JPH024053B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording/reproducing apparatus such as a video tape recorder suitable for recording short wavelength signals such as video signals.

Conventional Structure and Problems Conventionally, longitudinal magnetization (in-plane magnetization) has been common in magnetic recording/reproducing devices such as video tape recorders. It is known that recording demagnetization and self-demagnetization occur in longitudinal magnetization during short wavelength recording. For this reason, in video tape recorders and the like, these demagnetizations increase from a recording wavelength of about 1 μm, making it practically difficult to reproduce signals recorded at shorter wavelengths.

On the other hand, perpendicular magnetization systems aimed at recording at even shorter wavelengths have been studied, and many proposals for practical use have been made. However, most of the perpendicular magnetization systems currently proposed use a main magnetic pole and an auxiliary magnetic pole, so it is difficult to apply them to video tape recorders and the like that use a rotating head system.

In addition, perpendicular magnetization is performed by using a ring-shaped head and a tape with a perpendicular magnetization film, and by making the same direction as the longitudinal magnetization, that is, the head gap length direction and the direction of movement of the recording medium. A method has also been proposed. With this method, you only need to attach the head to one side of the recording medium, so
Applications to video tape recorders using a rotating head system are possible. However, this method has a problem in that it is difficult to obtain a sharp perpendicular magnetic field, so that recording and reproducing characteristics are worse than the method using the above-mentioned main magnetic pole and auxiliary magnetic pole.
Furthermore, a phenomenon occurs in which the level of the reproduced signal drops extremely at the recording wavelength corresponding to the head gap length of the reproduction head (so-called valley in frequency characteristics due to reproduction gap loss), There is a problem in that it is practically difficult to reproduce the wavelength recorded signal.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a magnetic recording/reproducing device which solves the above-mentioned conventional problems and makes it possible to reproduce significantly short wavelength recording signals.

Structure of the Invention In order to achieve the above object, the present invention includes a magnetic recording medium having a perpendicularly magnetized film and a ring-shaped magnetic head that moves at a required relative speed with respect to the magnetic recording medium, and The gap width direction of the head and the direction of relative movement are the same direction, and the ring-shaped magnetic head is
This is configured so that the core widths of the opposing cores that make up the head gap section are different in length. This eliminates the limitation on the reproduced signal frequency due to the gap width, making it possible to reproduce significantly shorter wavelength recording signals. can.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below based on the drawings. FIG. 1 shows a schematic diagram of the main parts of the tape head system of the present invention. 1 is a ring-shaped magnetic head, 2
3 is a magnetic tape, and 3 is a magnetic head support. G
Reference numeral 1 designates a gap portion of the magnetic head 1. As shown in FIG. A coil 4 is wound around the magnetic head 1. An arrow 5 indicates the moving direction of the magnetic head 1, which is the same direction as the gap width direction of the gap portion G1. Note that there is no problem even if the magnetic tape 2 runs in a direction relatively opposite to the arrow 5. Note that the gap length of the gap portion G1 is indicated by g.

FIG. 2 is an enlarged sectional view of the vicinity of the gap portion of the magnetic head 1 shown in FIG. 1 (the top and bottom are reversed from those shown in FIG. 1) and its coordinate axes x and y.

FIG. 3 is a characteristic diagram showing an example of the distribution of the magnetic field Hy (magnetic field in the y-axis direction) near the gap of the magnetic head 1 using the coordinate axes in FIG. Here, Ho is the magnetic field at the air gap center position (x=o, y=o).

In the magnetic field distribution of a so-called ring-shaped magnetic head as shown in Figure 3, it is known that the magnetic field in the y-axis direction exhibits a very large level in the region of y/g≒0.2 or less. There is. In order to record this magnetic field, a magnetic recording medium having a perpendicular magnetization film is used as the magnetic tape 2. As illustrated in FIG. 4, this magnetic recording medium having a perpendicularly magnetized film is composed of a perpendicularly magnetized film 6 and a horizontally magnetized film 7.
The layer structure itself is well known. These films are produced on the base 8.

