Belt cleaning apparatus and image forming apparatus

Abstract

The present invention provides a belt cleaning device that can clean dirt adhering to both sides of a belt without compromising maintainability, and that can keep the scale tape on the back of the belt at an optically readable level. [Solution] A belt cleaning device 75 comprising: a belt member 10 that can travel in the travel direction V by receiving a driving force from a drive member 71; a detected portion 8 provided on the inner circumferential surface of the belt member 10; a detection means 9 for detecting the detected portion 8; and a control means 72 for controlling the travel operation of the belt member 10 based on the detection result of the detected portion 8 by the detection means 9; a first cleaning member 76 provided on a predetermined roller 71 around which the belt member 10 is wrapped at an angle of 90 degrees or more, which contacts the detected portion 8 to clean the detected portion 8; and a second cleaning member 77 positioned opposite the first cleaning member 76 via the belt member 10, which contacts the outer circumferential surface of the belt member 10 to clean it.

Description

Technical Field

[0001] The present invention relates to a belt cleaning device and an image forming apparatus.

Background Art

[0002] Electrophotographic image forming apparatuses that form images on recording media are known to be equipped with belt devices such as transfer units and conveyance units that include an endless belt member wound around a plurality of rollers as a transfer body or conveyance body for the recording medium. In such a belt device, in order to control the moving speed of the belt member (the conveyance speed of the recording medium), a tape-shaped detected portion that is read by an optical detection unit is affixed over the entire longitudinal direction (full length direction) of the belt on at least one side in the belt width direction orthogonal to the belt movement direction, and such a configuration is known.

[0003] As an example of this, a technique is known in which a scale tape serving as a detected portion is affixed to the back surface of an intermediate transfer belt, and the scale tape is optically read to control the position and speed of the intermediate transfer belt with high accuracy. Slits and irregularities are formed on the surface of the scale tape, and such slits and irregularities are detected by the optical detection unit. However, this configuration has a problem that dirt such as toner adheres to the optical sensor serving as the optical detection unit, or toner dirt adheres to the scale tape itself, making it impossible to optically read the scale tape. Accordingly, a technique has been proposed in which a rotating brush with flocked bristles on a roller that stretches the belt is disposed on the upstream side of the optical sensor to clean the scale tape, and a technique in which the scale tape is cleaned by sandwiching the belt with a bracket provided with an integrated front and back brush disposed on the downstream side of the optical sensor (see, for example, Patent Document 1).

Summary of Invention

Problems to be Solved by the Invention

[0004] In the aforementioned technology, cleaning only the underside of the belt was insufficient, requiring periodic cleaning of the optical sensor. Furthermore, in a configuration where the belt is clamped between brackets equipped with a pair of brushes, there was a risk of damaging the scale tape when attaching or detaching the brackets, posing maintenance problems. Additionally, placing the cleaning mechanism upstream of the drive rollers could place a load on the belt, causing abnormalities in belt speed control and potentially generating abnormal images. The present invention aims to solve the above-mentioned problems and provide a belt cleaning device that can clean dirt adhering to both sides of a belt without impairing maintainability, and that can keep the scale tape provided on the back of the belt at an optically readable level. [Means for solving the problem]

[0005] The invention described in claim 1 is provided in a belt conveying device comprising: an endless belt member stretched over a plurality of rollers and capable of traveling in the direction of travel by receiving a driving force from a drive member; a detection portion provided over the entire circumference of the inner circumferential surface of the belt member near at least one end in the width direction perpendicular to the direction of travel; detection means for detecting the detection portion; and control means for controlling the travel operation of the belt member based on the detection result of the detection means for the detection portion, wherein the device is provided on a predetermined roller among the plurality of rollers around which the belt member is wrapped at an angle of 90 degrees or more, and a first cleaning member that contacts the detection portion to clean the detection portion; and a second cleaning member that is positioned opposite the first cleaning member via the belt member and contacts the outer circumferential surface of the belt member to clean the outer circumferential surface. [Effects of the Invention]

[0006] According to the present invention, a greater cleaning capacity can be obtained compared to conventional configurations, thereby maintaining the cleanliness of the detected area to a sufficient degree that reading by the detection means can be continued, and a belt cleaning device can be provided that can keep the detected area on the back surface of the belt at an optically readable level. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic front view of an image forming apparatus to which one embodiment of the present invention can be applied. [Figure 2] This is a schematic diagram illustrating the configuration of a belt conveying device according to one embodiment of the present invention. [Figure 3] This is a schematic perspective view of the intermediate transfer belt, rollers, and detection unit of a belt conveying device according to one embodiment of the present invention, as seen from the inside of the intermediate transfer belt. [Figure 4] This is a schematic cross-sectional view illustrating the configuration of the intermediate transfer belt and the detection unit used in one embodiment of the present invention. [Figure 5] This is a schematic diagram illustrating the configuration of a detection means used in one embodiment of the present invention. [Figure 6] This is a schematic diagram illustrating the configuration of a detection means used in one embodiment of the present invention. [Figure 7] This is a schematic diagram illustrating the configuration at the joint of the detection portion provided in the intermediate transfer belt used in one embodiment of the present invention. [Figure 8] This is a schematic diagram illustrating a scale tape and a scale sensor used in one embodiment of the present invention. [Figure 9] This is a schematic front view illustrating a belt cleaning device according to one embodiment of the present invention. [Figure 10] This is a schematic diagram illustrating a first cleaning member of a belt cleaning device according to one embodiment of the present invention. [Figure 11] This is a schematic diagram illustrating a first cleaning member of a belt cleaning device according to one embodiment of the present invention. [Figure 12] This is a schematic diagram illustrating a first cleaning member and a second cleaning member of a belt cleaning device according to one embodiment of the present invention. [Figure 13] This is a schematic diagram illustrating a first cleaning member and a second cleaning member of a belt cleaning device according to one embodiment of the present invention. [Figure 14]This is a schematic diagram illustrating a second cleaning member and a support bracket of a belt cleaning device according to one embodiment of the present invention. [Figure 15] This is a schematic diagram illustrating the winding angle of a belt member around a predetermined roller in a belt cleaning device according to one embodiment of the present invention. [Figure 16] This diagram illustrates a method for attaching and detaching a belt member of a belt cleaning device according to one embodiment of the present invention. [Figure 17] This diagram illustrates a method for attaching and detaching a belt member of a belt cleaning device according to one embodiment of the present invention. [Modes for carrying out the invention]

