| 摘要 |
PURPOSE:To simplify the device and to make the device inexpensive by using respectively two systems of video selecting circuits and video synchronizing circuits and changing over only in a part of a vertical synchronizing signal. CONSTITUTION:The inputted plural video signals are selected by the video selecting means 103a, 103b and synchronized by the video synchronizing means 104a, 104b. In this case, when the selected video is changed, the discontinuity of the picture on a screen is generated and the picture is disturbed. Therefore, with respect to the change of the selected video of one system, the video of the other system is operated previously by more than one picture (Before the change over, the next selected picture is prepared). Thereby, the picture having no discontinuity on the screen is formed and by selecting by a system selecting means 107, the generation of the boundary of the video on the screen due to the change in the selection of the video is prevented.
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