JPS58218030A - Recording and reproducing system - Google Patents

Abstract

PURPOSE:To attain high density recording, by reproducing a pilot signal of an adjacent track as a crosstalk for a prescribed period in forming the track, and compensating the shift in head bit by bit for arranging the relative height of the heads. CONSTITUTION:A drum pulse (a) is converted into pulse trains (b) and (c) at a processor 12. A pilot signal generator 13 generates a pilot signal (d) only during b1, b2. A switching circuit 15 interrupts the output of an amplifier 14 only during pulses c1, c2 and the output is recorded alternately at two heads 16. A circuit 17 passes through an input signal during the pulse c1, c2 period and the head 16 reproduces a signal of an adjacent track as a corsstalk signal to pass the signal through the switch circuit 17, and the said signal is extracted from a switch circuit 21. Signals (e), (f) reproduced from the adjacent track during recording of both the heads are included in the said signal. The processor 12 outputs a signal correcting a shift of the heads from the level difference between the signals (e) and (f). A large correcting amount is compensated with the processor 12 in several stages.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording/reproducing method having a head moving mechanism capable of high-density recording. If the pilot signal of an adjacent track is reproduced as crosstalk from the pilot signal recording period of the adjacent track and there is a dropout, etc., the amount of correction is limited and the correction is repeated multiple times in small steps to prevent the head moving mechanism from malfunctioning. An object of the present invention is to provide a recording/reproducing system capable of high-density recording, which has a head moving mechanism that can perform recording with the relative heights of a plurality of heads aligned.

In conventional helical scan type magnetic recording and reproducing devices (hereinafter referred to as "VTR"), the recording track has a curvature unique to the VTR due to variations in the mechanism of the tape running system. The best tracking condition cannot be obtained during compatible playback in which the tape is played back on another VTR. Furthermore, during special playback in which the tape is played back at a different tape running speed than during recording, not only during the above-mentioned compatible playback, but even in the case of so-called self-recording playback where playback is performed using the same VTR used for recording, the recording head is Since the head scan trajectory is different from time to time, it is not possible to accurately scan the recording track, and noise is often generated on the playback screen.

Therefore, conventionally, the head is moved in a direction perpendicular to the longitudinal direction of the recording track (that is, in the track width direction) using, for example, a piezoelectric element.
This method uses a head moving mechanism that has a so-called bimorph plate, in which two sheets of the sducer (sducer) are sandwiched between three electrodes, to move the head so as to eliminate track misalignment and perform more accurate tracking control. was there.

Here, in order to perform the above-mentioned highly accurate tracking control, it is necessary that the track pitch of the recording tracks be recorded at a constant value.

If the track pitch is not recorded at a constant level, especially if the track pitch is narrow and tracks are recorded without a guard band, one of the adjacent tracks may overlap the other and be recorded, or there may be gaps between the tracks. A guard band portion is formed.

In addition, this especially applies to Vs with a bed moving mechanism.
Required by TR. V without head moving mechanism
In the TR, the head is firmly attached and fixed to the rotating body with high precision so that the height position is constant, and the head does not move even slightly in the track width direction during recording mode. This is because, in a VTR having a moving mechanism, the head moving mechanism is easily displaced slightly in the track width direction due to temperature differences, external forces, and the like.

Therefore, in the recording mode, it is necessary to record with a constant track pitch, for example, in a two-head VTR, to align the two relative height positions. Therefore, in the recording mode, the head moving mechanism It is necessary to maintain control so that the relative heights of the heads remain at the same location.

Therefore, conventionally, the above requirements have been met by the method described below with reference to FIGS. 1 to 3.

FIG. 1 shows a track pattern of an example of a conventional recording/reproducing system. In the figure, 1 is the tape width A (for example, 12.7 m
M) is a magnetic tape (cassette tape) which, in the recording mode, is made to run to the right in the figure and has a video width W1 (e.g. 4.69 mm) and a video full width B1 in its lower half.
Video tracks 2a inclined with respect to the longitudinal direction of the tape (for example, 4.85 mm) are recorded and formed alternately by two heads having gaps having different azimuth angles. At the same time, an audio track 3a and a cue track 4a having an audio track width R1 (for example, 0.65 mm) are recorded along the longitudinal direction of the tape. When the above recording is completed, the magnetic tape is then turned upside down and moved to the right in the figure, and recording is performed on the lower half of the tape in the same manner as above, and as a result, the video width W2 (=W1), Video track 2b with full video width B2 (=B1) and audio track width R2 (=R1)
) are recorded into an audio track 3b and a cue track 4b, respectively.

