JPH0214452A - Tracking method in magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To remove the influence of the characteristic difference between reproducing systems in tracking information by recording a reference signal with a fixed head at the time of recording, regenerating the reference signal with a rotary head for obtaining a crosstalk at the time of reproducing and correcting the characteristic of the reproducing systems of both rotary heads. CONSTITUTION:At the time of recording, a tracking signal f2 is recorded in the part of the beginning of the track of a magnetic tape 50 with a head B, and simultaneously, the reference signal is recorded with a fixed head E. At the time of reproducing, the reference signal recorded with the fixed head E and the tracking signal f2 recorded with the rotary head B are regenerated with rotary heads A and C. Since relative speed between the magnetic tape 50 and rotary head is high, the reproduction can be executed without being influenced by an azimuth, the reference signal by the fixed head E is reproduced by a speed difference among the fixed head E and rotary heads A and C, and a crosstalk quantity is corrected according to the characteristic difference quantity. Thus, the tracking information can be obtained in which the influence of the characteristic difference between the reproducing systems is removed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a tracking method in a magnetic recording/reproducing device, and more specifically to a magnetic recording method in which signals are recorded and reproduced by diagonally scanning a rotating head onto a magnetic tape. The present invention relates to a tracking method in a playback device.

[Conventional technology]

Conventionally, in magnetic recording and reproducing devices that record and reproduce signals by diagonally scanning a rotating head with respect to a magnetic tape, capstan motors and cylinder motors are used to accurately trace tracks recorded diagonally. It is servo controlled.

For example, the VH3 system uses a tracking method that uses control signals recorded with a separate fixed head, and the 8mm video system uses a low-frequency tracking signal (or biloft signal) that is frequency-multiplexed with the image/audio signal. A method was adopted in which the crosstalk generated from the tracks on both sides adjacent to the playback track was used during playback.
DAT), by recording the tracking signal on a part of the recording track in a time-division manner, there is no need to manually adjust the tracking even when the tape is elongated or during compatible playback. This eliminates the need for overlapping.

With the increase in the amount of recorded information, a so-called multi-track recording method has been proposed in which the number of heads on a cylinder is increased and recording and reproduction are performed simultaneously with a plurality of heads.

If a multi-track recording method employs a time-division method in which tracking signals are recorded in a time-division manner, the sensitivity error of the recording amplifier or recording head will be directly linked to the tracking error, which is undesirable. Therefore, a configuration has been proposed in which a tracking signal recorded by one head is reproduced by two adjacent heads (Patent Application Publication No. 200562 of 1988).

[Problem to be solved by the invention]

With this configuration, the sensitivity error of the recording system basically does not affect tracking, but this is due to the fact that during playback,
Tracking matched perfectly. It is assumed that the outputs from two adjacent heads are equal in this state. In reality, there are differences in heads, differences in reproduction amplifier characteristics, differences in temperature characteristics, etc., and a means for finely adjusting these is required.

In addition, the output characteristics of the two reproduction systems change due to changes over time such as wear of the head. Therefore, it is difficult to perfectly match the characteristics of the two reproduction systems, and tracking errors may occur due to output errors.

Therefore, it is an object of the present invention to present a tracking method that can correct such differences in the characteristics of the reproduction system and achieve perfect tracking.

[Means to solve the problem]

The tracking method according to the present invention is applicable to a magnetic recording/reproducing device that simultaneously performs recording and reproduction using n (n is an integer of 3 or more) rotary heads. A tracking method in which a tracking signal is recorded with two rotating heads, and when playing back, tracking information is obtained by comparing the crosstalk output from the rotating heads on both sides of the rotating head that recorded the tracking signal. A reference signal is recorded in advance, and during playback, the reference signal is played back by the rotary head for obtaining the above-mentioned crosstalk, and the characteristics of the playback system for both rotations are corrected. It is characterized by eliminating the influence of characteristic differences.

