International Business Machines Corporation

Harry P Heibein

Carl Robert Bildstein

Roderick S Heard

John M Salvadore

Michael L Sendelweck

John A Lowy

John Michael Carmichael

Chein-Hwa S Tsao

Richard G Millington

Dean J Scott

Richard William McCornack

Harlan P Mathews

An ink jet pump is switched from a mechanically off or idle state to a mechanically on or active state with no drift in pressure output by maintaining the pump at the same point in its force-temperature characteristic when it is on and off. This is accomplished by driving the pump in both the active and idle states with signals that dissipate the same amount of power in the pump. The frequency of the idle state signal is high enough that the pump can not mechanically respond. The power dissipations in the active and idle states are matched by adjusting the current build-up and current decay through the coil of the pump during the idle state. When the RMS current through the coil in the active state equals the RMS current in the idle state, the power dissipations are matched.

Force-temperature stabilization of an electromagnetic device

In an ink jet printer, it is desirable to compensate the flight of the ink drops to correct for print errors caused by aerodynamic effects. The apparatus shown herein corrects the flight of ink drops for all aerodynamic effects, drop interactive and environmental. Correction for drop interactive effects can be accomplished in any of several well known ways. The additional correction for environmental effects is accomplished by scaling the drop interactive correction. The scale factor is first determined for static environmental conditions. Environmental conditions include the climate in which the printer operates and the specifications on the component parts of the ink jet printing assembly. The scale factor can be adjusted dynamically for changes in the environment. In particular, changes in air density of the environment are monitored and used to dynamically adjust the scale factor.

Scaling aerodynamic compensation in an ink jet printer

The ink jet head assembly disclosed herein has modular subassemblies with predetermined relationships between the subassemblies to minimize realignment of the ink stream when a subassembly is replaced in the field. The head assembly is modularized into nozzle, charge electrode, deflection electrode and gutter subassemblies. The charge electrode module is mounted on the nozzle module in a manner such that no field adjustment is necessary to center the charge electrode horizontally to the ink stream. The deflection electrode module is mounted on the gutter module in a manner such that no field adjustment is necessary to center the deflection electrode horizontally to the ink stream. The nozzle and charge electrode subassembly have a preset adjustment, and the gutter and deflection electrode assembly have a preset adjustment such that no field adjustment between these two subassemblies is necessary to maintain a constant flight distance for the ink drops. Finally, the nozzle module is adjustable to reposition the ink stream about the pitch axis (vertical adjustment) and the yaw axis (horizontal adjustment). The yaw axis adjustment may be preset. The pitch axis adjustment is the only mechanical adjustment necessary in the field when replacing the nozzle module.

Field replaceable modules for ink jet head assembly

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.

Ink jet printing system with pedestal synchronization

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Longmont, CO, United States of America

Harry P Heibein