JP2023061853A - Image forming apparatus - Google Patents

Abstract

To allow smooth retraction of a body-side coupling when retracting the body-side coupling by a release member.SOLUTION: A release member 40 includes a contact part 41a that, with the release member 40 moved in a drawing direction of a unit 10 from an apparatus body 110, is brought into contact with a body-side coupling 50 and retracts the body-side coupling 50 from a unit-side coupling 36. The contact part is in contact with the body-side coupling 50 at a third position P3 in the circumferential direction of the body-side coupling 50 when seen along the direction of the axis of rotation of the unit-side coupling 36, in an area of the body-side coupling 50 where it can be in contact with the release member 40 in the direction of the axis of rotation of the body-side coupling 50, and preferably regulates the direction of fall of the body-side coupling 50 caused by the release member 40 to be a tangential direction of a meshing part H of a gear part 52 and a former stage gear 55 of the body-side coupling 50 or a direction in which the interval between the gears is increased.SELECTED DRAWING: Figure 13

Description

The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine having a plurality of these functions, using an electrophotographic system or an electrostatic recording system.

2. Description of the Related Art Conventionally, as an image forming apparatus using an electrophotographic method or the like, a toner image formed on an image carrier is directly transferred onto a recording material that is carried and conveyed on a recording material carrier, or an intermediate transfer device. In some cases, the primary transfer is performed on the body, and then the secondary transfer is performed on the recording material. An endless belt is often used as a recording material carrier or an intermediate transfer member. An intermediate transfer type image forming apparatus having an intermediate transfer belt, which is an intermediate transfer member formed of an endless belt, will be mainly described below as an example.

In such an image forming apparatus, problems such as breakage of the intermediate transfer belt may occur due to deterioration of the intermediate transfer belt over time or fatigue due to long-term driving of the intermediate transfer belt. are exchanged on a regular basis. A detachable unit (intermediate transfer belt unit) including the intermediate transfer belt is attached to the main body of the image forming apparatus (hereinafter also simply referred to as "apparatus main body") so that replacement and maintenance of the intermediate transfer belt can be easily performed. It may be detachable.

The detachable unit is generally configured to be pulled out (pulled out) in a substantially horizontal direction with respect to the apparatus main body. In order to pull out the removable unit horizontally with respect to the apparatus main body, it is conceivable that the removable unit is pulled out in a direction substantially perpendicular to the plane of the frame of the apparatus main body. However, in this case, a large hole is formed in the frame of the apparatus main body, which is undesirable from the viewpoint of the rigidity of the apparatus main body. Therefore, the detachable unit is sometimes configured to be pulled out in a direction substantially parallel to the plane of the frame of the apparatus main body. In this case, when the detachable unit is pulled out from the apparatus main body, the detachable unit is pulled out in a direction substantially orthogonal to the drive shaft, so a configuration for releasing the engaging portion such as the coupling is required. As such a configuration, it has been proposed to provide a release member (coupling shutter) for retracting the coupling at the grip portion of the detachable unit (Patent Document 1).

JP 2016-126152 A

Drive input to the detachable unit is generally performed using drive transmission through a coupling. Further, in order to increase the rigidity in the rotational direction, it is desirable that the drive transmission gear coaxial with the apparatus main body side coupling (main body side coupling) is formed integrally with the main body side coupling. In addition, misalignment between the detachable unit side coupling (unit side coupling) and the main body side coupling may affect the image. For this reason, the body-side coupling holds the tip of the detachable unit side in the rotational axis direction in a free state so that the position is determined when the body-side coupling and the unit-side coupling are engaged. desirable.

However, in such a configuration, conventionally, when the detachable unit is pulled out from the apparatus main body, if the release member is moved in a direction substantially orthogonal to the drive input direction, the main body side coupling is pulled out of the detachable unit from the apparatus main body. I was starting to fall over. At that time, depending on the arrangement of the drive gear train on the device main body side, the distance between the gears formed integrally with the main body side coupling and the gears meshing with it becomes narrow, resulting in reduced frictional resistance. There was a possibility that the body side coupling could not be retracted due to the increase. In some cases, the tip of the gear hits the bottom of the gear, which may damage the gear and cause banding (periodic image density unevenness such as horizontal streaks) to occur.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to enable smooth retraction of the body-side coupling when the body-side coupling is retracted by a releasing member.

The above object is achieved by an image forming apparatus according to the present invention. In summary, the present invention comprises a drive source, a front gear that rotates when a drive force is transmitted from the drive source, and a gear portion that meshes with the front gear, and rotates when the drive force is transmitted from the drive source. an apparatus main body comprising a main body side coupling movable in a rotational axis direction; an endless belt; a driving roller for driving the belt; and a main body side cup engaged with the main body side coupling. a unit-side coupling that receives driving force from a ring and rotates coaxially with the body-side coupling to transmit the driving force to the driving roller; a unit that is moved in an inserting direction with respect to the apparatus main body and an extracting direction from the apparatus main body along the direction to be attached to and detached from the apparatus main body; a releasing member provided movably with respect to the unit along the direction of the pull-out, the releasing member releasing the engagement between the body-side coupling and the unit-side coupling; It includes a contact portion that abuts on the main body side coupling and retracts the main body side coupling from the unit side coupling when moved, and when viewed along the rotation axis direction of the unit side coupling, In the image forming apparatus in which the meshing portion between the gear portion and the front gear is positioned downstream in the pull-out direction with respect to the rotation center of the main body side coupling, in the rotation axis direction of the main body side coupling, A first position P1 and a second position P1 in the circumferential direction of the body side coupling when viewed along the rotational axis direction of the unit side coupling in the region of the body side coupling that can come into contact with the releasing member. P2 and third position P3, wherein the first position P1 is such that the tangential direction of the body side coupling at the first position P1 is substantially orthogonal to the pull-out direction and the rotation center of the body side coupling. , and the second position P2 is such that the tangential direction of the body-side coupling at the second position P2 is substantially parallel to the pull-out direction, and the body side The third position P3 is a position on the meshing portion side with respect to the rotation center of the coupling, and the third position P3 is a region between the first position P1 and the second position P2 having a shorter distance in the circumferential direction. , the contact portion is located at the third position P3 The image forming apparatus is characterized in that it abuts on the body-side coupling at a .

According to the present invention, when the body side coupling is retracted by the release member, the body side coupling can be smoothly retracted.

2 is a vertical cross-sectional view of the image forming apparatus; FIG. 3 is a perspective view of an intermediate transfer belt unit; FIG. FIG. 4 is a side view of a gear train of the main drive unit; 4 is a horizontal cross-sectional view of the main drive unit; FIG. 2 is a schematic perspective view of a body frame and an intermediate transfer belt unit of the image forming apparatus; FIG. 2 is a perspective view showing the vicinity of a grip portion of the intermediate transfer belt unit attached to the apparatus main body; FIG. 3 is a horizontal cross-sectional view showing the vicinity of a handle portion of the intermediate transfer belt unit attached to the apparatus main body; FIG. It is a perspective view of a releasing member. 3 is a perspective view showing the state of the intermediate transfer belt unit attached to the apparatus main body and the main body side coupling; FIG. 3 is a horizontal sectional view showing the state of the intermediate transfer belt unit attached to the apparatus main body and the main body side coupling; FIG. FIG. 10 is a perspective view showing the state of the intermediate transfer belt unit and the body-side coupling when the releasing member is pulled; FIG. 10 is a horizontal cross-sectional view showing the state of the intermediate transfer belt unit and the body-side coupling when the releasing member is pulled; FIG. 4 is a schematic diagram showing the relationship between the gear train of the main drive unit and the release member; FIG. 5 is a schematic diagram for explaining a contact position of the releasing member with respect to the body-side coupling; FIG. 10 is a schematic diagram showing another example of the release member; 4 is a perspective view showing a state of the intermediate transfer belt unit and main body side coupling when inserting the intermediate transfer belt unit into the apparatus main body; FIG. 4 is a horizontal cross-sectional view showing the state of the intermediate transfer belt unit and the body-side coupling when inserting the intermediate transfer belt unit into the apparatus body; FIG.

