JP2000264479A - Belt conveying device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent fluctuation of a belt by bringing a contact member into contact with a belt, while adjusting the contact member in the operation level calculated by an operation level calculating means by a contact member driving means. SOLUTION: The inclination angle of a steering roller 3 is controlled by driving a steering motor 11 by a steering control part 20, on the basis of a belt edge signal output from an edge sensor 10 to correct the meandering of an intermediate belt 1. An operation level calculating means (attitude calculating means 27, a corresponding relationship calculating means 26) is provided aside from the contact member driving means (driving means) 25. The driving means 25 adjusts the attitude of the contact member (secondary transfer roller) 16 and a cleaning unit 9, on the basis of the attitude calculated by the attitude calculating means 27, and then the secondary transfer roller 16 and the cleaning unit 9 are contacted with the intermediate belt 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a belt conveying device provided with a belt moving along a predetermined path, and an image forming apparatus to which the belt conveying device is applied.

[0002]

2. Description of the Related Art In recent years, it has been desired to increase the speed and reduce the size of an image forming apparatus, and a belt is used for a photoreceptor on which a toner image is formed, an intermediate transfer member for receiving a toner image formed on the photoreceptor, and the like. There is an increasing demand for an image forming apparatus using the image forming apparatus. In an image forming apparatus using such a belt, members such as a cleaner and a transfer roll are often arranged so as to be able to freely contact and separate from the belt. In this case, when a member separated from the belt comes into contact with the belt, the belt meanders greatly, and the position of the belt fluctuates rapidly. Therefore, for example, when a member such as a cleaner or a transfer roll comes into contact with the belt during image formation, the influence of the fluctuation of the belt position appears on the image, and the image is easily deteriorated. In particular, in the color image forming apparatus, there is a problem that an image printed on a sheet undergoes color misregistration or color unevenness, and image quality is significantly reduced.

[0003]

In order to solve such a problem, a cleaner blade is gradually brought into contact with the belt from one edge to the other edge of the belt, so that the load applied to the belt changes rapidly. And Japanese Patent Application Laid-Open No. HEI 9-117176, and an image forming apparatus that predicts fluctuations in the load applied to the belt in advance and switches the belt drive gain to eliminate fluctuations in the belt. However, in these image forming apparatuses, the fluctuation of the belt with respect to the traveling direction of the belt is taken into consideration, but not taken into account in the width direction of the belt. In addition to these image forming apparatuses, an image forming apparatus that reduces the disturbance of the belt due to a shift in the parallelism between the rolls that stretch the belt by reducing the disturbance applied to the belt by an attenuating means (Japanese Patent Laid-Open Publication No. 10-
104998), but is not effective against disturbance directly applied to the belt.

[0004] In view of the above circumstances, it is an object of the present invention to provide a belt transport device in which belt fluctuation is suppressed, and an image forming apparatus to which the belt transport device is applied.

[0005]

According to the present invention, there is provided a belt conveying device which detects a belt moving along a predetermined path, and a position shift of the belt in a width direction from a predetermined reference moving path. A steering control means for correcting a displacement in the width direction of the belt by changing a steering control position in accordance with a displacement in the width direction of the belt detected by the displacement detection means; And a contact member capable of freely adjusting the action level of the belt in the width direction at the time of contact, and the action level of the contact member is freely adjusted, and the contact member is attached to the belt. A contact member driving means for making contact with and detachable from the contact member;
Referring to the correspondence calculated by the correspondence level between the action level at the time of contact with the belt and the steering control position of the steering control means, and the correspondence calculated by the correspondence calculation means, An operation level calculating unit that calculates an operation level of the contact member corresponding to a current steering control position in a state where the member is separated from the belt; wherein the contact member driving unit converts the contact member into the operation level calculation. The operation level is adjusted to the operation level calculated by the means and the belt is brought into contact with the belt.

Here, in the belt transport device of the present invention, the contact member driving means adjusts a posture of the contact member or a contact pressure difference in a belt width direction when the contact member contacts the belt. It is preferable to adjust the above-mentioned action level.

Further, in the belt transport device of the present invention, it is preferable that the contact member is a roll or a blade.

The image forming apparatus of the present invention is an image forming apparatus for forming an image on a sheet by forming a toner image and finally transferring and fixing the toner image on a predetermined sheet. A belt that moves along a predetermined path, which is employed in a process of forming or conveying a toner image,
Displacement detection means for detecting a displacement in the width direction of the belt from a predetermined reference movement path, and changing a steering control position according to the displacement in the width direction of the belt detected by the displacement detection means. A steering control means for correcting the displacement of the belt in the width direction, a contact member capable of freely contacting and separating from the belt and adjusting the action level to the displacement of the belt in the width direction at the time of contact , The contact member, while adjusting the operation level freely, a contact member driving means for allowing the contact member to come into contact with and detachably from the belt, the operation level of the contact member at the time of contact with the belt, A correspondence calculating means for calculating a correspondence between the steering control means and the steering control position; An operation level calculating unit that calculates an operation level of the contact member corresponding to a current steering control position in a state where the contact member is separated from the belt, with reference to the obtained correspondence relationship; However, the present invention is characterized in that the contact member is adjusted to the operation level calculated by the operation level calculation means and is brought into contact with the belt.

