FR2462831A1 - DEVICE FOR REPRODUCING A VIDEO IDLING OR IDLE STOP SIGNAL - Google Patents

Abstract

REPRODUCTION OF A VIDEO SIGNAL. THE DEVICE INCLUDES SEVERAL ROTATING VIDEO HEADS 13A, 13B WITH GAPS IN DIFFERENT AZIMUTES AND MEANS 47, 49, 43 FOR DELAYING A REPRODUCED CONTROL SIGNAL AND STOPPING THE MOVEMENT OF THE BAND SUCH AS THE MOMENT OR THE SIGNAL LEVEL VIDEO REPRODUCED BECOMES MINIMUM SITUATED IN THE PERIOD OF FRAME DELETION OR NEAR THIS PERIOD. REPRODUCTION IN IDLE OR STOP IN IMAGE.

Description

The invention relates generally to a device

  to reproduce recorded video signals.

  on a magnetic tape so as to obtain slow-motion or still-picture reproduction, and more particularly, a device for reproducing

  slow motion or still image free of noise and

on the screen.

  The prior art uses a device in which a video signal is recorded on a magnetic tape, on parallel tracks formed obliquely to the longitudinal direction of the tape. This band is moving at a different speed than

  it is used when registering or else it stops

  te to enable speed-shifting reproduction, for example, accelerated playback, slow motion playback, or still picture playback. In this device, the length of the tape at the time of reproduction is different from what it is at the time of recording and that is why the course (track) that describes the head on the tape during the reproduction is different -of the one she describes

during the recording.

  A classical device for recording and

  reproduction of video signals usually form

  on a recording medium

  neighboring tracks an area or strip without registration

  the safety barrier so as to prevent interference

  interference caused by reproduced signals from neighboring tracks as a result of centering deviation of the head during reproduction. When reproducing with a gear shift as indicated above a tape recorded in this manner, the head will travel the track and the non

  recorded. When the head goes through the unregistered area

  the signal reproduced is of a significantly reduced level or disappears. For this reason, a noise is created in the reproduced image. In addition, in said device, since unregistered areas are provided

  between tracks, the rate of use of the band is mediocre

  cre. There is also known a device in which the angle of inclination of the strip is varied relative to the plane of rotation of the head as a function of the speed of the strip so that the heads traverse exactly the

  track when reproducing with gear change.

  However, this device has the disadvantage of the complexity of the mechanism for varying the angle of inclination of the strip, which makes the device is expensive and it is difficult in practice to obtain a precise path. In addition, a device is known in which tracks are formed on a band with no interval between

  tracks and in which, in addition, it is possible to record

  to reproduce and reproduce a color video signal without any interference occurring (see French Patent No. 76 31190). In this prior device, two

  azimuth heads with inclined air gaps of a certain

  In the opposite direction, the azimuth angle is relative to the direction perpendicular to the longitudinal direction of the runway, and adjacent runways are formed in close contact with each other without an interval therebetween. In addition, the phase of

  chrominance signal is shifted by 900 for each

  horizontal exploration mode and, moreover, the direction of this phase shift is reversed from a track to the adjacent track. According to this device, the rate of use of the band is high since the tracks are in close contact with each other and,

  in addition, there is no interference.

  A device is also known in which, in addition to applying the means described above, several rotating heads having air gaps whose centers, in the direction of the width of the tracks, have positions of different degrees of

  planes of rotation o move their heads and make

  move the magnetic tape at a speed V shown

  by the relation V = Vo (nl1) in which Vo is the velocity

  of the tape for normal reproduction (and record it

  normal) and n a positive or negative integer,

  or the tape is immobilized to reproduce

  slow motion or still image (see patent

French No. 78 09667).

  This last device makes it possible to reproduce

  slow-motion or still picture with the least amount of noise. However, it is necessary that the magnetic tape moves at the speed corresponding to the above relationship, which gives a disadvantage, namely that it can not perform slow motion at all speeds

  data. In addition, when one wants to stop the band-

  tick in motion for playback in still image, the position where the magnetic

  not set. Consequently, the operator must

  the position where the magnetic tape stops with the least noise or noise while watching the screen

  of reproduction. Thus, a disadvantage is that the function

tioning is rather difficult.

