JP2008129494A - Belt conveyance device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a belt conveyance device which has long service life by correcting meandering of a belt, without producing stress in the peripheral part of the belt, and to provide an image forming apparatus provided with the belt conveyance device. <P>SOLUTION: In the belt conveyance device, when the belt rotated and driven by a plurality of rollers is moved in a meandering manner, a roller is moved according to the movement of the belt by a roller supporting section movably supporting the roller. The movement of the roller can be assisted via the roller supporting section by an auxiliary mechanism provided in the roller supporting section supporting the roller. Consequently, meandering of the belt can be corrected without producing the stress in the peripheral part of the belt, so that cracking of the belt can be prevented and a long-life belt conveyance device can be provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  In recent years, color copiers have been developed in response to office color orientation. One of these color copying machines is a quadruple tandem system. In this method, four photosensitive drums that are image carriers are arranged in parallel, and toner images are formed on the respective photosensitive drums using yellow, magenta, cyan, and black toners. This is a method of obtaining a color image by sequentially transferring to a recording medium conveyed by running of the belt.

  In color copiers, color misregistration of each color greatly affects image quality. One of the causes of this color misregistration is the effect of endless belt meandering. In order to prevent the endless belt from meandering, a regulating plate is arranged in parallel with the end of the endless belt driving roller or idle roller, and when the endless belt is driven, the peripheral edge is slid onto the plate surface of the regulating plate. Thus, meandering is regulated (see, for example, Patent Document 1).

JP 11-202591 A

  However, in the belt conveying device of the conventional image forming apparatus as in Patent Document 1, since the meandering of the belt is regulated by the regulating plate, if the belt meandering force increases, the pressing force of the belt against the regulating plate increases. However, there was a problem that the belt cracked and the belt was cut.

  SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a belt conveying device that corrects the meandering of a belt without generating stress at the belt peripheral portion and has a long life. It is another object of the present invention to provide an image forming apparatus having such a belt conveyance device.

  The belt conveying device of the present invention is provided on at least one of the plurality of rollers, a belt stretched by the rollers and driven to rotate by rotation of the rollers, and the belt. It has a roller support part that supports the roller so that it can move in response to rotational driving, and an auxiliary mechanism that is provided on the roller support part and assists the movement of the roller.

  According to the belt conveyance device of the present invention, when the belt that is rotationally driven by the plurality of rollers moves so as to meander, the roller moves in accordance with the movement of the belt by the roller support portion that supports the rollers movably, Further, the movement of the roller is assisted through the roller support portion by an auxiliary mechanism provided in the roller support portion. As a result, the meandering of the belt can be corrected without generating stress in the belt peripheral portion.

  An image forming apparatus of the present invention is an image forming apparatus that forms an image on a recording medium, and includes the belt conveying device described above and an image forming unit that forms an image on the recording medium conveyed by the belt conveying device. It is characterized by having.

  According to the image forming apparatus of the present invention, the meandering of the belt can be corrected by providing the above-described belt conveying device. With this belt conveying device, the recording medium can be conveyed to the image forming unit without displacement, and an image without color misregistration can be formed.

  In the present invention, when a belt that is rotationally driven by a plurality of rollers moves in a meandering manner, the roller is moved according to the movement of the belt by a roller support portion that supports the rollers so as to be movable. The movement of the roller can be assisted through the roller support portion by an auxiliary mechanism provided in the roller support portion that supports the roller. Therefore, the meandering of the belt can be corrected without generating stress at the belt peripheral edge. Thereby, the crack to a belt can be prevented and a long-life belt conveyance apparatus can be provided.

  The image forming apparatus of the present invention forms an image on a recording medium conveyed by a belt conveying device by an image forming unit. At this time, the belt conveyance device provided in the image forming apparatus has a structure which will be described later, and is a belt conveyance device capable of correcting the meandering of the belt without generating stress in the belt peripheral portion.

  First, the configuration of the image forming apparatus and the operation during printing will be described in detail. FIG. 1 is a schematic view of an image forming apparatus of the present invention. As shown in FIG. 1, the image forming apparatus of the present invention includes a paper tray 100, a paper feeding unit 200, a paper conveying unit 300, a toner image forming unit 430 as an image forming unit, and a belt conveying device to be described later. A transfer unit 460 and a fixing unit 500 are provided.

  As shown in FIG. 1, the paper tray 100 of the image forming apparatus is detachably attached to the image forming apparatus, and sheets 101 as recording media are stacked therein. Inside the paper tray 100, a paper stacking plate 102 is rotatably disposed on a support shaft (not shown), and the paper 101 is stacked on the paper stacking plate 102. Further, the paper tray 100 is provided with a guide member (not shown) that regulates the stacking position of the paper 101, and the position of the side surface of the paper 101 in the direction orthogonal to the feeding direction of the paper 101 (the right direction in FIG. 1). And the stacking position of the paper 101 with respect to the feeding direction of the paper 101 are regulated to be constant.

  A lift-up lever 103 is rotatably disposed on a support shaft (not shown) on the feeding side of the paper tray 100, and the support shaft is engaged with the motor 104 so as to be able to contact and separate. When the paper tray 100 is inserted into the image forming apparatus, the lift-up lever 103 and the motor 104 are engaged, and a control unit (not shown) drives the motor 104. As the lift-up lever 103 rotates, the tip of the lift-up lever 103 lifts the bottom of the paper stacking plate 102, and the paper 101 stacked on the paper stacking plate 102 rises. Then, when the paper 101 rises to a certain height, the rise detection unit 201 detects it, and the control unit stops the motor 104 based on the information detected by the rise detection unit 201.

