Abstract: Printing apparatus has an ink jet printhead mounted on a carrier for movement during printing of characters between left and right margin locations relative to a document. A directionally oriented grating and associated circuitry is provided to maintain a record of character and ink drop printing locations. The printhead begins its movement prior to the left margin location and sweeps toward the right margin for printing of an entire line of characters. Thereafter, the printhead is returned to the aforesaid position prior to the left margin in readiness for another line sweeping action. Provision is made for testing carrier velocities encountered in movement to the right during printing as well as to the left during carrier return and for determining optimum times of operation of the carrier return magnet and its release in order to reduce time required for carrier turnaround.

Abstract: An ink jet printing system is provided with synchronization facilities including charging, deflecting, and gutter components and a technique is described for referencing synchronizing pulses to a pedestal voltage level to insure that the ink drop stream clears the gutter during synchronization cycles.