| 摘要 |
<p>PURPOSE:To rapidly display data without successively calculating boundary coordinates by performing the logical operation of the signals read from an image memory and a boundary data memory to select only the video signal in an image display region. CONSTITUTION:A character or figure mark desired to be displayed is written in a character memory 3 by the setting of a display mode and the interior of an image display region is set to a logical value 1 to write coordinates data in a boundary data memory 4. When the AND of the content a2 of the memory 3 and the content of the memory 4 successively read during a display period is performed by the AND gate of a logical operation circuit 6, the character or figure mark on the memory 3 present within the image display region can be taken out and the result thereof becomes c3. In the same way, when the AND of the logical values read from an image memory 1 and the memory 4 is performed, only the image signal c1 in the image display region can be taken out. These signals are separately controlled in voltage level by an output control circuit 7 to be displayed in a superposed state. By this method, only the image signal in the image display region can be selected without calculating boundary coordinates.</p> |
