Typewriting machines – Including adjustment for optimum printing plane – By adjustment of carriage
Reexamination Certificate
2000-01-19
2001-11-13
Eickholt, Eugene (Department: 2853)
Typewriting machines
Including adjustment for optimum printing plane
By adjustment of carriage
C347S008000, C400S703000, C033S483000, C033S732000, C033S501090
Reexamination Certificate
active
06315469
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an ink jet printer, and in particular to a tool and a method for calibrating the height of a space between a printhead and a platen in an ink jet printer.
BACKGROUND OF THE INVENTION
Ink jet printers typically include a plurality of printheads supported in a moveable carriage. A platen is spaced from the printheads and supports the print media during the printing operation. A typical minimum distance between the printheads and the platen is 1.20 mm. This distance must be constant, within a tolerance, along the entire printing path of the printhead to obtain uniform printing.
Certain maintenance procedures for ink jet printers, such as carriage replacement or platen replacement, require that the printhead to platen distance be calibrated. A conventional method of calibrating the printhead to platen distance is to insert a block gauge between the platen and a part of the carriage. This method has several disadvantages. First, use of the block gauge requires that there be an accessible area for insertion of the block gauge beneath the carriage. Second, the block gauge necessarily will be displaced from the printheads, and thus there is no assurance that the spacing at the printheads will be the same as the spacing where the block gauge was inserted. Third, the technician holding the block gauge may hold the gauge at an improper angle, and thus cause errors in the calibration process. Finally, a block gauge requires that the technician feel when the gauge seizes, which also can introduce errors given the cramped area in which the tool is inserted.
Thus, there is a need for a more accurate and easier to use tool and method for calibrating the printhead to platen spacing in an ink jet printer.
SUMMARY OF THE INVENTION
The present invention improves on conventional tools and methods for calibrating the height of the space between a printhead, in a print cartridge, and the platen in an ink jet printer. A tool, in accordance with one embodiment of the present invention, has a body that mimics the shape of a print cartridge. The tool is inserted into an aperture in the carriage in the place of a print cartridge. The tool includes a member extending from the body of the tool. When the tool is inserted into the aperture, the member extends toward the platen. The length of the member is such that, when it touches the platen, the spacing between a printhead in the same aperture and the platen would be the minimum acceptable spacing for that area of the platen.
A method of calibrating the space between the printhead and the platen includes inserting the tool into an aperture in the carriage where the print cartridge normally is held during printing. The member of the tool extends toward the platen. Next, the member is made to contact the platen, if it is not initially contacting the platen, by adjusting the carriage height. Once contact is made, the carriage gradually is raised relative to the platen so that the member is as close as possible to the platen without touching. The position of the carriage relative to the platen is checked and adjusted over the entire length of the printing path by moving the carriage along the platen and listening for sound and/or watching for flexure indicative of contact between the tool's extended member and the platen. If contact is detected, the carriage is raised just enough to eliminate the contact.
These and other objects, features and advantages of the present invention will be more readily apparent from the figures and the detailed description of the exemplary embodiments set forth below.
REFERENCES:
patent: 4607967 (1986-08-01), Hirata et al.
patent: 4720200 (1988-01-01), Gomoll et al.
patent: 5774139 (1998-06-01), Salzer et al.
patent: 6027264 (2000-02-01), Maher et al.
Alvarez Jose Antonio
Angulo Emilio
Ramaswamy Rajan
Eickholt Eugene
Hewlett--Packard Company
Ogonowsky Brian D.
Parsons James E.
Skjerven Morrill & MacPherson LLP
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