JPH1165323A - Belt carrying device and image forming device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a belt carrying device capable of revolving an endless-like belt along a fixed path with high accuracy, while preventing the damage of projected line parts for regulating the movement in a width direction of the endless-like belt or the endless-like belt itself and an image forming device using the belt carrying device. SOLUTION: The belt carrying device is constituted of plural carrying rolls 2a-(2d), the endless-like belt 2 which is extended on these carrying rolls 2a-(2d), to be revolved and has the projected line parts 20 formed along the side edges of the inner periphery and guiding members 21 which are provided in the end parts of at least one carrying roll 2a and abutted on the projected line parts 20 of the belt 2, to restrain the movement in the width direction of the belt 2. In such a case, the carrying roll 2a provided with the guiding members 21 is of an elastic roll having plural disk-like elastic fins 23 erected in the axial direction of a rotary shaft 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt conveying device for rotating an endless belt around a plurality of conveying rolls and rotating the belt, and an image forming apparatus using the same. The present invention relates to an improvement for preventing a displacement in a width direction during rotation of the.

[0002]

2. Description of the Related Art Conventionally, as one of the color image forming apparatuses, a plurality of color toner images are superimposed on an endless intermediate transfer belt, and then these toner images are collectively transferred to a recording sheet. There is known an arrangement configured to do so. FIG. 5 shows such an apparatus.
Reference numeral 00 denotes a photosensitive drum on which an electrostatic latent image corresponding to image information is formed, and reference numerals 101 to 104 denote the electrostatic latent image as yellow Y,
A developing device for developing with each color toner of magenta M, cyan C, and black BK;
6 is a primary transfer roll for transferring the toner image T developed on the photosensitive drum 100 to the intermediate transfer belt 105;
Reference numeral 107 denotes a secondary transfer roll for transferring the toner image T on the intermediate transfer belt 105 to the recording sheet 108, and reference numeral 109 denotes a cleaner for cleaning the surface of the intermediate transfer belt 105.

In such a configuration, the toner images T of yellow Y, magenta M, cyan C, and black BK are sequentially formed on the photosensitive drum 100 at a predetermined timing for each rotation of the intermediate transfer belt 105. The image is sequentially transferred to the intermediate transfer belt 105 by the operation of the primary transfer roll 106. As a result, when the intermediate transfer belt 105 rotates four times, a combined toner image in which four color toner images overlap at a predetermined position on the belt 105 is completed. Further, while the intermediate transfer belt 105 is rotating while carrying the toner image T, the secondary transfer roll 107 and the cleaner 109 are separated from the intermediate transfer belt 105, and are placed on the intermediate transfer belt 105. Contact with the transferred toner image T is prevented.

Thereafter, when all of the four color toner images are transferred to the intermediate transfer belt 105, the secondary transfer roll 10
7 and the cleaner 109 are in contact with the intermediate transfer belt 105, and the synthetic toner image on the belt 105 is collectively transferred to the recording sheet 08. Then, this recording sheet 108
Is passed through a fixing device (not shown), so that a full-color recording image is formed on the recording sheet 108. Further, the surface of the intermediate transfer belt 105 after the synthetic toner image is collectively transferred is cleaned by the cleaner 109.

As described above, in the above color image forming apparatus, a plurality of color toner images are superimposed on the intermediate transfer belt. Therefore, in order to form a high quality color recording image without color shift, It is important that the intermediate transfer belt does not displace in the width direction during the rotation.

However, generally, when a belt formed in an endless shape is wound around a plurality of transport rolls including a driving roll and a driven roll and is rotated, a forming error of the endless belt and a diameter of the transport roll are reduced. Due to the error and the mounting angle error, a biasing force acts on the endless belt in the axial direction of the transport roll, and the endless belt moves in the axial direction of the transport roll to obtain a stable rotation position. It will be displaced.

