| 摘要 |
A video signal of a sub-picture screen is supplied from an input terminal (5) via an adder (6) for superimposing display to a forming control circuit (7) for a sub-picture screen signal, and a sub-picture screen video signal, which is compressed to an arbitrary size, is synthesized with a video signal of a main picture screen from an input terminal (1) at a change-over switch (2). Further, in accordance with a command signal supplied to a microcomputer (10), a central processing unit (CPU) (11) produces a control signal which decides a size, a position and the like of display of sub-picture screen. Also, a signal from the central processing unit 11 is supplied to a display control circuit (12) which then produces a figure signal to be superimposed and displayed. Set values of size, position and the like of sub-picture screen display are recorded on and held by a random access memory (RAM) (13). The set values are supplied through the central processing unit (11) to the display control circuit (12) and hence such a figure signal is produced that the figure is reduced or expanded in response to expansion or reduction of the sub-picture screen.
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