JP4569340B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine, a printer, and a facsimile, and more specifically, an image forming apparatus including an edge sensor that detects an edge of an endless belt provided to convey an image, a sheet, or the like. It relates to devices.

  In recent years, so-called full-color tandem machines have been proposed in image forming apparatuses such as printers, copiers, and facsimile machines for the purpose of forming color images at high speed and high image quality. As a typical tandem machine, four image forming units of yellow (Y), magenta (M), cyan (C), and black (K) are arranged in parallel with each other, and each of these image forming units. The toner images of yellow, magenta, cyan, and black, which are sequentially formed in Step 1, are transferred onto the intermediate transfer belt once in a multiple (primary transfer), and then transferred from the intermediate transfer belt onto the paper in a batch ( (Secondary transfer) and fixing the toner image formed on the paper to form a full-color or black-and-white (monochrome) image.

In this type of image forming apparatus, if the intermediate transfer belt meanders while rotating, the color toner images are shifted and superimposed on the intermediate transfer belt. I will invite you. Further, in the secondary transfer, the transfer position of the superimposed toner image with respect to the recording material is shifted, so that the image quality is further deteriorated.
Therefore, an edge sensor that detects the end of the intermediate transfer belt in the direction orthogonal to the rotation direction, that is, a belt edge, is provided, and various rolls that stretch the intermediate transfer belt are installed based on the detection result of the belt edge by the edge sensor. There is a technique for correcting the meandering of the intermediate transfer belt by tilting a predetermined roll (steering roll) (see Patent Document 1). In the technique described in Patent Document 1, a contact that is swingably arranged around an axis is used as an edge sensor, and a side surface on one end side of the contact is separated from the intermediate transfer belt using a spring. By pulling the contact, the side surface on the other end side of the contact is brought into contact with the belt edge of the intermediate transfer belt to follow the movement of the belt edge. Then, the meandering state of the intermediate transfer belt is detected by detecting the position of the contact.

In addition, the intermediate transfer belt needs to be periodically replaced because its electrical and mechanical characteristics decrease as the usage history increases.
In view of this, there is a technique that allows the intermediate transfer belt to be replaced by releasing the tension applied to the intermediate transfer belt, for example, by loosening the steering roll among a plurality of rolls that stretch the intermediate transfer belt (Patent Document 2). reference.). In the image forming apparatus described in Patent Document 2, a secondary transfer device is provided below the intermediate transfer belt, and the edge sensor is disposed in the vicinity of the secondary transfer device, whereby the secondary transfer device is provided. The meandering of the intermediate transfer belt in the vicinity of the transfer device is detected.

JP 2000-34031 A (Page 4, FIG. 3) JP 2004-317773 A (page 3, page 12, FIG. 6, FIG. 10)

By the way, in the image forming apparatus disclosed in Patent Document 2, when the tension applied to the intermediate transfer belt is released, the intermediate transfer belt is stretched around various rolls in a state of hanging downward. In particular, the image forming apparatus disclosed in Patent Document 2 has the following problem because the edge sensor is provided below the intermediate transfer belt.
The contact provided in the edge sensor is urged by using a spring so as to contact the belt edge of the intermediate transfer belt. Therefore, when the tension applied to the intermediate transfer belt is released and the intermediate transfer belt hangs downward, the belt edge does not exist at a portion facing the side surface on the one end side of the contact. It is held in a state of protruding to the intermediate transfer belt side. Then, a new intermediate transfer belt is wound around the various rolls by replacement, and when the tension is applied to the new intermediate transfer belt, one end of the contact of the edge sensor is not in contact with the edge of the intermediate transfer belt. I will come in contact. When such a phenomenon occurs, not only the belt edge cannot be detected, but also the contact and the intermediate transfer belt may be damaged.

  In order to deal with such a problem, in Patent Document 2, the edge sensor is provided with a retracting elastic member that retracts one end of the contact outside the edge of the intermediate transfer belt against the elastic force of the spring. In addition, the belt is connected to a belt frame to which various rolls for stretching the intermediate transfer belt are attached while tension is applied to the intermediate transfer belt. A bracket having a function of urging the elastic member is provided. The original function of this bracket is to attach a sticking detection sensor for detecting the sticking of the sheet to the intermediate transfer belt after the secondary transfer, downstream of the secondary transfer device in the moving direction of the intermediate transfer belt. belongs to. Since the bracket is disposed to face the surface of the intermediate transfer belt, it is necessary to apply an insulating coating or the like, which is very expensive.

  However, recently, by devising the configuration of the secondary transfer device and the like, paper sticking to the intermediate transfer belt has hardly occurred. For this reason, there has been a request to remove the sticking detection sensor and the bracket for attaching the sticking detection sensor, and there has been a demand for the development of a new retracting mechanism for the contact provided in the edge sensor.

The present invention has been made to solve such a technical problem, and the object of the present invention is to have a simple configuration, and the endless belt and the edge sensor interfere when the endless belt is attached. Is to prevent.
Another object is to enable edge detection of an endless belt by an edge sensor after the endless belt is attached with a simple configuration.

  For this purpose, an image forming apparatus to which the present invention is applied has a drawer that can be pulled out from the apparatus main body, and an endless belt that is rotatably supported by a plurality of rolls. A belt module that can be accommodated, an edge sensor that is attached to the belt module and that detects the edge position of the endless belt using an edge contact member that contacts the edge of the endless belt, and moves the belt module within the drawer And a contact / separation mechanism for bringing the edge contact member of the edge sensor into contact with and separating from the endless belt in conjunction with the operation of the movement mechanism.

  The image forming apparatus further includes an image carrier that carries an image, and the moving mechanism includes a belt module, a first position where the endless belt contacts the image carrier, and a first position where the endless belt is separated from the image carrier. When the belt module is in the first position, the contact / separation mechanism causes the edge contact member to contact the endless belt when the belt module is in the first position, and the endless belt when the belt module is in the second position. The edge contact member can be separated from the edge. In this case, the drawer may be characterized in that it can be pulled out from the apparatus main body when the belt module is in the second position. Furthermore, the tension applied to the endless belt can be released by moving at least one of the plurality of rolls that stretch the endless belt. In this case, the edge sensor may be arranged below the endless belt.

  From another point of view, an image forming apparatus to which the present invention is applied has a drawer that can be pulled out from the apparatus main body, and an endless belt that is rotatably supported by a plurality of rolls. A belt module that can be accommodated in the drawer, an edge sensor that is attached to the belt module and detects an edge position of the endless belt using an edge contact member that contacts the edge of the endless belt; An abutment retracting mechanism for abutting the edge abutting member against the endless belt when set inside, and retracting the edge abutting member from the endless belt when the drawer is pulled out from the apparatus main body.

