JP2019211541A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that, during belt replacement, can regulate a thrust position of a belt without adding a special member for regulating a belt end position.SOLUTION: A grip member attached to a belt unit or a stand member supporting the belt unit in a standing state is configured to be removably attached to the belt unit, and the member regulates an end of a belt when the belt is replaced.SELECTED DRAWING: Figure 10

Description

  The present invention relates to an image forming apparatus that conveys and drives an endless belt stretched by a plurality of stretch rollers.

  In recent years, with the increase in the speed of image forming apparatuses, a configuration in which a plurality of image forming units are arranged side by side on an image carrier such as an endless belt, and the image forming process of each color is processed in parallel has become mainstream. A typical example of the image carrier is an intermediate transfer belt in an electrophotographic full-color image forming apparatus.

  In the intermediate transfer belt, toner images of respective colors are sequentially superimposed and transferred onto the belt surface, and a full-color toner image is collectively transferred to a recording material such as a sheet. The intermediate transfer belt constitutes a belt conveying device in a state of being stretched by a plurality of stretching rollers including a driving roller, and is driven to travel.

  In such an intermediate transfer belt type image forming apparatus, the intermediate transfer belt may have an image defect due to a resistance value variation, surface deterioration, and the like due to continuous use. Therefore, when the intermediate transfer belt reaches a predetermined life, it is necessary to replace the intermediate transfer belt with a new one in order to maintain a desired image quality.

  However, the operation of mounting such a belt on the apparatus main body requires skill. Particularly, since positioning in the thrust direction is stretched to a predetermined position by visual observation, it has been difficult to position with high accuracy.

  Therefore, a configuration has been proposed in which the belt abutting portion protrudes by loosening the belt tension when replacing the old and new belts. (Patent Document 1).

JP 2010-217528 A

  However, by adopting a configuration in which a belt abutting member, which is a belt replacement dedicated part, protrudes, the size of the unit is increased and the cost is increased due to an increase in the number of parts.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of regulating the position in the belt width direction without using a belt replacement dedicated component at the time of belt replacement.

  In order to solve the above problems, an image forming apparatus of the present invention is an apparatus main body, a belt unit detachably provided on the apparatus main body, the belt, a plurality of rollers for stretching the belt, and the plurality of the plurality of rollers. A belt unit that includes a frame that supports the roller, and a gripping member that is detachably provided on the belt unit and that grips the belt unit when the belt unit is removed from the apparatus main body. In the image forming apparatus, the gripping member is supported by the belt unit with a first position where the gripping unit is mounted for gripping the belt unit and with one end of the roller facing upward when the belt is replaced. The belt is configured to be attachable to and detachable from the second position where the position in the width direction of the belt can be regulated by contacting the lower end of the belt when It is characterized in that.

In order to solve the above problems, an image forming apparatus according to the present invention includes an apparatus main body, a belt unit detachably provided on the apparatus main body, the belt, and a plurality of rollers that stretch the belt. A frame unit that supports the plurality of rollers, and a stand member for supporting the belt unit with one end side of the rollers facing upward after the belt unit is removed from the apparatus main body. In an image forming apparatus having
The stand member is capable of regulating the position in the width direction of the belt by contacting the lower end portion of the belt when the belt unit is supported by the stand member when the belt is replaced. It is characterized by.

  According to the present invention, it is possible to provide an image forming apparatus capable of regulating the position in the belt width direction without using a belt replacement dedicated component when replacing the belt.

