Belt device and image forming apparatus

Abstract

This reduces the likelihood of the intermediate transfer belt shifting. [Solution] The system includes a drive roller 21 that drives the intermediate transfer belt 17, a tension roller 24 that applies tension to the intermediate transfer belt 17, and a backup roller 25 whose end is rotatably supported by a relay member 46. A housing 40 is provided that rotatably supports both ends of the multiple roller members 21-26, 14Y, 14M, 14C, and 14BK. A slide plate 42 is provided that is slidably held relative to the housing 40 and also holds the relay member 46, and by sliding relative to the housing 40, the position in which the backup roller 25 contacts the inner circumferential surface of the intermediate transfer belt 17 in a cross section perpendicular to the axial direction is varied. An adjustment screw 48 is provided that allows manual adjustment of the fixed position of the relay member 46, which is fixedly held by the slide plate 42.

Description

【Technical Field】 【0001】 The present invention relates to a belt device provided with a belt member such as an intermediate transfer belt, and an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine having the same. 【Background Art】 【0002】 Conventionally, in image forming apparatuses such as copying machines and printers, there is known a belt device in which a belt member such as an intermediate transfer belt is stretched and supported by a plurality of roller members and caused to run in a predetermined direction (for example, see Patent Document 1). 【0003】 On the other hand, Patent Document 1 discloses a technique for correcting the belt deviation of an intermediate transfer belt by inclining a tension roller, which is one of a plurality of roller members that stretch and support the intermediate transfer belt (belt member), in the axial direction. 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0004】 In the conventional belt device, the belt deviation of the belt member has occurred due to dimensional accuracy, assembly accuracy, deformation, etc. of a plurality of roller members and other constituent members that stretch and support the belt member. In particular, such a belt deviation becomes significant when the plurality of roller members that stretch and support the belt member include a roller member whose contact position with respect to the belt member is variable. Even if a mechanism for correcting the belt deviation of the belt member by inclining the tension roller in the axial direction is provided, the problem cannot be sufficiently solved. 【0005】 The present invention has been made to solve the above-described problems, and an object thereof is to provide a belt device and an image forming apparatus in which belt deviation hardly occurs in a belt member. 【Means for Solving the Problems】 【0006】 The belt device of this invention comprises a belt member stretched and supported by a plurality of roller members, one of the plurality of roller members which is a drive roller that drives the belt member, one of the plurality of roller members which is a tension roller that applies tension to the belt member, one of the plurality of roller members which is a backup roller whose end is directly or indirectly rotatably supported by an intermediate member, a housing which rotatably supports both ends of the plurality of roller members directly or indirectly, a sliding plate which is held slidably relative to the housing and holds the intermediate member, and which changes the position in which the backup roller contacts the inner circumferential surface of the belt member when viewed in a cross section perpendicular to the axial direction as it slides relative to the housing, and an adjustment mechanism which allows manual adjustment of the fixed position of the intermediate member which is fixedly held by the sliding plate. [Effects of the Invention] 【0007】 According to the present invention, it is possible to provide a belt device and an image forming apparatus that are less prone to belt shifting in the belt member. [Brief explanation of the drawing] 【0008】 [Figure 1] This is an overall configuration diagram showing an image forming apparatus according to an embodiment of the present invention. [Figure 2] This is a diagram showing the configuration of the image-making unit. [Figure 3] (A) A diagram showing the intermediate transfer belt device in full-color mode, and (B) A diagram showing the intermediate transfer belt device in monochrome mode. [Figure 4] This is a diagram showing the intermediate transfer belt device from above. [Figure 5] This is a diagram showing the intermediate transfer belt device from the side. [Figure 6] This is a diagram showing an intermediate transfer belt device as a modified example (modification 1). [Figure 7]This is a cross-sectional view showing a belt alignment correction mechanism in an intermediate transfer belt device, as a modified example (2). [Figure 8] This is a side view showing one end of a tension roller in the width direction. [Figure 9] This is a cross-sectional view showing the operation in which the belt-bias of the intermediate transfer belt is corrected. [Modes for carrying out the invention] 【0009】 Hereinafter, embodiments for carrying out this invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations will be simplified or omitted as appropriate. 【0010】 First, Figure 1 will explain the overall configuration and operation of the image forming apparatus 1. In Figure 1, 1 represents a color copier as an image forming apparatus, 3 represents a document transport unit that transports the original document to the document reading unit 4, 4 represents a document reading unit that reads the image information of the original document, and 6 represents a writing unit (exposure unit) that emits laser light based on the input image information. Furthermore, 7 is a paper feeder in which a sheet P such as paper is stored, 10Y, 10M, 10C, and 10BK are process cartridges that serve as image-forming units corresponding to each color (yellow, magenta, cyan, and black), 16 is an intermediate transfer belt device which is a belt device in which an intermediate transfer belt 17 is installed as a belt component, 17 is an intermediate transfer belt which is a belt component on which toner images of multiple colors are transferred in layers, and 18 is a secondary transfer roller that transfers the toner image formed on the intermediate transfer belt 17 to the sheet P. Furthermore, 20 represents a fixing device for fixing unfixed images on sheet P, 28 represents toner containers for supplying toner of each color to the developing devices for each process cartridge 10Y, 10M, 10C, and 10BK, and 30 represents a waste toner collection container from which waste toner is collected. 【0011】 Here, each process cartridge 10Y, 10M, 10C, and 10BK (image-forming unit) integrates a photosensitive drum (11Y) as the image carrier, a charging device (12Y), a developing device (13Y), and a cleaning device (15Y) (see Figure 2). Each process cartridge 10Y, 10M, 10C, and 10BK is replaced with a new one when it reaches the end of its lifespan. On the photoconductor drums 11Y, 11M, 11C, and 11BK (see Figure 3(A)) in each process cartridge 10Y, 10M, 10C, and 10BK, toner images of each color (yellow, magenta, cyan, and black) are formed, respectively. 【0012】 The following describes the operation of the image forming apparatus during normal color image formation. First, the document is transported from the document glass by the transport rollers of the document transport unit 3 and placed on the contact glass of the document reading unit 4. Then, the image information of the document placed on the contact glass is optically read by the document reading unit 4. Then, the image information for each color—yellow, magenta, cyan, and black—is transmitted to the writing unit 6. From the writing unit 6, laser light (exposure light) based on the image information for each color is irradiated onto the photosensitive drum 11 of the corresponding process cartridges 10Y, 10M, 10C, and 10BK. 【0013】 Meanwhile, the four photoreceptor drums 11Y, 11M, 11C, and 11BK (see Figure 3(A)) are each rotating clockwise as shown in Figures 1 to 3. Then, referring to Figure 2, the surface of the photoreceptor drum 11 is first uniformly charged at the position opposite the charging device 12Y (charging roller) (this is the charging process). In this way, a charge potential is formed on the photoreceptor drum 11Y. Subsequently, the charged surface of the photoreceptor drum 11Y reaches the irradiation position of each laser beam. In the writing unit 6, laser light L corresponding to the image signal is emitted from the light source for each color. The laser light L enters the polygon mirror and is reflected, and then passes through a plurality of lenses. The laser light after passing through the plurality of lenses will pass through different optical paths for each of the yellow, magenta, cyan, and black color components (this is the exposure process). 【0014】 The laser light corresponding to the yellow component is irradiated onto the surface of the photosensitive drum 11Y of the first process cartridge 10Y from the left side of the paper surface. Thus, an electrostatic latent image corresponding to the yellow component is formed on the photosensitive drum 11Y after being charged by the charging device 12Y. Similarly, the laser light of the cyan component is irradiated onto the surface of the photosensitive drum 11C of the second process cartridge 10C from the left of the paper surface, and an electrostatic latent image of the cyan component is formed. The laser light corresponding to the magenta component is irradiated onto the surface of the photosensitive drum 11M of the third process cartridge 10M from the left of the paper surface, and an electrostatic latent image corresponding to the magenta component is formed. The laser light of the black component is irradiated onto the surface of the photosensitive drum 11BK of the fourth process cartridge 10BK from the left of the paper surface, and an electrostatic latent image of the black component is formed. 【0015】 After that, the surfaces of the photosensitive drums 11Y on which the electrostatic latent images of each color are formed respectively reach the positions facing the developing devices 13Y (see Figure 2). Then, toners of each color are supplied onto the photosensitive drums 11Y from each developing device 13Y, and the latent images on the photosensitive drum Y are developed (this is the developing process). After that, the surfaces of the photosensitive drums 11Y after the developing process respectively reach the positions facing the intermediate transfer belt 17 (intermediate transfer body) as the image carrier. Here, primary transfer rollers 14Y are installed at each facing position so as to abut against the inner peripheral surface of the intermediate transfer belt 17. And at the position of the primary transfer roller 14Y, the toner images of each color formed on the photosensitive drum 11 are sequentially superimposed and transferred onto the intermediate transfer belt 17 (this is the primary transfer process). 【0016】 After that, the surface of the photoreceptor drum 11 after the primary transfer process reaches the position facing the cleaning device 15Y (see Fig. 2) respectively. Then, the cleaning device 15Y collects the untransferred toner remaining on the photoreceptor drum 11Y (this is the cleaning process). After that, the surface of the photoreceptor drum 11Y passes through the position of the charge eliminator, and a series of image forming processes on the photoreceptor drum 11Y are completed. 【0017】 On the other hand, the surface of the intermediate transfer belt 17 on which the images of each color on the photoreceptor drum 11Y are superimposed and transferred travels in the direction of the arrow in Fig. 1 and reaches the secondary transfer nip (the position where the secondary transfer roller 18 presses against the intermediate transfer belt 17). Then, at the position of the secondary transfer roller 18 (secondary transfer nip), the full-color image on the intermediate transfer belt 17 is secondarily transferred onto the sheet P (this is the secondary transfer process). After that, the surface of the intermediate transfer belt 17 reaches the position of the intermediate transfer cleaning device 9 (cleaning device). Then, the untransferred toner on the intermediate transfer belt 17 is collected by the intermediate transfer cleaning device 9, and a series of transfer processes on the intermediate transfer belt 17 are completed. 【0018】 Here, the sheet P conveyed to the position of the secondary transfer roller 18 is conveyed from the paper feeding device 7 via a conveyance guide, a registration roller 19, etc. Specifically, the sheet P fed by the paper feeding roller 8 from the paper feeding device 7 that stores the sheet P is guided to the registration roller 19 after passing through the conveyance guide. The sheet P that reaches the registration roller 19 is conveyed toward the position of the secondary transfer roller 18 in synchronization with the toner image on the intermediate transfer belt 17. 