  The object of the invention is therefore: a new and useful device for reproducing video signals in slow motion and still images in which the above problems are solved;

  - a device enabling alternative

  reproduction in freeze frame for a desired time and normal reproduction on two track steps,

  which ensures slow reproduction: the reproduc-

  in still mode in the above mode is

  noise-free so that we obtain globally

  idle reproduction without noise; by choosing at will the reproduction period in freeze frame described above, we can perform the

  slow-motion reproduction to a slowdown report

  born; - a device for reproducing video signals in slow motion or still image in which the magnetic tape stops in a position where the

  less noise when playing back in still picture.

  Various other features of the invention

  come out from the detailed description which

follows.

  Embodiments of the subject of the invention

  are shown, by way of non-limiting examples,

in the attached drawing.

  Fig. 1 is a block diagram of an embodiment of the video signal reproducing device

  in slow motion and still image, according to the invention.

  Figs. 2 (A) to 2 (I) are diagrams respectively showing signal waveforms in various

  parts of the block diagram of fig. 1.

  Fig. 3 is a diagram indicating a configuration

  track ration when recording.

  Fig. 4 is a diagram indicating the configuration

  ration of an exploration track during reproduction in

pause.

  Fig. 5 is a diagram showing the level of the signal reproduced during reproduction in freeze frame. Fig. 6 is a diagram indicating the position where the tape must stop when the reproduction is stopped

  on image according to the device of the invention.

  Figs. 7 (A) to 7 (F) are diagrams respectively indicating waveforms of signals at essential portions of the block diagram of FIG. 1, when operating in the playback mode when stopped on

picture.

  Fig. 8 is a block diagram showing a variant of the essential part of the execution mode of

fig. 1.

  Figs. 9 (A) to 9 (E) are diagrams respectively indicating the signal waveforms in various

  parts of the block diagram of fig. 8, during the

  playback for still image reproduction.

  Figs. 10 (A) to 10 (F) are diagrams respectively indicating waveforms of signals in various parts of the block diagram of FIG. 1 at the

  slow reproduction according to the device of the invention.

  We first consider FIG. 1; a video signal to be recorded is introduced into the device shown

  by an input terminal 11, passes through a recording circuit

  12 and 13b and to a vertical sync signal separation circuit 14. The video heads 13a and 13b have opposite azimuths and different track widths. as indicated

  further, and they are mounted on diametrically

  opposed to a rotating drum 16 rotated by a motor 15 at a speed of 30 revolutions per second. A

  magnetic strip 18 wraps obliquely around the drum

  rotating shaft 16 and a fixed drum 17 and is driven in the direction of the arrow X by a capstan 19 driven by a motor 20 via a belt 21 and a flywheel 22 and a pinch roller 23 . A signal

  video is recorded by heads 13a and 13b alternatively

  along the tracks of Band 18, one frame

  per track, the tracks being therefore contiguous

  and oblique in relation to the longitudinal direction

tudinal of the band.

  On the other hand, a vertical synchronization signal

  hold (Fig. 2 (A)) of 60 Hz, which has been separated from the signal

  video in the sync signal separation circuit

  14, is provided to a monostable multivibrator 24 where its frequency is divided by two and

  reduced to 30 Hz. The resulting output signal b, -

  indicated in fig. 2 (B) is fed to a monostable multivibrator 25 for adjusting the phase of the signal and

  same time, via a switch 26 whose

  mobile touch is connected to a contact point R in a recording mode, to a control head 27 by which the signal is recorded as a signal of

  control on the lower edge of the strip 18.

  The resulting output signal c of the monostable multivibrator 25, whose waveform is indicated in FIG. 2 (C), is passed through a switch 28 whose movable contact is connected to a contact R, to a

  sampling and holding circuit 29.

  The rotary drum 16 mentioned above is

  coaxially on a rotating shaft 31 entrained by the

  motor 15 and rotating at the same time as the drum 16.