1 is a cross-sectional view of a color image forming apparatus using an electrophotographic system. 3 is a perspective view of an intermediate transfer unit in Embodiment 1. FIG. It is a perspective view of a belt automatic alignment mechanism. It is an edge part enlarged view of a belt self-alignment mechanism. It is an operation principle diagram of a belt automatic alignment mechanism. It is explanatory drawing of a structure of a belt cleaning apparatus. FIG. 2 is an operation explanatory view 1 when replacing an intermediate transfer belt in Embodiment 1. FIG. 3 is a work explanatory diagram 2 when replacing the intermediate transfer belt in Embodiment 1. FIG. 3 is a detailed view of a handle in the first embodiment. FIG. 3 is a detailed attachment diagram of the handle in the first embodiment. 4 is a detailed view of a belt positioning unit in Embodiment 1. FIG. 5 is a perspective view of an intermediate transfer unit in Embodiment 2. FIG. FIG. 6 is a detailed view of a handle portion in Embodiment 2. FIG. 6 is a detailed view of a part of a belt cleaning device in Embodiment 2. 6 is a detailed view of an assembled state in Embodiment 2. FIG. 6 is a perspective view of an assembled state in Embodiment 2. FIG. FIG. 6 is a detailed view of a belt positioning unit in Embodiment 2.

[Example 1]
<About image forming apparatus>
An image forming apparatus 200 equipped with an intermediate transfer unit 20 (belt conveying apparatus 20) as a belt unit according to the present invention will be described. FIG. 1 is a cross-sectional view of a color image forming apparatus using an electrophotographic system. The image forming apparatus 200 forms an image by a so-called intermediate transfer tandem system in which four color image forming units are arranged side by side on an intermediate transfer belt 7. Device. The intermediate transfer tandem system has become a mainstream structure in recent years because it can cope with high productivity and transport of various media.

<Recording material transport process>
The recording material S is stored on the storage 60 so as to be stacked, and is fed in accordance with the image formation timing by a feeding roller 61 employing a frictional separation method. The recording material S sent out by the feeding roller 61 passes through the transport path and is transported to the registration roller 62. After the skew correction and timing correction are performed in the registration roller 62, the recording material S is sent to the secondary transfer portion T2. The secondary transfer portion T2 is a transfer nip portion formed by the opposing driving roller 8 and secondary transfer outer roller 9, and a toner image is formed on the recording material S by applying a predetermined pressure and an electrostatic load bias. To adsorb.

<Image creation process>
A process of forming an image sent to the secondary transfer portion T2 at the same timing as the conveyance process of the recording material S to the secondary transfer portion T2 described above will be described. The image forming units Pa to Pd mainly include photosensitive drums 1a to 1d as image carriers, charging devices 2a to 2d, exposure devices 3a to 3d, developing devices 100a to 100d, developing containers 101a to 101d, and primary transfer rollers. 5a to 5d, and photoreceptor cleaners 6a to 6d.

  The surfaces of the photosensitive drums 1a to 1d that are rotationally driven in the R1 to R4 directions are uniformly charged in advance by the charging devices 2a to 2d. On the photosensitive drums 1a to 1d, electrostatic images are formed by the exposure devices 3a to 3d based on image information signals.

  Next, the electrostatic images formed on the photosensitive drums 1a to 1d are developed as toner images through toner development by the developing devices 100a to 100d. Thereafter, predetermined pressure and electrostatic load bias are applied by the primary transfer rollers 5a to 5d, and the toner image is transferred onto the intermediate transfer belt 7 in the primary transfer portions T1a to T1d. Finally, the transfer residual toner slightly remaining on the photoconductor drums 1a to 1d is collected by the photoconductor cleaners 6a to 6d and prepared for the next image forming process again.

  When the amount of toner in the developing devices 100a to 100d decreases, toner is supplied from the corresponding storage containers (toner storage containers) Ta to Td (Tb to Td have the same shape as Ta). At this time, the replenishing devices 70a to 70d (70b to 70d have the same shape as 70a and are therefore abbreviated as 70. Note that 70b to 70d are omitted in FIG. 1. The suffix corresponds to the suffix of the developing device). Performs toner replenishment while synchronizing driving with the corresponding developing devices 100a to 100d.

