JP2004061798A - Intermediate transfer unit and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an intermediate transfer unit which easily improves the positioning accuracy of the coupling of a contact/separation mechanism and reduces the effect of a drive input or the contact /separation mechanism on rotation moment, and to provide an image forming apparatus having the unit. <P>SOLUTION: The representative structure of the intermediate transfer unit which is attachable/detachable to/from a device body comprises: an intermediate transfer member on which an image formed on an image carrier is primarily transferred; a drive roller and a driven roller around which the intermediate transfer member is laid with tension; a secondary transfer means contact/separation means which brings a secondary transfer means into contact with the intermediate transfer member or separates it therefrom, the secondary transfer means being used for transferring the image on the intermediate transfer member to a sheet; a first coupling which transmits drive to the drive roller; a second coupling which transmits drive to the secondary transfer means contact/separation means; and first and second positioning means which position the unit with respect to the device body. The second coupling is situated between the first and second positioning means. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a configuration of an intermediate transfer unit in an image forming apparatus such as a copying machine or a printer using an electrophotographic method.
[0002]
[Prior art]
2. Description of the Related Art An image forming apparatus using an electrophotographic system forms an image by visualizing a latent image with toner as a developer, transferring the image to a sheet, and fixing the image. In such an electrophotographic image forming apparatus, a configuration is generally known in which, in order to form a color image in particular, a toner image of a plurality of colors is primary-transferred onto an intermediate transfer member in a superimposed manner, and then is collectively secondary-transferred onto a sheet. ing. Further, a configuration has been known in which an intermediate transfer member is unitized to be detachable from an apparatus main body.
[0003]
In an image forming apparatus using the above-mentioned intermediate transfer body unit, it is generally known that a contact and separation mechanism of a secondary transfer roller and a contact mechanism of a cleaning roller for cleaning an intermediate transfer body are arranged on the apparatus main body side. ing. In this case, the intermediate transfer body unit has no coupling other than the drive roller coupling for driving the intermediate transfer body.
[0004]
In a conventional color image forming apparatus using an intermediate transfer body, as shown in FIG. 10, for example, an elevation mechanism of a secondary transfer roller 107 (secondary transfer means) for collectively transferring a toner image on an intermediate transfer belt 106 to a sheet. 108 and the intermediate transfer unit 101 are independent from each other. A large movable frame 102 is provided on the front side (left side in the drawing) of the apparatus, and by rotating and opening the movable frame 102, the intermediate transfer body unit 101 and the image carrier unit 100 can be detached. I have. The elevating mechanism 108 of the secondary transfer roller 107 is arranged on the apparatus main body side, and the driving is directly obtained from the main body.
[0005]
Waste toner on the intermediate transfer belt 106 of the intermediate transfer unit 101 is also scraped off by a cleaning blade (not shown), transported to a lower portion of the first transport pipe by a transport coil, and further removed by a screw in the first transport pipe. Is transported to above the waste toner storage box 105. Thereafter, the toner is conveyed by the conveyance coil in the second conveyance pipe, and is finally stored in the waste toner storage box 105. The connecting portion between the second transport pipe and the waste toner box is a separate unit and is configured to be detachably attached to each other, so that waste toner is not spilled at the time of attachment and detachment.
[0006]
In the above configuration, the secondary transfer roller 107 and the intermediate transfer body unit 101 are independently positioned on the image forming apparatus main body, and the drive transmission coupling of the intermediate transfer belt 106 and the drive of the secondary transfer roller 107 are driven. Are connected independently from the image forming apparatus main body side.
[0007]
Here, the cleaning blade itself for scraping waste toner on the intermediate transfer belt 106 is provided in the intermediate transfer unit 101, but a driving unit for bringing the cleaning blade into contact with and separating from the intermediate transfer belt 106 is provided in the apparatus main body. Have been. Further, a driving unit for bringing the secondary transfer unit 107 into and out of contact with the intermediate transfer belt 106 is also provided on the apparatus main body side.
[0008]
[Problems to be solved by the invention]
However, in the configuration according to the conventional example, a cleaning blade for scraping waste toner on the intermediate transfer belt 106 and a driving unit for moving the secondary transfer roller 107 toward and away from the surface of the intermediate transfer belt 106 are provided. Since the rotational driving force is provided on the apparatus main body side and transmitted from a driving source in the apparatus main body via a gear train, a drive transmission path in the apparatus main body is complicated.
[0009]
Further, the mechanism for bringing the cleaning blade and the secondary transfer roller 107 into and out of contact with the intermediate transfer belt 106 uses a lever and a cam, respectively, and requires a through shaft extending across the width of the apparatus main body, and requires a large space in the apparatus main body. However, there is a problem that the configuration becomes complicated. For this reason, there has been a problem that the unit becomes larger, the apparatus body becomes more complicated and larger, and the production cost increases.
