Abstract

A thermal master making device includes a thermal head having a plurality of heating elements arranged in an array in the main scanning direction. The thermal head is caused to contact a stencil including a thermoplastic resin film. While the master is fed at a preselected feed pitch in the subscanning direction perpendicular to the main scanning direction, the heating elements selectively heat and perforate the film of the stencil in accordance with image data to thereby form an image in the stencil in the form of a dot pattern. A pitch at which the heating elements are arranged and the feed pitch are substantially equal to each other. The heating elements each have a length in the subscanning direction smaller than one-half of the feed pitch inclusive and have a length in the main scanning direction greater than the length in the subscanning direction. The device is capable of stably forming desired perforations in the stencil and extending the life of the heating element and therefore the life of the head. In addition, the device needs a minimum of master making time and therefore operates at a high speed.