JPS61273787A - Monitoring method for movement extent of tape - Google Patents

Abstract

PURPOSE:To position and stop a tape speedily at a target position and to retrieve the target position by counting the number of tracks that a head moves across and scans by using the envelope waveform of a playback signal reproduced by the head, and calculating the movement extent of the tape from the counted value. CONSTITUTION:The envelope waveform of the playback signal reproduced by the head is used to count tracks that the head scans across, and the counted value and the time required for every turn of the head are used to calculate the movement extent of the tape per hour. Further, the target position is retrieved by stopping the movement of the tape when the tape movement extent becomes equal to the distance between the target position and current tape position before the start of the tape movement. A control part 18 monitors the tape movement extent Ta to feed the tape until Ta=Tt when Tanot equal to Tt and stops the feeding of the tape when Ta=Tt, thus retrieving the target position automatically. Consequently, position retrieval is performed on an hour basis by the simple constitution without recording any new signal on the tape.

Description

[Detailed Description of the Invention] <Industrial Application> The present invention relates to a method for monitoring the amount of tape movement in a magnetic recording/reproducing device, and is particularly applicable to a method for automatically searching for a predetermined position on a tape. Concerning quantity monitoring method.

<Prior Art> In a video tape recorder (VTR) or a rotating head type digital audio tape device @ (R-DAT), two recording/reproducing heads are provided on a rotating drum (cylinder) at an interval of 180 degrees, and The magnetic tape is run while being obliquely in contact with the cylindrical surface of the rotating drum, so that the running locus of each head is inclined with respect to the longitudinal direction of the tape, and the running locus of each head alternates one track at a time. During recording and reproduction, the two heads are alternately switched to record signals on the magnetic tape or to read and reproduce signals from the magnetic tape. In addition, in a VTR, the magnetic tape is wound around a rotating drum 180 degrees and running, so each head alternately contacts the magnetic tape 180 degrees each time the rotating drum rotates 180 degrees to record or play back. It will be done. In addition, in R-DAT, the magnetic tape is wound around a rotating drum at 90 degrees while running, so each head alternately wraps the magnetic tape 90 degrees each time the rotating drum rotates 180 degrees.
Recording or reproduction is performed by contacting the terminal for 00 minutes at a time.

However, in such conventional magnetic recording and reproducing apparatuses, there was no effective method for monitoring the amount of tape movement at the time of fast forwarding or rewinding. Therefore, the beginning of the tape is 1/2
In inch VTRs, this is done by recording a dedicated signal on the control track and detecting this signal, or by detecting a silent portion of the audio track. Also, in the R-DAT, like a CD device (compact disk device), the beginning of the tape is found using the time code and track number information included in the sub-coding recorded on the tape.

<Problem to be solved by the invention> However, with cueing methods that use a dedicated cueing signal or a silent part of an audio track, it is difficult to search for the position where the cueing signal is recorded or the position of the silent part. In other words, it is only possible to cue at these positions, and there is a problem in that it is not possible to search for a cue signal or any desired position other than the silent portion and stop the tape at that position.

In addition, with the method of using the time code and track number information included in subcoding, the signal cannot be reproduced unless the relative speed between the head and the magnetic tape is the same as during normal recording and reproduction. There is a problem in that the servo circuit that drives the reels becomes complicated.

From the above, an object of the present invention is to monitor the amount of tape movement in a simple manner during fast forwarding and rewinding, so that the tape can be positioned and stopped at a commanded target position at high speed (in other words, An object of the present invention is to provide a tape movement amount monitoring method (which can search for a target position).

Means for Solving Problems> The present invention records signals on the magnetic tape or extracts signals from the magnetic tape by feeding the magnetic tape in the longitudinal direction of the tape and rotating the head while tilting it with respect to the longitudinal direction of the tape. This is a method for monitoring the amount of tape movement in a magnetic recording and reproducing device that reads and reproduces data. The envelope waveform of the reproduction signal reproduced by the head is used to count the number of tracks scanned across by a rotating head, and the count value and one revolution of the head are calculated. Calculate the amount of tape movement in units of time using the hit time. Further, the search for the commanded target position is performed by stopping the movement of the tape when the tape movement amount becomes equal to the distance between the target position and the tape current position before the start of tape movement. This type of magnetic recording/reproducing device performs azimuth recording. Therefore, when the first head scans across each track, the reproduction signal from the track recorded by the first head and another second head has a significantly higher voltage than the reproduction signal from the track recorded by the head. descend. Due to this lick, the envelope waveform of the reproduced signal becomes larger or smaller for each track. That is, when a head scans across tracks by fast-forwarding or rewinding, the reproduced signal becomes large for the track recorded by the scanning head, and becomes small for the track recorded by a head other than the scanning head. . Therefore, by counting the number of times the envelope waveform of the reproduced signal exceeds a predetermined level, the number of tracks crossed can be determined, and using the number of tracks and the time required for one rotation of the head during recording, the number of tracks can be calculated in units of time. The amount of tape movement can be determined.

