| 摘要 |
PROBLEM TO BE SOLVED: To enable a pattern to be accurately and efficiently drawn, without enhancing the accuracy of a DA converter or complicating pattern data and their conversion. SOLUTION: Main and auxiliary deflection data are sent from a pattern data generating circuit to a main and auxiliary D/A converters 24 and 25, through the intermediary of a main/auxiliary deflection control circuit 23 based on pattern data sent from a host computer 21, additional deflection data set on a register are given to the main and auxiliary deflection data by the use of an adder 32 and a subtracter 33, with which the D/A converters 24 and 25 are changed in deflection position without changing a drawing position, and multiple drawing is carried out by successively changing the deflection position in variation. Through this multiple drawing, random errors of the D/A converters are averaged out, so that the D/A converters are substantially enhanced in accuracy.
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