JPS61261843A - Tracking controller - Google Patents

Abstract

PURPOSE:To reduce the variation of a track control signal and to perform accurate tracking by detecting playback outputs of adjacent tracks and obtaining their difference signal, calculating its mean value, and holding the mean value until next track reproduction and controlling the track scanning position of a head. CONSTITUTION:Playback signals of adjacent tracks 1' and 2' are detected by using a magnetic head 1, whose output is sent to a tracking control circuit 22 which constitutes the main part of this method through an amplifying circuit 10 and a signal separating circuit 11. This circuit 22 consists of a detection control circuit 16, the 1st and the 2nd detecting circuits 13 and 14, a differential circuit 15, a mean value holding circuit 21, and a capstan motor control circuit 18 and the difference signal S13 corresponding to the quantities of breadthwise shifting between the tracks 1' and 2' and magnetic head 1 is applied to the circuit 21 and held until next track reproduction. Then, its output is applied to a capstan motor 19 through the circuit 18 to put the motor 19 in accurate tracking operation.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a tracking control device in a magnetic recording/reproducing device or the like.

2. Description of the Related Art In recent years, audio signal recording and reproducing devices time-compress the audio signal and use Parnu code modulation (Pulnu code modulation) to compress the audio signal.
De Modulation is abbreviated as PGM hereinafter. ), magnetic recording and reproducing apparatuses are being developed that use a rotating head to perform multi-channel recording diagonally on a tape-shaped recording medium in different parts in the width direction of the tape.

In these devices, in order to obtain a good reproduction signal, tracking control is required to control the head to accurately scan the recorded track.

First, an outline of the magnetic recording/reproducing apparatus described above will be described.

FIG. 4 shows a schematic configuration diagram of a tape-shaped recording medium and a head of a magnetic recording/reproducing apparatus.

In FIG. 4, the magnetic heads 1 and 2 are mounted on a rotating cylinder 3 with a positional relationship of approximately 18°, and the rotating cylinder 3 is rotating at a high speed of, for example, 18° per minute. In this case, a winding of 180° or more is wound at an angle, and a winding of about 220°, for example, is wound around the rotary cylinder 3 at an angle while running in the longitudinal direction.

FIG. 6 is a schematic diagram of a signal recording system, and FIG. 6 shows a timing chart of signals recorded in FIG. 5.

In FIG. 6, the audio signal S1 is a temporally continuous signal as shown in FIG.
The GM encoding circuit 6 obtains a PCM encoded signal S2 by time-compressing the signal in the sections A to F into the sections DE. (Signal S2
is shown in FIG. 682. ) The signal S2 is applied to the signal recording circuit 7, and the pilot signal S3 used for the tracking control is applied to the signal recording circuit 7 from the pilot signal generation circuit 8.
and signal S are mixed.

Further, to the signal recording circuit 7, a recording timing control signal S4 synchronized with the rotation of the rotary cylinder 3 as shown in FIG.
' When a recording current is applied to the magnetic head 1 in the section and the magnetic head 1 or 2 scans the section from specific position D to E in the tape width direction of the tape-shaped recording medium 4, the pilot signal S3 and the PCM encoded signal S2 Record.

Every time the rotating cylinder 3 rotates 1800 times, the magnetic throat 1.
This recording is repeated alternately by the magnetic head 2, and as a result, as shown in FIG. Recording is performed continuously in the longitudinal direction of the tape.

Also, by switching the phase of the recording timing control signal S4, it is possible to change the position to another position in the tape width direction, for example, A, -B,
BNC, cNn, E-F, FG (6 of this A-G
Each section is called a channel. Similar recording can be performed in the six sections of ), and a total of six channels of signals can be recorded.

In addition, in FIG. 5, the tracks named 1' and 2' are the magnetic nodes 1 and 2, respectively. Tracks recorded by magnetic head 5.2 are shown.

Further, FIG. 7 shows how the tracks recorded on each channel of A to H are lined up, and is drawn with the horizontal axis as the head scanning locus.

During recording, there is no control to perform writing at a specific position in the longitudinal direction of the tape, so the joints between the channels A to G are uneven as shown in FIG.

A recording method called azimuth recording is used as a recording method, and the magnetic heads 1 and 2 are each attached to a rotating cylinder with an angular difference called an azimuth angle. When a head, for example, track 1' is reproduced with magnetic head 2, or track 2' is reproduced with magnetic throat 1,
With high frequency signals, a loss called azimuth loss occurs and the signal cannot be reproduced, whereas with low frequency signals, this azimuth loss is small, so the signal can be reproduced.

As mentioned above, the PCM encoded signal S2 is a signal modulated at a high frequency and is often reproduced by heads with different azimuth angles. However, the pilot signal S3 is a low frequency signal, so the azimuth loss is small and the azimuth angle is different. It can also be played on heads that are connected.

