Method of and apparatus for making heat-sensitive stencil and heat-sensitive stencil material

Abstract

When thermally perforating a thermoplastic resin film of heat-sensitive stencil material by the use of a thermal head, supply of energy to the thermal head is cut at a time the diameter of the perforations becomes not smaller than 65% and not larger than 95% of a target diameter of the perforations.

What is claimed is:  
     
         1 . An apparatus for making a stencil comprising a heat source which is heated through a supply of energy, a heat source control means for supplying energy to the heat source and a scanning means for scanning a thermoplastic resin film of heat-sensitive stencil material with the heat source to thermally form perforations arranged in both a main scanning direction and a sub-scanning direction in the thermoplastic resin film, wherein 
 the heat source control means cuts the supply of energy to the heat source at a time the diameter of the perforations becomes not smaller than 65% and not larger than 95% of a target diameter of the perforations.    
     
     
         2 . An apparatus as defined in  claim 1  in which the heat source control means sets the target diameters of the perforations in the main scanning direction and the sub-scanning direction to be not smaller than 45% and not larger than 80% of the scanning pitches in the respective directions.  
     
     
         3 . An apparatus as defined in  claim 1  in which the heat source control means sets the target area of the perforations to be not smaller than 20% and not larger than 50% of the product of the scanning pitches in the main scanning and sub-scanning directions.  
     
     
         4 . An apparatus for making a stencil comprising a heat source which is heated through a supply of energy, a heat source control means for supplying energy to the heat source and a scanning means for scanning a thermoplastic resin film of heat-sensitive stencil material with the heat source to thermally form perforations arranged in both a main scanning direction and a sub-scanning direction in the thermoplastic resin film, wherein the heat source control means cuts supply of energy to the heat source at a time the area of the perforations becomes not smaller than 42% and not larger than 90% of a target area of the perforations.  
     
     
         5 . An apparatus as defined in  claim 4  in which the heat source control means sets the target area of the perforations to be not smaller than 20% and not larger than 50% of the product of the scanning pitches in the main scanning and sub-scanning directions.  
     
     
         6 . An apparatus as defined in  claim 4  in which the heat source control means sets the target diameters of the perforations in the main scanning direction and the sub-scanning direction to be not smaller than 45% and not larger than 80% of the scanning pitches in the respective directions.