[0008] Figure 1 shows an image forming apparatus to which one embodiment of the present invention can be applied. In the figure, the electrophotographic color copier 1, which is an image forming apparatus, comprises a main unit 2, a paper feed table 3 on which the main unit 2 is placed, a scanner 4 which is an image reading unit mounted on the top of the main unit 2, and an automatic document feeder (ADF) 5 mounted above the scanner 4. At the center of the main body 2 of the device is an intermediate transfer unit 6, which is a belt conveying device having an endless belt member, the intermediate transfer belt 10. The intermediate transfer belt 10 is stretched over multiple rollers and is driven to travel in a clockwise direction, which is the belt travel direction indicated by the symbol V in Figure 1.

[0009] Around the intermediate transfer belt 10, a transfer cleaning device 17 is arranged to remove residual toner remaining on the intermediate transfer belt 10 after image transfer to the recording medium. Above the intermediate transfer unit 6, four process cartridges 18Y, 18M, 18C, and 18K corresponding to yellow, magenta, cyan, and black are arranged in order from upstream along the belt travel direction V. Each of the process cartridges 18Y, 18M, 18C, and 18K constitutes a tandem image forming unit 20. An exposure device 21 is arranged above the tandem image forming unit 20.

[0010] The process cartridges 18Y, 18M, 18C, and 18K are each provided with a drum-shaped photoreceptor 40Y, 40M, 40C, 40K that serves as an image bearing member, and have the functions of forming a toner image of each color on the corresponding photoreceptor 40 using a known electrophotographic process, and cleaning the surface of the photoreceptor after the toner image is transferred. The process cartridges 18Y, 18M, 18C, 18K and the intermediate transfer unit 6 are detachably supported by the apparatus main body 2.

[0011] At a position facing the tandem image forming portion 20 with the intermediate transfer unit 6 interposed therebetween, a secondary transfer roller 23 serving as a secondary transfer member is disposed. The secondary transfer roller 23 is pressed against a secondary transfer opposing roller 7 serving as a secondary transfer opposing member via the intermediate transfer belt 10, and a nip portion 22 serving as a secondary transfer portion is formed at the contact portion between the two. In the nip portion 22, a transfer bias is applied to the secondary transfer opposing roller 7 or the secondary transfer roller 23, so that the toner image or the combined color image on the intermediate transfer belt 10 is transferred onto a transfer sheet S which is a recording medium.

[0012] A fixing device 25 for fixing the toner image transferred onto the transfer sheet S is disposed on the downstream side of the secondary transfer roller 23 in the sheet conveying direction. The fixing device 25 is configured by pressing a pressure roller 27 serving as a pressure member against a fixing belt 26 serving as a fixing member. As the secondary transfer opposing member, a member in which an endless belt is wound around a plurality of roller members may be used instead of the secondary transfer opposing roller 7. In the present embodiment, a contact system in which the secondary transfer roller 23 is brought into contact with the intermediate transfer belt 10 is adopted, but a non-contact charger may be disposed as the secondary transfer member. In such a case, since it becomes difficult to additionally provide a sheet conveying function using rollers or a belt, conveying means such as rollers and a belt may be disposed separately. In the configuration shown in Figure 1, below the nip portion 22 and the fixing device 25, a sheet reversing device 28 that reverses the transfer sheet S to form images on both sides of the transfer sheet S is arranged in parallel with the tandem image forming portion 20, and is configured to enable double-sided image formation. The color copying machine 1 may be configured to be connectable to an external terminal device such as a personal computer, whether wired or wireless, so as to function as a printer.

[0013] To obtain a color output using the color copying machine 1 having such a configuration, first, a color original is set on the original platen 30 of the automatic document feeder 5, or the automatic document feeder 5 is opened to set the color original on the contact glass 32 of the scanner 4, and then the automatic document feeder 5 is closed to hold the original. In the color copying machine 1, when a start switch (not shown) is turned on, if an original is set in the automatic document feeder 5, the original is conveyed and moved onto the contact glass 32, and immediately after that, or when an original is set on the contact glass 32, the scanner 4 is operated to cause the first traveling body 33 and the second traveling body 34 to travel. In the color copying machine 1, the first traveling body 33 irradiates light from the light source, further reflects the reflected light from the original surface and irradiates it toward the second traveling body 34, the irradiated light is reflected by the mirror of the second traveling body 4, sent to the reading sensor 36 via the imaging lens 35, and the content of the original is read.

[0014] When the start switch is turned on, a drive motor to be described later operates to drive the intermediate transfer belt 10 to travel in the belt traveling direction V. At the same time, the photoreceptors 40Y, 40M, 40C, and 40K included in the process cartridges 18Y, 18M, 18C, and 18K are rotationally driven, and monochromatic toner images of yellow, magenta, cyan, and black are formed on each photoreceptor 40, respectively. In the color copying machine 1, the monochromatic toner images formed along with the conveyance travel of the intermediate transfer belt 10 are sequentially superimposed and transferred onto the intermediate transfer belt 10 to form a composite color image on the intermediate transfer belt 10.

