JP2001147601A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an endless belt from twisting due to the tension change of the endless belt which is caused by displacement operation of a roll in an image forming device where one of rolls supporting the endless belt is displaced to control the running state of the belt. SOLUTION: When the device has a belt running control mechanism 20 which displaces one (a driving roll 22) of plural rolls supporting an endless belt 21 in control direction of arrows J and K to control the running state of the belt 21, a tension correction mechanism 60 is provided which displaces a contact body (a tension roll 25), which is brought into contact with the belt 21 in the breadthwise direction, in correction directions of arrows L and M to correct the tension change of the endless belt 21 which is caused in accordance with the displacement operation of the roll 22 by the bolt running control mechanism 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copier, a printer, a facsimile, and a multifunction peripheral.
The present invention relates to an image forming apparatus provided with an endless belt that requires a high degree of accuracy in its running state.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine or a printer, as shown in FIG.
An image (toner image) formed on a photosensitive drum or the like by an electrophotographic method is applied to the surface of the endless belt 200 by applying a belt traveling device that stretches the endless belt 200 around 1, 102, and 103 and rotates and runs in the direction of arrow e. It is used as a so-called intermediate transfer belt mechanism that once transfers and carries the image, and then re-transfers it to a recording sheet such as recording paper conveyed so as to merge with the belt 200.

In addition, the above-mentioned belt traveling device is used as a photosensitive belt mechanism for forming an electrostatic latent image corresponding to image information and its toner image on the surface of an endless belt by an electrophotographic method, or Is transported to a transfer position on a photosensitive drum or the like where an image is formed, and the image is transferred from the photosensitive drum or the like to the recording sheet side and discharged. It is known to use as a sheet conveyance transfer belt mechanism.

Incidentally, in an image forming apparatus using such a belt traveling device, manufacturing errors of rolls and belts for supporting the endless belt, errors of parallelism of the rolls, one end and the other end of each roll. Due to a difference in tension applied to the belt in the portion, a meandering phenomenon occurs in which the endless belt 200 travels while moving in the axial direction of the roll (corresponding to the width direction of the belt), or the endless belt 200 The endless belt 200 travels in an inclined state without running in a direction perpendicular to the rolls 101, 102, and 103, and the entire endless belt 200 travels in a “8-shaped” shape as shown in FIG. Symptoms may occur. If the endless belt runs in a state where the meandering phenomenon or the twisting phenomenon occurs, the image is not transferred to a regular position of the endless belt or the recording sheet in the meandering phenomenon, and the twisting phenomenon occurs. In some cases, an image transferred from a photosensitive drum to an endless belt as an intermediate transfer belt is distorted, and an image transferred to a recording sheet after being transferred to the endless belt also has a problem of large skew. . Such a problem also induces a new problem that image quality defects such as color shift and color unevenness occur in a color image formed by superimposing a plurality of color toner images.

In order to solve such a problem, the applicant of the present invention has proposed a method in which, when an endless belt is running meandering or twisting, one end of a drive roll that supports and rotates the endless belt. An end of a backup roll that supports an endless belt at a secondary transfer position where an image is transferred to a recording sheet is displaced upward or downward by an eccentric cam mechanism or the like to tilt the entire roll. An image forming apparatus has been proposed (JP-A-10-260).
590, etc.).

[0006]

However, when one of the rolls supporting the endless belt is displaced so as to be tilted upward or downward, the tension of the endless belt changes, and this tension is changed. In some cases, a problem that the belt is twisted due to the change in the temperature may occur. As shown in FIG. 18b, when the one end of the roll 101 is tilted upward (open arrow) Yu, as shown in FIG. 18b, the tension applied to the endless belt portion 200a tilted upward is shown in FIG. 18b. Endless belt portion 2 on the side tilted downward when tilted downward (hatched arrow) Yd.
That is, the tension applied to 00a is weaker than normal. Such a problem may similarly occur in the case of the image forming apparatus disclosed by the present applicant in a patent application (Japanese Patent Application No. 10-243573).

SUMMARY OF THE INVENTION An object of the present invention is to adjust the running state of one endless belt by displacing one of the rolls supporting the endless belt. It is an object of the present invention to provide an image forming apparatus capable of preventing the occurrence.

[0008]

An image forming apparatus according to the present invention for achieving the above object is an apparatus for forming an image according to image information, comprising a plurality of rotatably supported rolls,
An endless belt that runs while being stretched over the plurality of rolls,
A belt travel adjustment mechanism that adjusts a traveling state of the endless belt by displacing at least one end of the one roll, and a tension change of the endless belt that occurs with a roll displacement operation by the belt travel adjustment mechanism. And a tension correcting mechanism that corrects by displacing a contact body that is in contact with the belt along the width direction thereof.

In this image forming apparatus, the contact member of the tension correcting mechanism is displaced in a desired direction when the operation of displacing the roll by the belt travel adjusting mechanism is performed.
The change in the tension of the endless belt caused by the displacement of the roll is corrected (canceled). That is, the tension correcting mechanism displaces the contact body in a direction in which the tension is reduced when the tension is increased by the displacement operation of the roll, while the tension is reduced when the tension is reduced by the displacement operation of the roll. The contact body is displaced in the direction in which it increases.

The contact member in the tension correcting mechanism can be applied without limitation as long as it is in contact with the belt in the width direction and can correct a change in the tension of the belt by being displaced. Although it is possible to add a simple contact body, it is preferable to use an existing component. For example, among a plurality of rolls supporting the endless belt, at least one roll other than the roll displaced by the belt travel adjusting mechanism, or a blade pressed against the endless belt. When the contact body is a roll, it may be configured so that one end of the roll is displaced in a predetermined direction capable of correcting a change in the tension of the belt. When the contact body is a blade, the contact pressure of the blade against the belt surface may be changed so as to change the contact pressure to a predetermined state capable of correcting a change in belt tension. Such blades include cleaning blades.

Further, the tension compensating mechanism first executes the roll displacement operation by the belt traveling adjusting mechanism,
The endless belt at that time may be controlled to operate after detecting whether or not a change in tension (or torsion) has occurred in the endless belt. However, it is desirable that the endless belt be operated in conjunction with the displacement operation of the belt traveling adjustment mechanism. It may be controlled to operate. In this case, in addition to being able to quickly respond to a change in belt tension, it is possible to improve the adjustment range of the belt traveling state by the belt traveling adjustment mechanism or to improve the adjustment speed. Become.

Further, in the image forming apparatus according to the present invention, the belt running adjusting mechanism may be configured to move the roll to be displaced between the roll of the endless belt and each roll positioned before and after in the belt running direction of the roll. The circumferential length is configured to be displaced in a changing direction, and the tension correcting mechanism uses a tension applying roll that applies tension to the endless belt as the contact body, and the tension applying roll to the roll. The end position of the endless belt is adjusted by the displacement operation of the belt travel adjustment mechanism, and the emission position where the side end of the endless belt separates from the roll is adjusted with respect to the incident position where the side end of the endless belt first contacts during traveling. It may be configured to be displaced in a direction having a positional relationship shifted in the same direction as the direction.

