JP3275433B2 - Intermittent magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intermittent magnetic recording / reproducing apparatus (hereinafter referred to as "time lapse VTR") for intermittently recording and reproducing a video signal, for example, used for monitoring.

[0002]

2. Description of the Related Art In recent years, a time-lapse VTR capable of intermittently recording a video signal on a commercially available ordinary video tape and, for example, recording 720 hours on one tape has been widely used. This is used, for example, to record a video signal from a television camera monitored on behalf of a person at a factory, a construction site, a store, or the like. When an abnormality occurs, the recorded video signal can be reproduced to obtain valuable information.

Hereinafter, an example of such a conventional time-lapse VTR will be described with reference to the drawings.

FIG. 24 is a block diagram showing an example of a conventional time-lapse VTR. Reference numeral 7 denotes a system control means, which is a normal mode in which the normal operation of the time-lapse VTR is performed. Generates a normal mode pulse Ma, a continuous slow mode pulse Mb, and an intermittent mode pulse Mc corresponding to the continuous slow mode in which the vehicle travels and the intermittent mode in which the vehicle runs intermittently, and outputs either normal drive, continuous slow drive or intermittent drive. An operation mode selection signal MS for selecting a mode pulse for the mode is also generated.

[0005] Reference numerals 20 to 23 denote magnetic heads, and 19 denotes a rotary cylinder. The rotary cylinder 19 has a magnetic head 23 having a second azimuth angle opposite to the magnetic head 20 having a first azimuth angle by 180 degrees. And a magnetic head 21 having a second azimuth angle is arranged adjacent to the magnetic head 20, and a magnetic head 22 having a first azimuth angle is arranged 180 degrees opposite to the magnetic head 21. ing. The adjacent magnetic heads 20, 21 and the magnetic heads 22, 23 are respectively double azimuth heads, and such a rotary cylinder 19 is hereinafter referred to as a DA-4 configuration rotary cylinder. Hereinafter, the first azimuth and the second azimuth are referred to as plus azimuth and minus azimuth, respectively.

The system control means 7 also controls a period in which the magnetic heads 20 and 21 contact the magnetic tape 18 wound around the rotating cylinder 19 and travels to perform recording and reproduction, and a period in which the magnetic heads 22 and 23 contact. And outputs a SW30 pulse for distinguishing between recording and reproducing periods.

The servo circuit 10 includes a capstan motor 14
And to drive the cylinder motor 15.
Each drive mode can be switched by the operation mode selection signal MS. 2 is a video signal processing means, 28 is an audio recording and reproducing means, 11 is a CTL switch for switching between a recording CTL (control) signal and a reproduced CTL signal, 1
Reference numeral 2 denotes CTL recording / reproduction control means.

5 is an additional V (vertical) means.
(Vertical) synchronization signal (hereinafter referred to as additional V pulse) AVS
An additional V changeover switch 5a for switching between adding and not adding S, an additional V changing means 5b for changing the additional V pulse AVSS in place of the vertical synchronizing signal in the reproduced video signal, and an additional V pulse AVSS. And an additional V generating means 5c.

Reference numeral 4 denotes a recording / reproducing control means. The recording means 4a, a recording / reproducing switch 4b for switching between recording and reproducing, a head switching switch 4c for switching a magnetic head to be reproduced by SW30 pulse, and an azimuth switching pulse AZP. It comprises an azimuth switch 4d for switching the reproducing magnetic head having the corresponding azimuth angle and an amplifier circuit 4e. 24 is a CTL head for recording and reproducing CTL signals, 25 is a pinch roller, 26
Is a capstan, 16 is a supply reel, 17 is a take-up reel, 27 is an audio magnetic head for recording and reproducing an audio signal, 28 is an audio recording / reproducing means, and 13 is normally in intermittent reproduction drive mode and continuous slow reproduction. An azimuth pulse changeover switch for switching between azimuth changeover pulses AZP 'and AZP in the drive mode, 29 is an input terminal for a recording audio signal, 3
Numeral 0 is an output terminal for a reproduced audio signal.

Reference numeral 33 denotes an azimuth selecting means, which is a comparison / discrimination circuit 3 for determining which of the magnetic heads 20, 21 and which of the magnetic heads 22, 23 has a larger output.
3b and 33c, and a comparison / determination changeover switch 33a that selects an output from the comparison / determination circuits 33b and 33c based on the SW30 pulse. The azimuth selecting means 33 outputs an azimuth switching pulse AZP for always selecting the larger of the output of the reproduced video signal from the magnetic head having a different azimuth angle in the double azimuth head during the continuous slow mode reproduction. Switches the azimuth of the magnetic head.

The magnetic tape 18 is rotated by a rotating cylinder 19.
Motors for operating a tape guide, a reel, a pinch roller, and the like for winding around are not shown.

In such a configuration, when a commercially available 120-minute video tape is used, the rotation speed of the capstan motor 14 is changed from 2 hours in the normal running standard mode (SP mode, track width 59 μm) of the VHS system VTR. For example, for 24 hours, 1
Long time recording such as 20 hours or 480 hours can be performed. Also, capstan 1 slower than normal SP mode
Even in a long time triple mode (EP mode, track width of 19.3 μm) with a speed of 4, a long time recording can be performed in the same manner.

The operation of the time-lapse VTR having the above-described configuration in continuous slow drive will be described.

When the DA-4 component rotary cylinder 19 rotates and the magnetic heads 20 to 23 trace tracks (hereinafter referred to as azimuth tracks) on the magnetic tape 18 on which the video signals are recorded, the tracks having different azimuth angles sequentially.
The video signal is reproduced. At this time, the + (plus) azimuth head 20 and the − (minus) azimuth head 21 and the + azimuth head 22 and the − azimuth head 23 are mounted adjacent to each other (double azimuth head), and the + azimuth head adjacent to each other is mounted. Video signals are simultaneously reproduced from the head and the -azimuth head. The output levels of video signals reproduced simultaneously by two magnetic heads having different azimuth polarities are determined and compared by the comparison and determination circuits 33b and 33c, and azimuth switching is performed such that the magnetic head having the larger azimuth angle of the output is selected. Since the pulse AZP is supplied to the azimuth changeover switch 4d, during continuous slow reproduction, the double azimuth head always selects the magnetic head having the larger azimuth angle of the reproduction output.

That is, if there are more + azimuth parts in the azimuth track being traced,
The azimuth head side is selected. Conversely, if there are more -azimuth parts in the traced azimuth track, the -azimuth head side is automatically selected. As a result, the magnetic head having the higher azimuth angle is always selected. Therefore, for example, when performing continuous slow reproduction on a magnetic tape recorded in different recording modes, the magnetic head accurately traces the azimuth track. The output deterioration due to the impossible state (tracking failure) has been improved, and a screen with little tracking noise can be obtained.

[0016]

As described above, in the conventional time-lapse VTR, when the video signal is reproduced in the continuous slow mode, the larger one of the video signals reproduced by the double azimuth head is always selected and output. However, this method has the following problems.

FIG. 25 shows a case where a magnetic tape recorded in a different recording mode is reproduced in a continuous slow mode.
This shows how the magnetic head traces the azimuth track. However, in the figure, + VTa, + VTb, + V
Tc is + azimuth track, -VTa, -VTb, -V
Tc indicates a -azimuth track, and 109 to 112 indicate magnetic heads tracing the azimuth track.
Since the modes at the time of recording and at the time of reproduction are different, the trajectories of the magnetic head tracing the azimuth track are not parallel. The arrow X in the figure indicates the traveling direction of the magnetic tape, and the arrow Y indicates the trace direction of the magnetic head.

In FIG. 25, if the magnetic head is 11
When tracing is started in the state as shown in 1, the + azimuth head of the double azimuth head is selected, and the video signal is reproduced from the hatched portion of the lower right of 111. Even if tracing continues and the state becomes like 112, the + azimuth head is similarly selected, and good reproduction is performed. On the other hand, when tracing is started in the state shown by 109, the output of the + azimuth head is large at first, and the + azimuth head of the double azimuth head is selected.
The video signal is reproduced in the diagonally shaded area of
In a state like 110, the output of the -azimuth head becomes large, and the azimuth head is switched from the + azimuth head to the -azimuth head in the middle of the trace, and the reproduction is started from the shaded portion rising to the right. This switching is performed instantaneously, and since the level of the video signal is always kept high, no tracking noise is generated.

