Patent attributes
A roll sheet is unwound and fed with its side edge being positioned in a reference point of the thermal head, and then subjected to printing by the thermal head. Coil springs are placed at positions respectively dividing substantially equally a length from a center to each end of the thermal head. A distribution of loads on the thermal head by each coil spring is determined so that a load exerted on the thermal head on the reference point side is larger than a load exerted on the thermal head on the opposite side. A position of a resultant force of the coil springs acts on the thermal head at a position displaced by a distance obtained by multiplying an entire length of the thermal head by a coefficient, from a center of the thermal head in the longitudinal direction toward the reference point.
