JPS6016159B2 - Video tape recorder simultaneous monitor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a video tape recorder simultaneous monitoring device.

When testing a large number of video tapes, it is necessary to run a large number of video tapes through a number of video tape recorders.

In such a case, in order to monitor the reproduced signal on a television, conventionally the same number of televisions as the number of video tape recorders were lined up for monitoring.

However, since one person usually works by operating a large number of video tape recorders, arranging a large number of monitor televisions in this way is not only difficult and inconvenient, but also increases the size of the equipment. In order to eliminate these drawbacks, the present invention makes it possible to simultaneously monitor multiple playback signals on one television by making only slight improvements to the conventional videotape recorder. Let's explain by following an example. In FIG. 1, numeral 1 is a first rotary head type video tape recorder operating at a fixed frequency 2, and numeral 3 is another rotary head type video tape recorder operating with a variable frequency power supply 4. In FIG.

From each video tape recorder, a respective synchronization separation circuit 5,
6 separates the synchronization signal and compares it in phase comparison circuit 7. And even with that phase difference, the variable frequency power supply 4
control. By doing this, the rotation of the video head of the rotary head type video tape recorder No. 3 is controlled, so that the synchronization of both signals is exactly the same as shown in FIGS. 2a and 2b. In the figure, a is the signal of one rotary head type video tape recorder, b' is a signal of each of three rotary head type video tape recorders. When these signals are input to the video signal switching circuit 8 and the signals are switched at an arbitrary point x, a composite signal divided at the switching point x is obtained as shown in FIG. 2c. When this signal is input to the monitor television 9, two images A and B are obtained overlapping each other. Note that instead of using the synchronization signal of the first rotary head type video tape recorder as the reference, a television signal generator may be used and used as the reference. As described above, the video tape recorder simultaneous monitoring device according to the present invention is a simple device that can monitor the signals of multiple video tapes on a single television, and is therefore very useful as a measuring device and also as a completely synchronized signal converter. is also valid.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a video tape recorder simultaneous monitor device according to the present invention, and FIG. 2 is a time chart of its signals. 2... Fixed frequency power supply, 1... First playback device, 4
...Variable frequency power supply, 3...Other playback devices, 5, 6
...Synchronization separation circuit, 7...Phase comparison circuit, 8...
Video signal conversion circuit, 9...Monitor TV. Figure 1 Figure 2

Claims (1)

[Claims] 1. Detecting the phase difference between synchronizing signals extracted from a first reproducing device operating with a fixed frequency power source and another reproducing device operating with a variable frequency power source, and determining the variable frequency based on the phase difference between the detected synchronizing signals. Controlling the power supply to synchronize the first playback device and another playback device, and switch the video signals re-output from the first playback device and the other playback device to play them simultaneously on one monitor television. A videotape recorder simultaneous monitor device characterized by: