JP3336763B2 - Playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reproducing apparatus for reproducing a magnetic tape on which data is recorded, and more particularly, to a reproducing apparatus for reproducing a magnetic tape on which data such as video and audio are recorded on inclined tracks on the magnetic tape. Related to the device.

[0002]

2. Description of the Related Art Conventionally, in a so-called helical scan type VTR in which data is recorded on an inclined track, a control signal (hereinafter, referred to as a CTL signal) is recorded on a longitudinal track, and the tape is reproduced during reproduction. A so-called capstan servo for controlling the running speed of the tape based on the obtained CTL signal is applied.

In such a VTR, when recording a video signal, a CTL signal synchronized with a vertical synchronizing signal of the video signal is generated, and the generated CTL signal is recorded on a longitudinal track. The rotation of the rotary head is synchronized with the CTL signal, and a video signal for one frame is recorded on one helical track, for example.

[0004] When reproducing the video signal recorded as described above, the CTL signal recorded in the longitudinal direction of the magnetic tape is reproduced, and the tape speed is adjusted so that the reproduced CTL signal becomes constant. Perform the capstan servo to control.

More specifically, a conventional VTR has a CTL as a capstan servo system, for example, as shown in FIG.
A phase comparator 51 for comparing the phase of a CTL signal reproduced by the reproducing head 50 with a phase of a reference signal (hereinafter referred to as a REF signal), a signal processing system 52 for forming a servo signal from an output of the phase comparator 1, Capstan motor 53
And a frequency generator 54 that generates a signal having a frequency corresponding to the rotation speed of the capstan motor 53.

The phase comparator 51 compares the phase of the CTL signal reproduced by the CTL reproducing head 50 with the phase of the REF signal and outputs the same. The signal processor 52 compares the phase of the CTL signal with the output of the frequency generator 54. A capstan servo is performed by forming a servo signal from the output of the device 51 and driving a capstan motor 53 based on the servo signal.

That is, the CTL signal serves as a reference for the capstan servo.
If the TL signal cannot be reproduced, the phase of the capstan motor cannot be locked, and accurate tape running cannot be maintained.

In this VTR, a CTL signal recorded in the longitudinal direction of the magnetic tape is reproduced, and the reproduced C
The rotation of the rotary head is synchronized with the TL signal, tracking servo is performed so that the trajectory of the rotary head coincides with the tilt track recorded as described above, and the video signal recorded on the tilt track is accurately output every frame. It can be played.

For this reason, in this VTR, CTL
If the signal cannot be reproduced, accurate tracking servo cannot be performed, and the video signal recorded on the inclined track cannot be reproduced accurately.

[0010]

However, depending on the environment in which the VTR is used, the magnetic tape is separated from the magnetic tape at a head gap of a CTL recording head for recording the CTL signal on the tape or a CTL reproducing head for reproducing the CTL signal from the tape. A so-called clog may occur in which the reproduction level of the CTL signal temporarily drops due to attachment of oxide film particles and the like. In this case, it is usually impossible to reproduce the images and sounds recorded on the tape. However, for applications such as broadcasting, it is required to reproduce the sounds and images normally even in this case.

For this reason, in the VTR shown in FIG.
A clog detection unit 55 for detecting that the CTL reproducing head 50 has clogged, a voltage holding unit 56 for holding an output voltage of the phase comparator 51, and an output of the voltage holding unit 56 and the phase comparator 51. And a switch 57 for switching and supplying the signal to the signal processing unit 52.

When the CTL reproducing head 50 logs, the switch 57 operates as a clog detecting unit 55.
And supplies the voltage held in the voltage holding unit 56 to the signal processing unit 52. The signal processing unit 52 drives the capstan motor 53 based on the supplied voltage, CTL playback head 50
The data recorded on the inclined track is reproduced as a value before clogging.

However, in the above-described operation, if the CTL reproducing head clogs before the capstan servo is applied, the data recorded on the inclined track is reproduced based on the voltage held in the voltage holding section 55. It is not possible.

When the CTL reproducing head clogs, it is conceivable to keep the rotation speed of the capstan motor at a predetermined rotation speed. In this case, however, the diameter of the capstan shaft at the time of recording and reproduction is reduced. Since the tape speed changes due to expansion and contraction of the tape due to a difference, a change in temperature, or the like, tracking cannot be performed even if the rotation speed of the capstan motor is fixed, and data on the inclined track cannot be reproduced.

A so-called dynamic track head (hereinafter, referred to as a DT head) in which the head is movable in the axial direction of the rotating head, that is, in the width direction of the inclined track, is used as a rotating head for reproducing the data of the inclined track. It is conceivable to perform data reproduction by following a track.

However, there is a limit to the moving range of the DT head, and when this limit is reached, a head jump occurs and the reproduced data is lost. Depending on the device, stable tracking for a long time of several minutes or more can be achieved. It was difficult to do.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a reproducing apparatus capable of stably reproducing data even when a CTL reproducing head logs.

[0018]

According to the present invention, there is provided a reproducing apparatus comprising: an inclined track on which data is recorded with identification information added for each predetermined length unit; and a longitudinal track on which a control signal serving as a reference for tape running is recorded. A reproducing apparatus for reproducing a magnetic tape having a track and performing tracking servo based on a reproduced control signal, comprising: a rotating head for reproducing data recorded on the inclined track; and a rotating head for reproducing data recorded on the longitudinal track. A fixed head for reproducing a control signal, control signal detecting means for detecting the presence or absence of a control signal from a reproduced output of the fixed head, tape running control means for controlling running of the magnetic tape, and the inclined track of the rotary head Scanning control means for controlling scanning with respect to the head, and detection by the control signal detecting means Control means for controlling the tape running control means and the head scanning control means based on a force; and data reproduction means for reproducing data from the reproduction output of the rotary head based on identification information during reproduction output of the rotary head. And

In the reproducing apparatus, the control means controls the tape running so that the running of the magnetic tape is controlled based on the control signal reproduced by the fixed head when the control signal is detected. In addition to controlling the control means, the head scan control means is controlled so that the rotary head performs one scan on one inclined track. When a control signal is not detected, the magnetic tape is kept at a fixed level. The tape running control means is controlled so as to run at a speed, and the head scanning control means is controlled so that the rotary head scans the inclined track a plurality of times.

Also, in the reproducing apparatus according to the present invention, the head scanning control means controls the scanning of the rotating head with respect to the inclined track by controlling the number of rotations of the rotating head, When a signal is detected, the head scanning control means is controlled so that the rotation speed of the rotary head is equal to the rotation speed for performing one scan on one inclined track, and no control signal is detected. In this case, the head scanning control means is controlled such that the rotation speed of the rotary head is a rotation speed at which the inclined track is scanned a plurality of times.

Further, in the reproducing apparatus according to the present invention, the rotary head has a plurality of heads which is a plurality of times the number of heads used for performing one scan on one inclined track,
The head scanning control means controls the scanning of the rotating head on the inclined track by controlling the number of rotating heads used for reproduction, and the control means performs reproduction when the control signal is detected. The head scanning control means is controlled so that the number of heads of the rotary head used for the above-mentioned operation is equal to the number of heads performing one scan for one inclined track, and when a control signal is not detected, reproduction is performed. The head scanning control means is controlled so that the number of heads of the rotary head used in the above-mentioned method is the number of heads which scan the inclined track a plurality of times.

[0022]

In the reproducing apparatus according to the present invention, when a control signal is detected during reproduction of the magnetic tape, the control means controls the running of the magnetic tape based on the control signal reproduced by the fixed head. In addition to controlling the tape running control means, the head scanning control means is controlled so that the rotary head performs one scan on one inclined track. The data reproducing means reproduces data from the reproduction output of the rotary head based on the identification information during the reproduction output of the rotary head.

During reproduction of the magnetic tape, when so-called head clog occurs in which oxide film particles and the like separated from the magnetic tape adhere to the head gap of the fixed head, the reproduction level of the control signal reproduced by the fixed head decreases,
In some cases, the running of the magnetic tape cannot be controlled using the control signal.

At this time, in the reproducing apparatus, the control signal is not detected by the control signal detecting means, and the control apparatus controls the tape running control means so that the magnetic tape runs at a constant speed, and the rotary head is driven by the rotating head. The head scanning control means is controlled so that scanning is performed a plurality of times on one inclined track.

When the rotating head scans one inclined track a plurality of times, the same inclined track is reproduced two or more times, and the reproduced output of the rotating head is overlapped, but is recorded on the inclined track. Since the identification information is added to the data for each predetermined length unit, even if there is duplicated data during the output of the rotary head, the data reproducing means reproduces the data based on the identification information during the reproduction and output of the rotary head. And data without duplication is obtained.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a reproducing apparatus according to the present invention will be described below in detail with reference to the drawings.

In this embodiment, the present invention is applied to a digital tape recorder (hereinafter referred to as a digital VTR) which records and reproduces video and audio as data on a magnetic tape.

The magnetic tape reproduced by the digital VTR has a video and an audio which are converted from analog to digital.
As video data and audio data, for example, so-called D-
It is recorded on a magnetic tape in two formats.

That is, in the digital VTR, the video data and the audio data are recorded on a helical track _TRHEL inclined with respect to the traveling direction of the magnetic tape TP, for example, as shown in FIG. . Further, in the longitudinal direction of the magnetic tape TP is an analog audio cue track TR _AC to be described later and the control track TR _CTL and time code track TR _TC is provided. The arrow DT in FIG. 1 shows the tape running direction, and the arrow DH in the figure shows the running direction of the rotary head 31.

Here, data of a video channel and four audio channels are recorded on the helical track TR _HEL . The video data of the video channel is the video sector VS of the helical truck TR _HEL.
The audio data of the four audio channels is recorded in four audio sectors AS per track.

The video data of the video channel is 6
It consists of video data for one-half field. That is,
Image data for one field is recorded on six helical tracks TR _HEL .

The control track TR _CTL
The control signal (hereinafter, referred to as CTL signal) in synchronization with the recording of the helical track TR _{HE L} is recorded. In this digital VTR, a helical truck T
Since recording of _RHEL is performed for every two channels by so-called two-channel recording, the CTL signal has a frequency corresponding to two helical tracks, that is, three times the field frequency.

Here, one helical truck TR _HEL
As shown in FIG. 2, only two of the four audio sectors AS are helical tracks TR.
_It is placed at the beginning of the _HEL and the other two are placed at the back of the truck. Video data is stored in these audio sectors A
It is recorded in the video sector VS in the middle of S. Each of the video and audio sectors includes a preamble including a clock run-up sequence, a sync pattern, and an ID pattern; a sync block including a sync pattern, an ID pattern, a fixed-length data block, and error control data; It is divided into each element of a postamble composed of a sync pattern and an ID pattern. Further, in the track _TRHEL , an edit gap is provided between each sector in order to prevent a timing shift at the time of editing.

Each sync block includes, for example, a 2-byte sync pattern SYNC and a 2 byte sync pattern, as shown in FIG.
A 95-byte first inner code block including a byte ID pattern, a fixed-length data block, and error control data; a 93-byte second inner code block including a fixed-length data block and error control data; Consists of

Then, the I of the first inner code block
The helical track T is stored in ID ₀ of the first byte of the D pattern.
Information identifying the individual sync blocks in R _HEL is recorded, the second byte ID ₁ of ID pattern is information for identifying an individual helical track TR _HEL is recorded. That is, each sync block can be identified by the ID pattern.

The digital VTR has a capstan servo system for controlling the running of the magnetic tape during reproduction,
It has a head rotation speed control system for controlling the rotation speed of the rotating head at the time of reproduction, and a data reproduction system for reproducing a video signal and an audio signal from data reproduced from a magnetic tape by the rotation head.

This digital VTR performs a so-called capstan servo for controlling the running of the magnetic tape based on the CTL signal recorded on the control track when reproducing the magnetic tape recorded as described above.
Tracking servo is performed so that the rotating head traces the helical track.

In this digital VTR, for example, as shown in FIG. 4, the capstan servo system includes a CT for reproducing a CTL signal recorded on the control track.
The servo according to the comparison output of the L reproducing head 1, the phase comparator 3 for comparing the output of the CTL reproducing head 1 amplified by the amplifier 2 with the phase of the reference signal REF, and the phase comparator 3 amplified by the amplifier 4 A signal processing unit 5 for generating a signal, and a capstan motor 7 for driving a capstan based on the servo signal amplified by the amplifier 6 to run a magnetic tape.
And a frequency generator 8 for outputting a signal of a frequency corresponding to the rotation of the capstan motor 7.

The phase comparator 3 compares the output of the CTL reproducing head 1 amplified by the amplifier 2 with the phase of a reference signal REF having a reference frequency, and supplies a comparison output to a signal processing unit 5. The signal processing unit 5 includes a phase comparator 3
A servo signal is generated on the basis of the comparison output from the amplifier and a signal having a frequency corresponding to the rotation of the capstan motor 7 supplied from the frequency generator 8, and the generated servo signal is transferred to the capstan via the amplifier 6. It is supplied to a motor 7 to control the driving of the capstan motor 7 to control the traveling speed of the magnetic tape.

The signal processing section 5 includes, for example, two mono-multi vibrators 15 and 16, a bootstrap section 17, and a sampling section 18, as shown in FIG.

The first mono-multi vibrator 15 includes:
The output of the phase comparator 3 amplified by the amplifier 4 and FIG.
The output FG of the frequency generator 8 shown in FIG. The first monostable multivibrator 15, for example, as shown in FIG. 6 (b), generates a pulse which rises period T ₁ from the rising of the output FG of the frequency generator 8,
The generated pulse is transmitted to a second monomultivibrator 16.
Is supplied to the bootstrap unit 17. This figure 6
Pulse width T ₁ of the pulse shown in (b) is determined by the output of the phase comparator 3 is supplied through the amplifier 4.

The bootstrap section 17 generates, for example, a sawtooth wave shown in FIG. 6C from the rising to the falling of the output of the first monomultivibrator 15.

On the other hand, the second monomultivibrator 16
It is the first preset between rising pulse of a predetermined time T ₂ from the fall of the output of the monostable multivibrator 15 generates and supplies the sampling unit 18.

The sampling section 18 synchronizes with the falling edge of the second mono-multivibrator 16, for example, as shown in FIG.
The output of the bootstrap unit 17 is held during the period shown in (e), and the held output of the bootstrap unit 17 is output as, for example, a servo signal shown in FIG.

That is, the servo signal output from the sampling unit 18 is determined by the ratio between T ₁ and T ₂ ,
Since T ₂ is a predetermined value and T ₁ is determined by the comparison output of the phase comparator 3 as described above, the servo signal having a voltage corresponding to the comparison output of the phase comparator 3 is supplied to the amplifier. 6 to a capstan motor 7.

In this capstan servo system, as described above, the capstan motor 7 is driven in accordance with the comparison output with the CTL signal supplied from the phase comparator 3, and the running of the magnetic tape is controlled. ing.

Further, this capstan servo system has a CT
A clog detection unit 9 for detecting the presence or absence of an L signal; a frequency divider 10 for dividing the output frequency of the frequency generator 8; and a CTL reproducing head 1 amplified by the output of the frequency divider 10 and the amplifier 2. And a switch 11 for changing over the output of

The frequency divider 10 outputs the output of the frequency generator 8 at the time of steady reproduction in which the CTL signal shown in FIG. 7C is 30 Hz and the CTL signal shown in FIG. Assuming that the frequency is 360 Hz, the output frequency of the frequency generator 8 is divided by 12 to generate a signal having a frequency of 30 Hz, which is the same as the frequency of the CTL signal, as shown in FIG. 7B.

The frequency divider 10 is reset by a CTL signal reproduced at the time of steady reproduction. As shown in FIGS. 7 (b) and 7 (c), the frequency divider 10 The rise of the output of the detector 10 coincides with the rise of the CTL signal.

Then, the clog detection unit 9 performs the
The presence or absence of a CTL signal is detected from the reproduced output of the reproducing head 1. If no CTL signal is detected, the switch 11 is switched to supply the output of the frequency divider 10 to the phase comparator 3.

That is, the phase comparator 3 includes the frequency divider 1
From 0, a signal having a frequency obtained by dividing the output frequency of the frequency generator 8 by 12 is supplied. Based on the comparison output of the phase comparator 3, the signal processor 5 outputs the output of the frequency divider 10 and the reference signal REF. The capstan motor 7 is adjusted so that the phases match.
To control the rotation of In other words, the clog detection unit 9
When the CTL signal is not detected, the rotation speed of the capstan motor 7 is controlled to be constant, and the control for keeping the running speed of the magnetic tape constant is performed.

Thus, in this digital VTR,
Even when the CTL signal is not detected, the running speed of the magnetic tape can be maintained at substantially the same speed as during normal reproduction.

