Typewriting machines – Including adjustment for optimum printing plane – By adjustment of carriage
Reexamination Certificate
2001-10-30
2003-10-07
Hirshfeld, Andrew H. (Department: 2854)
Typewriting machines
Including adjustment for optimum printing plane
By adjustment of carriage
C400S354000, C400S703000, C400S055000, C347S008000
Reexamination Certificate
active
06629788
ABSTRACT:
TECHNICAL FIELD
The present invention relates to printers, and more particularly, to a method and apparatus for adjusting the anti-rotation rail in a printer to thereby adjust the printhead-carrying carriage relative to the platen in a printer which correspondingly adjusts the printhead-to-platen spacing.
BACKGROUND OF THE INVENTION
Inkjet printers typically include a carriage which holds printheads for ejecting ink onto media as the carriage reciprocates along a guide shaft above a platen. The platen provides a surface along which media, such as single-sheet paper or envelopes, are carried.
Conventional inkjet printers include a bearing rail, called an “anti-rotation rail,” which is mounted on a hanger in the printer, along which an arm of the carriage slides, as the carriage reciprocates along the guide shaft during a printing operation. The anti-rotation rail can be adjusted and fixed, to pivot the carriage, and correspondingly the printhead, relative to the guide shaft, which in turn sets the printhead-to-platen spacing. In the manufacture of printers, it is desirable to pre-set and fix the printhead-to-platen spacing to some nominal distance to ensure optimum print quality. A common practice is to use a measurement tool, such as a linear variable differential transducer (LVDT), by inserting it into the receptacle on a carriage which carries a printhead.
The tool includes a probe which extends downwardly and engages the platen, and a readout informs production or line personnel of the printhead-to-platen spacing. The practice heretofore has been to adjust the anti-rotation rail, which then adjusts the carriage and the printhead-to-platen spacing, to fix that spacing at some nominal amount, say 1.4 mm. This adjusting step is done with a pair of screws mounted on the anti-rotation rail, positioning of these screws being necessary to adjust the anti-rotation rail to a predetermined setting. The next step requires that additional screws, not part of the adjusting process, be used to fix the anti-rotation rail to the hanger. This method has several drawbacks, the first being that line personnel have difficulty keeping track of the multiple screws which can be misplaced. Importantly, a problem resides in the fixing of the anti-rotation rail, after adjustment, because the fixing or tightening can vary an adjustment which has just been made. Thus, the nominal spacing, as a printer unit leaves, may not be achieved. If screws are not properly affixed, vibration during shipping and handling can vary the printhead-to-platen spacing.
SUMMARY OF THE INVENTION
The present invention provides apparatus for adjusting and maintaining printhead-to-platen spacing in a printer, and a method for achieving the adjustment which contemplates that the anti-rotation rail is first clamped or fixed to the hanger, followed by the adjusting step where the nominal printhead-to-platen spacing is set. This is accomplished by using a combination clamp structure/adjuster mechanism in which the anti-rotation rail is first clamped to the hanger, and the adjuster mechanism, which includes a rotatable member, is operable for selectively shifting the anti-rotation rail vertically upwardly or downwardly to position and maintain the carriage, and correspondingly, the printhead at a preselected distance from the platen.
The clamp structure typically includes a pin member, such as a screw, which extends through the anti-rotation rail and engages a rotatable member operable for rotation to urge the pin member against the anti-rotation rail to shift the rail to a desired position. In the depicted embodiment, there are two clamp structure/adjuster mechanisms provided, one adjacent each end of the anti-rotation rail. The lateral spacing of the mechanisms ensures that during a production process, line personnel may efficiently and accurately pre-set nominal printhead-to-platen spacing at opposed ends of the carriage travel, thereby ensuring that any offset in the platen will be taken into account.
REFERENCES:
patent: 5065169 (1991-11-01), Vincent et al.
patent: 5078517 (1992-01-01), Hiroshi et al.
patent: 5468076 (1995-11-01), Hirano et al.
patent: 5692842 (1997-12-01), Sasai et al.
patent: 5975778 (1999-11-01), Kanemitsu
patent: 6406110 (2002-06-01), Ahne et al.
patent: 6450710 (2002-09-01), Foster et al.
patent: 6524021 (2003-02-01), Johnson et al.
patent: 6561606 (2003-05-01), Yoshida
patent: 6575543 (2003-06-01), Ahn
Close Shawn M.
Hsu Carol Chia-Sheng
Miranda Mark
Ghatt Dave A.
Hewlett--Packard Development Company, L.P.
Hirshfeld Andrew H.
LandOfFree
Method and apparatus for clamping and adjusting an... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for clamping and adjusting an..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for clamping and adjusting an... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3160543