JPS5838861B2 - Jiki Tape Couch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic tape device that uses three rotating magnetic heads to sequentially record video signals on linear tracks in units of l fields in the length direction of a magnetic tape. In particular, with the magnetic tape running at a constant speed, video signals in one field unit are recorded in a continuous manner with each recording length being constant, and the video signals are recorded in the field unit. It is an object of the present invention to provide a magnetic tape device that can also record audio signals related to video signals.

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 1 includes a perspective view of the main parts of a tape running system and a rotating magnetic head/drum section in an embodiment of the present invention that allows audio and still images to be simultaneously recorded on a tape and the recorded tape to be played back. FIG. 2 is a block configuration diagram of an electric circuit.

FIG. 2 is a plan view of essential parts of the tape running system and rotating magnetic head/drum section, and FIG. 3 is a diagram of the magnetic track pattern of the tape used in this embodiment.

Now, in explaining the present invention, it is necessary to describe a method for simultaneously reproducing still images and audio from a tape having a magnetic track pattern diagram shown in FIG. 3, and then to explain a method for recording signals on the tape. Since it is easy to understand, I will explain the playback method first.

First, in Figures 1 and 2, tape 1 is capstan 1.
2 (driven by a motor 19) and a pinch roller 13, it is driven to run at a constant speed in the direction of an arrow 14.

As the tape 1 is running, a rotating magnetic head/drum device 2 for reproducing video signals and a fixed magnetic head 11 for recording and reproducing audio signals are arranged as shown.

The recording pattern of the tape 1 is as shown in FIG. 3, with a track 56 recording a video signal and a track 57 recording an audio signal.

As the tape 1 runs, the magnetic head 11 reproduces the audio signal recorded on the track 57, which is amplified by the amplifier 21 shown in FIG. 1, and if a speaker is connected to the output terminal 42. You can hear the audio.

On the other hand, the rotating magnetic head/drum device 2 includes three rotating magnetic heads arranged at equal intervals (120° intervals in this embodiment) for tracing the video signal track 56 in FIG. 3 and reproducing the video signal. 5, 6.7 are provided.

Further, the tape 1 is wound around the drum 8 of the rotating magnetic head/drum device 2 in an 8-shape over two-thirds or more of the entire circumference.

Furthermore, on the video track 56 of the tape 1, A is shown in FIG.
As shown by B, C, etc., video signals of fields with different contents are recorded sequentially, each field having the same length, and It is equal to the length on the drum 8 between each head.

Therefore, a length of tape longer than two fields is always wound on the drum 8.

Furthermore, the arm 4 to which the rotating magnetic head 5.6.7 is attached
is attached to the motor shaft 9 of the motor 23, and the arm 4 is rotated in the direction of arrow 15 by the motor 23.

Therefore, in this apparatus, the rotary magnetic heads 5, 6, 7 rotate in the opposite direction to the running direction of the tape 1.

Now, rotate the motor 23 at 20 rpS, and make the length of one field of the video signal track of the tape 1 1671.
If it is n71L, the circumferential length of the drum 8 will be 167×3:500 mm from the above.

Therefore, the peripheral speed of each rotating magnetic head 5, 6.7 is approximately 10
m/sec.

In the Japanese-American standard television system, the video signal usually includes a signal of about 0 to 4 MHz, but at the above-mentioned peripheral speed, the above-mentioned signal can be reproduced.

By the way, since the tape 1 is traveling at a constant speed in the direction of the arrow 14 as described above, the third tape attached to the drum 8 is
A shown in the figure.

B, C,...fields move sequentially on the drum, but since there is always more than two fields of tape on drum 8, there is no need to move anywhere on drum 8. There must necessarily be a complete l field that each rotating magnetic head 5, 6.7 traces in turn.

Therefore, as tape 1 moves, the field that can be completely played also moves, but if that complete field leaves the drum even a little, the next field becomes a complete field, and that field is played back this time. In this way, still images are sequentially reproduced by the rotating magnetic heads 5, 6, and 7 (the same field is reproduced multiple times, resulting in a still image).

) Now, set the running speed of tape 1 to 47.5 mrn/s.
ec, the time for one complete field on the drum is 167747.5 = 3.6 seconds, and the same field is played for 3.6 seconds.

By the way, if we consider the part where the screen changes, that is, the point where the screen switches from field B to field C in Figure 3, in this case, fields B and C are both on the circumference of drum 8. This is the point at which the tape is ready for complete playback.

In such a case, one magnetic head, for example, the magnetic head 5, only needs to reproduce field B and then field C, and when a new field C begins to be reproduced, subsequent rotations will start as described above. The C field can be reproduced repeatedly using a magnetic head.

By doing this, the image will not be cut off even when the screen is switched.

Now, if we consider the case where the fields A, B, C, D, etc. in FIG. At 6.7°, output signals as shown in A22B and C in FIG. 4 are obtained.

This figure shows the case in which fields B and C are placed on the drum 8.

In addition, χ and B! shown in Figure 4 A2 and C! , c', and v indicate reproduction signals of fields A, B, C, and D on the tape.

Now, from the above, in order to obtain continuous still images, it is sufficient to extract a necessary portion of the output of each magnetic head so as to finally obtain a signal as shown in FIG. 4-2.

For this reason, Figure 2 has the following configuration.

That is, the outputs of the rotating magnetic heads 5, 6, 7 [A2 in FIG.
2B and C are gate circuits 25.26.2 which are taken out from the rotating system by a rotating transformer 16°17.18 and include an amplifier.
7.

(However, the signal from the rotary transformer 16 passes through a gate circuit 24, which will be described later.

) The gate circuits 25, 26, and 27 are also supplied with the gate signals shown in FIG. .27, a signal in which only the diagonal lines among the output signals shown in FIG. 4 are gated is obtained.

