JP2001194922A - Image forming device and belt driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device and a belt driving device capable of forming a good image by controlling the widthwise position of a belt member so that the belt member may be shifted in a prescribed direction and preventing the positional deviation in the width direction. SOLUTION: As for an obliquely arranged tension roller 15, a force for pulling the intermediate transfer belt 11 toward the end part side of the roller which comes into contact with the upstream side of the transfer belt 11 in the rotating direction is applied to the belt 11 by the roller 15. Thus, the belt 11 is energized in a prescribed direction, then, a deviation checking member 11a arranged on the belt 11 comes into contact with the end part opposite to the aforesaid end part of the tension roller 15, then, the position in the width direction is controlled. By bringing the deviation checking member 11a into contact with the end part of the tension roller 15 in advance, the widthwise position of the intermediate transfer belt 11 is not shifted even in the case where the belt 11 is rotated.

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 copying machine, a facsimile, a printer, and the like. More specifically, the present invention relates to a belt member, a plurality of roller members for stretching the belt member, and a plurality of roller members. The present invention relates to an image forming apparatus having a driving means for rotating at least one of the roller members, and having a detent member on one of the belt member and the plurality of roller members.

[0002]

2. Description of the Related Art In a conventional image forming apparatus, an image forming apparatus using an intermediate transfer device that superimposes toner of multiple colors on an intermediate transfer belt and then collectively transfers the toner onto a transfer material is used. The overlay accuracy of each color is important. In the alignment of each color, it is necessary to perform alignment in both the belt width direction and the belt rotational movement direction. If the positioning accuracy is poor, each color is displaced at the time of color superimposition, so that an abnormal image such as poor color reproducibility and double-line appearance occurs. Regarding the above-described alignment, the higher the accuracy, the better the color reproducibility, and this is a problem in the image forming apparatus as an element for improving the image quality. In recent years, with the demand for improved image quality in the market, the density of pixels has further been increased, and a more severe accuracy is required for the above-described alignment.

In the intermediate transfer belt, as shown in FIG. 6, detent members 11a are provided at both ends of the intermediate transfer belt 11.
11b is provided. These detent members 11a, 1
1b collides with one of the roller ends in the belt width direction, thereby preventing the intermediate transfer belt 11 from being cut off.

The position of the roller on which the intermediate transfer belt is stretched is important in terms of the positional relationship with respect to the photosensitive member and the paper transfer portion, and high precision is required. In addition, if the positional relationship and the parallelism of the rollers are largely shifted, a large belt deviating force is generated,
Since a load is applied to the detent member at the end of the belt, the dimensions and configuration of each component are set to minimize the deviation in parallelism.

In a conventional intermediate transfer device, for example,
In the example of the intermediate transfer device shown in FIG.
The dimensions (a to h) from the axis of No. 4 are set to be the same on the front side (front side in the figure) and the rear side (rear side in the figure), and the parallelism of each roller is maintained. By making the positional accuracy of each roller higher, a state in which the belt does not lean on either side, that is, a state in which the stopper does not contact the roller is obtained. By reducing the deviation of the belt in this way, the above-described positioning accuracy can be improved.

[0006]

However, when the main body of the image forming apparatus is moved in a place where there is unevenness on the floor surface, the frame is twisted by the weight of the apparatus itself, and the entire apparatus is distorted. The positional relationship may be shifted. If the position of each roller is misaligned,
Deviation of the intermediate transfer belt occurs. Therefore, immediately after the apparatus main body is moved, the belt moves until the stop comes into contact with the roller, and there is a possibility that the positional shift of each color occurs in the above-described alignment. In particular, when the intermediate transfer belt is hardly shifted and the belt is not in contact with the shift stopper, the device is apt to be easily shifted with respect to the distortion of the apparatus, and there is a possibility that the above-described positional shift occurs. In addition, when the circumferential length of the belt slightly changes due to elongation of the belt or the like, deviation tends to occur due to deviation of the circumferential length of the belt, and there is a possibility that a positional shift may occur each time.

