JPH07320348A - Tracking controller - Google Patents

Tracking controller

Info

Publication number
JPH07320348A
JPH07320348A JP6109304A JP10930494A JPH07320348A JP H07320348 A JPH07320348 A JP H07320348A JP 6109304 A JP6109304 A JP 6109304A JP 10930494 A JP10930494 A JP 10930494A JP H07320348 A JPH07320348 A JP H07320348A
Authority
JP
Japan
Prior art keywords
track
means
control
tracking
error
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP6109304A
Other languages
Japanese (ja)
Inventor
Harushige Nakagaki
Naozumi Sugimura
春重 中垣
直純 杉村
Original Assignee
Hitachi Ltd
株式会社日立製作所
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Ltd, 株式会社日立製作所 filed Critical Hitachi Ltd
Priority to JP6109304A priority Critical patent/JPH07320348A/en
Priority claimed from DE1995117509 external-priority patent/DE19517509C2/en
Publication of JPH07320348A publication Critical patent/JPH07320348A/en
Pending legal-status Critical Current

Links

Abstract

PURPOSE:To pull in a rotary magnetic head to a required track quickly and facilitate the accurate tracking by detecting the scanned track position of the rotary magnetic head corresponding to a track on which variable speed reproduction data are recorded and controlling in accordance with a track number error value. CONSTITUTION:In the variable speed reproduction, if a tape running speed reaches a required multiplied speed, a control means turns the contact of a switch 12 from (a) to (b). A track error detecting means 15 detects a block address from a data row reproduced through a reproduced signal processor 13 and compares the detected block address with a block address table and calculates the discrepancy between the present scanned track and the required variable speed reproduction track and outputs an error signal. A phase control means 17 starts the pull-in control of the phase so as to make the error signal zero. Then, if a head scanning phase reaches a phase one track before the required phase, an identification signal is outputted to the means 16 from the means 15 and the contact of the switch 12 is turned from (b) to (c) to perform the tracking control.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a consumer digital VTR for recording / reproducing a compressed video signal by using a rotary magnetic head, and in particular, information for variable speed reproduction at an arbitrary speed faster than normal reproduction is a rotary magnetic field. The present invention relates to a tracking control method suitable for performing variable speed reproduction of a magnetic tape recorded in a distributed manner at each track position according to a scanning locus of a head.

[0002]

2. Description of the Related Art Consumer digital VTRs use image compression technology to reduce the amount of data recorded on a magnetic tape. The so-called MPEG method is generally used as an example of the image compression technique.

In the MPEG system, since the video is constructed by utilizing the difference between the frames, the continuity of the data of the preceding and following frames is lost when the high speed reproduction is performed. Therefore, the video should be decoded from this data. I can't.

Therefore, as a high-speed VTR playback method utilizing image compression by the MPEG system, for example, "FIRST S
CAN TECHNOLOGY FOR DIGITAL VIDEO TAPE RECORDERS (I
EEE Transactions on Consumer Electronics Vol.39, No.
3, AUGUST 1993) "has been proposed.

In this system, in order to enable the decoding of the image even at the time of high speed reproduction, at the time of high speed reproduction at a specific position on the magnetic tape which matches the scanning locus of the reproducing head according to the tape speed of variable speed reproduction. Video data for recording is recorded separately and separately, which enables variable speed reproduction such as search and shuttle reproduction even on a tape compressed and recorded by the MPEG system.

[0006]

However, the variable speed reproduction in the above-mentioned conventional system has the following problems.

That is, since the video data for variable speed reproduction is recorded only on a specific track that matches the head scanning locus, when the normal reproduction state is changed to the variable speed reproduction, or the speed is changed in the variable speed reproduction state. In case of changing, the control must be performed quickly so that the rotary magnetic head can accurately scan the predetermined track on which the video data is recorded. However, the control method for this must be considered and disclosed. Didn't.

An object of the present invention is to solve the above-mentioned problems, and when the normal reproduction state is switched to the variable speed reproduction, or when the speed is changed in the variable speed reproduction state, it is quickly pulled into a predetermined track. Another object of the present invention is to provide a tracking control device capable of accurately tracking a track for variable speed reproduction.

