Patent ID: 8465263

Claim:
An airless paint sprayer comprising: a pump; a reciprocating electromagnetic actuator operably coupled to the pump, the actuator having a coil that when energized causes the actuator to drive the pump; coil current sensing circuitry configured to provide an indication of current flowing in the coil; coil drive circuitry configured to supply current to the coil; and a controller coupled to the coil current sensing circuitry and the coil drive circuitry to supply current pulses to the coil during a plurality of pulse cycles, each pulse cycle having a pulse on-time in which current is applied to the coil and a pulse off-time, the controller being configured to: set a target pulse on-time threshold; monitor a current pulse applied to the coil during a particular one of the pulse cycles; terminate the monitored current pulse if a duration of the monitored current pulse meets the target pulse on-time threshold; and determine whether an amplitude of the monitored current pulse meets an amplitude threshold and, in response: terminate the monitored current pulse; determine the pulse on-time of the monitored current pulse that was terminated; adjust the target pulse on-time threshold based on the determined pulse on-time; and terminate a current pulse applied to the coil during one or more subsequent pulse cycles based on the adjusted target pulse on-time threshold.