Electrophotography – Image formation – Fixing
Reexamination Certificate
2000-09-27
2001-09-25
Beatty, Robert (Department: 2852)
Electrophotography
Image formation
Fixing
C399S122000
Reexamination Certificate
active
06295436
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the installation of the lower skive plate in the fuser section of a electrophotographic copier/printer apparatus and in one of its aspects relates to an assembly for removing and replacing the lower skive plate of the fuser section of an electrophotographic apparatus whereby the assembly prevents the blades on the skive plate from cutting or digging into the pressure roller of the fuser section while the lower skive plate is being installed.
BACKGROUND OF THE INVENTION
In a typical electrophotographic machine (e.g. copier, duplicators, printers, etc.), a continuous loop of photoconductor film is commonly used to transfer an image from an input section onto a receiving medium (e.g. a sheet of paper). The film is initially charged and then passes through an input section where an image (i.e. analog or digital) is projected onto the charged film. The film then moves through a developing section where a toner is applied to the charged image, and on through an image transfer section where the image is transferred to the sheet of paper or other medium. The paper is subsequently passed through a fuser section where the toner forming the image is fixed to the paper by elevated temperature and pressure. This is typically accomplished by passing the paper between two, opposed rollers in the fuser section, i.e. a pressure roller and a fuser roller, one of which is heated.
In fuser sections such as described above, the nip between the pressure and fuser rollers is very tight. To insure that the paper will continue on through this gap and not stick to one of the rollers, “skive plates” (i.e. upper and lower skive plates) are normally provided to strip the paper off the rollers (i.e. fuser and pressure rollers, respectively) after the toner is fused onto the paper. Each plate carries a plurality of thin, extremely sharp “skives” (i.e. blades) (e.g. 0.004 inches thick) which effectively ride on its respective roller. These plates are rigidly mounted near the rollers at a precise location and angle to provide the proper stripping force without digging or gouging into the roller. As will be appreciated in this art, during assembly and service of the electrophotographic machine, the skive plates are frequently removed and then reinstalled. During this operation, the skive plate must be guided so that the sharp skives do not gouge the roller.
In known, prior art machines of this type, the installation of such skive plates present a number of problems to a service technician. First, there is nothing in the fuser section which prevents the skives from touching and possibly damaging the rollers during while the skive plate is being removed/installed. Further, there is no “fool-proof” procedure to be followed during the removal/installation of the skive plates. That is, the lower skive plate is not installed by a single straight, in-and-out movement but requires some manual adjustment before it is secured in its final operable position. A competent technician can be trained to follow the exact motions required to prevent contact between the skives and the roller but the possibility of human error is always present in operations of this type.
Still further, a cooling grill, which is used for cooling the paper as it comes off the rollers, is an integral part of the lower skive plate in prior art machines of this type and is coupled to the cooling air duct by a gasket which exerts a high frictional force on the underside of the lower skive plate. This frictional contact with the gasket makes it difficult to slide the lower skive plate smoothly out of and into its operable position.
Accordingly, those skilled in this art will recognize the need of simplifying the installation of the skive plates in the fuser section of an electrophotographic machine and making such installation effectively “fool-proof” to prevent the accidental gouging of the pressure and fuser rollers during the installation. Further, this fool-proof removal/installation procedure should be capable of being carried out by any trained technician without the need of special tools.
SUMMARY OF THE INVENTION
The present invention provides a fuser section for an electrophotographic apparatus which includes a lower skive plate which, in turn, can be easily and quickly installed in and removed from within the fuser section without the risk of accidentally damaging the fuser roller and the method for installing the skive plate in the fuser section. The lower skive plate has a plurality of skives (i.e. sharp blade-like elements) thereon which are designed to ride on a fuser roller in the fuser section and strip sheets of paper off the fuser roller as they pass thereover. Also, the skive plate has a forward and a rear latch pin on each side thereof.
To install the skive plate, the plate is positioned within the housing of the fuser section so that the plate is above the fuser roller in a substantially horizontal position. The forward latch pins are positioned into respective guide tracks of a guide assembly on the fuser section. Next, the skive plate is moved forward and downward (preferably at about a 45° angle) toward said fuser roller while keeping the plate in a relative horizontal position. This positioning keeps the skives clear of said fuser roller as the plate is being installed.
As the skives on the skive plate approach the fuser roller, the rear latch pins on said skive plate are latched to the fuser section by releasable, spring-biased rear detents therein. It is important that the rear pins are latched in the fuser section before the forward latch pins are latched which further insures that the technician installing the plate will not inadvertently tip the plate forward whereupon the sharp skives could contact and seriously damage the fuser roller. The front on the skive plate is then moved down through the remaining short distance to latch the forward latch pins in the releasable, spring-biased forward detents in the housing thereby securing said skive plate in said fuser section in its operable position with the skives now riding on said fuser roller. To remove the skive plate, the procedure is merely reversed. By releasing and raising the front of the skive plate first, the danger of the skives gouging into the fuser roller is eliminated.
Further, to simplify the installation and removal of the skive plate, the fuser section of present invention includes a cooling grill which is fixed within the housing adjacent the downstream side of the fuser roller. The present skive plate has a recess across a portion of the rear thereof which is adapted to lie over the cooling grill when the skive plate is in its operable position within the housing to thereby allow air from said cooling grill to flow through the skive plate to cool the sheets of paper as they pass over the skive plate. This eliminates the need for perforating a section of the skive plate and then frictionally coupling the plate to a source of cooling air which was required in known fuser sections of this type.
REFERENCES:
patent: 4475804 (1984-10-01), Kanno et al.
patent: 5532810 (1996-07-01), Cahill
patent: 5708946 (1998-01-01), Cahill et al.
Morganti Terry N.
Orchard, II James V.
Beatty Robert
Heidelberg Digital L.L.C.
Ngo Hoang
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