[0010]
Here, in order to produce the entire apparatus more compactly and inexpensively, it is conceivable to provide the intermediate transfer body unit 101 with a mechanism for contacting and separating the secondary transfer roller 107 and a mechanism for contacting the cleaning blade. For example, by providing a cam near the secondary transfer roller 107, it is possible to enable a mechanism for raising and lowering the secondary transfer roller 107.
[0011]
At that time, drive transmission from the main body to the intermediate transfer body unit 101 via a coupling is required. In this case, the drive positioning of the coupling of the contact / separation mechanism causes a dimensional error between the intermediate transfer body unit 101 and the apparatus main body and a dimensional error on the intermediate transfer body unit 101 to overlap with each other, so that the position is difficult to come out. In addition, an increase in the number of drive couplings causes a problem that the influence of the rotational moment of the coupling and the reaction force received via the cam increases.
[0012]
Therefore, the present invention provides an intermediate transfer body unit capable of easily improving the positional accuracy of the coupling of the contact / separation mechanism and reducing the influence of the driving input and the rotational moment due to the contact / separation mechanism, and an image forming apparatus having the same. It is intended to be.
[0013]
[Means for Solving the Problems]
In order to solve the above problems, a typical configuration of the intermediate transfer body unit according to the present invention is a unit that is detachable from the apparatus main body, and is used to temporarily transfer an image formed on an image carrier. A secondary transfer unit that moves an intermediate transfer body, a driving roller and a driven roller that stretches the intermediate transfer body, and a secondary transfer unit that transfers an image on the intermediate transfer body to a sheet; Transfer means contact / separation means, a first coupling for transmitting drive to the drive roller, a second coupling for transmitting drive to the secondary transfer means contact / separation means, and a first coupling for positioning the unit in the apparatus main body. It has a positioning means and a second positioning means, wherein the second coupling is located between the first and the second positioning means.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of an intermediate transfer body unit and an image forming apparatus according to the present invention will be described with reference to the drawings. In this embodiment, the image forming apparatus is a four-color full-color laser beam printer employing an electrophotographic system.
[0015]
(Image forming device)
FIG. 1 is a longitudinal sectional view illustrating a schematic configuration of the image forming apparatus. The image forming apparatus A has a process cartridge B detachably as an intermediate transfer member unit having an intermediate transfer member and a secondary transfer contact / separation unit or a cleaning contact / separation unit. The process cartridge B will be described later.
[0016]
During image formation, the surface is uniformly charged by a charging roller 2 as a charging unit while rotating a photosensitive drum 1 as an image carrier in an arrow direction (counterclockwise) in FIG. This forms an electrostatic latent image. At the same time as the formation of the electrostatic latent image, the developing device 4 is driven to place the yellow developing unit 4Y at the developing position, and the electrostatic latent image on the photosensitive drum 1 is developed with the yellow toner. A voltage having the same polarity and substantially the same potential as the charging polarity of the photosensitive drum 1 is applied to the toner to cause the yellow toner to adhere to the electrostatic latent image.
[0017]
The toner image formed on the photosensitive drum 1 is transferred to an intermediate transfer belt 5 that is an intermediate transfer member that rotates in synchronization with the photosensitive drum 1 by a primary transfer roller 6 that is a primary transfer unit. A voltage having a polarity opposite to that of the toner is applied to the primary transfer roller 6, and the toner image on the photosensitive drum 1 is attracted. When the yellow toner image is primary-transferred, the developing device 4 is rotated, and similarly, formation, development, and primary transfer of an electrostatic latent image are sequentially performed for each of the colors magenta, cyan, and black. Are superimposed.
[0018]
At this time, a secondary transfer roller 7 described later is not in contact with the intermediate transfer belt 5. The charging roller 8 as a cleaning unit for the intermediate transfer belt 5 is also in a non-contact state with the intermediate transfer belt 5.
[0019]
On the other hand, a feed cassette 10 for stacking and feeding sheets is disposed below the apparatus main body A, and is fed to a pair of registration rollers 13 by a feed roller 11. A pre-registration sensor 12 for detecting a sheet is provided upstream of the pair of registration rollers 13, and detects the leading edge of the sheet to cut off the rotational driving force of the pair of registration rollers 13 and wait the sheet S at a predetermined position. Let it.
