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

An apparatus for making a stencil comprising a heat source which is heated through supply of energy, a heat source control means which supplies energy to the heat source and a scanning means which scans 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 when a time interval not shorter than 50% and not longer than 100% of an estimated perforating time lapses from the time at which supply of energy to the heat source is started, the estimated perforating time being a time interval expected to be necessary for a perforation to be produced by the heat of the heat source and to be enlarged to a desired size as a final size as measured from the time at which the supply of energy to the heat source is started, wherein the estimated perforating time being set to be a time t2 represented by formula
• 15 B A ⁢ ⁢ exp ⁢ ⁢ ( Ct 2 ) = 4 100
• when a graph of the diameter of the perforation against the time from the time at which supply of energy to the heat source is started is regressed on an exponential function
• 16 A - B exp ⁡ ( Ct )
• wherein A, B and C are positive constants.