Here, the image forming apparatus of the present invention has a correspondence calculation mode for calculating a correspondence by the correspondence calculation means and an image formation mode for forming an image on a sheet. Preferably, the mode and the image forming mode are separately executed.

[0010]

Embodiments of the present invention will be described below.

FIG. 1 is a schematic configuration diagram showing an embodiment of an image forming apparatus of the present invention to which an embodiment of the belt conveying apparatus of the present invention is applied.

This image forming apparatus includes an intermediate transfer belt 1 for receiving a toner image. The intermediate transfer belt 1 is rotatably controlled by a driving roll 2, a steering roll 3, a backup roll 4, and idler rolls 5 and 6 while passing through a primary transfer position T1, a secondary transfer position T2, and a cleaning position C. It is stretched with tension. The intermediate transfer belt 1 is circulated in the direction of an arrow P (hereinafter, referred to as a process direction) by the driving roll 2. The steering roll 3 is a roll for adjusting the position of the intermediate transfer belt 1 in the width direction (a direction perpendicular to the paper surface of FIG. 1; hereinafter, referred to as a lateral direction).

The image forming apparatus has two toner image forming units 7 and 8. These two toner image forming units 7 and 8 are arranged in the process direction P on the movement path of the intermediate transfer belt 1 on the downstream side of the drive roll 2 and on the upstream side of the idler roll 5.

Each of the toner image forming units 7, 8 has a photosensitive drum 7a, 8 on which a toner image is formed on the surface.
a. Each of these photosensitive drums 7a, 8a
An image forming apparatus main body frame (not shown) is rotatably supported in the direction of arrow D via the primary transfer position T1. The toner images formed on the photosensitive drums 7a and 8a are transferred to the intermediate transfer belt 1 at a primary transfer position T1. Further, each of the toner image forming units 7 and 8 has raster scanners 7b and 8b for exposing and scanning the surfaces of the photosensitive drums 7a and 8a with a laser beam or the like. A cleaner 7c, a charger 7d, a yellow developing device 7e, and a cyan developing device 7f are arranged around the photosensitive drum 7a in the drum rotation direction D, and the intermediate transfer belt 1 is interposed therebetween. Then, the photosensitive drum 7
a primary transfer roll 7g is disposed between the first transfer roller 7a and the first transfer roller 7g. Around the photoreceptor drum 8a, a cleaner 8c, a charger 8d, and a developing device 8 of magenta are arranged in the drum rotation direction D.
e and black developing devices 8f are arranged in order, and a primary transfer roll 8g is arranged between the developing device 8f and the photosensitive drum 8a with the intermediate transfer belt 1 interposed therebetween.

Further, a cleaning device 9 is disposed at the cleaning position C. The cleaning device 9 includes a cleaning blade 9a for cleaning the intermediate transfer belt 1 by coming into contact with and separating from the intermediate transfer belt 1 and scraping off deposits such as toner adhered to the intermediate transfer belt 1; And a container 9b for storing the adhered substance scraped by the blade 9a.

Further, on the moving path of the intermediate transfer belt 1,
A belt home sensor 11 that detects a mark (not shown) provided on the back surface of the intermediate transfer belt 1 is disposed downstream of the drive roll 2 and upstream of the primary transfer roll 7g. Further, a lateral displacement of the intermediate transfer belt 1 from a predetermined reference movement path is detected downstream of the steering roll 3 and upstream of the idler roll 6 on the movement path of the intermediate transfer belt 1. An edge sensor 10 (an example of a displacement detection unit according to the present invention) is disposed. This edge sensor 10
The position of the edge (corresponding to an edge 1a shown in FIG. 3 described later) of the intermediate transfer belt 1 on the front surface of the paper surface shown in FIG. By detecting with respect to the vertical direction (see FIG. 3 described later), a positional deviation of the intermediate transfer belt 1 in a lateral direction from a predetermined reference movement path is detected.

FIG. 2 is a schematic configuration diagram showing a contact type sensor which is an example of the edge sensor 10.

The edge sensor 10 has a contact 10b, and the contact 10b is supported so as to be rotatable in a Z direction about a support shaft 10c provided at an intermediate portion thereof. One end 10d of the contact 10b is
Oa keeps the intermediate transfer belt 1 pressed against one edge 1a with a pressure of about 0.1N. A displacement sensor 10f that detects displacement of the contact 10b in the Z direction is provided at a position facing the other end 10e of the contact 10b.
Is arranged.

When the intermediate transfer belt 1 moves in the process direction P, the intermediate transfer belt 1 meanders (in the lateral direction R).
Movement) and the shape of the edge 1a itself of the intermediate transfer belt 1 causes the contact 10b of the edge sensor 10 to move
Displaced in the Z direction about 0c. At this time, in accordance with the displacement of the edge 1a of the intermediate transfer belt 1 in the lateral direction R, the displacement of the contact 10b of the edge sensor 10 in the Z direction changes. The signal output from the displacement sensor 10f fluctuates in accordance with the change in the amount of displacement, whereby the displacement of the intermediate transfer belt 1 in the lateral direction R from a predetermined reference movement path is continuously detected.

FIG. 3 is a schematic configuration diagram showing a non-contact type sensor which is another example of the edge sensor 10.

