JP2014074877A - Belt deviation correction mechanism, belt device, transfer belt device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deviation correction mechanism that achieves stable running of a belt with the minimum necessary number of components without using a sensor.SOLUTION: A deviation correction mechanism 30 corrects deviation in a width direction of an endless belt laid over a plurality of rollers. The deviation correction mechanism 30 includes a pair of journal members 31 that support both ends of a shaft 10a of a driven roller 10 and can be moved individually in a direction to allow the movement in the shaft direction of the roller 10 and increase tension of an intermediate transfer belt 8. On both ends of the roller 10, flange parts 10c are provided where the belt 8 moves in deviation and comes into contact at end parts thereof. The journal members 31 on the right and left sides are urged by an urging mechanism comprising tension springs 35a and 35b and lever members 33 and 53, in a direction to increase the tension of the belt 8. A roller reception member 32 is moved in association with the movement in the shaft direction of the roller 10 caused by the deviation movement of the belt 8 so as to decrease the urging force applied to the journal member 31 on the deviation side of the belt 8 and increase the urging force applied to the journal member 31 on the opposite side.

Description

  The present invention relates to a belt misalignment correction mechanism, and a belt device, a transfer belt device using the correction mechanism, and an image forming apparatus such as an electrophotographic copying machine, a printer, a plotter, a facsimile, or a complex machine thereof. It relates to the device.

  In this type of image forming apparatus, a photosensitive member, which is an image carrier, is charged by a charging unit, and an electrostatic latent image is formed by irradiating the charged photosensitive member with a light beam modulated according to an original image or image information. To do. The electrostatic latent image is developed with the toner of the developing means to be visualized, the visible image is transferred directly or via an intermediate transfer member to a transfer material such as transfer paper, and the image transferred to the transfer material is fixed to the fixing means. To fix and obtain an image. When a color image is formed, the above-described charging, latent image formation, development, and transfer processes are performed for a plurality of colors, and a plurality of colors are superimposed to form a color image.

  For example, as an example of a color image forming apparatus, a single photosensitive member, a plurality of developing units and an intermediate transfer member are used, and an image for each color (for example, yellow, yellow, etc.) is formed on the photosensitive member through processes of charging, latent image formation, and development. Magenta, cyan, and black images). Then, the process of transferring to the intermediate transfer member is performed for the number of colors, and a color image is formed by superimposing four colors on the intermediate transfer member. There is known a color image forming apparatus which obtains a color image by fixing with a toner.

  Another example of the color image forming apparatus is one in which a plurality of image forming units each including a photoconductor, a charging unit, a developing unit, a transfer unit, and the like are arranged in parallel along the intermediate transfer body. Each image forming unit forms an image of each color of yellow, magenta, cyan, and black, and sequentially superimposes the images of each color of yellow, magenta, cyan, and black formed by each image forming unit on the intermediate transfer member. Transcript. Thereafter, a color image is formed by superimposing the four colors on the intermediate transfer member, and the color image is collectively transferred from the intermediate transfer member to a transfer material and fixed by a fixing unit to obtain a color image. Such a so-called tandem type color image forming apparatus is conventionally known.

  Some tandem color image forming apparatuses include a plurality of image forming units arranged along the transfer material conveying means without using an intermediate transfer member. That is, a color in which images of each color of yellow, magenta, cyan, and black formed by each image forming unit are sequentially superimposed and transferred onto a transfer material conveyed by a transfer material conveying unit, and four colors are superimposed on the transfer material An image is formed, and the color image is fixed by a fixing unit to obtain a color image.

  In the various image forming apparatuses as described above, the endless belt traveling apparatus is used in various parts. For example, a belt-shaped photoreceptor (photosensitive belt) that is an image carrier, a belt-shaped intermediate transfer body (intermediate transfer belt), a transfer material transport belt that transports a transfer material, a belt-shaped fixing member (fixing belt), and the like What was applied as a traveling device is known.

  In general, in an endless belt traveling apparatus that supports an endless belt with a plurality of rollers and travels the endless belt using one of the rollers as a driving roller, a phenomenon in which a so-called meandering belt or skew (skew) occurs is known. Yes. In other words, due to non-uniformity problems such as roller roundness, straightness, parallelism, belt circumference difference, belt width direction tension difference, left and right frictional force on the surface of the roller or belt, This is a phenomenon in which the endless belt moves in the width direction (direction perpendicular to the belt traveling direction).

  If the belt meandering or shifting is severe, the endless belt will fall off the rollers (driving roller, driven roller) and the belt will be damaged. Further, even if the endless belt is not dropped or damaged, the meandering of the belt may greatly reduce the quality of the formed image.

  In particular, as in the case of a color image forming apparatus, when forming a single color image by transferring each color image formed on a photosensitive member onto an intermediate transfer belt (or transfer material) by superimposing the number of colors, a belt is used. The transfer position is displaced by meandering of the (photosensitive belt, intermediate transfer belt or transfer material conveying belt), and color misregistration and image unevenness are easily noticeable. As described above, the meandering and deviation of the belt cause the image quality to be remarkably deteriorated in the case of the intermediate transfer belt of the color image forming apparatus.

  The fixing belt also has a problem that if the meandering or deviation occurs during running of the belt, the fixing belt is damaged, jammed or paper jam occurs, and image misalignment (image contamination) due to the meandering of the fixing belt. Will also occur.

  For this reason, various proposals have been made to prevent the endless belt from meandering and shifting. For example, using the characteristic that the transfer belt is offset in the direction of strong tension in the left / right direction, the sensor detects the offset direction and the amount, and adjusts the left / right difference in the tension of the transfer belt using the power of the motor etc. by feedback control. The technology to do is known.

  For example, Patent Document 1 (Japanese Patent No. 4590215) discloses an apparatus in which line sensors are disposed on both side edges in a direction perpendicular to the running direction of the transfer belt for the purpose of correcting the deviation of the belt. Yes. In this apparatus, when the occurrence of meandering on the left side is detected by the line sensor, the belt tension adjusting means on the right side of the tension roller is operated by the control unit to increase the belt tension on the right side of the tension roller. When the belt tension on the right side of the roller increases, the transfer belt moves to the right side, and the meandering to the left side is corrected. If meandering to the right occurs, meandering can be corrected in the same way.

  In addition, when the driven roller tilts to the right when viewed from the front of the transfer belt running direction with respect to the driving roller, the transfer belt is shifted to the left, and when it is tilted to the left, the roller is shifted to the right. Techniques for adjusting the degree are also known.

  For example, Patent Document 2 (Japanese Patent No. 3919589) discloses an endless movement direction of an endless belt portion wound around at least one support member among a plurality of support members for the purpose of correcting the deviation of the belt, and the endlessness. Inclination detecting means for detecting the inclination of the belt portion with the normal endless moving direction is disclosed. The meandering is corrected by correcting the endless moving direction of the endless belt portion to the normal endless moving direction based on the detection result by the inclination detecting means.

  However, the conventional device for correcting the meandering / deviation of the endless belt requires a motor and driving system power for adjusting the belt tension in addition to the sensor and the control unit, and thus has a problem of high cost.

  An object of this invention is to provide the belt apparatus which can implement | achieve the stable belt driving | running with few members, without using drive systems, such as a sensor, a control part, and a motor.

In order to solve the above problems, the present invention provides a displacement correction mechanism that is attached to at least one roller in order to correct a displacement in the width direction of an endless belt that is stretched between a plurality of rollers. The offset correction mechanism is
A pair of shaft support members that support both ends of the roller shaft and allow the roller to move in the axial direction while individually moving in a direction to increase or decrease the tension of the belt, and the pair of shaft support members, It is generated by the biasing mechanism that biases the belt in the direction of increasing the tension, a pair of flange portions that are formed at both ends of the roller and abutted against the edge of the belt that has shifted to the one side, and the one side movement of the belt. Due to the movement of the roller in the axial direction, the biasing force of the biasing mechanism on the other shaft support member on the opposite side to the movement direction is more than the biasing force of the biasing mechanism on the one pivot support member in the movement direction. And an urging force adjusting means for relatively increasing the deviation correction mechanism.

  According to the belt deviation correction mechanism of the present invention and the belt device and transfer belt device using the correction mechanism, a stable belt traveling can be performed with a small number of members without using a drive system such as a sensor, a control unit, and a motor. Can be realized. Further, in the image forming apparatus using the correction mechanism, since the belt running is stable, a good image can be obtained.

1 is a schematic cross-sectional view showing an embodiment of an image forming apparatus using a belt deviation correction mechanism of the present invention. FIG. 2 is a plan view of a driven roller of an intermediate transfer belt having a first embodiment of a belt deviation correcting mechanism of the present invention. FIG. 2 is a perspective view of one end of a driven roller of an intermediate transfer belt having a first embodiment of a belt deviation correcting mechanism of the present invention. FIG. 3 is a plan view of a driven roller when the intermediate transfer belt of FIG. 2 is moved to the right. FIG. 3 is a plan view of a driven roller when the intermediate transfer belt of FIG. 2 is moved to the left. FIG. 6 is a plan view of a driven roller of an intermediate transfer belt having a second embodiment of a belt deviation correcting mechanism of the present invention. FIG. 6 is a plan view of a driven roller when the intermediate transfer belt of FIG. 5 is moved to the right. FIG. 6 is a plan view of a driven roller when the intermediate transfer belt in FIG. 5 is moved to the left. FIG. 6 is a plan view of a driven roller of an intermediate transfer belt having a first modified embodiment of a belt deviation correction mechanism of the present invention. FIG. 9 is a plan view of a driven roller of an intermediate transfer belt having a second modified embodiment of the belt deviation correcting mechanism of the present invention. FIG. 10 is a plan view of a driven roller of an intermediate transfer belt having a third modified embodiment of the belt deviation correcting mechanism of the present invention. (A)-(c) is a figure which shows the action | operation of the deviation correction mechanism of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings for explaining the present invention, components such as members and components having the same function or shape are denoted by the same reference numerals as much as possible, and once described, the description will be given. Omitted.

(Image forming device)
First, the overall configuration and operation of an image forming apparatus that uses the belt deviation correction mechanism of the present invention will be described with reference to FIG.
The image forming apparatus shown in FIG. 1 is a color laser printer, and four process units 1Y, 1M, 1C, and 1Bk as image forming units are detachably mounted on the apparatus main body 100. Each process unit 1Y, 1M, 1C, 1Bk contains developers of different colors of yellow (Y), magenta (M), cyan (C), and black (Bk) corresponding to the color separation components of the color image. The configuration is the same except that. In this embodiment, a one-component developer made of toner is used as the developer.

  Specifically, each of the process units 1Y, 1M, 1C, and 1Bk includes a drum-shaped photosensitive member 2 as a latent image carrier, a charging roller 3 that charges the surface of the photosensitive member 2, and the like, The image forming apparatus includes a developing device 4 that supplies toner to the surface of the photoconductor 2 and a cleaning device that includes a cleaning blade 5 for cleaning the surface of the photoconductor 2. In FIG. 1, only the photoconductor 2, the charging roller 3, the developing device 4, and the cleaning blade 5 included in the yellow process unit 1 </ b> Y are denoted by reference numerals. Omitted.

  In FIG. 1, an exposure device 6 as an exposure means for exposing the surface of the photoreceptor 2 is disposed above each process unit 1Y, 1M, 1C, 1Bk. The exposure device 6 includes a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates the surface of each photoreceptor 2 with laser light based on image data.

  A transfer device 7 is disposed below each process unit 1Y, 1M, 1C, 1Bk. The transfer device 7 has an intermediate transfer belt 8 constituted by an endless belt as a transfer body. The intermediate transfer belt 8 is stretched between a driving roller 9 as a support member and a driven roller 10, and when the driving roller 9 rotates counterclockwise in the figure, the intermediate transfer belt 8 is changed to an arrow in the figure. It is configured to run around (rotate) in the direction shown. A biasing force is applied to the shaft of the driven roller 10 in a direction away from the shaft of the driving roller, and a predetermined tension is applied to the intermediate transfer belt 8 by this biasing force. For this reason, the driven roller 10 is also called a tension roller. Usually, one or two or more rollers are rotatably disposed between the driving roller 9 and the driven roller 10, and the intermediate transfer belt 8 is supported by three or more rollers.

  Four primary transfer rollers 11 as primary transfer means are disposed at positions facing the four photoconductors 2. Each primary transfer roller 11 presses the inner peripheral surface of the intermediate transfer belt 8 at each position, and a primary transfer nip is formed at a location where the pressed portion of the intermediate transfer belt 8 and each photoconductor 2 are in contact with each other. ing. Each primary transfer roller 11 is connected to a power source (not shown), and a predetermined direct current voltage (DC) and / or alternating current voltage (AC) is applied to the primary transfer roller 11.

  A secondary transfer roller 12 as a secondary transfer unit is disposed at a position facing the drive roller 9. The secondary transfer roller 12 presses the outer peripheral surface of the intermediate transfer belt 8, and a secondary transfer nip is formed at a location where the secondary transfer roller 12 and the intermediate transfer belt 8 are in contact with each other. Similar to the primary transfer roller 11, the secondary transfer roller 12 is connected to a power source (not shown) so that a predetermined direct current voltage (DC) and / or alternating current voltage (AC) is applied to the secondary transfer roller 12. It has become.

  A belt cleaning device 13 for cleaning the surface of the intermediate transfer belt 8 is disposed on the outer peripheral surface on the right end side of the intermediate transfer belt 8 in the drawing. A waste toner transfer hose (not shown) extending from the belt cleaning device 13 is connected to an entrance of a waste toner container 14 disposed below the transfer device 7.

  A paper feed cassette 15 that accommodates a recording medium P such as paper or an OHP sheet is disposed below the apparatus main body 100. The paper feed cassette 15 is provided with a paper feed roller 16 for feeding out the stored recording medium P. On the other hand, a pair of paper discharge rollers 17 for discharging the recording medium to the outside and a paper discharge tray 18 for stocking the discharged recording medium are disposed on the upper part of the apparatus main body 100.

  In the apparatus main body 100, a transport path R for transporting the recording medium P from the paper feed cassette 15 through the secondary transfer nip to the paper discharge tray 18 is disposed. In the transport path R, a pair of timing rollers 19 are disposed upstream of the position of the secondary transfer roller 12 in the recording medium transport direction. A fixing device 20 is disposed downstream of the position of the secondary transfer roller 12 in the recording medium conveyance direction.

The image forming apparatus operates as follows.
When the image forming operation is started, the photosensitive members 2 of the process units 1Y, 1M, 1C, and 1Bk are rotated in the clockwise direction in FIG. 1, and the surface of each photosensitive member 2 is made to have a predetermined polarity by the charging roller 3. It is charged like this. Based on the image information of the document read by a reading device (not shown), the exposure device 6 irradiates the charged surface of each photoconductor 2 with laser light, and an electrostatic latent image is formed on the surface of each photoconductor 2. . At this time, the image information to be exposed on each photoconductor 2 is single-color image information obtained by separating a desired full-color image into color information of yellow, magenta, cyan, and black. As the electrostatic latent image formed on the photosensitive member 2 is supplied with toner by each developing device 4, the electrostatic latent image is visualized (visualized) as a toner image.

  A drive roller 9 that stretches the intermediate transfer belt 8 is driven to rotate, causing the intermediate transfer belt 8 to run in the direction of the arrow in the figure. Also, a primary transfer nip between each primary transfer roller 11 and each photoreceptor 2 is applied to each primary transfer roller 11 by applying a constant voltage or a voltage controlled by a constant current opposite to the charging polarity of the toner. A transfer electric field is formed. Then, the toner images of the respective colors on the respective photoconductors 2 are sequentially superimposed and transferred onto the intermediate transfer belt 8 by the transfer electric field formed in the primary transfer nip. Thus, the intermediate transfer belt 8 carries a full-color toner image on its surface. Further, the toner on each photoreceptor 2 that could not be transferred to the intermediate transfer belt 8 is removed by the cleaning blade 5.

  When the image forming operation is started, the paper feed roller 16 rotates and the recording medium P is carried out from the paper feed cassette 15. The unloaded recording medium P is timed by the timing roller 19 and sent to the secondary transfer nip between the secondary transfer roller 12 and the intermediate transfer belt 8. At this time, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the intermediate transfer belt 8 is applied to the secondary transfer roller 12, thereby forming a transfer electric field in the secondary transfer nip. Then, the toner image on the intermediate transfer belt 8 is collectively transferred onto the recording medium P by the transfer electric field formed in the secondary transfer nip. Thereafter, the recording medium P is sent to the fixing device 20 and the toner image is fixed on the recording medium P. Then, the recording medium P is discharged to the paper discharge tray 18 by the pair of paper discharge rollers 17.