  On the feeding side of the sheet tray 100, a sheet feeding unit 200 that feeds the sheets 101 one by one from the top is disposed. The paper feeding unit 200 includes a pickup roller 202 disposed so as to be in pressure contact with the paper 101 raised to a desired height, a feed roller 203 that separates the paper 101 fed by the pickup roller 202 one by one, and A roller pair including the retard roller 204 is provided. The paper feeding unit 200 includes a paper presence / absence detection unit 205 that detects the presence / absence of the paper 101 and a paper remaining amount detection unit 206 that detects the remaining amount of the paper 101.

  The paper 101 that has been fed out by the paper feed unit 200 is sent to the paper transport unit 300. The fed paper 101 passes through the paper sensor 301 and is sent to the conveyance roller pair 302. The conveyance roller pair 302 is driven by a drive unit (not shown) controlled by the control unit at a predetermined timing after the paper sensor 301 detects the paper 101 and sends out the paper 101. At this time, by keeping the rotation of the conveying roller pair 302 stopped for a predetermined time after the sheet sensor 301 detects the sheet 101, the sheet 101 is pushed into the pressure contact portion of the conveying roller pair 302, and the sheet 101 is skewed. It will be corrected.

  The paper 101 sent out from the transport roller pair 302 passes through the paper sensor 303 and is sent to the transport roller pair 304. The conveyance roller pair 304 is rotated by a driving unit (not shown) from the time when it passes through the paper sensor 303 and sends out the paper 101 without stopping. The sheet 101 sent out by the conveyance roller pair 304 passes through the writing sensor 305 and is sent to the image forming unit 400.

  The toner image forming unit 430 includes an OPC (Organic Photo Conductor) drum 431 that carries a toner image, a charging roller 432 that charges the surface of the OPC drum 431, and an LED that forms an electrostatic latent image on the surface of the charged OPC drum 431 ( The exposure head 433 includes a light emitting diode (Light Emitting Diode) array, a developing roller 434 that forms a toner image on the electrostatic latent image by frictional charging, and a toner supply unit 436 that supplies toner.

  The transfer unit 460 is rotated by a belt 461 that is an endless belt that electrostatically attracts and conveys the paper 101 and is rotated by a drive unit (not shown), and forms a pair with the drive roller 462 and the drive roller 462 that drive the belt 461. On the transfer roller 464 and the belt 461 which are arranged so as to face the toner image forming unit 430 and to be in pressure contact with the OPC drum 431 and to apply a voltage so as to transfer the toner image onto the paper 101. A cleaning blade 465 for scraping and cleaning the adhering toner and a toner box 466 for depositing the toner scraped off by the cleaning blade 465 are provided.

  The toner image forming unit 430 and the belt 461 are driven in synchronization, and the toner images are sequentially superimposed and transferred onto the sheet 101 electrostatically attracted to the belt 461. The sheet 101 on which the image is transferred by the transfer unit 460 is sent to the fixing unit 500 that fixes the toner image to the sheet 101 with heat and pressure.

  The fixing unit 500 includes a halogen lamp 503 serving as a heat source therein, and includes a roller pair including an upper roller 501 and a lower roller 502 whose surfaces are formed of an elastic body. Heat and pressure are applied to the toner image on the paper 101 sent out from the image forming unit 400 to melt the toner image and fix it on the paper 101. Then, the sheet 101 is discharged to the stacker unit 505 by the discharge roller pair 504.

  Such an image forming apparatus of the present invention is equipped with the belt conveying device shown in the following first to fourth embodiments. Hereinafter, a belt conveyance device mounted on the above-described image forming apparatus of the present invention will be described with reference to the drawings.

[Embodiment 1]
FIG. 2 is a top view of the belt conveyance device according to the first embodiment of the present invention, and FIG. 3 is a side view of the belt conveyance device according to the first embodiment of the present invention.

  As shown in FIGS. 2 and 3, the belt conveyance device of the transfer unit 460 is rotatably supported by a belt frame 471 and has a high-friction drive roller 462 having a gear 470 fixedly locked at its end. It has an idle roller 463 or the like whose end is rotatably supported by a bearing 472. The bearing 472 is slidably supported in a hole 473 b of an arm 473 that is rotatably supported by the belt frame 471, and the idle roller 463 is biased in a direction away from the drive roller 462 by a spring 469. A belt 461 is stretched around the drive roller 462 and the idle roller 463, and the drive roller 462 is rotated by a drive unit (not shown), so that the belt 461 travels in the direction of arrow a in FIG.

  A pulley 467 is disposed at one end of the idle roller 463 so as to be rotatable on the rotation shaft O2 and fixed in the axial direction. The pulley 467 is attached to the inner periphery of one end of the belt 461 as a meandering correction material. When the bead 468 is engaged with the groove of the pulley 467, the belt 461 is restricted from moving in the direction orthogonal to the arrow a direction in FIG.

  The belt 461 is made of, for example, an elastic resin such as polyimide or urethane, and is centrifugally molded. The bead 468 is made of, for example, urethane rubber, and is affixed to the belt 461 with a double-sided adhesive tape, an adhesive, or the like. The belt 461 and the bead 468 mentioned here are examples, and are not limited to these.

  An arm 473 as a roller support member is rotatably supported by the rotation shaft 473a on the belt frame 471 on the end side of the rotation shaft O2 of the idle roller 463, and rotates about the rotation shaft 473a. A bearing 472 is slidably disposed on the arm 473 and supports the idle roller 463 so as to be movable.

  Between the arm 473 and the pulley 467, a tilting lever 474 as a roller moving portion having a rotating shaft 474a inclined with respect to the rotating shaft O1 of the drive roller 462 is disposed. 4A and 4B are three views of the tilt lever according to the first embodiment of the present invention. FIG. 4A is a top view of the tilt lever, FIG. 4B is a side view of the tilt lever, and FIG. 4C is a front view of the tilt lever. FIG. 5 is a perspective view of the tilt lever according to Embodiment 1 of the present invention.

