JP2007223783A - Belt conveyance device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a belt conveyance device capable of preventing concentration of stress caused in a peripheral fringe part of an endless belt and having long service life. <P>SOLUTION: This belt conveyance device is provided with the endless belt for carrying an object to be conveyed, a plurality of rotary members for stretching and rotating the endless belt and letting it run, and a belt guide member guiding the peripheral fringe part of the endless belt and having such elasticity that reduces force in the direction of rotary shaft of the rotary member received from the endless belt. By providing the belt guide member having such elasticity that reduces force in the direction of rotary shaft of the rotary member received from the endless belt, it is possible to suppress contact stress generated in the peripheral fringe part of the endless belt and prolong service life of the belt conveyance device. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  One type of image forming apparatus that performs color printing is a quadruple tandem system. In this method, four photosensitive drums as 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 onto a sheet of paper conveyed by running an endless belt. In such an image forming apparatus, the color misregistration of each color may greatly affect the image quality, and one of the causes of the color misregistration is the effect of meandering of the endless belt. In order to prevent the endless belt from meandering, in the conventional image forming apparatus, a regulating plate is arranged in parallel with the end face of the driving roller or idle roller of the endless belt. The guide is slid on the sliding surface.

  If the force acting in the meandering direction (hereinafter referred to as the thrust force) on the peripheral edge of the endless belt that slides with such a regulating plate is large, the endless belt will swell temporarily on the sliding surface with the regulating plate, and this state If it continues, there is a problem that bending fatigue occurs in the portion where the rising of the conveying belt occurs, and the conveying belt is destroyed. In order to solve such a problem, a belt guide provided with a retaining portion formed so as to be opposed to the endless belt and project so as to prevent the peripheral edge from rolling up when the endless belt runs is proposed. (For example, refer to Patent Document 1).

Japanese Patent Laid-Open No. 11-84753

  However, in the conventional belt conveyance device of the image forming apparatus, the force that causes the peripheral edge of the endless belt to roll up is pressed toward the flange side by pressing the retaining portion, so that the endless belt is pressed against the flange portion. Strength increases. Normally, when the peripheral edge of the endless belt is flat, the stress generated at the peripheral edge of the endless belt is not particularly problematic because it contacts the regulating part uniformly, but there are steps, irregularities, waviness, etc. at the peripheral edge of the endless belt Further, since the contact stress generated at the peripheral edge of the endless belt becomes high, there is a problem that the step itself or the like repeatedly comes into contact with the flange portion to cause a crack and the belt itself is cut.

  The present invention has been made to solve these problems, and effectively prevents stress concentration occurring at the peripheral edge of the endless belt and provides a long-life belt conveying device.

  In order to solve the above-described problems, a belt conveyance device according to the present invention includes an endless belt that carries an object to be conveyed, a plurality of rotating members that stretch and rotate the endless belt, and a peripheral portion of the endless belt. And a belt guide member having elasticity to relieve a force in a rotation axis direction of the rotating member that is guided and received from the endless belt.

  Furthermore, the image forming apparatus of the present invention has the belt conveying device as described above, and has an image forming unit that forms an image on the conveyance object carried on the endless belt by the belt conveying device. Features.

  According to the belt conveying device of the present invention, the belt guide member has a structure having elasticity that relaxes the force in the rotation axis direction of the rotating member received from the endless belt, and therefore the endless belt exhibits an operation that meanders. Even when stress is applied to the peripheral edge portion of the endless belt, it is possible to prevent an adverse effect that an excessive force is applied to the endless belt, and it is possible to extend the life of the belt conveyance device.

  A preferred embodiment of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus. In this embodiment, the image forming apparatus is an example of a printer, but the image forming apparatus of the present invention may be a facsimile machine, a copying machine, or a multifunction machine having a scanner function. Also good.

  In FIG. 1, a housing 600 has a sheet tray 100 on which sheets 101 of sheets as a medium are stacked, a sheet feeding unit 200 that feeds the sheets 101 one by one, and one sheet from the sheet feeding unit 200. A sheet conveying unit 300 for conveying the sheet taken out and fed out every time to the image forming unit 400, an image forming unit 400 for transferring a toner image onto the sheet, and a toner image transferred onto the sheet A fixing unit 500 for fixing the sheet with heat and pressure is disposed as a main mechanism unit.

