JP2001163424A - Belt conveying device and image forming device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a belt conveying device and an image device by using it, which can control the meandering excellently while reducing an occurrence of damage in a belt and implement a stable rotation traveling in an endless belt for the long term. SOLUTION: A rib member 50 is provided along with both edges of the inner circumferential surface of an intermediate transfer belt 21 in an image forming device and a rib guide part 60 having a taper guide surface 61, is provided, in which an inner tip 50a in the rib member 50 is guided while it is abutted on both the ends of plural supporting rolls 23, 25 including a driving roll 22. The taper angle in a taper guide surface 61 shall be formed within an angle of 2×(45 deg.-70 deg.), and the rib guide part 60 is provided so as to be an independent structure and freely rotated to the roll.

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 carrying an object to be conveyed by carrying it on an endless belt, and a belt conveying device for carrying an object to be carried such as a toner image or a recording medium by carrying it on an endless belt. The present invention relates to an image forming apparatus such as a copying machine and a printer using the same.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine or a printer using an electrophotographic system or the like, a toner image or a recording medium (paper, etc.) is transferred by an endless belt such as a photosensitive belt, an intermediate transfer belt, and a paper transfer belt. ) That uses a belt conveying device that carries and conveys. In these belt conveyance devices, each endless belt is usually stretched around a plurality of support rolls including a drive roll and rotated.

[0003] In addition, since this type of belt conveying device sometimes passes an endless belt through a process that requires positional accuracy, such as formation and transfer of a toner image, the endless belt is preferably moved in the axial direction of the roll. It is necessary to suppress the so-called meandering, which runs in one direction, as much as possible. As a measure to suppress such a deviation (meandering), a protruding portion is mainly provided along both edges of the inner peripheral surface of the endless belt (for example, an elongated plate-shaped member is fixed to the inner peripheral surface of the belt). Then, the endless belt is rotated so that the inner wall surface of the protruding portion can be brought into contact with both end surfaces of the support roll.

[0004]

However, in a belt conveyance device employing such a meandering prevention structure,
As illustrated in FIG. 9A, the inner wall surface of the protrusion 120 of the endless belt 100 and both end surfaces (vertical guide surfaces) of the support roll 130 are brought into contact in parallel with each other to suppress meandering. Of the endless belt 100 is sometimes deformed so that a part 110 of the endless belt 100 rises when the protruding portion 120 is slightly raised on the end face of the roll 130. I will be. If the belt travel continues for a long time in a state in which such stress concentration or the like has occurred, the endless belt 100 cannot withstand the state and breaks such as a crack (a portion indicated by reference numeral 140 in FIG. 9B) occurs. The belt cannot be used, and the image forming operation itself cannot be performed. Endless belt breakage due to such stress concentration and the like is more likely to occur particularly when the mechanical strength of the belt itself has been reduced due to long-term use.

[0005] Incidentally, Japanese Patent Laid-Open No. 10-104995 discloses a rotating member (support roll) 1 as shown in FIG.
The protrusion (rib member) 1 of the endless belt 100
A belt rotation driving device or the like in which a stepped portion 160 for guiding the guide 20 is provided and the stepped portion 160 is formed in a tapered shape is shown. In this device, the endless belt 1
In this case, stable rotation driving can be performed by guiding the convex portion 120 of the “00” into contact with the stepped portion 160, and the stepped portion 160 is formed into a tapered shape so that the suddenly convex portion is formed by the stepped portion 160. Prevent the 120 from getting on,
The influence of the change in the position of the stepped portion 160 on each of the rotating members 150 prevents the protrusions 120 on the other rotating members 150 from running over.

However, as in this device, the endless belt 10
In the case where the convex portion 120 is brought into contact with the stepped portion 160 and guided, the convex portion 120 and the stepped portion 160 come into surface contact with each other. It is easy to be reflected in. That is, for example, the protrusion 12
If there is a variation in the height of 0, the convex portion 1
The effect of the shape accuracy of 20 is reflected on the endless belt 100 without being absorbed by the stepped portion 160,
On the contrary, the belt may meander. In addition, even when the dimensional accuracy of the stepped portion 160 is poor, the convex portion 120 is strongly affected by the shape accuracy of the stepped portion 160, which may cause the belt to meander. In addition, in the case where the endless belt 100 is guided as described above, the rotational movement speed (peripheral speed) governed by the contact of the endless belt 100 with the rotating member 150 and the protrusion 1
A speed difference occurs between the endless belt 1 and the rotational movement speed governed by the abutment with the stepped portion 160 (consisting of a stepped surface having a diameter smaller than the outer diameter of the rotating member 150).
00 may become unstable, or the stress due to the speed difference may concentrate on the belt joining portion of the convex portion 120 and cause damage to the belt.

