Electrophotography – Image formation – Fixing
Reexamination Certificate
2000-03-09
2001-07-10
Grainger, Quana M. (Department: 2852)
Electrophotography
Image formation
Fixing
Reexamination Certificate
active
06259881
ABSTRACT:
This application is based on an application No. 11-72141 filed in Japan, the content of which is incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a paper guiding device, applied to an image forming apparatus for forming an image by an electrophotographic system, for guiding paper discharged from a fixing device for fixing a toner image transferred to the paper. More specifically, it is directed to a paper guiding device comprising a stripping claw so adapted that paper fed from a processing roller in a fixing device is not affixed to the processing roller, and relates to the construction and the like of the stripping claw.
2. Description of the Related Art
Examples of an image forming apparatus for forming an image by an electrophotographic system include a copying machine and a laser printer. The apparatus comprises a fixing device for fixing a toner image transferred to paper. The fixing device generally comprises a pair of rollers, that is, a heat roller and a pressure roller. The paper passes between the rollers, so that toner transferred to the paper is heated and is pressurized. Accordingly, the toner is melted, and the melted toner is fixed to the paper. Generally, the heat roller heats the toner in contact with the surface of the paper to which the toner has been transferred, and the pressure roller pressurizes the toner in contact with the reverse surface of the paper.
Many of the conventional image forming apparatuses are so constructed as to convey paper horizontally with respect to the fixing device. The toner has been transferred to the surface (the upper surface) of the paper horizontally conveyed. Consequently, the heat roller and the pressure roller are respectively arranged in upper and lower parts of the fixing device, and the paper horizontally passes between the rollers.
When the paper is jammed in the fixing device, a paper guide, for example, is made movable in order to release the jam.
In such conventional construction that the paper is horizontally conveyed, the pressure roller provided in the lower part of the fixing device, a stripping claw for preventing the paper from adhering to the pressure roller, and a lower guide for guiding the paper are generally fixed.
SUMMARY OF THE INVENTION
Some of recent image forming apparatuses are so constructed that paper is conveyed not horizontally but almost vertically upward from below with respect to a fixing device. In such construction that paper is conveyed perpendicularly with respect to the fixing device, a heat roller and a pressure roller are arranged in the horizontal direction. In this case, a paper guide provided on the side of the pressure roller must be made movable from the viewpoint of the facility of jam processing, unlike that in a case where the paper is horizontally conveyed.
In a case where the paper guide on the side of the pressure roller is made movable, when the paper guide is returned to a predetermined position after jam processing, a stripping claw projecting from the paper guide abuts against the surface of the pressure roller, so that the surface of the pressure roller may, in some cases, be damaged.
Such a problem should be solved even when not only the paper guide provided in the pressure roller but also a paper guiding device for guiding paper fed from the processing roller has a claw for stripping the paper from the processing roller.
The present invention has been made in order to solve such a problem, and has for its object to provide a paper guiding device so improved that the surface of a processing roller is prevented from being damaged upon abutment of a stripping claw for stripping paper from the processing roller against the surface of the processing roller when a paper guide is made movable in order to perform jam processing or the like.
The present invention is directed to a paper guiding device for guiding paper fed from a processing roller for processing the paper, which is characterized by comprising a paper guide, having a guide surface, for guiding the paper fed from the processing roller along the guide surface, a stripping claw provided in the paper guide, projecting from the guide surface, and having its front end brought into sliding contact with the surface of the processing roller, claw displacement means for displacing the stripping claw, such that the front end of the stripping claw separates from a position in contact with the surface of the processing roller, in synchronism with an operation for releasing the paper guide from the processing roller.
According to the above-mentioned construction, the stripping claw is displaced such that the front end of the stripping claw separates from the position in contact with the surface of the processing roller in synchronism with the operation of releasing the paper guide from the processing roller. In releasing the paper guide from the processing roller, therefore, the surface of the processing roller may not be damaged by the stripping claw.
The claw displacement means displaces the stripping claw to the position spaced apart from the surface of the processing roller until the paper guide is set in a predetermined position. When the paper guide is set, therefore, the stripping claw may not be pressed against the surface of the processing roller.
More specifically, the claw displacement means displaces, when the paper guide which is operated to be released is set, the stripping claw in the opposite direction to that in a case where the paper guide is operated to be released. After the paper guide is set, therefore, the stripping claw is also abutted against the surface of the processing roller. Accordingly, the surface of the processing roller may not be damaged by the front end of the stripping claw.
According to the present invention, the processing roller can be prevented from being damaged by the stripping claw, and the life of the processing roller can be lengthened. Further, the stripping claw can be displaced in synchronism with the operation of releasing the paper guiding device. In the paper guiding device, therefore, no problem arises in jam processing or the like, and the processing roller is not damaged by the stripping claw.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4806966 (1989-02-01), Suga
patent: 5448347 (1995-09-01), Mills
Grainger Quana M.
Kyocera Mita Corporation
Smith , Gambrell & Russell, LLP
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