JP2006208931A - Fixing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing apparatus, wherein inclination of a bearing for a pressurizing roller is prevented at a low cost and with simple constitution. <P>SOLUTION: The fixing apparatus 20 is provided with a heating roller 14, a pressurizing roller 16 and a pressurizing member 21 supporting the bearing 15 which supports the pressurizing roller to be able to be rotated and bringing the pressurizing roller into a pressurized contact with the heating roller by applying pressurizing force to the bearing in the direction of the heating roller, and a toner image on recording paper passing a nip part between the heating roller and the pressurizing roller is fixed. A groove part 21a opened in the direction crossing an axial direction of the pressurizing roller and also crossing the direction of the pressurizing force is stipulated in the pressurizing member and the bearing is held by being abutted on the groove part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a fixing device that is used in an image forming apparatus such as a copying machine, a printer, or a facsimile machine, and includes a fixing roller (heating roller) and a pressure roller to fix a toner image onto a recording sheet. .

In general, an image forming apparatus using an electrophotographic process includes a fixing device, and the fixing device fixes a toner image on a recording sheet (hereinafter simply referred to as a sheet) using a heating roller and a pressure roller. . In the fixing device, the heating roller is supported so as to be rotationally driven through a gear, a bearing, a bush, and the like disposed on a rotation shaft of the fixing device casing (hereinafter simply referred to as an apparatus casing). The pressure roller is rotatably supported by the apparatus housing via a bearing, and the bearing is urged by the pressure member so that the pressure roller is pressed against the fixing roller. Then, the sheet is passed through the nip portion between the heating roller and the pressure roller to fix the toner image on the sheet.

The above-mentioned pressure member has a U-shaped groove portion. A bearing is inserted into the groove portion to support the pressure roller by the pressure member and press the pressure roller in the direction of the heating roller. ing. And this groove part is opened in the pressurization direction of the pressure roller.

By the way, since the fixing device repeats heating and cooling, that is, when the image forming apparatus is turned on, the heating roller is heated, and when the image forming apparatus is turned off, heating of the heating roller is stopped. In response to this heating, the pressure roller repeats expansion and contraction, and due to the expansion and contraction, the bearing attached to the pressure roller is gradually pushed outward in the axial direction. And a bearing moves to an axial direction outer side until it contacts a pressurization member.

As described above, when the bearing comes into contact with the pressure member and is pressed toward the heating roller by the pressure member, the pressure member opens in the pressure direction, so that the contact between the bearing and the pressure member The bearing may tilt with the contact part as a fulcrum. As a result of the pressure being applied while the bearing is tilted, the rotation axis of the pressure roller is displaced when the pressure roller is rotated.

On the other hand, the inner ring of the bearing creeps and the pressure balance becomes poor, and the paper is wrinkled during fixing. Furthermore, if the rotation is repeated in the above-described state, the bearing will be damaged in the worst case.

On the other hand, as a fixing device, a U-shaped fitting opening having an opening on the pressure contact portion side with the pressure roller is provided, and the bearing of the heating roller is fitted into the fitting opening, and the hook portion of the frame is used. Supporting a part of the outer periphery of the bearing, supporting the upper fixing unit so that it can be opened and closed around the support shaft with respect to the lower fixing unit supported by the pressure roller, and one end of the upper fixing unit to the frame There is one in which the bearing is held by a bearing retainer that is a rod-like elastic member that is supported and detachably engaged with the convex portion of the frame (see Patent Document 1).

JP-A-8-44236

In order to prevent the above-described problems, for example, an E-ring or a screw is used at both ends of the pressure roller to prevent the pressure roller bearing from being tilted. It is only necessary to provide bearing tilt prevention members at both ends of the roller to prevent the pressure roller bearing from tilting, but using such a bearing tilt prevention member not only increases the number of parts, There is a problem that the number of man-hours for assembling the fixing device increases and the cost of the fixing device itself is increased.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fixing device capable of preventing the inclination of a pressure roller bearing with an inexpensive and simple configuration in view of the problems of the prior art.

