JPS6234322A - Magnetic recording and reproducing system - Google Patents

Abstract

PURPOSE:To execute a tracking control being excellent in its stability and responsiveness with high accuracy by using a tracking control signal recorded by the same recording head by a time division multiplex with recording information, at the time of reproduction. CONSTITUTION:At the time of recording, recording information S2 and a tracking control signal S1 are sent to a recording switcher 1, brought to a time division in a form synchronizing with the rotation of a drum by a drum rotating phase signal and recorded in a recording medium by the same recording head. A reproducing signal by a head at the time of reproduction is sent to a reproducing switch 2, separated into the signal S1 and the information S2 by the drum rotating phase signal, the signal S1 is sent to a tracking servo-means 3, amplified 4 and drives a fitting press-contacting element of the head 8, and the information S2 is sent to a reproducing equalizer $ demodulator and reproducing information is obtained. By using such a signal S1, a reproducing head can be controlled to an optimum tracking state.

Description

TECHNICAL FIELD The present invention relates to a magnetic recording and reproducing system, and more particularly to an improvement in a tracking control system in a magnetic recording and reproducing apparatus.

There is always a demand for high-density recording in conventional magnetic recording and reproducing devices, and efforts are being made to achieve higher densities in terms of both linear density and track density. Improvements in linear density have been made mainly in magnetic heads and magnetic tapes, and recording wavelengths of 1 .mu.m or less have become practical, which is approaching the limit when considering head shape and magnetic tape particle size. On the other hand, the track density depends on many factors such as mechanical assembly precision and stability of tape running, and track widths of about 10 μm are currently in practical use.

Conventionally, especially in video tape recorders (hereinafter referred to as VTRs), while recording video with a rotating head for tracking control, a signal for tracking control is simultaneously recorded in the longitudinal direction of the tape, and this signal is used during playback. Optimal tracking is obtained by controlling the tape feed speed and phase.

It is well known that such a signal is called a control track signal.

As described above, in tracking control using control track signals, optimal tracking may not always be achieved due to differences in environmental conditions between recording and playback, differences in mechanical position between the control track head and rotating head, tape elongation, etc. It is difficult to obtain. Furthermore, optimization within one track (for example, following a curved track, etc.) is difficult, so tracking control is performed directly from the track of a rotating head.

The method of directly controlling the tracking of the rotary head, as in conventional devices, focuses on maximizing the amplitude of the signal reproduced by the rotary head, and moves the head a small amount in the track width direction using a piezoelectric element. Methods for detecting tracking positions and obtaining optimal tracking conditions are well known. Also, a method using a phase difference between signals reproduced using a head having l pairs of azimuth angles, a method using a pilot signal, etc. have been announced.

However, according to the method of the conventional device described above, it is difficult to utilize the amplitude and phase of the signal that should be reproduced.
It is not necessarily optimal for tracking control, and therefore the detection accuracy, detection sensitivity, detection dynamic range, etc. of tracking information are insufficient, and as a result, the stability and responsiveness of tracking control are deteriorated. In particular, when using a VTR that requires a high track density, and when editing work using the VTR or editing still images frame by frame, it is difficult to maintain track continuity at the editing point with current mechanical precision. This method is extremely difficult, and requires very precise machining and assembly techniques to meet the specifications, making it technically difficult and the equipment expensive. Therefore, there has been a desire for a tracking control device that has stability and responsiveness that can tolerate the above-mentioned mechanical accuracy to some extent.

Purpose of the Invention The present invention was made with the purpose of overcoming the above-mentioned drawbacks of conventional devices, and its purpose is to provide a magnetic recording and reproducing method that enables tracking control with high precision, stability, and responsiveness. There is.

The configuration of the present invention is such that during recording, the information to be mainly recorded and the tracking control signal are time-divided and recorded in the same recording in rad, and during playback, the tracking control signal reproduced by the playback head is The playback head is controlled to an optimal tracking state using the following method.

Embodiments Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, in which a recording head 7 and a reproducing head 8 are attached to a rotating drum 6.
Information is recorded on the magnetic tape 9 by. Recording signals and reproduction signals are sent via rotary transformers RTI and RT2. The above configuration etc. are the same as the method in the conventional device.

During recording, the information to be recorded and the tracking control signal are sent to the recording switcher 1, and are time-divided and recorded in synchronization with the rotation of the drum using the drum rotation phase signal. On this occasion,
The information to be recorded and the tracking control signal do not overlap in time, and for this reason, it is natural that the information to be recorded must be compressed in the time axis as necessary.

During reproduction, the signal reproduced by the reproduction head 8 is sent to the reproduction switcher 2, and is separated into a tracking control signal S1 and main information S2 according to a drum rotation phase signal. The tracking control signal Sl is sent to the tracking servo means 3, and further amplified through the piezoelectric element drive amplifier 4,
A piezoelectric element (not shown) to which the reproducing head 8 is attached is driven.

On the other hand, the main information S2 is sent to the reproduction equalizer and demodulator 5 to obtain reproduced information. Here, the signals S1 and S2 do not overlap in time, and during the period when the signal S1 exists, the playback head 8
It goes without saying that there is no problem in obtaining the main information S2 even if there is some jitter or overshoot due to the track following of the signal S1. An optimal tracking state can be obtained during the signal 82 period simply by performing track following using a weak closed loop.

FIG. 2 shows the track locus of a tape edited and recorded using the present invention. In the diagram, the hatched part at the beginning of the track is the tracking control signal S1, after that is the main information S2, and the point A is the editing switching point. To be. If the reproducing head scans from the lower end of the track toward the upper end to obtain a reproduced signal, the track pitch I changes before and after point A, so instantaneous tracking cannot be achieved and information cannot be obtained under normal circumstances. However, since the head rests on a part of the shaded area, the tracking control signal can be detected with some S deterioration, and optimal tracking can be obtained before the shaded area ends.

That is, the reproducing head follows a trajectory as shown by the arrow in the figure (this is shown conceptually, and naturally there may be some overshoot etc. depending on the control method), and the subsequent information portion can be stably reproduced.

FIG. 3 shows a recording track locus in a case where the track curvature is large by 9 degrees using the present invention. In this case, the track curve is not very sharp, but tracking control signals are recorded at the beginning and center of the track to improve the frequency characteristics of tracking.

The tracking control device/device that can achieve high track density has been described above with reference to embodiments of the present invention. However, the purpose of the present invention is high-density recording, and tracking control signals are mainly used to improve trunk density. It takes advantage of what can be accomplished with little information. On the other hand, in order to obtain a very high track density, the tracking control signal becomes long and the area of the main information becomes narrow, which impairs high density [this is not the main subject of the present invention]. However, in magnetic recording, it has been theoretically and experimentally confirmed that reducing the track density reduces the S/N degradation of the reproduced signal by reducing the linear density. The direction is to mainly do this.

As described above, according to the present invention, it is possible to perform tracking control with high accuracy, stability, and responsiveness while increasing track density.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an explanatory diagram of the case where discontinuity of editing points is corrected and reproduced, and FIG. 3 is an explanatory diagram of the case where curved track following reproduction is performed. Explanation of symbols of main parts 1... Recording switcher 2... Playback switcher 3... Tracking servo means 7... Recording head 8... Playback head

Claims (1)

[Claims] During recording, a recording information signal and a tracking control signal are time-division multiplexed and recorded onto a recording medium by the same recording head, and during playback, the tracking control signal reproduced by the playback head is used to control the tracking of the playback head. A magnetic recording and reproducing method characterized by: