JPS60149273A - Variable speed reproduction method of magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To ensure the stable variable reproduction without using any control signal by sampling a tracking error signal with a signal synchronous with a head switch signal in a variable speed reproduction mode and using this sampling output to control a capstan motor. CONSTITUTION:A pilot signal is separated from the video signal supplied through an LPF 20 of a magnetic recording/reproducing device. This pilot signal is multiplied by the reference signal through a beat detecting circuits 21 and 22 for detection of beats of 1H and 3H respectively. These beat levels are compared with each other by a comparator 23, and a tracking error signal 22 is delivered. The signal 22 is applied to a switch 24 and sampled by a sampling pulse 21 to be held by a holding circuit 25. The output of one side of the circuit 25 is applied directly to a changeover switch 27; while the other output of the circuit 25 is applied to the switch 27 after inversion through an inverting circuit 26. These two outputs are selected by a head switch signal HSW. Then an intermittent feed signal 15 of an intermittent feed signal producing circuit 29 and the output of the switch 27 are switched by a switch 28 with a still ON signal 20. Thus the stable variable speed reproduction is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a variable speed reproduction (slow motion reproduction) method for a magnetic recording and reproducing apparatus.

Conventional configurations and their problems In recent years, magnetic recording and reproducing devices (hereinafter referred to as VTRs) have required high-density recording on magnetic tapes (hereinafter referred to as tapes), as well as the need to reproduce video signals from tapes on a regular basis. control technology is also required; for example, the current VH
A four-frequency pilot system has been developed and is being put into practical use as an alternative to the tracking system using control signals used in VTRs such as the 8-system.

And along with this, variable speed playback (slow motion regeneration)
This is no longer possible with conventional means, and new methods are needed.

The conventional control signal system (hereinafter referred to as the CTL system) and the conventional variable speed playback (still, intermittent playback) of this system will be explained using a two-head helical pulse scan system VTR.

FIG. 1 is a diagram of a tape pattern for explaining the CTL method, which is a conventional tracking method.
2 is the normal tape running direction, broken line T111 T1
21 T139 T14... is the center line of the scanning trajectory of the video head during recording, and the CTL is indicated by a black circle.
T111 and T13 are placed at the positions of ll and CTL13, respectively.
Above is a control signal recorded on a control track provided in the longitudinal direction of the tape using a control head when recording a video signal, and this signal is recorded every other scan of the head.

During playback, tracking of the video head is performed based on the control signal. For example, if track T11 is tracked using the CTI&11 signal, then CTL
The track T13 is tracked by the signal.

Incidentally, the tracks of the tape pattern shown in FIG. 1 are actually inclined tracks, but in order to make the explanation easier to understand, they are shown as tracks perpendicular to the longitudinal direction of the tape.

The above is the conventional CTL system, and the variable speed reproduction (still, intermittent feed) system based on this system will be described below.

Figure 2 is a diagram explaining the variable speed playback method using the conventional CTL method, where ■ is a diagram showing the scanning locus of the head, 1 is the tape, and arrow 3 is the progress of the tape when performing intermittent feeding. Direction, dashed line TI2. T131T14 are the scanning loci of the head during recording, and the bold line ST1. Sr1 is the scanning trajectory of the head during still shooting, solid lines a-b with arrows, b
-c, c-d, de.

e - f is a thick line ST1 due to tape movement during intermittent feeding.
The scanning locus when the head moves from the still position to the still position Sr1 is shown, and ■ is a diagram showing the current applied to the capstan motor to perform the still-intermittent feed-still operation. state), startup section (solid line a-b).

between b - = c), constant speed section (between c and d), deceleration section (
d-e, e-f), and a stop section (Sr1 state), ■ is a diagram showing the correspondence between the video head switching signal (hereinafter referred to as H3W) and the above a-f, and ■ is an intermittent When sending,
The tracking error signal obtained in the constant speed section (the CTL
Signal), ■ is a deceleration command signal created from the CTL signal of ■, and the falling edge of this signal applies an applied current for deceleration to the motor.

This will be explained in detail below.

