JP2012194472A - Belt tension unit and image formation device with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a belt tension unit which achieves space saving and facilitates replacement work without causing complication of the configuration.SOLUTION: A belt tension unit 500 is provided in an image formation device body 100 and includes a tension member 501 that abuts on a belt surface 10a of an intermediate transfer belt 10 stretched between a plurality of rollers 14, 15, 16 and rotatively driven, and pressurization means 502 that pressurizes the tension member 501 toward the belt surface 10a. The belt tension unit 500 does not have depressurization means for releasing the pressurized state of the intermediate transfer belt 10 by the tension member 502 and the belt tension unit 500 is detachable from the image formation device body 100 or a belt unit 12 having the intermediate transfer belt 10 at the time of device driving stop.

Description

  The present invention relates to a belt tension unit and an image forming apparatus such as a copying machine, a printer, a facsimile, and a multifunction machine having a plurality of functions thereof.

Some image forming apparatuses using an electrophotographic system use a belt-like image carrier. In such an image forming apparatus using a belt-like image carrier, the belt-like image carrier is stretched and rotated by a plurality of rollers. However, if the belt-like image carrier is waved, good image formation is achieved. Therefore, an appropriate tension is applied to the belt-shaped image carrier using a belt tension unit.
The belt tension unit includes a tension roller serving as a tension member, and a pressurizing unit that presses the tension roller against the belt-shaped image carrier, and image formation is performed with tension applied during an image forming operation. However, when the tension is always applied, the load on the tension roller and the belt-like image carrier is large, so that the tension is weakened when a non-image is formed or when the belt-like image carrier is replaced. In particular, when removing the belt-shaped image carrier as a consumable from a plurality of rollers, the tension on the belt is weakened more than at the time of non-image formation and the belt is removed and replaced.
For example, in Patent Document 1, a belt tension unit is integrally provided with a pressure-reducing means for reducing the tension for belt removal, and in Patent Document 2 in which a belt-shaped image carrier is used as an intermediate transfer body, a belt-shaped image carrier and And an intermediate transfer unit including a plurality of rollers that support the intermediate transfer body, and the tension is weakened by lifting the intermediate transfer unit.

If the belt tension unit that applies tension to the belt-like image carrier is provided with a pressure-removing means for removing and attaching the belt as in Patent Document 1, the unit configuration becomes complicated, the number of parts increases, and the occupied space increases. End up. When the intermediate transfer unit is lifted as in Patent Document 2, it is difficult to replace the belt-shaped image carrier.
In addition, since an image forming apparatus using an electrophotographic method is required to be compact to reduce the size of the image forming apparatus, the size of functional parts and functional units used in the image forming apparatus is reduced, and the number of parts is reduced. There is a demand for reducing costs.
SUMMARY OF THE INVENTION An object of the present invention is to provide a belt tension unit and an image forming apparatus that are space-saving and can be easily replaced without complicating the configuration.

A belt tension unit according to the present invention is provided in a main body of an image forming apparatus, a tension member that abuts on an image carrying surface of a belt-like image carrier that is stretched and rotated by a plurality of rollers, and a tension member Pressurizing means for pressurizing the belt-shaped image carrier toward the image carrying surface, and without the depressurizing means for releasing the pressurization state of the belt-like image carrier by the tension member, The belt unit having the belt-shaped image carrier is detachable when the apparatus is stopped.
In the belt tension unit according to the present invention, the tension member extends in the width direction of the belt-like image carrier, and the pressurizing means is independently arranged in the width direction of the belt-like image carrier. It is said.
A belt tension unit according to the present invention includes a pair of arm members that support both ends of a tension member at one end thereof, a tension unit frame that rotatably supports each arm member, the other end of the arm member, and a tension unit. Both ends of the belt-like image carrier are attached to the frame, the pressure member pressurizes the tension member toward the belt-like image carrier, and the belt-like image carrier is located in a region surrounded by the pair of arm members and the tension unit frame. It has a guide member that extends in the width direction, reinforces the tension unit frame, and supports the movable body so as to be movable in the width direction of the belt-like image carrier.
The belt tension unit according to the present invention is supported by the front and back frames of the main body of the image forming apparatus included in the belt unit, and one end of the back side frame is swingably supported. It is characterized by being.
An image forming apparatus according to the present invention includes a belt unit having a belt-like image carrier that is stretched and rotated by a plurality of rollers, a tension member that abuts on an image carrying surface of the belt-like image carrier, and a tension member A belt tension unit including a pressurizing unit that pressurizes the belt-shaped image carrier toward the image carrying surface of the belt-like image carrier, and the belt tension unit includes the belt tension unit according to the present invention.

  According to the present invention, the belt-like image carrier is not provided with a depressurizing means for releasing the pressure applied by the tension member, and the belt is provided when the apparatus is stopped with respect to the image forming apparatus main body or the belt unit having the belt-like image carrier. Since the tension unit can be attached and detached, the replacement work is facilitated in a space-saving manner without complicating the configuration.

1 is a schematic configuration diagram showing an embodiment of an image forming apparatus according to the present invention. The figure which shows typically one form of a belt unit and a decompression means. Explanatory drawing which shows typically the movement operation from the contact state of a belt unit to a 1st separation state. Explanatory drawing which shows typically the movement operation from the 1st separation state of a belt unit to a 2nd separation state. It is a figure which shows typically the decompression means of the belt unit which concerns on other embodiment, (a) is a contact state, (b) shows a 1st separation state, (c) shows a 2nd separation state, respectively. The perspective view which shows the structure of the flame | frame with which a belt unit is provided. The enlarged view which looked at schematic structure of the belt tension unit and the cleaning unit concerning the present invention from the near side of the apparatus. The perspective view which shows the structure of a cleaning unit. The perspective view which looked at the composition of the belt tension unit from the slanting upper part. The perspective view which looked at the structure of the belt tension unit from the intermediate transfer belt side. It is a figure which shows the support state of a cleaning unit and a belt tension unit, (a) is the support state by a near frame, (b) is an enlarged view which shows the support state by a back frame. The figure which shows typically the contact state by a depressurization means, and the tension | tensile_strength provision state by a tension member. The figure which shows typically the 2nd separation state of a belt unit. The perspective view for demonstrating attachment / detachment operation of the belt tension unit with respect to a belt unit. The perspective view for demonstrating the state which mounted | wore the belt unit with respect to the belt tension unit. The perspective view for demonstrating the state in the middle of pushing the belt unit into the back | inner side with respect to the belt tension unit. The perspective view for demonstrating the state which pushed in the belt unit to the back | inner side with respect to the belt tension unit, and was completed. FIG. 5 is a schematic diagram for explaining an interference state between an inner cover provided in the image forming apparatus main body and an operation lever for manually operating the pressure release means. The schematic diagram explaining the non-interference state of an inner cover and an operation lever in the 2nd separation state. The schematic diagram explaining the state which a part of inner cover interferes with a belt tension unit and a belt unit. The schematic diagram explaining the removable state of the belt tension unit and a belt unit by removing the inner cover which is interfering.

  Embodiments of the present invention will be described below with reference to the drawings. First, the overall configuration and operation of the image forming apparatus according to the present invention will be described, and then the configuration of the belt tension unit will be described.

  The image forming apparatus shown in FIG. 1 illustrates a tandem full-color copying machine. The copier includes a printer unit 100 serving as an image forming apparatus main body, a paper feeding unit 200 disposed below the printer unit 100, a scanner unit 300 disposed above the printer unit 100, and an upper part of the scanner unit 300. And an automatic document feeder (hereinafter referred to as “ADF”) 400. The image forming apparatus is not limited to a copying machine, but may be a printer, a facsimile machine, or a multifunction machine having a plurality of these functions.

  The printer unit 100 includes an endless belt-like intermediate transfer belt 10 as an intermediate transfer member at the center thereof. In this embodiment, the intermediate transfer belt 10 is a belt-like image carrier. The intermediate transfer belt 10 is formed of an elastic layer on the surface, and is wound around the driving roller 14, the driven roller 15, and the secondary transfer counter roller 16 in a posture in which the side view is an inverted triangular shape. It is stretched and is endlessly moved in the clockwise direction in the figure by the rotational drive of the drive roller 14. In order to form toner images of Y (yellow), M (magenta), C (cyan), and K (black) above the intermediate transfer belt 10 stretched between the driving roller 14 and the driven roller 15. The four image forming units 18Y, 18M, 18C, and 18K are arranged so as to be aligned along the belt moving direction.

  The image forming units 18Y, 18M, 18C, and 18K are drum-shaped photoreceptors 20Y, 20M, 20C, and 20K as latent image carriers, developing units 61Y, 61M, 61C, and 61K, and photoreceptor cleaning units 63Y and 63M. , 63C, 63K. The photoreceptors 20Y, 20M, 20C, and 20K are in contact with the belt surface 10a serving as an image carrying surface of the intermediate transfer belt 10 to form primary transfer nips for Y, M, C, and K, respectively, and drive not shown. By means, it is rotated in the counterclockwise direction in the figure. The developing units 61Y, 61M, 61C, and 61K are for developing the electrostatic latent images formed on the photoreceptors 20Y, 20M, 20C, and 20K with toners of Y, M, C, and K. The photoconductor cleaning units 63Y, 63M, 63C, and 63K are for cleaning the transfer residual toner adhering to the photoconductors 20Y, 20M, 20C, and 20K after passing through the primary transfer nip. In this copying machine, the tandem image forming unit 11 is configured by four image forming units 18Y, 18M, 18C, and 18K arranged in the belt moving direction.

  In the printer unit 100, an optical writing unit 21 is disposed above the tandem image forming unit 11. The optical writing unit 21 performs an optical writing process by optical scanning on the surfaces of the photoconductors 20Y, 20M, 20C, and 20K that are driven to rotate counterclockwise in the drawing to form an electrostatic latent image. Is. Prior to the optical writing process, the surfaces of the photoreceptors 20Y, 20M, 20C, and 20K are uniformly charged by charging means of the image forming units 18Y, 18M, 18C, and 18K, respectively.

  A belt unit 12 as an intermediate transfer unit including the intermediate transfer belt 10 and the like has primary transfer rollers 62Y, 62M, 62C, and 62K inside the loop of the intermediate transfer belt 10. These primary transfer rollers 62Y, 62M, 62C, and 62K press the intermediate transfer belt 10 toward the photoreceptors 20Y, 20M, 20C, and 20K behind the primary transfer nips for Y, M, C, and K. Yes.

  A secondary transfer roller 23 serving as a secondary transfer member is disposed below the intermediate transfer belt 10. The secondary transfer roller 23 is in contact with a portion of the intermediate transfer belt 10 that is wound around the secondary transfer counter roller 16 from the belt surface side to form a secondary transfer nip. The secondary transfer counter roller 16 is connected to a voltage applying means composed of a high voltage power supply (not shown), and a transfer bias having the same polarity as the charging polarity of the toner constituting the toner image is applied to the secondary transfer counter roller 16. As a result, a transfer electric field is formed between the grounded secondary transfer roller 23. As a result, the unfixed toner image carried on the intermediate transfer belt 10 is collectively secondary to a sheet-like recording medium P (hereinafter referred to as “recording sheet P”) fed at a predetermined timing in the secondary transfer nip. Transcribed.

  The recording sheet P on which the unfixed toner image has been transferred moves from the secondary transfer roller 23 to the conveyance belt 29 and is conveyed to the fixing device 25 while being attracted to the conveyance belt 29, and heat and pressure are applied by the fixing device 25. The toner image is fixed. The recording paper that has passed through the fixing device 25 is discharged to a paper discharge tray 57 by a discharge roller 56 and stacked.

  The scanner unit 300 reads image information of a document placed on the contact glass 32 by the reading sensor 36 and transmits the read image information to a control unit (not shown) of the printer unit 100. Based on the image information received from the scanner unit 300, the control unit controls a light source such as a laser diode or an LED in the optical writing unit 21 of the printer unit 100, and laser writing light for Y, M, C, K. And the photoconductors 20Y, 20M, 20C, and 20K are optically scanned. By this optical scanning, electrostatic latent images are formed on the surfaces of the photoreceptors 20Y, 20M, 20C, and 20K, and the electrostatic latent images are developed into Y, M, C, and K toner images through a predetermined development process. .

  The paper feed unit 200 includes a paper feed roller 42 that feeds recording sheets P from paper feed cassettes 44 arranged in multiple stages in the paper bank 43, and a separation roller that separates the sent recording sheets P and guides them to a paper feed path 46. 45, a conveyance roller 47 for conveying the recording sheet P to the paper feed path 48 of the printer unit 100, and the like. In addition to the paper feed unit 200, manual paper feed is also possible, and the manual feed tray 51 for manual feed and the recording sheet P on the manual feed tray 51 toward the manual feed path 53 one by one. A separation roller 52 for separation is also provided. In the printer unit 100, the manual paper feed path 53 joins the paper feed path 48.

  Near the end of the paper feed path 48, a registration roller pair 49 is disposed. The registration roller pair 49 sandwiches the recording sheet P conveyed in the paper feed path 48 between the rollers, and then feeds it toward the secondary transfer nip at a predetermined timing.

  In the copying machine according to the present embodiment, when copying a color image, an original is set on the original platen 30 of the ADF 400, or the ADF 400 is opened and an original is set on the contact glass 32 of the scanner unit 300. Hold the document by closing it. Then, a start switch (not shown) is pressed. Then, when the document is set on the ADF 400, the document is conveyed onto the contact glass 32. Thereafter, the scanner unit 300 starts driving, and the first traveling body 33 and the second traveling body 34 start traveling along the document surface. Then, the light emitted from the light source by the first traveling body 33 is emitted on the original surface, and the obtained reflected light is folded and directed toward the second traveling body 34. The folded light is further folded by the mirror of the second traveling body 34 and then incident on the reading sensor 36 through the imaging lens 35. As a result, the document content is read.

  When the printer unit 100 receives image information from the scanner unit 300, the printer unit 100 feeds a recording sheet having a size corresponding to the image information to the paper feed path 48. Along with this, the drive roller 14 is rotationally driven by a drive motor (not shown) to move the intermediate transfer belt 10 endlessly in the clockwise direction in the drawing. At the same time, after the rotational driving of the photoconductors 20Y, 20M, 20C, and 20K of the image forming units 18Y, 18M, 18C, and 18K is started, charging processing, optical writing processing, and development processing are performed on the photoconductors 20Y, 20M, 20C, and 20K. And so on. The Y, M, C, and K toner images formed on the surfaces of the photoreceptors 20Y, 20M, 20C, and 20K by these processes are sequentially superimposed on the primary transfer nips for Y, M, C, and K. Primary transfer is performed on the belt surface 4a of the intermediate transfer belt 10 to form a four-color superimposed toner image.

  In the paper supply unit 200, one of the paper supply rollers 42 is selectively rotated according to the recording sheet size, and the recording sheet P is sent out from one of the plurality of paper supply cassettes 44. The fed recording sheets P are separated one by one by the separation roller 45, introduced into the paper feed path 46, and then sent to the paper feed path 48 in the printer unit 100 via the conveyance roller 47. When the manual feed tray 51 is used, the paper feed roller of the tray is driven to rotate, and the recording sheet P on the tray is fed to the manual paper feed path 53 while being separated by the separation roller 52, and is near the end of the paper feed path 48. To. In the vicinity of the end of the paper feed path 48, the recording sheet P stops by abutting the leading edge against the registration roller pair 49. Thereafter, when the registration roller pair 49 is rotationally driven at a timing that can be synchronized with the four-color superimposed toner image on the intermediate transfer belt 10, the registration roller pair 49 is fed into the secondary transfer nip and is in close contact with the four-color superimposed toner image on the belt. . Then, secondary transfer is performed collectively on the recording sheet P due to the influence of nip pressure, secondary transfer bias, and the like.

  The recording sheet P on which the four-color superimposed toner image is secondarily transferred at the secondary transfer nip is sent into the fixing device 25 by the conveyance belt 29. When the fixing device 25 is sandwiched between the fixing nip between the pressure roller 27 and the fixing belt 26, the four-color superimposed toner image is fixed on the surface by pressure or heat treatment. The recording sheet P on which the color image is formed in this manner is stacked on a discharge tray 57 outside the apparatus via a discharge roller pair 56.

  In the case of double-sided copying in which an image is also formed on the other side of the recording sheet P, the recording sheet P is discharged from the fixing device 25 and then sent to the sheet reversing device 57 by the path switching by the switching claw 55. It is done. Then, after being turned upside down, it is returned to the registration roller pair 49 again, and then goes through the secondary transfer nip and the fixing device 25 again.

Next, the configuration of the belt unit 12 will be described.
FIG. 2 is an enlarged view of the belt unit 12. The belt unit 12 includes a primary transfer roller 62K as a transfer member that transfers a toner image on the photoconductor 20K that forms a monochrome image onto the intermediate transfer belt 10, and a plurality of photoconductors 20Y that form color images. Primary transfer rollers 62Y, 62M, and 62C are provided as a plurality of transfer members that transfer toner images on 20M and 20C onto the intermediate transfer belt 10. The belt unit 12 includes a position adjusting unit 70 that controls contact / separation between the primary transfer roller 62K and the photosensitive member 20K, and contacts between the primary transfer rollers 62Y, 62M, and 62C and the photosensitive members 20Y, 20M, and 20C. A position adjusting means 71 for controlling the separated state is provided. In this embodiment, the position adjusting means 70 and 71 function as a pressure releasing means for releasing the tension applied to the intermediate transfer belt 10.

  The primary transfer rollers 62K, 62Y, 62M, and 62C, the driving roller 14, the driven roller 15, the secondary transfer counter roller 16, and the position adjusting means 70 and 71 shown in FIG. 1 are arranged on a pair of frames 120 and 121 shown in FIG. It is supported. The metal frames 120 and 121 are in the width direction of the recording sheet P, are arranged at a distance from the front side and the back side of the recording printer unit 100, and are integrated by a plurality of connecting members. A cleaning unit 17 and a belt tension unit 500, which will be described later, are detachably supported by these frames 120 and 121. The frame 120 also functions as a mounting portion for inner covers 601, 602, and 603 to be mounted on the printer unit 100 described later.

  The belt unit 12 is detachable from the printer unit 100 after a tension releasing operation in which the respective photoconductors 20 and the respective first transfer rollers are positioned at a second separation position, which will be described later, by the position adjusting means 70 and 71. .

  In this embodiment, the belt unit 12, the cleaning unit 17, and the belt tension unit 500 are attached / detached from the front side of the printer unit 100, that is, from the frame 120 side. In this embodiment, the mounting direction is a direction from the front side of the printer unit 100 to the back side unless otherwise specified, and the separation direction is the back side from the back side of the printer unit 100 unless there is a special notice. It is the direction toward.

  The position adjusting means 70 includes a support member 81, a first cam 72, and a second cam 74. The support member 81 has a flat or rectangular frame shape, and rotatably supports the primary transfer roller 62K and the downstream backup roller 75. The support member 81 is rotatable in a direction in which it contacts and separates from the inner surface of the intermediate transfer belt 10 around a rotation fulcrum 82 located inside the belt at a position upstream of the primary transfer roller 62K in the belt traveling direction. Yes.

  The position adjusting means 70 has a configuration in which the primary transfer roller 62K and the downstream backup roller 75 are disposed between the driving roller 14 and the driven roller 15 that are fixed with respect to the intermediate transfer belt 10. Position adjustment of the next transfer roller 62K and the downstream backup roller 75 can be easily performed. In the present embodiment, the support member 81 rotates about the rotation fulcrum 82, whereby the primary transfer roller 62K and the downstream backup roller 75 move in conjunction with each other, and the position of the intermediate transfer belt 10 with respect to the photoreceptor 20K is changed. It can be adjusted. The downstream backup roller 75 is disposed downstream of the primary transfer roller 62K with respect to the traveling direction of the intermediate transfer belt 10 with respect to the position of the intermediate transfer belt 10, and the nip amount of the primary transfer nip is the same for each color. It functions as a roller.

  As shown in FIG. 2, the first cam 72 and the second cam 74 are provided below the support member K81 in the drawing. The state shown in FIG. 2 shows a contact state in which the first cam K72 supports the support member 81 at the top dead center, and the intermediate transfer belt 10 contacts the photoconductor 20K. By rotating the first cam 72 and the second cam 74, the support member 81 rotates about the rotation fulcrum 82, and the transfer roller 62K and the downstream backup roller 75 can be moved in conjunction therewith. it can. Then, by controlling the rotation stop positions of the first cam K72 and the second cam K74, respectively, two-stage rotation operation (two operations from the contact state to the first separation state and from the first separation state to the second separation state) )It can be performed. The intermediate transfer belt 10 is separated from the photoconductor 20K by the first stage rotation operation to perform the first separation state, and further the second separation state is performed by the second stage rotation operation. The operation of decreasing the belt tension by decreasing the winding amount of 75 can be sequentially performed. The first cam 72 and the second cam K74 are arranged side by side, but the second cam 74 is located below the first cam 72 in the vertical direction, and the first cam 72 is bottom dead. It arrange | positions so that the position of the top dead center of the 2nd cam 74 may become above rather than the position of a point.

  By arranging in this way, the support member 81 is at the top dead center of the first cam 72 in the contact state, the top dead center of the second cam 74 in the first separated state, and the first cam in the second separated state. 72 or the second cam 74 is supported at the bottom dead center.

  In the following description, the positions of the intermediate transfer belt, the transfer roller, and the like in the contact state, the first separation state, and the second separation state are referred to as “contact position”, “first separation position”, and “second separation position”, respectively. " The state of the apparatus in which the intermediate transfer belt 10 and the primary transfer roller occupy the second separation position is when the apparatus is stopped.

  FIG. 3 shows a first separated state in which the intermediate transfer belt 10 is separated from each photoconductor 20 (Y, M, C, K) by moving each first transfer roller 62 (Y, M, C, K). It is an enlarged view of the belt unit 12 shown. The transfer roller 62K disposed at a position facing the photoconductor 20K that forms a monochrome image will be described. In order to shift the first transfer roller 62K from the contact position shown in FIG. 2 to the first separation position shown in FIG. 3, the first transfer roller 62K is located at the top dead center position by the driving force of a driving means such as a motor or a solenoid (not shown). The cam K72 is rotated 180 degrees and stopped at the bottom dead center position. Then, with the rotation of the first cam K72, the support member K81 rotates about the rotation fulcrum 82 together with the transfer roller 62K and the downstream backup roller 75 in the clockwise direction in the drawing due to the belt tension and its own weight. The support member K81 is positioned in contact with the top dead center of the second cam K74 before the first cam K72 reaches bottom dead center.