Hereinafter, the image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

[Example 1]
1. 1. Overall Configuration and Operation of Image Forming Apparatus FIG. 1 is a vertical cross-sectional view of an image forming apparatus 100 of this embodiment (a cross section substantially orthogonal to the rotation axis direction of a photosensitive drum 1 and a drive roller 12, which will be described later). The image forming apparatus 100 of this embodiment is a tandem-type laser beam printer that employs an intermediate transfer method and is capable of forming a full-color image using an electrophotographic method.

Image forming apparatus 100 includes first, second, and second image forming units (stations) that form yellow (Y), magenta (M), cyan (C), and black (K) images, respectively. 3. It has fourth image forming units PY, PM, PC, and PK. In this embodiment, the configurations and operations of the image forming units PY, PM, PC, and PK are substantially the same except that the colors of toner used are different. For elements having the same or corresponding functions or configurations in the image forming units PY, PM, PC, and PK, the suffixes Y, M, C, and K are omitted from the symbols indicating that they are elements for one of the colors. may be described in a comprehensive manner.

The image forming apparatus 100 has a photosensitive drum 1 which is a drum-shaped (cylindrical) electrophotographic photosensitive member (photosensitive member) as an image carrier. The photosensitive drum 1 is rotated clockwise in FIG. The following units are arranged around the photosensitive drum 1 . First, a charging roller 2, which is a roller-shaped charging member, is arranged as charging means. Also, an exposure device (laser scanner device) 3 is arranged as exposure means. In this embodiment, the exposure device 3 is configured as one unit that exposes each of the photosensitive drums 1Y, 1M, 1C, and 1K. Further, a developing device 4 is arranged as developing means. A primary transfer roller 6 is also arranged. Further, a drum cleaning device 5 is arranged as a photoreceptor cleaning means.

In this embodiment, a photosensitive drum 1, a charging roller 2, an exposure device 3, a developing device 4, a primary transfer roller 6, a drum cleaning device 5, etc. used for forming an image of each color are used to form an image of each color. is configured. In each image forming portion P, the photosensitive drum 1 and the charging roller 2, the developing device 4, and the drum cleaning device 5 acting on the photosensitive drum 1 as process means are integrally connected to the apparatus main body 110 of the image forming apparatus 100. A detachable process cartridge 9 is constructed by

The image forming apparatus 100 also has an intermediate transfer belt unit 10, which is a belt conveying device as a detachable unit, arranged so as to face each of the photosensitive drums 1Y, 1M, 1C, and 1K. The intermediate transfer belt unit 10 is detachable from the apparatus main body 110 of the image forming apparatus 100 . The intermediate transfer belt unit 10 has an intermediate transfer belt 11 configured as an endless belt as an intermediate transfer member so as to face each of the photosensitive drums 1Y, 1M, 1C, and 1K. The intermediate transfer belt 11 is stretched around a driving roller 12, a regulating roller 13, and a tension roller 14 as a plurality of stretching rollers (stretching members). The intermediate transfer belt 11 rotates (circulates) in the counterclockwise direction in FIG. 1 when the drive roller 12 is rotationally driven. The tension roller 14 is urged from the inner peripheral surface side toward the outer peripheral surface side of the intermediate transfer belt 11 as indicated by an arrow T in FIG. is given. Primary transfer rollers 6Y, 6M, 6C, which are roller-shaped primary transfer members as the above-described primary transfer means, are provided on the inner peripheral surface side of the intermediate transfer belt 11 corresponding to the respective photosensitive drums 1Y, 1M, 1C, 1K. , 6K are arranged. The primary transfer roller 6 is urged (pressed) toward the photosensitive drum 1 with a predetermined pressure, contacts the photosensitive drum 1 via the intermediate transfer belt 11, and the intermediate transfer belt 11 and the photosensitive drum 1 are brought into contact with each other. A primary transfer portion (primary transfer nip portion) N1 is formed. Of the plurality of tension rollers, the tension rollers other than the drive roller 12 and the primary transfer rollers 6Y, 6M, 6C, and 6K are driven to rotate as the intermediate transfer belt 11 rotates.

Further, a secondary transfer roller 16, which is a roller-shaped secondary transfer member as a secondary transfer means, is arranged at a position facing the drive roller 12 on the outer peripheral surface side of the intermediate transfer belt 11 . The secondary transfer roller 16 is urged (pressed) toward the driving roller 12 with a predetermined pressure and comes into contact with the driving roller 12 via the intermediate transfer belt 11 so that the intermediate transfer belt 11 and the secondary transfer roller 16 are in contact with each other. forms a secondary transfer portion (secondary transfer nip portion) N2 with which the . A belt cleaning device 15 as intermediate transfer body cleaning means is arranged at a position facing the tension roller 14 on the outer peripheral surface side of the intermediate transfer belt 11 . The belt cleaning device 15 is detachable from the apparatus main body 110 of the image forming apparatus 100 as an intermediate transfer belt unit 10 integrally with the intermediate transfer belt 11 and the like.

In addition, the image forming apparatus 100 is provided with a feeding/conveying device 20 that supplies the recording material S to the secondary transfer portion N2, a fixing device 17 that fixes the toner image on the recording material S, and the like.

During image formation, the surface of the photosensitive drum 1, which rotates clockwise in FIG. The charged surface of the photosensitive drum 1 is scanned and exposed by the exposure device 3 according to the image information of the color component corresponding to each image forming portion P, and an electrostatic latent image is formed on the photosensitive drum 1 according to the image information. (electrostatic image) is formed. The electrostatic latent image formed on the photosensitive drum 1 is developed (visualized) by supplying toner as developer by the developing device 4 to form a toner image on the photosensitive drum 1 . In this embodiment, the charging polarity of the photosensitive drum 1 (in this embodiment, (Negative polarity) and toner charged to the same polarity adheres (reversal development method). In this embodiment, the normal charge polarity of the toner, which is the charge polarity of the toner during development, is negative.

The toner image formed on the photosensitive drum 1 is transferred (primary transfer) onto the intermediate transfer belt 11 rotating counterclockwise in FIG. 1 by the action of the primary transfer roller 6 at the primary transfer portion N1. be done. At the time of primary transfer, a primary transfer power source (not shown) as a voltage applying means supplies a primary transfer roller 6 with a DC voltage having a polarity opposite to the normal charging polarity of the toner (positive polarity in this embodiment). A transfer voltage (primary transfer bias) is applied. For example, when forming a full-color image, yellow, magenta, cyan, and black toner images formed on the respective photosensitive drums 1Y, 1M, 1C, and 1K are sequentially superimposed on the intermediate transfer belt 11. be transcribed.

The toner image formed on the intermediate transfer belt 11 is transferred to a recording sheet which is sandwiched and conveyed between the intermediate transfer belt 11 and the secondary transfer roller 16 by the action of the secondary transfer roller 16 at the secondary transfer portion N2. is transferred (secondary transfer) onto the recording material S such as the At the time of secondary transfer, the secondary transfer roller 16 is supplied with a DC voltage having a polarity opposite to the normal charging polarity of the toner (positive polarity in this embodiment) from a secondary transfer power supply (not shown) as voltage applying means. A secondary transfer voltage (secondary transfer bias) is applied. For example, when a full-color image is formed, a multiple toner image formed on the intermediate transfer belt 11 in a state in which toners of four colors are superimposed is conveyed by the intermediate transfer belt 11 and moved to the secondary transfer portion N2. They are collectively transferred onto the recording material S at the next transfer portion N2. A recording material (transfer material, recording medium, sheet) S is accommodated in a recording material cassette 21 or the like as a recording material accommodating portion. The recording material S is sent out one by one from the recording material cassette 21 or the like by a feeding roller 22 or the like, and then conveyed to a registration roller pair 23 . Then, the recording material S is conveyed to the secondary transfer portion N2 in timing with the toner image on the intermediate transfer belt 11 by the pair of registration rollers 23 . A feeding/conveying device 20 is configured by the recording material cassette 21, the feeding roller 22, and the like.

The recording material S onto which the toner image has been transferred is conveyed to the fixing device 17 . The fixing device 17 has a fixing roller 17a having a heat source and a pressure roller 17b that presses against the fixing roller 17a. The fixing device 17 heats and presses the recording material S bearing the unfixed toner image at the fixing nip portion between the fixing roller 17a and the pressure roller 17b. Thereby, the fixing device 17 fixes the unfixed toner image on the surface of the recording material S to the surface of the recording material S. As shown in FIG. After that, the recording material S is discharged (output) to the outside of the apparatus main body 110 of the image forming apparatus 100 .

On the other hand, adherents such as toner remaining on the photosensitive drum 1 after the primary transfer (primary transfer residual toner) are removed from the photosensitive drum 1 by the drum cleaning device 5 and collected. The drum cleaning device 5 scrapes and removes adherents such as toner from the surface of the rotating photosensitive drum 1 with a cleaning blade as a cleaning member. Further, adherents such as toner remaining on the intermediate transfer belt 11 after the secondary transfer (secondary transfer residual toner) are removed from the intermediate transfer belt 11 by the belt cleaning device 15 and collected. The belt cleaning device 15 scrapes and removes toner from the surface of the rotating intermediate transfer belt 11 with a cleaning blade as a cleaning member. Adhered matter such as toner removed by the drum cleaning device 5 and the belt cleaning device 15 as described above passes through a collected toner conveying path (not shown) and is conveyed to a collected toner container (not shown). is recovered.

2. Intermediate Transfer Belt Unit Next, the intermediate transfer belt unit (hereinafter also simply referred to as "unit") 10 as a detachable unit in this embodiment will be described. Regarding the image forming apparatus 100 and its elements, the front side of the paper surface of FIG. do. The depth direction connecting the front side and the rear side is substantially parallel to the rotation axis direction of the photosensitive drum 1 and the rotation axis direction of the tension rollers 12, 13, and 14 on which the intermediate transfer belt 11 is stretched. In addition, the vertical direction refers to the vertical direction in the direction of gravity (vertical direction), but does not mean just above or below, but includes above and below the horizontal plane passing through the element or position of interest. . Regarding each image forming portion P and its elements, upstream and downstream refer to the surface (primary transfer surface) of the intermediate transfer belt 11 stretched between the tension roller 14 and the regulating roller 13 unless otherwise specified. ) means upstream and downstream in the direction of movement.

FIG. 2 is a perspective view of the unit 10 in this embodiment as seen from the rear right side. The unit 10 is detachable from the apparatus main body 110 of the image forming apparatus 100 . In this embodiment, a unit 10 as a detachable unit in which a belt cleaning device 15 and a belt conveying section 10a including an intermediate transfer belt 11 and tension rollers 12, 13, and 14 are integrated is detachable from an apparatus main body 110. It is possible. In addition, in the unit 10, the belt cleaning device 15 may be detachable from the belt conveying portion 10a. The unit 10 is removed from the apparatus body 110 for maintenance such as inspection and repair of the intermediate transfer belt 11 and the belt cleaning device 15, or for replacement.

The unit 10 has an intermediate transfer belt 11 (part of the front side is cut off in FIG. 2). The unit 10 also has a drive roller 12, a regulation roller 13, and a tension roller 14 as a plurality of tension rollers around which the intermediate transfer belt 11 is wound. These drive roller 12 , regulation roller 13 and tension roller 14 are attached to a unit frame 31 as a support member of the unit 10 .

The drive roller 12 is rotatably supported by drive roller bearing members 32 (only the front side is shown in FIG. 2) at both ends in the direction of the rotation axis (longitudinal direction). This drive roller bearing member 32 is attached to the unit frame 31 . The driving roller 12 is rotated by a driving force transmitted from a motor 80 (FIG. 3) as a driving source provided in the apparatus main body 110 as will be described later in detail. The driving roller 12 is rotationally driven to convey the intermediate transfer belt 11 . The surface of the drive roller 12 is formed of a rubber layer having a high coefficient of friction so as to convey the intermediate transfer belt 11 without slipping. Further, the drive roller 12 is positioned on the downstream side (head side) in the drawing direction of the unit 10 from the apparatus main body 110 (hereinafter also simply referred to as the "drawing direction") from the apparatus main body 110, which will be described later in detail, and is the most downstream photosensitive drum 1K. is located in close proximity to

The regulating roller 13 is rotatably supported by regulating roller bearing members 33 (only the front side is shown in FIG. 2) at both ends in the rotation axis direction (longitudinal direction). This regulation roller bearing member 33 is attached to the unit frame 31 . The regulation roller 13 is driven to rotate as the intermediate transfer belt 11 rotates.

The tension roller 14 is rotatably supported by tension roller bearing members 34 (only the front side is shown in FIG. 2) at both ends in the direction of the rotation axis (longitudinal direction). The tension roller bearing member 34 is attached to the unit frame 31 so as to be movable (slidable) along the direction in which the intermediate transfer belt 11 is pressed from the inner peripheral surface to the outer peripheral surface. The tension roller bearing members 34 at both ends in the rotation axis direction of the tension roller 14 are urged by the compression force of tension springs (not shown) which are urging members as urging means. be. The tension roller bearing member 34 is moved (slid) from the inner peripheral surface side of the intermediate transfer belt 11 to the outer peripheral surface side along the biasing direction of the tension spring. As a result, the tension roller 14 urges the intermediate transfer belt 11 from the inner peripheral surface side toward the outer peripheral surface side of the intermediate transfer belt 11 as indicated by the arrow T in FIG. to give Further, the tension roller 14 is positioned on the downstream side (head side) of the insertion direction of the unit 10 with respect to the apparatus main body 110 (hereinafter also simply referred to as the "insertion direction") with respect to the apparatus main body 110, which will be described later in detail, and is positioned on the most upstream photosensitive drum 1Y. are placed in close proximity. The tension roller 14 is driven to rotate as the intermediate transfer belt 11 rotates.

The primary transfer rollers 6Y, 6M, 6C, and 6K are attached to the unit frame 41 so as to be swingable (rotatable) or linearly movable at both ends in the longitudinal direction (rotational axis direction). It is rotatably supported by a primary transfer bearing member (not shown). The primary transfer roller 6 is pressed against the photosensitive drum 1 as described above, and is driven to rotate as the intermediate transfer belt 11 rotates.

A belt cleaning device 15 is provided at a position facing the tension roller 14 of the unit 10 . Further, grip portions 35 are provided at both ends of the driving roller 12 and the regulating roller 13 in the direction of the rotation axis and used for operations such as attaching and detaching the unit 10 to and from the apparatus main body 110 . . Each grip portion 35 is provided so as to protrude in a direction in which the unit 10 is removed from the apparatus main body 110 .