  The paper tray 100 has a structure in which the paper 101 is stacked inside, and is disposed on the bottom surface side of the housing 600. A paper placement plate 102 for stacking paper 101 provided inside the paper tray 100 is provided in the paper tray 100, and the paper placement plate 102 is rotatable about a support shaft 105. . The paper tray 100 is provided with a guide member (not shown) that regulates the stacking position of the paper 101. The paper side in a direction orthogonal to the paper feeding direction (the right side in FIG. 1) and the paper side in the paper feeding direction. Restrict the loading position to be constant. A lift-up lever 103 for moving the paper placement plate 102 up and down is provided on the front end side of the paper placement plate 102 so as to be rotatable on a support shaft (not shown), and a drive motor 104 drives the lift-up lever 103. It is provided to do. The drive motor 104 is engaged with a support shaft (not shown) of the lift-up lever 103 so as to be able to contact and separate.

  A paper feeding unit 200 that feeds the paper 101 one by one is provided on the feeding side of the paper tray 100. The rise detection unit 201 is a sensor that is provided on the upper end side of the paper tray 100 and detects that the paper 101 has been raised to a certain height. The paper feeding unit 200 includes a pickup roller 202 provided so as to be pressed against the paper 101 raised to a certain height, and a roller pair of a feed roller 203 and a retard roller 204 that separates the paper fed by the pickup roller 202 one by one. 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 remaining paper amount detection unit 206 that detects the remaining amount of paper.

  The sheet conveyance unit 300 is a mechanism unit for conveying the sheet 101 separated and fed from the sheet feeding unit 200 to the image forming unit 400. In the conveyance path 306 of the paper 101, paper sensors 301 and 303 for detecting the fed paper 101 are provided. On the downstream side of the conveyance path 306 of the paper sensor 301, the fed paper 101 is fed. A pair of conveyance rollers 302 and 304 for conveyance are provided.

    Disposed above the paper tray 100 in the housing 600 is an image forming unit 400 for transferring a toner image onto the paper. The image forming unit 400 is arranged in series along the transport direction of the paper 101. The toner image forming unit 430 and the transfer unit 460 that transfers the toner image formed by the toner image forming unit 430 to the upper surface of the paper 101 by the Coulomb force. The toner image forming unit 430 includes a photosensitive drum 431 that carries a toner image, a charging roller 432 that charges the surface of the photosensitive drum 431, and an LED array that forms an electrostatic latent image on the charged surface of the photosensitive drum 431. An exposure head 433, a developing roller 434 that forms a toner image on an electrostatic latent image by frictional charging, a cleaning blade 435 that scrapes residual toner from the surface of the photosensitive drum 431, and a toner supply unit 436 that supplies toner. .

  The transfer unit 460 includes an endless belt 461 that conveys the paper 101, a drive roller 462 that is rotated by a driving unit (not shown) and drives the endless belt 461, a tension roller 463 that forms a roller pair with the drive roller 462, and stretches the endless belt 461. The transfer roller 464 arranged so as to face the toner image forming portion 430 and press-contact with each photosensitive drum 431, the cleaning blade 465 for scraping and cleaning the toner adhering to the endless belt 461, and the cleaning blade 465 being scraped off. The toner box 466 is configured to accumulate toner.

  At a further downstream portion of the transfer unit 460 centering on the endless belt 461, a fixing unit 500 for fixing the toner image transferred onto the paper 101 by the transfer unit 460 to the paper 101 by heat and pressure. Is disposed. The fixing unit 500 includes a halogen lamp 503 serving as a heat source therein, and includes a pair of rollers, an upper roller 501 and a lower roller 502, whose surfaces are formed of an elastic body. A discharge roller pair 504 is provided on the downstream side of the upper surface of the endless belt 461 in order to discharge the paper fixed by the fixing unit 500, and after the paper transport direction is rotated 180 degrees by the discharge roller pair 504, the housing The printed paper is deposited on the stacker unit 505 disposed on the top of the body 600.

  Here, the transfer unit 460 constituting the main part of the belt conveyance device of the present embodiment will be described in more detail with reference to FIGS. As shown in FIGS. 2 and 3, the transfer unit 460 is a plate-like frame member whose longitudinal direction is the conveying direction of the endless belt 461, and rotates around the belt frame 471 disposed on both sides of the endless belt 461. The endless belt has a drive roller 462 having a high-friction surface and a roller 463 that is supported and freely supported by the end portion, and an idle roller 463 that is rotatably supported by bearings 472 at both ends. 461 is stretched between the drive roller 462 and the idle roller 463.

  On the idle roller 463 side of the belt frame 471, there are formed a pair of arms 473 extending in the conveying direction (a direction in the figure) and having both circular ends, and one end of each of these arms 473 is rectangular. A slide opening 473b is formed so that the other end is cut out in a semicircular shape, and a bearing member 472 that is slidable inside the slide opening 473b is provided. The pair of arms 473 is supported by a belt frame 471 so as to be rotatable about a shaft 473a, and the bearing member 472 is biased by a spring 469 so as to maintain a predetermined position within the slide opening 473b. Since the idle roller 463 is rotatably supported by the bearing member 472, the idle roller 463 is biased by the spring 469 so as to be in a predetermined position.