If these are mixed in the mixer 28, the signal shown in FIG. 4, 2, is obtained.

By the way, in magnetic recording and reproducing devices, video signals are often recorded by performing frequency modulation due to the problem of level fluctuations and the difficulty of recording low frequency signals. It is sufficient to demodulate the mixed signal shown in FIG. 4 2 in the demodulator 29 shown in the figure.

The demodulated video signal becomes as shown in FIG. 4E.

Therefore, by connecting a monitor television receiver to the terminal 55, still images can be reproduced, and audio signals reproduced from the audio reproduction magnetic head 11 can also be heard at the same time.

On the other hand, the gate signals shown in FIG.

The video signal obtained by the demodulator 29 is first supplied to a vertical synchronizing signal separator 30 to extract only the vertical synchronizing signal as shown in FIG.

Further, this signal is delayed by a delay circuit 31 as shown in FIG.

The phase of this delayed signal will be described later, but it coincides with the joining position (solid line portion) of each field shown in FIG. 4-2.

In addition, Figure 4 A. The dotted lines shown at the top, c, and 2 indicate the reproduction position of the vertical synchronization signal.

This delayed vertical synchronization signal is then sent to the ring counter 32.
Clock input terminal T (also called toggle input terminal)
supplied to

On the other hand, a permanent magnet 10 is fixed to the arm 4 that rotates integrally with the motor shaft 9, and the permanent magnet 10
A magnetic head 9a is fixedly arranged above the rotating orbit.

This magnetic head 9a has a fourth magnetic head every rotation of the motor 23.
A pulse signal as shown in the figure (h) is obtained.

This pulse signal is generated because the rotating magnetic heads 5, 6, and 7 are rotated by the motor 23.
There is a constant phase relationship with the rotation of the rotating magnetic heads 5, 6.7.

Therefore, by amplifying the output signal of the magnetic head 9a [FIG. 4C] by the amplifier 33 and further delaying it by the delay circuit 48, the signal shown in FIG. Obtainable.

If this signal is supplied to the set input terminal S of the ring counter 32, the count of the delayed vertical synchronization signal input to the clock input terminal T is switched to another field (changes from B' to C in FIG. 4). By setting the gate signals in the section), it is possible to obtain gate signals such as N, R, and O in Fig. 4.

As is clear from the above explanation, this method is characterized by the fact that a closed loop is formed by generating a gate signal using the reproduced signal, and creating a gate signal using the gated reproduced signal. However, by changing the delay time of the vertical synchronizing signal using the delay circuit 31 described above, it is possible to appropriately change the phase at the joint between each field.

Further, by appropriately changing the rotational phase shown in FIG. 4H using the delay circuit 48, the time point at which the image is switched to another image can be changed.

This point will be described in more detail.

As mentioned above, two or more fields of magnetic tape 1 are wound around the drum 8, and since the entire circumference of the drum 8 is three or more fields, signals are reproduced by each magnetic head. The period of time is 2 fields or more.

For example, in the second reproduced signal from the left in Figure 4A, in addition to the complete fields B' and C', A' and Dlo)
Some have also been played.

The period during which two complete fields are played is determined by the length of the tape that is hung on the drum 8.
Similarly to the above, if one field length is 167 mrrt, and if a tape with a length of, for example, 364 mm (167 x 2 + 30) is wound around the drum 8, two complete fields will be played back while the tape moves for only 30 minutes. become.

Now, set the running speed of tape 1 to 47.5 urn/se.
If c, two complete fields are reproduced for 0.63 seconds.

Therefore, by appropriately changing the set pulse shown in the fourth diagram using the delay circuit 48, it is possible to change the screen switching point, for example, in the above time period.

Further, the above time period can be appropriately determined by changing the length of the tape wound around the drum 8.

By the way, the video signal and the audio signal are recorded on the tape 1 in correspondence with the audio reproduction magnetic head 11 and the position where the image is switched (the generation position of the set pulse described above). The position of the head drum device 2 may not correspond to the above correspondence.

In such a case, by adjusting the delay circuit 21 described above, the reproduction timings of the video and audio information can be matched.

The method for reproducing video and audio signals from a magnetic tape on which video and audio signals have been previously recorded as shown in the magnetic track pattern diagram of FIG. 3 has been described above.

In this case, the rotating magnetic head rotates at a constant speed regardless of the tape speed, so if you change the tape speed or stop the tape and play the video signal, the relationship between the tape and the rotating magnetic head will change in each case. The relative speed will be different.

Along with this, the synchronization signal period of the reproduced video signal also differs, so if the reproduction signal is applied to a monitor television receiver, in extreme cases, the horizontal and vertical synchronization may be disrupted on the television receiver, causing playback. You may not be able to view the image.

Next, we will discuss how to eliminate this problem.0 Conventional removal methods involve mechanically coupling the tape drive section and the rotation drive section of the rotary head using differential gears, etc., and changing the tape speed. There was also a method to prevent the relative speed between the rotating head and the tape from changing.

However, with this method, high-precision control could not be expected due to the rattling of the gears.

On the other hand, unlike the above-mentioned method, the method according to the present invention is electrical, so it can be controlled to a higher degree and can be carried out with a simple configuration.

This will be explained using the embodiment shown in FIG.

As shown in FIG. 1, when the direction in which the tape 1 advances (arrow 14) and the direction in which the rotary head rotates (arrow 15) are opposite,
If the tape speed is υ and the circumferential speed of the rotating head is υR, then
The relationship between the relative speed υM of the tape and the rotating head is as follows.

Therefore, even if the tape speed υ1 changes, if we try to make this relative speed υM constant at Ion/sec, the circumferential speed υR of the rotating head, that is, the rotational speed of the drum motor 23, will be reduced by the amount of change in the tape speed δυ1. Just lower it.

This can be expressed mathematically as follows, and the relative speed between the rotating head and the tape is the same as υy shown in equation (1).

However, in order to reduce the rotational speed of the drum motor 23 by the amount of change δυ1 in the tape speed, it is necessary to control the rotation of the drum motor 23 while constantly detecting the tape speed at that time.

Therefore, to detect the speed of the tape, it is necessary to record some kind of speed detection signal on the tape and detect it.

For this reason, in the past, a dedicated track was set up on the tape to record a continuous signal of a single frequency, and the signal was played back to detect the speed, or the signal and weight were recorded on a speed detection signal recording track. During playback, speed has been detected from a speed detection signal separated by a filter.

However, the above method has drawbacks such as requiring a separate track and requiring troublesome signal processing.

The present invention eliminates these drawbacks and automatically makes the relative speed between the rotating head and the tape constant regardless of the tape speed.

In FIG. 1, the oscillator 45 generates a pulse signal having the same period as the vertical synchronizing signal period of the television signal as shown in FIG.
59.95-Fl 6.6 m-5ec) and feeds this signal to the trapezoidal wave generator 40.

This trapezoidal wave generator 40 obtains a signal shown in the fourth diagram.

A phase comparator 41 that further compares the phases of two signals with this signal.
supply to a.

This phase comparator 41a also receives a vertical synchronizing signal shown in FIG. Then, for example, by sampling and holding, the phase error voltage of both signals can be obtained.

By the way, the above-mentioned delayed vertical synchronization signal is obtained as follows.

As mentioned above, the demodulator 29 obtains a reproduced video signal (the signal shown in FIG. 4, E).

By supplying this reproduced video signal to the vertical synchronization signal separation circuit 30, the vertical synchronization signal shown in FIG.
7, the delayed vertical synchronization signal shown in FIG.

Therefore, the drum motor 2 can control the phase of the phase error signal obtained from the phase comparator 41a via the drive amplifier 41b.
3, the drum motor 23 is controlled so that a reference signal having the same period as the vertical synchronization signal obtained from the oscillator 45 and the vertical synchronization signal of the reproduced video signal maintain a certain phase relationship. .

Let me explain this point in a little more detail.

Vertical synchronization signal obtained from the vertical synchronization signal separation circuit 30 [
4] is the recording position of the vertical synchronization signal of the video signal recorded on the tape on the drum, that is, the time at which the rotating magnetic disk reproduces the vertical synchronization signal, in other words,
It shows the rotational phase of the rotating magnetic helad.

Therefore, if the drum motor 23 is controlled by the error signal obtained by comparing the phases of the reference signal from the oscillator 45 and the reproduced vertical synchronization signal delayed by a certain period of time using the phase comparator 41a,
As shown in FIG. 4, the phases of the reproduced video signal [FIG. 4 e] and the reference signal [FIG. 4 w] match.

Now, it will be explained why, when controlled in this way, the relative speeds of the tape and the rotary head match regardless of the tape speed.

Now, if the tape speed is υ, the frequency of the reference signal is fs (59.95Hz as mentioned above), and the radius of the drum is γ (the radius of rotation of the rotating magnetic head), then the vertical synchronization signal phase of the reproduced video signal is is the period T s of the reference signal as described above
""t, so the distance the tape advances during this Ts dark time is υIXTs.

Therefore, if the circumferential speed of the rotating head is υR, then 2π Here, ωR−〒 means that one head moves the drum 33T=,
- XT means the angular velocity for one revolution in time, and when the frequency of the reference signal is constant, this value is constant.

In other words, it is the peripheral speed of the drum when the tape is stopped.

Therefore, the relative speed υM between the tape and the rotating head is υM = υR + υ1 from equation (1), so by substituting equation (4), υ
M=υR+υt=(γ・ωR−υt)+υt=γ・ωR
This value is υR when the tape is stopped and is constant, regardless of the tape speed.

It goes without saying that this relationship holds true even when the tape speed is zero, that is, when the tape is stopped.

Next, it will be explained that the above is also applicable to recording, that is, video signals can be recorded and reproduced at the same relative speed during both recording and reproduction.

First, the audio signal is supplied from the terminal 43, and the recording amplifier 22
The signal is amplified and supplied to the fixed magnetic head 11 via the R terminal of the switch 20 and recorded on the tape 1.

Since this point can be performed in exactly the same way as an audio tape recorder, the explanation will be omitted.

On the other hand, a video signal is supplied from the terminal 44 and recorded by the method described below.

The video signal shown in FIG. 5a supplied to the terminal 44 is applied to a vertical synchronizing signal separation circuit 46 and a frequency modulator 51, which will be described later.

The signal obtained from the vertical synchronization signal separation circuit 46 is the signal shown in FIG. 5, and has the same period as the reference signal obtained from the oscillator 45.

(That is, in the case of recording, instead of switching the power supply of the oscillator 45, the vertical synchronization signal of the video signal obtained from the vertical synchronization separation circuit is supplied to the trapezoidal wave generator 40.

) If this vertical synchronization signal is supplied to the trapezoidal wave generator 40,
As mentioned above, the signal shown in FIG. 5C is obtained.

Next, in the same manner as described in the method for reproducing the tape 1 to be recorded, the tape 1 is wound around the drum 8, and the tape 1 is driven to run using the capstan and the pinch roller.

(Stop until the first field is recorded.

) Now, at first, without even recording an example on tape,
Since no reproduction signal is obtained from the demodulator 29, the drum motor 23 cannot be controlled by the vertical synchronization signal of the reproduction signal as described in the reproduction method.

Therefore, until the first field is recorded on the tape, fixed magnetic heads 9 are placed at 120° intervals.
The drum motor 23 is controlled by applying a signal indicating the rotational phase of the rotating magnetic head obtained from a+9b and 9c to the phase comparator 41a.

