Tension roller unit, belt unit and image forming device

Abstract

To provide a tension roller unit, a belt unit and image forming device capable of simplifying pressurization release work.SOLUTION: A tension application mechanism 160, which serves as a tension roller unit, comprises: a tension roller 16 that comes into contact with a front surface of an intermediate transfer belt, which serves as a belt member, to apply tension to the intermediate transfer belt; a first pressurization mechanism 170a that serves as first pressurization means for performing pressurization to one axial end of the tension roller 16 toward the intermediate transfer belt; and a second pressurization mechanism 170b that serves as second pressurization means for performing pressurization to the other axial end of the tension roller 16 toward the intermediate transfer belt. The tension application mechanism 160 also comprises a pressure release lever 180 that serves as pressurization release means for simultaneously releasing the pressurization performed by the first pressurization mechanism 170a and the second pressurization mechanism 170b.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a tension roller unit, a belt unit, and an image forming apparatus. [Background technology]

[0002] Conventionally, a tension roller unit has been known which includes a tension roller that contacts the front surface of a belt member to apply tension to the belt member, a first pressure means that presses one axial end of the tension roller toward the belt member, and a second pressure means that presses the other axial end of the tension roller toward the belt member.

[0003] Patent Document 1 describes a tension roller unit in which the first pressure means and the second pressure means each have a tension spring as a biasing member, and describes that an operator can release the pressure of each pressure means by removing the hook portion of the tension spring of each pressure means from the hook portion. Summary of the Invention [Problem to be solved by the invention]

[0004] However, there was a problem that the operation of releasing the pressure was complicated. [Means for solving the problem]

[0005] In order to solve the above-mentioned problems, the present invention provides a tension roller unit comprising a tension roller that contacts the front surface of a belt member to apply tension to the belt member, a first pressure means that presses one axial end of the tension roller toward the belt member, and a second pressure means that presses the other axial end of the tension roller toward the belt member, and is characterized in that it also comprises a pressure release means that simultaneously releases the pressure applied by the first pressure means and the second pressure means. Effect of the Invention

[0006] According to the present invention, the operation of releasing pressure can be simplified. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic configuration diagram of a printer according to an embodiment of the present invention. [Diagram 2] FIG. [Diagram 3] FIG. 2 is a front view of the exterior of the printer with the pair of front doors open. [Figure 4] 1A is an enlarged front view of the area around the transfer door when the transfer door is closed, and FIG. 1B is an enlarged front view of the area around the transfer door when the transfer door is open. [Diagram 5] FIG. 2 is a schematic diagram showing a belt cleaning device, a lubricant application device, and a tension applying mechanism. [Figure 6] FIG. 2 is a schematic perspective view of an intermediate transfer unit pulled out from the main body of the apparatus. [Figure 7] FIG. 4 is a schematic perspective view of the intermediate transfer unit with the inner cover removed. [Figure 8] FIG. 4 is a schematic diagram illustrating a state in which the intermediate transfer belt is removed from the intermediate transfer unit. [Figure 9] FIG. [Figure 10] FIG. [Figure 11] Cross section AA of Figure 10. [Figure 12] FIG. [Figure 13] FIG. 4 is a schematic diagram of a pressing arm of a second pressurizing mechanism. [Figure 14] Schematic perspective view of a pressure release lever [Figure 15] Schematic diagram of the pressure release lever and its surroundings seen from below. [Figure 16] Cross section B-B of Figure 15 [Figure 17] FIG. [Figure 18] 5A and 5B are diagrams for explaining the pressure contact of a tension roller against an intermediate transfer belt by a pressure mechanism. [Figure 19]FIG. 4 is a perspective view of a tension applying mechanism attached to the intermediate transfer unit, as viewed from below. [Figure 20] 11A and 11B are diagrams illustrating the release of pressure from the first pressure mechanism and the second pressure mechanism by a pressure release lever. [Figure 21] Enlarged view of the pressure release lever area. [Figure 22] 5 is a schematic diagram showing an example of an operation of a pressure release lever. FIG. [Figure 23] 5A and 5B are diagrams illustrating a state of the intermediate transfer belt before and after the tension applying mechanism is removed. [Figure 24] FIG. 4 is a schematic diagram showing a state in which an inner cover and a front panel are removed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The best mode for carrying out the present invention will be described below with reference to the drawings. Note that a person skilled in the art can easily modify and alter the present invention within the scope of the claims to create other embodiments, and these modifications and alterations are included in the scope of the claims. The following description is an example of the best mode for carrying out the present invention, and does not limit the scope of the claims.

[0009] A so-called tandem type intermediate transfer printer (hereinafter simply referred to as printer) will be described below as an embodiment of an image forming apparatus to which the present invention is applied. First, the basic configuration of this printer will be described. FIG. 1 is a schematic diagram of a printer 60 according to this embodiment. This printer 60 has four process units 6Y, M, C, and K for generating toner images of yellow (Y), magenta (M), cyan (C), and black (K).

[0010] The four process units 6Y, M, C, K each have a drum-shaped photoconductor 1Y, M, C, K. Around the photoconductor 1Y, M, C, K are charging devices 2Y, M, C, K, developing devices 5Y, C, M, K, drum cleaning devices 4Y, M, C, K, and static eliminators. The process units 6Y, M, C, K each use a different color Y, M, C, K toner, but otherwise have the same configuration.

[0011] An optical writing unit 20 is disposed above the process units 6Y, M, C, and K for irradiating the surfaces of the photoconductors 1Y, M, C, and K with laser light L to write electrostatic latent images. An intermediate transfer unit 7 is disposed below the process units 6Y, M, C, and K as a pull-out unit having an endless intermediate transfer belt 8 as a belt member. In addition to the intermediate transfer belt 8, the intermediate transfer unit 7 has a plurality of tension rollers disposed inside the loop of the intermediate transfer belt, a tension roller 16, a belt cleaning device 100, a lubricant application device 200, and the like.

[0012] Arranged inside the loop of the intermediate transfer belt 8 are four primary transfer rollers 9Y, M, C, and K, a driven roller 10, a drive roller 11, a secondary transfer opposing roller 12, three cleaning opposing rollers 13, 14, and 15, and an application brush opposing roller 17. Each of these rollers functions as a tension roller that tensions the intermediate transfer belt 8 by wrapping the intermediate transfer belt 8 around a portion of its circumferential surface.

[0013] Incidentally, the cleaning facing rollers 13, 14, and 15 do not necessarily have to have a function of applying a constant tension, and may be ones that rotate following the rotation of the intermediate transfer belt 8. The intermediate transfer belt 8 is caused to move endlessly in the clockwise direction in the figure by the rotation of the drive roller 11 that is driven to rotate clockwise in the figure by a drive means.

[0014] Four primary transfer rollers 9Y, M, C, K arranged inside the belt loop sandwich the intermediate transfer belt 8 between them and the photoconductors 1Y, M, C, K. This forms primary transfer nips for Y, M, C, K where the front surface of the intermediate transfer belt 8 comes into contact with the photoconductors 1Y, M, C, K. A primary transfer bias of the opposite polarity to the toner is applied to each of the primary transfer rollers 9Y, M, C, K by a power source.

