JP2007079464A - Belt type fixing device for image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a belt type fixing device for an image forming apparatus, capable of easily fitting a belt meandering preventing member on a heat roller, and also, capable of suppressing the damage of an endless belt caused by the belt meandering preventing member. <P>SOLUTION: In the belt type fixing device 5 for the image forming apparatus, the belt meandering preventing member 13 and a heat insulating bush 14 are externally fitted on both end parts of the heat roller 10 in the direction of the axis L so that the belt meandering preventing member 13 can prevent the meandering of the endless belt 12, and the heat roller 10 can be freely rotatably supported by a bearing 5 via the heat insulating bush 14. The belt meandering preventing member 13 is formed to a ring shape continued over the whole periphery, and the belt meandering preventing member 13 is externally fitted in a state being clamped to the outer peripheral surface of the heat roller 10 at ordinary temperature, by external fitting in a state the belt meandering preventing member 13 is heated and expanded by heating or by external fitting in a state the heat roller 10 is cooled and contracted by cooling. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  According to the present invention, the belt detent member and the heat insulating bush are fitted on both ends of the heating roller in the axial direction with the belt detent member inside and the heat insulating bush arranged outside along the axial direction, The present invention relates to a belt-type fixing device in an image forming apparatus in which a belt detent member prevents meandering of an endless belt stretched around the heating roller, and the heating roller is rotatably supported by a bearing via a heat insulating bush.

Conventionally, in such a belt type fixing device, since the surface of the heating roller becomes considerably high, in order to suppress the influence of heat on the bearing, as shown in FIG. 14, and the heating roller 10 was rotatably supported by a bearing 15 through the heat insulating bush 14.
The belt detent member 13 for preventing the endless belt 12 from meandering is formed in a ring shape that is continuous over the entire circumference in the circumferential direction. The detent member 13 was relatively loosely fitted to the heating roller 10.
Therefore, in the conventional belt type fixing device, as shown in FIG. 3A, there is a gap S between the belt detent member 13 and the heating roller 10, and as shown in FIG. The endless belt 12 may enter the gap S and become unrotatable.

  Therefore, the belt detent member is formed in a C shape having a cut in the circumferential direction to facilitate external fitting to the heating roller, and the belt detent member is surrounded by the spring force of the belt detent member itself. It has been proposed that the belt is firmly fitted on the surface, and even if the heating roller is thermally expanded, the amount of deformation due to the thermal expansion is absorbed by the cuts so that mechanical stress is not applied to the belt detent member ( For example, see Patent Document 1).

JP-A-8-119484

However, in the prior art described in the above-mentioned patent document, there is a notch in the circumferential direction of the belt detent member, and therefore there is a problem that the endless belt is damaged when the endless belt contacts or slides on the edge of the notch. there were.
That is, according to the above-mentioned patent document, there is a description that the endless belt is caught on the cut by chamfering the cut portion of the belt stopper member, but even if chamfering is performed, Because the endless belt repeatedly contacts or slides on the chamfered portion, damage to the endless belt due to the cut of the belt detent member cannot be completely avoided, and there is room for improvement in this respect. .

  The present invention pays attention to such a conventional problem, and an object of the present invention is to make it possible to easily fit the belt stopper member to the heating roller and to endlessly cause the belt stopper member. An object of the present invention is to provide a belt type fixing device in an image forming apparatus capable of suppressing damage to the belt.

  The first characteristic configuration of the present invention is that the belt detent member and the heat insulating bush are arranged at both ends in the axial direction of the heating roller, with the belt detent member arranged inside along the axial direction and the heat insulating bush arranged outside. A belt in an image forming apparatus that is externally fitted, the belt detent member prevents meandering of an endless belt stretched around the heating roller, and the heating roller is rotatably supported by a bearing through the heat insulating bush. The belt fixing member is formed in a continuous ring shape around the entire circumference, and is heated at a normal temperature by a heat fitting that is externally fitted to the heating roller in a state where the belt stopping member is heated and expanded. It exists in the place externally fitted in the state clamped to the outer peripheral surface of the said heating roller.

