JPS5818828B2 - Video signal reproduction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reproduction method for reproducing video information signals for one individual field or one frame recorded and filed on a magnetic tape as a still image.

The video tape recorder (hereinafter referred to as rVTRJ) is
Generally, it has been used to record and reproduce continuous video signals as continuous video information.

Further, as a special method, there is a so-called skip recording and reproducing method in which video signals for one field or one frame are periodically recorded and reproduced at fixed time intervals from among continuous video signals.

During reproduction, these VTRs can display still images on a monitor television by still operation.

The reason why VTR technology has developed to this day is not only because of the progress in television broadcasting technology, but also due to the development of VTR technology.
This is probably because a lot of it depends on the usage characteristics of the TR itself.

In other words, as a result of using magnetic tape in VTR technology, recorded video information can be directly played back and viewed.
Not only can it be saved, but when it is no longer necessary, the recorded information can be erased, other information can be recorded again, and the information can be reproduced.

However, on the other hand, conventional VTR technology did not have the features that optical photography technology has.

In optical photography, by selecting objects one by one and pressing the shutter button on the camera as needed, it is possible to record independent still images, one by one, on film side by side.

Therefore, if VTR technology could be equipped with features similar to those of the above-mentioned optical photography technology, the uses of VTRs would be further expanded.

In response to such requests, a video signal recording method has been developed in which one field or one frame worth of video information is arbitrarily extracted from continuous video information, sequentially recorded on magnetic tape, and filed. For example, it is proposed by the original patent application of the main body.

The present invention aims to provide a reproduction method for reproducing video information for each field or frame recorded and filed in this manner as a still image.

Hereinafter, one embodiment of the present invention will be described in detail based on the drawings.

First, FIG. 1 shows an example of a recording pattern on a magnetic tape in which video information for one field or one frame is arbitrarily extracted from continuous video information, sequentially recorded, and filed.

In this figure, 21 is a magnetic tape, and 22 is a recording track showing a portion where a video signal for one field or one frame is magnetically recorded by a rotating video head.

However, in practice, when recording using multiple video heads, in order to prevent the part where the video head switches during playback from appearing on the screen as horizontal line noise, it is necessary to Extra video signals are recorded at the beginning and end positions of the recording track 22.

Then, during playback, the extra video signal portion is brought to an overscan portion at the top or bottom of the screen, and the video head output is switched there so that the nozzle is not visible.

This is well known in this field, but basically 1
Since the video signal for one field or one frame is recorded, in the description of the present invention, what is recorded on one recording track is "one field" or "one field".
It will be expressed as "1 frame".

A non-magnetized portion, ie, a guard band 23, is formed between the recording tracks 22, 22'.

The width of this guard band is larger than the width of the recording track.

This can be done, for example, by moving and scanning the video head in the direction of arrow D1 while the magnetic tape 21 is stopped.
When a recording track is formed and recording is repeated sequentially,
After recording is completed, the magnetic tape 21 is moved a certain distance t in the direction of arrow D2 and stopped, and a new recording scan is performed at this stopped position, thereby forming a plurality of recording tracks in sequence.

The present invention reproduces individual video information recorded on such a magnetic tape, and the basic idea of the system is as follows.

For example, after the reproduction of the recording track 22 is completed, the magnetic tape is transported a certain distance, and when the video head for reproduction leaves this recording track 22 and comes to the correct position on the next recording track 22', the magnetic tape 21 is stopped running. Stop and perform normal playback operations.

A method for moving the magnetic tape 21 by a certain amount and stopping it at the correct position is to keep the video head in a reproducing operation state when it leaves a recording track 22 and reaches a position that coincides with the next recording track 22'. A means is employed for controlling the traveling operation by reading the vertical synchronizing signal 24' recorded on the image recording track or a pulse signal dependent thereon.

The magnetic tape 21 shall be transported at a predetermined transport amount,
It is assumed that this speed is extremely slower than the rotational speed of the video head.

Then, the video head starts scanning from a position matching the width of the recording track 22 and scans this track overlappingly several times until only the guard band 23 is scanned.