[0009]

In order to achieve the above object, the present invention relates to a high speed running control means for running a magnetic tape at a speed higher than a normal playing speed, and a predetermined track on which variable speed playing information is recorded. Track error detection means for identifying the scan track position of the rotary magnetic head and outputting an error signal according to the scan track error amount and error direction, and the tracking error of the head with respect to the recording track from the reproduction signal of the rotary magnetic head. Tracking error detecting means, switching means for switching and controlling the output of the tracking error detecting means and the output of the tracking error detecting means, and the rotary magnetic head records the variable speed reproduction information on the basis of the output of the switching means. The phase control means for performing tracking control to scan the track being moved and the high-speed A control means for controlling the control means and the switching means is provided, and at the time of variable speed reproduction, first, the tape speed is raised by the high speed running control means, and then a rough search to a desired track is performed by the control signal of the track error detection means. Further, there is a three-stage control configuration in which the tracking control is performed by the tracking error detection means when the head scanning position reaches a predetermined range for a desired track.

[0010]

The track error detecting means detects the scanning position of the head from the block address or the like of the reproduction data, and outputs the error signal of the polarity depending on the track number error amount and the error direction with respect to the track on which the variable speed reproduction data is recorded. Works to output.

The tracking error detection means detects the tracking error of the head with respect to the recording track based on the head reproduction signal, and outputs an error signal having a polarity corresponding to the tracking error amount and the error direction.

Further, the switching means is controlled by the control means and serves to switch the output of the track error detecting means and the output of the tracking error detecting means to supply a control signal to the phase control means, and the high speed running control means is a tape. The speed is controlled so that the vehicle travels at a predetermined variable reproduction speed.

With this configuration, when the variable speed reproduction command is input, the control means starts the control of the high speed running control means, and the tape speed is raised to a predetermined speed by the tape high speed running control by the high speed running control means.

Next, when the tape speed reaches a predetermined speed, the control means detects this and controls the switching means to supply the output of the track error detection means to the phase control means, whereby the track error detection is performed. The head scanning phase is pulled toward the track on which the desired variable speed reproduction data is recorded by the phase control based on the control signal of the means.

Further, when the head scanning position is pulled within a predetermined range of the target track, the control means detects this,
The switching means is controlled to switch the control signal of the phase control means from the output of the track error detection means to the output of the tracking error detection means. As a result, the head is pulled to the track position where the variable speed reproduction data is recorded, and thereafter, the scanning phase of the head is centered on the track where the variable speed reproduction data is recorded by the phase control based on the control signal of the tracking error detecting means. It will be in line.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a tracking control device according to the present invention. In the figure, 1 is a take-up reel for winding a magnetic tape, 2 is a capstan for running the magnetic tape, 3 is a magnetic tape, 4 is a rotary magnetic head, 5 is a supply reel for supplying the magnetic tape, 6
Is a capstan motor that drives the capstan 2, 7 is an FG (tachogenerator) that generates a frequency signal in synchronization with the rotation speed of the capstan motor 6, and 8 is a rotary magnetic head 4
A pre-amplifier for amplifying the signal reproduced by, a motor drive circuit 9 for driving the capstan motor 6, a tracking error detection means for detecting a tracking error from the head reproduction signal, an addition circuit 11, a switching means 12,
Reference numeral 3 is a reproduction signal processing circuit for extracting data from the reproduction signal by a predetermined process, 14 is a high speed running control means for rotating the capstan motor at a high speed during high speed reproduction to run the tape at a high speed, and 15 is recorded with the variable speed reproduction data. Track error detection means for detecting an error in the number of scanning tracks for a certain track, 16 is control means, 17 is phase control means for controlling the scanning phase of the head, and 18 is an output terminal.

Prior to the description of the control operation of the embodiment of FIG. 1, the recording pattern of the variable speed reproduction data of the digital VTR which is the object of the present invention will be described.

The compressed data for variable speed reproduction for one frame is divided into several tracks and recorded according to the head scanning locus according to the reproduction speed. FIG. 2 shows an example of 3x speed and 9x speed in the forward direction.

In the figure, 21 is the scanning locus of the rotary magnetic head 4 during normal reproduction, and 22 and 23 are the scanning loci of the rotary magnetic head 4 during 3x and 9x speed reproduction, respectively.
The blank portion of 4 is the area in which the video data for normal reproduction is recorded, the shaded portion such as 25 is the video data for triple speed reproduction, and the shaded portion such as 26 is 9 An area in which data for double speed reproduction is recorded is shown.

In 3 × speed reproduction, the head obliquely scans 3 tracks as indicated by the locus 22 in FIG. Therefore, in order to perform the 3 × speed reproduction, the data 25 for the 3 × speed reproduction is divided and recorded at a specific position of each of the three tracks in accordance with the scanning locus of the rotary magnetic head 4, and 9 In the double speed reproduction, the rotary magnetic head 4 scans across nine tracks as shown by the locus of 23, so that the data 26 for the nine speed reproduction is divided into nine tracks and recorded.