  Two magnets 33a and 33b of opposite polarity are mounted on a rotating disc 32 fixed coaxially to the rotating shaft 31. At the same time as the drum 16 rotates, pulses

  d of positive polarity and negative polarity, as the

  say fig. 2 (D), are provided alternately by a read head 34 and applied to a flip-flop 35. The output signal of flip-flop 35, having the indicated waveform

  in fig. 2 (E), is applied through a

  mutator 36 whose mobile contact is connected to a contact

  R, to a trapezoidal wave forming circuit 37 and converging

  ti into a trapezoidal wave signal f, indicated at

  Fig. 2 (F)> and then applied to the exchange circuit

Tilling and Retention 29.

  The described embodiment is designed lace

  when the output signal e of the flip-flop 35 is at its low level, the video head IMa explores the band and when the output signal e is at its high level,

  the other video head 13b explores the tape.

  In the sampling and holding circuit 29, the trapezoidal wave signal is sampled in its inclined portion by the sampling impidlsio and a slope portion thus sampled is retained. The output signal given by the sampling circuit and

  maintenance 29 is applied via an amplifier

  motor excitation indicator 30, to the motor 15 so as to control its rotation. The phase of rotation of the motor 15

  is ordered in such a way that the sampling position

  on the trapezoidal wave in the sampling circuit.

  keeping and holding 29 becomes a decisive

  for example the middle of the sloping part of the

trapezoidal waveform.

  According to the control operation described above, the video heads 13a and 13b are rotated, their rotation phase keeping a determined relationship with the phase of the vertical synchronization signal of the input video signal. To adjust this phase relationship, the time constant of the monostable multivibrator is set

  by means of a variable resistor 38.

  On the other hand, as the capstan 19 rotates, a read head 39 detects the rotation of the capstan 19 in cooperation with magnets (not shown) mounted on the flywheel 22. The thus detected signal is applied to a

  capstan servocontrol circuit 40 o an error

  latively at the reference speed is detected. The

  output control signal given by the control circuit

  The capstan 40 is transmitted by a switch 41 whose movable contact is connected to a contact point N. by a motor excitation amplifier 42 and by a switching circuit, the movable contact of which is connected to a

  N, to the motor 20 so as to control its rotation.

  As a result, the magnetic tape 18 is driven by the capstan 19 at a constant speed so that it

  moves a measure corresponding to a step of

  the time when the video heads l3a and 13b turn from the

half a full turn.

  When reproducing at normal speed,

  movable contacts of the switches 26, 28 and 36 are

  switched at their contact points P, the

  mutator 41 and the switch circuit 43 being maintained

  in a position where their moving contacts are connected -

  at the contact points N. The control signal E reproduced by the control head 27 and whose waveform is indicated in FIG. 2 (G) is applied by the switch 26 and an amplifier 44 to a monostable multivibrator having a delay time t1. The output signal h given by the monostable multivibrator 45, whose waveform is indicated in FIG. 2 (H), is applied through the switch 28 to the sampling and holding circuit 29. On the other hand, the phase of the output signal e of the flip-flop 35 is inverted by a phase inverter 46 and this signal is then brought, by the switch 36, to

  Trapezoidal wave forming circuit 37. From the formal circuit

  A trapezoidal waveform 37 draws a trapezoidal wave signal i indicated in FIG. 2 (I) which is polarity

  opposite to the trapezoidal waveform f at the time of

  tration. The trapezoidal wave signal i is applied to the sampling and holding circuit 29 where it is

  sampled by the sample signal-

  swimming h mentioned previously delayed by a time ti.

  In response to the output signal of the sample circuit-

  and holding 29, the rotation of the motor 15 is

  mended. The video signal read or reproduced by the heads 1a and 13b passes through the recording circuit 12 and leaves

by a terminal 54.

