Electrophotography – Diagnostics – Document handling
Reexamination Certificate
2001-12-20
2003-10-28
Royer, William J. (Department: 2852)
Electrophotography
Diagnostics
Document handling
C399S022000, C399S124000, C399S322000
Reexamination Certificate
active
06640059
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to printing apparatus, in particular to clearance of jammed sheets as could be found in the post-fuser path of a xerographic printer or copier.
BACKGROUND OF THE INVENTION
In electrophotographic printers commonly in use today, a charge-retentive member is charged to a uniform potential and thereafter exposed to a light image of an original document to be reproduced. The exposure discharges the charge-retentive surface in exposed or background areas and creates an electrostatic latent image on the member which corresponds to the image areas contained within the original document. Subsequently, the electrostatic latent image on the charge-retentive surface is made visible by developing the image with developing powder referred to in the art as toner. Most development systems employ a developer material which comprises both charged carrier particles and charged toner particles which triboelectrically adhere to the carrier particles. During development the toner particles are attracted from the carrier particles by the charge pattern of the image areas on the charge-retentive member to form a powder image on a photoconductive area. This image is subsequently transferred to a support surface, such as copy paper, to which it is permanently affixed by heating or by the application of pressure. Following transfer of the toner image to a support surface, the charge-retentive member is cleaned of any residual toner that may remain thereon in preparation for the next imaging cycle.
One approach to fixing, or “fusing,” the toner image is applying heat and pressure by passing the copy paper or print sheet containing the unfused toner images between a pair of opposed roller members at least one of which is internally heated. During this procedure, the temperature of the toner material is elevated to a temperature at which the toner material coalesces and becomes tacky. This heating causes the toner to flow to some extent into the fibers or pores of the sheet. Thereafter, as the toner material cools, solidification of the toner material causes the toner material to become bonded to the sheet.
After the fusing step, it is common that the resulting output sheet be fed to a subsequent processing station, such as an inverter, collator, stapler, booklet maker and the like. In order to direct a sheet emerging from the fuser rolls to the next processing station, it is common that the volume of space immediately downstream of the fuser in the process direction, which can be called the “post-fuser path” be effectively shaped in a funnel configuration, so that a sheet passing through the post-fuser path is directed toward a fairly narrow opening, such as toward a stapler.
FIG. 1
is an elevational view of some basic elements of an electrostatographic printer, illustrating a practical problem addressed by the present invention. Blank sheets are drawn one at a time from a supply stack
100
and conveyed, by known means, through a paper path
102
along a process direction P. At a charge-retentive surface such as on photoreceptor
104
, marking material forming an image is electrostatically transferred to each sheet by one or more corotrons
106
or equivalent devices. Following transfer, the sheet is sent through fuser rolls
108
and
110
. After fusing, the sheet can be sent on for further processing, such as stapling or binding.
Following the fuser along process direction P, it is typical that the sheets pass through the post-fuser path which is of a general funnel shape, such as formed by surfaces of baffles
10
and
12
, whereby the vertical width of the path decreases to a relatively narrow slot
14
, through which the sheet can be directed to a subsequent processing station.
As can be seen in
FIG. 1
, a problem can occur if the subsequent processing station following slot
14
is unable to accept input of a sheet, such as if the station is malfunctioning. If a sheet S cannot be accepted through slot
14
and is nonetheless pushed forward by the motion of fuser rolls
108
,
110
, the sheet S will jam and be compacted between surfaces formed by baffles
10
and
12
. The funnel-like surfaces of the baffles
10
,
12
tend to exacerbate a jamming problem, because the shape causes a very compact accordion-folding of the moving sheet. The post-fuser path will fill up quickly with one or more sheets, and the compaction of sheets is liable to damage the hardware around baffles
10
and
12
.
The present invention is directed toward avoiding and obviating damage that can be caused in a post-fuser path in a printing apparatus, or indeed any post-roller path in any apparatus which feeds sheet material.
DESCRIPTION OF THE PRIOR ART
U.S. Pat. No. 5,245,395 discloses a fusing apparatus wherein a baffle associated with stripper fingers on an exit side of the apparatus imparts an arcuate profile on sheets emerging from the apparatus; this tends to prevent longitudinal waves from forming in the sheet.
U.S. Pat. No. 5,822,668 discloses a fusing apparatus which pivots open on its exit side for jam clearance. Various stripper fingers and plates are mounted on the pivoting exit side of the apparatus.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is provided an apparatus useful in moving sheets, comprising a first roller and a second roller, forming a nip therebetween; means defining a substantially enclosed post-roller path downstream of the nip along a process direction toward an output opening; and opening means for increasing a size of the post-roller path.
REFERENCES:
patent: 4497569 (1985-02-01), Booth, Sr.
patent: 5245395 (1993-09-01), Pawlik et al.
patent: 5822668 (1998-10-01), Fromm et al.
patent: 5839032 (1998-11-01), Yasui et al.
patent: 6236824 (2001-05-01), Pardubitzki
patent: 6393246 (2002-05-01), Tsujihara
patent: 0 278 237 (1988-08-01), None
patent: 0 870 707 (1998-10-01), None
patent: 62-102266 (1987-05-01), None
patent: 63-87464 (1988-04-01), None
European Search Report.
Benton Richard C.
Fromm Paul M.
Hutter R.
Royer William J.
Xerox Corporation
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