Therefore, various proposals have been made for stably rotating the endless belt along a fixed path. One of the proposals is as shown in FIG. A ridge called a rib 111 is provided along each side edge of the peripheral surface, and a pair of these ribs 111 and 1 are provided.
11 is a belt transport in which the endless belt 110 is wound around the transport roll 112 so as to sandwich the transport roll 112 from its axial direction, and the movement of the endless belt 110 is restricted by the interference between the rib 111 and the transport roll 112. Devices are known (JP-A-62-165676, JP-A-4-257888, JP-A-5-35131, etc.). In this belt conveying device, the endless belt 11
It is not known in which direction the belt 110 will be displaced until it is actually wound around the transport roll 112 and rotated, but the ribs 111 are formed on both side edges of the endless belt 110. From the endless belt 110
Is displaced, one of the ribs 111 always interferes with the transport roll 112, and the belt 110 can be rotated stably.

[0008]

By the way, in such a conventional belt conveying device, the rib is usually fixed to the side edge of the inner peripheral surface of the endless belt with an adhesive or the like. Also, it is difficult to fix the ribs in such a manner that the ribs perfectly match the rotation direction of the endless belt due to the processing accuracy of the side edges of the endless belt, the mounting accuracy of the ribs, and the like. That is, as shown in FIG.
The side surface 1 is not completely parallel to the rotation direction of the endless belt 110, but has a slight undulation in the rotation direction.

Therefore, when the endless belt is rotated while causing the ribs to interfere with the end of the transport roll, the endless belt is attached to the rib in the axial direction of the transport roll in order to cope with the aforementioned undulation of the rib side surface. A load F that is to be moved along is applied. However, the endless belt is stretched around a transport roll under a predetermined tension, and a large frictional force f acts between the endless belt and the roll. The endless belt does not move in the axial direction of the transport roll unless the frictional force f is exceeded. For this reason, troubles such as the ribs being peeled off from the endless belt by the load F or being extremely worn occur, and it has been difficult to accurately rotate the endless belt along a certain path. There is also a problem that the endless belt itself is broken by the load F.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing problems, and has as its object to damage a ridge that restricts movement of an endless belt in the width direction or damage an endless belt itself. It is an object of the present invention to provide a belt conveying device capable of rotating such an endless belt along a predetermined path with high accuracy while preventing the occurrence of a belt, and an image forming apparatus using the same.

[0011]

In order to achieve the above object, a belt conveying device according to the present invention comprises a plurality of conveying rolls,
An endless belt in which a ridge is formed along the side edge of the inner peripheral surface while rotating around these transport rolls, and an endless belt provided at an end of at least one transport roll. A guide member that abuts on the ridge portion and locks the movement of the endless belt in the width direction, wherein the transport roll provided with the guide member extends along the axial direction of the rotating shaft. A plurality of disk-like elastic fins.

According to such technical means, a ridge is provided on the inner peripheral surface of the endless belt along a side edge thereof, and the end of the transport roll around which the endless belt is wound. Since the portion is provided with a guide member that comes into contact with the ridge, the endless belt rotates along a fixed path without meandering in the width direction while the ridge is in contact with the guide member.

At this time, a load F due to a molding error of the ridge portion or an attachment error to the endless belt is applied to the ridge portion in the axial direction of the transport roll (the width direction of the endless belt). However, in the present invention, since the transport roll provided with the guide member is an elastic roll, that is, a roll in which a plurality of disk-shaped elastic fins are erected along the axial direction of the rotating shaft, the load F described above is reduced. When acting on the ridge, the elastic fin bends in the axial direction of the rotating shaft, and the load F acting on the ridge is reduced. Thus, the protrusion F can be prevented from being peeled off from the endless belt by the load F, or the endless belt itself can be prevented from breaking.

On the other hand, such a belt conveying apparatus of the present invention can be used in an image forming apparatus such as a copying machine or a printer, and can be used for an intermediate transfer belt conveying apparatus for transferring a toner image from an image carrier to a recording sheet. It can be used as a photosensitive belt conveying device.