According to the first characteristic configuration of the present invention, since the belt detent member for preventing meandering of the endless belt is formed in a ring shape continuous over the entire circumference, there is no cut or slit in the belt detent member. Therefore, even if the endless belt repeatedly contacts or slides on the belt detent member, damage to the endless belt due to the belt detent member is suppressed.
The belt detent member is externally fitted in a state of being clamped to the outer peripheral surface of the heating roller at room temperature by a heat fit that is fitted to the heating roller in a state where the belt detent member is heated and expanded. There is no risk of the endless belt entering between the detent member and the heating roller, and the belt detent member can be easily externally fitted to the heating roller by heating the belt detent member.

  According to a second characteristic configuration of the present invention, the belt detent member and the heat insulating bush are arranged at both ends in the axial direction of the heating roller, with the belt detent member arranged inside along the axial direction and the heat insulating bush arranged outside. A belt in an image forming apparatus that is externally fitted, the belt detent member prevents meandering of an endless belt stretched around the heating roller, and the heating roller is rotatably supported by a bearing through the heat insulating bush. The belt fixing member is formed in a continuous ring shape around the entire circumference, and the heating roller is cooled at a normal temperature by a cold fitting that is externally fitted to the heating roller in a cooled and contracted state. It is in the place fitted by the state clamped to the outer peripheral surface of a roller.

According to the second characteristic configuration of the present invention, as in the first characteristic configuration, the belt detent member for preventing meandering of the endless belt is formed in a continuous ring shape over the entire circumference. Further, damage to the endless belt due to the belt detent member is suppressed.
The belt detent member is externally fitted in a state of being clamped on the outer peripheral surface of the heating roller at a normal temperature by a cold fitting fitted to the heating roller in a state where the heating roller is cooled and contracted. There is no risk of the endless belt entering between the stop member and the heating roller, and the belt offset stop member can be easily fitted onto the heating roller by a cold fit of the heating roller.

An embodiment of a belt-type fixing device in an image forming apparatus according to the present invention will be described with reference to the drawings.
This belt-type fixing device is incorporated in an image forming apparatus such as a copying machine, a printer, or a facsimile, and is used for fixing a toner image onto a transfer sheet. For example, the belt-type fixing device may be a tandem type color image forming apparatus. For example, as shown in FIG. 1, an endless intermediate transfer belt 1 is provided, and only two developing devices 2 and 3 are shown below the intermediate transfer belt 1 in the figure. A total of four developing devices for magenta and black are provided.
By these four developing devices, different color toner images are successively transferred onto the intermediate transfer belt 1 in a superimposed manner. By applying a reverse bias to the secondary transfer roller 4, the toner image on the intermediate transfer belt 1 is transferred onto the transfer paper P. Thereafter, the toner image is fixed on the transfer paper P by the belt-type fixing device 5 and discharged to the paper discharge unit 6.

The belt-type fixing device 5 includes a fixing roller 7 including a heating unit H1 such as a halogen heater, a pressure roller 8 pressed against the fixing roller 7, and further includes an external heating unit 9.
The external heating means 9 includes a heating roller 10 incorporating a heating means H2 such as a halogen heater, a belt support roller 11, an endless belt 12 stretched between the heating roller 10 and the belt support roller 11, and the like. .
The heating roller 10 incorporating the heating unit H2 and the endless belt 12 are pressed against the fixing roller 7, and the fixing roller 7 is heated via the endless belt 12 by the heat from the heating unit H2. Yes.

As shown in FIGS. 2A and 2B, the heating roller 10 in which the heating unit H <b> 2 is built and the endless belt 12 is stretched has both ends of the heating roller 10 in the axial center L direction. An annular belt detent member 13 and a heat insulating bush 14 formed separately from each other are fitted around the belt detent member 13 on the inner side and the heat insulating bush 14 on the outer side along the axial center L direction of the heating roller 10, respectively. Has been.
The belt detent member 13 is formed in a ring shape that is continuous over the entire circumference in the circumferential direction, and the belt detent member 13 is externally fitted to the heating roller 10 in a state where the belt detent member 13 is heated and expanded, or the heating roller. 10 is externally fitted to the heating roller 10 by a cold fit that is externally fitted in a cooled and contracted state, whereby the belt detent member 13 is firmly removed in a state of being firmly clamped to the outer peripheral surface of the heating roller 10 at room temperature. It is fitted.

