JPS6332716A - Magnetic head in helical scanning system - Google Patents

Abstract

PURPOSE:To satisfactorily execute a cross recording by providing first - fourth magnetic heads on the periphery of a cylinder by making them have the phase difference of about 90 deg. from each other, deflecting second and fourth heads by 1/2 against the first and the third heads, and also, making the azimuth angle different in each adjacent head. CONSTITUTION:When the first and the second heads 1, 3 are provided as usual on each opposed periphery of a cylinder 5 having a rotary shaft 6, in addition to them, by having the phase difference of about 90 deg. between them, the second and the fourth heads 2, 4 are attached. Also, the head 2 and 4 are deflected by half of a track pitch Tp between first and second tracks with regard to the axial direction of the rotary shaft 6, and the first track formed by the head 1 and the second track formed by the head 3 are arranged adjacently. Also, as for the adjacent heads, its azimuth angles are made different, by which two kinds of information can be recorded in the same part of a recording medium, and also, the generation of a crosstalk at the time of reproduction is also obstructed.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a magnetic head using a helical scan method, and is a recording method for recording two types of information on the same overlapping track without causing crosstalk during reproduction. This method is useful for use in the cross-recording method (hereinafter referred to as cross-recording).

<Prior Art> In magnetic recording, various technical improvements have been proposed to improve the recording density of magnetic recording media.

One method was to increase the density by reducing the track width. As a result of reducing the track width, a situation occurs in which off-track occurs during playback even when tracking servo is applied. For this reason, it has been proposed to form guard bands between adjacent tracks in which no magnetic information exists. However, since this guard band is an idle part that does not contribute to the original function of the magnetic recording medium, which is to magnetically record information, it is necessary to achieve even higher density. A so-called guard pantress recording method has been proposed in which information is recorded by changing the relative azimuth angles of adjacent tracks in order to prevent crosstalk between adjacent tracks.

<Background of the Invention> Guard panless recording can be said to have achieved high recording density in the sense that the entire surface of the magnetic recording medium is used as the information recording surface. The information recorded in is single-layered.

It is clear that if multiple types of information can be recorded on the same portion of a magnetic recording medium without causing crosstalk during reproduction, that is, if multiple recording is possible, the recording density will be improved.

Therefore, the present inventors developed a so-called cross-recording method, a magnetic recording method that can record two types of information twice on the same part of a magnetic recording medium without causing crosstalk during playback. We have begun work on this and have set a prospect of putting it to practical use.

Here, the principle of the loss recording method will be explained below.

FIGS. 7(a) and 7(b) are explanatory diagrams schematically showing the orientation state of acicular particles, which are magnetic particles, together with a magnetic head. The magnetic head 1.2 shown in both figures is the magnetic head 1.2.
The magnetic recording medium 3 has an azimuth angle of approximately 45 degrees in the clockwise and counterclockwise directions with respect to a line perpendicular to the relative movement direction A of the magnetic recording medium 3. The magnetic recording medium 3 is formed by applying acicular magnetic particles (hereinafter referred to as magnetic particles).
The magnetic surface is preferably a collection of magnetic particles with completely random orientation. Among the magnetic particles, Fig. 7 (a
), the later explanation will be continued with 3b and 36 where the longitudinal direction and the magnetization direction B due to the gap of the magnetic head 1 are parallel and intersect at 38.45 degrees, respectively.

As shown in FIG. 7(a), when information is written on the magnetic recording medium 3 by the magnetic head 1, the magnetization state of the magnetic particles 3a easily changes, but the magnetization state of the magnetic particles 3c hardly changes.

Moreover, the magnetic particles 3b change slightly. That is, information by the magnetic head 1 is mainly recorded on the magnetic particles 3a.

On the other hand, as shown in FIG. 7(b), the magnetic recording medium 3
When information is written with the magnetic head 2, the magnetization state of the magnetic particles 3c parallel to the magnetization direction C due to the gap of the magnetic head 2 changes most easily. Further, the magnetic particles 3a hardly change, and the magnetic particles 3b change slightly to the same extent as in the previous case. That is, information by the magnetic head 2 is mainly recorded on the magnetic particles 3C.

Therefore, when the magnetic head 2 records second information on the first track on which the first information is recorded by the magnetic head 1 to form a second track, the magnetic recording medium 3 has a main track. The magnetic particles 33 recording the first information and the magnetic particles 3c mainly recording the second information coexist without significantly interfering with each other. That is, it is possible to record twice on the same track.

