that has magnetic anisotropy in the running direction of the magnetic tape, reducing noise during playback (erasure noise) and This realizes a pseudo AC erasing magnetic field with low distortion during recording. The present invention also allows stable magnetization strength to be obtained using a simple magnetization method, and multipolarization can be easily realized in a narrow space.

Explanation of the embodiments The structure and operation of the embodiments of the present invention are explained in the sixth section.
This will be explained with reference to FIGS.

20 is a magnetic erase head which is an embodiment of the present invention, 21 is its core, and 22 is a first perpendicular head made of an isotropic magnet material having no magnetic anisotropy and magnetized in the thickness direction of the magnetic tape. It is a magnetized magnetic pole. 23~
Reference numeral 27 denotes first to fifth horizontally magnetized magnetic poles made of a magnetic material having magnetic anisotropy in the running direction of the magnetic tape and magnetized in the running direction of the magnetic tape. 28 is a spacer made of a non-magnetic material, 29 is an upper magnetizing yoke, 30 is a lower magnetizing yoke, and 31 is a magnetizing winding.

In FIG. 10, a is the magnetization strength of the first vertically magnetized magnetic pole 22, +b and -b are the magnetization strengths of the N and S poles of the first horizontally magnetized magnetic pole 23, +c and -c, +d and -, respectively. d, +e and -e, +f
and -f are the second to fifth horizontally magnetized magnetic poles 2, respectively.
The magnetization strength of N pole and S pole is 4 to 27.

The core 21 of the magnetic erase head 20, which is an embodiment of the present invention, does not have magnetic anisotropy on the upstream side with respect to the running direction of the magnetic tape, as shown in FIGS. 6, 7, and 9. A first vertically magnetized magnetic pole 22 made of an isotropic magnetic material, and first to fifth horizontally magnetized magnetic poles 23 to 27 made of a magnetic material having magnetic anisotropy in the running direction of the magnetic tape are arranged on the downstream side. A spacer 2 made of a non-magnetic material is placed between each magnetized magnetic pole.
8. As shown in FIG. 11A, the core 21 of the magnet erasing head 20 is first arranged so that the front surface of the head faces 90 degrees with respect to the axial direction of the magnetizing yoke of the magnet erasing head 20, and the magnetizing winding is 31 to form the first to fifth horizontal magnetized magnetic poles in the core 21, and then as shown in FIG. A magnet erase head 2 is placed between an upper magnetizing yoke 29 and a lower magnetizing yoke 30 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 of No. 0 is magnetized to obtain a magnetized magnetic pole as shown in FIGS. 9 and 10. In this case, during the second magnetization, the magnetizing field is also applied to the first to fifth horizontal magnetized magnetic poles, but since the direction of the magnetic field and the direction of the magnetic anisotropy of the magnet material are 90 degrees different, they are hardly affected. do not have.

As shown in FIGS. 7 and 8, the thickness of the horizontally magnetized magnetic pole or spacer 28' is adjusted so that the thickness of the horizontally magnetized magnetic pole or spacer 28' is not thicker on the downstream side than on the upstream side in the running direction of the magnetic tape (t ₁ ≧t ₂ ≧t ₃ ≧t ₄ ≧t ₅ ) By configuring the tape, the distance between adjacent magnetic poles becomes smaller as it goes downstream in the tape running direction, increasing the mutual demagnetization between the magnetic poles, and achieving horizontal magnetization. The magnetization strength of the magnetic poles is configured to gradually decrease while the polarity is reversed as shown in FIG.

Unlike conventional magnet erasing heads, the present invention is not limited by the thickness of the magnetizing yoke or magnetizing winding of the magnetizing device, but the number of horizontal magnetizing poles is determined by the number of layers of magnet material. Therefore, by reducing the thickness of the magnet material and spacer and increasing the number of laminated sheets, multi-polarization can be easily achieved even in a narrow space.If the magnetization conditions are constant, the magnetization strength is determined by the thickness of the magnet material and non-magnetic material. Therefore, any desired magnetization strength can be stably obtained. In addition, by providing a vertically magnetized magnetic pole on the upstream side, a strong magnetization strength that can sufficiently saturate even magnetic tapes with high coercive force such as metal tapes can be obtained. effect can be achieved.

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

FIG. 12 shows the magnetization process when the magnetic tape 1 is erased by the magnetic erase head 20 as shown in FIG. 6. As shown in Figure 12, vertically magnetized magnetic poles can sufficiently magnetize (erase) even magnetic tapes with high coercive force, such as metal tapes, to saturation, and by increasing the number of horizontally magnetized magnetic poles, the magnetization strength can be increased to some extent. Even if there is a change (broken line), the residual magnetic flux density can be stably converged to zero.

