JP4760144B2 - Belt drive device and image forming apparatus - Google Patents

Description

  The present invention relates to a belt driving device, and more particularly to a belt driving device such as an intermediate transfer belt incorporated in an image forming apparatus such as a copying machine or a printer, and an image forming apparatus including the belt driving device.

  In recent years, various technologies have been developed along with the demand for higher image quality in color image forming apparatuses. One of them is the thinning of the intermediate transfer belt. The intermediate transfer belt is stretched endlessly by a plurality of rollers including a driving roller and a driven roller, and is rotationally driven in one direction to form Y (yellow), M (magenta), C ( Cyan and K (black) toner images are transferred by electrostatic force applied from a transfer roller. During this transfer, if the pressing force of the transfer roller against the photosensitive drum is too strong, the intermolecular force between the toners becomes stronger than the electrostatic force, resulting in a void phenomenon in which the central portion of the toner image becomes defective in transfer. To do.

  In order to prevent such a hollowing out phenomenon, it is effective for the present inventors to reduce the thickness of the intermediate transfer belt. A thin intermediate transfer belt having a thickness of about 85 μm to a thickness of about 100 to 150 μm is conventionally used. It has been found that a certain high image quality can be achieved by use.

  By the way, conventionally, the meandering or skewing of the intermediate transfer belt is regulated by color members provided at both ends of the roller, and this kind of meandering regulation technology is disclosed in Patent Document 1. FIG. 14 shows a configuration of an end portion of a driving or driven roller 100 of a belt driving device conventionally used. The roller 100 is held by a support shaft 101 and the surface of a cylindrical cored bar 102 is covered with an elastic material 103. A collar member 105 that is in contact with the end of the core metal 102 is rotatably attached to the support shaft 101. The meandering of the intermediate transfer belt 110 is restricted when the guide ribs 111 attached to the inner surfaces of both end edges of the intermediate transfer belt 110 abut on the inclined surface 105 a of the collar member 105.

However, if dust such as toner scattered in the machine enters the contact surface 115 between the collar member 105 and the cored bar 102, the collar member 105 may become loose or uneven in rotation, and the guide rib 111 may be colored. There is a problem in that the intermediate transfer belt 110 is cracked by riding on the outer peripheral surface of the member 105.
JP 2002-132057 A

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a belt driving device and an image forming device capable of effectively controlling the meandering of the belt member so as not to cause rattling or unevenness in the rotation of the collar member for regulating the meandering with respect to the belt member. To provide an apparatus.

In order to achieve the above object, the present invention stretches a belt member endlessly to a plurality of rollers including a driving roller and a driven roller, and rotates the belt member in one direction by a rotational driving force from the driving roller. In a belt driving device that regulates meandering of the belt member by a collar member that is rotatably provided at both ends of the roller, the collar member is rotatable on a support shaft of the roller so as to be in contact with the end of the roller. It is mounted | worn and it has a cap part which has the recessed part which can insert the edge part of the said roller, It is characterized by the above-mentioned.

  In the belt driving device according to the present invention, since the collar member has a cap portion that covers the end portion of the roller that drives or supports the belt member, the contact surface between the collar member and the roller is covered with the cap member. Dust such as toner is prevented from entering from the contact surface. Thereby, the meandering regulation of the belt member by the collar member can be effectively maintained without causing rattling or unevenness in the rotation of the collar member.

  In the belt driving device according to the present invention, the roller can be preferably used by coating the surface of a metal metal core with an elastic material, and the collar member covers both ends of the metal core. Should be provided.

  In addition, a lubricant may be applied to the collar member. The rotation of the color member can be made smooth. The lubricant is preferably applied to the inner surface of the collar member and the surface facing the cored bar.

  An uneven or stepped step portion may be formed on the inner surface side of the color member and facing the cored bar. Intrusion of dust can be more effectively prevented.

  An image forming apparatus according to the present invention includes the belt driving device.

  Embodiments of a belt driving device and an image forming apparatus according to the present invention will be described below with reference to the accompanying drawings.

(Schematic configuration of image forming apparatus, see FIG. 1)
The image forming apparatus shown in FIG. 1 is an electrophotographic color printer, and includes a printer main body 1 configured to synthesize four-color images in a so-called tandem system, an image reading device 2, and a control unit 3. Has been.

  The image reading device 2 is a well-known device that reads an image of an original placed on an original platen glass (not shown) by an image sensor such as a CCD element. The original image is RGB (red, green, blue) by the image sensor. They are separated into the three primary colors and converted into electrical signals. The image data is subjected to various types of data processing in the control unit 3 and further converted into YMCK (yellow, magenta, cyan, black) reproduction colors. The YMCK image data is stored in the memory 4 of the control unit 3 and subjected to necessary correction such as misalignment correction.