<Embodiment> Azimuth recording is performed in a rotating head type magnetic recording/reproducing device. That is, recording is performed with the gap of the first head tilted by θ degrees with respect to the vertical direction of the track, and the gap of the second head tilted by θ degrees in the opposite direction with respect to the gap of the first head. As a result, even if the first head reproduces a track recorded by the second head, the reproduction output is greatly attenuated due to azimuth loss, and similarly, the second head reproduces the track recorded by the second head.
Even when a track recorded by the head is reproduced, the reproduction output is greatly attenuated due to azimuth loss.

Therefore, when the head scans across each track by fast forwarding or rewinding, the envelope waveform of the reproduced signal becomes larger or smaller for each track.

That is, when scanning across tracks, the reproduced signal becomes large in the track recorded by the head during scanning, and becomes small in the track recorded by a head other than the head during scanning.

Therefore, by counting the number of times the envelope waveform of the reproduced signal exceeds a predetermined level, the number of tracks crossed can be determined.

Hereinafter, the tape movement amount monitoring method of the present invention will be explained with reference to the drawings.

Fig. 1 is a block diagram of an apparatus for implementing the method of the present invention;
The figure is a waveform diagram of each part of FIG. 1, and FIGS. 3 and 4 are head locus explanatory diagrams.

In Fig. 1, numeral 11 is a rotating drum (cylinder), and two recording/playback heads l are placed at an interval of 180' from each other.
la and llb are provided. In the case of a VTR, the magnetic tape MT is wound around the cylindrical surface of the rotary drum 11 more than 1,800 times and is run, so each head l
la and llb alternately contact the magnetic tape MT 1800 times each to perform recording or reproduction. Heads lla, 1 for the magnetic tape MT during recording or reproduction.
The locus (track) of 1b has a pattern inclined in the longitudinal direction of the tape, as shown in FIG. However, T1 in the figure
is a track by the first head l1m, and T2 is a track by the second head. Also, during fast forwarding, the rotating head l
la, llb alternately scan across each track as shown by thick solid lines and dotted lines in FIG. 3(A), and similarly alternately scan across each track during rewinding as shown in FIG. 3(B). and scan. However, Fig. 3(A).

In (B), the thick line iTA is the head trajectory caused by the first head lla, and the dotted line TB is the head trajectory caused by the second head 11b.

On the other hand, in the case of R-DAT, the magnetic tape MT is wound around the cylindrical surface of the rotary drum 11 900 times and is run, so each head lla, llb alternates each time the rotary drum 11 rotates 180 degrees. Recording and reproduction are performed by contacting the magnetic tape 90' at a time. Then, the heads lla, l are attached to the magnetic tape MT during recording or reproduction.
As in the case of a VTR, the locus (track) of lb becomes a pattern inclined in the longitudinal direction of the tape as shown in FIGS. 4(A) and 4(B). However, T1 in the figure is the first head 11a.
One track, T2, is a track by the second head. Also, during fast forwarding, the rotating heads lla and llb alternately scan across each track as shown by the thick solid lines and dotted lines in FIG. alternately scan across each track.

However, in FIGS. 4A and 4B, the thick solid line TA is the head trajectory of the first head lla, and the dotted line TB is the head trajectory of the second head llb.

That is, in R-DAT, each head only contacts the magnetic tape 1/4 turn (=90°) per rotation of the rotating drum, so the track in section 1a is scanned by head lla, and the track in section 1c is scanned by head lla. scanned by llb, but in interval 1b.

Track Id is not scanned by any head. From the above, the R-DAT shown in Fig. 4 is compatible with the VTR shown in Fig. 3.
In this case, the number of tracks scanned across by the head becomes 1/2.

Returning to FIG. 1, 12 is an envelope detector which detects the signal (reproduction signal) R8 read from the magnetic tape MT by the first and second radars lla and llb to generate an envelope waveform signal EVS. Incidentally, since the envelope EV of the reproduced signal R3 alternately increases and decreases with the track pitch as shown in FIG. 2, the envelope detector 12 outputs an envelope waveform signal having a peak every two tracks as shown in FIG. EVS is output. 13 is a slice level setting section, and fast forward (FF
), a predetermined slice level ■S is output in accordance with the rewind (REW). In this way, by changing the slice level depending on fast forwarding or rewinding, the relative speed between the magnetic tape MT and the head changes, and the envelope waveform signal EVS changes.
Even if the peak value changes, the peak can be identified well in the process described later. A comparator 14 compares the envelope waveform signal EVS and the slice level vS, and generates a high-level pulse signal PSG while the envelope waveform signal value is 78 or more. 15 is a pulse signal PS generated within a predetermined sampling period Ts.
16 is a buffer register that temporarily stores the counted value N of the counter 15; 17 is a reset pulse RP that resets the counted value of the counter 15;
A reset circuit such as a mono-multi or the like generates a signal, and 18 is a control section composed of a microcomputer.

