Electrophotography – Image formation – Fixing
Reexamination Certificate
2002-10-28
2004-06-08
Royer, William J. (Department: 2852)
Electrophotography
Image formation
Fixing
Reexamination Certificate
active
06748191
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fixing unit that applies heat and pressure to a toner image, which has been transferred onto a print medium, so as to fix the toner image.
2. Description of the Related Art
A conventional fixing unit for use in an electrophotographic image recording apparatus includes a fixing roller that has a built-in heater and a pressure roller that rotates in pressure contact with the fixing roller. A toner image is transferred onto a print medium and is delivered to the fixing unit. The fixing roller and the pressure roller rotate in such a way that the print medium is sandwiched between the fixing roller and the pressure roller and is advanced forward. The print medium is positioned relative to the fixing roller so that the toner image directly faces the fixing roller and is heated under pressure to be fixed on the print medium permanently.
When the toner is fused, it acquires viscosity so that the print medium is apt to stick to the fixing roller. In order to ensure that the print medium separates from the fixing roller, a separator tongue is provided in an abutting relation with the fixing roller to strip the print medium from the fixing roller.
However, with the aforementioned conventional fixing unit, the separator tongue is in contact with the fixing roller and therefore may scratch the fixing roller. Also, toner that failed to be fixed may be deposited on the separator tongue and cause poor print quality. An area of the fixing roller in contact with the separator tongue may change in surface roughness, causing variations in gloss of printed images.
SUMMARY OF THE INVENTION
The present invention was made in view of the aforementioned problems.
An object of the invention is to provide a fixing unit in which a toner image deposited on a medium is fused by heat under pressure. The fixing unit includes a fixing member; and a separator plate that is disposed near the fixing member to extend in a direction transverse to a transport path through which the print medium travels.
The separator plate may have a mid portion that extends away from the transport path and a guide member that pushes the mid portion of the separator plate to prevent the separator plate from extending away from the transport path. The fixing unit may further include a member for absorbing thermal expansion of the separator plate.
REFERENCES:
patent: 6564030 (2003-05-01), Baughman et al.
Murakami Tatsuya
Sakai Masato
Sunaga Naoki
Yamamoto Tsutomu
Oki Data Corporation
Rabin & Berdo PC
Royer William J.
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