3. Main drive unit Next, a main drive unit 120 provided in the apparatus main body 110 for driving the image forming section P (particularly, the most downstream image forming section PK for black color) and the unit 10 in this embodiment. A gear train will be explained. FIG. 3 is a side view of the gear train of the main drive unit 120 according to this embodiment as seen from the front side along the depth direction (the rotation axis direction of the drive roller 12). Hereinafter, the photosensitive drum 1K for black color is also simply referred to as "photosensitive drum 1K".

In this embodiment, the unit 10 and the photosensitive drum 1K are driven by one (common) motor 80 as a drive source. The driving force from the motor 80 is transmitted from the motor gear 53 fixed to the output shaft of the motor 80 to the gear portion 52 of the body side coupling 50 through the first idler gear 54 and the second idler gear 55 in sequence. As a result, the main body side coupling 50 rotates, and drive is transmitted from the coupling portion 51 of the main body side coupling 50 to the unit side coupling 36 described later. On the other hand, the driving force from the motor 80 is transmitted from the motor gear 53 to the gear portion 58 of the body side drum coupling 57 via the third idler gear 56 . As a result, the main body side drum coupling 57 rotates, and the drive is transmitted from the coupling portion 59 of the main body side drum coupling 57 to the drum coupling (not shown) fixed to the photosensitive drum 1 .

It is desirable that the gear portion 58 of the body side drum coupling 57 has a small module and a large number of teeth in order to reduce the influence of gear 1 tooth on the image. Therefore, it is effective to increase the outer diameter of the body-side drum coupling 57 as much as possible so that the space can be secured. It is difficult to greatly change the positional relationship between the photosensitive drum 1K and the driving roller 12 of the unit 10 in a vertical cross section (a cross section substantially perpendicular to the rotation axis direction of the photosensitive drum 1K and the driving roller 12). For example, from the viewpoint of improving the productivity of the image forming apparatus 100 by shortening the conveying distance of the intermediate transfer belt 11 from the most downstream primary transfer portion N1K to the secondary transfer portion N2, the degree of freedom is not large. Therefore, the gear train for transmitting drive to the body side coupling 50 for driving the unit 10 is configured as follows so as to avoid the gear portion 58 of the body side drum coupling 57 . That is, the meshing portion between the gear portion of the body side coupling 50 and the gear (previous gear) that meshes with the gear portion of the body side coupling 50 is positioned on the opposite side of the body side drum coupling 57 with respect to the rotation axis of the body side coupling 50 . It will be. Specifically, in the configuration of the present embodiment, the gear portion 52 of the body side coupling 50 and the second idler gear as the preceding gear are arranged downstream of the rotation axis of the body side coupling 50 in the direction in which the unit 10 is pulled out. (Hereinafter, it is also simply referred to as an "idler gear.") A meshing portion H with 55 is positioned. The gear portion of the main body side drum coupling 57 and the gear portion of the main body side coupling 50 can be made different in level in the rotation axis direction. As a result, it is considered possible to position the meshing portion between the gear portion of the body-side coupling 50 and the gear meshing therewith on the side of the body-side drum coupling 57 with respect to the rotational axis of the body-side coupling 50 . . However, in that case, the size of the device main body 110 becomes large, which is not desirable from the viewpoint of miniaturization of the device.

FIG. 4 is a horizontal cross-sectional view of the main drive unit 120 passing through the rotation axis of the body-side coupling 50 (a cross section substantially parallel to the rotation axis of the photosensitive drum 1K and the drive roller 12). A first drive frame 81 and a second drive frame 82 are attached to the rear side plate 63 of the device main body 110 for supporting a drive train for transmitting drive to the main body side coupling 50 . The body-side coupling 50 is supported by a first drive frame 81 and a spring holder 91 attached to the second drive frame 82 . The body-side coupling 50 is rotatable around a rotation axis substantially perpendicular to the plane of the rear plate 63 and is movable (slidable) in the direction of the rotation axis. Further, a gap B is formed between the body-side coupling 50 and the first drive frame 81 . As a result, the main body side coupling 50 is configured to swing around the position where the spring holder 91 supports the gear portion 52 of the main body side coupling 50 as a fulcrum. That is, the body-side coupling 50 is supported so that the tip on the side of the unit 10 (coupling section 51 side) in the direction of the rotation axis can swing with respect to the axis of rotation. In this manner, the body-side coupling 50 is held by the first drive frame 81 and the spring holder 91 with the free end on the unit 10 side in the rotation axis direction. Between the body-side coupling 50 and the spring holder 91, a coupling spring 92 is attached in a compressed state. The coupling spring 92 urges the body-side coupling 50 toward the front side, that is, the unit 10 side along a direction substantially orthogonal to the plane of the rear side plate 63 .

The main body side coupling 50 is configured by integrating a front side coupling portion 51 and a rear side gear portion 52, and the coupling portion 51 has a substantially cylindrical shape. The outer diameter of the end portion of the coupling portion 51 on the side of the spring holder 91 is made larger than the outer diameter of the coupling portion 51, and a gear portion 52 having a gear on the outer peripheral surface is formed. The coupling portion 51 has an engaging portion 51 a that engages with the unit-side coupling 36 at the front end portion of the coupling portion 51 in the rotational axis direction. Further, the coupling portion 51 has a tapered surface 51b formed at the front end portion of the coupling portion 51 in the rotation axis direction so as to increase in diameter as it becomes farther from the unit 10 side in the rotation axis direction.

In this embodiment, the image forming units PY, PM, and PC for yellow, magenta, and cyan are provided with drive sources ( In this embodiment, it is driven by one drive source).

4. Attachment and Detachment of Intermediate Transfer Belt Unit Next, attachment and detachment of the unit 10 to and from the apparatus main body 110 in this embodiment will be described.

FIG. 5 is a perspective view schematically showing a body frame (frame body) 60 provided in the device body 110 and the unit 10 attached to the device body 110. As shown in FIG. The body frame 60 includes a bottom plate 61, a front side plate 62 and a rear side plate 63 erected facing the bottom plate 61, a side frame 64 connecting the front side plate 62 and the rear side plate 63 on the left side of the device body 110, is configured with Further, as shown in FIG. 1, an opening/closing door 65 that opens and closes the right side of the apparatus main body 110 so as to divide the conveying path of the recording material S from the feeding/conveying device 20 to the fixing device 17 is pivoted about the pivot shaft 18. It is attached to the front side plate 62 and the rear side plate 63 so as to be rotatable as. The unit 10 can be removed from the apparatus main body 110 by opening the opening/closing door 65 and pulling out the unit 10 to the right side of the apparatus main body 110 in the direction of arrow A in FIG. Conversely, the unit 10 can be attached to the device main body 110 by inserting the unit 10 into the left side of the device main body 110 in the direction opposite to the arrow A direction in FIG.

FIG. 6 is a perspective view showing the vicinity of the grip portion 35 on the rear side of the unit 10 when the unit 10 is attached to the apparatus main body 110. As shown in FIG. 7 is a horizontal cross-sectional view of the vicinity of the handle portion 35 on the rear side of the unit 10 when the unit 10 is attached to the apparatus main body 110 (a cross section substantially parallel to the rotation axis direction of the photosensitive drum 1K and the driving roller 12). ).

As shown in FIG. 6, the front side plate 62 and the rear side plate 63 are each provided with a rail 70 (only the rail 70 of the rear side plate 63 is shown). The unit 10 is guided by the rails 70 and is moved (slid) substantially parallel to the planes of the front side plate 62 and the rear side plate 63, and in this embodiment, substantially horizontally. It is detachable.