In this case, when the roll to be displaced by the belt travel adjusting mechanism is displaced in the direction in which the belt length changes, the tension applying roll of the tension correcting mechanism acts so as to correct the tension change of the endless belt. At that time,
Since the tension applying roll is displaced in a direction in which the output position with respect to the incident position is in the positional relationship as described above, in addition to functioning to correct a change in the tension of the endless belt to a certain extent, in particular, the endless belt travels along the belt. It functions so as to be displaced in a direction coinciding with the adjustment direction by the adjustment mechanism to promote the adjustment action.

The endless belt as described above is not only an intermediate transfer belt, but also a photosensitive belt used in an electrophotographic system, a sheet transport transfer belt which attracts and transports a recording sheet to an image transfer position, and the like. You may. Further, when the image forming apparatus having both the belt traveling adjusting mechanism and the tension correcting mechanism is applied to a color image forming apparatus of a method of forming a color image by transferring a plurality of color toner images one by one and superimposing them, This is particularly advantageous since the problems of color shift and color unevenness as described above hardly occur.

[0015]

[First Embodiment] FIGS. 1 and 2
1 shows a first embodiment of the present invention. FIG. 1 is a schematic explanatory view showing the overall configuration of an image forming apparatus according to the first embodiment, and FIG. 2 is an intermediate transfer belt employed in the image forming apparatus. It is explanatory drawing which shows a mechanism.

In the image forming apparatus of the first embodiment, yellow (Y), magenta (M), cyan (C), and black (k) are individually formed by four image forming units 10Y, 10M, 10C, and 10K. After the four color toner images are primarily transferred so as to overlap the surface of the intermediate transfer belt 21 of the intermediate transfer belt mechanism 20, the intermediate transfer belt 2
This is a color image forming apparatus capable of forming a so-called full-color image by performing secondary transfer from No. 1 to the recording sheet P side. This apparatus can also form a black and white image by operating only the black image forming unit 10K among the four image forming units.

Each of the image forming units 10 forms a toner image by an electrophotographic process. Basically, a photosensitive drum 11, a charger (charging roll) 12, a latent image forming device 13, a developing device 14, Transfer device (transfer roll) 15
And a drum cleaner 16. According to each of the image forming units 10, the photosensitive drum 11 rotating in the arrow direction A is uniformly charged by the charger 12 and then subjected to color separation from the latent image forming device 13 on the charged surface. An electrostatic latent image is written by scanning and exposing a laser beam (dotted arrow) corresponding to the image data, and then the latent image is developed by a developer supplied from the developing device 14 to become a toner image. Finally, the toner image is primarily transferred electrostatically to the surface of the intermediate transfer belt 21 passing between the photosensitive drum 11 and the transfer device 15. The surface of the photosensitive drum 11 after the transfer is cleaned by a blade of a drum cleaner 16.

The intermediate transfer belt mechanism 20 includes an intermediate transfer belt 21 as an endless belt,
The idler roll 23, the driven roll 24, the tension roll (tension imparting roll) 25, the pre-roll 26, and the backup roll 27 are stretched over and run in the direction of arrow B by the rotational power of the drive roll 22. Each of the rolls is rotatably supported by a bearing. Reference numeral 28 in FIG. 1 is a belt cleaner for the intermediate transfer belt, 29 is a detection device for detecting the presence or absence of a belt home mark formed at the side end of the intermediate transfer belt and the position of the belt edge (edge portion). Is the sensor section.

The toner image multiplex-transferred onto the intermediate transfer belt 21 of the intermediate transfer belt mechanism 20 is transported to a secondary transfer position opposed to a secondary transfer roll 30 disposed opposite a backup roll 27. Then, the toner image on the intermediate transfer belt 21 is sent out from the storage tray 31 in accordance with the image formation and transfer timing of the toner image, and is transferred to a secondary transfer position through a sheet conveying path on which a roll 32, a registration roll 33, and the like are arranged. The recording sheet P to be conveyed is secondarily electrostatically transferred. 1 indicates a conveyance path of the recording sheet P. Then, the recording sheet P on which the toner image has been transferred is fixed to a roll nip type fixing device 35.
After the toner image is heat-fixed by passing through the nip between the heating roll 36 and the pressure roll 37 in the above, the toner image is discharged to the outside of the apparatus main body by the discharge roller 38. Through the above process, a color image is formed on the recording sheet P.

As shown in FIG. 2, the intermediate transfer belt mechanism 20 in this embodiment is provided with one end of a driving roll 22 in a predetermined adjustment direction J, K to displace the intermediate transfer belt 21. A belt traveling adjustment mechanism (hereinafter, also referred to as a “steering mechanism”) 50 for adjusting the traveling state is provided, and the one end of the tension roll 25 is displaced along predetermined correction directions L and M to thereby perform the above-described operation. A tension correcting mechanism 60 is provided for correcting a change in the tension of the intermediate transfer belt 21 caused by the displacement of the driving roll 22 by the belt travel adjusting mechanism 50.

FIGS. 3a and 3b show the steering mechanism 50.
1 shows a drive roll 22 provided with a tension roll 25 and a tension roll 25 provided with a tension correcting means 60.

The drive roll 22 has a roll shaft 22b to which a roll main body 22a is fixed, and a drive roll unit housing 4.
1 is rotatably supported via bearings 41a and 41b. The drive roll unit housing 41 is supported by a bracket 40a swingable by the fixed frame 40 at a lower position on one end side in the roll axis direction,
The other end portion is supported by a steering mechanism 50 described later. And the drive roll 2
2 is a configuration in which the rotational power of the drive motor 42 is supplied to the drive gear 43 attached to the output shaft of the drive motor 42 and the roll shaft 22b.
Is transmitted by a gear train that meshes with a passive gear 44 attached to the motor, and rotates. The rotational speed of the drive roll 22 is detected by a rotational speed detecting mechanism such as a rotary encoder (not shown) attached to the roll shaft 22b, and the rotational state of the drive motor 42 is feedback-controlled based on the detected information. By doing so, it is designed to rotate stably.

A steering mechanism 50 provided on the drive roll 22 (strictly speaking, the drive roll unit housing 41).
Is a steering motor 51 such as a stepping motor.
And an eccentric cam 52 attached to an output shaft 51a of the motor 51, and a cam floor 53 attached to a support shaft 45 that projects axially from the side surface of the unit housing 41 so that the eccentric cam 52 comes into contact with the eccentric cam 52. Have. Then, the eccentric cam 52 is rotated by an angle θ in the ± direction from the reference position X ₀ (θ = 0 °) by the driving force of the steering motor 51 (FIG. 3C), so that a constant cam displacement as shown in FIG. As a result, the drive roll unit housing 41 and, consequently, the drive roll 22 are displaced in the adjustment directions J and K by a distance corresponding to the cam displacement amount. In this embodiment, the adjustment directions J and K, which are the displacement directions of the drive roll 22, are set in the vertical direction of the apparatus. Specifically, the adjustment direction J is set to “up” and the adjustment direction K is set to “down”. Direction ".

The tension roll 25 is supported by a conventionally known tension applying mechanism 46 in a state where a predetermined tension is continuously applied to the intermediate transfer belt 21 from the back side thereof, and the roll body 25a to which the roll main body 25a is fixed is attached. One end of the shaft 25b is rotatably and tiltably supported by the spherical bearing 41b with respect to the support frame 46a of the tension applying mechanism 46, and the other end of the roll shaft 25b is rotatably supported by the bearing 41a. It is loosely fitted in the elongated hole 46b provided in the support frame 46a via the bearing 41a so as to be vertically movable. Further, a belt end regulating mechanism 47 for suppressing the meandering traveling of the intermediate transfer belt 21 is attached to the tension roll 25. The belt end regulating mechanism 47 controls the roll shaft 45b so that the belt end contacts and regulates the end position.
A donut disk-shaped restricting plate 48 that is loosely fitted to the supporting plate 48, and one end of the restricting plate 48 for supporting the restricting plate 48 so that it can be easily and elastically displaced and moved in the axial direction of the roll shaft 45b.
And a spring 49 fixed at the other end to the support frame 46a. Reference numeral 47a denotes a stopper for stopping the regulating plate 48 at the maximum movement allowable position.

The tension correcting means 60 provided on the tension roll 25 basically includes the steering mechanism 50
And a tension correction motor 61 such as a stepping motor, an eccentric cam 62 attached to an output shaft 61a of the motor 61, and a roll shaft 25b so that the eccentric cam 62 comes into contact with the roll shaft 25b. And an attached cam floor 63. Then, almost in the same manner as the steering mechanism 50, the eccentric cam 62 is rotated from the reference position X ₀ (θ = 0 °) by an angle θ in the ± direction (FIG. 3C), and thereby becomes constant as shown in FIG. The cam displacement amount is obtained, whereby the roll shaft 25b and, consequently, the tension roll 2 are moved by a distance corresponding to the cam displacement amount.
5 is displaced in the correction directions L and M. In this embodiment, the correction directions L and M, which are the directions of displacement of the tension roll 25, are directions in which the tension can be easily applied to the intermediate transfer belt 21 so as to be easily increased or decreased. The correction direction L is set to the “tension decreasing direction”, and the correction direction M is set to the “tension increasing direction”.

The steering mechanism 50 and the tension correcting means 60 in the intermediate transfer belt mechanism 20 are arranged as shown in FIG.
As shown in (1), it is connected to the control unit 70, and each operation is controlled by the control unit 70. That is, the control unit 70 basically performs the detection device 2 described above.
9, the walk (meandering) amount of the belt 21 is calculated based on the home mark detection information and the belt edge detection information of the intermediate transfer belt 21, and the steering amount (angle α) of the steering mechanism 50 is obtained from the walk amount and the tension is calculated. The tension correction angle β of the correction means 60 is obtained, and the motors 51 and 61 are operated according to the respective steering angles α and the tension correction angles β. The detection device 29 includes an optical sensor, a CCD, and the like that can detect a belt home mark and a belt edge position.
Further, the control unit includes a ROM in which various control programs and the like are stored, and an RA in which detection information and the like are fetched and stored.
M, and a CPU for performing arithmetic processing and the like based on the control program and the detection information.

Next, the operation of the steering mechanism 50 and the tension correcting means 60 in the intermediate transfer belt mechanism 20 will be described. FIG. 5 is a flowchart showing a control procedure at this time.

First, as shown in FIG. 6, the drive roll 22 and the tension roll 25 are in a state where the roll axis of the drive roll 22 is parallel to the horizontal reference line (dashed-dotted line) H in normal times. The axes are set so as to be in parallel with the center reference line (dashed line) O.

When the intermediate transfer belt mechanism 20 receives the operation start command, the driving roll 22 is driven to rotate, so that the intermediate transfer belt 21 starts rotating and running in the direction of arrow B. At this time, after the detection device 29 detects the belt home mark formed on the side end portion of the intermediate transfer belt 21 (Step 10, hereinafter abbreviated as "S10"), the position e of the belt edge is detected. (S
11). The control unit 70 calculates the walk amount W (= ep) of the intermediate transfer belt 21 based on the detection information (particularly, the edge position detection information) (S12), and then the steering amount S of the steering mechanism 50 (S12). = KW) and the steering angle α (= ΣS) is calculated (S13, S14). This angle α is obtained as an elevation angle with respect to the horizontal reference line H, and the angle on the adjustment direction J side beyond the reference line H is set as a plus angle “+ α” and adjusted beyond the reference line H. The angle on the direction K side is calculated as a negative angle “−α”.
P indicates the initial position of the belt edge, and k indicates a conversion coefficient obtained in advance by a test. Incidentally, in this image forming apparatus, it is determined whether the calculated steering angle α (the absolute value) is smaller than a preset threshold value αf of the angle (S15). Is regarded as "an abnormal steering angle" (S
18), the operation of the belt traveling mechanism 20 is stopped.

Subsequently, when the steering angle α is obtained, the controller 70 calculates a tension correction angle β (= h · α) of the tension corrector 60 (S16). The correction angle β is obtained as an elevation angle with respect to the center reference line O described above. An angle on the correction direction L side beyond the reference line O is defined as a plus angle “+ β” and exceeds the reference line O. The angle on the correction direction M side is calculated as a negative angle “−β”. H represents a conversion coefficient obtained in advance by a test.

When the steering angle α and the tension correction angle β are calculated in this manner, the control unit 70 issues a control command for executing the operation to the steering mechanism 50 and the tension correction mechanism 60, and thereby the motor 51 , 61 rotate substantially simultaneously by a predetermined angle in a predetermined direction (S1).
7). As a result, since the eccentric cams 52 and 62 rotate,
The driving roll 22 and the tension roll 25 are aligned with the horizontal reference line O.
Is tilted by predetermined angles α and β with respect to.

FIG. 7 shows the behavior of the intermediate transfer belt 21 when the drive roll 22 is tilted by the steering mechanism 50 in accordance with the steering angle α (however, the tension roll 22 is not tilted and is in a horizontal state). Things.

That is, when the drive roll 22 is tilted by the steering angle + α and displaced in the adjustment direction J as shown in FIG. 3A, the intermediate transfer belt 21 is moved as indicated by a two-dot chain line in FIG. Adjustment direction J from horizontal reference position H
The vehicle starts traveling while being displaced toward the end of the drive roll 22 that has been displaced. Conversely, when the drive roll 22 is tilted by the steering angle −α and displaced in the adjustment direction K as shown in FIG. 4B, the intermediate transfer belt 21 is horizontally moved as shown by a two-dot chain line in FIG. Adjustment direction K from reference position H
The driving roll 22 starts traveling while being displaced toward the end side (the end side located at a relatively high position) opposite to the end side of the driving roll 22 displaced toward the end. By the way, this steering mechanism 50
When the drive roll 22 is displaced in the adjustment directions J and K by the
When the portion of the intermediate transfer belt 21 that passes when the roller 2 is displaced makes one rotation and passes through the drive roll 22 again,
The entirety of the intermediate transfer belt 21 is rotated by the amount corresponding to the inclination of the drive roll 22 in each direction.
The vehicle travels completely in the direction 2b. Therefore, the adjustment of the running state of the belt by the steering mechanism 50 requires time for one rotation of the belt.