The edge sensor 10 has an LED (Light Emi) between the edge 1 a of the intermediate transfer belt 1.
(Tting Diode) 10g and its LED 10g
And a light amount sensor 10h for detecting the light amount of light emitted from the intermediate transfer belt 1 and passing beside the edge 1a of the intermediate transfer belt 1. When the intermediate transfer belt 1 moves in the process direction P, the edge sensor 10 emits light from the LED 10g due to the meandering of the intermediate transfer belt 1 and the shape of the edge 1a of the intermediate transfer belt 1 itself. The amount of light passing through the side of 1a changes. Therefore, it is possible to continuously detect the positional deviation of the intermediate transfer belt 1 from the predetermined reference movement path in the lateral direction R.

A signal detected by each of the edge sensors 10 is transmitted to a steering control unit 20 (FIG.
Reference). This steering control unit 20
An eccentric cam 2 to be described later is operated in accordance with a displacement of the intermediate transfer belt 1 in the lateral direction R detected by the edge sensor 10.
The tilt angle of the steering roll 3 is adjusted by changing the eccentric position 3 (an example of the steering control position according to the present invention). This steering roll 3
The intermediate transfer belt 1 is adjusted by adjusting the inclination angle of the intermediate transfer belt 1.
Is displaced in the lateral direction. The manner in which the lateral displacement of the intermediate transfer belt 1 is corrected will be described later in detail.

Returning to FIG. 1, the description will be continued.

In this image forming apparatus, the paper 13 on which an image is formed is accommodated in a paper cassette (not shown), and is fed one by one by a pickup roll 14 provided on the paper feeding side of the paper cassette. The fed out paper 13 is conveyed to a secondary transfer position T2 by a predetermined number of roll pairs 15 following a path shown by a broken line in the figure.
At the secondary transfer position T2, a secondary transfer roll 16 that comes into contact with and separates from the intermediate transfer belt 1 is disposed. The toner image transferred from the secondary transfer roll 16 to the intermediate transfer belt 1 at the primary transfer position T1 and transported to the secondary transfer position T2 by the rotation of the intermediate transfer belt 1 is transported to the secondary transfer position T2. This is a roll for transferring to the paper 13.
The secondary transfer roll 16 is driven by a driving unit 25 (see FIG. 5), which will be described later, so that the attitude of the intermediate transfer belt 1 at the time of contact is adjusted.

FIG. 4 is a schematic diagram showing a secondary transfer roll driving unit for driving the secondary transfer roll 16 included in the driving means.

The secondary transfer roll driving section 25a is provided with a ball screw 25b. This ball screw 25b
It is arranged to be rotatable in the direction of arrow a by driving the motor 25c. In addition, the secondary transfer roll driving unit 25a includes:
A threaded cylinder 25d to which the ball screw 25b is screwed is provided, and the threaded cylinder 25d is fixed to one end 16a of the secondary transfer roll 16.

The secondary transfer roll driving unit 25a thus configured is driven by a motor 25c to drive the ball screw 25.
When b rotates, the screwing cylinder 25d screwed to the ball screw 25b moves in the direction of arrow b. This screw cylinder 25
Due to the movement of d, one end 16a of the secondary transfer roll 16 becomes
The other end (not shown) opposite to the one end 16a is moved in the direction of arrow b as a pivot. Therefore, the motor 25c
By adjusting the driving amount of the secondary transfer roll 16
The angle formed between the intermediate transfer belt 1 and the lateral direction of the intermediate transfer belt 1 (the direction perpendicular to the paper surface of FIG. 4) at the time of contact with the intermediate transfer belt 1 is adjusted.
The posture at the time of contact with the intermediate transfer belt 1 is adjusted.
The driving means 25 is thus connected to the secondary transfer roll 16
Is adjusted at the time of contact with the intermediate transfer belt 1. In addition, the secondary transfer roll 16 is freely moved in the direction of arrow B. Due to the movement in the direction of the arrow B, the secondary transfer roll 16 comes into contact with the intermediate transfer belt 1 so as to be freely separated. Further, the driving means 25 is provided with the secondary transfer roll 16.
In addition, the intermediate transfer belt 1 of the cleaning blade 9a
In addition to adjusting the posture at the time of contact with the intermediate transfer belt 1, the cleaning blade 9a is brought into contact with the intermediate transfer belt 1 so as to be freely separated.

Returning to FIG. 1, the description will be continued.

The fixing device 18 fixes the toner image transferred on the paper 13 to the paper 13.

Next, a description will be given of how the image forming apparatus having the above-described configuration starts running the intermediate transfer belt 1 and forms a color image on the sheet 13.

FIG. 5 is a diagram specifically showing a path of a signal detected by the edge sensor in the image forming apparatus shown in FIG.

This image forming apparatus includes a steering arm 2
2 is provided. The steering arm 22 is rotatably supported at an intermediate portion thereof by a support shaft 24. One end 22a of the steering arm 22 is rotatably connected to one end of the steering roll 3, and an eccentric cam 23 fixed to the rotating shaft of the steering motor 21 is pressed against the other end 22b. The image forming apparatus includes a steering control unit 20 that controls driving of a steering motor 21. A combination of the steering control unit 20, the steering motor 21, the steering arm 22, the eccentric cam 23, the support shaft 24, and the steering arm 3 corresponds to a steering control unit according to the present invention.

When the running of the intermediate transfer belt 1 is started,
The edge sensor 10 detects a lateral displacement of the intermediate transfer belt 1 from a predetermined reference movement path, and outputs a belt edge signal indicating the displacement to the steering control unit 20. Further, the belt home sensor 11 detects the mark when the mark on the back surface of the intermediate transfer belt 1 passes over the belt home sensor 11 due to the traveling of the intermediate transfer belt 1, and indicates that the mark has been detected. Is output to the steering control unit 20. When the belt home signal output from the belt home sensor 11 is input to the steering control unit 20, the steering control unit 20 continuously samples the belt edge signal output from the edge sensor 10, and outputs the sampled belt edge signal. A control signal for controlling the rotation amount of the steering motor 21 is output to the steering motor 21 based on the signal. The steering motor 21 rotates by a rotation amount according to the control signal. The inclination angle of the steering roll 3 is controlled by the rotation amount of the steering motor 21, and the meandering of the intermediate transfer belt 1 is corrected.

FIG. 6 is an explanatory diagram showing how the meandering of the intermediate transfer belt is corrected.

FIGS. 6A, 6B and 6C respectively show, from left to right, a front view of the steering roll 3, a front view of the steering arm 22, and a steering motor 21 to which the eccentric cam 23 is attached. Is shown in a side view.

FIG. 6A shows a state in which the eccentric cam 23 stops at a predetermined angle and the steering roll 3 is held substantially horizontal (the inclination is almost zero) corresponding to the stop angle. I have. The steering roll 3 is supported in a cantilever manner in which one end 3b is pivoted (fixed) and the other end 3a is moved by a steering arm 22.

From this state, as shown in FIG.
When the eccentric cam 23 rotates counterclockwise due to the rotation of the steering motor 21, the steering arm 22 rotates in the θ1 direction according to the eccentric position of the eccentric cam 23.
Accordingly, one end 3a of the steering roll 3 moves upward, and the steering roll 3 is tilted by an angle corresponding to the amount of movement. Thereby, the intermediate transfer belt 1 moves to the one end 3a side of the steering roll 3.

On the other hand, as shown in FIG.
When the eccentric cam 23 rotates clockwise due to the rotation of the steering motor 21, the steering arm 22 rotates in the θ2 direction in accordance with the eccentric position of the eccentric cam 23. It is pushed down by the arm 22. Therefore, the intermediate transfer belt 1 moves to the other end 3 b opposite to the one end 3 a of the steering roll 3.

In the image forming apparatus of this embodiment, as described above, the steering control unit 20 drives the steering motor 21 based on the belt edge signal output from the edge sensor 10 to thereby control the inclination angle of the steering roll 3. Is corrected, and the meandering of the intermediate transfer belt 1 is corrected.

The image forming apparatus executes the image forming mode for forming an image on the sheet 13 while correcting the meandering of the intermediate transfer belt 1 as described above. Hereinafter, this image forming mode will be described.

In executing the image forming mode, the secondary transfer roll 16 and the cleaning device 9 are driven by the driving unit 2.
5, it is arranged in a state separated from the intermediate transfer belt 1. In this state, based on the detection of the mark on the back surface of the intermediate transfer belt 1 by the belt home sensor 11,
Exposure light is emitted from the raster scanners 7b and 8b (see FIG. 1) based on image signals, and electrostatic latent images corresponding to the respective colors of yellow and magenta are written on the surfaces of the respective photosensitive drums 7a and 8a. . Each photosensitive drum 7a, 8
The electrostatic latent images written to the developing devices 7e and 8e are rotated by rotating the photosensitive drums 7a and 8a in the direction of arrow D.
The toner images are respectively developed, and yellow and magenta toner images are formed on the respective photosensitive drums 7a and 8a. The yellow and magenta toner images formed on the photosensitive drums 7a and 8a are conveyed to the primary transfer position T1 and transferred to the intermediate transfer belt 1 at the primary transfer position T1. After the transfer of the yellow and magenta toner images to the intermediate transfer belt 1, the surfaces of the photosensitive drums 7a and 8a are cleaned by the cleaners 7c and 8c, respectively. On the other hand, the yellow and magenta toner images transferred to the intermediate transfer belt 1 return to the primary transfer position T1 via the secondary transfer position T2 and the cleaning position C by the movement of the intermediate transfer belt 1 in the process direction P. At this time, immediately after the yellow and magenta toner images pass through the secondary transfer position T2 and the cleaning position C, respectively, the driving unit 25 drives the secondary transfer roll 16 and the cleaning device 9 separated from the intermediate transfer belt 1 respectively. Is brought into contact with the intermediate transfer belt 1. The driving means 25
The intermediate transfer is performed by setting the postures of the secondary transfer roll 16 and the cleaning device 9 to the postures calculated by the posture calculation means (an example of an action level calculation means according to the present invention) 27 described later using the correspondence relation calculation means 26. It is in contact with the belt 1.

When the belt home sensor 11 detects the mark on the back surface of the intermediate transfer belt 1 again as the intermediate transfer belt 1 makes one revolution, the belt home sensor 11 applies the mark to the surface of each of the photosensitive drums 7a and 8a based on the detection. This time, an electrostatic latent image corresponding to each color of cyan and black is written, and a toner image of cyan and black is formed on each of the photosensitive drums 7a and 8a. The image is transferred to the transfer belt 1.

As described above, in the image forming apparatus of the present embodiment, first, in the first rotation of the intermediate transfer belt 1, the yellow and magenta toner images are transferred to the intermediate transfer belt 1, On the circumference, cyan and black toner images are transferred. That is, in the present embodiment, the intermediate transfer belt 1 is caused to make two rotations to transfer toner images of four colors of yellow, magenta, cyan, and black to the intermediate transfer belt 1.
Transfer to Therefore, the secondary transfer roll 16 and the cleaning device 9 that are not in contact with the intermediate transfer belt 1 first.
As described above, the yellow and magenta toner images contact the intermediate transfer belt 1 immediately after passing through the secondary transfer position T2 and the cleaning position C, respectively. When the toner images of four colors are transferred to the intermediate transfer belt 1,
The four color toner images are conveyed to the secondary transfer position T2 by the rotation of the intermediate transfer belt 1, and are collectively transferred to the paper 13 by the secondary transfer roll 16 which is in contact with the intermediate transfer belt 1.

By the way, the image forming apparatus of the present embodiment
As shown in FIG. 5, in addition to the driving unit 25, a posture calculating unit 27 and a correspondence calculating unit 26 are provided. As described above, the driving unit 25 is configured to control the postures of the secondary transfer roll 16 and the cleaning device 9. Is adjusted to the posture calculated by the posture calculation means 27, and the secondary transfer roll 16 and the cleaning device 9 are brought into contact with the intermediate transfer belt 1. However, if the image forming apparatus of the present embodiment temporarily Of the means 25, the attitude calculating means 27, and the correspondence calculating means 26, the attitude calculating means 27 and the correspondence calculating means 26 are not provided, and the attitudes of the secondary transfer roll 16 and the cleaning device 9 are not particularly adjusted. When the secondary transfer roll 16 and the cleaning device 9 are simply brought into contact with the intermediate transfer belt 1, the intermediate transfer belt 1 A cleaning device 9 meandering by contact respectively.

FIG. 7 is a diagram showing a lateral displacement of the intermediate transfer belt 1 when the secondary transfer roll 16 is simply brought into contact with the intermediate transfer belt 1.

Incidentally, even when the cleaning blade 9a of the cleaning device 9 is simply brought into contact with the intermediate transfer belt 1, the positional deviation of the intermediate transfer belt 1 in the lateral direction is caused by simply moving the secondary transfer roll 16 to the intermediate transfer belt 1. Therefore, the description is omitted when the cleaning blade 9 a is simply brought into contact with the intermediate transfer belt 1, and the secondary transfer roll 16 is simply brought into contact with the intermediate transfer belt 1. A description will be given only of the case where the control is performed.

In the state where the positional deviation E of the intermediate transfer belt 1 is 0 (that is, there is no positional deviation of the intermediate transfer belt 1), at the time t = a, the secondary transfer roll 16
, A force acts on the intermediate transfer belt 1, so that the intermediate transfer belt 1 meanders, and a displacement E of the intermediate transfer belt 1 occurs. The position shift E becomes a maximum E1 (hereinafter, the maximum value E1 of the position shift E is referred to as a walk amount W). When the position shift E of the intermediate transfer belt 1 occurs, the steering roll is controlled by the steering control unit 20. 3 is adjusted, and at time t = b, the positional deviation E of the intermediate transfer belt 1 becomes zero again. However, a <
During the time t <b, the position of the intermediate transfer belt 1 is displaced, so that after the secondary transfer roll 16 comes into contact with the intermediate transfer belt 1, cyan,
The transfer position of the black toner image may be shifted. Therefore, the image formed on the paper 13 may be deteriorated.

On the other hand, in the present embodiment, as described above, the positions of the secondary transfer roll 16 and the cleaning device 9 are adjusted to the positions calculated by the position calculating means 25, and And cleaning device 9
Are brought into contact with the intermediate transfer belt 1. By bringing the secondary transfer roll 16 and the cleaning device 9 into contact with the intermediate transfer belt 1 in this manner, the walk amount of the intermediate transfer belt 1 is suppressed, and the displacement of the intermediate transfer belt 1 is suppressed. Hereinafter, the principle of suppressing the displacement of the intermediate transfer belt 1 will be described.

It should be noted that, regardless of whether the secondary transfer roll 16 or the cleaning device 9 is brought into contact with the intermediate transfer belt 1, the principle of suppressing the displacement of the intermediate transfer belt 1 is the same. Taking the case where the secondary transfer roll 16 is brought into contact with the transfer belt 1 as an example, the principle of suppressing the displacement of the intermediate transfer belt 1 will be described.

FIG. 8 is a graph showing the relationship between the secondary transfer roll position and the walk amount W, and FIG. 9 is a graph showing the relationship between the secondary transfer roll position and the steering roll angle δ.