As shown in FIG. 7, a unit-side coupling 36 is attached to the drive shaft (rotational shaft) 12a of the drive roller 12 at the rear end of the drive roller 12 in the rotation axis direction. By engaging the unit-side coupling 36 and the body-side coupling 50 with the unit 10 positioned on the rail 70, the body-side coupling 50 is fixed to swing. Thereby, the unit-side coupling 36 is rotatable around a rotation axis substantially orthogonal to the plane of the rear side plate 63 in a state where the unit 10 is attached to the apparatus main body 110 . The unit-side coupling 36 has an engaging portion 36 a ( FIG. 11 ) that engages with the body-side coupling 50 provided on the device body 110 at its rear end in the rotation axis direction. The unit-side coupling 36 rotates when a driving force is transmitted from the body-side coupling 50, and inputs the driving force to the driving roller 12 as a driven member. In this manner, the position of the main body side coupling 50, which is held with its tip free, is determined when the main body side coupling 50 and the unit side coupling 36 are engaged with each other. This suppresses misalignment between the unit-side coupling 36 and the body-side coupling 50 .

As shown in FIGS. 6 and 7, the unit 10 includes a release member (coupling shutter) 40 that retracts the body-side coupling 50 from the unit 10 side to enable attachment/detachment of the unit 10 to/from the apparatus body 110. is provided. With the unit 10 attached to the apparatus main body 110, the release member 40 is arranged between the main body side coupling 50 and the unit side coupling 36 so as to enable engagement between these couplings. ing.

FIG. 8 is a perspective view of the release member 40 as viewed from the rear right side of the apparatus main body 110, with the side of the release member 40 on the main body side coupling 50 side. As shown in FIG. 8, the releasing member 40 is a plate-like or rod-like member that is elongated in one direction as a whole. A main portion 43 is provided between the portion 41 and the operation portion 42 . At a side portion of the releasing portion 41 on the main portion 43 side in the longitudinal direction of the releasing member 40, there is provided a first contacting surface 51b of the main body side coupling 50 when the unit 10 is pulled out from the apparatus main body 110, as will be described later in detail. A contact portion 41a is provided. Further, on the side portion of the releasing portion 41 opposite to the main portion 43 in the longitudinal direction of the releasing member 40, a tapered surface of the main body side coupling 50 is formed when the unit 10 is inserted into the apparatus main body 110, as will be described later in detail. A second contact portion 41b is provided to contact with 51b. The releasing portion 41 is connected to the main portion 43 by a connecting portion 44 , and an operating portion 42 is formed at the end of the main portion 43 opposite to the connecting portion 44 . The releasing member 40 is constructed integrally as a whole.

The release member 40 is attached to the handle portion 35 on the rear side of the unit 10 . The release member 40 is movable (slidable) on the handle portion 35 in the direction in which the unit 10 is attached to and detached from the apparatus main body 110 (substantially horizontal direction in this embodiment). In other words, the release member 40 is arranged so that its longitudinal direction is along the direction in which the unit 10 is attached to and detached from the device main body 110 (substantially horizontal direction in this embodiment), that is, along the direction substantially perpendicular to the rotation axis of the unit-side coupling 36 . and can be slid in the same direction. In this manner, the release member 40 can be operated at the handle portion 35 that is gripped when the unit 10 is attached to or detached from the apparatus main body 110, and can be moved along the movement direction of the unit 10 with respect to the apparatus main body 110. is provided in The release portion 41 of the release member 40 is arranged inside the device main body 110 with respect to the rotation axis of the unit side coupling 36, and the operation portion 42 and the main portion 43 are arranged outside the device main body 110 with respect to the rotation axis. , the connecting portion 44 is arranged to straddle the rotation axis. Thus, the release member 40 extends from the vicinity of the unit side coupling 36 to the vicinity of the end of the handle portion 35 . A hole portion 45 formed by the releasing portion 41, the main portion 43, and the connecting portion 44 is arranged at the position of the unit side coupling 36 so as not to hinder the connection between the unit side coupling 36 and the main body side coupling 50. It has become.

9 and 10 are a perspective view and a horizontal cross-sectional view showing the state of the unit 10 and the body-side coupling 50 when the unit 10 is attached to the apparatus body 110, respectively (the rotation axis of the photosensitive drum 1K and the driving roller 12). direction). As shown in FIG. 9 , the releasing member 40 is arranged so as to be sandwiched between the unit side coupling 36 and the body side coupling 50 . Then, the release member 40 is directed toward the left side of the apparatus main body 110 in the arrow A1 direction in the figure (the direction in which the unit 10 is inserted into the apparatus main body 110) by the handle spring 37 constituted by a compression spring as an urging means. energized. The handle spring 37 is attached in a compressed state between a spring support portion 35 a formed on the handle portion 35 and a spring receiving portion 46 formed on the release member 40 . Further, the main body side coupling 50 is biased toward the unit side coupling 36 in the arrow A2 direction in the drawing by a coupling spring 92 and engaged with the unit side coupling 36 . As shown in FIG. 10 , when the unit 10 is attached to the apparatus main body 110 , the release member 40 is arranged so that the first contact portion 41 a of the release portion 41 approaches the tapered surface 51 b of the main body side coupling 50 . are placed.

11 and 12 are a perspective view showing the state of the unit 10 and the main body side coupling 50 when the unit 10 is pulled out from the apparatus main body 110, and a horizontal cross-sectional view (the rotation axis direction of the photosensitive drum 1K and the drive roller 12). substantially parallel cross section). When pulling out the unit 10 from the apparatus main body 110, as shown in FIG. Pull the release member 40 in the direction. Then, the release member 40 slides on the handle portion 35 against the biasing force of the handle spring 37 until the contact portion 47 formed in the release member 40 abuts against the abutment portion 35b formed in the handle portion 35. Let me. Then, as shown in FIG. 12, the first contact portion 41a of the release portion 41 of the release member 40 contacts the tapered surface 51b of the body-side coupling 50 and slides on the tapered surface. As a result, the body side coupling 50 is moved away from the unit 10 side in the direction of the arrow A4 in the drawing, disengaging the body side coupling 50 and the unit side coupling 36, and the unit It is evacuated from the 10th side. In this state, by holding the handle 35 and pulling out the unit 10 to the right side of the device main body 110 in the direction of the arrow A3 in the drawing, that is, the direction substantially perpendicular to the rotation axis of the unit-side coupling 36, the unit 10 can be pulled out. can be taken out from the device main body 110 . The body-side coupling 50 rides on the releasing portion 41 of the releasing member 40, and after the releasing portion 41 has passed, it is biased by the coupling spring 92 to return to the state of protruding toward the unit 10 (see FIG. 16). ).

FIG. 13 is a schematic diagram of the gear train of the main drive unit 120 viewed from the front along the depth direction (rotation axis direction of the drive roller 12), showing the relationship between the release member 40 and the gear train of the main drive unit 120. FIG. be. That is, FIG. 13 is a schematic diagram in which the release member 40 is added to the side view of FIG. 3 so as to show the relationship with the main drive unit 120 . As described above, the body-side coupling 50 is configured to swing. Further, when the unit 10 is pulled out from the apparatus main body 110 , the release member 40 is moved in the pull-out direction of the unit 10 along the attachment/detachment direction of the unit 10 with respect to the apparatus main body 110 . Further, the meshing portion between the gear portion 52 of the body-side coupling 50 and the idler gear 55 is located downstream of the rotation axis of the body-side coupling 50 in the pull-out direction of the unit 10 .