[0015] In addition, the secondary transfer opposing roller 12 disposed inside the belt loop sandwiches the intermediate transfer belt 8 between itself and the secondary transfer roller 18 disposed outside the belt loop. This forms a secondary transfer nip where the front surface of the intermediate transfer belt 8 and the secondary transfer roller 18 come into contact with each other.

[0016] A secondary transfer bias having a polarity opposite to that of the toner is applied by a power source to the secondary transfer roller 18. Alternatively, a paper transport belt may be stretched across the secondary transfer roller, several support rollers, and a drive roller, and the intermediate transfer belt 8 and the paper transport belt may be sandwiched between the secondary transfer roller 18 and the secondary transfer opposing roller 12.

[0017] The belt cleaning device 100 disposed outside the belt loop includes a pre-cleaning unit 100a for roughly removing untransferred toner images on the intermediate transfer belt 8. It also includes a normally charged toner cleaning unit 100b for removing toner charged to the normally charged polarity on the intermediate transfer belt 8. It also includes an oppositely charged toner cleaning unit 100c for removing toner charged to the opposite polarity (positive polarity) to the normally charged polarity (negative polarity) on the intermediate transfer belt 8. The arrangement order of the above cleaning units 100a, 100b, and 100c is merely an example, and they may be arranged in the order of the pre-cleaning unit, the oppositely charged toner cleaning unit, and the normally charged toner cleaning unit.

[0018] Each of the cleaning units 100a, 100b, and 100c has a cleaning brush roller 101, a collection roller 102, and a scraping blade 103. The collection roller 102 collects toner adhering to the cleaning brush roller 101, and the scraping blade 103 comes into contact with the collection roller 102 to scrape off the toner from the roller surface.

[0019] A voltage of the opposite polarity (positive polarity) to the toner normally charged polarity (negative polarity) is applied to the pre-cleaning unit 100a and the cleaning brush roller 101 of the normally charged toner cleaning unit 100b, and the toner of the normally charged polarity on the intermediate transfer belt 8 is electrostatically removed. A voltage of a positive polarity larger than that of the cleaning brush roller 101 is applied to the collection roller 102 of the pre-cleaning unit 100a and the normally charged toner cleaning unit 100b, and the toner of the normally charged polarity attached to the cleaning brush roller 101 is electrostatically collected.

[0020] A voltage of normal toner charge polarity (negative polarity) is applied to the cleaning brush roller 101 of the oppositely charged toner cleaning unit 100c, and the toner of opposite charge polarity on the intermediate transfer belt 8 is electrostatically removed. A voltage of negative polarity larger than that of the cleaning brush roller 101 is applied to the collection roller 102 of the oppositely charged toner cleaning unit 100c, and the toner of opposite charge polarity attached to the cleaning brush roller 101 is electrostatically collected.

[0021] Three cleaning opposing rollers 13, 14, and 15 arranged inside the belt loop sandwich the intermediate transfer belt 8 between themselves and the cleaning brush rollers 101 of each cleaning section. This forms a cleaning nip where the front surface of the intermediate transfer belt 8 comes into contact with the cleaning brush rollers 101 of each cleaning section.

[0022] To protect the surface of the intermediate transfer belt 8, a lubricant is applied to the surface of the intermediate transfer belt 8 by a lubricant application device 200. The lubricant application device 200 includes a solid lubricant 202 such as a lump of zinc stearate, and an application brush roller 201 as an application member that contacts the solid lubricant 202 and applies the lubricant powder obtained by scraping it off from the solid lubricant 202 by rotation to the surface of the intermediate transfer belt 8.

[0023] The printer 60 of this embodiment includes a paper feed section 30 having a paper feed cassette 31 that stores recording paper P as a recording material, and a paper feed roller 32 that feeds the recording paper P from the paper feed cassette 31 to a paper feed path. Also, a pair of registration rollers 33 that receives the recording paper P sent from the paper feed section 30 and sends it toward the secondary transfer nip at a predetermined timing is provided on the right side of the above-mentioned secondary transfer nip in the drawing.

[0024] In addition, a fixing device 40 having a heating roller 41 and a pressure roller 42 that receives the recording paper P sent out from the secondary transfer nip and fixes the toner image onto the recording paper P is provided to the left of the secondary transfer nip described above in the figure.

[0025] A bottle storage section 50 is disposed in the upper right corner of the optical writing unit 20 in the figure. The bottle storage section 50 stores toner bottles 51Y, 51M, 51C, and 51K that contain toner for replenishing the toner to the developing devices 5Y, 51M, 51C, and 51K as necessary.

[0026] When image information is sent from a personal computer or the like, this printer rotates the drive roller 11 to move the intermediate transfer belt 8. The tension rollers other than the drive roller 11 are rotated following the belt. At the same time, the photoconductors 1Y, M, C, K of the process units 6Y, M, C, K are rotated. In addition, the surfaces of the photoconductors 1Y, M, C, K are uniformly charged by the charging devices 2Y, M, C, K, and an electrostatic latent image is formed on the charged surfaces by irradiating them with laser light L by the optical writing unit 20.

[0027] Then, the electrostatic latent images formed on the surfaces of the photoconductors 1Y, M, C, K are developed by the developing devices 5Y, M, C, K toner images are obtained on the photoconductors 1Y, M, C, K. The Y, M, C, K toner images are primarily transferred and superimposed on the front surface of the intermediate transfer belt 8 at the primary transfer nips for Y, M, C, K described above. As a result, a four-color superimposed toner image is formed on the front surface of the intermediate transfer belt 8.

[0028] Meanwhile, in the paper feed section 30, a paper feed roller 32 feeds out recording paper P one sheet at a time from a paper feed cassette 31 and transports it to a pair of registration rollers 33. Then, at a timing that can be synchronized with the four-color superimposed toner image on the intermediate transfer belt 8, the pair of registration rollers 33 is driven to feed the recording paper P into the secondary transfer nip, and the four-color superimposed toner image on the belt is transferred collectively (secondarily) onto the recording paper P. In this way, a full-color image is formed on the surface of the recording paper P. After the full-color image has been formed on the recording paper P, it is transported from the secondary transfer nip to a fixing device 40, where the toner image is fixed.

[0029] After the Y, M, C, and K toner images have been primarily transferred to the intermediate transfer belt 8, the photoconductors 1Y, M, C, and K are cleaned of residual toner by drum cleaning devices 4Y, M, C, and K. After that, the photoconductors are neutralized by a neutralization lamp and then uniformly charged by charging devices 2Y, M, C, and K in preparation for the next image formation. In addition, after the intermediate transfer belt 8 has been primarily transferred to the recording paper P, the belt cleaning device 100 cleans the residual toner from the intermediate transfer belt 8.

[0030] FIG. 2 is a front view of the appearance of the printer 60. As shown in FIG. 2, a pair of front doors 61a, 61b are provided on the front of the printer 60 as opening / closing covers for opening / closing an opening 60a of the printer body (hereinafter referred to as the device body). The front door 61a on the right side in the figure is rotatably attached to the right end of the device body by a hinge, and the front door 61b on the left side in the figure is rotatably attached to the right end of the device body by a hinge, so that the opening 60a of the device body is opened and closed in a double door manner.

[0031] FIG. 3 is an external front view of the printer 60 with the pair of front doors 61a, 61b open. 3, opening the pair of front doors 61a, 61b exposes the process units 6Y, M, C, K, the intermediate transfer unit 7, the fixing device 40, the paper transport section 62, and the paper discharge section 63. The paper transport section 62 transports the recording paper P sent from the paper feed section 30 toward the secondary transfer roller 18, and the paper discharge section 63 transports the recording paper that has passed through the fixing device 40 and discharges it outside the printer 60.

[0032] Each process unit 6Y, M, C, K is provided with a locking mechanism 21Y, M, C, K that locks the process unit to the apparatus body, and by releasing the lock with the locking mechanism, the process unit can be attached and detached from the front side of the apparatus. Each process unit 6Y, M, C, K may be configured to be removable from the apparatus body, and components of the process unit (photoconductor 1, charging device 2, developing device 5, drum cleaning device 4, etc.) may be replaced with the process unit removed.

[0033] The fixing device 40 also includes a locking mechanism 43 that locks the fixing device 40 to the device body, and can be attached and detached from the front side of the device by releasing the locking mechanism 43. The fixing device 40 may be configured to be placed on the paper discharge section 63, and the fixing device 40 may be attached and detached by pulling the paper discharge section 63 out of the device body and lifting the fixing device 40.

[0034] The paper transport section 62 and the paper discharge section 63 are provided so as to be removable from the device body. When a paper jam occurs, the jammed paper can be removed by releasing the locking mechanism 62a, 63b from the device body and removing the paper from the device body.

[0035] Further, the intermediate transfer unit 7 is provided with a small transfer door 70 which is an opening and closing member. Figure 4(a) is an enlarged front view of the area around the transfer door 70 when the transfer door 70 is closed, and Figure 4(b) is an enlarged front view of the area around the transfer door 70 when the transfer door 70 is open. The small transfer door 70 is provided with a locking member 75 that locks the small transfer door 70 in the closed position shown in Fig. 4(a). The locking member 75 is attached to the small transfer door 70 so as to be movable within a predetermined range in the vertical direction, and is biased vertically upward by a biasing member such as a spring. The locking member 75 has an operation portion 75b recessed inwardly to allow an operator to operate the locking member 75, and the operation portion 75b is exposed from the opening 70a of the small transfer door 70.

[0036] When opening the small transfer door 70, a finger is inserted into the operating portion 75b of the locking member 75 through the opening 70a of the small transfer door 70, and the locking member 75 is pushed downward against the biasing force of the spring. This causes the locking member 75 to move downward, releasing the lock, and the small transfer door 70 can be moved to the open position as shown in FIG. 4(b).

[0037] When the small transfer door 70 is opened, the upper part of the belt cleaning device 100, the lubricant application device 200, and the tension applying mechanism 160 serving as a tension roller unit supporting the tension roller 16, which were covered by the small transfer door 70, are exposed. Note that reference numeral 82 shown in Fig. 4 denotes a front frame 82 of the intermediate transfer unit 7, and reference numeral 90 denotes an inner cover serving as a cover member for covering the front frame 82 and the like.

[0038] The intermediate transfer unit 7 has a cleaning lock lever 110 for locking the belt cleaning device 100 to the intermediate transfer unit 7. By rotating the cleaning lock lever 110 90° counterclockwise from the state shown in FIG. 4B, the lock is released and the belt cleaning device 100 can be removed from the intermediate transfer unit 7. By rotating the lock lever 110 90° counterclockwise from the state shown in FIG. 4B, the cleaning opposing rollers 13, 14, and 15 are separated from the corresponding cleaning brush rollers, and the intermediate transfer belt 8 is separated from the three cleaning brush rollers of the belt cleaning device 100. This allows the belt cleaning device 100 to be removed from the intermediate transfer unit 7 without damaging the surface of the intermediate transfer belt 8.

[0039] The lubricant application device 200 has a lubricant lock lever 203 for locking the lubricant application device 200 to the intermediate transfer unit 7. By rotating this lubricant lock lever 203 counterclockwise by 90° from the state shown in FIG. 4(b), the lock is released and the lubricant application device 200 can be removed from the intermediate transfer unit 7.

[0040] The tension applying mechanism 160 is positioned by positioning pins 82a and 82b provided on the front frame 82 of the intermediate transfer unit, and is screwed to the intermediate transfer unit 7 by screws 89 serving as fastening portions.

[0041] FIG. 5 is a schematic diagram showing the belt cleaning device 100, the lubricant application device 200, and the tension applying mechanism 160. As shown in FIG. 5, the tension applying mechanism 160 has a first guide portion 165 that guides the movement (movement in the front-rear direction of the device) of the lubricant application device 200 as a removable unit when it is attached to the intermediate transfer unit 7. The tension applying mechanism 160 also has a second guide portion 166 that guides the movement (movement in the front-rear direction of the device) of the belt cleaning device 100 as a removable unit when it is attached to the intermediate transfer unit 7. The second guide portion 166 engages with a pair of guide grooves 104 provided on the upper surface of the case of the belt cleaning device 100, and guides the belt cleaning device 100 in the attachment / detachment direction with respect to the intermediate transfer unit 7.

[0042] In this way, by providing the tension applying mechanism 160 with the first guide portion 165, the lubricant applying device 200 can be easily attached to and detached from the intermediate transfer unit 7. Also, by providing the tension applying mechanism 160 with the second guide portion 166, the belt cleaning device 100 can be easily attached to and detached from the intermediate transfer unit 7.

[0043] FIG. 6 is a schematic perspective view of the intermediate transfer unit 7 when it is pulled out relative to the main body of the apparatus, and FIG. 7 is a schematic perspective view of the intermediate transfer unit with the inner cover 90, which is a cover member, removed.

[0044] The intermediate transfer unit 7 has a frame housing 80 that supports a plurality of tension rollers disposed inside the loop of the intermediate transfer belt 8, a tension applying mechanism 160, a belt cleaning device 100, a lubricant application device 200, and the like. The frame housing 80 is supported on slide rails 81 provided on the main body of the apparatus so as to be slidable in the front-rear direction of the apparatus.

[0045] 7, frame housing 80 is made of sheet metal and has a front frame 82 perpendicular to the front-rear direction of the device (the direction in which intermediate transfer unit 7 is pulled out, which is also the direction of the rotation axis of the tension roller), and a rear frame 83 also made of sheet metal and perpendicular to the front-rear direction of the device. In addition, horizontal frames 85 are arranged on both ends of frame housing 80 in the left-right direction of the device.

[0046] FIG. 8 is a schematic perspective view showing a state in which the intermediate transfer belt is removed from the intermediate transfer unit 7. As shown in FIG. 8, the frame housing 80 has a plurality of stay members 84. One end of each of the stay members 84 is fixed to the front frame 82.

[0047] 7, the frame housing 80 has a handle 124 as a gripping portion, and has a pair of front plates 120a, 120b made of sheet metal. Of the two front plates 120a, 120b, one front plate 120a is screwed to the right end of the front frame 82, and the other front plate 120b is screwed to the left end of the front frame 82.

