JP2006251677A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a belt from meandering without spoiling the durability of the belt. <P>SOLUTION: A fixing device 2 is equipped with a heat roller 4, two pressure rollers 8 and 10 on which the belt 6 is wound and which are pressed against the heat roller 4 across the belt 6. Ribs 16 are arranged on inner peripheral surfaces of both width-directional end portions of the belt 6. Small-diameter portions 8A and 10A and annular steps 8C and 10C are formed in both end regions of the pressure rollers 8 and 10. At the small-diameter portions 8A and 10A, a ring member 20 is fitted between the respective ribs 16, and steps 8C and 10C. One flank 20a of the ring member 20 which face one flank 16a of a corresponding rib 16 slants so that the gap formed with the one flank 16a of the corresponding rib 16 increases from the outer-periphery side end portion toward the inside of a radius. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a fixing device mounted on an image forming apparatus such as an electrophotographic copying machine, a printer, or a facsimile, and more specifically, a heat roller and a plurality of pressure rollers around which an endless belt is wound. And a plurality of pressure rollers pressed against the heat roller via the belt.

A fixing device mounted on an image forming apparatus requires high temperature and pressure for a certain time in order to fix unfixed toner on a sheet. In particular, in recent years, color image forming apparatuses, which have been in increasing demand, require a higher amount of heat and pressure than monochrome machines in order to print multiple color toners. In order to meet this requirement, a fixing device having a large nip width between the heat roller and the pressure roller is advantageous. As a typical example of such a fixing device, a heat roller and an endless belt are wound. An example of the fixing device includes two pressure rollers that are hung and two pressure rollers that are pressed against the heat roller via the belt (see Patent Document 1).

In such a fixing device, since a belt is used, a phenomenon occurs in which the belt is shifted in the width direction during the rotating operation and meanders. In order to prevent such meandering of the belt, the meandering-preventive ribs are bonded to the inner peripheral surfaces of both ends in the width direction of the belt so as to extend over the entire circumference, and the outer peripheral surface of the roller and the inner peripheral surface of the belt A synthetic resin ring member is disposed on the inner side of the rib in the width direction in order to prevent foreign matter from entering between and the rib from running on the outer peripheral surface of the corresponding roller. Means to do this has been proposed (see Patent Document 2).

In the above means, since one side surface of the rib of the belt and one side surface of the ring member facing the belt are formed to be orthogonal to the axis of the roller, the one side surface of the rib is bonded to the belt. When a force greater than the force acts in the width direction of the belt (axial direction of the roller), pressure acts on the entire one side surface of the rib, and the frictional force between the one side surface of the ring member increases. As a result, the ribs may be peeled off and eventually the belt may be cracked.
JP 2004-212844 A Japanese Patent Publication No. 07-066223

An object of the present invention is to provide a novel fixing device that makes it possible to prevent the belt from meandering without impairing the durability of the belt.

According to the present invention,
An inner peripheral surface of both end portions in the width direction of the belt, comprising: a heat roller; and a plurality of pressure rollers around which an endless belt is wound, the pressure rollers being in pressure contact with the heat roller via the belt The ribs for preventing meandering are arranged so as to extend over the entire circumference, and in each end region of each of the pressure rollers, a small-diameter portion having a smaller outer diameter than the intermediate region existing between the both end regions is formed. In the fixing device, an annular step is formed between the small diameter portion and the intermediate region, and each of the ribs of the belt is wound around the small diameter portion of each of the pressure rollers.
In each of the small-diameter portions of each of the pressure rollers, a ring member made of a synthetic resin is fitted between each of the ribs of the belt and the step, and the corresponding one of the ring members One side surface facing one side surface of the rib forms an inclined surface such that a gap with respect to the one side surface of the corresponding rib increases as it goes radially inward from the outer peripheral side end.
A fixing device is provided.
The one side surface of each of the ribs of the belt is formed so as to be orthogonal to the axis of each of the pressure rollers, and the outer peripheral end of each of the ring members is connected to the one side surface of each of the ring members. It is preferable that the corner portion intersects with the outer peripheral surface, and each corner portion forms a curved surface, and a partial region of the curved surface is in contact with the one side surface of each of the ribs.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of a fixing device configured according to the present invention will be described in detail with reference to the accompanying drawings.

1 to 4, the fixing device 2 includes a heat roller 4, and a plurality of pressure rollers 8 and 10 in the embodiment in which an endless belt 6 is wound with appropriate tension. It has. The pressure rollers 8 and 10 are pressed against the heat roller 4 via the belt 6. The heat roller 4 includes a cylindrical main body 12 made of a metal such as aluminum, and an elastic layer 14 made of silicon rubber or the like disposed on the outer peripheral surface of the cylindrical main body 12. A halogen heater H as a heat source is disposed at the center of the heat roller 4. The axes of the heat roller 4 and the pressure rollers 8 and 10 are parallel to each other.