[0007] The problem of the displacement caused by the deviation of the belt is not limited to the intermediate transfer belt, but can also occur when a photosensitive belt or the like is used as a belt member. Further, the problem caused by the deviation of the belt is not limited to the image forming apparatus, but may occur in a belt driving device that drives the belt by stretching the belt over a plurality of roller members.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to restrict the position of the belt member in the width direction by moving the belt member in a predetermined direction. An object of the present invention is to provide an image forming apparatus and a belt driving device that can form a good image while preventing positional deviation in a direction.

[0009]

According to one aspect of the present invention, a belt member, a plurality of roller members for stretching the belt member, and at least one of the plurality of roller members are provided. And a driving means for rotating and driving one of the plurality of roller members, wherein at least one of the plurality of roller members is provided with a detent member on one of the belt member and the plurality of roller members.
The belt member is disposed so as to be obliquely shifted with respect to a direction orthogonal to the rotational movement direction of the belt member, so that the belt member is shifted toward a predetermined direction.

In the image forming apparatus according to the first aspect, when the belt member rotates, the obliquely disposed roller member abuts on the upstream side in the rotational direction of the belt member among both end portions of the roller member. A force is applied to the belt member so as to approach the contacting end side. With this, the belt member is shifted toward the end of the roller member that is in contact with the upstream side in the rotational movement direction of the belt member, and the stopper member is the other of the roller members. By hitting the end, the position in the width direction is regulated.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the belt member is stretched in advance in the predetermined direction and the stopper member is abutted. Things.

In the image forming apparatus according to the present invention, the belt member is stretched in advance in the predetermined direction, and the stopper member is abutted against the belt member. Regulated. Thus, even if the belt member rotates, no displacement occurs due to the shift of the belt.

According to a third aspect of the present invention, in the image forming apparatus of the first or second aspect, the belt member is an intermediate transfer belt that carries the toner images of the respective color components formed on the image carrier in an overlapping manner. It is characterized by the following.

In the image forming apparatus according to the third aspect, since the position in the width direction when the intermediate transfer belt rotates is restricted, the toner images of the respective color components formed on the image carrier are removed. When superimposed on the intermediate transfer belt, there is no displacement in the width direction.

The invention according to claim 4 is the invention according to claim 1, 2, or 3.
The image forming apparatus according to any one of claims 1 to 3, wherein an angle at which the roller member is obliquely shifted with respect to a direction orthogonal to a rotational movement direction of the belt member is set to 0.01 degree or more and 1 degree or less.

According to experiments, if the angle is smaller than 0.01 degrees, a sufficient force of the roller member to move the belt member to one side cannot be obtained. On the other hand, if the angle is larger than 1 degree, the force of the roller member to move the belt member to one side is too large, and there is a possibility that the stopper member may be scraped or damaged. In the image forming apparatus according to the fourth aspect, since the angle is not less than 0.01 degrees and not more than 1 degree, the above problem does not occur, and the position of the belt member in the width direction can be regulated.

According to a fifth aspect of the invention, there is provided a belt member, a plurality of roller members for stretching the belt member, and driving means for rotating at least one of the plurality of roller members. In a belt driving device provided with a detent member on one of the belt member and the plurality of roller members, at least one of the plurality of roller members is moved in a direction orthogonal to a rotational movement direction of the belt member. An image forming apparatus, wherein the belt member is arranged obliquely shifted with respect to the belt member and the belt member is shifted in a predetermined direction.

In the belt driving device according to the fifth aspect, as described in the first aspect, the belt member is in contact with the end of the roller member on the upstream side in the rotational movement direction of the belt member. When approaching the end, the above-mentioned non-stop member abuts against the other end of the roller member, and the position in the width direction is regulated.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter referred to as a copying machine) as an image forming apparatus will be described. First, the configuration and operation of the entire copying machine according to the present embodiment will be described. FIG.
FIG. 1 is a schematic configuration diagram of a copying machine according to an embodiment. The copying machine includes a color image reading device (hereinafter, referred to as a scanner unit) and a color image recording device (hereinafter, referred to as a printer unit).

First, the configuration and operation of a scanner unit (not shown) in the above copying machine will be described. In this scanner unit, an image of a document placed on a contact glass is formed on a color sensor via an illumination / mirror optical system such as an illumination lamp, a mirror group and a lens, and color image information of the document is obtained. For example, it is read out for each color separation light of Blue (hereinafter, referred to as B), Green (the same, G), and Red (the same, R), and is converted into an electric image signal. The color sensor includes B, G, and R color separation means and a photoelectric conversion element such as a CCD, and can simultaneously read three colors. B, G, R obtained by this scanner unit
Each image signal is subjected to color conversion processing by the image processing unit based on the intensity level. By this color conversion processing,
Black (hereinafter, described as Bk), Cyan (the same,
C), Magenta (same, M), Yellow (same,
Y) color image data is obtained. Specifically, the illumination / mirror optical system scans a document upon receiving a start signal interlocked with the printer unit, and obtains color image data. In the present embodiment, since the image data of one color is obtained for each original scan in the illumination / mirror optical system, the color image data of four colors Bk, C, M and Y is obtained. In order to obtain it, the above document scanning is repeated four times in total.

Next, the configuration and operation of the printer unit of the copying machine according to the present embodiment will be described with reference to FIG.
The printer unit according to the present embodiment includes a writing optical unit (not shown) as exposure means and a photosensitive drum 1 as an image carrier. The writing optical unit converts the color image data from the above-described scanner unit into an optical signal, and forms a negative latent image corresponding to the original image on the photosensitive drum 1 uniformly charged to the negative polarity. As the writing optical unit, for example, a semiconductor laser, a light emission drive control unit (not shown) for controlling light emission and drive of the semiconductor laser, a polygon mirror, a rotation drive motor for rotating this, a f / θ lens, A mirror constituted by a reflection mirror can be used. The photosensitive drum 1 is rotationally driven in the direction of arrow A in FIG. 1, that is, counterclockwise.

Around the photosensitive drum 1, a writing optical unit as an exposing means (not shown), a photosensitive body cleaning device 2 as a cleaning means, a charging charger 3 as a charging means, and a rotating means as a developing means are provided. A revolver developing unit 4 as a mold developing device and an intermediate transfer unit 10 as an intermediate transfer device are provided. The photoconductor cleaning device 2 has a fur brush 2a and a photoconductor cleaning blade 2b, and cleans the surface of the photoconductor drum 1 after the primary transfer.

The revolver developing unit 4 has a Bk developing unit 4a, a C developing unit 4b, an M developing unit 4c, and a Y developing unit 4d, and the revolver developing unit rotates to develop each color. The developing position of the photoconductor drum 1 facing the photoconductor drum 1 can be determined. The developer contained in these four developing devices (4a, 4b, 4c, 4d) uses a two-component developer, and the toner in the developer is negatively charged.

The intermediate transfer unit 10 includes an intermediate transfer belt 11 serving as an intermediate transfer member, a primary transfer bias roller 12 serving as a charge applying means, a primary transfer power supply 17 connected to the primary transfer bias roller 12, and a primary transfer power supply 17 serving as a power supply. It has a configuration in which it is stretched around an earth roller 13 as a pre-transfer charge removing unit, a driving roller 14 as a belt driving unit, a tension roller 15, and a secondary transfer facing roller 16. The drive roller 14 is connected to a drive motor (not shown), and the drive of the drive motor is controlled by a control unit (not shown). All the rollers that stretch the intermediate transfer belt 11 are formed of a conductive material, and each roller other than the primary transfer bias roller 12 is grounded.

Further, a primary transfer bias roller 12 which stretches the intermediate transfer belt 11 is used for a primary transfer area formed by a nip formed by contact between the intermediate transfer belt and the photosensitive drum 1. The intermediate transfer belt is disposed on the downstream side in the surface movement direction, that is, the belt rotation direction. A primary transfer bias is applied to the primary transfer bias roller 12 by the primary transfer power supply 17. Further, a grounded earth roller 13 is arranged on the upstream side in the belt rotation direction with respect to the primary transfer area. These primary transfer bias roller 12 and ground roller 13
Thus, the intermediate transfer belt 11 is pressed against the photosensitive drum 1 to form the nip. At the time of primary transfer, a gap may be formed between the vicinity of both ends in the width direction of the intermediate transfer belt 11 and the photosensitive drum 1. For this reason, a backup member 18 is provided on the back surface of the intermediate transfer belt 11 in which the nip portion is formed, in contact with the vicinity of both ends in the width direction to fill the gap.

Around the intermediate transfer belt 11, a lubricant application device 20 as a lubricant application device, a belt cleaning device 30 as a cleaning device, and a transfer unit 40 as a transfer device are provided. These can be respectively brought into contact with and separated from the intermediate transfer belt 11 by a contact / separation mechanism (not shown).

The lubricant applying device 20 includes a lubricant applying brush roller 21 as a lubricant applying member, and a lubricant accommodating case 22. The lubricant containing case 22 contains a solid lubricant and a spring. As the solid lubricant, for example, zinc stearate composed of plate-shaped fine particles can be used. The solid lubricant is urged toward the lubricant applying brush roller 21 by the spring,
The brush is in contact with the lubricant application brush roller. The lubricant applying brush roller 21 can be driven to rotate by a driving unit (not shown). When the lubricant is applied to the intermediate transfer belt 11 after the secondary transfer, the lubricant applying brush roller 21 rotates to scrape off the solid lubricant. The lubricant thus scraped off is in the form of a powder, and the intermediate transfer belt 1
1 is applied.

The belt cleaning device 30 includes a belt cleaning blade 31 as a cleaning member.
, An inlet seal member 32 as a sealing means, and a casing 33. The toner peeled off by the belt cleaning blade 31 is stored in the casing 33. At this time, the entrance seal 32 receives the toner and guides the peeled toner into the casing so that the peeled toner does not fly into the apparatus.

The transfer unit 40 comprises a secondary transfer bias roller 41 facing the secondary transfer opposing roller 16 of the intermediate transfer unit 10, and a secondary transfer power source 42 connected to the secondary transfer bias roller 41. .

Further, the printer section further transfers the image to a secondary transfer area formed between the secondary transfer bias roller 41 of the transfer unit 40 and the secondary transfer opposing roller 16 of the intermediate transfer unit 10. Transfer paper 100 as material
, A not-shown registration roller, a transfer paper cassette for storing transfer paper 100 of various sizes, a manual feed tray (not shown) for using OHP paper, thick paper, and the like, and a paper not shown. It has a transport unit, a fixing device 50 as fixing means, and a copy tray (not shown). The fixing device 50 melts the unfixed toner image on the transfer paper 100 between a fixing roller pair including a fixing roller 51 and a pressure roller 52 controlled at a predetermined temperature, and fixes the unfixed toner image. I do.

Next, the operation of the copying machine when the order of development is Bk, C, M, and Y will be described. The order of image formation is not limited to this. When the copying operation is started, first, the Bk process starts, the color image information of the document is read by the above-described scanner unit, and the writing by the above-described printer unit is performed based on the Bk image data obtained from the image information. Bk on the photosensitive drum 1 by the laser light of the optical unit
A latent image is formed. This Bk latent image is stored in the Bk developing device 4
The Bk toner is attached by a, and is developed by forming a Bk toner image. At this time, in order to reliably develop the Bk latent image, the developing sleeve of the Bk developing device 4a is
Before the leading end of the Bk latent image reaches the developing position of the Bk developing device, it is rotated in advance. Thus, when the leading end portion of the Bk latent image reaches the developing position, the developer is in a spike state, so that the entire Bk latent image can be reliably developed. Further, in the Bk developing device 4a, when the rear end portion of the Bk latent image has passed the developing position, the developer formed on the developing sleeve is promptly cut off. As a result, the Bk developing device 4a becomes inoperative. At this time, at least C to be developed next
Before the leading end portion of the latent image reaches the developing position of the Bk developing device 4a, it is made completely inoperative. The cutting of the developer can be performed by switching the developing sleeve of the Bk developing device 4a in the direction opposite to the rotating direction during the developing operation. The Bk toner image thus formed on the photosensitive drum 1 by the Bk developing device 4a is primarily transferred onto the surface of the intermediate transfer belt 11 driven at the same speed as the photosensitive drum, thereby completing the Bk process. .

In parallel with the primary transfer of the Bk toner image,
The following C step is started on the photosensitive drum 1 side. That is, the color image information of the document is read again at a predetermined timing, and based on the C image data obtained from the image information, a C latent image is formed on the photosensitive drum 1 by laser light, and the C developing device 4b A C toner image is formed.
The rotation of the developing sleeve in the C developing device 4c
The process is started after the trailing end portion of the Bk latent image has passed to the developing position of the developing device and before the leading end portion of the C latent image has reached.
When the rear end of the C latent image has passed, the developer formed on the developing sleeve is cut off in the same manner as in the case of the Bk developing device 4a, and the C developing device 4b is not operated. State. At this time, the inactive state is completely set before the leading end of the next M latent image arrives. The C toner image thus developed and formed on the photosensitive drum 1 is primary-transferred by aligning the Bk toner image on the intermediate transfer belt 11 with the transferred image surface.

Thereafter, in the M step and the Y step, as in the above-mentioned C step, latent image formation, development, and primary transfer are performed based on the respective image data. In this manner, Bk, C, M, and Y sequentially formed on the photosensitive drum 1 on the same image surface on the intermediate transfer belt 11.
Is primarily transferred, a toner image in which these four colors overlap is formed on the intermediate transfer belt.

Further, until the toner image is formed on the intermediate transfer belt 11, specifically, the primary transfer of the Y toner image of the fourth color is performed after the primary transfer of the Bk toner image of the first color. Until the end, the lubricant application device 20 and
The belt cleaning device 30 is separated from the intermediate transfer belt 11 by a contact / separation mechanism (not shown).

The toner image primary-transferred onto the intermediate transfer belt 11 as described above is sent to the secondary transfer area for secondary transfer onto the transfer paper 100. At this time, the secondary transfer bias roller 41 of the transfer unit 40 is
Usually, at the timing when the toner image is transferred to the transfer paper 100, the toner image is pressed against the intermediate transfer belt 11 by the contact / separation mechanism. Thereafter, a predetermined secondary transfer bias is applied to the secondary transfer bias roller 41 by the secondary transfer power supply 42 to form a secondary transfer electric field in the secondary transfer area. Thus, the toner image on the intermediate transfer belt 11 is transferred onto the transfer paper 100. When the transfer paper 100 is fed, the transfer paper is transferred to the secondary transfer area at the timing when the leading end of the toner image on the intermediate transfer belt 11 reaches the secondary transfer area by the registration roller. Paper.

As described above, the intermediate transfer belt 1
The transfer paper 100 on which the toner images formed by overlapping the four colors on the transfer paper 100 are collectively transferred is then conveyed to a fixing device 50 by a paper conveyance unit, where the unfixed toner image on the transfer paper 100 is fixed. . Then, the transfer paper 100 is carried out to a copy tray and stacked.

The surface of the photosensitive drum 1 after the primary transfer is cleaned by the photosensitive member cleaning unit 2 and is uniformly discharged by a discharging lamp (not shown) as a discharging unit. The surface of the intermediate transfer belt 11 after the secondary transfer is cleaned by the belt cleaning device 30 being pressed against the intermediate transfer belt by the contact / separation mechanism.

Next, the features of this embodiment will be described. FIG. 2 is a perspective view of the vicinity of the intermediate transfer unit 10. As described above, the intermediate transfer belt 11 includes the primary transfer bias roller 12, the ground roller 13, and the drive roller 1.
4. It is stretched by a tension roller 15 and a secondary transfer opposing roller 16.

The intermediate transfer unit 10 according to the present embodiment
In the above configuration, at least one of the rollers is disposed obliquely shifted with respect to a direction orthogonal to the rotational movement direction of the intermediate transfer belt 11.
Thus, the intermediate transfer belt 11 is moved in a predetermined width direction.

In the illustrated example, the tension roller 1
5, the dimension g on the near side (front side of the copying machine) in the figure from the axis of the belt drive roller 14 is set to the back side (rear side of the copying machine) in the figure.
(G <g ′). With this configuration, the axis of the tension roller 15 is obliquely shifted with respect to a direction orthogonal to the rotational movement direction B of the intermediate transfer belt 11.