The image forming apparatus further includes an image carrier that carries an image, and the belt module is moved to a position where the endless belt contacts the image carrier when the drawer is set in the apparatus body. When the belt is pulled out, the endless belt is moved away from the image carrier. The belt module may be supported by the drawer so as to be movable up and down. Further, the belt module can be characterized in that it is swingably supported by the drawer.
The endless belt is an image carrier that carries and conveys an image. The endless belt further includes a transfer unit that transfers an image on the endless belt to a recording material below the endless belt. Can contact the edge of the endless belt near the transfer portion.

  Further, from another viewpoint, the present invention is an edge sensor that detects the edge position of a rotating endless belt, and is disposed so as to be swingable with respect to an axis along the moving direction of the endless belt. An edge abutting member that can abut on the edge of the endless belt, and a first biasing member that biases the edge abutting member so that one end of the edge abutting member swings toward the endless belt; A second urging member provided so as to be freely contactable to and away from the edge abutting member and retracting one end portion from the endless belt when urged against the edge abutting member; And an arm member attached to the biasing member and retracted from the other end side of the edge abutting member by being pressed by another member.

  Here, the arm member may be characterized by extending in a direction away from the endless belt. In the edge abutting member, the one end side may be a lower side. Furthermore, the first urging member can be attached to the other end side opposite to the one end side. Furthermore, the second urging member can be attached to and separated from the other end side opposite to the one end side.

  According to the present invention, for example, the endless belt and the edge contact member of the edge sensor are brought into contact with and separated from each other in conjunction with the movement of the belt module in the drawer. Interference with the sensor can be prevented. Further, after the endless belt is attached, the edge of the endless belt can be detected by the edge sensor.

The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a diagram illustrating an image forming apparatus to which the exemplary embodiment is applied. The image forming apparatus shown in FIG. 1 is a so-called tandem type, so-called intermediate transfer type image forming apparatus, and a main body 1 as a main body of the apparatus, and a plurality of image forming units in which toner images of respective color components are formed by electrophotography. A unit 10 (10Y, 10M, 10C, 10K) and an intermediate transfer belt 15 for sequentially transferring (primary transfer) and holding each color component toner image formed by each image forming unit 10 are provided. The image forming apparatus also includes a secondary transfer unit 20 that collectively transfers (secondary transfer) the superimposed toner image transferred onto the intermediate transfer belt 15 onto the paper P, and fixes the secondary transferred image onto the paper P. A fixing unit 60 is provided. The image forming apparatus also includes a control unit 40 that controls the operation of each device (each unit) and a user interface (UI) 41 that is used to give an operation instruction by the user.

  In the present embodiment, in each image forming unit 10 (10Y, 10M, 10C, 10K), the photosensitive drums 11 are charged around the photosensitive drums 11 as image bearing members that rotate in the direction of arrow A. A charging device 12, a laser exposure device 13 in which an electrostatic latent image is written on the photosensitive drum 11 (exposure beam is indicated by a symbol Bm in the drawing), and electrostatic toner on the photosensitive drum 11 containing each color component toner. A developing device 14 that visualizes the latent image with toner, a primary transfer roll 16 that transfers each color component toner image formed on the photosensitive drum 11 to the intermediate transfer belt 15, and residual toner on the photosensitive drum 11 are removed. The electrophotographic devices such as the drum cleaner 17 are sequentially arranged. These image forming units 10 are arranged substantially linearly in the order of yellow (Y color), magenta (M color), cyan (C color), and black (K color) from the upstream side of the intermediate transfer belt 15. Yes.

The intermediate transfer belt 15 as an endless belt or an image carrier is a material in which an appropriate amount of an antistatic agent such as carbon black is contained in a resin such as polyimide or polyamide, and has a volume resistivity of 10 ⁶ to 10 ^14. It is formed to be Ω · cm, and is formed of a film-like endless belt having a thickness of, for example, about 0.1 mm. The intermediate transfer belt 15 is circulated (rotated) at a predetermined speed in the direction B shown in the figure by various rolls (a plurality of rolls). As these various rolls, a drive roll 31 that is driven by a motor (not shown) having excellent constant speed and circulates and drives the intermediate transfer belt 15, and an intermediate that extends substantially linearly along the arrangement direction of the photosensitive drums 11. A support roll 32 that supports the transfer belt 15 is provided. Similarly, as various rolls, a tension roll 33 that functions as a correction roll that applies a constant tension to the intermediate transfer belt 15 and prevents meandering of the intermediate transfer belt 15, a backup roll 25 provided in the secondary transfer unit 20, A support roll 34 that supports the intermediate transfer belt 15 is provided between the backup roll 25 and the drive roll 31. The tension roll 33 as one roll is provided with an arm 36 that incorporates a spring or the like and applies a predetermined urging force to the tension roll 33 and tilts the tension roll 33. Further, on the free end side of the arm 36, a cam 37 is provided that urges the tension roll 33 by the arm 36 by rotating or releases the urging force.

  A primary transfer bias having a polarity opposite to the charging polarity of the toner is applied to each primary transfer roll 16 provided inside the intermediate transfer belt 15 facing the respective photosensitive drums 11 and extending substantially linearly. As a result, the toner images on the respective photosensitive drums 11 are sequentially electrostatically attracted to the intermediate transfer belt 15 to form toner images superimposed on the intermediate transfer belt 15.

  The secondary transfer unit 20 includes a secondary transfer conveyance belt 21 disposed on the toner image carrying surface side of the intermediate transfer belt 15, a backup roll 25, and the like. The backup roll 25 is a tube of EPDM and NBR blend rubber with carbon dispersed on the surface, and the inside is made of EPDM rubber, and the surface resistivity is 7 to 10 logΩ / □ and the roll diameter is 28 mm. Is set to 70 ° (Asker C), for example. The backup roll 25 is disposed on the back side of the intermediate transfer belt 15 and serves as a counter electrode of the secondary transfer conveyance belt 21. Further, a power supply roll 26 for applying a secondary transfer bias is disposed in contact with the backup roll 25.

On the other hand, the secondary transfer conveyance belt 21 is a semiconductive endless belt stretched by a drive roll 22 and an idle roll 23 and having, for example, a volume resistivity of 10 ⁶ to 10 ¹⁰ Ωcm. The secondary transfer conveyance belt 21 is driven by a driving roll 22 and given a predetermined tension by an idle roll 23. The driving roll 22 is disposed in pressure contact with the backup roll 25 with the secondary transfer conveyance belt 21 and the intermediate transfer belt 15 interposed therebetween, and performs a secondary transfer on the sheet P conveyed on the secondary transfer conveyance belt 21. Is functioning as In this embodiment, the secondary transfer unit 100 is configured by the secondary transfer conveyance belt 21, the drive roll 22, and the idle roll 23. In the secondary transfer unit 100, the drive roll 22 can swing in the direction of the arrow in the figure with the idle roll 23 as an axis. For example, when the intermediate transfer belt 15 is replaced, the intermediate transfer belt is used as necessary. The secondary transfer conveyance belt 21 can be separated from the belt 15.