  It is understood that when using the signal of on-

  trapezoidal f as the signal to be sampled. During the reproduction also, this signal f having the same form

  than during the registration, the operation of advance

  rotation phase meets a certain limitation. For this reason, it is adapted so that during reproduction, the downwardly inclined portion of the trapezoidal wave signal i, which has undergone a phase inversion, is sampled by the upstream part of the signal h. , delayed from time ti. Since the gaps of video heads l3a

  and 13b have opposite azimuths, no signal is reproduced

  due to azimuth losses in cases where the

  video heads 13b and 13a respectively explore the

  are recorded by the heads 13a and 13b (that is, when performing a reverse scan). Then, during normal speed reproduction, the phase of rotation of the motor 15 is controlled so that the sampling signal E formed by the monostable multivibrator in response to the positive polarity pulses in each set of two frames from the control head 27, as indicated above, samples the middle part of the slope of the trapezoidal wave signal formed during positive polarity pulses coming from the control head 27. In this case, the positive polarity pulses coming from of the control head 27 are

  arranged in such a way that they are

  dence with the rotational position of the head 13a by

  example. For this reason, in such a mode of repro-

  duction, the phases of rotation of the heads 13a and 13b are controlled so that these heads always explore (positive exploration) the recorded tracks

  respectively by these heads M3a and 13b and that the explo-

  inverted ration mentioned above does not occur.

  As shown in fig. 3, the video heads 13a and 13b have respective air gaps 60a and 60b making an angle in the opposite direction with the direction perpendicular to that of exploration, that is to say having angle azimuths. "These video heads 13a and 13b have widths

  different runways, Wl and W2 and are provided for

  so that their respective end faces 61a and 61b

  are on the same reference face of the rotary drum 16.

  In the execution mode considered, the width W1 is

practically from 1.5W2 to 1.6W2.

  The tracks o are recorded video signals are formed as follows on the band 18 by the heads 13a and 13b. When the head 13a, rotating in the direction of the arrow Y, explores the band 18 which moves in the direction of the arrow X, a recorded track width Wl

  is formed obliquely to the longitudinal direction

  tudinal of the band. Then when the head 13b explores

  the band 18 with an overlap of width Wo relati-

  to the track previously formed by the head 13a,

  a recorded track of width W2 (= T) is formed.

  Here, the overlap width Wo is set such that Wo = W1 = T. Then, since the recorded video signal has been frequency modulated, when a head is exploring and recording a new overlapped signal on a

  part of a previously recorded track, the pre-recorded signal

  cedently registered is erased by the effect of polarisa-

  this new signal and the new signal is registered.

  as in known systems. Therefore, the signal recorded by the head 13a remains in the form

  of a track T1 of width T while the signal

  stored by the head 13b remains in the form of a track t2 of width T. Similarly, then, tracks t3, t5, t7, ... (the indices being odd numbers) of width T are formed by the registration of the

  head 13a and the erasing effect of the head, and pistons

  t4, t6, t8, ... (the indices being even numbers) of width T are formed by the recording of the

head 13b.

  In this regard, it is understood that to form tracks in this way in close contact, it is not

  absolutely necessary to use heads with

  runners different as indicated above and that heads with the same track width can be used. However, in the practice of the device of the invention, it is necessary that the track widths of the reproduction heads are different in view of the

  reproduction with gearshift as indicated below

  after, and we gave the description above because

  registration may also be effected by means of these

reproduction heads.

  In such a case, the tracks t1, t2, t3, ... are in contiguous contact without gaps between them so that the utilization rate of the band is high. On each track is recorded part of a video signal that

  practically corresponds to a frame.

  Here, the angle between the video heads 13a and 13b and the magnets 33a and 33b as well as the time constant of the monostable multivibrator 25 for the phase adjustment, are set so that a vertical synchronization signal is placed near the one end of the track. A

  control signal is recorded at the lower side edges

  in the strip 18 along a control track 62,

  in the longitudinal direction of the strip.

  We now describe in connection with FIG. 4

  a reproduction operation in freeze frame.

  For still image reproduction, the motion

  magnetic tape 18 is stopped while the

  video heads 13a and 13b are rotated at a speed of

  which is the same as when registering or

normal reproduction.