  In the case of FIG. 1, the image forming units Pa to Pd described above exist in four sets of yellow (Y), magenta (M), cyan (C), and black (BK). However, the number of colors is not limited to four, and the color arrangement order is not limited to this. Further, a two-component developer obtained by mixing a non-magnetic toner and a magnetic carrier in advance is accommodated in the developing containers 101a to 101d. In this embodiment, a description will be given of a case where a two-component developer (initial agent) is accommodated. In addition, when the same reference numerals are used in the drawings, the same numbers may be assigned and the description may be omitted.

  Next, the intermediate transfer belt 7 will be described with reference to FIG. The intermediate transfer belt 7 is stretched by a drive roller 8 that also serves as a drive transmission means to the intermediate transfer belt 7, a steering roller 17, a pre-secondary transfer roller 18 (hereinafter referred to as a pre-secondary transfer roller 18), and an idle roller 19. The When the driving roller 8 is driven in the arrow R8 direction, the intermediate transfer belt 7 is driven in the arrow R7 direction. The intermediate transfer belt 7 is an endless belt.

  The image forming process of each color processed in parallel by the image forming units Pa to Pd of Y, M, C, and BK is performed at the timing of sequentially superposing on the upstream color toner image that is primarily transferred onto the intermediate transfer belt 7. . As a result, a full-color toner image is finally formed on the intermediate transfer belt 7 and conveyed to the secondary transfer portion T2. Note that the untransferred toner after passing through the secondary transfer portion T2 is collected by the belt cleaning device 11.

<Process after secondary transfer>
As described above, with the conveyance process and the image forming process described above, the timing of the recording material S and the full-color toner image coincide with each other in the secondary transfer portion T2, and the secondary transfer is performed. Thereafter, the recording material S is conveyed to the fixing device 13. The fixing device 13 melts and fixes the toner image on the recording material S by applying a predetermined pressure and heat to the passing recording material S in a fixing nip formed by opposing rollers.

  Accordingly, the fixing device 13 includes a heater serving as a heat source, and is controlled so that an optimum temperature is always maintained. The recording material S thus image-fixed is selected to be discharged onto the paper discharge tray 63, or when it is necessary to form a double-sided image, the recording material S is transported to a reverse conveying device (not shown).

<Configuration of belt conveyor and steering (alignment)>
Next, the steering configuration of the intermediate transfer belt 7 will be described. FIG. 2 is a perspective view of an intermediate transfer unit 20 as a belt conveying device in which the intermediate transfer belt 7 is installed. 2A shows a state where the intermediate transfer belt 7 is stretched, and FIG. 2B shows a state where the intermediate transfer belt 7 is removed.

  As shown in FIGS. 2A and 2B, the driving roller 8, the pre-revolution roller 18, and the idle roller 19 are sandwiched between the front frame 21F and the rear frame 21R, respectively, and can rotate at both ends in the axial direction. It is pivotally supported.

  The steering roller 17 is rotatably supported via a swinging plate 26 with respect to a frame support plate 28 passed between both ends of the front frame 21F and the rear frame 21R.

  A drive coupling 22 is attached to one end of the drive roller 8 in the axial direction. The drive coupling 22 is connected to an output shaft of a belt drive unit (not shown) to transmit drive force. The surface of the driving roller 8 is made of a material having a relatively high friction coefficient such as rubber, and the roller surface conveys the intermediate transfer belt 7 in the direction of arrow R7 in FIG. To drive. In the present embodiment, the drive coupling 22 is used as the drive transmission means, but may be connected using a gear.

  In the present embodiment, the intermediate transfer belt 7 driven and conveyed as described above is provided with a belt automatic alignment mechanism that performs belt alignment by the steering roller 17 maintaining its frictional force balance at both ends. ing.

  Next, the belt automatic alignment mechanism will be described with reference to FIGS. FIG. 3 is a perspective view for explaining the extracted automatic belt alignment mechanism in the present embodiment, and FIG. 4 is a perspective view of the automatic belt alignment mechanism.