FIG. 2 shows the winding angle of the magnetic tape 1 with respect to the head drum 5. The magnetic tape 1 is wound over an angular range of 186 degrees to record and form video tracks 2a and 2b.

Here, the video track 2a or 2b is a track ta recorded by the first head, as shown in FIG.
Tracks 1, ta2, ta3, . . . and tracks tb1, tb2, tb3, . It is also ta
1, tb, , ta2, tb2, ta3, tb3), each track recorded in the order of
Pilot signal f for detecting track deviation during playback of types
1 (=102.187KHz), f2 (=116,7
86KHz), f4 (=163.500KHz), f
3 (=148.637 KHz), f1, and f2 are recorded continuously on one track and switched for each track.

Furthermore, in each track ta1, tb1, ta2, tb2, and ta3, a pilot signal f5 (for detecting track deviation in recording mode) is applied during a 1.5H period after 15H (H is a horizontal scanning period; the same applies hereinafter) from the beginning of the track. =222.950
KHz) is inserted and recorded. Furthermore, the horizontal synchronizing signal recording positions of each track are recorded in alignment in the width direction of the track (recorded in H alignment), and the recording start position of one track is 1.5 times smaller than the recording start position of the next track.
A track pattern located at a location after H (so-called H deviation number of 1.5H) is recorded and formed.

Therefore, in the recording mode described above, the 1.5H period after recording the pilot signal f5 is set to the reproduction mode, and the pilot signal f5 of the adjacent track (for example, track tb1 when recording track ta2) is reproduced as a crosstalk signal. After that, the composite video signal and f1
- f4 One of the pilot signals for detecting track deviation during reproduction is recorded. the pilot signal f5 reproduced as crosstalk by the first head;
The levels of the pilot signal f5 reproduced as a crosstalk signal by the second head that records the next track are compared, and the head moving mechanism is controlled to adjust the height positions of the first and second heads, respectively. Align to a constant value.

However, in such conventional recording and reproducing methods, there is a period of 1.5 hours in which each field is not recorded, and the loss of the recorded signal during this period may cause vertical synchronization wobble or dropout during reproduction. There was a drawback.

In addition, in the conventional recording and reproducing method described above, the number of fields recorded on one track (usually 1 field)
By narrowing the track pitch and slowing down the tape running speed in order to record and play over a longer period of time without changing the There is a drawback that the reproduction period of the pilot signal f5 as a crosstalk signal becomes short.

For this reason, in conventional recording and playback systems, the slower the tape running speed and the narrower the track pitch, the shorter the playback period of the pilot signal that can be played back as a crosstalk signal, resulting in dropouts and other problems. This has the disadvantage that malfunctions are more likely to occur.

The present invention improves and eliminates the above-mentioned drawbacks, and embodiments thereof will be described with reference to the drawings from FIG. 4 onwards.

FIG. 4 shows a first embodiment of a track pattern according to the present invention. In the figure, ta1', (ta2', ta3' are tracks recorded by the first head, tb1',
tb2' is a track recorded by a second head having a gap with a different azimuth angle from that of the first head;
Records are formed in the order of a1', tb1'ta2', tb2', and ta3' in close proximity without a guard band. Each of the tracks ta1', tb2, ta2', tb2', and ta3' is recorded with an H deviation number of 0.25H, and the shaded area indicates the vertical synchronizing signal recording section.

In addition, each track tal', tb1', ta2', tb
2' and ta3', a pilot signal for detecting track deviation in the recording mode is recorded for a certain period T from the recording start point, for example, for about 1H period. This pilot signal recording section is shown in FIG. 4 as a section with a satin finish.

Also, only during the period when the first head is recording tracks ta1', ta2', or ta3' and the second head scans the area adjacent to the pilot signal recording section of the track recorded immediately before that. , the first head is temporarily placed in a reproduction mode for a very short period of 5 to 10 μs (1/12H to 1/6H) and reproduces the recorded edge pilot signal of the adjacent track as a crosstalk signal for a very short period of time.

