JPS6040522A - Automatic tracking system - Google Patents

Abstract

PURPOSE:To reduce the copying action of a magnetic tape and to attain the satisfactory automatic tracking by adding a signal which gives microvibrations to a magnetic head with a high frequency to a control signal which drives the magnetic head. CONSTITUTION:A signal track 2 and a track shift detecting track 3 are formed on a magnetic tape 1, and a signal reproducing head 5 and track shift detecting heads 6A and 6B are provided on a reproduction head 4. The output signals of the heads 6A and 6B are processed and supplied to a comparator 13. The output of the comparator 13 is added 16 to a signal which sets the output of an oscillator 14 at a proper level via an attenuator 15. This addition output is supplied to a driving device 7 which drives the head 4 in the width direction of the tape 1. Thus the copying action of the tape 1 can be reduced. This ensures the satisfactory automatic tracking.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a racking method for a magnetic recording/reproducing device using magnetic tape.

[Technical background of the invention and its problems]

In general, in a magnetic recording and reproducing device that uses magnetic tape, such as a fixed head recording and reproducing device, the magnetic tape moves up and down in the width direction while the magnetic tape is running, resulting in so-called track misalignment.C Level fluctuation of the reproduced signal occurs, causing signal deterioration.

Furthermore, recently there has been a demand for high-density recording such as PCM recording, and the use of multi-heads having a plurality of tracks has been eliminated, and moreover, the track pitch and track width have been reduced. As the track width becomes narrower, track misalignment is more likely to occur due to the vertical movement of the magnetic tape in the width direction, and level fluctuations in the reproduced signal become more noticeable, causing a serious problem during reproduction.

Conventionally, guide posts or the like for guiding the upper and lower ends of the magnetic tape are provided in the tape running mechanism to prevent vertical movement of the magnetic tape, thereby reducing the occurrence of track misalignment. However, in this method of preventing the downward movement of the magnetic tape by bringing the upper and lower ends of the magnetic tape into contact with the flanges of the guide post, mechanical stress is applied to the upper and lower ends of the magnetic tape, causing the upper and lower ends to The problem is that it can cause damage.

As another method, various methods have been considered in which a track misalignment between a magnetic head and a track on a magnetic tape is detected, and the magnetic head is driven to correct the track misalignment to perform auto-tracking.

However, even with this method, there is a problem that the tape moves in accordance with the movement of the magnetic head, a so-called tape tracing operation, and it is not always possible to sufficiently correct track deviations.

[Purpose of the invention]

This invention has been developed to deal with the above-mentioned problems, and detects a track misalignment between a magnetic head and a track on a magnetic tape, and drives the magnetic head to correct the trunk misalignment for auto-tracking. The object of the present invention is to provide a method for reducing the tape tracing operation and performing good auto-tracking.

[Overview of the invention]

This invention provides means for driving the magnetic head in the width direction of the magnetic tape to include a control signal for correcting the deviation (trunk deviation) of the magnetic head with respect to the track of the magnetic tape. The characteristic of this method is that it supplies a drive signal on which a signal of a lower level than this signal is superimposed.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows an embodiment of the auto-tracking device of the invention. In FIG. 1, the magnetic tape 1 is still in contact with the reproducing head 4 and slides in the direction of the arrow.

On the magnetic tape 1, there are a signal track 2 and a track deviation detection track 3, and on the raw head 4, there are
A signal reproduction head 5 and a trunk displacement detection head 6A,
6B is provided.

The configuration of a circuit for creating a drive signal to be supplied from the signals detected by the track deviation detection heads 6A and 6B to the drive device 7 that drives the magnetic head 4 in the width direction of the magnetic tape 1 is as shown in FIG. 2, for example. It is something.

The output signals of the track deviation detection heads 6A and 6B are filtered through filters 9A and 9B, and rJT variable resistance 10A, respectively.
The signal is supplied to the comparison circuit 13 via IOB, amplifiers 11A, , IIB, and low-pass filters 12A, 12B. Filter 9A.

