| 摘要 |
PURPOSE:To increase precision in drawing such geometic figures as trapezoids or triangles by a method wherein the drawing of a segment is terminated and another started when the difference between a basic travelling distance L of an electron beam and a gap DELTAl of radiated spots on the segment is not more than DELTAl/2. CONSTITUTION:A write command puts in a register 4 the data of the coordinate X for a segment end P and then the data of the coordinate Y are outputted from a unit 10, resulting in the radiation of the point P by an electron beam. Another command causes the register 4 to read the output of an adder 5 and the beam illuminates a point apart from the point P by a DELTAl. Stored in a register 15 are the data pertaining to the time length L during which a most concentrated illumination is to be made upon the segment M. Signals are transmitted through an adder 18, a switch 20, and a register 21 and then reachs a subtractor 22, which yields an output of L+DELTAl/2-iDELTAl when the spot of radiation is displaced by a pitch i using a DELTAl as the unit. When the output is not more than DELTAl/2, a comparator 23 yields a pulse which drives a controlling circuit 24, thereby ending the drawing of the segment M, and then the illuminator moves to a point where another drawing is to start. The constitution doubles the precision of the drawing work. |
