Electrophotography – Image formation – Fixing
Reexamination Certificate
1998-04-28
2001-05-01
Royer, William J. (Department: 2852)
Electrophotography
Image formation
Fixing
C399S329000, C399S400000
Reexamination Certificate
active
06226488
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to fixing apparatuses of image forming apparatuses which form developed images on recording media by image forming processes, such as electrophotographic processes and electrostatic recording processes.
2. Description of the Related Art
Image forming apparatuses, such as electrophotographic copying machines, printers and facsimiles, include image forming means and heating means. The image forming means forms a developed image on a recording medium, such as an electrofacsimile sheet, an electrostatic recording sheet, a transfer sheet or printing paper, by a direct or indirect (transfer) method. The heating means fixes the developed image on the recording medium by heat and pressure.
A typical heating means which has been used in image forming apparatuses is a heating roller-type fixing apparatus, as shown in FIG.
12
. Such a fixing apparatus has a pair of rollers and heaters provided inside the rollers, and fixes a toner image on a recording medium by heat and pressure when it passes through the rotating rollers.
When a toner formed by a polymerization process (hereinafter referred to as a polymeric toner) is fixed in such a fixing apparatus, the toner having high flowability transferred on a recording medium will diffuse by the shock when a recording medium passes through the rollers. The resulting image will therefore be disordered.
Control of the glossiness of the image is generally performed by changing the transfer speed of the recording medium passing through the roller or by changing the temperature of the heaters. A glossy image requires a longer fixing time. Accordingly the transfer speed should be reduced to form a highly glossy image. When the glossiness is controlled by changing the temperature of the heaters, an idling time is required until the heaters reach a temperature which is desirable for the glossiness of the next image. Accordingly, a change in glossiness requires such an idling time before fixing the next image.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a fixing apparatus capable of preventing the formation of a disordered image caused by the shock of a recording medium when it is nipped between rollers.
Another object of the present invention is to provide a fixing apparatus capable of controlling the glossiness of an image without a change in fixing speed.
A further object of the present invention is to provide a fixing apparatus capable of controlling the glossiness of an image without changing the temperature of a heater.
A still further object of the present invention is to provide a fixing apparatus including a fixing member for forming a nip to transfer a recording member which has an unfixed toner on it, the toner being spherical, and a first heating unit provided upstream of the nip in the moving direction of the recording medium, the first heating unit not being in contact with the recording medium.
Another object of the present invention is to provide a fixing apparatus including a fixing member for forming a nip to transfer a recording member which has an unfixed toner on it, a first heating unit for heating the recording medium upstream of the nip in the moving direction of the recording medium, and a control means for controlling the heat given from the first heating unit to the recording medium.
Those objects together with others not specifically mentioned will become clear to those skilled in the art from the following description.
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Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Royer William J.
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