[0007] Accordingly, the present invention has been made in view of the above-mentioned circumstances, and it is possible to suppress the meandering in which the belt is less likely to be broken, and to realize the stable rotation of the endless belt for a long period of time. It is an object of the present invention to provide a belt transport device capable of performing the following.

Further, the present invention realizes a stable rotation running without breakage or meandering of the endless belt for a long period of time even when using a belt conveying device for conveying a toner image, a recording medium, etc. by an endless belt. It is another object of the present invention to provide an image forming apparatus capable of stably performing good image formation without any trouble caused by the endless belt.

[0009]

According to the present invention, there is provided a belt conveying apparatus comprising: an endless belt for carrying an object to be conveyed; and a driving roll for stretching the endless belt to rotate and run. A belt transport device comprising: a support roll, wherein a protrusion is provided along both end edges of an inner peripheral surface of the endless belt, and an inner front end of the protrusion is provided at at least one roll end of the support roll. A guide portion having a tapered guide surface on which the portion abuts and is guided is provided.

According to this belt conveying device, the protruding portion provided on the endless belt is guided in a state where only the inner front end portion is in contact with the tapered guide surface of the guide portion. Accordingly, the vicinity of the joint of the protruding portion with the endless belt does not directly contact the guide portion, and the tip of the inner side of the protruding portion rarely runs on the inclined tapered guide surface. As a result, the belt is less likely to be damaged due to stress concentration near the belt joining portion of the protrusion and deformation at the time of riding, and at the same time, the protrusion is accurately guided by the tapered guide surface.

Further, the contact portion of the projecting portion with the guide portion (taper guide surface) is substantially linear and has a very small area. As a result, the protruding portion is less affected by the dimensional accuracy of the guide portion and the like, so that the protruding portion has a peculiar rotational movement speed controlled by the contact with the guide portion. (A speed different from the peripheral speed controlled by the stretch).

In the present invention, the tapered guide surface of the guide portion has a taper angle of 2 × (45 ° to 7 °).
0 °).

In this case, the projecting portion is more difficult to ride on the tapered guide surface. The angle in parentheses “45 ° to 70 °” in the above angle range is the inclination angle of the guide surface and corresponds to half the taper angle.

Further, in the present invention, it is preferable that the guide portion is formed as a structure (part) independent of the support roll, and is rotatably mounted on the support roll.

In this case, the guide portion can freely rotate with respect to the support roll. Due to this, the position where the protrusion comes into contact with the guide portion (taper guide surface) is on the inner circumferential side from the outer circumferential surface of the support roll (particularly the drive roll) by the thickness of the protrusion (difference in rotation radius). Even if the difference in the peripheral speed is likely to occur, the guide portion freely rotates without being influenced by the rotation state of the support roll, and the difference in the peripheral speed is absorbed by the free rotation. As a result, such a phenomenon that the protrusion slips with respect to the guide due to the peripheral speed difference does not occur as in the case where the guide is configured to rotate integrally with the support roll. Further, it is possible to avoid such a problem that the projecting portion is severely worn and the projecting portion easily rides on the guide portion as in the case of absorbing the difference in peripheral speed due to the slip phenomenon.

Further, according to the present invention, when the guide portion is provided on a drive roll and a support roll which is firstly arranged on the upstream side in the endless belt rotation direction from the drive roll,
The amount of deviation of the guide portion of the support roll relative to the guide portion of the drive roll in the roll axis direction is 0 to 0.5 m.
It is good to set in the range of m.

In this case, the guide functions of the respective guide portions of the drive roll and the support roll are normally exhibited, and the phenomenon of running over the tapered guide surface of the projecting portion can be suppressed more reliably. 0m for the above displacement
m, that is, a state without deviation is desirable. When the displacement is less than 0 mm, that is, when the guide portion of the drive roll projects beyond the guide portion of the support roll, the guide function of the guide portion on the support roll side cannot be normally performed, and Riding of the projecting portion at the guide portion of the roll is likely to occur.