On tape 1 in Figure 2 ■, the video signal is on track T1□I.
T131” is recorded on 14, and now the thick line ST1
Suppose that you are stilling at the position. As shown in FIG. 1, there is no corresponding CTL signal for the scan locus "12" during still recording, and it is track "121 T131.
"14, only T13 has a corresponding CTL signal. When performing intermittent feeding from this state, the motor first receives the H8W signal corresponding to points a-b and b-c of ■, based on the 8 points of ■. Apply accelerating current and move the head from point 8 to a
-b, bjC1C→d, d−+e, e→f. At this time, in the constant speed section where the head scans between c and d, the CTL signal CTL1 corresponding to track "13"
3 is reproduced by the control head as a tracking error signal.

A deceleration command signal (■) is created from this CTL, 3, and the falling edge is delayed by 10 hours, causing the motor to
, e and f to stop the tape. Therefore, the stop position of the head on the tape bump, that is, the position of the thick line 8T2 shown in (■) is the same. determined by

Furthermore, in order to prevent the tape from sagging when the motor decelerates and stops, the stop state is detected by the method described below, and the stop detection signal is used to ensure stable still operation at all times. Figure 2 (■) is a device for detecting motor stoppage; 4 is a capstan motor, 5 is a capstan shaft, 6 is a rotary encoder fixed to the capstan shaft 5 and has multiple holes through which light passes, and 7 is a rotary encoder. 6 is an arrow indicating the forward rotation, 8 is a photointerrupter equipped with two sets of light emitting and receiving elements, ■ is a diagram further specifically explaining the photointerrupter 8, 81. S2 is a light emitting element, R1
, R2 are the light receiving elements corresponding to Sl and S2, respectively, 8 is the detection signal at the photointerrupter 8 when the rotary encoder 6 is rotated in the positive direction (direction of 7), and ■a is the set of Sl and R1. The obtained signal, ■b, is 32. The signal obtained from the group R2, ■ is the photointerface 7 when the rotary encoder 6 is rotated in the opposite direction (opposite direction to 7)
In the detection signal at 8, ■a is 32. The signal obtained by the group R2, and (2) b, is the signal obtained by the group 51-R1.

A method for detecting motor stoppage with the above configuration will be described in detail.

Now, if intermittent feeding is performed in the forward direction (in the direction of the arrow), the light-emitting/receiving elements 51-R1 and 32-R2 of the photointerrupter 8 each detect the signal shown in (2). That is, each hole 8l-R1 of the rotary encoder 6
The set of 82-1't2 is detected earlier than the set of 82-1't2. Here, when applying a deceleration current to the motor to stop it, when it reaches position f in Figure 2, the rotary encoder 6 at that moment changes from forward direction to stop and reverse direction rotation, and the rotary encoder 6 moves in the opposite direction (opposite direction of arrow 7). Then, the light emitting/receiving element 5l- of the photointerrupter 8
Each of the pairs R1 and 82-R2 detects the signal shown in (2).

That is, each hole 82- of the rotary encoder 6 is
The R2 set is detected 8 times earlier than the R1 set.

Therefore, the moment when the signal pattern changes from the signal slam (■) to the signal pattern (2) is determined as motor stoppage detection. Using this motor stop detection, one pulse of current is applied to drive the motor in the forward direction again in order to prevent the tape from sagging when the motor is simply stopped.

This allows for stable stills without tape sagging after intermittent feeding.

However, these methods require the conventional control signal to be recorded on tape, and the new four-frequency pilot method, which does not use control signals, cannot obtain a similar tracking error signal and cannot be used. Can not.

Purpose of the Invention The present invention solves the above-mentioned conventional problems and proposes a method that can stably perform still and intermittent transmission 9 by obtaining a tracking error signal in the same way as in the conventional tracking method even in a tracking method that does not use a control signal. It is something.

Structure of the Invention The present invention records a pilot signal for tracking control during playback by superimposing it on a television signal to be recorded during recording, and during playback, a pilot signal for tracking control during playback is superimposed on a television signal to be recorded, and during playback, a pilot signal for tracking control during playback is recorded, and during playback, the track is played back from recording tracks adjacent to the front and rear of the recording track to be played back. The tracking error signal is detected from the crosstalk signal of the pilot signal.
A magnetic recording and reproducing device that performs reproduction by controlling the relative position between a recording track and a reproduction scanning locus of a reproduction magnetic head, wherein the tracking error signal is synchronized with a head switching signal during variable speed reproduction that repeats still reproduction and intermittent forwarding. This is a variable speed playback method that performs still playback by sampling a signal and controlling a capstan motor with the sampling output, which enables stable variable speed playback (slow motion playback).