Therefore, in order to solve such a problem, the present invention supports a heating roller, a pressure roller, and a bearing that rotatably supports the pressure roller, and applies pressure to the bearing in the direction of the heating roller. In addition, in a fixing device having a pressure member for pressing the pressure roller to the heating roller, and fixing a toner image on a recording sheet passing through a nip portion between the heating roller and the pressure roller. The pressure member has a holding portion that is opened in a direction that intersects the axial direction of the pressure roller and the direction of the pressing force, and is in contact with the holding portion to hold the bearing. It is a feature.

In this invention, the said holding | maintenance part is formed in U groove shape or U-shape, for example. In the present invention, a deformation preventing member that prevents deformation of the pressure member in the axial direction of the pressure roller due to axial movement of the pressure roller of the bearing is provided, and the deformation prevention member is the pressure member. One end of the roller extends along the axial direction of the roller, and one end of the roller is attached to the fixing device housing. The other end contacts the pressure member, and the deformation prevention member is disposed closer to the heating roller than the shaft of the pressure roller. It is desirable to do.

According to the present invention, the holding portion has a bottom surface portion and at least one arm portion that are in surface contact over the axial width of the bearing, and the bearing is supported by the bottom surface portion and the arm portion. .

As described above, the fixing device according to the present invention defines the holding portion opened in the direction intersecting both the axial direction of the pressure roller and the direction of the pressing force on the pressure member, and comes into contact with the holding portion. Since the bearing is held by the bearing, no rotational force is generated in the bearing even if the bearing moves outward in the axial direction and presses the pressure member due to the expansion of the pressure roller in the axial direction. There is no need for new parts, and as a result, there is an effect that the tilt of the bearing can be prevented with a simple structure at low cost.

In the present invention, the deformation prevention member for preventing the pressure roller from being deformed in the axial direction is provided, and the deformation prevention member is arranged on the heating roller side with respect to the shaft of the pressure roller. Even if the bearing is pressed in the axial direction due to expansion, there is an effect that deformation of the pressure member can be prevented.

In the present invention, since the bearing is supported by the bottom surface portion and the arm portion, the bearing can be stably supported, and since the bearing is pressurized at the bottom surface portion, the bearing is supported with respect to the axial width of the bearing. As a result of applying pressure at the central portion, there is an effect that the bearing does not tilt.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

First, the configuration of the fixing device will be described with reference to FIG. FIG. 1 is a perspective view illustrating an example of a fixing device. The illustrated fixing device 10 is used in an image forming apparatus, and fixes a toner image formed on a sheet by an electrophotographic process. The fixing device 10 includes a device housing 11, and a pair of bearing support members 12 are attached to the device housing 11, and bearings 13 are supported on the bearing support members 12, respectively, and a hollow cylindrical heating roller Both ends of the (fixing roller) 14 are supported by a bearing 13 so as to be rotationally driven. Although not shown, for example, a heater is provided inside the heating roller 14.

Further, both ends of the pressure roller 16 are rotatably supported by the apparatus housing 11 by bearings 15, and these bearings 15 are supported by a pressure member 17 described later. The bearing 15 is urged by the pressure member 17 in the direction of the heating roller 14, whereby the pressure roller 16 is pressed against the heating roller 14. The sheet on which the toner image is transferred passes through the nip portion between the pressure roller 16 and the heating roller 14, and at this time, the toner image on the sheet is fixed.

As shown in the figure, gears 18 and 19 are arranged on the rotating shafts at one end portions (the left end portion in the drawing) of the heating roller 14 and the pressure roller 16, respectively, and these gears 18 and 19 mesh with each other. When the heating roller 14 is rotationally driven by a drive source such as a motor that does not rotate, the pressure roller 16 rotates in synchronization with the heating roller 14.

Here, a conventional fixing device will be described with reference to FIGS. 2 and 3, the same components as those in FIG. 1 are denoted by the same reference numerals. FIG. 2 is a perspective view partially showing a conventional fixing device, and FIG. 3 is a view partially showing the conventional fixing device from the front.

