JP5760653B2 - Belt conveying apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a belt conveyance device in which an endless belt is stretched by a plurality of rollers, and an image forming apparatus including the belt conveyance device.

  2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus, an image forming apparatus provided with an endless belt as a transfer means for an intermediate transfer member as a transfer medium or a recording sheet as a transfer medium is known.

  In this type of image forming apparatus, the endless belt is circulated and driven around a plurality of rollers. However, when the endless belt is circulated, the endless belt is endless in the direction perpendicular to the belt conveyance direction (main scanning direction). There may occur “belt shift” in which the belt position moves and “belt skew” in which the conveying direction of the endless belt is inclined in the main scanning direction. When the belt is skewed, the image forming position on the transfer medium such as the intermediate transfer member or the recording paper is displaced, which causes image distortion. Further, black (hereinafter referred to as K), yellow (hereinafter referred to as Y), magenta (hereinafter referred to as M), and cyan (hereinafter referred to as C) monochromatic images are formed on the image carrier. In a color image forming apparatus that forms each image and superimposes them on a transfer medium to obtain a color image, a shift in image forming position appears as a color shift between the color toner images. Since both of these lead to image quality degradation, it is necessary to take some measures regarding the belt skew in order to obtain a high-quality image.

  In order to cope with the above problem, various methods have been proposed, and as one of them, a method of providing a “shift guide member” on the endless belt is employed. However, the force in the main scanning direction generated on the endless belt is regulated by abutting a guide member provided on the surface of the endless belt against the end face of the belt conveying roller to suppress the endless belt, so it is formed on the endless belt. The belt skew caused by the deflection of the shifting guide member in the main scanning direction and the deflection of the end face of the conveying roller cannot be suppressed, and there is a problem in that image distortion and color misregistration occur due to misalignment in the main scanning direction.

  Further, when the belt is driven at a high speed, a large external force is applied to the shift guide member, and the belt and the shift guide member are likely to be buckled or damaged, and it is difficult to increase the image output speed.

  To solve this problem, the belt shift is adjusted based on the endless belt member main scanning direction position information, and the main scanning direction latent image formation position on the image carrier is corrected based on the endless belt member main scanning direction tilt information. It is possible to significantly increase the image output speed without using a guide member or other component that hinders high-speed driving of the belt, accurately detecting and controlling the endless belt shift, and accurately skewing the endless belt. Is known, and the image forming position is corrected to prevent image distortion and color misregistration, and the output image can be greatly improved in image quality (for example, Patent Documents 1 to 4). reference).

  Also, a plurality of detecting means for detecting the position of the endless belt in the belt width direction, and two steerings for calculating the deviation and skew of the endless belt based on the detection results of the plurality of detecting means and stretching the belt A technique is known in which distortion of an image is corrected by controlling deviation and skew using a roller (see, for example, Patent Document 5).

  On the other hand, a first adjustment mechanism that moves one end of the steering roller in the first direction and a second adjustment mechanism that moves one end of the steering roller in the second direction, and by operating each of them, the shift of the endless belt is provided. A technique is known in which the adjustment mechanism is selectively used when the endless belt is moved quickly and accurately by adjusting (for example, see Patent Document 6).

  In addition, in order to absorb the change in tension in the belt width direction that occurs when correcting the shift of the endless belt by moving one end of the steering roller, the rollers other than the steering roller are inclined in conjunction with the movement of the steering roller, A technique is known in which belt torsion and image defects due to the influence of belt width direction tension change are prevented by making the tension in the belt width direction uniform (see, for example, Patent Documents 7 to 9). .

  However, as in Patent Documents 1 to 4, when correcting the image distortion and color misregistration due to the skew of the endless belt by the image forming position, the inclination of the endless belt is not directly corrected. When the required image forming position correction amount fluctuates due to variations in product assembly accuracy and environmental conditions, high-accuracy correction cannot be performed, and there is a problem in that there is a limit to high image quality.

  Further, when correcting not only the shift but also the skew by the steering roller as in Patent Document 5, specifically, it is necessary to move one end of the two steering rollers in two different directions as in Patent Document 6. is there. At this time, the tension change in the belt width direction caused by the movement of one end of the steering roller as in Patent Documents 7 to 9 becomes more complicated because the movement conditions of the respective steering rollers influence each other, causing belt twist and image defects. There is a concern that the correction of skew and skew becomes inoperable.