  The above description is an image forming operation when a full-color image is formed on a recording medium. A single color image is formed using any one of the four process units 1Y, 1M, 1C, and 1Bk, and 2 Two or three process units can be used to form a two or three color image.

  In the above-described embodiment, the one-component developer made of toner is used as the developer. However, the present invention is not limited to this, and can be applied to an image forming apparatus using a two-component developer made of toner and carrier. It is. The image forming apparatus to which the configuration of the present invention is applied is not limited to the tandem type color laser printer as shown in FIG. 1, but may be other printers, copiers, facsimiles, or complex machines thereof. . It goes without saying that various modifications can be made without departing from the scope of the present invention.

(Intermediate transfer belt offset correction mechanism)
As described above, the intermediate transfer belt 8 is stretched between the driving roller 9 as the support member and the driven roller 10, but each of the rollers 9, 10 has roundness, straightness, parallelism, etc. Since there is an error in accuracy, the belt 8 that is running always shifts. Therefore, the intermediate transfer belt device is provided with a deviation correction mechanism that corrects the deviation of the intermediate transfer belt 8. In the misalignment correcting mechanism of the present invention, one or more rollers are rotatably disposed between the driving roller 9 and the driven roller 10, and the intermediate transfer belt 8 is supported by three or more rollers. The present invention can also be applied to a belt device.

(Belt deviation correction mechanism according to the first embodiment)
FIG. 2 is a plan view of the end portion of the intermediate transfer belt 8 on the side of the driven roller 10 as viewed from above, and FIG. 3 shows the end portion obliquely. It is the perspective view seen from the upper part. The correction mechanism 30 in FIG. 2 has a bilaterally symmetric structure. The driven roller 10 has a function of applying a predetermined tension to the intermediate transfer belt 8 and is also called a tension roller as described above.

  In order to apply a predetermined tension to the intermediate transfer belt 8, the left and right ends of the shaft 10 a that supports the driven roller 10 are supported by a pair of left and right shaft support members 31. The shaft support member 31 is individually movable in a direction in which the tension of the intermediate transfer belt 8 is increased and a direction in which the tension is reduced (a direction in which the tension is increased or decreased). The shape of the shaft support member 31 is shown as a plate-like body extending toward the opposite drive roller 9 in the illustrated example, but the shape is merely an example, and the shaft support member 31 need not be limited to a plate-like body.

  When the main body 10b of the driven roller 10 is attached to the shaft 10a of the driven roller 10 so as to be rotatable and movable in the axial direction, the shaft 10a may be simply fixedly supported on the shaft support member 31. When the shaft 10a is a rotating shaft integrated with the driven roller 10, the shaft 10a is supported by the shaft support member 31 so as to be rotatable and movable in the axial direction.

  A roller receiving member 32 as an urging force adjusting means is disposed on the side of the driven roller 10, that is, on the side of the driven roller 10 of the driven roller 10. The roller receiving member 32 includes a pair of abutting portions 32a arranged so as to sandwich both ends of the driven roller 10, and a pair of abutting portions extending in the axial direction of the driven roller 10 inside the intermediate transfer belt 8. The arm part 32b which connects 32a and the spring base 32c formed in the center part of the arm part 32b are provided. As shown in FIG. 3, a hole 32e through which the shaft 10a of the driven roller 10 can be inserted with a margin is formed in the abutting portion 32a, and the shaft 10a does not interfere with the abutting portion 32a. It can move in the direction of the arrow and the opposite direction.

  A pair of left and right lever members 33 that constitute an urging mechanism together with tension springs 35 a and 35 b described later are disposed inside the intermediate transfer belt 8 and near the end of the driven roller 10. The lever member 33 is a kind of lever member, and an input side arm 33c having a force point and an output side arm 33d having an action point are coupled in an L shape and centered on a fulcrum pin 34 disposed at a corner portion. It can be turned. The lever member 33 can have any shape that can provide a lever action. For example, the L-shaped bending angle can be an obtuse angle or an acute angle.

  The lever ratio (L1 / L2) determined by the ratio of the effective lengths of the arms of the lever member 33 is the magnitude of the force required to urge the shaft 10a of the driven roller 10 and the urging force of tension springs 35a and 35b described later. Can be determined in consideration of the size of. That is, by changing the arm length ratio (L1 / L2), the force for urging the shaft 10a of the driven roller 10 can be adjusted.

  The position of the fulcrum pin 34 may be a position overlapping the intermediate transfer belt 8 as shown in FIG. 2 or may be disposed outside the intermediate transfer belt 8. In order to prevent the lever member 33 from projecting to the outside of the intermediate transfer belt 8, the fulcrum pin 34 may be disposed at a position overlapping the intermediate transfer belt 8 as illustrated. In this case, in order to support the fulcrum pin 34, a support member (not shown) is provided extending from the outside of the intermediate transfer belt 8 to the end of the fulcrum pin 34.

  A pair of left and right tension springs 35a and 35b are spanned between a fastening pin 33a provided at the first end of the lever member 33 and a pair of fastening pins 32d disposed on the spring base 32c. ing. The fastening pin 33a serves as a power point of the lever member 33, and the effective length L2 is a vertical distance between the fastening pin 33a and the fulcrum pin 34. The tension springs 35a and 35b, together with the left and right lever members 33, function as urging means that urges both ends of the shaft 10a of the driven roller 10 in a direction away from the end of the shaft of the opposite drive roller 9. . By arranging the roller receiving member 32 and the tension springs 35a and 35b in parallel with the axial direction of the driven roller 10 using the space inside the intermediate transfer belt 8, the intermediate transfer belt device can be downsized. .

  The tension springs 35a and 35b are preferably arranged in parallel to the axial direction of the driven roller 10 to save space, but there is no problem even if they are slightly inclined. The lever member 33 is urged to rotate around the fulcrum pin 34 by the tension springs 35a and 35b. That is, the left lever member 33 in FIG. 2 is urged to rotate counterclockwise (arrow C1 direction) by the tension spring 35, and the right lever member 33 is rotated clockwise (arrow C2 direction) by the tension spring 35b. It is energized. A predetermined tension is generated in the intermediate transfer belt 8 by the rotation bias.

  The second end portion of the lever member 33 is formed with a pressing portion 33b that is in contact with the end portion of the shaft support member. The pressing portion 33b serves as an action point of the lever member 33, and the effective length L1 is a horizontal distance between the pressing portion 33b and the fulcrum pin 34. The pressing portion 33b has a tip formed at an acute angle, and is configured to apply an urging force B in the arrow direction to the end of the shaft support member 31. The shape of the pressing portion 33b may be an arbitrary convex shape, and the acute angle shape shown is merely an example.

  The end portion of the shaft support member 31 that receives the pressing force by the pressing portion 33b is formed so as to extend to the end portion of the shaft of the drive roller 9 on the opposite side to a position substantially side by side with the fulcrum pin 34 in FIG. ing. By forming the shaft support member 31 in such a shape, the urging force from the lever member 33 can be efficiently received.

  The driven roller 10 includes a cylindrical main body 10b and a pair of left and right detent flange portions 10c that are press-fitted into both ends of the main body 10b. The diameter of the detent flange portion 10c is formed to be slightly larger than the diameter of the main body 10b, and when the intermediate transfer belt 8 moves to one side, the edge of the belt 8 comes into contact with the side surface of the detent flange portion 10c. ing. The side surface of the offset flange portion 10c is processed smoothly to prevent the intermediate transfer belt 8 from being worn.

  A small-diameter end portion 10d of the driven roller 10 protrudes short outside the pair of left and right offset flange portions 10c. A pair of left and right abutting portions 32a of the roller receiving member 32 is positioned outside the small diameter end portion 10d, and the intermediate transfer belt 8 is not offset between the small diameter end portion 10d and the abutting portion 32a. A minute gap is formed.

  The size of the gap is made as small as possible so as not to affect the accuracy of the image formed on the intermediate transfer belt 8. When the intermediate transfer belt 8 moves to the one side, the detent flange portion 10c is pushed at the edge of the belt 8 to move the driven roller 10 in the axial direction, whereby the small-diameter end portion 10d of the driven roller 10 receives the roller. The inner surface of the abutting portion 32a of the member 32 is pressed.

  In the intermediate transfer belt device configured as described above, the tension forces T of the tension springs 35a and 35b are balanced on the left and right as shown in FIG. 2 in a neutral state where the intermediate transfer belt 8 is not offset. For this reason, the left and right lever members 33 are urged to rotate with equal force by the tensile force T, and the left and right shaft support members 31 are pressed in the direction of the arrow with equal force by the pressing portions 33 b of the left and right lever members 33.

  For this reason, equal tension is applied to the intermediate transfer belt 8 on the left and right, and the intermediate transfer belt 8 travels without any deviation. In this state, a slight gap is formed between the edge of the intermediate transfer belt 8 and the left and right offset flange portions 10c. The gap is for avoiding friction between the edge of the intermediate transfer belt 8 and the detent flange portion 10c, and is not necessarily formed.

  Next, a correction operation when the deviation occurs in the intermediate transfer belt 8 will be described with reference to FIGS. 4A and 4B. First, consider a case where the intermediate transfer belt 8 is displaced in the right direction, that is, in the direction of the arrow A1, as shown in FIG. 4A. In this case, the right edge portion of the belt 8 contacts the side surface of the right offset flange portion 10c. For this reason, the driven roller 10 moves in the direction of arrow A <b> 1 so as to be pushed by the belt 8.

  When the driven roller 10 moves in the direction of the arrow A1, the small diameter end portion 10d on the right side comes into contact with the abutting portion 32a of the roller receiving member 32, and the roller receiving member 32 is moved in the arrow A1 direction. By the movement of the roller receiving member 32, the tensile force T of the right tension spring 35b is weakened to T2 (T2 <T), and the rotational biasing force of the right lever member 33 in the direction of arrow C2 is weakened. For this reason, the biasing force B in the arrow direction of the right shaft support member 31 is weakened, and the right tension of the intermediate transfer belt 8 is weakened.

  On the other hand, due to the movement of the roller receiving member in the direction of arrow A1, the tensile force T of the left tension spring 35a is increased to T1 (T <T1), and the left lever member 33 is turned in the direction of arrow C1. Power is strengthened. For this reason, the biasing force B in the arrow direction of the left shaft support member 31 is increased, and the tension on the left side of the intermediate transfer belt 8 is increased.

  As described above, the tension of the intermediate transfer belt 8 is weak on the right side and strong on the left side. Due to the magnitude relationship between the left and right tensions, the intermediate transfer belt 8 moves in the left direction where the tension is strong (the direction opposite to A1). The rightward misalignment of the intermediate transfer belt 8 is corrected.

  Next, when the intermediate transfer belt 8 is shifted to the left, that is, in the direction of the arrow A2 as shown in FIG. 4B, the left edge of the belt 8 contacts the side surface of the left offset flange portion 10c. For this reason, the driven roller 10 moves in the direction of arrow A <b> 2 so as to be pushed by the belt 8.