That is, the image forming apparatus of the present invention using such a belt transport device as a transport device for an intermediate transfer belt includes an image carrier on which a toner image is formed based on image information and the belt transport device of the present invention. An image forming apparatus which is arranged adjacent to the image forming apparatus, wherein the toner image is primarily transferred from the image carrier to an endless belt, and then the toner image is secondarily transferred from the endless belt to a recording sheet. The elastic roll is adjacent to the upstream side of the primary transfer position of the toner image in the rotation direction of the endless belt.

Further, the image forming apparatus of the present invention using such a belt conveying device as a photoreceptor belt conveying device,
After exposing the endless photoreceptor belt based on the image information to form an electrostatic latent image, the electrostatic latent image is developed to form a toner image, and the toner image is transferred from the photoreceptor belt to a recording sheet. An image forming apparatus configured to perform transfer, wherein the elastic roll is adjacent to an upstream side of the exposure position with respect to a rotation direction of the endless belt.

According to the image forming apparatus of the present invention configured as described above, the elastic roll provided with the guide member is used to expose the primary transfer position of the toner image to the intermediate transfer belt or to expose the electrostatic latent image to the photosensitive belt. Since the belt is adjacent to the upstream side of the position, the displacement in the width direction of these belts can be corrected at the upstream side of the toner image transfer position or the exposure position, and the transfer position shift of the toner image on the intermediate transfer belt and Image shift of the electrostatic latent image on the photoreceptor belt can be effectively prevented.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a belt conveying apparatus according to the present invention. FIG. 1 shows a schematic configuration of a color image forming apparatus using the belt conveying device of the present invention as an intermediate transfer belt for a toner image. Reference numeral 1 denotes a photosensitive drum (latent image carrier), and an electrostatic latent image corresponding to image information is formed on the surface of the photosensitive drum by a well-known electrophotographic process (not shown) with rotation in the direction of arrow A. Is done. That is, the photosensitive drum 1
Is charged to a predetermined dark potential by the charger 1a,
Exposure according to an image signal is performed by a light beam Bm emitted from a laser beam scanner (not shown). Also,
Around the photosensitive drum 1, developing devices 5 to 8 corresponding to black (Bk), yellow (Y), magenta (M), and cyan (C) are provided. The formed electrostatic latent image is developed by any one of the developing devices to form a toner image T. Therefore, if the electrostatic latent image written on the photosensitive drum 1 corresponds to the yellow image information, this electrostatic latent image is developed by the developing device 6 containing yellow (Y) toner, and A yellow toner image is formed on the body drum 1.

Reference numeral 2 denotes an endless intermediate transfer belt disposed so as to be in contact with the surface of the photosensitive drum 1, and is stretched over a plurality of transport rolls 2a to 2d including a driving roll and a driven roll. Then, it turns in the direction of arrow B. The unfixed toner image T formed on the photosensitive drum 1 is transferred from the photosensitive drum 1 to the surface of the intermediate transfer belt 2 at a primary transfer position where the photosensitive drum 1 contacts the intermediate transfer belt 2. At this primary transfer position, the intermediate transfer belt 2
A primary transfer roll 9 is disposed on the back surface of the photosensitive drum 1. By applying a voltage having a polarity opposite to the charging polarity of the toner to the primary transfer roll 9, the unfixed toner image T
Is electrostatically attracted to the intermediate transfer belt 2.

When a single color image is formed, the unfixed toner image T primarily transferred to the intermediate transfer belt 2 is secondarily transferred to the recording sheet 3 immediately. When the toner image is formed, the formation of the toner image on the photosensitive drum 1 and the primary transfer process of the toner image are repeated for the number of colors. For example, when a full-color image is formed by superimposing toner images of four colors, unfixed toner images T of black, yellow, magenta, and cyan are formed on the photoreceptor drum 1 every one rotation thereof. The image T is sequentially primary-transferred onto the intermediate transfer belt 2. On the other hand, the intermediate transfer belt 2 rotates at the same cycle as the photosensitive drum 1 while holding the first untransferred black unfixed toner image T, and the intermediate transfer belt 2
The yellow, magenta, and cyan unfixed toner images T are transferred onto the black unfixed toner image T on each rotation.