Next, the mechanism for shifting the belt will be described in detail. FIG. 3 is a view as viewed from the direction of arrow C in FIG. In the figure, the left side is the front side of the copying machine main body, and the right side is the rear side of the copying machine main body. As described above, the axis 15c of the tension roller 15 is obliquely shifted with respect to the direction orthogonal to the rotational movement direction B of the intermediate transfer belt 11. This obliquely shifted angle is defined as θ.

Tension roller 15 and intermediate transfer belt 1
In the part where a and are in contact, as shown, the force F ₂ in the direction perpendicular to the axis 15c of the tension roller 15 is applied. The direction of this force F _2, to the rotational movement direction B of the intermediate transfer belt 11 is a direction deviated by the angle theta. In other words, the direction is toward the rear side of the copying machine main body with respect to the rotation direction B of the intermediate transfer belt 11. This force F ₂
An intermediate transfer belt 11 in the direction of the intermediate transfer belt 11 the resultant force F ₃ which rotates the direction of movement of the force F ₁ is the synthesis of the rotational movement. Direction of the resultant force F ₃ is the rotational direction B of the intermediate transfer belt 11 is a direction facing the rear side of the copying machine main body. Therefore, the intermediate transfer belt 11 moves toward the rear side (the right side in the drawing) of the copying machine main body. When the intermediate transfer belt 11 moves toward the rear side of the copying machine main body, as shown in FIG.
5 and an end of another roller (not shown), the position of the intermediate transfer belt 11 in the width direction is regulated. Thereby, the accuracy of superimposing each color in the width direction on the intermediate transfer belt 11 is improved. In the illustrated example, the mechanism for moving the belt closer to the belt has been described with a configuration in which the belt is stretched over five rollers, but the same applies to a case in which the belt is stretched over two or more rollers.

The position of the intermediate transfer belt 11 in the width direction is restricted by abutting the stopper 11a of the intermediate transfer belt 11 against the end of each roller in advance, and the position of the intermediate transfer belt 11 in the width direction is shifted during the rotation. There is no.

Here, if the deviation of the intermediate transfer belt 11 is too strong, there is a possibility that the deviation preventing member 11a may be scraped or broken. Therefore, the present inventor has proposed the non-stop member 1.
In order to obtain an appropriate range of the angle θ at which the damage of 1a does not occur, an intensive experiment was conducted. FIG. 5 shows the results of this experiment. A fluorine resin was used as the material of the intermediate transfer belt, and a urethane resin was used as the material of the stopper member. The shift amount in the drawing is the shift amount [mm] in the belt width direction with respect to the belt advance amount of 500 mm. The roller wrap amount is an amount [mm] of contact between the outer periphery of the roller disposed obliquely in the belt traveling direction and the inner surface of the belt. The angle is the angle [degree] between the axis of the roller and the axis of the drive roller which are arranged obliquely in this experiment.

From the above experiment, it was found that shaving occurs when the deviation amount is 1.2 mm or more. Therefore, the appropriate range of the angle is 0.01 degree or more and 1 degree or less, and more preferably 0.1 degree or less.
It is not less than 01 degrees and not more than 0.8 degrees.

In the copying machine according to this embodiment, the position of the intermediate transfer belt in the width direction is regulated by abutting the stopper of the intermediate transfer belt against the end of the roller in advance.
The position in the width direction does not shift during the rotational movement. This prevents the intermediate transfer belt from shifting due to the movement of the copying machine main body in a place having irregularities and the elongation of the peripheral length of the intermediate transfer belt due to a temperature change. The accuracy of superimposing each color in the width direction can be improved. Further, since the intermediate transfer belt is always moved in a predetermined direction, as shown in FIG.
The structure can be such that the non-stop member is provided only on one side, and cost reduction can be achieved. In addition, when assembling the intermediate transfer belt with the roller stretched over the roller, there is also an advantage that the assembly is facilitated by inserting the intermediate transfer belt into the roller from the side without the stopper member.