  In this embodiment, since the secondary transfer conveyance belt 21 is used in the secondary transfer unit 20, the paper P that has passed through the secondary transfer unit 20 is easily guided to the secondary transfer conveyance belt 21 side. That is, the phenomenon that the sheet P after the secondary transfer is stuck to the intermediate transfer belt 15 is less likely to occur. For this reason, in the present embodiment, a separation claw that separates the sheet P after the secondary transfer from the intermediate transfer belt 15 and a sheet detection sensor that detects sticking of the sheet P after the secondary transfer to the intermediate transfer belt 15. Etc. are not provided. Accordingly, a POB (Paper On Belt) bracket or the like for mounting a paper detection sensor is not attached to the downstream side of the secondary transfer unit 20.

Further, on the downstream side of the secondary transfer portion 20 of the intermediate transfer belt 15, the intermediate transfer belt 15 is disposed so as to face the drive roll 31, and residual toner and the like on the intermediate transfer belt 15 after the secondary transfer are removed. A belt cleaner 35 to be removed is provided.
Further, a first edge sensor 42 for detecting an edge position on the side of the intermediate transfer belt 15 on the downstream side of the black image forming unit 10K and the upstream side of the support roll 32 with respect to the moving direction B of the intermediate transfer belt 15. Is provided. On the other hand, a second edge sensor 43 that detects the edge position on the side of the intermediate transfer belt 15 is provided in the vicinity of the downstream side of the secondary transfer unit 20 with respect to the moving direction B of the intermediate transfer belt 15. The first edge sensor 42 and the second edge sensor 43 are disposed on the rear side of the intermediate transfer belt 15 in the main body 1 for the reason described later. The control unit 40 calculates the meandering (walk) amount of the intermediate transfer belt 15 based on the edge position of the intermediate transfer belt 15 detected by the first edge sensor 42 and the second edge sensor 43, Based on the obtained amount of meandering, meandering adjustment by the tension roll 33 is performed.

Further, in the present embodiment, as a paper transport system, a paper tray 50 that stores paper P, a pick-up roll 51 that picks up and transports the paper P accumulated in the paper tray 50 at a predetermined timing, and a pick-up roll 51 A transport roll 52 that transports the fed paper P, and a transport chute 53 that feeds the paper P transported by the transport roll 52 to the secondary transfer unit 20 are provided. Further, the paper transport system includes a transport belt 54 that transports the paper P transported after the secondary transfer by the secondary transfer transport belt 21 to the fixing unit 60.
Furthermore, the fixing unit 60 includes a heating roll 61 that is rotatably arranged and is heated by a heating source (not shown), and a pressure belt 62 that is rotatably pressed against the heating roll 61.

  In the present embodiment, a drawer 70 that can be inserted into and removed from the front side of the main body 1 is provided at a substantially central portion in the vertical direction of the main body 1 of the image forming apparatus. Is contained. In addition to the intermediate transfer belt 15, the belt module 110 includes a primary transfer roll 16, a drive roll 31, a support roll 32, a tension roll 33, a support roll 34, a backup roll 25, a belt cleaner 35, a power supply roll 26, One edge sensor 42, a second edge sensor 43, and the like are included. Details of the drawer 70 and the belt module 110 will be described later.

  Next, a basic image forming process of the image forming apparatus according to the present embodiment will be described. Image data output from an image reading device (IIT) (not shown), a personal computer (PC) (not shown), or the like is input to an image forming apparatus as shown in FIG. In the image forming apparatus, after predetermined image processing is performed by an image processing apparatus (IPS) (not shown), an image forming operation is performed by the image forming unit 10 or the like. In the image processing apparatus (IPS), the input reflectance data is subjected to predetermined image editing such as shading correction, positional deviation correction, brightness / color space conversion, gamma correction, frame deletion, color editing, and moving editing. Image processing is performed. The image data that has been subjected to image processing is converted into color material gradation data of four colors of yellow (Y), magenta (M), cyan (C), and black (K), and is output to the laser exposure unit 13. .

  The laser exposure unit 13 irradiates the photosensitive drums 11 of the image forming units 10Y, 10M, 10C, and 10K with, for example, an exposure beam Bm emitted from a semiconductor laser according to the input color material gradation data. Yes. In the photosensitive drum 11 of the image forming units 10Y, 10M, 10C, and 10K, the surface is charged by the charger 12, and then the surface is scanned and exposed by the laser exposure unit 13 to form an electrostatic latent image. The formed electrostatic latent images are yellow (Y), magenta (M), cyan (C), and black (K) by the developing device 14 in the respective image forming units 10Y, 10M, 10C, and 10K. Developed as a toner image.

  The toner images formed on the photosensitive drums 11 of the image forming units 10Y, 10M, 10C, and 10K are transferred onto the intermediate transfer belt 15 at the primary transfer portion where the photosensitive drums 11 and the intermediate transfer belt 15 come into contact with each other. Transcribed. More specifically, in the primary transfer portion, a voltage having a polarity opposite to the toner charging polarity is applied to the substrate of the intermediate transfer belt 15 by the primary transfer roll 16, and the unfixed toner image is transferred to the surface of the intermediate transfer belt 15. Are sequentially superposed on each other to perform primary transfer. The unfixed toner image primarily transferred in this way is conveyed to the secondary transfer unit 20 as the intermediate transfer belt 15 rotates.

  On the other hand, in the paper transport system, the pickup roll 51 rotates in synchronization with the image formation timing, and the paper P of a predetermined size is supplied from the paper tray 50. The paper P supplied by the pickup roll 51 is transported by the transport roll 52 and reaches the secondary transfer unit 20 via the transport chute 53. Before reaching the secondary transfer unit 20, the paper P is temporarily stopped, and the registration roll (not shown) rotates in accordance with the movement timing of the intermediate transfer belt 15 carrying the toner image as described above. Thus, the position of the paper P and the position of the toner image are aligned.