【0019】 After that, the sheet P onto which the full-color image is transferred is guided to the fixing device 20. In the fixing device 20, the color image is fixed onto the sheet P at the nip between the fixing roller and the pressure roller. Then, the sheet P after the fixing process is discharged outside the apparatus main body 1 as an output image by the paper discharge roller 29, and then stacked on the paper discharge unit 5, and a series of image forming processes are completed. 【0020】 Next, Figure 2 will detail the image-forming section of the image-forming apparatus. Figure 2 is a diagram showing the configuration of the yellow process cartridge 10Y. The other three process cartridges, 10M, 10C, and 10BK, are configured almost identically to the yellow process cartridge 10Y, except that they use different toner colors in the imaging process; therefore, their illustrations and descriptions are omitted. 【0021】 As shown in Figure 2, the process cartridge 10Y integrally houses a photoreceptor drum 11Y as an image carrier, a charging device 12Y for charging the photoreceptor drum 11, a developing device 13Y for developing the electrostatic latent image formed on the photoreceptor drum 11Y, and a cleaning device 15Y for collecting untransferred toner on the photoreceptor drum 11Y, all within a single case. 【0022】 Here, the photoreceptor drum 11Y is a negatively charged organic photoreceptor, and has a photosensitive layer or the like provided on a drum-shaped conductive support. The charging device 12Y is a charging roller in which a medium-resistance elastic layer is coated on the outer circumference of a conductive core. A predetermined voltage is applied to this charging device 12Y (charging roller) from the power supply unit, thereby uniformly charging the surface of the opposing photoreceptor drum 11Y. 【0023】 The developing device 13Y mainly consists of a developing roller 13a facing the photoreceptor drum 11Y, a first transport screw 13b1 facing the developing roller 13a, a second transport screw 13b2 facing the first transport screw 13b1 via a partition member, and a doctor blade 13c facing the developing roller 13a. The developing roller 13a consists of a magnet fixed inside that forms magnetic poles on the roller's circumferential surface, and a sleeve that rotates around the magnet. Multiple magnetic poles are formed on the developing roller 13a (sleeve) by the magnet, and the developer is carried on the developing roller 13a. The developing device 13Y contains a two-component developer consisting of a carrier and a toner. 【0024】 The cleaning device 15Y is equipped with a cleaning blade 15a that contacts the photoreceptor drum 11Y, a transport screw 15b that transports the untransferred toner collected in the cleaning device 15Y toward a waste toner transport path (not shown), and the like. The cleaning blade 15a is made of a rubber material such as urethane rubber and contacts the surface of the photoreceptor drum 11Y at a predetermined angle and pressure. As a result, any deposits such as untransferred toner adhering to the photoreceptor drum 11Y are mechanically scraped off and collected in the cleaning device 15Y. The untransferred toner collected in the cleaning device 15Y is then transported to the waste toner transport path via a transport pipe (in which the transport screw 15b is installed) and finally collected as waste toner inside the waste toner collection container 30. Similarly, referring to Figure 3(A), the intermediate transfer cleaning device 9, which functions as a cleaning device, is also equipped with a cleaning blade that contacts the intermediate transfer belt 17, a transport screw that transports the untransferred toner collected in the intermediate transfer cleaning device 9 toward the waste toner transport path, and so on. The untransferred toner collected in the intermediate transfer cleaning device 9 is then transported to the waste toner transport path via a transport pipe (which has a transport screw inside) and is finally collected as waste toner inside the waste toner collection container 30. 【0025】 Figure 2 provides a more detailed explanation of the image creation process described earlier. The developing roller 13a rotates in the direction of the arrow in Figure 2 (counterclockwise). The developer in the developing device 13Y circulates longitudinally (perpendicular to the plane of the paper in Figure 2) while being agitated and mixed with the toner supplied from the toner container 28 by a toner supply unit (not shown) through the rotation of the first transport screw 13b1 and the second transport screw 13b2, which are arranged with a partition member between them. 【0026】 The toner, which has been triboelectrically charged and attracted to the carrier, is then supported on the developing roller 13a along with the carrier. The developer supported on the developing roller 13a then reaches the position of the doctor blade 13c. After being adjusted to an appropriate amount at the position of the doctor blade 13c, the developer on the developing roller 13a reaches the position opposite the photoreceptor drum 11 (the developing area). Subsequently, in the developing area, the toner in the developer adheres to the electrostatic latent image formed on the surface of the photoreceptor drum 11Y. More specifically, the toner adheres to the latent image (a toner image is formed) due to the electric field formed by the potential difference (developing potential) between the latent image potential (exposure potential) of the image area irradiated by the laser light L and the developing bias applied to the developing roller 13a. Subsequently, most of the toner adhering to the photoreceptor drum 11Y during the development process is transferred onto the intermediate transfer belt 17. Then, any untransferred toner remaining on the photoreceptor drum 11Y is collected into the cleaning device 15Y by the cleaning blade 15a. 【0027】 The following describes in detail the intermediate transfer belt device 16, which is a characteristic belt device in the image forming apparatus 1 of this embodiment. Referring to Figure 3(A), etc., the intermediate transfer belt device 16 as a belt device consists of an intermediate transfer belt 17 as a belt member, four primary transfer rollers 14Y, 14M, 14C, and 14BK, a drive roller 21, a press roller 22, a cleaning opposing roller 23, a tension roller 24, a backup roller 25, a pre-transfer roller 26, an intermediate transfer cleaning device 9, etc. 