  As shown in FIGS. 4 and 5, the tilt lever 474 has a rotation shaft 474a that is skewed by an angle θ with respect to the rotation shaft O1 of the drive roller 462. The elliptic shaft hole 474b has a rotation shaft of the idle roller 463. The convex portion 474 c is disposed so that O 2 is rotatably and slidably penetrated and is in contact with the pulley 467.

  Since the tilting lever 474 has a tilted rotating shaft 474a, when the tilting lever 474 rotates, the tilting lever 474 rotates with a locus 474d as shown in FIG. 4B. Therefore, when the shaft end portion of the idle roller 463 is inclined downward in FIG. 1, the tilting lever 474 is rotated downward and in the direction approaching the idle roller 463, and operates to push the pulley 467.

  Similarly, when the shaft end of the idle roller 463 is tilted upward, the tilt lever 474 is also rotated upward and away from the idle roller 463. Then, when the tilting lever 474 rotates around the rotation shaft 474a, the posture of the tilting lever 474 is continuously changed as shown in FIG.

As shown in FIG. 3, the arm 473 that supports the idle roller 463 is provided with a spring 490 as an auxiliary mechanism in the vicinity of the lower portion of the bearing 472 so as to generate an urging force Fs upward in FIG. ing. For example, if the density of the metal shaft of the idle roller 463 is 7.85 × 10 ⁻³ g / mm, the diameter of the shaft is φ8 mm, and the length is 322 mm, the spring 490 of the arm 473 is caused by the dead weight of the idle roller 463. A force Fi of 100 g is applied in the downward direction at the position where is attached.

  The spring 490 generates the largest urging force Fs in the upward direction when the arm 473 moves most downward, and the urging force Fs decreases as the arm 473 moves upward. When the arm 473 moves most upward, the urging force is minimized.

  Further, when the spring 490 is compressed to the maximum by the downward tilt due to the weight of the idle roller 463 as described later, for example, the spring 490 cancels the downward force Fi of 100 g due to the weight of the idle roller 463. An urging force Fs in the direction is generated. That is, the force Fi is canceled by the biasing force Fs of the spring 490.

  In the first embodiment, the spring 490 provided on the arm 473 is configured such that the urging force Fs of the spring 490 acts upward even when the arm 473 moves most upward. This is because when the urging force of the spring 490 moves downward, that is, when the urging force that pulls the arm 473 acts, when the arm 473 moves to the uppermost position, the idle roller 463 tilts upward. This is because a considerable load is applied. Therefore, in the first embodiment, in the tilting range of the idle roller 463, a relationship (Fi ≧ Fs) is established in which the biasing force Fs of the spring 490 is equal to or less than the force Fi applied downward to the arm 473 due to the weight of the idle roller. It is like that. In addition, since Fi ≧ Fs holds in the tilting range of the idle roller 463, the idle roller 463 can tilt downward due to its own weight or the like when, for example, the axial thrust force by the belt 461 is not applied.

  Next, the operation of the above-described belt conveyance device will be described.

  The belt 461 meanders during traveling, for example, as described with reference to FIGS. 7 and 8, depending on the parallelism between the drive roller 462 and the idle roller 463. As shown in FIG. 7, when the end of the right shaft of the idle roller 463 is twisted upward, the belt 461 meanders in the direction of the arrow b perpendicular to the direction of the arrow a in FIG.

  On the other hand, when the end of the shaft on the right side of the idle roller 463 is twisted downward, the belt 461 meanders in the direction of arrow c perpendicular to the direction of arrow a in FIG. At this time, as can be seen from FIGS. 7 and 8, the belt 461 meanders in proportion to the amount of twist between the drive roller 462 and the idle roller 463.

  In addition to the meandering of the belt 461 caused by the parallelism of the drive roller 462 and the idle roller 463, for example, the tension of the belt 461 is uneven, the difference in the circumferential length of the belt 461, the drive roller 462 that stretches the belt 461, The belt 461 meanders due to the influence of the cylindricity of the idle roller 463.

  The belt conveyance device of the present invention can correct meandering without generating stress at the peripheral edge of the belt 461. Hereinafter, a detailed description will be given with reference to FIGS.

  For example, as shown in FIG. 9, when the belt 461 is shifted to the right side with respect to the idle roller 463, the bead 468 is positioned on the right side, so that the pulley 467 follows the bead 468 disposed on the belt 461. Located in. At this time, the arm 473 moves downward as shown in FIG. 9 by the force Fi caused by the weight of the idle roller 463. The tilt lever 474 rotates around the rotation shaft 474 a by the force Fi caused by the weight of the idle roller 463, and the tilt lever 474 moves in a direction approaching the pulley 467. Then, the convex portion 474c on the upper side of the tilt lever 474 comes into contact with the pulley 467, and the tilt of the idle roller 463 is stopped.

  At this time, when the drive roller 462 (not shown) rotates and the belt 461 travels, the belt 461 meanders in the direction of arrow C in FIG. 9 as described above. Then, the belt 461 is pushed by the bead 468 along with the meandering of the belt 461, and the pulley 467 moves in the direction of arrow C in FIG.

  Then, the tilting lever 474 that is in contact with the pulley 467 at the convex portion 474c is pushed by the pulley 467 by the movement of the pulley 467 in the direction of arrow C, and rotates around the tilted rotating shaft 474a, so that the arm 473 is moved upward. Move in the direction.

  As shown in FIG. 9, when the idle roller 463 is tilted downward, the spring 490 is compressed to the maximum by the arm 473 that supports the idle roller 463. By this compression, the spring 490 generates, for example, an upward biasing force Fs that cancels, for example, a downward force Fi of 100 g applied to the arm 473 by the weight of the idle roller 463. By this urging force Fs, the idle roller 463 is pulled upward via the arm 473.

  Therefore, in the belt conveyance device described in the first embodiment, the downward tilt of the idle roller 463 is stopped by the tilt lever 474, and the idle roller 463 tilts upward by the meandering of the belt 461 in the arrow C direction. In this case, the idle roller 463 can be moved upward with a smaller thrust force (force acting in the meandering direction) than when the spring 490 is not provided. Thereby, the followability of the tilting of the idle roller 463 with respect to the meandering of the belt 461 is improved.

  As described above, when the arm 473 moves upward, the rotation axis O2 of the idle roller 463 becomes substantially parallel to the rotation axis O1 of the drive roller 462 as shown in FIG. 10, and the meandering of the belt 461 is corrected. Run stably.

  Further, for example, as shown in FIG. 11, when the belt 461 is moved to the left side with respect to the idle roller 463, the bead 468 is positioned on the left side, so that the pulley 467 follows the bead 468 disposed on the belt 461. Located on the side. At this time, the tilting lever 474 that is in contact with the pulley 467 by the convex portion 474c is pushed by the pulley 467, rotates around the tilted rotating shaft 474a, and moves the arm 473 upward. That is, the idle roller 463 tilts upward, the lower convex portion 474c of the tilt lever 474 contacts the pulley 467, and the tilt of the idle roller 463 is stopped.

  At this time, when the drive roller 462 (not shown) rotates and the belt 461 travels, the belt 461 meanders in the direction of arrow B in FIG. 11 as described above. Then, the belt 461 is pushed by the bead 468 along with the meandering of the belt 461, and the pulley 467 moves in the arrow B direction in FIG.

  Then, the tilting lever 474 that is in contact with the pulley 467 at the convex portion 474c rotates around the tilted rotating shaft 474a according to the weight of the idle roller 463 and the pulley 467 moving in the arrow B direction, and lowers the arm 473. Move in the direction.

  As shown in FIG. 11, when the idle roller 463 is tilted upward, the compression of the spring 490 is minimized by the arm 473 that supports the idle roller 463. In the spring 490, even when the arm 473 moves upward, the biasing force of the spring 490 acts upward.

  As described above, when the arm 473 moves downward, the rotation axis O2 of the idle roller 463 becomes substantially parallel to the rotation axis O1 of the drive roller 462 as shown in FIG. 10, and the meandering of the belt 461 is corrected. Run stably.

  As shown in FIG. 10, the rotation axis O2 of the idle roller 463 and the rotation axis O1 of the drive roller 462 are substantially parallel, whereby the meandering of the belt 461 is corrected.

  As described above, the belt conveyance device described in the first embodiment moves so that the arm 473 tilts according to the meandering of the belt 461 by the arm 473 supporting the idle roller 463 movably. Thereby, the meandering of the belt 461 can be corrected without generating stress in the peripheral edge of the belt 461. Therefore, the problem of generating cracks in the peripheral edge of the belt 461 can be solved.

  Further, by providing the spring 490 that urges the arm 473 upward, when the idle roller 463 is tilted, the downward force such as the own weight of the idle roller 463 serving as a load can be offset. Accordingly, the idle roller 463 can be tilted with a small thrust force, and the followability of the tilt of the idle roller 463 with respect to the meandering of the belt 461 is improved. Therefore, the idle roller 463 can be easily tilted by the weak thrust generated by the meandering of the belt 461.

  In the first embodiment, as the operation of the idle roller 463, from the state where the idle roller 463 is tilted downward as shown in FIG. 9, the rotation shaft O2 of the idle roller 463 and the drive roller 462 as shown in FIG. From the operation to the state where the rotation axis O1 is parallel and the state where the idle roller 463 is tilted upward as shown in FIG. 11, the rotation axis O2 of the idle roller 463 and the drive as shown in FIG. Two operations, that is, an operation to bring the roller 462 into a state where the rotation axis O1 is parallel to each other have been described. However, no matter which direction the idle roller 463 tilts and the arm 473 moves accordingly, the tilt lever 474 tilts in the direction to cancel the meandering of the idle roller 463 according to the meandering direction of the belt 461. It is like that.

  Therefore, for example, it is not necessary to assemble the position of the belt 461 and the idle roller 463 at a predetermined position when the belt conveyance device is assembled. The belt 461 can travel stably without meandering.

  In the belt conveyance device of the first embodiment, the tilting lever 474 having the rotation shaft 474a inclined with respect to the rotation shaft O1 of the drive roller 462 tilts the idle roller 463 in accordance with the meandering direction of the belt 461, whereby the belt 461 meandering is always corrected and prevented. Therefore, the contact force between the pulley 467 and the bead 468 is reduced, and wear of the bead 468 is suppressed. Therefore, the bead 468 does not get over the pulley 467 and the belt 461 does not come off.

  The belt conveyance device described in the first embodiment is exemplified by the one provided with the spring 490 below the arm 473. The present invention is not limited to this, and a spring 490 may be provided above the arm 473, and this modification will be described below.

  As shown in FIGS. 12 and 13, the arm 473 that supports the idle roller 463 is provided with a spring 490 as an auxiliary mechanism in the vicinity of the upper portion of the bearing 472 so that the urging force Fs is generated upward in FIG. 13. Is provided.

  When the spring 490 is extended to the maximum by the tilt of the idle roller 463 as will be described later, for example, an upward biasing force Fs of 100 g is generated so as to cancel the downward force Fi of 100 g. . That is, Fi is canceled out by the biasing force of the spring 490.

