JPS589496B2 - Shingo Noki Rokusai Seihouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recording, for example, a video signal by forming tracks with a constant pitch on a recording medium such as a magnetic tape using a rotating head, and reproducing it from the track. A rotary head separate from the rotary head is used to record a pilot signal, and the reproducing output of this pilot signal is used during playback so that the reproducing rotary head always correctly scans each track. .

Hereinafter, an example of the method of the present invention and a case where a video signal is recorded and reproduced and an erasing rotary head is used as a pilot signal recording and reproducing rotary head will be explained with reference to the drawings.

In FIG. 1, 1A and 1B are rotary magnetic heads for recording and reproducing, and 2 is a rotary magnetic head for erasing. Heads 1A and 1B are installed at an angular interval of 180° as shown in the figure, and head 2 is a rotary magnetic head for erasing. Install it before 1A.

Then, the magnetic tape 3 is wound around the tape guide drum 4 over an angular range that is larger than 180° by the angular interval between the heads 1A and 2, for example in its width direction, and is wound in the direction of the rotation axis of the heads 1A, 1B and 20. let it run,
The heads 1A and 1B are rotated in the direction shown by the arrow 5 at a speed of one rotation every two fields, for example.

Therefore, the heads 1A and 1B scan the tape 3 substantially in its width direction, that is, in a direction substantially perpendicular to its longitudinal direction.

In this example, the scanning width of the erasing rotary head 2 is twice the scanning pitch on the tape 3, and the gap is tilted somewhat with respect to the direction perpendicular to the scanning direction.

In recording, as shown in FIG.
B is formed and recorded, and the head 1 at one end of the tape 3
A pilot signal is recorded by the head 2 at the winding portion corresponding to the angular interval between A and the head 2.

Figure 3 shows an example of how to record this pilot signal.
An oscillation signal from the erasing signal oscillator 6 is supplied to the erasing rotary head 2 through the synthesizer 7, and a signal is generated from the pulse generator 8 when the head 2 comes to a predetermined position in front of the position of the head 1A in FIG. PG1 and this signal PG
1 triggers the monostable multivibrator 9 for delay, and the signal from this triggers the monostable multivibrator 10, which causes the head 2 to move from the position of the head 1A to the position of the head 2 in FIG. A pulse signal is obtained at a predetermined position in between, and this pulse signal is supplied to the head 2 via a synthesizer 7 as a pilot signal.

Therefore, a pilot signal is recorded by the head 2 in the winding portion corresponding to the angular interval between the head 1A and the head 2 at the end of the tape 3.

In this case, the scanning width of the head 2 is twice the scanning pitch, so the pilot signal is the solid line P in FIG.
As shown by t, the recording traces are recorded one after another with a portion equal to the scanning pitch remaining, and since the gap of the head 2 is inclined with respect to the scanning direction, the recording traces are separated.

Looking at the relationship between the scanning positions of heads 1A and 1B with respect to tracks TA and TB during reproduction, the scanning position of head 2 with respect to the recording trace Pt of the pilot signal, and the reproduction output level of the pilot signal from this, it is found that one head 1B correctly scans each track TA and TB as shown by the solid line HAzHB in FIG.
As shown in FIG. 5A, two pilot signals having the same level LM are obtained at slightly different times as shown in FIG. 5A.

On the other hand, the scanning positions of each head 1A and 1B are shifted, and the second
As shown by HA' and HB' in the figure, when scanning at a position advanced from the correct scanning position, three recording traces Pt are scanned, and as shown in FIG. pilot signals are obtained, and their level is greater than LM/2 on the 1st day and smaller than LM on the 1st day.
The th is equal to LM and the 3rd is less than LM/2.

In addition, when the heads 1A and 1B scan at positions delayed from the correct positions, as shown by HA'' and HB'' in FIG. In this case, as shown in FIG. It becomes smaller than LM.

Therefore, if the rotation of each head 1A and 1B and the running of the tape 30 are controlled so that two pilot signals of the same level are always obtained for each rotation, heads 1A and 1B
The tape 3 is always scanned at the correct position, and the video signal can be reproduced at the maximum level without causing crosstalk.