[0048] One of the front plates 120a is formed with a circular positioning hole 122 which serves as a primary reference for positioning the intermediate transfer unit 7 relative to the device body. The other front plate 120b is formed with a slotted positioning hole 123 which is elongated in the left-right direction of the device and serves as a secondary reference for positioning the intermediate transfer unit 7 relative to the device body.

[0049] Screws are inserted into these positioning holes 122, 123 and screwed into screw holes 66a provided in a front side plate 66 of the apparatus body shown in FIG. 6, whereby the intermediate transfer unit 7 is positioned and fastened to the apparatus body.

[0050] The intermediate transfer unit 7 is fixed to the main body of the apparatus with screws, so that the intermediate transfer unit 7 cannot be easily pulled out from the main body of the apparatus. This prevents the intermediate transfer unit 7 from being pulled out during maintenance or other work performed by a serviceman.

[0051] As described above, the frame housing 80 supports many functional devices of the intermediate transfer unit, such as the multiple tension rollers disposed inside the loop of the intermediate transfer belt 8, the tensioning mechanism 160, the belt cleaning device 100, and the lubricant application device 200. In this way, the frame housing 80 supports many functional devices, and thus the load on the frame housing 80 becomes large. However, due to the structure of the frame housing 80 and the pair of front panels 120a, 120b fastened to the front frame 82 being positioned and fastened to the device main body, the frame housing 80 can firmly support these functional devices without being deformed, even if the load on the frame housing 80 is large.

[0052] A drive motor 86a for driving a separation mechanism for moving the Y, M, and C primary transfer rollers 9Y, 9M, and 9C toward and away from the photoconductor is attached to the front frame 82. A drive motor 86b for driving a separation mechanism for moving the K primary transfer roller 9K toward and away from the photoconductor is also attached to the front frame 82. A cable 87 for supplying power and the like to the drive motors 86a and 86b is laid around the front frame 82.

[0053] 6, a resin inner cover 90 is attached to the frame housing 80 as a cover member that covers the front panels 120a, 120b and the front frame 82. As a result, the drive motors 86a, 86b and the cable 87 attached to the front frame 82 are covered by the inner cover 90.

[0054] As described above, when a paper jam occurs, the pair of front doors 61a, 61b are opened, and then the paper transport section 62 and the paper discharge section 63 are pulled out to clear the jam. If the inner cover 90 does not cover the electrical components such as the drive motors 86a, 86b and the cable 87, there is a risk of accidentally touching these electrical components. As a result, for example, the cable may come off the drive motor, or the electrical components attached to the front frame 82 may be damaged. In addition, the front panels 120a, 120b and the front frame 82 are made of sheet metal, and if the user accidentally touches these sharp parts, there is a risk of injury.

[0055] Meanwhile, as shown in this embodiment, by covering the front panels 120a, 120b and the front frame 82 with the inner cover 90, it is possible to prevent the user from accidentally touching the drive motor and cables held by the front frame 82. It is also possible to prevent the user from accidentally touching dangerous points such as sharp parts of the front panels 120a, 120b and the front frame 82. Furthermore, by covering the front panels 120a, 120b and the front frame 82 with the inner cover 90, it is possible to improve the appearance when the front doors 61a, 61b are opened.

[0056] As shown in FIG. 6, screw guide holes 92 are provided at both left and right ends of the inner cover 90 to guide the screws that screw the intermediate transfer unit 7 to the device body. The screw guide holes 92 are provided to communicate with the positioning holes 122, 123 of the front plates 120a, 120b. When the intermediate transfer unit 7 is pulled out from the device body, a screwdriver is inserted into the screw guide hole 92 to access the screw screwed into the screw hole 66a of the front plate 66, and the screw is removed from the screw hole 66a. At this time, the screw may come off the screwdriver and fall. However, even if the screw falls from the screwdriver, the screw guide hole 92 can catch the screw, and the screw can be prevented from falling into the device body. That is, the screw guide hole 92 functions as a fall prevention portion.

[0057] The inner cover 90 is made of resin and has low rigidity. Therefore, if a handle for pulling out the intermediate transfer unit 7 is provided on the inner cover 90, the following problem occurs. That is, as described above, the intermediate transfer unit 7 is heavy because it includes many functional devices of the intermediate transfer unit, such as the tension applying mechanism 160, the belt cleaning device 100, and the lubricant application device 200. Therefore, when pulling out the heavy intermediate transfer unit 7 by gripping the handle provided on the inner cover 90, the inner cover 90 may be deformed.

[0058] On the other hand, as shown in Fig. 7, by providing handles on the front panels 120a, 120b of the frame housing 80, which is made of sheet metal and has high rigidity, the intermediate transfer unit 7 can be pulled out without deforming the front panels 120a, 120b. Also, as described above, the frame housing 80 is reinforced in the front-rear direction of the device by a plurality of stay members 84 (see Fig. 8). Therefore, when the intermediate transfer unit 7 is pulled out, the frame housing 80 will not deform. Note that the handle may be provided on the front frame 82 of the frame housing 80.

[0059] Since the inner cover 90 covers the front frame 82 and the front plates 120a and 120b of the frame housing 80, the handles 124 of the front plates 120a and 120b are also covered. Therefore, in this embodiment, as shown in Fig. 6, the inner cover 90 is provided with a recess 91 for accessing the handles 124 provided on the front plates 120a and 120b. The recess 91 of the inner cover 90 is located directly below the handle 124, and a hole is formed in the upper surface of the recess 91 to allow a serviceman, who is an operator, to access the handle 124.

[0060] When pulling out the intermediate transfer unit 7 from the device body, a service person can access the handle 124 by inserting his / her finger into the hole of the recess 91. This allows the intermediate transfer unit 7 to be pulled out from the device body by grasping the handles 124 provided on the front panels 120a, 120b without removing the inner cover 90. This simplifies the work of pulling out the intermediate transfer unit 7 compared to removing the inner cover 90 and pulling out the intermediate transfer unit 7.

[0061] Next, the tension applying mechanism 160, which is a characteristic feature of this embodiment, will be described. Fig. 9 is a schematic perspective view of a tension applying mechanism 160 serving as a tension roller unit, and Fig. 10 is a schematic plan view of the tension applying mechanism 160. Fig. 11 is a cross-sectional view taken along line AA in Fig. 10.

[0062] The tension applying mechanism 160 has a pair of roller holders 190 that rotatably support the tension roller 16, and a base member 161 that holds the roller holders 190 so that they can swing. The tension applying mechanism 160 also has a first pressure applying mechanism 170a that serves as a first pressure applying means for applying pressure to the front roller holder 190 to apply pressure to the front end of the tension roller 16 toward the intermediate transfer belt 8. The tension applying mechanism 160 also has a second pressure applying mechanism 170b that serves as a second pressure applying means for applying pressure to the rear roller holder 190 to apply pressure to the rear end of the tension roller 16 toward the intermediate transfer belt 8. Each of the pressure applying mechanisms 170a and 170b has a plurality of coil springs 171 and a pressure arm 172 that presses the roller holder 190.

[0063] The pressing arms 172 of each of the pressure mechanisms 170a, 170b are arranged side by side in the front-to-rear direction of the device (which is also the axial direction of the tension roller) and are disposed on the base member 161. Each pressing arm 172 is held on the base member 161 so as to be freely swingable in the left-to-right direction of the device, with swing shafts 169a, 169b provided on the base member 161 as fulcrums. The center end of each pressing arm 172 in the front-to-rear direction of the device is biased by two coil springs 171 in a direction away from the tension roller 16.