Further, the magnetic heads 1 and 2 are constructed so that the head width is wider than the track width of the recording track, and performs recording outside the guard band while rewriting a part of the recorded track, which is called solid writing.

Next, an example of a conventional tracking control method for a magnetic recording/reproducing apparatus as described above will be explained.

FIG. 8 is a schematic configuration diagram of a conventional tracking control device 20.

In FIG. 8, the magnetic head 1 scans over the l-rack 1' to obtain a reproduced signal S6, and this signal S6 is amplified by an amplifier circuit 7 to obtain a signal S7 as its output.

This signal S7 is a mixture of a reproduced PGM encoded signal and a reproduced pilot signal, and is separated by the signal separation circuit 11 into a reproduced PCM signal S8 and a reproduced pilot signal S1°.

The reproduced PCM signal S8 is demodulated by the PGM reproduced signal processing circuit 12 to obtain an audio signal S.

Now, in order to obtain a good reproduced audio signal S, it is necessary for the magnetic nozzle 1 to accurately scan the track 1'''2.

FIG. 9 also shows the magnetic head 1 and track 1/track in FIG.
. Even if the centers in the width direction coincide, a part of the head scans the left and right adjacent tracks 2' at the same time.

Since azimuth recording is performed as described above, only the PCM signal recorded on track 1', which is a high frequency signal, is reproduced, but the pilot signal, which is a low frequency signal, is recorded on track 1'. Adjacent tracks 2 on the left and right where not only objects but also a part of the magnetic nod 1 is scanning
At the same time, the <Irosoto signal is also reproduced from ', and a mixture of these is obtained as the pilot signals S and o shown in FIG.

In FIG. 8 or 9, if the widthwise center of the magnetic head 1 deviates from the widthwise center of the track 1',
For example, in the case of a shift to the left, the magnetic head 1 scans the adjacent track on the left side wider and scans the adjacent track on the right side narrower, so that the pilot signal component included in the signal S1o also tracks the adjacent track on the left side. The component reproduced from the track increases, and the component reproduced from the adjacent track on the right decreases. On the other hand, if the signal is shifted to the right, the component reproduced from the adjacent track on the right increases, and the component reproduced from the adjacent track on the left decreases.

If this is not possible, but the frequencies of the pilot signals recorded on the left and right tracks are changed so that the signals can be separated, the levels of the signals reproduced from both adjacent tracks can be detected, and this level difference can be calculated to identify the tracks. The amount of head deviation can be determined.

In FIG. 8, the regenerated pilot signal S,. is added to the first detection circuit 13 and the second detection circuit 14, and in the first detection circuit 13, the adjacent left l in the signals S and o is added to the first detection circuit 13 and the second detection circuit 14.
・Detects the pilot signal component played from the rack,
A signal S11 corresponding to this detected amount is obtained. The second detection circuit 14 detects the piezo1- signal component reproduced from the adjacent right track in the signal S1o, and obtains a signal S12 corresponding to this detected amount. The signal S11 and the signal S1□ are added to the differential circuit 15, and the signal S11 and the signal S
, 2 is obtained.

When the levels of the pilot signals reproduced from the left and right adjacent trunks as shown in FIG. 9 are equal, the voltage of this signal S15 becomes a predetermined voltage Vrθf shown in FIG. 1o.

FIG. 10 shows the signal S13. of FIG. S14. As described above, the seams between channels A to F are uneven, so the level of signal S1 is also uneven depending on the channel to be reproduced.

In FIG. 8, the signal S1. is sample hold circuit 17
The signal ``+5'' is sampled in the ``H'' section of the sampling pulse S14, and the signal S, 5 is held in the next ``H'' section.
As a racking control signal, in addition to the Capnutan motor control circuit 18, the Capnutan motor 19 that drives the tape-shaped recording medium 4 is controlled to perform tracking control.

Problems to be Solved by the Invention Normally, the pilot signal is recorded at a low level so as not to adversely affect other signals, so the S/N ratio of the reproduced pilot signal is poor. circuit 15
The output signal S13 of FIG. 10 also has a poor S/N ratio and even if the same 1-rank is reproduced, As shown in the figure, the result is a signal with superimposed noise.

Therefore, when this is sampled and held, noise superimposed on the sampling point causes fluctuations in the sample and hold signal S15 as shown in FIG. 10, resulting in a problem that tracking control becomes unstable.

In view of the above problems, the present invention provides a tracking control device that stabilizes l-lanogging control by removing the noise superimposed on the signal 813.