The meandering-preventing ribs 16 extend over the entire circumference on the inner circumferential surfaces of both ends of the belt 6 in the width direction (the horizontal direction in FIG. 3 and the axial direction of the heat roller 4 and the pressure rollers 8 and 10). Arranged (adhered). In the embodiment, each of the ribs 16 has a rectangular cross section that is long in the width direction. The belt 6 is made of polyimide resin, and the surface is covered with a PFA tube. Each of the ribs 16 is made of a silicone resin.

In both end regions of the pressure rollers 8 and 10, small diameter portions 8B and 10B having outer diameters smaller than the large diameter portions 8A and 10A in the intermediate region existing between the both end regions are formed. Between the small diameter portions 8B and 10B and the large diameter portions 8A and 10A, annular steps 8C and 10C are formed, respectively. Each of the ribs 16 of the belt 6 is wound around the small diameter portions 8B and 10B of the pressure rollers 8 and 10, respectively.

In each of the small diameter portions 8B and 10B in each of the pressure rollers 8 and 10, an appropriate synthetic resin, for example, PPS resin, is provided between each of the ribs 16 of the belt 6 and the corresponding steps 8C and 10C. A ring member 20 made of (polyphenylene sulfide resin) or PEEK resin (polyether ether ketone resin) is fitted. As clearly shown in FIG. 4, the outer peripheral surfaces of the ring members 20 have substantially the same diameter as the outer peripheral surfaces of the large diameter portions 8 </ b> A and 10 </ b> A in the pressure rollers 8 and 10, respectively. Each of the ring members 20 is fitted to the small diameter portions 8B and 10B of the pressure rollers 8 and 10 so as to be relatively rotatable. The one side surface 20a of each ring member 20 that faces the one side surface 16a of the corresponding rib 16 has a gap that increases with respect to the one side surface 16a of the corresponding rib 16 as it goes radially inward from the outer peripheral end. It has an inclined surface. A corner where each side surface 20a and outer peripheral surface 20b of the ring member 20 intersects is formed into a curved surface. Although not shown, both ends of the heat roller 4 are arranged so as to exist in both end regions of the belt 6 and in both end regions where the ribs 16 exist.

One side surface 16 a of each of the ribs 16 of the belt 6 and the other side surface 20 c of each of the ring members 20 are formed so as to be orthogonal to the respective axes of the pressure rollers 8 and 10. In each step 8C and 10C of each of the pressure rollers 8 and 10, an annular region that faces and contacts the other side surface 20c of the corresponding ring member 20 is formed to be orthogonal to the axis of each of the pressure rollers 8 and 10. ing. In the embodiment, since the corners where each of the steps 8C and 10C in each of the pressure rollers 8 and 10 and the outer peripheral surfaces of the large diameter portions 8A and 10A intersect are formed on the inclined surfaces, the steps 8C and 10C The annular region that can face and contact the other side surface 20c of the corresponding ring member 20 is a region excluding the corner portion.

The heat roller 4 is drivingly connected to, for example, an electric motor that is a driving source through a power transmission mechanism such as a gear (none of which is shown). The unit comprising the pressure rollers 8 and 10, the belt 6 with each of the ribs 16, and each of the ring members 20 is biased towards the heat roller 4 by known spring means. The pressure rollers 8 and 10 are brought into pressure contact with the heat roller 4 via the belt 6. The region between the pressure rollers 8 and 10 on the outer peripheral surface of the belt 6 is also brought into pressure contact with the heat roller 4. When the heat roller 4 is rotationally driven in the clockwise direction in FIG. 1 by the electric motor, the pressure rollers 8 and 10 are driven to rotate together with the belt 6 in the counterclockwise direction. When the halogen heater H is energized and heat generation is started, the heating of the heat roller 4 is started. The heat transmitted to the heat roller 4 is also transmitted to the belt 6 and the pressure rollers 8 and 10 via the belt 6. After the surface temperature of the heat roller 4 reaches a predetermined temperature from room temperature, the sheet P on which the toner is transferred on one side (upper surface) is conveyed from right to left in FIG. 1, and the heat roller 4, the belt 6, After passing through the nip portion between the pressure rollers 8 and 10, the unfixed toner transferred to one side of the paper P is melted and fixed on one side of the paper P by the heat roller 4.