  When the driven roller 10 moves in the arrow A2 direction, the left small diameter end portion 10d abuts against the abutting portion 32a of the roller receiving member 32, and the roller receiving member 32 is moved in the arrow A2 direction. By the movement of the roller receiving member 32, the tensile force T of the left tension spring 35a is weakened to T3 (T3 <T), and the rotation biasing force of the left lever member 33 in the direction of arrow C1 is weakened. For this reason, the biasing force B in the arrow direction of the left shaft support member 31 is weakened, and the tension on the left side of the intermediate transfer belt 8 is weakened.

  On the other hand, due to the movement of the roller receiving member in the direction of arrow A2, the tensile force T of the right tension spring 35b is increased to T4 (T <T4), and the right lever member 33 is turned in the direction of arrow C2. Power is strengthened. For this reason, the urging force B in the arrow direction of the right shaft support member 31 is increased, and the right tension of the intermediate transfer belt 8 is increased.

  As described above, the tension of the intermediate transfer belt 8 is weak on the left side and strong on the right side, and the intermediate transfer belt 8 moves in the right direction (the direction opposite to A2) with a strong tension due to the magnitude relationship between the left and right tensions. The deviation in the left direction of the intermediate transfer belt 8 is corrected.

  As described above, the offset correction of the intermediate transfer belt 8 uses the characteristic that the belt 8 moves to the higher tension side. However, in order to stabilize the running of the intermediate transfer belt 8, the belt tension is corrected. It is important to reduce the difference between left and right. In this respect, in this embodiment, the left and right tension springs 35a and 35b are fixed to the common spring base 32c to enhance the response of the deviation correction. In other words, when the belt 8 is offset, the tensile force of the left and right tension springs 35a and 35b increases on one side and decreases on the opposite side, so that the belt tension magnitude relationship for offset correction is generated quickly. ing. For this reason, stable belt running can be realized.

  In the embodiment of the present invention, the straight line connecting the fastening pins 32d and 33a at both ends of the tension spring 35a and the straight line connecting the fastening pins 32d and 33a at both ends of the tension spring 35b are respectively axis lines of the driven roller 10. And can be parallel. This makes it possible to dispose a tension spring having a small spring constant and a long overall length by effectively utilizing the width (axial length) of the driven roller 10. It is desirable to align the left and right straight lines connecting the fastening pins 32d and 33a to one straight line, but it is not always necessary to align the straight lines with strict accuracy, and the steps are arranged in a range that does not substantially affect the urging force. May be. It is possible to use a compression spring instead of a tension spring as the biasing means. However, the tension spring can have a smaller wire diameter and a smaller spring constant than the compression spring. Therefore, by using the tension springs 35a and 35b, the difference in belt tension between the left and right can be reduced, and more stable belt running can be realized.

  Further, the force of the tension spring used for the biasing means for biasing the driven roller 10 is generally given a tolerance of about 15%. However, in the embodiment of the present invention, since the spring base 32c is movable, it is possible to run the intermediate transfer belt 8 where the tensile forces of the tension springs 35a and 35b are naturally balanced. Therefore, it is not necessary to apply extra force to the shaft 10a of the driven roller 10 or the end of the intermediate transfer belt 8, and the life of the belt 8 can be extended. Therefore, the running cost of the intermediate transfer belt device can be reduced.

(Belt deviation correction mechanism according to the second embodiment)
Next, a belt deviation correcting mechanism 50 according to the second embodiment will be described with reference to FIG. FIG. 5 is a plan view of the end of the intermediate transfer belt 8 on the driven roller 10 side as seen from above, as in FIG.

  Similar to the correction mechanism 30 in FIG. 2, the correction mechanism 50 in FIG. 5 includes a pair of left and right detent flange portions 10 c press-fitted into both ends of the main body 10 b of the driven roller 10, an L-shaped lever member 53, Spring 35a, 35b is provided. The lever member 53 has an input side arm 53c having a power point and an output side arm 53d having an action point, and is rotatable about a fulcrum pin 54 disposed at a corner.

  One ends of the tension springs 35a and 35b are fixed to the fixing pin 53a of the input side arm 53c of the lever member 53. The other end on the opposite side of the tension springs 35 a and 35 b is fixed to a fastening pin 52 d provided on the machine frame of the apparatus main body 100. Thus, in this 2nd Embodiment, since the roller receiving member 32 of 1st Embodiment is not used, the number of parts is reduced by that much and it is simplified mechanically.

  The tension springs 35a and 35b are preferably arranged in parallel to the axial direction of the driven roller 10 to save space, but there is no problem even if they are slightly inclined. The lever member 53 is urged to rotate around the fulcrum pin 54 by the tension springs 35a and 35b. That is, the left lever member 53 in FIG. 5 is urged to rotate counterclockwise (arrow C1 direction) by the tension spring 35a, and the right lever member 53 is rotated clockwise (arrow C2 direction) by the tension spring 35b. It is energized.

  The output side arm 53d of the lever member 53 extends at a right angle to the side of the intermediate transfer belt 8, and a pressing surface 53b parallel to the shaft 10a of the driven roller 10 is formed on its side surface. The pressing surface 53b is finished smoothly, and a pressure receiving roller 55 provided on the shaft support member 51 as a pressed portion to be described later can be moved smoothly along the pressing surface 53b.

  On the other hand, both ends of the shaft 10 a of the driven roller 10 are rotatably supported by bearings 49. The driven roller 10 and the bearing 49 can move in the axial direction as a unit. A shaft support member 51 is integrally connected to the bearing 49. The shaft support member 51 can be composed of, for example, a bar member or a plate member that extends toward the opposite drive roller 9.