[0020]
After the four color toner images are formed on the intermediate transfer belt 5, the secondary transfer roller 7 is pressed against the intermediate transfer belt 5 (the state shown in FIG. 1). Further, in synchronization with the rotation of the intermediate transfer belt 5, the conveyance of the sheet waiting at a predetermined position near the registration roller pair 13 as the sheet conveyance means is started, and the nip between the intermediate transfer belt 5 and the secondary transfer roller 7 is started. Sent to the department. A voltage having a polarity opposite to that of the toner is applied to the secondary transfer roller 7, and the toner image on the intermediate transfer belt 5 is secondarily transferred to the surface of the conveyed sheet at a time.
[0021]
The sheet on which the toner image has been secondarily transferred reaches the fixing unit 15 via the transport belt unit 14, where heat and pressure are applied to fix the toner image. Then, the sheet is conveyed along a discharge guide 17 by a fixing discharge roller 16 and discharged and stacked by a discharge roller pair 18 on a discharge tray 19 provided on the upper surface of the apparatus, thereby completing image formation.
[0022]
On the other hand, a charging roller 8 as a cleaning unit is pressed against the intermediate transfer belt 5 after the completion of the secondary transfer, and the remaining toner remaining on the intermediate transfer belt 5 is given a charge opposite to that at the time of transfer. 5 is electrostatically attached to the photosensitive drum 1. A cleaning blade 9 is brought into contact with the photosensitive drum 1 as cleaning means, and the residual toner scraped off from the surface is collected and accumulated in a waste toner storage box 20 by following a waste toner conveying means described later.
[0023]
(Intermediate transfer unit)
Next, the process cartridge B, which is an intermediate transfer unit, will be described. 2 and 3 are side views as viewed from the left side of the front surface of the intermediate transfer unit, FIGS. 4 and 5 are side views as viewed from the right side of the front side of the intermediate transfer unit, and FIG. FIG. 7 is a top view of the unit, FIG. 7 is a view for explaining the operation of the waste toner conveying means, FIG. 8 is a view showing a state in which the secondary transfer means and the cleaning means are in contact with the intermediate transfer member, and FIG. FIG.
[0024]
As shown in FIG. 2, in the process cartridge B, the image carrier 21 having the photosensitive drum 1 is disposed above the projection of the intermediate transfer member 22 including the intermediate transfer belt 5, and the projection of the intermediate transfer member 22 is performed. A waste toner storage box 20 is disposed below.
[0025]
In the image carrier 21, the photosensitive drum 1 is rotatably supported at both ends by a right bearing 1 a and a left rotating shaft 1 b, and the main body of the apparatus via a drive transmission coupling 58 which is a drive bearing at the right end. A predetermined rotational driving force is transmitted from the motor (see FIG. 6). The image carrier 21 is also provided with a drum shutter 25 that opens and closes in conjunction with the operation of attaching and detaching the image carrier to and from the image forming apparatus main body.
[0026]
The charging roller 2 is pressed against the photosensitive drum 1 with a predetermined force by a compression spring 24 via bearings 23 at both ends, and is configured to rotate following the photosensitive drum 1. At least one of the bearings 23 is formed of a conductive member, and applies a predetermined charging bias voltage to the charging roller 2 to uniformly charge the surface of the photosensitive drum 1. Such a contact charging type charging device is disclosed in Japanese Patent Application Laid-Open No. 63-149669.
[0027]
In the intermediate transfer member 22, the intermediate transfer belt 5 is an endless belt, and is stretched around an intermediate transfer member frame 35 including a handshake portion 35a by a driving roller 26 and a driven roller 27. The driven roller 27 is given a predetermined tension by a compression spring 29 provided on bearings 28 at both ends. The drive roller 26 is rotatably supported at both ends thereof by a right bearing 26a and a left bearing 26b. The drive roller 26 is provided at a predetermined position from the apparatus body via a drive transmission coupling 59 (first coupling) which is a drive bearing at the right end. The rotational driving force is transmitted.
[0028]
A primary transfer roller 6 is provided at a position facing the photosensitive drum 1 with the intermediate transfer belt 5 interposed therebetween. The primary transfer roller 6 is pressed by a compression spring 31 via bearings 30 at both ends with a predetermined force, and is driven to rotate by the intermediate transfer belt 5. It is configured to be. At least one of the bearings 30 is formed of a conductive member. By applying a predetermined charging bias voltage to the primary transfer roller 6, the toner image on the surface of the photosensitive drum 1 is primarily transferred onto the intermediate transfer belt 5.
[0029]
In addition, a cleaning charging roller unit 32 as a cleaning unit (hereinafter, referred to as ICL) is provided on the driving roller 26 of the intermediate transfer body unit 22 and has an integral structure. The charging roller 8 arranged in the cleaning charging roller unit 32 is pressed against the intermediate transfer belt 5 with a predetermined force by a compression spring 34 via bearings 33 at both ends, and is configured to be driven to rotate. At least one of the bearings 33 is formed of a conductive member, and applies a voltage opposite to that at the time of transfer to the charging roller 8 to apply a charge to the residual toner on the intermediate transfer belt 5 opposite to that at the time of transfer. As a result, the waste toner on the intermediate transfer belt 5 is electrostatically attracted and collected on the surface of the photosensitive drum 1.