[0015] When a start switch (not shown) is turned on, one of the paper feed rollers 42 on the paper feed table 3 is selectively driven to rotate, and a transfer sheet S is fed from one of the multiple paper feed cassettes 44 on the paper bank 43. The fed transfer sheet S is separated one by one by the separation roller 45 and sent to the paper feed path 46, which is then transported by multiple transport rollers 47 and sent to the paper feed path 48 in the main body of the device 2, where it is stopped by being struck against the pair of registration rollers 49. Alternatively, the paper feed roller 50 on the manual feed tray 51 is driven to rotate and feed the transfer sheet S, which is then separated one by one by the separation roller 52 and sent to the manual feed path 53, where it is stopped by being struck against the pair of registration rollers 49.

[0016] Then, the pair of resist rollers 49 are rotated in sync with the timing when the composite color image on the intermediate transfer belt 10 reaches the nip section 22, and the transfer sheet S is fed into the nip section 22 between the intermediate transfer belt 10 and the secondary transfer roller 23, where the composite color image on the intermediate transfer belt 10 is transferred onto the transfer sheet S in one go. When obtaining a monochrome output, a monochrome toner image is formed and transferred onto the intermediate transfer belt 10, and this monochrome toner image is transferred onto the transfer sheet S in the nip section 22.

[0017] After image transfer, the transfer sheet S is sent from the nip section 22 to the fixing device 25, where the transferred image is fixed by heat and pressure. Then, the transport direction is determined by the switching claw 55, and the sheet is discharged outside the machine by the discharge roller 56 and stacked on the output tray 57. Alternatively, the transport direction is switched by the switching claw 55 and the sheet is sent to the sheet reversing device 28, where it is reversed front to back and then sent back to the nip section 22 to transfer the image to the back side, and then stacked on the output tray 57 by the discharge roller 56. After image transfer, the intermediate transfer belt 10 is cleaned of residual toner by the transfer cleaning device 17 and prepared for further image formation.

[0018] The intermediate transfer belt 10 used in this embodiment is composed of one or more layers of PVDF (polyvinylidene fluoride), ETFE (ethylene-tetrafluoroethylene copolymer), PI (polyimide), PC (polycarbonate), etc. A release layer may be coated on the surface of the intermediate transfer belt 10 as needed. An elastic belt having a rubber layer may be used as the intermediate transfer belt 10. By using an elastic belt, the intermediate transfer belt 10 can be compressed at the nip portion 22, filling the gaps even in the uneven transfer sheet S, thereby improving transferability. Furthermore, since a rubber layer alone would result in excessive belt elongation, the intermediate transfer belt 10 may have a resinous layer such as a polyimide layer (PI layer) in the base layer, and a layer with a low coefficient of friction may be provided on the surface layer.

[0019] Figure 2 is a schematic diagram showing each process cartridge 18 and the intermediate transfer unit 6 as viewed from the front side of the main body 2 of the apparatus. The intermediate transfer unit 6 comprises a plurality of rollers, namely rollers 61 to 71 and a secondary transfer opposing roller 7, and an intermediate transfer belt 10 wrapped around these rollers 7, 61 to 71. As shown in Figure 3, the rollers 61 to 71 are mounted on the outer circumference of roller shafts 61a to 71a and rotate integrally with the roller shafts 61a to 71a. Of the plurality of rollers, rollers 71 and 68 are located on the right end and left end sides of the main body 2 of the apparatus, respectively. In this embodiment, roller 71 is configured as a drive roller, which is a driving member, and rollers 61 to 70 are configured as driven rollers. Roller 71 is rotated clockwise in Figure 2 by a drive motor M1, which is a drive source, and this drive drives the intermediate transfer belt 10 to travel in the belt travel direction V at a predetermined speed.

[0020] The intermediate transfer belt 10 is wrapped between rollers 71 and 68, and its upper edge faces the photoreceptors 40Y, 40M, 40C, and 40K. Between rollers 66 and 67, a tension roller 15 is positioned to press the intermediate transfer belt 10 from the outside inward. The tension roller 15 is configured as an elastic roller with a rubber layer on the outer circumference of a metal core. The secondary transfer opposing roller 7 is a rubber roller with a rubber layer on the outer circumference of a metal core, and is configured to apply a secondary transfer bias to the metal core. In this embodiment, the secondary transfer bias is applied under constant current control.

[0021] Primary transfer rollers 14Y, 14M, 14C, and 14K are positioned on the upper inner side of the intermediate transfer belt 10, opposite the photoreceptors 40Y, 40M, 40C, and 40K. The primary transfer rollers 14Y, 14M, 14C, and 14K are rotatably supported by support arms 13Y, 13M, 13C, and 13K, which swing vertically in the figure using a well-known contact and separation mechanism. Each primary transfer roller 14 is configured to move toward and away from the intermediate transfer belt 10 by adjusting the angle of each support arm 13 with an electric actuator or cam. Each primary transfer roller 14 is a rubber roller with a rubber layer on the outer circumference of a metal core, and a primary transfer bias is applied to each portion of the metal core. In this embodiment, a constant current controlled primary transfer bias is applied.

[0022] As shown in Figure 3, a scale tape 8, which is the part to be detected, is arranged over the entire length of the belt on the inner surface 10b of the intermediate transfer belt 10, which faces each roller on at least one side of the end 10a of the belt width direction X that intersects the belt running direction V. As shown in Figure 4, the scale tape 8 has a three-layer structure consisting of an insulating protective layer 81, a conductive metal layer 82, and an adhesive layer 83. It is bonded and fixed to the inner surface 10b of the intermediate transfer belt 10 by the adhesive force of the adhesive layer 83, and is integrated with the intermediate transfer belt 10. The conductive metal layer 82 is a metal vapor-deposited film formed by vapor-depositing a conductive metal such as aluminum onto an insulating film, such as polyethylene terephthalate (PET), which constitutes the protective layer 81 and has insulating properties. In the scale tape 8, the protective layer 81 is provided on one side 82a of the metal layer 82, and the adhesive layer 83 is provided on the other side 82b of the metal layer 82. Note that Figure 4 exaggerates each layer to illustrate the structure of the scale tape 8.