In this digital VTR, the head rotation speed control system is, specifically, as shown in FIG. 8, for example, a switch 20 that is switched by the output of the above-described clog detection unit 9 and a head drive motor 21. A frequency generation unit 22 that outputs a signal having a frequency corresponding to the rotation speed of
A frequency divider 23 for dividing the output frequency of the frequency generator,
A comparator for comparing the output of the frequency divider with a signal supplied via the switch; and a motor drive unit for driving the head drive motor based on the output of the comparator. The rotation speed of the rotary head is controlled based on a signal supplied from the switch 20.

The switch 20 has a reference signal REFN having the same frequency as the rotational speed of the rotary head during recording.
And a reference signal REFD having a frequency twice as high as the rotation speed of the rotary head during recording. Note that the reference signal RE
The phases of the FN and the reference signal REFD are controlled in synchronization with the CTL signal when the CTL signal is detected.

When the CTL signal is detected, the clog detecting section 9 outputs the reference signal REFN to the comparing section 24.
When the CTL signal is not detected, the switch 20 is switched so that the reference signal REFD is supplied to the comparison unit 24.

The comparing section 24 compares the frequency of the signal supplied from the switch 20 with the frequency and phase of the output of the frequency divider 23 and supplies a comparison output to the motor driving section 25.
Drives the head drive motor 21 based on the comparison output from the comparison unit 24.

That is, in this digital VTR, C
When the TL signal is detected, the rotation speed of the rotary head is controlled so as to be equal to the rotation speed at the time of recording, and the CTL is controlled.
When no signal is detected, the rotation speed of the rotary head is controlled to be twice the rotation speed during recording.

Thus, in this digital VTR,
When the CTL signal is detected, the rotary head performs one scan on one inclined track, and when the CTL signal is not detected, the rotary head performs multiple scans on one inclined track. Scanning is performed.

In this digital VTR, the data reproduction system is, for example, as shown in FIG.
And a SY for detecting synchronization information and the like from the reproduced output of the rotary head 31 amplified by the head amplifier 32.
An NC / ID detection unit 33, a buffer 34 for storing data reproduced based on the synchronization information and the like detected by the SYNC / ID detection unit 33, and a controller 35 for controlling the buffer 34 and the like are provided.

The data of the helical track reproduced by the rotary head 31 is supplied to the SYNC / ID detection unit 33 via the head amplifier 32, and the SYNC / I
The data is stored in the buffer 34 based on the synchronization information and the like detected by the D detection unit 33.

The data reproducing system is provided with a buffer 34
A video data reproducing unit 36 that reproduces video data from the data stored in the video data unit, an error processing unit 37 that performs processing such as error correction and error correction on the video data reproduced by the video data reproducing unit 36, A digital / analog converter 38 for converting the video signal into a video signal;
A video signal is formed from the data stored in the storage device 4, and the formed video signal is output.

Further, the data reproducing system includes an audio data reproducing section 39 for reproducing audio data from the data stored in the buffer 34, and error correction and error correction for the audio data reproduced by the audio data reproducing section 39. And the like, and a digital / analog converter 41 for converting audio data into an audio signal, forming an audio signal from the data stored in the buffer 34, and outputting the formed audio signal. It is supposed to.

Further, the rotary head 31 is, for example, shown in FIG.
As shown at 0, two pairs of heads H1, H2, H3, H
4 for recording and reproducing helical tracks with these heads H1 to H4. The head width of each of the heads H1 to H4 is, for example, about 50 μm or less, and is wider than 39 μm, which is the track pitch of a helical track for recording data.

The heads H1 to H4 are
1, H3 and heads H2, H4 are each 180 degrees,
The head H1 and the head H2 are arranged so that the angle between them is 4.22 degrees.

By the way, in this digital VTR, recording of two helical tracks is performed by two heads every half rotation of the head drum.
Data is recorded by a channel recording method.

The reproduced output of the heads H1 to H4 is switched by a switch or the like and supplied to the above-described head amplifier 32.

For this reason, the heads H1 and H3 and the head H
2 and H4 are attached to the head drum with a height difference of about 37 μm in the axial direction of the head drum.
Then, the track pitch becomes 39 μm based on the running of the magnetic tape during recording and the angle difference between the head H1 and the head H2.