Similarly, the video head repeatedly scans the adjacent recording track 22' several times until it reaches a position that matches the width of the recording track.

The vertical synchronizing signal contained in the repetitive video signal reproduced by these overlapping scans is illustrated as shown in FIG. 2, for example.

The pulse of the first period t1 is applied to the recording track 22 in FIG.
The pulse of period t3 is the repetition of the synchronization signal 24' of the next recording track 22'.

The period t2 is a period during which the video head is scanning the guard band 23.

Therefore, if the running of the magnetic tape 21 is stopped when the number of pulses in the period t3 has been counted, it is possible to obtain a large head reproduction output whose width matches that of the recording track 22' and the video head.

The vertical synchronizing signal at that time is shown in Fig. '2 t4.

When implementing such a system, for example, the video head is kept rotating at all times, and the magnetic tape is controlled to be transferred and stopped using a predetermined control means that will be described later.
For this purpose, it is desirable to separate the motor that rotates the video head and the motor that runs the magnetic tape.

The control means used to carry out the present invention includes, for example, a function that first sets the VTR side to a playable state, and then transports the magnetic tape and stops the magnetic tape accurately when it has been transported a predetermined amount to bring it into playback mode. This control device is attached to the VTR and has a function to maintain the current level (hereinafter described as rSHIFT-PJ Bokun).

Then, the operation of the control means, for example, first of all, the VT
The R side is set to the regeneration preparation state, and initial setting of the control device is performed.

Thereby, when the video head scans the recording track, a reproduction signal can be taken out at any time.

At this time, the magnetic tape is stopped.

Next, the rsHIFT-Pj button is pressed.

Then, when the magnetic tape is transferred and the video head starts scanning over the recording track, a predetermined number n of vertical synchronizing signal pulses included in the reproduced repetitive video signal is counted.

When the counting of the number of pulses n is completed, the magnetic tape is stopped.

At this time, the video head scans the optimum position on the recording track, and the VTR repeatedly sends out a video signal forming a still image.

Next, when the user presses the "15HIFT-P" button again, the magnetic tape runs until the video head can scan the adjacent recording track, and the same operation is repeated.

FIG. 3 shows an electric circuit configuration of a regeneration control device for implementing the present invention.

In the figure, a VTR (not shown) is connected through terminals 'r41T and +'r6, and signals are transmitted and received.

A vertical synchronization signal included in the reproduced video signal is supplied from the terminal T4 via a synchronization separation circuit, and a motor drive pulse for running the magnetic tape on the VTR side is supplied from the terminal T6. is supplied to the VTR motor drive circuit from terminal T5 when gate G4 is opened.

Reference numeral A5 is a signal generator whose output temporarily changes from rLJ to rHJ by pressing the rSHI FT-Pj button.

The output terminal of the signal generator A is connected to the input terminal of the inverter 4, and the output terminal of the inverter 4 is connected to invert the input and apply it to the set input terminal S9 of the latch circuit F9.

This latch circuit F, when the set input becomes rLJ even once, keeps its output at "H" until the next reset human power rLJ is supplied, and even once the reset input becomes r
When LJ is reached, the output is kept at rHJ until the next set human power rLJ is supplied.

The output terminals of latch circuit F are gate circuits G3 and G4.
is connected to the input terminals ga1r and g4t of.

A reproduced vertical synchronizing signal is applied to the input terminal g32 of the gate circuit G3 from the VTR side via the terminal T4.

The output terminal of gate circuit G3 is connected so that when this circuit gates a vertical synchronization signal, it can be applied to the input terminal of counter 3.

When the counter 3 counts the number n of pulses of the vertical synchronizing signal, it sends one temporary pulse whose output changes from rHJ to rLJ.

The output thereof is applied to the latch circuit F and the glue set input terminal r9.

Terminal T4 is also connected to the base of a buffer transistor Q5, whose emitter is connected to a resistor R.
Grounded by 4.

Further, the emitter of the transistor Q5 is connected to a circuit for smoothing the vertical synchronizing signal, which includes a resistor R3 and a capacitor C2.