Further, each track is composed of a plurality of data blocks of several hundreds of bytes, and a block address including a track number / block number is recorded in each data block together with image data.

In FIG. 2, the triple speed in the forward direction, 9
Although an example of double-speed recording is shown, it is of course possible to record information for any reproduction speed if necessary, and it is also possible to record variable speed reproduction data in the reverse (reverse feed) direction as well. Is.

The variable speed reproduction tracking control operation according to the embodiment of FIG. 1 on the tape recorded in the pattern as shown in FIG. 2 will be described below by taking the 9 × speed as an example.

When the user operates a variable speed reproduction command key (not shown), the control means 16 first recognizes this and operates the switching means 12 so that the contact of the switching means 12 is at the position a in the figure. Simultaneously with control, the command speed for variable speed reproduction is identified and input to the high speed traveling control means 14.

As a result, the high speed running control means 14 starts controlling the rotation speed of the capstan motor 6 so that the reproduction speed of the tape 3 becomes the variable speed reproduction speed designated by the control means 16, and the tape speed is in phase. With the control in the non-operating state, the speed is raised to the predetermined speed of 9 times in the manner shown by 32 in FIG. 3 only by the speed control by the high speed traveling control means 14.

The high-speed traveling control means 14 is constructed by sharing a speed control circuit for normal reproduction, for example, and dividing and inputting the capstan FG signal 7 according to the speed ratio during variable speed reproduction. However, the specific contents are well known and will not be described in detail.

Next, when the tape running speed reaches a predetermined 9-times speed at the point t 1 , the control means 16 causes the capstan FG to operate.
This is detected from the frequency of 7 and the switching means 12 is controlled so that the contacts of the switching means 12 are supplied from a to b in the figure, that is, the output of the track error detection means 15 is supplied to the phase control means 17. At this time, since the phase control is inoperative up to the time point t 1 , at the moment when the contact point of the switching means 12 is switched to b in the figure, the scanning locus of the head is for 9 × speed reproduction as shown by 23 in FIG. The data recording track is not necessarily scanned, and the data is deviated from the desired scanning track.

The track error detecting means 15 detects the block address of the reproduced data from the data string reproduced through the reproduced signal processing circuit 13, and the block address table in which the original 9 × speed reproduced data is recorded. By comparison, the deviation between the current scanning track and the desired variable speed reproduction track is calculated, and an error signal corresponding to the number of scanning track errors and the error direction is output.

Therefore, when the scanning locus of the head deviates from the desired track at the time point t 1 , an error signal corresponding to this deviation amount and direction is input from the track error detecting means 15 to the phase control means 17. The phase control means 17 starts phase pull-in control so that this error signal becomes zero, that is, the head scans a desired track.

Reference numeral 33 in FIG. 3 shows the aspect of this phase pull-in control. When the scanning phase of the head is behind the desired scanning phase, the tape speed is accelerated as shown by the solid line. On the contrary, when the head scanning phase is advanced, the head scanning phase is pulled toward the recording track on which the 9 × speed reproduction data is recorded by the tape speed deceleration control as indicated by the broken line.

Next, at time point t 2 , when the head scanning phase reaches one track before the desired phase, the track error detection means 15 outputs this identification signal to the control means 16, and the control means 16 recognizes this. Then, the switching means 12
Switching means 12 so that the contact point of b is changed from b to c, that is, the control signal of the phase control means 17 is switched from the output of the track error detection means 15 to the output of the tracking error detection means 10.
To control.

The tracking error detecting means 10 can be easily realized by using, for example, an area division ATF (Automatic Track Finding) method which is well known in DAT (digital audio tape recorder). The details are omitted because they are not directly related to the gist of the invention, but the error signal is output according to the off-track amount of the head with respect to the recording track and the off-track direction.

Therefore, after the time point t 2, the phase pull-in control (the aspect of tape speed change is 34 in FIG. 3) is performed by the phase control means 12 based on the control signal of the tracking error detection means 10, and thereafter the head is scanned. As shown by 23 in FIG. 2, the locus sequentially scans the center of the track on which the variable speed reproduction data of 9 × speed is recorded.

The control operation of the embodiment shown in FIG. 1 has been described above.

As shown in FIG. 1, the phase pull-in control is divided into two steps of control by the track error detecting means 15 and the tracking error detecting means 10, and the phase pull-in control using the control signal of the track error detecting means 15 is performed up to the target track. After that, the fine phase control using the control signal of the tracking error detecting means 10 is performed because the resolution of the head scanning phase error detection by the track error detecting means 15 is 1.
This is because the track is rough and the head phase pulling speed to the target variable speed reproduction track is increased.

