Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-04-10
2001-10-30
Nguyen, Thinh (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S029000
Reexamination Certificate
active
06309044
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates to ink-jet printing systems, and more particularly to a two-stage capping technique for capping the print head nozzles of an ink-jet pen when the pen is not printing.
BACKGROUND OF THE INVENTION
Pens used with ink-jet printing systems available today include print heads which have nozzle arrays with very small nozzles through which ink droplets are fired. The ink used with the pens typically dries quickly, permitting plain paper printing. Such pens are susceptible to nozzle clogging with dried ink or minute particles such as paper fibers.
Ink-jet printers have utilized a service station which includes a mechanism to cap the print head nozzles when the pen is not printing. Typically, the cap mechanism encloses the exposed outer surface of the orifice plate defining the nozzle array, to help prevent drying of the ink at the nozzles, and prevent contact with dust. The service station may also include a wiper mechanism for wiping away particles accumulated on the orifice plate, and a receptacle into which the pen periodically fires to purge dried or plugged nozzles.
In a multi-function office machine marketed by Hewlett-Packard Company as the 500 Series “OfficeJet,” the service station includes a sled to which are affixed rubber caps to serve the capping function. A motor driven rotating cam engages the sled, when the carriage is positioned at the service station, to lift the sled and its datum surfaces into engagement with the carriage. As the datum surface engage the corresponding carriage datum surfaces, the rubber caps are brought into engagement with the nozzle arrays of the print cartridges mounted in the carriage. This arrangement is a single stage capping mechanism.
This invention provides an improved two-stage capping technique for capping the nozzle arrays of an ink-jet printing system.
SUMMARY OF THE INVENTION
A service station is described for servicing an ink-jet printhead of an ink-jet printing system, the printhead having nozzles that selectively eject ink therethrough. The service station includes a sled structure, and an elevator mechanism coupled to the sled structure for moving the sled structure between a rest position and a sled capping position. A printhead cap is supported on the sled structure, and is movable relative to the sled structure for movement between a retracted position and a printhead capping position. The cap is adapted to surround and seal the printhead nozzles when the sled has been moved to the sled capping position and the printhead cap has been moved to the printhead capping position. In an exemplary embodiment, a piston is carried by the sled structure, and the printhead cap is mounted to the piston. An actuating mechanism moves the piston from a retracted position to an extended position, wherein the printhead cap is positioned at the printhead capping position when the piston is moved to the extended position.
The sled structure includes a set of sled datum structures adapted to mate with a corresponding set of datum features formed in a printhead carriage structure when the carriage structure is positioned at the service station as the sled structure is moved from the rest position to the sled capping position. The actuating mechanism is adapted to move the piston to the extended position after the sled structure has been moved from the rest position to the sled capping position.
In accordance with a further aspect of the invention, a two-stage capping method for capping ink-jet nozzles of an ink-jet printhead carried by a carriage of an ink-jet printing system, comprising the steps of:
positioning the carriage at a service station;
in a first stage, moving a sled structure from a rest position to a sled capping position;
in a second stage, moving a printhead cap carried by the sled structure from a retracted position to a printhead capping position, the cap adapted to surround and seal the printhead nozzles when the sled has been moved to the sled capping position and the printhead cap has been moved to the printhead capping position.
The first stage further includes, in a preferred embodiment, engaging a set of sled datum structures with a corresponding set of datum features formed in the carriage to accurately locate the sled structure relative to the carriage before the printhead cap contacts the printhead nozzles. The carriage is movable along a carriage scan axis, and the first stage can optionally further include incrementally moving the carriage back and forth along the carriage scan axis about a carriage service position while the sled datum structures are being engaged with the carriage datum structures to facilitate said engaging of the sled datum structures with the carriage datum structures.
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Hewlett--Packard Company
Hsieh Shih-Wen
Nguyen Thinh
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