JPH10124960A - Tracking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tracking device capable of precisely tracking also for a recording medium edited for insertion. SOLUTION: By a circuit 17 of video system, a sampling pulse having a phase in exact timing with the time of reproducing the exclusive tracking area where is formed on a part of the inclined track of a magnetic tape, by rotary head R for the tracking reproduction is produced from a reproduced signal of a reproducing head P, thereby the envelope of a reproduced RF signal of the rotary head R is sampled and held by a sample-and-hole circuit 16. The rotation of a capstan 5 is controlled based on a tracking error signal obtained by this sampling and holding operations and the phase comparison result obtained by comparing the phase of a reference signal with that of a reproduction control signal. The exculsive tracking area is not rewritable on the editing for insertion, and the tracking is carried out so that the lower end of the head coincides with the lower end of the track.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tracking device, and more particularly to a tracking device in a helical scan type VTR that causes a rotary head to scan following an inclined track on a recording medium.

[0002]

2. Description of the Related Art As a conventional tracking device applied to a helical scan type VTR, for example, a device using both control tracking and envelope detection is known. In other words, this conventional tracking device uses a rotating head to record an information signal such as a video signal in the form of an RF signal having a constant amplitude. A tracking error signal obtained by comparing the phase of a reproduction control signal with a reference signal at the time of reproducing a recorded signal of a magnetic tape having a recording track (control track) of a control signal of a constant period recorded in a direction. Controls the running phase of the magnetic tape, controls the running phase of the magnetic tape so as to maximize the average value of the signal level of the reproduced RF signal from the inclined track, and causes the rotary head to scan following the inclined track.

According to this conventional tracking apparatus, since the control signal recorded on a control track different from the inclined track is used, there is an advantage that stable tracking can be obtained without being affected by the inclined track pattern. is there. The running speed of the magnetic tape is controlled, for example, by controlling the rotation of the capstan motor by a bridge circuit or the like so as to keep the back electromotive voltage of the capstan motor constant. Further, not only at the time of reproduction but also at the time of recording, for example, tracking control is performed by an error signal obtained by comparing the phase of a vertical synchronization signal in a recorded video signal with a signal synchronized with the rotation of the capstan motor. VT
For R, there is not only the tracking control by the capstan servo described above but also a drum servo for controlling the rotation of the rotary head. However, since it is not related to the present invention, its description is omitted.

[0004]

However, in the above-mentioned conventional tracking apparatus which uses the envelope of a reproduced RF signal for generating a tracking error signal, an insert for recording another information signal later in a group of recorded tracks is used. At the time of editing, it is common that a recorded track and a track recorded later for insert editing partially overlap and the track width changes, and the envelope of the reproduced RF signal of the insert-edited track is changed to the recording track. The accuracy is poor because it cannot be said to correspond exactly to the position.

In the conventional tracking device, the envelope level of the reproduced RF signal is averaged to obtain a tracking error signal. However, one inclined track is not straight but usually slightly meanders (so-called track bending). Therefore, it is difficult to achieve the best tracking with the tracking that maximizes the average value of the envelope level of the reproduction RF signal.

On the other hand, in a conventional tracking device for controlling the position of the rotary head at a position where the maximum value of the envelope level of the reproduced RF signal is obtained, it is not always possible to control the position to the best tracking position in consideration of insert editing.

[0007] The present invention has been made in view of the above points,
An object of the present invention is to provide a tracking device capable of performing tracking with high accuracy even on a recording medium on which insert editing has been performed.

It is another object of the present invention to provide a tracking device capable of performing the best tracking even on a recording medium on which tracks having different head widths are recorded.

Another object of the present invention is to provide a tracking device capable of appropriately tracking a recording medium having a curved track.