On the other hand, when the same track formed as described above is read and scanned by the magnetic head 1, the magnetic particles 3 parallel to the magnetization direction B are
The first information recorded on the magnetic particles 3c is mainly reproduced, and the second information recorded on the magnetic particles 3c perpendicular to the magnetization direction B is hardly reproduced because it involves a large azimuth loss.

Also, when the magnetic head 2 performs reproduction scanning in the same way, the magnetization direction C
The second information recorded on the magnetic particles 3c parallel to the magnetization direction C is mainly reproduced, and the first information recorded on the magnetic particles 3a perpendicular to the magnetization direction C is hardly reproduced because it involves a large azimuth loss. That is, the first and second information can be individually reproduced without causing crosstalk.

At this time, the orientation directions of the magnetic particles in the actual magnetic recording medium 3 are, of course, not limited to the three types described above, but are randomly distributed in all orientation directions, so some crosstalk occurs, but it is sufficient. It was confirmed that a reproduced signal with a S/N ratio suitable for practical use could be obtained.

<Problems to be solved by the invention> With the development of the above-mentioned cross-recording method,
It has become necessary to develop a magnetic head suitable for use in this method. In other words, in the conventional helical scan magnetic head, which consists of two heads arranged with a phase difference of approximately 180 degrees on the same circumference on a plane perpendicular to the rotation axis, the same track cannot be tracked. Duplicate tracing with the two heads is not possible.

In view of the above-mentioned points, it is an object of the present invention to provide a magnetic head capable of realizing cross recording using a helical scan method.

<Means for Solving the Problems> The present invention achieves the above object by using first, second, and third heads arranged with a phase difference of approximately 90° with respect to adjacent heads on the same circumference. and having a fourth head:
The first and third heads have a phase difference of approximately 180 degrees with respect to each other, whereas the second and fourth heads have a phase difference of approximately 180 degrees with each other. In the axial direction of the shaft, the track pitches of the tracks formed by the first and third heads are different from each other, and the azimuth angle of the gap between adjacent heads is wide.

Effect> According to the present invention having the above configuration, when the track formed by the first head and the track formed by the third head are arranged adjacently, the track formed by the second head The head follows the track formed by the first head, and the fourth head follows the track formed by the third head. At this time, since the azimuth angle of the gap between adjacent heads is different, the information recorded by the second head is different from the information recorded by the first head, and the information recorded by the third head is different from the information recorded by the first head. The information recorded by the four heads does not interfere with each other.

<Example> Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 1 is an explanatory diagram conceptually showing the magnetic head of this embodiment when viewed from above, and FIG. 2 conceptually shows the magnetic head when viewed from the front. As shown in both figures, the first to fourth heads 1.2.3.4 are arranged on the same circumference formed by the circumference of the cylinder 5, with a phase difference of approximately 90° from each other. ing. In other words, the first and third heads 1.3 are arranged on the same circumference with a phase difference of about 180°, that is, the conventional magnetic head standardized in the helical scan method, and the first A second head 2.4 and a fourth head 2.4 are added to the third head 1.3, which are arranged on the same circumference with a phase difference of approximately 90''.

Further, in this embodiment, the second head 2 follows the first track formed by the first head 1, and the fourth head 4 follows the second track formed by the third head 3. It is necessary to Therefore, the second and fourth heads 2.4 are different from the first and third heads 1.3 in terms of the rotation axis of the cylinder 5, that is, the rotation axis 6 of the first to fourth heads 1 to 4. The first and second tracks are offset by half the track pitch Tp in the axial direction. In this way, the first track formed by the first head 1 and the second track formed by the third head are arranged adjacent to each other. That is, when recording in accordance with the standard format for magnetic recording using the conventional helical scan method, the second head 2 tracks the first track, and the fourth head tracks the second track.
They started to follow each other's tracks. Further, among the first to fourth heads 1 to 4, adjacent ones have different azimuth angles of gaps. 1st to 4th heads 1 to 4
The preferred azimuth angle to be used will be discussed in detail later, but the first
When the difference in azimuth angle between head 1 and second head 2 and the difference in azimuth angle between third head 3 and fourth head 4 are 90 degrees, two types of cross-recording on the same track are recorded. When reproducing one of the information, the azimuth loss of the other becomes maximum, allowing the best reproduction by the first and second heads 1, 2 or the third and fourth heads 3.4.

