JPS63263623A - Magnetic recording/reproducing method - Google Patents

Abstract

PURPOSE:To automatically execute tracking correction based upon an output difference by successively forming recording tracks on a magnetic tape while oscillating magnetic heads at prescribed frequency levels to form the recording tracks having different oscillation frequency components at both the side edges of each track, and at the time of reproducing, extracting oscillation frequency components of outputs reproduced by the magnetic heads. CONSTITUTION:The magnetic heads 3a, 3b are oscillated and scanned at oscillation frequency levels fa, fb which are several hundreds - several thousands Hz and not integer times and at 1/10-1/20 amplitude of a track shift to form waveforms having the components fa, fb on both the sides of the recording tracks a1, b1 - an, bn. At the time of reproducing, the tracks are scanned without oscillating the heads 3a, 3b. The amplitude values of the outputs Vfa, Vfb of the fa, fb are detected and compared through amplitude detection and output separation. Tracking correction F, F' is automatically executed so that output difference DELTAV=0 is formed and the heads 3a, 3b are allowed to follow the recording tracks.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording and reproducing method, and more particularly, the present invention relates to a magnetic recording and reproducing method, and more specifically, recording and reproducing by correcting the tracking of a magnetic head used in a head rotation and helical scanning type VTR device. It is about how to do this.

For example, the current home-use V using the helical scanning method
As shown in Figures 4 and 5, the TR device is equipped with a recording and reproducing magnetic field on the outer periphery of a rotating drum (2) whose rotating shaft is slightly inclined with respect to the running direction of the magnetic tape (1). The heads (3a) and (3b) are mounted at 180° opposite positions.

First, recording with this VTR device involves rotating the rotating drum (2) at a constant speed as shown in FIG.
2) a recording trunk AI for video signals tilted at a predetermined angle on the magnetic tape (1) rotating in sliding contact with the outer peripheral surface of the recording trunk AI;
This is done by forming Bl, A2, B2... Furthermore, playback on a VTR device is performed using the recording trunks AI, B1 provided on the magnetic tape ('1) as described above.
, A2, B2...-, the magnetic head (3a) (3
A two-head heli force scanning system is adopted in which the two heads (b) are scanned alternately. Furthermore, during this playback, the magnetic head (3
a) Recording tracks A l , B 1 according to (3b)
, A2, B2, . . . , a slight off-track occurs, and video signals on adjacent recording tracks are also reproduced, resulting in crosstalk. Therefore, in order to prevent deterioration of image quality due to this crosstalk, the 5th B! 0 and a magnetic head (3a) as shown in FIG.
For example, +θ° in the magnetic gap Ga5Gb of (3b)
An azimuth recording method is adopted in which an azimuth angle of , -θ° is provided and video signals of adjacent recording tracks are not reproduced.

In this way, when playing back a VTR device, a magnetic head (3a) (3
b) Record the scans of trunks A, B, AH, B2.
・Tracking correction is required to prevent track deviation by following -.

That is, a recording track A is formed along the side edge of the magnetic tape (1).
1, B1, A2, B2 --- by providing a control track (not shown) separately from the control track and reading out the control (pulse) signal written in this control track with a control head (not shown). Rotating drum (
In this tracking correction, in which the phase (rotation angle) of 2) and the phase of the magnetic tape (1) are adjusted to a certain relationship, since the rotational speed of the rotating drum (2) is constant, By temporarily increasing or slowing down the running speed of the magnetic tape (1), the rotation speed of the rotating drum (2) is increased.
) and the magnetic tape (1) are aligned in phase. the current,
This tracking correction is performed by manually varying the running speed of the magnetic tape (1) described above for each VTR device.

By the way, automatic tracking correction is difficult in the above-mentioned helical scanning home VTR device.

That is, tracking correction for ensuring compatibility of the magnetic tape (1) between various VTR devices is performed on the magnetic tape (1).
The rotating drum (2) and the magnetic tape (1) are aligned in phase by reading the control signal written in the control trunk (1). However, on the magnetic tape (1), the control track where the control signal is written and the recording track where the video signal is written A1.131, A2, B! . . . is slightly different in various VTR devices, it has been difficult to automate the above-mentioned tracking correction.