However, the azimuth track crosses the azimuth track momentarily during the tracing of the azimuth track, and the azimuth track is switched so that the video signal is reproduced from the middle of another azimuth track. May shift. At present, in the VHS and S-VHS color systems, signal processing using line correlation is performed every 1H (H: horizontal scanning period). Therefore, if the timing of reproduced H is shifted, the signal processing is normally performed. There is a problem that color noise occurs in the horizontal direction of the screen.

Also, at the moment when the track changes from a + azimuth track to a −azimuth track during reproduction and in the opposite direction, the synchronization signal shifts by several H, causing the screen to shake. There was a problem. Regarding this problem, for example, in the intermittent reproduction mode, the magnetic head selected at the time of reproduction is known in advance, and switching between magnetic heads having the same azimuth angle until the magnetic head finishes tracing one azimuth track. Conventionally, a method of adding an additional V pulse to a reproduced video signal in accordance with the selection of a magnetic head and correcting a deviation of H has been adopted. However, when reproducing in the continuous slow mode, it is not clearly determined which side of the magnetic head having a different azimuth angle of the double azimuth head is to be selected, and the azimuth track is not traced by the magnetic head. Since the azimuth angle can be switched between different magnetic heads, it is very difficult to predict and correct the azimuth angle. Conventionally, this has not been corrected at all.

This not only occurs during reproduction on a magnetic tape recorded in different recording modes, but also
This also occurs when a magnetic tape recorded in the continuous slow mode is reproduced in the same continuous slow mode, that is, when the azimuth track and the trajectory of the magnetic head tracing the azimuth track are parallel. This will be described with reference to FIG. However, reference numerals 113 to 114 indicate magnetic heads that trace the azimuth track.

In the figure, when tracing is performed as indicated by 113, a + azimuth head in a double azimuth head is selected, whereby good reproduction can be performed. If the reproduction is continued in this state, the magnetic head does not switch in the middle of the trace and the reproduction can be continued satisfactorily. However, actually, the rotation of the capstan motor 14 and the phase of the cylinder motor 15 are slightly changed. Due to the misalignment, the trace position of each magnetic head with respect to the azimuth track is gradually reduced.

As a result, when the same magnetic head traces an intermediate point between the + azimuth track and the −azimuth track as indicated by 114, the output levels of the + azimuth head and the −azimuth head are almost the same, so that the capstan motor 14 And the slight fluctuation of the rotation of the cylinder motor 15, the azimuth head side or the −azimuth head side is selected during the azimuth track tracing. As a result, similar to the above problem, there is a problem that color noise is instantaneously generated on the screen since the magnetic head is switched to a magnetic head having a different azimuth angle across the track momentarily while tracing the azimuth track. In addition, since the track being reproduced is changed from a track being reproduced to a track having another azimuth angle, an H shift of several H occurs at the moment of the change, which causes a problem that the screen shakes. Was. Moreover, it is also difficult to correct the H shift as described above.

An object of the present invention is to solve such a problem and to prevent the occurrence of color noise due to the magnetic head traversing the track and the shaking of the screen due to the H shift during the continuous slow mode reproduction of the magnetic tape, thereby achieving satisfactory slow reproduction. An object of the present invention is to provide an intermittent magnetic recording / reproducing apparatus capable of obtaining an image.

[0025]

In order to achieve the above object, the present invention provides a 1 / n normal slow playback mode.
When driving at twice the speed, the state in which the magnetic head traces the azimuth track is predicted in advance, and resetting is performed each time a CTL signal is reproduced from the magnetic tape, and switching to a magnetic head having a different azimuth angle is performed according to the prediction. When the magnetic head does not trace the azimuth track as expected, for example, when the magnetic tape recorded in a mode different from that during playback is continuously slow-reproduced, etc. Azimuth switching pulse selecting means for selecting and outputting one of n patterns of azimuth switching pulses having different switching timings between magnetic heads having different azimuth angles in order to obtain a slightly better reproduction screen. Is provided.

Also, according to the present invention, when the double azimuth head starts tracing the azimuth track, the envelope levels of the video signals reproduced by both azimuth heads of the double azimuth head are detected and compared, and the envelope level is detected. Envelope comparison azimuth holding means for selecting the larger azimuth head and generating an azimuth switching pulse which keeps tracing to the end of the azimuth track while maintaining the selection of the azimuth head is provided.

Further, according to the present invention, even in the case of continuous slow reproduction, the azimuth switching pulse selection means is selectively output to the additional V-pulse generation means in order to correct the screen fluctuation due to the interval between the two magnetic heads in the double azimuth head. The supplied azimuth switching pulse is supplied.

Similarly, during continuous slow reproduction, in order to correct a screen shift due to a phase shift of a vertical synchronizing signal of a reproduced video signal caused by a shift between a recording start position of an azimuth track and a trace start position of a magnetic head. In addition, the azimuth switching pulse, the continuous slow mode pulse, the SW30 pulse, and 1 /
When the magnetic tape 18 is driven at a speed of n, a continuous slow specifying pulse for specifying n in the continuous slow mode is supplied.

[0029]

The azimuth switching pulse generating means predicts in advance how the magnetic head will trace the azimuth track when reproducing in the continuous slow mode while reproducing the audio signal by the audio signal recording / reproducing means. The azimuth switching pulse selecting means, which can output rills every time a signal is reproduced, selects and outputs n azimuth switching pulses output from the azimuth switching pulse generating means. Thus, for example, the azimuth track is not traced by the magnetic head as predicted in advance, or the azimuth track is traced, as in the case of continuous slow reproduction on a magnetic tape recorded in a different mode. When the trajectory of the magnetic head is not parallel, etc., adjust the timing of the azimuth switching pulse so that the azimuth switching pulse can be obtained so that the azimuth track can be traced by the magnetic head having the same azimuth angle. Can be.

The envelope comparison azimuth holding means selects the larger one of the outputs of the two magnetic heads in the double azimuth head at the moment when the tracing of the track is started, and continues tracing this track to the end without changing the magnetic head. An azimuth switching pulse can be generated. As a result, switching to a magnetic head having a different azimuth angle does not occur during tracing, so that color noise does not occur, and two magnetic fields with double azimuth are obtained even during continuous slow reproduction. It is also possible to correct the screen shaking caused by the head spacing.

The additional V pulse generating means is provided with the supplied SW
From the 30 pulses and the azimuth switching pulse, the vertical synchronizing signal of the reproduced video signal can be changed according to the selected magnetic head to delay or not to delay by 2H.
As a result, it is possible to correct the screen shake caused by the interval between the two magnetic heads of the double azimuth head having different azimuth angles during the continuous slow reproduction.

Similarly, the additional V-pulse generating means includes S
Based on the W30 pulse and the azimuth switching pulse, an additional V synchronization signal output to correct the screen shake generated by the interval of the selected head is added to the SW30 pulse and the azimuth switching pulse, and furthermore, the continuous slow pulse is input. By advancing or delaying the phase of the additional V synchronization signal by a predetermined amount by the mode signal and the continuous slow designation pulse, the video signal corresponding to the deviation from the recording track end of the reproduction trace start point of the magnetic head on the tape is measured. The phase shift of the vertical synchronization signal can be corrected.