  Furthermore, the analysis revealed that the inclination produced in the tension direction of the tension roller for stretching the belt with a constant tension varies greatly depending on the position of the steering roller, the moving direction of the roller, and the rotation direction of the belt.

  FIG. 4 shows the configuration of the endless belt and roller used in the above analysis. In FIG. 4, the driven roller 1 is urged in the tension direction in the figure, and the belt is driven to rotate while controlling the belt tension acting on both ends of the roller to be a constant value. When the steering condition 1) and the driven roller 2 are inclined around the X axis (steering condition 2) and the Y axis (steering condition 3) in the figure, the relationship between the steering inclination angle and the inclination angle of the driven roller 1 in the tension direction Asked.

  The result of the steering condition 1 is shown in FIG. 5, the result of the steering condition 2 is shown in FIG. 6, and the result of the steering condition 3 is shown in FIG.

  As shown in FIG. 5, in the steering condition 1, if the driven roller 1 is controlled so that there is no tension difference, the driven roller 1 has a small inclination in the tension direction in the belt rotation direction +, and the driven roller 1 in the belt rotation direction −. There is almost no inclination in the tension direction.

  However, under the steering condition 2 as shown in FIG. 6, even if the driven roller 1 is controlled so that there is no tension difference, the inclination in the tension direction of the driven roller 1 changes nonlinearly with respect to the steering inclination.

  Further, under the steering condition 3 as shown in FIG. 7, even when the driven roller 1 is controlled so as not to have a tension difference, the driven roller 1 is hardly inclined in the tension direction in the belt rotation direction − In the belt rotation direction +, the driven roller 1 is greatly inclined in the tension direction.

  As described above, the following behavior was clarified from the analysis results as the cause of the inclination of the tension roller changing nonlinearly or the difference in inclination depending on the rotation direction. That is, A: The belt is tilted by the steering operation, and the belt tilt (belt entry angle) with respect to each roller changes. B: The direction and size of each roller acting on the belt are different from each other, and the belt is deformed in the width direction. C: The tension roller tilts in the tension direction due to the reaction force of the deformation in the belt width direction.

  Here, in the steering condition 3 in FIG. 7, the driven roller 1 that is a tension roller and the driving roller and the driven roller 2 have opposite directions acting on the belt, and each has a large displacement force. A large reaction force of deformation in the belt width direction acts on the belt, and the belt tilts greatly. The direction of the belt acting on the belt reverses depending on the rotation direction, so that the inclination of the tension roller varies greatly depending on the rotation direction. Thus, when the tension roller is greatly inclined with respect to the original inclination angle that makes the belt width direction tension uniform, the tension greatly changes in the belt width direction, and normal operation becomes impossible.

  From these analysis results, when one end of the steering roller is moved in one direction to correct the deviation, normal operation is possible by selecting the moving direction, but one end of the two steering rollers is moved in two different directions. It can be seen that it is difficult to select a moving direction that achieves normal operation when both of them need to be moved.

  For this reason, even if one end of the two steering rollers is moved in two different directions and is shifted to correct skew, a belt twist or an image defect occurs, and the correction of skew and skew becomes inoperable. Occurs.

  The present invention has been made to solve such a problem, and can be significantly increased in speed without using a structural member that hinders belt high-speed driving such as a shift guide member as in the prior art, An object of the present invention is to provide a belt conveyance device and an image forming apparatus capable of accurately correcting the position in the width direction of the endless belt and performing a reliable deviation / slanting correction operation by preventing problems caused by belt twisting. .

