JPS6322361B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application 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.

Structure of the conventional example and its problems The conventional example 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 magnetic erase heads 5.
11 is a magnetizing device for magnetizing the conventional magnet erase head 5; 12 is a magnetizing magnetic pole magnetized to the core 6;
15 are the magnetizing windings thereof, and 16 to 19 are the magnetizing yokes.

The conventional magnet erasing head 5 has a core 6 in which magnetized magnetic poles adjacent to each other in the running direction (arrow) of the magnetic tape are different, as shown in FIG. 2, and magnetized as shown in FIG. The strength of the magnetic poles 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 magnetized magnetic poles 7, 8, 9, and 10, respectively.

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 magnetized by the core 6 of the magnetic erase head 5. The process will be explained according to FIG. The magnetic tape 1 is magnetized to saturation by the magnetized magnetic pole 7 (magnetization strength a) of the core 6, and then attenuated by reversing the magnetization so that the residual magnetization becomes zero at the magnetized magnetic poles 8 to 10. To go. However, in this case, due to variations in the magnetic properties of the material of the core 6, changes in the magnetization strength of the magnetized magnetic pole due to changes in the magnetization conditions, changes in the contact between the core 6 and the magnetic tape 1, etc., as shown in FIG. When the magnetization of the magnetic tape 1 by the magnetized magnetic pole 9 changes from c to c', residual magnetization e occurs in the magnetic tape 1 after erasing, which causes noise during playback and distortion during recording.

To eliminate this drawback, it may be possible to increase the number of magnetized magnetic poles so that residual magnetization is less likely to occur even if the magnetization changes as described above, but the conventional magnet erase head 5 generally has the structure shown in FIG. Since the magnetizing device 11 as shown in FIG.
The width of the magnetic poles could not be narrowed too much, and the distance between the magnetized magnetic poles could not be narrowed too much due to the space of the magnetized winding and its insulation, making it impossible to obtain a sufficient number of magnetized magnetic poles.
In FIG. 4, the core 6 of the conventional magnet erasing head 5 is pressed against the magnetizing yoke of the magnetizing device 11, and the magnetizing yokes 16, 17, 18 and 19 and the magnetizing windings 12, 13 wound thereon are removed. , 14 and 15, the magnetized magnetic poles 7,
8, 9 and 10 are formed. The magnetization strength of the magnetization pole is controlled by the width of the magnetization yoke, the magnitude of the magnetization current, the number of turns of the magnetization winding, the wire diameter, and the position.

Purpose of the Invention In order to eliminate such drawbacks, the present invention aims to realize a magnet erasing head that eliminates noise and distortion during recording and playback by providing a large number of magnetized magnetic poles in a limited core width dimension. .

Structure of the Invention The present invention provides one or more magnet materials each having magnetic anisotropy in the thickness direction of a magnetic tape and one or more magnet materials having magnetic anisotropy in the running direction of the magnetic tape, and between each magnetic material. This is a magnetic erasing head in which the core portion is constructed with a non-magnetic material interposed therebetween, and the erasing magnetic field capable of magnetically saturating the magnetic tape sufficient for erasing is obtained by the magnetic material having magnetic anisotropy in the thickness direction of the tape, and The number of poles can be easily increased by laminating a number of magnetic materials with magnetic anisotropy in the tape running direction with non-magnetic materials interposed between them. This makes it possible to easily realize pseudo AC erasure in which the magnetic field strength is gradually attenuated while the polarity is reversed, and high-performance erasure characteristics with low erasure noise and low distortion during recording can be obtained.

DESCRIPTION OF EMBODIMENTS The structure and operation of the present invention will be explained with reference to FIGS. 6 to 12. 20 is a magnetic erasing head which is an embodiment of the present invention; 21 is its core; 22 is made of a magnetic material having magnetic anisotropy in the thickness direction of the magnetic tape; 1 perpendicularly magnetized magnetic pole. Reference numerals 23 to 27 are 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.

As shown in FIGS. 6, 7, and 9, the core 21 of the magnetic erase head 20, which is an embodiment of the present invention, is arranged in the upstream direction in the thickness direction of the magnetic tape with respect to the running direction of the magnetic tape. A first vertically magnetized magnetic pole 22 made of a magnetic material having magnetic anisotropy, 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 on the downstream side. A spacer 28 made of a non-magnetic material is interposed between each magnetized magnetic pole.

As shown in FIG. 11A, the core 21 of the magnet erasing head 20 is constructed between the upper magnetizing yoke 29 and the lower magnetizing yoke 30 by first passing a magnetizing current I through the magnetizing winding 31. The first vertically magnetized magnetic pole 22 of the core 21 of the magnet erase head 20, which is placed so that its front face is oriented in the axial direction, is magnetized;
As shown in FIG. The first to fifth horizontally magnetized magnetic poles are magnetized, and finally, the magnetized magnetic poles as shown in FIGS. 9 and 10 are obtained.