  In fig. 4, when the head 13b, for example,

  mence are course starting from a position where it overlaps the tracks t6 and t7, it follows the course indicated in full line and finishes its course in a position where it overlaps the tracks t5 and t6. Since the band 18 is stopped, the head 13a too, its end face 6a along the same path as the end face 61b of the head 13b, begins its journey from a position where it overlaps the tracks t6, t7 and t8 and ends his journey in a position o

  it overlaps tracks t5q t6 and t7. Then the operation

ration above is repeated.

  The heads 13b and 13a have a normal course relationship respectively with the tracks t6 and t2. For this reason, the level of the signal reproduced by the heads 13b and Ia is that indicated in FIG. 51 which represents, as a function of time, the scanning period of the heads Ia and 13b and the level L of the signal reproduced in d 6 e It is assumed here that the relative positions of the heads of the heads Ia and 13b with respect to the band are shifted ,

  for example to the left, relative to the states represented

  felt in the figure. In such a case, the level of reproduction

  Ll when the head 13b begins to travel the track t6 increases, but the reproduction level L2 at the time of completion of the course decreases. In addition, the reproduction time of the maximum level L3 of the head

  13a with respect to runway t7 becomes short, and the

  portion of the course of runway t5 at the time of purchase

  course relative to runway t7 increases.

  For this reason, there is interference in the neighboring part of the L4 level. On the other hand, when the relative path positions of the heads 13a and 13b on the strip are shifted to the right relatively

  the states shown in the figure, the level of reproduction

  LI duction decreases starting from the t6 track of the head

  Ib, the signal-to-noise ratio of this part of reproduction

  duction being greatly diminished. As a result, the state

  the most desirable of the course of the heads 13a and 13b

  to the tracks during the reproduction in freeze frame is that indicated in FIG. 4. Then, when the control signal is recorded by the head 27, the recording of the tracks t2 (t4, t6 ...) by the head 13b begins. Therefore, if the motion of the tape is stopped arbitrarily at a desired moment of free-picture reproduction, while the magnetic tape 18 thus recorded is set in motion and reproduced, the stopping position of the tape 18 relatively to the heads is indefinite. For this reason, manipulation operations are required to move the web a small distance so that the optimum state of travel of FIG. 4 is reached after stopping the movement of the tape, or so as to observe the reproduced image while the tape is being driven at a low speed and

  movement of the tape at the moment when noise, interference

  etc. become minimal. These de-manual operations

  are bothersome and require skill and

experience.

  If we immediately stop the movement

  of the tape at the moment when the control signal is re-

  produced, the head 13b takes the state where it begins its journey starting from the track t6, for example, while the head 13a takes the state where it starts its course starting from tracks t6 and t? as indicated

  fig. 6. In such cases, while the level of reproduction

  duction of the t6 track is maximum when the head 13b begins its journey, it becomes almost zero when

  the completion of the course and the noise becomes very big.

  In addition, the signal reproduced from tracks t7 and t5 gives rise to interference for a certain time after the beginning of the path of the head 13a, and the

  quality of the reproduced image is strongly altered.

  On the other hand, the optimal positions of head travel relative to the tracks for reproduction in freeze frame, as shown in FIG. 4, are the positions where the end faces 61a and 61b of the heads 13a and 13b run through the dashed line of FIG. 6. Accordingly, in the invention, the magnetic tape 18 is moved a distance of a distance f 1 and is then stopped once the control signal has been detected, the movement of the tape is stopped while the heads 13a and 13b are in the position where they

  can make their journey in the optimal state indi-

that in fig. 4.

  The freeze reproduction operation is now described according to the first embodiment of

  the invention, again with reference to FIG. 1. The provision

When it is in the state of the normal reproduction mode, if the manipulation button (not shown) corresponding to the reproduction mode in freeze frame is pushed, the switches 28 and 41 switch and are connected to their contact points S At the same time, triggering pulses, as indicated in FIG. 7 (A), are applied by a terminal 50 to a flip-flop 49 to trigger it. Then, a control signal reproduced by the control head 27 and having the shape

  wave shown in fig. 7 (B) (the same as the one indicated

  as in fig. 2 (G) except that the time axis is compressed) is passed through switch 26 and

  the amplifier 44 to a monostable multivibrator 47.