The head gaps of the heads H1 and H3 have an azimuth angle of 15 degrees with respect to the helical track, and the head gaps of the heads H2 and H4 have an azimuth angle of -15 degrees with respect to the helical track. I have.

In this digital VTR, data is encoded by so-called mirror square coding in which the DC component of the encoded data becomes 0, and is recorded on a helical track.

For this reason, in a digital VTR, when reproducing data of a helical track, data interference between adjacent tracks is extremely reduced.

Further, in the digital VTR, the head width of the heads H1 to H4 is wider than the track pitch as described above, so that there is a certain margin for a track error during reproduction.

Here, the heads H1, 3 are A heads, the helical recorded by the A head is A track, the heads H2, 4 are B heads, and the helical recorded by the B head is B track. FIG. 11 shows a trajectory for a half rotation of the rotary head 31 at the time of steady reproduction in which the CTL signal is detected, for example, as shown in FIG.
The A head traces on the A track, and the B head traces on the B track.

Here, when the above-mentioned head clog occurs and the above-mentioned CTL signal is not detected, as described above, the running speed of the magnetic tape is controlled so as to be substantially the same as that during the normal reproduction, and the rotating head 31 is rotated. Is 2 at the time of recording
It is controlled to double.

A trajectory for one rotation of the rotary head 31 at this time is illustrated, for example, as shown in FIG.
1 obliquely traces the first half of the track A on the locus T1, the head H2 obliquely traces the first half of the track B on the locus T2, and then the head H3 traces the locus T
In 2, trace the second half of track A diagonally,
The head H4 obliquely traces the latter half of the B track on the locus T3.

As described above, the heads H1 to H1
4 are wider than the track pitch, the heads H1 to H4 actually have the trajectories T1 to T4 shown in FIG.
An area wider than 3 is traced.

Since the heads H1 and H3 are A heads, the reproduction levels of the B tracks having different azimuth angles are negligibly low, and the heads H2 and H4 are B heads having the A track having different azimuth angles. The playback level is negligibly low.

If the heads H1 to H4 trace about half the length of the helical track in the vertical direction, a sufficient reproduction level for reproducing data recorded on the helical track can be obtained.

For this reason, in the state shown in FIG.
The head H1 reproduces the first half of the track A on the locus T1, the head H2 reproduces the first half of the track B on the locus T2, the head H3 reproduces the track A on the locus T2, and the head H4 reproduces the track B on the locus T3. To play.

That is, in this state, the tracks A and B
Are reproduced in duplicate, but all the data of tracks A and B are reproduced.

The trajectory of the rotary head 31 is the same as that shown in FIG.
Even when the tracking is shifted by about half the track pitch from the tape running direction from the state shown in FIG. 2, the head H1 obliquely traces the first half of the A track on the locus T1, and the head H2 tracks the B track on the locus T2. , The head H3 obliquely traces the latter half of the track A on the locus T2, and the head H4 obliquely traces the latter half of the track B on the locus T3.

At this time, the head H1 reproduces the first half of the track A on the locus T1, the head H2 reproduces the first half of the track B on the locus T2, and the head H3 reproduces the latter half of the track A on the locus T2. On the trajectory T3, the head H4 reproduces the latter half of the track B.

That is, even in this state, all the data recorded on the tracks A and B are reproduced.

As described above, this digital VTR records data on a helical track even if tracking is deviated if the tape running speed is almost equal to that during normal reproduction and the number of rotations of the rotary head 31 is twice or more that of recording. All of the data can be reproduced.

The data of the helical track reproduced in this manner is supplied to the above-mentioned data reproduction system, and is supplied to the SYNC / ID detection unit 33 via the head amplifier 32. Then, the SYNC / ID detection unit 33 extracts an ID pattern constituting a sync block of the helical track.

The SYNC / ID detector 33 stores data reproduced by the rotary head 31 in the buffer 34 for each sync block based on the extracted ID pattern.

Further, the SYNC / ID detection unit 33
The duplication of the sync block is monitored based on the extracted ID pattern, and the data of the duplicated sync block is invalidated and is not supplied to the buffer 34. That is, the SYNC / ID detection unit 33 supplies the buffer 34 with data without duplication. The data reproduction system reproduces data without duplication in this way.