Next, a method for monitoring the amount of tape movement during fast forwarding or rewinding will be described.

If the tape movement amount monitoring request signal TMM is generated, the control unit 1
8 performs a reset g817 to generate a reset pulse R3 and clear the contents of the counter 15 to zero.

After that, the counter 1 during a predetermined sampling period Ts.
5 counts the pulse signal PS generated from the comparator 14. Note that since the pulse signal PS is generated when the envelope waveform (i-th EVS) reaches a slice level of 78 or higher, the number of pulse signals PS is 1/2 of the peak number of the envelope waveform signal EVS, in other words, the number of tracks scanned across.

The control unit 18 causes the count value N of the counter 15 to be transferred to the buffer register 16 every predetermined sampling period Ts, and also causes the reset circuit 17 to clear the contents of the counter 15 to zero. - After that, the control unit 18 calculates the number N, which is 1/2 of the number of tracks scanned across by each head, using the following formula N+N -hN (the initial value of N is zero)... (1)
At the same time, in the case of a 1/2 inch VTR, the tape movement amount Ta is calculated using the following formula (% formula %). However, in equation (2), T is the time required for one revolution of the rotary drum 11 during recording.

In addition, in the case of R-DAT, 1/1 of one rotation of the rotating drum
Since the signal can only be read during two rotations, the number N, which is 1/2 of the number of tracks, is 1/4 of the actual number of tracks, so instead of formula (2), 2-N-T-hTa
- Calculate the tape movement amount Ta using (3).

The above is the method for monitoring the amount of tape movement during fast forwarding or rewinding. Next, the position search process will be explained.

The distance 1111 (distance in time unit) from the current position to the target position is determined from the target position setting section on the operation panel (not shown).
) and press the search button.

It is assumed that the distance is set as a plus value in the fast-forward direction and as a minus value in the rewind direction.

The control unit 18 stores the input distance glTt in the built-in memory MEM, and also causes the reset circuit 17 to generate a reset pulse RP by pressing the search button to clear the contents of the counter 15.

The control unit 18 also checks the sign of the distance, and if it is positive, it issues a fast forward command FFC, and if it is negative, it issues a rewind command R.
Generates WC and inputs it to the tape drive section.

Thereafter, the control unit 18 performs the tape movement amount monitoring process described above to monitor the tape movement amount Ta and checks whether Ta=Tt.

Then, if Taf:Tt, the tape is fed until Ta=Tt, and when Ta=Tt, the tape feeding is stopped, and the target position is automatically searched.

In the case of R-DAT, highly accurate position searches cannot be performed because there is a period when the head does not cross the track. However, by using the above position search method together with a search method using time code, etc., it is possible to First, a rough position search is performed by running the tape using the method described above, and then a precise position search is performed by reading the time code when the tape approaches the target position, thereby making it possible to perform a high-speed and highly accurate position search.

As mentioned above, two recording/playback heads are mounted on a rotating drum.
Although the present invention is applied to VTRs and R-DATs arranged at 0° intervals, the present invention is not limited to such cases, but can also be applied to systems having 4 heads, and is generally applied to rotary heads that perform azimuth recording. This can be applied to a type of magnetic recording/reproducing device.

<Effects of the Invention> According to the present invention, the number of tracks scanned across by the rotary head is counted using the envelope waveform of the reproduction signal reproduced by the head, and the count value and the head 1
The amount of tape movement is calculated in units of time using the time per rotation, and the amount of tape movement is monitored. When the tape becomes equal, the movement of the tape is stopped and the target position is searched, so the amount of tape movement can be easily monitored during fast forwarding and rewinding, and without recording new signals on the tape. Location search in time units can be performed with a simple configuration.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an apparatus for implementing the method of the present invention;
The figure is a waveform diagram of each part of FIG. 1, and FIGS. 3 and 4 are head locus explanatory diagrams. 11...Rotating drum, lla, llb...head, 12
...Envelope detector, 13..Slice level R constant m, 14.Comparator, 15..Counter, 16..Baku core register, 17..Reset circuit, 18..Control unit patent applicant
Alpine Co., Ltd. agent
Patent Attorney Chiki Saito

Claims (3)

[Claims] (1) Tape in a magnetic recording and reproducing device that records signals on the magnetic tape by feeding the magnetic tape in the longitudinal direction of the tape and rotates the head while tilting it with respect to the longitudinal direction of the tape, or reads and reproduces signals from the magnetic tape. In the movement amount monitoring method, the number of tracks scanned across by the head is counted using an envelope waveform of a reproduction signal reproduced by the head, and the movement amount of the tape is calculated from the count value. Quantity monitoring method. (2) The tape movement amount monitoring method according to claim (1), wherein the tape movement amount is calculated in units of time using the count value and the time required for one rotation of the head during recording. (3) Claim (1) characterized in that the tape movement is stopped when the tape movement amount becomes equal to the distance between the commanded target position and the tape current position before the start of tape movement. Or the tape movement amount monitoring method described in paragraph (2).