Here, the horizontal axis in FIGS. 8 and 9 is the position of the secondary transfer roll. The secondary transfer roll position is a position of one end 16a of the secondary transfer roll 16 in the direction of arrow b (see FIG. 4) when the secondary transfer roll 16 is brought into contact with the intermediate transfer belt 1. The vertical axis of FIG. 8 is the walk amount W of the intermediate transfer belt 1 corresponding to the position of the secondary transfer roll, and the vertical axis of FIG. 9 is the intermediate transfer belt 16 when the secondary transfer roll 16 contacts the intermediate transfer belt 1. When the belt 1 meanders, and the intermediate transfer belt 1 is displaced E by the meandering, the inclination angle of the steering roll 3 when the intermediate transfer belt 1 is displaced E becomes 0 (hereinafter referred to as steering roll angle and steering roll angle). Δ).

As shown in FIG. 8, there is a linear correspondence represented by a straight line L1 between the secondary transfer roll position and the walk amount W. By setting the position of the secondary transfer roll to D from the straight line L1, the secondary transfer is performed while the walk amount W of the intermediate transfer belt 1 is kept at 0 (without causing the position shift of the intermediate transfer belt 1). It can be seen that the roll 16 can be brought into contact with the intermediate transfer belt 1. As shown in FIG. 9, there is also a linear correspondence represented by a straight line L2 between the secondary transfer roll position and the steering roll angle δ.

Accordingly, from FIGS. 8 and 9, when the secondary transfer roll 16 is set in a state of being separated from the intermediate transfer belt 1 (non-contact state), the steering roll angle δ in that state is ε (see FIG. 9). Then, while the secondary transfer roll 16 is in contact with the intermediate transfer belt 1, the secondary transfer roll position is maintained at the secondary transfer roll position C (see FIG. 9) corresponding to the steering roll angle ε,
Regardless of whether the secondary transfer roll 16 is in contact with the intermediate transfer belt 1 or not, the steering roll angle δ is always ε.
(See FIG. 9). This means that the secondary transfer roll 16
Means that the steering roll angle δ does not need to be changed even if the The fact that there is no need to change the steering roll angle δ means that the secondary transfer roll 16 does not meander even when it comes into contact with the intermediate transfer belt 1, and the walk amount W is zero. Accordingly, it is possible to suppress the shift of the transfer position of the toner image transferred to the intermediate transfer belt 1 and to prevent the deterioration of the image formed on the paper 13.

In the present embodiment, how the secondary transfer roll position C shown in FIG. 9 is obtained will be described with reference to FIG. 10 and, if necessary, FIGS. 1 to 9 together with FIG.

FIG. 10 is a view showing a flowchart for obtaining the secondary transfer roll position C.

The image forming apparatus of this embodiment has a correspondence calculation mode and a secondary transfer roll position calculation mode which are executed prior to the image forming mode, in addition to the image forming mode. The correspondence relationship calculation mode is a mode for calculating a slope K of a straight line L2 representing a correspondence relationship between a secondary transfer roll position and a steering roll angle δ shown in FIG. 9, and this mode is a correspondence calculation shown in FIG. Means 26
Is executed by The secondary transfer roll position calculation mode corresponds to the current steering roll angle in a state where the secondary transfer roll 16 is separated from the intermediate transfer belt 1 from the inclination K calculated by executing the correspondence relationship calculation mode. This is a mode for calculating the secondary transfer roll position of the intermediate transfer belt 1, and this mode is executed by the attitude calculation means 27 shown in FIG.

When the execution of this correspondence calculation mode is started, the motor 25c (see FIG. 4) is driven, and the one end 16a of the secondary transfer roll 16 moves to the secondary transfer roll position B which is shifted to the right as much as possible. And fixed at position B. Thereby, the secondary transfer roll 16 is moved to the secondary transfer roll position B.
At the intermediate transfer belt 1. The intermediate transfer belt 1 meanders due to the contact of the secondary transfer roll 16 with the intermediate transfer belt 1, and the meandering causes a displacement of the intermediate transfer belt 1. However, the steering roll 3 is controlled by the steering roll control unit 20. Is adjusted to the steering roll angle β when the displacement E of the intermediate transfer belt 1 becomes zero. As a result, as shown in FIG.
And the point P representing the correspondence between the steering roll angle β
1 is required. Next, one end 16 of the secondary transfer roll 16
a moves to the secondary transfer roll position A which is shifted to the left as much as possible and is fixed at the position A. Thereby, the secondary transfer roll 16 contacts the intermediate transfer belt 1 at the secondary transfer roll position A. At this time, under the control of the steering roll control unit 20, the steering roll angle δ of the steering roll 3 is adjusted to the steering roll angle α at which the displacement E of the intermediate transfer belt 1 becomes zero. As a result, a point P2 representing the correspondence between the secondary transfer roll position A and the steering roll angle α is obtained. Thereafter, the slope K of the straight line L2 connecting the points P1 and P2 is calculated by the following equation (1).

K = (β-α) / (BA) (1) When the slope K is calculated, the slope K is stored in the correspondence calculating means 26, and the correspondence calculation mode is ended ( Step S1). When the inclination K is obtained in this way, the secondary transfer roll position calculation mode is executed.