【0028】 The intermediate transfer belt 17, as a belt component, is stretched and supported by a plurality of roller members 21-26, 14Y, 14M, 14C, and 14BK. The plurality of roller members are arranged in the following order along the running direction of the intermediate transfer belt 17, with reference to the position of the secondary transfer nip: drive roller 21, press roller 22, cleaning opposing roller 23, tension roller 24, backup roller 25, primary transfer rollers 14Y, 14M, 14C, 14BK, and pre-transfer roller 26. The roller members 21, 23-26, 14Y, 14M, 14C, and 14BK, excluding the press roller 22, are in contact with the inner circumferential surface of the intermediate transfer belt 17. Multiple roller members 21-26, 14Y, 14M, 14C, and 14BK are each rotatably supported at both ends by the housing 40 (see Figure 4) of the intermediate transfer belt 17, either directly or indirectly. 【0029】 The drive roller 21 is one of several roller members and is the roller member that drives the intermediate transfer belt 17 (belt member). The intermediate transfer belt 17 is moved endlessly in the direction of the arrows in Figures 3(A) and (B) by the rotational drive of the drive roller 21 by a drive motor (not shown). The other roller members 22-26, 14Y, 14M, 14C, and 14BK, excluding the drive roller 21, rotate in a manner that follows the movement of the intermediate transfer belt 17. The drive roller 21 is in contact with the secondary transfer roller 18 (see Figure 1) via the intermediate transfer belt 17, forming a secondary transfer nip. Furthermore, in this embodiment, the drive roller 21 is directly and rotatably supported in the housing 40, as shown in Figure 4. 【0030】 The tension roller 24 is one of several roller members and is a roller member that applies tension to the intermediate transfer belt 17 (belt member). The tension roller 24 is slidably held in the housing of the intermediate transfer belt device 16 and is biased by a compression spring, which acts as a biasing member, to apply tension to the intermediate transfer belt 17 from the inner circumferential side. In this embodiment, the tension roller 24 is indirectly rotatably supported by the housing 40 via a holder 41, as shown in Figure 4. 【0031】 The backup roller 25 is one of several roller members, and as shown in Figures 4 and 5, its end is indirectly rotatably supported by the intermediate member 46 via a bearing member 47. The intermediate member 46 is adjustablely held by a slide plate 42 (which is slidably held in the housing 40), which will be described later. Therefore, the backup roller 25 is indirectly rotatably supported by the housing 40 via the bearing member 47 and the intermediate member 46. The position in which the backup roller 25 contacts the intermediate transfer belt 17 changes as the slide plate 42 slides, which will be described in detail later using Figure 3, etc. In this embodiment, the backup roller 25 can also be directly and rotatably supported on the relay member 46. 【0032】 The presser roller 22 is in contact with the outer surface of the intermediate transfer belt 17 downstream of the secondary transfer nip. Although not shown in the diagram, an optical sensor is installed in this vicinity, facing the outer surface of the intermediate transfer belt 17. This optical sensor optically detects the image density of the patch pattern formed on the surface of the intermediate transfer belt 17, and the image formation conditions are adjusted based on the detection result. At this time, the stability of the movement of the intermediate transfer belt 17 by the presser roller 22 improves the detection accuracy of the optical sensor. The cleaning opposing roller 23 is positioned to sandwich the intermediate transfer belt 17 between itself and the cleaning blade of the intermediate transfer cleaning device 9. This configuration improves the cleaning performance of the intermediate transfer cleaning device 9. The pre-transfer roller 26 is located upstream of the secondary transfer nip and is in contact with the inner surface of the intermediate transfer belt 17. The presence of the pre-transfer roller 26 facilitates the feeding of the sheet P into the secondary transfer nip. 【0033】 Each of the four primary transfer rollers 14Y, 14M, 14C, and 14BK has an intermediate transfer belt 17 sandwiched between it and the photoreceptor drums 11Y, 11M, 11C, and 11BK to form a primary transfer nip. A transfer voltage (primary transfer bias) with the opposite polarity to the toner polarity is applied to the primary transfer rollers 14Y, 14M, 14C, and 14BK from a primary transfer power supply (not shown). The intermediate transfer belt 17 then travels in the direction of the arrow, sequentially passing through the primary transfer nips of the primary transfer rollers 14Y, 14M, 14C, and 14BK. In this way, the toner images of each color on the photoreceptor drums 11Y, 11M, 11C, and 11BK are superimposed onto the surface of the intermediate transfer belt 17 and primary transferred (this is the primary transfer process). 【0034】 In this embodiment, the image forming apparatus 1 is configured to be switchable between a full-color mode as the first mode shown in Figure 3(A) and a monochrome mode as the second mode shown in Figure 3(B). Switching between full-color mode and monochrome mode is performed by the control unit 50, based on the user's operation (print command) on the control panel (not shown), by driving and controlling the cam motor 52 that slides the slide plate 42, and by controlling the contact and release mechanism (not shown) that moves the three primary transfer rollers 14Y, 14M, and 14C for color up and down. 【0035】 Referring to Figure 3(A), the first mode, the full-color mode, is a control mode in which the intermediate transfer belt 17 (belt member) is stretched and supported by all of the multiple roller members 21-26, 14Y, 14M, 14C, and 14BK, and the intermediate transfer belt 17 is driven by the drive roller 21. The full-color mode (mode 1) is executed based on the user's operation on the control panel (not shown) when performing full-color printing using four colors (yellow, magenta, cyan, and black). In full-color mode, all four photosensitive drums 11Y, 11M, 11C, and 11BK have an intermediate transfer belt 17 sandwiched between them and the primary transfer rollers 14Y, 14M, 14C, and 14BK, forming four primary transfer nips. 