Apparatus and method for positioning an ink-jet printing head

摘要

A circuit and related method are provided for maintaining a desired spacing between an ink-jet printing means and a receiving surface along a line scanned by the printing means. An ultrasonic transducer transmits signals at timed intervals to the receiving surface from the printing means. A reflected signal from the receiving surface is sensed by the transducer during a receiving time window after the signal is transmitted. A reference position signal representative of the head to surface spacing at a printing location is compared to the desired head to surface spacing to produce a position error signal. A servomotor responds to the position error signal to move the printing means toward and away from the receiving surface to maintain the desired spacing.