[Effect]

By reproducing the reference signal with a rotary head for obtaining tracking information, it is possible to know the difference in characteristics of the reproduction systems of both rotary heads. Therefore, by correcting the amount of crosstalk according to the amount of characteristic difference, it is possible to obtain tracking information from which the influence of the characteristic difference of the reproduction system has been removed.

Since not only variations in the reproduction system but also changes in characteristics due to changes over time, such as wear of the head, are taken into consideration, it is not affected by changes over time.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 shows a block diagram of an embodiment of the present invention, and FIG. 2 shows a recording pattern of a magnetic tape. In addition, in this example,
A cylinder with a diameter of 621 mm has 4 channels on one side, an azimuth angle of ±10°, a head width of 15 μm, and a head with 4 channels on one side and 8 channels on both sides so that adjacent tracks have reverse azimuth, and the cylinder is operated at 60 rps.
Let us take as an example the case where a 172-inch magnetic tape is wound around 190 degrees and a 1/2 interlace video signal of 30 frames per second is recorded. The four-channel rotary heads are respectively referred to as heads A, B, C, and D, and the fixed head provided in this embodiment is referred to as head E.

Heads A and C1 and heads B and C have the same azimuth angle.

During recording, the beginning part 5 of the trunk of the magnetic tape 50
2, a tracking signal rg with a frequency of 550 KHz is recorded by the head B, and at the same time, a reference signal of about 5.5 KHz is recorded by the fixed head. Since it is a fixed head, the recording area of the reference signal is a linear track 54. In this embodiment, since the reference signal is reproduced by the rotary heads A and C, the azimuth angle of the fixed head E is set to be the same as that of the rotary heads A and C.

During playback, the reference signal recorded by the fixed head E and the tracking signal ft recorded by the rotating head B
is reproduced by rotating heads A and C.

The relative speed between the magnetic tape 50 and the rotating head is 10°6.
Since the tracking signal f2 is at a high speed of m/s, the tracking signal f2 is recorded on the magnetic tape 50 at a long wavelength and can be reproduced without being affected by the azimuth1.Furthermore, the reference signal by the fixed head E is fixed head E and rotating head A,
Due to the speed difference with C, it is played back at 850 KHz.

In FIG. 1, the reproduction output of a magnetic head 10 (head A) is amplified by a reproduction amplifier 12 and applied to a band pass filter (BPF) 14.16. Furthermore, the reproduction output of the magnetic head 18 (head C) is output from the reproduction amplifier 20.
The signal is amplified and applied to the BPF 22°24. BPF1
4.22 is the tracking signal r recorded by head B
The frequency component of t (550 KHz in this example) is extracted and applied to the detection circuit 26.30, and the BPF 16.24 extracts the frequency component of
KHz) frequency components are extracted and applied to the detection circuits 28 and 32.

The sample and hold (S/H) circuits 34 and 38 are located at a location where the head 10 (head A) and the head 18 (head C) are adjacent to the recording area 52 (FIG. 2) of the tracking signal f2 (i.e., the recording area 26 and 30), the detection outputs of the detection circuits 26 and 30 are sampled and held. In addition, the S/H circuits 36 and 40 are configured such that the head 1o (head A) and the head 18 (head C) record a reference signal using a fixed head trunk 54 (see FIG. 2).
When the signal reaches a position where it can be reproduced, the detection outputs of the detection circuits 28 and 32 are sampled and held.

The E circuit 42 converts the hold value of the S/H circuit 34 into an S/H circuit 42.
Divide by the hold value of the H circuit 36. In addition, the division circuit 4
4 divides the hold value of the S/H circuit 38 by the hold value of the S/H circuit 40. By the division circuits 42 and 44,
A normalized amount of crosstalk can be obtained. The division results of the division circuits 42 and 44 are applied to the subtraction circuit 46,
Subtracted.

The output of the subtraction circuit 46 indicates the difference between the amount of crosstalk caused by the head 10 (head A) and the amount of crosstalk caused by the head 18 (head C), that is, the tracking error.

