Electrophotography – Image formation – Fixing
Reexamination Certificate
1999-09-21
2001-10-02
Royer, William J. (Department: 2852)
Electrophotography
Image formation
Fixing
C399S333000
Reexamination Certificate
active
06298216
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a new type of fusing roller for use in high speed web printers.
BACKGROUND OF THE INVENTION
Developed toner images in electrostatographic processes can be transferred and fused to another substrate such as paper. Transfer of the toner image can be accomplished by electrostatic methods, pressure contact, or other means. Once transferred, the toner image can be fused or fixed to the paper. The fusing step commonly consists of passing the paper on which toner powder is distributed in an imagewise pattern, through the nip of a pair of rolls, at least one of which is heated. The heated roller is often referred to as a fusing roller.
Toner fusing rollers have a cylindrical core which may contain a heat source in its interior, and a resilient covering layer formed directly or indirectly on the surface of the core. Roller coverings are commonly fluorocarbon polymers or silicone polymers, such as poly(dimethylsiloxane) polymers, of low surface energy which minimizes adherence of toner to the roller.
One persistent problem in this operation is that when the toner is heated during contact with the fusing roller, it may adhere not only to the paper but also to the fusing member. Any toner remaining adhered to the member can cause a false offset image to appear on the next sheet and can also degrade the fusing roller. Any toner or dirt stuck to the roller should be easily removable.
In the past, fusing rollers often had to be cleaned several times before their useful life ran out. This meant that printing time was wasted while somebody physically opened the machine and wiped down the fusing roller. In the case of the high-speed reel paper printers like the one we have described below, the fusing rollers had to be cleaned once every 25,000 copies. This meant that every 2 days or so, the printers had to be opened and the fusing rollers cleaned.
Frequently release oils composed of, for example, poly(dimethylsiloxanes), are also applied to the roller surface to prevent adherence of toner to the roller. Such release oils may interact with the roller surface upon repeated use and in time cause swelling, softening and degradation of the roller. Silicone rubber covering layers which are insufficiently resistant to release oils and cleaning solvents are also susceptible to delamination of the roller cover after repeated heating and cooling cycles. For the high speed printers, every 2 weeks or so the fusing roller needed to be replaced. This also cost more time and money.
SUMMARY OF THE INVENTION
The object of the invention is design for, and a method of using an electrophotographic printer for reel paper that utilizes a new type of fusing roller that has a lifetime of 2 million copies and is self-cleaning. The fusing rollers as used in the printer has needed little to no cleaning, and had experimental lifetimes of up to 2.4 million pages.
It should be noted that these thicknesses were for printer speeds of between 120 and 500 pages of A4 paper per minute. At slower speeds, thicker outer layers should be considered.
These objects of the invention are achieved with an electrophotographic printer for reel paper having: a print transfer station with integrated paper transport device for transferring onto the reel paper a toner image which is produced on an intermediate carrier and inked; an electrothermal fixing station, which is arranged downstream of the print transfer station in the transport direction of the paper, for the toner image with an electrically heated fusing roller driven by an electric motor, a feed roller which can be pivoted onto and away from the fusing roller in a fixing area and an unheated paper guide saddle which can be pivoted onto and away from the fusing roller and by means of which the reel paper is guided around the fusing roller at a wrapping angle which can be predetermined by the pivot position of the paper guide saddle for the purpose of preheating before the actual fixing; and a paper brake which is mounted upstream of the fixing station in the transport direction of the paper for making the reel paper taut, as required, between the fixing area and paper guide saddle.
The fusing roller used in this printer offers a much better toner release than prior fusing rolls. This is true in part because of the softness of the roller. The softness of the outer layer is a result of the hardness of the rubber and the thickness of the coating surrounding the core. This coating is comprised of the base cushion layer and the wearable outer release layer. The thicknesses that we found suitable for the coating ranged between 300 &mgr;m and 600 &mgr;m, with a thickness of 500 &mgr;m optimally. To further optimize the superior functionality of this coating, this coating is divided equally between base layer and surface layer
The present invention relates to use of a new fusing roller design in image transferring devices such as printers and copiers. In particular, devices similar to those covered by patents U.S. Pat. Nos. 5,839,038 and 5,568,241. The disclosures of these patents are hereby incorporated by reference to the present disclosure.
The present invention is a copier with a new fusing roller that has a much longer lifetime than those in the prior art. The fusing roller is also self-cleaning. This roller works particularly well in OPS's web printer. The printer it is used in allows the web of paper to pull itself off the fusing roller upon exit. The toner is presoftened prior to entering the fuser nip and then the web pulls itself off the fusing roller.
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Goretzky Michael
Loedermann Gerhard
McMindes Michael
Montgomery James
Stypa Eric
Harter Secrest & Emery LLP
Royer William J.
Salai Esq. Stephen B.
Shaw Esq. Brian B.
Ten Cate Enbi, Inc.
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