The process by which the rotational phase signals of the rotating magnetic head are obtained from the magnetic heads sa, 9bs, and 9c will now be explained in more detail.

The fixed magnetic heads 9a, 9b, 9c are arranged at equal angular intervals on the drum as shown in FIG. 2, so they are mounted on the arm 4 on the side where the rotating magnetic head 5 is located. Each time the permanent magnet 10 passes under the magnetic heads 9ap9b, 9c due to the rotation of the motor 23, pulse signals shown in FIG. 5d, e, and f are obtained from those magnetic heads.

Therefore, the output pulse signals of the magnetic heads 9a, 9b, and 9c are supplied to the amplifiers 33, 34, and 35 for amplification, and further mixed by the mixer 36, resulting in a signal as shown in FIG. 5g.

(This signal indicates the rotational positions of the three rotating magnetic heads 5, 6.7.

) This signal is passed through a switch circuit 39 (described later) [the output signal of the switch circuit 39 is shown in FIG.
The phase comparator 41a is supplied with a signal delayed for a certain period of time [the signal shown in FIG. Therefore, the phase error signal of the above two signals can be obtained here.

When this is supplied to the drum motor 23 via the drive amplifier 41b, the rotating magnetic head rotates with a constant phase relationship with the vertical synchronizing signal of the video signal supplied from the terminal 44.

Now, when the magnetic heads 9a, 9b, and 9c are arranged while controlling the drum motor 23 in this way, as shown in FIG. ) and the center of the drum, and if magnetic heads 9a and 9c are placed at an interval of 120° to the left and right of this magnetic head 9b, one of the rotating magnetic heads will move point a and One field of video signals can be recorded between points b.

Therefore, let us consider recording one field of video signals between points a and b using the full rotation magnetic head 5.

In this case, it is necessary to extract and record the signal of one field, which is exactly temporally between points a and b of the rotating magnetic field 5, from among the video signals supplied to the terminal 44.

The method for extracting this signal will be described below.

First, the rotational phase pulse of the magnetic head 9a (signal of the amplifier 33 shown in FIG. 5d) is supplied to the phase comparator 49a.

The signal shown in FIG. 5m, which is the output signal of the switch circuit 39, is also applied to the phase comparator 49a.

Now, if a recording start command signal is applied to the terminal 49c from time t1 as shown in FIG.
At the point where the phase of the rotational phase pulse shown in FIG. d and the output signal of the switch circuit 39 shown in FIG. 5 m match, the pulse shown in FIG. 5 q is obtained.

[As mentioned above, the signal in FIG. 5 m is a rotational phase pulse signal, so the pulse in FIG. 5q indicates the rotational phase pulse in FIG. ing.

] Next, the signal shown in FIG. 5q obtained from this phase comparator 49a is supplied to a gate signal generator 49b.

This gate signal generator 49b generates the signal shown in FIG.
As shown in Figure R, 1/3 V (V is vertical synchronization period 4 divided by 1
6.6 m5), and from this signal, a gate pulse of about 2 V period as shown in FIG. 5g is generated.

Furthermore, the signal shown in FIG. 5g obtained from the gate signal generating circuit 9b is supplied to the gate circuit 50.

The gate circuit 50 is also supplied with a signal shown in FIG. 5p, which is obtained by delaying the vertical synchronizing signal [FIG. 5b] of the input video signal obtained from the vertical synchronizing signal separation circuit 46 by a certain period of time in a delay circuit 47. , by gating this signal with the signal in FIG. 5g to obtain the signal shown in FIG. 5t.

Next, the signal shown in FIG. 5t obtained from this gate circuit 50 is applied to the input terminal T of the flip-flop 54, and the rotational phase pulse shown in FIG. If so, flip flop 5
At the output Q of 4, a signal shown in FIG. 5U is obtained.

Furthermore, the inverted signal of FIG. 5U is obtained from the output terminal Q of the flip-flop.

These signals are respectively supplied to a gate circuit 52 and a gate circuit 24, which will be described later.

By the way, when recording video signals on tape, frequency modulated video signals are often recorded.
The video signal [FIG. 5a] supplied to the input terminal 44 is supplied to the frequency modulator 51 to obtain a frequency-modulated video signal in advance.

If this signal is supplied to the gate circuit 52, the gate circuit 5
2, the signal of FIG. 5 is obtained in which the frequency modulated video signal is gated with the signal of FIG. 5U.

When this signal is supplied to the rotating magnetic head 5 via the buffer amplifier 53 and the rotating transformer 16, the gated video signal is recorded between the point a and the point 16 on the drum 8.

Now, until this first field is recorded on a blank tape, the tape is stopped, that is, the capstan motor 19 is not rotating.

Then, at the same time as this field is recorded, power is supplied to the capstan motor 19 to rotate it.

When the tape 1 begins to run in this manner, the recorded video signals are simultaneously reproduced from each rotary magnetic head 5, 6.7.

The signals reproduced from each rotating magnetic head 5, 6.7 are
However, the signal indicated by the internal medicine line is the recorded signal itself, not the reproduced signal.

Now, by mixing and demodulating the signals reproduced from the above-mentioned rotating magnetic heads 5, 6.7, the recorded video signal can be reproduced.

That is, if the reproduced signals from each rotating magnetic head 5, 6.7 are amplified by the gate circuits 25, 26, and 27 including the amplifiers, and then mixed by the mixer 28 and demodulated by the demodulator 29, the terminals are A demodulated video signal is obtained from 55.

The method of generating the gate signals to be applied to the gate circuits 25, 26, and 27 has been described above, so the explanation thereof will be omitted here.

The buffer amplifier 53 and gate circuit 24 described above will now be explained.

This amplifier 53 performs amplification in only one direction.

That is, the frequency-modulated video signal shown in FIG. It has become.