  As shown in FIGS. 3 and 4, the steering roller 17 also serving as a tension roller has a roller shaft 17 b protruding from both ends in the axial direction. Steering bearings 23 are respectively disposed at positions facing both ends of the steering roller 17 in the axial direction. The roller shafts 17b protruding from both ends in the axial direction are rotatably supported by the steering bearing 23 in a manner of being inserted into support holes 10a provided in the steering bearing 23.

  The pair of steering bearings 23 are attached to the swing plate 26 so as to support both ends in the axial direction of the steering roller 17 as the first stretching roller. That is, the respective steering bearings 23 at both ends in the axial direction of the steering roller 17 are supported by the slide guides 24 respectively attached to both ends of the swing plate 26. A tension spring 25 which is a compression spring is provided between the steering bearing 23 and the slide guide 24 in a contracted state.

  The swing plate 26 constitutes a swing member that supports the steering roller 17 so that the relative alignment with the drive roller 8 can be changed. The tension spring 25 constitutes an urging member that applies a tension acting on the inner periphery of the intermediate transfer belt 7 to the steering roller 17. The tension spring 25 of the present embodiment is composed of a pair of spring members that respectively apply an urging force to the pair of steering bearings 23 at both ends of the swing plate 26.

  As shown in FIG. 4, the slide guide 24 has a fitting groove that guides the steering bearing 23 only along the pressing direction of the tension spring 25 (the direction of the arrow K). That is, the slide guide 24 constitutes a guide portion that guides the pair of steering bearings 23 in the biasing direction of the tension spring 25. Further, a stopper (not shown) in the pressurizing direction of the tension spring 25 is provided so that the steering bearing 23 does not come out in the assembly state of only the belt automatic alignment mechanism shown in FIG. With these configurations, the urging forces of the tension springs 25 at both ends can be effectively transmitted to the corresponding steering bearings 23.

  As shown in FIG. 2A, the intermediate transfer belt 7 is stretched by the driving roller 8, the steering roller 17, the pre-secondary rotation roller 18, and the idle roller 19. In this state, the steering bearing 23 moves from the position restricted by the stopper in the direction in which the tension spring 25 is compressed (in the direction of arrow K in FIG. 4), and applies a predetermined tension to the intermediate transfer belt 7. In this embodiment, with this configuration, as described above, the steering roller 17 also serves as a tension roller.

  The swing plate 26 as a swing member is fixed in a state where a rotating shaft member 27 protrudes rearward at a central portion, and slide guides 24 are fixed at both ends. The rotating shaft member 27 is fitted into a fitting portion (not shown) provided on a frame support plate 28 (see FIGS. 2B and 4) provided in the intermediate transfer unit 20, thereby steering. The rocking plate 26 that supports the roller 17 is rotatably supported.

  As shown in FIG. 3, such a belt automatic alignment mechanism has a steering roller support unit AL (alignment changing means). That is, the steering roller support unit AL supports the swing plate 26 that supports the steering roller 17 so as to be rotatable around the steering axis J (arrow R0 in FIG. 3).

<Detailed configuration of automatic alignment part>
Next, a detailed configuration of the belt automatic alignment mechanism in the present embodiment will be described.

  As shown in FIG. 4, the pair of steering bearings 23 that support the roller shaft 17 b are arranged so that a force for changing the alignment is applied to the steering roller 17 in order to automatically align the intermediate transfer belt 7. 7 has a rubbing surface 231 that rubs against the inner surface of. The rubbing surface 231 as the rubbing surface is formed in a tapered shape in which the radial distance from the outer peripheral surface of the steering roller 17 gradually increases toward the outer side in the axial direction of the steering roller 17. Thereby, the function of belt automatic alignment can be improved more.

  In the present embodiment, the outer diameter of the steering roller 17 is set to φ16 (16 mm), for example. The steering bearing 23 has a curved surface portion (sliding surface 231) having the same φ16 curved surface at the joint portion with the steering roller 17, and the taper angle ψ = 10 ° from the curved surface portion (see FIG. 5B). It has a shape that gradually increases in diameter toward the outside at a rate of.

