JPS6339193B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a video recording and reproducing device that can provide special video effects. The video recording and reproducing device is a rotating head type magnetic recording and reproducing device (hereinafter referred to as VTR).
However, home VTRs have become extremely popular in recent years, and are increasingly being used not only to record TV broadcasts, but also to create home movies using small VTRs and small color cameras.

There was a growing demand for a VTR that could easily make effective scene changes by overlapping the previous and subsequent scenes at the scene change, or by fading out the previous scene and fading in the subsequent scene. strong. Nevertheless, in order to perform this type of technique conventionally, two steps are required as shown in Figure 1.
By mixing the reproduced video signals from two VTRs (VTR1, VTR2) or one camera and one VTR (VTR1) using the mixer 100 and changing the mixing ratio, the overlap part at the time of scene change can be suppressed. The method used was to create a VTR and dub it to another VTR (VTR3).

In this case, in order to synchronize and drive two VTRs or a camera and a VTR, external synchronization is possible.
A VTR or camera is required. Not only that, but
For general users, the above method requires two or more VTRs, and therefore the equipment is large and expensive, making it impossible for general users to achieve such special effects. Ta.

The present application has been made in view of this background, and its purpose is to provide a video recording and reproducing device that can easily obtain the above-mentioned special effects with a single device with an extremely simple configuration. This is what I did.

In order to achieve such an objective in the present invention,
An auxiliary head is provided for tracing the locus on the recording medium traced by the rotating main head, and a mixing means for mixing the video signal reproduced by the auxiliary head with the video signal from the video input means; and switching means for selectively supplying the video signal from the video input means and the video signal from the video input means to the main head.

This will gradually darken the screen,
You can easily adjust the brightness or gradually switch to another screen.

The present invention will be explained below based on examples.

FIGS. 2, 3, and 4 show the positional relationship between the rotating main head and the auxiliary head of the present invention in the case of a two-head helical scan type VTR.

In a conventional two-head helical scan type VTR, as shown in Figure 3, a magnetic tape T is wound diagonally at an angle of just over 180 degrees around a cylindrical tape guide drum (hereinafter referred to as drum) 1 to run the magnetic tape. , an odd field and an even field are sequentially formed diagonally on a magnetic tape as one track by rotary magnetic heads A and B provided 180 degrees opposite each other in the drum. The situation is shown in Figure 2.
In FIG. 2, the odd field tracks recorded by the A head are shown as OT, and the even field tracks recorded by the B head are shown as ET.

In the second illustrated embodiment, a pair of heads A and B located 180 degrees apart in the drum in a conventional two-head helical scan type VTR are used as the main rotating heads, and two heads A' and B are used as rotating main heads. ' is used as an auxiliary head, but the present invention is not limited to a helical scan type, and may be one that scans in the width direction of the tape. Furthermore, the number of heads is not limited to two.

In the embodiment shown in the second figure, the auxiliary head A',
B' is positioned to trace each recorded track exactly 2n fields (n is an integer) behind the main heads A and B, respectively. Figure 2 shows the case where n=1, where the main heads A and B are located at the end and beginning of writing of tracks OT1 and ET1, respectively, and the auxiliary heads A' and B' are located at the end and beginning of tracks OT1 and ET1, respectively.
The position to be traced with a delay of 2 fields relative to B,
That is, the main heads A and B are arranged so as to be located at the writing end and writing start positions of the tracks OTO and ETO that have already been recorded.

Therefore, if the main heads A and B are in the m-th horizontal scanning period of a certain field, they are located in the m-th horizontal scanning period 2n fields before the auxiliary heads A' and B'.

The present invention reproduces a signal that has already been recorded on a magnetic tape (hereinafter referred to as a pre-recorded signal) using the auxiliary head, and combines the reproduced signal by the auxiliary head with a signal that is to be newly recorded (hereinafter referred to as a post-recorded signal). By mixing the signals (referred to as
The post-recording signal is faded in.

In the second illustrated embodiment, the auxiliary head is placed at a position where it traces 2n fields behind the main head, but by doing so, it is possible to mix signals without using a special delay circuit. It is effective.