  As shown in FIGS. 4 to 6, a roller tilting lever member 474 is provided inside one arm 473. The roller tilting lever member 474 has a rectangular plate shape having a circular end substantially along the shape of the arm 473, and an elongated hole-shaped through hole 474b corresponding to the position of the idle roller 463 is formed at the center of the flat plate portion. The shaft of the idle roller 463 is inserted through the through hole 474b. A pair of gently projecting contact portions 474c are formed on the upper and lower portions of the through hole 474b of the flat plate portion and facing the idle roller 463, and the contact portions 474c will be described later. It abuts on the belt guide holding member 467. The roller tilting lever member 474 disposed between the arm 473 and the belt guide holding member 467 has a rotating shaft 474a inclined with respect to the direction of the rotating shaft 462a of the drive roller 462, and rotates around the rotating shaft 474a. Then, the position relative to the belt guide holding member 467 changes relatively.

  As shown in FIG. 7, the belt guide holding member 467 is rotatably supported on the rotation shaft of the idle roller 463 and is slidable in the axial direction. The shape of the belt guide holding member 467 is a flange shape having a disk-shaped bottom surface 467a and a cylindrical portion 467b formed in the center portion, and an outer peripheral edge portion 467c whose outer peripheral portion rises in the axial direction. Have. A belt guide member 481 for abutting and guiding the peripheral edge portion of the endless belt 461 with elasticity is held so as to fit in the outer peripheral edge portion 467c of the belt guide holding member 467. The belt guide member 481 is circumferentially connected at the outer peripheral portion, and slits are provided radially toward the center. The belt guide member 481 is made of a springy material such as a stainless plate or a synthetic resin plate. Therefore, the guide portion 481a that guides the endless belt 461 has elasticity in the axial direction (thrust direction), and can be partially bent by receiving an axial force. A stopper ring 482 for holding the belt guide member 481 on the belt guide holding member 467 is formed on the outer peripheral surface of the cylindrical portion of the belt guide holding member 467, and the belt guide member 481 is detached from the belt guide holding member 467. To prevent it.

  The endless belt 461 is generally formed into a sheet by stretching with an elastic synthetic resin such as polyimide or urethane. After molding, the peripheral edge of the endless belt 461 is cut to a desired width according to the size of the paper or the like, so that a step, unevenness, or undulation may occur in the peripheral edge of the finished endless belt 461. In addition, in order to maintain the strength of the peripheral edge portion of the endless belt 461, there is a case where a reinforcing film 468 is attached along the peripheral edge portion of the endless belt 461 with a double-sided adhesive tape, an adhesive, or the like. The above configuration is an example, and other materials may be used depending on the material and speed of the paper to be conveyed, the service life, and the like.

  The roller tilt lever member 474 will be described in detail with reference to FIG. 6. The roller tilt lever member 474 has a rotation shaft 474a inclined by an angle θ with respect to the rotation shaft 462a of the drive roller, and has a long hole shape. The shaft of the idle roller 463 is rotatably and slidably penetrated through the hole 474b, and a contact portion 474c is provided so as to contact the belt guide holding member 467. As will be described later, the roller tilting lever member 474 has a rotating shaft 474a inclined with respect to the flat plate portion. Therefore, when the roller tilting lever member 474 rotates around the rotating shaft 474a, a locus like a broken line 474d is drawn as shown in FIG. Therefore, when the shaft end of the idle roller 463 is inclined downward (indicated by a down arrow in FIG. 6), the roller tilting lever member 474 is also rotated downward and closer to the idle roller 463. Then, the belt guide member 467 is operated to be pushed in via the belt guide holding member 467. Similarly, when the shaft end of the idle roller 463 is tilted upward (indicated by an upward arrow in FIG. 6), the roller tilting lever member 474 rotates upward and away from the idle roller 463.

  Next, the overall operation of the image forming apparatus will be schematically described with reference to FIG. 1, and then the operation of the transfer unit will be described. First, in FIG. 1, a paper tray 100 is detachably attached to an image forming apparatus, and paper 101 is stacked inside by an operator. At this time, the paper tray 100 is provided with a guide member (not shown) that regulates the stacking position of the paper 101, the paper side surface in the direction orthogonal to the paper feeding direction (right side in FIG. 1), and the paper in the paper feeding direction. The loading position is regulated to be constant. When the paper tray 100 is inserted into the image forming apparatus, the lift-up lever 103 and the drive motor 104 are engaged, and a control unit (not shown) drives the drive motor 104. As the lift-up lever 103 rotates, the tip of the lift-up lever 103 lifts the bottom of the paper placing plate 102 and raises the paper 101 stacked on the paper placing plate 102.

