JPS6118251B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of recording, for example, a video signal on a recording medium such as a magnetic tape by forming a track with a constant pitch, and reproducing the same. A pilot signal that can be separated from the video signal to be recorded is recorded on every other track of the tracks recorded by the same rotary head together with the video signal to be recorded by a recording rotary head, and during playback, this pilot signal is separated from the video signal to be recorded. The reproducing rotary head always correctly scans each track by using the reproduced output of the signal.

An example of the method of the present invention will be described below.
Let's take the case of playback as an example and explain it with reference to the diagram.

In FIG. 1, 1A and 1B are rotating magnetic heads for recording and reproducing video signals, respectively, and 2 is a rotating magnetic head for erasing. Rotating magnetic heads 1A and 1B for recording and reproducing are mounted at an angular interval of 180 degrees as shown in the figure, and rotated in the direction shown by arrow 3 at a speed of, for example, two fields per revolution. The rotating magnetic head 2 for erasing precedes the head 1A,
And install it in a close position. Then, the magnetic tape 4 is placed against the tape guide drum 5 at a 180-degree angle.
It is wound diagonally over an angular range of .degree., and is run in the direction shown by arrow 6. Therefore, in this case,
Heads 1A and 1B and head 2 have tape 4
scan in a direction tilted by a certain angle with respect to the longitudinal direction of the

Furthermore, the scanning positions of the rotary magnetic head 1A for recording and reproducing and the rotary magnetic head 2 for erasing are set in a fixed relationship, and the head 1A is scanned by a fixed width, for example, 1/2. Attach both heads so that 2 is scanning. That is, if the width of the magnetic gap of head 1A is g _A , one end of the magnetic gap of head 2 in the width direction and one end of the magnetic gap of head 2 in the width direction are shifted by 1/2 g _A. in,
In this example, as shown in FIG. 2, a head 1A is mounted on one end of the bimorph plate 7 in the longitudinal direction as a head height position control means, and a head 2 is mounted on this end with a thickness of 1/2 g _A. It is attached via the plate 8. In this case, the other longitudinal end of the bimorph plate 7 to which the head 1A and the head 2 are not attached is fixed.

Furthermore, the width g _E of the magnetic gap of the rotary head 2 for erasing is the same as that of the head 1 on the tape 4.
When the scanning pitch of A, 1B, and 2 is set to 2p, the following should be satisfied: g _E = 2p + 1/2g _A + α (1) (0<α<1/2g _A ).

Further, the head 1B is configured to scan on the same rotational axis position as the head 1A, and although this head 1B is also not shown, one longitudinal end of the bimorph plate is fixed, and the other longitudinal end thereof is not fixed. Attach to.

By the way, the bimorph plate 7 is formed by pasting together piezoelectric elements 7A and 7B made of barium titanate, and metal electrodes are adhered to the outer surface of the plate 7A and the outer surface of the plate 7B.
By selecting the direction of polarization of the plates 7A and 7B, one plate 7A expands and contracts in its longitudinal direction according to the voltage value applied between the metal electrodes, and the other plate 7B expands and contracts in its longitudinal direction.
expands and contracts in its longitudinal direction in the opposite direction to that of the plate 7A. Therefore, in this case, since the other end of the bimorph plate 7 in the longitudinal direction where the head is not attached is fixed, one end side of the bimorph plate 7 is perpendicular to the surface where the two plates 7A and 7B are pasted together. This moves the head in the width direction of the magnetic gap, ie, in the head height direction, thereby controlling the head height position.

Recording and reproduction are performed using the rotary head device constructed as described above, and the heads 1A and 1B always scan the recording track correctly during reproduction.

First, in recording, as shown in FIG. 3, the heads 1A and 1B pass the video signal onto the tape 4 on diagonal magnetic tracks T _A1 , T _B1 , T _A2 ,
T _B2 , . . . are sequentially formed at a pitch of p and recorded.