Here, when the drive roll 22 is tilted by the steering mechanism 50 in accordance with the steering angle α, the drive roll 22 is displaced in the adjustment direction J, which is the upward direction, as described in the prior art. Then, the tension of the intermediate transfer belt 21 at the portion where the drive roll 22 is tilted becomes stronger than usual, and as a result, the tension balance of the entire belt may be lost and the belt 21 may be twisted. When the drive roll 22 is displaced in the adjustment direction K, which is the downward direction, the intermediate transfer belt 21
Is weaker than normal, and as a result, the tension balance of the entire belt is lost, and the belt 21 may be twisted.

Therefore, in this image forming apparatus, the tension correction mechanism 60 operates in conjunction with the displacement operation of the drive roll 22 by the steering mechanism 50 to displace the tension roll 25 in the predetermined correction directions L and M. The changed belt tension is corrected.

FIGS. 8 and 9 show the case where the tension roll 25 is tilted by the tension correction mechanism 60 in accordance with the correction angle β (however, the operation is performed in conjunction with the displacement of the drive roll 22 by the steering mechanism 50). 3 illustrates a behavior state of the intermediate transfer belt 21.

That is, as shown in FIG.
2 is displaced in the adjustment direction J, the tension roll 2
5 is displaced in the correction direction L by being tilted by the correction angle + β. As a result, the intermediate transfer belt 21 starts running while being displaced from the horizontal reference position H toward the end of the drive roll 22 displaced in the adjustment direction J from the horizontal reference position H, as indicated by the two-dot chain line in FIG. The vehicle travels while being displaced from the reference position O in the correction direction L to the end of the tension roll 25 where the belt tension is weakened. As a result,
The displacement of the drive roll 22 in the adjustment direction J increases the tension of the part of the intermediate transfer belt 21 on the side of the displaced drive roll 22, but the displacement of the tension roll 25 in the correction direction L, which is the direction in which the tension decreases. As a result, the change in the tension is canceled and corrected, so that the intermediate transfer belt 21
But never twist.

On the other hand, when the drive roll 22 is displaced in the adjustment direction K as shown in FIG. 9, the tension roll 25 is tilted by the correction angle -β and displaced in the correction direction M. Thereby, the intermediate transfer belt 21 is displaced toward the end side opposite to the end side of the drive roll 22 displaced in the adjustment direction K from the horizontal reference position H as shown by the two-dot chain line in the drawing. While starting to run, the center reference position O
Then, the vehicle travels while being displaced in the correction direction M toward the end of the tension roll 25 where the belt tension is increased. As a result, the tension of the portion of the intermediate transfer belt 21 on the side of the displaced drive roll 22 is weakened by the displacement operation of the drive roll 22 in the adjustment direction K, but the displacement in the correction direction M, which is the tension increase direction of the tension roll 25, is reduced. By the displacement operation, the tension change is canceled out and corrected,
The intermediate transfer belt 21 is not twisted.

According to the study of the present inventors, in this image forming apparatus, the tension correcting mechanism 60 is operated in conjunction with the displacement of the drive roll 22 by the steering mechanism 50, as shown in FIG. And the intermediate transfer belt 2
Displacement amount Y displaced (moved) in the roll axis direction 1
However, compared to the case where only the drive roll 22 is displaced by the steering angle α by the steering mechanism 50 (the two-dot chain line in the figure), the number increases (solid line in the figure). That is,
Steering mechanism 50 for the same steering angle α
, The adjustment range of the belt running state can be improved. It is presumed that this is because the tension roll 25 displaced by the tension correction mechanism 60 acts to promote the displacement operation of the intermediate transfer belt 21 by the operation of the steering mechanism 50.

Further, in this image forming apparatus, as shown in FIG. 11, when the displacement amount Y displaced in the roll axis direction of the intermediate transfer belt 21 is viewed from the displacement state with respect to the belt rotation amount, the steering mechanism 50 Drive roll 22
This is achieved in a shorter time (solid line in the figure) than when only the steering angle is displaced by the steering angle α (the two-dot chain line in the figure). That is, in the case of only the steering mechanism 50, the displacement of the belt requires one rotation of the belt. However, when the tension correction mechanism 60 is linked with the steering mechanism 50, the belt moves before the rotation of the belt. Therefore, the adjustment speed of the belt traveling state by the steering mechanism 50 for the same steering angle α can be improved. This also applies to the tension correction mechanism 6.
It is presumed that the tension roll 25 displaced by 0 acts in cooperation to promote the displacement operation of the intermediate transfer belt 21 by the operation of the steering mechanism 50.

According to the image forming apparatus of the first embodiment,
Even if the intermediate transfer belt 21 runs meandering or deviates with respect to each roll, the running state of the belt is adjusted by the operation of the steering mechanism 50 and corrected to a normal running state. In addition, since the tension correcting mechanism 60 operates in conjunction with the operation of the steering mechanism 50, the change in the belt tension caused by the operation of the steering mechanism 50 is corrected, and the belt tension may be generated due to the fluctuation in the tension. Preventive belt twisting is prevented. Therefore, the toner image formed by the image forming unit 10 is primarily transferred to the correct transfer position of the intermediate transfer belt 21, and the toner image transferred to the intermediate transfer belt 21 is next transferred to the correct transfer position of the recording sheet P. Is secondarily transcribed. Further, the toner image transferred from each image forming unit 10 to the intermediate transfer belt 21 is not distorted, and the toner image retransferred from the intermediate transfer belt 21 to the recording sheet P also has a large skew. There is no fear. Furthermore, even when a full-color image is formed, image quality defects such as color misregistration and color unevenness due to poor running state of the intermediate transfer belt 21 do not occur.

[Second Embodiment] FIGS. 12 and 13 show a second embodiment of the present invention. FIG. 12 is a schematic explanatory view showing the entire configuration of an image forming apparatus according to the second embodiment. FIG. 2 is an explanatory view showing a sheet conveyance transfer belt mechanism employed in the image forming apparatus.

In the image forming apparatus according to the second embodiment, a sheet transport transfer belt mechanism 8 is used in place of the intermediate transfer belt mechanism 20.
The configuration is the same as that of the image forming apparatus according to the first embodiment except that 0 is adopted. That is, when a full-color image is formed by this image forming apparatus, four color toner images individually formed by the four image forming units 10 are used.
The recording sheet P that is adsorbed and conveyed to the surface of the sheet conveyance transfer belt 81 of the sheet conveyance transfer belt mechanism 80 is sequentially transferred so as to be superimposed on each other, and the transferred recording sheet P is transferred from the sheet conveyance transfer belt 81 The sheet is separated and sent to the transfer device 35.

The sheet transporting transfer belt mechanism 80 employed in this embodiment is configured such that a sheet transporting transfer belt 81 as an endless belt is stretched around a driving roll 82, a driven roll 83, and a tension roll 85. The vehicle is driven to rotate in the direction of arrow B by the rotational power of. Each of the rolls is rotatably supported by a bearing. Reference numeral 88 in FIG. 12 includes a belt cleaner for the sheet conveyance transfer belt 81, and 89 includes a sensor unit that detects the presence or absence of a belt home mark formed at the side end of the sheet conveyance transfer belt 81 and the position of the belt edge. It is a detection device. Reference numeral 86 in FIG. 1 denotes a sheet suction device that electrostatically sucks the recording sheet P onto the surface of the sheet transfer belt 81.