FIGS. 13 and 14 show the results of comparing one embodiment of the present invention with a conventional one in a cassette tape recorder. Curve P is the result of this embodiment, curve Q
is the conventional example, and the curve S is the value of the system itself, unrelated to the erase head. That is, according to the present invention, the erasure noise can be reduced by 5 to 10 dB, and the distortion rate during recording can be reduced by 3 to 5%.

Effects of the Invention The present invention provides one or more isotropic magnet materials having no magnetic anisotropy and one or more magnet materials having magnetic anisotropy in the running direction of the magnetic tape, and provides space between each magnet material. A magnetic field is first applied in the running direction of the magnetic tape to magnetize the magnet material having magnetic anisotropy in the running direction of the magnetic tape, and a non-magnetic material is interposed therebetween to form the core part. In addition to obtaining a multipolar alternating magnetic field even in a space, a magnetizing magnetic field is added in the thickness direction of the magnetic tape to generate a strong magnetic field for magnetizing and erasing the magnetic material having magnetic anisotropy in the thickness direction of the magnetic tape. This is to realize a magnet erasing head that can obtain the following characteristics.

Furthermore, a magnet material that has magnetic anisotropy in the running direction of the magnetic tape is placed downstream with respect to the running direction of the magnetic tape, and an isotropic magnet material that does not have magnetic anisotropy is placed downstream with respect to the running direction of the magnetic tape. on the upstream side,
By arranging one or more of each type, a magnetic erasing head is realized in which a strong magnetic field for erasing is applied as the magnetic tape runs, and then an alternating magnetic field for zero erasing is obtained. It is.

In addition, the thickness of magnetic materials that have magnetic anisotropy in the running direction of a plurality of magnetic tapes arranged downstream with respect to the running direction of the magnetic tapes, or the non-magnetic materials interposed between them, that are close to each other. The distance between the magnetized magnetic poles on the downstream side in the running direction of the magnetic tape is larger than that on the upstream side with respect to the running direction of the magnetic tape. The present invention provides a magnet erasing head that can stably obtain an alternating magnetic field that gradually attenuates in the running direction of the magnetic tape by utilizing mutual demagnetization between the magnetic poles without increasing the magnetic field. This is to realize erasure.

[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 a conventional magnetic erase head, and Figure 3 is the magnetization strength of a conventional magnetic erase head. FIG. 4 is a perspective view of a conventional magnetizing device for a magnet erase head, and FIG.
The figures are characteristic diagrams showing the magnetization process when a magnetic tape is erased using a conventional magnetic erase head, FIG. The figure is a perspective view showing the magnetized state of this embodiment, 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 embodiment, Fig. 10 is a characteristic diagram showing the magnetization strength of this embodiment, and Fig. 11 A and B are the magnetizing device of this embodiment. FIG. 12 is a characteristic diagram showing the magnetization process when a magnetic tape is erased as shown in FIG. 6 according to this embodiment, and FIG. FIG. 14 is a characteristic diagram comparing head erasure noise, and FIG. 14 is a characteristic diagram comparing distortion rates during recording between the conventional example and this embodiment. 22... Isotropic magnet material without magnetic anisotropy, 23-27... Magnet material having magnetic anisotropy in the running direction of the magnetic tape, 28... Non-magnetic material.

Claims (1)

[Claims] 1. One or more magnetic materials having magnetic anisotropy and one or more isotropic magnetic materials having no magnetic anisotropy in the running direction of the magnetic tape, and between each magnetic material. 1. A magnet erasing head characterized in that a core portion is constructed by interposing a non-magnetic material into the magnet. 2. Place an isotropic magnet material without magnetic anisotropy on the upstream side with respect to the running direction of the magnetic tape, and place a magnet material with magnetic anisotropy with respect to the running direction of the magnetic tape in the running direction of the magnetic tape. 2. The magnet erasing head according to claim 1, wherein at least one magnet erasing head is disposed on the downstream side. 3 A plurality of magnet materials having magnetic anisotropy in the running direction of the magnetic tapes arranged downstream with respect to the running direction of the magnetic tapes are arranged so that the thickness of the magnet materials adjacent to each other is arranged downstream with respect to the running direction of the magnetic tapes. 3. The magnet erasing head according to claim 1, wherein the magnetic erase head is arranged so that one side thereof is not larger than one on the upstream side. 4 A non-magnetic material interposed between magnet materials having magnetic anisotropy in the running direction of a plurality of magnetic tapes arranged downstream with respect to the running direction of the magnetic tape is 3. The magnetic erase head according to claim 1, wherein the magnetic erase head is arranged so that the one on the downstream side is not larger than the one on the upstream side with respect to the running direction of the magnetic tape.