The belt conveyance device according to the present invention includes a plurality of rollers substantially parallel to each other, and an endless belt stretched around the plurality of rollers, and the plurality of rollers drive the endless belt; A tension roller supported so as to be displaceable in a tension applying direction so as to apply tension to the endless belt, and a steering supported at one or the other end so as to be relatively movable in a direction perpendicular to the width direction of the endless belt A tension urging means for urging both ends of the tension roller in a tension applying direction, and one end of the steering roller relative to the other end in a direction perpendicular to the width direction of the endless belt. Adjusting means for adjusting the attitude of the steering roller by moving it, and conveying the endless belt by the drive roller to the adjusting means. A belt conveying device that controls the position of the endless belt in the width direction by adjusting the attitude of the steering roller, wherein a friction coefficient between the tension roller and the endless belt is applied to the tension roller in the belt conveying direction. upstream and rather less than the coefficient of friction between the two adjacent rollers the endless belt downstream, the with the surface of one side of the endless belt the tension roller is in contact, the surface of the other side of the endless belt the two adjacent rollers is in contact with the surface of one side of the endless belt, the other side than the coefficient of friction of a side of said endless belt and said small Ikoto.

  With this configuration, it is possible to greatly increase the speed without using a configuration that obstructs high-speed belt driving such as a shift guide member as in the prior art, and it is possible to accurately correct the position in the width direction of the endless belt. By preventing problems due to twisting, it is possible to perform a reliable shift / skew correction operation.

  In the belt conveying device according to the present invention, the other end of the steering roller is moved relative to the one end in a direction orthogonal to the width direction of the endless belt to adjust the attitude of the steering roller. Adjusting the position of the endless belt in the width direction by adjusting the attitude of the steering roller by the adjusting means and the second adjusting means while conveying the endless belt by the driving roller. Features.

  With this configuration, it is possible to significantly increase the speed without using a configuration that obstructs high-speed driving of the belt such as a shift guide member as in the past, and it is possible to accurately correct the shift and skew of the endless belt. By preventing problems due to twisting, it is possible to perform a reliable shift / skew correction operation.

  In the belt conveying device according to the present invention, the surface of the tension roller has a smaller coefficient of friction than the surfaces of the two adjacent rollers.

  With this configuration, it is possible to greatly increase the speed without using a configuration that obstructs high-speed belt driving such as a shift guide member as in the past, and it is possible to accurately shift and skew the endless belt with a simple configuration. It is possible to correct, and it is possible to perform a reliable deviation / skew correction operation by preventing problems caused by belt twist.

  In the belt conveyance device according to the present invention, the tension roller is supported so as not to rotate so that the endless belt slides, and the two adjacent rollers are driven rollers that are brought into contact with the endless belt. It is characterized by being.

  With this configuration, it is possible to greatly increase the speed without using a configuration that obstructs high-speed belt driving such as a shift guide member as in the past, and it is possible to accurately shift and skew the endless belt with a simple configuration. It is possible to correct, and it is possible to perform a reliable deviation / skew correction operation by preventing problems caused by belt twist.

  The image forming apparatus according to the present invention includes an image carrier on which a latent image is formed, a developing unit that visualizes the latent image formed on the image carrier, and a visible image formed by the developing unit. An intermediate transfer body that sequentially transfers primary images of a plurality of colors that have been transferred from the image carrier and secondary transfer of the primary transferred visible image to a recording material. In the apparatus, the belt transfer device is provided as the intermediate transfer member, the position of the endless belt in the main scanning direction is adjusted by the adjusting means, and the main transfer surface of the endless belt on the primary transfer surface that contacts the image bearing member is adjusted. The scanning direction inclination is adjusted by the second adjusting means.

  With this configuration, in an image forming apparatus provided with a belt conveying device, it is possible to significantly increase the image output speed without using a configuration that obstructs high-speed belt driving such as a shift guide member as in the prior art, and simple. In addition, since the distortion and color misregistration can be prevented by reliably correcting the endless belt shift and skewing with a low-cost configuration, the output image can be greatly improved in image quality.

  According to the present invention, it is possible to greatly increase the speed without using a configuration that hinders belt high-speed driving, such as a shift guide member, and to shift and skew the endless belt with a simple and low-cost configuration. It is possible to provide a belt conveying device and an image forming apparatus that can reliably correct.

