Electrophotography – Image formation – Fixing
Reexamination Certificate
2002-09-13
2003-12-23
Pendegrass, Joan (Department: 2852)
Electrophotography
Image formation
Fixing
C219S216000, C430S124300, C492S030000
Reexamination Certificate
active
06668152
ABSTRACT:
FIELD OF THE DISCLOSURE
The present disclosure relates to fusing toner to print media. More particularly, the disclosure relates to a fuser roller having a textured surface and a method for texturing toner to mask toner gloss differential.
BACKGROUND
Electrophotographic imaging devices such as printers and photocopiers typically are provided with fusing systems that thermally fuse a toner image onto a print media, such as sheets of paper. Such fusing systems normally comprise a heated fuser roller and a pressure roller that presses against the fuser roller to form a nip in which the fusing occurs. The fuser and pressure rollers typically comprise hollow metal tubes that are surrounded with outer lavers of material.
High-end electrophotographic imaging devices normally include fusing systems in which one or more of the rollers are surrounded with an outer layer composed of a heat resistant, highly compliant material. such as silicon rubber. In that such fusing systems are relatively expensive, lower-end electrophotographic imaging devices typically include fusing systems that use less expensive materials. For example, such devices may comprise fusing systems in which one or both of the rollers are surrounded with a relatively inelastic polymeric material, such as a polyester material (e.g., mylar).
Although such materials are resistant to heat, they are less effective in terms of facilitating fusing of toner to print media. As is known in the art, most print media are non-uniform across their outer surfaces. For example, sheets of paper normally include depressions and high points that result from the fibers contained within the paper and the process used to form the sheets. When such print media pass through the nip of a fusing system, the toner particles within the depressions receive less pressure and, therefore, may not fully fuse to the media. Incomplete fusing results in relatively glossy and non-glossy (i.e., matte) portions of toner on the print media. In other words, a gloss differential is formed across the toner printed on the media.
Substantial gloss differential is undesirable from an aesthetics perspective. In particular, when light reflects off of the toner and into the eyes of the observer, the non-uniformity of the toner can be obvious and detract from the print or photo copy job. This is particularly the case where an image has been printed or copied in that more toner covers the media.
Although gloss differential can be reduced by using more compliant materials for the roller outer layers, as noted above the materials may be too expensive for inclusion in lower-end devices. More even fusing could, at least theoretically speaking, be obtained if greater pressure were used to squeeze the print media as the media pass through the nip. Practically speaking, however, there are limitations as to how firmly the rollers can be pressed together without causing undue flexion of the rollers, which ultimately could result in even less uniform pressure being applied to the media.
From the foregoing, it can be appreciated that it would be desirable to have a fusing system with which gloss differential can be masked so as to improve the aesthetics of print or photocopy jobs output from imaging devices having relatively noncompliant fusing system rollers.
SUMMARY
Accordingly, one embodiment of the invention is directed to a fuser roller having a textured outer surface. The textured outer surface can be used to produce a textured appearance on toner as it is fused to print media. Another embodiment of the invention is directed to a method that includes texturing the toner as it is fused to the print media. Texturing the toner helps mask gloss differential.
REFERENCES:
patent: 4363862 (1982-12-01), Giorgini
patent: 5649273 (1997-07-01), Shimizu et al.
patent: 5753348 (1998-05-01), Hatakeyama et al.
patent: 6144819 (2000-11-01), Nishiuwatoko
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