[0023] On the scale tape 8, uneven areas 82c are formed by partially melting the metal layer 82 by irradiating it with processing laser light from, for example, a laser processing machine, from the protective layer 81 side. As shown in Figures 4 and 6(a), the uneven areas 82c are arranged at the same length, parallel to each other, at equal intervals, and with an extremely small pitch along the belt running direction V, and are provided around the entire circumference of the intermediate transfer belt 10, thereby forming a scale mark M that makes the scale tape 8 function as a detected area for reading by an optical detection means.

[0024] As shown in Figure 4, if the thickness of the scale tape 8 is t, the thickness of the protective layer 81 is t1, the thickness of the metal layer 82 is t2, and the thickness of the adhesive layer 83 is t3, then it is preferable that thicknesses t1 and t2 are each 10 μm or more. In this embodiment, a scale tape 8 with thicknesses t1 and t2 of 25 μm each and thickness t3 of 5 μm is used. Therefore, the thickness of the end of the intermediate transfer belt 10 will be formed to be thicker than other parts by the thickness t of the scale tape 8. In this embodiment, the scale tape 8 is adhered to the inner surface 10b of the intermediate transfer belt 10, but the scale marks M may be directly formed on the inner surface 10b using a laser processing machine or the like to serve as the detection area. Also, in this embodiment, the scale tape 8 is provided around the entire circumference of the intermediate transfer belt 10, but the scale tape 8 may be provided only in a part of the direction of movement of the intermediate transfer belt 10.

[0025] As shown in Figure 5, the scale sensor 9, acting as a detection means, is positioned opposite the scale marks M and is connected to the drive control device 72, acting as a control means, via a signal line. The scale sensor 9 sequentially detects the scale marks M on the intermediate transfer belt 10 and outputs a detection signal to the drive control device 72. In other words, the scale sensor 9 has the function of detecting and reading the scale tape 8, which is the part to be detected. The drive control device 72 is connected to the drive motor M1 via the motor drive circuit 73 and has the function of controlling the operation of the drive motor M1 to control the belt travel speed. As will be described later, the drive control device 72 acquires position data for pitch correction of the scale mark M from the detection signal of the scale sensor 9, and controls the belt travel speed of the intermediate transfer belt 10 by inputting target position data to the motor drive circuit 73. In this way, the drive control device 72 outputs a signal to the motor drive circuit 73 as appropriate based on the position information of the intermediate transfer belt 10 detected by the scale sensor 9, and the motor drive circuit 73 drives the drive motor M1 to provide feedback control of the belt travel speed of the transfer belt 10.

[0026] The detection of scale marks M by the scale sensor 9 will be explained using Figure 6. Figure 6(a) is a plan view of the scale marks M formed on the scale tape 8, Figure 6(b) is a side perspective view showing the optical system configuration and optical path of the scale sensor 9, and Figure 6(c) is a plan view of the detection surface of the scale sensor 9. The scale marks M are reflective marks, and as shown in the figure, scale marks M as reflective parts and light-shielding parts S1 are alternately formed on the outer surface of the intermediate transfer belt 10 along the belt running direction V.

[0027] The scale sensor 9 includes a light-emitting element 91 such as an LED, a collimating lens 92, a slit mask 93 (see Figure 6(b)), a light-receiving window 94 made of a transparent cover such as glass or a transparent resin film, and a light-receiving element 95 such as a phototransistor, which are fixed to various parts of the housing 90. When the light-emitting element 91, which is the light source of the scale sensor 9, emits light, the light passes through the collimating lens 92 to become a parallel beam, and passes through multiple slits 93a parallel to the scale marks M of the slit mask 93 shown in Figure 6(c), splitting into multiple light beams LB that irradiate the scale tape 8 on the intermediate transfer belt 10. A portion of these multiple light beams LB is reflected by the scale marks M, and the reflected light passes through the light-receiving window 94 and is received by the light-receiving element 95, which converts the change in brightness (intensity) of the reflected light into an electrical signal. In this way, the scale sensor 9 detects the scale marks M by sensing the intensity of the reflected light with the light-receiving element 95, and outputs a continuously modulated analog alternating signal indicating the presence or absence of the scale marks M as the intermediate transfer belt 10 moves.

[0028] The scale tape 8, provided at the end of the intermediate transfer belt 10, may experience a significant decrease in its light reflectivity due to the accumulation of contaminants such as paper dust and toner during use. In this case, although the degree of decrease in the light reflectivity of the scale tape 8 varies, if it falls below a certain level of light reflectivity detectable by the scale sensor 9, the scale sensor 9 may be unable to detect the scale mark M on the scale tape 8, potentially leading to reading errors. As a result of the scale sensor 9 no longer detecting the scale mark M, it becomes impossible to accurately control the movement speed of the intermediate transfer belt 10, which can significantly affect image formation and cause problems such as color misalignment.

[0029] For the reasons mentioned above, it is desirable to periodically clean any contaminants adhering to the scale tape 8 or scale sensor 9. When cleaning the scale sensor 9 using a dedicated cleaning tool, it is assumed that the cleaning tool will be placed in contact with the scale sensor 9. However, variations in the positional relationship between the cleaning tool and the scale sensor 9 can lead to inadequate cleaning, so relative positional accuracy between the cleaning tool and the scale sensor 9 is required. Furthermore, since the scale tape 8 is not endless but cut from a strip and attached to the inner surface 10b of the end of the intermediate transfer belt 10, a joint 8c is created between the starting end 8a and the ending end 8b, as shown in Figure 7. If toner, paper dust, etc. get into the joint 8c, it can cause poor adhesion of the scale tape 8, leading to lifting of the ends 8a and 8b of the scale tape 8 over time. This can cause the scale tape 8 to reach the end of its lifespan before reaching the preset durability time of the intermediate transfer unit 6, necessitating the replacement of the intermediate transfer belt 10.