  The spring 490 generates the largest urging force Fs in the upward direction when the arm 473 moves downward, and the urging force Fs decreases as the arm 473 moves upward. When the arm 473 moves most upward, the urging force is minimized.

  Also in this modification, the spring 490 is configured so that the urging force of the spring 490 acts upward when the arm 473 moves most upward. This is because when the urging force of the spring 490 moves downward, that is, when the urging force that pushes the arm 473 is applied when the arm 473 moves to the uppermost position, the idle roller 463 tilts upward. This is because a considerable load is applied. Therefore, in the first embodiment, in the tilting range of the idle roller 463, a relationship is established in which the urging force Fs of the spring 490 is equal to or less than the force Fi applied downward to the arm 473 by the weight of the idle roller. . Further, since Fi ≧ Fs holds in the tilting range of the idle roller 463, the idle roller 463 can tilt downward due to its own weight or the like when, for example, the axial thrust force by the belt 461 is not applied.

  By providing the spring 490 above the arm 473 as described above, when the idle roller 463 is tilted downward as shown in FIG. 9, the spring 490 is maximized by the arm 473 that supports the idle roller 463. Stretched. By this extension, the spring 490 generates, for example, an upward biasing force Fs of 100 g, which cancels, for example, the downward force Fi applied to the arm 473 by its own weight. By this urging force Fs, the idle roller 463 is pulled upward via the arm 473.

  Therefore, the tilting lever 474 stops the downward tilting of the idle roller 463, and when the idle roller 463 tilts upward due to the meandering of the belt 461 in the arrow C direction, the thrust is smaller than that without the spring 490. The idle roller 463 can be moved upward by force. Thereby, the followability of the tilting of the idle roller 463 with respect to the meandering of the belt 461 is improved.

[Embodiment 2]
In the belt conveyance device described in the second embodiment, a torsion spring 495 as an auxiliary mechanism is provided in the arm 473 instead of the spring 490 provided in the arm 473 described in the first embodiment. In addition, about the member which overlaps with the belt conveying apparatus demonstrated in Embodiment 1, the same number is attached | subjected and description is abbreviate | omitted.

In the belt conveyance device of the present invention described in the second embodiment, a torsion spring 495 is provided on an arm 473 as shown in FIGS. The torsion spring 495 is wound around the rotary shaft 473a, and one end of the torsion spring 495 extending in the turning direction is provided on the arm 473, and the other end is provided on a frame (not shown), and urges the arm 473 counterclockwise. As in the first embodiment, for example, when the density of the metal shaft of the idle roller 463 is 7.85 × 10 ⁻³ g / mm, the diameter of the shaft is φ8 mm, and the length is 322 mm, the idle roller 463 Due to its own weight, a force Fi of 100 g is applied downward to the position of the arm 473 that supports the shaft of the idle roller 463.

  This torsion spring 495 is the largest in the direction of turning counterclockwise around the torsion spring 495 when the arm 473 moves most downward (the direction of the arrow indicating the biasing force Fs in FIG. 15), that is, substantially upward. As the urging force Fs is generated and the arm 473 moves upward, the urging force Fs decreases. When the arm 473 moves most upward, the urging force is minimized.

  Further, as described above, when the torsion spring 495 is compressed to the maximum by the downward tilt due to the weight of the idle roller 463 as described above, for example, the force of 100 g in the downward direction due to the weight of the idle roller 463 is reduced. An urging force Fs in the direction of turning counterclockwise about the torsion spring 495 is generated so as to cancel Fi. That is, the force Fi is canceled by the urging force Fs of the torsion spring 495.

  The torsion spring 495 provided on the arm 473 in the second embodiment is adapted to act in the direction in which the urging force Fs of the torsion spring 495 rotates counterclockwise even when the arm 473 moves most upward. This is because when the arm 473 moves upward, the urging force of the torsion spring 495 turns clockwise, that is, if the urging force that pushes the arm 473 downward is applied, the idle roller This is because a load is applied to the upward tilting of 463. Therefore, in the second embodiment, in the tilting range of the idle roller 463, the urging force Fs of the torsion spring 495 has a smaller relationship (Fi ≧ Fs) than the force Fi applied downward to the arm 473 by the weight of the idle roller. It comes to hold. In addition, since Fi ≧ Fs holds in the tilting range of the idle roller 463, the idle roller 463 can tilt downward due to its own weight or the like when, for example, the axial thrust force by the belt 461 is not applied.

  As described above, the belt conveyance device having the torsion spring 495 operates as follows. Note that the description of the same operations as those in Embodiment 1 is omitted.

  For example, as shown in FIG. 9, when the belt 461 is shifted to the right side with respect to the idle roller 463, the bead 468 is positioned on the right side, so that the pulley 467 follows the bead 468 disposed on the belt 461. Located in. At this time, the arm 473 moves downward as shown in FIG. 9 by the force Fi caused by the weight of the idle roller 463. The tilt lever 474 rotates around the rotation shaft 474 a by the force Fi caused by the weight of the idle roller 463, and the tilt lever 474 moves in a direction approaching the pulley 467. Then, the convex portion 474c on the upper side of the tilt lever 474 comes into contact with the pulley 467, and the tilt of the idle roller 463 is stopped.

  As shown in FIG. 9, when the idle roller 463 is tilted downward, the torsion spring 495 is compressed to the maximum by the arm 473 that supports the idle roller 463. By this compression, the torsion spring 495 generates a biasing force Fs in a counterclockwise turning direction that cancels, for example, a downward force Fi of 100 g applied to the arm 473 by the weight of the idle roller 463. By this urging force Fs, the idle roller 463 is pulled upward via the arm 473.

