JPS62116084A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To enable a stable fine slow reproduction even in a tracking system using a pilot signal by performing a tracking control using the four types of pilot signals and varying the acceleration in accordance with a voltage value of a tracking error signal obtained in a stop interval during the fine slow reproduction. CONSTITUTION:A sample holding circuit (S & H) 2 samples the tracking error signal (b) by a sample pulse (c) and outputs a hold voltage (d). The pulse (c) is generated in a center position of a change point of an H-S signal (a). In the case of a still scanning, the voltage (d) goes to a Vo potential. In the case of a scanning deviated from the till scanning, the voltage (d) changes according to the quantity of the deviation from the Vo potential. The voltage (d) is inputted to a delay circuit 6 and is used as a signal varying the quantity of a delay according to the voltage value. From a terminal 5, an acceleration position command signal (e) is inputted and impressed to the delay circuit 6 and an output signal of the circuit 6 becomes to an acceleration setting pulse (f). Accordingly, a delay time of the circuit 6 is suitably set corresponding to the direction of the deviation and the automatically stable fine sow reproduction can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is a magnetic recording/reproducing device (hereinafter referred to as VTR) that uses a rotating head to sequentially record and reproduce signals on a magnetic tape as an inclined discontinuous recording trajectory. In particular, the present invention relates to fine throw control in a VTR that performs tracking control using pilot signals.

Conventional technology First, in the conventional tracking method using OTL signals (for example, VH8 system, β system control signals), the magnetic tape is driven intermittently, and the deteriorated portion of the playback output is vertical blanking (V blanking). The so-called fine-slow reproduction, in which still reproduction is performed in a state close to the E37H position and a reproduced image with good E37H is obtained, will be described with reference to FIG.

Now, during the period from to to tl, the capstan motor is controlled to be accelerated, and after the end of the acceleration period, a constant speed period (slower speed than usual) is entered. During this constant speed period, during recording, a CTL signal written in a fixed temporal relationship with the on-track position of the end of the tape and written every frame is detected, and a certain period of time elapses from the time tc when the CTL signal is detected. (Generally, after a slow tracking delay time), the tape is fed at a constant speed until t2, and the capstan motor is braked from t2 to t to enter a deceleration section.Thereafter, the tape is stopped and a still state is entered.

After changing the still state several times depending on the throw ratio,
Once again, the single production mentioned above is being played back in fine slow motion.

FIG. 9 shows the head scanning locus with respect to the track during the fine slow playback.

When entering the acceleration section from the so-called still state ■ in the stop section, the scan shown by ■ was performed, then when the vehicle entered the constant speed section, the scan shown by ■ was performed, and when it entered the deceleration section, the scan shown by ■ was performed. After that, a still state is reached, and the head scanning locus shown by ``■'' is obtained.

The above is the principle of fine slow playback in the conventional tracking method using the CTL signal, and as can be seen from the above, the CTL signal is a reference signal essential for controlling the still stop position.

Next, an overview of a tracking method using four types of pilot signals, which is adopted in 8 mm video that does not use a general GTL signal, will be explained.

During recording, four types of pilot signals f, to f4 are sequentially switched for each field and recorded while being superimposed on the video signal. The recording order of the pilot signals is as shown in FIG. 5 in the order f, -+f2→f5→f4, and one type of pilot signal is continuously recorded within one field period.

The frequency of the pilot signal is set, for example, to the values shown in the table below.

In the table, 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.

Next, we will discuss playback.

Since the pilot signal is a relatively low frequency signal, the pilot signal recorded on an adjacent track is also reproduced as a crosstalk signal.

Now, when the head reproduces and scans the track where the pilot f3 is recorded, the crosstalk causes f2. f'3. The composite signal of f4 is reproduced.

This composite signal and the reference pilot signal (a signal with the same frequency as the pilot signal recorded on the main scanning track)
Balance modulation is performed on the two signals, and the difference frequency signal is extracted.

The difference frequency signals are fH and 3fH signals as shown in FIG. When all the heads scan a track on which a pilot signal of fl+f5 is recorded, the one on the right side is 3 fH.

Also, f2. When the head scans the track on which the pilot signal f'4 is recorded, the left-right relationship is opposite to that described above. fH,3 obtained by this balanced modulation
When the reproduction levels of both rH signals are compared by a full comparison circuit, the compared signals contain information on the amount of track deviation and the direction of deviation. This signal is used as a tracking error signal to control the relative position between the recording track and the reproduction scanning locus of the reproduction magnetic head.

The above is an overview of the tracking method using four types of pilot signals.

Problems to be Solved by the Invention However, even with the above-mentioned tracking method that does not use the GTL signal, there is a problem in performing fine slow playback.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic recording and reproducing apparatus that can perform fine slow reproduction similar to that using an OTL signal even in a tracking method using four types of pilot signals.