As shown in the figure, the outer ring of the bearing 15 is supported by the pressure member 17, and the rotation shaft of the pressure roller 16 is rotatably supported by the bearing 15. As shown in FIG. 3, the pressure member 17 is formed in a U-shaped cross section, and a U-shaped groove portion (holding portion) 17a is formed on one surface (the surface on the side surface of the pressure roller 16). The bearing 15 is inserted into the groove portion 17 a and the outer ring of the bearing 15 is supported by the pressure member 17.

The U-shaped groove portion 17 a is opened in the pressing direction of the pressure roller 16, and a shaft member 17 b that is eccentric from the rotation shaft of the pressure roller 16 and extends in parallel with the rotation shaft of the pressure roller 16 is disposed. The pressure member 17 is rotatably supported by the shaft member 17b. The shaft member 17 b is supported by a support plate portion 11 a formed in the apparatus housing 11. As described above, the bearing 15 is pressed in the direction of the heating roller 14 by the pressing member 17, whereby the pressing roller 16 is pressed against the heating roller 14.

As described above, the pressure roller 16 repeatedly expands and contracts according to the heating of the heating roller 14, and the bearing 15 attached to the pressure roller 16 is caused by the expansion / contraction due to the expansion / contraction. As shown by the solid arrow in FIG. The bearing 15 moves outward in the axial direction until the flange portion 15 a formed at the axially inner end of the bearing 15 contacts the pressure member 17.

FIG. 4 is a diagram showing a state in which the flange portion 15a of the bearing 15 is in contact with the pressure member 17 from the front side, and the flange portion 15a of the bearing 15 is in contact with the pressure member 17 as shown in FIG. After that, the bearing 15, that is, the pressure roller 16 is pressed toward the heating roller 14 by the pressure member 17, and the pressure member 17 has a groove portion 17 a that opens in the pressure direction. Since the bearing is supported by 17a, when the bearing 15 is pressed toward the heating roller 14, a force in the direction of the heating roller 14 is applied to the bearing 15 as shown in FIG. The bearing 15 is tilted in the direction indicated by the solid line arrow in the drawing with the contact point A with the member 17 as a fulcrum.

As a result of the pressure applied while the bearing 15 is tilted, the rotation axis of the pressure roller 16 is displaced when the pressure roller 16 rotates. On the other hand, the inner ring of the bearing 15 creeps and the pressure balance is deteriorated, and the paper is wrinkled during fixing. Furthermore, if the rotation is repeated in the above-described state, the bearing 15 is damaged in the worst case.

In the present embodiment, the configuration shown in FIG. 6 is adopted in order to prevent the inclination of the bearing 15 as described above. 6 is a perspective view partially showing an example of the fixing device according to the first embodiment of the present invention. In FIG. 6, the fixing device is denoted by reference numeral 20, and the same components as those in FIGS. Give it a number.

Referring to FIG. 6, the illustrated fixing device 20 has a pressure member 21, which is perpendicular to the pressure direction indicated by the solid line arrow and has a U-shape that opens to the front side in the figure. A groove 21a is formed, and the outer ring of the bearing 15 is supported by the groove 21a. That is, the pressure member 21 has a pair of arm portions 21b and 21c on the side surface side of the pressure roller 16, and the arm portions 21b and 21c extend to the front side in the figure orthogonal to the pressure direction indicated by the solid line arrow. is doing. The arm portion 21b is shorter than the arm portion 21c, and a U-shaped groove portion 21a is formed by the arm portions 21b and 21c.

As shown in the figure, the arm portion 21b is a plate-like body, and the arm portion 21c has a bottom surface portion 21f and upright side portions 21d and 21e that stand upright at both axial ends of the bottom surface portion 21f. The arm portion 21c faces the upright side portion 21d, and the outer ring of the bearing 15 is sandwiched between the arm portion 21b and the upright side portion 21d.