[0064] The tension applying mechanism 160 also has a pressure release lever 180 as a pressure release means for releasing the pressure applied by the pair of pressure mechanisms 170a, 170b. The pressure release lever 180 is held by the base member 161 so as to be slidable within a predetermined range in the left-right direction of the device. Specifically, the through shaft 168 of the base member 161 penetrates a through hole 180a extending in the left-right direction of the device provided at the center of the pressure release lever 180 in the front-rear direction of the device, so that the pressure release lever 180 is held so as to be slidable within a predetermined range in the left-right direction of the device. The pressure release lever 180 is also prevented from coming off the through shaft 168 by a retaining member 181 so as not to come off.

[0065] The end of the retaining member 181 on the tension roller side has a surface bent downward by 90 degrees, and an engagement groove 181a is formed in the center of this surface in the front-to-rear direction of the device. The engagement protrusion 161a of the base member 161 shown in FIG. 12 is fitted into this engagement groove 181a, and the retaining member 181 is fitted onto the through shaft 168, whereby the retaining member 181 is attached to the base member 161 so as to prevent the pressure release lever 180 from coming off the through shaft 168.

[0066] The pressure release lever 180 releases the pressure applied by each of the pressure mechanisms 170a, 170b by pressing the end portions of the pressing arms of the pressure mechanisms 170a, 170b on the central side in the front-rear direction against the biasing force of the coil spring 171, as described below.

[0067] As shown in FIG. 11, a second guide portion 166 is provided on the underside of the base member 161 to guide the movement (movement in the front-rear direction of the device) of the belt cleaning device 100 described above when it is attached to or detached from the intermediate transfer unit 7.

[0068] FIG. 12 is a schematic perspective view of the base member 161. As shown in FIG. The base member 161 is made of sheet metal, and its end on the front side of the device is bent 90° upward to form a positioning surface portion 162. This positioning surface portion 162 is provided with positioning holes 162a, 162b into which positioning pins 82a, 82b (see FIG. 4(b)) provided on the front frame 82 of the intermediate transfer unit 7 are inserted.

[0069] One of the positioning holes 162a is a round hole that serves as a primary reference for positioning, and the other positioning hole 162b is a secondary reference for positioning and is an elongated hole that extends in the left-right direction of the device. Between the positioning holes 162a and 162b of the positioning surface portion 162, there is provided a screw through hole 162c through which a screw 89 (see FIG. 4(b)) passes as a fastening portion for screwing the tension applying mechanism 160 to the front frame 82.

[0070] The base member 161 also has a first guide portion 165 that guides the movement (movement in the front-rear direction of the device) of the lubricant application device 200 described above when it is attached to or detached from the intermediate transfer unit 7. As will be described later, this first guide portion 165 functions as a gripping portion that is grasped by an operator when removing the tension applying mechanism 160 from the intermediate transfer unit 7.

[0071] Further, a holder holding plate 163 that swingably holds the front roller holder 190 is provided on the rear side of the positioning surface portion 162 of the base member 161 (inside the device). The holder holding plate 163 is provided with a holder support shaft 163a that swingably supports the roller holder 190 (see FIG. 10).

[0072] A predetermined distance Sp (see FIG. 10) is provided between the holder holding plate 163 and the positioning surface portion 162 in the front-rear direction of the device. As a result, when the tension applying mechanism 160 is attached to the intermediate transfer unit 7, a predetermined gap is formed between the holder holding plate 163 and the front frame 82, and the tension applying mechanism 160 is movable in the front-rear direction within the range of this gap. Therefore, when removing the tension applying mechanism 160 from the intermediate transfer unit 7, the tension applying mechanism 160 can be moved toward the device to remove the positioning pins 82a, 82b from the positioning holes 162a, 162b.

[0073] The rear end of the base member 161 is bent upward by 90 degrees to have a holder holding surface 167 that swingably holds the rear roller holder 190. The holder holding surface 167 is also provided with a holder support shaft 167a that swingably supports the rear roller holder 190.

[0074] Two positioning pins 167b, 167c (see FIG. 10) are provided on the surface (outer surface) opposite to the surface on which the holder support shaft 167a of the holder holding surface portion 167 is provided. The rear side of the tension applying mechanism 160 is positioned by inserting these positioning pins 167b, 167c into positioning holes of the intermediate transfer unit (frame housing). These positioning pins 167b, 167c are set to a length such that they can be removed from the positioning holes by moving the tension applying mechanism 160 toward the device as described above.

[0075] Further, a through shaft 168 for holding the above-mentioned pressure release lever 180 slidably in the left-right direction of the device is provided at the center of the base member 161 in the front-rear direction of the device. Further, the base member 161 is provided with a pair of swing shafts 169a, 169b for supporting the pressing arms 172 of the above-mentioned pressure mechanisms 170a, 170 so that they can swing freely.

[0076] In addition, the end of the base member 161 on the tension roller side is bent upward by 90°. On the surface portion formed by the bending, an engagement protrusion 161a that engages with the engagement groove 181a of the above-mentioned retaining member 181 and a spring receiver 161b that receives one end of the coil spring of each of the pressure mechanisms 170a and 170b are provided.

[0077] FIG. 13 is a schematic diagram of the pressing arm 172 of the second pressing mechanism 170b. 13, the pressing arm 172 has an engagement recess 172d at one end (the end on the front-rear central side of the tension applying mechanism) with which the slippage prevention protrusion 180b (see FIG. 14(a)) of the pressure release lever 180 engages. Also, one end of the pressing arm 172 has an abutment surface 172e with which the abutment protrusion 180c (FIG. 14(a)) of the pressure release lever 180 abuts.

[0078] The other end of the pressing arm 172 (the end on the front-rear direction side of the tension applying mechanism) has a pressing portion 172c that abuts against a pressed portion 190c (see FIG. 17) of the roller holder 190 to press the roller holder 190. The pressing arm 172 is provided with two spring holding projections 172a adjacent to the engagement recess 172d to which the other end of the coil spring 171 is attached. The pressing arm 172 also has a holding hole 172b into which the swing shaft 169b (see FIG. 9) is inserted. The swing shaft 169b is inserted into the holding hole 172b, so that the pressing arm 172 is held on the base member 161 so as to be able to swing freely. The pressing arm 172 of the first pressurizing mechanism 170a has a configuration obtained by flipping the pressing arm of FIG. 13 from left to right.

[0079] Fig. 14 is a schematic perspective view of the pressure release lever 180, (a) is a perspective view of the pressure release lever 180 seen from below, and (b) is a perspective view of the pressure release lever 180 seen from above. Fig. 15 is a schematic view of the periphery of the pressure release lever 180 seen from below, and Fig. 16 is a cross-sectional view taken along line B-B of Fig. 15. A through hole 180a extending in the left-right direction of the device is provided in the center of the pressure release lever 180 in the front-rear direction of the device. As shown in Fig. 15, the through shaft 168 of the base member 161 passes through this through hole 180a, so that the pressure release lever 180 is held slidable within a predetermined range in the left-right direction of the device.

