Videojet Systems International, Inc.

Other

Colin R Sharpe

Robert I Keur

Michael E Stamer

An ink supply system for an ink jet printing device in which the elevation of the ink reservoir is controlled as a function of the elevation of the printhead orifices. In a preferred embodiment, the ink reservoir is mounted on an elevating carriage which is mechanically linked to the printhead via a Bowden.TM. cable. The cable cooperates with a pulley on the printhead such that rotation of the printhead results in translational movement of the elevating carriage. The dimensions of the pulley are selected such that the elevational changes in the reservoir ink level correspond directly with the elevational changes in the printhead orifices. Thus, the hydrostatic pressure head at the printhead orifices remains constant as the printhead is rotated from its home position to the priming position.

Apparatus for maintaining hydrostatic pressure in an ink jet printhead

The ink level sensor of the invention comprises an ink container having a generally cylindrical shield extending downward from its top to define shielded and unshielded compartments within the container. Ink, but not foam, froth or mist, flows under the shield to the shielded compartment. A plurality of conductive rods of differing length extend downwardly into the shielded compartment from the container top. The rods are connected to an impedance network which provides signals representative of the ink level inside the container. A vacuum source can be connected to each compartment to maintain pressure equilibrium in the compartments and to prevent foam, froth or mist from entering the shielded compartment. Alternatively, a return pump is used to force ink into the container such that each compartment can be vented to the atmosphere.

Liquid level sensor for ink jet printers

An element for a drop on demand ink jet printer employing a lever seal in a housing to control the frequency and quantity of ink delivered to a printing material such as paper.

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Chicago, IL, United States of America

Colin R Sharpe