9B is for passing only desired detection signals from among the signals reproduced by the track deviation detection heads 6A and 6B. The variable resistors +OA and IOB are for adjusting the level of the playback output, and while the magnetic head 4 is running at the reference position of the magnetic tape 1, the playback outputs of both should be equal, but in reality they differ slightly. Therefore, fine-tune the deviation.

The output of the comparison circuit 13 is the output of the excavator 14 and the output of the attenuator 15.
The output is added by an adder 16 to a value set at an appropriate level by the adder 16, and the output thereof is supplied through a drive amplifier 17 to a drive unit [7] that drives the magnetic head 4 in the width direction of the magnetic tape 1.

By the way, the drive device 7 for the magnetic head 4 used here is
It may be of any type, such as an electrodynamic type using a movable ring or a piezoelectric type using a piezo effect, but its vibration amplitude characteristics are as shown in FIG. 3, for example.

Further, the wave number of waving (meandering) when the magnetic tape 1 runs is about 10) Tz at most. Specifically, for example, when the tape speed is 9.5 cm/s, the main components of waving are 4 Hz due to the rotation speed of the roller in the cassette half and 3.27 Hz due to the rotation speed of the pinch roller. On the other hand, the same wave number supplied by the oscillator 14 is set to a frequency sufficiently higher than the waving frequency, for example, 100 Hz, within a range below the resonance same wave number according to the vibration amplitude characteristics of the head.

Further, in this case, the output of the excavator 14 is added to the output of the comparator circuit 13 by the adder 16, but it is necessary to set the output level to a sufficiently low level compared to the output level of the comparator 13.

〔Effect of the invention〕

Conventional compact cassettes allow a tape waving width of up to ±50 μm. In the case of PCM recording, considering compatibility, good auto-tracking is an essential technology, but magnetic tape 1 and magnetic head 4
When the magnetic head 4 is driven in the width direction of the magnetic tape 1 using a control signal generated simply from a comparison signal of this detection signal, the tracking movement of the magnetic tape 1 causes a track deviation of 30 to 40%. 'A cannot be corrected.

However, according to the present invention as described above, by adding a signal that slightly vibrates the magnetic head 4 at a high frequency to the control signal that drives the magnetic head 4, the tracing operation of the magnetic tape 1 can be almost eliminated. This makes it possible to perform good auto-tracking.

Further, the tracing operation of the magnetic tape 1 is generally highly dependent on the humidity of the environment, and the higher the humidity, the more the operation becomes more severe, but with the method according to the present invention, the humidity dependence is also significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a mechanism of an embodiment of auto-tracking according to the present invention, and FIG. 2 is a configuration diagram for generating a drive signal for driving a magnetic head in the width direction of a magnetic tape from a track deviation detection signal. , FIG. 3 shows an example of vibration amplitude characteristics of a magnetic head drive device. 1...Magnetic tape, 2...Signal track, 3...
・Trunk shift detection track, 4... playback head,
5... Signal reproduction head, 6A, 6B... Track deviation detection head, 7... Drive device, 8...
Installation is at the base, 9A, 9B...filter, IOA
, IOB... variable resistor, 11A, 11B... amplifier. 12A, 12B...Low pass filter, 13...Comparison circuit, 14...Oscillator, 15...Attenuator, I6
...Adder, 17...Drive amplifier. Agent Patent attorney Kensuke Norichika (and 1 other person) Figure 1 Figure 3 1 10 100 [1'Hz': 1 Frequency! Me;

Claims (1)

[Claims] Means for detecting the slippage of a magnetic head with respect to a track on a magnetic tape, and control for driving the magnetic head to correct the misalignment according to the amount of track misalignment detected by the means. means for generating a signal high; 1. An auto-tracking system for a magnetic recording/reproducing apparatus, comprising means for driving a magnetic head in the width direction of a magnetic tape based on a signal.