Similarly, the second head moves to tracks tb1' and tb2.
′, the second head temporarily scans the area next to the pilot signal recording section of the tracks ta1′ and ta2′ recorded by the first head immediately before that. Short term 5~10μs (1/12H1
/6H) The recording mode is set for a short period of time, and the recorded edge pilot signal of the adjacent track is reproduced as a crosstalk signal for a very short period of time. This pilot signal regeneration section is shown in FIG. 4 by a section marked with parallel lines.

The above pilot signal is a single low-frequency signal with little azimuth loss effect so that it can be easily reproduced as a crosstalk signal from adjacent tracks, and a frequency that can be separated from information signals such as recorded video signals during reproduction. The selection of the frequency to be used will be described in detail later with reference to FIG.

As described above, according to this embodiment, as can be seen from FIG. The sections are recorded so that they are not lined up, and when the head scans next to the pilot signal recording section of the adjacent track, the playback mode is temporarily set for a very short period of time, and the pilot signal of the adjacent track is reproduced as a crosstalk signal. This makes it possible to stably and reliably obtain the crosstalk reproduction signal output of the pilot signal even when recording a track pattern with a small number of H deviations. In other words, it is possible to reduce the time for signal dropouts, and even when recording a track pattern with a narrow track pitch by slowing down the tape running speed as in the case of high-density recording, the pilot can be used as needed in the conventional method. The signal reproduction period does not shorten and change, and a pilot signal reproduction period can always be ensured, although it is short, regardless of the tape running speed.

Next, the signal processing system of the present invention will be explained below with reference to FIGS. 5 and 6.

FIG. 5 shows a block system diagram of an embodiment of the signal processing system according to the seventh type of the present invention. To explain the operation in recording mode,
The composite video signal to be recorded is supplied from an input terminal 8 to a recording processing circuit 9, where it converts a chroma signal into a predetermined signal format suitable for magnetic recording, for example, and superimposes it on an FM luminance signal. After that, the signal is supplied to a mixer 10, where it is mixed with a pilot signal of constant amplitude and constant frequency from a pilot signal generator 13.

This pilot signal is generated as follows. This is because the frequency fp of this pilot signal for recording and tracking has a band that is shared with the low-band converted chroma signal of the so-called color low-band converted recording signal, which is recorded by converting the chroma signal into a low band and superimposing it with the FM luminance signal. (see Figure 7),
Since it was difficult to separate and reproduce the signal and use it accurately as a control signal, in the method of the present invention, the signal shown in FIG. 8(A)
As shown in the figure explaining the color signal recording method of the present invention method, the pilot frequency fp is set lower than the band of the low frequency converted chroma signal (for example, fp=100K).
Hz), or as a frequency between the band of the low frequency converted chroma signal and the band of the FM luminance signal as shown in FIG. 8(B). In either case, the pilot signal and the television information signal, which is the information signal to be recorded, are selected so that they do not share a common frequency band.

Alternatively, as shown in FIG. 8(C), there is no chroma signal during the blanking period, so the side band is narrow and the bandpass filter (BPF) band can be widened, so even if the pilot signal is recorded during the blanking period. good. Furthermore, only the chroma signal near the pilot signal is recorded at a lower level than the chroma signal level in other areas, thereby making reproduction separation easier. With these features, it is possible to clearly distinguish only the crosstalk component of the pilot signal from other recorded television information signals, both in terms of frequency and level, and to facilitate separation and reproduction.

Furthermore, as shown in the graph showing the relationship between tracking error and crosstalk in FIG. 9, the reproduction level of the reproduced crosstalk signal of the pilot signal becomes smaller as the frequency of the pilot recorded signal becomes higher, When increasing the head width, the head width is set to be larger than the track pitch to make it easier to reproduce crosstalk signals.

On the other hand, in the case of a recording/reproducing system having a so-called guard band in which the head width is smaller than the track pitch, the recording frequency of the pilot signal may be set to a lower frequency.

The graph shown in FIG. 9 showing the relationship between tracking error and crosstalk is shown for the case where the head width is 70 μm as an example.

