BigPatents India

A plate making method for mimeographic printing which melts by thermal head heating a plate consisting of a thermoplastic resin film to form ink permeable openings. A film (12) is formed on one surface thereof with many fine recesses (14). A heater size for a thermal head (10) satisfies the relations, HM > 0.6PM and HS > 0.7PS, when the main-scanning-side array pitch of the heater is PM, main-scanning-side heater length HM, sub-scanning-side feed pitch PS, and sub-scanning-side heater length HS. A surface opposite to the fine recess-formed surface of the film is heated by an energy output of up to 35 milli-joule per mm2. The heated portion is melted for communication with fine recesses to form ink permeable openings. Ink-permeable openings can be thermally punched independently in the film without increasing a thermal head output, and plate making is realized by using a plate consisting of only a thermoplastic resin film. (FIG. 1 )