1 is a diagram illustrating a schematic configuration of a main part of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a diagram illustrating a belt shift detection unit of the image forming apparatus according to the embodiment of the present invention. 1 is a perspective view illustrating a schematic configuration of an intermediate transfer member of an image forming apparatus according to an embodiment of the present invention. FIG. 10 is a configuration diagram for analyzing a relationship between a change in skew angle of an intermediate transfer belt and a change in inclination generated in a tension direction of a tension roller in a conventional image forming apparatus. FIG. 5 is a diagram illustrating a relationship between a steering inclination angle and an inclination angle of a driven roller in a tension direction under the inclination condition 1 in the configuration of FIG. 4. FIG. 5 is a diagram illustrating a relationship between a steering inclination angle and an inclination angle of a driven roller in a tension direction under the inclination condition 2 in the configuration of FIG. 4. FIG. 5 is a diagram illustrating a relationship between a steering inclination angle and an inclination angle of a driven roller in a tension direction under the inclination condition 3 in the configuration of FIG. 4.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, the configuration will be described.

  As shown in FIG. 1, the image forming apparatus 10 includes four photosensitive drums 101, 102, 103, and 104 in which developing devices 131, 132, 133, and 134 are arranged in parallel, and is provided on an endless intermediate transfer belt 200. A full color image is formed.

  In the image forming apparatus 10, at the time of image formation, the four photosensitive drums 101, 102, 103, and 104 as image carriers are rotationally driven in the directions of arrows (counterclockwise), and the surfaces thereof are charged by the chargers 111, 112, After being charged uniformly by 113 and 114, exposure devices 121, 122, 123, and 124 perform exposure according to input image information to form electrostatic latent images, respectively.

  The yellow developing unit 131 causes toner to adhere to the electrostatic latent image on the photosensitive drum 101 and develops it as a yellow toner image. Further, a magenta developing device 132 attaches toner to the electrostatic latent image on the photosensitive drum 102 and develops it as a magenta toner image. Further, a cyan developing device 133 attaches toner to the electrostatic latent image on the photosensitive drum 103 and develops it as a cyan toner image. Further, a black developing device 134 attaches toner to the electrostatic latent image on the photosensitive drum 104 and develops it as a black toner image.

  The yellow toner image, the magenta toner image, the cyan toner image, and the black toner image are primarily transferred onto the intermediate transfer belt 200 that contacts the photosensitive drums 101, 102, 103, and 104 and rotates in the direction of the arrow. It has come to be. Then, four color toner images are superimposed on the intermediate transfer belt 200. These four color toner images are secondarily transferred to a recording material P conveyed from a paper feed cassette (not shown), so that a full color image can be obtained.

  The intermediate transfer belt 200, and the driving roller 211, the driven rollers 212 and 213, the tension roller 214, and the steering roller 215 that stretch the intermediate transfer belt 200 constitute an intermediate transfer member 199 as a belt conveying device.

  As shown in FIG. 2, on the surface of the intermediate transfer belt 200, a line-shaped detection mark 201 formed over the entire circumference in the transport direction is formed at a fixed position in the main scanning direction (width direction). . Two belt offset / skew detection means 205 for detecting the position of the detection mark 201 in the main scanning direction are arranged at a position facing the detection mark 201, and the belt deviation / skew detection means 205 is provided as a detection mark. By detecting the position of 201 in the main scanning direction (width direction of the intermediate transfer belt 200), the displacement (belt deviation) of the intermediate transfer belt 200 in the main scanning direction can be detected as belt deviation detection information. ing. The movement of the intermediate transfer belt 200 in the main scanning direction is also referred to as “belt shift” hereinafter.

  As shown in FIG. 3, two belt deviation / skew detection means 205 are arranged on the primary transfer surface (upper surface) of the intermediate transfer belt 200 at a predetermined interval in the sub-scanning direction (belt conveyance direction). ing. By detecting the difference in position in the main scanning direction of the detection marks 201 detected by the two belt deviation / skew detection means 205, the belt skew detection of the intermediate transfer belt 200 is detected. It can be detected as information.

  As described above, the movement in the main scanning direction of the line-shaped detection mark 201 formed with high accuracy in advance on the intermediate transfer belt 200 is detected by the two belt deviation / skew detection means 205 arranged in the sub-scanning direction. In order to detect the belt deviation by detecting, refer to the edge data measured in advance as compared with the configuration for detecting the belt deviation by detecting the position of the belt edge (for example, see Japanese Patent Application Laid-Open No. 2000-233843). In addition, it is not necessary to store data that averages periodic fluctuations of the edge position in the storage means, etc., so it is possible to detect and control the belt deviation at high speed without waste time with a lower cost configuration It has become.

  As shown schematically in FIG. 3, the intermediate transfer member 199 as a belt conveying device includes a driving roller 211, driven rollers 212, and 213 as a plurality of rollers arranged substantially parallel to each other, which stretch the intermediate transfer belt 200. , A tension roller 214 and a steering roller 215 are provided. The intermediate transfer belt 200 is driven in the belt conveyance direction by a driving roller 211 among the plurality of rollers.

  A drive source 250 such as a motor for driving the drive roller 211 is provided at one end of the drive roller 211. The driving source 250 may be a transmission gear that transmits driving force from another motor (not shown).

  The driving roller 211 and the driven rollers 212 and 213 are fixed at predetermined positions, whereas the tension roller 214 is urged at both ends of the rotation shaft in the direction of the arrow (tension direction). The transfer belt 200 is stretched with a substantially constant tension.

  Specifically, both ends of the tension roller 214 are respectively urged in the tension direction by a load generator 219 as a tension urging means, and the tension roller 214 is attached with an arbitrary tension by controlling the load generator 219. It is possible to support.

  Further, the steering roller 215 corrects the belt shift and skew generated in the intermediate transfer belt 200, and one end side 215a and the other end side 215b are swung in a direction orthogonal to the roller rotation axis indicated by an arrow by a pivot bearing or the like. It is supported movably. Specifically, one end side 215a of the steering roller 215 is supported by an actuator 216 so as to be reciprocally movable in the arrow direction, and the other end side 215b is supported by an actuator 217 so as to be reciprocally movable in the arrow direction.

  Based on the belt deviation detection information, a control unit (not shown) drives the actuator 216 and swings the steering roller 215 so that the intermediate transfer belt 200 moves in a direction opposite to the generated movement in the belt main scanning direction. The belt shift is controlled within a certain range, and the belt shift can be suppressed without providing a shift guide member or the like as in the prior art.

  Further, based on the belt skew detection information, a control unit (not shown) drives the actuator 217 to swing the steering roller 215 so that the intermediate transfer belt 200 is inclined in the direction opposite to the generated inclination in the belt main scanning direction. Thus, the belt skew is controlled within a certain range, and image distortion and color misregistration can be prevented.

  In the present embodiment, the coefficient of friction between the tension roller 214 and the intermediate transfer belt 200 is between the driven roller 213 and the steering roller 215 and the intermediate transfer belt 200 adjacent to the tension roller 214 on the upstream and downstream sides in the belt conveyance direction. The value is smaller than the friction coefficient. That is, the friction coefficient between the tension roller 214 and the intermediate transfer belt 200 is smaller than the friction coefficient between the driven roller 213 and the intermediate transfer belt 200, and the friction between the tension roller 214 and the intermediate transfer belt 200 is small. The coefficient is smaller than the friction coefficient between the steering roller 215 and the intermediate transfer belt 200.

  As described above, the following three methods can be used to reduce the friction coefficient between the tension roller 214 and the intermediate transfer belt 200 to a value smaller than the friction coefficient between the two rollers adjacent to the belt conveyance direction and the intermediate transfer belt 200. Techniques can be used.

  That is, the first method of reducing the friction of the surface of the tension roller 214 by smoothing or lubricating coating, or the surface (outer surface) of the intermediate transfer belt 200 on the side in contact with the tension roller 214 is smoothed or lubricated. The second method for reducing the friction by the property coating process, or by fixing the tension roller 214 so that the intermediate transfer belt 200 slides and setting the coefficient of friction between them as the dynamic coefficient of friction reduces the friction. A third technique can be used. These three methods can be used alone or in combination.

  As the first method, for example, the roller surface of the tension roller 214 is processed to have a surface roughness smaller than the roller surfaces of the driven roller 213 and the steering roller 215, or the roller surface of the tension roller 214 is On the other hand, by applying a surface coat with good lubricity such as a fluororesin, the friction coefficient between the tension roller 214 and the intermediate transfer belt 200, the friction coefficient between the driven roller 213 and the intermediate transfer belt 200, and the steering roller 215. And a value smaller than the friction coefficient between the intermediate transfer belt 200 and the intermediate transfer belt 200.

  In this way, as a result of driving the actuators 216 and 217 to swing the steering roller 215 to correct the belt shift and the belt skew, the tension roller 214 and the upstream side of the tension roller 214 in the belt conveyance direction and Even if the shifting force acting on the intermediate transfer belt 200 between the driven roller 213 and the steering roller 215 adjacent to each other on the downstream side is in the reverse direction, the tension roller 214 and the intermediate transfer belt 200 having a small friction coefficient are used. As a result, slippage in the direction of the belt is generated, and the belt reaction force acting on the tension roller 214 is reduced. Therefore, the tension roller 214 is not greatly inclined.

  In FIG. 3, the surface of the intermediate transfer belt 200 on the side where the tension roller 214 abuts is different from the surface of the intermediate transfer belt 200 on the side where the driven roller 213 and the steering roller 215 abut.

  That is, the tension roller 214 is disposed so as to contact the outer surface of the endless intermediate transfer belt 200, while the driven roller 213 and the steering roller 215 are disposed on the inner side of the endless intermediate transfer belt 200. It arrange | positions so that it may contact | abut on a surface.

  Therefore, as the second method described above, the outer surface of the intermediate transfer belt 200, which is the surface on which the tension roller 214 is in contact, and the intermediate transfer belt 200, which is the surface on which the driven roller 213 and the steering roller 215 are in contact with each other. The friction coefficient between the tension roller 214 and the intermediate transfer belt 200 is set to be smaller than the friction coefficient between the driven roller 213 and the steering roller 215 and the intermediate transfer belt 200. Can do.

  Specifically, the outer surface of the intermediate transfer belt 200, which is the surface on the side where the tension roller 214 abuts, is rougher than the inner surface of the intermediate transfer belt 200, on which the driven roller 213 and the steering roller 215 are abutted. The friction coefficient between the tension roller 214 and the intermediate transfer belt 200 can be set to the driven roller 213 and the intermediate transfer belt 200 by using a small-layer process or a two-layer structure having a surface made of a material having good lubricity such as a fluororesin. A value smaller than a friction coefficient between the steering roller 215 and the intermediate transfer belt 200 can be set.

  Further, as the third method, the tension roller 214 and the intermediate transfer belt 200 are supported by a tension roller 214 in a fixed state that does not rotate around the axis and is not driven with the intermediate transfer belt 200. Is a sliding state. On the other hand, the driven roller 213 and the steering roller 215 are driven rollers that can rotate around their axes.

  As a result, the friction coefficient between the tension roller 214 and the intermediate transfer belt 200 becomes a dynamic friction coefficient, and the friction coefficient between the driven roller 213 and the steering roller 215 and the intermediate transfer belt 200 becomes a static friction coefficient.

  Therefore, the friction coefficient (dynamic friction coefficient) between the tension roller 214 and the intermediate transfer belt 200 is set to a value smaller than the friction coefficient (static friction coefficient) between the driven roller 213 and the steering roller 215 and the intermediate transfer belt 200. it can.

  In the image forming apparatus 10 of FIG. 1 provided with the intermediate transfer member 199 as the belt conveying apparatus of FIG. 3, the deviation and skew of the intermediate transfer belt 200 can be reliably corrected with a simple and low-cost configuration. Distortion and color shift can be prevented.

  As described above, the intermediate transfer member 199 according to the present embodiment includes the plurality of rollers that are substantially parallel to each other and the intermediate transfer belt 200 that is stretched around the plurality of rollers. A driving roller 211 for driving the belt 200, a tension roller 214 supported so as to be displaceable in a tension applying direction so as to apply tension to the intermediate transfer belt 200, and one end or the other end of the tension roller 214 orthogonal to the width direction of the intermediate transfer belt 200 A steering roller 215 supported so as to be relatively movable in the direction in which the tension roller 214 is urged, and a load generator 219 that urges both ends of the tension roller 214 in the tension applying direction, and one end of the steering roller 215 relative to the other end. An actuator that adjusts the attitude of the steering roller 215 by relatively moving the intermediate transfer belt 200 in a direction perpendicular to the width direction of the intermediate transfer belt 200. 216, and controls the position of the intermediate transfer belt 200 in the width direction by adjusting the attitude of the steering roller 215 by the actuator 216 while conveying the intermediate transfer belt 200 by the driving roller 211, and the tension roller 214 The friction coefficient between the intermediate transfer belt 200 and the intermediate transfer belt 200 is equal to the friction coefficient between the two rollers (the driven roller 213 and the steering roller 215) adjacent to the tension roller 214 on the upstream side and the downstream side in the belt conveyance direction. It is characterized by being smaller.

  With this configuration, the speed of the intermediate transfer belt 200 in the width direction of the intermediate transfer belt 200 can be accurately corrected and the speed can be greatly increased without using a configuration that obstructs the high-speed driving of the belt such as a conventional guide member. In addition, it is possible to perform a reliable deviation / skew correction operation by preventing problems caused by belt twisting.

  In addition, the intermediate transfer member 199 according to the present embodiment moves the other end of the steering roller 215 relative to one end in a direction orthogonal to the width direction of the intermediate transfer belt 200 to change the posture of the steering roller 215. An adjusting actuator 217 is provided, and the position of the intermediate transfer belt 200 in the width direction is controlled by adjusting the attitude of the steering roller 215 by the actuator 216 and the actuator 217 while conveying the intermediate transfer belt 200 by the driving roller 211. To do.

  With this configuration, it is possible to significantly increase the speed without using a conventional configuration that obstructs high-speed belt driving such as a shift guide member, and to accurately correct the shift and skew of the intermediate transfer belt 200. In addition, it is possible to perform a reliable deviation / skew correction operation by preventing problems caused by belt twisting.

  Further, the intermediate transfer member 199 according to the present embodiment is characterized in that the surface of the tension roller 214 has a smaller coefficient of friction than the surfaces of the two adjacent rollers (the driven roller 213 and the steering roller 215).

  With this configuration, it is possible to significantly increase the speed without using a conventional configuration that hinders belt high-speed driving such as a shift guide member, and the intermediate transfer belt 200 can be shifted and tilted accurately with a simple configuration. The line can be corrected, and a reliable deviation / skew correction operation can be performed by preventing problems caused by the twisting of the belt.

  In addition, the intermediate transfer member 199 according to the present embodiment has a tension roller 214 in contact with a surface on one side of the intermediate transfer belt 200 and the two adjacent rollers (on the other surface of the intermediate transfer belt 200). The driven roller 213 and the steering roller 215 are in contact with each other, and the surface of one side of the intermediate transfer belt 200 has a smaller coefficient of friction than the surface of the other side of the intermediate transfer belt 200.

  With this configuration, it is possible to significantly increase the speed without using a conventional configuration that hinders belt high-speed driving such as a shift guide member, and the intermediate transfer belt 200 can be shifted and tilted accurately with a simple configuration. The line can be corrected, and a reliable deviation / skew correction operation can be performed by preventing problems caused by the twisting of the belt.

  Further, in the intermediate transfer member 199 according to the present embodiment, the tension roller is supported so as not to rotate so that the intermediate transfer belt 200 slides, and the two adjacent rollers (the driven roller 213 and the steering roller 215) are The driven roller is brought into contact with the intermediate transfer belt 200 and is driven.

  With this configuration, it is possible to greatly increase the speed without using a configuration that obstructs high-speed belt driving such as a shift guide member as in the past, and it is possible to accurately shift and skew the endless belt with a simple configuration. It is possible to correct, and it is possible to perform a reliable deviation / skew correction operation by preventing problems caused by belt twist.

