JPS5936358A - Tracking system of magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To ensure stable control, by sampling and holding a tracking error signal obtained from a pilot signal recorded with superposition on an information signal synchronously with a head switching signal and having the relative control between a track and a head locus. CONSTITUTION:A head switching signal (a) is supplied from a terminal 15 to a monostable multivibrator MM16 which is triggered with the rise or fall of the signal (a). A pulse output signal (c) which is synchronous with the signal (a) and has a proper time width is obtained from the output of the MM16. The signal (c) is supplied to an MM17 to obtain a pulse output signal (d) having a comparatively short time width. A tracking error signal (b) having a large variation of level is supplied to a terminal 18 and then supplied to a sampling/ holding circuit 19. The signal (d) is supplied to the circuit 19 to obtain a held output signal (e). The signal (e) has virtually no variation of level and therefore supplied to a capstan motor as a phase error signal. Thus the wow is greatly reduced for a control system.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a tracking method in a magnetic recording/reproducing apparatus (hereinafter referred to as a VTR) that uses a rotating head to sequentially record and reproduce signals as an inclined recording trajectory on a magnetic tape. In particular, there is a tracking method in Vi'H in which a tracking system + alt is performed using a pilot signal.

Conventional configurations and their problems Currently, various methods have been proposed for creating tracking error No. 4i using high lot signals, ranging from one to four types of pilot signals. Regardless of the method used, the tracking error signal that returns 1 will have the same form.

The present invention can be applied to all kinds of methods for creating tracking error signals. Here, an example of a four-frequency pilot signal method using four types of pilot signals will be explained.

Figure 1 shows the recorded magnetization trajectory using the 4-frequency pilot signal method. 7. Figure 2 shows the tracking error signal fr:(l
FIG.

In FIG. 1, A1. B1. A2, . . . are respective recording tracks recorded on the magnetic tape by the head head and the head B, each having a predetermined azimuth angle.

Arrow 1 indicates the scanning direction of the rotation head. In each recording trunk, pilot signals indicated by f1 to f4 are sequentially recorded field by field together with the video signal.

The recording order of pilot signals (is the order shown in Figure 1, and within one field period, one type of pilot signal is recorded continuously. The frequency of the pilot signal is shown in Table 1 for example. set to the value.

(Table 1) In Table 1, fH indicates the frequency of the horizontal synchronization signal, and 6.5 fH indicates a frequency that is 6.5 times the frequency of the horizontal synchronization signal.

The frequency difference of the pilot signal between each recording track is the first
As shown in the figure, the frequency is <s fH or 3f)i. Then, the head is Ai (i:=1.2,...
...) When scanning tracks, the frequency difference between the pilot signal of the scanning track and the pilot signal recorded on the right adjacent track on the paper is always fH, and that on the left ('1. 3f) i. When the head scans the Di) rank, the relationship is opposite to that described above, and the frequency difference of the pilot signal between the running track and the right 4111.1 rank is always 3 fH, and the left 11411 It is fH in the ′′ part ′′.

Pilot Book - Since the bow signal is a relatively low frequency signal around 100 kHz, it is difficult for the head to run on adjacent tracks.
- IIJ can be generated by using the pilot (A) recorded on the adjacent track as a crosstalk signal even without scanning.

For example, the pilot information obtained when the head tracks an A2 track and performs reproduction scanning is f4. f2. f
It is a composite signal of 3, and its level (rif4 is the largest and the second is f2.f3 is the same level. When the head slightly slides from track A2 to the trunk B2 side and scans for reproduction, the reproduction obtained is The level of the pilot signal decreases in the order of f4.f3.f2.Conversely, when the head shifts to the track B1 side and scans, the level of the pilot signal to be received decreases in the order of f4.f2.f3.

The difference signals fH and 3fH-2 between the pilot signal on the second pilot track and the pilot signals recorded on the fifth and second track are taken out.

By comparing the playback levels of both signals, it is possible to determine the head deviation from the main scanning trunk and the direction of the deviation.

FIG. 2 is a block diagram of a reproducing circuit for obtaining a tracking error signal.・In Figure 2.