The magnetic head 1 is scanned over such a magnetic tape 2 on the perpendicularly magnetized film 6 side as shown in FIG. 1, and a recording current is caused to flow through the coil 4. If the waveform of the recording current is, for example, a digital waveform as shown in FIG. 5, the recording magnetization pattern will be as shown in FIG. In FIG. 6, downward arrow 9 and upward arrow 1
0 indicates a magnetization vector recorded in the perpendicular magnetization film 6 at the rear end in the head traveling direction of the gap G1 of the magnetic head 1, and 11 and 12 indicate magnetic tracks. Where the surface of the magnetic track is satin-like, the magnetization vector 9 is directed downward, and where the surface is plain, the magnetization vector 10 is directed upward. In addition,
As shown in FIG. 3, the y-axis magnetic field is approximately symmetrical about x/g=0.5 when y/g≦0.2. For this reason, as shown in FIG.
The center spacing of 12 is approximately g. Further, a magnetization vector as shown by 13 is recorded in the horizontal magnetization film 7. The direction of this magnetization vector 13 is reversed as the vector in the perpendicularly magnetized film 6 is reversed. By forming horseshoe-shaped magnetization vectors such as those shown by magnetization vectors 9, 13, and 10, a recording magnetic field with a very large magnetization moment can be obtained with little demagnetization effect. In addition, magnetic head 1
By setting the moving direction of the gap portion G1 in the same direction as the gap width direction, magnetic tracks 11 and 12 as shown in FIG. 6 can be obtained with almost no recording demagnetization.

For example, if the gap length g of magnetic head 1 is 5μ
m and the thickness of the perpendicular magnetization film 6 is 0.5 μm,
At the boundary between the vertically magnetized film 6 and the horizontally magnetized film 7, y/g=0.1, and a magnetic field shown by the curve y/g=0.1 in FIG. 3 is applied. If the coercive force of the vertically magnetized film 6 and the horizontally magnetized film 7 is approximately 0.5 (normalized by Hy/Ho), a magnetic track as shown in FIG. 6 is obtained.

FIG. 7 shows the gap G1 of the magnetic head 1.
FIG. 2 is an enlarged perspective view of the magnetic tape 2 viewed from the lower front side. In Figure 7, the head gap G
1 has an opposing core end 14 and core end 1
5, and the straight line 16 connects the core end 14 and the core end 1.
It is a straight line connecting 5. Similarly, the rear end portion is composed of core ends 17 and 18 facing each other, and has a straight line 1.
9 is a straight line connecting the core end 17 and the core end 18. The straight line 16 and the extension line 20 of the arrow 5 intersect at an angle that is not a right angle, and the straight line 19 and the extension line 20
intersects at a right angle. This means that the length of the core width L ₁ between the opposing cores, that is, the core end 14 and the core end 17, and the core width length L ₂ between the core end 15 and the core end 18 are different. caused by When such a magnetic head 1 is used to reproduce recorded tracks 11 and 12 as illustrated in FIG. 6, the reproduction frequency characteristics are flat and short as shown in FIG. It can be seen that even wavelength signals (ie, high frequency signals) can be reproduced.

Here, as illustrated in FIG. 9 (an enlarged perspective view seen from the same direction as FIG. 7), during playback, the length L ₃ of the core width between the core end 22 and the core end 24,
Core width length between core end 23 and core end 25
L ₄ is equal, that is, the gap width is L (L = L ₃
= L ₄ ), the first
A frequency characteristic as illustrated in Fig. 0 is obtained. Point A in FIG. 10 is the valley of the frequency characteristics, and this is the playback gear loss that occurs when the wavelength of the signal recorded on the magnetic tape 2 and the gap width L become equal, and the gap width L is equal to the wavelength of the signal recorded on the magnetic tape 2. Since the signal (high frequency signal) has a plurality of reproduction gap losses as shown in the figure, it could not be used for actual use (recording and reproduction).

However, as shown in FIG. 7, when the recording tracks 11 and 12 shown in FIG. 6 are reproduced using a magnetic head 1 having a head gap G1 in which _L1 and _L2 have different lengths, As mentioned above, the reproduction frequency characteristics shown in Fig. 8 have no so-called valleys, and this removes the limitation on the reproduction wavelength due to the gap width, making it possible to reproduce significantly short wavelength recorded signals. It becomes possible to do so.
The wavelength of this recording signal is sufficiently shorter than the normally used longitudinal magnetization.