In other words, the auxiliary head may be configured to trace a track with a delay of several tracks relative to the main head, and in that case, the output of the auxiliary head and the post-recorded signal may be mixed after passing through an appropriate delay means. good.

FIG. 5 is a main block diagram showing an embodiment of the VTR control circuit of the present invention. 2 is a video signal input terminal, 3 is a synchronization separation circuit, blocks 4 to 9 are drum servo systems, 13 to 17 are capstan servo systems, 18 to 20 are recording systems, 36A, 36B, 37
~39 is the main head regeneration system, 29A, 29B, 30
-32 are auxiliary head regeneration systems, 21-28 are overlap control systems, SW1-SW4, SW7, SW8
is a switch that is linked to switching between recording and playback modes, with each P contact indicating the playback mode and the R contact indicating the recording mode.

SW5, SW6, SW9, and SW10 are switches that are linked to switching between the special mode and the normal mode according to the present invention. Contacts a of these switches SW5 and SW9 are for the normal mode, and contacts b for the special mode.

Next, the operation will be explained based on FIGS. 5 and 6.

When the recording video signal is applied to the input terminal 2, it is synchronously separated by the synchronous separator 3, frequency-divided into 1/2, and applied to the phase comparator 4 via the switch SW3. On the other hand, the rotational phase of the rotary head is detected by the detector 5, and the flip-flop circuit 7 is triggered via the block 6 composed of two monomultis to generate a 30Hz rectangular wave synchronized with the rotational phase of the rotary head. The generated rectangular wave is shaped into a trapezoidal wave by a trapezoid 8, and the phase of the trapezoidal wave and a signal which has been synchronously separated from the video signal and divided into 1/2 is compared by a phase comparator 4, and the phase error is determined according to the phase error. Get the error voltage. By applying the error voltage to the drum motor drive amplifier 9, the rotational phase of the rotary head is synchronized with the vertical synchronization signal of the recorded video signal. Also, during this recording, the synchronization is separated from the video signal by 1/2.
CTL every frame using a signal divided into
A (control) signal is recorded on one side of the tape by the CTL head CLH via the R terminal of the switch SW1.

On the other hand, in the capstan control system, during recording, a signal (30 Hz) synchronously separated from the video signal is applied to the phase comparator 13 via the switch SW4.
Further, the frequency detected by the head 15 which detects the frequency corresponding to the rotational speed of the capstan 14 is as follows.
The frequency is divided to 30Hz by the frequency divider 16 and the switch SW2
The signal is input to the phase comparator 13 via the phase comparator 13. Furthermore, the phase is compared with a 30Hz signal obtained by synchronously separating the video signal, and the error voltage is applied to the capstan motor drive amplifier 17 to cause the capstan motor CM to run the magnetic tape T at a constant speed. Driven.

On the other hand, in the normal recording mode, the video signal input from the input terminal 2 is gain-controlled to a constant level by the AGC circuit 18 via the switch SW5, then FM modulated by the FM modulator 19, and then sent to the recording amplifier 20. Width increased and switch SW7,8
is added to main heads A and B and recorded on tape.

Next, following the recording operation described above, the structure and operation for performing a scene change using a special mode such as overlap according to the present invention will be explained.

SW10 is an overlap switch that is closed when recording a scene before overlapping recording, and SW11 is a switch that is closed when the trigger switch is turned on when shooting with a camera, and when a pause switch, etc. is released when shooting with a VTR. This is a switch that closes. 21,
22 is a pulse generator that generates pulses in response to opening and closing of the switch SW11, respectively;
23 and 24 are AND gates, 25 is a first one shot circuit, 26 is a capstan motor reverse drive control circuit for running the tape in reverse only while a high level signal is output from the one shot circuit 25, and 27 is a reverse drive control circuit for the capstan motor. Second one-shot circuit, 2
8 is a third one-shot circuit.

With this structure, when the trigger switch is turned off (or the pause switch is turned on) with the overlap switch SW10 closed in advance, the switch SW11 is turned off, thereby setting the pulse generator 21 to a high level. Output a signal. Therefore, the output of the AND gate 23 also becomes high level, so that the first one shot circuit 25 outputs a high level signal for a predetermined period of time. During this predetermined period of time, the tape is rewound by the motor reverse rotation drive control circuit.

