| 摘要 |
PURPOSE:To reduce the manufacture cost by writing a subscreen signal into a display field memory synchronously with a main screen signal so as to eliminate a buffer line memory and its control circuit required for time matching of the two screens. CONSTITUTION:A video signal of the subscreen inputted to an input terminal 5 is subject to digital conversion by an A/D converter 6, inputted to a latch circuit 7, where the signal is latched by a latch pulse LP introduced from a memory control circuit 9. A data of the latch circuit 7 is read and written in a field memory 10 and in this case, it is controlled that the data at the address N is written in the address N of the field memory 10 without fail. The subscreen data written in th field memory 10 is used synchronously with a master clock BS during a prescribed period within the image period of the main screen by the memory control circuit 9, decoded into an analog signal by a D/A converter 11 and applied to an image circuit.
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