  In the printer main body 1, a print head 30 (30Y, 30M, 30C, 30K) that forms a YMCK image including a photosensitive drum 31, a laser scanning optical device 32, a developing device 33, and the like is juxtaposed directly below the intermediate transfer belt 10. ing. In each print head 30, the laser scanning optical device 32 receives the transfer of the YMCK image data, forms a latent image on the photosensitive drum 31, and forms a toner image by the developing device 33. Such an electrophotographic process is well known and will not be described.

  The intermediate transfer belt 10 is stretched endlessly between a driving roller 21 and a driven roller 25 for applying tension, and is rotationally driven in the direction of arrow A by a rotational driving force transmitted from the driving roller 21. On the inner surface side of the intermediate transfer belt 10, primary transfer rollers 18 are disposed at positions facing the respective photosensitive drums 31.

  A secondary transfer roller 19 is disposed on the intermediate transfer belt 10 at a portion facing the driving roller 21. Further, a cleaning blade 15 for wiping the residual toner comes into contact with the intermediate transfer belt 10 at a portion facing the driven roller 25, and the toner wiped by the blade 15 is accommodated in a waste bottle 16.

  An automatic paper feed unit 40 that feeds the stacked sheets one by one is installed in the lower stage of the printer body 1. Further, a fixing unit 50 for heating and fixing the toner is disposed immediately above the secondary transfer portion.

  The toner images formed on the respective photosensitive drums 31 are sequentially primary-transferred onto the intermediate transfer belt 10 that is rotationally driven in the direction of arrow A, and four color images are combined. On the other hand, the sheets are fed one by one from the automatic sheet feeder 40, and the composite toner image is secondarily transferred from the intermediate transfer belt 10 in the secondary transfer section. Thereafter, the sheet is conveyed to the fixing unit 50 to heat and fix the toner image, and is discharged from the discharge roller 51 onto the tray 52.

(Belt drive unit, see FIGS. 2 and 3)
As shown in FIG. 2, the intermediate transfer belt 10 is stretched endlessly between a driving roller 21 and a driven roller 25 that applies tension to the belt 10, and in order to restrict meandering when rotating in the direction of arrow A, Rubber guide ribs 11 are provided on the back side of the belt 10 and around the entire periphery of both end edges. The rollers 21 and 25 are attached to the support shafts 22 and 26, respectively, and a rotational force is transmitted to the support shaft 22 by a transmission means (not shown).

  Further, collars 27 for receiving the guide ribs 11 are provided at both ends of the rollers 21 and 25. The collar 27 is made of, for example, polyacetal resin, and as shown in FIG. 3, a regulation surface 27a having an angle θ1 is formed on the outer surface thereof. The regulation surface 27a is opposed to the corner portion 11a of the guide rib 11. Yes. The restricting surface 27a is an inclined plane, and the upper portion thereof has a circular arc shape with a radius R.

  The guide rib 11 is made of urethane rubber, and is adhered to the rear edge of the intermediate transfer belt 10 with an adhesive. When the intermediate transfer belt 10 rotates meandering (meandering force F1) and tries to move in the width direction of the belt 10, the corner portion 11a of the guide rib 11 opposite to the moving direction is on the regulating surface 27a of the collar 27. By pressure contact, the meandering of the belt 10 is regulated.

  FIG. 3 shows a state in which the collar 27 restricts the meandering of the intermediate transfer belt 10. When the intermediate transfer belt 10 is rotated by the driving force transmitted from the driving roller 21, the guide ribs 11 provided at both edge portions on the back surface of the belt 10 are wound around the collar 27, and the corner portion 11 a is dotted by the meandering force F 1. The meandering is regulated while being deformed as shown in. Such deformation of the guide rib 11 occurs when the belt tension F4 overcomes the force obtained by combining the collar reaction force F2 and the curvature reaction force F3 of the belt 10 itself.

  By the way, when dust such as toner enters the contact surfaces (indicated by reference numeral 115 in FIG. 14) between the rollers 21 and 25 and the collars 27 provided at both ends thereof, the collars 27 become loose and uneven. As a result, an imbalance occurs in the forces F1 to F4 and the guide rib 11 rides on the outer peripheral surface of the collar 27.

  Therefore, in the present invention, a cap portion that covers the end portions of the rollers 21 and 25 is formed on the collar 27 to prevent intrusion of dust such as toner. Examples 1 to 10 will be described below with reference to FIGS. In the first to tenth embodiments, the driving roller 21 and the collar 27 provided on the driving roller 21 will be described. Of course, the same configuration can be adopted for the driven roller 25 and the collar provided thereon.

(Refer to Examples 1, 2, FIG. 4 and FIG. 5)
The roller 21 is obtained by coating the surface of a cylindrical metal core 23 with an elastic material 24, and the collar 27 is rotatably mounted on the support shaft 22 so as to contact the end of the metal core 23. In Examples 1 and 2, cap portions 27b each having a recess 27c into which the end portion of the core metal 23 can be inserted are provided in the collar 27. Thus, it is possible to prevent dust such as toner from entering the contact surface 28 between the collar 27 and the end surface of the cored bar 23. Also in Examples 2 to 10 below, it is possible to prevent dust from entering the contact surface 28.

