Print head and roller biasing mechanism for a hand held thermal printer

A printing mechanism for a hand held printer which prints characters and drawings on a print paper by manual movement of said printer over the surface of said print paper, said printer being movable in a print direction and a nonprint direction over said print paper surface by manually pressing the printing mechanism to the print paper, the printing mechanism comprising a thermal print head movably supported in the printer, a thermal transfer ribbon supported in the printer, thermal head biasing means for biasing the thermal print head through the thermal transfer ribbon to the print paper, ribbon take up means for winding the ribbon, movement measurement means for generating a signal corresponding to movement of the printer over the print paper, drive roller means for driving the ribbon take up means and movement measurement means, clutch means engaging the drive roller means and only rotatable in the print direction, drive roller biasing means for biasing the drive roller means in a predetermined direction, and displacement means acting independently of the thermal head biasing means for moving the drive roller means independently of the thermal print head to the print surface when the drive roller means is biased by the drive roller biasing means.