Although the above-described intermediate transfer belt has been described as a belt member, the present invention is not limited to this.
For example, the present invention can be applied to a photoreceptor belt as a belt member. Further, although the configuration in which the non-stop is provided on the belt member has been described, the same effect can be obtained by providing the configuration on the roller member side. Furthermore, in the present embodiment, an example in which the present invention is applied to an image forming apparatus has been described. However, the present invention is not limited to this, and the present invention is also applicable to a belt driving apparatus that drives a belt by stretching a belt over a plurality of roller members. it can.

[0048]

According to the first to fourth aspects of the present invention, the belt member is moved in a predetermined direction to regulate the position of the belt member in the width direction, thereby preventing the belt member from being displaced in the width direction. There is an excellent effect that an image can be formed. Further, since the position of the belt member in the width direction can be regulated with a simple configuration without adding new components, there is also an excellent effect that cost can be reduced.

In particular, according to the second aspect of the present invention, since the position of the belt member in the width direction is regulated, even if the belt member rotates, the belt does not shift. Accordingly, the belt member does not move due to the movement of the apparatus main body in a place having irregularities or the elongation of the peripheral length of the belt member due to a temperature change, and the above-described positional displacement can be prevented. There is.

In particular, according to the third aspect of the invention, when the toner images of the respective color components formed on the image carrier are superimposed on the intermediate transfer belt, there is no displacement in the width direction. . Thereby, there is an excellent effect that the accuracy of superimposing each color in the width direction on the intermediate transfer belt is improved, and a better image can be formed.

In particular, according to the fourth aspect of the invention, it is possible to prevent abrasion, breakage, and the like of the stopper member, so that there is an excellent effect that the durability of the belt member can be improved.

According to the fifth aspect of the present invention, there is an excellent effect that the position of the belt member in the width direction can be regulated by moving the belt member in a predetermined direction. Further, since the position of the belt member in the width direction can be regulated with a simple configuration without adding new components, there is also an excellent effect that cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a copying machine according to an embodiment.

FIG. 2 is a perspective view of the vicinity of an intermediate transfer device in the copying machine.

FIG. 3 is a diagram for explaining a belt shift mechanism.

FIG. 4 is a diagram illustrating a state in which the intermediate transfer belt is stretched by a tension roller.

FIG. 5 is a graph of an experimental result showing a relationship between an angle and a shift amount.

FIG. 6 is a diagram showing a state in which an intermediate transfer belt according to a conventional example is stretched over rollers.

FIG. 7 is a perspective view around an intermediate transfer device according to a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor drum 4 revolver developing unit 11 intermediate transfer belt 11 a, b non-stop guide 12 bias roller 14 belt drive roller 15 tension roller 30 belt cleaning unit 40 paper transfer unit 100 transfer paper

Claims (5)

[Claims] A belt member; a plurality of roller members for stretching the belt member; and driving means for driving at least one of the plurality of roller members to rotate. In an image forming apparatus provided with a detent member on one of a plurality of roller members, at least one of the plurality of roller members is obliquely shifted with respect to a direction orthogonal to a rotational movement direction of the belt member. An image forming apparatus, wherein the belt member is arranged in a predetermined direction. 2. The image forming apparatus according to claim 1, wherein said belt member is stretched in advance in said predetermined direction and said stopper member is abutted against said belt member. 3. The image forming apparatus according to claim 1, wherein the belt member is an intermediate transfer belt that carries the toner images of the respective color components formed on the image carrier in an overlapping manner. Image forming device. 4. The image forming apparatus according to claim 1, wherein an angle at which the roller member is obliquely shifted with respect to a direction orthogonal to a rotational movement direction of the belt member is 0.01.
An image forming apparatus, wherein the temperature is not less than 1 degree and not more than 1 degree. 5. A belt member, a plurality of roller members for stretching the belt member, and driving means for rotating at least one of the plurality of roller members, the driving member comprising: In a belt driving device provided with a detent member on one of a plurality of roller members, at least one of the plurality of roller members is oblique to a direction orthogonal to a rotational movement direction of the belt member. A belt driving device, wherein the belt driving device is arranged so as to be shifted and the belt member is shifted in a predetermined direction.