The output of the smoothing circuit is inverted by the inverter ■, and connected to the resistor R7.
2 is applied to the reset input terminal of 3 through the counter.

A charging time constant circuit consisting of a resistor R5 and a capacitor C2 is also connected to the output terminal of the latch circuit F9, and applies the voltage generated across the capacitor C2 between the base and emitter of the switching transistor Q6.

The collector of transistor Q6 is connected to the reset input terminal of counter 3 via diode D3.

Gate circuit G4 connects terminal T to input terminal g+2 from the VTR side.
6, a motor drive pulse is applied, and when this circuit is opened, the pulse is derived from the output terminal T.

Next, the operation of the regeneration control system circuit will be explained according to its operation order.

First, the VTR side is set to a playback preparation state, and the power to the control device is turned on.

As a result, the output of the signal generator A5 is rLJ, the latch circuit F, and the counter 3 are reset, and initial setting is performed.

At this time, it is assumed that the video head is idly scanning a portion of the magnetic tape with no recording track at the beginning.

When the rsHIFT-Pj button is closed, the signal generator A5
The output of inverter 4 temporarily becomes rHJ, and the output of inverter 4 becomes rLJ.

As a result, latch circuit F enters the set state, and its output rHJ causes gate circuit G3. G4 will be held.

Therefore, the motor drive pulse applied from terminal T6 is derived from terminal T through gate circuit G4,
The capstan motor rotates.

Even when the magnetic tape runs, no vertical synchronizing signal appears at the input terminal T4 unless a recording track appears.

At this time, even if the gate circuit G2 is open, there is no input of 3 to the counter, so its output is rHJ.

Furthermore, the output of inverter 5 also becomes rHJ, resetting the counter to 3.

As the magnetic tape progresses, the first recording track appears.

When the video head begins to scan over the recording track even slightly, a vertical synchronization signal is applied to terminal T4.

Then, since the input of inverter 5 becomes rHJ, the output becomes rLJ and the function of 3 is restored to the counter.

As a result, 3 is input to the counter υ through gate circuit G3.
The number of synchronization signals received is counted and the predetermined number of pulses is n.
When two pieces are counted, an "L" pulse is sent out.

As a result, the latch circuit F9 enters the reset state, and its output rLJ becomes the gate circuit G3. Close G4.

The motor drive pulse sent from terminal T5 to the magnetic tape is cut off, the capstan motor is stopped, and the magnetic tape stops running.

That is, in this state, the video head repeatedly scans the optimum location on the recording track, and the VTR repeatedly sends out video signals for one field to provide a still image to the television monitor.

Further, since the gate circuit G3 is closed, the synchronizing signal is no longer applied to the counter 3, and the counter 3 is reset.

Next, in order to reproduce the information on the adjacent recording track, r
The SHIFT-PJ button is pressed.

Then, the magnetic tape runs as before.

As explained in Fig. 2, the video head gradually scans only the gart band while decreasing the scanning width on the first recording track that it has been scanning up until now, and when that is finished, it starts scanning on the adjacent recording track. Follow the sequence of starting.

In this case, the vertical synchronization signal extracted from the reproduced signal appears at the open terminal T4 until the video head leaves the first recording track.

Here, if this is counted by 3 in the counter and the number of counted pulses reaches n, the magnetic tape will stop at that point.

This means that the video head does not scan over the adjacent recording track, but scans the area in front of it, and a predetermined reproduction operation is not performed.

In order to eliminate this inconvenience, a charging time constant circuit consisting of a resistor R6 and a capacitor C2 and a switching transistor Q6 are provided.

When the latch circuit F9 is set to run the magnetic tape, its output rHJ causes the capacitor C to
2 is charged.

Initially, the voltage across capacitor C2 is low and transistor Q6
cannot be made conductive.

When transistor Q6 is off, its collector potential becomes rHJ, which is used as a counter to input 2 to the reset terminal of 3.
3 through diode D3, forcing this circuit into a reset state.