  Therefore, in the belt conveyance device described in the second embodiment, the downward tilt of the idle roller 463 is stopped by the tilt lever 474, and the idle roller 463 is moved by the meandering of the belt 461 in the arrow C direction in FIG. When tilting upward, the idle roller 463 can be moved upward with a smaller thrust than when the torsion spring 495 is not provided. Thereby, the followability of the tilting of the idle roller 463 with respect to the meandering of the belt 461 is improved.

  The arm 473 is provided with a torsion spring 495 that is biased in a counterclockwise turning direction, so that when the idle roller 463 is tilted, the downward force such as the load of the idle roller 463 serving as a load can be offset. it can. Accordingly, the idle roller 463 can be tilted with a small thrust force, and the followability of the tilt of the idle roller 463 with respect to the meandering of the belt 461 is improved. Therefore, the idle roller 463 can be easily tilted by the weak thrust force generated by the meandering of the belt 461.

  Further, by using the torsion spring 495, the belt conveying apparatus described in the second embodiment is stable for a long time without buckling that may occur in the compression spring that expands and contracts in accordance with the movement of the arm 473. The above-described effects can be exhibited.

[Embodiment 3]
In the belt conveyance device described in the third embodiment, a pulley mechanism 491 as an auxiliary mechanism is provided in the arm 473 instead of the spring 490 provided in the arm 473 described in the first embodiment. In addition, about the member which overlaps with the belt conveying apparatus demonstrated in Embodiment 1, the same number is attached | subjected and description is abbreviate | omitted.

  In the belt conveyance device of the present invention described in Embodiment 3, a pulley mechanism 491 is provided on an arm 473 as shown in FIGS. The pulley mechanism 491 includes a wire 492, a weight 493, and a pulley 497. The pulley 497 is rotatably provided on a frame (not shown) so as to be positioned above the arm 473.

  The wire 492 is wound around the pulley 497. One end of the wire 492 is connected to the vicinity of the bearing 472 on which the idle roller 463 of the arm 473 is supported, and the other end is provided with a weight 493 having a predetermined weight. The arm 473 is pulled up by the weight 493.

As in the first embodiment, for example, when the density of the metal shaft of the idle roller 463 is 7.85 × 10 ⁻³ g / mm, the diameter of the shaft is φ8 mm, and the length is 322 mm, the idle roller 463 Due to its own weight, a force Fi of 100 g is applied downward to the position of the arm 473 that supports the shaft of the idle roller 463.

  The weight 493 of the pulley mechanism 491 has a force that balances the force Fi caused by the weight of the idle roller 463, such as about 95 to 100% of the force Fi, or a force slightly smaller than the force Fi acting on the arm 473. The weight is selected. The pulley mechanism 491 lifts the arm 473 upward by the pulling force Fs by the weight 493 via the wire 492 so that the force Fi due to the weight of the idle roller 463 is canceled.

  The pulley mechanism 491 provided on the arm 473 in the third embodiment is different from the urging force of the spring or torsion spring as in the first or second embodiment in that the idle roller 463 tilts upward and the arm 473 moves upward. Even when moved, the lifting force Fs does not change. That is, a constant lifting force Fs acts regardless of the position of the arm 473. Therefore, the tilt of the idle roller 463 is always stable. Further, as described above, in the tilting range of the idle roller 463, the pulling force Fs of the pulley mechanism 491 is, for example, 90 to 100% of the force Fi applied to the arm 473 in the downward direction by the weight of the idle roller. Is selected so as to be applied in the upward direction, and a relationship (Fi ≧ Fs) that is equal to or less than the force Fs is established.

  It is difficult to maintain a state where the force Fi and the lifting force Fs are equal over the entire tilting range of the idle roller 463. Therefore, by setting the lifting force Fs to be slightly smaller than the force Fi, the balance of the force is lost depending on the state of the belt conveyance device and the like, and the force Fi is smaller than the lifting force Fs (Fi <Fs). This can be prevented. As a result, it is possible to reduce the load applied to the upward tilting of the idle roller 463.

  As described above, the belt conveyance device having the pulley mechanism 491 operates as follows. Note that the description of the same operations as those in Embodiment 1 is omitted.

  For example, as shown in FIG. 9, when the belt 461 is shifted to the right side with respect to the idle roller 463, the bead 468 is positioned on the right side, so that the pulley 467 follows the bead 468 disposed on the belt 461. Located in. At this time, the arm 473 moves downward as shown in FIG. 9 by the force Fi caused by the weight of the idle roller 463. The tilt lever 474 rotates around the rotation shaft 474 a by the force Fi caused by the weight of the idle roller 463, and the tilt lever 474 moves in a direction approaching the pulley 467. Then, the convex portion 474c on the upper side of the tilt lever 474 comes into contact with the pulley 467, and the tilt of the idle roller 463 is stopped.

  As shown in FIG. 9, the pulley mechanism 491 gives the arm 473 an upward pulling force Fs that cancels, for example, a downward force Fi of 100 g applied to the arm 473 by the weight of the idle roller 463. When the idle roller 463 is tilted downward, the pulley mechanism 491 acts to counteract the force Fi applied by the idle roller 463's own weight. With this lifting force Fs, the idle roller 463 is pulled upward via the arm 473.

  Therefore, in the belt conveyance device described in Embodiment 3, the downward tilt of the idle roller 463 is stopped by the tilt lever 474, and the idle roller 463 is moved by meandering of the belt 461 in the direction of arrow C in FIG. When the upward direction tilts, the idle roller 463 can be moved upward with a smaller thrust force than when the pulley mechanism 491 is not provided. Thereby, the followability of the tilting of the idle roller 463 with respect to the meandering of the belt 461 is improved.