  In the secondary transfer unit 20, the drive roll 22 is pressed against the backup roll 25 via the semiconductive secondary transfer conveyance belt 21 and the intermediate transfer belt 15. At this time, the sheet P transported at the same timing is sandwiched between the intermediate transfer belt 15 and the secondary transfer transport belt 21. At this time, when a voltage having the same polarity as the toner charging polarity is applied to the power supply roll 26, a transfer electric field is formed with the secondary transfer conveyance belt 21 as a counter electrode, and the toner image carried on the intermediate transfer belt 15 is Then, electrostatic transfer is performed on the paper P at the secondary transfer position pressed by the drive roll 22 and the backup roll 25.

  Thereafter, the sheet P on which the toner image has been electrostatically transferred is conveyed as it is while being peeled off from the intermediate transfer belt 15 by the secondary transfer conveyance belt 21, and is provided downstream of the secondary transfer conveyance belt 21 in the sheet conveyance direction. It is conveyed to the conveyor belt 54. The conveyance belt 54 conveys the paper P to the fixing unit 60 in accordance with the optimum conveyance speed in the fixing unit 60. The toner image on the paper P conveyed to the fixing unit 60 is fixed on the paper P by receiving a fixing process with heat and pressure in the fixing unit 60. The paper P on which the fixed image is formed is discharged to the outside of the image forming apparatus by a discharge roll (not shown). On the other hand, after the transfer onto the paper P is completed, the residual toner remaining on the intermediate transfer belt 15 is conveyed to a position facing the belt cleaner 35 as the intermediate transfer belt 15 rotates, and is intermediated by the belt cleaner 35. It is removed from the transfer belt 15.

  In this image forming apparatus, since the characteristics of the intermediate transfer belt 15 deteriorate as the number of prints increases, periodic replacement is necessary. Therefore, in this embodiment, as described above, the intermediate transfer belt 15 can be easily replaced by allowing the drawer 70 in which the belt module 110 including the intermediate transfer belt 15 is accommodated to be pulled out from the main body 1. It is configured as follows.

  FIG. 2 is a perspective view showing a drawer 70 provided in the main body 1 of the image forming apparatus shown in FIG. 3 and 4 are perspective views showing the drawer 70 and the belt module 110 attached to the drawer 70. FIG. 3 shows a state in which the belt module 110 is accommodated in the drawer 70, and FIG. 4 shows a state in which the belt module 110 is pulled up from the drawer 70. However, in FIG. 3, the belt cleaner 35 is removed from the belt module 110.

  The drawer 70 includes a front frame 71 provided on the front side of the main body 1 (see FIG. 1) and a rear frame 72 provided on the rear side. The drawer 70 is provided on the left side when viewed from the front side of the main body 1, the left frame 73 connecting the left end portion of the front frame 71 and the left end portion of the rear frame 72, and provided on the right side when viewed from the front side of the main body 1. The light frame 74 is provided to connect the right end of the front frame 71 and the right end of the rear frame 72. Further, the drawer 70 is provided at the lower left portion when viewed from the front side of the main body 1, and the left under frame 75 connecting the lower left portion of the front frame 71, the lower left portion of the rear frame 72, and the lower portion of the left frame 73, A light under frame 76 is provided at the lower right portion when viewed from the front side, and connects the lower right portion of the front frame 71, the lower right portion of the rear frame 72, and the lower portion of the light frame 74. Note that the lower center of the drawer 70 is opened because the intermediate transfer belt 15 needs to be exposed to the lower side.

  A left rail 77 extending in a direction perpendicular to the moving direction of the intermediate transfer belt 15 (the rotation axis direction of the intermediate transfer belt 15) is attached to the outer side surface of the left frame 73. On the other hand, a right rail 78 parallel to the left rail 77 is mounted on the outer side surface of the right frame 74. The left rail 77 and the right rail 78 are inserted into guide rails (described later) provided on the main body 1 of the image forming apparatus, and thereby the drawer 70 can be pulled out to the front side of the main body 1. It is possible.

  Further, a first shaft 81 that is rotatably disposed through the front frame 71 and the rear frame 72 is provided at the lower left portion of the drawer 70. A first lever 82 that is fixed to the first shaft 81 and rotates the first shaft 81 is attached to the front side and the left side of the front frame 71. Further, a first eccentric cam 83 fixed to the first shaft 81 is attached to the front side and the left side of the rear frame 72. On the right side of the first lever 82, a first stopper 84 that swings in conjunction with the first lever 82 via a link mechanism is mounted. Although not shown, a first eccentric cam 83 is attached to the first shaft 81 also on the rear side of the front frame 71.

  On the other hand, on the lower right side of the drawer 70, a second shaft 85 that is rotatably disposed through the front frame 71 and the rear frame 72 is provided. A second lever 86 that is fixed to the second shaft 85 and rotates the second shaft 85 is attached to the front side and the right side of the front frame 71. Furthermore, a second eccentric cam 87 fixed to the second shaft 85 is attached to the front side and the right side of the rear frame 72. A second stopper 88 that swings in conjunction with the second lever 86 via a link mechanism is mounted on the left side of the second lever 86. Although not shown, a second eccentric cam 87 is attached to the second shaft 85 on the rear side of the front frame 71.

  In the present embodiment, the first shaft 81, the first lever 82, the first eccentric cam 83, the first stopper 84, the second shaft 85, the second lever 86, and the second eccentricity. The moving mechanism of the belt module 110 is configured by the cam 87, the second stopper 88, and the like.

  The belt module 110 includes various rolls (primary transfer roll 16, drive roll 31, support roll 32, tension roll 33, support roll 34, backup roll 25, power supply roll 26) used to stretch the intermediate transfer belt 15. : See FIG. 1) includes a first side plate 111 and a second side plate 112 that are rotatably attached. The first side plate 111 and the second side plate 112 are also attached with a belt cleaner 35, an arm 36, a cam 37, and the like shown in FIG. Here, the first side plate 111 is disposed on the front frame 71 side of the drawer 70, that is, the front side of the main body 1, and the second side plate 112 is disposed on the rear frame 72 side of the drawer 70, that is, the rear side of the main body 1. Note that the first edge sensor 42 and the second edge sensor 43 shown in FIG. 1 are attached to the second side plate 112.

  In the state shown in FIG. 2 (the state where the first lever 82 and the second lever 86 face substantially upward), the upper surfaces of the first eccentric cam 83 and the second eccentric cam 87 are placed at higher positions. Here, on the first eccentric cam 83 and the second eccentric cam 87, the first side plate 111 and the second side plate 112 (see FIGS. 3 and 4) of the belt module 110 are placed. . For this reason, for example, in the state shown in FIG. 2 (the state shown in FIG. 3), the belt module 110 is accommodated inside the drawer 70, but the upper side protrudes from the drawer 70. At this time, the intermediate transfer belt 15 contacts the photosensitive drums 11 of the image forming units 10Y, 10M, 10C, and 10K. At this time, the belt module 110 is said to be in the first position.