  A support shaft 51 a extending in a direction perpendicular to the intermediate transfer belt 8 is disposed at the end of the shaft support member 51 opposite to the bearing 49, that is, the end of the drive roller 9. And the pressure receiving roller 55 which contact | abutted to the press surface 53b of the lever member 53 is rotatably attached to this spindle 51a. Thereby, the rotational biasing force of the lever member 53 by the tension springs 35 a and 35 b is transmitted to the shaft support member 51 as the biasing force B via the pressure receiving roller 55.

  Here, the tensile force of the tension springs 35a and 35b is T, the horizontal distance from the fulcrum pin 54 of the lever member 53 to the contact portion of the pressure receiving roller 55 is L1, and the vertical distance from the fulcrum pin 54 to the fastening pin 53a is L2. Then, an urging force B having a size of (L2 / L1) × T acts on the left and right shaft support members 51. A predetermined tension is generated on the intermediate transfer belt 8 by the urging force B. The tension of the intermediate transfer belt 8 is automatically adjusted when the pressure receiving roller 55 moves and the lever ratio (L2 / L1) changes. That is, the biasing force adjusting means is configured by the lever member 53 and the pressure receiving roller 55 of the shaft support member 51.

  Next, the correction action when the deviation occurs in the intermediate transfer belt 8 will be described with reference to FIGS. 6A and 6B. First, consider a case where the intermediate transfer belt 8 is displaced in the right direction, that is, in the direction of the arrow A1, as shown in FIG. 6A. In this case, the right edge portion of the belt 8 contacts the side surface of the right offset flange portion 10c. For this reason, the driven roller 10 moves in the direction of arrow A <b> 1 so as to be pushed by the belt 8.

  When the driven roller 10 moves in the direction of the arrow A1, the left and right shaft support members 51 move in the direction of the arrow A1 together with the driven roller 10. Due to the movement of the shaft support member 51 in the direction of arrow A1, the contact position of the pressure receiving roller 55 on the pressing surface 53b of the lever member 53 changes, and the left lever member 53 shortens L1 to L1a, and the right lever member At 53, L1 becomes longer and becomes L1b. Accordingly, the urging force B acting on the shaft support member 51 and the bearing 49 increases to B1 on the left side (B <B1) and decreases to B2 on the right side (B2 <B).

  As a result, the tension of the intermediate transfer belt 8 is in a tension relationship where the left side is strong and the right side is weak. Due to the relative magnitude relationship of the left and right tensions, the intermediate transfer belt 8 is in the left direction (the direction opposite to A1) where the tension is strong. The intermediate transfer belt 8 is moved and the deviation in the right direction of the intermediate transfer belt 8 is corrected.

  Next, when the intermediate transfer belt 8 is shifted to the left, that is, in the direction of the arrow A2, as shown in FIG. 6B, the left edge of the belt 8 contacts the side surface of the left detent flange portion 10c. For this reason, the driven roller 10 moves in the direction of arrow A <b> 2 so as to be pushed by the belt 8.

  When the driven roller 10 moves in the arrow A2 direction, the left and right shaft support members 51 move in the arrow A2 direction together with the driven roller 10. By the movement of the shaft support member 51 in the direction of arrow A2, the contact position of the pressure receiving roller 55 on the pressing surface 53b of the lever member 53 is changed, and the left lever member 53 becomes longer L1 and becomes L1c. At 53, L1 is shortened to L1d. Accordingly, the urging force B acting on the shaft support member 51 and the bearing 49 decreases to B3 on the left side (B3 <B) and increases to B4 on the right side (B <B4).

  In this way, the tension of the intermediate transfer belt 8 is weak on the left side and strong on the right side, and the intermediate transfer belt 8 has a strong rightward direction (the direction opposite to A2) due to the relative magnitude relationship of the left and right tensions. , And the leftward deviation of the intermediate transfer belt 8 is corrected.

  In the second embodiment as well, the right and left pivotal support members 51 are moved simultaneously by the shift of the belt 8 and the belt tension magnitude relationship for the correction of the shift is generated quickly. Driving can be realized. Further, by using the tension springs 35a and 35b having a small spring constant and a long overall length, the left-right difference in belt tension can be reduced, and more stable belt running can be realized.

  Further, it is possible to run the intermediate transfer belt 8 where the tensile force of the tension springs 35a and 35b is naturally balanced by the movement position of the shaft support member 51 and the pressure receiving roller 55. For this reason, a typical tolerance of about 15% of the tension spring is unnecessary, and it is not necessary to apply an extra force to the shaft 10a of the driven roller 10 or the end of the intermediate transfer belt 8. Therefore, it is possible to extend the life of the belt 8 and reduce the running cost of the intermediate transfer belt device.

  Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment and can be variously modified. For example, in addition to the intermediate transfer belt 8, the belt device of the present invention can be applied to a fixing belt as a fixing member, a photosensitive belt as a photosensitive member, and the like.

  As shown in FIG. 7, it is also possible to connect the left and right tension springs 35a and 35b to form one tension spring 35c. As a result, the number of parts can be reduced, as well as the use of a tension spring with a small spring constant and a long overall length, and the difference in left and right belt tension can be reduced. Can be realized.

  Further, as the urging means, it is possible to use a compression spring instead of a tension spring. As shown in FIG. 8, for example, the compression spring includes a pair of left and right lever members 33 and a pair of left and right pivot support members 31. In between, it can arrange | position as compression spring 36a, 36b. In this case, the roller receiving member 32 and the lever member 33 have, for example, an engagement structure of a pin 37 provided in the roller receiving member 32 and a long hole 38 provided in the lever member 33, and the roller receiving member 32 in the direction of the arrow A. The movement is converted into rotation about the fulcrum pin 34 of the lever member 33 without using a spring.

