Dot printer.

摘要

This invention relates to a dot printer of the type in which received printing data are converted into dot-patterns to be printed. A printer of this type mainly comprises: a main memory (2) which stores the printing data as either fixed part data and variable part data; a mechanism for identifying the fixed part data and the variable part data; and a buffer or buffers (B1, B2) for storing the result of performing an operation, usually called "dot-expansion," on the printing data stored in the main memory (2). The contents of the buffers (B1, B2) are applied to the printing head (H), which in turn, prints dot-images on a sheet of paper. Because the CPU (1) dot-expands and recopies only the variable part data in the main memory (2) into the buffer (B1, B2), a needless computation associated with dot-expanding fixed-part data is eliminated. In addition, if two buffers (B1, B2) are used, a first buffer may hold dot-expanded data while the printing head is operating and while the other buffer is being filled with dot-expanded data, to be printed subsequent to the printing of the contents of the first buffer. Segmenting the main memory into fixed part data and variable part data and two-buffer scheme allow printers of the present invention to print a document faster than conventional dot-printers.