【0036】 In contrast, referring to Figure 3(B), the monochrome mode as the second mode is a control mode in which at least one roller member (in this embodiment, the three primary transfer rollers 14Y, 14M, and 14C for color) from the multiple roller members 21-26, 14Y, 14M, 14C, and 14BK, excluding the drive roller 21, tension roller 24, and backup roller 25, is separated from the intermediate transfer belt 17, and the intermediate transfer belt 17 is stretched and supported by the remaining roller members 21-26 and 14BK, and the intermediate transfer belt 17 is driven by the drive roller 21. Monochrome mode (second mode) is activated based on user operation on the control panel (not shown) when performing monochrome printing using only black ink. In monochrome mode, only the black photoreceptor drum 11BK has the intermediate transfer belt 17 sandwiched between it and the black primary transfer roller 14BK, forming a single primary transfer nip. In contrast, the three color photoreceptor drums 11Y, 11M, 11C, and 11BK, and their corresponding three primary transfer rollers 14Y, 14M, and 14C, are separated from the intermediate transfer belt 17 to avoid unnecessary contact with it. 【0037】 Referring to Figures 4 and 5, the intermediate transfer belt device 16 is provided with a slide plate 42 that is held so as to be slidable relative to the housing 40 and holds a relay member 46 that supports the backup roller 25. More specifically, in this embodiment, the slide plate 42 is installed at both ends in the width direction so as to follow the surface of the housing 40, and the cams 43 installed in the respective recesses are connected by rods 44. The cams 43 are also connected to a cam motor 52, and the control unit 50 controls the rotation of the cam motor 52, causing the slide plate 42 to move to the left or right in Figures 4 and 5. Furthermore, the slide plate 42 is provided with a guide portion 42a, and the intermediate member 46 is fixedly held to this guide portion 42a by screw fastening with an adjustment screw 48, which will be described later. This intermediate member 46 also functions as a reinforcing member that reinforces the slide plate 42 (guide portion 42a). Then, as the slide plate 42 slides in the left-right direction as shown in Figures 4 and 5, the intermediate member 46 also moves in the same direction, and the backup roller 25, which is supported via the bearing member 47, also moves from the position shown in Figure 3(A) (or Figure 3(B)) to the position shown in Figure 3(B) (or Figure 3(A)). In other words, referring to Figures 3 and 5, the slide plate 42 slides relative to the housing 40, thereby changing the position in which the backup roller 25 contacts the inner surface of the intermediate transfer belt 17 when viewed in a cross section perpendicular to the axial direction. To put it another way, the slide plate 42 slides relative to the housing 40, thereby changing the contact state (displacing the contact position) with respect to the inner surface of the intermediate transfer belt 17. 【0038】 The sliding movement of the slide plate 42 (displacement of the backup roller 25) is performed automatically by the control of the cam motor 52 by the control unit 50 when switching between the full-color mode (first mode) and the monochrome mode (second mode), as explained earlier using Figures 3(A) and (B). This ensures that the orientation of the intermediate transfer belt 17 in full-color mode, as shown in Figure 3(A), and the orientation of the intermediate transfer belt 17 in monochrome mode, as shown in Figure 3(B), are maintained in good condition. 【0039】 As shown in Figures 4 and 5, the intermediate transfer belt device 16 in this embodiment is provided with an adjustment screw 48 as an adjustment mechanism that allows manual adjustment of the fixing position of the relay member 46, which is fixed and held on the slide plate 42 (guide portion 42a). More specifically, the guide portion 42a of the slide plate 42 has a through hole that is sufficiently larger than the screw diameter of the adjustment screw 48. The intermediate member 46 has a female screw portion into which the adjustment screw 48 can be screwed. This allows the relative position of the intermediate member 46 with respect to the slide plate 42 (guide portion 42a) to be adjusted while the adjustment screw 48 (adjustment mechanism) is loosened, and then the intermediate member 46 to be fixed in place by tightening the adjustment screw 48 at the adjusted position. In this embodiment, a slide plate 42 and a connecting member 46 are provided at both ends in the width direction, and one adjustment screw 48 is installed on each. Therefore, the connecting member 46 can be adjusted in multiple directions relative to the slide plate 42. On the other hand, if the configuration is to adjust the connecting member 46 in only one direction (for example, horizontally) relative to the slide plate 42, multiple adjustment screws 48 can be installed. 【0040】 Thus, in this embodiment, the position of the intermediate member 46 relative to the slide plate 42 is adjustable, so that the intermediate transfer belt 17 is less likely to shift due to the multiple roller members 21-26, 14Y, 14M, 14C, 14BK that tension and support the intermediate transfer belt 17, or other components such as the housing 40. In particular, the intermediate transfer belt device 16 in this embodiment includes a roller member (a backup roller 25) whose contact position with the intermediate transfer belt 17 is variable, among the multiple roller members 21-26, 14Y, 14M, 14C, and 14BK that tension and support the intermediate transfer belt 17. The reaction force received by the backup roller 25 from the intermediate transfer belt 17 is large in full-color mode and monochrome mode, making the frame, such as the housing 40, prone to deformation such as twisting. As a result, the parallelism of the multiple roller members 21-26, 14Y, 14M, 14C, and 14BK deteriorates, making the intermediate transfer belt 17 prone to shifting towards the belt. Therefore, it is useful to configure the intermediate member 46 to be adjustable relative to the slide plate 42. 【0041】 In this embodiment, as shown in Figure 3(B), among the multiple roller members 21-26, 14Y, 14M, 14C, and 14BK, the tension roller 24, the backup roller 25, and the primary transfer rollers 14Y, 14M, and 14C for color (at least one roller member that moves apart in monochrome mode) are arranged along the running direction of the intermediate transfer belt 17. Therefore, the backup roller 25 becomes the roller member that receives the most tension (reaction force) from the intermediate transfer belt 17 when switching between full-color mode and monochrome mode. As a result, by adjusting the position of the relay member 46 relative to the ride plate 42 and displacing the backup roller 25, it becomes easier to correct the belt-bias of the intermediate transfer belt 17 than by displacing other roller members. 【0042】 In this embodiment, the intermediate transfer belt device 16 (belt device) is detachably installed relative to the image forming apparatus body 1 with the axial direction (the vertical direction in Figure 4, and the direction perpendicular to the plane of the paper in Figures 1, 5, etc.) as the attachment / detachment direction. Specifically, in Figure 4, the intermediate transfer belt device 16 is pulled out from above toward downwards relative to the image forming apparatus body 1 and attached from below toward upwards. Furthermore, the adjustment screw 48 (in particular, the adjustment screw 48 located on the lower side in Figure 4) is installed on the image forming apparatus body 1 so that it can be manually operated from the front side in the mounting direction (the lower side in Figure 4 and the upstream side in the mounting direction) relative to the intermediate transfer belt device 16 mounted on the image forming apparatus body 1. In order to enable such manual operation, an opening is formed in the housing 40 to allow access to the adjustment screw 48. This configuration allows for manual operation of the adjustment screw 48 without removing the intermediate transfer belt device 16 from the image forming apparatus body 1, thereby improving the efficiency of the adjustment work. Furthermore, regarding the adjustment screw 48 located on the upper side of Figure 4, manual operation is difficult when the intermediate transfer belt device 16 is attached to the image forming apparatus body 1. Therefore, if sufficient belt alignment correction cannot be achieved by adjusting only the adjustment screw 48 on the lower side of Figure 4, the intermediate transfer belt device 16 will be pulled out from the image forming apparatus body 1 and manually adjusted. 【0043】 Furthermore, referring to Figure 4, the intermediate transfer belt device 16 in this embodiment is provided with a belt offset detection sensor 51 as a detection means for detecting the amount of belt offset in the axial direction (up and down direction in Figure 4) of the intermediate transfer belt 17 (belt member). More specifically, the belt deviation detection sensor 51 (detection means) is, for example, a set of multiple photosensors arranged in parallel in the axial direction, and detects the amount of belt deviation (including the deviation direction) by optically detecting the position of the axial end (widthwise end) of the intermediate transfer belt 17. Then, in accordance with the detection result of the belt deviation detection sensor 51 (detection means), the slide plate 42 is automatically slid to correct the belt deviation. Specifically, when the belt deviation detection sensor 51 detects a predetermined amount of belt deviation toward one end in the width direction, the slide plate 42 is moved to adjust the balance of the tension of the backup roller 25 so that the predetermined amount of belt deviation is corrected. This configuration allows for responsive automatic correction even for relatively slight belt deviations that cannot be fully corrected by manual adjustment of the adjustment screw 48. In particular, in this embodiment, since the belt deviation detection sensor 51 is provided near the backup roller 25, the responsiveness of belt deviation correction can be improved. 【0044】 <Example 1> As shown in Figure 6, in Modification 1, the intermediate transfer belt device 16 does not have an adjustment mechanism (adjustment screw 48) on both sides in the width direction (axial direction), but rather it is provided only on one side in the width direction (the side facing the user in the mounting direction of the intermediate transfer belt device 16). This configuration is useful when sufficient belt alignment correction can be achieved by adjusting only one of the adjustment screws 48 in the width direction. 【0045】 <Modification 2> As shown in Figures 7 to 9, the intermediate transfer belt device 16 in the modified example 2 is provided with a belt alignment correction mechanism 79 that corrects the axial (widthwise) alignment of the intermediate transfer belt 17 (belt member) by tilting the tension roller 24 with respect to the axial direction (the direction perpendicular to the plane of the paper, as in Figures 3, 5, and 8; the up and down direction, as in Figure 4; and the left and right direction, as in Figures 7 and 9). This belt-bias correction mechanism 79 corrects the belt bias of the intermediate transfer belt 17 by tilting the tension roller 24 in conjunction with the movement of the intermediate transfer belt 17 in the width direction. More specifically, as shown in Figure 7, the tension roller 24 is provided with a roller portion 24a that contacts the inner circumferential surface of the intermediate transfer belt 17, and shaft portions 24b (roller shafts) that have a smaller outer diameter than the roller portion 24a and protrude from both ends of the roller portion 24a. The shaft portions 24b can be formed using two shaft portions 24b to protrude separately from both ends of the roller portion 24a, or a single shaft portion 24b can be passed through the roller portion 24a and protrude from both ends. In any case, in this embodiment, the tension roller 24 has the roller portion 24a and the shaft portion 24b integrated and rotates as a single unit. Furthermore, as shown in Figure 7, the holder 41 of the intermediate transfer belt device 16 is provided with a bearing 76 that receives the shaft portion 24b of the tension roller 24. That is, the tension roller 24 is rotatably held by the holder 41 (see Figure 8), which functions as an oscillating plate, via the bearings 76 at both ends of the shaft portion 24b. This holder 41 (oscillating plate), together with the tension roller 24, is held in the housing 40 so as to be rotatable around the support shaft 41b in the direction of the arrow in Figure 8. The holder 41 is configured to be biased clockwise in Figure 8 by a tension spring 78 connected to the housing 40. Furthermore, the shaft portion 24b of the tension roller 24 is rotatably held in the guide holes 41a of the holders 41 at both ends via bearings 76. The bearings 76 are slidably held in the guide holes 41a and are biased to the left in Figure 8 by a compression spring 77. With this configuration, the tension roller 24 is pressed against the inner circumferential surface of the intermediate transfer belt 17 by the biasing force of the compression spring 77, thereby applying tension to the intermediate transfer belt 17. 