In order to solve the problem described in "11.-7 Means for Solving Problems", the tracking control device of the present invention has the following features: detecting the reproduction output of the first signal reproduced from the track, obtaining a difference signal corresponding to the difference between these two reproduction outputs, and calculating the average value of the difference signal during the reproduction period of the track, An average value holding signal is obtained by holding this average value for a period until the next trunk is reproduced, and the track scanning position of the head is controlled based on this average value holding signal.

Effects of the Invention According to the configuration described above, the noise in the difference signal is removed, thereby reducing fluctuations in the signal used for tracking control, thereby making it possible to perform accurate tracking operations.

Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing the configuration of an embodiment of the present invention, and parts similar to those explained in FIG. 8 are designated by the same reference numerals. Also in FIG. 1, a difference signal S13 corresponding to the amount of deviation in the width direction between the track 1' and the magnetic head 1 is obtained as in the conventional example shown in FIG. 8, and this difference signal S13 is applied to the average value holding circuit 21. Note that 22 in the figure is a tracking control circuit which constitutes the main part of the present invention. The average value hold circuit 21 includes, for example, an analog inochi 23. as shown in FIG. It is composed of a resistor aR, a capacitor C, and a buffer amplifier 24.

Further, FIG. 3 is a waveform diagram of each part of the average value hold circuit 21.

In FIG. 2, the signal "13" is applied to one terminal of the analog switch 23, and the opening/closing of the analog switch 23 is controlled by the signal S17.
17 is closed when it is H' and opened when it is L'.

The signal S17 becomes 'H' and closes the analog switch 23 when reproducing the section D to E, and becomes L' and opens in other sections, and as shown in FIG. It becomes 'H' at point D' after passing point D, becomes L' at point E' before reaching point E, and the transient state when the track changes from section C-D to section D-E. , the transient state when switching from the E section to the E to F section track is avoided.

When the analog switch 23 closes, the signal "+3" is connected to the resistor R.
and a smoothing circuit composed of capacitor C,
The average value of the closed section signal S,5 from which noise has been removed is
It is stored in the capacitor C as a signal 81'8, and holds the signal of the capacitor C in the section where the analog switch 23 is open. Signal 81'8 is connected to high input impedance buffer amplifier 24, resulting in buffer 7 amplifier 2
4 is an average value holding signal "+" which holds the average value of the signal S15 in the interval from D' to E' from E' to the next D'.
8 is obtained.

This average value holding signal S18 is applied as a tracking control signal to the capstan motor control circuit 18, and the capstan motor is controlled to perform tracking control.

Signal S18 is the average value 14 obtained by removing noise in signal S13.
I・-.

This allows stable tracking control with no small fluctuations due to the influence of noise.

In addition, in FIGS. 1 and 2, the detection control circuit 1
6 is the first when the magnetic head 1 scans the track 1'- and when the magnetic head 2 scans the track 2'.
This is for switching the detection frequencies of the second detection circuit 13 and the second detection circuit 14.

Effects of the Invention As described above, according to the present invention, it is possible to obtain excellent effects such as reducing fluctuations in signals for performing tracking control and stabilizing 1-racking control.

[Brief Description of the Drawings] Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a block diagram of the average value hold circuit in Fig. 1, and Fig. 3 is a waveform diagram of the second circuit section. , FIG. 4 is a schematic diagram of a recording/reproducing apparatus to which the present invention is applied, FIG. 6 is a schematic diagram of a signal recording system of the recording/reproducing apparatus shown in FIG. 4, and FIG. 6 is a schematic diagram of a signal recording system of the recording/reproducing apparatus shown in FIG. A signal waveform diagram, FIG. 7 shows a pattern 15 showing the locus of a recorded track. FIGS. 7 and 8 are configuration diagrams of a conventional tracking control device, and FIG. A pattern diagram illustrating the relationship, FIG. 1o, is a waveform diagram of the signal shown in FIG. 1.2... Magnetic head, 4... Tape-shaped recording medium, 1', 2'... Track, 21... Average value hold circuit, 22... Tracking control circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person
Ward book

Claims (1)

[Claims] The first signal and the second signal are sequentially diagonally to the longitudinal direction of the tape.
A track on which a signal is recorded, and that track is recorded adjacent to an already formed track in the tape longitudinal direction, and that track is scanned with a head having a head width wider than the width of the recorded track. Then, the reproduction output of the first signal reproduced from the adjacent left track and the reproduction output of the first signal reproduced from the right track are detected, and a difference signal corresponding to the difference between these two reproduction outputs is generated. At the same time, calculate the average value of the difference signal during the reproduction period of the track, obtain an average holding signal that holds this average value for a period until the next track is played, and adjust the head on the basis of this average value holding signal. A tracking control device characterized in that it is configured to control a track scanning position of.