As a result, in the case of performing the variable speed reproduction of the magnetic tape in which the information for the variable speed reproduction of the arbitrary speed faster than the normal reproduction is dispersed and recorded at each track position according to the scanning locus of the rotary magnetic head, The phase can be quickly pulled into the target track, and the information track for variable speed reproduction can be accurately tracked.

By the way, the phase control of the embodiment shown in FIG. 1 is controlled only by the tracking error detecting means 10 once the scanning phase of the head is pulled into the variable speed reproducing track, and therefore, for example, the tape running system. In the case where the phase lock is lost due to external disturbances, etc., there is no restoration function, so the scanning locus of the head deviates from the desired variable speed reproduction track, making it impossible to reproduce the variable speed reproduction information. There are drawbacks.

FIG. 4 is a block diagram showing another embodiment of the tracking control device according to the present invention which solves the above-mentioned drawbacks. In the figure, 19 is an output of the same track error detection means 15 as in FIG. 1 and track error detection means configured to output two systems of error signals which are appropriately attenuated by an attenuator 20, and 30 is a track error detection means. The switching means including the first switching means 31 and the second switching means 32 is shown, and the parts denoted by the same reference numerals as those in FIG. 1 indicate the same things, and their operations are also equivalent.

In the present embodiment, the tracking error detecting means 10 does not completely disable the control at the time of shifting to the phase control by the tracking error detecting means 10 as in the embodiment of FIG. Even in the case where the control by the track error detection means is always maintained in the operating state even during the phase control by the means 10 and the phase lock is released during the variable speed reproduction, the phase pull-in control by the track error detection means is desired. It is possible to return to the track for variable speed reproduction of.

The switching means 30 includes a first switching means 31 for switching between the output of the tracking error detecting means 10 and the error signal of the track error detecting means 15, and an error signal of the track error detecting means 19 via the attenuator 20. Is added to the output of the tracking error detection means 10 and a second switching means, both of which are included in the control means 1.
A control signal from 6 commonly controls the contact positions a, b, and c in the figure.

Similar to the control of FIG. 1, when a variable speed reproduction command is input, the control means 16 first recognizes this and operates the switching means 30 so that the contacts of the switching means 31 and 32 are located at the position a in the figure. Simultaneously with control, the command speed for variable speed reproduction is identified and input to the high speed traveling control means 14.

Next, when the tape running speed reaches a predetermined speed, the control means 16 supplies the contacts of the switching means 31 and 32 to a to b in the figure, that is, the output of the track error detection means 15 to the phase control means 17. The switching means 30 is controlled.

When the head scanning phase reaches one track before the desired phase, the track error detection means 19 outputs this identification signal to the control means 16 and the control means 1
When 6 recognizes this, the contacts of the switching means 31 and 32 are changed from b to c, that is, the control signal of the phase control means 17 from the output of the tracking error detection means 15 to the output of the tracking error detection means 10 and the attenuator 20. So that the output of the track error detection means 19 obtained via
The switching means 30 is controlled.

With the above control, the control by the track error detecting means 19 always works even during the phase control by the tracking error detecting means 10. Therefore, when the phase lock is lost during the variable speed reproduction, the track error detecting means is performed. Since the head scanning locus is pulled back to the original variable speed reproduction track by the phase pull-in control by 19, the reproduction of the variable speed reproduction information does not become impossible due to the tracking deviation as in the embodiment of FIG. 1, and stable tracking is achieved. Can be realized.

The embodiment of the present invention has been described with reference to FIGS. 1 and 2.

In the above embodiment, forward (forward feed)
Although the variable speed reproduction in the directional direction is taken as an example, the present invention is not particularly limited, and it goes without saying that the same can be applied to the variable speed reproduction in the reverse (reverse feed) direction. Further, although the reproduction speed is 3 times or 9 times as an example, the reproduction speed is not particularly limited, and needless to say, variable speed reproduction at an arbitrary speed can be performed. Further, the attenuator is provided in FIG. 4 in order to make the control by the track error detecting means an auxiliary (subordinate) control with respect to the main control by the tracking error detecting means, and it is not particularly indispensable, and is in its configuration. However, the invention is not limited to the independent installation, and it is possible to easily provide the track error detecting means with the function, for example, and various modifications can be easily made within the scope of the present invention.