Further, in the present invention, it is preferable that the projecting portion is formed of a material softer than the guide portion.

In this case, when the projecting portion comes into strong contact with the guide portion when meandering occurs, the projecting portion side is always compressed and deformed. Thereby, the pressure generated by the contact is absorbed by the protrusion. As a result, not only the stress concentration near the belt joining portion of the protrusion is avoided, but also the amount of the protrusion rising on the tapered guide surface is reduced.

Further, in the present invention, it is preferable that the tapered guide surface of the guide portion has a smaller coefficient of friction than the surface of the protrusion.

In this case, the tapered guide surface of the guide portion becomes slippery for the projecting portion. This allows
When the protrusion comes into contact with the guide, the mechanical action of the tapered guide surface trying to ride on the protrusion is weakened. As a result, the amount of protrusion of the protrusion on the tapered guide surface is reduced.

On the other hand, an image forming apparatus according to the present invention that can achieve the above object uses the above-described belt conveying apparatus as a belt conveying apparatus in an image forming apparatus that forms a toner image according to image information. It is characterized by the following.

The belt conveying device in such an image forming apparatus includes, for example, an intermediate transfer belt device, a photosensitive belt device, and the like, in which a toner image is a conveying object, and a recording medium is a conveying object. Examples thereof include a paper transport transfer belt device and a normal paper transport belt device.

[0024]

[First Embodiment] FIG. 1 is a schematic view showing a color image forming apparatus provided with a belt conveying device according to one embodiment of the present invention. In the figure, reference numeral 10 denotes an image forming unit as an image forming apparatus capable of forming four color toner images of yellow (Y), magenta (M), cyan (C), and black (B), and reference numeral 20 denotes an image forming unit. An intermediate transfer belt module P as a belt transport device that transports the toner image formed by the unit 10 to a predetermined position by an endless belt, and P indicates a recording sheet (recording medium).

In the color image forming apparatus, first, in the image forming unit 10, the surface of a photosensitive drum 11 as an image carrier which is driven to rotate at a predetermined speed in the direction of arrow A is charged by a charging roll 12 of a charging device. Is charged uniformly to a predetermined potential, and then the charged photosensitive drum 11
ROS (Raster Output) as a latent image forming device
Scanner 13 scans and exposes laser beam Bm modulated according to image information to form an electrostatic latent image.
Next, the electrostatic latent image is developed by a developing device 14 of a rotary developing device 14 in which toner corresponding to the color of the latent image is stored.
(Y, M, C, B). As a result, a toner image T of a color corresponding to the electrostatic latent image is formed on the photosensitive drum 11. On the other hand, the surface of the photosensitive drum 11 after the transfer is cleaned by the drum cleaner 15. The image information is image information obtained from a document reading device, an externally connected device (such as a personal computer), or the like.

The toner image T formed on the photosensitive drum 11 of the image forming unit 10 is transferred to the intermediate transfer belt 21 of the intermediate transfer belt module 20.

Here, the intermediate transfer belt 21 is composed of an endless belt made of a synthetic resin film or rubber, and includes a plurality of support rolls, a drive roll 22, a tension roll 23,
It is stretched around the backup roll 24 and the driven roll 25 and is driven to rotate at a predetermined speed in the direction of arrow B. The photosensitive drum 1 of the intermediate transfer belt 21
A primary transfer bias roll to which a primary bias having a polarity opposite to the charging polarity of the toner on the photosensitive drum 11 is applied is disposed on the inner peripheral surface (primary transfer position N1) opposite to the first transfer bias roller. A belt cleaner 27 is provided on the outer peripheral surface of the intermediate transfer belt 21 facing the driven roll 25, the belt cleaner 27 being capable of coming into contact with and separating from the intermediate transfer belt 21. Further, the backup roll 24 of the intermediate transfer belt 21
On the outer peripheral surface side (secondary transfer position N <b> 2) opposite to the above, a secondary transfer roll 30 that can be brought into and away from the intermediate transfer belt 21 is provided. The backup roll 24 is provided with a power supply roll 31 for applying a secondary transfer bias having the same polarity as the charging polarity of the toner on the intermediate copying belt 21 to the roll 24.