  By providing the pulley mechanism 491 that pulls the arm 473 upward, the arm 473 can cancel downward force such as its own weight of the idle roller 463 as a load when the idle roller 463 is tilted. Accordingly, the idle roller 463 can be tilted with a small thrust force, and the followability of the tilt of the idle roller 463 with respect to the meandering of the belt 461 is improved. Therefore, the idle roller 463 can be easily tilted by the weak thrust generated by the meandering of the belt 461.

  In addition, by using the pulley mechanism 491, the belt conveyance device described in Embodiment 3 can stably apply a constant lifting force Fs to the arm 473 regardless of the position of the arm 473.

[Embodiment 4]
The belt conveyance device described in the fourth embodiment includes an arm 498 instead of the arm 473 described in the first embodiment and the spring 490 provided on the arm 473. In addition, about the member which overlaps with the belt conveying apparatus demonstrated in Embodiment 1, the same number is attached | subjected and description is abbreviate | omitted.

  As shown in FIGS. 18 and 19, the belt conveyance device of the present invention described in the fourth embodiment has an arm 498 as a roller support member longer than the arm 473 instead of the arm 473 of the first embodiment. 471. The arm 498 closer to the idle roller 463 than the rotary shaft 473a is provided with a hole 498b provided with a bearing 472 via a spring 469, and supports the idle roller 463 so as to be movable. The arm 498 is an auxiliary mechanism integrally formed so that the arm 498 extends in a direction substantially perpendicular to the rotation axis O2 of the idle roller 463 and on the opposite side of the hole 498b with respect to the rotation shaft 473a. The extending portion 499 is provided. As a result, the center of gravity of the arm 498 is closer to the extending portion 499 than the rotation shaft 473a.

As in the first embodiment, for example, when the density of the metal shaft of the idle roller 463 is 7.85 × 10 ⁻³ g / mm, the diameter of the shaft is φ8 mm, and the length is 322 mm, the idle roller 463 Due to its own weight, a force Fi of 100 g is applied downward to the position of the arm 473 that supports the shaft of the idle roller 463.

  As described above, the center of gravity of the arm 498 is closer to the extending portion 499 than the rotation shaft 473a. The arm 498 is configured such that a force F is generated in the downward direction by the weight of the arm 498 at a position on the extending portion 499 that is a distance L away from the rotation shaft 473a of the arm 498. The arm 498 has a pulling force Fs that lifts the vicinity of the bearing 472 supporting the idle roller 463 on the opposite side across the rotation shaft 473a by rotating about the rotation shaft 473a. . The idle roller 463 is pulled upward by the lifting force Fs.

  For this lifting force Fs, for example, a force that balances with the force Fi of the idle roller 463, such as about 95 to 100% of the force Fi, or a force slightly smaller than the force Fi acts in the vicinity of the bearing 472 of the arm 473. Such weight is selected. The extending portion 499 pulls up the vicinity of the bearing 472 provided on the arm 498 via the rotating shaft 473a, so that the force Fi due to the weight of the idle roller 463 is canceled out.

  In the fourth embodiment, the arm 498 differs from the spring or torsion spring biasing force as in the first or second embodiment, even when the idle roller 463 tilts upward and the arm 473 moves upward. The pulling force Fs does not change. That is, a constant lifting force Fs acts regardless of the position of the arm 473. Therefore, the tilt of the idle roller 463 is always stable. Furthermore, the configuration is simplified compared to the pulley mechanism of the third embodiment. Further, as described above, in the tilting range of the idle roller 463, the lifting force Fs due to the weight of the arm 498 is, for example, 90 to 100% of the force Fi applied downward to the arm 473 by the weight of the idle roller. The force is selected so as to be applied in the upward direction, and a relationship (Fi ≧ Fs) that is equal to or less than the force Fs is established.

  It is difficult to maintain a state where the force Fi and the lifting force Fs are equal over the entire tilting range of the idle roller 463. Therefore, by setting the lifting force Fs to be slightly smaller than the force Fi, the balance of the force is lost depending on the state of the belt conveyance device and the like, and the force Fi is smaller than the lifting force Fs (Fi <Fs). This can be prevented. As a result, it is possible to reduce the load applied to the upward tilting of the idle roller 463.

  Thus, the belt conveyance device having the arm 498 operates as follows. Note that the description of the same operations as those in Embodiment 1 is omitted.

  For example, as shown in FIG. 9, when the belt 461 is shifted to the right side with respect to the idle roller 463, the bead 468 is positioned on the right side, so that the pulley 467 follows the bead 468 disposed on the belt 461. Located in. At this time, the arm 498 moves downward as shown in FIG. 9 by the force Fi caused by the weight of the idle roller 463. The tilt lever 474 rotates around the rotation shaft 474 a by the force Fi caused by the weight of the idle roller 463, and the tilt lever 474 moves in a direction approaching the pulley 467. Then, the convex portion 474c on the upper side of the tilt lever 474 comes into contact with the pulley 467, and the tilt of the idle roller 463 is stopped.

  As shown in FIG. 9, the arm 498 is generated by the downward force F of the extending portion 499 due to its own weight, which cancels the downward force Fi of 100 g applied to the arm 498 by the own weight of the idle roller 463. A force Fs for pulling up the idle roller 463 is applied. When the idle roller 463 is tilted downward, the arm 498 acts so as to cancel the force Fi applied by its own weight.