FIG. 3 is a perspective view showing a mode in which information is recorded on or reproduced from a magnetic tape, which is a magnetic recording medium, by the magnetic head of this embodiment. As shown in the figure, the magnetic tape 7 running in the direction of the arrow in the figure has first to fourth heads 1 to 4 (not shown in the figure) that rotate as the cylinder 5 rotates in the direction of the arrow B. head 1.2
) was received well and thereby recorded the +IIi information/
It is set to play. At this time, the second head 2
The fourth head 4 traces the first track 8 formed by the first head at a distance of % track length TQ of the first track 8, and although not shown, the fourth head 4 traces the first track 8 formed by the first head. A second track formed by the third head 3 adjacent to the track 8 is followed.

FIG. 4 is an explanatory diagram conceptually showing tracks formed by the magnetic head according to this embodiment, together with the magnetic tape and the head. In the figure, θ1.03 is the azimuth angle of the first and third heads 1.3, θ2. θa is the azimuth angle of the second and fourth heads 2.4, and these azimuth angles θ7. θ
2 are first and second heads 1.2 for the magnetic tape 7;
The angle of deflection in the clockwise and counterclockwise directions with respect to a line perpendicular to the relative movement direction C of the line is used as a reference. In this embodiment, the azimuth angle θ1. θ3 or 45° clockwise, azimuth angle θ2. θ4 is 45° counterclockwise.

Therefore, the longitudinal directions of the gaps la and 3a and the longitudinal directions of the gaps 2a and 4a are orthogonal to each other.

According to the magnetic head of this embodiment, the second head 2 follows the first track 8 formed by the first head 1, and the second track 9 formed by the third head 3 follows the fourth track 8. Head 4 follows suit. This becomes clear if you think about it as follows.

That is, the first track 8 formed by the first head 1 and the third track 8 having a phase difference of 180° on the same circumference on the same plane perpendicular to the rotation axis 6 with respect to the first head 1. When the track pitch with respect to the second track 9 formed by the head 3 is Tp, if the second and fourth heads 2.4 are perpendicular to the first and third heads 1.3 and the rotation axis 6. If they are on the same plane, the first and third heads are 1.3 to 90 degrees.
The second and fourth heads 2.4 having a phase difference of ° follow between the first track 8 and the second track 9; %T in the axial direction of the rotating shaft 6 with respect to the first and third heads 1.3
It is p-deviated. Therefore, the second head 2 follows the first track 8, and the fourth head 4 follows the second track 9. Therefore, the first and third heads 1.3 transmit the first information, and the second and fourth heads 2.4 transmit other second information to the first and second tracks 8. 9 can be cross-recorded respectively.

The first and second tracks 8.9 formed by the magnetic head of this embodiment are formed by the first and third heads 1.3 without forming a guard band between them. That is, the track pitch Tp is the same as that of the first and second tracks 8.
It has the same width as the track width of 9. Also, the solid lines in the first and second tracks 8.9 indicate the gap between the first and third heads 1.3! a, the direction perpendicular to the first magnetization direction which is the magnetization direction formed by 3a, that is, the gap I
a shows the long plane direction of 3a. In other words, it can be said that the solid line symbolically represents the first information IO. On the other hand, the dashed lines in the first and second tracks 8.9 indicate the second and third tracks.
The figure shows a direction perpendicular to the second magnetization direction E, which is the magnetization direction formed by the gaps 2a and 4a of the head 2.4, that is, the longitudinal direction of the gaps 2a and 4a. In other words,
It can be said that the broken line symbolically shows the second information 11.

FIG. 5 is an explanatory diagram conceptually showing the first to fourth heads 1 to 4 according to the embodiment, together with the magnetic tape 7 on which they each record information. Azimuth angle θ1. of the first and third heads 1.3 in this embodiment. As described above, θ3 is 45° clockwise, and the azimuth angle θ2.4 of the second and fourth heads 2.4. θ4 is 45° counterclockwise. Therefore, the first and second information to and II recorded by these first to fourth heads 1 to 4 are different from that recorded on the first track 8 and the second It becomes parallel to what was recorded on track 9. For this reason, in this example, in addition to the fact that the recording is guard breadless,
When reproducing the first and second information 10.11, the first information 10 of one and the other of the first and second tracks 8.9 and the second information of one and the other interfere with each other, respectively. However, there is a possibility that the S/N ratio of the reproduced signal may be deteriorated. Incidentally, the first information 10 and the second information 11 are orthogonal, and when one is reproduced, the other is accompanied by the largest azimuth loss, so the other is hardly reproduced.