Further, the gate circuit 24 includes an amplifier that can change the gain, and transmits the signal reproduced from the rotating magnetic head with a gain of 1 to the 5-gate gate circuit 25, and the recording signal from the buffer amplifier 53. , the level is changed to a level comparable to that of the reproduced signal and then supplied to the gate circuit 25.

The signal in the shaded area in the fifth diagram mentioned above means this signal.

, Now, after the first field is recorded as described above, a reproduced video signal is obtained from the demodulator 29, so the next vertical synchronization separation circuit 30 outputs a signal as shown in FIG. 5e. Vertical synchronization signal is obtained.

(This signal is generated immediately after the video signal is recorded.

) This signal is then supplied to the switch circuit 39 and the signal detection circuit 38.

This signal detection circuit 38 is connected to the vertical synchronization signal separation circuit 30.
When the vertical synchronization signal from the switch circuit 39 is supplied, the switch circuit 39
It provides a switch control signal to the

That is, as described above, when nothing is recorded on the tape at first, the switch circuit 39
The rotational phase pulse from the mixer 36 supplied to the mixer 36 is transmitted to the delay circuit 3T and the phase comparator 49a. ) has a switch circuit 39
The vertical synchronization signal is transmitted to the delay circuit 37 and the phase comparator 49a.
to communicate.

As a result, the output signal of the switch circuit 37 becomes as shown in FIG.

This is a rotational phase signal obtained from signals 9b and 9c, and is a vertical synchronization signal of a reproduced video signal after recording.

The first field is recorded as described above, and the second field is recorded as follows.

As described above, since the reproduced vertical synchronization signal is obtained from the switch circuit 39, after the first field is recorded, the drum motor 23 is connected to the vertical synchronization signal of the input video signal and the reproduced video. It is controlled by the vertical synchronization signal of the signal.

That is, the phase comparator 41a receives the trapezoidal wave described above (the signal shown in FIG. 5C generated by the trapezoidal wave generator 40 from the vertical synchronization signal).
Since the signal of FIG.

Now, in this state, the relationships of equations (3) and (4) above hold, and even though the tape is running, the relative position between the same tape that recorded the first field and the rotating head is Become the speed.

(The tape is stopped during the first recording.

) That is, when the tape is running, the peripheral speed of the rotating magnetic head is lower than when the tape is stopped by the variation in the tape running speed.

Therefore, the periods of the rotational phase pulses shown in FIGS. 5d, e, and f are different between the period until the first field is recorded and the reproduction state thereafter.

In other words, it becomes longer in the playback state.

Next, to record the second field, the tape is run and the second field is recorded when the tape section to be recorded comes from point a to point b on the drum shown in Figure 2. Since the first field is between points b and c, it should be connected to the first field.

From the above, it is sufficient to detect the point in time when the first field recorded comes between point b and point C, and record the second field in the same way as the first field was recorded. .

Although the time point at which the second field is recorded is not shown in FIG. 5, the signal waveform following FIG. 5 is shown in FIG.

These correspondences are from Figure 5a to Figure 4 Evening. Figure 5 b → Figure 4 wa, Figure 5 C → Figure 4 power, Figure 5 d → Figure 4 U, Figure 5 h → Figure 4 , Figure 5 i → Figure 4 tsu, Figure 5 j → Figure 4 tsu, Figure 5 → Figure 4 ne, Figure 5 m-'M4, Figure 5
Figure n → Figure 4 y, Figure 5 q → Figure 4 m.

The signals from FIG. 5 r to FIG. 5 U are not shown in FIG. 4, but if the signals in FIG. 4 a [FIG. 5 q] are obtained,
The one field gate signal shown in FIG. U can be generated from flip-flop 54 as described above.

From the above explanation, when the tape portion to be recorded reaches points a and b on the drum 8 shown in FIG. 2, one field of video signals is recorded.

In this case, the tape is stopped only for the first field, but the subsequent second, third, . . . fields can be recorded while the tape is running.

Moreover, all recorded fields have the same length, and the connecting portions between fields are also continuous.

That is, the video track 56 shown in FIG. 3 is recorded.

Here is the time interval t between recorded fields when recording as described above while running the tape.
i is the tape speed υ(” 4.76 (,7rL/Se
If the radius of rotation of the magnetic head for one rotation is r28cm, then t = 2 πr/3 v t = 3.6s. This time t1 is obtained from the phase comparator 49a as shown in Fig. 4A. This is the pulse period shown in .

The pulse signal shown in FIG. 4B is obtained from the signal obtained from the switch circuit 39 shown in FIG. 4B and the rotational phase pulse obtained from the magnetic head 9a shown in FIG. This is the time when the phases match.

Then, based on this signal, the field sampling signal,
That is, since the signal shown in FIG. 5U is obtained from the flip-flop 54, the pulse signal shown in FIG.
It must occur at a certain position on the drum 8, in this case at the position of the magnetic head 9a.

However, depending on the tape speed, the radius of rotation of the rotating head, and the period of the vertical synchronizing signal, pulses may not necessarily occur at the same position.

In order to make this match, a first-order condition is sufficient.

That is, if the number of fields between the fields (shaded areas) to be recorded as shown in the signal shown in FIG. 4 is 3n+1 (n is a positive integer), the above condition is definitely satisfied.

From this, we now set the tape speed to υ7 and the vertical synchronization signal period to T8. If the relative speed between the rotating magnetic head and the tape is υM, then 2π As mentioned earlier, υM2rωM−r''3T, so n near 0, r = 8.003zB υt=4
．． The above formula (5) holds true when the speed is 76 cm/sec and T5-59.95 SeC.

Next, considering the connection between fields recorded on a tape, when one field Be of a video signal is recorded every (3n+1) fields, adjacent fields may be different.