[0010]

In order to achieve the above-mentioned object, the present invention achieves the above-mentioned object by fixing an inclined track in which an information signal is recorded in the form of an RF signal having a constant amplitude by a recording rotary head and a control signal having a constant period. When a recorded signal on a tape-shaped recording medium on which a control track recorded by a control head is formed is reproduced, a tracking-only signal is recorded on a part of the inclined track in a tracking device that causes a reproducing rotary head to follow and scan the inclined track. A recording means for recording and forming a tracking-only area, which is not rewritten during insert editing, by a recording rotary head, and a reproduction time of the tracking-only area based on a signal reproduced from an inclined track by a reproducing rotary head. That generates a sampling pulse with a phase corresponding to Loose generating means, delaying the reproduction by the reproducing rotary head, reproducing the recording RF signal of the inclined track by using the recording rotary head for reproduction, detecting the envelope level thereof, and detecting the envelope level by the detecting means. Sampling and holding means for sampling and tracking the envelope detection signal with a sampling pulse and outputting a tracking error signal, and a comparison result obtained by comparing the phase of a control signal and a reference signal reproduced by a control head from a control track, Based on the output tracking error signal of the sampling and holding means, a control signal generating means for generating a control signal, and a control means for controlling the running of the tape-shaped recording medium by the output control signal of the control signal generating means,
The tracking is performed so that the envelope level of the reproduction RF signal in the tracking-only area becomes a predetermined level.

According to the present invention, an RF reproduced from a tracking-only area which is not rewritten during insert editing.
So that the envelope level of the signal is at a predetermined level
Since tracking is performed, even a tape-shaped recording medium on which insert editing is repeated is not affected by a change in the track width of the inclined track after insert editing.

Also, in the present invention, the above-mentioned tracking-dedicated area is formed at least at three positions near the start end, near the center, and near the end of the inclined track. It is possible to obtain an envelope level of the reproduced RF signal that exactly corresponds to the recording trace.

Further, according to the present invention, the lower end of the trailing head of the recording rotary head when the envelope level of the reproduction RF signal in the tracking-only area is used as the reproducing rotary head is the lower end of the inclined track recorded by the following head. Since the tracking is performed so as to be at a level that matches with, even if the data is reproduced by a device having a different head width, tracking can be appropriately performed.

[0014]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of a tracking device according to the present invention, and FIG. 2 is a schematic diagram of a main portion of FIG. 1 and a signal waveform diagram for explaining operation. In FIG. 1, a rotating drum 1 is rotatably provided on a fixed drum 2, and a recording and tracking reproducing head R and a reproducing head P are provided on a rotating surface of the rotating drum 1 which faces away from the fixed drum 2. ing.

The heads R and P will be described in more detail. As shown in the plan view of FIG. 2A, the recording and tracking reproducing heads R are provided opposite to each other as indicated by R1 and R2. Further, as shown by P1 and P2, the reproducing heads P are provided opposite to each other and provided at 90 ° adjacent to the recording and tracking reproducing heads R1 and R2 (FIG. 1). In the drawing, the heads R and P are illustrated as being adjacent to each other at an angle smaller than 90 ° for convenience of illustration.)

Although the heads R1, R2, P1 and P2 are not shown, they are substantially at the same position in the rotational direction and different in the height direction. Consists of a pair of different leading and trailing heads. Each head R1, R2, P1 and P2
Of the pair of heads, the leading heads have the same azimuth angle, and the trailing heads have the same azimuth angle.

The recording and tracking reproducing heads R1 and R2 and the reproducing heads P1 and P2 are rotated integrally with the rotary drum 1 at a predetermined rotation speed by a drum motor (not shown). The rotational phase of the rotating drum 1 is detected by a known drum pulse generating means 3, and the detected pulse is input to a microcomputer 4, and a head switching pulse synchronized with the rotational phases of the recording and tracking reproducing heads R1 and R2. It is generated as a head switching pulse HIDR synchronized with the HIDP and the rotational phase of the reproducing heads P1 and P2.