Further, while the output of the one-shot circuit 25 is at H level, switches SW1 to SW4, SW7, SW8, etc. are configured to switch from recording mode R to playback mode P, or to continue energizing heads A and B. It is configured. This prevents the previously recorded signal from being erased while the tape is running in reverse.

Further, in conjunction with the rise of the output of the one-shot circuit 25, a pinch roller (not shown) is released.
The VCR is placed in pause mode.

Furthermore, the output time of the high level signal of the one-shot circuit 25 is determined by the resistance 126 in addition to the rise time of the reproduction MOBO system when the tape runs in reverse as described later, so that the previously recorded signal is returned to the position where it is reproduced by several fields. The settings are automatically or manually set in advance.

In addition, in the special mode according to the present invention, it is not necessary to once rewind the tape as in this embodiment.

That is, since the auxiliary head traces with a delay of several tracks relative to the main head, it is possible to change the screen according to the present invention by simply stopping the tape running and recording by turning off the camera trigger or pausing the VTR. be.

Now, with the preparation for image conversion completed in this way, if you apply the post-recording signal that should follow the above-mentioned pre-recording signal to input terminal 2 and trigger the camera (or turn off the pause switch of the VTR), The switch SW11 is turned on, and the pulse generator 22 outputs a high level signal. Therefore, a high level signal is output from the AND gate 24, and the second one shot circuit 27 outputs a high level signal for a predetermined period of time.

The control system other than the switches SW3 and SW4 is configured to be in the reproduction mode while the one shot circuit 27 is outputting a high level signal. Therefore, the rotating head rotates in phase synchronization with the signal synchronously separated from the post-recording signal, and the capstan servo system rotates in phase synchronization with the signal synchronously separated from the post-recording signal.
Hz and the reproduced CTL signal reproduced by the CTL head are compared in phase by a phase comparator 13, and the output error voltage is used to drive a capstan motor via a capstan drive amplifier 17. Further, after the high level signal of the one-shot circuit 27 is output, the pinch roller pinches and presses the tape against the capstan.

In this manner, the time constant of the one-shot circuit 27 is set so that the main heads A and B trace the pre-rise recording signal track of the capstan and drum servo system again within the output period of the one-shot circuit 27.

Further, when the one shot circuit 27 falls, an output is generated at the output terminal of the third one shot circuit 28 for a certain period of time. In response to the rise of this output, the remaining switches SW1, SW2, SW7, and SW8 are switched to the recording mode, and the switch SW5 is switched to the b side only during the output period of the third one-shot circuit 28, and the switch SW6 is closed. will be accomplished.

Therefore, at this time, the main heads A and B are switched to the recording side, while the auxiliary heads A' and B' are respectively reproducing the signal 2n fields before the main heads A and B as described above. The reproduction signal from the auxiliary head A'B' is reproduced by the preamplifiers 29A and 29B, and the output signal of the flip-flop 7 is used to alternately switch and reproduce A' and B'. Furthermore, after passing through the switching circuit 30, the odd and even fields are converted into a continuous signal, demodulated by the demodulator 31, amplified by the output amplifier 32, and sent to the overlap switch.
The signal is input to the mixer 33 via the switch SW9 which is switched to the b side in conjunction with the closing of the SW10. The mixer 33 mixes the pre-recorded signal reproduced by the above-mentioned auxiliary heads A', B' and the post-recorded signal inputted via the input terminal and SW5, and records the mixed signal on the tape by the main head AB. .

Now, if n=1 and the mixing ratio of the mixer 33 is 1:1, the output of the output amplifier 32 and the post-recording signal are mixed at a ratio of 1:1 at the time of output of the timing switch circuit 28, and the main head, A, B recorded on magnetic tape. Furthermore, when the main heads A and B record the next frame, the output from the auxiliary head A'B' is such that the ratio of the pre-recorded signal and the post-recorded signal recorded by the main heads A and B one frame before is 1:1.
1, the ratio of the previous signal in the output signal of the mixer 33 is 1/4. In this way, after m frames, the above ratio becomes 1/2 ^m , and the previous signal gradually attenuates.