[0030] Therefore, the above-mentioned "Patent Document 1" proposes a technique for cleaning the scale tape by placing a rotating brush (indicated as reference numeral 60 in Figure 3) with bristles implanted on a roller that tensions the intermediate transfer belt upstream of the scale sensor, and a technique for cleaning the scale tape by clamping the intermediate transfer belt with a bracket equipped with a double-sided brush located downstream of the scale sensor. However, it was found that the technology disclosed in "Patent Document 1" has various problems as described in the "Problems to be Solved by the Invention" section. Therefore, a technology to solve these various problems is described below as one embodiment of the present invention.

[0031] Figure 8 is a schematic diagram illustrating a scale sensor 9, which is a detection means for detecting the scale tape 8, the part to be detected as described above. The scale sensor 9 is equipped with an upstream reading section 9a and a downstream reading section 9b, and optically reads the amount of movement of the scale tape 8 using these two reading sections. The upper surface of the scale sensor 9, on which the reading sections 9a and 9b are provided, serves as the belt sliding surface of the intermediate transfer belt 10. The sliding surface can be configured with a felt-like material (not shown) that is flocked, or with two ribs that protrude in a direction parallel to the scale tape 8 without flocking, and is configured to contact the scale tape 8 provided on the intermediate transfer belt 10 which is driven to move. A holding component (not shown) is provided at a position opposite the scale sensor 9 via the intermediate transfer belt 10, which contacts the front surface of the intermediate transfer belt 10 and sandwiches the intermediate transfer belt 10 with felt-like flocking or sponge, etc. Due to the action of this holding component (not shown), the intermediate transfer belt 10 is held and pressed so that the distance from the scale sensor 9 remains constant without flapping in the vertical direction.

[0032] The scale sensor 9 optically reads the scale marks M on the scale tape 8. To prevent scratches and dirt from being rubbed onto the reading sections 9a and 9b by the movement of the intermediate transfer belt 10, the reading sections 9a and 9b are positioned in recesses that are set back from the sliding surface. The surface of the recesses where the reading sections 9a and 9b are located is provided with a transparent protective material such as Mylar to prevent contaminating substances such as toner and paper dust from entering the recesses. However, if the device body is heavily contaminated, contaminating substances may accumulate in the recesses, potentially preventing the scale sensor 9 from optically reading the scale tape 8. In such cases, a service technician or other worker needs to remove the intermediate transfer belt 10 and remove the contaminating substances accumulated in the recesses using air or a soft cloth.

[0033] The contaminants that accumulate in the recess of the scale sensor 9 mainly accumulate from the surface side of the intermediate transfer belt 10 and the photoreceptor 40 side. This is because toner that falls directly from the developing unit and photoreceptor unit, as well as untransferred toner generated during primary and secondary transfer, peels off from the surface of the intermediate transfer belt 10 and disperses into the main body of the device, accumulating as toner stains on the surface edge of the intermediate transfer belt 10. The toner stains adhering to the surface edge of the intermediate transfer belt 10 are then rubbed off by airflow and sealing members in contact with the belt surface, etc., and move to the back side of the intermediate transfer belt 10, where contaminants accumulate on the back side of the intermediate transfer belt 10. The contaminants accumulated on the back side then contaminate the scale tape 8 and the scale sensor 9 located on the back side of the intermediate transfer belt 10, ultimately preventing the scale sensor 9 from optically reading the scale tape 8, and making belt speed control by the scale sensor 9 impossible. For this reason, periodic removal of contaminants by an operator is necessary, either when contaminants accumulate or when necessary.

[0034] Figure 9 shows a belt cleaning device used in one embodiment of the present invention. In Figure 9, the belt cleaning device 75 has a member that scrapes off contaminants accumulated on the surface of the intermediate transfer belt 10 and contaminants that have spread to the back surface of the intermediate transfer belt 10, making it possible to constantly clean contaminants attached to the scale tape 8 and the scale sensor 9. This makes it possible to constantly maintain the detection level required for the scale sensor 9 to read the scale tape 8. Specifically, the device comprises a first cleaning member that cleans the back surface of the intermediate transfer belt 10 and the scale tape 8 provided on the back surface of the intermediate transfer belt 10, and a second cleaning member that cleans the surface of the intermediate transfer belt 10.

[0035] The first cleaning member is a brush roller 76 rotatably supported by the roller shaft 71a of the drive roller 71. As shown in Figure 10, the brush roller 76 is positioned at one end of the drive roller 71, and its position corresponds to the position of the scale tape 8 provided inside the intermediate transfer belt 10. As shown in Figure 11, the brush roller 76 is fixed to a brush collar 76a rotatably supported by the roller shaft 71a, and its surface is fitted with brush bristles for removing contaminants adhering to the scale tape 8. The brush roller 76 receives driving force from the intermediate transfer belt 10 on which the surface of the brush bristles runs, and rotates together with the brush collar 76a in accordance with the driving force of the intermediate transfer belt 10.

[0036] As described above, the brush roller 76 can rotate independently of the drive roller 71 without being affected by the drive roller 71's rotational speed. Therefore, even if a speed difference occurs between the brush roller 76 and the drive roller 71 when the surface of the brush member contacts the intermediate transfer belt 10 and rotates with it, the effects of rotational irregularities caused by this speed difference are not transmitted to the drive roller 71. This prevents rotational irregularities from occurring in the drive roller 71, and thus prevents the generation of abnormal images caused by rotational irregularities in the drive roller 71.