[0033]

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

FIG. 1 is a block diagram showing an embodiment of an intermittent magnetic recording / reproducing apparatus according to the present invention, wherein 1 is an input terminal,
2 is a video signal processing means, 3 is an output terminal, 4 is a recording / reproduction control means, 4a is a recording means, 4b is a recording / reproduction switching switch, 4c is a head switching switch, 4d is an azimuth switching switch, 4e is an amplifier, and 5 is an addition. Means, 5a is an additional V switch, 5b is replacement means, 5c is additional V (vertical synchronization signal) generating means, 6 is an input terminal, 7 is system control means, 8 is azimuth switching pulse generating means, 9 is azimuth switching pulse Selection means, 10 is a servo circuit, 11 is CTL
(Control signal) changeover switch, 12 is CTL recording / reproduction control means, 13 is an azimuth changeover pulse changeover switch, 14 is a capstan motor, 15 is a cylinder motor, 16 is a supply reel, 17 is a take-up reel, 18 is a magnetic tape, 19 is a rotary cylinder, 20 to 23 are magnetic heads, 24 is a CTL head, 25 is a pinch roller, 26 is a capstan, 27 is a magnetic head for audio, 28 is audio recording / reproducing means, 29 is an input terminal, and 30 is an output terminal. And
Parts corresponding to those in FIG. 25 are denoted by the same reference numerals, and redundant description will be omitted.

In the figure, an azimuth switching pulse generating means 8 and an azimuth switching pulse selecting means 9 are added, and the azimuth selecting means 33 is removed instead of the conventional Timelabs VTR shown in FIG.

The azimuth switching pulse generating means 8 is supplied with a continuous slow specifying pulse SAP for specifying n in the continuous slow mode when the magnetic tape 18 is driven at 1 / n the speed of the normal running from the system control means 7. CTL
“H” (high level) and “L” (low level) are performed n times each from the switching edge of the SW30 pulse to the next switching edge while resetting by the reproduced CTL signal from the changeover switch 11. The azimuth switching pulse which generates one cycle every 2n times is generated while n is continuous, and the order of "H" and "L" is shifted by one time in one cycle, and there are n kinds of patterns. Azimuth switching pulse AZS is generated.

The azimuth switching pulse selecting means 9 selects one of the n types of azimuth switching pulses AZS generated by the azimuth switching pulse generating means 8 and outputs the selected azimuth switching pulse AZP. This selection is made according to the pulse selection signal PSS from the input terminal 6.

The azimuth changeover switch 13 is used in the normal / intermittent reproduction driving mode and the continuous slow reproduction driving mode.
The azimuth switching pulse AZP from the azimuth switching pulse selector 9 and the azimuth switching pulse AZP 'from the system controller 7 are switched by the operation mode selection signal MS.

Except for the above points, it is the same as the conventional time lapse VTR shown in FIG.

Next, the operation of this embodiment will be described.

At the time of recording, the operation is as follows.

The video signal RVS input from the input terminal 1
Is processed by the video signal processing means 2 so that it can be recorded on the magnetic tape 18, and then supplied to the recording / reproduction control means 4, where it is supplied to the magnetic heads 20 to 23 via the recording / reproduction switch 4b and the recording means 4a. , Are recorded on the magnetic tape 18. At this time, the recording CTL signal is also output from the system control means 7, supplied to the CTL head 24 via the CTL changeover switch 11 and the CTL recording / reproduction control means 12, and simultaneously recorded on the magnetic tape 18.

On the other hand, the operation of the servo system is performed as follows.

The normal mode pulse Ma, the continuous slow mode pulse Mb, and the intermittent mode pulse Mc are supplied from the system control means 7 to the servo circuit 10, and one of them is selected by the operation mode selection signal MS, and in the selected mode. Capstan motor 14 and cylinder motor 15
Are driven. In the continuous slow mode, recording is performed while the capstan motor 14 is driven at a speed of 1 / n of the normal mode (standard traveling mode and triple speed mode). In the intermittent mode, the capstan 26 is sent at regular intervals. To record. The audio signal RAS is also input from the input terminal 29 and supplied to the audio head 27 via the audio recording / reproducing means 28, so that the audio signal RAS is simultaneously recorded on the magnetic tape 18. Recording is possible only in the slow mode, and recording is not possible in the intermittent mode in which the magnetic tape 18 is driven intermittently.

A magnetic pattern as shown in FIG. 2 is drawn on the magnetic tape 18 on which such recording has been made. Here, AT is an audio recording track, + VTa, + VTb,
+ VTc is + azimuth track, -VTa, -VTb,
-VTc is the -azimuth track, CT is the recording track of the CTL signal, arrow X indicates the traveling direction of the magnetic tape 18, and arrow Y indicates the trace direction of the magnetic heads 20 to 23, respectively.

Next, a description will be given of the operation at the time of reproduction of this embodiment. As an example, a continuous slow 1/3 speed in which the capstan motor 14 rotates at a speed 1/3 of the rotational speed in the normal EP mode. A case where the magnetic tape 18 recorded in the mode is reproduced in the same continuous slow 1/3 speed mode will be described. In this case, since the mode is the EP mode, the track width is 19.3 μm, and the track width of the magnetic heads 20 to 23 is 30 μm. In this case, the azimuth pulse changeover switch 13 selects the azimuth changeover pulse AZP from the azimuth changeover pulse selecting means 9 according to the operation mode selection signal MS.

In this case, the azimuth tracks + VTa, + VTb, -VTb,.
The locus of each of the magnetic heads 20 to 23 for... Is as shown in FIG. Since both recording and reproduction are driven in the 1/3 speed continuous slow mode, the track and the trajectory of each magnetic head are parallel (the magnetic head moves along the dotted line) as shown in the figure. The magnetic head traces the magnetic tape 18 in the horizontal direction and moves it to 1 /
3, that is, shifts by 6.4 μm. When a certain magnetic head 66 finishes tracing from bottom to top according to the SW30 pulse, the next magnetic head 67 starts tracing from a position shifted by 6.4 μm from the magnetic head 66 as shown in FIG. Therefore, as shown in FIG. 2, tracing is started from a state where the magnetic head 66 just overlaps the + azimuth track + VTa, and the magnetic heads 67 to 7 are sequentially arranged.
As shown in FIG. 1, when tracing each track, by switching each magnetic head in the order of azimuth angles +,-,-,-, +, +, it is possible to always reproduce a large amount of video signals (shaded portions in FIG. 2). ). From this, the azimuth switching pulse AZP from the azimuth switching pulse selecting means 29 for switching the azimuth angle of the magnetic head is, as a whole, as shown in FIG. H may be generated three times, and then “L” may be generated three times in six cycles. However, in FIG. 3, the reset pulse is generated with the positive polarity of the reproduced CTL signal.

In this case, the width of the head track is 30 μm.
FIG. 4 shows the width of the track actually traced by the magnetic head. That is, the trace width is always 17 μm or more, and the azimuth of the magnetic head is not switched during tracing. Therefore, the continuity of H is maintained in one field, and there is no color noise. A good reproduced image can be obtained.

Here, as shown in FIG. 2, the magnetic head is positioned at a certain position of the azimuth track on the magnetic tape 18 (in the case of FIG. 2, like the magnetic head 66, the left edge of the + azimuth track and the left side of the magnetic head). The position where the edge just overlaps)
The CTL signal recorded on the magnetic tape 18 corresponding to the azimuth track is used to detect the
The L signal is fed back to the servo circuit 10 so that the magnetic head accurately traces the azimuth track. That is, as an example, as shown in FIG. 2, when the magnetic head 66 comes to the illustrated position at the moment when the reproduced CTL signal is reproduced, as shown in FIG. 3, the reset pulse is generated at the positive timing of the CTL signal. Is generated and reset, and “H”, “L”,
The azimuth switching pulse AZP of “L”, “L”, “H”, “H” should be generated from the azimuth switching pulse selecting means 9. In this way, the width shown in FIG. 4 can always be secured for the magnetic head to trace the azimuth track.

On the other hand, as shown in FIG. 5, when the SW30 pulse for controlling the rotary cylinder 19 is not synchronized with the reproduced CTL signal (in this case, the capstan motor 1
Azimuth switching pulse selecting means 9 detects the position of the magnetic head using the reproduced CTL signal, and the position of the magnetic head is always determined. Azimuth switching pulse AZP
Therefore, as described below, the deviation can be corrected and a good video signal can always be reproduced. FIG. 6 shows the relationship between the azimuth track and the magnetic head at this time.
Here, 110a to 110l indicate the positions of the magnetic heads.