Means for Solving the Problems The present invention is configured to control the relative position between the recording track and the reproducing scanning locus of the reproducing magnetic head using four types of pilot signals, and the above-mentioned stop during fine slow reproduction. The present invention is a magnetic recording/reproducing apparatus having means for varying the amount of acceleration according to the voltage value of a tracking error signal obtained in a section.

The action tracking error signal includes information on the amount of track deviation, and by varying the amount of acceleration according to the voltage value of the tracking error signal, the mechanism and Stable fine-throw playback is possible, with tape load compensation possible.

Example First, Figure 6 shows the head scanning trajectory when scanning a track on which four types of pilot signals are recorded when fine slow playback is performed under normal conditions, and the tracking error signal at this time is shown. FIG. 7 shows the operation waveforms of . In order to obtain the tracking error signal shown in FIG. 7, a pilot signal of 7 kra is used for one field during which the head scans in a constant speed section, and fl is used for the other scanning periods.
It is used as the reference pilot signal mentioned above.

Currently, a still scan (2) is being performed on the track where f is recorded. When the vehicle enters the acceleration zone from this state, the scan indicated by ■ is carried out, and then when it enters the constant speed zone, the scan indicated by ■ is carried out. During this scan, the head scans the track on which f2 is recorded, almost on trunk. Next, when entering the deceleration section, the scanning indicated by ``■'' is performed, and the camera stops on the track where f3 is recorded, which is one frame away, and still scanning ``■'' is performed.

After repeating all the still scans, the head scans of ■→■′→■′→■′→■′ are performed again in the same manner as above.
A stealth scan is performed on the track where f, is recorded, and the above operation is repeated.

Note that ■'(■') scans in the constant speed section during fine slow playback between 7 and 7 scans the trunk where f4 is recorded. In Fig. 7, the potential V shown at the center of the tracking error signal represents the potential of the tracking error signal when scanning the center of one track in normal playback, that is, when scanning with on-trunk.

Also, the tracking error signal during fine slow playback scanning from ■→■→C-+■, and ■'-■'-■
The tracking error signal during fine slow reproduction scanning from '-■' is inverted with respect to the Yak reference.

This means that the constant speed section is r4. The other scanning sections are f, because the pilot signal is used as the reference pilot signal, and during scanning from ■→■→■→■ and ■′→■′
During scanning from →■′→■′, on paper, the relationship between the reference pilot signal and the frequency difference between the left and right tracks (fH
and s rH) are reversed.

The above is an explanation of changes in the head scanning locus and tracking error signal when slow-in-slow playback is performed.

A fine-throw reproduction method using a four-frequency pilot system is described in the specification of Patent Application No. 42221 of 1985.

This is the tracking error signal shown in FIG. 7, especially the potential of the tracking error signal obtained when scanning in a constant speed section, that is, V. This method detects the value of vl that changes from , and uses this detection signal to automatically vary the slow tracking delay time to perform fine slow playback, but in reality it stops due to changes in mechanical load and tape load. The position varies as shown in the scanning shown in FIG.

From this state, accelerate to the on-track position of the next track (
When reproducing one area at a constant speed, the reproduction position may deviate significantly from the on-track position, causing noise on the screen.

The present invention detects a change in the potential of a tracking error signal obtained when scanning as shown in FIG. It is something to do.

FIG. 4 shows changes in the tracking error signal when head scanning as shown in FIG. 3 is performed during the stop period.

The scan marked ■ in Fig. 3 shows scanning at the best position in the stop section, but for example, the fH is shifted to the right on the paper (when the head scan shown above is performed, the fH is reproduced from the right side). The crosstalk signal level of 3FU reproduced from the left side is also higher than that of 3FU, and as shown in
Constant potential decreases relatively. Also, it is shifted to the left side on the paper■
When the head scan shown in Fig. 4 is performed, the level of the 3fH crosstalk signal reproduced from the left side is higher than the level of the fH crosstalk signal reproduced from the right side, and the tracking error signal becomes V as shown in Fig. 4. . The potential is relatively high.

The present invention uses the above-mentioned tracking error signal whose potential changes to determine the amount of acceleration when accelerating from a stopped section. Fig. 1 shows a circuit of an embodiment of the invention, and Fig. 2 shows a circuit according to an embodiment of the present invention. The explanation will be given by showing the operation waveform diagram in FIG.

A tracking error signal (b) is input from terminal 1 and applied to sample and hold circuit (S&H) 2.

The H-8W signal (A) is input from the terminal 3 and applied to the sample pulse generation circuit 4.

The tracking error signal (b) applied from the terminal 1 is sampled by the sample pulse (c) obtained from the output of the sample pulse generating circuit 4, and the hold voltage 01ks&H output is obtained.