DESCRIPTION OF EMBODIMENTS Before explaining the present invention in detail, a tracking method (four-frequency pilot method) that does not use a control signal will be explained first.

FIG. 3 is a diagram of the tape pattern during recording to explain the 4-frequency pilot system, where 1 is the tape, and 2 is the arrow broken line T4, which indicates the tape traveling direction at normal speed. T2.
T3. T4 is the scanning trajectory T1 of the head during recording, and the frequency F1=6.6H (H is the frequency of the horizontal synchronizing signal, in this case means 6.5 times the frequency of H) is T4.
2 has F2=7.5H, T3 has F3=10.6H, and T4 has F4-F9.5H superimposed and recorded on the television video signal.

The four types of pilot signals on the recording tape button are arranged so that when the head scans the recording track to be reproduced, a crosstalk signal of the pilot signal corresponding to the difference between 1H and 3H is obtained from the front and rear adjacent tracks. I'm here. In such a tracking method, a tracking error signal is detected based on the level difference of the crosstalk signal during normal reproduction.

In Fig. 3, if the head is currently reproducing and scanning on track T1, crosstalk signals F2-7.5H from the right and F4-9.6H from the left in the figure are obtained, and these are used as crosstalk signals on the scanning track. By multiplying by signal F1=6.5H, beat signals of 1H1 from the right and 3H from the left can be extracted. Using this, if the 1H bit signal is larger than the 3H bit signal, information is obtained that the tape has shifted to the right, that is, the tape has advanced too much, and conversely, if the 1H bit signal is less than the 3H bit signal, it has shifted to the left. In other words, information is obtained that the tape is too delayed. Also F2. F3. Similar information can be obtained when scanning F4. This information corresponds to a tracking error signal. By controlling the current applied to the capstan motor based on the above information, optimal tracking is made possible during normal playback.

The above is the operating principle of the tracking method that does not use force or control signals.

The variable speed reproducing method of the magnetic recording/reproducing apparatus of the present invention will be explained below.

FIG. 4 is a diagram explaining the still operation of the variable speed playback method according to the first embodiment of the present invention, and 0 is a diagram showing the relationship between the tape slam during recording and the scanning trajectory of the head during methylation. 1 is the tape, arrow 2 is the tape running direction during normal playback, and broken line T1. F2°F3 are the scanning loci of the head during recording, and the three thick lines are.

(2) is a beat signal obtained by multiplying the pilot signal of the recording track specified in advance to be reproduced (in this example, F2 superimposed on track T2) and the pilot signal obtained by scanning the head during still recording. This is a diagram of the created tracking error signal during still time, and shows the level of each point during still time (■). Furthermore, @ is a sample pulse that samples the midpoint of each waveform obtained in ①, SH, SHL, and SHR, and this is the head switching signal (H
8W) is created every % cycle.

Based on the above configuration, the still operation of the variable speed reproduction method of this embodiment will be explained in detail below.

On tape 1 in FIG. 4, a video signal and four-frequency pilot signals F11, F21, and F3 are respectively transmitted to tracks T4. Assume that the image is recorded on T2°T and is currently still at the position of the thick line (e, f). Note that when tracks "11" and "2" are written, they indicate the portion within the solid line surrounding the broken line. At this time, when the head is at position e, F3 = 10.5H is common, and F1 =
e, 5H are regenerated less, and F2 = 6.5H (
By multiplying by the signal of the track to be reproduced by the head during still recording, more 3H beat signals are detected and fewer 1H beat signals are detected. (3H>IH). Similarly, when the head is at the midpoint of #=f, Fl and F3 are reproduced equally, therefore (3H=IH), and conversely, when the head is at position f, Fl is reproduced more and F3 is reproduced less, and therefore ( IH>3H). The relationship between these is shown as (+) if there are many 1H bit signals and (-) if there are many 3H bit signals. This section describes in detail how to perform still control.

The meaning of the 1H and 3H beat signals obtained by processing the reproduced pilot signal is that in this case, if a large number of 1H bit signals are obtained, it means that the head is approaching the recording track T. Conversely, if a large number of 3H bit signals are obtained, it means that the head is approaching the recording track T3 side.

