| 摘要 |
PURPOSE: To decrease the variation in the transmittance of liquid crystals and to enable marking with decreased uneven images by successively changing over the marking patterns of a liquid crystal mask in the scanning line unit subjected to scanning with a laser beam to ensuing marking patterns. CONSTITUTION: A controller 7 drives the liquid crystal mask 6 so as to shift raster scanning to the next main scanning line and to change over the marking pattern for the main scanning line subjected to the raster scanning to the marking pattern to be displayed next when the end of the raster scanning of the one main scanning line is detected. From this time on, the controller 7 similarly drives the liquid crystal mask 6 so as to shift the raster scanning to the next main scanning line at every ending of the raster scanning of the one main scanning line and to change over the marking pattern of the main scanning line subjected to the raster scanning to the marking pattern to be displayed next. The controller 7, thereafter, drives motors 14, 15 to change the marking position of a work piece, and then, scans the mask 6 again when the laser scanning of the present marking pattern ends. |