In the pressure member 21 described above, the U-shaped groove 21a opens in a direction perpendicular to the pressure direction, that is, the arm portions 21b and 21c extend in a direction perpendicular to the pressure direction. Therefore, even if the pressure roller 16 is pressed toward the heating roller 14 after the bearing 15 moves outward in the axial direction and the flange portion 15a comes into contact with the pressure member 20, the arm portion 21b remains in contact with the heating member 14. And the inclination of the bearing 15 is prevented.

That is, the pressure roller 16 and the arm portions 21b and 21c extending in the direction orthogonal to the pressure direction function as contact members, and a rotational force is generated even when the flange portion 15a contacts the pressure member 21. And the inclination of the bearing 15 is prevented.

If the rotation shaft of the pressure roller 16 is short, when the bearing 15 is pushed outward in the axial direction due to expansion / contraction, the bearing 15 is caught on the edge (end) of the rotation shaft of the pressure roller 16. Thus, when it expands, the force with which the rotating shaft tries to push the bearing 15 increases. For this reason, the bearing 15 is configured so that the rotation axis 16a of the pressure roller 16 has at least a radial width of the bearing 15 + a length (play) + a margin of thermal expansion. It is desirable not to get caught by the edge of the rotating shaft 16a.

In the example shown in FIG. 6, the U-shaped groove 21 a is formed in the pressure member 21, but a U-shaped groove 211 may be formed as shown in FIG. 7. That is, the U-shaped groove 211 may be formed by the arms 21b and 21c, and the groove 211 may have an opening in a direction perpendicular to the pressure roller 16 and the pressure direction.

In this way, compared to the U-shaped groove 21a, the area where the outer ring of the bearing 15 contacts the peripheral surface of the groove 211 is reduced, and the frictional force with the bearing 15 can be reduced. In FIG. 7, the bearing 13, the heating roller 14, and the shaft member 17b are omitted.

By the way, in the example shown in FIG.6 and FIG.7, since the arm part 21b is plate shape, when the bearing 15 is pressed to an axial direction due to the thermal expansion of the pressure roller 16, the arm part 21b and Although the arm portion 21c functions as a retainer, the arm portion 21b may be deformed in the example shown in FIGS. 6 and 7 because the arm portion 21b is plate-shaped. In order to prevent such deformation, it is desirable to provide a deformation preventing member 31 as shown in FIGS.

8 is a perspective view partially showing the fixing device 20, and FIG. 9 is a view partially showing the fixing device 20 from the front side. As illustrated, the deformation preventing member 31 has one end attached to the support plate portion 11a and the other end in contact with the arm portion 21b. The deformation preventing member 31 is disposed at a position closer to the heating roller 14 than the rotating shaft 16a of the pressure roller 16.

Thus, if the deformation preventing member 31 is provided, even if the bearing 15 is pressed in the axial direction due to the thermal expansion of the pressure roller 16, and the arm portion 21b is pressed in the axial direction by the bearing 15, The deformation preventing member 31 prevents the arm portion 21b from being deformed.

Furthermore, in the example shown in FIG. 6 or FIG. 7, the bearing 15 is supported by the groove portion 21a or 211 formed in the arm portion 21b and the arm portion 21c. However, since the arm portion 21b is plate-shaped, the bearing 15 Is supported by a side portion having a small area, the support of the bearing 15 becomes unstable, and the bearing 15 may tilt.

In order to prevent such a problem, for example, a pressure member 41 shown in FIGS. 10 and 11 is used. 10 is a perspective view partially showing the fixing device 20, and FIG. 11 is a view showing the fixing device 20 partially from the front side. 10 and 11, the same components as those shown in FIGS. 6 and 7 are denoted by the same reference numerals. As described above, the arm portion 21c has the bottom surface portion 21f and the upright sides 21d and 21e. In FIGS. 10 and 11, the arm portion 21b is formed at a position facing the bottom surface portion 21f. Further, the pressing member 41 has an arm portion 41a formed at a position facing the upright side portion 21e, and the arm portion 41a extends in the extending direction of the upright side portion 21e.

