JPS5854792A - Recording method of synthesized video signal on magnetic tape or the like - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a composite video signal recording method, and more specifically, a composite video signal recording method on a magnetic tape etc. that can obtain a magnetic tape on which a copy-protected composite video signal is recorded.
Regarding this.

Conventionally, in order to prevent copying, there has been a method of recording on magnetic tape by reducing the width of the vertical synchronizing signal in the composite video signal, for example, to about 1/2.

When this magnetic tape is copied using a video tape recorder, etc., if the vertical Jυ (#lMk of the signal is reduced by about 1/3), there is almost no copy prevention effect.
When a copied magnetic tape is played back, it is played back without any problem.

In addition, even if a video tape recorder is used to play a copied magnetic tape and the images are not combined properly, if the video tape recorder is improved and the video tape is dubbed and the magnetic tape is played back, It was easy to obtain normal images and there was no copy protection effect.

The present invention has been made in view of the above, and it is an object of the present invention to provide a method for recording composite video signals on a magnetic tape that can eliminate the above-mentioned drawbacks and reliably prevent copying. According to the present invention, a vertical synchronizing signal of a level deeper than the level of the vertical synchronizing signal is placed on a magnetic tape at a predetermined position between the vertical synchronizing signals sandwiching one field of video signal in the composite video signal. By superimposing and recording over a predetermined range t on a composite video signal, the present invention will be explained in more detail with reference to an embodiment. Figure 1 shows an embodiment to which the method of the present invention is applied. It is a block diagram.

1 is a video camera, and a synthesized video signal from the video camera 1 is inputted to a video tape recorder 3 through a waveform synthesis circuit 2. On the other hand, the composite video signal from the video camera 1 is input to the vertical synchronization signal separation circuit 4v, and the vertical synchronization signal is separated and applied to the video tape recorder 31 as a motor synchronization control signal. Further, the vertical synchronizing signal is inputted to a vertical synchronizing signal waveform shaping circuit 5e which generates other vertical synchronizing signals to be described later. The vertical synchronization signal waveform shaping circuit 5 has a pulse width that is at least longer than the pulse width of a normal vertical synchronization signal at approximately the center between the input vertical synchronization signals and the subsequent vertical synchronization signals, and the pulse level is equal to the input vertical synchronization signal. It is configured to output another vertical synchronizing signal (hereinafter referred to as a vertical synchronizing signal) which is at least deeper than the level of the ``1'' signal and closer to the black level side.

The variable resistor 5-1 of the vertical synchronizing signal waveform shaping circuit is a variable resistor that sets the output timing of the vertical synchronizing signal. The variable resistor 5-2 is a variable resistor that sets the pulse width of the sensitive vertical synchronizing signal, and it is normal to keep the pulse width of the sensitive vertical synchronizing signal constant, so it may be omitted.

The vertical synchronizing signal output from the vertical synchronizing signal waveforming circuit 5 is applied to the waveform synthesizing circuit 2, multiplied by 1f with the composite video signal output from the video camera 1, and applied to the video tape recorder 3. .

Therefore, the signal recorded on the video tape recorder 3 is a composite video signal and a vertical video signal inserted approximately in the center between the two vertical Jυ signals sandwiching the video signal of one field of the composite video signal. υ1 and jojun are recorded in a superimposed manner. The period during which the vertical synchronization signal is inserted is a predetermined period from the start of recording on the magnetic tape.

Therefore, when a magnetic tape on which a composite video signal with a vertical sync signal superimposed is played back on a television receiver, the television receiver uses the inserted vertical sync signal as the vertical sync signal rather than the original vertical sync signal. The image is originally a VU image because it is detected as ■. The image on the television receiver that should be displayed to the north of the image is as shown in Figure 2.The VD image is on top and the VU image is on the bottom.The original image is divided into two, upper and lower. This is the image P that was replaced. In this case, when producing a television image from a video source, the television ll! is created so that the image as shown in FIG. 2 does not look unnatural. ! By creating a single image (software), it will not cause any discomfort.For example, if a vertical synchronization signal is inserted in the Jυ11i, ++, after a few seconds of 1m have passed, the vertical synchronization will be lost. The part where the signal is inserted ends, and a normal +t+U image is displayed in the part e where the sensitive 1G synchronization signal is not interposed.

In addition, when copying a magnetic tape recorded with a composite video signal obtained by m-folding the sensitivity type 1α same R) I signal, the sensitivity j1η direct 101 signal is inserted due to the presence of the sensitivity direct synchronization signal. During the transition period t, the motor of the video tape recorder malfunctions, causing disturbances in the running of the magnetic tape. Therefore, when the above-copied magnetic tape is played back, the 11'' W1 in the section where the sync signal was inserted is distorted, and the image becomes disorganized.

The above example shows the case where the vertical synchronization signal (vP) is inserted approximately at the center P between two vertical synchronization signals (Vs) sandwiching one field of video signal in the composite video signal, that is, the vertical synchronization signal Vs The time difference between
An example has been described in which the time difference of /2 field is e, but this time difference may be arbitrarily e. When this time difference is set to an arbitrary V, the reproduced image of the magnetic tape is the third
As shown in the figure, a black band appears at the top or bottom of the image due to the time difference between the direct 1υ] signal Vp and the original vertical synchronization signal Vs, and when the image]ψ is horizontally long, it becomes an M cinema scope-like image. . In this case, if you take this into account when producing television images, the image will not look strange and will simply have black bands at the top and bottom.

Next, the sensitive direct synchronization signal Vp and the original vertical synchronization signal V8
When the magnetic tape in case 2 is copied from a video tape recorder (e) where the time difference is set to a time other than the 1/2 field time, the synchronization of the motor of the video tape recorder is controlled by the direct synchronization signal Vp It. The image when playing the copied magnetic tape is distorted and the image is similar to Jυ
In the transient Jυ1 where the j signal is inserted, the synchronization is disrupted,
Although the case where a video camera is used in the embodiment of zero or more images that do not form a body of image 1ψ has been described as an example, other image sources may be used.

Further, in this embodiment, a magnetic tape has been described, but the present invention can also be applied to a video disk.

As explained above, according to the present invention, when copying and generating +4f by inserting a deep-level direct synchronization signal over a certain range of I9r in the section other than the vertical blanging of the composite video signal, Since the synchronization of the reproduced image is disrupted, it is no longer possible to produce a correct H copy.

[Brief explanation of drawings]

FIG. 1 is a block diagram in which an embodiment of the method of the present invention is connected, and FIGS. 2 and 3 are diagrams for explaining the operation of the embodiment of the present invention. 1...Video camera, 2...Waveform synthesis circuit, 3...Video tape recorder, 4...Vertical synchronization signal 1IlIF
Circuit, 5 - Sensitive direct synchronization signal waveform shaping circuit 0 Patent applicant: Toshiba EM Corporation 0 Figure 3 -550-

Claims (1)

[Claims] When recording a composite video signal on a magnetic tape or a video disk, a predetermined position between vertical synchronizing signals sandwiching one field of video signal in the composite video signal is at least higher than the level of the vertical synchronizing signal. A method for recording a composite video signal on a magnetic tape or the like, characterized in that another deep level vertical synchronization signal is superimposed and recorded on the composite video signal over a predetermined range of the magnetic tape or video disc.