Patent ID: 7595971

Claim:
A coordinated method of operating solenoids comprising the steps of: applying a pulsed driving voltage to a coil of a first solenoid, the pulsed driving voltage having a frequency of about 5 to about 10 KHz; measuring a resultant current in the coil; and detecting a first discontinuity in a rate of change of the current, which first discontinuity is produced simultaneously with a first change of speed of an armature of the first solenoid; releasing the driving voltage from the coil of the first solenoid; measuring a resultant current in the coil; detecting a second discontinuity in a rate of change of the current, which second discontinuity is produced simultaneously with a second change of speed of the armature; producing a coordinating control signal from said detection of either the first or the second discontinuity; employing the coordinating control signal to actuate a second solenoid within a time period no greater than about 5 milliseconds; and wherein timing of production of the control signal is independent of a rise time or a decay time of current in the coil of the first solenoid.