JPS59198557A - Tracking method of magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain stable control by eliminating a flyback signal superimposed on a regenerated pilot signal in the method conducting tracking control using a pilot signal. CONSTITUTION:The regenerated pilot signal B superimposed with a flyback pulse signal is inputted from a terminal 15. The regenerated pilot signal C where a low frequency energy component of the flyback pulse signal is eliminated is obtained from the output by allowing the signal to pass through a high pass filter 16. A horizontal synchronizing signal B is inputted to a monostable multivibrator 18 triggered by the leading edge. This time constant is set to obtain either a pulse output D equal to the flyback signal in time width superimposed on the regenerated pilot signal, or broader more or less than the flyback signal. An output of the said high pass filter 16 is inputted to a gate circuit 19 and only the high period of the pulse output signal D of a monostable multivibrator 18 is gated, then the regenerated pilot signal E is obtained from the output of the gate circuit 19 and the signal is outputted from a terminal 20.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetic recording and reproducing apparatus (hereinafter referred to as 'I/TR') that uses a rotating head to sequentially record and reproduce signals as inclined discontinuous recording trajectories on a magnetic tape. The present invention relates to a tracking method in -, and particularly relates to a tracking method in a VTR that performs tracking control using a pilot signal.

Configuration of conventional examples and their problems Currently, various methods have been proposed for creating tracking error signals using pilot signals.Here, we will use a four-frequency pilot signal method using four types of pilot signals as an example. Let me explain.

FIG. 1 shows a recorded magnetization trajectory by the four-frequency pilot signal method, and FIG. 2 is a block diagram of a reproducing circuit for obtaining a tracking error signal.

In FIG. 1, AI l BI I A21 B2・
. . . are recording tracks recorded on the magnetic tape by head A and head B, which have different predetermined azimuth angles.

Arrow 1 indicates the scanning direction of the rotary head.

On each recording track, each pilot signal indicated by f1 to f4 is sequentially and repeatedly recorded every 174-/2-do along with the video signal. The recording order of the pilot signals is as shown in FIG. 1, and one type of pilot signal is continuously recorded within one field period. The frequency of the pilot signal is set to a value shown in Table 1, for example.

Table 1 In Table 1, fH indicates the frequency of the horizontal synchronization signal, and 6.5 rH indicates a frequency that is 6.6 times the frequency of the horizontal synchronization signal.

The difference in the same wave number of pilot signals between each recording track is the first
As shown in the figure, fH or 3 t7. The frequency will be . Then, the head is Ai (i=1, 2,...
...) When scanning a track, the frequency difference between the pilot signal of the scanning trunk and the pilot signal recorded in the adjacent track on the right on the paper is always fH, and that on the left is always 3 FU. . The head is Bi
) When scanning a rank, the relationship is opposite to that described above, and the frequency difference of the pilot signal between the scan l rank and the adjacent trunk on the right is always 3 fH, and that on the left is always fH.
It is.

Since the pilot signal is a relatively low-frequency signal in the vicinity of 100 KH2, it is possible to reproduce the pilot signal recorded on the adjacent track as a crosstalk signal without the head scanning the adjacent track.

For example, if the head on-tracks A2 track,
.

The pilot signal obtained when scanning is '3 + f
It is a composite signal of 2+f4, and f3 has the highest level, and then f2+f4 is reproduced at the same level.

When the head slightly deviates from the trunk A2 toward the track B2 side and performs reproduction scanning, the level of the obtained reproduction error signal decreases in the order of f3 + f41 f2.

On the other hand, the level of the special pilot signal when the head shifts to the track B1 side and scans is f3 + f2 + f4
decreases in the order of Therefore, if the difference frequency signals fH and 3rH between the pilot signal on the main scanning trunk and each pilot signal recorded on both adjacent tracks are separated and extracted, and the reproduction levels of both signals are compared,
The amount and direction of head deviation from the main scanning track can be known.