  4 further moves the first transfer rollers 62 (Y, M, C, K) to move the intermediate transfer belt 10 from the photoreceptors 20 (Y, M, C, K) to the first separation shown in FIG. It is an enlarged view of the belt unit 12 which shows the 2nd separation state spaced apart so that it may separate further from a state. The transfer roller 62K disposed at a position facing the photoconductor 20K that forms a monochrome image will be described. In order to shift the first transfer roller 62K from the first separated position shown in FIG. 3 to the second separated position shown in FIG. 4, the second cam 74 is moved 180 degrees by manually operating an operation lever 700 described later. Rotate to stop at bottom dead center. As the second cam 74 rotates, the support member 81 further rotates in the clockwise direction in the drawing together with the transfer roller 62K and the downstream backup roller 75 around the rotation fulcrum 82 due to the belt tension and its own weight. The support member K81 is positioned at the bottom dead center position of the first cam 72. In the second separation position, the intermediate transfer belt 10 is separated from the photoconductor 20K than in the first separation position. The support member 81 is supported not only at the bottom dead center of the first cam 72 but also at the bottom dead center of the second cam 74.

  By rotating the first cam 72 in this way, the first transfer roller 62K supported by the support member 81 moves, and the position control between the contact position and the first separation position is possible. By rotating the position, position control between the first separation position and the second separation position is possible. Further, the downstream backup roller 75 also moves with the support member 81 and is position-controlled at the contact position, the first separation position, and the second separation position. As a result of such position control, the tension applied to the intermediate transfer belt 10 can be increased or decreased.

  As shown in FIG. 2, the color position adjusting means 71 includes a support member 83, a first cam 76, and a second cam 77. The support member 83 has a flat plate shape or a rectangular frame shape, and rotatably supports the first transfer rollers 62Y, 62M, and 62C and the upstream backup roller 78. The support member 83 is rotatable in a direction in which it contacts and separates from the inner surface of the intermediate transfer belt 10 around a rotation fulcrum 84 located inside the belt at a position downstream of the first transfer roller 62Y in the belt traveling direction. Yes.

  The position adjusting means 71 is supported by a configuration in which the first transfer rollers 62Y, 62M, and 62C and the upstream backup roller 78 are disposed between the driving roller 14 and the driven roller 15 that are fixed in position relative to the intermediate transfer belt 10. The member 83 can easily adjust the position of the first transfer rollers 62Y, 62M, and 62C and the upstream backup roller 78. In the present embodiment, the support member 83 rotates about the rotation fulcrum 84, whereby the first transfer port rollers 62Y, 62M, 62C and the upstream backup roller 78 move in conjunction with each other, and the photoconductors 20Y, 20M. The position of the intermediate transfer belt 10 with respect to 20C can be adjusted. The upstream backup roller 78 is provided upstream of the first transfer roller 62C in the traveling direction of the intermediate transfer belt 10, and functions as a roller for making the nip amount of the primary transfer nip the same for each color. To do.

  The first cam 76 and the second cam 77 are provided below the support member 83 in the drawing. The state shown in FIG. 2 shows a contact state in which the first cam 76 supports the support member 83 at the top dead center, and the intermediate transfer belt 10 is brought into contact with the photoreceptors 20Y, 20M, and 20C. By rotating the first cam 76 and the second cam 77, the support member 83 rotates about the rotation fulcrum 84, and in conjunction with this, the primary transfer rollers 62Y, 62M, 62C and the upstream backup roller 78 are rotated. And can be moved. Then, by controlling the rotation stop positions of the first cam 76 and the second cam 77, respectively, a two-step rotation operation (two operations from the contact state to the first separation state and from the first separation state to the second separation state) )It can be performed. The intermediate transfer belt 10 is moved away from the photoconductors 20Y, 20M, and 20C by the first rotation operation, and the winding amount of the upstream backup roller 78 is reduced by the second rotation operation. The operation of decreasing the belt tension can be sequentially performed.

  The first cam 76 and the second cam 77 are arranged side by side, but the second cam 77 is located below the first cam 76 in the vertical direction, and the first cam 76 is at the bottom dead center. The second cam 77 is disposed such that the position of the top dead center is higher than the position. With this arrangement, the support member 83 is at the top dead center of the first cam 76 in the contact state, the top dead center of the second cam 77 in the first separated state, and the first cam in the second separated state. 76 or the second cam 77 is supported at the bottom dead center.

  In order to cause the primary transfer rollers 62Y, 62M, and 62C to transition from the contact position shown in FIG. 2 to the first separated position shown in FIG. 3, the position of the top dead center is driven by the driving force of a driving means such as a motor or a solenoid (not shown). The first cam 76 is rotated 180 degrees and stopped at the bottom dead center position. Then, as the first cam 76 rotates, the support member 83 rotates in the counterclockwise direction in the drawing together with the transfer rollers 62Y, 62M, 62C and the upstream backup roller 78 around the rotation fulcrum 84 due to the belt tension and its own weight. To do. The support member 83 is positioned in contact with the top dead center of the second cam 77 before the first cam 76 reaches bottom dead center.

  In order to shift the primary transfer rollers 62Y, 62M, and 62C from the first separated position shown in FIG. 3 to the second separated position shown in FIG. 4, the second cam is operated by manually operating an operation lever 700 described later. 77 is rotated 180 degrees and stopped at the bottom dead center position. As the second cam 77 rotates, the support member 83 further rotates in the counterclockwise direction in the drawing together with the transfer rollers 62Y, 62M, 62C and the upstream backup roller 78 around the rotation fulcrum 84 due to the belt tension and its own weight. . The support member 83 is positioned at the bottom dead center position of the first cam 76. In the second separation position, the intermediate transfer belt 10 is located farther from the photoconductors 20Y, 20M, and 20C than in the first separation position. The support member 83 is supported not only at the bottom dead center of the first cam 76 but also at the bottom dead center of the second cam 77.

  By rotating the first cam 76 in this way, the first transfer rollers 62Y, 62M, and 62C supported by the support member 83 move, and position control between the contact position and the first separation position is possible. By rotating the second cam 77, position control between the first separation position and the second separation position is possible. Further, the upstream backup roller 78 also moves with the support member 83, and is position-controlled at the contact position, the first separation position, and the second separation position. As a result of such position control, the tension applied to the intermediate transfer belt 10 can be increased or decreased.

  In the present embodiment, in a contact state, the two backup rollers 75 and 78, the black first transfer roller 62K, and the plurality of color transfer rollers 62C, 62M, and 62Y are arranged on the intermediate transfer belt 10 on substantially the same plane. It is in contact. Since there are two backup rollers 75 and 78, each of the photoconductors 20Y, 20M, 20C, and 20K and the first transfer rollers 62Y, 62M, 62C, and 62K are used for printing (full color printing). The transfer nip amount can be made the same. In particular, as shown in FIG. 2, the upstream backup roller 78 prevents the intermediate transfer belt 10 from inclining toward the driven roller 15 on the upstream side of the photoreceptor 20C, and the downstream backup roller 75 is connected to the photoreceptor 20K. The intermediate transfer belt 10 is prevented from inclining toward the drive roller 14 on the downstream side.

  In the present embodiment, the rotation fulcrum 82 and the rotation fulcrum 84 of the position adjusting means 70 and 71 are arranged between the black first transfer roller 62K and the color transfer rollers 62Y, 62M and 62C, respectively. Any one of the image forming portion (photosensitive member 20K, first transfer roller 62K) or the color image forming portion (photosensitive drums 20Y, 20M, 20C, first transfer rollers 62Y, 62M, 62C) is separated. Is also easy.

  Further, when the intermediate transfer belt 10 and each first transfer roller occupy the second separation position by the position adjusting means 70 and 71, the belt tension is the weakest state. When attaching / detaching 500, the attaching / detaching work can be easily performed.

