| 摘要 |
PURPOSE:To maintain well a position accuracy determined depending upon a resolution of a D/A converter by extending a drawing point distance by incresing a current density and shortening the drawing time by a jump-over scanning of the beam, with a bit shift circuit provided in a counter circuit. CONSTITUTION:A drawing is performed along a pattern edge 21 and a drawing point 22 is determined by a resolution of a D/A converter, the beam draws an image 23 at a maximum current amout and a pattern information is given at the beginning point (X1,Y1) and termination point (X2,Y2). An information is shifted one bit by a X1 load signal to a X1 register and the smallest order bit side, thereafter, being added to a X-counter. At this time, a digit-down is stored by utilizing for a register a highest bit on the counter. The X-counter serves to perform the operation by a pulse from a controller, the output of which is shifted by one bit to the highest side to be applied to the D/A converter, and the information is advanced two steps. In this case, the highest bit output of the X-counter is connected to the lowest bit of the converter. The exposure can be achieved at a high accuracy also for a Y- direction. |