  In addition, the image forming apparatus 10 according to the present embodiment allows the photosensitive drums 101, 102, 103, and 104 on which the latent image is formed and the latent images formed on the photosensitive drums 101, 102, 103, and 104 to be used. From the photosensitive drums 101, 102, 103, 104, developing devices 131, 132, 133, 134 for visualizing, and visible images for a plurality of colors visualized by the developing devices 131, 132, 133, 134 are displayed. And an intermediate transfer body 199 that sequentially transfers the primary image to the recording material P, and adjusts the position of the intermediate transfer belt 200 in the main scanning direction by the actuator 216. The inclination of the primary transfer surface of the intermediate transfer belt 200 in contact with the photosensitive drums 101, 102, 103, 104 is adjusted by the actuator 217. And features.

  With this configuration, in the image forming apparatus 10, it is possible to significantly increase the image output speed without using a configuration that obstructs high-speed belt driving such as a shift guide member as in the prior art, and it is simple and low-cost. With the configuration, it is possible to prevent image distortion and color misregistration by reliably correcting the shift and skew of the intermediate transfer belt 200, so that the output image can be greatly improved in image quality.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 101, 102, 103, 104 Photosensitive drum (Image carrier)
111, 112, 113, 114 Charger 121, 122, 123, 124 Exposure device 131, 132, 133, 134 Developer 199 Intermediate transfer member (belt transport device)
200 Intermediate transfer belt (endless belt)
201 Detection mark 205 Belt deviation / skew detection means 211 Drive roller 212, 213 Followed roller 214 Tension roller 215 Steering roller 216 Actuator (adjustment means)
217 Actuator (second adjusting means)
219 Load generator (tension biasing means)
250 Driving source

JP 2010-217300 A JP 2010-217301 A JP 2011-002632 A JP 2011-022549 A JP 2000-233843 A JP 2007-163695 A JP 2001-147601 A JP 2002-091185 A JP 2009-025475 A

Claims (5)

A plurality of rollers substantially parallel to each other;
An endless belt stretched around the plurality of rollers,
The plurality of rollers are
A driving roller for driving the endless belt;
A tension roller supported so as to be displaceable in a tension applying direction to apply tension to the endless belt;
A steering roller having one end or the other end supported so as to be relatively movable in a direction perpendicular to the width direction of the endless belt,
Tension urging means for urging both ends of the tension roller in a tension applying direction;
Adjusting means for adjusting the attitude of the steering roller by moving one end of the steering roller relative to the other end in a direction perpendicular to the width direction of the endless belt;
A belt conveying device that controls the position of the endless belt in the width direction by adjusting the attitude of the steering roller by the adjusting means while conveying the endless belt by the driving roller;
The coefficient of friction between the endless belt and said tension roller, said tension roller on the upstream side of the belt conveying direction and two rollers adjacent the downstream side the rather smaller than the coefficient of friction between the endless belt,
The tension roller is in contact with the surface on one side of the endless belt, and the two adjacent rollers are in contact with the surface on the other side of the endless belt,
The surface of one side of the endless belt, the belt conveying device other friction coefficient than the surface on the side of the endless belt and wherein the small Ikoto. Second adjustment means for adjusting the attitude of the steering roller by moving the other end of the steering roller relative to one end in a direction perpendicular to the width direction of the endless belt;
The position of the endless belt in the width direction is controlled by adjusting the posture of the steering roller by the adjusting means and the second adjusting means while conveying the endless belt by the driving roller. The belt conveyance apparatus as described in.   The belt conveyance device according to claim 1 or 2, wherein the surface of the tension roller has a smaller coefficient of friction than the surfaces of the two adjacent rollers. The tension roller is supported non-rotatably so that the endless belt slides,
The belt conveying device according to any one of claims 1 to 3 , wherein the two adjacent rollers are driven rollers that are brought into contact with the endless belt. An image carrier on which a latent image is formed;
A developing unit that visualizes the latent image formed on the image carrier;
An intermediate transfer in which visible images of a plurality of colors visualized by the developing device are sequentially primary-transferred from the image carrier and the primary-transferred visible image is secondarily transferred to a recording material. An image forming apparatus comprising: a body;
The belt transfer device according to any one of claims 2 to 4 is provided as the intermediate transfer member,
The main scanning direction position of the endless belt is adjusted by the adjusting means, and the main scanning direction inclination of the primary transfer surface in contact with the image carrier of the endless belt is adjusted by the second adjusting means. An image forming apparatus.

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