  On the other hand, when the first lever 82 and the second lever 86 are operated in the direction of the arrows in the figure, the upper surfaces of the first eccentric cam 83 and the second eccentric cam 87 are positioned lower than those shown in FIG. I'm left. Then, the first side plate 111 and the second side plate 112 are lowered, and as a result, the position of the belt module 110 is lowered, and the belt module 110 is further accommodated in the drawer 70. In this state, the intermediate transfer belt 15 of the belt module 110 is separated from the photosensitive drums 11 of the image forming units 10Y, 10M, 10C, and 10K. At this time, the belt module 110 is said to be in the second position. Further, the amount of height fluctuation of the belt module 110 due to the operation of the first lever 82 and the second lever 86 is set to about 5 mm.

  When the first lever 82 is operated in the direction of the arrow in the drawing, the first stopper 84 is also rotated in the direction of the arrow in conjunction with this, and as a result, the stopper surface 84a provided at the lower portion of the first stopper 84. Moves upward. The stopper surface 84a has a function of locking the secondary transfer unit 100 shown in FIG. 1, and the locking of the secondary transfer unit 100 is released when the stopper surface 84a moves upward. Further, in the state shown in FIG. 2, the upper ends of the first lever 82, the first stopper 84, the second lever 86, and the second stopper 88 are the image forming units 10Y, 10M, 10C, 10K is locked. Then, by operating the first lever 82 and the second lever 86 in the direction of the arrows in the figure, the locking of the image forming units 10Y, 10M, 10C, and 10K is released.

  Furthermore, in the present embodiment, a shaft (not shown) (see shaft 117 shown in FIGS. 10 and 11 described later) is attached to the upper portion of the rear frame 72 of the drawer 70 along the rear frame 72. On the other hand, the upper part of the second side plate 112 of the belt module 110 is swingably attached. This shaft is configured to be linked to the vertical movement of the belt module 110 so as to move up and down. Therefore, as shown in FIG. 4, the belt module 110 swings around the rear side of the drawer 70, and the front side is lifted upward.

  Next, the second edge sensor 43 used for detecting the edge of the intermediate transfer belt 15 will be described in detail. As described above, the second edge sensor 43 is attached to the belt module 110, specifically, the second side plate 112 provided on the rear side of the belt module 110. 5 to 7 are perspective views showing the second edge sensor 43, FIG. 5 is a view seen from the intermediate transfer belt 15 side, FIG. 6 is a view seen from the opposite side to FIG. Reference numeral 7 denotes a state in which the edge of the intermediate transfer belt 15 is detected by being attached to the second side plate 112.

  As shown in FIG. 7, an edge detection through hole 113 for attaching the second edge sensor 43 is formed on the lower side of the second side plate 112. A pair of belt position regulating members 114 having a cylindrical surface are formed to protrude toward the front side. Further, a single positioning pin 115 is formed so as to protrude toward the front side on the right side of the edge detection through hole 113 of the second side plate 112 when viewed from the intermediate transfer belt 15 side.

  And the 2nd edge sensor 43 is provided with the position detection bracket 120 connected with the 2nd side plate 112, as shown in FIGS. The position detection bracket 120 includes a frame attachment portion 121 for connection to the second side plate 112, and an edge contact member connection portion 122 that protrudes from the left end of the frame attachment portion 121 to the front side when viewed from the intermediate transfer belt 15 side. And a sensor mounting portion 123 extending leftward from the front side of the edge contact member connecting portion 122 and a through portion 124 extending from the lower end of the frame mounting portion 121 to the rear side and penetrating the edge detection through hole 113. is doing. The position detection bracket 120 is connected to the rear side end of the through portion 124 and extends upward, and is connected to the rear side end of the through portion 124 and below the through portion 124. And a leaf spring connecting portion 126 disposed on the surface.

  Further, the frame mounting portion 121 of the position detection bracket 120 has a pin fitting hole 121a for fitting to a positioning pin 115 provided on the second side plate 112, and a screw through hole 121b. The position detection bracket 120 is fixed to the second side plate 112 by screws (not shown) passing through the screw through holes 121b and screw holes (not shown) provided in the second side plate 112. It has become so. When the position detection bracket 120 is connected to the second side plate 112, the through portion 124 of the position detection bracket 120 passes through the edge detection through hole 113 in the front-rear direction. Therefore, in the position detection bracket 120, the frame attachment portion 121, the edge contact member connection portion 122, and the sensor attachment portion 123 are arranged on the front side of the second side plate 112, and the tension spring connection portion 125 and the plate spring are arranged. The connecting portion 126 is disposed on the rear side with respect to the second side plate 112.

  Further, a shaft 127 extending parallel to the moving direction of the intermediate transfer belt 15 is fixed to the edge contact member connecting portion 122 of the position detection bracket 120, and the edge contact member 128 swings on the shaft 127. It is supported freely. Further, a stopper 122 a extending leftward when viewed from the intermediate transfer belt 15 side is provided on the front side of the lower end portion of the edge contact member connecting portion 122. The stopper 122a restricts the rotation range when the lower portion of the edge contact member 128 rotates to the front side. A tension spring 129 as a first biasing member is provided between the upper portion of the shaft 127 of the edge contact member 128 and the tension spring connecting portion 125, and the edge contact member 128 has a tension spring 129. The spring 129 exerts a force to rotate the lower end portion thereof to the front side (intermediate transfer belt 15 side) at all times. That is, the tension spring 129 functions to cause the edge abutting member 128 to exert a force with its lower end pressing the rear edge of the intermediate transfer belt 15.

  The sensor mounting portion 123 of the position detection bracket 120 includes a light emitting element and a light receiving element (not shown), and is connected to the optical sensor 130 that detects the swing position of the edge contact member 128 and the optical sensor 130. A circuit board 131 is supported. A connector 131 a is fixedly disposed on the upper end of the circuit board 131. The connector 131a is connected to the control unit 40 (see FIG. 1) via a cable with a connector (not shown). The optical sensor 130 detects light reflected by the edge contact member 128 through the light transmission hole 130a shown in FIG. 6 and detects the swing position of the upper end portion of the edge contact member 128. The edge position on the rear side of the intermediate transfer belt 15 is detected.