At this time, in the present invention, the tracks T _A1 , on which the video signal is recorded by the head 1A,
Among T _A2 , T _A3 ......, every other track T _A1 , T _A3 , T _A5 , ... is indicated by diagonal lines in Fig. 3.
...can be separated from the video signal. For example, a signal having a frequency such as 100 kHz that does not affect the band of the video signal is used as a pilot signal and is recorded together with the video signal by the head 1A.

Next, by using the tape recorded in this manner, the heads 1A and 1B are controlled to always correctly scan over the tracks T _A1 , T _B1 , T _A2 , T _{B2 .} . . during playback. Let me explain the situation using some examples.

FIGS. 4 and 5 are diagrams for explaining an example of this. In this example, a pilot signal is reproduced by the erasing rotating magnetic head 2 and its output is utilized.

That is, as shown in FIG. 4, the reproduced output from the rotating magnetic head 2 is passed through a band pass filter 11 for erasing.
From this, a 100kHz pilot signal is attached, and this is supplied to the peak detector 12.
The peak detection output _SP (FIG. 5B) is obtained, and this peak detection output is supplied to gate circuits 13 and 14.

Reference numeral 10 denotes a pulse generator installed to maintain a constant rotational angle positional relationship with the head 1A. From this pulse generator, when the head 2 comes to the position of the head 1B in FIG. pulses PG _A
(FIG. 5A) is obtained, and the flip-flop circuit 17 is triggered by the rise of this pulse _PGA , and the state of the flip-flop circuit 17 is alternately inverted, and from this, every time the rotary head 2 rotates once, it becomes "0".
Obtain a signal in which the "1" state is inverted.

Also, the output S _P of the peak detector 12 is supplied to the level detector 15, from which the peak detection output S
When _P is below a certain value, an output signal of "1" is obtained, which is supplied to the pulse amplifier 16, and from this, a pulse P _R (Fig. 5C) is obtained at the rising edge of the comparison output. Flip-flop circuit 17
Force a reset.

In this case, the tracks T _A of heads 1A and 1B
₁ , T _A2 ...... and T _B1 , T _B2 ......, and the relationship between the reproduction output of the pilot signal from head 2, we see that for heads 1A and 1B,
In the case of the so-called straight tracking state in which the tracks T _A1 , T _A2 , T _{A3 .} . . and T _B1 , T _B2 , T _B3 . When head 1A is scanning tracks T _A1 , T _A3 , T _A5 . . . on which pilot signals are recorded, head 2 scans tracks T _A1 , T _A
3. In the half-rotation section F _AP of scanning T _A5 , head 2 scans tracks T _A1 , T _A3 , T _A5 . The tracks T _A2 , T
_A4 , T _A6 ...... when the head 2 is in the state of scanning.
In the half-turn interval F _A in which the head 2 scans the tracks T _A2 , T _A4 , T _A6 , the head 2 scans the tracks T _A2 , T _A
4 , T _A6 ...... Scan over the entire width. Therefore, in this case, the output signal S _P (FIG. 5B) from the peak detector 12 obtains an output of E _P in the section F _A , whereas an output of 1/2 E _P is obtained in the section F _AP . It will be done.

Then, the scanning positions of the heads 1A and 1B with respect to the tracks T _A1 , T _A2 . . . and T _B1 , T _B2 . If there is a slight deviation in the direction shown by arrow 40 in FIG.
The value of the peak detection output S _P obtained at _A does not change at E _P , but the peak detection output S obtained at section F _AP
When the value of _P becomes higher than E _P /2 and becomes a value between 1/2 E _P and, on the other hand, the scanning positions of heads 1A and 1B shift slightly in the direction of arrow 41 opposite to the direction of arrow 40, The value of the output S _P obtained in the section F _A is E _P
However, the value of the output S _p obtained in the section F _AP becomes lower than E _P /2.

Therefore, from this, the pulse amplifier 16 obtains a pulse P _R that rises at the time of the rise of the pulse P _A obtained at the start position of the section F _AP , and this forces the flip-flop circuit 17. is reset, the first output S _F (FIG. 5D) of the flip-flop circuit 17 becomes "0" during the period L P of one rotation including the section F _AP , and during the period L _P of one rotation excluding the section F AP. "1" in period L
The second output _F (Fig. 5E) is the inverse of that.