When the execution of the secondary transfer roll position calculation mode is started, the secondary transfer roll 16 separates from the intermediate transfer belt 1. Immediately after the separation, the intermediate transfer belt 1 meanders, and the meandering causes a displacement of the intermediate transfer belt 1. The steering roll control unit 20 controls the steering roll angle δ of the steering roll 3.
Is adjusted to the steering roll angle ε at which the displacement E of the intermediate transfer belt 1 becomes zero. At this time, the steering roll angle ε (see FIG. 9) is recorded (step S2). From the steering roll angle ε and the straight line L2, a secondary transfer roll position C corresponding to the steering roll angle ε is obtained. When the secondary transfer roll position C is determined, the amount of movement X required for the secondary transfer roll 16 to move from the secondary transfer roll position A to the secondary transfer roll position C is calculated from the following equation (2). Ask.

Movement amount X = (BA) / (β−α) · (ε−α) (2) After calculating the movement amount X (step S3), the secondary transfer roll position calculation mode ends. I do.

The movement amount X is similarly obtained for the cleaning blade 9a of the cleaning device 9.

When the movement amount X of the secondary transfer roll 16 and the cleaning blade 9a is obtained, the execution of the image forming mode is started while the secondary transfer roll 16 and the cleaning device 9 are not in contact with the intermediate transfer belt 1. In the first rotation of the intermediate transfer belt 1, first, yellow,
The magenta toner image is transferred to the intermediate transfer belt 1. Immediately after the yellow and magenta toner images pass through the secondary transfer position T2 and the cleaning position C, the secondary transfer roll 16 and the cleaning device 9 are removed.
At a position corresponding to the calculated movement amount X, the intermediate transfer belt 1
Contact. In this way, by bringing the secondary transfer roll 16 and the cleaning device 9 into contact with the intermediate transfer belt 1, meandering of the intermediate transfer belt 1 is suppressed. Thereafter, in the second rotation of the intermediate transfer belt 1, cyan and black toner images are transferred to the intermediate transfer belt 1. When the toner images of four colors are transferred to the intermediate transfer belt 1 in this manner, the toner images of four colors are conveyed to the secondary transfer position T2 by the rotation of the intermediate transfer belt 1, and the intermediate transfer is performed. The sheet is collectively transferred to the sheet 13 by the secondary transfer roll 16 which is in contact with the belt 1. Paper 1 onto which toner image has been transferred
3 is conveyed to the position where the fixing device 18 is disposed by the paper conveying system 17, and the fixing device 18 fixes the toner image.

In this way, the amount of movement of the secondary transfer roll 16 and the cleaning blade 9a is obtained, and the secondary transfer roll 16 and the cleaning blade 9 are brought into contact with the intermediate transfer belt 1 based on the amount of movement.
The meandering of the intermediate transfer belt 1 is suppressed. Therefore, the shift of the transfer position of the toner image transferred to the intermediate transfer belt 1 is suppressed, and the deterioration of the image formed on the paper 13 is prevented.

In this embodiment, the secondary transfer roll 16
By adjusting the posture of the cleaning blade 9a, the displacement of the intermediate transfer belt 1 when the secondary transfer roll 16 and the cleaning blade 9a are brought into contact with the intermediate transfer belt 1 is suppressed. Similarly, the contact pressure difference in the lateral direction of the intermediate transfer belt 1 is
There is a linear relationship with the walk amount W and the steering roll angle δ. Therefore, instead of adjusting the posture, the secondary transfer roll 16 and the cleaning blade 9 are used.
By adjusting the contact pressure difference in the lateral direction of the intermediate transfer belt 1 at the time of contact with the intermediate transfer belt 1
The displacement of the intermediate transfer belt 1 may be suppressed. Hereinafter, a contact pressure adjusting mechanism for adjusting the contact pressure difference of the secondary transfer roll 16 will be described.

FIG. 11 is an explanatory view of the mechanism.

The contact pressure adjusting mechanism 30 has a ball screw 30a.
Is provided. The ball screw 30a is
The rotation in the direction of the arrow a is performed by the drive of 0b. Further, the contact pressure adjusting mechanism 30 includes a T-shaped screwing cylinder 30c into which the ball screw 30a is screwed. Further, one end 16a of the secondary transfer roll 16 is connected to the screwing cylinder 30c and the attachment body 30 attached to the one end 16a of the secondary transfer roll 16.
The backup roller 4 is biased in the direction in which the backup roll 4 is disposed by the spring 30e sandwiched between the backup roll 4d and the spring 30e.

The contact pressure adjusting mechanism 30 constructed as described above
When the ball screw 30a is rotated by the drive of the motor 30b, the screwing cylinder 3 screwed to the ball screw 30a
0c moves in the direction of arrow b. The movement of the screw cylinder 30c changes the nip pressure difference between the intermediate transfer belt 1 and the one end 16a of the secondary transfer roll 16.

As described above, the positional deviation of the intermediate transfer belt 1 may be suppressed by adjusting the nip pressure difference.

[0069]

As described above, according to the present invention,
As a result, it is possible to obtain a belt conveyance device in which belt fluctuation is suppressed and an image forming apparatus to which the belt conveyance device is applied.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an embodiment of an image forming apparatus of the present invention to which an embodiment of a belt conveying device of the present invention is applied.

FIG. 2 is a schematic configuration diagram showing a contact type sensor which is an example of the edge sensor 10.