4. From the 4th child 2, the video signal and the pylon) are synthesized and reproduced RF (the @ signal is input. The circuit 3 is a low-pass filter, and the pilot signal is completely separated from the reproduced) tF times signal. Take it out. The pilot signal used at this time is a composite signal of the main scanning trunk and the pilot signals recorded on both adjacent tracks. Circuit 4 is
This is a balanced modulation circuit, which multiplies the aforementioned composite signal by the reference signal supplied from terminal 5. The reference signal supplied from the terminal 5 is a pilot signal having the same frequency as the pilot signal recorded on the main running eclipse track.

For example, when one head performs reproduction scanning on track A2 in FIG. 1, the input signal to the balanced modulation circuit 4 is f2.
f4. f3, and the reference signal I'L supplied from terminal 5 is f4. Therefore, the output signal of the balanced modulation circuit 4 is f
The sum and difference signals of each signal of ff and the signal 2+49 3 of f4 are output. The circuit 6 is a tuned amplifier circuit tuned to an fH signal, and the circuit 7 is a 3fH tuned amplifier circuit. Circuit 8.9 is a detection rectifier circuit and 1
Circuit 10 is a level comparison circuit.

Therefore, each pilot signal taken out as a crosstalk signal from both adjacent tracks is separated as a difference signal from the pilot signal recorded on the main scanning track, and then sent to the bell comparison circuit 10 after a height of 9. A signal corresponding to the level difference is extracted. The signal obtained by the level comparison circuit 1o has a reproduction level of fH of I of sfH.
When the voltage is higher than the IJ raw level, a potential of 10, 1, and 1,000 volts is taken out according to the level difference, and in the opposite case, a negative potential is taken out. Note that the signal obtained by the level comparison circuit 1Q includes information on the amount of tracking and the direction of deviation of the head, and therefore can be used as a tracking error signal. However, a tracking error signal that is actually suitable for practical use requires further processing. This is because, as is clear from FIG. 4, the relationship between the head displacement direction and the beat signal (fh or 3fH) obtained at that time is opposite to each other for the A track and the B track.

In FIG. 2, circuit 11 is an analog inverting circuit and 1
The circuit 12 is an electronic switch that switches according to the level of the head switching signal 1 supplied from the terminal 13.

Therefore, when the head regenerates and scans the A track, for example, one output signal of the level comparison circuit 10 is outputted to the terminal 14.

When the B track is reproduced and scanned, the output signal of the level comparison circuit 10 is inverted in analog form and output. For this reason, the signal obtained at the terminal 14 is always - regardless of tracks A and B when the head is shifted to the right from the track to be checked, and when the potential of 10 is shifted to full to the left.
The potential is output.

Therefore, the tracking error signal obtained at the terminal 14 is supplied, for example, to the capstan motor as a phase error signal, and the tape feeding speed is determined.
Head d: Always scans on-trunk on the main scanning track.

This is an outline of a method for determining a tracking error signal using the above four types of pilot signals.

However, in VTRs, the trajectory of the rotating head on the tape is somewhat different for each VTR, so
In the method of obtaining the tracking error signal described above, self-recording/reproduction (for example, recording with a VTR A,
There is no problem in the case of compatible playback (for example, recording on a VTR called A and producing on a different VTR from A), as shown in Figure 3, there is no problem with recording (solid line) and playback. (dotted line), if the trajectory drawn by the rotating head is slightly different, the head switching signal - ``JJ
Corresponding to K, the level of the trunking error signal fluctuates by 60I (1υ per Z period) as shown in FIG.

This varying tracking error signal is supplied as a phase error signal to all the CAGstan motors, and the control deviation of the tape feeding speed causes the wah of the 60H7 component to increase in accordance with the magnitude of the fluctuation level of the tracking error signal described above.

Purpose of the Invention The present invention is based on a pylon recorded on an information signal
The level of the tracking error signal changes even if 1 compatibility occurs in the Noj method of performing l-Jinoking ttlJi wholesale using a signal! Eliminate i￥1, stable '+
1ilJ This is for the purpose of performing 1fill.