If a reset pulse is generated and tracing is started from the position 110a, in this case, the rotation of the capstan motor 14 is slightly faster than one-third of the rotation speed in the normal EP mode. Trace while moving slightly more than 1/3 of the width of the azimuth track. For this reason, as shown in FIG. 6, the deviation gradually increases. However, the magnetic heads 110a-110
One cycle is completed as predicted by f (“H”, “L”, “L”, “L”, “H”,
If the trace is further continued, even if the deviation gradually increases, the reset pulse is reset by the reset pulse for five times of the SW30 pulse in the next one cycle, and the magnetic head is returned again. As shown in 110l, since the state returns to the state where it exactly overlaps with the + azimuth track + VT, as shown in FIG. 7, the maximum deviation is only 6.4 μm as compared with the case where it is accurately traced.

Also, as shown in FIG.
The same applies to the case where the rotation of No. 4 is shifted in a direction slightly slower than 1/3 of the rotation speed of the normal EP mode.
In this case, since the reproduction timing of the reproduced CTL signal is late, as shown in one cycle of the magnetic heads 111a to 111g in FIG. The shift in this case is also suppressed to a maximum of about 6.4 μm as shown in FIG.

As described above, in this embodiment, the azimuth switching pulse selecting means 9 always resets by using the reproduced CTL signal to correct the deviation, and each time, "H",
An azimuth switching pulse AZP of "L", "L", "L", "H", "H" is generated. As a result, even when the displacement is maximized, the trace width is secured to 12.9 μm, and the trace width is sufficient for reproducing a video signal, and a good reproduced image is always obtained.

As described above, when the CTL signal is reproduced, if the magnetic head just overlaps the + azimuth track, reset is performed each time, and then "H", "L", "L" , "L", "H", and "H", the azimuth switching pulse AZP generates a good image.

However, in an actual time-lapse VTR,
Due to slight variations in the structure, even when the reproduced CTL signal is reproduced, the magnetic head does not always exactly overlap the + azimuth track. Normally, the position of the magnetic head at the moment when the CTL signal is reproduced is determined by the x value. When recording and reproduction are performed by the same VTR, the x value does not shift, but recording and reproduction are different. When VTR is performed, the x value may be slightly shifted. This will be described with reference to FIG.

In the figure, here, as an example, the instantaneous magnetic head in which the reproduced CTL signal is reproduced is shown in FIG.
It is assumed that the tracing is started from here. In this case, as shown in the figure, each time the CTL signal is reproduced, the reset is performed, and “L”, “L”,
When the azimuth switching pulses AZP of “H”, “H”, “H”, and “L” are generated, the traced area becomes as shown by the hatched portion in FIG.
Traces T and -VT well.

As described above, when the positional relationship between the CTL signal and the magnetic head as shown in FIG. 2 is obtained, and when the positional relationship as shown in FIG. The azimuth switching pulse AZP having a period of 6 times “3” followed by “L” 3 times may be shifted in timing.

FIG. 10 is for explaining the above. That is, suppose that the azimuth switching pulse AZP is generated by the reset pulse as shown in FIG. A, and the azimuth switching pulse AZP is shifted one by one while being synchronized with the SW30 pulse, as shown in b, c, d, e, and f in FIG. By generating six azimuth switching pulses AZS and selectively outputting them, it is possible to cope with set variations.

FIG. 11 shows the azimuth switching pulse generating means 8 of FIG. 1 for generating the six azimuth switching pulses AZS and the azimuth switching pulse selecting means 9 for selecting one of the azimuth switching pulses AZS as the azimuth switching pulse AZP. It is a block diagram which shows one specific example, Comprising: 8a-8d
Is a flip-flop, 8e is an inverter, 8f is SW3
An SW60 pulse generation circuit for generating a SW60 pulse rising at the edge of the 0 pulse, and 8g is a basic pulse pattern generation circuit for generating a reference pulse pattern of an azimuth switching pulse.

In the figure, a basic pulse generating circuit 8g includes a reproduced CTL signal, a connected slow designating pulse SAP and SW.
Azimuth switching pulse A which is a reference by 30 pulses
The azimuth switching pulse AZSb is generated from the clip flops 8a to 8d by generating ZSa and delaying the clock by the flip-flops 8a to 8d with the SW60 pulse generated from the SW30 pulse as a clock in the SW60 pulse generation circuit 8f. ~ AZS
Generate f.

The azimuth switching pulse AZSd is inverted by the inverter 8e to be the azimuth switching pulse AZSd, and the azimuth switching pulses AZSe and AZSf are generated by the flip-flops 8c and 8d from the output of the inverter 8e. ~ AZSf
And the azimuth switching pulse AZSa in the flip-flop 8
a to 8d, if the azimuth switching pulse AZSa is assumed to be 6 pulses of the normal SW30 pulse,
In the case where the reset cycle is applied five times by the reproduced CTL signal, or when the pulse is extended to seven times without being reset in six times, the reset CTL signal can be used to make a good reset. This is because an error occurs.

The azimuth switching pulse selector 9 selects and outputs one of the six azimuth switching pulses AZSa to AZSf generated by the azimuth switching pulse generator 8 in accordance with the pulse selection signal PSS.

Further, if the azimuth switching pulse AZP can be selectively output by the azimuth switching pulse selecting means 9 as described above, there are the following advantages. This is called the continuous slow 1/3 speed mode (1 of the normal EP mode).
The azimuth track when the magnetic tape 18 recorded in a mode other than the mode in which the capstan motor 14 is rotated at a speed of) is reproduced in the continuous slow ３ speed mode, and the magnetic head for tracing the azimuth track. This will be described with reference to FIG. Here, 103 to 107 indicate respective magnetic heads, and their traces are indicated by dotted lines.

In this figure, in this case, since the azimuth track and the trajectory of the magnetic head are not parallel, in order to always reproduce a video signal having a sufficient level, a magnetic field having a different azimuth angle during the trace is required. It is necessary to switch to the head. However, in that case, as described above as a conventional example, a screen shake and color noise occur. Even if switching to a magnetic head having a different azimuth angle is performed as predicted by the azimuth switching pulse and such switching is not performed in the middle of the trace, if "H", "H", "H", “L”, “L”,
Assuming that only the azimuth switching pulse of “L” is generated, in the case shown in FIG.
4, 106 and 107, the video signal cannot be reproduced, and there is a problem that a lot of tracking noise is generated on the reproduction screen. Actually, if the operation mode at the time of recording and the operation mode at the time of reproduction are different,
It is difficult to predict the state of tracing the azimuth track on which the magnetic head is formed.

Therefore, as in the present embodiment, the azimuth switching pulse selecting means 9 traces the azimuth track best according to the operation mode at the time of recording, like the azimuth switching pulses AZSa and AZSf shown in FIG. By selecting a possible azimuth switching pulse, even if a magnetic tape having a different operation mode during recording is reproduced in a continuous slow mode, a good reproduced image with less noise due to tracking deviation can be always obtained.

As described above, when the capstan motor 14 is driven at 1/3 the speed of the normal EP mode, the azimuth switching pulse generating means 8 generates the reproduced CTL signal and the SW 30 as shown in FIG. The azimuth switching pulse AZP generated by the basic pulse generation circuit 8g using the SW30 pulse as a clock as described with reference to FIG. 11 can be generated by the pulse and the continuous slow mode instruction pulse SAP.
Are sequentially delayed by the flip-flops 8a to 8d in synchronization with the SW30 pulse, whereby desired azimuth switching pulses AZSa to AZSf can be generated.

The azimuth switching pulse selection means 9 selectively switches and outputs the azimuth switching pulses AZS of the six patterns generated by the azimuth switching pulse generation means 8 in accordance with a pulse selection signal PSS input from the outside. be able to. This makes it possible to reproduce a video signal that always provides a good reproduced image even when the magnetic tape recorded in different recording modes is continuously and slowly reproduced, even when the set varies.

As described above, an EP having a track width of 19.3 μm is used.
In the mode, the case where the rotation speed of the capstan motor 14 is driven at 1/3 of the normal rotation speed has been described. However, this is an example, and the present invention is applied to the case where the rotation speed is reduced to the normal rotation speed. Capstan motor 1
This applies to all cases when the rotation speed of No. 4 is driven at 1 / n (n is a natural number). Hereinafter, this will be described with reference to FIG.