As illustrated, the bearing 15 is accommodated in a space formed by the arm portion 21b, the arm portion 21c, and the arm portion 41a, and the outer ring of the bearing 15 is in contact with the bottom surface portion 21f and the arm portion 21b. In this way, if the bearing 15 is supported, the bearing 15 can be stably supported. Even if the bearing 15 is pressed in the axial direction due to the thermal expansion of the pressure roller 16, the bearing 15 It does not tilt.

Further, since the bearing 15 is pressed toward the heating roller 14 by the bottom surface portion 21f, that is, the bearing 15 is pressed by the surface, the pressing force can be applied at the central portion with respect to the axial width of the bearing 15. As a result, the bearing 15 does not tilt.

The holding member that opens in the direction that intersects the axial direction of the pressure roller and the direction of the pressing force is defined on the pressure member, and the bearing is held in contact with the holding portion. Even if the pressure member is moved outward and the pressure member is pressed, no rotational force is generated in the bearing, and the inclination of the bearing can be prevented with a simple configuration. As a result, it can be applied to a fixing device having a heating roller and a pressure roller.

1 is a perspective view illustrating an example of a fixing device used in an image forming apparatus. FIG. 10 is a perspective view partially showing a conventional fixing device. It is a figure which shows the conventional fixing device partially from the front. It is a figure which shows the state which the flange part of the bearing for pressure rollers shown in FIG. 3 contact | abutted to the pressurization member from the front side. It is a figure which shows the state which the bearing for pressure rollers shown in FIG. 4 inclined from the front side. 1 is a perspective view partially showing a first example of a fixing device according to Embodiment 1 of the present invention; FIG. FIG. 6 is a perspective view partially showing a second example of a fixing device according to Embodiment 1 of the present invention. FIG. 6 is a perspective view partially showing a third example of a fixing device according to Embodiment 1 of the present invention. FIG. 10 is a diagram partially showing the third example of the fixing device according to the first embodiment of the present invention from the front. FIG. 6 is a perspective view partially showing a fourth example of a fixing device according to Embodiment 1 of the present invention. FIG. 7 is a perspective view partially showing the fourth example of the fixing device according to the first exemplary embodiment of the present invention from the front.

Explanation of symbols

10, 20 Fixing device 11 Device housing 12 Bearing support member 13, 15 Bearing 14 Heating roller 16 Pressure roller 17, 21, 41 Pressure member 17a, 21a, 211 Groove portion 21b, 21c, 41a Arm portion 21d, 21e Upright side Part 21f bottom part 31 deformation prevention member

Claims (4)

A heating roller and a pressure roller, and a bearing that rotatably supports the pressure roller are supported, and pressure is applied to the bearing in the direction of the heating roller to press the pressure roller against the heating roller. A fixing device for fixing a toner image on a recording sheet that passes through a nip portion between the heating roller and the pressure roller.
The pressing member is formed with a holding portion that is opened in a direction intersecting with the axial direction of the pressing roller and the direction of the pressure applied from the pressing roller to the heating roller. A fixing device, wherein the bearing is held in contact therewith. The fixing device according to claim 1, wherein the holding portion is formed in a U-groove shape or a U-shape. A deformation preventing member that prevents deformation of the pressure member in the axial direction of the pressure roller due to axial movement of the pressure roller of the bearing;
The deformation preventing member extends along the axial direction of the pressure roller, and one end side thereof is attached to the fixing device casing, and the other end side abuts on the pressure member.
The fixing device according to claim 2, wherein the deformation preventing member is disposed closer to the heating roller than a shaft of the pressure roller. The holding portion has a bottom surface portion that makes surface contact with the bearing over the width of the bearing in the axial direction of the pressure roller and at least one arm portion, and supports the bearing by the bottom surface portion and the arm portion. The fixing device according to claim 2, wherein the fixing device is configured as described above.

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