【0046】 Here, as shown in Figures 7 and 9, the belt alignment correction mechanism 79 is composed of a flange 80, a sliding member 81, a contact member 82, and the like. The sliding member 81 is slidably supported with respect to the shaft portion 24b of the tension roller 24, and in conjunction with the movement of the intermediate transfer belt 17 in the width direction (left-right direction in Figures 7 and 9) (towards the belt), it tilts the tension roller 24 (shaft portion 24b). The sliding member 81 has a parallel surface 81a that is parallel to the axis of rotation and an inclined surface 81b that is inclined relative to the parallel surface 81a. The contact member 82 then comes into contact with these parallel surface 81a and inclined surface 81b. Furthermore, the sliding member 81 is configured not to rotate in conjunction with the movement of the intermediate transfer belt 17 or the rotation of the tension roller 24 (shaft portion 24b). Specifically, the sliding member 81 is locked into a rotation-stopping projection formed on the housing 40 of the device, thereby restricting its rotation. The contact member 82 is formed to be able to contact the parallel surface 81a and the inclined surface 81b of the sliding member 81. Then, in conjunction with the movement of the intermediate transfer belt 17 in the width direction, the inclined surface 81b of the sliding member 81 and the contact member 82 slide against each other, thereby tilting the tension roller 24 (shaft portion 24b). The flange 80 is positioned so as to be able to contact the end face of the intermediate transfer belt 17, and moves by being pushed by the intermediate transfer belt 17 as the intermediate transfer belt 17 moves in the width direction. The flange 80 is configured to be rotatable (co-rotate) in accordance with the movement of the intermediate transfer belt 17 and the rotation of the tension roller 24 (shaft portion 24b). The sliding member 81 is positioned so as to be able to contact the flange 80 at a position opposite to the intermediate transfer belt 17. The belt deviation correction mechanism 79 configured in this way corrects the belt deviation of the intermediate transfer belt 17 (the belt movement in the left-right direction in Figures 7 and 9). Specifically, as the intermediate transfer belt 17 moves to the right, the end face of the intermediate transfer belt 17 comes into contact with the abutment portion 80a of the flange 80, as shown in Figure 9(A), causing the flange 80 to slide to the right and push the sliding member 81 to the right. When the sliding member 81 is pushed to the right, the contact member 82, which was in contact with the parallel surface 81a as shown in Figure 9(A), comes into contact with the inclined surface 81b as shown in Figure 9(B), and the tension roller 24 tilts along the inclination of the inclined surface 81b as shown in Figure 9(B). Then, as shown in Figure 9(B), when the right end of the tension roller 24 is tilted, the intermediate transfer belt 17 tilts to the left when viewed from the tension roller 24 side. As the intermediate transfer belt 17 travels a distance Y, it shifts to the left, canceling out the shift to the right. In this way, the belt shift correction mechanism 79 corrects the belt shift of the intermediate transfer belt 17. By adding the belt deviation correction mechanism 79 configured in this way to the intermediate transfer belt device 16 described using Figures 3 to 5, the belt deviation of the intermediate transfer belt 17 becomes even less likely to occur. Although not shown in Figures 8 and 9, in this embodiment, the belt alignment correction mechanism 79 is not installed only on one end in the width direction (lower part of Figure 8), but also on the other end in the width direction (upper part of Figure 8). 【0047】 As described above, the intermediate transfer belt device 16 (belt device) in this embodiment includes an intermediate transfer belt 17 (belt member) stretched and supported by a plurality of roller members 21-26, 14Y, 14M, 14C, and 14BK, a drive roller 21 which is one of the plurality of roller members and drives the intermediate transfer belt 17, a tension roller 24 which is one of the plurality of roller members and applies tension to the intermediate transfer belt 17, and a backup roller 25 which is one of the plurality of roller members and whose end is directly or indirectly rotatably supported by a relay member 46. Furthermore, a housing 40 is provided that rotatably supports both ends of the plurality of roller members 21-26, 14Y, 14M, 14C, and 14BK, directly or indirectly. In addition, a slide plate 42 is provided which is slidably held relative to the housing 40 and also holds the relay member 46, and by sliding relative to the housing 40, the position in which the backup roller 25 contacts the inner circumferential surface of the intermediate transfer belt 17 in a cross section perpendicular to the axial direction is varied. Furthermore, an adjustment screw 48 (adjustment mechanism) is provided that allows manual adjustment of the fixing position of the intermediate member 46, which is fixed and held by the slide plate 42. This makes it less likely for the intermediate transfer belt 17 to shift out of position. 【0048】 In this embodiment, the present invention was applied to an intermediate transfer belt device 16 as a belt device, but it can naturally be applied to other belt devices (for example, a secondary transfer belt device in which a secondary transfer belt is installed as a belt member). In such cases, in this embodiment, the full-color mode was used as the first mode and the monochrome mode as the second mode, but other modes can be used as the first and second modes. Furthermore, in this embodiment, the adjustment mechanism (adjustment screw 48) is positioned to be manually operable from the front side in the mounting direction, but the adjustment mechanism (adjustment screw 48) can also be positioned in other locations (for example, a position that can be manually operated from the left side in Figure 4). Furthermore, the same effects as those of this embodiment can be obtained in such cases as well. 【0049】 It is clear that the present invention is not limited to this embodiment, and that this embodiment can be modified as appropriate within the scope of the technical concept of the present invention, in addition to what is suggested here. Furthermore, the number, position, shape, etc. of the constituent members are not limited to this embodiment, and can be set to a number, position, shape, etc. that is suitable for carrying out the present invention. [Explanation of Symbols] 【0050】 1. Image forming apparatus (image forming apparatus main unit), 16. Intermediate transfer belt device (belt device), 17 Intermediate transfer belt (belt component), 21 Drive roller (roller member), 24 Tension roller (roller component), 25 Backup roller (roller component), 40 cabinets, 41 holder, 42 sliding plates, 42a Guide section, 43 Cam, 44 rods, 46. ​​Intermediate members (reinforcement members), 47 Bearing members, 48 Adjustment screw (adjustment mechanism), 51 Belt-side detection sensor (detection means), 79. Belt-bias correction mechanism. 