Although not shown in FIG. 1, a magnetic tape as a recording medium is obliquely mounted on
It is wound over an angle range of 0 °, and is nipped by a capstan 5 and a pulley (not shown) so as to travel at a constant speed in a certain direction. Then, as in the conventional case, the control head 6 in which the control pulse synchronized with the vertical synchronization signal of the recording video signal is fixed is provided on the magnetic tape.
A control track is formed on the side edge along the longitudinal direction of the tape to record the data.
2 is similar to a conventional VTR in that an information signal such as a video signal is converted into digital data, for example, and is recorded in the form of an RF signal having a constant amplitude by sequentially forming tracks inclined with respect to the longitudinal direction of the magnetic tape. It is.

However, in this embodiment, FIGS.
As shown in (B) and (F), each inclined track 21 tracks a total of three places: a region 22a near the beginning of the track (entrance), a region 22b near the center of the track, and a region 22c near the end of the track (exit). Dedicated area (IT
The feature of I) is that a tracking-only signal is recorded. This tracking-only signal is a signal of constant amplitude modulated with data indicating a tracking-only area. When the tracking-only signal is newly recorded, the signal is combined with the digital data in a time-series manner and recorded.

However, these three tracking-only areas 22a, 22b and 22c are not rewritten during insert editing. This is because if insert editing is repeated, the insert recording track 28 is often recorded at a position shifted from the original track 21 as shown in FIG. This increases the track width and makes it impossible to determine the exact tracking position.

The inclined tracks on which information signals such as video signals are converted into digital data by the heads R1 and R2, for example, and recorded in the form of RF signals having a constant amplitude are formed by the preceding heads having different azimuth angles from each other as described above. Are recorded in parallel by the trailing head. FIG. 4 shows two tracks 21a1 and 21b1 recorded in one scan on the magnetic tape 23, and two tracks 21a2 and 21b2 recorded in the next scan.

Next, the operation of this embodiment will be described. In FIG. 1, a magnetic tape (not shown) is used during reproduction.
The control signal reproduced from the control track is amplified by the reproduction amplifier 7 and shaped by the waveform shaping circuit 8, and then input to the phase comparison circuit 10 in the microcomputer 4, where the reference signal from the input terminal 9 The phase is compared with the signal. At this time, the phase comparison circuit 10
An initial value is input from the tracking circuit 12. The phase error signal output from the phase comparison circuit 10 is supplied to a capstan servo circuit 11, converted into a control voltage, and then power-amplified by a motor driver 13 and applied to a capstan motor that rotates the capstan 5. And controls its rotation phase.

On the other hand, the RF signal reproduced from the magnetic tape by the recording and tracking reproducing heads R1 and R2 is amplified by a reproducing amplifier 14, and then supplied to an envelope detecting circuit 15 to be envelope-detected. The envelope detection signal is supplied to a sample and hold circuit 16, sampled and held by a sampling pulse input from a video system circuit 17 described later, and then converted into a digital signal by an A / D converter 18. And supplied to the RF tracking circuit 12. As a result, the RF tracking circuit 12
And outputs a target value corresponding to the envelope level of the reproduced RF signal.

The above circuit constitutes a circuit using both the control tracking method and the so-called RF envelope hill climbing. As shown in FIG. Is scanned, the envelope level of the reproduced RF signal at that time is the maximum as shown by 30 in FIG. 6, but the reproduction head P or R as shown by 27 in FIG.
The more the scanning position is shifted from the track center, the lower the envelope level of the reproduced RF signal of the reproducing head P or R at that time is, as shown in FIG.

Therefore, in the circuit of the control tracking method, when the tracking position is shifted from the center position, the optimum tracking position for the inclined track is set by observing the change in the envelope level of the reproduced RF signal.

Here, in this embodiment, the tracking position is not the position where the envelope level of the reproduced RF signal becomes the maximum, and the lower end of the following head 24 to be reproduced is recorded by the following head as shown in FIG. This is the position that coincides with the lower end of the track (the following track) 21b1. In order for the trailing head to track to this lower end position,
The envelope can be realized by controlling the envelope of the reproduced RF signal to a level slightly lower than the maximum level at the center position as indicated by 31 in FIG.