  Since the contact state and the first separated state are at the time of printing and at the time of printing standby, it is possible to consider the normal usage mode of the copier (the case where printing and standby operations are repeated many times with the copier powered on). For example, it is preferable that the position is automatically adjusted by the driving means. On the other hand, the second separated state is when the image forming units 18Y, 18M, 18C, and 18K shown in FIG. 1 having the belt unit 12 and the respective photosensitive members are attached and detached, and mainly the intermediate transfer belt 10 and the like. It is assumed at the time of maintenance of the apparatus such as replacement of each photoconductor. Since the position adjustment operation in the second separated state is very infrequent compared to the position adjustment operation between the contact state and the first separated state, no drive means is provided in consideration of the manufacturing cost of the apparatus, and the operation lever Manual adjustment at 700 or the like is preferable.

  Regardless of the detachability of the belt unit 12 or the image forming units 18Y, 18M, 18C, and 18K, the first separation position is determined by the first transfer rollers 62Y, 62M, 62C, and 62K and the photoreceptors 20Y, 20M, 20C, and 20K. Since the position of the intermediate transfer belt 10 is set to be close and the travel path of the intermediate transfer belt 10 generated during the contact / separation operation between the intermediate transfer belt 10 and the photoconductors 20Y, 20M, 20C, and 20K is small, the belt tension varies. The intermediate transfer belt 10 is given a predetermined belt tension. For this reason, it is possible to prevent a deviation in the position control in the width direction of the intermediate transfer belt 10 and to prevent the belt from loosening or slipping while the intermediate transfer belt 10 is being driven.

  In the second separation position, the intermediate transfer belt 10 and the plurality of photoconductors 20Y, 20M, 20C, and 20K are largely separated regardless of the fact that the meandering control of the intermediate transfer belt 10 becomes unstable due to fluctuations in belt tension. Therefore, the belt unit 12 (particularly, the intermediate transfer belt 10, the drive roller 14 and the driven roller 15, and the secondary transfer counter roller 16) and the image forming units 18Y, 18M, 18C, and 18K are very detachable. Is good.

  In the configuration according to the present embodiment, the moving distances of the transfer rollers 62Y, 62M, 62C, and 62K, the downstream backup roller 75, and the upstream backup roller 78 are set to be small in the contact state and the first separated state. The downstream backup roller 75 and the upstream backup roller 78 have a smaller amount of winding around the intermediate transfer belt 10 and less force to receive belt tension than the drive roller 14 and the driven roller 15. Therefore, the load applied to the driving components (first cam 72 and first cam 76) that make contact and separation is small. In addition, the belt tension variation can be set small between the contact state and the first separated state.

  The distance that the transfer rollers 62Y, 62M, 62C, and 62K, the downstream backup roller 75, and the upstream backup roller 78 move is set large in the first separation state and the second separation state. In the second separation state, it is not necessary to secure belt tension, and the distance between each photoconductor and the intermediate transfer belt 10 is set to a position that greatly separates the photoconductors 20Y, 20M, 20C, and 20K and the intermediate transfer belt. Excellent detachability with 10. As shown in FIG. 4, in the configuration according to the present embodiment, the tension of the intermediate transfer belt 10 is greatly reduced by reducing the belt winding amount around the backup rollers 75 and 78 in the second separated state. Yes. Accordingly, the belt unit 12 including the intermediate transfer belt 10, each primary transfer roller, the drive roller 14, the driven roller 15, the secondary transfer counter roller 16, the backup rollers 75 and 78, and the like is used as the photoreceptors 20Y, 20M, 20C, and 20K. After being separated from the roller, it is possible to easily remove the intermediate transfer belt 10 from each roller.

  FIG. 5 is a view schematically showing a separated state of the belt unit (intermediate transfer unit) 12 while showing another form of the position adjusting means functioning as the pressure releasing means. 5A shows a contact state, FIG. 5B shows a first separated state, and FIG. 5C shows a second separated state. The position adjusting means 70A as a detaching means according to this embodiment differs from the previous position adjusting means 70 in that the auxiliary roller 91 is provided at a position upstream of the first transfer roller 62K in the traveling direction of the intermediate transfer belt 10. The auxiliary roller 91 is rotatably supported by a support member 81 at a position near the rotation fulcrum 82 between the rotation fulcrum 82 and the primary transfer roller 62K. In the contact state shown in FIG. 5A, the auxiliary roller 91 and the transfer roller 62K are in contact with the intermediate transfer belt 10 without being wound. On the other hand, in each separated state shown in FIGS. 5B and 5C, the auxiliary roller 91 is wound around the intermediate transfer belt 10.

  In these states, since the auxiliary roller 91 supports the intermediate transfer belt 10 just above the rotation fulcrum 82, the rotation fulcrum 82 and the intermediate transfer belt 10 do not come into contact with each other. By providing the auxiliary roller 91 in this way, the degree of freedom of arrangement of the rotation fulcrum 82 and each roller is increased. Further, the first transfer roller 62K is positioned between the auxiliary roller 91 and the downstream backup roller 75, and these are aligned in a straight line as shown in FIGS. 5 (a) to 5 (c). The first transfer roller 62K does not wind around the intermediate transfer belt 10 because it moves in conjunction with the relationship. Since the load due to the winding of the intermediate transfer belt 10 is not applied to the first transfer roller 62K that affects the transfer accuracy, distortion and deformation of the support shaft of the first transfer roller 62K can be prevented.

  Here, an example of setting the separation distance between the photoconductor 20K and the first transfer roller 62K will be described with reference to FIGS. 5 (a) to 5 (c). The distance from the rotation fulcrum 82 to the downstream backup roller 75 is, for example, 200 mm, the distance from the rotation fulcrum 82 to the transfer roller 62K is, for example, 130 mm, and the contact state is set as shown in FIG. From this contact state, the first cam K72 is rotated 180 degrees to move the contact position between the support member 81 and the first cam 72 substantially vertically downward, and the support member 81 contacts the top dead center of the second cam 74. Let This state is the first separated state as shown in FIG. At this time, the separation distance Dl between the photoconductor 20K and the first transfer roller 62K is, for example, 4 mm.

  Further, the second cam 74 is rotated 180 degrees from the first separated state to move the contact position between the support member 81 and the second cam 74 substantially vertically downward, and the support member K81 is brought to the bottom dead center of the first cam 72. Make contact. As shown in FIG. 5C, this state is a second separation state in which the separation amount is larger than that in the first separation state. At this time, the separation distance D2 between the photoconductor 20K and the first transfer roller 62K is, for example, 17 mm.

  The amount of winding of the downstream backup roller 75 around the intermediate transfer belt 10 and the belt tension of the intermediate transfer belt 10 are greatest in the contact state, and then increase in the order of the first separation state and the second separation state. In the first separation state, the separation distance D1 is set to be as small as 4 mm, for example, and the difference in the amount of winding of the downstream backup roller 75 and the belt tension when compared with the contact state is small. On the other hand, in the second separation state, the separation distance D2 is set to be as large as 17 mm, for example, and the amount of winding of the backup roller 75 around the belt is small, and the belt tension is also small.

  In this embodiment, the configuration in which the auxiliary roller 91 is provided on the black support member 81 has been described. However, a similar auxiliary roller may be provided on the color-side support member 83.

  Next, the cleaning unit 17 and the belt tension unit 500 will be described. In the printer unit 100, a cleaning unit 17 and a belt tension unit 500 are arranged. After passing through the secondary transfer nip, the cleaning unit 17 is a position before entering the primary transfer nip for Y, which is the most upstream among the four colors, that is, the driven roller 15 and the secondary roller. It is arranged between the transfer opposing rollers 16. The cleaning unit 17 cleans the transfer residual toner and paper dust adhering to the belt surface 10a after the secondary transfer.

