Sheet feeding or delivering – Feeding – Separators
Reexamination Certificate
2000-05-23
2001-04-03
Bollinger, David H (Department: 3651)
Sheet feeding or delivering
Feeding
Separators
C271S117000, C271S118000
Reexamination Certificate
active
06209862
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to print media feeding for hard copy printing and plotting apparatus and, more particularly, to a cut-sheet, print medium, pick and feed mechanisms.
2. Description of Related Art
Many office products such as computer printers and plotters, plain paper facsimile machines, and photocopiers use mechanisms that pick a sheet of paper from a stack of media in an input tray and feed a single sheet of pre-cut printing medium (for example, a sheet of paper of a particular size such as standard letter size, legal size, or A4 (metric), or transparencies, or envelopes) into the hard copy producing apparatus. These mechanisms are generically referred to as “sheet feeders.”
Sheet feeders usually are provided with an adjustable or replaceable media cartridge, tray, or other type of stacker in which a user can stack multiple cut-sheets of the media of choice. The use of media cartridges (essentially easily substituted paper trays) adapted to the various styles of media provide a mechanism for quick changes between any particular printing medium by the user. Upon receiving a media feed command (“FEED”) from the hard copy machine controller electronics, a sheet picking device is actuated to deliver the top sheet from the stack into the hard copy machine. Under proper operating conditions, a sheet picking mechanism associated with the stacker should deliver a single sheet of the print medium to the hard copy machine input mechanism, such as a set of pinch rollers used for registration and feed into the actual printing subsystem of the machine.
Misfeeds, multiple sheet feeds, paper jams, and the like are common problems associated with sheet feeders.
FIGS. 1 and 1A
depict a typical problem of a misfeed caused by a premature bending (“wrap” or “wrap-back”) of a picked sheet before its leading edge can be captured by an input mechanism (not shown; generally located close to the exit plane of the leading edge of a picked sheet) used to transport the sheet to a printing station.
FIG. 1
shows a normal feed of a sheet
100
from a stack
101
of sheets in an input bin
102
by a pick mechanism
103
having a feed arm
104
and a motorized pick roller
105
. In
FIG. 1
the sheet
100
is being properly fed up the input tray angled wall
106
. The details of a stack loader located below a hard copy apparatus' printing mechanisms are shown in U.S. Pat. No. 5,507,478 by Nottingham et al. for PRINTING MEDIA STATUS SENSING, assigned to the common assignee herein and incorporated herein by reference.
FIG. 1A
shows a misfeed in which the picked sheet
100
has wrapped around the pick mechanism
103
before properly exiting the bin and being received by the input feed mechanism. High humidity tends to exacerbate such a problem. Thin media or media that has any inherent curl in it is highly susceptible to the problem.
One solution to the problem is to flatten out the feed angle. U. S. Pat. No. 5,876,133 by Kleln et al. for a SHEET PRESENTER AND METHOD OF USING SAME has an elongated platform adapted to engage a printer. A pair of spaced walls extend upwardly from the platform to support pivotally an arm at one end thereof. A motor disposed at another end of the arm is operatively connected to a drive roller wherein the mass of the motor urges the corresponding end of the arm downwardly to engage a sheet. This however requires a much larger workspace footprint than a printer having a contained input tray located below the printing zone such as illustrated by
FIGS. 1 and 1A
and preferable in the marketplace.
Another solution is to provide a paper guide fixed to a pivotal feed arm
104
. However, such paper guides move with the arm. When the rollers of the feed arm are on a full stack, the paper guides protrude above the highest level of the feed arm, requiring extra height in the media bin to accommodate them. If the guides are made to be very short to minimize the amount that they protrude above the feed arm's highest position, they will not be effective when the paper stack is low and the feed arm pivoted into a more vertical than horizontal orientation. The picked sheet of a low stack will tend even more to wrap around the feed arm before reaching the top of the wall
106
where it can be captured by transport rollers.
Therefore, there is a need to facilitate the transfer of a sheet of print media from an internal input supply stack to a hard copy machine's printing zone.
SUMMARY OF THE INVENTION
In its basic aspects, the present invention provides guide device for a cut-sheet print media stack bin having a sheet egress guide wall associated with a pick mechanism, including: fixedly mounted substantially parallel to sheets stacked in said bin, a member having a reach such that a guiding end is substantially proximate an exit extremity of the guide wall; and a biased flexible guide attached to said member at a position distal of said guiding end, wrapped about said reach, and attached to said pick mechanism wherein moving said pick mechanism extends and retracts said flexible guide such that said flexible guide between said reach and said pick mechanism provides an anti-wrap barrier to the sheets during egress from said bin.
In another basic aspect, the present invention provides a method for preventing wrap of a picked cut-sheet of paper about a stack-following pick mechanism in an input bin, including the steps of: mounting a flexible member in fixed relationship to said bin and coupled to said pick mechanism; and moving a surface of the flexible member in coordination with said pick mechanism to form a closed exit path from said bin.
In another basic aspect, the present invention provides a print media anti-wrap device including: coupled to a pick device in a paper supply, a mechanism for maintaining a closed print media egress path configuration such that a leading edge of exiting paper is guided out of the supply and prevented from wrapping back onto the pick device.
Some of the advantages of the present invention are:
it provides a mechanism for preventing wrapping of a picked sheet of print media in an input bin; and
it does not increase the height of the input bin.
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 apprise 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: 5276469 (1994-01-01), Beaufort et al.
patent: 5300160 (1994-04-01), Wilson et al.
patent: 5507478 (1996-04-01), Nottingham et al.
patent: 5516011 (1996-05-01), Fielding
patent: 5622364 (1997-04-01), Dutton et al.
patent: 5876133 (1999-03-01), Klein et al.
patent: 5932313 (1999-08-01), Barton
Bollinger David H
Hewlett--Packard Company
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