Here, the reason why no valley occurs in the reproduction frequency characteristic is considered to be that the angle of the front end of the gap formed by the core ends 14 and 15 is different from the angle of the domain wall of the recorded signal. Note that this also applies to a magnetic head (not shown) configured such that the angle at the front end of the gap is the same as the angle of the domain wall of the recorded signal, and the angle at the rear end of the gap is different from the angle of the domain wall of the recorded signal. You can get the following effect. These magnetic heads are obtained by making the core widths of opposing cores forming the head gap portion of the reproducing magnetic head 1 different in length.

Furthermore, almost the same effect can be obtained with a magnetic recording medium of the type that does not have the horizontal magnetization film 7 and performs recording and reproduction only with the perpendicular magnetization film 6. Furthermore, substantially similar results can be obtained with magnetic recording media of a type that includes the perpendicularly magnetized film 6 and the horizontally magnetized film 7 and has other magnetized films.

Effects of the Invention As is clear from the above description, according to the present invention, the limitation on the reproduced signal frequency due to the gap width can be removed, and reproduction of significantly short wavelength recorded signals can be realized. Also, to reproduce the horseshoe magnetization vector,
Its magnetization moment is large, and it is possible to reproduce a signal with a very high reproduction signal level, even though the recording signal has a significantly short wavelength. In addition, since the magnetic head can be installed only on one side of the recording medium,
This has the advantage of being easy to apply to video tape recorders using a rotating head system.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view of a main part showing an example of the configuration of a tape head system according to the present invention, FIG. 2 is an enlarged sectional view of the vicinity of the gap of the magnetic head in FIG.
The figure is a characteristic diagram showing an example of magnetic field distribution, Figure 4 is an enlarged perspective view showing an example of the configuration of a magnetic recording medium used in the present invention, Figure 5 is a waveform diagram showing an example of the recording current waveform, and Figure 6 is a waveform diagram showing an example of the recording current waveform. FIG. 7 is an enlarged perspective view showing an example of a magnetic track in a magnetic recording medium recorded according to the present invention, FIG. 7 is an enlarged schematic perspective view of the magnetic head of FIG. 1, and FIG. 8 is a schematic frequency characteristic diagram of a reproduced signal according to the present invention. , FIG. 9 is an enlarged schematic perspective view of a magnetic head illustrated for comparison with the magnetic head of FIG. 7,
FIG. 10 is a schematic frequency characteristic diagram of a reproduced signal obtained by using the magnetic head illustrated in FIG. 9. DESCRIPTION OF SYMBOLS 1... Magnetic head, 2... Magnetic tape, 4... Coil, 5... Relative movement direction, 6... Vertical magnetization film, 7... Horizontal magnetization film, 9, 10, 13... Magnetization vector, 1
1, 12...magnetic track, 14, 15, 17, 1
8... Core end, G1... Head gap part, L ₁ ,
L ₂ ...Length of core width, g...Gap length.

Claims (1)

[Scope of Claims] 1. A magnetic recording medium having a perpendicular magnetization film and a ring-shaped magnetic head that moves at a required relative speed with respect to the magnetic recording medium, and wherein the gap width direction of the magnetic head and the relative The magnetic head is moved in the same direction as the magnetic head, and the ring-shaped magnetic head is a magnetic head in which the core widths of opposite cores constituting a head gap portion are different in length. Recording/playback or playback device. 2. Construct the straight line connecting the opposing core ends of the front end of the head gap portion of the magnetic head to be at an angle different from a right angle to the direction of relative displacement between the magnetic recording medium and the magnetic head, and Magnetic recording according to claim 1, characterized in that a straight line connecting the opposing core ends of the rear end of the head gap portion of the head is configured to be perpendicular to the direction of relative movement. playback or playback device. 3. A straight line connecting the opposing core ends of the front end of the head gap of the magnetic head is configured to be perpendicular to the direction of relative movement between the magnetic recording medium and the magnetic head, and the head gap of the magnetic head is The magnetic recording and reproducing device according to claim 1, wherein a straight line connecting the opposing core ends of the rear end of the section is configured to form an angle different from a right angle with respect to the relative movement direction. Or a playback device. 4. The magnetic recording medium according to any one of claims 1 to 3, wherein a magnetic recording medium having a two-layer structure consisting of a perpendicularly magnetized film and a horizontally magnetized film is used. Recording/playback or playback device.