Further, if the mixing ratio of the mixer 33 is set to P:1 between the front signal and the rear signal, the ratio of the previous recording signal in the recording signal after m frames becomes P/2 ^m (P+1).

Therefore, it is possible to control the fade-in and fade-out times of the overlap portion simply by adjusting the mixing ratio of the mixer.
That is, the larger the value of P mentioned above, the more gradual the fade-in and fade-out will be, and the longer the overlap period will be. Further, the value of this P is adjusted by the volume 34. Further, when the output of the timing switch circuit 28 falls, SW6 is opened and SW5 is set to the a side.

The falling point of the timing switch circuit 28 is preferably immediately after the previous recording signal has attenuated to some extent, and is configured to be linked to the volume 34 so that an optimum time constant can be set according to the overlap period. In Fig. 5, 36A and B are the main heads A and B.
In each preamplifier, 37 is a reproduction switching circuit, 38 is a demodulator, 39 is an output amplifier, and 40 is an output terminal during normal reproduction.

Furthermore, as is clear from the above description, it is also possible to monitor the signal actually recorded on the tape by the output from the a terminal of SW9 during normal recording.

In the above embodiment, there was one system each for the main head and the auxiliary head of the reproduction system circuit, but this can be used for both the preamplifiers 36A and 36.
B, playback switch 27, circuit 37, demodulator 38,
Each block of the output amplifier 39 has 29A and 29A, respectively.
B, 30, 31, and 32 can be substituted. In that case, the inputs to the above-mentioned 29A and 29B may be switched from the auxiliary heads A' and B' to the main heads A and B during reproduction.

Further, in the above embodiment, a normal video signal is assumed as the post-recording signal, but if the image is a constant brightness image such as a white level video signal or a black level video signal, the fade-out effect can be effectively produced. . Furthermore, if the prerecorded signal is an image such as a white level video signal, a fade-in effect can be easily obtained. In these cases, the above-mentioned effects can be obtained with a single VTR by simply providing a signal generator for generating such a reference signal in the VTR or camera. Alternatively, only the luminance component of the video signal input from the video signal input terminal may be cut or amplified before being input to the mixer.

A similar effect can also be obtained by closing or fully opening the aperture on the camera side. Further, at this time, if the control of the aperture and the operation of the one-shot circuits 27, 28, etc. are linked, the operation becomes easier.

As described above, according to the present invention, special effects such as overlap recording can be easily achieved with a single device, and recording signals can also be monitored by the auxiliary head during normal recording.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the prior art, FIG. 2 is a diagram showing an embodiment of the head tracing relationship in the magnetic recording/reproducing apparatus of the present invention, and FIGS. 3 and 4 are diagrams showing the main head and auxiliary head. FIG. 3 is a diagram seen from above, FIG. 4 is a diagram seen from an oblique direction, FIG. 5 is a diagram showing an example of the control circuit, and FIG.
The figure is a diagram showing timing relationships. A, B... Rotating main head, A', B'... Auxiliary head, 4, 5, 6, 7, 8, 9... Drum servo system, 13, 14, 15, 16, 17... Capstan Servo system, 33... Mixer, 18, 19,
20...recording system, 36A, 36B, 37, 38,
39...Main head regeneration system, 29A, 29B, 3
0, 31, 32...Auxiliary head regeneration system, SW10
...Special effect switch, SW11...Switch that is linked to the trigger or pose switch.

Claims (1)

[Scope of Claims] 1. A rotating main head that can record signals on a recording medium that is transported in a predetermined direction, an auxiliary head that tracks the trajectory on the recording medium traced by the rotating main head, and an input video signal. a video input means for mixing the video signal reproduced by the auxiliary head and the video signal from the input means; a video signal mixed by the mixing means and the video signal from the input means; and switching means for selectively supplying video to the main head. 2. The video recording and reproducing apparatus according to claim 1, wherein the auxiliary head is provided at a position that traces a trajectory on the recording medium with a delay of an even field period with respect to the main rotary head. Device.