  Further, in the modified embodiment of FIG. 7, the input side arm 53 c is disposed on the opposite side of 180 ° with the fulcrum pin 54 as the center, and one input side arm 53 c disposed on the opposite side in this way is provided with one piece. It is also possible to arrange a compression spring.

  Further, as shown in FIG. 9, the left and right tension springs 35 a and 35 b are connected to form one tension spring 35 c, and the input side arm 33 c and the roller receiving member 32 of the left or right lever member 33 are protruded from the recess material 60. The member 61 may be configured to be engaged in the axial direction. By using one tension spring 35c, the number of parts can be reduced, and the difference in right and left belt tension can be reduced, so that stable belt running can be realized.

  As shown in FIG. 10A, the concave member 60 and the convex member 61 are located in the middle of the concave member 60 when the intermediate transfer belt 8 is running without any deviation. When the intermediate transfer belt 8 is moving to the right or left, the convex member 61 contacts either the left or right side of the inner surface of the concave member 60 as shown in FIG.

  When the convex member 61 contacts the right inner surface of the concave member 60 as shown in FIG. 10B, the rotational biasing force of the lever member 33 is weakened, and the inner left side of the concave member 60 as shown in FIG. 10C. When abutting against the side surface, the rotational biasing force of the lever member 33 is strengthened. Thereby, it is possible to realize the deviation correction of the intermediate transfer belt 8 as in the above-described embodiment. That is, the concave member 60 and the convex member 61 constitute an urging force adjusting means.

  Either one or both of the concave member 60 and the convex member 61 can be formed of an elastic member. It is also possible to interpose an elastic member between the concave member 60 and the convex member 61. Thereby, the offset correction of the intermediate transfer belt 8 can be performed more smoothly.

1Y, 1M, 1C, 1Bk: process unit 2: photoconductor 3: charging roller 4: developing device 5: cleaning device 6: exposure device 7: transfer device 8: intermediate transfer belt 9: driving roller 10: driven roller 10c: flange Section 11: Primary transfer roller 12: Secondary transfer roller 13: Belt cleaning device 14: Waste toner container 15: Paper feed cassette 16: Paper feed roller 17: Paper discharge roller 18: Paper discharge tray 19: Timing roller 20: Fixing Device 30: Deviation correction mechanism 31, 51: Shaft support member 32: Roller receiving member 33, 53: Lever members 35a, 35b, 35c: Tension spring (elastic member)
36a, 36b: compression spring (elastic member)
49: Bearing 55: Pressure receiving roller

Japanese Patent No. 4590215 Japanese Patent No. 3919589

Claims (14)

In order to correct the deviation in the width direction of the endless belt spanned between a plurality of rollers, a deviation correction mechanism mounted on at least one roller, the deviation correction mechanism,
A pair of shaft supporting members that support both ends of the shaft of the roller and can be moved individually in a direction to increase or decrease the tension of the belt while allowing the roller to move in the axial direction;
An urging mechanism for urging the pair of shaft support members in a direction to increase the tension of the belt;
A pair of flange portions formed at both ends of the roller and abutted against the edge of the belt moved to the offset;
Due to the movement of the roller in the axial direction caused by the movement of the belt in the offset direction, the other shaft support portion on the opposite side to the moving direction with respect to the biasing force of the biasing mechanism with respect to one shaft supporting member in the moving direction And an urging force adjusting means for relatively increasing the urging force of the urging mechanism against the material.   2. The deviation correction mechanism according to claim 1, wherein the urging mechanism is disposed inside the endless belt. The urging force adjusting means is disposed on the side of the roller and is movable in the axial direction of the roller, and when the roller moves in the axial direction by contacting the belt with the flange portion, A roller receiving member that engages and moves in the same direction as the roller;
The biasing mechanism includes an elastic member having one end connected to the roller receiving member, an input side arm connected to the other end of the elastic member, and an output side arm connected to the shaft support member. And a lever member that transmits an urging force of the elastic member to the shaft support member according to a lever ratio determined by a ratio of an effective length of the arm on the output side,
The piece according to claim 1 or 2, wherein the biasing force of the elastic member is changed by moving the roller receiving member by the movement of the roller in the axial direction caused by the deviation of the belt. Shift correction mechanism.   4. The deviation correction mechanism according to claim 3, wherein the roller receiving member is disposed inside the endless belt.   5. The deviation correction mechanism according to claim 4, wherein the elastic member is a tension spring, and the tension spring is disposed between the roller receiving member and the lever member.   6. The offset correction mechanism according to claim 5, wherein the tension spring is disposed in parallel with the axis of the roller.   2. The offset correction mechanism according to claim 1, wherein the elastic member constituting the biasing mechanism is a compression spring. The biasing mechanism has an input side arm connected to the elastic member and an output side arm connected to the shaft support member, according to a lever ratio determined by a ratio of effective lengths of the input side and output side arms. A lever member that transmits the urging force of the elastic member to the shaft support member;
3. The deviation correction mechanism according to claim 1, wherein the lever ratio of the lever member is changed by the axial movement of the roller caused by the movement of the belt.   The output side arm of the lever member has a pressing surface extending in parallel with the axis of the roller, and the pressed portion of the shaft support member is movably in contact with the pressing surface. Offset correction mechanism.   The deviation correction mechanism according to claim 8 or 9, wherein the elastic member is a tension spring.   11. The offset correction mechanism according to claim 10, wherein the tension spring is disposed in parallel with the axis of the roller.   A belt device comprising the deviation correction mechanism according to claim 1.   13. A transfer belt device, wherein an image is transferred onto the belt of the belt device according to claim 12.   An image forming apparatus comprising the transfer belt device according to claim 13.

Images