  Next, when the sheet 101 rises to a height at which it is in pressure contact with the pickup roller 202, the rise detection unit 201 detects it, and a control unit (not shown) stops the drive motor 104 based on the detected information. Image data is processed by an image processing unit (not shown), and a print command is sent to a control unit (not shown). A drive motor (not shown) drives the pickup roller 202 to rotate. The sheet fed by the pickup roller 202 is conveyed to the nip position of the feed roller 203 and retard roller 204 pair, and the sheets 101 are separated one by one. The paper 101 separated and fed out from 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 transport roller pair 302 drives a drive unit (not shown) by a control unit (not shown) based on the passage time of the paper sensor 301 to send out the paper 101. In general, by delaying the time when the conveying roller pair 302 starts to rotate from the time when the sheet passes through the sheet sensor 301, the sheet is pushed into the pressure contact portion of the conveying roller pair 302 to correct the skew of the sheet. The sheet fed from the conveyance roller pair 302 passes through the sheet sensor 303 and is sent to the conveyance 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 304 and feeds the paper 101 without stopping. The sheet sent out by the conveying roller pair 304 passes through the writing sensor 305 and is sent to the image forming unit 400.

  In the image forming unit 400, the exposure head 433 including an LED array irradiates the surface of the photosensitive drum 431 based on the image data sent from the image processing unit (not shown), so that the photosensitive drum charged by the charging roller 432 is used. An electrostatic latent image is formed on the surface of 431. The toner supplied from the toner supply unit 436 forms an image on the photosensitive drum 431 by the developing roller 434. The toner image carried on the photosensitive drum 431 is transferred onto a sheet conveyed by electrostatic attraction at a pressure contact portion with a transfer roller 464. The endless belt 461 that electrostatically attracts and conveys the paper 101 causes the endless belt 461 to travel by rotating a drive roller 462 from a driving unit (not shown). The photosensitive drum 431 and the endless belt 461 of the toner image forming unit 430 are driven in synchronization, and the toner images are sequentially superimposed and transferred onto a sheet electrostatically attracted to the endless belt 461. The sheet on which the image is transferred by the image forming unit 400 is sent to a fixing unit 500 that fuses the toner image to the sheet with heat and pressure. The sheet on which the image sent from the image forming unit 400 is transferred applies heat and pressure to the toner image on the sheet to melt and fix the toner image on the sheet. Thereafter, the sheet 101 is discharged to the stacker unit 505 by the discharge roller pair 504.

  Here, the operation of the transfer unit 460 will be described in more detail with reference to FIGS. 2, 3, and 8 to 12. FIG. The endless belt 461 travels in the direction of arrow a shown in FIG. 1 by a drive roller 462 that is rotatably supported by the belt frame 471 and is fixedly locked to a gear 470 at the end and has a high friction surface and is rotated by a drive unit (not shown). Let Here, when the endless belt 461 is running, the parallelism between the drive roller 462 and the idle roller 463 is poor. For example, when the shaft end on the right side of the idle roller 463 is twisted upward as shown in FIG. Since 461 runs perpendicularly to the axis of the wound roller, it shows a running locus as shown in the figure. As a result, the endless belt 461 meanders in the direction b perpendicular to the running direction a, and conversely the shaft end portion. Is twisted downward (see FIG. 12), it is known to meander in the c direction. At this time, as can be seen from FIGS. 11 and 12, the amount of meandering of the belt increases in proportion to the twisted amount of the roller pair. When the endless belt 461 meanders as described above, a phenomenon that the meandering of the endless belt 461 is regulated while the peripheral edge portion of the endless belt 461 and the reinforcing film 468 are rubbed against the belt guide member 481 occurs.

  Under such circumstances, the belt conveyance device of the present embodiment operates as follows and functions to correct the position of the endless belt 461 meandering. As shown in FIG. 8, when the endless belt 461 is biased to the right side for some reason, the belt guide holding member 467 guides the peripheral edge of the endless belt 461 through the belt guide member 481 having elasticity. 8, the roller tilting lever member 474 is rotated around the rotating shaft member 474 a so as to be inclined downward and toward the idle roller 463, and the idle roller 463 is tilted as shown in FIG. 8. To do.

  When the drive roller 462 (not shown) is rotated and the endless belt 461 starts to run, the belt guide holding member 467 and the belt guide member 481 are pushed against the peripheral edge of the endless belt 461 as described above. And move in the C direction. Since the roller tilting lever member 474 is in contact with the belt guide holding member 467 at the contact portion 474c, the roller tilting lever member 474 is pushed by the belt guide holding member 467 having elasticity to relieve the force in the thrust direction and is inclined by the rotating shaft member 474a. It will rotate around the axis and return to the position shown in FIG. In the position shown in FIG. 9, the rotation shaft 463a of the idle roller 463 and the rotation shaft 462a of the drive roller 462 (not shown) are substantially parallel. Therefore, the meandering of the endless belt 461 is reduced, and the meandering converges and stabilizes at this position. Will run.

  This is because when the endless belt 461 is biased to the right side for some reason, the pressing force of the endless belt 461 to the belt guide member 481 is reduced, and the roller tilting lever member 474 moves downward according to its own weight of the idle roller 463, The roller tilt lever member 474 rotates to the idle roller 463 side, and the upper contact portion 474c comes into contact with the belt guide holding member 467. At this time, the endless belt 461 moves meandering in the C direction. When the pressing force of the endless belt 461 to the belt guide member 481 increases, the endless belt 461 is pushed by the belt guide member 481 and the roller tilting lever member 474 is moved. This time, it rotates so that it moves upward. Eventually, the pressing force by the endless belt 461 and the force that the roller tilting lever member 474 tries to lower due to its own weight balance, and the two rotating shafts 462a and 463a are parallel. (See FIG. 9).

  When the idle roller 463 tilts to the position shown in FIG. 10, the endless belt 461 meanders in the direction of arrow B, so that the belt guide holding member 467 similarly moves in the B direction, and the roller tilt lever member 474 is the idle roller. The abutting portion 474c rotates downwardly and toward the idle roller 463 so as to be in contact with the belt guide holding member 467 by its own weight, and the endless belt 461 travels stably at a position as shown in FIG.

  As described above, the operation according to the position of the idle roller 463 has been described with respect to the two cases of the operation from the state shown in FIG. 8 to FIG. 9 and the operation from the state shown in FIG. 10 to FIG. The roller tilting lever member 474 tilts the idle roller 463 in a direction that always reduces and cancels the meandering according to the meandering direction of the endless belt 461. Therefore, for example, when the belt device is assembled, it is not necessary to assemble the endless belt 461 and the idle roller 463 at predetermined positions. If the endless belt 461 is run, the guide portion 481a of the belt guide member 481 and the endless belt 461 A force acting in the meandering direction of the belt (hereinafter referred to as a thrust force) is generated at the peripheral portion, and the idle roller 463 tilts to a position where the meandering is naturally reduced and canceled, and the endless belt 461 can run stably without meandering. Become.

  By the way, as described above, the rotation shaft 463a of the idle roller 463 and the rotation shaft 462a of the drive roller 462 (not shown) are substantially parallel, and the meandering of the endless belt 461 is accommodated and travels stably. The belt guide member 481 always has a predetermined contact force, that is, a force that balances the force by which the roller tilting lever member 474 is lowered by the weight of the idle roller 463 and the force by which the endless belt 461 is pressed against the belt guide member 481. It is in contact. As shown in FIGS. 13 and 14, the case where the endless belt 461 has a convex portion 461 a at the peripheral edge will be described. As shown in FIG. 13, when the belt guide member 483 is made of a rigid material, the endless belt 461 rotates, and the convex portion 461a at the peripheral edge of the endless belt 461 is in contact with the point A of the belt guide member 483. Since the belt guide holding member 467 is moved in contact, a gap t is opened between the peripheral edge of the endless belt 461 and the belt guide member 483. As a result, when the gap t is opened, the thrust force acting on the point A of the belt guide member 483 and the belt peripheral portion is concentrated on the convex portion 461a of the endless belt 461 peripheral portion.

  As described above, in this embodiment, as shown in FIG. 14, the belt guide member 481 is made of a springy material such as a stainless steel plate. Therefore, the guide portion 481a for guiding the endless belt 461 is elastic in the axial direction. 14 and when the endless belt 461 rotates and the convex portion 461a at the peripheral edge of the endless belt 461 contacts the point A of the belt guide member 481 (at the point A in FIG. 14). However, the guide portion 481a of the belt guide member 481 follows the shape of the convex portion 461a at the peripheral edge of the endless belt 461 and always contacts the entire peripheral edge of the endless belt 461. It is possible to prevent stress from concentrating on the peripheral portion, and to run the endless belt 461 stably without causing the endless belt 461 to bend or crack.