[0037] Furthermore, since the stationary brush roller 76 rotates by receiving driving force from the intermediate transfer belt 10, it is expected to have a strong scraping effect on the intermediate transfer belt 10, thus scraping off accumulated contaminants. The surface of the brush member of the brush roller 76 is set to have a penetration depth of about 0.3 to 0.5 mm with respect to the intermediate transfer belt 10. As a result, at the moment the surface of the brush member bites into the intermediate transfer belt 10, the radius of the brush roller 76 changes due to the penetration, and the moving speed of the surface of the brush member is constantly changing. Therefore, a speed difference is obtained between the back surface of the belt and the surface of the intermediate transfer belt 10 when in contact with it, and the effect of scraping off contaminants can be obtained even with driven rotation.

[0038] The second cleaning member is a cleaning brush 77 positioned opposite the brush roller 76 via the intermediate transfer belt 10, and contacting the outer circumferential surface of the intermediate transfer belt 10 to clean this surface. As shown in Figures 12, 13, and 14, the cleaning brush 77 is fixed to a bracket 78 provided at a predetermined distance from the outer circumferential surface of the intermediate transfer belt 10, and its position corresponds to the position of the scale tape 8 provided inside the intermediate transfer belt 10. The curved bracket 78 has an arc-shaped mounting surface on its inner side that is concentric with the rotation axis of the drive roller 71 to which the cleaning brush 77 is attached. That is, the cleaning brush 77 fixed to the bracket 78 is configured such that its surface has approximately the same curvature as the surface of the drive roller 71, i.e., the outer circumferential surface of the brush roller 76. The bracket 78 is attached to the side plate 80 of the intermediate transfer unit 6 (see Figure 14).

[0039] With the above configuration, by fixing the cleaning brush 77, which has a rectangular cross-section and bristles of equal length across its entire surface, to the bracket 78 by attaching it or the like, the surface of the brush member of the cleaning brush 77 can be embedded in the surface of the intermediate transfer belt 10, which is wrapped around the drive roller 71, by an equal length. The amount of embedment of the surface of the brush member of the cleaning brush 77 into the intermediate transfer belt 10 is set to about 0.3 to 0.5 mm, similar to the brush roller 76. This makes it possible to maintain an equal amount of embedment in the entire range over which the cleaning brush 77 is embedded in the intermediate transfer belt 10, and to maintain a stable ability to scrape off contaminants. In the above configuration, the shape of the cleaning brush 77 can be simplified, and the processing to equalize the length of the bristles on the surface of the brush member can be simplified, thereby reducing manufacturing costs. Since the cleaning brush 77 is fixed to the intermediate transfer belt 10 which is driven to move, a speed difference is constantly generated between the intermediate transfer belt 10 and the cleaning brush 77 when the intermediate transfer belt 10 moves, so the surface of the intermediate transfer belt 10 can be cleaned effectively.

[0040] The contaminants scraped from the surface of the intermediate transfer belt 10 by the cleaning brush 77 fall into a storage member 79 located below the area where the brush roller 76 and the cleaning brush 77 come into contact, and are stored there. As shown in Figure 9, the storage member 79 is sized to be able to catch the contaminants falling from the surface of the intermediate transfer belt 10 over a wide area, and is positioned to reliably catch the falling contaminants. The storage member 79 is detachably attached to a frame (not shown) of the intermediate transfer unit 6, and by having a service technician or other worker periodically clean the storage member 79, it is possible to prevent the contaminants stored in the storage member 79 from contaminating the inside of the device body or the transport path.

[0041] Most of the contaminants adhere to the surface of the intermediate transfer belt 10, and since cleaning with the cleaning brush 77 removes almost all of the contaminants adhering to the surface of the intermediate transfer belt 10, the amount of contaminants that move from the front side to the back side of the intermediate transfer belt 10 is minimized. As a result, even without providing a mechanism to collect contaminants adhering to the surface of the brush member of the brush roller 76 that cleans the back side of the intermediate transfer belt 10, a natural cleaning operation can be continuously performed without causing contamination at a level that affects the formed image or the movement of the intermediate transfer belt 10. In this embodiment, examples of materials used for the brush members of the brush roller 76 and cleaning brush 77 include synthetic resin fibers and conductive PET resin. In this embodiment, the brush member is constructed by implanting conductive PET resin fibers into a resin color part or PET sheet, with a bristle length of 4 to 6 mm and a penetration depth of approximately 0.3 to 0.5 mm.

[0042] Next, the wrapping angle of the intermediate transfer belt 10 around the drive roller 71 in one embodiment of the present invention will be explained with reference to Figure 15. In the present invention, the angle from the contact start point A to the contact end point B between the intermediate transfer belt 10 and the drive roller 71 is defined as the wrapping angle of the intermediate transfer belt 10 around the drive roller 71. Similarly, the wrapping angle of the intermediate transfer belt 10 around the brush roller 76, which is the first cleaning member, is approximately the same as the wrapping angle of the intermediate transfer belt 10 around the drive roller 71, since the drive roller 71 and the brush roller 76 are arranged coaxially and the diameter of the brush roller 76 is approximately the same as the diameter of the drive roller 71, with the difference being only slightly. In this embodiment, the wrapping angle of the intermediate transfer belt 10 around the drive roller 71 and the wrapping angle of the intermediate transfer belt 10 around the brush roller 76 are approximately 140 degrees.

[0043] The larger the wrapping angle of the intermediate transfer belt 10 around the brush roller 76, the longer the contact time and contact distance between the brush roller 76 and the intermediate transfer belt 10. This allows the intermediate transfer belt 10 to continuously receive greater driving force, thereby increasing its cleaning ability on the back surface. In configurations like the one disclosed in "Patent Document 1," where the cleaning member, the brush, and the belt are wrapped around each other at an angle of about 30 degrees and there is no opposing member to clean the surface, the contact time and distance between the brush and the belt are short, making it difficult to receive sufficient driving force from the belt, resulting in a smaller cleaning capacity compared to the configuration of this embodiment. Therefore, in conventional configurations, when the inside of the device is heavily soiled, the rate of accumulation of contaminating substances exceeds the cleaning rate, making it difficult to maintain a level of cleanliness of the scale tape sufficient for the scale sensor to continue reading.