FIG. 3 is a schematic configuration diagram showing a non-contact type sensor which is another example of the edge sensor 10.

FIG. 4 is a schematic diagram illustrating a secondary transfer roll driving unit that drives a secondary transfer roll 16 included in a driving unit.

FIG. 5 is a schematic configuration diagram of the image forming apparatus, specifically showing a path of a signal detected by an edge sensor.

FIG. 6 is an explanatory diagram of how the meandering of the intermediate transfer belt is corrected.

FIG. 7 simply shows the secondary transfer roll 16 as the intermediate transfer belt 1
FIG. 3 is a diagram showing a lateral displacement of the intermediate transfer belt 1 when the intermediate transfer belt 1 is brought into contact with the intermediate transfer belt 1.

FIG. 8 is a graph showing a relationship between an angle δT of a secondary transfer roll and a walk amount W.

FIG. 9 is a graph showing a relationship between a secondary transfer roll angle δT and a steering roll angle δS.

FIG. 10 is a view showing a flowchart for obtaining a secondary transfer roll position C;

FIG. 11 is an explanatory diagram of a contact pressure adjusting mechanism for adjusting a contact pressure difference.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Intermediate transfer belt 1a Edge 2 Drive roll 3 Steering roll 3a, 10e, 22b The other end 3b, 10d, 16a, 22a One end 4 Backup roll 5, 6 Idler roll 7, 8 Toner image forming unit 7a, 8a Photoconductor drum 7b, 8b Raster scanner 7d, 8d Charger 7e, 7f, 8e, 8f Developing device 7g, 8g Primary transfer roll 7c, 8c Cleaner 10 Edge sensor 10a Spring 10b Contact 10c Support shaft 10f Displacement sensor 10g LED 10h Light intensity sensor 11 Belt home Sensor 13 Paper 14 Pickup roll 15 Roll pair 16 Secondary transfer roll 17 Paper transport system 18 Fixing unit 20 Steering control unit 21 Steering motor 22 Steering arm 23 Eccentric cam 24 Support shaft 25 Drive means 25a Secondary transfer roll drive unit 25b, 30a Ball screw 25c, 30b Motor 25d, 30c Screwing cylinder 26 Correspondence calculating means 27 Attitude calculating means 30 Contact pressure adjusting mechanism 30e Spring

Continued on front page F term (reference) 2H027 DA21 DE02 DE07 DE10 EB04 EC06 EC19 ED24 EE04 EE06 EF01 EF12 ZA07 2H032 AA05 AA15 BA09 BA23 3F049 BB11 LA04 LB03 3J049 AA01 BE06 BE09 BG04 BH20 CA10

Claims (5)

[Claims] A belt that moves along a predetermined path; a position shift detecting unit that detects a position shift of the belt in a width direction from a predetermined reference moving path; the belt that is detected by the position shift detecting unit A steering control means for correcting a displacement in the width direction of the belt by changing a steering control position in accordance with the displacement in the width direction of the belt; A contact member capable of freely adjusting an operation level to a positional shift in a direction; a contact member driving unit configured to freely adjust the operation level of the contact member, and contact the contact member with the belt so as to be freely separated; A correspondence relationship for calculating a correspondence relationship between an operation level of the contact member at the time of contact with the belt and a steering control position of the steering control means. An operation for calculating an operation level of the contact member corresponding to a current steering control position in a state where the contact member is separated from the belt with reference to the correspondence calculated by the calculation unit and the correspondence calculation unit. A belt transport device comprising a level calculation unit, wherein the contact member driving unit adjusts the contact member to the operation level calculated by the operation level calculation unit and makes the contact member come into contact with the belt. 2. The contact member driving means adjusts a posture of the contact member or a contact pressure difference in a belt width direction when the contact member contacts the belt.
2. The belt conveyance device according to claim 1, wherein the operation level is adjusted. 3. The belt conveying device according to claim 1, wherein the contact member is a roll or a blade. 4. An image forming apparatus for forming or conveying a toner image by forming a toner image and finally transferring and fixing the toner image on a predetermined sheet to form an image on the sheet. A belt that moves along a predetermined path, a position shift detecting unit that detects a position shift of the belt in a width direction from a predetermined reference moving path, the belt that is detected by the position shift detecting unit A steering control means for correcting a displacement in the width direction of the belt by changing a steering control position in accordance with the displacement in the width direction of the belt; A contact member capable of freely adjusting the action level for the positional deviation in the direction; and adjusting the action level of the contact member freely, and connecting the contact member to the base. A contact member driving unit that makes contact with and detachable from the belt, a correspondence calculating unit that calculates a correspondence between an operation level of the contact member at the time of contact with the belt, and a steering control position of the steering control unit, and An action level calculating means for calculating an action level of the contact member corresponding to a current steering control position in a state where the contact member is separated from the belt with reference to the correspondence calculated by the correspondence calculation means. An image forming apparatus, wherein the contact member driving unit adjusts the contact member to the operation level calculated by the operation level calculation unit and makes the contact member come into contact with the belt. 5. A correspondence calculation mode for calculating a correspondence by the correspondence calculation means, and an image formation mode for forming an image on a sheet, wherein the correspondence calculation mode and the image formation mode are set. The image forming apparatus according to claim 4, wherein the image forming apparatuses are separately executed.