[0080] 14(b), the area around the through shaft 168 at the top of the pressure release lever 180 is a stepped portion 180d that is one step lower. A retaining member 181 (see FIG. 9) engages with this stepped portion 180d, and the retaining member 181 also functions as a guide member that guides the sliding of the pressure release lever 180 in the left-right direction of the device.

[0081] 14(a), the pressure release lever 180 is provided with a pair of removal prevention protrusions 180b that prevent the pressure release lever 180 from being removed from each pressing arm 172. As shown in Fig. 16, each removal prevention protrusion 180b engages with an engagement recess 172d provided at the end of the pressing arm 172, preventing the pressure release lever 180 from being removed from each pressing arm 172. As shown in Fig. 16, the removal prevention protrusions 180b are not in contact with the pressing arm 172 so as not to impede the swinging of the pressing arm 172.

[0082] 14(a), the pressure release lever 180 is provided with a pair of contact protrusions 180c that come into contact with the contact surface 172e of the pressing arm 172. When the pressure of each pressurizing mechanism 170a, 170b is released by the pressure release lever 180, the contact protrusions 180c press the contact surface 172e against the biasing force of the coil spring 171, thereby swinging the pressing arm and releasing the pressure. The tip of the contact protrusion 180c is rounded so that the pressing arm 172 can swing smoothly.

[0083] The contact protrusion 180c may be omitted, and one end of the pressing arm may be pushed in by the release protrusion 180b when the pressure is released. However, it is preferable to provide the contact protrusion 180c and have it contact the surface opposite to the side (the surface where the spring holding protrusion 172a is provided) that receives the urging force from the coil spring 171 of the pressing arm. In this case, when the contact protrusion 180c is omitted and the release protrusion 180b pushes in one end of the pressing arm, the urging force of the coil spring 171 acts as a shear force on the release protrusion 180b. The pressure release lever 180 is made of a resin material with low rigidity, and the urging force of the coil spring 171 is strong. Therefore, there is a risk that the release protrusion 180b may be deformed or damaged. In contrast, when the contact protrusion 180c pushes in one end of the pressing arm, the urging force of the coil spring 171 acts as an axial force on the contact protrusion 180c. As a result, even if the pressure release lever 180 is made of a resin material with low rigidity and the biasing force of the coil spring 171 is strong, deformation or damage to the contact protrusion can be suppressed.

[0084] In addition, the symbol 180e shown in Figure 14 (b) is a recess that prevents the pressure release lever 180 from hitting the engagement protrusion 161a (see Figure 12) of the base member 161 when it is pushed in (slid toward the coil spring).

[0085] FIG. 17 is a schematic diagram of the roller holder 190. The roller holder 190 has a roller support hole 190a that rotatably supports the tension roller 16 via a bearing, a support hole 190b that is supported on the holder support shaft so as to be able to swing freely, and a pressed portion 190c that is pressed by the pressing portion of the pressing arm.

[0086] FIG. 18 is a diagram for explaining the pressure contact of the tension roller 16 against the intermediate transfer belt 8 by the pressure mechanisms 170a and 170b. As shown in FIG. 18, the center side of the pressing arm 172 is biased in the direction of the arrow F1 in FIG. 18(a) by the coil spring 171. The biasing force of the coil spring 171 causes the pressing arm 172 to swing around the swing shaft as a fulcrum so that the center side moves downward in FIG. 18(a). As a result, the pressing part 172c of the pressing arm 172 presses the pressed part 190c of the roller holder 190 in the direction of the arrow F2 in the figure. Then, the roller holder 190 rotates around the holder support shaft as a fulcrum in the direction of the arrow F3 in FIG. 18(b), and the tension roller held by the roller holder 190 moves in the direction of the arrow F4 in FIG. 18(b). As a result, both ends of the tension roller 16 are pressed toward the intermediate transfer belt 8, and tension is applied to the intermediate transfer belt 8.

[0087] When removing the tension applying mechanism 160 from the intermediate transfer unit 7, first, the belt cleaning device 100 and the lubricant application device 200 are removed, and the intermediate transfer unit 7 is pulled out from the main body of the apparatus (see FIG. 19). Next, the screws 89 (see FIG. 4(b)) are removed to release the fastening of the tension applying mechanism 160.

[0088] Next, the tension applying mechanism 160 is moved forward to remove the positioning pins 82a and 82b from the positioning holes 162a and 162b, and the positioning pins 167b and 167c (see FIG. 10) from the positioning holes. As described above, a predetermined gap is formed between the holder holding plate 163 and the front frame 82, so that the tension applying mechanism 160 can move forward by the amount of this gap. This allows the positioning pins 82a and 82b to be removed from the positioning holes 162a and 162b, and the positioning pins 167b and 167c (see FIG. 10) to be removed from the positioning holes.

[0089] If the tension roller 16 is applying tension to the intermediate transfer belt 8 when the positioning pins are removed from the positioning holes, the following problem occurs. That is, the tension roller 16 rubs against the front surface of the intermediate transfer belt 8 in the front-rear direction of the device, and there is a risk of damaging the front surface of the intermediate transfer belt 8. Therefore, when the tension applying mechanism 160 is moved forward to remove the positioning pins 82a, 82b from the positioning holes 162a, 162b, it is necessary to release the pressure of the pressure applying mechanisms 170a, 170b and separate the tension roller 16 from the intermediate transfer belt 8.

[0090] Conventionally, pressure was released by removing the hook portion of the coil spring of the pressure mechanism provided at the front side of the device and the hook portion of the coil spring of the pressure mechanism provided at the back side of the device. In order to remove the hook portions of these coil springs, it is necessary to crawl under the intermediate transfer unit, which is time-consuming and dangerous. However, in this embodiment, the pressure of both the first pressure mechanism 170a and the second pressure mechanism 170b can be released by simply pressing the pressure release lever 180 provided at the center of the front-rear direction of the device with one hand. This makes it possible to release the pressure of each pressure mechanism 170a, 170b and separate the tension roller 16 from the intermediate transfer belt 8 without danger or time-consuming work. Hereinafter, the pressure release of the first pressure mechanism 170a and the second pressure mechanism 170b by the pressure release lever 180 will be specifically described with reference to the drawings.

[0091] Fig. 20 is a diagram for explaining the pressure release of the first pressurizing mechanism 170a and the second pressurizing mechanism 170b by the pressure release lever 180, and Fig. 21 is an enlarged view of the vicinity of the pressure release lever. Also, Fig. 22 is a diagram showing an example of the operation of the pressure release lever 180. By pressing the pressure release lever 180 in the direction of the arrow F5 in Fig. 20 and Fig. 21(b), the abutted surface 172e of the pressing arm 172 of each pressurizing mechanism 170a, 170b is pressed into the abutting protrusion 180c of the pressure release lever 180. As a result, the center side of the pressing arm 172 in the device front-rear direction moves in the direction of the arrow F6 in Fig. 20 against the biasing force of the coil spring 171, and each pressing arm 172 swings around the swing shafts 169a, 169b as a fulcrum. As each pressing arm 172 swings, the pressing portion 172c of each pressing arm 72 moves in the direction of the arrow F7 in Fig. 20.