  The latter, whose time constant is regulated by a variable resistor 48, gives as output a signal of a waveform which goes down in response to a positive polarity control signal as shown in FIG. 7 (0) and rises after the lapse of a time t2 determined by the time constant mentioned above. The output signal of the flip-flop 49 takes a waveform that rises in response to a trigger pulse from the terminal 50 and goes down in response to a rise in the output of the monostable multivibrator 47, such as the

shows fig. 7 (D).

  Switch circuit 43 is switched to its point of contact S in response to the descent of the output of flip-flop 49. Accordingly, as shown in FIG. 7 (E), the signal from the capstan servo circuit 40 is applied to the motor 20 until the switch 41 is switched and after this switching and until the switch circuit 43 is switched, the signal from the latch 49 is applied to the motor 20 which rotates, causing the magnetic tape 18. However, when the switch circuit 43 is switched, the motor 20 is set

  to the ground by the point of contact S and stops immediately

  as shown in fig. 7 (F), and the tape

tick stops his movement.

  So after the command manipulation for the

  reproduction in freeze frame, the magnetic tape

  tick 18 arrives at the complete stop after a time t3 (equal to the sum of the time mentioned t2 and the rotation time of the motor 20 per speed acquired), starting

  detection of the positive polarity command signal

  tive. The distance -S indicated for freeze 6 is

  determined by this time t3 which is itself set in function

  time t2. As a result, the resistance is

  variable 48 and the delay time t2 of the multi

  monostable vibrator 47 so that the distance between the detection of the control signal and the point where the magnetic tape 18 arrives at the complete stop is the

  desirable distance t mentioned previously.

  In a real example, the distance A is about

  0.4 mm and the delay time t2 is of the order of

milliseconds.

  We now describe in connection with FIG. 8, an example of a modification of an essential part of the embodiment described above. In fig. 8, the parts which are similar or equivalent to corresponding parts of FIG. 1 are designated by the same

  references and are not described again in detail.

  Flip-flop 49 provides an output signal having a shape

  wave which, as shown in fig. 9 (C), shows in response

  to a trigger pulse shown in fig. 9 (A) applied through terminal 50 as a result of the control manipulation for the reproduction mode.

  freeze frame and goes down in response to a com signal

  positive polarity command, shown in fig. 9 (B),

  reproduced by the control head 27 and applied without

  use a monostable multivibrator. The switching circuit

  Actuator 43 is switched to its point of contact S by the falling part of the output signal of flip-flop 49. As a result, the voltage waveform applied to motor 20

  becomes that indicated in fig. 9 (D).

  A variable resistor 70 is connected between the

  contact point S of the switching circuit 43 and the mas-

  is. Therefore, the motor 20 rotates by inertia for a time t4 which is a little longer than in the embodiment of the freeze 1, when the switch circuit 43 has been switched to its point of contact S as indicated by fig. 9 (E), then stop. Here, the variable resistor is set such that this time t4 of rotation of the motor 20 by inertia is equal to the time that the

  magnetic tape 18 to travel the distance l and to s'ar-

  to stop, starting from the moment of the detection of the control signal. In some cases, the acquired speed (inertia) of

  the rotation set of the capstan, including the cabs-

  tan 19, the motor 20, the head 21 and the flywheel 22, is excessive so that the movement of the magnetic tape can not stop entirely on the distance P after detection of the positive polarity command signal by the devices shown in figs. I and 8. In such a case, an arrangement is used in which a negative polarity command signal is used instead of a positive polarity command signal, reproduced by the control head 279 to trigger the monostable multivibrator 47 or the In another exemplary embodiment, a second control head (not shown) is provided at a point spaced from the control head 27, by a distance f2 given by the following relationship and the motor 20 is stopped by a control signal reproduced by this second head

control: -

  Z 2 = 1 + 2P * n - t0 3, - P being the pitch of the track on the magnetic tape 18, - n an integer and - 3 the movement distance of the magnetic tape 18 under the effect of the inertia of the set of

capstan rotation.

  As stated above, according to the device of the invention, optimal reproduction is achieved by

  freeze frame with minimum noise and interference

  in response to a command manipulation for the

  playback mode in still picture. We describe

  after the operation of performing idle reproduction with the minimum of noise and interference

  by the application of the principle of this reproduction op-

timal in freeze frame.

  When performing the control manipulation for the idle reproduction mode of operation, the switches 26, 28 and 36 of the device of FIG. 1 to their respective contact points P and the switch 41 is connected to its point of contact S while

  a switch 53 is closed. In addition, the

  division port of a frequency divider 51, which receives the output of the flip-flop 35, according to the slow reproduction speed. For example, for a reproduction at a speed reduced by half, one rule

  the ratio of frequency division to 1/2.

  The output signal of the flip-flop 35, shown in FIG. 10 (A) and which is the same as the signal e of FIG. 2 (E) except that the time axis is compressed relative to that of FIG. 2 (E), is subject to

  frequency division by two in the frequency divi-

  quence 51 which thus sends to a monostable multivibrator 52 an output signal of the waveform indicated in FIG. 10 (B). This monostable multivibrator 52 thus produces an output signal of the waveform indicated in FIG. (C) descends in response to a rise of the signal from the frequency divider 51 and goes up after a determined time. This output signal is applied via the switch 53 to the flip-flop 49. On the other hand, a control signal reproduced by the control head 27, indicated in FIG. 10 (D), and which is the same as that of FIG. 7 (B), is brought to a

  monostable multivibrator 47 which then provides the basement

  FIG. 49 shows a signal of the waveform shown in FIG. (E) and which is the same as the signal shown in FIG.

  7 (C). Flip-flop 49 produces an output signal which,

  tell me, fig. 10 (F), rides in response to a climb

  signal from the monostable multivibrator 52 and

  in response to a rise in the signal from the multi-

monostable vibrator 47.

  During the high-level time (duration of 2 frames)

  of the output signal coming from the flip-flop 49, as the

  say fig. 10 (F), the motor 20 rotates and the machine band

  Gnetic 18 moves at a distance equal to twice the pitch of the track. Then, during the low-level time

  (duration of the next 2 frames) of the signal, the circuit

  mutator 43 switches to its point of contact S, and the motor 20 stops, so that the magnetic tape

  18 stops. Similarly, then, the functioning

  cyclic, in which the magnetic tape 18 moves twice the track and stops, repeats itself

every two frames.

  So when the average speed of the magnetic

  tick 18 when its movement is the normal speed, we get a normal reproduced image in a period

  two frames and a still image is obtained in the

  of 2 frames that follows. As a result, as a result

  overall average, we obtain a reproduction at a high speed

  half-off. In this operation, in each case of

  reproduction in freeze frame, both of which

  frames of 2 frames, the magnetic strip 18 stops in

  a position where there is the minimum of noise and interference

  ferences and that is shifted from the distance relatively

  at the position during the reproduction of the com-

  This is similar to the still image reproduction operation described above. For this reason, no noise is created of course in the normal reproduction which occurs every two periods of two frames and there is almost no noise No More in the freeze frame reproduction which. occurs during the other periods of two frames. One gets

  therefore an image reproduced in slow motion having a good quality

  free of defects such as noise and interference.

  In this regard, the frequency division of the frequency divider 51 is set in accordance with the idle ratio, and the still picture reproduction time is thus set so that slow reproduction is achieved at the desired speed. For example, for slow speed reproduction at 1/3, you set 1/3

  the ratio of the frequency divider 51. The signals indicated

  as in fig. 10 (B) and 10 (C) then become 6-frame period signals, and the signal indicated in FIG. (F) becomes a high level signal for a period of 2 frames and a low level signal for a period of 4 frames. As a result, the normal reproduction takes place during a period of 4 frames so that globally,

  we obtain a reproduction at a reduced speed to the third.

  The invention is not limited to the examples of

  realization, represented and described in detail, because

  its modifications can be made without going out of

its frame.