Note that in the half-rotation period F _B in which the head 2 does not come into contact with the tape 4, the output of the detector 12 is "0".

Then, the rise of the first output S _F of the flip-flop circuit 17 triggers the monostable multivibrator 18, and the rise of the second output _F triggers the monostable multivibrator 19, respectively.
And, from the monostable multivibrator 18,
A signal S _M1 (FIG. 5F) which becomes "1" in the interval F _A is obtained and is supplied to the gate circuit 13, thereby _the output S _{K (} 5H) is supplied to the delay circuit 20, delayed by one revolution of the head 2 (corresponding to one frame of the video signal), and this delayed signal is supplied to the level comparator 21.

On the other hand, from monostable multivibrator 19,
A signal S _M2 (FIG. 5G) which becomes "1" in the interval F _AP is obtained, and this is supplied to the gate circuit 14, from which _{the output S V ( the} 5 I) and supply it to the multiplier 22 to generate a signal S _2V with twice the level.
(FIG. 5J) is obtained and supplied to the comparator 21.

Then, the comparison output voltage of the comparator 21 is supplied between the metal electrodes of the bimorph plate 7 on which the heads 1A and 2 are attached, and the comparison output voltage is also supplied to the delay circuit 23, which outputs the output voltage of each head. /2
The signal is delayed by a period corresponding to the rotation, ie, one field of the video signal, and this delayed signal is supplied between the metal electrodes of the bimorph plate 24 on which the head 1B is mounted.

In this case, as mentioned above, heads 1A and 1
If B is in the just tracking state, the level of the signal S _K obtained from the gate circuit 13 is E _P
Then, the level of the signal S _V obtained from the gate circuit 14 becomes 1/2 E _P , and therefore the level of the output from the multiplier 22 becomes E _P . Therefore, the output voltage of the comparator 21 becomes zero, and the heads 1A, 1B and 2 continue to rotate and scan each track correctly.

When the heads 1A and 1B are out of the just tracking state, the gate circuit 1
The level of the signal S _V obtained from 4 is higher or lower than 1/2 E _P as described above.

The head 1A is shifted in the direction of arrow 40, and the signal S
When the level of _V becomes higher than 1/2E _P ,
The output of the multiplier 22 becomes higher than E _P , and at this time, the level of the signal from the delay circuit 20 is E _P , so the comparator 21 obtains a positive DC voltage corresponding to the difference, and this is the bimorph The head 1A is supplied between the metal electrodes of the plate 7, thereby moving the head 1A in the direction of arrow 41 in FIG. 3, so that the head 1A is in a straight tracking state.

The output voltage of the comparator 21 is also applied to the delay circuit 23.
Therefore, the head 1B is supplied between the metal electrodes of the bimorph plate 24 during the period when it is in contact with the tape 4, and the head 1B is thereby moved in the same manner as the head 1A.
is also placed in the just tracking state.

When head 1A shifts in the direction of arrow 41 and the level of signal S _V becomes lower than 1/2E _P ,
The output of the multiplier 22 becomes lower than E _P and since the level of the signal from the delay circuit 20 is constant at E _P at this time, the comparator 21 outputs a negative voltage corresponding to the difference. This is supplied between the metal electrodes of the bimorph plate 7 and the bimorph plate 24, which is delayed by 1/2 rotation, so that each head 1A, 2, and 1B moves in the direction of the arrow 40 in FIG. Moved to head 1A class and 1
B is brought into a just tracking state.

In this case, when the heads 1A and 1B deviate greatly from the scanning position on each track and the level of the signal S _K from the gate circuit 13 becomes lower than E _P , the signal S _V from the gate circuit 14
The level E _P becomes, which is twice the size,
Since the level of the signal S _K from the gate circuit 13 is compared, the output of the comparator 21 becomes large, and each head 1A, 1B, and 2 moves accordingly, and the level of the signal S _K from the gate circuit 13 becomes E _P Then, as described above, each head 1 and 1B enters the just tracking state.