Incidentally, in recent years, 8mm VTR devices that have become more and more penetrating have adopted automatic tracking correction.
This is done not by using a recording format like the R device, but by using a special recording format as shown in FIG. That is, on the recording trunk AI, Bl', A, , B, - of the magnetic tape (lo), along with the video signal, four types of frequencies f1 % fl , f3, f4 are recorded in a frequency band different from that of the video signal. When simultaneously writing and reproducing a tracking pilot signal consisting of
For example, when scanning the recording trough B1 with the magnetic head (3b'), recording trunks AH and A adjacent on both sides
Frequencies f1, f3 of the tracking pilot signal on g
component is detected, and this frequency f1 is determined based on the detection output.
, magnetic tape (1°) so that the f3 components are at the same level.
) is automatically varied.

In this way, automatic tracking correction in an 8mm VTR device uses four types of frequencies f1, jj, and rs as described above.
A special recording format using a tracking pilot signal consisting of s'4 was required.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a magnetic recording and reproducing method that enables automatic tracking correction in conventional recording formats in helical scanning home VTR devices and the like.

The present invention has been proposed in view of the above-mentioned problems, and includes a magnetic head disposed on the outer circumferential surface of the rotating drum that is in sliding contact with the outer circumferential surface of the rotating drum and transmits a predetermined frequency to the rotating magnetic tape. After recording by forming a recording trunk on the magnetic tape while vibrating it, during playback, the vibration frequency component of the magnetic head playback output from the recording track is detected and extracted, and the extracted signal drives an actuator. This magnetic recording and reproducing method achieves the above object by correcting the tracking of the magnetic head.

According to the method of the present invention, during recording, by sequentially forming recording tracks on the magnetic tape while vibrating the magnetic head at a predetermined frequency, a recording trunk having different vibration frequency components on both sides is formed on the magnetic tape. formed on top. Further, during reproduction, the vibration frequency component of the magnetic head reproduction output from the recording track is detected and extracted, and the tracking of the magnetic head is automatically corrected based on the output difference.

A helical scanning home VTR using the back application method of the present invention
An embodiment applicable to conventional recording formats in devices will be described with reference to FIGS. 1 to 3(a) to 3(d). However, the same or equivalent parts as in FIGS. 4 to 6 are given the same reference numerals and their explanations will be omitted.

A feature of the method of the present invention is that during recording, the magnetic heads (3a) (3b) of the rotating drum (2) scan the magnetic tape (1) while vibrating at a predetermined frequency. Recording trunk al, bl%a described below
t, bl '-', and during reproduction, the imaging frequency component of the reproduction output of the magnetic head is detected and extracted, and the magnetic heads (3a) and (3b) are caused to scan while performing tracking correction.

During recording in the method of the present invention, the magnetic heads (3a) (3b)
) as a specific means for vibrating the magnetic heads (3a) and (3b) using an actuator made of a piezoelectric element such as a laminated ceramic or a bimorph. to be placed. During recording, driving voltages of different frequencies fa and fb are applied to the piezoelectric elements of the actuator to cause the piezoelectric elements to expand and contract, thereby causing the magnetic heads (3a) and (3b) to perform recording as shown in FIG. The tracks a1, bl, at, bl-- are scanned in the width direction while being vibrated at the frequencies fa and fb. The vibration frequency fas fb of the magnetic heads (3a) (3b) is selected to be a value of about several hundred to several KHz, which is not an integral multiple, and its amplitude is optimally about 4 to 10 times the width of the recording track. As described above, the magnetic head (3a)
(3b) is scanned so that the side edge (right side edge in the figure) of the already formed recording track overlaps the side edge (left side edge in the figure) of the next recording track to be formed. As a result, as shown in FIG. 1, the recording tracks al, bl, afi, bl-' formed on the magnetic tape (1) have a waveform shape having acid components of different frequencies fa and fb on both sides thereof.

