JPS60124019A - Tracking control method of multi-track magnetic head - Google Patents

Abstract

PURPOSE:To omit a track exclusively used for tracking control and also receiving virtually no effects of the drop-out, the clogging of a magnetic head, etc., by dividing the tracks of a magnetic head for reproduction into two groups of different arrays and using the difference of outputs obtained from both track groups as a tracking control signal. CONSTITUTION:For tracks of a magnetic head for reproduction, tracks P1-P4 are shifted to the upper side from the center O of a magnetic tape with tracks P5-P8 shifted to the lower side from the center O respectively. The reproduction outputs S1-S8 of tracks P1-P8 are amplified by amplifiers 1-8 and then delivers as outputs S1'-S8' after the adjustment of variance carried out by attenuators 9-16. The outputs S1-S4' given from attenuators 9-12 are used as the 1st signal f1; while the outputs S5-S8' of attenuators 13-16 are used as the 2nd signal f2. Both signals f1 and f2 are calculated by a differential amplifier 29 for production of a control signal Cs. In such a way, no track is needed exclusively for tracking control. Furthermore the tracking control is made possible without effect of drop-out of the magnetic tape.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a tracking control method for a multi-track magnetic head.

BACKGROUND TECHNOLOGY Generally, in a multi-track magnetic recording/reproducing device, by increasing the number of recording tracks, higher density recording is possible, but by increasing the number of tracks, the track pitch of each track becomes smaller by one. Stability of tape running is required. One way to deal with this problem is to use a precise running system to control tape drift, but this method also has its limitations. be. Here, a conventional example of this dynamic tracking method will be briefly explained.

FIG. 1 is a schematic diagram of the track format of this conventional multi-track magnetic head.
Tn to Tn correspond to the main information tracks on the magnetic tape for recording main information such as audio signals, and in particular, the large left part corresponds to the track of the recording magnetic head.
The narrow portions on the right side indicate the tracks of the reproducing magnetic head. Also, Tc corresponds to the control information track on the magnetic tape on which the control signal for the tracking servo is recorded, and in particular, The wide part on the left side shows the track of the recording magnetic head, and the narrow part on the right side shows the track of the reproducing magnetic head.

In the conventional system having the track format as described above, tracking servo is executed by the difference in output between tracks A and H of the reproducing magnetic head that traces the control information track of the magnetic tape. That is, as shown in FIG. 2, the outputs of A and B fl), +2
) is zero, but when the magnetic head shifts in the positive direction, the output (2) of track B decreases even though the output [+] of trunk A remains constant, so as a result, 2 The output difference (3) between the two tracks A and H increases, and this increase directs the reproducing magnetic head in the negative direction.

Conversely, if the magnetic head shifts in the negative direction, the output f+) of track A decreases and the output (2) of track B decreases.
Since is constant, the output difference (3) between the two is a negative value, and this negative value directs the reproducing magnetic head (3) in the positive direction.

As described above, since the output difference (3) is proportional to the tracking deviation, tracking control is conventionally performed using this output difference.

However, this conventional method requires a separate control information track, and has many drawbacks such as loss of control when the signal from such track is lost for a long time due to tape dropouts or magnetic head clogging, etc. There is.

<Object of the present invention> The present invention was invented in view of the above-mentioned drawbacks of the conventional system, and it is possible to reproduce control information by considering the track arrangement of the reproduction magnetic head that contributes to reproduction of main information. The present invention provides a tracking control method that does not require a dedicated track for tracking control such as a track for use, and is hardly affected by dropouts or clogging of a magnetic head.

<Example of the present invention> Explain in detail.

FIG. 3 is a schematic diagram showing the track format of the recording magnetic head and the reproducing magnetic head when the number of trunks on the magnetic tape is 8 tracks from Tl to T8 as an embodiment of the present invention. R1 to R8 on the left side indicate the tracks of the recording magnetic head, and P1 to P8 on the right side indicate the tracks of the reproducing magnetic head.

What should be noted in the above track format is that each trunk R1 to R8 of the recording magnetic head is aligned with the track center O of the magnetic tape, but among the tracks of the reproduction magnetic head, the trunks R1 to R8 of the magnetic tape Tracks P+ to P4 corresponding to tracks Tl to T4 are arranged above the center O, and tracks P5 to P8 corresponding to tracks T5 to T8 of the magnetic tape are shifted downward from the center 0. .