[0092] 20, the roller holder 190 rotates in the direction of the arrow F8 in FIG. 22 around the holder support shaft 167a due to the weight of the tension roller 16. As a result, the tension roller 16 moves in the direction of the arrow F9 in FIG. 22 and separates from the intermediate transfer belt 8.

[0093] Then, with the pressure release lever 180 pushed in to release the pressure, the tension applying mechanism 160 is moved forward to remove the positioning pin from the positioning hole. This allows the positioning pin to be removed from the positioning hole with the tension roller 16 separated from the intermediate transfer belt 8, preventing damage to the front surface of the intermediate transfer belt 8. Thereafter, with the pressure release lever 180 pushed in to release the pressure, the tension applying mechanism 160 is moved downward, and the tension applying mechanism 160 is removed from the intermediate transfer unit 7.

[0094] In this embodiment, the pressure from both the first pressure mechanism 170a and the second pressure mechanism 170b is released simply by pressing the pressure release lever 180, and the tension applying mechanism 160 can be easily attached to and detached from the intermediate transfer unit 7 without damaging the front surface of the intermediate transfer belt 8.

[0095] The first guide portion 165 is a gripping portion that an operator grasps when removing the tension applying mechanism 160 from the intermediate transfer unit 7 while pushing in the pressure release lever 180. Therefore, as shown in FIG. 22, an operator can grasp the tension applying mechanism 160 by pushing the tension release lever 180 with his / her thumb and pushing the surface of the first guide portion 165 on the tension roller side with his / her fingers other than the thumb in the opposite direction to the pushing direction of the pressure release lever 180. In this way, the tension applying mechanism 160 can be grasped with one hand in a state where the pressure release lever 180 is easily pushed in and the pressure is released. This simplifies the installation and removal work of the tension applying mechanism 160.

[0096] In this embodiment, as shown in Fig. 10, the pressing arms 172 of the pressing mechanisms 170a, 170b are arranged side by side in the front-rear direction of the device. This allows the pressing arms 172 of the pressing mechanisms 170a, 170b to be swung and released with a pressure release lever 180 provided in the center in the front-rear direction with a simple configuration. This allows the number of parts to be reduced, making the tension applying mechanism 160 smaller and preventing the cost of the tension applying mechanism 160 from increasing.

[0097] By pulling out the intermediate transfer unit 7 and removing the tension applying mechanism 160, the intermediate transfer belt 8 changes from the state shown by the solid line in Fig. 23 to the slackened state shown by the two-dot chain line. By slackening the intermediate transfer belt 8, the primary transfer rollers 9Y, 9M, 9C, and 9K in the loop of the intermediate transfer belt 8 and the secondary transfer opposing roller 12 can be removed from the frame housing 80 and replaced with new rollers.

[0098] When replacing the intermediate transfer belt 8, the tension applying mechanism 160 is removed, and then the inner cover 90 and the front panels 120a and 120b are removed.

[0099] FIG. 24 shows a state in which the inner cover 90 and the front panels 120a and 120b have been removed. 24, the front frame 82 is shorter than the distance from one horizontal frame to the other horizontal frame in the left-right direction of the device, and a predetermined gap S is formed between the front frame 82 of the frame housing 80 and the horizontal frame 85. By removing the inner cover 90 and the front plates 120a, 120b, a path for moving the intermediate transfer belt 8 to the front side is created. This allows the slack intermediate transfer belt 8 to pass through this gap and be removed from the intermediate transfer unit 7.

[0100] Thus, in this embodiment, when replacing the intermediate transfer belt 8, it is necessary to remove the inner cover 90. However, when replacing the tension applying mechanism 160, the lubricant application device 200, the belt cleaning device 100, and tension rollers such as the primary transfer rollers 9Y, 9M, 9C, and 9K in the loop of the intermediate transfer belt 8 and the secondary transfer opposing roller 12, which are supported by the intermediate transfer unit 7 (frame housing 80), they can be replaced without removing the inner cover 90. This makes it possible to shorten the maintenance work time for the intermediate transfer unit 7.

[0101] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the spirit of the present invention described in the claims, unless otherwise specifically limited in the above description.

[0102] The above description is merely an example, and each of the following aspects provides unique effects. (Aspect 1) In a tension roller unit such as a tension applying mechanism 160 that includes a tension roller 16 that contacts the front surface of a belt member such as an intermediate transfer belt 8 to apply tension to the belt member, a first pressure applying means such as a first pressure applying mechanism 170a that applies pressure to one axial end of the tension roller 16 toward the belt member, and a second pressure applying means such as a second pressure applying mechanism 170 that applies pressure to the other axial end of the tension roller 16 toward the belt member, the tension roller unit is provided with a pressure releasing means such as a pressure release lever 180 that simultaneously releases pressure from the first pressure applying means and the second pressure applying means. According to this, as described in the embodiment, the operator can release the pressure of both pressurizing means by operating the pressure release means, and the pressure of each pressurizing means can be released more easily than in Patent Document 1, in which the operator releases the pressure of each pressurizing means by removing the hook parts of the tension springs of each pressurizing means from the respective hook parts. This simplifies the pressure release operation.

[0103] (Aspect 2) In embodiment 1, a first pressure applying means such as the first pressure applying mechanism 170a and a second pressure applying means such as the second pressure applying mechanism 170b have a pressing arm 172 that is held so as to be able to swing and press a holding member such as a roller holder 190 that holds the axial end of the tension roller 16, and the pressing arm of the first pressure applying means and the pressing arm of the second pressure applying means are arranged in series in the axial direction. According to this, as explained in the embodiment, a pressure release means such as a pressure release lever 180 is disposed between the pressing arm of the first pressing means and the pressing arm of the second pressing means (at the center in the arrangement direction of the pressing arms), and the pressing arm of each pressing means is pushed in at the center end in the axial direction by the pressure release means, thereby making it possible to simultaneously release the pressure of each pressing means by swinging the pressing arm of each pressing means. In this way, it is possible to simultaneously release the pressure of each pressing means without using a complex mechanism such as a link mechanism, thereby suppressing an increase in the cost of the device and achieving a miniaturization of the device.

[0104] (Aspect 3) In embodiment 2, a pressure release means such as pressure release lever 180 simultaneously presses the axial center end of pressing arm 172 of a first pressing means such as first pressing mechanism 170a and the axial center end of the pressing arm of a second pressing means, causing each pressing arm to swing in the opposite direction to the swing direction pressing a holding member such as roller holder 190, thereby simultaneously releasing the pressure of the first pressing means and the second pressing means. According to this, as described in the embodiment, it becomes possible to simultaneously release the pressure from each pressure means without using a complex mechanism such as a link mechanism, thereby preventing an increase in the cost of the device and making the device smaller.

[0105] (Aspect 4) In aspect 3, when removing a tension roller unit such as the tension applying mechanism 160 from a belt unit such as an intermediate transfer unit 7 having a belt member such as an intermediate transfer belt 8, the tension roller unit has a gripping portion such as a first guide portion 165 that can be gripped by an operator while pressing a pressure release means such as a pressure release lever 180. According to this, as described in the embodiment, the tension roller unit such as the tension applying mechanism 160 can be removed from the belt unit such as the intermediate transfer unit with the pressure of each pressure means released and the tension roller 16 separated from the intermediate transfer belt 8, thereby preventing damage to the front surface of the belt member. In addition, the presence of the gripping portion such as the first guide portion 165 allows the tension roller unit to be easily removed from the belt unit while maintaining the released state of the pressure of each pressure means.