  Further, a retracting elastic member 132 as a second urging member formed of a stainless steel plate spring is connected to the lower surface of the plate spring connecting portion 126 of the position detection bracket 120. The retracting elastic member 132 is provided in the vicinity of the leaf spring coupling portion 126 and has a shape that curves toward the upper portion, thereby generating an elastic force, and an upper end from the upper end of the lower bending portion 132a. And a pressing portion 132c that extends laterally from the upper end of the arm 132b and presses the rear side surface of the upper end of the edge contact member 128 toward the front. In a state in which the retracting elastic member 132 presses the upper portion of the edge contact member 128 to the front side by its elastic force, the lower end portion of the edge contact member 128 is swung to the rear side and the intermediate transfer belt 15 is moved. It moves to the rear side of the rear side edge. That is, the retracting elastic member 132 formed of a leaf spring functions to retract the lower end portion of the edge contact member 128 from the rear edge of the intermediate transfer belt 15 against the elastic force of the tension spring 129. is doing.

  Further, a retracting arm 133 as an arm member made of metal is connected to the rear side of the substantially vertical central portion of the arm portion 132b of the retracting elastic member 132. The retracting arm 133 includes a first arm portion 133a extending substantially horizontally from the arm portion 132b of the retracting elastic member 132 toward the rear side, and an obliquely lower side from the rear side end of the first arm portion 133a. A second arm portion 133b extending in the direction, and a third arm portion 133c extending substantially horizontally from the rear side end portion of the second arm portion 133b.

  Next, a procedure for replacing the intermediate transfer belt 15 in this image forming apparatus will be described with reference to FIGS. 1 to 4, 8, and 9. FIG. 8 is a side view showing a state in which the drawer 70 is pulled out to the front side of the main body 1 of the image forming apparatus and the belt module 110 is lifted from the drawer 70. FIG. 9 is a view showing the intermediate transfer belt 15 stretched over various rolls such as the drive roll 31. Here, FIG. 9A shows a state where tension is applied by various rolls and the intermediate transfer belt 15 is stretched. FIG. 9B shows a state in which the tension is released by an operation described later and the intermediate transfer belt 15 is stretched over various rolls in a relaxed state. That is, FIG. 9A shows a state when the intermediate transfer belt 15 is used for image formation, and FIG. 9B shows a state when the intermediate transfer belt 15 is replaced by an operation described later.

  Now, a specific procedure for replacing the intermediate transfer belt 15 will be described. First, the first lever 82 and the second lever 86 provided on the drawer 70 are operated in the direction of the arrow shown in FIG. As a result, the position of the belt module 110 in the drawer 70 is lowered, and the intermediate transfer belt 15 provided in the belt module 110 is separated from the photosensitive drums 11 provided in the image forming units 10Y, 10M, 10C, and 10K. . Further, the lock (locking) of the secondary transfer unit 100 is released in accordance with the operation of the first lever 82. Subsequently, the unlocked secondary transfer unit 100 is operated, and the drive roll 22 is moved in the arrow direction shown in FIG. Then, the secondary transfer conveyance belt 21 is separated from the intermediate transfer belt 15. As a result, the intermediate transfer belt 15 is separated from the photosensitive drum 11 and the secondary transfer conveyance belt 21.

  Next, the drawer 70 in which the belt module 110 is accommodated is pulled out to the front side of the main body 1 of the image forming apparatus. Note that guide rails 90 (see FIG. 8) into which the left rail 77 and the right rail 78 of the drawer 70 are inserted are attached to both inner sides of the main body 1, and the drawer 70 is smoothly pulled out to the front side. . When the drawer 70 is pulled out to the front side of the main body 1 and the front side of the belt module 110 is pulled upward, the belt module 110 swings around the rear side and is held in an inclined state. That is, the state shown in FIG. 8 is obtained. During this time, the intermediate transfer belt 15 is maintained in a state where it is stretched between various rolls with a predetermined tension, that is, the state shown in FIG.

When the cam 37 provided on the belt module 110 is operated by a lever or the like (not shown), the arm 36 is drawn into the intermediate transfer belt 15 along with the operation of the cam 37, and along with this, the tension roll 33 is pulled. Is also drawn into the intermediate transfer belt 15. As a result, the tension applied to the intermediate transfer belt 15 is released. That is, the state shown in FIG. 9A shifts to the state shown in FIG. In a state in which the tension applied to the intermediate transfer belt 15 is released in order to replace the intermediate transfer belt 15, the intermediate transfer belt 15 sag as shown in FIG. 9B. At this time, since a downward force is applied to the intermediate transfer belt 15 due to gravity, the intermediate transfer belt 15 hangs down as a result.
In this state, the intermediate transfer belt 15 is removed and a new intermediate transfer belt 15 is attached. Thereafter, the belt module 110 including the new intermediate transfer belt 15 and the drawer 70 to which the belt module 110 is attached are set to the main body 1 by a procedure reverse to the above-described procedure.

  FIGS. 10 and 11 are diagrams for explaining the behavior on the rear side of the drawer 70 and the belt module 110 during the replacement of the intermediate transfer belt 15 described above. 10 shows a state in which the belt module 110 is set in the main body 1 (see FIG. 1) of the image forming apparatus, that is, a state in which the intermediate transfer belt 15 is brought into contact with each photosensitive drum 11. Further, in FIG. 11, the position (height) of the belt module 110 in the drawer 70 is relatively lowered by operating the first lever 82 and the second lever 86, and the intermediate position from each photosensitive drum 11. A state in which the transfer belt 15 is separated is shown. FIG. 5 is also a diagram showing the behavior of the second edge sensor 43 in the state shown in FIG. 6 is also a diagram showing the behavior of the second edge sensor 43 in the state shown in FIG.

  10 and 11, a protrusion 116 provided with a circular perforation (not shown) is formed on the rear side surface of the second side plate 112 in the belt module 110. On the other hand, a protrusion 79 having an oval perforation 79a formed in the vertical direction is formed on the upper portion of the front side surface of the rear frame 72 of the drawer 70. A shaft 117 is provided through a perforation (not shown) formed in the protrusion 116 and a perforation 79 a provided in the protrusion 79. Accordingly, the belt module 110 including the second side plate 112 is supported so as to be able to move up and down relatively with respect to the drawer 70 including the rear frame 72. Further, the belt module 110 can swing with respect to the drawer 70 about the shaft 117 as an axis. Further, in the present embodiment, the retracting arm 133 (specifically, the second edge sensor 43 attached to the second side plate 112 of the belt module 110 in a state where the belt module 110 is set in the drawer 70. A third arm portion 133 c) is disposed directly below the lower end portion of the rear frame 72 provided on the drawer 70.

  10 and FIG. 5, the lower end of the rear frame 72 is connected to the third arm 133 for the retracting arm 133 in the second edge sensor 43 due to the relative positional relationship between the drawer 70 and the belt module 110. The arm portion 133c is urged downward. Therefore, the arm portion 132b of the retracting elastic member 132 to which the retracting arm 133 is attached is tilted to the rear side against the spring force of the lower curved portion 132a, and the pressing portion provided on the retracting elastic member 132 132 c moves away from the edge contact member 128. As a result, the upper end portion of the edge contact member 128 is pulled by the tension spring 129, and the lower end portion contacts the edge end surface of the intermediate transfer belt 15, and can move following the edge end surface. It becomes like this.