Structure of the Invention 3 At αH, /C pilot information for tracking control during playback is recorded superimposed on the television signal to be recorded,
During reproduction, a tracking error signal corresponding to the level difference of the crosstalk signal of the pilot signal reproduced from the recording trunks adjacent to the front and rear of the recording track to be reproduced is used to differentiate between the recording track and the reproduction scanning locus of the reproduction magnetic head. In a tracking method that performs relative position control, a sandal hold is performed using the ζrus (II) synchronized with the rise or fall of the tracking error signal, and the recording track and playback are performed using the full hold output information. This is a tracking method for a magnetic recording/reproducing device that controls the relative position of the 6-star head with respect to the reproducing scanning locus.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention is shown in FIG. 5, and will be explained using the operational waveform diagram of FIG. 6.

The head switching signal A is inputted from the terminal 15, and the first monostable multi-node ibrator [M-M
, 116. and.

From the output of the first M-M 16, a pulse output signal having an appropriate time width synchronized with the above-mentioned switching signal A is obtained. The pulse output signal δ of the first M-Mle is triggered by this falling or rising edge. Input into the second stabilizing multivibrator 17, pulse output No. 18 with a relatively shorter time width than the output. 4). terminal 18
In this case, the tracking error signal obtained from the terminal 14 shown in FIG. By inputting the aforementioned pulse output signal 2 of the second M-M 17 as a sampling pulse to the sample and hold circuit 19, a part of the fluctuating level of the tracking signal is sampled, and the held output signal is generated. - E is obtained from the output of the sample and hold circuit 19.

It is obtained from the output of this sample and hold circuit 19. The output signal E has almost no level fluctuation and is supplied to the capstan motor as a phase error signal to control the tape feeding speed.

Also, here we have explained a configuration in which the tracking error signal is sampled at a cycle of 30 Hz, but by adding a monostable multivibrator, all Zanzo ring pulses can be created from the rising and falling edges of the head switching signal mentioned above. It is possible to sample the dragging error signal at a frequency of 60 Hz.

This is an explanation of the configuration and operation of an embodiment of the present invention.

Effects of the Invention With the configuration of the present invention, in a tracking method using one pilot signal, there is almost no level fluctuation in the signal supplied to the capstan motor as a phase error signal even when compatible reproduction occurs. .

Kokichi is able to significantly reduce the wah and the control system becomes female.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the recording pattern of a tape using a tracking method using a 14-frequency pilot signal, and Figure 2 is a block diagram showing the configuration of a reproduction processing circuit for a tracking method using a 4-frequency pilot signal. FIG. 3 is a diagram showing the trajectory of the different moving heads when performing compatible playback, and FIG. 4 is a diagram showing the state of the dragging error signal when performing playback as shown in FIG. 3. @Figure 5 is the 4th
FIG. 6 is a block diagram showing an embodiment of the circuit configuration of the present invention for processing the tracking error signal shown in the figure. FIG. 6 is an operational waveform diagram in the configuration shown in FIG. 3...Lobes filter, 4...Equilibrium adjuster. 6.7... Tuning amplifier IIJ, 8, 9... Tuning/detection rectifier circuit, 10... Level comparison circuit, 11...
...Reverse 11J1 path, 12...Electronic switch, 16,17...Monostable multi-high l/-
19...Sample and hold circuit times fly. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] A pilot signal for tracking control at the time of birth is molded into an image signal to be recorded in a recording assistant, and is recorded as a group of discontinuous recording trajectories on a magnetic tape by a rotating magnetic head. During reproduction, the recording track and the reproduction magnetic head are scanned for reproduction using a tracking error signal corresponding to the level difference of the crosstalk signal of the pilot signal reproduced from the recording track adjacent to the recording track before and after the recording track to be reproduced. This is a tracking method that performs position control relative to the trajectory, and the tracking error signal is sampled and held using a pulse signal synchronized with the rise or fall of a head switching signal. A tracking method for a magnetic recording/reproducing apparatus characterized in that the relative position between a recording track and a reproducing scanning locus of a reproducing magnetic head is controlled by the sample and hold output signal.