Claims (7)

  1 - Device for reproducing video signals   recorded on a tape along video tracks   obliquely in relation to the longitudinal direction   the band, practically without. spacing therebetween, a control signal being recorded on a control track in the longitudinal direction, the video tracks being recorded and formed by a plurality of rotating video recording heads having air gaps having an azimuth angle of different , the signal   command being recorded along the runway   in a manner related to the recording and the formation of the video tracks by the video heads, characterized in that it comprises reproduction means comprising a plurality of rotating video heads (13Y, 13a) for   reproduction and functioning in order to   the video track so as to play back and play the recorded video signal, the rotating video heads   with gaps whose azimuth angle is different   these angles being respectively equal to the first   azimuth angles, the air gaps having   different heights above the plane of rotation of the center of the tracks in the direction of their width, and means (47, 49, 43) for delaying by a predetermined time the control signal reproduced according to the band of way to get a delayed signal and use that   delayed signal to stop the printed motion.   band by the driving and stopping means (19, 20), the stopping band, relative to the video heads of   reproduction, in a relative position where reproduction is   video heads is performed so that the time when the level of the reproduced video signal becomes minimal is within the frame blanking period. or around this period.   2 - Device according to claim 1, characterized   characterized in that the means for braking and stopping the belt comprise a capstan (19) and a motor (20) for engaging the rotating capstan and the means for stopping the movement printed on the belt by the driving and stopping means comprise switching means 43 for supplying the electrical energy for driving and cutting the motor and means (47, 49) for delaying the signal by a determined time command reproduces to obtain a   delayed signal and use this delayed signal to   cer the switching means in their cutoff state.   3 - Device according to claim 2, characterized   characterized in that the switching means (43) are designed such that, in their cut-off state, the   motor is connected directly to the ground.   4 - Device according to claim 2, characterized   characterized in that between the switching means (43) and the ground is connected a variable resistor 70, the switching means being designed such that, in their cut-off state, the motor is connected to ground   through the variable resistor.   Device according to Claim 2, characterized in that a reproduction of the signal is carried out   freeze video and that the means   for producing a delayed signal comprises means (47) for delaying the reproduced control signal by a predetermined time and means (49) for producing a voltage waveform that rises in response to a mode signal reproduction in freeze frame   and goes down in response to the delayed signal.   6 - Device according to claim 2, characterized   in that a reproduction of the video signal is carried out at idle, and that means (33a, 33b, 34) are furthermore provided for detecting the rotation of the reproducing rotating video heads so as to produce a signal   rotation detection means and means (51)   to divide in frequency the detection signal of   the means for producing the delayed signal comprising means (47) for delaying the reproduced control signal by a predetermined time to provide a delayed signal and means (49 for generating a waveform of rising tension   response to an output signal from the division means   frequency and goes down in response to the delayed signal.   7 - Device according to claim 6, characterized   characterized in that the frequency dividing means (51) are designed so that their division ratio varies and is adjusted according to the idling ratio of the reproduction of the video signal.   8 - Apparatus for reproducing video signals recorded on a tape along video tracks directed obliquely to the longitudinal direction of the tape, substantially without spacing therebetween,   control signal being recorded on a communication track   in the longitudinal direction, the video tracks being recorded and formed by several heads   rotating video recording featuring   irons whose azimuth angle is different, the control signal being recorded along the control track in a manner related to the recording and the formation of the video tracks by the video heads, characterized in that it comprises reproduction means comprising several   rotating video heads (1Ia, 13b) for reproducing   and operative to successively browse the video track to read and reproduce the recorded video signal, the rotating video heads having gaps whose azimuth angle is different, these angles being respectively equal to the first azimuth angles mentioned, air gaps having positions of   different height above the plane of rotation of the   tracks in the direction of their width, means for reproducing the control signal in a position (ú2) offset relative to the recording position and means (47, 49, 43) for stopping the movement printed at the band by means (19, 20) for driving and stopping the band using the   control signal reproduces, the band stopping,   to the reproduction video heads, in a position where the reproduction by the video heads is made such that the moment when the level of the reproduced video signal becomes minimal is within the suppression period   frame or in the vicinity of this period.