  On the other hand, when the belt module 110 shown in FIGS. 11 and 6 is lowered, the relative positional relationship (vertical relationship) between the drawer 70 and the belt module 110 changes, and the lower end of the rear frame 72 is the second edge sensor. The third arm portion 133c of the 43 retracting arm 133 is not biased downward. This is because the position of the second edge sensor 43 with respect to the rear frame 72 is relatively lowered. Accordingly, the arm portion 132b of the retracting elastic member 132 to which the retracting arm 133 is attached swings to the front side by the spring force of the lower curved portion 132a, and the pressing portion 132c provided on the retracting elastic member 132. Presses the edge contact member 128 to the front side. As a result, the edge abutting member 128 has its upper end pressed against the spring force of the tension spring 129 and its lower end separated from the edge end surface of the intermediate transfer belt 15. In FIG. 11, the rear frame 72 and the third arm portion 133 c are slightly in contact with each other, but it is not necessary that both are in contact with each other.

  Thereafter, when the tension on the intermediate transfer belt 15 is released and the state shown in FIG. 9B is reached, the lower side of the intermediate transfer belt 15 hangs down below the lower end portion of the edge contact member 128. Become. In practice, as shown in FIG. 4, the tension applied to the intermediate transfer belt 15 via the tension roll 33 is released by operating the cam 37 after the intermediate transfer belt 15 is lifted obliquely upward. The Then, after the intermediate transfer belt 15 is replaced and a new intermediate transfer belt 15 is attached, the cam 37 is operated again, whereby the tension roll 33 moves and tension is applied to the intermediate transfer belt 15. Thereby, the downward sag of the intermediate transfer belt 15 is eliminated. At this time, since the lower end portion of the edge contact member 128 of the second edge sensor 43 is retracted to the rear side by the retracting elastic member 132, when the intermediate transfer belt 15 is tensioned, the edge contact member 128 is retracted. A situation in which the lower end portion of the contact member 128 is caught by the intermediate transfer belt 15 and pinched does not occur.

  Then, after the drawer 70 in which the belt module 110 is accommodated is again pushed into the main body 1 of the image forming apparatus and accommodated in the main body 1, the first lever 82 and the second lever 86 provided in the drawer 70 are moved to the arrows. Is operated in the opposite direction. As a result, the position of the belt module 110 in the drawer 70 rises, and the intermediate transfer belt 15 provided in the belt module 110 abuts on the photosensitive drum 11 provided in each of the image forming units 10Y, 10M, 10C, and 10K. . Then, the relative positional relationship between the drawer 70 and the belt module 110 returns to the state shown in FIG. That is, the lower end portion of the rear frame 72 is in a state of urging the third arm portion 133c of the retracting arm 133 of the second edge sensor 43 downward. Accordingly, the arm portion 132b of the retracting elastic member 132 to which the retracting arm 133 is attached is tilted to the rear side against the spring force of the lower bending portion 132a, and the pressing portion 132c provided on the retracting elastic member 132 is pressed. Moves away from the edge contact member 128. As a result, the upper end portion of the edge contact member 128 is pulled by the tension spring 129, and the lower end portion contacts the edge end surface of the intermediate transfer belt 15, and can move following the edge end surface. It becomes like this. That is, the edge position of the intermediate transfer belt 15 can be detected.

  As described above, in the present embodiment, the tension spring 129 provided in the second edge sensor 43, the retracting elastic member 132, the retracting arm 133, and the second side plate 112 provided in the belt module 110 are It functions as a contact / separation mechanism for contacting / separating the intermediate transfer belt 15 and the edge contact member 128 or a contact evacuation mechanism. Further, the second side plate 112 functions as another member that presses the retracting arm 133 as an arm member.

  Since the first edge sensor 42 is provided on the upper side of the intermediate transfer belt 15, even if the tension of the intermediate transfer belt 15 is released, the intermediate transfer belt 15 hardly sags at this position. Therefore, the first edge sensor 42 having a simpler mechanism than the second edge sensor 43 can be used.

  As described above, in the present embodiment, the drawer 70 that can be inserted into and removed from the main body 1 of the image forming apparatus is provided, and the belt module 110 including the intermediate transfer belt 15 is accommodated in the drawer 70. When the intermediate transfer belt 15 is replaced, the belt module 110 to which the intermediate transfer belt 15 is attached is separated from each photosensitive drum 11. That is, the belt module 110 can be moved up and down in the drawer 70. Then, in conjunction with the vertical movement of the belt module 110 in the drawer 70, a retracting unit attached to the rear frame 72 of the drawer 70 and the second edge sensor 43 attached to the second side plate 112 of the belt module 110. The contact state with the arm 133 is changed. As a result, when replacing the intermediate transfer belt 15, when the belt module 110 is separated from each photosensitive drum 11, the edge contact member 128 provided in the second edge sensor 43 is moved to the intermediate transfer belt 15. It can be retracted from the edge end face. For this reason, when the intermediate transfer belt 15 is replaced, the tension applied to the intermediate transfer belt 15 is released, and after the replaced new intermediate transfer belt 15 is slung over the various rolls, the tension is applied again. Even so, since the edge contact member 128 maintains the retracted state, interference between the intermediate transfer belt 15 and the second edge sensor 43, that is, the situation where the edge contact member 128 is caught on the intermediate transfer belt 15. It can be avoided. Therefore, it is possible to prevent the intermediate transfer belt 15 and the edge contact member 128 from being damaged.

  Further, after the replacement of the intermediate transfer belt 15 is completed, the belt module 110 to which the new intermediate transfer belt 15 is attached is accommodated in the drawer 70, and the drawer 70 is stored in the main body 1 of the image forming apparatus. After being stored in the main body 1, the belt module 110 is brought into contact with the photosensitive drums 11 again. At this time, in conjunction with the vertical movement of the belt module 110 in the drawer 70, the retraction attached to the rear frame 72 of the drawer 70 and the second edge sensor 43 attached to the second side plate 112 of the belt module 110. The contact state with the arm 133 changes in the opposite direction to that described above. Thereby, when the belt module 110 is brought into contact with each photosensitive drum 11, the edge contact member 128 provided in the second edge sensor 43 can be brought into contact with the edge end surface of the intermediate transfer belt 15. Therefore, the edge abutting member 128 can automatically abut on the edge end surface of the intermediate transfer belt 15 in conjunction with the attaching operation of the drawer 70 and the belt module 110. After this is done, it becomes possible to immediately detect the edge of the intermediate transfer belt 15.

