| 摘要 |
PURPOSE:To hit a part of the unnecessary part on a display surface to earse the peripheral part of hitted coordinates, by providing a CRT refresh memory which sends data to an outline coordinate table generator and a smear-out generator and sends image information to a CRT. CONSTITUTION:In case of erasing of a dirty part A on a CRT2, when a part of the part A is hitted with a light pen 3, coordinates of the hitted part are calculated in a light pen hit coordinate generator 4. A table of outline coordinates of an image picture including coordinates of the hitted part is generated on a basis of coordinates of the generator 4 by an outline coordinate table generator 5, and an erasing signal related to the image picture of the part A is generated on a basis of the outline coordinate table by a smear-out generator 6. Data is sent to the generator 5 and the generator 6 from a CRT refresh memory 1 in accordance with the control signal from them, and image information is sent to the CRT2, thus simplifying the operation for erasing. |
