Wire dot matrix printer capable of printing letters on a plurality of superposed sheets of paper

Claim 1

A wire dot matrix printer for printing letters on a plurality of superposed sheets of paper, comprising: a printing head including a plurality of solenoids and a plurality of printing wires which are each displaced by a corresponding one of the solenoids; a platen roller opposed to the printing head; distance adjusting means for increasing and decreasing the relative distance between the front ends of the printing wires in the printing head and the platen roller, the distance adjusting means including a control lever for adjusting a relative distance between the front ends of the printing wires of the printing head and the platen roller; and control means cooperable with the distance adjusting means for controlling the drive current to the respective solenoids to continuously adjust the drive current of the solenoids in accordance with the position of the control lever, the control means comprising: a one-shot monostable multivibrator generating variable-width printing control signals to continuously adjust the drive current of the solenoids, and a capacitance/resistance circuit including a variable resistor coupled to the one-shot monostable multivibrator and to the control lever such that adjustment of the control lever is operable to adjust the resistance value of the variable resistor to change the pulse width of the printing control signals and adjust the drive current of the solenoids in accordance with the position of the control lever.