  As shown in FIGS. 7 and 8, the cleaning unit 17 includes a brush roller 101 as a cleaning member, a cleaning blade 103 as a cleaning member, from the upstream side to the downstream side in the moving direction of the belt surface 10a of the intermediate transfer belt 10. The application brush roller 105 as the lubricant application member and the leveling blade 107 as the lubricant leveling member are arranged in the order supported by the unit frame 109. The brush roller 101, the cleaning blade 103, the application brush roller 105, and the leveling blade 107 are disposed so as to contact the belt surface 10a.

  The brush roller 101 is rotatably supported by the unit frame 109, and has a function of removing paper dust and transfer residual toner adhered to the belt surface 10a by rotating. The brush roller 101 may be rotated with the intermediate transfer belt 10, but in this embodiment, the brush roller 101 is driven to rotate by belt driving. Here, PET resin is used as the material of the brush hair.

  By disposing the brush roller 101 upstream of the cleaning blade 103 in the belt moving direction, it is possible to remove the transfer residual toner simultaneously with the removal of paper dust, and the burden on the cleaning blade 103 is reduced. The effect of prolonging the service life can also be expected.

  The cleaning blade 103 made of a rubber plate material typified by polyurethane rubber is a known blade that scrapes off the paper dust and transfer residual toner adhering to the belt surface 10a as the intermediate transfer belt 10 moves.

  The application brush roller 105 is rotatably supported by the unit frame 109. The brush portion is in contact with the end surface of the solid lubricant 111 and the belt surface 10a, and is rotated by a driving unit (not shown). The solid lubricant 111 is scraped off and applied to the belt surface 10a to improve the smoothness of the belt surface. The leveling blade 107 is for uniformizing the thickness of the lubricant applied to the belt surface 10 a by the applying brush roller 105.

  A slide rail 113 is provided on the upper portion of the unit frame 109. The metal slide rail 113 has a C-shaped cross section, extends from the front side of the printer unit 100 toward the back side, and a unit frame by a fastening member such as a screw so that the opening 113a faces upward. 109 is fixed.

  The slide rail 113 accommodates a hat-shaped guide member 510 provided in the belt tension unit 500 shown in FIGS. 7 and 9 inside, and both ends of the opening 113a are hooked on the hat-shaped flanges 510a and 510b. It is slidably supported on the front side and the back side of the unit 100. That is, when the belt tension unit 500 is fixed, the cleaning unit 17 can be detachably moved with respect to the belt tension unit 500 in a narrow sense, and the belt tension unit 500 is supported by the frames 120 and 121 in a broad sense. The belt unit 12 is configured to be detachably movable.

  As shown in FIG. 8, mounting portions 160 and 161 for the frames 120 and 121 shown in FIG. 6 are formed on the side surface 109a located on the near side of the unit frame 109 and the side surface 109b located on the far side. The mounting portion 160 includes holes 160a and 160b formed in the side plate 109a with a space in the vertical direction when the cleaning unit 17 is mounted on the frame 120. The hole 160a is circular, and the hole 160b is a long hole that is long in the vertical direction. The mounting portion 161 is formed of pins 161a and 161b having a circular cross section that are formed so as to protrude from the side plate 109b toward the back side with an interval in the vertical direction. These pins 161 a and 161 b are arranged so as to be shifted from each other in the horizontal direction when the belt tension unit 500 is mounted on the frames 120 and 121. The side surface 109a is formed with a grip portion 114 that is gripped by an operator when the cleaning unit 17 is attached or detached.

  The belt tension unit 500 according to the present embodiment, as shown in FIGS. 7, 9, and 10, presses the tension roller 501 as a tension member in contact with the belt surface 10a and the tension roller 501 toward the belt surface 10a. Pressurizing means 502. In this embodiment, the position adjusting means 70 and 71 are attached to the belt unit 12, and the tension of the intermediate transfer belt 10 is weakened by the function of the position adjusting means 70 and 71, thereby functioning as the pressure releasing means. For this reason, the belt tension unit 500 is configured not to include a depressurizing unit that releases the pressure applied by the tension roller 501. The belt tension unit 500 can be attached to and detached from the belt unit 12 when the apparatus is stopped.

  The tension roller 501 extends in the width direction intersecting the belt moving direction of the intermediate transfer belt 10. In this embodiment, the width direction of the intermediate transfer belt 10 corresponds to the direction toward the front and back of the printer unit 100, and this direction is the attachment / detachment direction.

  The pressing unit 502 includes an arm member 505 that is rotatably supported on a tension unit frame 503 by a shaft 504, and a tension coil spring 506 as a pressing member that presses the tension roller 501 toward the belt surface 10a. Yes. The arm member 505 rotatably supports one end of the central shaft 501A of the tension roller 501 on its one end side 503a. One end 506 a of the tension coil spring 506 is attached to the other end 505 b of the arm member 505, and the other end 506 b is attached to the tension unit frame 503, and the arm member 505 pressurizes in a direction of rising about the shaft 504. ing. That is, the pressing unit 502 always urges the tension roller 501 in the pressing direction to the intermediate transfer belt 10.

  In the present embodiment, the pressure unit 502 having such a configuration is independently arranged in the width direction of the intermediate transfer belt 10, that is, in the direction in which the tension roller 501 extends.

  The metal guide member 510 extends in the width direction of the intermediate transfer belt 10 in a frame region surrounded by the pair of arm members 505 and 505 and the tension unit frame 506, and the side surfaces 503a and 503b of the tension unit frame 503. Are fixed to the tension unit frame 503 so as to connect the two. That is, the guide member 510 has a function of reinforcing the side surfaces 506a and 506b of the frame 503 on which the shaft 504 that rotatably supports the arm member 505 that supports the tension roller 501 to which a heavy load is applied, and a width in the attaching / detaching direction. It also has a function of supporting the cleaning unit 17 that becomes a movable body so as to be movable in the direction.

  As shown in FIGS. 9 and 10, mounting portions 511 and 512 for the frames 120 and 121 shown in FIG. 6 are formed on the side surface 503a located on the front side of the tension unit frame 503 and the side surface 503b located on the back side. Has been. The mounting portion 511 is formed with a gap in the horizontal direction when the belt tension unit 500 is mounted on the frame 120 in a grip portion 514 that is located on the outer side of the frame 120 by bending a part of the side surface 503a toward the front side. It consists of holes 511a and 511b. The hole 511a is circular, and the hole 511b is a long hole that is long in the horizontal direction. As shown in FIG. 9, the mounting portion 512 includes pins 512a and 512b having a circular cross section formed on the side plate 503b with a space in the vertical direction when the belt tension unit 500 is mounted on the frame 120.

  Positioning portions 150 and 151 for mounting the cleaning unit 17 and positioning portions 152 and 153 for mounting the belt tension unit 500 are formed on the frames 120 and 121 shown in FIG.

  The positioning portion 150 formed on the front frame 120 protrudes toward the front side of the frame and is inserted into the holes 160a and 160b of the mounting portion 160 of the cleaning unit 17 shown in FIG. 8 to support one side of the cleaning unit 17. It consists of pins 150a and 150b. The positioning portion 151 formed on the back frame 121 is configured by positioning holes 151 a and 151 b for inserting pins 161 a and 161 b of the mounting portion 161 of the cleaning unit 17 to support one side of the cleaning unit 17. The positioning hole 151a is circular, and the hole 151b is a long hole extending in the vertical direction.