Then, the sheet transport transfer belt mechanism 8
As shown in FIG. 13, the drive roll 82 of the intermediate transfer belt mechanism 20 is substantially the same as the intermediate transfer belt mechanism 20 in the first embodiment.
Is provided with a steering mechanism 50 for adjusting the running state of the sheet conveying transfer belt 81 by displacing one end of the tension roller 85 in a predetermined adjustment direction J, K. , M, a tension correction mechanism 60 for correcting a change in the tension of the sheet conveying transfer belt 81 caused by the displacement of the driving roll 82 by the steering mechanism 50 is provided.

The drive roll 82, the steering mechanism 50, the tension roll 85, and the tension correcting means 60 of the sheet transport transfer belt mechanism 80 are all the same as the drive roll 22 of the intermediate transfer belt mechanism 20 in the first embodiment. The structure is substantially the same as that of the steering mechanism 50, the tension roll 25, and the tension correcting means 60 (see FIGS. 2 to 4). Further, the steering mechanism 50 of the belt mechanism 80 is used.
As shown in FIG. 13, the tension correcting means 60 is connected to a control unit 70, as in the first embodiment, and each operation is controlled by the control unit 70.

Next, the sheet transport transfer belt mechanism 80
The operation of the steering mechanism 50 and the tension correcting means 60 in the above will be described.

In this image forming apparatus, the tension correcting mechanism 60 operates in conjunction with the displacement operation of the drive roll 82 by the steering mechanism 50 to displace the tension roll 85 in the predetermined correction directions L and M.
The change in the tension of the sheet conveyance transfer belt 81 caused by the displacement operation of the drive roll 82 due to the above is corrected. The operation contents of the mechanisms 50 and 60 at this time are basically the same as those of the first embodiment.

FIGS. 14 and 15 show the case where the tension roll 85 is tilted by the tension correction mechanism 60 in accordance with the correction angle β (however, the operation is performed in conjunction with the displacement of the drive roll 22 by the steering mechanism 50). This shows the behavior of the sheet conveying transfer belt 81.

That is, as shown in FIG. 14, when the drive roll 82 is displaced in the adjustment direction J by the tension angle + α, the tension roll 85 is tilted by the correction angle + β and displaced in the correction direction L. Thereby, the sheet conveyance transfer belt 81 starts traveling while being displaced from the horizontal reference position H toward the end of the drive roll 22 displaced in the adjustment direction J from the horizontal reference position H, as indicated by the two-dot chain line in the figure. The vehicle travels while being displaced from the center reference position O in the correction direction L to the end of the tension roll 85 where the belt tension is weakened. As a result, the sheet conveyance transfer belt 81 is displaced by the drive roll 82 in the adjustment direction J.
The tension of the portion on the side of the displaced drive roll 82 increases, but the change in the tension is canceled out by the displacement operation of the tension roll 85 in the correction direction L, which is the direction in which the tension is reduced. There is no twist.

On the other hand, as shown in FIG.
Is displaced in the adjustment direction K by the tension angle −α, the tension roll 25 is tilted by the correction angle −β and displaced in the correction direction M. As a result, the sheet conveying transfer belt 81 is moved from the horizontal reference position H in the adjustment direction k as shown by a two-dot chain line in the drawing.
At the same time as starting to travel while being displaced toward the end side opposite to the end side of the tension roll 85, which is displaced in the correction direction M from the center reference position O to increase the belt tension. It will run while being displaced. As a result, by the displacement operation of the drive roll 82 in the adjustment direction K,
Although the tension of the portion of the belt 81 on the side of the displaced drive roll 82 is weakened, the change in the tension is canceled out and corrected by the displacement operation of the tension roll 85 in the correction direction M, which is the direction in which the tension is increased. But never twist.

According to the image forming apparatus of the second embodiment,
Even if the sheet conveying transfer belt 81 is meandering or running offset with respect to each roll, the running state of the belt is adjusted by the operation of the steering mechanism 50,
Corrected to normal running conditions. In addition, since the tension correcting mechanism 60 operates in conjunction with the operation of the steering mechanism 50, the change in the belt tension caused by the operation of the steering mechanism 50 is corrected, and the belt tension may be generated due to the fluctuation in the tension. Preventive belt twisting is prevented. For this reason, the toner image formed by the image forming unit 10 is not distorted or skewed, and the recording sheet P which is adsorbed and conveyed by the sheet conveyance transfer belt 81 is conveyed.
Satisfactorily transferred to the correct transfer position. Further, even when a full-color image is formed, image quality defects such as color misregistration and color unevenness due to poor running state of the belt 81 do not occur.

[Embodiment 3] FIG. 16 shows a third embodiment of the present invention.
FIG. 9 is an explanatory diagram illustrating a belt traveling mechanism employed in the image forming apparatus according to the third embodiment. The image forming apparatus according to the third embodiment is the same as the image forming apparatus according to the second embodiment except that, for example, a sheet transport transfer belt mechanism 90 having a different configuration is used instead of the sheet transport transfer belt mechanism 80 according to the second embodiment. It has a configuration.

In the sheet conveying transfer belt mechanism 90 according to the third embodiment, a sheet conveying transfer belt 91 as an endless belt generally includes a driving roll 92, a driven roll 93,
The drive roll 92 is stretched around the tension roll 94 and the tension roll 95 to rotate in the direction of arrow B by the rotational power of the drive roll 92. Each of the rolls is rotatably supported by a bearing. Reference numeral 98 in FIG. 16 denotes a belt cleaner provided with a cleaning blade 98a disposed so as to contact the sheet conveyance transfer belt 81;
Reference numeral 9 denotes a detection device including a sensor unit 99a for detecting the presence or absence of a belt home mark formed at the side end of the sheet conveyance transfer belt 91 and the position of the belt edge.

Then, the sheet conveying transfer belt mechanism 9
0, the one end of the drive roll 92 is fixed in the same adjustment direction J, as in the belt mechanism 80 in the second embodiment.
A steering mechanism 50 is provided to adjust the running state of the sheet conveyance transfer belt 91 by displacing the belt cleaner to K, and one end of the cleaning belt 98a of the belt cleaner is moved in a predetermined correction direction L, M.
The steering mechanism 5 is displaced along
A tension correction mechanism 60 is provided for correcting a change in the tension of the sheet conveyance transfer belt 91 caused by the displacement of the drive roll 92 due to zero.

The drive roll 92 of the belt mechanism 90 and the steering mechanism 50 of the belt mechanism 90 are the same as those of the drive roll 8 of the belt mechanism 80 in the second embodiment.
2. It has substantially the same configuration as the steering mechanism 50 (see FIGS. 2 to 4). Then, the tension correction mechanism 60
17, as shown in FIG. 17, depending on whether one of the ends of the cleaning blade 98a abutting on the sheet transfer belt 91 is pressed to the belt 81 stronger than normal or weaker than normal. , To increase or decrease the contact pressure. That is, the cleaning blade 89a is displaced in the correction direction M corresponding to the direction away from the belt 91 so that the contact pressure E1 smaller than the contact pressure E0 in the normal state (dotted arrow in the drawing) E0 is exerted. Alternatively, the blade 89a is displaced in the correction direction M corresponding to the direction in which the blade 89 bites into the belt 91 so as to exert a contact pressure E2 greater than the normal contact pressure E0. The steering mechanism 50 and the tension correcting means 60 in the belt mechanism 90 are connected to a control unit 70, as in the second embodiment, and each operation is controlled by the control unit 70.