The unfixed toner image T primarily transferred to the intermediate transfer belt 2 in this manner is conveyed to a secondary transfer position facing the conveyance path of the recording sheet 3 with the rotation of the intermediate transfer belt 2. You. At the secondary transfer position, a semiconductive secondary transfer roll 10 is in contact with the intermediate transfer belt 2, and the tray 12 is moved by a feed roll 11 at a predetermined timing.
The recording sheet 3 carried out from the secondary transfer roll 10
And the intermediate transfer belt 2. Further, the transport roll 2d facing the secondary transfer roll 10 with the intermediate transfer belt 2 interposed therebetween forms an opposite electrode of the secondary transfer roll, and the secondary transfer roll 10 has a polarity opposite to the charging polarity of the toner. When a voltage is applied, the unfixed toner image T carried on the intermediate transfer belt 2 is electrostatically transferred to the recording sheet 3 at the secondary transfer position.

Then, the recording sheet 3 to which the unfixed toner image has been transferred is peeled off from the intermediate transfer belt 2 and sent to a fixing device (not shown) to perform a fixing process of the unfixed toner image. On the other hand, the residual toner is removed by the cleaner 15 from the intermediate transfer belt 2 on which the secondary transfer of the unfixed toner image has been completed.

In the above configuration, the secondary transfer roll 1
0 and the cleaner 15 are disposed so as to be able to freely contact and separate from the intermediate transfer belt 2. When a color image is formed, these members are used until the final unfixed toner image is primarily transferred to the intermediate transfer belt 2. Is separated from the intermediate transfer belt 2.

Next, a structure for stably rotating the intermediate transfer belt 2 along a fixed path without displacing the intermediate transfer belt 2 in the width direction will be described. As shown in FIG. 2, on the inner peripheral surface of the intermediate transfer belt 2, ribs (protrusions) 20 of ridges are fixed along both side edges with an adhesive, while the intermediate transfer belt 2 is hung. Disc-shaped guide members 21 and 21 are provided at both end portions of the transported roll 2 a to be in contact with the side surfaces of the rib 20. The guide member 21 is rotatably mounted on the rotation shaft 22 of the transport roll 2a, and is rotated by being rotated by the rib 20 that comes into contact with the guide member 21, so that the wear of the rib 20 is suppressed as much as possible. .

Here, when the intermediate transfer belt 2 is rotated, a biasing force acts on the intermediate transfer belt 2 along the axial direction of the transport roll 2a, and the biasing force is caused by a molding error of the intermediate transfer belt 2. And the error of the diameter of the transport rolls 2a to 2d, the mounting angle error, and the like, and the generation direction is unique to each device. Therefore, the intermediate transfer belt 2 moves in the axial direction of the transport roll 2a in search of a stable rotation position, but the movement direction is only one direction, and the intermediate transfer belt 2 is in one of the directions. The movement in the width direction is locked in a state in which the rib 20 provided on the side edge of the abutment is brought into contact with the guide member 21, and thereafter, a stable path is stably rotated while maintaining the same state. Become.

However, since it is difficult to completely eliminate a molding error of the side edge of the intermediate transfer belt 2 and a mounting error of the rib 20 itself, it comes into contact with the guide member 21 as shown in FIG. A slight undulation exists in the side surface of the rib 20 in the conveyance direction of the intermediate transfer belt 2. Accordingly, during the rotation of the intermediate transfer belt 2, the intermediate transfer belt tries to move in the width direction due to the undulation of the side surface of the rib 20, while the inner circumferential surface of the intermediate transfer belt and the transport roll are not moved. Since a large frictional force acts between the ribs, an extremely large load acts on the ribs 20 unless the intermediate transfer belt slips on the transport roll.