In other words, the input video signal is a general composite signal, that is, one frame constitutes one image, and the (3n+1)th field becomes an even number or an odd number depending on the value of n. or

Therefore, if (3n+1) is an even number, the (3n+1)th field will always be an even field, then all the recorded fields will be even fields, but if it is an odd field, the recorded field will be an odd field. It becomes all the time.

When (3n+1) is an odd number, (3n+1) appears alternately in odd and even fields, so that the fields recorded on the tape are alternately odd and even fields.

Now, if (3n+1) is an odd number, the adjacent fields will be even and odd, so the phase of the horizontal synchronization signal at the joint of the fields will be continuous, which is convenient when playing back a tape recorded in this way. In Although,(
If 3n+1) is an even number, the adjacent fields are the same, so there will be a phase difference of 1/2H (H is the horizontal synchronization period) of the horizontal synchronization signal at the joint, resulting in a difference in the phase of the television screen. An inconvenience occurs in that the upper part becomes distorted.

In such a case, that is, when (3n+1) is an even number, the continuity of the horizontal synchronizing signal at the joint can be maintained by recording as follows.

That is. One field is 262.5H, so after one field is recorded, the tape will be 262H (or 261H).
, about 260H), recording starts and the recording is performed overlapping the previous field by 1/2H.

To do this, the rotational phase pulse shown in Figure 4 is set to 0.
．． If the signal is delayed by 5 H and recorded at the time when this signal coincides with the signal shown in FIG.

Next, the positional relationship between the audio and video signals on the tape will be described.

The method of reproducing audio and video signals from the recorded tape shown in FIG. 3 is as described above, but in this case, the timing at which the audio and images are reproduced is determined by the recording pattern on the tape.

As mentioned above, for example, the time when playback of field E shown in FIG. 3 begins is when this field moves from point a to point b on drum 8 in FIG.

If the explanation of this reproduced image is to be reproduced simultaneously with audio, the tape distance l between the audio head 11 shown in FIG. 2 and the point 13 on the drum 8 must be in the relationship shown in FIG. 6. Must be.

That is, as shown in FIG. 6, if EA is the audio information for the image information of field EV, then the distance between EV and EA must be l.

When recording video signals and audio signals in this way, in the recording method described above, that is, the method of recording one field of video signals between point a and point b on the drum, EA At the same time as starting to record the audio of field Ev, the video signal of field Ev can be recorded at point a and point b.

When playing back a tape recorded in this way, the audio and images can be perfectly synchronized, but on the other hand, consider a case where only the audio is recorded on the tape in advance and the images are recorded later. Then, you must first record the audio on the tape, play it back, and then record the corresponding image.

In such a case, unlike the above case, it is necessary to record one field of video signals between point b and point C.

To explain this with reference to Fig. 6, at the moment when the EA audio is played back by the audio head 11, the corresponding field E is at points B and C on the drum, so it must be recorded in these areas. If this happens, the image and audio will not be synchronized.

The above is a recording method that can be considered when recording audio based on a still image, or conversely when recording a still image with an audio signal.On the other hand, when there is a video and audio, for example There is video and audio that can be obtained from a general video tape recorder.

When a video signal is recorded between points a and b on the drum 8 as described above, one field of the first portion of audio information is recorded in the continuous video signal.

This relationship is shown in FIG.

Figure 7 I is the video signal to be recorded, and Figure 7
is the audio signal.

The audio signal is continuously recorded by the fixed head 11, but the video signal is recorded one field at a time interval as described above.

That is, as shown in FIG. 7, one field is recorded at time t, and then at time t2.

When this one fin do is recorded between points a and b on the drum 8, the corresponding audio signal between times t1 and t2 corresponds to this image information.

Actually, since the video signal changes every moment between time t1 and t2, it is sufficient if the image that best matches this audio information is the video information of one field at time t1.

However, this may not always be the case.

Therefore, it is desirable to be able to record an image that best matches the audio signal among the moving image information, so a method for changing the audio recording position and the image information recording position will be described below.

As mentioned above, the recording method between points a and b on the drum 8 in FIG. 2 is based on the vertical synchronization signal of the video signal recorded on the tape and the vertical synchronization signal of the input video signal. By controlling the drum motor 23, a video signal track as shown in FIG. 3 can be formed.

However, when trying to change the recording positional relationship of the audio and video signals on the tape as described above, one method is to change the position of the audio head 11, but it is not necessary to change the position of this head one by one. is very troublesome and is therefore undesirable.

Therefore, by changing the recording position of the video signal on the drum, the positions of the audio and video signals are changed.

That is, as mentioned above, do not record between points a and b on the drum, but record between points d and e (distance is 120 degrees), or record between points c and hb. If you record between the two, you can change the recording position of the audio and video signals.

Now, in this way, one part of the video signal can be placed anywhere on the drum.
When recording a field, the vertical synchronization signal of the recorded video signal as described above cannot be obtained.

That is, if we now try to record between points d and e, the already recorded field is from point d to point C1 and near the guide pole 3a in FIG. 2 away from the drum.

In other words, the part where the vertical sync signal is recorded has left the drum.

Therefore, since there is no reproduction vertical synchronization signal, control using the reproduction vertical synchronization signal cannot be performed.

Therefore, in this case, the signal shown in FIG. 8d, which is obtained by waveform shaping the reproduced output signal of the rotating magnetic head shown in FIG. 8g, is used.

In FIG. 8, the end A of the signal a coincides with the signal d.

Similarly, output signals obtained from two other rotating magnetic heads [
The signals obtained by shaping the waveforms of FIGS. 8(a) and 8(c) become as shown in FIGS. 8(e) and 8(f).

The signal obtained by mixing these signals is as shown in Figure 8g,
This signal is used in place of the vertical synchronization signal.

A specific circuit system in this case is shown in FIG.

In each block in FIG. 9, the same blocks as in FIG. 1 are given the same numbers.

