Electrophotography – Image formation – Fixing
Reexamination Certificate
2000-10-04
2002-10-08
Grainger, Quana M. (Department: 2852)
Electrophotography
Image formation
Fixing
C399S333000
Reexamination Certificate
active
06463250
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
Reference is made to the commonly assigned U.S. patent applications, the disclosures of which are incorporated herein by reference.
U.S. patent application Ser. No. 09/679,016, filed Oct. 4, 2000, in the names of Arun Chowdry et al, entitled DOUBLE-SLEEVED ELECTROSTATOGRAPHIC ROLLER AND METHOD OF USING.
U.S. patent application Ser. No. 09/679,113, filed Oct. 4, 2000,in the names of Robert Charlebois et al, entitled INTERMEDIATE TRANSFER MEMBER HAVING A STIFFENING LAYER AND METHOD OF USING.
U.S. patent application Ser. No. 09/679,177, filed Oct. 4, 2000,in the names of Muhammed Aslam et al, entitled SLEEVED ROLLERS FOR USE IN A FUSING STATION EMPLOYING AN INTERNALLY HEATED FUSER ROLLER.
U.S. patent application Ser. No. 09/680,133, filed Oct. 4, 2000,in the names of Arun Chowdry et al, entitled SLEEVED PHOTOCONDUCTIVE MEMBER AND METHOD OF MAKING.
U.S. patent application Ser. No. 09/680,134, filed Oct. 4, 2000,in the names of Muhammed Aslam et al, entitled SLEEVED ROLLERS FOR USE IN A FUSING STATION EMPLOYING AN EXTERNALLY HEATED FUSER ROLLER.
U.S. patent application Ser. No. 09/680,135, filed Oct. 4, 2000,in the names of Jiann-Hsing Chen et al, entitled TONER FUSING STATION HAVING AN INTERNALLY HEATED FUSER ROLLER.
U.S. patent application Ser. No. 09/680,136, filed Oct. 4, 2000,in the names of Arun Chowdry et al, entitled IMPROVED INTERMEDIATE TRANSFER MEMBER.
U.S. patent application Ser. No. 09/680,139, filed Oct. 4, 2000,in the names of Robert Charlebois et al, entitled INTERMEDIATE TRANSFER MEMBER WITH A REPLACEABLE SLEEVE AND METHOD OF USING SAME.
FIELD OF THE INVENTION
This invention generally relates to fusing stations and rollers used within electrostatographic imaging and, more particularly, to an externally heated fusing roller having a deformable structure for controlling overdrive and improving image quality.
BACKGROUND OF THE INVENTION
In electrostatographic imaging and recording processes such as electrophotographic reproduction, an electrostatic latent image is formed on a primary image-forming member such as a photoconductive surface and is developed with a thermoplastic toner powder to form a toner image. The toner image is thereafter transferred to a receiver, e.g., a sheet of paper, and the toner image is subsequently fused to the receiver in a fusing station using heat or pressure, or both heat and pressure. The fuser member can be a roller, belt, or any surface having a suitable shape for fixing thermoplastic toner powder to the receiver. The fusing step in a roller fuser commonly consists of passing the toned receiver between a pair of rollers that are engaged to produce an area of contact pressure known as a fusing nip. In order to form the nip, at least one of the rollers typically has a compliant, or conformable, layer on its surface. Heat is transferred from at least one of the rollers to the toner in the fusing nip, causing the toner to partially melt and attach to the receiver. In the case where the fuser member is a heated roller, a resilient layer having a smooth surface is typically used which is bonded either directly or indirectly to the core of the roller. Where the fuser member is in the form of a belt (as described herein a belt refers to a flexible endless belt that passes around the heated roller) it typically has a smooth, hardened outer surface.