  In the present embodiment, the dimension in the width direction orthogonal to the conveyance driving direction (the direction of the arrow R7 in FIG. 5) of the intermediate transfer belt 7 is set so as to partially extend to the curved region having the taper angle ψ. Yes. As described above, the steering bearing 23 has a degree of freedom only in the direction of the arrow K in FIG. Therefore, the steering bearing 23 can simply slide on the inner peripheral surface of the intermediate transfer belt 7 without being driven during the conveyance driving of the intermediate transfer belt 7 in the arrow R7 direction.

<Operation principle of automatic belt alignment>
Next, the operation principle that enables automatic belt alignment by the frictional force generated at the time of rubbing will be described in detail below with reference to FIGS.

  As described above, since the steering bearing 23 is supported so as not to be able to follow the intermediate transfer belt 7, the steering bearing 23 always receives a frictional resistance from the inner peripheral surface of the intermediate transfer belt 7 during the conveyance drive.

  FIG. 5 is a plan view (upper view) corresponding to the state seen in the direction of the arrow TV in FIG. 2, and FIG. 5 (a) is a steady state balanced by automatic alignment and shows the state of the intermediate transfer belt 7. This shows the state where the hanging position is at the nominal (center) position. FIG. 5B shows a state in which when the intermediate transfer belt 7 is conveyed in the direction of the arrow R7, the belt is shifted to the left side in the drawing.

  In this embodiment, as shown in FIG. 5A, the width Lb of the intermediate transfer belt 7 is set longer than the axial width Lr of the steering roller 17 and shorter than the width Lr + 2Lf between both ends of the steering bearing 23. Has been. In the nominal state, the intermediate transfer belt 7 always rubs against both the steering bearings 23 with a predetermined engagement width (for example, 2 mm in this embodiment).

  On the other hand, in FIG. 5B in which the belt is offset, the relationship of the engagement width between the intermediate transfer belt 7 and the steering bearing 23 is in a biased state in which only the left side in the drawing has the engagement width D. Assume.

  In this case, the left side of the steering bearing 23 receives a frictional force from the belt, and the direction of the force is downward in the ST1 direction shown in FIG. On the other hand, the right side receives no force from the belt. It can be explained that such a frictional force difference between both ends is a driving force for generating a moment around the steering axis J (a direction in which the left side, which is the approaching side in the assumption of FIG. 5B, is lowered).

  In this way, the intermediate transfer belt 7 and the pair of steering bearings 23 have the following positional relationship in the state of FIG. 5A in which the intermediate transfer belt 7 is evenly positioned in the center of the steering roller 17 in the axial direction. ing. That is, the both ends in the width direction of the intermediate transfer belt 7 are in a positional relationship covering a part of the rubbing surfaces (rubbing surfaces 231) of the pair of steering bearings 23.

  Hereinafter, the moment around the steering axis J is referred to as steering torque.

  Since the steering angle direction of the steering roller 17 generated by the above principle matches the direction in which the intermediate transfer belt 7 is returned to its original position, an automatic alignment effect can be obtained. In the present embodiment, the steering bearing 23 is provided with a taper angle ψ so as to be set to a relatively low friction coefficient μS so as to avoid an abrupt steering operation.

  Specifically, a resin material such as POM (polyacetal) having rubbing properties is used as the material of the steering bearing 23, and the friction coefficient μS is set to about 0.3 and the taper angle ψ is set to about 5 to 10 °. As a result, good results can be obtained. Furthermore, in consideration of electrostatic adverse effects due to frictional charging with the intermediate transfer belt 7, the steering bearing 23 is also provided with conductivity.

<Belt cleaning device>
FIG. 6 is an explanatory diagram of the configuration of the belt cleaning device.

  As shown in FIG. 6A, the belt cleaning device 11 rubs the cleaning blade 12 against the intermediate transfer belt 7 to collect the transfer residual toner. The cleaning blade 12 is arranged in the counter direction with respect to the moving direction R7 of the intermediate transfer belt 7 whose inner surface is supported by the steering roller 17. The belt cleaning device 11 brings the tip of the cleaning blade 12 into contact with the outer surface of the intermediate transfer belt 7 and collects transfer residual toner and the like remaining on the intermediate transfer belt 7 without being transferred to the recording material S. The cleaning blade 12 is made of urethane rubber. The hardness of the urethane rubber is 75 degrees in terms of JIS-A hardness, and the thickness of the urethane rubber is 2 mm. The contact angle of the cleaning blade 12 is 25 °, and the contact pressure is 3 N / m (30 gf / cm). However, the present invention is not limited to these.

  As shown in FIG. 6B, the swing plate 26 is tiltable with respect to the frame support plate 28 about the steering shaft 27. The end of the belt cleaning device 11 is attached to the steering bearing 23. The steering bearing 23 is movable along a slide guide 24 fixed to the swing plate 26 while rotatably supporting the end portion of the steering roller 17. The belt cleaning device 11 tilts integrally with the steering roller 17 and presses the tip of the cleaning blade 12 through the intermediate transfer belt 7 at a constant position of the steering roller 17 at all times. The cleaning blade 12 is disposed so as to be always parallel to the steering roller 17, and ensures a uniform friction state over the entire contact length of the cleaning blade 12 with respect to the intermediate transfer belt 7. Even when the intermediate transfer belt 7 is shifted and the steering roller 17 is tilted, the contact state between the intermediate transfer belt 7 and the cleaning blade 12 is kept the same, and the residual transfer toner is collected. .

<Belt exchange>
The intermediate transfer belt 7 is a consumable item. When the service life is reached after long-term use or when it becomes unusable due to careless scratches or dents, the intermediate transfer unit 20 can be used continuously by replacing the belt. As described above, attention must be paid to the position of the intermediate transfer belt 7 in the thrust direction with respect to the intermediate transfer unit 20 when performing belt replacement. If the initial thrust position of the intermediate transfer belt 7 is greatly deviated, the belt may be damaged due to image color misalignment or belt misalignment. Therefore, a belt replacement method capable of simple and highly accurate thrust positioning of the intermediate transfer belt 7 proposed here will be described below.

  7A to 7E show a procedure for removing the intermediate transfer belt 7. The belt cleaning device 11 and the handle 29 as a gripping member are removed from the state where the intermediate transfer unit 20 is placed flat (a → b). The handle 29 is detachably provided on the intermediate transfer unit 20 and is a part to be gripped when the intermediate transfer unit 20 is attached to and detached from the apparatus main body. The tension spring 25 on both sides, the steering bearing 23 on the handle 29 side, and the slide guide 24 are removed (b → c). The intermediate transfer unit 20 is set up with the handle 29 side up, the steering roller 17 is pulled upward, and the intermediate transfer belt 7 is loosened (c → d). That is, the steering roller 17 is pulled upward with one end side in the axial direction of the steering roller 17 facing upward. The intermediate transfer belt 7 is pulled upward to complete the removal of the intermediate transfer belt 7 (d → e).

  8A to 8C show a procedure for attaching the intermediate transfer belt 7. FIG. A handle 29 is attached to the root of the drive roller 8 from the state shown in FIG. 7E (a → b). Details will be described later. Thereafter, the intermediate transfer belt 7 is attached by performing the reverse operation of the removal. The intermediate transfer belt 7 is attached. The steering roller 17 is inserted and attached between the swing plate 26 and the intermediate transfer belt 7. A steering bearing 23 and a slide guide 24 are attached, and tension springs 25 on both sides are attached. The handle 29 is removed from the base of the driving roller 8 and attached to the original position.

  The above is the outline of belt replacement. The characteristic features will be described in detail. FIG. 9 shows a perspective view of the handle 29. The handle 29 has a C-shaped holding portion 29b in addition to the positioning hole 29a fitted to the front frame 21F, and a frame seat surface 29c and a belt seat surface 29d are provided so as to sandwich the holding portion 29b. The thickness t of the frame seat surface 29c and the belt seat surface 29d is the same as the nominal distance between the front frame 21F and the end surface of the intermediate transfer belt 7 when the intermediate transfer unit 20 is assembled.

  FIG. 10 shows an enlarged view of the attachment portion of the handle 29. FIG. 10 (a) is a view before attachment, FIG. 10 (b) is after attachment, and FIG. The front frame 21F has a cylindrical temporary fastening portion 21Fa coaxial with the drive roller 8, and is attached so that the holding portion 29b of the handle 29 is pushed into the temporary fastening portion 21Fa. After the attachment, the frame seat surface 29c is pressed so as to be in close contact with the front frame 21F. When the frame seat surface 29c is lifted from the front frame 21F, the thrust position of the intermediate transfer belt 7 is shifted. In order to eliminate the risk, a step 21Fb may be provided in the temporary fixing portion 21Fa as shown in FIG. 11 so that the handle 29 is uniquely determined. Further, the handle 29 may be directly attached to the shaft of the driving roller 8 instead of the front frame 21F.

  When the intermediate transfer belt 7 is inserted with the handle 29 attached in this way, the end surface (lower end) of the intermediate transfer belt 7 is pressed against the belt seat surface 29d by gravity as shown in FIG. The intermediate transfer belt 7 is held at the position. That is, when the handle 29 is attached to the front frame 21 </ b> F, the handle 29 can abut the intermediate transfer belt 7 and regulate the position of the intermediate transfer belt 7 in the width direction.

  The point here is to have the attachment position of the handle 29 in the drive roller 8 part. The surface of the driving roller 8 is made of rubber having a high friction coefficient μ in order to drive the intermediate transfer belt 7. When exchanging the belt, the intermediate transfer belt 7 is difficult to move in the thrust direction at the drive roller 8 having a high μ. Therefore, it is important to position the intermediate transfer belt 7 at the nominal thrust position when the intermediate transfer belt 7 is inserted. . By attaching the handle 29 as in this embodiment, the thrust position can be accurately determined at the time of belt insertion. When the handle 29 is not used, the intermediate transfer belt 7 falls to the same surface as the front frame 21F due to gravity, and it is necessary to correct the thrust position in a subsequent process. However, correction becomes difficult because of high μ. As long as the handle 29 is used to determine the thrust position at the drive roller 8 part, the thrust position at the roller part with low μ on the surface of the other steering roller 17, the pre-secondary rotation roller 18, and the idle roller 19 is simple. It is decided. This is because by attaching a tension spring 25 and applying tension to the belt, the intermediate transfer belt 7 causes a side slip at each roller portion and moves to an appropriate thrust position in accordance with the thrust position of the drive roller 8 portion.

  With the above configuration, it is possible to provide an image forming apparatus that can perform belt positioning with low thrust, good workability, and high thrust positioning accuracy without using belt replacement dedicated parts.

[Example 2]
In this embodiment, the belt positioning means is different from that of the first embodiment.

<Belt exchange>
FIG. 12 is a perspective view of the intermediate transfer unit 20 having a shape different from that of the first embodiment. The configuration is substantially the same as that of the first embodiment, and the intermediate transfer belt 7, the belt cleaning device 11, and the handle 29 are attached to the frame 21. The intermediate transfer belt 7, the belt cleaning device 11, and the handle 29 are configured to be removable from the frame 21.

  FIG. 13 is a detailed view of the handle portion 21 a of the frame 21. The handle portion 21a has a positioning boss 21b and a mounting hole 21c. FIG. 14 is a detailed view of a part of the belt cleaning device 11. At the center of the cleaning container 11a, there are a through hole 11b, a positioning hole 11c, a snap fit 11d, and a belt restricting portion 11e. FIG. 15 shows a state in which the handle portion 21a and the cleaning container 11a are combined and positioned. The handle portion 21a is inserted into the through hole 11b, and the positioning boss 21b is positioned in the positioning hole 11c. Further, a snap fit 11d is fitted in the mounting hole 21c to prevent the frame 21 and the belt cleaning device 11 from coming off. As a result of the combination, the frame 21 and the belt cleaning device 11 become T-shaped as shown in the perspective view of FIG. 16, and the belt cleaning device 11 functions as a stand for the frame 21. That is, the belt cleaning device 11 functions as a stand member for raising the frame 21.