In such a configuration, conventionally, when the release member 40 is moved when the unit 10 is pulled out from the apparatus main body 110, the main body side coupling 50 falls down in the direction in which the unit 10 is pulled out. At that time, the distance between the shafts of the gear portion 52 of the main body side coupling 50 and the idler gear 55 becomes narrower, the frictional resistance increases, and there is a possibility that the main body side coupling 50 cannot be retracted. there were. In some cases, the tip of the gear hits the bottom of the gear, which may damage the gear and cause banding (periodic image density unevenness such as horizontal streaks) to occur. This phenomenon occurs after the release member 40 is completely slid (until it abuts against the abutting portion 35b) to release the engagement between the body-side coupling 50 and the unit-side coupling 36, and then the device body 110 of the unit 10 is released. It is relatively unlikely to occur if you start withdrawing However, when the unit 10 is started to be pulled out from the apparatus main body 110 in a state in which the release member 40 is not completely slid, the phenomenon described above tends to become remarkable. This is thought to be due to the fact that the couplings are in an engaged state and that the movement of the release member 40 and the movement of the unit 10 are overlapped, and so on, and this promotes the fall of the body-side coupling 50. be done. When the main body side coupling 50 falls down and the axial distance (between the gears) between the gear portion 52 of the main body side coupling 50 and the idler gear 55 is shortened, the tip of the tooth and the root of the tooth slightly interfere with each other. There is a possibility that 50 will not be able to evacuate.

Therefore, in the present embodiment, the release member 40 is configured to restrict the direction in which the body-side coupling 50 falls when the unit 10 is pulled out from the apparatus body 110 in a desired direction. Next, this point will be described in detail.

FIG. 14 shows the unit side coupling 36 (driving roller 12 ) is a schematic diagram viewed along the direction of the rotation axis. More specifically, when the release member 40 is moved in the pull-out direction of the unit 10 , the contact position is such that the first contact portion 41 a of the release portion 41 of the release member 40 is aligned with the cup of the body side coupling 50 . This is the position at which the tapered surface 51b of the ring portion 51 first contacts.

As shown in FIG. 14, when the unit 10 is pulled out from the apparatus main body 110, the release member 40 is moved in the pull-out direction A3 of the unit 10. As shown in FIG. Further, when viewed along the rotation axis direction of the unit-side coupling 36, the rotation axis (rotation center) 55a of the idler gear 55 is closer to the rotation axis (rotation center) 50a than the body-side coupling 50. It is located downstream in direction A3. Therefore, when viewed along the rotation axis direction of the unit-side coupling 36, the meshing portion H between the gear portion 52 of the body-side coupling 50 and the idler gear 55 is aligned with the rotation axis (rotation center) 50a of the body-side coupling 50. , is located downstream of the unit 10 in the pull-out direction A3. More specifically, the meshing portion H between the gear portion 52 of the body-side coupling 50 and the idler gear 55 is defined by the pitch point of the body-side coupling 50 and the idler gear 55 (a common tangent line of the root circles of both gears and both gears). point of intersection with the line connecting the centers of rotation of

14 shows the unit-side coupling 36 in the area (tapered surface 51b of the coupling portion 51) where the body-side coupling 50 can contact the release member 40 in the rotational axis direction of the body-side coupling 50. A first position P1, a second position P2 and a third position P3 in the circumferential direction of the main body side coupling 50 when viewed along the rotation axis direction are shown. At the first position P1, the tangential direction of the main body side coupling 50 at the first position P1 is substantially orthogonal to the pull-out direction A3 of the unit 10, and the unit 10 is pulled out with respect to the rotation axis 50a of the main body side coupling 50. This is the position on the upstream side in the direction A3. At the second position P2, the tangential direction of the body side coupling 50 at the second position P2 is substantially parallel to the pull-out direction A3 of the unit 10, and the engagement portion H is located with respect to the rotation axis 50a of the body side coupling 50. position on the side. The third position P3 is closer to the second position P2 than the first position P1 in the region between the first position P1 and the second position P2, which are closer in the circumferential direction of the body-side coupling 50, and It is a position closer to the first position P1 than the second position P2.

Conventionally, the release member 40 is configured to abut on the body-side coupling 50 at the first position P1 in FIG. In this case, the direction of the force acting on the body side coupling 50 (the tilting direction of the body side coupling 50) is substantially perpendicular to the tangential direction of the body side coupling 50 at the first position P1, that is, the direction of the unit 10. It becomes the pull-out direction A3. Therefore, the gear portion 52 of the body-side coupling 50 is displaced from the idler gear 55 by the angle θ between this direction A3 and the tangential direction F of the meshing portion H between the gear portion 52 of the body-side coupling 50 and the idler gear 55 . It becomes a form that bites into. The tangential direction F of the meshing portion H between the gear portion 52 of the body-side coupling 50 and the idler gear 55 is, more specifically, the direction of the common tangent to the pitch circle of the gear portion 52 of the body-side coupling 50 and the idler gear 55. represented by

On the other hand, in the present embodiment, the release member 40 is configured to abut on the body side coupling 50 at the third position P3 in FIG. 14 when the unit 10 is pulled out from the device body 110. In this case, the direction of the force acting on the main body side coupling 50 (the tilting direction of the main body side coupling 50) is substantially orthogonal to the tangential direction of the main body side coupling 50 at the third position P3. approaches the second position P2, the degree of biting becomes smaller. However, in a configuration in which the release member 40 abuts on the body side coupling 50 at the second position P2, it is difficult to retract the body side coupling 50 . In this way, when the unit 10 is pulled out from the apparatus main body 110, the release member 40 is configured to abut on the main body side coupling 50 at the third position P3. It is possible to regulate in the direction of reducing biting. As a result, the body-side coupling 50 can be smoothly retracted. Also, it is possible to suppress damage to the gear. Here, the third position P3 between the first position P1 and the second position P2 is typically a line segment passing through the first position P1 with the rotation axis 50a of the body-side coupling 50 as a reference. From the position where the angle between the line segment passing through the third position P3 and the line segment passing through the third position P3 is 10° or more to the position where the angle between the line segment passing through the second position P2 and the line segment passing through the third position P3 is 10° or more is the position of In other words, for example, in the conventional structure in which the body-side coupling 50 abuts at the first position P1, the case where the abutment position slightly deviates due to a tolerance or the like is not included.

Further, the releasing member 40 is configured to adjust the tilting direction of the main body side coupling 50 (the direction of the force acting on the main body side coupling 50) by the releasing member 40 when the unit 10 is pulled out from the apparatus main body 110. 50 and the idler gear 55, or in the direction in which the axial distance between the gear portion 52 of the body-side coupling 50 and the idler gear 55 is widened. preferable. In other words, even if the main body side coupling 50 falls down, the main body side coupling 50 is rotated in a direction in which the inter-axial distance between the gear portion 52 of the main body side coupling 50 and the idler gear 55 does not decrease or in a direction in which the inter-axial distance increases. (the direction of the force acting on the main body side coupling 50) is preferably regulated. As a result, the body-side coupling 50 can be retracted more smoothly. In addition, damage to the gear can be further suppressed.

More specifically, as shown in FIG. 13, the tangential direction F of the meshing portion H between the gear portion 52 of the body side coupling 50 and the idler gear 55 and the tapered surface of the body side coupling 50 when the releasing member 40 is operated. The angle E formed by the direction D of the force acting on 51b is preferably 0° or more. The direction in which this force acts is the direction in which the normal force of the contact portion acts. In other words, this direction D can be said to be a direction substantially orthogonal to the tangential direction G of the main body side coupling 50 at the position where the release member 40 contacts the main body side coupling 50 when the unit 10 is pulled out from the apparatus main body 110 . Therefore, in other words, the tangential direction F of the meshing portion H between the gear portion 52 of the main body side coupling 50 and the idler gear 55 and the releasing member 40 abut against the main body side coupling 50 when the unit 10 is pulled out from the apparatus main body 110. It is preferable that the angle I formed by the tangential direction G of the main body side coupling 50 at the position is 90° or more.

