Patent ID: 6978978

Claim:
An electric fluid dispenser for dispensing a fluid onto a substrate comprising: a dispensing valve movable between open and closed positions for controlling a flow of the fluid from said fluid dispenser; a solenoid coil operable to cause said dispensing valve to move between the open and closed positions; a power circuit comprising a power switching circuit providing a stepped current waveform to said solenoid coil, and an unregulated power supply providing an output voltage to said power switching circuit; and a control circuit comprising a power switch control operable to cause said power switching circuit to provide said stepped waveform comprising an initial peak current followed by a lesser hold current, said initial peak current having a rate of current flow represented by a slope of a leading edge of said initial peak current, said slope of the leading edge being produced in response to a first output voltage from the unregulated power supply, a current sensor providing a current feedback signal representing current flow in said solenoid coil, and a duty cycle control responsive to said output voltage from said unregulated power supply and said current feedback signal and being operable to cause said power switch control to maintain the slope of the leading edge of said initial peak current substantially constant in response to changes in said output voltage from said first output voltage.