  In the present embodiment, in the second edge sensor 43, the retracting arm 133 is attached to the retracting elastic member 132 that is used to move the lower end portion of the edge contact member 128 away from the intermediate transfer belt 15. Here, the retracting arm 133 extends rearward from the arm portion 132 b of the retracting elastic member 132, that is, in a direction away from the intermediate transfer belt 15. And it comprised so that the lower end part of the rear frame 72 (other members) in the drawer 70 might contact | abut to the 3rd arm part 133c which is the free end side of the arm 133 for a retraction | saving. As a result, the pressing force received by the retracting arm 133 from the rear frame 72 changes in conjunction with the vertical movement of the belt module 110 in the drawer 70. As a result, when the belt module 110 is moved downward in the drawer 70 in order to replace the intermediate transfer belt 15 (when the intermediate transfer belt 15 is separated from the photosensitive drums 11), the edge contact is caused. The lower end portion of the member 128 can be retracted from the intermediate transfer belt 15. On the other hand, when the belt module 110 is moved upward in the drawer 70 after the replacement of the intermediate transfer belt 15 is completed (when the intermediate transfer belt 15 is brought into contact with each photosensitive drum 11), the reverse operation is performed. Thus, the lower end portion of the edge contact member 128 can be brought into contact with the intermediate transfer belt 15.

  In this embodiment, the intermediate transfer belt 15 is described as an example of the endless belt. However, the present invention is not limited to this. For example, the endless belt is opposed to the photosensitive belt having the photosensitive layer or the photosensitive drum 11. The target may be a paper transport belt that carries and transports the paper P. In the present embodiment, the retracting arm 133 (more specifically, the third arm portion 133 c) provided in the second edge sensor 43 is in contact with the rear frame 72 provided in the drawer 70. As long as the relative positional relationship with the belt module 110 to which the second edge sensor 43 is attached is changed, for example, a member provided in the main body 1 of the image forming apparatus may be used.

1 is a diagram illustrating an overall configuration of an image forming apparatus to which the exemplary embodiment is applied. 2 is a perspective view illustrating a configuration of a drawer provided in a main body of the image forming apparatus. FIG. It is a figure for demonstrating the belt module accommodated in a drawer and a drawer. It is a figure for demonstrating the state which lifted the belt module from the drawer. FIG. 6 is a perspective view showing a second edge sensor as seen from the intermediate transfer belt side. FIG. 6 is a perspective view showing a second edge sensor as seen from the reverse side of the intermediate transfer belt. It is a perspective view which shows the 2nd edge sensor attached to the 2nd side plate. FIG. 10 is a diagram illustrating a state in which the drawer is pulled out from the main body of the image forming apparatus and the belt module is lifted from the pulled out drawer. (a) is a diagram showing a state in which the intermediate transfer belt is stretched and tensioned, and (b) is a diagram showing a state in which the tension on the intermediate transfer belt is released. FIG. 6 is a diagram for explaining a relative positional relationship between a drawer and a belt module (second edge sensor) when a tension is applied to the intermediate transfer belt. FIG. 6 is a diagram for explaining a positional relationship between a drawer and a belt module (second edge sensor) when tension is released with respect to the intermediate transfer belt.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Main body, 10 (10Y, 10M, 10C, 10K) ... Image forming unit, 11 ... Photosensitive drum, 20 ... Secondary transfer part, 21 ... Secondary transfer conveyance belt, 22 ... Drive roll, 23 ... Idle roll, 25 ... backup roll, 31 ... drive roll, 33 ... tension roll, 36 ... arm, 37 ... cam, 42 ... first edge sensor, 43 ... second edge sensor, 70 ... drawer, 100 ... secondary transfer unit, 110 ... belt module

Claims (10)

A drawer arranged so as to be able to be pulled out from the apparatus body;
A belt module that has an endless belt that is rotatably supported on a plurality of rolls, and is disposed so as to be accommodated in the drawer;
An edge sensor that is attached to the belt module and detects an edge position of the endless belt using an edge contact member that contacts the edge of the endless belt;
A moving mechanism for moving the belt module in the drawer;
An image forming apparatus comprising: a contact / separation mechanism that contacts and separates the edge contact member of the edge sensor from the endless belt in conjunction with the operation of the moving mechanism. Further comprising an image carrier for carrying an image,
The moving mechanism moves the belt module between a first position where the endless belt contacts the image carrier and a second position where the endless belt is separated from the image carrier,
The contact / separation mechanism causes the edge contact member to contact the endless belt when the belt module is in the first position, and from the endless belt when the belt module is in the second position. The image forming apparatus according to claim 1, wherein the edge contact member is separated.   The image forming apparatus according to claim 2, wherein the drawer is drawable from the apparatus main body when the belt module is in the second position.   The image forming apparatus according to claim 1, wherein the tension applied to the endless belt is released by moving at least one of the plurality of rolls that stretch the endless belt.   The image forming apparatus according to claim 4, wherein the edge sensor is disposed below the endless belt. A drawer arranged so as to be able to be pulled out from the apparatus body;
A belt module that has an endless belt that is rotatably supported on a plurality of rolls, and is disposed so as to be accommodated in the drawer;
An edge sensor that is attached to the belt module and detects an edge position of the endless belt using an edge contact member that contacts the edge of the endless belt;
The edge abutting member is retracted from the endless belt in conjunction with an operation for pulling out the drawer housed in the apparatus body from the apparatus body and exposing the belt module housed in the drawer to the outside. The edge abutted against the endless belt in conjunction with the operation for storing the drawer pulled out from the apparatus main body in the apparatus main body and setting the belt module accommodated in the drawer in the apparatus main body. An image forming apparatus including a retracting mechanism for contacting a member . Further comprising an image carrier for carrying an image,
The belt module is moved to a position where the endless belt contacts the image carrier when the drawer is set in the apparatus body, and the endless belt is moved from the image carrier when the drawer is pulled out from the apparatus body. The image forming apparatus according to claim 6, wherein the belt is moved to a position where the belt is separated.   The image forming apparatus according to claim 6, wherein the belt module is supported by the drawer so as to be movable up and down.   The image forming apparatus according to claim 6, wherein the belt module is swingably supported by the drawer. The endless belt is an image carrier that carries and conveys an image;
Below the endless belt, further includes a transfer portion for transferring an image on the endless belt to a recording material,
The image forming apparatus according to claim 6, wherein the edge contact member of the edge sensor contacts an edge of the endless belt in the vicinity of the transfer portion.

Images