JP4691425B2 - Belt-type fixing device in image forming apparatus - Google Patents

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.

In such a belt-type fixing device, normally, the heating roller is rotatably supported by bearings at both ends thereof, and a belt detent member is externally fitted to the heating roller inside each bearing. (For example, refer to Patent Document 1).
Then, the surface of the heating roller becomes considerably hot. In particular, as shown in FIG. 5, when the supporting portion of the heating roller 10 by the bearing 15 has a small diameter, the supporting portion of the small diameter is about 300 ° C. In order to suppress the influence of heat on the bearing 15, the heating roller 10 is normally rotatably supported by the bearing 15 via a heat insulating bush 14 fitted on the heating roller 10. Conventionally, the belt detent member 13 and the heat insulating bush 14 have been configured separately.

JP-A-8-119484

  Thus, conventionally, since the belt detent member 13 and the heat insulation bush 14 are configured separately, two belt detent members 13 and two heat insulation bushes 14 are required for one heating roller 10, There is a disadvantage that the number of parts increases, and the assembly work of the belt detent member 13 and the heat insulating bush 14 to the heating roller 10 becomes complicated.

  The present invention pays attention to such conventional problems, and an object of the present invention is to provide an image forming apparatus that can reduce the number of parts related to the belt detent member and the heat insulating bush and can be easily assembled to the heating roller. The object is to provide a belt-type fixing device.

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 and the heat insulating bush are integrated, the belt locking member and the heat insulating bush are integrated, and the heat insulating bush and the belt offset in the axial direction of the heating roller. A slit is provided over the entire length of the member, and the endless belt of the slit in the belt detent member It is where the chamfer to the the open end prevents snagging of the endless belt.

According to the first characteristic configuration of the present invention, the belt detent member for preventing meandering of the endless belt stretched around the heating roller and the heat insulating bush supported by the bearing are integrated. And the heat insulating bush can be handled as one component, and therefore, the assembly of the belt stopper member and the heat insulating bush to the heating roller is facilitated, and the efficiency of the assembling work can be improved.
In addition, since the slit is provided over the entire length of the heat insulating bush and the belt stopper member in the axial direction of the heating roller, the presence of the slit makes it easy to fit the belt stopper member and the heat insulating bush to the heating roller. It can be done easily.
Furthermore, even if the heat insulating bush is thermally expanded due to the temperature rise, the expansion of the outer diameter of the heat insulating bush is suppressed by the thermal expansion to the slit side. Therefore, a large force due to the expansion of the outer diameter of the heat insulating bush acts on the bearing. This will not cause any damage to the bearing.
In addition, since the chamfering to prevent the endless belt from catching is provided at the opening end of the slit in the belt stopper member on the endless belt side, the slit is provided over the entire length of the heat insulating bush and the belt stopper member. The endless belt is not caught by the end of the slit of the belt stopper member on the endless belt side and is not damaged.

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. In the fixing device, the belt detent member and the heat insulation bush are integrated, and the inner diameter of the belt detent member is larger than the inner diameter of the heat insulation bush, and the shaft of the heating roller in the heat insulation bush The slit is provided over the entire length in the center direction .

According to the second characteristic configuration of the present invention, the belt detent member for preventing meandering of the endless belt stretched around the heating roller and the heat insulating bush supported by the bearing are integrated. And the heat insulating bush can be handled as one component, and therefore, the assembly of the belt stopper member and the heat insulating bush to the heating roller is facilitated, and the efficiency of the assembling work can be improved.

Further, since the inner diameter of the belt detent member is formed larger than the inner diameter of the heat insulating bush, the belt detent member is set to such an extent that the inner diameter of the belt detent member can be easily fitted to the heating roller. Can be easily fitted to the heating roller with respect to the heating roller, and the contact area between the inner circumferential surface of the belt retaining member and the outer circumferential surface of the heating roller. Can be reduced.
That is, by reducing the contact area between the inner peripheral surface of the belt detent member and the outer peripheral surface of the heating roller, the heat transfer from the heating roller to the belt detent member is suppressed, and the thermal expansion of the belt detent member is suppressed. Can do. If the thermal expansion of the belt stopper member is suppressed, there is no large gap between the inner surface of the belt stopper member and the outer peripheral surface of the heating roller. The endless belt can be prevented from meandering between the surface and non-rotatable, and the endless belt can be prevented from meandering by the belt detent member as desired.

Furthermore, since the slit is provided over the entire length in the axial direction of the heating roller in the heat insulating bush , the heat fitting bush can be easily and easily fitted to the heating roller due to the presence of the slit, As described in relation to the first characteristic configuration, even if the heat insulating bush is thermally expanded due to the temperature rise, the slit is prevented from expanding the outer diameter, so that the bearing is not damaged.

According to a third characteristic configuration of the present invention, in the belt-type fixing device having the second characteristic configuration, the slit is positioned closer to the belt detent member and closer to the rotation direction of the heat-insulating bush. The end opposite to the stop member is inclined so as to be located on the lower side in the rotational direction of the heat insulating bush.

According to the third characteristic configuration of the present invention, the slit is positioned on the upper side in the rotation direction of the heat insulation bush toward the belt detent member, and the end on the side opposite to the belt detent member is located on the lower side in the rotation direction of the heat insulation bush. For example, foreign matter such as abrasion powder generated by sliding contact between the bearing and the belt detent member is located on the opposite side of the belt detent member in the slit as the heat-insulating bush rotates. In other words, since it is forcibly conveyed to the end side of the heating roller and discharged, adverse effects caused by clogging of foreign matters are surely avoided.

According to a fourth characteristic configuration of the present invention, in the belt-type fixing device having the third characteristic configuration, a plurality of the slits are provided in a circumferential direction of the heat insulating bush.

According to the fourth characteristic configuration of the present invention, since a plurality of the slits are provided in the circumferential direction of the heat insulating bush, the above-described release of the foreign matter such as the wear powder is further ensured, and the adverse effect due to the clogging of the foreign matter is further reduced. It is avoided more reliably.

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. 2 (a), 3 (a), and 4 (a), the heating roller 10 in which the heating means H2 is incorporated and the endless belt 12 is stretched is heated. At both ends of the roller 10 in the axial center L direction, an annular belt detent member 13 and a heat insulating bush 14 are arranged along the axis L direction of the heating roller 10 with the belt detent member 13 inside and the heat insulating bush 14 outside. They are fitted on the outside.
The outer diameter of the belt detent member 13 is formed to be larger than the outer diameter of the heat insulating bush 14, and the belt detent member 13 and the heat insulating bush 14 are integrally made of the same material, for example, have high heat resistance, In addition, it is integrally formed of PPS (polyphenylene sulfide) resin having excellent mechanical strength and rigidity.
A belt detent member 13 fitted around the heating roller 10 prevents meandering of the endless belt 12 stretched around the heating roller 10, and the heating roller 10 is rotated by a bearing 15 via a heat insulating bush 14. It is configured to be supported freely.

  The above is the configuration common to the first to third embodiments of the present invention. Next, the first to third embodiments will be described in detail.

(First embodiment)
In the first embodiment, as shown in FIGS. 2A to 2C, in the belt detent member 13 and the heat insulating bush 14 integrally formed of PPS resin, an inner diameter D1 of the belt detent member 13 is formed. The inner diameter D2 of the heat insulating bush 14 is formed to be substantially the same diameter, and is fitted on the end portion of the heating roller 10 so as to be in close contact therewith. However, in the drawings, a slight gap is shown between the heating roller 10 and the heating roller 10 for easy understanding.
The belt stopper member 13 and the heat insulating bush 14 are provided with one straight slit 16 extending substantially along the axis L in the axial center L direction of the heating roller 10, and the belt stopper A chamfer 17 for preventing the endless belt 12 from being caught is provided at an opening end portion located on the rear side in the rotational direction R of the belt detent member 13 at the laterally open end portion of the slit 16 in the stop member 13. A chamfer 18 for preventing the endless belt 12 from being damaged is also provided at the opening end of the belt.