This tracking error signal is supplied from the output terminal 48 to a capstan servo circuit (not shown), and servo control is performed so that the tracking error becomes zero.

It is thought that the reference signal generated by the fixed head width hardly changes between about two head widths, so the difference in output size between the S/H circuit 36 and the same 40 is due to the difference between the outputs of the playback head 10 and the playback amplifier 12. This is thought to be due to the difference in output between the reproduction system consisting of the reproduction head 18 and the reproduction amplifier 20.

Therefore, during reproduction, by correcting the reproduction system based on this signal, tracking accuracy can be improved.

In the above embodiment, the tracking signal is recorded using a time division method, but of course it can also be applied to a case where the tracking signal is recorded using a frequency multiplex method.

FIG. 3 shows a block diagram of another embodiment of the present invention.

The same components as in FIG. 1 are given the same reference numerals. In this modified embodiment, the rotary head A.

Taking advantage of the fact that the tracking signal r2 reproduced by C and the reference signal reproduced from the reference signal track of the fixed head E can be separated in time, the frequencies of both are set to be the same. Therefore, the BPF 16.24 and the detection circuit 28.32 shown in FIG. Furthermore, the S/H circuits 62 and 66 sample and hold the detection outputs of the detection circuits 26 and 30 at the timing when the reference signal is reproduced by the fixed head.

In addition, in order to absorb differences in the characteristics of the reproduction systems, in this modified embodiment, the detection output of the tracking signal f2 is multiplied by the detection output of the other reference signal in the reproduction system of head A and the reproduction system of head C. This eliminates the influence of differences between the two reproduction systems. That is, the multiplier circuit 68 multiplies the output of the S/H circuit 6o by the output of the S/H circuit 66, and the multiplier circuit 70 multiplies the output of the S/H circuit 64 by the output of the S/H circuit 62. There is. The subtraction circuit 46 compares the output of the multiplication circuit 68 and the output of the multiplication circuit 70, and the difference signal is outputted from the output terminal 48.

The above embodiments can basically be realized by analog circuits or digital circuits, and furthermore, by program calculations. Multiplication processing is more advantageous than division processing in that circuit hardware and arithmetic programs can be made smaller and faster.

In the above embodiment, the case where four rotating heads are provided is used as an example, but in general, tracking is performed with one head excluding both ends of a head group consisting of n (n is an integer of 3 or more) rotating heads. A tracking error signal is obtained by recording a signal and comparing the amounts of crosstalk output from two heads adjacent to the head that recorded the tracking signal during playback.

〔Effect of the invention〕

As can be easily understood from the above description, according to the present invention, by reproducing signals of substantially the same size,
Since the sensitivity error of the reproduction system is corrected, the influence of differences in the characteristics of the reproduction system can be removed from the tracking error signal, and therefore,
Stable tracking control that is unaffected by variations in playback system characteristics or changes over time can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a recording pattern of a magnetic tape, and FIG. 3 is a block diagram of a modified embodiment. A, B, C, D; E, 10.18---Magnetic head 14.16.22.24---Band bass filter 34. 36. :lt8. 40. 60
．． 62. 64゜66---Sample/hold circuit 42.44---Division circuit 46---Subtraction circuit 48---Output terminal 50---Magnetic tape 52・
-Tracking signal recording area 54...Reference signal recording track 68.70...-Multiplication circuit

Claims (1)

[Claims] In a magnetic recording and reproducing device that simultaneously performs recording and reproduction using n (n is an integer of 3 or more) rotating heads, a tracking signal is recorded by one rotating head excluding the heads at both ends in a head group consisting of n rotating heads. This tracking method obtains tracking information by comparing the crosstalk output from the rotating heads on both sides of the rotating head that recorded the tracking signal during playback, and the reference signal is recorded using a fixed head during recording. At the time of reproduction, the reference signal is reproduced by the rotary head for obtaining the crosstalk, and the characteristics of the reproduction system of both rotary heads are corrected, thereby eliminating the influence of the difference in characteristics of the reproduction system on the tracking information. A tracking method characterized by: