JPH06349161A - Device for tracking vtr - Google Patents

Abstract

PURPOSE:To control a head position for track bends optimally by using tracking error signals on plural positions of a track subjected to sample-and-hold in an approach run interval at the time of recording sound post-recording and performing tracking control. CONSTITUTION:In the approach run interval, a switch circuit 18 is turned on, and the switch circuit 22 is set to a 22A side. By the tracking error signals of both channels A, B from a comparator 6, a synthesis tracking error signal averaging the whole tracks is outputted through sample-hold circuits 8A-8C, 9A-9C, averaging circuits 11, 12, multiplier circuit 13, 14 and an adder 16 respectively. Further, the synthesis tracking error signal in an ITI area is processed by an operation circuit 17, and an obtained weighting coefficient alpha1 is stored in a memory 19. In the sound post-recording interval, the circuit 22 is set to a 22B side, by the tracking error signal in the ITI area of both channels A, B, the synthesis tracking error signal is provided through the circuits 10A, 10B, the circuits 20A, 20B and the circuit 21. At this time, the alpha1 is used as the weighting coefficient in the circuit 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a VTR tracking device suitable for use in a digital VTR which compresses a digital video signal and records it on a magnetic tape by a rotary head.

[0002]

2. Description of the Related Art A digital video signal is DCT-converted,
A digital VTR that is compressed by variable length coding and recorded on a magnetic tape by a rotary head is under development. A track of such a digital VTR is shown in FIG.
As shown in FIG. 3, an ITI area, an audio area, a video area, and a subcode area are provided at the head of the track in the order in which the heads abut. For example, one frame of an NTSC video signal is recorded on 10 such tracks.

A sync, an ATF pilot signal, ID data and the like are recorded in the ITI area. As the ID data, a flag (SP / LP) indicating the distinction between the SP mode in which the recording time is short and the LP mode in which the recording time is long, and data indicating the discrimination between video audio and subcode are recorded. In the audio recording area, uncompressed audio data is recorded as it is when high-quality audio reproduction is required. In the video area, a DCT-converted, variable-length coded, and compressed digital video signal is recorded. Also, a digital audio signal compressed by DPCM is recorded. In the sub-code area, data necessary for high-speed access, time code, and other data associated with digital video signals and digital audio signals recorded in the video recording area and audio recording area are recorded.

[0004]

In such a digital VTR, an ATF is used by using a low frequency pilot signal.
Tracking control is being performed. Then, in the case of after-recording video and audio with such a digital VTR, the head is traced along the recorded track, and new video data and audio data are overwritten on the recorded track. During post-recording, ATF tracking control is performed only in the ITI area near the beginning of the track. For this reason, a so-called track bending may occur in which the post-recorded track is bent with respect to the original track. This track bending is relatively caused by the linearity of the track of the device that formed the original track and the linearity of the track of the device that post-records.
When such a track bend is large, as shown in FIG. 34, the subcode may not follow the extension of the post-recorded track, and the subcode may not be picked up.

Further, in consideration of the processing accuracy of the head, the head width is usually wider than the track pitch.
For example, while the track pitch Tp is 10 μm,
The head width Tw is 13 μm. Therefore, when the head is scanned along the track center of the recorded track during dubbing, a tracking problem arises.
To improve the tracking problem, it is necessary to shift the track so that the edge of the previously recorded track and the edge of the new track formed by post-recording match. However, when the edge of the previously recorded track and the edge of the new track formed by the post-recording are matched, the new track formed by the post-recording largely protrudes from the adjacent previously recorded track,
Affects adjacent previously recorded tracks.

Therefore, an object of the present invention is to provide a VTR tracking device capable of optimally controlling the head position with respect to track bending.

Another object of the present invention is to provide a VTR tracking device capable of optimal track shift according to the relationship between the head width and the track pitch.

[0008]

SUMMARY OF THE INVENTION According to a first aspect of the present invention, in a VTR tracking device in which tracking control is performed using a pilot signal recorded in a track, a plurality of tracks are recorded in a run-up period before post-recording. Tracking control of the VTR, wherein the tracking error signal is sampled and held at the position, and tracking control is performed by using the tracking error signals at a plurality of positions of the track sampled and held during the run-up period during post-recording. It is a device.

According to a second aspect of the present invention, in a VTR tracking device in which tracking control is performed using a pilot signal recorded on a track, a tracking error at a plurality of positions on the track during a run-up period before post-recording is performed. The signal is sampled and held, and the track bending shape is judged using the tracking error signals at a plurality of positions of the track sampled and held during the run-up period,
This is a VTR tracking device that controls the track shift during post-recording according to the track bend shape.

[0010]

According to the first aspect of the invention, the tracking error signals at a plurality of positions are sampled and held during the run-up period before the after-recording, and these tracking error signals are averaged. Using the averaged tracking error signal, the tracking error signal obtained from the ITI area is corrected during post-recording. Therefore, when a track bend occurs, the track shift is averaged from near the ITI area to away from the ITI area.

According to the second aspect of the present invention, the tracking error signals at a plurality of track positions are sampled and held during the run-up period before post-recording, and the tracking error signals at a plurality of track positions sampled and held during the run-up period are recorded. Use to determine the track bend shape. The track shift during post-recording can be optimally set according to the track bending shape and the post-recording mode.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention. In FIG. 1, 1A and 1B are rotary heads. The rotary head 1A is an A channel head,
The rotary head 1B is a B-channel head. Recording signals are reproduced from the magnetic tape by the rotary heads 1A and 1B. An inclined track is formed on the magnetic tape as shown in FIG. Each track is provided with an audio area, a video area, and a subcode area. As shown in FIG. 2, in each track, A channel tracks and B channel tracks having different azimuth angles are alternately formed. Low-frequency pilot signals f ₂ , f ₁ , f ₂ , ... Are recorded on the tracks T1, T3, T5 ,.

In FIG. 1, the outputs of the rotary heads 1A and 1B are supplied to the RF switch circuit 2. An RF switching pulse is supplied from the input terminal 3 to the RF switch circuit 2. By this RF switching pulse, RF
The switch circuit 2 is switched. RF switch circuit 2
Is supplied to a video / audio signal processing circuit (not shown) and to the bandpass filters 4A and 4B.

The bandpass filter 4A has a characteristic of passing the pilot signal f1. The bandpass filter 4B has a characteristic of passing the pilot signal f2. The output of the bandpass filter 4A is supplied to the envelope detection circuit 5A. The output of the bandpass filter 4B is supplied to the envelope detection circuit 5B. The reproduction signal level of the pilot signal f1 is detected by the envelope detection circuit 5A. The reproduction signal level of the pilot signal f2 is detected by the envelope detection circuit 5B.

The outputs of the envelope detection circuits 5A and 5B are supplied to the comparator 6. The comparator 6 is
The reproduction signal level of the pilot signal f1 from the envelope detection circuit 5A and the reproduction signal level of the pilot signal f2 from the envelope detection circuit 5B are compared to form a tracking error signal.

Reference numeral 7 is a timing pulse generation circuit. An RF switching pulse is supplied from the input terminal 3 to the timing pulse generating circuit 7. The timing signal generating circuit 7 is based on this RF switching pulse, and
Sampling pulses P1 to P8 as shown in FIG.

That is, FIG. 3A shows an RF switching pulse, and by this RF switching pulse, the A channel rotary head 1A and the B channel rotary head 1 are shown.
B and B are switched. As a result, a reproduction signal as shown in FIG. 3B is obtained. As shown in FIG. 3C, the sampling pulse P1 is generated during the reproduction of the ITI area of the A channel. Then, sampling pulses P2, P3, and P4 are generated in the first half, middle, and second half of the A channel data, respectively. During the period in which the ITI area of the B channel is reproduced, the sampling pulse P
5 is generated. Then, sampling pulses P6, P7, and P8 are generated in the first half, the center, and the second half of the B channel data, respectively.

In FIG. 1, 8A to 8C are sample and hold circuits for holding a tracking error signal on the A channel during the run-up period, and 9A to 9C are samples for holding a tracking error signal on the B channel during the run-up period. It is a hold circuit. Sample hold circuit 8A
8C and the sample hold circuits 9A to 9C are supplied with the tracking error signal from the comparator 6. Further, the sampling and holding circuits 8A to 8C are supplied from the timing pulse generating circuit 7 with sampling pulses P2 to P4 which are respectively generated in the first half portion, the middle portion and the second half portion of the A channel data. The sampling and holding circuits 9A to 9C are supplied from the timing pulse generating circuit 7 with sampling pulses P6 to P8 which are respectively generated in the first half portion, the middle portion, and the second half portion of the B channel data.

Reference numerals 10A and 10B are sample and hold circuits for holding a tracking error signal during after-recording. A tracking error signal is supplied from the comparator 6 to the sample hold circuits 10A and 10B. In addition, sample hold circuits 10A and 10B
From the timing pulse generator 7 to the sampling pulse P in the ITI area of the A channel and the B channel.
1 and P5 are respectively supplied.

Reference numeral 11 denotes an averaging circuit for averaging the tracking error signal on the A channel. The sample-and-hold circuits 8A to 8C hold tracking error signals in the first half, middle, and second half of the data on the A channel during the run-up period. The tracking error signals in the first half, middle part, and second half of the data on the A channel are supplied to the averaging circuit 11. In the averaging circuit 11,
The average of the tracking error signals in the first half, middle part, and second half of the data on these A channels is obtained.

Reference numeral 12 is an averaging circuit for averaging the tracking error signals on the B channel. The sample-and-hold circuits 9A to 9C hold tracking error signals in the first half, middle, and second half of the data on the B channel during the run-up period. The tracking error signals in the first half, middle part, and second half of the data on the B channel are supplied to the averaging circuit 12. In the averaging circuit 12,
The average of the tracking error signals in the first half, the middle and the second half of the data on these B channels is obtained.

Reference numerals 13 and 14 are multiplication circuits. The multiplication circuit 13 is supplied with the output of the averaging circuit 11 and the coefficient α from the fixed value memory 15. The multiplication circuit 13 multiplies the average value of the tracking error signals in the first half, middle portion, and second half of the data of the A channel output from the averaging circuit 11 by the coefficient α. The multiplier circuit 14 is supplied with the output of the averaging circuit 12 and the coefficient (1-α) from the fixed value memory 15. By the multiplication circuit 14, the coefficient (1-α) is added to the average value of the tracking error signals in the first half, the middle, and the second half of the B channel data output from the averaging circuit 12.
Is multiplied by. The output of the multiplication circuit 13 and the output of the multiplication circuit 14 are added by the addition circuit 16. This adder circuit 16
The combined error signal is obtained from the output of.

The fixed value memory 15 has a fixed coefficient α and (1−) determined by the head width Tw and the track pitch Tp.
Output α). Track shift can be performed by this coefficient α. For example, when (α = 1), the rotary heads 1A and 1B are tracking-controlled to the same azimuth track center, and when (α = 0), the rotary heads 1A and 1B are tracking-controlled to the reverse azimuth track center. To be done.

Reference numeral 17 is an arithmetic circuit for performing an operation for correcting the coefficient α. In the arithmetic circuit 17, the tracking error signal in the ITI region of the A channel and the IT of the B channel are sampled from the sample hold circuits 10A and 10B.
A tracking error signal in the I region is supplied.

The coefficient α ₁ obtained by the arithmetic circuit 17 is supplied to the coefficient memory 19 via the switch circuit 18. The switch circuit 18 is turned on during the run-up period. The coefficient memory 19 stores the coefficients α ₁ and (1-α ₁ ) in the run-up period.
Is stored.

Reference numerals 20A and 20B are multiplication circuits. The multiplication circuits 20A and 20B are the sample hold circuit 10
And 10B supply the tracking error signal in the ITI area of the A channel and the tracking error signal in the ITI area of the B channel. In addition, the multiplication circuit 2
Coefficients α ₁ and (1−α ₁ ) are supplied from the coefficient memory 19 to 0A and 20B. Multiplier circuits 20A and 20
At B, the tracking error signal in the ITI region of the A channel and the tracking error signal in the ITI region of the B channel are multiplied by the coefficients α ₁ and (1−α ₁ ), respectively. The outputs of the multiplication circuits 20A and 20B are added by the addition circuit 21.

Reference numeral 22 is a switch circuit which can be switched between the run-up period and after-recording. The switch circuit 22 is set on the terminal 22A side during the run-up period. During the post-recording period, the switch circuit 22 is set to the terminal 22B side. The addition circuit 16 is connected to the terminal 22A of the switch circuit 22.
The output of is supplied. The output of the adder circuit 21 is supplied to the terminal 2B of the switch circuit 22.

Reference numeral 23 is a capstan motor. The rotation of the capstan motor 23 is detected by the FG generator,
This FG pulse is supplied to the speed error detection circuit 24. The combined tracking error signal from the switch circuit 22 and the speed error signal from the speed error detection circuit 24 are added by the adder circuit 25. The output of the adder circuit 25 is supplied to the capstan motor 23 via the capstan motor driver 26.

The operation of the embodiment of the present invention will be described. As shown in FIG. 2, the pilot signals f1 and f2 are recorded on each track. Rotating head 1
When A traces the track T2 of the A channel, reproduced signals of the pilot signal f1 and the pilot signal f2 are output as the crosstalk components of the adjacent tracks T1 and T3. The level of the reproduction pilot signal f1 is detected by the envelope detection circuit 5A, and the reproduction pilot signal f2 is detected.
Is detected by the envelope detection circuit 5B. The level of the reproduced pilot signal f1 and the pilot signal f
The two levels are compared by the comparator 6.

FIG. 4 shows the relationship between the tracking error signal output from the comparator 6 and the tracking shift amount. In FIG. 4, the horizontal axis represents the amount of track deviation, and the vertical axis represents the tracking error signal level from the comparator 6. As shown in FIG. 4, if the rotary head 1A traces the center of the track of the A channel, the tracking error signal level from the comparator 6 becomes "0".

When the rotary head 1B traces the track of the B channel, as shown in FIG. 2, the reproduced signal of the pilot signal f1 is output, whereas the pilot signal f2 is hardly reproduced. This reproduction pilot signal f
The comparator 6 compares the level of 1 and the level of the pilot signal f2. FIG. 5 shows the relationship between the tracking error signal output from the comparator 6 and the tracking shift amount. As shown in FIG. 5, when the rotary head 1B traces the center of the track of the B channel, the tracking error signal level from the comparator 6 becomes a large level.

Now, the tracking error signal obtained from the comparator 6 on the A channel is sampled as f (A), and the tracking error signal obtained from the comparator 6 on the B channel is sampled as f (A).
(B). When these tracking error signals f (A) and f (B) are weighted and combined, and f = αf (A) + (1-α) f (B) is taken as the combined tracking error signal, this combined tracking error signal is When used, the tracking amount can be shifted according to the value of α. For example, if α = 1, then f = f (A) and the track center of the same azimuth channel is traced. When α = 0, f = f (B) and the track center of the reverse azimuth channel is traced. Therefore, at the time of dubbing, when the head is scanned so that the edge of the recorded track and the edge of the new dubbing track match, the track width Tw
When the track pitch Tp is known, α = 1 − ((Tw−Tp) / 2) (1 / Tp) may be set.

During the run-up period, the switch circuit 18 is turned on and the switch circuit 22 is set to the terminal 22A side. The tracking error signal is output from the comparator 6. The tracking error signal in the data region of the A channel is taken in by the sample hold circuit 8A at the first half thereof and is sampled by the sample hold circuit 8B at the intermediate portion thereof.
And the latter half is captured by the sample hold circuit 8C. Then, these sample and hold circuits 8
The outputs of A to 8C are averaged by the averaging circuit 11. The averaging circuit 11 outputs the tracking error signal f _AVE (A) of the channels averaged over the entire track.

The first half of the tracking error signal in the data area of the B channel is the sample and hold circuit 9.
It is taken in by A, the middle part is taken in by the sample hold circuit 9B, and the latter half is taken in by the sample hold circuit 9C. Then, these sample hold circuits 9A
The outputs of 9C are averaged by the averaging circuit 12. The averaging circuit 12 outputs the tracking error signal f _AVE (B) of the channels averaged over the entire track.

The averaged tracking error signal f _AVE (A) of the A channel and the averaged tracking error signal f _AVE (B) of the B channel are multiplied by the multiplication circuit 1
3 and 14, and the addition circuit 16 performs weighted addition. The adder circuit 16 outputs a combined tracking error signal f _AVE averaged over the entire track. The output of the adder circuit 16 is the output of the switch circuit 22 and the adder circuit 2.
It is supplied to the capstan motor driver 26 via 5. As a result, the rotation of the capstan motor 23 is controlled according to the combined tracking error signal f _AVE . In this way, during the run-up period, tracking is performed using the composite tracking error signal averaged over the entire track.

Further, during this run-up period, the tracking error signal in the ITI region of the A channel is taken into the sample hold circuit 10A, and the IT of the B channel is
The tracking error signal in the I region is taken into the sample hold circuit 10B. Sample and hold circuit 10
The outputs of A and the output of the sample hold circuit 10B are weighted and added by the multiplication circuits 20A and 20B and the addition circuit 21 to obtain a combined tracking error signal.
The combined tracking error signal in the ITI region at this time is obtained as f = αf (A) + (1-α) f (B). Tracking is averaged over the entire track during the run-up period, and tracking shifts in the ITI region, so that (f≈0). Therefore, the arithmetic circuit 17 sets α such that (f = 0)
_The operation of changing α to ₁ is performed. 0 = α ₁ f (A) + (1-α ₁ ) f (B) α ₁ = f (B) / (f (B) −f (A) The coefficient α ₁ obtained by the arithmetic circuit 17 is a switch. It is stored in the memory 19 via 18.

During the post-recording period, the switch circuit 22 is set to the terminal 22B. The tracking error signal in the ITI area of the A channel is the sample hold circuit 10A.
The tracking error signal in the ITI area of the B channel is taken into the sample hold circuit 10B, weighted and added by the multiplication circuits 20A and 20B, and the adder circuit 21 to obtain a combined tracking error signal. At this time, α ₁ obtained during the run-up period is used as the coefficient. The combined tracking error signal is supplied to the capstan motor driver 26 via the switch circuit 22 and the adder circuit 25.

As described above, the tracking error signal obtained from the ITI area is corrected at the time of after-recording by using the averaged tracking error signal. For this reason,
Even when a track bend occurs, the track can be shifted on average.

Incidentally, the head width of the heads 1A and 1B is generally wider than the track pitch in consideration of the processing accuracy of the heads. Therefore, when the head is traced along the track center of the recorded track during post-recording, the track center of the new track formed by post-recording will not match the track center of the previously recorded track, and the tracking change will occur. Problem arises. At the time of after-recording, in order to match the track center of the new track formed by the after-recording with the track center of the previously recorded track,
As mentioned above, it is necessary to shift the track so that the edge of the previously recorded track and the edge of the new track formed by post-recording match.

However, if the edge of the previously recorded track and the edge of the new track formed by post-recording are made to coincide with each other, the new track formed by the post-recording will be larger than the adjacent previously recorded track. Overhang, affecting adjacent previously recorded tracks.

That is, FIG. 6 shows a state in which the head is traced along the track center of a recorded track during dubbing. In FIG. 6, 51A and 5A
1B, 51C, ... are recorded tracks, 52A,
Tracks 52B, 52C, ... Are post-recorded. For example, the track pitch Tp is 10 μm and the head width Tw is 13 μm. As shown in FIG. 6, the track centers T of the recorded tracks 51A, 51B, 51C, ...
Post-recording tracks 52A, 52 to match _C1
When B, 52C, ... Are formed, the head width is wider than the track pitch. As a result, the track center T of the formed post-recording tracks 52A, 52B, 52C ,.
_C2 does not coincide with the track center T _C1 of the recorded tracks 51A, 51B, 51C, ....

FIG. 7 shows a state in which the head is traced so that the edge of a recorded track and the edge of a new track formed by post-recording coincide with each other. As shown in FIG. 7, the recorded tracks 53A, 53B, 53
Dubbing track 54 so that the edges of C, ...
When A, 54B, 54C, ... Are formed, as a result, the formed dubbing tracks 54A, 54B, 54C ,.
The track center T _C4 is recorded tracks 51A, 5
It coincides with the track center T _C3 of 1B, 51C, ....
However, when the head is traced so that the edge of the recorded track and the edge of the new track formed by post-recording match, the after-recording track 54C protrudes onto the adjacent recorded track 53E, and the recorded track The destruction of 53E becomes large.

From the above, it is necessary to determine the track shift according to the curved shape of the track in consideration of the tracking change and the destruction of the recorded track.

The shape of the track bend is typically
J-shape and bow shape are conceivable. The J-shape and the arcuate shape each have a front bend and a rear bend. The after-recording mode includes a mode for dubbing a video area and a subcode area, a mode for dubbing an audio area, a mode for dubbing a subcode area, a mode for dubbing an audio area and a subcode area, and an audio area and a video. There is a mode for dubbing the area and the subcode area.

The bend shape can be detected, for example, as follows. That is, as shown in FIGS. 8 and 9, the tracking error signal from the first half to the second half of the track is sampled during the run-up period. In this example, the six tracking error signals D1 to D6 are sampled.

FIG. 8A shows the bow shape of the front bend,
FIG. 8B shows the tracking error at that time. The characteristic in the case of the bow shape of the front curve is that the tracking error signal D2 in the first half exceeds the front side threshold value, the tracking error signal in the middle part is equal to or more than the front side threshold value, and the tracking error signal D6 in the second half part is This is the point at which the threshold value falls below the front threshold again. FIG. 9A shows a J shape with a forward bend, and FIG. 9B shows a tracking error at that time. The characteristic of the J-shaped curve with a forward curve is that the tracking error signal D2 in the front half exceeds the front side threshold value,
The point is that the tracking error signal in the middle portion is equal to or higher than the front side threshold value, and the tracking error signal D6 in the latter half portion is also equal to or higher than the front side threshold value.

FIG. 10 is a flow chart showing a specific process for judging the curved shape. In this example,
A tracking error signal at three points as shown in FIG. 11 is used. In FIG. 11, the sample value of the tracking error signal in the first half of the track is d1, the sample value of the tracking error signal in the middle of the track is d2, and the sample value of the tracking error signal in the second half of the track is d3. .

Steps 101 to 105 are processes for setting the front half front bending flag b1 and the front half rear bending flag b2. It is determined whether the sampled value (d2-d1) is larger than the front side threshold th (step 101). If the sampled value (d2-d1) is larger than the front side threshold th, the front half front bending flag b1 is set. It is set to "1" and the first half rearward bending flag b2 is set to "0" (step 102). Sample value (d2
If -d1) is not larger than the front side threshold value th, it is judged whether the sample value (d2-d1) is smaller than the rear side threshold value -th (step 103), and the sample value (d2-d1) is If it is smaller than the rear threshold value -th, the front half front bending flag b1 is set to "0" and the front half rear bending flag b2 is set to "1" (step 104). If the sampled value (d2-d1) is not smaller than the rear threshold value -th, the front half front bend flag b1
Also, the first half rearward bending flag b2 is set to "0".

Steps 106 to 110 are processing for setting the second half front bending flag b3 and the second half rear bending flag b4. It is determined whether the sampled value (d2-d3) is larger than the front side threshold th (step 106). If the sampled value (d2-d3) is larger than the front side threshold th, the latter half front curve flag b3 is set. The flag is set to "1" and the second half rearward turning flag b4 is set to "0" (step 107). Sample value (d2
If -d3) is not larger than the front threshold value th, it is determined whether the sample value (d2-d3) is smaller than the rear threshold value -th (step 108), and the sample value (d2-d3) is If it is smaller than the rear side threshold value −th, the second half front bending flag b3 is set to “0” and the second half rear bending flag b4 is set to “1” (step 109). If the sampled value (d2-d3) is not smaller than the rear threshold value -th, the second half front curve flag b3
Also, the second half rearward bending flag b4 is set to "0".

In steps 11 to 126, the bending shape is determined from the states of the front half front bending flag b1 and the front half rear bending flag b2, and the rear half front bending flag b3 and the rear half rear bending flag b4 set as described above. Processing.

If the front half front curve flag b1 is "0", the first half rear curve flag b2 is "0", the second half front curve flag b3 is "0", and the second half rear curve flag b4 is "0" (step 111), the curve curve is forward. It is determined to be the J-shape (step 112).

If the front half front curve flag b1 is "0", the first half rear curve flag b2 is "1", the second half front curve flag b3 is "0", and the second half rear curve flag b4 is "1" (step 113), the curve curve is forward. It is determined that the shape is a bow shape (step 114).

If the front half front curve flag b1 is "1", the first half rear curve flag b2 is "0", the second half front curve flag b3 is "1", and the second half rear curve flag b4 is "0" (step 115), the curve curve is backward. It is determined that the shape is a bow shape (step 116).

If the front half front curve flag b1 is "1", the first half rear curve flag b2 is "0", the second half front curve flag b3 is "0", and the second half rear curve flag b4 is "0" (step 117), the front side front It is determined that it has a curved J-shape (step 118).

If the front half front curve flag b1 is "0", the first half rear curve flag b2 is "0", the second half front curve flag b3 is "0", and the second half rear curve flag b4 is "1" (step 119), the rear side It is determined that the shape is a backward-bent J-shape (step 120).

If the front half front curve flag b1 is "0", the first half rear curve flag b2 is "1", the second half front curve flag b3 is "0", and the second half rear curve flag b4 is "0" (step 121), the front rear side It is determined that it has a curved J-shape (step 122).

If the front half front curve flag b1 is "0", the first half rear curve flag b2 is "0", the second half front curve flag b3 is "1", and the second half rear curve flag b4 is "0" (step 123), the rear side It is determined that the shape is a backward-bent J-shape (step 124).

If the first half front curve flag b1 is "0", the first half rear curve flag b2 is "1", the second half front curve flag b3 is "1", and the second half rear curve flag b4 is "0" (step 125), then the curve curve is backward. It is determined to be the J-shape (step 126).

If the front half front curve flag b1 is "1", the first half rear curve flag b2 is "0", the second half front curve flag b3 is "0", and the second half rear curve flag b4 is "1" (step 127), the front side front It is determined that the shape is a J-shape with a curve behind and a curve behind (step 128).

Considering the change in tracking and the destruction of recorded tracks, track shifting is performed according to each dubbing mode as follows.

A. Dubbing the video area and the subcode area a. In the case of a bow shape with a forward bend, the track is shifted forward by ((Tw-Tp) / 2) + (amount of bend / 2). The ITI area is used as a reference. FIG. 12 shows how the video area and the subcode area are post-recorded in this way.
In FIG. 12, a track without hatching is a previously recorded track, whereas a track shown with hatching is an after-recording track.

B. In the case of the bow shape of the backward curve, the track is shifted backward by ((Tw-Tp) / 2) + (the amount of curve / 2). The ITI area is used as a reference. FIG. 13 shows a state where the video area and the subcode area are post-recorded in this way.
In FIG. 13, a track without hatching is a previously recorded track, while a track shown with hatching is an after-recording track.

C. In the case of a J shape with a forward curve, the track is shifted forward by ((Tw-Tp) / 2) + (amount of curve / 2). The ITI area is used as a reference. FIG. 14 shows a state where the video area and the sub-code area are post-recorded in this way.
In FIG. 14, a track without hatching is a previously recorded track, while a track shown with hatching is an after-recording track.

D. In the case of a J shape with a backward bend, the track is shifted forward by ((Tw-Tp) / 2) + (amount of bend / 2). The ITI area is used as a reference. FIG. 15 shows a state where the video area and the sub-code area are post-recorded in this way.
In FIG. 15, a track without hatching is a previously recorded track, while a track shown with hatching is an after-recording track.

B. Post-record audio area a. In the case of a bow shape with a forward curve, the track is shifted forward only ((Tw-Tp) / 2). The ITI area is used as a reference. 16
The figure shows a state where the audio area is post-recorded in this way. In FIG. 16, a track without hatching is a previously recorded track, whereas a track shown with hatching is an after-recording track.

B. Center tracking is used when the bow is curved backward. The ITI area is used as a reference. FIG. 17 shows how the audio area is post-recorded in this way. In FIG. 17, a track without hatching is a previously recorded track, while a track shown with hatching is an after-recording track.

C. In the case of a J shape with a forward curve, the track is shifted forward only ((Tw-Tp) / 2). The ITI area is used as a reference. Figure 18
The figure shows a state where the audio area is post-recorded in this way. In FIG. 18, a track without hatching is a previously recorded track, while a track shown with hatching is an after-recording track.

D. Center tracking is used in the case of a J shape with a backward bend. The ITI area is used as a reference. FIG. 19 shows how the audio area is post-recorded in this way. In FIG. 19, a track without hatching is a previously recorded track, while a track shown with hatching is an after-recording track.

C. Postcode the subcode area a. In the case of a bow shape with a forward curve, the track is shifted forward only ((Tw-Tp) / 2). The rear of the video area is used as a reference. Figure 20
Shows the situation when the subcode area is post-recorded in this way. In FIG. 20, a track without hatching is a previously recorded track, while a track shown with hatching is an after-recording track.

B. In the case of an arched shape with a backward curve, the track is shifted forward only ((Tw-Tp) / 2). The rear of the video area is used as a reference. Figure 21
Shows the situation when the subcode area is post-recorded in this way. In FIG. 21, a track without hatching is a previously recorded track, whereas a track shown with hatching is an after-recording track.

C. In the case of a J shape with a forward curve, the track is shifted forward only ((Tw-Tp) / 2). The rear of the video area is used as a reference. FIG. 22
Shows the situation when the subcode area is post-recorded in this way. In FIG. 22, a track without hatching is a previously recorded track, whereas a track shown with hatching is an after-recording track.

D. In the case of a J shape with a backward curve, the track is shifted forward only ((Tw-Tp) / 2). The rear of the video area is used as a reference. FIG. 23
Shows a situation where the video area and the sub-code area are post-recorded in this way. In FIG. 23, a track without hatching is a previously recorded track, while a track shown with hatching is an after-recording track.

D. Post-record audio and sub-code areas a. In the case of a bow shape with a forward curve, the track is shifted forward only ((Tw-Tp) / 2). The ITI area is used as a reference. Figure 24 shows
In this way, a state in which the audio area and the sub-code area are post-recorded is shown. In FIG. 24, a track without hatching is a previously recorded track, whereas a track shown with hatching is an after-recording track.

B. Center tracking is used when the bow is curved backward. The ITI area is used as a reference. FIG. 25 shows a state where the audio area and the sub-code area are post-recorded in this way. In FIG. 25, a track without hatching is a previously recorded track, whereas a track shown with hatching is an after-recording track.

C. In the case of a J shape with a forward bend, the track is shifted forward by ((Tw-Tp) / 2) + (amount of bend / 4). The ITI area is used as a reference. FIG. 26 shows a state where the audio area and the sub-code area are post-recorded in this way. In FIG. 26, a track without hatching is a previously recorded track, while a track shown with hatching is an after-recording track.

D. In the case of a J shape with a backward bend, the track is shifted backward by ((Tw-Tp) / 2) + (amount of bend / 4). The ITI area is used as a reference. FIG. 27 shows a state where the audio area and the sub-code area are post-recorded in this way. In FIG. 27, a track without hatching is a previously recorded track, whereas a track shown with hatching is an after-recording track.

E. After-recording the audio area, the video area, and the subcode area a. In the case of the bow shape of the forward bend, the track is shifted forward by ((Tw-Tp) / 2) + (the amount of bend / 4). The ITI area is used as a reference. FIG. 28 shows a state where the audio area, the video area, and the subcode area are post-recorded in this way. In FIG. 28, a track without hatching is a previously recorded track, whereas a track shown with hatching is an after-recording track.

B. In the case of an arched shape with a backward bend, the track is shifted backward by ((Tw-Tp) / 2) + (amount of bend / 4). The ITI area is used as a reference. FIG. 29 shows a state where the audio area, the video area, and the subcode area are post-recorded in this way. In FIG. 29, a track without hatching is a previously recorded track, whereas a track shown with hatching is an after-recording track.

C. In the case of a J shape with a forward bend, the track is shifted forward by ((Tw-Tp) / 2) + (amount of bend / 4). The ITI area is used as a reference. FIG. 30 shows a state where the audio area, the video area, and the subcode area are post-recorded in this way. In FIG. 30, a track without hatching is a previously recorded track, whereas a track shown with hatching is an after-recording track.

D. In the case of a J shape with a backward bend, the track is shifted backward by ((Tw-Tp) / 2) + (amount of bend / 4). The ITI area is used as a reference. FIG. 31 shows a state where the audio area, the video area, and the subcode area are post-recorded in this way. In FIG. 31, a track without hatching is a previously recorded track, while a track shown with hatching is an after-recording track.

[0081]

According to the first aspect of the invention, the tracking error signals at a plurality of positions are sampled and held during the run-up period before post-recording, and these tracking error signals are averaged. By using this averaged tracking error signal, ITI
The tracking error signal obtained from the area is corrected. Therefore, when a track bend occurs, the ITI
The average track shift is from near the area to away from the ITI area. For this reason, as shown in FIG. 32, when audio or video is post-recorded, even if a track bend occurs, the index will continue on the extension of the post-recording track, and the index signal can be reliably picked up.

According to the invention of claim 2, the tracking error signals at a plurality of positions of the track are sampled and held during the run-up period before the after-recording, and the tracking error signals are sampled and held at the plurality of positions during the run-up period. The track bend shape is determined using the error signal.
Depending on the track bending shape and dubbing mode,
The track shift during post-recording can be set optimally.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a schematic diagram used to describe an embodiment of the present invention.

FIG. 3 is a timing chart used for explaining one embodiment of the present invention.

FIG. 4 is a graph used to explain one embodiment of the present invention.

FIG. 5 is a graph used to explain one embodiment of the present invention.

FIG. 6 is a schematic diagram showing a relationship between a track shift and an after-recording track formed.

FIG. 7 is a schematic diagram showing a relationship between a track shift and an after-recording track formed.

FIG. 8 is a schematic diagram used to describe detection of a track bend.

FIG. 9 is a schematic diagram used to describe detection of a track bend.

FIG. 10 is a flowchart used for explaining detection of track bending in the embodiment of the present invention.

FIG. 11 is a schematic diagram used to describe detection of track bending in the embodiment of the present invention.

FIG. 12 is a schematic diagram used to explain a track shift in the embodiment of the present invention.

FIG. 13 is a schematic diagram used to explain a track shift in the embodiment of the present invention.

FIG. 14 is a schematic diagram used to explain a track shift in the embodiment of the present invention.

FIG. 15 is a schematic diagram used to explain a track shift in the embodiment of the present invention.

FIG. 16 is a schematic diagram used to explain a track shift in the embodiment of the present invention.

FIG. 17 is a schematic diagram used to explain a track shift in the embodiment of the present invention.

FIG. 18 is a schematic diagram used to explain a track shift in the embodiment of the present invention.

FIG. 19 is a schematic diagram used to explain a track shift in the embodiment of the present invention.

FIG. 20 is a schematic diagram used to explain a track shift in the embodiment of the present invention.

FIG. 21 is a schematic diagram used to explain a track shift in the embodiment of the present invention.

FIG. 22 is a schematic diagram used to explain a track shift in the embodiment of the present invention.

FIG. 23 is a schematic diagram used to explain a track shift in the example of the present invention.

FIG. 24 is a schematic diagram used to explain a track shift in the embodiment of the present invention.

FIG. 25 is a schematic diagram used to explain a track shift in the embodiment of the present invention.

FIG. 26 is a schematic diagram used to explain a track shift in the example of the present invention.

FIG. 27 is a schematic diagram used to explain a track shift in the example of the present invention.

FIG. 28 is a schematic diagram used to explain a track shift in the example of the present invention.

FIG. 29 is a schematic diagram used to explain a track shift in the example of the present invention.

FIG. 30 is a schematic diagram used to explain a track shift in the example of the present invention.

FIG. 31 is a schematic diagram used to explain a track shift in the example of the present invention.

FIG. 32 is a schematic diagram showing an effect of the present invention.

FIG. 33 is a schematic diagram used to describe a track format of a digital VTR.

FIG. 34 is a schematic diagram used for explaining tracking in a conventional digital VTR.

[Explanation of symbols]

1A, 1B Rotary head 5A, 5B Envelope detection circuit 8A-8C, 9A-9C, 10A, 10B Sample hold circuit

Claims (2)

[Claims] 1. A tracking device of a VTR for performing tracking control using a pilot signal recorded on a track, wherein a tracking error signal at a plurality of positions on the track is sample-held in a run-up period before after-recording, A tracking device for a VTR, wherein tracking control is performed using tracking error signals at a plurality of positions of the track sampled and held during the run-up period during post-recording. 2. A tracking device of a VTR for performing tracking control using a pilot signal recorded on a track, wherein a tracking error signal at a plurality of positions on the track is sampled and held during a run-up period before after-recording, The track error shape is determined by using the tracking error signals at a plurality of positions of the track sampled and held during the run-up period, and the track shift during post-recording recording is controlled according to the track curve shape.
R tracking device.