  The positioning portion 152 formed on the front frame 120 protrudes toward the front side of the frame, and is inserted into the holes 511a and 511b of the mounting portion 511 of the belt tension unit 500 shown in FIG. It consists of pins 152a and 152b to support. The positioning portion 153 formed in the frame 121 is configured by positioning holes 153 a and 153 b that insert the pins 512 a and 512 b of the mounting portion 512 located on the back side of the belt tension unit 500 and support one side of the belt tension unit 500. ing. The positioning hole 153a is circular, and the positioning hole 153b is a long hole extending in the vertical direction.

  The positioning portion 152 formed on the frame 120 is located inside the intermediate transfer belt 10 when viewed from the front side, the positioning portion 153 formed on the frame 121 is located outside the intermediate transfer belt 10, and The belt tension unit 500 is configured to be a swing fulcrum when the belt tension unit 500 is attached / detached.

In the positioning portion 151, one positioning hole 151a serves as a main reference when the cleaning unit 17 is mounted on the frame 121, and the other positioning hole 151b serves as a sub-reference when the cleaning unit 17 is mounted.
In the positioning portion 153, one positioning hole 153a serves as a main reference when the belt tension unit 500 is mounted on the frame 121, and the other positioning hole 153b serves as a sub-reference when the belt tension unit is mounted.

  In order to attach the belt tension unit 500 to the frames 120 and 121, the pins 512 a and 512 b of the attachment portion 512 located on the back side are positioned on the positioning holes 153 a of the positioning portion 153 of the frame 121 as shown in FIG. 153b, and the pins 152a and 152b of the positioning portion 152 of the front frame 120 are inserted even into the holes 511a and 511b of the mounting portion 511 located on the front side as shown in FIG. As a result, it is attached to the frames 120 and 121.

  When the belt tension unit 500 is in the mounted state, the tension roller 501 is pressed against the belt surface 10 side of the intermediate transfer belt 10. At this time, the intermediate transfer belt 10 occupies the second separation position shown in FIG. 13 from the contact position shown in FIG. 12 by the position adjusting means 70 and 71 shown in FIGS. Since the tension is the weakest, the load applied to the tension roller 501 is small, and the operation of attaching the belt tension unit 500 can be easily performed manually.

  In order to remove the belt tension unit 500 from the mounted state, the grip portion 514 is pulled by the operation and the pins 152a and 152b are disengaged from the holes 511a and 511b of the mounting portion 511. This can be done by removing 512b from the positioning holes 153a and 153b. Even when such a belt tension unit 500 is detached from the copying machine, the operation of removing the belt tension unit 500 can be performed by placing the intermediate transfer belt 10 at the second separation position shown in FIG. Easy to do manually.

  Further, when the belt tension unit 500 is detached from the belt unit 12 in a state where the belt tension of the intermediate transfer belt 10 is greatly reduced in the second separated state by the position adjusting means 70 and 71, an opening space is formed below the belt unit 12. Therefore, the intermediate transfer belt 10 can be easily detached and replaced from the drive roller 14, the support roller 15, and the secondary transfer counter roller 16. That is, as shown in FIG. 13, since the belt tension of the intermediate transfer belt 10 is greatly lowered and relaxed in the second separated state by the position adjusting means 70 and 71 described above, the belt tension unit 500 is manually operated. Removal from the belt unit 12 can be easily performed.

  When the belt tension unit 500 is attached / detached, the lower positioning hole 153b formed in the frame 121 is a long hole extending in the vertical direction. Therefore, the belt 511b of the belt tension unit 500 is inserted into the positioning hole 153b. The tension unit 500 can be swung up and down as shown in FIG. That is, one end of the belt tension unit 500 is swingably supported by the frame 121.

  Next, in order to mount the cleaning unit 17 on the copying machine, the slide rail 113 of the cleaning unit 17 is attached to the guide member 510 of the belt tension unit 500 already supported by the frames 120 and 121 and mounted on the copying machine. Insert from the front as shown in Then, as shown in FIG. 16, the cleaning unit 17 is pushed from the near side toward the far side. Then, the cleaning unit 17 moves while being suspended from the belt tension unit 500 and is pushed to the mounting completion position shown in FIG.

  When the cleaning unit 17 occupies the mounting completion position shown in FIG. 17, the pins 161a and 161b of the cleaning unit 17 are inserted into the positioning holes 151a and 151b of the frame 121 as shown in FIG. The holes 160a and 160b of the mounting portion 160 are inserted into the positioning pins 152a and 152b of the frame 120 as shown in FIG. Therefore, the cleaning unit 17 is supported by the frames 120 and 121 from the state suspended from the belt tension unit 500. Then, by screwing the screw 165 into the frame 120 from the side plate 109a side, the cleaning unit 17 is fixed to the frame 120, and when the cleaning unit 17 is fixed, the movement of the belt tension unit 500 is also restricted and fixed. . That is, the screw 165 is provided as an attachment / detachment restricting member that restricts the belt tension unit 500 from being attached to and detached from the belt unit 12 in a state where the cleaning unit 17 is supported by the belt tension unit 500. The procedure can be regulated. This is because the belt tension unit 500 cannot be removed from the copying machine unless the screw 165 is removed and the cleaning unit 17 is detached, so that waste toner and the like in the cleaning unit 17 are prevented from being scattered when the belt tension unit 500 is attached and detached. And contamination of the device and the surrounding environment can be prevented.

  As described above, the belt tension unit 500 does not have the position adjusting means 70 and 71 serving as pressure releasing means for releasing the pressure applied to the intermediate transfer belt 10 by the tension roller 501 and is attached to and detached from the belt unit 12 when the apparatus is stopped. Since it is possible, the operation of releasing the tension is not required when the belt tension unit 500 is attached / detached, and the replacement work can be facilitated in a small space without complicating the configuration.

  Since the pressing means 502 for pressing the tension roller 501 toward the intermediate transfer belt 10 is arranged independently on the front side and the back side of the apparatus in the longitudinal direction of the tension roller 501, one pressing means is used. Compared with the case of pressurization, the tension deviation to the intermediate transfer belt 10 on the near side and the far side of the apparatus is reduced, and the belt tension is stabilized.

  In the belt tension unit 500 according to the present invention, a guide member 510 that slidably supports the cleaning means 17 for cleaning the intermediate transfer belt in a detachable direction is surrounded by a pair of arm members 505 and 505 and a tension unit frame 506. Since it is arranged in the frame area, the sliding function of the cleaning unit 17 can be accommodated within the projected area of the belt tension unit 500, which helps to save space.

  The belt tension unit 500 according to the present invention abuts the tension roller 501 from the belt surface 10a located outside the loop of the intermediate transfer belt 10 toward the inside of the loop. Compared to the configuration, the space occupied by the intermediate transfer belt 10 (belt unit 12) is small, and space saving can be achieved. In addition, the belt tension unit 500 that supports the tension roller 501 that contacts the belt surface 10a side of the intermediate transfer belt 10 and the cleaning unit 17 are arranged close to each other so that the cleaning unit 17 can be attached to and detached from the belt tension unit 500. Therefore, the workability of attaching / detaching the cleaning unit 17 is improved, and the space for the attaching / detaching structure and both units can be saved.

  In the belt tension unit 500 according to the present embodiment, the tension unit frame 503 is provided with a guide member 510 for attaching and detaching the cleaning unit 17, and the slide rail 113 guided by the guide member 510 is disposed in the cleaning unit 17. The space can be saved as compared with the case where each is formed separately from each unit.

  In this embodiment, the intermediate transfer belt 10 is freely contactable / separable with respect to the photoconductors 20Y, 20M, 20C, 20K, and the tension release operation by the position adjusting means 70, 71 serving as the release means is performed by the intermediate transfer belt 10. 13 is separated from the photoconductors 20Y, 20M, 20C, and 20K shown in FIG. 13, and the belt unit 12 is detachable from the printer unit 100 after the tension releasing operation. The transfer belt 10 and the respective photoconductors can be separated greatly, and the image forming units 18Y, 18M, 18C, and 18K including the photoconductors can be attached and detached with one operation, and the belt unit (intermediate transfer unit) 12 can be attached and detached. It is possible to improve the property and release the belt tension, thereby reducing the number of parts and reducing the cost.