For this reason, in this embodiment, in order to enable the intermediate transfer belt 2 to slightly move in the width direction corresponding to the undulation of the rib 20, the structure of the transport roll 2a provided with the guide member 21 is provided. Is special. Specifically, as shown in FIG. 2, a plurality of disc-shaped elastic fins 23 are formed along the axial direction of the rotating shaft 22 as an elastic roll, and each elastic fin 23 has its tip at the intermediate transfer belt 2. The structure was designed to support Each of the elastic fins 23 is equally divided into a plurality of pieces along the circumferential direction, and each of the divided segments can be individually bent in response to an external force. The elastic roll 2a is manufactured by using injection molding. First, an elastic fin 23 made of rubber or a soft synthetic resin is thickened around the rotation shaft 22, and then the outer peripheral surface of the erected elastic fin 23 is removed. It is manufactured by polishing or grinding to a predetermined outer diameter.

When an elastic roll having such a structure is used as the transport roll 2a provided with the guide member 21, the elastic fins 23 are easily bent in the direction by an external force acting in the axial direction of the transport roll 2a. From
As shown in FIG. 3, when the intermediate transfer belt 2 attempts to move in the direction of arrow C in response to the undulation of the side surface of the rib 20,
Although no slip occurs between the elastic fins 23 and the intermediate transfer belt 2, the intermediate transfer belt 2 can be slightly moved in the width direction by bending of the elastic fins 23.

As a result, in the image forming apparatus of the present embodiment, a large load is not applied to the rib 20 while the intermediate transfer belt 2 is rotating, and the rib 20
Is peeled off from the intermediate transfer belt 2 or the intermediate transfer belt 2
It is possible to effectively avoid breakage itself.

In the image forming apparatus of this embodiment, the guide member 21 may be provided not only on the transport roll 2a but also on all of the other transport rolls 2b to 2d. However, in this case, all of the transport rolls 2b to 2d need to be the elastic rolls shown in FIG.

If the guide member 21 is provided on any one of the transport rolls, it is possible to prevent the intermediate transfer belt from being displaced in the width direction, but in such a case, the transport is performed as in the above-described embodiment. It is preferable to provide the guide member 21 for the roll 2a, that is, the transport roll adjacent to the primary transfer position of the toner image and located upstream of the primary transfer position in the rotation direction of the intermediate transfer belt 2. If a guide member is provided for the transport roll 2a, the intermediate transfer belt 2 passes through the primary transfer position of the toner image immediately after the position in the width direction is corrected by the guide member 21, so that the width of the intermediate transfer belt is The transfer position deviation of the toner image in the direction can be effectively prevented.

FIG. 4 shows an example of an image forming apparatus in which the belt conveying device of the present invention is applied to an endless photosensitive belt. In the figure, reference numeral 30 denotes a photosensitive belt formed endlessly, reference numeral 31 denotes a charging corotron for uniformly charging the photosensitive belt, and reference numeral 32 denotes a photosensitive beam formed on the photosensitive belt 30 by a light beam Bm. Reference numeral 33 denotes a transfer corotron for transferring a toner image formed on the photoreceptor belt 30 by development to a recording sheet 34, and reference numeral 35 denotes cleaning of toner remaining on the photoreceptor drum 30. Cleaner to do.

In the image forming apparatus thus constructed, the ribs are provided along both side edges of the inner peripheral surface of the photoreceptor belt 30, while the transport rolls 30a to 30c around which the photoreceptor belt 30 is wound. A guide member that abuts the rib on any one or all of the transport rolls,
By using the elastic roll shown in FIG. 2 for the transport roll provided with such a guide member, it is possible to prevent the photosensitive belt 30 from being damaged and to prevent the belt 30 from moving in the width direction. You can do it.