The most ideal still condition is one in which the amount by which the head at point 0 approaches track T3 is equal to the amount by which the head at point f approaches track T1.In other words, the amount by which the head at point f approaches track T1 is equal. Still trajectory of point and head thick line (e
, f) that the midpoints on the top coincide.

Therefore, the still position can be detected by sampling the midpoint between e and f.

As a method of actually controlling still scanning based on this sample value, for example, head switching (H8W) is first used, and a position of % of this half cycle is set as a sampling point. Using this sampling point, the thick line ('a
R, fR) to detect SHR, and if a large number of 3H bit signals are obtained, the motor is controlled to advance the tape in the opposite direction (-) to arrow 2. In this case, SHR is the center of recording track T2. The control is such that it can be approached close to. ), scan the thick lines (eL, fL) to detect S HL , and 1
If a large number of H-bit signals are obtained, the motor is controlled to advance the tape in the same direction (+) as arrow 2 (in this case, SHL is controlled to move closer to the center of recording track T2).

With this, the tape is controlled so that when the sampling point is at SHo or SHR in the 0 diagram, it aims at the "'0" position, that is, the SH point, so in the end, the tape
stops when the midpoint SH of the thick lines (e, f) coincides with the midpoint of the recording track T2.

The above is a case where stills on track T2 are considered, but track T1. T2. The same thing can be said when performing still at T4.

However, in track T2, when the 1H bit signal is detected (+
) forward direction drive and (-) reverse direction drive when 3H bit signal was detected, but in other cases, the results are as shown in Table 1 due to the arrangement of the four-frequency pilot signals on the tape.

Table 1 As described above, according to this embodiment, the beat signal to be used for (+) forward drive is selected as shown in Table 1 depending on the recording track to be reproduced for still recording, and the pilot signal of the recording track is selected. Stable still operation can be performed by multiplying by a pilot signal reproduced during still operation and controlling the motor based on the level difference (tracking error signal) of the obtained beat signal.

Next, a method of performing a frame advance operation by applying the still operation described above will be specifically explained below using FIGS. 5, 6, and 7.

FIG. 6 is a specific circuit diagram explaining the frame advance operation of the variable speed playback method according to the second embodiment of the present invention. Filter (L, P, F,), 21.
22 is a detection circuit that multiplies the extracted pilot signal by the pilot signal (reference signal) included in the recorded track to be reproduced to detect the 1H beat and 3H beat, respectively; 23 is the detected two types of beats; A comparator 24 compares the signal levels, and 24 is a half cycle of the head switching signal (
%H3W), a switch that is turned ON and OFF by a sample pulse created in synchronization with %H3W), 26 is a hold circuit that holds the level value output from the comparator 23 and sampled by the switch 24, and 26 is the output of the hold circuit 26. An inverting circuit that inverts in an analog manner, 2
7 is a changeover switch that determines whether to perform forward drive at the detection beat of 1H or 3H based on the H8W signal, and switches the output of the hold circuit 26 to either normal rotation or inversion, and 28 is a still frame. 29 is an intermittent feed signal generation circuit. .

Hereinafter, the configuration of FIG. 6 of the second embodiment will be explained.
This will be described in detail using FIGS.

FIG. 6 is a signal diagram illustrating the operation during still operation.

When the video signal is input to L, P, F, 20, only the pilot signal is separated, and the separated signal and the reference signal are
By multiplying by the detection circuit of 1.22, 1H and 3H
Each beat of is detected. Furthermore, by comparing these beat levels with a comparator 23, a tracking error signal (2) is output. The tracking error signal shown in (2) is of the same quality as the signal (2) explained in connection with the still control in FIG. Next, the tracking error signal (■) output from the comparator 23 is sent to the switch 24 by the letter sample pulse @ (Sl, 32 + S3 shown t) created at the edge of the half cycle and at the center of the half cycle of the H8W signal [phase]. This value is sampled by the hold circuit 2.
5 to obtain a sample and hold signal O. still,
Sample pulse @ is of the same quality as sample pulse 0 in FIG.

Further, the sample-and-hold signal output from the hold circuit 23 is input to the changeover switch 27 through two routes, one as is and the other through the inversion circuit 26.