[0048]

As described above, according to the present invention,
When performing variable speed reproduction of a magnetic tape in which information for variable speed reproduction at an arbitrary speed faster than normal reproduction is distributed and recorded at each track position according to the scanning locus of the rotating magnetic head, the variable speed is changed from normal reproduction to variable speed. Tracking that allows the head scanning phase to be quickly pulled to a predetermined track position when switching to reproduction or when changing the speed in a variable speed reproduction state, and also enables accurate tracking of the variable speed reproduction track. A control device can be provided.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a tracking control device according to the present invention.

FIG. 2 is a diagram showing an example of a recording pattern of variable speed reproduction information.

FIG. 3 is a diagram showing a control aspect of tape traveling speed in the embodiment of FIG.

FIG. 4 is a configuration diagram showing another embodiment of the tracking control device according to the present invention.

[Explanation of symbols]

3 ... Magnetic tape, 4 ... Rotating magnetic head, 6 ... Capstan motor, 10 ... Tracking error detecting means, 12, 3
0, 31, 32 ... Switching means, 14 ... High speed running control means, 15, 19 ... Track error detection means, 16 ... Control means, 17 ... Phase control means, 20 ... Attenuator,

Claims (2)

[Claims]
1. An oblique track is formed on a magnetic tape to record information for normal reproduction, and the information for variable speed reproduction at an arbitrary speed faster than normal reproduction corresponds to the scanning locus of a rotary magnetic head. A tracking control device of a device for reproducing magnetic tape recorded in a distributed manner at each track position, which comprises a high-speed running control means for running the magnetic tape at a speed higher than a normal playback speed, and the variable speed playback information. Track error detecting means for identifying the scanning track position of the rotary magnetic head with respect to a predetermined recorded track and outputting an error signal according to the scan track error, and tracking of the head with respect to the recording track from the reproduction signal of the rotary magnetic head. A tracking error detecting means for detecting an error, an output of the track error detecting means, and an output of the tracking error detecting means. Switching means for switching and controlling the output; phase control means for performing phase control so that the rotary magnetic head scans the track on which the variable speed reproduction information is recorded based on the output of the switching means; A control means for controlling the control means and the switching means is provided, and at the time of variable speed reproduction of the magnetic tape, first, the speed of the magnetic tape is raised by the high speed running control means, and then the tape speed reaches a predetermined value. Based on the error signal of the track error detection means, control of pulling the rotary magnetic head to the track on which the variable speed reproduction information is recorded is started, and the scanning phase of the rotary magnetic head is within a predetermined range of the target position. The switching means is controlled when it reaches the inside, and tracking control of the rotary magnetic head is performed based on the error signal of the tracking error detection means. Tracking control apparatus according to claim.
2. The track error detecting means comprises a predetermined first
Error signal and a second error signal obtained by appropriately attenuating this error signal, and the switching means outputs the tracking error detecting means and the first error of the track error detecting means. First switching means for switching signals, and when the output of the tracking error detecting means is selected by the first switching means, the second error signal of the tracking error detecting means is changed to the tracking error detecting means. Second switching means configured to add to the output of the switching magnetic head. When the scanning phase of the rotary magnetic head reaches within a predetermined range of the target position, the switching means is controlled and the tracking error detecting means is provided. 7. The tracking control of the rotary magnetic head is performed by an addition signal of the error signal of 1) and the second error signal of the track error detecting means. Tracking control apparatus according.
JP6109304A 1994-05-24 1994-05-24 Tracking controller Pending JPH07320348A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP6109304A JPH07320348A (en) 1994-05-24 1994-05-24 Tracking controller

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP6109304A JPH07320348A (en) 1994-05-24 1994-05-24 Tracking controller
DE1995117509 DE19517509C2 (en) 1994-05-13 1995-05-12 Inclined track playback device with tracking control for fast playback of digital information signals from magnetic tapes
KR1019950011786A KR0173860B1 (en) 1994-05-13 1995-05-13 Tracking control in apparatus for fast reproducing digital information signal from magnetic tape
US08/441,703 US5532835A (en) 1994-05-13 1995-05-15 Tracking control in apparatus for fast reproducing digital information signal from magnetic tape

Publications (1)

Publication Number Publication Date
JPH07320348A true JPH07320348A (en) 1995-12-08

Family

ID=14506807

Family Applications (1)

Application Number Title Priority Date Filing Date
JP6109304A Pending JPH07320348A (en) 1994-05-24 1994-05-24 Tracking controller

Country Status (1)

Country Link
JP (1) JPH07320348A (en)

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