  As described above, in the first embodiment of the present invention described above, it is possible to partially deflect the belt guide member 481 made of a springy material by providing a slit portion on a disk-shaped plate. The peripheral edge portion of the endless belt 461 can avoid stress concentration with the belt guide member 481. Therefore, it is possible to prevent cracks from occurring while preventing the peripheral edge of the endless belt 461 from curling up.

[Second Embodiment]
The configuration of the second embodiment of the present invention will be described with reference to FIGS. In the second or subsequent embodiments, the same reference numerals are used for the same members as those described above in the first embodiment, and a duplicate description is omitted. FIG. 15 is a top view including a partial cross-sectional view of a belt conveyance device according to the second embodiment of the present invention, and FIG. 16 is a side view of the belt conveyance device according to the second embodiment of the present invention. Compared to the belt conveying device of the first embodiment, a belt guide member 481r for abutting and guiding the peripheral edge of the endless belt 461 is made of an elastic member such as rubber or silicone resin, as shown in the perspective view of FIG. The annular section has a substantially trapezoidal shape with a required thickness, and the radially provided slits are eliminated. The central cylindrical portion of the belt guide holding member 467 is fitted to the inner diameter portion of the belt guide member 481r, and the belt guide member 481r made of an elastic material is held by the belt guide holding member 467. Further, the surface of the belt guide member 481r is coated with a resin such as fluorine.

  17 to 19 are three views of the main part of the belt conveyance device according to the second embodiment. Similar to the operation of the first embodiment described above, the rotation shaft 463a of the idle roller 463 and the rotation shaft 462a of the drive roller 462 (not shown) are substantially parallel, and the meandering of the endless belt 461 is contained and runs stably. The belt guide member 481r held by the peripheral edge portion of the endless belt 461 and the belt guide holding member 467 always has a predetermined contact force, that is, the force that the roller tilting lever member 474 tries to lower by the weight of the idle roller 463, and the endless belt 461. Are in contact with each other with a force that balances the force pressed against the belt guide member 481r.

  As shown in FIG. 13, when the end portion of the endless belt 461 has a convex portion 461 a, if the belt guide member 483 is made of a rigid material, the endless belt 461 rotates and the end portion of the endless belt 461 has a convex portion. Since the portion 461 a contacts the point A of the belt guide member 483 and moves the belt guide holding member 467, a gap t is opened between the peripheral edge of the endless belt 461 and the belt guide member 483. When the gap t is opened, the thrust force acting on the point A of the belt guide member 483 and the peripheral portion of the endless belt 461 is concentrated on the convex portion 461a of the peripheral portion of the endless belt 461.

  On the other hand, in this embodiment, since the belt guide member 481r is made of an elastic member such as rubber, the guide portion 481s that guides the endless belt 461 has elasticity in the axial direction and is partially bent. Therefore, even when the endless belt 461 rotates and the convex portion 461a at the peripheral edge of the endless belt 461 contacts the point A of the belt guide member 481r, as shown in FIG. 21, the guide of the belt guide member 481r. The contact portion follows so that the portion 481 s follows the shape of the convex portion 461 a at the peripheral edge of the endless belt 461, and can always contact the entire peripheral edge of the endless belt 461.

  Particularly in this embodiment, the radial slits provided in the belt guide member 481 in the previous first embodiment are eliminated, so that the contact area with the peripheral edge of the endless belt 461 is increased, and the first The stress can be further reduced as compared with the embodiment. Also, since the belt guide member 481r is made of an elastic member such as rubber, the coefficient of friction with the peripheral edge of the endless belt 461 increases, and therefore the surface of the belt guide member 481r is coated with a resin such as fluorine. It has been subjected.

  As shown in FIG. 22, the peripheral edge of the endless belt 461 and the belt guide member 481r are in contact at the portions L1 and L2 and the curved portion R of the endless belt 461, and the peripheral edge of the endless belt 461 is at the curved portion R of the endless belt 461. The belt guide member 481r does not slide, but when the endless belt 461 is conveyed in the direction of arrow a, in the range of the portions L1 and L2 stretched tangentially from the curved portion R of the endless belt 461, the b direction In addition, the frictional force is generated at the peripheral edge portion of the endless belt 461 because of sliding in the c direction. Therefore, by applying a resin coating such as fluorine to the surface of the belt guide member 481r as described above, the friction coefficient μ with respect to the endless belt 461 can be reduced, and generation of useless stress can be prevented. The friction coefficient μ is preferably equal to or less than the friction coefficient of a metal (for example, stainless steel) or a resin (polyacetal, etc.) for the endless belt 461 made of polyimide, urethane, or the like. Therefore, the friction coefficient μ is preferably set to about 0.2 or less, for example. Examples of a method for reducing the friction coefficient of the surface of the belt guide member 481r include a method of irradiating rubber with light such as a laser to form a carbon layer on the surface, and a method of chemically modifying the surface.