In the fixing device 2 according to the present invention, in each of the small diameter portions 8B and 10B of the pressure rollers 8 and 10, a ring member made of a synthetic resin is provided between each of the ribs 16 of the belt 6 and the steps 8C and 10C. The one side surface 20a of the ring member 20 facing the one side surface 16a of the corresponding rib 16 is directed to the one side surface 16a of the corresponding rib 16 as it goes radially inward from the outer peripheral end. It has an inclined surface that increases the gap. Due to such a configuration, as shown in FIG. 4, when one of the ribs 16 receives a force toward the inner side in the width direction of the belt 6, a root portion on one side surface 16 a of the rib 16 is Since it is brought into pressure contact with the corresponding corner of the ring member 20 and receives a reaction force directed outward in the width direction as indicated by an arrow directed to the left in FIG. As a result, the rib 16 can be prevented from being peeled off from the adhesive portion and from being cracked at the end of the belt 6. As a result, the meandering of the belt 6 can be prevented and the durability of the belt 6 and the rib 16 can be improved. Further, the ribs 16 of the belt 6 are prevented from riding on the ring member 20.

Furthermore, one side surface 16 a of each of the ribs 16 of the belt 6 is formed so as to be orthogonal to each axis of the pressure roller, and an outer peripheral side end portion of each of the ring members 20 is one side surface of each of the ring members 20. 20a and the outer peripheral surface are composed of corners, and each of the corners forms a curved surface, and a partial region of the curved surface is configured to come into contact with the one side surface 16a of each of the ribs 16, respectively. Friction with respect to the one side surface 16a in each of the ribs 16 is reduced, and peeling of each of the ribs 16 is prevented.

Although not shown in the drawing, both ends of the outer peripheral surface of the heat roller 4 to which the outer peripheral surface of the belt 6 is pressure-contacted are both end portions in the width direction of the belt 6 and are located in the region in the width direction where the ribs 16 are present. When the belt 6 is rotated, the belt 6 may be offset toward one side in the width direction and lifted toward the ring member 20 by one end portion of the outer peripheral surface of the heat roller 4. Since it is regulated, the durability of the belt 6 including the ribs 16 is sufficiently ensured and the meandering of the belt 6 is prevented.

As shown in FIG. 5, when the one side surface 16 a of the rib 16 and the one side surface 20 a of the ring member 20 are formed so as to be orthogonal to the axis, the rib 16 is on the inner side in the width direction of the belt 6. When the force toward the surface is received, almost the entire surface of the one side surface 16a of the rib 16 is brought into pressure contact with the substantially entire surface of the one side surface 20a of the ring member 20, and the width as shown by the arrow toward the left in FIG. Since the reaction force is directed outward in the direction, the friction increases, and the possibility that the rib 16 peels increases. On the other hand, as shown in FIG. 6, when the slope of the one side surface 20a of the ring member 20 is formed in the opposite direction to that in the present invention shown in FIG. Since the pressure acts, the tendency for the rib 16 to peel off or ride on the ring member 20 becomes strong. According to the present invention described above, such a problem is solved.

FIG. 3 is a schematic configuration diagram illustrating a main part of an embodiment of a fixing device configured according to the present invention, and is a schematic configuration diagram viewed in the axial direction of each roller. FIG. 2 is a perspective view showing a part of the fixing device shown in FIG. 1, omitting a heat roller and a belt. It is an AA arrow cross-sectional schematic of FIG. It is the B section enlarged view of FIG. In FIG. 4, it is a figure which replaces and shows a ring member to a comparative example. In FIG. 4, the ring member is replaced with another comparative example.

Explanation of symbols

2: Fixing device 4: Heating roller 6: Belt 8, 10: Pressure roller 8A, 10A: Large diameter portion 8B, 10B: Small diameter portion 8C, 10C: Step 16: Rib 16a: One side surface of rib 20: Ring member 20a: One side surface 20b of the ring member: outer peripheral surface 20c of the ring member: the other side surface of the ring member

Claims (2)

An inner peripheral surface of both end portions in the width direction of the belt, comprising: a heat roller; and a plurality of pressure rollers around which an endless belt is wound, the pressure rollers being in pressure contact with the heat roller via the belt The ribs for preventing meandering are arranged so as to extend over the entire circumference, and in each end region of each of the pressure rollers, a small-diameter portion having a smaller outer diameter than the intermediate region existing between the both end regions is formed. In the fixing device, an annular step is formed between the small diameter portion and the intermediate region, and each of the ribs of the belt is wound around the small diameter portion of each of the pressure rollers.
In each of the small-diameter portions of each of the pressure rollers, a ring member made of a synthetic resin is fitted between each of the ribs of the belt and the step, and the corresponding one of the ring members One side surface facing one side surface of the rib forms an inclined surface such that a gap with respect to the one side surface of the corresponding rib increases as it goes radially inward from the outer peripheral side end.
A fixing device. The one side surface of each of the ribs of the belt is formed so as to be orthogonal to the axis of each of the pressure rollers, and the outer peripheral end of each of the ring members is connected to the one side surface of each of the ring members. 2. The fixing device according to claim 1, comprising corner portions that intersect with an outer peripheral surface, each of the corner portions forming a curved surface, and a partial region of the curved surface is in contact with the one side surface of each of the ribs.

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