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 -d, +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.

As shown in FIGS. 7 and 8, horizontally magnetized magnetic poles 23, 24, 25, 26, 27 or spacers 2
By configuring the thickness of the magnetic tape 8' so that the downstream side is not thicker than the upstream side in the running direction of the magnetic tape (t ₁ ≧t ₂ ≧t ₃ ≧t ₄ ≧t ₅ ), By decreasing the distance between the magnetic poles downstream in the tape running direction and increasing the mutual demagnetization (cancellation) of the magnetic poles, the magnetization strength of the horizontally magnetized magnetic poles increases as shown in Figure 10. It is configured so that the polarity gradually decreases while being reversed. In the present invention, by reducing the thickness of the horizontally magnetized magnetic pole and the spacer, multipolarization can be easily realized, and by selecting the thickness, an arbitrary magnetized pattern can be stably obtained.

Further, by providing a vertically magnetized magnetic pole on the upstream side, a strong magnetizing strength, that is, an erasing magnetic field, can be obtained that can sufficiently magnetically saturate even a magnetic tape with a high coercive force such as a metal tape. Furthermore, in magnetization, as shown in FIG. 11A, it is possible to magnetize a large number of magnets at once, and the magnetizing device can be easily configured.

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, by increasing the number of horizontally magnetized magnetic poles, residual magnetization can be stably converged to zero even if the magnetization strength changes slightly, and vertically magnetized Even tapes with large coercive force, such as metal tapes, can be sufficiently magnetized to saturation using the magnetic poles.

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. In other words, in the present invention, the erasure noise is 5 to 10 dB, and the distortion rate during recording is 3 to 10 dB.
I was able to improve it by 5%.

Effects of the Invention The present invention provides one or more magnet materials each having magnetic anisotropy in the thickness direction of the magnetic tape and one or more magnet materials having magnetic anisotropy in the running direction of the magnetic tape, and one or more magnet materials having magnetic anisotropy in the running direction of the magnetic tape, and one or more magnet materials having magnetic anisotropy in the running direction of the magnetic tape. This is a magnetic erasing head with a core made up of a non-magnetic material.By magnetizing the tape in the thickness direction, the magnetic material with magnetic anisotropy in the tape thickness direction is placed on the front surface of the head (tape contact surface). It is possible to magnetize the entire part of the tape that is exposed to the magnetic field, thereby obtaining an erasing magnetic field that can magnetically saturate the magnetic tape sufficiently for erasing, and by magnetizing in the running direction of the tape, magnetic anisotropy is created in the running direction of the tape. A magnetized magnetic pole can be obtained at the end of the part where the magnetic material with magnetic properties is exposed at the front of the head, and by thinning this magnetic material and laminating a number of layers with non-magnetic material interposed between them, polarization can be easily obtained. In addition, by decreasing the thickness of the magnetic material and non-magnetic material toward the downstream side in the tape running direction, the magnetic field strength gradually decreases while the polarity is reversed. Pseudo-AC erasing can be realized, and erasing can be completely performed using a magnetic material that has magnetic anisotropy in the thickness direction of the magnetic tape provided on the upstream side of the tape running direction, and also The pseudo-AC erasing section is constructed by laminating magnetic materials having magnetic anisotropy in the traveling direction with non-magnetic materials interposed therebetween, and provides high-performance erasing characteristics with less erasing noise and less distortion during recording.

[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 the distortion rate during recording between a conventional magnetic erasing head and this embodiment. 22... Magnet material having magnetic anisotropy in the thickness direction of the magnetic tape, 23-27... Magnet material having magnetic anisotropy in the running direction of the magnetic tape, 28...
Non-magnetic material.

Claims (1)

[Scope of Claims] 1. One or more magnet materials each having magnetic anisotropy in the thickness direction of the magnetic tape and one or more magnet materials having magnetic anisotropy in the running direction of the magnetic tape, and A magnet erasing head characterized in that a core portion is constructed with a non-magnetic material interposed therebetween. 2. A magnet material having magnetic anisotropy in the running direction of the magnetic tape is placed downstream with respect to the running direction of the magnetic tape, and a magnet material having magnetic anisotropy in the thickness direction of the magnetic tape with respect to the running direction of the magnetic tape. 2. The magnet erasing head according to claim 1, wherein one or more magnet erasing heads are disposed on the upstream side of the magnet erasing head. 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 that are close to each other is on the downstream side 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 such that the magnetic erase head on the side is not larger than the magnetic erase head 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 magnetic tape on the downstream side is not larger than the magnetic erase head on the upstream side with respect to the running direction of the magnetic tape.