  As shown in FIG. 16, the drive roller 8 is located in the vicinity of the handle portion 21a. This is a location where the thrust of the intermediate transfer belt 7 should be positioned at the time of belt replacement. Since the belt replacement method is the same as that of the first embodiment, the description thereof is omitted.

  FIG. 17 is a detailed view of the positioning portion of the intermediate transfer belt 7. By attaching the belt cleaning device 11 to the handle portion 21a, the belt regulating portion 11e provided in the cleaning container 11a is disposed in the vicinity of the drive roller 8 portion. By inserting the intermediate transfer belt 7 into the frame 21 in this state, the end surface of the intermediate transfer belt 7 abuts against the belt regulating portion 11e and the thrust position is determined.

  With the above configuration, it is possible to provide an image forming apparatus that can perform belt positioning with low thrust, good workability, and high thrust positioning accuracy without using belt replacement dedicated parts.

DESCRIPTION OF SYMBOLS 7 Intermediate transfer belt 8 Drive roller 11 Belt cleaning device 11a Cleaning container 11b Through hole 11c Positioning hole 11d Snap fit 11e Belt regulating part 17 Steering roller 18 Roll before rotation 19 Idle roller 20 Intermediate transfer unit (belt conveyance device)
21 Frame 21a Handle part 21b Positioning boss 21c Mounting hole 21F Front frame 21Fa Temporary fastening part 21Fb Step 21R Rear frame 23 Steering bearing 24 Slide guide 25 Tension spring 26 Swing plate 29 Handle 29a Positioning hole 29b Holding part 29c Frame seating surface 29d Belt seat

Claims (7)

The device body;
A belt unit detachably provided on the apparatus main body, the belt unit including a belt, a plurality of rollers for stretching the belt, and a frame for supporting the plurality of rollers;
A gripping member that is detachably provided on the belt unit, and for gripping the belt unit when the belt unit is removed from the apparatus main body;
In an image forming apparatus having
When the belt unit is supported with the one end side of the roller facing upward at the time of replacement of the belt and the first position where the gripping member is mounted to grip the belt unit, An image forming apparatus, wherein the image forming apparatus is configured to be attachable to and detachable from a second position where the position in the width direction of the belt can be regulated by contacting the lower end of the belt.   2. The image forming apparatus according to claim 1, wherein the plurality of rollers include a driving roller having a surface made of rubber and driving the belt, and the gripping member is attached to an end of the driving roller. apparatus.   The image forming apparatus according to claim 1, wherein the belt is a transfer belt for transferring an image to a recording material. The device body;
A belt unit detachably provided on the apparatus main body, the belt unit including a belt, a plurality of rollers for stretching the belt, and a frame for supporting the plurality of rollers;
An image forming apparatus comprising: a stand member for supporting the belt unit in a state where one end side of the roller is directed upward after removing the belt unit from the apparatus main body;
The stand member is capable of regulating the position in the width direction of the belt by contacting the lower end portion of the belt when the belt unit is supported by the stand member when the belt is replaced. An image forming apparatus.   The image forming apparatus according to claim 4, wherein the stand member is a cleaning device that cleans the belt, and is detachably supported by the belt unit.   The plurality of rollers include a driving roller whose surface is made of rubber and drives the belt, and the stand member restricts the belt at a position facing the driving roller in the axial direction of the driving roller. The image forming apparatus according to claim 4, further comprising:   The image forming apparatus according to claim 4, wherein the belt is a transfer belt for transferring an image to a recording material.

Images