Printer hammerbank cam drive having pulsed startup

Abstract From the Canadian patent

In a dot matrix line printer in which an elongated hammerbank and an opposite counterbalancing assembly are driven in opposing reciprocating fashion by a motor driven cam, the size of the cam drive motor and the current requirements thereof during startup of the printer are greatly reduced by applying current pulses to the motor in a pattern synchronous with the resonant frequency of the reciprocating cam driven system. The current pulses which are considerably smaller in amplitude than the continuous current conventionally used to produce startup are generated during alternate half cycles of the resonant frequency causing the, cam to rock back and forth until eventually the peak resistance …