A drum pulse a with one rotation period of the drum as shown in FIG. 6(A) generated by a known method is supplied from an input cap 11 to a processor 12, where a pulse train b as shown in FIG. 6(B) and a drum pulse a as shown in FIG. The pulse train c is converted into a pulse train c shown in (C).

As shown in FIG. 6(B), the pulse train b includes a pulse b1 that rises after the period (T) from the rise of the drum pulse a, and a pulse b2 that rises after the period T has elapsed from the fall of the drum pulse a. Therefore, pulses b1 and b
2 has a pulse width of about 1H. Further, as shown in FIG. 6(C), the pulse train c has a pulse c1 that rises after a period of about (T+1H) has elapsed since the rise of the drum pulse a, and a pulse c1 that rises after a period of approximately (T+1H) has elapsed since the fall of the drum pulse a.
The pulse c2 rises after a period of about 1H), and both of these pulses c1 and c2 have a pulse width of 5
It is selected to be approximately μs to 10 μs (1/12H to 1/6H).

The above pulse train b is supplied to the pilot signal generator 13, which generates a pilot signal of a single frequency fp only during the period of the high-level pulses b1 and b2, as shown by d in FIG. 6(D).

This pilot signal d is mixed with the recording video signal converted into a predetermined signal form as described above in the mixer 10, and then amplified by the recording amplifier 14 and supplied to the switch circuit 15. The switch circuit 15 is supplied with the pulse train c as a switching pulse from the processor 12, and passes the output signal of the recording amplifier 14 during its low level period.
It is configured to cut off the output signal of the recording amplifier 14 only during the high level period (pulse c1%, pulse c2 incoming period).

The recording video signal and pilot signal that have passed through this switch circuit 15 are transferred to the head 16 (actually, the front and side cross sections of a head drum having a head moving mechanism as shown in FIGS. 11 and 12, respectively) via a rotary transformer. As shown in the figure, there are two heads, which alternately record one field at a time), thereby recording on a magnetic tape (not shown). As a result, a track pattern as shown in FIG. 4 described above is recorded on the magnetic tape.

On the other hand, the pulse train c is also supplied as a switching pulse to the switch circuit 17, and the switch circuit 17 is set to a state where the input signal is cut off during the low level period and allows the input signal to pass only during the high level period (pulse c1, c2 incoming period). Control as follows.

Therefore, as described above, during the period when the pulses C1 and C2 are received, the switch circuit 15 is in the input signal cutoff state.
Since the recording video signal and the pilot signal d are not supplied to the head 16, the head 16 operates as a reproducing head during this period and reproduces the recorded green signal of the adjacent track as a crosstalk signal. The signal passed through the switch circuit 17. Here, the above pulse c1 causes the head 16 to operate as a reproducing head.
The periods c2 and c2 are periods in which the head 16 (in this embodiment, the first or second head) is just scanning the area adjacent to the pilot signal recording section of the track recorded immediately before, and therefore, the switch circuit 17, a mixed signal of a recording video signal and a pilot signal reproduced as a crosstalk signal from an adjacent track is taken out.

This mixed signal is amplified to the required level by the preamplifier 18 and then supplied to the reproduction processing circuit 19, while the band is widened so that the band is sufficiently secured, e.g.
KHz bandpass filter (BPF) 20 (Fig. 8 (A)
, when the pilot signal is recorded in the manner shown in (C), it is supplied to a low-pass filter (LPF)), where the pilot signal reproduced as a crosstalk signal is frequency-selected and sent to the switch circuit 21. supplied to

The switch circuit 21 is supplied with the pulse train c as a switching pulse, and is configured to perform the same operation as the switch circuit 17. Therefore, the pilot signal reproduced as a crosstalk signal from the adjacent track in the reproduced signal is extracted from the switch circuit 21 with good S/N only during the input period of the pulses c1 and c2, and the gate pulse c
1. Although the width of c2 is narrow at 5 μs to 10 μs, the band of the bandpass filter (BPF) 20 is sufficiently secured, so the level of the reproduced pilot signal does not decrease much as shown by waveform d in Figure 10 (D). (If the width of the gate pulses c1 and c2 is simply narrowed to 5 μs to 10 μs, the level will become small as shown by waveform c in FIG. 10(C).

Note that FIG. 10 shows the pilot signal reproduction level after passing through the BPF. Figure 10 (A) shows the case where the reproduction pulse width of the conventional method is 80 μs to 95 μs, Figure 10 (B) shows the case where the pulse width is slightly narrower, and Figure 10 (C) shows the case where the pulse width is very narrow. (5 μs to 10 μs) indicates that the playback level is low. Figure 10 (D) shows that even if the pulse width is very narrow, the bandpass filter (
BPF) bandwidth (200KHz to 400KHz)
(This indicates that the reproduction level will be high), and is further supplied to the next stage level detector 22 where it is subjected to envelope detection and then converted into a DC voltage. This level detector 22
The output DC voltage is converted into a digital signal by an A/D converter (converter) 23 according to the level, and is supplied to the processor 12, where it is stored, and
It is compared with the crosstalk regeneration pilot signal level before the track.

That is, the pilot signal extracted from the switch circuit 21 and reproduced as a crosstalk signal includes the pilot signal reproduced from the adjacent track ta1' while the second head is recording a certain track (for example, tb1' in FIG. 4). 6th
The pilot signal f shown in FIG.
There is also a pilot signal e shown in FIG. 3E, which is reproduced from the adjacent track tb1 by the first head which is recording and forming ta2' in the figure. If the level of the pilot signal e is higher than that of the pilot signal f, the relative rate at which the first head scans the previous track recorded by the second head is the same as that of the second head. Therefore, the height position of the first head is relatively lower than the height position of the second head. Conversely, pilot signal f is better than pilot signal e.
When the level is greater than , the height position of the second head is relatively lower than the height position of the first head. Also, the level difference between pilot signals e and f is the first
and the relative deviation amount of the height position of the second head.

Therefore, the processor 12 generates a control signal for correcting the relative height position deviation of the first or second head from the level difference between the DC voltages of the pilot signals e and f, and sends this to the output terminal 24. Then, it is supplied to the bimorph plate of the head moving mechanism shown in FIGS. 10 and 11, and the first or second head is displaced in the track width direction to align the relative height positions of both heads.

Note that which head's crosstalk reproduction signal is the pilot signal taken out from the switch circuit 21 can be determined by the polarity of the drum pulse a.

If the amount of correction of the head 16 by the control signal for correcting the height of the head 16 is a small amount of change less than the predetermined change Rμm, the head is returned to the predetermined height by one correction, but the height of the head is In the case of a large correction amount of Rμm or more, it is divided into several steps and performed in small increments so as to gradually approach the appropriate height. This determination function is performed by the processor 12 described above.

In this way, by making small corrections in multiple steps and gradually approaching the appropriate height, the playback time is extremely short (5 μs to 10 μs) as in the present invention, and the influence of dropout can be minimized in the playback time. This is particularly effective when the head is more easily affected than the conventional example, which has a long length, and this prevents the head from being moved to the wrong position due to a single erroneous control signal.

In this way, in this embodiment, when one recording track is formed, the first head performs a relatively long section (for example, 1H) after a certain period of time from the start of track recording, regardless of the number of H deviations.
After recording the pilot signal together with the video signal for
The second head enters the playback mode for a short period of time, and after a certain period of time from the start of track recording, records a pilot signal for a certain period of about 1H together with the video signal, the second head enters the playback mode for a short time (i.e., the adjacent track recorded by the first head). Since the scanning section (scanning section adjacent to the pilot signal recording section) is repeated, the operation of automatically aligning the height positions of the two heads can be performed stably and reliably.

Note that the reproduction processing circuit 19 converts the reproduction signal into a standard composite color video signal and outputs it to the output terminal 25.

By the way, although the above embodiment has been described assuming that the number of heads 16 is two as shown in FIG. 11, the present invention can of course be applied to a case where there are three or more heads.

FIG. 13 is a track pattern diagram of the second embodiment,
This shows a case where the playback period selected as a very short period is made to coincide with the horizontal synchronization period.

In this case, since the recording gap period is exactly the horizontal synchronization period, there is an advantage that the signal missing portion during reproduction can be actively used as a horizontal synchronization signal.

Of course, the position of the horizontal synchronization signal is selected so that during the reproduction horizontal synchronization period used, the pilot signals recorded in the adjacent previous track are adjacent to each other and the pilot signal can be reproduced as a crosstalk signal.

As described above, the recording/reproducing method according to the present invention involves a certain number of steps when recording and forming a signal recording track by sequentially switching a plurality of heads mounted so as to be movable in the width direction of the signal recording track by a head moving mechanism. A head that is recording one signal recording track continuously records a pilot signal over a certain period for a certain period unique to that head from the start of recording on that track, and the head records one signal recording track that was recorded immediately before. During the scanning period adjacent to the pilot signal recording section of the adjacent signal recording track of the book, the head is temporarily used as a playback head to reproduce the pilot signal of this adjacent signal recording track as a crosstalk signal for a certain period of time. A control signal obtained by detecting and comparing the pilot signal level reproduced for a certain period as a crosstalk signal from each of the plurality of heads when forming the signal recording track of each of the plurality of heads is sent to the bimorph plate of the head moving mechanism. Furthermore, even if the reproduced pilot signal is somewhat missing due to dropout, etc., if the amount of head correction by the control signal is longer than a predetermined length, the amount of correction per time is limited and the amount of correction is reduced in small steps. By repeating the correction multiple times, the height positions of multiple heads are corrected in small increments and gradually aligned automatically.
In particular, the operation of the head placed on the bimorph plate during recording can be made stable and reliable.As explained above, the system of the present invention has a number of features.

[Brief explanation of drawings]

1 and 3 are track patterns and partially enlarged views of an example of a conventional method, respectively. FIG. 2 is a diagram showing the winding angle of a magnetic tape around a rotating body in a conventional method. FIGS. 4 and 13. 5 is a block diagram showing an embodiment of the signal processing system of the present invention, and FIG.
) to (F) are signal waveform diagrams for explaining the operation of FIG. 5, FIG. 7 is a diagram explaining the conventional color signal recording method, and FIG. 8 is a diagram explaining the color signal recording method of the present invention, respectively. Figure 9 is a graph showing the relationship between tracking error and crosstalk, Figure 10 is an explanatory diagram for reproducing crosstalk signals using the method of the present invention, Figures 11 and 12 are graphs showing the relationship between tracking error and crosstalk.
The figures are front and side sectional views of a head drum each having a head moving mechanism. 1... Magnetic tape, 2a, 2b... Video track, 3a, 3b... Audio track, 4a, 4b
... Cue track, 8... Composite video signal input terminal, 11... Drum pulse input terminal, 12... Processor, 13... Pilot signal generator, 15, 17
, 21... switch circuit, 16... head, 20...
・Bass band filter (BPF) for pilot signal filtering,
22... Level detector, 23... A/D converter (converter), 24... Control signal output terminal, 25...
Output terminal, 50... Bimorph board, 51... Bimorph board mounting base, 52... Slip ring, 5
3...Brush, 54...Upper drum, 55...
・Flywheel, 56...lower drum. Patent Applicant: Victor Company of Japan Co., Ltd. (B) (C) Cf さq5i:I ) Fyjt>7”x-rah\.

Claims (1)

[Claims] 1. A head moving mechanism in which a plurality of heads are placed on a bimorph plate made of piezoelectric elements so as to be able to move in the width direction of the signal recording track is used to sequentially switch the plurality of heads to record and form a signal recording track on the tape. On this occasion,
A period during which a head that is recording a certain signal recording track records a pilot signal, and the head scans next to the pilot signal recording section of one adjacent signal recording track that was recorded immediately before. , when forming the signal recording track of each of the plurality of heads, the head is temporarily used as a reproduction head to reproduce the pilot signal recorded in the adjacent signal recording track as a crosstalk signal; If the amount of head correction based on the control signal obtained by comparing the pilot signal levels reproduced as crosstalk signals from each of a plurality of heads after detection is longer than a predetermined length, the amount of correction at one time is limited. A recording/reproducing method characterized in that a control signal is supplied to the bimorph plate of the head moving mechanism so as to repeat correction multiple times in small increments, thereby automatically aligning the height positions of the plurality of heads and performing recording. .