In this example, instead of comparing the level of the output signal S _V of the gate circuit 14 with the output signal S _K of the gate circuit 13, a constant reference voltage E _P is used in the interval F _AP .
It may be configured to compare with.

Also, during recording, head 1B causes head 1A to
A signal with a frequency different from that of the pilot signal recorded in the head 1B is recorded on every other track formed by this head 1B, and a signal for reproducing the pilot signal is recorded in the same manner as in heads 1A and 2 for this head 1B. A separate erasing rotary head is provided,
If this other erasing rotary head and head 1B are mounted on the same bimorph board, head 1
B can also be independently tracked.

Figures 6 to 8 show other examples in which not only the reproducing output of the pilot signal from head 2 but also the reproduction output of the pilot signal from head 1A is performed.
This is an example in which the reproduced output of the pilot signal is also used.

That is, as shown in FIG. 6, the reproduced output of the head 1A is supplied to the bandpass filter 25, from which a 100kHz pilot signal is obtained, which is supplied to the peak detector 26, and its detected output S _A ( 7th
C) is supplied to the gate circuit 27, and the peak detection output _SP (FIG. 7B) of the pilot signal being reproduced from the head 2 from the peak detector 12 is supplied to the gate circuit 28.

Then, the signal S _M2 (FIG. 7E) obtained by supplying the second output _F (FIG. 7D) of the flip-flop circuit 17 to the monostable multivibrator 19 is supplied to the gate circuits 27 and 28. Section F
The output S _AP (FIG. 7F) of the detector 12 at _AP and the output S _V (FIG. 7 G) of the detector 26 are obtained, and these outputs S _AP and S _V are supplied to the comparator 29 for level comparison. .

A delay circuit 31 supplies the output of the comparator 29 to one input 30A of the switch circuit 30 and delays it by the time equivalent to one rotation of the head.
On the other hand, the output _F of the flip-flop circuit 17 is supplied to the switch circuit 30, so that the switch circuit 30 is connected to the input terminals 30A and 30B in the interval L _P and the interval L.
0B and 0B alternately.

Then, the voltage obtained at the switch circuit 30 is applied to the bimorph board 7 on which the heads 1A and 2 are attached.
1/2 of the head.
The signal is supplied between the metal electrodes of the bimorph plate 24 on which the head 1B is mounted through a delay circuit 23 which delays the signal by the time of each batch.

In this case, the tracks T _A of heads 1A and 1B
The relationship between the scanning positions of ₁ , T _A2 , T _B1 , T _B2 , and the peak detection outputs S _A and S _P of the pilot signals from heads 1A and 2 is as shown in FIG. be done.

In FIG. 8, the solid line shows the change in the output S V obtained in the section F _AP of the output S _P from the detector 12, and the broken line shows the change in the output S _V obtained in the section F _AP of the output S _A from the detector 26 _. In the straight tracking state, head 1A scans over the entire width of tracks T _A1 , T _A3 , T _A5 , and head 2 scans over the entire width of tracks T _A1 , T _A3 , T _A5 ……
However, the peak detection output of the reproduced pilot signal is the same as that of the detectors 12 and 2.
The outputs of 6 are made equal to 1/2E _P.

Therefore, at this time, the output of comparator 29 is zero, and heads 1A and 1B maintain their scanning state.

When the scanning position of the head 1A shifts in the direction shown by the arrow 40 _{in FIG .}
The output S _V of the detector 26 will be greater than 1/2E _P , while the output S _AP of the detector 26 will be less than 1/2E _P. Therefore, the comparator 29 obtains, for example, a positive voltage of the difference between the two outputs in this section F _AP .

At this time, since the switch circuit 30 is switched to the input terminal 30A side, this positive voltage is supplied to the bimorph plate 7, and the head 1A is moved in the direction shown by the arrow 41 in the section F _AP , F _AP is set to just tracking state. In addition, in the section F _B after this section F _AP , the head 1A comes into contact with the tape 4, and at this time, the head 1A is delayed by 1/2 rotation by the delay circuit 23.
The same voltage as that applied to A is obtained and is applied to the bimorph plate 24 so that in the section F _B head 1B is moved in the same way as head 1A and is in a state of just tracking.

