Sheet feeding or delivering – Feeding – With means to align sheet
Reexamination Certificate
1999-10-12
2001-06-05
Skaggs, H. Grant (Department: 3651)
Sheet feeding or delivering
Feeding
With means to align sheet
C271S250000, C271S272000
Reexamination Certificate
active
06241242
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to hard copy apparatus and, more specifically, to a method and apparatus for deskew of a fed sheet using spherical drive mechanisms with independent axial drives.
2. Description of Related Art
It is well known that a cut sheet piece of print media must be appropriately aligned to the associated printing mechanism if a true print of the data or a true copy of a document is to be successfully rendered. Problems associated with the variety of prior art mechanisms—such as spring-loaded side guides and canted rollers used to drive d sheet into and along a side wall—are exacerbated by the fact that it is difficult to tune a hard copy paper transport subsystem to work identically with a broad range of print media weights and sizes available to the end user. Spring-loaded side guides are sensitive to the parallelism of the side edges and the width of the sheet. Side guides do not give predictable alignment or edge position due to the inaccuracy of the paper cutting process. The edges of the sheet will generally not be perfectly parallel. As the side guides are attempting to align on both edges simultaneously, it is unpredictable which edges will end up dominating the alignment. For this same reason, the location of the edge of the sheet is unpredictable. The stiffness of the media being aligned will also vary and in some cases the force imparted by the side guides will cause the edge of the sheet to buckle. In addition to possibly damaging the sheet, this further reduces the predictability of the sheet position and orientation.
Canted rollers may slip on the sheet surface and cause damage to soft-coated media. Media type settings that work well for relatively lightweight media—e.q., plain paper-are often ineffective for relatively heavyweight media—e.g., card stock, letter size envelopes, and overhead transparencies. Settings that work for stiffer media frequently damage relatively flexible media.
There is a need for a deskewing system that works effectively over a broad range of media weights, sizes, and types.
[For convenience of description, print media of all shapes, sizes, and varieties are referred to hereinafter simply as “media,” “sheet,” or “paper” as best fits the context; no limitation on the scope of the invention is intended by the inventors, nor should any such limitation be implied.]
SUMMARY OF THE INVENTION
In its basic aspects, the present invention provides a print media deskew system for aligning print media to a hard copy producing mechanisms located downstream of the deskew system along a print media transport path. The system includes: guide mechanisms for supporting a print medium, including a base member having support surface for supporting a first surface of the print medium transported through the system, and adjacent the support surface, an abutment for abutting an edge of the print medium transported through the system and for aligning the print medium to the hard copy producing mechanisms, and at least two apertures through the support surface; and located proximate the base member, print medium feeder for transporting the print medium through the system. The feeder includes, located respectively to bridge each of the at least two apertures, at least two paired spherical members for sequentially receiving the print medium by a leading edge between each of the paired spherical members and simultaneously driving the print medium along the transport path
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across the support surface and driving the print medium laterally to the transport path across the support surface such that the edge of the print medium is driven against the abutment.
In another basic aspect, the present invention provides a method for aligning a sheet of print media in a transport path to a downstream printing station of a hard copy apparatus. The method includes the steps of: providing a fixed abutment having a substantially vertical wall in a plane parallel to the transport path; and driving the sheet along the transport path via spherical contact members contacting both sides of the sheet and imparting therewith both a force in the transport path toward the printing station and a force normal to the transport path such that an edge of the sheet is driven to and along the wall.
In another basic aspect, the present invention provides a print media deskew apparatus, including: a print media support having a first surface defining a plane for a print media transport path and a second surface parallel to the print media transport path and two apertures in the first surface aligned in the print media transport path; and a first set of selectively driven spheres in the print media ransport path and a second set of selectively driven spheres in the print media transport path downstream from the first set, each the set having a drive sphere and a pinch sphere mounted such that the drive sphere and the pinch sphere are in peripheral contact in the plane wherein a sheet of print medium is captured and driven between the drive sphere and the pinch sphere of the first set and second set sequentially as the sheet is transported along the print media transport path and wherein the driven spheres further impart a lateral driving force on the sheet such that the sheet is driven laterally to the print media transport path until edge contact with the second surface removes any skew from the sheet.
Some of the advantage of the present invention are:
it provides solutions to the problems inherent in the prior art;
it accommodates transport and alignment a range of print media sizes, preferably without requiring foreknowledge of the size;
it exerts enough force just to align a sheet, requiring no sliding contact with drive rollers; and
it can be implemented in an adjustable contact force embodiment.
The foregoing summary and list of advantages is not intended by the inventor to be an inclusive list of all the aspects, objects, advantages and features of the present invention nor should any limitation on the scope of the invention be implied therefrom. This Summary is provided in accordance with the mandate of 37 C.F.R. 1.73 and M.P.E.P. 608.01 (d) merely to apprize the public, and more especially those interested in the particular art to which the invention relates, of the nature of the invention in order to be of assistance in aiding ready understanding of the patent in future searches. Other objects, features and advantages of the present invention will become apparent upon consideration of the following explanation and the accompanying drawings, in which like reference designations represent like features throughout the drawings.
REFERENCES:
patent: 4836119 (1989-06-01), Siraco et al.
patent: 4909500 (1990-03-01), Grutzmacher et al.
patent: 5280903 (1994-01-01), Herrick
patent: 5449161 (1995-09-01), Cysling
patent: 5507478 (1996-04-01), Nottingham et al.
patent: 6053494 (2000-01-01), Baskette et al.
patent: 1154964 (1969-06-01), None
Hewlett--Packard Company
Skaggs H. Grant
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