The controller 35 of the data reproducing system described above.
Supplies the video data of the data stored in the buffer 34 to the video data reproducing unit 36 and the audio data to the audio data reproducing unit 39 based on the ID pattern.

The video data and the audio data reproduced by the video data reproducing unit 36 and the audio data reproducing unit 39 are subjected to error correction and error correction in error processing units 37 and 40, respectively. /
The analog / digital converters 38 and 41 perform digital / analog conversion and output the video and audio signals.

As is clear from the above description, in this digital VTR, when the CTL signal is not detected due to the head clog or the like, the number of rotations of the rotary head 31 is set to twice that at the time of recording to reproduce data. , All data recorded on the helical track can be read.

The data reproduced at this time is invalidated based on the ID pattern as described above, and accurate data without duplication is output to the video data reproducing unit 3.
6 and the audio data reproducing unit 39.

As a result, in this digital VTR, even if the CTL signal is not detected due to a head clog or the like generated by the oxide film particles and the like separated from the magnetic tape adhering to the head gap of the CTL reproducing head 1, Video and audio can be played.

In the above embodiment, SYNC / ID
Although the duplicated data is invalidated based on the ID pattern extracted by the detection unit 33, the SYNC / ID
The detection unit 33 is connected to the rotary head 31 via the head amplifier 32.
The controller 35 controls the reading of data from the buffer 34 based on the ID pattern of the data stored in the buffer 34, and stores the data without duplication in the video data. Even when the data is supplied to the reproducing unit 36 and the audio data reproducing unit 39, accurate video and audio reproduction without duplication can be performed similarly to the above-described embodiment.

In the above-described embodiment, when the CTL signal is not detected, the rotational speed of the rotary head 31 is set to twice the rotational speed at the time of recording.
13, for example, as shown in FIG. 13, a configuration including four heads H1 ′ to H4 ′ arranged at positions different from each other by 90 degrees with respect to the above-described four heads H1 to H4 may be adopted.

In this case, unlike the above-described embodiment, C
The number of rotations of the rotary head 31 is controlled so that the number of rotations of the rotary head 31 when the TL signal is not detected is equal to the number of rotations at the time of recording. It is controlled so as to be doubled.

At this time, the trajectory for a half rotation of the rotary head 31 is the same as that in FIG. That is, the head H
No. 1 obliquely traces the first half of the track A on the locus T1, and the head H2 obliquely traces the first half of the track B on the locus T2. Then, the head H1 'moves on the locus T2 and the head H3 in the above-described embodiment. alike,
Track A is traced diagonally, and head H2 'is traced
3, in the same manner as the head H4 in the above-described embodiment, B
Trace the track diagonally.

That is, with such a configuration,
As in the above-described embodiment, all data recorded on track A and track B can be reproduced.

However, at this time, the heads H1, H
2 and the data reproduced by the heads H1 'and H2' are different from the above-described embodiment, since there is an overlap of the period of 1/4 rotation of the rotary head 31, two data SYs are provided in the data reproduction system.
It is necessary to provide an NC / ID detection unit. If the two SYNC / ID detectors control the timing of storing data in the buffer 34, the configuration after the buffer 34 of the data reproducing system may be the same as that of the above-described embodiment. By controlling the reading of the data from the DUT 34, the duplicated data can be invalidated, and accurate video and audio reproduction without duplication can be performed.

[0098]

In the reproducing apparatus according to the present invention, when the control signal is not detected by the control signal detecting means as described above, the control means controls the tape running control means so that the magnetic tape runs at a constant speed. In addition, the head rotation speed control means is controlled so that the rotation speed of the rotary head is twice or more than that during recording, and the data reproduction means reproduces data based on the identification information during reproduction output of the rotary head. Even if the control signal cannot be reproduced, the data recorded on the inclined track can be reproduced without duplication.

In the reproducing apparatus according to the present invention, when the control signal is not detected by the control signal detecting means as described above, the control means controls the tape running control means so that the magnetic tape runs at a constant speed. In addition, the head number control means is controlled so that the number of heads used for reproducing the rotary head is twice or more than that for recording, and the data reproducing means reproduces data based on the identification information during reproduction output of the rotary head. Thus, even if the control signal cannot be reproduced, the data recorded on the inclined track can be reproduced without duplication.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an outline of a recording track standard of a D-2 format which is a format of a magnetic tape reproduced by a digital VTR to which the present invention is applied.