Here, by selecting and switching which detected beat is used to drive the tape in the forward direction using the H8W signal as shown in Table 1 above, the output is transmitted to the motor through the switch 28. The operation described above is the operation in the methyl mode, and the switch 28 is switched by setting the still '''ON I+ signal to a high level, and the tracking error signal output from the changeover switch 27 is output during this period.

In addition, tracking error signal ■, sample hold signal O
The signal change shown is a stable still. The intermittent feed signal [phase] is of the same quality as the voltage applied to the capstan motor shown in FIG.

When an intermittent feed command signal is received from a microcomputer and a corresponding circuit, an acceleration command signal @ is created by the falling edge of the H8W signal [phase]. Then, by the falling edge of this acceleration command signal @ delayed by the time tl, an acceleration signal and a deceleration command signal [phase] of the intermittent feed signal [phase] are created, and furthermore, the stillpa ○N'' signal is set to a low level. From now on, the intermittent transmission signal [phase] output from the intermittent transmission signal generation circuit 9 is outputted to the output of the changeover switch 28 shown in FIG.

The acceleration signal of the intermittent feed signal [phase] is output at the next falling edge of the H3W signal as in the conventional example, and then the motor shifts to constant speed operation. Furthermore, a 12-hour delayed falling edge of the deceleration command signal 0 creates a deceleration signal of the intermittent feed signal [phase], and the motor is stopped. At this time, the stop detection of the motor is performed in the same manner as in the conventional example shown in FIGS. And this stop detection signal [phase]
The rise of the signal causes the still "ON" signal to go high. As a result, the tracking error signal at the time of methylation is output again to the output of the changeover switch 28 shown in FIG.

Note that tll''2 is set to an optimal value so that no noise appears on the screen during intermittent feeding.

As described above, according to this embodiment, the intermittent feed operation can be performed by determining t11t2 in advance from the tape feed amount, and simply outputting an intermittent feed signal when necessary. Stable operation can be achieved without using control signals.

As a result of the effects of the invention, in the variable speed reproduction method of the magnetic recording and reproducing apparatus of the present invention, stable still and frame advance can be realized by repeating the still control and intermittent advance operations described above. Further, in the present invention, frame-by-frame feeding in the forward direction has been described, but frame-by-frame feeding in the reverse direction can also be realized using a similar method.

[Brief explanation of the drawing]

Fig. 1 is a diagram explaining the CTL method of the conventional tracking method, Fig. 2 is a diagram explaining the conventional variable speed reproduction method, Fig. 3 is a diagram explaining the 4-frequency pilot method, and Fig. 4 is a diagram explaining the present invention. FIG. 6 is a diagram explaining the still operation of the variable speed playback method according to the first embodiment of the present invention, FIG. FIG. 7 is a signal diagram illustrating the methyl time of the frame-by-frame advance operation of the present invention. FIG. 7 is a signal diagram illustrating the intermittent time of the frame-by-frame advance operation of the present invention. 2o...L, P, F,, 21.22...
・Beat detection circuit, 23...Comparator, 2
4...Switch, 25...Hold circuit, 26...Inverting circuit, 28...Switch, 29...Intermittent feed signal generation circuit . Name of agent: Patent attorney Toshio Nakao and 1 other person8
Forward direction Nobuko Azusa 84 S, - 1 Ill, 5z-1?2 8 ÷ 9 9 One direction detection I q, 5z-P・Imiyamoto 9b 5r-Rr Ill deri Fig. 3 Akira 4 Figure Il Handle $/Il U, So~shi 2゛3 fork J (Signal--
--177H5141-111 Ward 6 1 16 Figure 7

Claims (1)

[Claims] A pilot signal for tracking control during playback is recorded by superimposing it on the television signal to be recorded during recording, and a crosstalk signal of the pilot signal is reproduced from recording tracks adjacent to the front and rear of the recording track to be played back during playback. A magnetic recording and reproducing apparatus detects a tracking error signal from a magnetic recording head and controls the relative position between a recording track and a reproducing scanning locus of a reproducing magnetic head for reproduction, and the tracking error signal is detected during variable speed reproduction that repeats still reproduction and intermittent forwarding. A variable speed playback method for a magnetic recording and playback device, characterized in that still playback is performed by sampling an error signal with a signal synchronized with a head switching signal and controlling a capstan motor with the sampling output.