FIG. 14 shows the state of the magnetic head with respect to the azimuth track when the rotation speed of the capstan motor 14 is driven at 1/5 of the normal speed.
k is the trajectory of the magnetic head with respect to the azimuth track.

In the same figure, assuming that the position of the magnetic head when the reproduced CTL signal is reproduced is located at 89a,
In order for the magnetic head to trace the track best, the azimuth angles should be +, +,-,-,-,-,-, +,
It is sufficient to switch between + and + (shaded portions in the figure). FIG. 15 shows a time chart in this case.

In the figure, a reset pulse is generated at the timing when the reproduced CTL signal is reproduced, and +, +,-,-,-,-,-, +, + are set at the edge of the SW30 pulse following the rising edge of the reset pulse. , +, + Azimuth switching pulses AZP are generated. As a result, even when the capstan motor 14 is rotated at 1/5 the normal speed, the magnetic head traces the azimuth track satisfactorily and a good reproduced image is obtained.

When the capstan motor 14 is driven at 1 / n of the normal speed in this way, the reset from the reproduction CTL signal is performed while the time from the rising edge of the SW30 pulse to the next rising edge is set to one time. n
Each magnetic head may be switched by the azimuth switching pulse AZP, which becomes one cycle every 2n times while "H" and "L" continue each time.

Also, when recording is performed in the SP mode with a track width of 59 μm, the track width is set to 19.
This is similar to the case where recording was performed in the EP mode of 3 μm. This will be described with reference to FIG. However, in this case, S
It is assumed that the magnetic tape recorded in the P mode is reproduced while rotating the capstan motor 14 at 1/7 the speed in the normal SP mode. Note that 90
a to 90o indicate the position of the magnetic head with respect to the azimuth track, and the track width of the magnetic head is 64 μm.

In this case, in this case, the capstan motor 14 is driven at 1/7 the speed in the SP mode. The position is shifted by 4 μm. At this time, as described in the EP mode,
Azimuth angles +, +, +, +,-,-,-,-,-,-,
The magnetic head may be switched between-, +, +, +. Also,
The time chart at this time is as shown in FIG.

A reset pulse is generated at the reproduction timing of the reproduced CTL signal, and +, +, +, +,-,-,-,-,-, from the edge of the SW30 pulse immediately after the reset pulse.
Azimuth switching pulse AZ in the order of-,-,-, +, +, +
P occurs. As described above, when the capstan motor 14 is driven at 1/7 the speed of the SP mode, seven times from the rising edge of the SW30 pulse to one time while resetting by the reproduction CTL signal. The azimuth of the magnetic head may be switched by an azimuth switching pulse AZP which is one cycle in 14 times while "H" and "L" are successively each. This is the same as when the recording mode described above is the EP mode.

The embodiment described above has the following effects.

FIG. 18 shows a rotary cylinder 19 having a DA-4 structure.
FIG. 3 is a diagram showing an arrangement relationship of magnetic heads 20 to 23 attached to the head.

In the figure, here, there is a time interval of about 2H (127 μsec) between the two magnetic heads constituting the double azimuth head. Now, assuming that the reference line is a + azimuth magnetic head (+ A head) 20 and a -azimuth magnetic head (-B
If a line connecting the head 23 is shifted by 2H, if the -A head 21 or the + B head 22 is selected, the reproduction of the video signal is delayed by 2H, which is a cause of the screen shaking. Cause.

Therefore, the delay of the reproduction timing of the video signal is set according to the magnetic head to be selected, and the additional means 5 (FIG. 1) adds the additional delay when the magnetic heads 20 and 23 are selected. When the magnetic heads 21 and 22 are selected with respect to the V synchronization signal, the correction is performed by replacing the additional V synchronization signal with a timing before or after the V synchronization signal. Can be eliminated.

In this embodiment, magnetic heads having different azimuth angles are switched by the azimuth switching pulse AZP as predicted in advance, and the azimuth of the magnetic head to be reproduced is determined. Therefore, as shown in FIG. 19, by using the azimuth switching pulse AZP and the SW30 pulse 3, it is easy to determine which magnetic head in the rotary cylinder 19 is selected. Thus, an additional V pulse switching pulse is generated, and using this, the additional V signal delayed by 2H time and the additional V signal without delay are switched in accordance with the selected magnetic head, and the reproduced video signal is switched. By replacing with a vertical synchronizing signal, it is possible to obtain a good screen without screen shaking.

FIG. 20 is a block diagram showing a specific example of the additional V pulse generating means 5c of FIG. 1 which performs the above operation. 5c1 is an additional V pulse generating circuit without delay, and 5c is an additional V pulse generating circuit with delay. , 5c3 are additional V pulse switching pulse generation circuits, and 5c4 is additional V pulse switching means.

In the figure, additional V-pulse switching means 5c
Reference numeral 4 denotes an additional V-pulse switching circuit AVcW generated by the additional V-pulse switching pulse generator circuit 5c3, and an additional V-pulse without delay from the additional V-pulse generator circuit 5c1 and an additional V-pulse generator circuit 5c2 with a delay.
Is switched to the additional V-pulse with delay from, and is output as the additional V-pulse AVSS. The rotating cylinder 19
2 with double azimuth head attached to (Fig. 1)
The interval between two magnetic heads is about 2H (127 μsec), but there is a variation. To finely adjust this, an additional V-pulse generating circuit 5c2 with a delay is provided with a variable resistor for adjusting the delay time. Is provided.

FIG. 21 is a block diagram showing another embodiment of the intermittent magnetic recording / reproducing apparatus according to the present invention. Numeral 31 denotes an azimuth switching pulse automatic adjusting means, and portions corresponding to those in FIG. And a duplicate description will be omitted.

In FIG. 21, the azimuth switching pulse automatic adjusting means 31 determines the level of the envelope signal EVS output from the video signal processing means 2 of the video signal reproduced from the magnetic tape 18 and detects that the envelope level is sufficient. If the reproduced video signal is not reproduced properly, a pulse selection signal is generated to select one of the azimuth switching pulses AZS and the azimuth switching pulse AZP.
Output as

Next, the operation of this embodiment will be described with reference to FIG.

In the continuous slow mode, when reproducing by driving the capstan motor 14 at 1 / n the speed of the normal mode, first, the azimuth switching pulse of the n1 pattern generated by the azimuth switching pulse generating means 8 is used. The video signal is reproduced from the magnetic tape 18 while the azimuth switch 4d is switched by the AZS. The envelope signal EVS of the reproduced video signal is supplied to the azimuth switching pulse automatic adjusting means 31, and the maximum value and the minimum value of the envelope signal EVS are detected. Then, a difference between the maximum value and the minimum value is obtained and stored as a difference value S1. Then, the azimuth switching pulse automatic adjusting means 3
1 outputs the azimuth switching pulse AZS output from the azimuth switching pulse generating means 8 while sequentially selecting and switching from the n2 pattern to the nn pattern, and determines the maximum value and the minimum value of the envelope signal EVS obtained for each pattern. The difference is detected and stored as difference values S2 to Sn. When the difference values S1 to Sn of all n patterns have been stored, the smallest difference value Smin is selected from them, and the azimuth switching is performed so that the difference between the maximum value and the minimum value of the envelope signal EVS becomes the difference value Smin. The pulse AZS is selectively output.

The small difference between the maximum value and the minimum value of the envelope signal EVS means that the magnetic head traces the azimuth track almost satisfactorily at any timing of the SW30 pulse. That is, a good screen without tracking deviation can be obtained.

Thus, when the recorded magnetic tape is continuously and slowly reproduced, the azimuth switching pulse AZS can be obtained by himself / herself so as to obtain a good reproduced image with as little tracking deviation as possible while watching the reproduced image on the monitor.
The azimuth switching pulse AZS is automatically selected and output so that the reproduced image becomes the best without switching and selecting one of the above, thereby greatly improving the usability.

