A servo system for adjusting the velocity of ink drops in a magnetic ink jet printer has a coarse control loop for making coarse increment adjustments to the pump which supplies ink under pressure to a nozzle and a fine control loop for making fine increment adjustments to the pressure of said pump....http://www.google.com.au/patents/US4045770?utm_source=gb-gplus-sharePatent US4045770 - Method and apparatus for adjusting the velocity of ink drops in an ink jet printer
