| 摘要 |
PROBLEM TO BE SOLVED: To regulate head pressure automatically depending on the breadth dimension of a print sheet when it is altered by providing a head pressure regulating mechanism for increasing or decreasing the head pressure based on a displacement detected by a sheet width detecting means on the side of platen roller or thermal head. SOLUTION: A head pressure regulating means, i.e., a press rod 12, has one end side secured to the upper end of an inclining plate 11 and the other end side provided with a spring receiving part 12A wherein a spring 14 is inserted, under compressed state, between the spring receiving part 12A and a thermal head 3. In order to position a print sheet 2 in the center of a sheet holder 5, a centering mechanism 7 is operated and the press rod 12 is displaced by the inclining plate 11 depending on the displacement in the interval of sheet width detecting mechanisms, i.e., flange members 10, interlocked with the centering mechanism 7 thus regulating the pressure of the thermal head 3 automatically through the spring 14.
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