Such an intermediate transfer belt module 20
In the above, the toner image T on the photosensitive drum 11 is primarily transferred electrostatically to the intermediate transfer belt 21 at the primary transfer position N1, and thereafter, the secondary transfer is performed with the rotation of the intermediate transfer belt 21. The sheet is transported to the position N2. Then, the toner image on the intermediate transfer belt 21 is moved to the secondary transfer position N
2 is electrostatically secondary-transferred to the recording paper P supplied to the recording paper 2. Here, the recording paper P is stored in a paper storage cassette 35, sent out of the cassette by a feed roll 36, and then registered via a paper transport path including a plurality of transport rolls 37. The sheet is conveyed to a roll 38, and finally is sent to the secondary transfer position N2 by the registration roll 38 in synchronization with the secondary transfer timing. A dashed line with an arrow in the drawing indicates a transport path of the recording paper P.

In this intermediate transfer belt module, when a single-color image is formed, the single-color toner image T primarily transferred to the intermediate transfer belt 21 is secondarily transferred to the recording sheet P immediately. When forming a color image in which toner images of a plurality of colors are superimposed, the steps of forming the respective toner images on the photosensitive drum 11 and the primary transfer of the toner images are repeated by the number of colors. It has become. For example, when a full-color image is formed by superimposing four color toner images, yellow, magenta, cyan, and black toner images are sequentially formed on the photosensitive drum 11, and are primarily transferred to the intermediate transfer belt 21 in the order of formation. You. In the case of forming a color image, since a plurality of toner images are multiply transferred so as to be superimposed on the intermediate transfer belt 21 as described above, the belt cleaner 26 and the secondary transfer roll 30 are provided at least in the intermediate transfer belt. The toner image primarily transferred onto the transfer belt 21 is brought into contact with or separated from the intermediate transfer belt 21 at a predetermined timing so as not to be disturbed by the cleaner 26 and the secondary transfer roll 30 being touched. It is supposed to.

Next, the recording paper P after the secondary transfer of the toner image T is sent to the fixing device 40 and subjected to fixing processing. The fixing device 40 is arranged so as to rotate in a state where a heating roll 41 and a pressure roll (which may have a heating function) 42 are pressed against each other. The recording paper P is introduced into and passed through a fixing nip portion, which is a pressing portion. Therefore, the recording paper P peeled off from the intermediate transfer belt 20 after the secondary transfer is sent to and passed through the fixing nip portion of the fixing device 40, so that the toner image is heated and pressurized and fixed on one side of the recording paper P. Is done. The recording paper P after the completion of the fixing is discharged from the fixing device 40 and then conveyed and discharged outside the apparatus or to a post-processing device (or a double-sided conveyance path in the case of double-sided printing) by a discharge roll 43 or the like.

Through the above steps, the basic image forming process by this color image forming apparatus is completed.

By the way, in this image forming apparatus,
When the color image is formed, multiple transfer of the toner image from the image forming unit 10 to the intermediate transfer belt 21 is performed,
Since the secondary transfer of the toner image is performed from the intermediate transfer belt 20 to the recording sheet P, if the intermediate transfer belt 21 is meandering at each transfer, the multiple transfer and the secondary transfer are performed normally. However, there is a problem that the image quality is poor. For this reason, it is necessary to stably rotate the intermediate transfer belt 21 so as not to meander.

For this reason, in this image forming apparatus, FIGS.
As shown in FIG. 4, rib members (projections) 50 projecting along both edges of the inner peripheral surface of the intermediate transfer belt 21 in the intermediate transfer belt module 20 are provided, and the intermediate transfer belt 21 is supported. The inner end 50a of the rib member 50 is provided at each end of the drive roll 22, the tension roll 23 and the driven roll 25 among the four support rolls.
Is provided with a rib guide portion (guide portion) 60 having a tapered guide surface 61 which is guided in contact with the guide portion.

The intermediate transfer belt 21 has a thickness of 50 to 50 made of a material obtained by mixing carbon black with polyimide.
An endless belt having a width of 100 μm and a width of 365 mm is used. As the rib member 50, a band-shaped member made of urethane rubber and having a cross-section width of 5 mm and a cross-section height of 1 mm is attached to both ends of the inner peripheral surface of the intermediate transfer belt 21 with an adhesive or the like.