(Second Embodiment)
In the second embodiment, as shown in FIGS. 3A and 3B, in the integrally formed belt detent member 13 and the heat insulating bush 14, the belt detent member 13 is continuous over the entire circumference. The inner diameter D1 is larger than the inner diameter D2 of the heat insulating bushing 14, and the heat insulating bushing 14 is externally fitted in a state of being in close contact with the end of the heating roller 10 (however, In the drawing, a slight gap is shown between the heating roller 10 and the heating roller 10 for the reason described above).
And only in the heat insulation bush 14, the one linear slit 19 covering the full length of the axial center L direction of the heating roller 10 is provided along the axial center L substantially in parallel.

(Third embodiment)
In the third embodiment, as shown in FIGS. 4A and 4B, the belt detent member 13 and the heat insulating bush 14 formed integrally are formed in a continuous ring shape over the entire circumference. The inner diameter D1 of the belt detent member 13 is formed to be larger than the inner diameter D2 of the heat insulating bush 14, and the heat insulating bush 14 is fitted on the end of the heating roller 10 so as to be tightly attached (in the drawing, the above-mentioned is described above). For this reason, a plurality of linear slits 20 extending over the entire length in the axial center L direction of the heating roller 10 are formed in the axial center L only in the heat insulating bush 14. It is provided along.
The plurality of slits 20 are positioned on the upper side of the rotation direction R of the heat insulation bush 14 toward the belt detent member 13, and the rotation direction R of the heat insulation bush 14 toward the end opposite to the belt detent member 13. It is inclined so as to be located on the lower side.

〔The invention's effect〕
According to the present invention, since the belt detent member 13 and the heat insulating bush 14 are integrated, the belt detent member 13 and the heat insulating bush 14 can be handled as one part, and the belt detent member with respect to the heating roller 10 can be handled. 13 and the heat insulating bush 14 can be easily assembled, and the efficiency of the assembling work can be improved.

[Another embodiment]
In the first to third embodiments, the belt detent member 13 and the heat insulating bush 14 are integrally formed of PPS resin. However, the belt detent member 13 and the heat insulating bush 14 may be integrally formed of a material other than PPS resin. The belt detent member 13 and the heat insulating bush 14 may be formed separately from different materials, and the belt detent member 13 and the heat insulating bush 14 may be integrated by bonding or the like.

Schematic diagram of main parts of color image forming apparatus BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of a belt-type fixing device according to a first embodiment, where (a) is a cross-sectional view of the main part, (b) is a perspective view of the main part, and (c) is a side view of the main part. 4A and 4B are explanatory views of a belt-type fixing device according to a second embodiment, in which FIG. 4A and 4B are explanatory diagrams of a belt-type fixing device according to a third embodiment, in which FIG. Sectional view of the main part of a conventional belt-type fixing device

DESCRIPTION OF SYMBOLS 5 Belt type fixing device 10 Heating roller 12 Endless belt 13 Belt detent member 14 Thermal insulation bush 15 Bearing 16 Slit covering the entire length of the belt detent member and the thermal insulation bush 17 Chamfering to prevent the endless belt from catching 19 Slit covering the entire length of the thermal insulation bush 20 Inclined slit over the entire length of the heat insulation bush D1 Inner diameter of the belt detent member D2 Inner diameter of the heat insulation bush L Center axis of the heating roller R Direction of rotation of the heat insulation bush

Claims (4)

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 and the heat insulating bush are integrated ,
A slit is provided over the entire length of the heat insulating bush and the belt detent member in the axial direction of the heating roller, and the endless belt is prevented from being caught at the opening end of the slit in the belt detent member on the endless belt side. A belt-type fixing device in an image forming apparatus provided with chamfering . 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 and the heat insulating bush are integrated,
A belt-type fixing device in an image forming apparatus , wherein an inner diameter of the belt stopper member is formed larger than an inner diameter of the heat insulating bush, and a slit is provided over the entire length of the heat insulating bush in the axial direction of the heating roller . The slit is inclined such that the side closer to the belt detent member is located on the upper side in the rotation direction of the heat insulation bush, and the end opposite to the belt detent member is located on the lower side in the rotation direction of the heat insulation bush. belt type fixing device in the image forming apparatus according to claim 2 are. The belt-type fixing device in the image forming apparatus according to claim 3 , wherein a plurality of the slits are provided in a circumferential direction of the heat insulating bush .

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