Nitto Kogyo Co., Ltd.

Yuichiro Higashi

Yasuhide Hamada

Takeshi Kato

Youichi Ishikawa

Kesaaki Kitazawa

The present invention provides a fixing apparatus includes a fixing roller, a heating sourcefor allowing the outer peripheral surface of the fixing rollerto have a given temperature capable of performing a fixing operation, a pressing rollerin rotational contact with the fixing roller, and a biasing memberfor allowing the pressing rollerto be brought into press contact with the fixing rollerat a given pressure. The fixing apparatus is operable to allow a sheet with a surface supporting an unfixed toner thereon to pass through the rotational contact region along one direction so as to fix the unfixed toner onto the sheet. In this fixing apparatus, the fixing rolleris disposed on the side of the sheet surface supporting the unfixed toner, and the pressing rolleris disposed on the opposite side of the fixing rollerwith respect to the sheet. Further, the biasing memberis adapted to apply a biasing force to the pressing roller in a direction Y intersecting with an axis X connecting the respective center positions of the fixing rollerand the pressing roller

Fixing apparatus

A toner image fixing apparatus has a fixing roller, a pressing roller, and a heating roller. The pressing roller is normally urged toward the fixing roller for pressing a sheet with an unfixed toner image carried on a surface thereof against the fixing roller to fix the unfixed toner image to the sheet when the sheet passes in one direction through a rolling contact region between the fixing roller and the pressing roller. The heating roller is disposed on one side of the fixing roller opposite to the pressing roller. A first heat source is disposed in the heating roller for heating the heating roller, and a second heat source is disposed in the pressing roller for heating the pressing roller. An endless heat transfer belt is trained around the heating roller and the fixing roller for transferring heat from the first heat source to heat the unfixed toner image on the sheet when the sheet passes through the rolling contact region. When the apparatus is in a standby mode, a controller energizes the first heat source and the second heat source. When the apparatus is in the sheet feed mode, the controller energizes the first heat source, and also energizes the second heat source only if the sheet is of a size larger than a predetermined size.

Toner image fixing apparatus capable of keeping constant fixing roller temperature

The fixing apparatus is capable of ensure the freedom of the design for a driving mechanism which is provided for endlessly traveling the fixing belt. In order to accomplish the object, the fixing apparatus has a fixing roller (,), a pressing roller (,) being rollingly contacted the fixing roller (,), a heating roller (,) positioned upstream side of the fixing roller (,) with respect to a feeding direction in which a sheet (S) carrying an unfixed toner image thereon is fed and having a heating source therein, a fixing belt (,) trained around the heating roller (,) and the fixing roller (,) for transferring heat from the heat source to preheat the unfixed toner image on the sheet (S) before the sheet (S) passes through a rolling contact region defined between the fixing roller (,) and pressing roller (,), and a driving mechanism (,) for rotatably driving the pressing roller (,).

The present invention provides a fixing apparatus which can secure a sufficient fixing performance even if a nip pressure is arranged in relatively low value. A fixing apparatus comprises a fixing member (,) having an elastic layer (,B,,B) formed on the fixing member at a side to which a sheet surface supporting an unfixed toner is contacted; a pressing member (,) for making the sheet surface supporting the unfixed toner contact to the fixing member (,) with a particular pressure and forming a nip portion between the fixing member and the pressing member; and a heating means (,) heating the fixing member(,), wherein 0.05&lE;P&middot;t/E&lE;0.50 is satisfied, where t (mm) is thickness of the elastic layer (,B,,B), E (Pa) is Young's modulus of the elastic layer (,B,,B) and P (Pa) is pressure in the nip portion.

A toner image fixing apparatus has a fixing roller, a pressing roller, and a heating roller which are rotatable about their own axes. The pressing roller presses a sheet carrying an unfixed toner image against the fixing roller to fix the unfixed toner image to the sheet. The heating roller is disposed on one side of the fixing roller remotely from the pressing roller. An endless heat transfer belt is trained around the heating and fixing rollers for transferring heat from a heater to heat the unfixed toner image on the sheet. A guide plate is positioned upstream of the pressing roller for guiding the sheet to enter between the fixing and pressing rollers. The heat transfer belt and the guide plate are so spaced from each other that the sheet prior to being entering between the fixing and pressing rollers is kept out of contact with the heat transfer belt. The heat transfer belt may be positioned outside of a region where the sheet guided by the guide plate possibly passes. An angle between a line segment interconnecting the centers of the heating and fixing rollers and a reference line interconnecting the centers of the fixing and pressing rollers lies in a range from 105.degree. to 255.degree.. The fixing roller is a resilient roller with an outer resilient layer. The temperatures of the fixing and pressing rollers are kept in a predetermined temperature range in a standby mode.

Toner image fixing apparatus

A toner image fixing apparatus has a fixing roller, a pressing roller normally urged toward the fixing roller for pressing a sheet with an unfixed toner image carried on a surface thereof against the fixing roller to fix the unfixed toner image to the sheet when the sheet passes in one direction through a rolling contact region between the fixing roller and the pressing roller, a heating roller disposed on one side of the fixing roller opposite to the pressing roller, the heating roller having a heating source disposed therein for heating the heating roller, an endless heat transfer belt trained around the heating roller and the fixing roller for transferring heat from the heating source to heat the unfixed toner image on the sheet when the sheet passes through the rolling contact region, and a standby mode temperature control circuit for maintaining temperatures of the fixing roller and the pressing roller in a predetermined temperature range in a standby mode.

Toner image fixing apparatus having standby mode temperature control

A fixing device to be used in electrophotographic apparatus for providing a clear fixed image with no offset with use of no oil or the least amount of oil, wherein an endless fixing belt provided with a metal body having a release thin film thereon is stretched between a fixing roller having a elastic surface and a heating roller, a pressing roller is arranged to press the surface of the elastic fixing roller upwardly from the lower side thereof through the fixing belt to form a nip portion between the fixing belt and the pressing roller, a guide plate for unfixed image carrying support member is provided underneath the fixing belt, between the heating roller and the nip portion, to form substantially a linear heating path between the guide plate and the fixing belt, and the metal body of the fixing belt has a heat capacity per cm.sup.2 within a range of 0.001 to 0.02 cal/.degree.C.

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Tokyo, Japan

Yuichiro Higashi