JPH09263342A - Meandering correction device for belt mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct the meandering of a belt in a short time without exerting a large force on the belt pinched by both outer and inner supporting members when the meandering is corrected, by providing a supporting structure for integrally supporting an outer supporting member and an inner supporting member opposite to the outer supporting member and a moving structure for slanting the supporting structure. SOLUTION: When it is detected that a belt 14 is meandered more then a prescribed amount, a controller moves a moving flange 40 to set a heating roller 24 and a pressing roller 28 at a slant position to a drive roller 18 or the like, whereby the belt 14 is moved in the direction of the width while rotating and meandering are corrected. The constraining force of the belt 14 at a nip part 34 is the strongest and since the nip part 34 is moved with the heating roller 24 and the pressing roller 28, the meandering is corrected in a short time. When the correction of the meandering is finished, the moving flange 40 is returned to an original position and the heating roller 24 and the pressing roller 28 are set in parallel to the drive roller 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for correcting the meandering of a belt in a belt mechanism in which an endless belt is supported by a plurality of supporting members such as rollers.

[0002]

2. Description of the Related Art In a belt mechanism for rotatably moving an endless belt supported from the inside by a plurality of rollers, a slight roller setting error or uneven tension on the belt causes The belt gradually moves to one side of the roller. (Hereinafter, this movement in the roller axial direction is referred to as "meandering".) Therefore, conventionally, the amount of movement of the belt, that is, the meandering amount is detected, and when the value exceeds a predetermined amount, one of the rollers is tilted to cause the meandering. A compensating device has been proposed.

[0003]

However, in the case where the pressure roller is arranged outside the belt and the pressure roller is pressure-contacted to the inner roller via the belt, the belt restraining force at this pressure-contact portion is different. Larger than the roller contact part. Therefore, even if the rollers other than the roller facing the pressure roller are inclined, the meandering cannot be corrected well, and it takes a long time to correct the meandering.

[0004]

Therefore, according to the present invention, an endless belt, a plurality of inner supporting members for supporting the belt from the inner side, and at least one of the inner supporting members arranged outside the belt. In a belt mechanism including an outer supporting member that is pressed against the two via the belt,
A support structure integrally supporting the outer support member and an inner support member facing the outer support member, and a moving mechanism for inclining the support structure are provided.

[0005]

In the meandering correction device of the belt mechanism described above, the outer supporting member and the inner supporting member, which is pressed against the outer supporting member through the belt, are integrally supported by the supporting structure. When operated, the outer support member and the inner support member are integrally tilted. Therefore, at the time of correcting the meandering, an excessive force is not applied to the belt portion sandwiched by the outer supporting member and the inner supporting member, and the meandering is corrected early.

[0006]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a fixing device 10 in an electrophotographic image forming apparatus that heats and melts unfixed toner and fixes it to a sheet. The fixing device 10 includes a belt mechanism and a meandering correction device according to the present invention. . The belt mechanism 12 of the fixing device 10 includes an endless belt 14 made of a heat resistant material. Belt 1
4 is a drive roller 18 drivingly connected to the motor 16;
A driven roller 20 and a heating roller 2 having a heater 22 built therein.
It is supported from inside by 4. The drive roller 18
The driven roller 20 is rotatably supported in parallel with a fixing device main body (not shown), and the heating roller 24 is supported by a support mechanism 36 described later. Further, a temperature detecting device 26 is provided on the outer peripheral portion of the heating roller 24,
The heater 22 is turned on / off based on the detected temperature of the outer peripheral portion of the heating roller 24. The pressure roller 28 has an outer peripheral portion of a cylindrical cored bar 30 covered with an elastic coating layer 32 such as rubber, is arranged outside the belt 14, and is in pressure contact with the heating roller 24 via the belt 14. (Hereinafter, a contact portion between the pressure roller 28 and the belt 14 is referred to as a nip portion 34.) The pressure roller 28 is supported by the support mechanism described later together with the heating roller 24.

The support mechanism 36 is shown in FIGS. The support mechanism 36 is provided with a fixed flange 38 and a moving flange 40 facing the fixed flange 38 in order to support both ends of the heating roller 24 and the pressure roller 28. Fixed flange 3
8 is fixed to the fixing device main body 42. The moving flange 40 includes a protrusion 44. On the other hand, the fixing device body 4
A guide groove 48 is formed on the base 46 fixed to the second member 2 in parallel with a plane orthogonal to the driving roller 18 and the driven roller 20.
The protrusion 44 is movably fitted. A stepping motor 50 capable of rotating in the forward and reverse directions is fixed to the base 46, and a worm gear 52 is attached to its drive shaft. Correspondingly, the moving flange 40 is provided with a rack gear 54, and the worm gear 52 is engaged with the rack gear 54, so that the moving flange 40 moves along the guide groove 48 based on the rotation of the stepping motor 50. It has become.