  In this embodiment, the belt tension unit 500 is supported by the frame 121 on the back side of the belt unit 12 so that one end of the belt tension unit 500 can swing, so that even when one side of the belt tension unit 500 is removed from the frame 120. Since the end of the unit is supported by the frame 121, the weight of the belt tension unit 500 applied to the operator when attaching and detaching can be reduced, and the operability is improved. Further, since the swing fulcrum when the belt tension unit 500 is attached / detached is on the back side of the printer unit 100, the belt tension unit 500 can be attached / detached with a small force when operated on the front side, and workability is improved.

  In this embodiment, of the positioning holes 153a and 153b constituting the positioning portion 153 of the belt tension unit 500, the hole 153b which is a long hole is used as a secondary reference, and the circular positioning hole 153a into which the pin 512a is inserted is used as a main reference. The detachability of the belt tension unit 500 is improved.

  In this embodiment, since the belt tension unit 500 is attached and detached when the intermediate transfer belt 10 is attached to the belt unit 12, the operation is performed while viewing from below the intermediate transfer belt 10 as shown in FIG. become. For this reason, by positioning the positioning holes 153a and 153b of the positioning portion 153 in the vertical direction on the back side, the positioning holes serving as targets when the pins 512a and 512b of the belt tension unit 500 are inserted into the positioning holes 153a and 153b. 153a and 153b can easily enter the field of view, and the workability during assembly is improved.

  As shown in FIG. 18, the printer unit 100 of the copying machine according to this embodiment covers the belt unit 12, the belt tension unit 500, and the cleaning unit 17 from the front side of the printer unit, and is detachable from the printer unit 100. First to third inner covers 601 to 603 are provided. The inner covers 601 to 603 are exposed when an exterior cover (not shown) provided in the printer unit 100 is opened. In FIG. 18 to FIG. 21, the notation of the frames 120 and 121 is omitted.

As described above, the position adjusting means 70 and 71 serving as pressure releasing means are the operation lever 700 for operating the cam when moving the intermediate transfer belt 10 and the primary transfer roller from the first separated position to the second separated position. It has. As shown in FIG. 18, the operation lever 700 faces the outer side of the inner cover 601 and can be operated without removing the inner cover 601. The operation lever 700 is engaged with the inner cover 601 when the intermediate transfer belt 10 or the primary transfer roller occupies the contact position with each photoconductor, and the inner cover 601 is engaged with the printer. It interferes so that it cannot detach from part 100. As shown in FIG. 19, when the operation lever 700 is rotated counterclockwise in the drawing, the intermediate transfer belt 10, the primary transfer roller, and the like occupy the second separated position. When the operation lever 700 is operated to the separation completion position shown in FIG. 19 and the intermediate transfer belt 10 and the primary transfer roller are in tension release pressure, the interference with the inner cover 601 is avoided, and the inner cover 601 is attached and detached. It is possible. That is, the inner cover 601 is disposed so as to be engageable / detachable with the operation lever 700. In the present embodiment, the first inner cover 601 includes substantially half of the belt unit 12, the cleaning unit 17, and the belt tension unit 500. A part is covered from the front side of the apparatus, and the second inner cover 602 covers the belt tension unit 500, the center of the cleaning unit 17 and the belt unit 12 from the front side of the apparatus. The third inner cover 603 mainly covers the support roller 15 side of the belt unit 12 from the front side of the apparatus.

  Among the plurality of inner covers, the inner cover 602, when attached, partially interferes with the belt tension unit 500 as shown in FIG. 20, and restricts the belt tension unit 500 from being attached to and detached from the copying machine. Yes. To attach and detach the belt tension unit 500, as shown in FIG. 21, the inner covers 601 and 602 are both removed.

  As described above, the inner cover 601 cannot be removed from the printer unit 100 (copier) unless the operation lever 700 is operated to occupy the separation completion position. When the contact position 10 or the primary transfer roller occupies the contact position, it cannot be removed, so that an inadvertent operation into the operating apparatus can be prevented. Further, since a part of the inner cover 602 interferes with a part of the cleaning unit 17 and the belt tension unit 500, the attaching / detaching operation to the belt tension unit 500 and the cleaning unit 17 cannot be performed unless these covers 602 are removed. Therefore, the attachment / detachment operation of the belt tension unit 500 and the cleaning unit 17 when the intermediate transfer belt 10 and the primary transfer roller occupy the contact position and the belt tension is high can be prohibited. Durability can be improved.

  In the above embodiment, the intermediate transfer belt 10 is used as the belt-shaped image carrier, and the belt tension unit 500 is described as a form used for the intermediate transfer belt 10. However, the belt-like image carrier is a belt-shaped photosensitive member. As a matter of course, the belt tension unit 500 can obtain the same effect as that of the present embodiment even when the belt tension unit 500 is used for a belt-shaped photoconductor. Further, the cleaning unit 17 according to the present invention can obtain the same effect as that of the present embodiment even if it is used as a cleaning unit for a belt-shaped photosensitive member instead of cleaning the intermediate transfer belt 10.

DESCRIPTION OF SYMBOLS 10 Belt-shaped image carrier 10a Image carrying surface 12 Belt unit 14, 15, 16 Plural rollers 70, 70A, 71 Decompression means 100 Image forming apparatus main body 120 Front frame 121 Back frame 500 Belt tension unit 501 Tension Member 502 Pressurizing means 503 Tension unit frame 505 Arm member 505a One end of arm member 505b The other end of arm member 506 Pressurizing member 506a One end of pressing member 506b The other end of pressing member 510 Guide member

JP 2000-276007 A JP 2003-216011 A

Claims (5)

A tension member that is provided in the image forming apparatus main body and is in contact with an image carrying surface of a belt-like image carrier that is stretched and rotated by a plurality of rollers, and the tension member is attached to the belt-like image carrier. In a belt tension unit including a pressurizing unit that pressurizes the image bearing surface.
The belt-shaped image carrier is not attached to the image forming apparatus main body or the belt unit having the belt-shaped image carrier, and is not attached or detached when the apparatus is stopped. Belt tension unit, characterized in that it is possible. The belt tension unit according to claim 1, wherein
The tension member extends in the width direction of the belt-shaped image carrier,
The belt tension unit, wherein the pressurizing means are arranged independently in the width direction of the belt-shaped image carrier. The belt tension unit according to claim 1 or 2,
A pair of arm members that support both ends of the tension member at one end thereof, a tension unit frame that rotatably supports each arm member, and both ends of the other end of the arm member and the tension unit frame. A pressure member that pressurizes the tension member toward the belt-shaped image carrier,
In the region surrounded by the pair of arm members and the tension unit frame, the belt-shaped image carrier extends in the width direction, reinforces the tension unit frame, and the width direction of the belt-like image carrier. A belt tension unit having a guide member that supports the movable body so as to be movable. The belt tension unit according to any one of claims 1 to 3,
The belt unit is supported by the front and back frames of the main body of the image forming apparatus, and one end is swingably supported by the back frame. Belt tensioning unit. A belt unit having a belt-like image carrier that is stretched and rotated by a plurality of rollers;
An image including a belt tension unit including a tension member that abuts on an image bearing surface of the belt-shaped image carrier and a pressing unit that pressurizes the tension member toward the image bearing surface of the belt-shaped image carrier. In the forming device,
An image forming apparatus comprising the belt tension unit according to claim 1 as the belt tension unit.

Images