【0051】 Furthermore, the embodiments of the present invention can also be, for example, combinations of appendices 1 to 7 as follows. (Note 1) A belt member stretched and supported by multiple roller members, One of the plurality of roller members, which is a drive roller that drives the belt member, One of the plurality of roller members, which is a tension roller that applies tension to the belt member, A backup roller, one of the plurality of roller members, whose end is rotatably supported directly or indirectly by the intermediate member, A housing that rotatably supports both ends of the plurality of roller members, either directly or indirectly, A sliding plate is held slidably within the housing and holds the relay member, thereby changing the position in which the backup roller contacts the inner circumferential surface of the belt member when viewed in a cross section perpendicular to the axial direction, as the plate slides relative to the housing. An adjustment mechanism that allows manual adjustment of the fixing position of the relay member, which is fixed and held on the slide plate, A belt device characterized by having the following features. (Note 2) The system is configured to allow switching between a first mode in which the belt member is taut and supported by all of the plurality of roller members and the belt member is driven by the drive roller, and a second mode in which at least one of the plurality of roller members, excluding the drive roller, the tension roller, and the backup roller, is separated from the belt member and the belt member is taut and supported by the remaining roller members and the belt member is driven by the drive roller. The belt device according to Appendix 1, characterized in that the sliding plate is automatically moved when switching between the first mode and the second mode. (Note 3) The belt device according to Appendix 2, characterized in that the tension roller, the backup roller, and at least one roller member are arranged among the plurality of roller members along the direction of travel of the belt member. (Note 4) The belt device is detachably installed on the main body of the image forming apparatus with the axial direction as the attachment / detachment direction. The belt device according to any one of the appendices 1 to 3, characterized in that the adjustment mechanism is installed so as to be manually operable from the front side in the mounting direction with respect to the belt device attached to the main body of the image forming apparatus. (Note 5) The belt device according to any one of the appendices 1 to 4, characterized by comprising a belt bias correction mechanism that corrects the axial bias of the belt member by tilting the tension roller with respect to the axial direction. (Note 6) The belt member is provided with a detection means for detecting the amount of deviation of the belt member towards the belt in the axial direction, The belt device according to any one of Appendix 1 to Appendix 5, characterized in that the slide plate is automatically moved by sliding in accordance with the detection result of the detection means. (Note 7) An image forming apparatus characterized by being equipped with a belt device as described in any of Appendix 1 to Appendix 6. [Prior art documents] [Patent Documents] 【0052】 [Patent Document 1] Japanese Patent Publication No. 2017-161877

Claims

[Claim 1] A belt member stretched and supported by multiple roller members, One of the plurality of roller members, which is a drive roller that drives the belt member, One of the plurality of roller members, which is a tension roller that applies tension to the belt member, One of the plurality of roller members, a backup roller whose end is rotatably supported directly or indirectly by the intermediate member, A housing that rotatably supports both ends of the plurality of roller members, either directly or indirectly, A sliding plate is held slidably within the housing and holds the relay member, thereby changing the position in which the backup roller contacts the inner circumferential surface of the belt member when viewed in a cross section perpendicular to the axial direction, as the plate slides relative to the housing. An adjustment mechanism that allows manual adjustment of the fixing position of the relay member, which is fixed and held on the slide plate, A belt device characterized by having the following features. [Claim 2] The system is configured to allow switching between a first mode in which the belt member is taut and supported by all of the plurality of roller members and the belt member is driven by the drive roller, and a second mode in which at least one of the plurality of roller members, excluding the drive roller, the tension roller, and the backup roller, is separated from the belt member and the belt member is taut and supported by the remaining roller members and the belt member is driven by the drive roller. The belt device according to claim 1, characterized in that the sliding plate is automatically moved when switching between the first mode and the second mode. [Claim 3] The belt device according to claim 2, characterized in that the tension roller, the backup roller, and at least one roller member are arranged among the plurality of roller members along the direction of travel of the belt member. [Claim 4] The belt device is detachably installed on the main body of the image forming apparatus with the axial direction as the attachment / detachment direction. The belt device according to claim 1 or 2, characterized in that the adjustment mechanism is installed so as to be manually operable from the front side in the mounting direction with respect to the belt device attached to the main body of the image forming apparatus. [Claim 5] The belt device according to claim 1 or 2, further comprising a belt alignment correction mechanism that corrects the axial alignment of the belt member by tilting the tension roller with respect to the axial direction. [Claim 6] The belt member is provided with a detection means for detecting the amount of deviation of the belt member towards the belt in the axial direction, The belt device according to claim 1 or 2, characterized in that the sliding plate is automatically slid in accordance with the detection result of the detection means. [Claim 7] An image forming apparatus characterized by comprising the belt device described in claim 1 or claim 2.

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