FIG. 2 is a diagram for explaining an outline of one helical truck in the D-2 format.

FIG. 3 is a diagram for explaining an outline of one sync block of the D-2 format.

FIG. 4 is a block diagram showing a configuration of a capstan servo system constituting a digital VTR to which the present invention is applied.

FIG. 5 is a circuit diagram showing a configuration of a signal processing unit constituting the capstan servo system.

FIG. 6 is a waveform chart for explaining the operation of the signal processing unit.

FIG. 7 is a waveform chart for explaining the operation of the frequency divider forming the capstan servo system.

FIG. 8 is a block diagram showing a configuration of a head rotation speed control system constituting the digital VTR.

FIG. 9 is a block diagram showing a configuration of a data reproduction system constituting the digital VTR.

FIG. 10 is a diagram showing a configuration of a rotary head constituting the digital VTR.

FIG. 11 is a diagram for explaining the operation of the rotary head during steady reproduction.

FIG. 12 is a diagram for explaining the operation of the rotating head when the CTL reproducing head crogs.

FIG. 13 is a diagram showing another configuration of the rotary head constituting the digital VTR.

FIG. 14 is a block diagram showing a configuration of a capstan servo system of a conventional VTR.

[Explanation of symbols]

 Reference Signs List 1 CTL reproducing head 2, 4, 6 amplifier 3 phase comparator 5 signal processing unit 7 capstan motor 8, 22 frequency generator 9 clog detection unit 10, 23 frequency divider 11, 20 switch 15, 16 mono multivibrator 17 boot Strap section 18 Sampling section 21 Head drive motor 24 Comparison section 25 Motor drive section 31 Rotating head 32 Head amplifier 33 SYNC / ID detection section 34 Buffer 35 Controller 36 Video data reproduction section 37, 40 Error processing section 38, 41 Digital / analog conversion Device 39 audio data playback unit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/782-5/783 H04N 5/91-5/956 G11B 15/467

Claims (3)

(57) [Claims] 1. A magnetic tape having an inclined track on which data is recorded with identification information added for each predetermined length unit and a longitudinal track on which a control signal serving as a tape running reference is recorded is reproduced and reproduced. A rotating head for reproducing data recorded on the inclined track, a fixed head for reproducing a control signal recorded on the longitudinal track, and the fixed head. Control signal detection means for detecting the presence or absence of a control signal from the reproduction output of the magnetic tape; tape travel control means for controlling the travel of the magnetic tape; head scan control means for controlling the rotation head to scan the inclined track; The tape running control means based on the detection output of the control signal detecting means And control means for controlling the head scanning control means, and data reproduction means for reproducing data from the reproduction output of the rotary head based on identification information during reproduction output of the rotary head, wherein the control means comprises: When the control signal is detected, the tape drive control means is controlled so that the travel of the magnetic tape is controlled based on the control signal reproduced by the fixed head, and the rotary head is connected to one inclined track. The head scanning control means is controlled so as to perform one scan with respect to the tape. When the control signal is not detected, the tape traveling control means is controlled so that the magnetic tape runs at a constant speed.
A reproducing apparatus, wherein a head scanning control means is controlled so that the rotary head performs a plurality of scans on one inclined track. 2. The head scanning control means controls scanning of the rotating head with respect to the inclined track by controlling the number of rotations of the rotating head. The control means controls the scanning when the control signal is detected. Controlling the head scanning control means so that the number of rotations of the rotary head is equal to the number of rotations for performing one scan on one inclined track. When no control signal is detected, the rotation of the rotary head is controlled. 2. The head scanning control unit according to claim 1, wherein the number of rotations is controlled to a number of rotations for performing a plurality of scans on the inclined track.
The playback device as described in the above. 3. The rotating head has a plurality of heads which is a multiple of the number of heads used for performing one scan on one inclined track, and the head scanning control means is used for reproduction. By controlling the number of rotating heads, the scanning of the rotating head with respect to the inclined track is controlled.When the control signal is detected, the number of rotating heads used for reproduction is controlled. The head scanning control means is controlled so that the number of heads performs one scan for one inclined track, and when the control signal is not detected, the number of the rotating heads used for reproduction is reduced. 2. The reproducing apparatus according to claim 1, wherein the head scanning control means controls the number of heads for performing a plurality of scans on the inclined track.