Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-10-27
2001-08-14
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S029000, C347S033000
Reexamination Certificate
active
06273547
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the handling of waste ink accumulated in an ink jet printer system, and more particularly, to an apparatus for decreasing ink misting during a printhead nozzle purge operation.
2. Description of the Related Art
Ink jet printers require maintenance operations to keep the nozzles of the print cartridge operating properly. Such maintenance operations typically include the steps of wiping the nozzle area of the print cartridge, firing the nozzles at prescribed intervals to purge the nozzles (spitting), and capping the cartridge during idle periods to prevent the jetted ink which remains on the nozzle plate from drying and clogging one or more of the nozzles of the nozzle plate. Typically, the spitting operation occurs at a location in the maintenance station. Over a period of time, the solids in the waste ink accumulate in the maintenance station, and the resulting waste ink build-up can affect the operation of the maintenance assembly.
Ink jet printers have been plagued with the problem of ink mist from maintenance operations drifting around and landing on the print media which is being printed. The mist is generated when the printer stops periodically to clean and clear the printing nozzles by spitting ink. When the printer resumes printing on the print media, airborne mist from the maintenance operation is drawn by the carrier movement and drifts onto the paper. This results in a noticeable image defect on the paper, and tends to also contaminate other printer mechanisms.
One previous attempt to control and collect the mist ink is to perform the spitting operation on-page. Other printers have used fans and absorbent pads in attempts to collect and contain the mist ink. However, with the more prevalent use of higher non-volatile constituents in ink formulations, residual or waste ink build-up interferes with the operation of printing by contaminating the printheads. Furthermore, passive collection systems, such as pads and venturies, have limited effectiveness and limited capability to store non-volatile waste ink. Active systems, such as fans, can be effective, but are complex and expensive to implement.
Other attempts have included providing a rotating annular wheel for receiving waste ink discharged by an ink jet printhead which is driven by a rotary capping assembly which is rotated by a motor and gear or belt. Such a configuration, however, is not readily adaptable for use with sled-type maintenance assemblies, since such sled-type maintenance assemblies do not include a source of rotary motion. In addition, a curvature of the annular wheel is not uniformly spaced from the generally parallel columns of nozzles of the printhead, thereby limiting its effectiveness for waste ink mist recovery.
Accordingly, a need exists for a printing system which includes a simple and effective drive mechanism to provide rotary power to a sled-type maintenance assembly and provides improved waste ink mist recovery.
SUMMARY OF THE INVENTION
One aspect of the invention is a maintenance station for an ink jet printer which includes a frame. A device, such as for example a cylindrical drum, is rotatably coupled to the frame for collecting waste ink. A ratchet drive assembly is coupled to the frame for effecting rotation of the device.
In preferred embodiments of the invention, the ratchet drive assembly includes a ratchet gear coupled to the device, wherein the ratchet gear has a plurality of teeth. A distal end of a back-check member engages the teeth of the ratchet gear for effecting a rotation of the device in a first direction. The back-check member effects the rotation of the device in the first direction and prevents a rotation of the device in a direction opposite to the first direction. Also, preferably, rotation of the device is effected as the printhead cap is moved in a vertical direction.
Another aspect of the invention is a maintenance station for an ink jet printer having a carriage assembly for moving an ink jet printhead along a linear scanning path. The ink jet printhead includes a column of nozzles. The maintenance assembly includes a frame and a printhead capping assembly coupled to the frame. The printhead capping assembly has a printhead cap for engaging the printhead during a capping operation. The printhead capping assembly is located on the frame along the linear scanning path of the ink jet printhead. A cylindrical drum having a cylindrical surface is rotatably coupled to the frame and positioned adjacent the printhead capping assembly. The cylindrical drum is orientated such that an axis of rotation of the cylindrical drum is substantially perpendicular to the linear scanning path of the ink jet printhead. The orientation may also provide a substantially uniform spacing between the column of printhead nozzles and the cylindrical surface of the cylindrical drum.
Still another aspect of the invention is a printer for printing with an ink jet printhead. The printer includes a printer frame, and a carriage assembly coupled to the printer frame, wherein the carriage assembly moves the ink jet printhead along a linear scanning path. A maintenance assembly frame is coupled to the printer frame. A device, such as a cylindrical drum, is rotatably coupled to the maintenance frame for collecting waste ink ejected by said printhead. A ratchet drive assembly is coupled to the maintenance frame for effecting rotation of the device.
An advantage of the present invention is the inclusion of a rotatable cylindrical drum for controlling misting and a rotary drive therefor for use in a maintenance assembly having a maintenance sled which moves in a substantially linear motion.
Another advantage is that the rotatable cylindrical drum is oriented to provide a uniform spacing between the columns of printhead nozzles and a cylindrical surface of the cylindrical drum to thereby effectively control ink misting during a printhead nozzle purge operation.
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patent: 5614930 (1997-03-01), Osborne et al.
patent: 5617124 (1997-04-01), Taylor et al.
patent: 5712668 (1998-01-01), Osborne et al.
patent: 5742303 (1998-04-01), Taylor et al.
Aust Ronald K.
Daspit Jacqueline M.
Hsieh Shih-Wen
Le N.
Lexmark International Inc.
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