During the next period L of one revolution, no pilot signal is output from the head 1A, and since the gate circuits 27 and 28 are off, the output of the comparator 29 is zero. At this time, the switch circuit 30
is switched to the input terminal 30B side, and the comparative output voltage obtained in the interval F _AP one rotation before from the delay circuit 31 is obtained from this switch circuit 30, and this is supplied to the bimorph plates 7 and 24. As a result, the scanning state of the heads 1A and 1B is controlled in the same manner as one rotation.

When the head 1A shifts in the direction of arrow 41 _{in FIG .}
As is clear from the figure, the output S _V of the detector 12 and the output S _AP of the detector 26 are both smaller than 1/2E _P , but the output S _V is smaller than the output S _AP .
The comparator 29 obtains the difference, for example, a negative voltage.

Then, this is supplied to each bimorph plate 7 and 24 in the same manner as in the above case, and the head 1A is
and 1B are moved in the direction of the arrow 40 to the section where they are in contact with the tape 4, respectively, so that they are always in a straight tracking state.

According to the example in Fig. 6, the reproduced output of the pilot signal can be compared at the same time, so the phase delay is smaller than when comparing the delayed signal as in the example in Fig. 4. This has the advantage that the response frequency becomes faster.

As described above, according to the method of the present invention, at the time of recording, the recording method of the pilot signal is devised, and the pilot signal is reproduced by another head installed in a predetermined relationship with the reproduction head. By using the output, each playback head can be automatically controlled to always scan correctly over each track.

In addition, since a rotating magnetic head for erasing is used as a special head for reproducing pilot signals,
In particular, there is no need to provide a separate head, and the apparatus used in the method of the present invention has the advantage of being inexpensive.

Furthermore, the method of the present invention is applicable not only to the case where a guard band is provided and information signals are recorded as diagonal tracks, as in the example shown in the figure, but also to the case where adjacent tracks are formed and recorded without providing a guard band. It can also be applied to recording by forming tracks in the width direction of the tape, which is substantially perpendicular to the longitudinal direction of the tape.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a rotary head device used in the method of the present invention, FIG. 2 is a diagram showing an example of the mounting state of the head, FIG. 3 is a diagram showing an example of a recording pattern by the method of the present invention, and FIG. The figure is a system diagram of an example of a control system during the regeneration, FIG. 5 is a diagram for explaining the same, FIG. 6 is a system diagram of another example of the control system during the regeneration, and FIGS. 7 and 8 is a diagram for explaining the same. 1A and 1B are rotating magnetic heads for recording and reproduction; 2
4 is a tape, 7 and 24 are bimorph plates, 11 and 25 are band pass filters, 12 and 26 are peak detectors, and 21 and 29 are level comparators.

Claims (1)

[Claims] 1. First and second rotary heads for recording and reproducing that record and reproduce information signals on a recording medium, and a rotary head for recording and reproducing that is close to the first rotary head for recording and reproducing and that is is provided with a rotating head for erasing information signals and reproducing pilot signals, which is mounted at a position shifted by a certain distance in the width direction of the gap,
The first recording/reproducing rotary head and the information signal erasing/pilot signal reproducing rotary head are disposed on a common head height position control means, and when recording an information signal, the first recording/reproducing rotary head is arranged on a common head height position control means. One of the information signal recording tracks to be formed by the reproducing rotary head.
A pilot signal, which can be separated from the information signal, is recorded on every other track over almost the entire length of the track, and upon reproduction, the pilot signal is reproduced by the rotary head for reproducing the pilot signal, and the pilot signal is reproduced by the rotary head for reproducing the pilot signal. The level of the reproduction output is detected by a level detection circuit, and the detected output is supplied to the head height position control means, thereby controlling the relative scanning position of the recording and reproduction rotary head with respect to the information signal recording track. A signal recording and reproducing method that controls almost the entire length of the signal.