Most roller fusers are of a type known as simplex fusers that function to attach toner to only one side of the receiver at a time. In a simplex fuser, the roller that contacts the unfused toner is commonly known as the fuser roller and is usually heated. The roller that contacts the other side of the receiver is known as the pressure roller and is usually unheated. Either, or both, of the rollers can have a compliant layer on, or near, the surface. In most fusing stations employing a fuser roller and an engaged pressure roller, it is common for only one of the two rollers to be driven rotatably by an external source. The other roller is then driven rotatably by frictional contact.
Another less common roller fuser embodiment known within the prior art, is a duplex fusing station, which has two toner images that are simultaneously attached to each side of a receiver passing through a fusing nip. In such a duplex fusing station there is no real distinction between fuser roller and pressure roller with both rollers perform similar functions in providing heat and pressure.
Two basic types of simplex heated roller fusers have evolved. The first uses a deformable pressure roller to form the fusing nip against a hard fuser roller, such as in a Docutech 135 machine made by the Xerox® corporation. The second uses a deformable fuser roller to form the nip against a hard or relatively non-deformable pressure roller, such as in a Digimaster 9110 machine made by Heidelberg Digital LLC®. A deformable fuser roller as designated, herein, typically includes a conformable or a compliant layer having a thickness greater than about 2 mm and in some cases exceeding 25 mm. A hard fuser roller as designated herein, typically includes a rigid cylinder which can have a relatively thin polymeric, or conformable, elastomeric coating that is typically less than about 1.25 mm thick. A deformable fuser roller used in conjunction with a hard pressure roller tends to provide easier release of a receiver from the heated fuser roller, because the distorted shape of the deformable surface in the nip tends to bend the receiver towards the relatively non-deformable pressure roller and away from the much more deformable fuser roller.
Conventional toner fuser rollers typically have a cylindrical core member (which is often metallic such as aluminum) coated with one or more synthetic layers (which typically include polymeric materials made from elastomers).
The most common type of fuser roller is one that is internally heated, which means that a source of heat is provided inside the roller to generate the heat required for fusing. Such a fuser roller normally has a hollow core, inside of which is located a heating source, usually a lamp. Surrounding the core is an elastomeric layer through which heat is conducted from the core to the surface, and the elastomeric layer typically contains fillers for enhanced thermal conductivity.
Another type of fuser roller is referred to as an externally heated fuser roller is heated by surface contact between the fuser roller and one or more heating rollers. An example of an externally heated fuser roller is the Image Source 120 copier marketed by Eastman Kodak Company®. Externally heated fuser rollers are also disclosed by U.S. Pat. No. 5,450,183 issued to O'Leary and in U.S. Pat. No. 4,984,027 issued to Derimiggio et al.
A deformable fuser roller can include a compliant or conformable layer of any useful material, such as for example a substantially incompressible elastomer (those having a Poisson's ratio approaching 0.5). Such a substantially incompressible compliant layer including a poly(dimethyl siloxane) elastomer has been disclosed by Chen et al., in U.S. patent application Ser. No. 08/879,896 which is hereby incorporated by reference. Alternatively, a conformable layer can include a relatively compressible foam having a value of Poisson's ratio much lower than 0.5. A conformable polyimide foam layer is disclosed by Lee in U.S. Pat. No. 4,791,275. A lithographic printing blanket is disclosed by Goosen et al. in U.S. Pat. No. 3,983,287, illustrating a conformable layer containing a vast number of frangible, rigid-walled tiny bubbles which are mechanically ruptured to produce a closed cell foam having a smooth surface.
Receivers remove the majority of heat during fusing. Since receivers that have a narrower width than the fuser roller width, can have heat removed differentially, causing areas of higher temperature or lower temperature along the fuser roller surface parallel to the roller axis. Higher or lower temperatures can cause excessive toner offset in roller fusers.
Improved heat transfer to the surface of an externally heated fuser roll
Chen Jiann-Hsing
Chowdry Arun
May John W.
Mills Borden H.
Quesnel David
Grainger Quana M.
Leimbach James D.
Nexpress Solutions LLC
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