Electrophotography – Image formation – Fixing
Reexamination Certificate
2000-01-21
2001-05-01
Grimley, Arthur T. (Department: 2852)
Electrophotography
Image formation
Fixing
C015S001510, C399S071000
Reexamination Certificate
active
06226489
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to a fixing device for fixing toner images onto a receiving material, and to a method of removing debris from the surface of an endless fixing member of such a fixing device.
BACKGROUND OF THE INVENTION
In an electronic printer, where toner particles are deposited on a surface in image form and are subsequently transferred to a receiving material, such as paper, the toner particles must be fixed onto the receiving material in order to render the images permanent. This fixing process is often achieved by a combination of heat and pressure applied in a fixing nip. For example, the receiving material onto which unfixed toner particles have already been deposited, is passed through the fixing nip where an increased temperature and pressure serve to fix the image permanently to the receiving material. Alternatively, a transfer surface carrying the unfixed toner particles is fed through the fixing nip together with the receiving material, whereby the increased temperature and pressure cause the transfer of the toner particles from the transfer surface to the receiving material and the simultaneous fixing of the toner image thereon.
In such devices, especially where the receiving material is formed of paper or a like fibrous material, debris in the form of dust and fibers can build up in the region of the fixing nip. If this debris remains, the quality of fixing, and the efficiency of the image transfer where applicable, can be affected.
A fixing device is known, for example from European patent specification EP 149860 (Océ-Nederland BV) for fixing toner images onto a receiving material. The device comprises a fixing roller urged into contact with a pressure roller to form a fixing nip therebetween through which a copy sheet passes. A perforated cleaning roller is in contact with the surface of the fixing roller to remove debris therefrom. Toner particles are applied to the cleaning member to render the surface tacky.
In a fixing device described in United States patent U.S. Pat. No. 4,018,555 (Thettu/Xerox Corporation), a fuser roll is urged into contact with a backup roll to form a fixing nip therebetween through which copy paper or substrate material passes. An internally heated cleaning roll having a tacky surface is positioned in contact with the surface of the fixing roll to remove debris therefrom. The cleaning roll can be rejuvenated by the application thereto of a tacky polymeric adhesive.
U.S. Pat. No. 4,705,388 (Huntjens et al/Océ-Nederland BV) describes a method and device for determining the moment that a layer of tacky material on an internally heated cleaning roll needs to be rejuvenated.
We have found that the above mentioned fixing devices are not as successful at removing debris from the fixing nip as may be desired for high quality work. Thus it is an objective of the present invention to provide a device and method in which an improved removal of debris is possible.
SUMMARY OF THE INVENTION
We have discovered that this objective, and other useful advantages, can be obtained by heating the toner particles on the cleaning member surface with a controllable radiant heating device to render the surface tacky prior to contact of the cleaning member surface with the fixing member surface.
Thus, according to a first aspect of the invention, there is provided a fixing device for fixing toner images onto a receiving material, the device comprising an endless fixing member urged into contact with an endless counter member to form a fixing nip therebetween through which a receiving material path extends, a cleaning member having a tacky surface in contact with the surface of the fixing member to remove debris therefrom, means for applying polymer material particles to the cleaning member to render the surface tacky, and a controllable radiant heating device positioned adjacent the cleaning member surface for heating the polymer material particles on the cleaning member surface to render the surface tacky prior to contact of the cleaning member surface with the fixing member surface.
In a second aspect of the invention a fixing device for fixing toner images onto a receiving material is provided, the device comprising an endless fixing member urged into contact with an endless counter member to form a fixing nip therebetween through which a receiving material path extends, a retractable cleaning member having a tacky polymer surface in contact with the surface of said fixing member, and a controllable radiant heating device positioned adjacent the cleaning member surface for heating said polymer on said cleaning member surface to adjust the tackiness thereof prior to contact of said cleaning member surface with said fixing member surface.
According to a third aspect of the invention, there is provided a method of removing debris from the surface of an endless fixing member of a fixing device in which the fixing member is urged into contact with an endless counter member to form a fixing nip therebetween through which receiving material passes, the method comprising contacting the surface of the fixing member with a cleaning member having a tacky surface, applying polymer material particles to the cleaning member, and heating the polymer material particles on the cleaning member surface in a controlled way by use of a radiant heating device positioned adjacent the cleaning member surface to render the surface tacky prior to contact of the cleaning member surface with the fixing member surface.
The fixing member preferably has an elastomeric outer layer consisting of, or coated with, a silicone material. The elastomeric outer layer enables the fixing member to exert a pressure against the counter member at the fixing nip which is optimum for the fixing of the toner particle image.
The fixing member may be in the form of a belt or a drum.
In the case where the fixing member is a belt, preferably this belt comprises an electrically conductive backing member covered with e.g. a silicone elastomer, polytetrafluoroethylene, fluorsilicones, polyfluoralkylene and other fluorinated polymers. On top, a semi-insulating or insulating coating layer, e.g. a fluorsilicone, may be formed. Alternately, a (reinforced) fabric backing may be used covered with a conductive (conformable) silicone layer, optionally covered with a top coating.
The invention is most applicable where the fixing member surface is dry, that is it is not supplied with a liquid release agent such as silicone oil.
The counter member may be in the form of a counter roller, although the use of a counter belt is also possible.
The cleaning surface is preferably an endless surface, such as the surface of a cleaning roller, although the use of a cleaning belt is also possible.
The cleaning roller may comprise a rigid core optionally provided with a conformable layer provided thereon. The inner core may be partly hollow or comprise at least one cavity, while the outer surface is perforated. In the latter case, the perforations extend throughout the conformable layer. The tacky surface layer is formed on the inner core or on the conformable layer, if present. The decision whether or not to provide a conformable layer depends on the conformability of the fixing member. The conformable covering preferably has a hardness of less than 80, most preferably less than 70, Shore A and a thickness of at least 1.0 mm, most preferably at least 2.0 mm. These requirements enable the cleaning roller to exert a pressure on the fixing member which is optimum for the removal of debris therefrom. Conductive fillers may be included in the conformable covering of the cleaning roller to control the electrical resistance thereof.
The cleaning member may be a cleaning roller which co-operates with a back-up roller to form a cleaning nip therebetween through which the transfer belt passes, downstream of the fixing nip. Means may be provided to adjust the pressure exerted between the cleaning roller and the back-up roller at the cleaning nip.
Heating the polymer material particles on the cleaning me
Broddin Dirk
Eelen Peter
Nuyts Kris
Verluyten Ludo
Grimley Arthur T.
Larson & Taylor PLC
Ngo Hoang
Xeikon NV
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