(See Example 3, FIG. 6)
The third embodiment is the same as the first and second embodiments in that the collar 27 is provided with a cap portion 27b having a concave portion 27c into which the end portion of the core metal 23 can be inserted. It extends to the vicinity of the elastic member 24 to prevent the entry of dust such as toner as much as possible.

(See Example 4, FIG. 7)
In the fourth embodiment, a threaded uneven portion 27d is formed on the inner peripheral surface of the recessed portion 27c formed in the cap portion 27b of the collar 27.

(See Example 5, FIG. 8)
In the fifth embodiment, a stepped portion 27e is formed in the concave portion 27c formed in the cap portion 27b of the collar 27, and a stepped portion 23a corresponding to the stepped portion 27e is formed at the end of the core metal 23.

(See Example 6, FIG. 9)
In the sixth embodiment, the concave portion 27c of the cap portion 27b of the collar 27 is formed as a tapered surface, and the tapered surface 23b corresponding to the end portion of the core metal 23 is formed.

(See Example 7, FIG. 10)
In the seventh embodiment, a tapered convex portion 27 f is formed in the concave portion 27 c of the cap portion 27 b of the collar 27, and a tapered surface 23 c corresponding to the end portion of the core metal 23 is formed.

(See Example 8, FIG. 11)
In the eighth embodiment, the convex portion 27g is formed in the concave portion 27c of the cap portion 27b of the collar 27, and the concave portion 23d corresponding to the end portion of the core metal 23 is formed.

(See Example 9, FIG. 12)
In the ninth embodiment, an annular protrusion 27 h is formed in the recess 27 c of the cap portion 27 b of the collar 27, and an annular recess 23 e in which the protrusion 27 h is fitted is formed at the end of the core metal 23.

(See Example 10, FIG. 13)
In the tenth embodiment, the bulging portion 23f chamfered at the end of the core metal 23 is formed, and the concave portion 27c of the cap portion 27b of the collar 27 is formed in a shape corresponding to the bulging portion 23f.

(lubricant)
By the way, it is preferable that a lubricant is applied to the collar 27 in order to make its rotation smooth. In particular, it is more preferably applied to the inner peripheral surface of the collar 27 and the surface facing the core metal 23.

(Other examples)
The belt driving device according to the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the gist thereof. In particular, materials such as the intermediate transfer belt, the guide rib, and the meandering restriction roller are arbitrary.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to the present invention. It is the perspective view which notched a part which shows an example of the belt drive device concerning the present invention. It is sectional drawing which shows the principal part of the said belt drive device. It is sectional drawing of the principal part which shows Example 1 of this invention. It is sectional drawing of the principal part which shows Example 2 of this invention. It is sectional drawing of the principal part which shows Example 3 of this invention. It is sectional drawing of the principal part which shows Example 4 of this invention. It is sectional drawing of the principal part which shows Example 5 of this invention. It is sectional drawing of the principal part which shows Example 6 of this invention. It is sectional drawing of the principal part which shows Example 7 of this invention. It is sectional drawing of the principal part which shows Example 8 of this invention. It is sectional drawing of the principal part which shows Example 9 of this invention. It is sectional drawing of the principal part which shows Example 10 of this invention. It is sectional drawing which shows the principal part of the conventional belt drive device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Printer main body 10 ... Intermediate transfer belt 11 ... Guide rib 21 ... Drive roller 22 ... Support shaft 23 ... Core metal 24 ... Elastic material 25 ... Driven roller 27 ... Collar 27a ... Serpentine regulation surface 27b ... Cap part

Claims (6)

A belt member is stretched endlessly around a plurality of rollers including a driving roller and a driven roller, and the belt member is rotated in one direction by a rotational driving force from the driving roller. In a belt driving device that regulates meandering of the belt member by a member,
The collar member is rotatably mounted on a support shaft of the roller so as to be in contact with the end of the roller, and has a cap portion having a recess into which the end of the roller can be inserted ;
A belt driving device characterized by the above.   2. The roller according to claim 1, wherein an elastic material is coated on a surface of a metal cored bar made of metal, and the collar member is provided so as to cover both ends of the cored bar. Belt drive device.   The belt driving device according to claim 1, wherein a lubricant is applied to the collar member.   4. The belt driving device according to claim 3, wherein the lubricant is applied to an inner surface side of the collar member and a surface facing the cored bar.   The belt according to any one of claims 2 to 4, wherein an uneven or stepped step portion is formed on an inner surface side of the collar member and facing the cored bar. Drive device.   An image forming apparatus comprising the belt driving device according to claim 1.

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