  As described above, in the second embodiment of the present invention, the belt guide member 481r is made of an elastic member such as rubber, and the slits provided radially as in the previous embodiment are eliminated, thereby eliminating the endless belt 461. The contact area with the peripheral edge is enlarged, and the stress can be reduced as compared with the belt conveying device of the first embodiment, and the life of the endless belt 461 can be further extended.

[Third embodiment]
The configuration of the third embodiment of the present invention will be described with reference to FIGS. FIG. 23 is a top view with a partial cross section of the belt conveyance device according to the third embodiment of the present invention, and FIG. 24 is a side view of the belt conveyance device according to the third embodiment of the present invention. Compared to the first and second embodiments, the belt guide member and the stopper ring are not provided, and as shown in FIGS. 25 to 28, the belt guide holding member 467m has a peripheral edge portion of the endless belt 461. A guide portion 467g for contacting and guiding is provided.

  25 to 28 are a three-side view and a perspective view of the main part of the belt conveyance device according to the third embodiment of the present invention. As shown in FIG. 28, the belt guide holding member 467m is rotatably attached to the idle roller 463, and is provided with a rib-like elastic portion 467n extending radially from the central portion fitting with the shaft of the idle roller 463 toward the outer periphery. . The belt guide holding member 467m is, for example, injection-molded with a resin material that is considered from the viewpoint of slidability and elasticity, such as polyacetal resin. Therefore, the radially extending rib-shaped elastic portion 467n provided on the belt guide holding member 467m for guiding the endless belt has elasticity in the axial direction and can be partially bent. Even when the undulation or uneven portion of the peripheral edge of the endless belt 461 contacts the guide portion 467g of the belt guide holding member 467m, the contact portion follows the shape of the uneven portion of the peripheral edge of the endless belt 461. By always abutting the entire peripheral edge of the endless belt 461, it is possible to run the belt stably without causing stress to concentrate on the peripheral edge of the endless belt 461 and without causing any twisting or cracking.

  In the third embodiment of the present invention described above, the belt guide member and the stopper ring are eliminated, and the guide portion 467g for abutting and guiding the peripheral edge portion of the endless belt 461 is integrally provided on the belt guide holding member 467m. In addition to the effects of the first embodiment, the cost can be reduced by eliminating the belt guide member.

  The present invention has been described as applied to an endless belt of an electrophotographic printer. However, the fixing device of an electrophotographic printer using an endless belt, a sheet conveying device, and a belt device using an endless belt, not limited to an electrophotographic printer. Is available. In the description of the embodiments, the image forming apparatus according to the present invention has been described as a printer. However, the image forming apparatus according to the present invention may be a facsimile machine, a copying machine, or the like, and a composite having a scanner function. It may be a machine.