FIG. 23 is a block diagram showing still another embodiment of the intermittent magnetic recording / reproducing apparatus according to the present invention.
Denotes an envelope comparison azimuth holding means, 32a denotes a changeover switch, 32b and 32c denote holding means, and 32d and 32e denote comparison discriminating means. Parts corresponding to those in FIG.

In this embodiment, an envelope comparison azimuth holding means 32 is used instead of the azimuth switching pulse generating means 8 and the azimuth switching pulse selecting means 9 in FIG.

In the figure, the envelope comparison azimuth holding means 32 moves the magnetic tape 18 from the magnetic heads 22 and 2.
3, comparing the envelope levels of the video signals reproduced by the magnetic heads 20 and 30 with the comparison and determination means 32d for determining the azimuth magnetic head of the higher level.
A comparison discriminating means 32e for comparing the envelope level of the video signal reproduced by the disc 22 and discriminating the magnetic head of the higher azimuth azimuth, a comparison discriminating means 32d,
Holding means 32 for holding each determination result between the edges of the SW30 pulse and generating an azimuth switching pulse for switching to a magnetic head having an azimuth angle corresponding to the held result;
b and 32c, and a changeover switch 32a for switching the azimuth changeover pulse output from the holding means 32b and 32c by the SW30 pulse.

Next, the operation of this embodiment will be described.

In the same figure, when the reproduction is performed in the continuous slow mode, when the double azimuth head starts tracing the azimuth track on the magnetic tape 18, the reproduction is performed by the respective magnetic heads in the envelope comparison azimuth holding means 32. The envelope levels of the video signals are detected and compared by the comparison determination means 32d and 32e. However, at this time, the operation is as follows. That is, the time for the double azimuth head to trace the azimuth track is determined by the edge of the SW30 pulse, and the tracing starts from the edge of the SW30 pulse and ends with the next edge.

However, actually, the magnetic tape 18 has
The magnetic head has already contacted before the timing of the edge of the SW30 pulse, and it is possible to reproduce the video signal before the occurrence of the edge of the SW30 pulse. Therefore, SW3
Before the edge of the 0 pulse is generated and the video signal is reproduced, the envelope level of the video signal is detected at a portion where the magnetic tape 18 is already in contact with the magnetic head, and this is compared by the comparison determination means 32d and 32e. Then, the larger one is determined and held by the holding means 32b and 32c.
The holding means 32b and 32c continue to hold the magnetic head having the larger azimuth angle determined from the edge of the SW30 pulse to the next edge, and output an azimuth switching pulse for switching the held azimuth to the magnetic head side. I do. Then, it is selectively switched by the changeover switch 32a and output.

As a result, the magnetic head does not switch to a magnetic head having a different azimuth angle while the azimuth track is being traced, so that the color noise which has conventionally occurred can be eliminated. Further, since only the azimuth selection circuit block needs to be changed as compared with the conventional case, it can be realized at low cost.

Further, it is also possible to perform V rattling as follows.

FIG. 27 is a block diagram showing a specific example of the additional V pulse generating means 5c.

5c1 is an additional V pulse generating circuit without delay,
5c2 is an additional V pulse generating circuit with a delay, 5c3 is an additional V pulse switching pulse generating circuit, 5c4 is an additional V pulse switching means, 5c5 is a SW30 pulse, an azimuth switching pulse AZP, a continuous slow mode pulse Mb, and 1 / n of normal running. The amount of deviation for detecting the amount of deviation of the magnetic head from the recording start end of the azimuth track being recorded, from the continuous slow specifying pulse SAP that specifies n in the continuous slow mode when the magnetic tape 18 is driven at the speed of The detecting means 5c6 is an additional V pulse switching means 5c4.
The phase of the additional V-pulse input from the above is corrected by a predetermined advance or delay phase in accordance with the phase variable amount Ft input from the shift amount detecting means 5c5, and the additional V-pulse phase for outputting the additional V-pulse It is a variable means.

The operation of FIG. 27 will be described with reference to FIGS.

FIG. 28 is similar to FIG.
FIG. 4 is an explanatory diagram for explaining a trace starting point when a recording pattern on a magnetic tape recorded by a 3 μm head is traced and reproduced by a head having a track width of 30 μm.

As shown, the track width is 19.3 μm (EP
Mode), signals of 1H to 262.5H and 263 / 2H to 525H are recorded side by side with a horizontal synchronization signal in one track. The distance (referred to as αH) between the respective recording start points is 0.5H.

When a track recorded in this manner is normally reproduced, the magnetic head always traces from the end of each track (recording start point). The period Tv up to the signal is 262.5H, and normal reproduction is performed.

However, in the case of continuous slow reproduction, the result is as shown in FIG. The figure shows an example of a case where continuous slow reproduction is performed at a speed of 1/3 of the normal reproduction speed. In this case, as in FIG. 2, the magnetic head is moved from the position shown in FIG. Start tracing for each track.

When the magnetic head is at the position, since the magnetic head starts tracing from the end of the recorded minus azimuth track, there is no phase shift of the vertical synchronizing signal in the reproduced video signal. However, when tracing is started from this position, since the magnetic head traces the + azimuth track as shown in the figure, the read video signal is shortened by the amount shown by t1 in the figure, and the phase of the vertical synchronization signal advances. . The same applies to the case of. Similarly, in the above case, since there is a shift shown by t2 in the figure between the trace start position of the magnetic head and the end of the minus azimuth track, the vertical synchronization signal of the video signal reproduced by this shift Advances in phase.

FIG. 29 shows such a shift amount. 21 shows the type of the magnetic head selected from the double azimuth heads and the shift amount of the trace start position of the magnetic head from the track end in each of the cases of FIG.

This shift shifts in the following order with reference to the azimuth switching point, that is, the switching edge of the azimuth switching pulse AZP.

-T1 → -t2 → 0 Here, t1 and t2 are as follows.

T1 = αH / 3 * 2 t2 = αH / 3 * 1 (where αH = 0.5H) Thus, in the EP mode, when performing continuous slow reproduction at a speed of 1/3 of the normal speed,
With reference to the switching edge of AZP, the shift is always αH / 3 in the order of −t1 → −t2 → 0 at each edge of the SW30 pulse. Therefore, this shift amount is determined by SW30, AZP,
By detecting from the continuous slow mode pulse Mb and the SAP and correcting it in reverse according to the amount of deviation, the deviation can be reduced to zero.

The shift amount detecting means 5c5 receives the input SW
30, AZP, continuous slow mode pulse Mb and SAP
From the trace start point of the magnetic head and the recording start point of the azimuth track, the phase shift amount Ft
Can be output. Additional V pulse phase varying means 5c
In step 6, a predetermined leading phase or lagging phase is corrected in accordance with the phase variable amount Ft, and an additional V pulse is output.

FIG. 30 is a timing chart for explaining this correction. Assuming that the timing of the additional V pulse with respect to the SW30 edge in the case where there is no shift is ta, the phase advances by t1 in this case, so that the phase of the vertical synchronizing signal (additional V pulse) is varied as shown in FIG. Add time delayed. Similarly, in the case of (1), the phase is advanced by t2 due to the deviation, and conversely, the vertical synchronization signal is added delayed by t2. The same applies to the case of.
Thus, the period Tv from the vertical synchronizing signal to the vertical synchronizing signal of the reproduced video signal can be all the same.

Thus, during continuous slow mode playback,
It is possible to obtain a good image without V rattling (up and down of the screen).

FIG. 31 is a view similar to FIG. 28. In the EP mode, when the magnetic tape is driven at 1/5 the speed of the normal EP, the recording pattern on the magnetic tape is changed to a head width of 30 μm. FIG. 7 is an explanatory diagram for explaining a state of a trace start point in a case where trace is performed for reproduction.