Furthermore, a plan view of the drum portion is shown in FIG.

(This corresponds to FIG. 2.

) First, if one field of video signals is sequentially recorded while running a tape between points e and d of the drum 8 shown in Fig. 10, then the signals as shown in Fig. 8 a, b, and c are obtained. Reproduction signals are obtained from the rotating magnetic heads 5, 6.7.

This signal is shown in Figure 4, and there is not always a complete field recorded on the drum, as in the case of the 7T signal, but as the tape moves, the recorded tape portion gradually decreases. .

Therefore, in a state where the recorded portion of the vertical synchronizing signal has left the drum, the above-mentioned control using the vertical synchronizing signal cannot be performed.

Therefore, as described above, the signal shown in FIG. 8g obtained by waveform shaping the reproduced signal is used.

This signal in Fig. 8g is transmitted to the amplifier 25°26.2 in Fig. 9.
After the reproduced output of each head amplified in step 7 is amplified, the signal is subjected to envelope detection, for example, in waveform shaping circuits 58, 59, and 60, and the detected signal is waveform-shaped.

For example, if the reproduced signal in Figure 8g is envelope-detected,
The signal shown in FIG. 8V is obtained, and if this signal is differentiated and waveform-shaped, the signal shown in FIG. 8D is obtained.

Next, FIG. 8d is obtained from the waveform shaping circuits 58, 59, and 60.

If the signals e and f are mixed in the mixer 61, the signal shown in FIG. 8g is obtained as the output.

The signal shown in FIG. 8g has some parts missing.

This will be explained later, but this is the part where the newly recorded signal [the shaded part in Figure 8g] is connected to the part that has already been recorded during recording. This can be supplemented by the generated signal shown in FIG. 8W.

Now, the signal shown in FIG. 8g, which is the output signal of the mixer 61, is supplied to the signal detection circuit 38 and the switch circuit 39.

The operation of these circuits is the same as that shown in Figure 1,
As previously explained, the explanation will be omitted here, but if there is an output signal from the mixer 61 [Fig. Switch the signal supplied to 39.

When the signal to be switched is not recorded on the tape at first, that is, when there is no output signal from the mixer 61, the output of the switch circuit 39 is the rotational phase pulse sent from the mixer 36.

And as soon as the first field is recorded.

Since the output of the mixer 61 is obtained, the signal of the mixer 61 is obtained from the above point as the output of the switch circuit 39.

When the rotation phase pulse of the mixer 36 is obtained from the switch circuit 39, no signal has been recorded on the tape yet, and as explained earlier, the first field is recorded first. Think about it from the moment you do it.

In this case, the recording method using the reproduced vertical synchronization signal described above (see FIGS. 1 and 5) is almost the same, and in the case of FIG. 1, the rotational phase pulse of the amplifier 33 is directly applied to the phase comparator 49a. In the case of FIG. 9, a signal obtained by passing the rotational phase pulse of the amplifier 33 through the delay circuit 62 is applied to the phase comparator 49a.

In addition. In FIG. 1, the permanent magnet 10 is the rotating magnetic head 5.
In the case of FIG. 9, the rotary magnetic head 7 is mounted on the arm 4.

(Since the mounting position is different, the code for this permanent magnet is 10a.
It becomes.

) Therefore, an output pulse is obtained from the amplifier 33 when the one-rotation magnetic head 7 is just below the magnetic head 9a.

This signal becomes a signal as shown in FIG. 5 υ, and the signal delayed by the delay circuit 62 becomes the signal shown in FIG. 5 d.

(The explanation is using the same signal as in Figure 1, but below
The process up to the process of obtaining the gate signal for one field shown in FIG. U is the same as the recording method explained in FIG.

) After the first field is recorded in the above manner, the signal shown in FIG. 8g is obtained from the mixer 61, and therefore the signal shown in FIG. can get.

This signal is further supplied to mixer 64 and phase comparator 49a.

The phase comparator 49a also receives the signal shown in FIG. 8 m, which is obtained by delaying the rotational phase pulse [FIG. 8 1] obtained from the amplifier 33 by the delay circuit 62, so that the phases of the two signals match. At this point, the signal of FIG. 8n is obtained.

The obtained signal is supplied to the gate signal generator 49b to obtain the signal shown in FIG. 8p.

That is, this gate signal generator 49b is connected to the phase comparator 4.
Based on the signal of FIG. 8 n obtained from 9a delayed by about 1/3V (V is the vertical synchronization signal period) as shown in FIG. 8 0, the signal shown in FIG. It is something that generates.

Hereinafter, the gate circuit 50 and the flip-flop circuit 54 are as explained above, and the gate circuit 50 delays the vertical synchronization signal of the input video signal obtained from the delay circuit 47, and outputs the signal shown in FIG. The flip-flop 54 receives the signal I shown in FIG. 8 r from the signal I shown in FIG.
The signal obtained is as follows.

On the other hand, the signal of FIG. 8g of the switch circuit 39 is transmitted to the mixer 64
In addition, the signal shown in FIG. 8 W, which is obtained by delaying the signal shown in FIG. In this way, the signal shown in Fig. 8 t is obtained by supplementing the missing portion of Fig. 8 g.

Furthermore, this signal is delayed by I in the delay circuit 37 as shown in FIG. 8U, and this signal is applied to the phase comparator 41a.

By the way, as explained in FIG. 1, the phase comparator 41a also receives the signal shown in FIG. 8 which is generated from the input vertical synchronizing signal obtained from the trapezoidal wave generator 40, Phase error signals of the above two signals are obtained.

If this phase error signal is supplied to the drive amplifier 41b for amplification and then supplied to the drum motor 23, the drum motor 23 receives the vertical synchronization signal of the input video signal [FIG. 8j] and the playback signal [FIG. 8J]. The phase is controlled so that the signals of the mixer 61 [FIG. 8g] generated from the signals g, b, and c) have a constant phase relationship.