As a result, even if the video head reproduces and scans the first recording track as the magnetic tape runs, the reproduced vertical synchronization signal is not counted.

Eventually, when the voltage of the capacitor C2 increases, the transistor Q6 becomes conductive, and its collector potential becomes [L].

When the collector potential falls, 3 restores the counting function to the circuit,
Start counting the number of vertical synchronization signal pulses.

Therefore, in the process of leaving the first recording track, by appropriately selecting the charging time constant of resistor R3 and capacitor C2, the start of counting of the synchronization signal to be reproduced can be delayed, and even after counting, the remaining The number of counted pulses is sufficiently smaller than the predetermined number n.

As a result, the output "H" of 3 on the counter does not change.

If the scanning of the video head falls into the guard band between the first track and the next track in this state, no synchronizing signal will appear at the terminal T4.

Then, since the input voltage of the inverter I5 becomes rLJ, its output becomes "H" and resets the counter to 3.

The video head then scans to the next recording track.

Then, a vertical synchronizing signal appears at terminal T4, and the output of Impark 5 returns to rLJ.

As a result, the synchronization signal is counted by 3 in the counter, and when the count value reaches n, the gate circuit G
3. G4 is closed.

Therefore, the magnetic tape stops running and the information on the adjacent recording track is reproduced.

As explained above, since the present invention performs reproduction while the magnetic tape is stopped, a reproduced image with extremely low jitter can be obtained, and there is no need to consider time axis correction, which facilitates colorization.

During playback, the video head scans while substantially matching the width of the recording track, so the S/N of the playback image is
The ratio is extremely good.

In addition, magnetic tape on which individual video information is recorded is
By making the width of the guard band substantially larger than the width of the individual recording tracks, cueing of the first recording track of the magnetic tape can be facilitated.

When scanning adjacent recording tracks at the same time, a circuit that counts and controls vertical synchronization signals can be easily constructed.

Moreover, in the hydraulic type, when controlling the running and stopping of the magnetic tape, the reproduction vertical synchronization signal or pulses dependent on this signal are counted, so if only the purpose of the present invention is considered, a separate head may be provided. There is no need to use a separate track for control.

It should be noted that the video information to be reproduced described in the above embodiments may be video information that is individually recorded, even if it is continuous video signals recorded individually, or completely separate video information. They may have independent contents; in short, any type of video information in which one field or one frame of video information is individually recorded on a magnetic tape can be applied to the method of the present invention. .

This means that regarding the relationship between each recording track, it is only necessary that the width of the guard band between them be greater than the width of each recording track.

Furthermore, the pulse signal counted by the counter in the above embodiment is not limited to the reproduced vertical synchronization signal or a signal dependent thereon, and it goes without saying that any signal having a natural frequency similar to these signals can be used in the same way. be.

[Brief explanation of the drawing]

FIG. 1 shows an example of a recording pattern of a magnetic tape on which video information to be reproduced according to the present invention is recorded, FIG. 2 shows pulses of a vertical synchronization signal included in a reproduced video signal, and FIG. An example of a regeneration control device used to implement the method of the present invention will be shown. 21... Magnetic tape, 22, 22'...
・Recording track, 23...Gart band, A5
... Signal generator, F9 ... Latch circuit, G3. G4...Gate circuit, K3...
...Counter, ■4. ■5... Inverter, G
5, G6...transistor.

Claims (1)

[Claims] 1 Individual records recorded and filed by using a magnetic recording and reproducing device that scans the magnetic tape with a rotating video head, and alternately forming recording tracks and guard bands larger than the width of the recording tracks on the magnetic tape. A reproduction method for reproducing one field or one frame worth of video information from a track as a still image, when the scanning of the video head approaches the recording track to be reproduced according to the running of the magnetic tape. Counting a predetermined number of pulses of a pulse signal dependent on a reproduced vertical synchronizing signal separated from the repeatedly generated reproduced video signal, and stopping the magnetic tape when the number of pulses has been counted. A video signal reproducing method characterized in that a still image is extracted by repeatedly scanning the optimal position of a recording track to be reproduced using the video head.