Further, the sample pulse generating circuit 4 generates all sample pulses (e) at the center of the period from the rising edge to the falling edge and from the falling edge to the rising edge of the H, SW multiplied signal (a). Configure it like this.

The tracking error signal when the head is scanned at the best position in the stop section during scanning (2) is vertically symmetrical with respect to the vo constant potential reference, and the point where the vo constant potential intersects is )I-
This is the center position within the period from the rising edge to the falling edge and from the falling edge to the rising edge of the 5t signal (a).

Therefore, when the head scan in the stop section is ``■'', the potential of the S&H output () becomes the vo constant potential.

In addition, when the head scan is O, which is shifted to the right on the paper compared to when the head scan is ■, the tracking error signal decreases relative to the constant potential as described above, so the output voltage obtained from S&H2) V.

It decreases depending on the amount of potential deviation.

Also, when the head scan is 0, which is shifted to the left on the paper compared to when the head scan is (■), the tracking error signal will be relatively high as mentioned above, so the output voltage obtained from S&H2 will be is v.

It increases depending on the amount of potential deviation.

The output voltage of the S&H circuit 2) is input to the delay circuit 6 and used as a signal for varying the amount of delay according to the voltage value.

An acceleration position command signal (e) for accelerating from a stopped state is inputted from the terminal 5 and applied to the delay circuit 6. The output signal of the delay circuit 6 is led to a terminal 7, from which an acceleration amount setting pulse (to) for determining the acceleration amount is obtained.

Further, this delay circuit 6 provides a pulse output with a delay time T when the head scan is ◎, and a pulse output with a delay time T which is shorter than the delay time T when the head scan is ◎. Pulse output with delay time can be obtained,
During head scanning, T is longer than the delay time T mentioned above.
The configuration is such that a pulse output with a delay time B can be obtained.

Now, scan the head at the best position in the stop section shown in Figure 6.
If the delay time T is set so that the amount of acceleration is sufficient to perform head scanning in the constant speed section near the on-trunk position, the queue will be in the stop section. Even if the head scan becomes (), it will automatically
If the delay amount of the acceleration amount setting pulse (c) is TA shorter than T, the head can be scanned almost near the on-track position during the constant speed section, and the head scan during the stop section can be set to O. Acceleration amount setting pulse (to) automatically even when
If the delay amount is longer than T, then Ta is longer than T, and in the constant speed section, the head can be scanned almost in the vicinity of the on-track position, as described above.

Furthermore, as shown in Fig. 7, the tracking error signals obtained in the head scans ■ and ■' in the stop section have reversed polarities with respect to the Vo potential, but for example, in the trunk where f3 is recorded, The tracking error signal obtained from the side that stops and plays, that is, the head scan
The same processing as described above is possible by performing analog inversion using the potential as a reference. It is also conceivable to use this method to perform fine throw control by varying the acceleration position and deceleration position or the amount of deceleration.

As described in detail, according to the present invention, the conventional C,TL@
Even with a tracking method using a 4-frequency pilot signal that does not use a signal, stable foot-in-slow playback is possible. It is possible to perform fine-slow playback without this occurring.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a processing circuit according to an embodiment of the present invention, Fig. 2 is an operation waveform diagram of the same implementation, Fig. 3 is a head scanning locus diagram during a stop section, and Fig. 4 is similar to Fig. 3. Figure 5 is a recording pattern diagram in a tracking method using a 4-frequency pilot signal, and Figure 6 is a waveform diagram of a tracking error signal when head scanning is performed as shown in Figure 6. 7 is a waveform diagram of a tracking error signal when performing the head scan shown in FIG. 6; FIG. 8 is an explanatory diagram of capstan speed changes during fine slow reproduction; FIG. 9 is a head scanning locus diagram during fine slow playback. 2...Sample hold circuit, 4...Sample pulse generation circuit, 6...Delay circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person
1121 Figure 2 Figure 3 [Yes] j, T 4 Figure 5 f113+s fs Dfg fs 3ts5
S 6 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] During recording, a pilot signal for tracking control during playback is superimposed on the television signal to be recorded, and is sequentially recorded on the magnetic tape as close recording tracks by a rotating magnetic head. The system is configured to control the relative position between the recording track and the reproducing scanning locus of the reproducing magnetic head by detecting a tracking error based on the level difference of the crosstalk signal of the pilot signal reproduced from the front and rear adjacent recording tracks. , and when slow playback scanning is performed by repeating the tape feed speed in the order of stop → acceleration → constant speed → deceleration → stop in the playback mode, the acceleration position or deceleration position is determined according to the tracking error voltage value obtained at the time of stopping. and a magnetic recording/reproducing device characterized by varying the amount of acceleration or deceleration.