On the other hand, as shown in FIGS. 3 and 4, the rib guide portion 60 is provided at both ends of each of the rolls 22, 23 and 25.
A structure having a tapered guide surface 61 formed of a conical slope inclined toward each roll shaft 22a (23a, 25a) was mounted on an outer portion of a thick disk having an outer diameter substantially the same as the outer diameter of each roll. Things. Particularly, in this embodiment, the taper angle θ of the tapered guide surface 61 is set to 2 × 60 °
Is set to The rib guide portion (hereinafter simply referred to as “rib guide member”) 60 having a structure independent of such a roll is made of POM (polyacetal).
Is formed into a shape having a bearing hole into which the above-mentioned roll shaft is fitted, and is rotatably mounted on each roll shaft 22a via a bearing member 65 fitted into the bearing hole. .

With this configuration, in the intermediate transfer belt module 20, the pair of left and right rib members 50 provided at both ends of the inner peripheral surface of the intermediate transfer belt 21 are formed such that only the inner front end 50 a has the taper of the rib guide body 60. The guide is guided in a state of contact with the guide surface (conical slope) 61. As a result, even if the intermediate transfer belt 21 is about to meander, the meandering is suppressed by the rib member 50 being guided by the rib guide body 60. As a result, the meandering of the intermediate transfer belt 21 is suppressed. Runs in a stable state. Further, at the time of this guide, the joint 51 of the rib member 50 with the belt does not contact the rib guide body 60, so that stress is less likely to concentrate on the joint 51, and as a result, due to the stress concentration, The occurrence of breakage such as a crack in the intermediate transfer belt 21 is also suppressed.

In this embodiment, the taper angle θ of the tapered guide surface 61 of the rib guide body 60 is “60 °”.
, It is difficult for the rib member 50 to ride on the tapered guide surface 61. As a result, it is possible to suppress breakage such as a crack of the belt, which is generated when the intermediate transfer belt 21 in the vicinity of the belt joining portion 150 of the rib member 50 runs long while deformed due to the riding. Thereby, the durability of the intermediate transfer belt 21 is improved, and troubles such as the image forming operation having to be stopped due to the breakage of the belt are less likely to occur.

FIG. 5 shows the taper angle θ (1/2) of the taper guide surface 61 and the running amount α of the intermediate transfer belt 20.
It is a test result showing the relationship with. Belt ride amount α
6A, the rib member 50 moves to the outer peripheral side (the upper side in the figure) of the tapered guide surface 61 as shown by the two-dot chain line in the figure, so that the intermediate transfer belt 21 is normal. The height (distance) rising from the position H is measured. From the result of FIG. 5, it is found that the taper angle θ is 2
It is evident that when the value of the fraction falls in the angle range of 45 ° to 75 °, the amount of running of the belt is reduced. For this reason, from the viewpoint of reliably reducing the running amount α of the belt, the taper angle θ of the tapered guide surface 61 of the rib guide body 60 is “2 × (45 ° to 7 °)”.
0 °).

In this embodiment, since the rib member 50 is formed of urethane rubber and the rib guide body 60 is formed of another material, the rib member 50 is formed of a material softer than the rib guide body 60. In a relationship. For this reason, for example, the intermediate transfer belt 50
When the rib member 50 strongly contacts the tapered guide surface 61 of the rib guide body 60, the rib member 50 is compressed and deformed and the pressure (shock) at that time is absorbed and disappears. At the same time, the stress concentration on the rib member 50 is avoided, and the amount of climbing on the tapered guide surface 61 of the rib member 50 is reduced. This also suppresses breakage such as cracks caused by the intermediate transfer belt 21 rotating and running for a long time in a state deformed by the riding of the rib member 50.

Further, in this embodiment, the rib member 50
(Surface) is a rubber surface, whereas the rib guide body 60
Since (the surface of) is the surface of the plastic molded product, the surface of the rib guide body 60 has a smaller friction coefficient than the surface of the tapered guide surface 61 of the rib guide body 60.
For this reason, the taper guide surface 61 of the guide portion 60 becomes slippery with respect to the rib member 50.
When 0 is in contact with the tapered guide surface 61 of the guide portion 60, the mechanical action of the tapered guide surface 61 for causing the rib member 50 to ride on by the contact frictional force is weakened.
As a result, the riding amount of the rib member 50 on the tapered guide surface 61 is reduced. This also suppresses breakage, such as cracks, caused by the intermediate transfer belt 21 running for a long period of time in a state of being deformed by the riding of the rib member 50 for a long period of time.