Specifically, in this embodiment, as shown in FIG. 13, the first contact portion 41a of the release portion 41 of the release member 40 extends in the pull-out direction A3 of the unit 10 and in a direction substantially orthogonal to the pull-out direction A3. It is composed of inclined surfaces having an angle with respect to each other. Thus, the release member 40 is configured such that the angle E is 0° or more (the angle I is 90° or more).

In this embodiment, the first contact portion 41a of the releasing portion 41 of the releasing member 40 is linear, but the present invention is not limited to such an aspect. The first contact portion 41a of the release portion 41 of the release member 40 may be configured as follows. For example, as shown in FIG. 15( a ), the first contact portion 41 a is designed to contact the body side coupling 50 first when the unit 10 is pulled out from the apparatus body 110 . They may be convexly curved in the direction of separation. Alternatively, as shown in FIG. 15(b), the first contact portion 41a is provided on the side of the body side coupling 50 so that it can first contact the body side coupling 50 when the unit 10 is drawn out from the apparatus body 110. may be convexly curved.

According to the configuration of this embodiment, for example, even when the unit 10 is pulled out from the apparatus main body 110 before the release member 40 is slid, the clogging between the gears can be smoothly eliminated by sliding the release member 40. can. Then, the body-side coupling 50 can be smoothly retracted, and the unit 50 can be pulled out from the device body 110 .

Next, FIGS. 16 and 17 are a perspective view and a horizontal sectional view showing the state of the unit 10 and the body-side coupling 50 when the unit 10 is inserted into the apparatus body 110, respectively. cross section substantially parallel to the rotation axis direction). As shown in FIG. 16, the body-side coupling 50 is biased by the coupling spring 92 to protrude toward the unit 10 side. In this state, the operator holds the grip portion 35 and inserts the unit 10 into the left side of the apparatus main body 110 in the direction of arrow A5 in the figure, that is, in the direction substantially orthogonal to the rotation axis of the unit-side coupling 36. To go. Then, as shown in FIG. 17, the second contact portion 41b of the release portion 41 of the release member 40 contacts the tapered surface 51b of the body-side coupling 50 and slides on the tapered surface 51b. As a result, the body-side coupling 50 is moved away from the unit 10 side in the arrow A6 direction in the drawing, and is retracted from the unit 10 side. In this state, the unit 10 can be further inserted and mounted at a predetermined position within the apparatus main body 110 . Note that the body-side coupling 50 rides on the release portion 41 of the release member 40, and after the release portion 41 has passed, it is biased by the coupling spring 92 and engaged with the unit-side coupling 36 ( See Figure 10).

When the unit 10 is inserted, the main body side coupling 50 is tilted in the direction away from the idler gear 55, so the retreating operation of the main body side coupling 50 is not affected. Therefore, in this embodiment, as shown in FIGS. 8 and 16, the second contact portion 41b of the release portion 41 of the release member 40 is positioned in the insertion direction A5 of the unit 10 (the direction opposite to the pull-out direction A3 of the unit 10). ) and is composed of a linear surface substantially orthogonal to the In this case, the direction of the force acting on the body side coupling 50 (the tilting direction of the body side coupling 50) is the insertion direction A5 of the unit 10. FIG. As described above, in this embodiment, when viewed along the rotation axis direction of the unit side coupling 36, the tilting direction of the main body side coupling 50 (main body side cup) when the unit 10 is pulled out from the device main body 110 relationship between the direction of force acting on the ring 50) and the tilting direction of the body side coupling 50 when the unit 10 is inserted into the apparatus body 110 (direction of force acting on the body side coupling 50) are not inversely related. That is, the angle formed by both directions is less than 180°. In other words, in this embodiment, when viewed along the rotation axis direction of the unit side coupling 36, the tangential direction of the main body side coupling 50 at the position where the first contact portion 41a contacts and the second contact The tangential direction of the body-side coupling 50 at the position where the portion 41b abuts is not parallel, and both directions intersect at an angle. If the gear train of the main drive unit 120 has a structure in which the inter-axis distance between the gears is reduced when the unit 10 is inserted, the following may be done. In other words, the second contact portion 41b of the release member 40 is provided with an inclined surface on which force acts in the direction in which the distance between the shafts of the gears increases in the same manner as the first contact portion 41a of the present embodiment. It is possible.

Here, by providing a tapered surface 41a1 (FIGS. 8 and 10) at the corner of the first contact portion 41a of the releasing portion 41 of the releasing member 40, the unit 10 can be pulled out from the apparatus main body 110 more smoothly. operation can be realized. The tapered surface 41a1 of the first contact portion 41a is inclined with respect to the rotational axis of the unit side coupling 36 to the same side as the tapered surface 51b of the body side coupling 50 when the tapered surface 41a1 is in contact with the tapered surface 41a1. form like Similarly, by providing a tapered surface 41b1 (FIG. 10) at the corner of the second contact portion 41b of the releasing portion 41 of the releasing member 40, smoother operation when inserting the unit 10 into the apparatus main body 110 is achieved. realizable. The tapered surface 41b1 of the second contact portion 41b is inclined to the same side as the tapered surface 51b of the main body side coupling 50 when it contacts the tapered surface 41a1 with respect to the rotational axis of the unit side coupling 36. form like Either one of the tapered surfaces 41a1 and 41b1 of the first and second contact portions 41a and 41b may be provided, but both are preferably provided.

As described above, the image forming apparatus 100 of this embodiment includes the drive source 80 , the front gear 55 rotated by the driving force transmitted from the drive source 80 , and the gear portion 52 meshing with the front gear 55 . A device main body 110 having a main body side coupling 50 which is rotated by transmission of a driving force from and movable in the rotation axis direction. Further, the image forming apparatus 100 of the present embodiment includes the endless belt 11, the driving roller 12 for driving the belt 11, and the body side coupling 50 which are engaged with each other to transmit the driving force from the body side coupling 50. and a unit side coupling 36 that rotates coaxially with the main body side coupling 50 and transmits driving force to the drive roller 50, and is inserted into the apparatus main body 110 along a direction intersecting the rotation axis of the unit side coupling 36. It has a unit 10 that can be attached to and detached from the apparatus main body 110 by being moved in a direction and an extraction direction from the apparatus main body 110 . In this image forming apparatus 100, the unit 10 is provided movably with respect to the unit 10 along the attachment/detachment direction of the unit 10 with respect to the apparatus main body 110. A releasing member 40 for releasing is provided, and when the releasing member 40 is moved in the pull-out direction, the releasing member 40 comes into contact with the main body side coupling 50 and retracts the main body side coupling 50 from the unit side coupling 36. The contact portion 41 a is provided, and when viewed along the rotation axis direction of the unit side coupling 36 , the meshing portion H between the gear portion 52 and the front stage gear 55 extends in the pull-out direction with respect to the rotation center of the main body side coupling 50 . located downstream of In the image forming apparatus 100, the unit side coupling 36 is viewed along the rotation axis direction in the area where the body side coupling 50 can contact the releasing member 40 in the rotation axis direction of the body side coupling 50. When the first position P1, the second position P2 and the third position P3 in the circumferential direction of the main body side coupling 50 are defined as shown in FIG. It abuts on the coupling 50 .