FIG. 4 is a circuit diagram showing a control signal generating circuit that generates a tracking control signal from the output of the reproducing magnetic head having the above-mentioned track arrangement, and 1 to 8 in the figure are tracks P+ of the reproducing magnetic head. Amplifying circuits 9 to 16 receive and amplify the reproduced outputs S1 to S8 of P8 to A, respectively, and are attenuators for adjusting variations in outputs 81' to Ss' obtained from the amplifying circuits 1 to 8.

Diodes 17 to 24 detect the outputs from the attenuators 9 to 16, and the outputs of diodes 17 to 20 are smoothed by a common capacitor 25 and then become the first signal fl. It is designed to be input to ten poles of the differential amplifier 29.

Further, the outputs of the diodes 21 to 24 in the diode group are smoothed by a common capacitor 27 and then converted into a second signal f.
2 and is to be input to one pole of the differential amplifier 29.

The differential amplifier 29 receives the first and second signals f1 +
fz is calculated and the control signal Cs for tracking control is calculated.
This outputs the following.

In the figure, 26.28 determines the discharge time constant of the capacitor 25.27, and is set to a sufficiently large time constant.

In the above-described configuration, when a magnetic tape signal (main information) is reproduced on each of the tracks P1 to P8 of the reproduction magnetic head, the reproduction outputs S+ to S8 of each track are amplified by amplifiers 1 to 8 and sent to attenuators 9 to 8, respectively. The dispersion is adjusted at step 16, and outputs 81' to Ss' and l~ are output (see the waveform diagram in FIG. 5).

Outputs S, I to 84' from attenuators 9 to 12 among these outputs S, l to 88' are detected and added by diodes 17 to 20, respectively, and then outputs 85 from attenuators 13 to 16 are added. ' to 88' are detected and added by diodes 21 to 24, respectively, and then smoothed by a common capacitor 27 to become a second signal f2, which is input to one pole of the differential amplifier 29, and then the first signal The control signal C is calculated by the differential amplifier 29 and f1.
In the waveform diagram of FIG. 5, the section (A) of the control signal Cs is such that the reproducing magnetic head shifts upward from the track center 0 of the magnetic tape in the waveform diagram of FIG. Indicates the case where it is a dog from P4,
Section B shifts downward and the output of tracks PI to P4 becomes P5.
This shows a case in which the outputs are more dog than those in tracks P+ to P8, and section C shows a case in which the outputs of tracks P+ to P4 are equal to those of tracks P5 to PR.

Therefore, when the control signal Cs is applied to the not-shown tracking servo mechanism of the reproducing magnetic head, the mechanism directs the reproducing magnetic head downward in section (B), and in both directions in section (B). In section (C), the current situation is maintained.

Also, in FIG. 5 above, points (a) and (b) indicate dropouts on the magnetic tape, but the influence of these dropouts does not appear on the first signal f1 at all. This is because the outputs S, l to S4' of the two attenuators 9 to 12 are detected by the diodes 17 to 2o, and then added and averaged to obtain one signal f1 (8).

<Effects of the Present Invention> The present invention provides a first track group in which each track of a reproducing magnetic head consisting of multi-tracks is shifted in a first direction from the track center of the magnetic tape, and The system is divided into a second track group shifted in the opposite direction, and the output difference between both track groups is used as a trunking control signal. There is no need to provide a trunk for control, and therefore, the track of the magnetic head can be effectively used for recording main information such as audio signals, and tracking control can be performed without being affected by magnetic tape dropouts. This is a great invention.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the track format of a multi-track magnetic head in a conventional multi-track magnetic head method, FIG. 4 is a block electric circuit diagram showing a control signal generation circuit in the tracking control method of the present invention, and FIG. FIG. 5 is an output waveform diagram used to explain the present invention. Agent Patent Attorney Aihiko Fukushi (and 2 others)

Claims (1)

[Claims] 1. Tracking control of a multi-track reproducing magnetic head on a magnetic tape, a first track in which each track of the reproducing magnetic head is shifted in a first direction from the track center of the magnetic tape. track group and a second track group shifted in a second direction opposite to the first direction, and tracking control is performed using the output difference between the outputs obtained from the first and second track groups. A tracking control method for a multi-track magnetic head using signals.