Next, the sheet conveying transfer belt mechanism 90
The operation of the steering mechanism 50 and the tension correcting means 60 in the above will be described.

In this image forming apparatus, the tension correction mechanism 60 operates in conjunction with the displacement of the drive roll 92 by the steering mechanism 50 to displace the cleaning blade 98a in the predetermined correction directions L and M. The change in the tension of the sheet conveyance transfer belt 91 caused by the displacement operation of the drive roll 92 due to the above is corrected. The operation contents of the mechanisms 50 and 60 at this time are basically the same as those of the second embodiment.

That is, as shown in FIG. 17A, when the drive roll 92 is displaced in the adjustment direction J by the tension angle + α by the steering mechanism 50, the tension correction mechanism 6
By 0, the cleaning blade 98a is displaced in the correction direction L. Thereby, the sheet conveyance transfer belt 91
Starts running while being displaced from the horizontal reference position H toward the end of the drive roll 22 displaced in the adjustment direction J from the horizontal reference position H as shown by a two-dot chain line, Cleaning blade 98a with reduced tension
The vehicle travels while being displaced toward the end. As a result, by the displacement operation of the drive roll 92 in the adjustment direction J,
The tension of the displaced portion of the sheet transfer belt 91 on the drive roll 92 side increases. However, the displacement of the cleaning blade 98a in the correction direction L, which is the direction in which the tension of the cleaning blade 98a decreases, cancels out the change in the tension and corrects it. Therefore, the belt 91 is not twisted.

On the other hand, as shown in FIG.
When the cleaning blade 98a is displaced only in the adjustment direction K, the cleaning blade 98a is displaced in the correction direction M by the tension correction mechanism 60. As a result, the sheet conveyance transfer belt 91 is displaced toward the end opposite to the end of the drive roll 92 displaced in the adjustment direction K from the horizontal reference position H as indicated by the two-dot chain line in the drawing. At the same time, the cleaning blade 98a is displaced in the correction direction M, and travels while being displaced toward the end of the cleaning blade 98a in which the belt tension is increased. As a result, the displacement of the drive roll 92 in the adjustment direction K weakens the tension of the belt 91 on the displaced drive roll 92 side.
Since the change in the tension is canceled out and corrected by the displacement operation in the correction direction M which is the tension increasing direction of a, the belt 91 is not twisted.

[Fourth Embodiment] FIG. 17 shows a fourth embodiment of the present invention.
FIG. 9 is an explanatory diagram illustrating a belt traveling mechanism employed in the image forming apparatus according to the fourth embodiment. The image forming apparatus according to the fourth embodiment has the same configuration as the image forming apparatus according to the first embodiment, for example, except that a part of the intermediate transfer belt mechanism 20 is changed.

That is, the intermediate transfer belt mechanism 20 in the fourth embodiment first has its steering mechanism 50
However, it is configured such that the drive roll 22 displaced by such a mechanism is displaced in predetermined adjustment directions J and K.
The adjustment directions J and K of the drive roll 22 at this time are shown in FIG.
As shown in FIG. 6, when one end of the drive roll 22 is tilted in each of the directions J and K, the drive roll 22 of the intermediate transfer belt 21 and the rolls 27 located before and after in the belt running direction B of the roll 22 are arranged. , 23 (the entire belt length is L) is the driving roll 22.
Is a direction that changes in comparison with the belt circumference on the other end side (the side that becomes a fulcrum at the time of tilting). In the case of this embodiment, when one end of the drive roll 22 is tilted upward in the adjustment direction J, the belt circumferential length L1 is shortened, and on the contrary, it is tilted downward in the adjustment direction K. In some cases, the belt circumference L1 becomes longer.

In the intermediate transfer belt mechanism 20, the tension correction mechanism 60 uses the tension roll (tension applying roll) 25 to drive the drive roll 22 by the steering mechanism 50.
The predetermined correction directions L, L associated with the above adjustment directions J, K
M. The correction directions L and M of the tension roll 25 at this time are shown in FIGS.
As shown in FIG. 3, an emission position 25b where the side end 21a of the intermediate transfer belt 21 comes into contact with the tension roll 25 for the first time during traveling when the side end 21a of the belt separates from the tension roll 25. Are configured to be displaced in a direction having a positional relationship shifted in the same direction as the displacement direction (D, E) of the intermediate transfer belt 21 adjusted by the displacement operation of the steering mechanism 50.

In this adjustment / correction mechanism 60, FIG.
As shown in FIG. 5, the correction directions L and M of the tension roll 25 are set in a direction along a biasing direction F (a direction in which the intermediate transfer belt 21 is pushed almost vertically) by a tension applying mechanism (not shown). , This correction direction L,
Roll shaft 2 of tension roll 25 to secure M
Support frame 4 for displaceably supporting 5b bearing 41a
The long hole 46b formed in 6a is formed such that the center line along the longitudinal direction is parallel to the correction directions L and M. The adjustment correction mechanism 60 is connected to the tension roll 25 by a cam mechanism or the like as in the first embodiment.
Does not adopt a configuration in which is tilted in the correction directions L and M,
Therefore, unlike the first embodiment, the control unit (see FIG. 2)
Also not connected. Therefore, when the drive roll 22 is tilted in the above-mentioned predetermined adjustment directions J and K by the operation of the steering mechanism 50 based on the control of the control unit 70, the tension roll 25 is moved so as to follow the operation.
The guide is regulated by 6b and is displaced in the predetermined correction directions L and M. As for the correction directions L and M of the tension roll 25, as long as the relationship between the incident position and the output position with respect to the intermediate transfer belt 21 accompanying the displacement operation of the steering mechanism 50 described above is satisfied, the tension applying mechanism is used. The direction does not have to be along the biasing direction F.

By the way, the intermediate transfer belt mechanism 20
In other words, the drive roller 22 displaced by the steering mechanism 50 is moved in a special adjustment direction Q, in which the belt circumferential length L1 of the intermediate transfer belt 21 is not changed by the displacement of the roll 22, as illustrated in FIG. At least it is possible to avoid a configuration that can be displaced to R.

That is, the special adjustment directions Q and R are, as shown in FIG. 26b, a roll 27 arranged at a position where the moving direction (Q, R) of the drive roll 22 hits the belt running direction before and after. The direction is such that a locus is drawn with each central part of 23 as the focal point of an ellipse (an ellipse indicated by a dotted line).
This means that the drive roll 22 and the rolls 27 and 23 have the same roll diameter as shown in FIG.
The center of the driving roll 22 is represented by f ₁ ,
Each center 3 after having the f _2, f _3, if the trajectory of the drive roll 22 and a part of the ellipse and the focal point of the center f _2, f _3, generally in the center f _1, f from the mathematical definition Distance l ₁ between ₂
It is known that the sum of the distance and the distance l ₂ between the centers f ₁ and f ₃ is constant. The amount of change in the sum of the _two distances l ₁ and l ₂ is determined by the direction (Q,
Also, it becomes "zero" when displaced to R). Therefore, only when the drive roll 22 is displaced in the special adjustment directions Q and R, the belt circumferential length L1 is constant and does not change regardless of the displacement of the drive roll 22. For this reason, the adjustment direction of the drive roll 22 by the steering mechanism 50 may be set to be at least a direction other than the special adjustment directions Q and R.