In this embodiment, when viewed along the rotation axis direction of the unit side coupling 36, the tangential direction F of the meshing portion H and the tangential direction of the main body side coupling 50 at the position where the contact portion 41a contacts The angle I formed with G is 90° or more. Further, in this embodiment, the contact portion 41a is formed of a surface having an angle with respect to the pull-out direction and a direction substantially orthogonal to the pull-out direction. In this embodiment, the releasing member 40 is another contact that contacts the body side coupling 50 and retracts the body side coupling 50 from the unit side coupling 36 when the unit 10 is moved in the insertion direction. It has a contact portion 41b. In this embodiment, when viewed along the rotation axis direction of the unit-side coupling 36, the tangential direction of the body-side coupling 50 at the position where the contact portion 41a contacts another contact portion 41b contacts. and the tangential direction of the body-side coupling 50 at the position intersect. In this embodiment, the body-side coupling 50 has a taper formed in a region where it can come into contact with the release member 40 in the rotational axis direction so as to increase in diameter as it becomes farther from the unit side in the rotational axis direction. It has a surface 51b. Further, in this embodiment, the unit 10 includes a biasing member 37 that biases the releasing member 40 in the insertion direction. By moving the release member 40 in the pull-out direction against the biasing force, the contact portion 41a contacts the body side coupling 50 in a state in which the unit 10 is attached to the apparatus body 110, thereby releasing the body side coupling. 50 is retracted from the unit-side coupling 36. Further, in this embodiment, the body-side coupling 50 is supported so that the tip on the unit 10 side in the direction of the rotation axis can swing with respect to the rotation axis. Further, in this embodiment, the belt 11 is an intermediate transfer belt that conveys toner images that have been primarily transferred from a plurality of image carriers 1 to the recording material S for secondary transfer. Further, in this embodiment, the image carrier 1K positioned closest to the drive roller 12 in the attachment/detachment direction of the unit 10 with respect to the apparatus main body 110 among the plurality of image carriers 1 and the drive roller 12 share the common drive source 80. It rotates by the driving force transmitted from

As described above, according to this embodiment, when the body side coupling 50 is retracted by the releasing member 40, the body side coupling 50 can be smoothly retracted.

[others]
Although the present invention has been described with reference to specific examples, the present invention is not limited to the above-described examples.

For example, in the above embodiments, the detachable unit detachable from the main body of the apparatus has been described as the intermediate transfer belt unit, but it is not limited to this. For example, as a recording material carrier for carrying and conveying a recording material onto which a toner image is transferred from the image carrier, a recording material carrying belt constituted by an endless belt similar to the intermediate transfer belt in the above-described embodiment is used. There is a direct transfer type image forming apparatus used. The detachable unit may be a recording material carrying belt unit including this recording material carrying belt. In other words, the present invention works favorably in a detachable unit having an endless belt that directly carries a toner image or carries and conveys a recording material via a recording medium, and the driven member is a drive roller that drives the belt. do.

Further, the driven member is not limited to a driving roller of an endless belt such as an intermediate transfer belt or a recording material carrying belt. It is conceivable to apply the present invention to any detachable unit that has a driven member to which driving force from a driving source provided in the device main body is transmitted and is detachable from the device main body. Also in this case, the same effect as the above-described embodiment can be obtained. For example, the detachable unit includes a cartridge including a photosensitive drum as a driven member, and a fixing device including a fixing roller and a pressure roller as the driven member.

Further, in the above-described embodiments, the detachable unit is arranged substantially horizontally within the apparatus main body, and is moved substantially horizontally to be attached to and detached from the apparatus main body. However, the present invention is not limited to such an aspect. For example, as shown in FIG. It may be arranged obliquely. In such a case, for example, the detachable unit may be moved in a direction inclined with respect to the horizontal plane to be detached from the apparatus main body.

Reference Signs List 1 photosensitive drum 10 intermediate transfer belt unit 12 drive roller 36 unit side coupling 40 release member 41 release portion 41a first contact portion 41b second contact portion 50 body side coupling 51 coupling portion 55 idler gear

Claims (10)

A drive source, a front gear that rotates by transmission of the driving force from the drive source, and a gear portion that meshes with the front gear are provided, and are rotated by the transmission of the drive force from the drive source and are movable in the direction of the rotation axis. a device main body comprising a main body side coupling,
an endless belt, a drive roller for driving the belt, and a drive roller that engages with the main body side coupling, receives a driving force from the main body side coupling, and rotates coaxially with the main body side coupling to rotate the drive roller. and a unit-side coupling that transmits a driving force to the unit-side coupling, and is moved in a direction of insertion into the apparatus main body and a direction of withdrawal from the apparatus main body along a direction intersecting the rotation axis of the unit side coupling. a unit that is detachable from the device main body,
the unit includes a releasing member that is provided movably with respect to the unit along a direction in which the unit is attached to and detached from the apparatus body and that releases engagement between the body-side coupling and the unit-side coupling;
The release member has a contact portion that contacts the main body side coupling and retracts the main body side coupling from the unit side coupling when the release member is moved in the pull-out direction,
When viewed along the rotation axis direction of the unit side coupling, the meshing portion between the gear portion and the front stage gear is positioned downstream in the pull-out direction with respect to the rotation center of the body side coupling. In an image forming apparatus with
Circumference of the main body side coupling when viewed along the rotational axis direction of the unit side coupling in a region where the main body side coupling can contact the release member in the rotational axis direction of the main body side coupling a first position P1, a second position P2, and a third position P3 of the direction, wherein the tangential direction of the body-side coupling at the first position P1 is substantially orthogonal to the pull-out direction; In addition, the second position P2 is a position on the upstream side in the pull-out direction with respect to the rotation center of the body-side coupling, and the second position P2 is such that the tangential direction of the body-side coupling at the second position P2 is the pull-out direction. and is located on the meshing portion side with respect to the center of rotation of the body-side coupling, and the third position P3 is the first position P1 having a shorter distance in the circumferential direction. In the region between the second position P2, when the position is closer to the second position P2 than the first position P1 and closer to the first position P1 than the second position P2, the The image forming apparatus, wherein the abutting portion abuts on the body-side coupling at the third position P3. When viewed along the rotation axis direction of the unit-side coupling, the angle I between the tangential direction of the meshing portion and the tangential direction of the body-side coupling at the position where the contact portion abuts is 90. ° or more, the image forming apparatus according to claim 1 . 3. The image forming apparatus according to claim 1, wherein the contact portion is formed of a surface having an angle with respect to the pull-out direction and a direction substantially orthogonal to the pull-out direction. The release member has another abutment portion that abuts against the main body side coupling and retracts the main body side coupling from the unit side coupling when the unit is moved in the insertion direction. 4. The image forming apparatus according to any one of claims 1 to 3. When viewed along the rotation axis direction of the unit side coupling, the tangential direction of the body side coupling at the position where the contact portion contacts and the body side coupling at the position where the another contact portion contacts 5. The image forming apparatus according to claim 4, wherein the tangential direction of . The body-side coupling is characterized in that it has a tapered surface formed so as to increase in diameter as it becomes farther from the unit side in the direction of the rotation axis in a region where it can come into contact with the release member in the direction of the rotation axis. 6. The image forming apparatus according to any one of claims 1 to 5. The unit includes a biasing member that biases the releasing member in the insertion direction, and the releasing member resists the biasing force of the biasing member when the unit is pulled out from the apparatus body. By moving the releasing member in the direction, the abutting portion abuts against the main body side coupling in a state where the unit is attached to the apparatus main body, thereby separating the main body side coupling from the unit side coupling. 7. The image forming apparatus according to claim 1, wherein the image forming apparatus is retracted. 8. The image according to any one of claims 1 to 7, wherein the body-side coupling is supported so that the tip of the unit side in the direction of the rotation axis can swing with respect to the rotation axis. forming device. 9. The apparatus according to any one of claims 1 to 8, wherein the belt is an intermediate transfer belt that conveys toner images that have been primarily transferred from a plurality of image bearing members so as to be secondarily transferred onto a recording material. image forming device. Among the plurality of image carriers, the image carrier positioned closest to the driving roller in the mounting/demounting direction of the unit with respect to the apparatus main body and the driving roller are rotated by a common driving force transmitted from the driving source. 10. The image forming apparatus according to claim 9, wherein:

Images