[0044] However, in the configuration of this embodiment, the wrapping angle of the intermediate transfer belt 10 around the brush roller 76 is 90 degrees or more, allowing the brush roller 76 to continuously receive a greater driving force from the intermediate transfer belt 10. As a result, a greater cleaning capacity can be obtained compared to the conventional configuration, and the cleanliness of the scale tape 8 can be maintained to a sufficient extent that readings by the scale sensor 9 can continue. As described above, a configuration that can fully demonstrate the effects of the present invention requires a winding angle of 90 degrees or more between the roller and the belt. Therefore, as shown in Figure 2, the drive roller 71 or the roller 68 is suitable as the predetermined roller in the present invention.

[0045] The greater the angle at which the belt wraps around the cleaning element, the better the cleaning ability of the element. However, the influence of the cleaning element on the belt's movement increases proportionally. When this influence exceeds a certain level, rotational irregularities of the cleaning element destabilize the belt's speed, resulting in image irregularities in the output image due to belt speed fluctuations. These image irregularities due to speed fluctuations are more likely to occur in positions where the belt is slack and upstream of the drive roller or downstream of the scale sensor. In these positions, the belt flutters, causing the values ​​read by the scale sensor on the scale tape to become unstable, which easily affects the image.

[0046] To prevent such problems from occurring, the present invention provides a first cleaning member that cleans the inner surface of the belt on the coaxial axis of the drive roller around which the belt is wrapped at an angle of 90 degrees or more, and a second cleaning member that contacts the outer surface of the belt on the opposite side of the first cleaning member. With this configuration, the belt is sufficiently wrapped around the first cleaning member, and the cleaning member can be positioned at the location where belt slack is least likely to occur, allowing for belt cleaning. As a result, even when sufficient contact length, contact time, and penetration amount are applied to the belt to prevent contamination of the scale tape, the running performance and rotational performance of the belt and drive roller are not affected, and the occurrence of abnormal images can be continuously prevented.

[0047] Figures 16 and 17 illustrate a method for attaching and detaching the intermediate transfer belt 10 in one embodiment of the present invention. The intermediate transfer unit 6 is supported at both ends in the belt travel direction by slide rail holding members 6a provided on the device body 2. In Figure 16, it is fixed to the slide rail holding members 6a by a faceplate (not shown) provided on the front side of each slide rail holding member 6a, and is positioned in the front-rear direction relative to the device body 2. When attaching or detaching the intermediate transfer belt 10 from the intermediate transfer unit 6, the faceplate (not shown) is removed to the state shown in Figure 16, and from this state, the tension roller 15 that applies tension to the intermediate transfer belt 10 is removed to create sufficient slack in the intermediate transfer belt 10 for removal.

[0048] On the outside of the intermediate transfer belt 10, there are retaining parts and storage members 79 (not shown) positioned opposite the scale sensor 9. After removing these parts, a service technician or other worker can remove the intermediate transfer belt 10 by grasping both ends of the intermediate transfer belt 10 and pulling it horizontally towards the front relative to the intermediate transfer unit 6. As shown in Figure 17, the intermediate transfer belt 10 is positioned at a height of approximately 750 mm from the mounting surface of the color copier 1. When a typical adult male worker, approximately 1700 mm tall, performs the intermediate transfer belt 10 replacement work, he will need to look down at the intermediate transfer belt 10 from diagonally above to remove it from the intermediate transfer unit 6.

[0049] Because the replacement of the intermediate transfer belt 10 is performed in the manner described above, the parts located at the bottom of the intermediate transfer unit 6 are in a blind spot for the worker. If the intermediate transfer belt 10 is removed without removing the necessary parts, the intermediate transfer belt 10 and the parts may interfere with each other, causing damage such as scratches or breaks, which may necessitate replacement. The intermediate transfer belt 10 is made of high-gloss polyimide with a thickness of about 0.6 mm or has an elastic layer on its surface, but all of them are prone to breakage and damage and are expensive, so replacement work must be carried out carefully.

[0050] In this embodiment, the second cleaning member, the cleaning brush 77, is positioned on the surface side of the intermediate transfer belt 10, opposite the first cleaning member, the brush roller 76, which is located coaxially with the drive roller 71, via the intermediate transfer belt 10. Therefore, when attaching or detaching the intermediate transfer belt 10, it is necessary to remove the cleaning brush 77 and the bracket 78 that secures the cleaning brush 77 from the intermediate transfer unit 6. When removing the cleaning brush 77, if it is positioned below the intermediate transfer belt 10, as described above, it may become a blind spot for the worker during replacement work, potentially leading to it being forgotten and damaging the expensive intermediate transfer belt 10.

[0051] In general, in an image forming apparatus where a transfer sheet is conveyed horizontally and multiple photoreceptors are arranged horizontally, the intermediate transfer unit is positioned opposite each photoreceptor, resulting in a horizontally elongated inverted triangle shape. In this case, in order to obtain the frictional force necessary to drive the intermediate transfer belt, if the drive roller is to be positioned to obtain a sufficient belt winding angle, the drive roller will inevitably be positioned at either end of the intermediate transfer unit, i.e., at either end of the inverted triangle shape. For this reason, by positioning the cleaning brush 77 and the bracket 78 that holds it, as shown in this embodiment, opposite the drive roller 71 and above the intermediate transfer belt 10, it is possible to prevent the cleaning brush 77 from being positioned in the operator's blind spot when removing the intermediate transfer belt 10.