In this case, similarly, the magnetic heads 1 to
A shift as shown in FIG. 32 occurs according to the trace as shown in FIG. In the case of this example, based on the azimuth switching point, that is, the switching timing of the azimuth switching pulse AZP (both rising and falling edges), always -t1 → -t2 → -t3 → 0 → − every 30 pulses of SW. are shifted in the order of t3
Good. Further, t1, -t2, and t3 are respectively t1 = αH / 5 * 3 t2 = αH / 5 * 2 t3 = αH / 5 * 1. Based on the AZP switching timing, S
Since it is always shifted by αH / 5 every W30 pulse, the position shift between the trace start point of the magnetic head and the recording start point of the azimuth track is determined from SW30, AZP, continuous slow mode pulse Mb and SAP as described above. The deviation can be reduced to 0 by detecting and correcting in reverse according to the amount of deviation.

The same applies to the case of the SP mode. FIG.
FIG. 8 is an explanatory diagram for explaining a case where the capstan motor is rotated at 1/7 the speed of the standard driving speed in the SP mode to perform continuous slow reproduction.

The magnetic head on the track has a track width of 1
/ 7, as shown by 1 to 14 in the figure. At this time,
As in the case of the above-described EP mode, a deviation of the reproduction trace start point from the recording track end occurs.

FIG. 34 shows the shift. For each of the cases 1 to 14, a head as shown in the figure is selected, and a shift such as t1 to t3 in the figure occurs. The shift is shifted as follows based on the switching edge of the AZP.

−t3 → −t2 → −t1 → 0 → + t1 + t2 → + t3 At this time, t1 to t3 are the following shift amounts, respectively.

T1 = αH / 7 * 3 t2 = αH / 7 * 2 t3 = αH / 7 * 1 In this manner, based on the switching timing of AZP, there is always a shift of αH / 5 every 30 pulses of SW. Therefore, as described above, the shift amount detection means 5c5 outputs the SW
30, AZP, continuous slow mode pulse Mb and SAP
Therefore, if the deviation between the trace start point of the magnetic head and the recording start point of the azimuth track is detected and corrected in reverse according to the deviation amount, the deviation can be made zero.

Therefore, even in the SP mode, similarly to the above description, the phase shift of the vertical synchronizing signal caused by the shift from the track end shown in FIG. 26 is corrected by reversely changing only the shifted phase amount. By doing so, the period Tv from the vertical synchronizing signal to the vertical synchronizing signal of the reproduced video signal can be all the same, so that a good reproduced image without screen shake can be obtained.

[0120]

As described above, according to the present invention,
Compared to the normal running mode, when the audio signal is reproduced by the audio signal recording / reproducing means and reproduced in the continuous slow mode driven at 1 / n times speed, the azimuth switching of the double azimuth head is performed during the azimuth track tracing. It is possible to prevent noise due to a color signal processing error that occurs, screen fluctuation due to lack of a horizontal scanning period, and noise due to tracking deviation, and to obtain a reproduced image with good image quality.

Further, according to the present invention, when the audio signal is reproduced by the audio signal recording / reproducing means in the continuous slow mode while reproducing the audio signal, even if the magnetic tape is recorded in a mode different from the driving mode to be reproduced, By switching and selecting the pattern of the azimuth switching pulse, a good image can be reproduced.

Further, according to the present invention, when the audio signal is reproduced by the audio signal recording / reproducing means in the continuous slow mode while reproducing the audio signal, the envelope level of the reproduced video signal is detected and the difference between the maximum value and the minimum value is detected. The user must select the azimuth switching pulse by himself / herself so as to obtain the best noise-free reproduction screen while watching the monitor screen, since the user selects the azimuth switching pulse that minimizes the noise. As a result, a reproduced image having the best image quality without tracking noise can be automatically obtained.

Further, according to the present invention, when the audio signal is reproduced by the audio signal recording / reproducing means in the continuous slow mode while reproducing the audio signal, the azimuth track tracing is started from the edge of the SW30 pulse to reproduce the video signal. Before starting, the envelope level of the video signal is detected from each magnetic head of the double azimuth head that is already in contact with the magnetic tape, and the video signal is reproduced while maintaining the selection of the magnetic head with the higher level. because there is,
Noise due to color signal processing error caused by switching from one magnetic head to another magnetic head with different azimuth angles during azimuth track tracing of the azimuth track, screen shake due to lack of horizontal scanning period, and tracking deviation Noise can be prevented, and a reproduced image with good image quality can be obtained.

In the present invention, since the azimuth of the magnetic head that traces the azimuth track is predicted and switched, the interval between the double azimuth magnetic heads and the distance between the recording start end and the trace start point of the magnetic head are changed according to the azimuth to be switched. The displacement can be corrected, and a good reproduced image without vertical fluctuation of the screen can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an intermittent magnetic recording / reproducing apparatus according to the present invention.

FIG. 2 is a diagram showing a trace pattern on a magnetic tape and a trace state of a magnetic head in FIG. 1;

FIG. 3 is a timing chart showing an operation example of the embodiment shown in FIG. 1;

FIG. 4 is a diagram showing a trace width of the magnetic head in FIG. 1;

FIG. 5 is a timing chart showing another operation example of the embodiment shown in FIG. 1;

FIG. 6 is a timing chart showing another trace state of the magnetic head in the embodiment shown in FIG. 1;

FIG. 7 is a diagram showing a trace width of the magnetic head in the operation shown in FIG. 6;

FIG. 8 is a diagram showing still another operation example of the embodiment shown in FIG. 1;

FIG. 9 is a view showing still another trace state of the magnetic head of the embodiment in FIG. 1;

FIG. 10 is a timing chart showing the operation of the azimuth switching pulse generator in FIG. 1;

FIG. 11 is a block diagram showing a specific example of an azimuth switching pulse generator in FIG. 1;

FIG. 12 is a diagram showing still another trace state of the magnetic head in FIG. 1;

FIG. 13 is a timing chart showing the operation of the embodiment shown in FIG. 1 with respect to the trace state shown in FIG.

FIG. 14 is a diagram showing still another trace state of the magnetic head in FIG. 1;

15 is a timing chart showing the operation of the embodiment shown in FIG. 1 with respect to the trace state shown in FIG.

FIG. 16 is a view showing still another trace state of the magnetic head in FIG. 1;

17 is a timing chart showing the operation of the embodiment shown in FIG. 1 with respect to the trace state shown in FIG. 16;

FIG. 18 is a plan view showing a specific example of an arrangement relationship of a magnetic head on a rotary cylinder in FIG. 1;

FIG. 19 is a timing chart showing an operation of the embodiment shown in FIG. 1 when the rotary cylinder shown in FIG. 18 is provided.

FIG. 20 is a block diagram showing a specific example of an additional V pulse generating means in FIG. 1;

FIG. 21 is a block diagram showing another embodiment of the intermittent magnetic recording / reproducing apparatus according to the present invention.

FIG. 22 is a flowchart showing the operation of the embodiment shown in FIG.

FIG. 23 is a block diagram showing still another embodiment of the intermittent magnetic recording / reproducing apparatus according to the present invention.

FIG. 24 is a block diagram showing an example of a conventional intermittent magnetic recording / reproducing apparatus.

FIG. 25 is a diagram showing a trace state of the magnetic head in the conventional example shown in FIG. 24;

FIG. 26 is a diagram showing another example of the trace state of the magnetic head in the conventional example shown in FIG. 24;

FIG. 27 is a block diagram showing a second configuration example of the additional V pulse generating means;

FIG. 28 is an explanatory diagram for explaining a trace positional relationship between a magnetic head and an azimuth track when continuous slow drive is performed at a normal 1/3 speed in the EP mode.

FIG. 29 shows a case of FIG. 20, in which the positional deviation between the trace start end of the magnetic head and the recording start end of the azimuth track is changed.

FIG. 30 is a timing chart for explaining a case where reverse correction is performed according to a shift amount;

FIG. 31 is an explanatory diagram for explaining a trace positional relationship between a magnetic head and an azimuth track when performing continuous slow drive at a normal 1/5 speed in the EP mode.

FIG. 32 shows the case of FIG. 23, in which the amount of displacement between the trace start end of the magnetic head and the recording start end of the azimuth track is changed.

FIG. 33 is an explanatory diagram for explaining a trace positional relationship between a magnetic head and an azimuth track when performing continuous slow drive at a normal 1/7 speed in the SP mode.