  Therefore, in the belt conveyance device described in the fourth embodiment, the downward tilt of the idle roller 463 is stopped by the tilt lever 474, and the idle roller 463 is moved by the meandering of the belt 461 in the direction of arrow C in FIG. When the upward direction tilts, the idle roller 463 can be moved upward with a smaller thrust than when a short arm without the extending portion 499 is provided. Thereby, the followability of the tilting of the idle roller 463 with respect to the meandering of the belt 461 is improved.

  The arm 498 is provided with an extending portion 499 that pulls up the idle roller 463 in the upward direction, so that when the idle roller 463 is tilted, the downward force such as the own weight of the idle roller 463 serving as a load can be offset. Accordingly, the idle roller 463 can be tilted with a small thrust force, and the followability of the tilt of the idle roller 463 with respect to the meandering of the belt 461 is improved. Therefore, the idle roller 463 can be easily tilted by the weak thrust generated by the meandering of the belt 461.

  Further, by using the arm 498 provided so that the extending portion 499 is integrally formed, the belt conveyance device described in the fourth embodiment idles a constant lifting force Fs regardless of the position of the arm 498. It can be stably applied to the roller 463. In addition, the configuration can be simplified.

  The belt conveyance device described in Embodiments 1 to 4 can be applied to the above-described image forming apparatus. Thus, the belt conveying device capable of correcting the meandering of the belt can convey the recording medium to the image forming unit without being displaced, and can form an image without color misregistration.

  The present invention is an example applied to an endless belt of an electrophotographic printer. However, the present invention can also be applied to a fixing device and a sheet conveying device of an electrophotographic printer using an endless belt. Furthermore, the present invention can be used not only for an electrophotographic printer but also for a belt device using an endless belt.

1 is a diagram illustrating an example of a configuration of an image forming apparatus of the present invention. 1 is a top view of a belt conveyance device of the present invention described in Embodiment 1. FIG. It is a side view of the belt conveyance apparatus of the present invention explained in Embodiment 1. It is a top view of the tilting lever of the belt conveyance device of the present invention. It is a side view of the tilting lever of the belt conveyance device of the present invention. It is a front view of the tilting lever of the belt conveyance device of the present invention. It is a perspective view of the tilting lever of the belt conveyance device of the present invention. It is a figure which shows operation | movement of the tilting lever of the belt conveying apparatus of this invention. It is a figure explaining the meandering of the belt of the belt conveying apparatus of this invention. It is a figure explaining the meandering of the belt of the belt conveying apparatus of this invention. It is a figure explaining operation | movement of the belt conveying apparatus of this invention. It is a figure explaining operation | movement of the belt conveying apparatus of this invention. It is a figure explaining operation | movement of the belt conveying apparatus of this invention. It is a top view of the belt conveyance apparatus as a modified example of the present invention described in the first embodiment. It is a side view of the belt conveyance apparatus as a modification of this invention demonstrated in Embodiment 1. FIG. It is a top view of the belt conveyance device of the present invention explained in Embodiment 2. It is a side view of the belt conveyance apparatus of this invention demonstrated in Embodiment 2. FIG. FIG. 6 is a top view of a belt conveying device of the present invention described in a third embodiment. It is a side view of the belt conveyance apparatus of this invention demonstrated in Embodiment 3. FIG. It is a top view of the belt conveyance device of the present invention explained in Embodiment 4. It is a side view of the belt conveyance apparatus of this invention demonstrated in Embodiment 4. FIG.

Explanation of symbols

460 Transfer section 461 Belt 462 Drive roller 463 Idle roller 464 Transfer roller 465 Cleaning blade 466 Toner box 467 Pulley 468 Bead 469 Spring 470 Gear 471 Belt frame 473 Arm 473a Rotating shaft 473b Hole 474 Tilt lever 474a Rotating shaft 474b Elliptical hole 474c Convex Portion 474d locus 490 spring 491 pulley mechanism 492 wire 493 weight 495 torsion spring 497 pulley 498 arm 498b hole 499 extension portion

Claims (9)

Multiple rollers,
A belt stretched by the roller and driven to rotate by rotation of the roller;
A roller support portion provided on at least one of the plurality of rollers, and supporting the roller so that the roller can move according to the rotational driving of the belt;
A belt conveyance device comprising: an auxiliary mechanism provided on the roller support portion and assisting movement of the roller.   A rotating shaft inclined in the axial direction of the roller, and further having a roller moving section that rotates around the rotating shaft and moves the roller as the belt moves in the axial direction of the roller; The belt conveyance device according to claim 1.   The belt conveyance device according to claim 1, wherein the auxiliary mechanism supports the roller support portion so as to cancel the weight of the roller and assists the movement of the roller. The auxiliary mechanism is a spring;
The belt conveying device according to claim 1, wherein the roller is pulled upward by an urging force of the spring. The auxiliary mechanism is a torsion spring,
The belt conveying device according to any one of claims 1 to 3, wherein the roller is pulled upward by an urging force of the torsion spring. The auxiliary mechanism is
A weight,
A wire provided at one end with the weight and connected to the roller support member at the other end;
A pulley mechanism having a pulley disposed between one end of the wire provided with the weight and the other end connected to the roller support member;
The belt conveyance device according to claim 1, wherein the roller is lifted upward by the weight. The auxiliary mechanism is
4. The extending portion integrally formed with the roller support portion so as to extend in a direction substantially perpendicular to the roller support portion with respect to the axial direction of the roller. The belt conveyance apparatus as described in.   The relationship between the force Fs that the auxiliary mechanism moves the roller upward via the roller support portion and the force Fi that the roller moves downward due to its own weight is Fi ≧ Fs. The belt conveying device according to claim 1. An image forming apparatus for forming an image on a recording medium,
The belt conveyance device according to any one of claims 1 to 8,
An image forming apparatus comprising: an image forming unit that forms an image on the recording medium transported by the belt transport device.