The first information lO and the second information 11 recorded on the first track 10 and the second track II, respectively,
In order to reduce the mutual interference as described above, the azimuth angle θ3 . θ, and the azimuth angle θ2 of the second and fourth heads 2.4. It is sufficient that θ4 is different from each other. On the other hand, if we consider mutual interference during reproduction of the first and second information 10.
It is most desirable that 11 be orthogonal.

FIG. 6 is an explanatory diagram conceptually showing the first to fourth heads according to another embodiment in which the azimuth angles are respectively selected in consideration of the above points, together with the magnetic tape 7 on which each of these heads records information. be. The azimuth angle θ5 of the first head 21 in this embodiment is θ clockwise with respect to the perpendicular 2, (= 45
°) + δ, the azimuth angle θ6 of the second head 22 is the perpendicular 2
The azimuth angle θ of the third head 3 is 02 (=45°) - δ counterclockwise with reference to 0, and the azimuth angle θ of the third head 3 is 0 clockwise with reference to perpendicular 1.
3 (= 45") - δ and the azimuth angle θ8 of the fourth head 4 is 04+δ in the counterclockwise direction with respect to the perpendicular 2. That is, the azimuth angles θ5, θ7 and θ6, θ8 are respectively 2δ°. There is a difference, and the azimuth angle θ5.θB and θ7
．． There is a difference of 90° in θ8. Therefore, these first to
The first information 30 and the second information 31 recorded on the magnetic tape 7 by the fourth heads 21 to 24 are orthogonal to each other and have different azimuth angles between the first and second tracks 8.9. , that is, θ5. ≠07 and θ6. ≠08
becomes.

Thus, according to this embodiment, when playing back, the same track 8.9
Not only do the first and second information 30.31 recorded on the track 8.9 hardly interfere with each other, but also the first information 30 and the second information recorded on the adjacent track 8.9 Mutual interference among 31 comrades is also reduced.

Various combinations can be considered for the first information and second information recorded by the magnetic head of the above embodiment, and for example, the following combinations are suitable.

Margin below However, when recording video signals of odd and even fields as the first and second information, the distance between the first and third heads and the second and fourth heads is % on the same track. Vertical scanning period (y2V period)! ! 1, therefore special measures are required, such as recording video signals of odd fields with a delay of 34V.

<Effects of the Invention> As specifically explained above with the embodiments, according to the present invention, the first and second heads formed by the first and third heads
The second and fourth heads follow the track of
Since the azimuth angles of the second and fourth heads with respect to the third head are greatly different, good loss recording can be performed.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is an explanatory diagram conceptually showing the magnetic head according to the embodiment of the present invention when viewed from above, and FIG. 2 is a conceptual diagram showing the magnetic head viewed from the front. FIG. 3 is a perspective view showing how the magnetic head records and reproduces information, and FIG. 4 conceptually shows tracks formed by the magnetic head together with the magnetic tape and the head. 5 is an explanatory diagram conceptually showing the magnetic head together with a magnetic tape, FIG. 6 is an explanatory diagram conceptually showing a magnetic head according to a second embodiment of the present invention together with a magnetic tape, and FIG. (a) and (b) are explanatory diagrams schematically showing the orientation state of acicular particles, which are magnetic particles, together with a magnetic head. In the drawing! , 2. 3.4.21.22.23.24, the head 6 is the rotating shaft, 7 is the magnetic tape, 8.9 is the track, θ1. θ2. θ3. θ4. θ5. θ6. θ7. θ6 is the azimuth angle, and Tp is the track pitch.

Claims (1)

[Claims] It has first, second, third, and fourth heads arranged with a phase difference of approximately 90 degrees with respect to adjacent heads on the same circumference, and also has a phase difference of approximately 180 degrees with respect to each other. The second and fourth heads, which have a phase difference of approximately 180° with respect to the first and third heads,
With respect to the axial direction of the rotation axis of the fourth head, 1/1/2 of the track pitch of the tracks formed by the first and third heads, respectively.
2. A magnetic head in a helical scan system, characterized in that adjacent heads have different azimuth angles of gaps.