1 is a schematic diagram illustrating an example of an image forming apparatus according to a first embodiment of the present invention. It is a top view which shows the belt conveyance apparatus of the 1st Embodiment of this invention in a partial cross section. It is a side view of the belt conveyance apparatus of the 1st Embodiment of this invention. It is one of the three views of the principal part of the belt conveying apparatus of the 1st Embodiment of this invention, Comprising: It is a principal part front view. It is one of the three surface views of the principal part of the belt conveying apparatus of the 1st Embodiment of this invention, Comprising: It is a principal part top view. It is one of the three views of the principal part of the belt conveying apparatus of the 1st Embodiment of this invention, Comprising: It is a principal part side view. It is a perspective view of the principal part of the belt conveying apparatus of the 1st Embodiment of this invention. It is a schematic diagram for demonstrating operation | movement of the belt conveying apparatus of the 1st Embodiment of this invention, Comprising: It is a figure which shows the state in which the endless belt is biased to the right side. It is a schematic diagram for demonstrating operation | movement of the belt conveying apparatus of the 1st Embodiment of this invention, Comprising: It is a figure which shows the state which exists in the position which the endless belt and the roller tilting lever member converged. It is a schematic diagram for demonstrating operation | movement of the belt conveying apparatus of the 1st Embodiment of this invention, Comprising: It is a figure which shows the state in which the endless belt is biased to the left side. It is a schematic diagram for demonstrating operation | movement of the belt conveying apparatus of the 1st Embodiment of this invention, Comprising: It is a figure which shows the state which an endless belt meanders to the left side. It is a schematic diagram for demonstrating operation | movement of the belt conveying apparatus of the 1st Embodiment of this invention, Comprising: It is a figure which shows the state in which an endless belt meanders to the right side. It is a top view of the principal part of the general belt conveyance apparatus contrasted with this invention, and is a figure which shows the place where the clearance gap was opened. It is a top view of the principal part of the belt conveyance apparatus of the 1st Embodiment of this invention, and is a figure which shows the place where a part of belt guide member bent. It is a top view including the partial cross section figure of the belt conveying apparatus which concerns on the 2nd Embodiment of this invention. It is a side view of the belt conveyance apparatus which concerns on the 2nd Embodiment of this invention. It is one of the three views of the principal part of the belt conveying apparatus of the 2nd Embodiment of this invention, Comprising: It is a principal part front view. It is one of the three views of the principal part of the belt conveying apparatus of the 2nd Embodiment of this invention, Comprising: It is a principal part top view. It is one of the three views of the principal part of the belt conveying apparatus of the 2nd Embodiment of this invention, Comprising: It is a principal part side view. It is a perspective view of the principal part of the belt conveying apparatus of the 2nd Embodiment of this invention. It is a top view of the principal part of the belt conveyance apparatus of the 2nd Embodiment of this invention, and is a figure which shows the place where a part of belt guide member bent. It is a schematic diagram which shows the positional relationship of the peripheral part of an endless belt and the belt guide member in the belt conveying apparatus of the 2nd Embodiment of this invention. It is a top view including the partial cross section figure of the belt conveying apparatus which concerns on the 3rd Embodiment of this invention. It is a side view of the belt conveyance apparatus which concerns on the 3rd Embodiment of this invention. It is one of the three views of the principal part of the belt conveying apparatus of the 3rd Embodiment of this invention, Comprising: It is a principal part front view. It is one of the three views of the principal part of the belt conveying apparatus of the 3rd Embodiment of this invention, Comprising: It is a principal part top view. It is one of the three surface views of the principal part of the belt conveying apparatus of the 3rd Embodiment of this invention, Comprising: It is a principal part side view. It is a perspective view of the principal part of the belt conveying apparatus of the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Paper tray 101 Paper 103 Lift-up lever 104 Drive motor 200 Paper feeding part 201 Lift detection part 202 Pickup roller 203 Feed roller 204 Retard roller 300 Paper conveyance part 301 Paper sensor 302 Conveyance roller pair 303 Paper sensor 304 Paper sensor 305 Write sensor 400 Image forming unit 430 Toner image forming unit 431 Photosensitive drum 432 Charging roller 433 Exposure head 434 Developing roller 435 Cleaning blade 436 Toner supply unit 461 Endless belt 464 Transfer roller 462 Drive roller 462a Rotating shaft 463 Idle roller 463a Rotating shaft 467, 467m Belt Guide holding member 467g Guide portion 467n Elastic portion 474 Roller tilt lever member 474a Rotating shaft 474b Through holes 481, 481 Belt guide member 481a, 481s guide portion 483 belt guide member 500 fixing unit 504 discharge roller pair 505 stacker

Claims (11)

An endless belt carrying the object to be conveyed;
A plurality of rotating members that stretch and rotate the endless belt;
A belt guide member having elasticity that guides the peripheral edge of the endless belt and relaxes the force in the rotation axis direction of the rotating member received from the endless belt;
A belt conveying device comprising: 2. The belt conveyance device according to claim 1, wherein the belt guide member is disposed at an end portion of at least one rotation member of the plurality of rotation members. The belt conveyance device according to claim 2, wherein a rotation shaft of the rotation member provided with the belt guide member is tiltable. The belt conveyance device according to claim 1, wherein the belt guide member includes a plurality of elastic portions that can be independently displaced. The belt conveying device according to claim 4, wherein the plurality of elastic portions are provided radially so as to surround a rotating shaft of the rotating member. The plurality of elastic portions are connected to each other at least one of a first end close to the rotation axis of the rotation member and a second end away from the rotation axis of the rotation member. The belt conveyance device according to claim 5, wherein: The belt conveyance device according to claim 6, further comprising a belt guide holding member that is rotatable with respect to a rotation shaft of the rotating member, wherein the belt guide member is held by the belt guide holding member. . The belt conveyance device according to claim 7, wherein the belt guide member and the belt guide holding member are integrally formed of a resin material having elasticity. The belt conveyance device according to claim 1, wherein the belt guide member is formed of a rubber material. The belt conveyance device according to claim 9, wherein a friction coefficient μ of a surface of the belt guide member in contact with the endless belt is smaller than 0.2. A belt conveyance device according to any one of claims 1 to 10, and an image forming unit that forms an image on the conveyance object carried on the endless belt by the belt conveyance device. An image forming apparatus.