Printing unit particularly intended for price labelling machines

Claim 1

An improved printing unit, particularly intended for price labelling machines, comprising a plurality of printing wheels, a plurality of pivotally supported carrier arms equal in number to the number of said printing wheels and juxtaposed to each other in side-by-side relationship, means rotatably supporting each of said printing wheels on a respective one of said carrier arms with said printing wheels being positioned in a row and presenting printing matrices on their respective outer peripheries, intermittent drive means having a common driving element operatively coupled to each of said printing wheels for advancing said printing wheels simultaneously over an equal number of degrees of incremental rotation, a plurality of pivotable pressure arms equal in number to the number of said carrier arms, means providing an operative connection between each of said pressure arms and a respective one of said carrier arms for pivoting a respective carrier arm upon pivotal movement of the respective pressure arm, a rotatably driven impact member, shoulder means formed on said pressure arms, said pressure arms being movable between a non-printing position in which said shoulder means is free of engagement with said impact member and a printing position in which said shoulder means is positioned to be engaged by said impact member for pivoting said pressure arms and said carrier arms for bringing the respective printing wheel into engagement with the article to be imprinted, a position determining device responsive to the angular position of said printing wheels, electromagnetic means operatively connected to said position determining device for operation thereby, motion transmitting means operably connected to said electromagnetic means for moving selected of said pressure arms into a position wherein said shoulder means is positioned to be contacted by said impact member for pivotally moving said selected pressure arms and their associated carrier arms for pressing the matrix in printing positon on the associated printing wheel into engagement with the article to be imprinted.