A bearing 56 for supporting one end of the heating roller 24 and a through hole 60 into which one end of a support shaft 58 of the pressure roller 28 is inserted are formed in the fixed flange 38. Similarly, on the moving flange 40, the heating roller 24
A bearing 62 that supports the other end of the pressure roller 28 and a through hole 64 into which the other end of the support shaft 58 of the pressure roller 28 is inserted are formed. The through holes 60 and 64 are respectively provided in the bearing 5
It has a track shape (oval shape) having a major axis in the direction toward 6, 62, and the support shaft 58 is movable in the major axis direction.

With respect to the support mechanism 36, as shown in FIG. 2, the heating roller 24 has bearings 5 at both ends thereof.
It is rotatably supported by being inserted through 6, 62. In the pressure roller 28, the ends of the support shaft 58 are inserted into the through holes 60 and 64, respectively, and the heating roller 24 is rotated by the springs 66 and 68.
Is urged towards. In addition, normally, the moving flange 4
0 is fixed at a position where the heating roller 24 and the pressure roller 28 supported by the fixing flange 38 are parallel to the driving roller 18 and the like.

In the fixing device 10 having the above structure, the drive roller 18 is rotated in the direction of arrow 70 by driving the motor 16. As a result, the belt rotates in the direction of arrow 72. In addition, the driven roller 20 that contacts the belt 14,
The heating roller 24 and the pressure roller 28 have arrows 74,
It rotates in the 76 and 78 directions. Then, when a voltage is applied to the heater 22, the heater 22 generates heat, and the heat is transmitted to the fixing belt 14 in contact with the heater 22 via the heating roller 24. Therefore, when the sheet 84 having the unfixed toner 82 is supplied to the nip portion 34 from the direction of the arrow 86 along the upstream guide 80, the toner 82 comes into contact with the fixing belt 14 at the nip portion 34 and is heated and melted. It Also,
The toner 82 melted based on the pressing force of the pressure roller 28
Permeate between the fibers of the sheet 84 and are fixed. And
The sheet 84 that has passed through the nip portion 34 receives the downstream guide 86.
And is discharged along the roller pair 88 (not shown).
Is discharged.

When the belt 14 meanders, the meandering is corrected as follows. First, in the meandering detection, for example, a detection switch such as a light detection sensor 96 is provided near the edge of the belt 14, and based on a signal from the light detection switch 96, the controller 98 detects that the belt meanders more than a predetermined amount. To detect. When the control device 98 detects that the belt 14 has meandered by a predetermined amount or more, the control device 98 drives the stepping motor 50 to move the moving flange 40, and causes the heating roller 24 and the pressure roller 28 to move to the driving roller 18 or the like. On the other hand, it is set to be oblique (that is, not parallel). As a result, the belt 14 moves in the width direction while rotating, and the meandering is corrected. At this time, the binding force of the belt 14 at the nip portion 34 is strongest,
Is a heating roller 24 and a pressure roller 28 that sandwich this.
As it moves with, the meandering is corrected in a short time. When the meandering correction is completed, the stepping motor 50 is reversely rotated to return the moving flange 40 to the original position, and the heating roller 24 and the pressure roller 28 are set parallel to the driving roller 18 and the like.

Although the heating roller 24 and the pressure roller 28 are normally held in parallel with the driving roller 18 in the above-described embodiment, the heating roller 24 and the pressure roller 28 are normally held in parallel with the driving roller 18. Is set so that the belt 14 meanders in a specific direction, and when the meandering amount of a predetermined amount or more is detected, the moving flange 40 is moved in the opposite direction (that is, The direction in which the meandering is corrected) The belt 14 may be moved to correct the meandering. The end time of the meandering correction may be defined by controlling the time from the start of the movement of the moving flange 40 to the return to the original position with a timer, or by a detection switch provided separately, the meandering amount of a predetermined amount or more. It may be the time when the completion of the correction is detected.

Further, the present invention can be applied to a belt type fixing device having a heating device 92 of another form instead of the heating roller 24 as shown in FIG. It can be applied to any device having a belt mechanism.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a fixing device.

FIG. 2 is a cross-sectional view of the fixing device shown in FIG.

FIG. 3 is a perspective view showing a mechanism that supports a heating roller and a pressure roller, and a moving flange and a mechanism that moves the moving flange.

FIG. 4 is a sectional view of another fixing device.

[Explanation of symbols]

10 ... Fixing device, 12 ... Belt mechanism, 14 ... Belt, 1
8 ... drive roller, 20 ... driven roller, 22 ... heater, 2
4 ... Heating roller, 28 ... Pressure roller, 34 ... Nip portion,
36 ... Support mechanism, 38 ... Fixed flange, 40 ... Moving flange, 50 ... Stepping motor.

Claims (1)

[Claims] 1. An endless belt, a plurality of inner supporting members for supporting the belt from the inner side, and an outer supporting member disposed outside the belt, and press-contacted to at least one of the inner supporting members via the belt. In the belt mechanism including the outer supporting member, the supporting structure integrally supporting the outer supporting member and the inner supporting member facing the outer supporting member, and the moving mechanism for inclining the supporting structure are provided. Meandering correction device.