Abstract: An apparatus and method for removing air or other gases from a free-ink ink-jet pen is provided in a manner that does not waste ink or require disposal of purged ink. A gas separation and purge mechanism is incorporated into a pen body construct having an ink containment chamber such that gases will rise toward the mechanism. A vacuum is cyclically applied to the gas separation and purge mechanism to remove the gas and to allow the ink containment chamber to refill from a remote reservoir as needed.

Abstract: An ink supply for an inkjet printer is provided with a main reservoir, which is typically maintained at ambient pressure. The main reservoir, which has flexible side walls supported by a rigid frame, is coupled to a variable volume chamber via a check valve which allows the flow of ink from the reservoir to the chamber and limits the flow of ink from the chamber to the reservoir. The chamber is coupled to a fluid outlet which is normally closed to prevent the flow of ink. However, when the ink supply is installed in a printer, the fluid outlet establishes a fluid connection between the chamber and the printer. The chamber is part of a pump provided with the ink supply that can be actuated to supply ink from the reservoir to the printer.

Abstract: An apparatus and method for removing air or other gases from a free-ink ink-jet pen is provided in a manner that does not waste ink or require disposal of purged ink. A gas separation and purge mechanism is incorporated into a pen body construct having an ink containment chamber such that gases will rise toward the mechanism. A vacuum is cyclically applied to the gas separation and purge mechanism to remove the gas and to allow the ink containment chamber to refill from a remote reservoir as needed.

Abstract: A thermal technique for reducing print density shifts due to print wait time in thermal ink jet printers. The ink jet firing resistors of the printhead are driven with warming pulses having a pulse width insufficient to cause ink drop firing at the warming pulse frequency. They are driven for an interval that depends on the amount of time that has elapsed since printing by the printhead last occurred, or an interval that depends on the amount of decrease in the printhead temperature since printing stopped. In a particular embodiment of the printhead warming technique, the warming pulses have the same amplitude as the ink drop firing pulses, and a higher frequency.