Control apparatus for the recording head of a parallel printer

Claim 1

In a control circuit for a multiple printing position printer having a stationary printing head which extends over the entire widTh of a printing line and has a plurality of individual printing elements for each printing position, said circuit including a printing position selection means for selectively applying printing current to the printing elements of a selected printing position, and a character selection means, which is common to all printing positions, for controlling the flow of printing current to the printing elements of the selected printing position in dependance on the particular character to be printed at said selected printing position, the improvement wherein: said position selection means has a plurality of outputs each of which is connected via respective series resistors with all of said individual printing elements of the associated printing position; and character selection means has a plurality of output leads each associated with only one printing element of each of a plurality of said printing positions, and a plurality of controllable normally open short circuit switches each of which is connected in series between one of said character outputs and a point of reference potential; and, each of said printing elements is connected to the associated one of said character output leads only via a separate decoupling diode whereby the selective closing of one or more of said switches will short circuit the printing current flowing from said position selection means around the printing element of the selected printing position associated with the closed switch and only the printing elements of the selected printing position which are associated with open ones of said switches will be supplied with printing current.