Further, in this embodiment, the rib guide body 60 is rotatable with respect to the drive roll 22 and the like, and therefore has the following advantages.

That is, as shown in FIG. 6B, the position of contact with the tapered guide surface 61 of the inner front end portion 50a of the rib member 50 (the portion shown by the two-dot chain line in the figure) corresponds to the thickness E of the rib member 50. Only on the inner peripheral side from the outer peripheral surface of the drive roll 22 or the like (difference in rotational radius: “radius R of drive roll”)
> “Radius r of the above-mentioned contact position of the rib member”), even if the peripheral speed difference is likely to occur due to the rib guide portion 60
Rotate freely without being influenced by the rotation state of the drive roll 22, the difference in peripheral speed is absorbed by the free rotation. As a result, unlike the case where the rib guide body 60 is fixedly attached to the drive roll 22 or the like, the rib member 50 does not slip and wear with the rib guide body 60, and the rib member 50 is The amount of riding on the tapered guide surface 61 can be suppressed.
Therefore, this also suppresses breakage such as cracks that occur due to the intermediate transfer belt 21 rotating and running for a long time in a state where the intermediate transfer belt 21 has been deformed by riding on the rib member 50.

The intermediate transfer belt module 2
7, the shift amount β in the roll axis direction of the rib guide body 60 of the driven roll 25 with respect to the rib guide body 60 of the drive roll 22 is 0 to 0, as shown in FIG.
It is set to be within the range of 0.5 mm. The guide function of each rib guide body 60 in the drive roll 22 and the driven roll 25 is normally exhibited, and
The riding phenomenon on the taper guide surface 61 of the rib member 50 is also suppressed more reliably.

FIG. 8 is a test result showing the relationship between the amount of deviation β and the amount of belt running α on the driving roll 22 and the driven roll 25. From the results shown in FIG. 8, when the shift amount β exceeds 0.5 mm, the belt running amount α on the driven roll 25 increases, and the shift amount β is 0 m.
If m is less than m (when the drive roll 22 jumps out of the driven roll 25), it can be seen that the belt running amount α on the drive roll 22 side sharply increases. Therefore, the belt running amount α between the two rolls 22 and 25 is α
From the viewpoint of reducing both the shift amount β and the shift amount β.
It is preferable to set the range to “5 mm”.

The intermediate transfer belt module 2 as described above
In the case where 0 is used, the intermediate transfer belt 21 has no belt damage caused by the concentration of stress on the belt joining portion 51 of the rib member 50 or the belt deformation caused by the rib member 50 riding on the rib guide body 60. , And the vehicle runs stably for a long period of time. In addition, due to the stable rotation of the intermediate transfer belt 21 without breakage of the belt, the primary transfer and the secondary transfer can be performed satisfactorily without problems such as misalignment. And good color image formation without stabilization is performed stably.

[Other Embodiments] In the first embodiment, the case where the rib members 50 which are separate from the belt are adhered as the protruding portions provided along the both edges of the inner peripheral surface of the intermediate transfer belt 21 has been described. Alternatively, the protrusion may be formed integrally with the belt.

Although the intermediate transfer belt device has been exemplified as the belt conveying device, a photosensitive belt device provided with a belt-shaped image carrier such as a photosensitive belt for forming and carrying a toner image, and a recording paper carrying device. It is also possible to apply the present invention to a paper transport transfer belt device provided with a paper transport transfer belt that transports the paper so as to pass through a transfer position and the like, and the same operational effects as those of the above-described intermediate transfer belt device can be obtained. Further, the belt transport device having such a configuration can be applied as a belt transport device used other than the image forming apparatus.

Further, as the image forming apparatus, the image forming apparatus 10 is used, and each image forming apparatus 10 uses the image forming apparatus 10 corresponding to the color of the toner image forming the color image (in this case, each image forming apparatus 10 is used). Need only be a single developing device for accommodating the toner of each color), and separately form the toner images of the respective colors by the respective image forming devices and sequentially primary-transfer them to the intermediate transfer belt 21 sequentially. A so-called tandem type image forming apparatus may be used.

