Apparatus for pressing a print head in a printer

An apparatus for pressing a print head against a platen roll in a printer, which comprises a rotating profiled cam having a peripheral surface supporting the print head for moving the print head toward and away from the platen roll, means for pressing the print head against the peripheral surface of the cam, a shaft in the center of and integral with said cam for rotating the cam, said peripheral surface having three peripheral sections, an arcuate first peripheral surface section for gradually and smoothly changing the distance between the print head and the platen roll, points along said arcuate first peripheral surface section being at a gradually increasing distance from the shaft until a smooth, gradual transition into a circular second peripheral surface section for maintaining the print head against the platen roll, points along said circular second surface section being equidistant from said shaft, and a third peripheral surface section disposed between those ends of said arcuate first and circular second peripheral surface sections that are opposed to their ends at said smooth, gradual transition, each of the respective ends of said third peripheral surface section defining abrupt peripheral stopping surfaces for preventing the rotation of the cam past each of said abrupt stopping surfaces.