FIG. 34 shows the case of FIG. 25, in which the positional deviation between the trace start end of the magnetic head and the recording start end of the azimuth track is changed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Video signal input terminal 2 Video signal processing means 3 Video signal output terminal 4 Recording / playback control means 5 Addition means 5a Additional V switch 5b Replacement means 5c Additional V generation means 7 System control means 8 Azimuth switching pulse generation means 9 Azimuth Switching pulse selection means 10 Servo circuit 11 CTL switching switch 12 CTL recording / reproduction control means 13 Azimuth switching pulse switching means 14 Capstan motor 15 Cylinder motor 18 Magnetic tape 19 Rotating cylinder 20 to 23 Magnetic head 31 Azimuth switching pulse automatic adjusting means 32 Envelope Comparative azimuth holding means

Continued on the front page (72) Inventor Mitsuru Kudo 1410 Inada, Katsuta-shi, Ibaraki Pref. AV Equipment Division, Hitachi, Ltd. (56) References JP-A-2-280480 (JP, A) JP-A-63-84387 (JP) JP-A-1-248776 (JP, A) JP-A-59-112778 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 5/782-5/783 H04N 5/91-5/956 G11B 15/14

Claims (6)

(57) [Claims] 1. A control signal recording / reproducing means for recording and reproducing a control signal for controlling the running of a magnetic tape corresponding to a track position recorded in a diagonal direction of the magnetic tape, a control head, and an input video signal during recording. Servo means for controlling tape running in accordance with the control signal reproduced from the magnetic tape during reproduction, and controlling continuous slow drive for driving at 1 / n speed of normal running. An intermittent magnetic recording / reproducing apparatus, comprising: a first magnetic head having a first azimuth angle;
A second magnetic head having a second azimuth angle is disposed so as to face the first magnetic head, and a third magnetic head having the second azimuth angle is disposed adjacent to the first magnetic head; A rotating cylinder on which a fourth magnetic head having the first azimuth angle is disposed 180 degrees opposite to the third magnetic head; The magnetic tape according to a SW30 pulse for distinguishing between a period in which the first and third magnetic heads make contact and perform recording and reproduction and a period in which the second and fourth magnetic heads make contact and perform recording and reproduction, respectively. Is selected, and has one of the first and third magnetic heads or the second and fourth magnetic heads which are arranged adjacently and have different azimuth angles. Selective switching of magnetic head An azimuth switching pulse generating means for generating an azimuth switching pulse; and an audio signal recording / reproducing means for recording and reproducing an audio signal with a magnetic head for audio. When reproducing at a speed of 1 / n, a signal is reproduced from two tracks recorded diagonally on the magnetic tape every time the rotary cylinder rotates n times. A control signal reproduced by the reproducing means is supplied to the azimuth switching pulse generating means, and the azimuth switching pulse generating means performs resetting by the control signal from the switching edge of the SW30 pulse to the next switching edge. Is one time, and a high level and a low level are successively performed n times each, and 2n times forms one cycle. Intermittent magnetic recording and reproducing apparatus characterized by generating a Jimasu switching pulse. 2. The azimuth switching pulse generating means according to claim 1, wherein the azimuth switching pulse is such that the order of the high level and the low level in one cycle of the azimuth switching pulse is shifted by one SW30 pulse. Azimuth switching pulse of the following pattern, further comprising azimuth switching pulse selecting means, wherein the azimuth switching pulse selecting means is driven at a speed of 1 / n of the normal running while reproducing the audio signal by the audio signal recording / reproducing means. An intermittent magnetic recording / reproducing apparatus, wherein a desired azimuth switching pulse is selected from among the n patterns of azimuth switching pulses generated by the azimuth switching pulse generating means when performing the reproduction. 3. A control signal recording / reproducing means for recording and reproducing a control signal for controlling the running of the magnetic tape in accordance with a track position recorded in an oblique direction of the magnetic tape, a control head, and an input video signal at the time of recording. A servo circuit for controlling tape running in accordance with the control signal reproduced from the magnetic tape during reproduction, and a system control means for controlling continuous slow drive for driving at 1 / n the speed of normal running. And an intermittent magnetic recording / reproducing apparatus comprising: a first magnetic head having a first azimuth angle;
A second magnetic head having a second azimuth angle is disposed so as to face the first magnetic head, and a third magnetic head having the second azimuth angle is disposed adjacent to the first magnetic head; A rotating cylinder on which a fourth magnetic head having the first azimuth angle is disposed 180 degrees opposite to the third magnetic head; A SW30 pulse for distinguishing between a period in which recording and reproduction are performed when the first and third magnetic heads are in contact with each other and a period in which recording and reproduction are performed when the second and fourth magnetic heads are in contact with each other; The first and third magnetic heads or the second and third magnetic heads arranged adjacent to each other and having different azimuth angles from the control signal reproduced by the reproducing means.
An azimuth switching pulse generating means for generating an azimuth switching pulse for selectively switching one of the fourth magnetic heads having an azimuth angle; a maximum value and a minimum value of an envelope level of a video signal reproduced from the magnetic tape; Azimuth switching pulse automatic adjusting means for generating a pulse selection signal for selecting an azimuth switching pulse so as to reduce the difference between them, and an audio signal recording / reproducing means for recording and reproducing an audio signal by a magnetic head for audio. In the case where the audio signal is reproduced by the audio signal recording / reproducing means while being reproduced at a speed of 1 / n of the normal running while the audio signal is reproduced by the audio signal recording / reproducing means, recording is performed in an oblique direction of the magnetic tape every time the rotary cylinder rotates n times. The azimuth switching pulse automatic adjusting means,
Immediately after the reproduction is started, the envelope level of the video signal reproduced from the magnetic tape is detected while sequentially switching the n azimuth switching pulses generated by the azimuth switching pulse generating means. An intermittent magnetic recording / reproducing apparatus characterized by judging a difference between a maximum value and a minimum value of an envelope level in each case of a switching pulse, and automatically selecting an azimuth switching pulse that reduces the difference. . 4. The audio system according to claim 1, further comprising: an additional unit for replacing a vertical synchronizing signal with a video signal reproduced by the magnetic head according to the selected magnetic head. In the case where the signal is reproduced by driving at a speed of 1 / n of the normal traveling while reproducing the audio signal by the signal recording / reproducing means, the additional means comprises two azimuth angles different from each other which are arranged adjacent to each other on the rotary cylinder. The two magnetic heads determine the time difference between the video signals reproduced by the magnetic heads according to the interval between the magnetic heads.
The phase of the vertical synchronization signal added when these two magnetic heads are the third and fourth magnetic heads is advanced by a predetermined amount with respect to the phase of the vertical synchronization signal added when the two magnetic heads are used. An intermittent magnetic recording / reproducing apparatus characterized in that correction is made by delaying. 5. The apparatus according to claim 4, further comprising an additional vertical synchronizing signal phase changing means for changing a phase of the added vertical synchronizing signal, wherein the additional vertical synchronizing signal phase changing means comprises a magnetic head for tracing during reproduction. An intermittent magnetic recording / reproducing apparatus characterized in that the phase of a vertical synchronizing signal is advanced or delayed by a predetermined amount according to sequential prediction. 6. An apparatus according to claim 5, wherein said additional vertical synchronizing signal phase changing means includes said input SW30 pulse, said azimuth switching pulse, a continuous slow mode pulse for controlling a servo circuit in a continuous slow mode, and a continuous slow mode pulse. When driving at a normal 1 / n speed in the mode, the phase of the input additional vertical synchronizing signal is varied according to a continuous slow mode designating pulse for designating n. The vertical synchronizing signal phase varying means responds to 1 / n of the distance between the recording start points of adjacent recording tracks each time the rising and falling edges of the SW30 pulse are input during continuous slow mode reproduction. The playback trace of the magnetic head on the tape is advanced or delayed by a predetermined amount at each timing. Starting the intermittent magnetic recording and reproducing apparatus, characterized in that for correcting the phase shift of the vertical synchronizing signal of the video signal corresponding to the deviation from the recording track end of.