This relationship is a modification of the control method using the reproduced vertical synchronization signal and the input vertical period signal described above, and uses the signal of the mixer 61 generated from the reproduced signal instead of the reproduced vertical synchronization signal. This method allows you to change the recording position of the signal.

Now, the signal waveform shown in Fig. 8 is the point d on the drum 8.
This is a signal waveform when one field is recorded between and point e, and this recording position can be arbitrarily changed by changing the delay time of the delay circuit 62 in FIG.

That is, the signal shown in FIG. 8 m is obtained by delaying the rotational phase signal of the rotating magnetic head shown in FIG. By changing the position of occurrence of [Fig. 8n],
This allows the recording position on the drum to be changed.

With this, it is possible to arbitrarily change the field of the video signal of the moving image explained in FIG.

As mentioned above, when recording between points a and b of the drum in Figure 2, the field of pulse positions shown in figure 7 m is recorded, and when recording between points C and b. In this case, the pulse position field shown in FIG. 7 is recorded.

Furthermore, the case between the above points d and e is approximately as shown in FIG. 7V.

Furthermore, the area between point f and point g is as shown in Fig. 7 (■).

In the manner described above, the relative relationship between the recording position of the video signal and the recording position of the audio signal on the drum can be changed.

As is clear from the above description, the present invention provides a means for generating a signal indicating the rotational phase of the rotating magnetic head in accordance with the rotational position of the rotating magnetic head (for detection in the above-mentioned embodiments) when recording a video signal for the first time. By comparing the phase of the signal of the magnetic heads 9a to 9c, the permanent magnet 10, the amplifiers 33 to 35, and the mixer 36) with the vertical synchronization signal included in the input video signal, When recording the second and subsequent video signals, the vertical synchronization signal included in the signal obtained by reproducing the previously recorded video signal with a rotating magnetic head, and the vertical synchronization signal included in the input video signal By comparing the phase of the magnetic head, the rotation of the motor for driving the rotary magnetic head is controlled, and the recording length of the video signal is determined in units of one field while the magnetic tape is running at a constant speed. It is possible to keep the data constant and record the data in a continuous manner.

Furthermore, in the present invention, since the magnetic tape is run at a constant speed when recording video signals as described above, audio information related to the content of the video signal to be recorded (for example, You can also record narration, etc., which is an excellent effect.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram including a perspective view of a drum unit according to an embodiment of the present invention, FIG. 2 is a plan view of essential parts of the drum unit in FIG. Figures 4 and 5 are diagrams showing an example of a signal pattern. Figures 4 and 5 are signal waveform diagrams of various parts in Figure 1. Figure 6 is a diagram of a signal pattern on a tape for explaining the same embodiment. FIG. 8 is a signal waveform diagram for explaining the present invention; FIG. 9 is a circuit block diagram including a perspective view of a drum section showing another embodiment of the present invention. , 10th
This figure is a plan view of the main part of the drum section in FIG. 9. 1... Tape, 2... Rotating magnetic head/drum device, 5, 6, 7... Rotating magnetic head, 8... Drum, 9a to 9c. ...Magnetic head, 10...Permanent magnet, 11...
Magnetic head, 12...Capstan, 13...
... Pinch roller, 16-18 ... Rotating transformer, 19 ... Capstan motor, 22.
...Recording amplifier, 23...Drum motor, 24-27.50,52...Gate circuit, 2
B, 36°61.64...Mixer, 29°...
... Demodulator, 30°46 ... Vertical synchronization signal separation circuit, 32 ... Ring counter, 33-3
5...Amplifier, 38...Signal detection circuit, 40...Trapezoidal wave generator, 41a, 49a...
... Phase comparator, 41b ... Drive amplifier,
43...Audio signal input terminal, 44...
・Video signal input terminal, 49b... Gate signal generator, 51... Frequency modulator, 53...
... Buffer amplifier, 54 ... Flip-flop, 58, 59, 60 ... Waveform shaping circuit.

Claims (1)

[Claims] 1. A rotating magnetic head having three rotating magnetic heads arranged at equal angular intervals, and a magnetic tape wound around the outer periphery in eight shapes with a length sufficient to record video signals for at least two fields. a head drum device, a magnetic tape constant speed drive means including a capstan and a pinch roller that drive the magnetic tape to travel in a predetermined direction at a predetermined speed; video signal recording means for supplying the input video signal to one of the three rotary magnetic heads for sequential recording in the horizontal direction; and running of the magnetic tape by the magnetic tape constant speed driving means. Accordingly, the three rotating magnetic heads scan tracks of video signals recorded on the magnetic tape in units of one field to obtain playback signals of each video signal from each of the rotating magnetic heads, and reproduce the video signals. a first signal processing means for obtaining a first signal which is a vertical synchronization signal from the input video signal; and a second signal processing means for extracting a vertical synchronization signal contained therein from the input video signal and outputting it as a second signal. ,
a third signal processing means for generating a third signal indicative of the rotational phase of the rotating magnetic head in accordance with the rotational position of the rotating magnetic head; and selecting the first signal when the first signal is obtained;
At other times, the fourth signal indicates the rotational phase of the rotary magnetic head by selecting the third signal.
a fourth signal processing means for obtaining a signal; a motor control means for controlling the rotation of a rotary magnetic head rotation drive motor by comparing the phases of the second signal and the fourth signal; and the magnetic tape. The audio signal recording means includes a magnetic head for recording an audio signal on a track different from the track on which the video signal is recorded, and the audio signal is recorded on the magnetic tape following the previously recorded video signal. What is claimed is: 1. A magnetic tape device characterized in that the video signals to be recorded are recorded so as to be continuous with each other at a constant recording length, and the audio signals related to the video signals to be recorded can also be recorded.