On the other hand, the heat insulating bush 14 is not formed in a circumferentially continuous ring shape like the belt detent member 13, but has a slit 14 a that is parallel to the axis L of the heating roller 10 and extends over the entire width of the heat insulating bush 14. It is formed in a substantially C shape so as to have.
The outer diameter of the belt detent member 13 is formed to be larger than the outer diameter of the heat insulating bushing 14, and the belt detent member 13 and the heat insulating bush 14 have high heat resistance, mechanical strength and rigidity. Further, a belt detent member 13 formed of PPS (polyphenylene sulfide) resin and externally fitted to the heating roller 10 prevents meandering of the endless belt 12 stretched around the heating roller 10. The roller 10 is configured to be rotatably supported by a bearing 15 via a heat insulating bush 14.

〔The invention's effect〕
According to the present invention, the belt detent member is formed in a continuous ring shape around the entire circumference and has no cuts or slits. Therefore, even if the endless belt repeatedly contacts or slides on the belt detent member. Further, damage to the endless belt due to the belt detent member is surely suppressed.
The belt detent member is externally fitted in a state of being firmly clamped to the outer peripheral surface of the heating roller at normal temperature by heat fitting or cold fitting, so that the endless belt is interposed between the heating roller and the belt detent member. In addition, there is no gap into which the belt enters, and the belt-fitting stopper member can be easily fitted to the heating roller by heat fitting or cold fitting.

[Another embodiment]
(1) In the previous embodiment, the belt detent member 13 and the heat insulating bush 14 are both formed of PPS resin. However, the belt detent member can be formed of a material other than PPS resin. 13 and the heat insulating bush 14 may be formed of different materials.

(2) In the previous embodiment, the belt detent member 13 is heated and expanded to be externally fitted to the heating roller 10, or a cold fit that is externally fitted in a state in which the heating roller 10 is cooled and contracted is cooled. Although the example in which the stopper member 13 is externally fitted to the heating roller 10 is shown, the belt stopper member 13 is attached to the heating roller 10 in a state where the belt stopper member 13 is heated and expanded and the heating roller 10 is cooled and contracted. It can also be fitted.

Schematic diagram of main parts of color image forming apparatus 2A and 2B are explanatory views of a belt-type fixing device, in which FIG. Sectional view of the main part of a conventional belt-type fixing device

Explanation of symbols

DESCRIPTION OF SYMBOLS 5 Belt type fixing device 10 Heating roller 12 Endless belt 13 Belt detent member 14 Heat insulation bush 15 Bearing L Shaft roller axis

Claims (2)

A belt detent member and a heat insulation bush are fitted on both ends of the heating roller in the axial direction, with the belt detent member arranged inside and the heat insulation bush arranged outside along the axial direction. Is a belt-type fixing device in an image forming apparatus that prevents meandering of an endless belt stretched around the heating roller, and the heating roller is rotatably supported by a bearing through the heat insulating bush,
The belt detent member is formed in a continuous ring shape over the entire circumference, and the belt detent member is fitted on the outer peripheral surface of the heating roller at room temperature by a heat fit that is externally fitted to the heating roller in a heated and expanded state. A belt-type fixing device in an image forming apparatus that is externally fitted in a clamped state. A belt detent member and a heat insulation bush are fitted on both ends of the heating roller in the axial direction, with the belt detent member arranged inside and the heat insulation bush arranged outside along the axial direction. Is a belt-type fixing device in an image forming apparatus that prevents meandering of an endless belt stretched around the heating roller, and the heating roller is rotatably supported by a bearing through the heat insulating bush,
The belt detent member is formed in a ring shape that is continuous over the entire circumference, and is clamped to the outer peripheral surface of the heating roller at normal temperature by a cold fitting that is fitted to the heating roller in a state where the heating roller is cooled and contracted. A belt-type fixing device in an image forming apparatus that is externally fitted in a state.

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