[0106] (Aspect 5) In any of aspects 1 to 4, there is a guide portion (first guide portion 165 and second guide portion 166 in this embodiment) that guides the attachment and detachment of a detachable unit (in this embodiment, a belt cleaning device 100 and a lubricant application device 200) that is configured to be detachable from a belt unit such as an intermediate transfer unit 7 having a belt member such as an intermediate transfer belt 8. According to this, as described in the embodiment, the detachable units such as the belt cleaning device 100 and the lubricant application device 200 can be easily attached and detached.

[0107] (Aspect 6) In a belt unit such as an intermediate transfer unit 7 having a belt member such as an intermediate transfer belt 8 and a tension roller unit such as a tension applying mechanism 160 that applies tension to the belt member by a tension roller 16, a tension roller unit according to any one of embodiments 1 to 5 was used as the tension roller unit. This makes it possible to easily release the tension applied to the belt member.

[0108] (Aspect 7) In an image forming apparatus equipped with a belt unit such as the intermediate transfer unit 7, the belt unit of embodiment 6 was used as the belt unit.

[0109] (Aspect 8) In aspect 7, a belt unit such as the intermediate transfer unit 7 includes a housing such as a frame housing 80 that supports a tension roller that stretches a belt member such as the intermediate transfer belt 8 and a tension roller unit such as a tension applying mechanism 160, and the belt unit is configured to be able to be pulled out from the main body of the image forming device. The belt unit has a cover member such as an inner cover 90 that covers the downstream side panel of the housing perpendicular to the pull-out direction on the downstream side of the pull-out direction of the belt unit, and the tension roller unit is configured to be removable from the belt unit without removing the cover member. This makes it possible to shorten the time required for maintenance work on belt units such as intermediate transfer units, compared to a configuration in which a tension roller unit such as the tension applying mechanism 160 can be removed from the belt unit by removing a cover member such as the inner cover 90.

[0110] (Aspect 9) In embodiment 8, a fastening portion such as a screw 89 for fastening a tension roller unit such as a tension applying mechanism 160 to a belt unit such as an intermediate transfer unit is provided on the downstream side panel, and an opening / closing member such as a transfer small door 70 is configured to be rotatable so as to be able to cover the fastening portion or expose it. According to this, the tension roller unit such as the tension applying mechanism 160 can be removed without removing the cover member such as the inner cover 90. [Explanation of symbols]

[0111] 7: Intermediate transfer unit 8: Intermediate transfer belt 9C: Primary transfer roller 9K: Primary transfer roller 9M: Primary transfer roller 9Y: Primary transfer roller 10: Driven roller 11: Drive roller 12: Secondary transfer opposing roller 13: Cleaning facing roller 14: Cleaning facing roller 15: Cleaning facing roller 16: Tension roller 17: Application brush facing roller 18: Secondary transfer roller 60: Printer 60a: Opening 61a: Front door 61b: Front door 66: Front side plate 66a: Screw hole 70: Small door with transcription 70a: opening 72: Pressing arm 75: Locking member 75b: Operation section 80: Frame housing 81: Slide rail 82: Previous frame 82a: Locating pin 82b: Locating pin 83: Rear frame 84: Stay member 85: Horizontal frame 86a: Drive motor 86b: Drive motor 87: Cable 89: Screw 90: Inner cover 91: Recess 92: Screw guide hole 100: Belt cleaning device 104: Guide groove 110: Cleaning lock lever 120a: Front plate 120b: Front plate 122: Positioning hole 123: Positioning hole 124: Handle 125: Screw 160: Tensioning mechanism 161: Base member 161a: Engagement protrusion 161b: Spring holder 162: Positioning surface 162a: Positioning hole 162b: Positioning hole 162c: Screw through hole 163: Holder holding plate 163a: Holder support shaft 165: First guide part 166: Second guide part 167:Holder holding surface part 167a: Holder support shaft 167b: Locating pin 167c: Locating pin 168:Through shaft 169: Screw 169a: Swing shaft 169b: Swing shaft 170a: First pressure mechanism 170b: second pressure mechanism 171: Coil spring 172: Pressing arm 172a: Spring retaining protrusion 172b: Retaining hole 172c: Pressing part 172d: Engagement recess 180: Pressure release lever 180a: Through hole 181: Anti-slip material 181a: Engagement groove 190: Roller holder 190a: Roller support hole 190b: Support hole 190c: Pressed part 200: Lubricant application device [Prior art documents] [Patent documents]

[0112] [Patent Document 1] JP 2021-113867 A

Claims

1. a tension roller that contacts the front surface of the belt member to apply tension to the belt member; a first pressure means for pressing an axial end of the tension roller toward the belt member; a second pressure means for pressing the other axial end of the tension roller toward the belt member, a tension roller unit comprising: a pressure release means for simultaneously releasing the pressure applied by the first pressure means and the second pressure means;

2. 2. The tension roller unit according to claim 1, the first pressure means and the second pressure means each have a pressing arm that is pivotably held and presses a holding member that holds an axial end of the tension roller, A tension roller unit, characterized in that the pressing arm of the first pressure means and the pressing arm of the second pressure means are arranged side by side in the axial direction.

3. 3. The tension roller unit according to claim 2, the pressure release means simultaneously presses the axial center end of the pressing arm of the first pressing means and the axial center end of the pressing arm of the second pressing means to swing each pressing arm in a direction opposite to the swing direction in which the pressing arm presses the holding member, thereby simultaneously releasing the pressure of the first pressing means and the second pressing means.

4. 4. The tension roller unit according to claim 3, A tension roller unit comprising a gripping portion that can be gripped by an operator while pressing the pressure releasing means when removing the tension roller unit from a belt unit including the belt member.

5. 2. The tension roller unit according to claim 1, a tension roller unit including a guide portion for guiding attachment and detachment of a detachable unit configured to be detachable from a belt unit including the belt member.

6. A belt unit including a belt member and a tension roller unit that applies tension to the belt member by a tension roller, 2. A belt unit comprising the tension roller unit according to claim 1 as said tension roller unit.

7. In an image forming apparatus having a belt unit, 7. An image forming apparatus comprising the belt unit according to claim 6 as said belt unit.

8. 8. The image forming apparatus according to claim 7, the belt unit includes a housing that supports a tension roller that stretches the belt member and the tension roller unit; the belt unit is configured to be removable from a main body of the image forming apparatus, the belt unit has a cover member that covers a downstream side plate of the housing perpendicular to a pull-out direction of the belt unit, the cover member being located downstream of the pull-out direction of the belt unit; The image forming apparatus is characterized in that the tension roller unit is detachable from the belt unit without removing the cover member.

9. 9. The image forming apparatus according to claim 8, a fastening portion for fastening the tension roller unit to the belt unit is provided on a downstream side plate, An image forming apparatus comprising: an opening / closing member that is rotatably configured to cover the fastening portion and to expose the fastening portion.

Images