When reproducing from the recording tracks a1, bl, at, bl-'' formed on the magnetic tape (1) in this way, the recording tracks a1, bl, at are reproduced without vibrating the magnetic heads (3a) (3b). ,bl・-
・Scan the top in a straight line. At this time, the magnetic head <3a
) The reproduction output Va+Vb of (3b) is as shown in Fig. 3(a).
As shown in FIG. 2, the video signal has a distorted waveform containing different vibration frequency fa and fb components, and as shown in FIG. 2, the reproduction output Va from the magnetic heads (3a) (3b)
+Vb imaging frequency fas fb acid component detected (second
As shown in FIG. 3(a) and FIG. 3(b), a detection output Vfa+Vfb is obtained in which a high vibration frequency fb component is superimposed on a low imaging frequency fa component. After this detection, as shown in Figure 3 (C) and (d), the detected output Vfa + Vfb is separated by a filter (Figure 2 (B)), and then each vibration frequency fa
,, detect and compare the amplitudes of the outputs Vfa and Vfb of the fb component (Figure 2 (c)), the output difference Δ due to this amplitude comparison
The magnetic heads (3a) (3b) are made to follow the recording tracks a1, bl, at, bl, . . . by automatically performing tracking correction so that V=Vfa−Vfb becomes zero. That is, during tracking correction of one magnetic head (3a), if the output difference ΔV becomes positive, the magnetic head (3a)
3a) has shifted in the direction of the solid arrow F in Figure 1. In this case, either temporarily increase the running speed of the magnetic tape (1) or expand and contract the piezoelectric element of the actuator to move the magnetic head (3a). ) in the direction of the broken line arrow F° in the figure. Further, when the output difference ΔV becomes negative, it means that the magnetic head (3a) is shifted in the F° direction in the figure.

At this time, contrary to the above, the running speed of the magnetic tape (1) is temporarily delayed, or the actuator is driven to displace the magnetic head (3a) in the direction F in the figure. In addition, when correcting the tracking of the other magnetic head (3b), the deviation direction F of the magnetic head (3b) is determined depending on the sign or negative of the output difference ΔV.
, F' are reversed in the case of the magnetic head (3a), so the magnetic head (3a)
The operation is the opposite of that for .

By the way, the above VTR apparatus generally has special playback functions such as slow and speed search in addition to the above-mentioned standard playback. For example, during slow playback, the magnetic head (
3a) If the same recording track is scanned n times in (3b), it will be reproduced at a speed of 4, and during speed search, the magnetic head (3a)
If (n-1) recording tracks are skipped and scanned in (3b), playback will be performed at 1 times the speed.During this special playback, the rotating drum (2) is independent of the number of image frames, etc. Yes, constant speed rotation is required, so magnetic tape (
1) Varying the traveling speed. As a result, the magnetic head (3a
) (3b) are recording tracks al, bl, a2
, b2- is not scanned accurately, and noise bands occur in the reproduced image. However, the pressure used in the method of the present invention? !
By driving an actuator consisting of an element, the magnetic heads (3a) (3b) are moved to recording tracks al, b.
It becomes possible to automatically perform tracking correction by following l, a2, b2, . . . , and it becomes easy to achieve noiseless special reproduction.

According to the method of the present invention, head rotation,
Automatic tracking correction for conventional recording formats such as helical scanning home VTR devices can be easily realized, and magnetic tapes can be made compatible with various VTR devices with a simple means, making magnetic tape of great practical value. A recording/playback method can be provided.

[Brief explanation of drawings]

1 to 3(a) to 3(d) are for explaining one embodiment of the magnetic recording and reproducing method according to the present invention, and the second figure shows the recording tracks on the magnetic head and magnetic tenip. Fig. 2 is a block diagram showing the processing procedure of re-output during playback, and Figs. 3(a) to (d) are waveforms at each processing stage of playback output during playback. FIG. 3 is a waveform diagram showing output. FIG. Fig. 4 is a perspective view showing the rotating drum' and magnetic tape of the VTR device, 5WJ is a plan view of Fig. 4, and Figs. 6 and 7.
The diagram is for explaining the conventional magnetic recording and reproducing method.
FIG. 6 is a plan view showing the magnetic head and recording trunk on the magnetic tape in a helical scanning VTR device, and FIG. 7 is a plan view showing the magnetic head and recording tracks on the magnetic tape in an 8 mm VTR device. be. (1) - Magnetic tape, (2) Single rotation drum, (3
a) C3b) - Magnetic head, 'a 1 , bl
s a2.1) g ”-' recording track, faJfb・
...-Frequency. Figure 1 Figure 2 Figure 3 (a)

Claims (1)

[Claims] (1) A magnetic head disposed on the outer periphery of the rotating drum is vibrated at a predetermined frequency with respect to the magnetic tape rotating in sliding contact with the outer periphery of the rotating drum, while forming recording tracks on the magnetic tape to record information. Then, during reproduction, the vibration frequency component of the magnetic head reproduction output from the recording track is detected and extracted, and the extracted signal drives an actuator to correct the tracking of the magnetic head. A magnetic recording and reproducing method.