In the intermediate transfer belt mechanism 20 having the steering mechanism 50 and the tension roll 25, the driving roll 22 is driven by the steering mechanism 50.
If the tension roll 25 (one end of the tension roll 25) is arbitrarily displaced when is tilted in the adjustment directions J and K, the steering adjustment operation of the endless belt 21 by the steering mechanism 50 may be hindered. FIG. 27 shows a state in which the belt 21 is shifted (displaced) when the drive roll 22 is tilted by the steering mechanism 50. In FIG. 27, particularly when the drive roll 22 is tilted downward, the belt 21 is moved by the behavior of the tension roll 25.
Indicates a state in which it is not displaced by the expected amount. The dotted line in the figure shows a state where the displacement is performed as expected. In this embodiment, such a problem is also solved as described later.

Next, the operation of the steering mechanism 50 and the tension correcting means 60 in the intermediate transfer belt mechanism 20 will be described.

In this image forming apparatus, the tension roll 25 by the tension correction mechanism 60 is displaced in the predetermined correction directions L and M following the displacement operation of the drive roll 22 by the steering mechanism 50, whereby the drive roll by the steering mechanism 50 is moved. The change in tension of the intermediate transfer belt 21 caused by the displacement operation of the belt 22 is substantially corrected. The operation contents of the steering mechanism 50 at this time are basically the same as those of the first embodiment.

First, as shown in FIG. 22, the steering mechanism 50 causes the drive roll 22 to move upward in the adjustment direction J.
When the intermediate transfer belt 21 is displaced by the steering angle + α, the circumferential length L1 of the intermediate transfer belt 21 changes in a direction in which the circumferential length L1 increases, so that the tension roll 85 is biased by the tension applying mechanism so as to absorb the increase in the circumferential length L1. Displaced in the correction direction L while being restricted by the elongated hole 46b against F. As a result, the intermediate transfer belt 21 is
2, the vehicle starts traveling while being displaced in the direction indicated by the dotted arrow D in the drawing due to the displacement in the adjustment direction J, and travels in a state where the belt tension is reduced to some extent by the displacement of the tension roll 25 in the correction direction L. Become like As a result, the tension at the one end side of the displaced drive roll 22 of the intermediate transfer belt 21 is increased by the displacement operation of the drive roll 22 in the adjustment direction J, but the tension roll 25 is displaced.
Is displaced in the correction direction L, which also corresponds to the direction in which the tension decreases, so that the change in tension is almost canceled and corrected, so that the belt 21 is not twisted. Moreover, the displacement of the tension roll 25 in the correction direction L causes the roll 25 to move.
, The output position 25b of the intermediate transfer belt 21 with respect to the incident position 25a is shifted in the same direction as the displacement direction (D) of the intermediate transfer belt 21 adjusted by the displacement operation of the steering mechanism 50.
In 1, the displacement in the displacement direction (D) is promoted also by the tension roll 25, and the adjustment action by the steering mechanism 50 is properly exhibited as scheduled.

On the other hand, as shown in FIG. 23, the drive mechanism 22 is moved downward by the steering mechanism 50 in the adjustment direction K.
When the intermediate transfer belt 21 is displaced by the tension angle -α, the circumferential length L1 of the intermediate transfer belt 21 changes in a direction in which the circumferential length L1 decreases (shortens), and the tension roll 85 applies tension so as to compensate for the decrease in the circumferential length L1. It is displaced in the correction direction M while being regulated by the elongated hole 46b based on the urging force F by the mechanism. As a result, the intermediate transfer belt 21 starts running while being displaced in the direction indicated by the dotted arrow E in the drawing due to the displacement of the drive roll 22 in the adjustment direction K, and at the same time, due to the displacement of the tension roll 25 in the correction direction M. The vehicle runs with the belt tension reinforced to some extent. As a result, the tension of the one end side of the displaced drive roll 22 of the intermediate transfer belt 21 is reduced by the displacement operation of the drive roll 22 in the adjustment direction K, but the tension roll 25 is displaced.
Is displaced in the correction direction M, which also corresponds to the tension increasing direction, and the change in the tension is almost canceled and corrected, so that the belt 21 does not twist. In addition, the displacement of the tension roll 25 in the correction direction M
, The emission position 25b of the intermediate transfer belt 21 with respect to the incident position 25a is shifted in the same direction as the displacement direction (E) of the intermediate transfer belt 21 adjusted by the displacement operation of the steering mechanism 50.
In 1, the displacement in the displacement direction (E) is promoted also by the tension roll 25, and the adjustment action by the steering mechanism 50 is properly exhibited as scheduled.

According to the image forming apparatus of the fourth embodiment,
Even if the intermediate transfer belt 21 runs meandering or deviates with respect to each roll, the running state of the belt is adjusted by the operation of the steering mechanism 50 and corrected to a normal running state. In addition, the tension roll 25 is displaced in a predetermined correction direction by the tension correction mechanism 60 following the adjustment operation of the drive roll 22 of the steering mechanism 50, thereby causing a change in the belt tension caused by the operation of the steering mechanism 50. Is substantially corrected, belt torsion that may occur due to the fluctuation in the tension is prevented, and the running state of the intermediate transfer belt 21 by the steering mechanism 50 is properly adjusted as scheduled. FIG. 21 shows a state in which the intermediate transfer belt 21 is shifted (displaced) when the driving roll 22 is tilted by the steering mechanism 50, and the adjustment action by the steering mechanism is working properly as scheduled. This can be seen (see FIG. 27). Therefore, the toner image formed by the image forming unit 10 is satisfactorily transferred to the correct transfer position of the recording sheet P conveyed while being attracted and conveyed by the sheet conveyance transfer belt 81 without distortion or skew. . Further, even when a full-color image is formed, image quality defects such as color misregistration and color unevenness due to poor running state of the belt 81 do not occur.

[Other Embodiments] In the first and second embodiments, the case where there are a plurality of image forming units 10 has been described as an example. Embodiment 1
4, the case where the endless belt is an intermediate transfer belt or a sheet conveyance transfer belt is illustrated, but the endless belt may be a photosensitive belt.

[0074]

As described above, according to the image forming apparatus of the present invention, when one of the rolls supporting the endless belt is displaced and the running state of the belt is adjusted, the displacing operation of the roll is performed. It is possible to reliably and easily prevent the belt from being twisted due to the change in the tension of the endless belt. Therefore, when an image is formed using this image forming apparatus, it is possible to form a good image without image quality defects caused by meandering and twisting of the endless belt.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a main part of an image forming apparatus according to a first embodiment.

FIG. 2 is an explanatory diagram illustrating a configuration of an intermediate transfer belt mechanism according to the first embodiment.

3A is a partial cross-sectional explanatory view showing a configuration of a drive roll and a steering mechanism, and FIG. 3B is a partial cross-sectional explanatory view showing a configuration of a tension roll and a tension correction mechanism.
(C) is an explanatory view showing a main part of a steering mechanism and a tension correction mechanism.

FIG. 4 is a correlation diagram showing a relationship between a rotation angle of an eccentric cam and a displacement amount of the eccentric cam in a steering mechanism and a tension correction mechanism.