If a guide member is provided on any one of the transport rolls, it is possible to prevent the photosensitive belt from being displaced in the width direction.
0a, that is, it is preferable to provide a guide member for a transport roll adjacent to the exposure position for the photosensitive belt 30 and located upstream of the exposure position in the rotation direction of the photosensitive belt 30. If a guide member is provided for such a transport roll 30a, the photosensitive belt 30 passes through the exposure position immediately after its position in the width direction is corrected by the guide member, as in the previous embodiment. The displacement of the writing position of the electrostatic latent image in the width direction of 30 can be effectively prevented.

[0035]

As described above, according to the belt conveying apparatus and the belt conveying apparatus of the present invention, the ridge provided on the endless belt and the guide member provided at the end of the conveying roll are brought into contact with each other. In preventing the endless belt from being displaced in the width direction, since the transport roll provided with the guide member is configured as an elastic roll having a plurality of disk-shaped elastic fins, the endless belt rotates during rotation. In addition, the load acting on the ridge can be reduced, and the ridge can be effectively prevented from peeling off from the endless belt or breaking the endless belt itself.

Further, according to the image forming apparatus using the belt conveying device of the present invention, the transfer position of the toner image on the intermediate transfer belt or the exposure position of the electrostatic latent image on the photosensitive belt in the width direction of these belts. Since the movement can be effectively prevented, it is possible to form a high-quality recorded image without color shift or image position shift with respect to the recording sheet.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of an image forming apparatus using a belt conveyance device of the present invention as an intermediate transfer belt for a toner image.

FIG. 2 is a diagram illustrating a state in which an intermediate transfer belt is wound around an elastic roll according to the embodiment.

FIG. 3 is an enlarged cross-sectional view illustrating a state in which an elastic fin of an elastic roll according to an embodiment is bent and the intermediate transfer belt is moved in a width direction.

FIG. 4 is a schematic view showing an embodiment of an image forming apparatus using the belt conveyance device of the present invention as a photosensitive belt.

FIG. 5 is a schematic view showing a conventional color image forming apparatus using an intermediate transfer belt.

FIG. 6 is a diagram illustrating a main part of a conventional belt transport device in which a rib is formed on an inner peripheral surface of an endless belt.

FIG. 7 is an enlarged view showing occurrence of undulation in a belt conveyance direction of a rib fixed to a side edge of the endless belt.

[Explanation of symbols]

2. Intermediate transfer belt, 2a to 2d: transport roll, 20 ...
Rib, 21: guide member, 22: rotating shaft, 23: elastic fin

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Shinichi Kanaya 2274 Hongo, Ebina City, Kanagawa Prefecture, within Fuji Xerox Co., Ltd. (72) Inventor Takahiko Tatsuzaki 2274 Hongo, Ebina City, Kanagawa Prefecture, within Fuji Xerox Co., Ltd.

Claims (3)

[Claims] 1. An endless belt having a plurality of transport rolls, an endless belt that is wound around these transport rolls, and has a ridge formed along a side edge of an inner peripheral surface, and at least one transport roll. A guide member provided at an end portion and comprising a guide member that abuts on a ridge portion of the endless belt and locks movement of the endless belt in a width direction, wherein the guide member is provided. A belt transport device, wherein the transport roll is an elastic roll in which a plurality of disk-shaped elastic fins are erected along an axial direction of a rotating shaft. 2. An image carrier on which a toner image based on image information is formed and a belt conveying device according to claim 1 are disposed adjacent to each other, and a toner image is primarily transferred from said image carrier to an endless belt. And an image forming apparatus configured to secondarily transfer the toner image from the endless belt to the recording sheet, wherein the elastic roll is located at a primary transfer position of the toner image with respect to a rotation direction of the endless belt. An image forming apparatus which is adjacent to an upstream side. 3. An electrostatic latent image formed by exposing the endless belt of the belt conveying device according to claim 1 to a photosensitive belt based on image information to form an electrostatic latent image. An image forming apparatus configured to form a toner image by developing the endless belt with respect to a rotation direction of the endless belt. An image forming apparatus, which is adjacent to an upstream side of the image forming apparatus.