FIG. 4 shows an example of the control circuit for erasing rotary head 2.
The extracted pilot signal is supplied to a limiter 12 via a regenerative amplifier 11 to remove signals with a level below LM/2, and the signal SL from this limiter 12 is supplied to a peak hold circuit 13 to hold its peak value. is held, and the signal SH from the peak hold circuit 13 is supplied to the clamp circuit 14. On the other hand, the signal SL from the limiter 12 is supplied to a clamp signal forming circuit, for example, a flip-flop circuit 15, and the first signal of the signal SL is This is set by the second signal, and the clamp signal Cs is obtained from this, and this signal Cs is supplied to the clamp circuit 14 to clamp the level of the signal sH to zero during the clamp period.

Then, the signal Sc from the clamp circuit 14 is supplied to the low-pass filter 6, and the rotation of the heads 1A and 1B or the running of the tape 30 is controlled by the output signal obtained from this.

Therefore, since the levels of the two pilot signals that are just in contact are both LM, the output signal of the peak hold circuit 13 always has a magnitude of LM, and the signal Sc obtained from the clamp circuit 14
becomes zero as shown in FIG. 5B, and the output of the low-pass filter 6 becomes zero.

If the heads 1A and 1B are shifted and a signal as shown in FIG. 5C is obtained from the head 2, the signal sL from the limiter 12 will be higher than the level of the first signal as shown in FIG. 5D. The signal becomes small, so peak hold circuit 1
The signal sH from the clamp circuit 14 becomes as shown in FIG. 5E, the signal Sc from the clamp circuit 14 becomes as shown in FIG. 5F, and a positive DC output of the level LC1 is obtained from the low-pass filter 16.

When heads 1A and 1B are delayed and a signal as shown in FIG. 5G is obtained from head 2, the signal SL from limiter 12 is at the level of the second signal as shown in FIG. 5H. Therefore, the signal SH from the beer hold circuit 13 becomes as shown in FIG.
The signal Sc from the clamp circuit 14 becomes as shown in FIG. 5J, and a negative DC output at a level of LC2 is obtained from the low-pass filter 16.

Therefore, by controlling the output of the low-pass filter 16 to be zero, the heads 1A and 1B can always be scanned at the correct position.

As described above, according to the present invention, by recording and reproducing pilot signals using a rotary head with a wide gap other than the rotary head for recording and reproducing, for example, a rotary head for erasing, the rotary head for recording and reproducing is always rotated. The head can be correctly scanned over each track.

Furthermore, according to the method of the present invention, the control output is not obtained by phase comparison of the regenerated pilot signals, but is obtained by the level difference of the regenerated pilot signals, and therefore is not affected by jitter at all. .

Furthermore, since the method of the present invention records and reproduces pilot signals using a rotary head, it has the advantage that it can be applied to cases where the running speed of the tape is slowed down.

Furthermore, if the erasing rotary head is used as the rotary head for recording and reproducing the pilot signal as in the above example, there is no need to provide a separate rotary head.

Note that even when three recording/reproducing heads are installed at angular intervals of 120° and a separate rotating head is attached, the recording/reproducing rotary head is rotated at a speed of, for example, one rotation in three fields. The same can be done.

The present invention can also be applied to the case where recording and reproduction are performed by running a tape wound diagonally around a guide drum and scanning the head in a direction slightly inclined with respect to the longitudinal direction of the tape.

In this case, the gap of the rotary head for recording and reproducing pilot signals may be in a direction perpendicular to the scanning direction.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an example of the arrangement of the rotary head used in the method of the present invention, Fig. 2 is a diagram for explaining the recording pattern on the tape and the scanning state during playback, and Fig. 3 is a diagram of the pilot signal. FIG. 4 is a system diagram of an example of a recording system, FIG. 4 is a system diagram of an example of a control circuit, and FIG. 5 is a waveform diagram for explaining the system. 1A and 1B are circuit heads for recording and reproduction, 2 is a rotary head for erasing, 3 is a tape, and 4 is a guide drum.

Claims (1)

[Claims] 1. Another rotary head is provided preceding the recording rotary head, and when this other rotary head scans a specific position in the width direction of the recording medium, this other rotary head sends a constant pilot signal to the remaining recording width. During reproduction, the recording pattern is sequentially recorded so as to be smaller than the scanning width of another rotary head and tilted with respect to the direction perpendicular to the scanning direction.
The pilot signal is transmitted by the another rotary head.
A plurality of recording patterns are sequentially reproduced per revolution at times when they are shifted by an amount corresponding to the above-mentioned tilted recording pattern, and a control voltage calculated from the magnitude relationship of each level and the time relationship of the magnitude is obtained, and this control voltage is used for reproduction. A signal recording and reproducing method for controlling the rotation of a rotary head or the running of the recording medium.