FIG. 5 is a flowchart showing an operation procedure of a steering mechanism and a tension correction mechanism.

FIG. 6 is an explanatory diagram showing a state of the intermediate transfer belt mechanism in a normal state.

FIG. 7 is an explanatory diagram illustrating a state of the intermediate transfer belt mechanism when the steering mechanism operates.

FIG. 8 is an explanatory diagram showing the state of the intermediate transfer belt mechanism when the steering mechanism (when the tension increases) and the tension correction mechanism are operating.

FIG. 9 is an explanatory diagram showing the state of the intermediate transfer belt mechanism when the steering mechanism (when the tension is reduced) and the tension correction mechanism are operating.

FIG. 10 is a correlation diagram illustrating a relationship between a steering angle and a belt displacement amount.

FIG. 11 is a correlation diagram showing a relationship between a belt rotation amount and a belt displacement amount when the steering angle is displaced;

FIG. 12 is a schematic explanatory view showing a main part of the image forming apparatus according to the second embodiment.

FIG. 13 is an explanatory diagram illustrating a configuration of a sheet conveyance transfer belt mechanism according to the second embodiment.

FIG. 14: Steering mechanism (when tension increases)
FIG. 4 is an explanatory diagram illustrating a state of a sheet conveyance transfer belt mechanism when a tension correction mechanism operates.

FIG. 15: Steering mechanism (when tension decreases)
FIG. 4 is an explanatory diagram illustrating a state of a sheet conveyance transfer belt mechanism when a tension correction mechanism operates.

FIG. 16 is an explanatory diagram illustrating a configuration of a sheet conveyance transfer belt mechanism according to a third embodiment.

FIG. 17 is an explanatory diagram showing a state of the sheet conveyance transfer belt mechanism when the steering mechanism (when the tension increases or decreases) and the tension correction mechanism operate.

FIG. 18 is an explanatory diagram illustrating a configuration of an intermediate transfer belt mechanism according to a fourth embodiment.

FIG. 19 is an explanatory diagram showing a state change of the intermediate transfer belt according to a displacement operation of a drive roll by a steering mechanism.

20A is a partial cross-sectional explanatory view showing a configuration of a tension roll and a tension correcting mechanism and the like, and FIG. 20B is an explanatory diagram showing a main part of the tension correcting mechanism.

FIG. 21 is a correlation diagram illustrating a biased (displaced) state of the intermediate transfer belt when the drive roll is tilted by the steering mechanism according to the fourth embodiment.

FIG. 22: Steering mechanism (when tension increases)
FIG. 4 is an explanatory diagram illustrating a state of an intermediate transfer belt mechanism accompanying operation of a tension correction mechanism.

FIG. 23: Steering mechanism (when tension decreases)
FIG. 4 is an explanatory diagram illustrating a state of an intermediate transfer belt mechanism accompanying operation of a tension correction mechanism.

FIG. 24 is a schematic explanatory view showing a configuration of a conventional belt traveling mechanism.

FIG. 25 is a schematic explanatory view showing a belt twist phenomenon in a conventional belt traveling mechanism.

FIG. 26 is an explanatory diagram showing a configuration related to a driving roll adjustment direction by a steering mechanism, which is not adopted in the fourth embodiment.

FIG. 27 is a correlation diagram showing a biased state of the intermediate transfer belt when the driving roll is tilted by the steering mechanism (an example in which the belt is not as expected).

[Explanation of symbols]

Reference numeral 21: intermediate transfer belt (endless belt), 22 to 27: plural rolls, 25, 85: tension roll (contact body), 50: steering mechanism (belt running adjustment mechanism), 60: tension correction mechanism, 81, 91 ... Sheet conveyance transfer belt (endless belt), 98a: cleaning blade (contact body), J, K: adjustment direction of the steering mechanism (roll displacement direction), L, M ... correction direction of the tension compensation mechanism (displacement direction of the contact body) ).

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mitsuaki Kuroda 2274 Hongo, Ebina City, Kanagawa Prefecture, within Fuji Xerox Co., Ltd. (72) Inventor Yukitomo Shigemori 2274 Hongo, Ebina City, Kanagawa Prefecture, within Fuji Xerox Co., Ltd. 72) Inventor Kazuo Takano 2274 Hongo, Ebina City, Kanagawa Prefecture, within Fuji Xerox Co., Ltd. (72) Inventor Seiichi Takayama 2274 Hongo, Ebina City, Kanagawa Prefecture, within Fuji Xerox Co., Ltd. (72) Naoto Nishi, Kanagawa Prefecture 2274 Hongo, Ebina City, Fuji Xerox Co., Ltd. (72) Inventor Norio Hokari 2274 Hongo, Ebina City, Kanagawa Prefecture, Fuji Xerox Co., Ltd. (72) Inventor Takashi Hoshino 2274 Hongo, Ebina City, Kanagawa Prefecture, Fuji Zero (72) Inventor Kozo Tagawa Ebi shrimp, Kanagawa 2274, Hongo-shi, Fuji Xerox Co., Ltd. (72) Inventor Satoshi Nishikawa 2274, Hongo, Ebina-shi, Kanagawa Prefecture, Fuji Xerox Co., Ltd. (72) Yoshihiko Mitamura 2274, Hongo, Ebina-shi, Kanagawa Prefecture, Fuji Xerox Inside the corporation

Claims (6)

[Claims] 1. An apparatus for forming an image in accordance with image information, comprising: a plurality of rolls rotatably supported; an endless belt stretched and run on the plurality of rolls; A belt travel adjusting mechanism that adjusts a traveling state of the endless belt by displacing at least one end thereof; and a change in tension of the endless belt caused by a roll displacement operation by the belt travel adjusting mechanism, in a width direction of the belt. An image forming apparatus comprising: a tension correcting mechanism that corrects by displacing a contact body that is in contact with the image forming apparatus. 2. The apparatus according to claim 1, wherein the contact body of the tension correcting mechanism is at least one of the rolls other than the roll displaced by the belt travel adjusting mechanism. Image forming device. 3. The image forming apparatus according to claim 1, wherein the contact member of the tension correcting mechanism is a blade pressed against an endless belt. 4. The image forming apparatus according to claim 1, wherein the tension correction mechanism is controlled to operate in conjunction with a displacement operation of the belt travel adjustment mechanism. 5. The apparatus according to claim 1, wherein the belt travel adjusting mechanism moves the roll to be displaced between the roll of the endless belt and each roll positioned before and after in the belt travel direction of the roll. The tension correcting mechanism is configured to be displaced in a direction in which the circumferential length changes, and the tension correcting mechanism uses a tension applying roll that applies tension to the endless belt as the contact body, and the tension applying roll to the roll. The end position of the endless belt is adjusted by the displacement operation of the belt travel adjustment mechanism, and the emission position where the side end of the endless belt separates from the roll is adjusted with respect to the incident position where the side end of the endless belt first contacts during traveling. An image forming apparatus configured to be displaced in a direction having a positional relationship shifted in the same direction as the direction. 6. The image forming apparatus according to claim 1, wherein the endless belt is at least one of a photosensitive belt, a sheet conveyance transfer belt, and an intermediate transfer belt.