By doing so, the width of the head varies, and its attachment to the rotating drum 1 is based not on the center but on the lower end of the head. A position where the lower end of the head coincides with the lower end of the following track is an appropriate tracking position for all heads. The reason why the lower end of the following track is used is that the upper end and the lower end of the preceding track and the upper end of the following track are overwritten by another track and cannot be recognized.

Also, in this embodiment, the envelope of the reproduced RF signal used for tracking is neither the maximum value nor the average value, and as shown in FIGS. 3 and 2B and 2F, three envelopes are used. The envelope of the RF signal reproduced from only the tracking-dedicated regions 22a, 22b and 22c is used. That is, the RF signal schematically shown in FIG. 2C reproduced by the reproducing head P (P1, P2) is supplied to the video system circuit 17 in FIG. 1 and demodulated here. The video system circuit 17 is provided by the microcomputer 4 as shown in FIG.
FIG. 2E shows the falling or rising position of the head switching pulse HIDP of the reproducing heads P1 and P2 shown in FIG. A period T until the tracking-dedicated signal SPAP is reproduced from the first tracking-dedicated area 22a is measured.

Subsequently, the video system circuit 17 supplies the falling or rising position of the head switching pulse HIDR of the tracking reproducing head R (R1, R2) shown in FIG. As shown in FIG. 2 (J), a sampling pulse j1 is generated at a timing delayed from the timing at which one of the read heads R1 and R2 is located at the track start end of the inclined track by the above-described measurement period T.
This sampling pulse j1 is generated when one of the tracking reproducing heads R1 and R2 reproduces the first tracking-only area 22a shown in FIG.

Further, the first tracking-only area 22
Since the time from “a” to the second tracking-only area 22b and the time from the third tracking-only area 22c are known, the video system circuit 17 continues with FIG.
As shown by j2 and j3 in (J), a sampling pulse is generated and output corresponding to the reproduction time of the second tracking-only area 22b and the reproduction time of the third tracking-only area 22c.

As described above, the video system circuit 17 knows the position of the tracking-only area 22a by pre-reading with the reproducing head P (P1, P2), and thereafter (for example, after several tens of tracks), the tracking reproducing head R (R1 , R2) to generate a sampling signal of the reproduced RF signal to be reproduced.

As a result, the sample and hold circuit 16 shown in FIG.
The detected signal shown in FIG. 2 (H) obtained by detecting the envelope of the reproduced RF signal shown in FIG. 2 (G) is sampled with the sampling pulse shown in FIG. 2 (J), and is sampled until the next sampling pulse is input. By repeating the operation of holding the level, a tracking error signal as shown in FIG. The tracking error signal is converted into a digital signal by the A / D converter 18 and then supplied to the RF tracking circuit 12 in the microcomputer 4.

As described above, in this embodiment, instead of superimposing the tracking-only signal on another information signal,
Since the recording and reproduction are performed in the dedicated area, the tracking dedicated areas 22a, 22b and 22c are not rewritten even when the recording signal of the magnetic tape subjected to insert editing is reproduced, so that an accurate tracking position can be detected. Also, the tracking-only areas 22a, 22b and 2
Since 2c is located at the entrance, the center, and the exit of the track, an appropriate tracking position can be detected even when the track is bent.

The present invention is not limited to the above embodiment. For example, the area where the tracking-only signal is recorded may be other than three.

[0036]

As described above, according to the present invention,
By performing tracking so that the envelope level of the RF signal reproduced from the tracking-only area which is not rewritten at the time of insert editing becomes a predetermined level, even for a tape-shaped recording medium on which insert edit is repeated, the insert edit is performed. Since it is not affected by the change in the track width of the inclined track, tracking can be performed with high accuracy on the recording inclined track of the tape-shaped recording medium on which insert editing is repeated.