[0052] Furthermore, when removing the intermediate transfer belt 10 from the intermediate transfer unit 6, the worker grasps both ends of the intermediate transfer belt 10 and removes it by pulling it horizontally towards the worker. Therefore, by positioning the cleaning brush 77 and bracket 78 on either end of the intermediate transfer unit 6, the cleaning brush 77 and bracket 78 are positioned near the position where the worker grasps the intermediate transfer belt 10 during attachment and detachment, making it easier for the worker to notice if they have forgotten to remove the cleaning brush 77 and bracket 78 during attachment and detachment of the intermediate transfer belt 10. This reliably prevents damage to the intermediate transfer belt 10 during replacement work caused by forgetting to remove parts that need to be removed.

[0053] In the above embodiment, an example was shown in which a color copier that forms full-color images was used as an image forming apparatus to which the present invention can be applied. However, the present invention is not limited to this, and can also be applied to printers, facsimile machines, multifunction devices, etc. Furthermore, although the above embodiment shows a configuration in which a transfer sheet S is used as the recording medium on which the image is formed, this transfer sheet S is not limited to recording paper, but also includes cardboard, postcards, roll paper, envelopes, plain paper, thin paper, coated paper (such as coated paper or art paper), tracing paper, OHP sheets, OHP films, resin films, etc., and any material that can form an image in sheet form may be used.

[0054] Examples of the present invention are as follows: [1] A belt conveying device comprising: an endless belt member stretched over a plurality of rollers and capable of traveling in the direction of travel by receiving a driving force from a drive member; a detectable portion provided on the inner circumferential surface of the belt member near at least one end in the width direction perpendicular to the direction of travel; detection means for detecting the detectable portion; and control means for controlling the travel operation of the belt member based on the detection result of the detection means for the detectable portion; a belt cleaning device provided on a predetermined roller among the plurality of rollers around which the belt member is wrapped at an angle of 90 degrees or more, which contacts the detectable portion to clean the detectable portion; and a second cleaning member positioned opposite the first cleaning member via the belt member, which contacts the outer circumferential surface of the belt member to clean the outer circumferential surface. [2] The belt cleaning device according to [1], characterized in that the first cleaning member is a rotating body provided coaxially with the predetermined roller. [3] The belt cleaning device according to [1] or [2], characterized in that the predetermined roller is the drive member. [4] The belt cleaning device according to any one of [1] to [3], characterized in that the second cleaning member is a fixed member that contacts the outer peripheral surface at a fixed position. [5] The belt cleaning device according to any one of [1] to [4], characterized in that the second cleaning member is located on the upper part of the belt member. [6] The belt cleaning device according to any one of [1] to [5], characterized in that the second cleaning member is configured such that its surface has substantially the same curvature as the outer surface of the predetermined roller. [7] The belt cleaning device according to [2], characterized in that the rotating body is provided with a brush member on its surface. [8] The belt cleaning device according to [2] or [7], characterized in that the rotating body is rotatable relative to the predetermined roller and rotates in contact with the detected portion provided on the traveling belt member. [9] The belt cleaning device according to [4], characterized in that the fixed member has a brush member on its surface.

[10] An image forming apparatus characterized by comprising a belt conveying device and a belt cleaning device according to any one of claims 1 to 9.

[0055] Although preferred embodiments of the present invention have been described above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the spirit of the invention as described in the claims, unless otherwise specifically limited in the above description. The effects described in the embodiments of the present invention are merely illustrative of the most preferred effects that may arise from the present invention, and the effects of the present invention are not limited to those described in the embodiments. [Explanation of Symbols]

[0056] 1. Image forming apparatus (color copier) 6. Belt conveying device (intermediate transfer unit) 8. Detected area (scale tape) 9. Detection means (scale sensor) 10 Belt component (intermediate transfer belt) 68. Designated roller (roller) 71 Drive member, predetermined roller (drive roller) 72 Control means (drive control device) 75 Belt cleaning device 76. First cleaning component (brush roller) 77. Second cleaning component (cleaning brush) V-belt travel direction X Belt width direction [Prior art documents] [Patent Documents]

[0057] [Patent Document 1] Japanese Patent Publication No. 2017-167498

Claims

1. A belt conveying device comprising: an endless belt member stretched over multiple rollers and capable of traveling in the direction of travel by receiving driving force from a drive member; a detection portion provided on the inner circumferential surface near at least one end of the belt member in the width direction perpendicular to the direction of travel; detection means for detecting the detection portion; and control means for controlling the travel operation of the belt member based on the detection result of the detection portion by the detection means, A first cleaning member is provided on a predetermined roller among the plurality of rollers around which the belt member is wrapped at an angle of 90 degrees or more, and which contacts the detected part to clean the detected part. A second cleaning member is positioned opposite the first cleaning member via the belt member and contacts the outer circumferential surface of the belt member to clean the outer circumferential surface, A belt cleaning device equipped with a belt cleaning device.

2. In the belt cleaning device according to claim 1, The belt cleaning device is characterized in that the first cleaning member is a rotating body provided coaxially with the predetermined roller.

3. In the belt cleaning device according to claim 1, A belt cleaning device characterized in that the predetermined roller is the drive member.

4. In the belt cleaning device according to claim 1, The belt cleaning device is characterized in that the second cleaning member is a fixed member that contacts the outer circumferential surface at a fixed position.

5. In the belt cleaning device according to claim 1, A belt cleaning device characterized in that the second cleaning member is positioned on the upper part of the belt member.

6. In the belt cleaning device according to claim 1, The belt cleaning device is characterized in that the second cleaning member is configured such that its surface has substantially the same curvature as the outer surface of the predetermined roller.

7. In the belt cleaning device according to claim 2, The belt cleaning device is characterized in that the rotating body has a brush member on its surface.

8. In the belt cleaning device according to claim 2, The belt cleaning device is characterized in that the rotating body is rotatable relative to the predetermined roller and rotates in contact with the detected portion provided on the traveling belt member.

9. In the belt cleaning device according to claim 4, A belt cleaning device characterized in that the fixed member has a brush member on its surface.

10. An image forming apparatus characterized by comprising a belt conveying device and a belt cleaning device according to any one of claims 1 to 9.

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