| 摘要 |
PURPOSE:To sharply reduce memory capacity by a method wherein, in the memory cell region having a repetitive pattern, a subfield is formed in the size integer multiple of a cell size and used as the jumping pitch of the main deflector, and the pattern information only in the subfield is stored. CONSTITUTION:The subfields F1-F3 in the main field of a memory reticle have the same repetitive patterns Pa and Pb. The matrix-formed subfields as above-mentioned can be selected by the information only by giving pitches PX and PY, and the amount of memory becomes several thousandths of that of the method heretofore in use when the coordinate and the size of each pattern is memorized in the same manner as before. When there is a repetitive pattern Pc, said region and the other subfields F1 and F2' are superposed and divided into the matrix in the same manner as above, and the same main field is exposed again by giving the starting point of the coordinate of F', the pitch and the number of the subfields. All the information are stored in an overflowed field. According to this method, the amount of memory can be reduced sharply.
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