According to the present invention, the above-mentioned tracking-dedicated area is formed at least at three positions near the start end, near the center, and near the end of the inclined track. Since the envelope level of the reproduced RF signal corresponding to the trace can be obtained accurately, tracking can be appropriately performed even on an inclined track having a curved track.

Further, according to the present invention, the lower end of the trailing head of the recording rotary head when the envelope level of the reproduction RF signal in the tracking-only area is used as the reproducing rotary head is recorded by the trailing head. Since the tracking is performed so that the level matches the lower end of the recording head, tracking can be properly performed even when the reproduction is performed by a device having a different head width, so that the best tracking can be performed even in the compatible reproduction as compared with the related art.

[Brief description of the drawings]

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

FIG. 2 is a schematic plan view showing a head arrangement of a main part of FIG. 1 and a signal waveform diagram for explaining operation of FIG. 1;

FIG. 3 is a diagram for explaining three tracking-dedicated areas of the inclined track according to the present invention.

FIG. 4 is a diagram showing an example of a recording track pattern to be tracked in the present invention.

FIG. 5 is a diagram showing each example of a head position with respect to an inclined track.

FIG. 6 is a diagram illustrating a relationship between a tracking position and an envelope level of a reproduction RF signal.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 rotating drum 2 fixed drum 3 drum pulse generating means 4 microcomputer (control signal generating means) 5 capstan (control means) 6 control head (control signal generating means) 10 phase comparison circuit 11 capstan servo circuit 12 RF tracking circuit 15 Envelope detection circuit (detection means) 16 Sample and hold circuit (sampling and hold means) 17 Video system circuit (sampling pulse generation means) 18 A / D converter 21, 25 Inclined tracks 21a1, 21a2 Previous track 21b1, 21b2 Next track 22a, 22b, 22c Tracking dedicated area 24, 26, 27 Head scanning position P, P1, P2 Reproducing head (reproducing rotary head) R, R1, R2 Reproducing head for recording and tracking (revolving head for recording) Head HIDP reproducing head switching pulse HID recording and a head switching pulse for the tracking reproducing head

Claims (3)

[Claims] 1. A tape-shaped recording in which an inclined track in which an information signal is recorded in the form of an RF signal having a constant amplitude by a recording rotary head and a control track in which a control signal having a constant period is recorded by a fixed control head are formed. In a tracking device for causing a reproducing rotary head to follow and scan the inclined track when reproducing a recorded signal of a medium, a tracking-only signal is recorded on a part of the inclined track, and is not rewritten during insert editing. Recording means for forming a tracking-only area by the recording rotary head; and generating a sampling pulse having a phase corresponding to a reproduction time point of the tracking-only area based on a signal reproduced from the inclined track by the reproducing rotary head. Sampling pulse generating means for performing A detecting means for reproducing the recording RF signal of the inclined track by using the recording rotary head for reproduction with a delay from the reproduction by the raw rotary head, and detecting an envelope level thereof, and an envelope detection detected by the detecting means. Sampling and holding means for outputting a tracking error signal by holding after sampling the signal with the sampling pulse, and a comparison result obtained by comparing the phase of a control signal and a reference signal reproduced by the control head from the control track. A control signal generating means for generating a control signal based on an output tracking error signal of the sampling and holding means, and a control means for controlling the running of the tape-shaped recording medium by an output control signal of the control signal generating means. Having said trucking Tracking device envelope level of the reproduced RF signal of the dedicated region is characterized by tracking to a predetermined level. 2. The tracking device according to claim 1, wherein the tracking-dedicated area is formed at least at three positions near a start end, near a center, and near an end of the inclined track. 3. The control means controls the running of the tape-shaped recording medium according to the tracking error signal,
When the envelope level of the reproduction RF signal in the tracking-only area is used as a reproduction rotary head, the lower end of the trailing head of the recording rotary head coincides with the lower end of the inclined track recorded by the subsequent head. 2. The tracking device according to claim 1, wherein the tracking is performed.