FIG. 2 is a block diagram of a reproducing circuit for obtaining a tracking error signal. In FIG. 2, a reproduced RF signal in which a video signal and a pilot signal are combined is input from a terminal 2. Circuit 3 is a low-pass filter, and the reproduction R
Separate and extract only the Nonoirosoto signal from the F signal.

The pilot signal obtained at this time is a composite signal of the main scanning track and the pilot signals recorded on both adjacent tracks.

The circuit 4 is a balanced modulation circuit, and multiplies the above-mentioned composite signal by the reference signal supplied from the terminal 5.

The reference signal supplied from the terminal 6 is a pilot signal having the same frequency as the pilot signal recorded on the main scanning track. For example, in FIG. 1, when the head performs reproduction scanning on track A2, the input signals to balanced modulation circuit 4 are f21 f3114, and the reference signal supplied from terminal 6 is f3. Therefore, the output signal of the balanced modulation circuit 4 is f2 + f3. Frequency sum and difference signals between each signal of f4 and the signal of f4 are output. Circuit 6 is a tuned amplifier circuit tuned to the fH signal, and circuit 7 is a tuned amplifier circuit tuned to the fH signal.
This is an fH tuned amplifier circuit. Circuits 8 and 9 are detection rectifier circuits, and circuit 1o is a level comparison circuit.

Therefore, each pilot signal taken out as a crosstalk signal from both adjacent tracks is separated and taken out as a difference signal from the pilot signal recorded on the main scanning trunk. A signal corresponding to the difference is extracted. Level comparison circuit 1
For the signal obtained at 0, when the reproduction level of fH is higher than the reproduction level of 3fH, a positive voltage corresponding to the level difference is extracted, and in the opposite case, a negative potential is extracted. Note that the signal obtained by the level comparison circuit 1o includes information on the amount and direction of track 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. 1, the relationship between the direction of head deviation and the crosstalk signal (fH or 3fH) obtained at that time is opposite to each other for the A trunk and the B track.

In FIG. 2, circuit 11 is an analog inversion circuit,
The circuit 12 is an electronic switch that switches according to the period of the head switching signal supplied from the terminal 13. Therefore, for example, when the head reproduces and scans the A track, the output signal of the level comparison circuit 10 is output as is, and when the head reproduces and scans the B track, the output signal of the level comparison circuit 10 is output as an analog signal. is inverted and output.

Therefore, the signal obtained at the terminal 14 is always a positive potential when the head deviates to the right from the track to be scanned, and a negative potential is always output when the head deviates to the left, regardless of the rank.

Therefore, if the signal obtained at the terminal 14 is supplied as a tracking error signal and the tape feeding speed is controlled, the head will always scan on-track on the main scanning track.

The above is an overview of the method for obtaining a tracking error signal using four types of pilot signals.

Now, when a VTR using this tracking method is installed near or inside a television (TV) and played back, the TV's flyback pulse signal (fH same period pulse) is transmitted through the VTR's magnetic head. Since this pulse contains many harmonic components and also has energy in the pilot signal frequency domain, it is largely superimposed on the reproduced pilot signal. As a result, the tracking error signal is disturbed during the period when it is affected by the flybank signal, and the control performance is significantly degraded.

Purpose of the Invention The object of the present invention is to perform out-of-stability control by removing a flybank signal superimposed on a reproduced pilot signal in a tracking control method using a pilot signal recorded superimposed on an information signal. shall be.

Structure of the Invention The present invention records a pilot signal for tracking control during playback by superimposing it on a television signal to be recorded, and during playback, a pilot signal for tracking control during playback is recorded by superimposing it on a television signal to be recorded, and during playback, a pilot signal for tracking control is superimposed on a television signal to be recorded. In a tracking method that controls the relative position between a recording track and a reproduction scanning locus of a reproduction magnetic head using a tracking error signal corresponding to a level difference of a crosstalk signal of a reproduced pilot signal, the reproduced pilot signal is After passing through the bypass filter (HPF), the horizontal synchronizing signal (H
-3YNC) is used to turn off the gate during the period when the flyback signal is superimposed, removing the influence of the flyback signal, and installing the recording/reproducing device near or inside the television receiver. This is a tracking control method that keeps tracking operation stable even when

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention is shown in FIG. 3, and will be explained using the operational waveform diagram of FIG. 4.

A regenerated pilot signal (b) on which a flyback pulse signal is superimposed is input from a terminal 16, and is input to a bypass filter (HPF) 16 whose cutoff frequency is set to a lower frequency than the lowest frequency pilot signal. Ru.

By passing the HPFl 6, a regenerated pilot signal from which the low frequency energy component of the flyback pulse signal has been removed is obtained from the output of the HPFl 6. V
The flyback pulse generated from the TV receiving the TR playback signal is in a synchronous relationship with the horizontal synchronization signal in the VTR playback signal, so this flybank signal is synchronized with the horizontal synchronization signal (H-3YNC ) is synchronized with (b).

H-8YNCj (A) is input to the monostable multi 18 which is triggered by the rising edge. This monostable multi 1
The time constant 8 is set so as to obtain a pulse output that is equal to or somewhat wider than the time width of the flyback signal superimposed on the regenerated pilot signal e→.

The output → of the HPF 16 is input to the gate circuit 19,
The pulse output signal of the monostable multi 17 is gated only during the Hi period.

Therefore, from the output of the gate circuit 19, a reproduced pilot signal (e) which is non-signal can be obtained during the period when the flybank signal is superimposed, and is output from the terminal 20.

By connecting an implementation circuit used in the method of the present invention shown in FIG. 3 between the output of the low-pass filter 3 and the input of the balanced modulation circuit 40 shown in FIG.
Even if the flybank signal from the magnetic head is superimposed on the reproduced pilot signal, the input of the balanced modulation circuit 4 can be supplied with the reproduced pilot signal from which the flyback signal has been completely removed. Even when installed near the aircraft, it is possible to prevent the effects of flyback and <Russ from appearing on the tracking signal.

Effects of the Invention The present invention provides an l-racking method using a pilot signal, in which even if a TV flyback signal is superimposed on a regenerated pilot signal, the flyback signal can be easily removed. Stable control can be performed without being affected.

Further, according to the present invention, it is possible to shorten the superimposition period of the flybank signal in order to pass the tracking error signal superimposed with the flyback signal through the HPF. That is, it has the advantage that the gate period can be shortened.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the recording pattern on the tape of the trunking method using 4-frequency pilot signals, and Figure 2 is a diagram showing the recording pattern on the tape using the 4-frequency pilot signal.
FIG. 3 is a block diagram showing a reproduction processing circuit for a tracking method using a frequency pilot signal; FIG. 3 is a block diagram showing an embodiment of a reproduction pilot signal processing circuit used in the trunking method of the present invention; FIG. ~(The wings are operating waveform diagrams in the circuit of Figure 3. 3...Low pass filter, 4...Equilibrium i
xi, 6.7...tuned amplifier, 8,9...detection rectifier circuit, 10...level comparison circuit, 11.
...Inverting circuit, 12...Electronic switch,
16... Bypass filter, 18... Monostable multi, 19... Gate circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 1?5 Figure 4

Claims (1)

[Claims] A pilot signal for tracking control is superimposed on the video signal to be recorded and sequentially recorded on a magnetic recording medium as an adjacent recording track, and during reproduction, it is reproduced as crosstalk from recording trunks adjacent to the front and back of the recording track to be reproduced. When controlling the relative position between the recording track and the reproducing scanning locus of the reproducing magnetic head using a tracking error signal corresponding to the level difference of the pilot signal, the regenerated pilot signal is extracted by a bandpass filter and A tracking error signal created based on the regenerated pilot signal from which the induced noise synchronized with the regenerated horizontal synchronization signal contained in the regenerated pilot signal is removed by a gate pulse synchronized with the regenerated horizontal synchronization signal, and this induced noise has been removed. A tracking method for a magnetic recording/reproducing device, characterized in that tracking is performed using a magnetic recording/reproducing device.