[0049]

As described above, according to the belt conveying apparatus of the present invention, it is possible to suppress the meandering in which the belt is less likely to be broken, and to realize the stable rotation of the endless belt for a long period of time. It is possible. As a result, the durability of the endless belt is greatly improved, and therefore, the belt of the object to be transferred can be stably transported for a long time.

Further, according to the image forming apparatus of the present invention to which such a belt conveying device is applied, stable rotation running without breakage of the endless belt and meandering is realized by the belt conveying device for a long time. Belt conveyance of images, recording media, and the like can be stably performed over a long period of time, and good image formation can be stably performed without any trouble caused by the endless belt.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an image forming apparatus using a belt conveyance device according to a first embodiment.

FIGS. 2A and 2B show an intermediate transfer belt module which is the belt conveyance device of FIG. 1, wherein FIG.
2B is a cross-sectional view of a main part taken along line QQ in FIG.

FIG. 3 is an enlarged view of a main part showing a contact state between a rib member of the intermediate transfer belt and a rib guide body.

FIG. 4 is a cross-sectional view showing a structure of a rib guide body and a state of being attached to a roll.

FIG. 5 is a taper angle (1/2 angle) of a rib guide body.
FIG. 6 is a graph of test results showing the relationship between the distance and the amount of running of the belt.

FIGS. 6A and 6B show a contact state between a rib member of an intermediate transfer belt and a tapered guide surface of a rib guide body, wherein FIG. 6A is a side view of a main part thereof, and FIG.

FIG. 7 is an explanatory plan view showing a state of a displacement amount in a roll axis direction between a rib guide body in a driving roll and a rib guide body in a driven roll.

FIG. 8 is a graph of test results showing the relationship between the amount of deviation of the driven roll (the rib guide body) with respect to the driving roll (the rib guide body) and the amount of belt running.

FIG. 9 shows a conventional belt conveying device, in which (a)
FIG. 2 is an explanatory view of a main part showing a belt deformation occurring near a belt coupling part of a protruding portion (rib member) provided on the endless belt. FIG. 2B is a perspective view of a main part showing a state of breakage such as a crack generated on the endless belt. FIG.

FIG. 10 is a main part explanatory view showing main components of a conventional belt conveying device.

[Explanation of symbols]

10 image forming apparatus, 20 intermediate transfer belt module, 2
1: Intermediate transfer belt, 22: drive roll, 23-24 ...
Support roll, 25: driven roll, 50: rib member, 50
a: inside tip, 60: rib guide (body), 61: taper guide surface, T: toner image, P: recording paper, θ: taper angle, β: shift amount.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Koichi Matsumoto 1600 Takematsu, Minamiashigara-shi, Kanagawa Prefecture, F-term in Fuji Xerox Co., Ltd. 2H032 BA09 BA18 BA23 2H035 CA05 CB06 CF02 3F023 AA05 BA02 BA10 BB01 BC03 GA01 GA03 3F049 BB11 LA02 LA07 LB03

Claims (7)

[Claims] 1. A belt transport device comprising: an endless belt that carries an object to be transported; and a plurality of support rolls including a drive roll that stretches and rotates the endless belt. Protrusions are provided along both end edges of the peripheral surface, and a guide portion having a tapered guide surface is provided at at least one roll end of the support roll so that the inner tip of the protrusion contacts and is guided. A belt conveying device characterized by the above-mentioned. 2. The belt conveying device according to claim 1, wherein the tapered guide surface of the guide portion has a taper angle of 2 degrees.
A belt conveying device formed to have an angle range of x (45 ° to 70 °). 3. The belt conveying device according to claim 1, wherein the guide portion has a structure independent of a support roll, and is rotatably mounted on the support roll. . 4. The belt conveying device according to claim 1, wherein the guide portion is provided on a drive roll and a support roll that is firstly disposed upstream of the drive roll in the endless belt rotation direction. Wherein the amount of deviation of the guide portion of the support roll from the guide portion in the roll axis direction is set in a range of 0 to 0.5 mm. 5. The belt conveying device according to claim 1, wherein said projecting portion is formed of a material softer than said guide portion. 6. The belt conveying device according to claim 1, wherein the tapered guide surface of the guide portion has a smaller coefficient of friction than the surface of the projecting portion. 7. A belt conveying device in an image forming apparatus for forming a toner image according to image information.
An image forming apparatus using the belt conveyance device according to any one of claims 6 to 10.