[0030]
A cleaning blade 9 serving as a cleaning unit is provided at a predetermined position on the photosensitive drum 1, and the residual toner on the photosensitive drum 1 and the residual toner on the intermediate transfer belt 5 adsorbed and collected on the photosensitive drum 1 described above. Is configured to be scraped off. The scraped-off waste toner is prevented from falling onto the intermediate transfer belt 5 by the squeeze sheet 36 and falls into the image carrier frame 37. The waste toner accumulated at the bottom of the image carrier frame 37 is conveyed to the right as viewed from the front of the apparatus by the rotation of the screw 38 (the direction of arrow C in FIG. 6).
[0031]
As shown in FIG. 4, the waste toner is conveyed by the screw 38 to the right side when viewed from the front of the apparatus of the process cartridge B, and slides down the waste toner passage 39 (the direction of arrow D in FIG. 4). Further, a wire 40 having a U-shape is provided inside the waste toner passage 39 as shown in FIG. 6, and one end thereof is rotated to a position eccentric from the rotation center of the screw 38 as shown in FIG. The other end is a free end, and is inserted into a hole 41 connecting the waste toner passage 39 and the waste toner storage box 20.
[0032]
As a result, when the screw 38 rotates in the direction of arrow C, the wire 40 traces the inner wall surface of the waste toner passage 39 while swinging as shown in FIGS. At this time, the U-shape of the wire 40 moves back and forth in the waste toner conveying direction, so that clogging of the waste toner is prevented and the effect of conveying the waste toner is obtained. Further, in the hole 41 connecting the waste toner passage 39 and the waste toner storage box 20, the end of the wire 40 rotates around the outer periphery of the hole 41 as shown in FIGS. Clogging can also be prevented.
[0033]
The waste toner that has dropped into the waste toner storage box 20 from the hole 41 is adjusted by the stirring plate 42 and accumulated. The stirring plate 42 is rotated by transmitting a rotational driving force from the image forming apparatus main body, similarly to the screw 38.
[0034]
(Contact and separation means)
Here, a description will be given of the secondary transfer unit and the contacting / separating unit of the cleaning unit (ICL), which are features of the present invention. As shown in FIG. 6, at both ends of the drive roller 26 of the intermediate transfer belt 5, ICL contact / separation cams 45a and 45b and secondary transfer roller contact / separation cams 46a and 46b are provided, respectively. Further, cam drive gears 47a and 47b are disposed between the ICL contact / separation cam 45 and the secondary transfer roller contact / separation cam 46, respectively, and the ICL contact / separation cam 45 and the secondary transfer roller contact / separation cam 46 are cam drive gears. 47 is fixed with a predetermined phase.
[0035]
The ICL contact / separation cam 45, the secondary transfer roller contact / separation cam 46, and the cam drive gear 47 are integrally provided rotatably with respect to the drive roller 26. Also, the cam phases at the left and right ends are matched to the target, and drive transmission gears 49a and 49b, which are cam drive transmission means provided at both ends of the through shaft 48, mesh with the left and right cam drive gears 47a and 47b, respectively. The cams at both ends are configured to rotate synchronously. As shown in FIG. 5, the rotational driving force transmitted from the apparatus main body is transmitted from the gear 50 via the idler gears 51 and 52 to the right drive transmission gear 49a. As a result, the driving force is transmitted to the cam drive gears 47a and 47b from the drive transmission gears 49a and 49b provided at the left and right ends, respectively, and the ICL contact / separation cams 45a and 45b and the secondary transfer roller contact / separation cams 46a and 46b rotate. I do.
[0036]
Here, the charging roller 8 for cleaning is rotatably held by the left and right bearings 33 as described above, and is moved along the bearing slide portion 35b (see FIG. 4) of the intermediate transfer body frame 35 by the left and right compression springs 34. It is urged by the drive roller 26 of the intermediate transfer belt 5. In the state shown in FIGS. 3 and 4, the tips 33 a of the left and right bearings 33 abut against the ICL contact / separation cams 45 a and 45 b, and the charging roller 8 for cleaning is separated from the surface of the intermediate transfer belt 5.
[0037]
Also, the secondary transfer roller 7 provided on the apparatus main body side is rotatably held by the left and right bearings 54, and drives the intermediate transfer belt 5 along the bearing slide guide portion 57 of the apparatus main body frame 56 by the compression spring 55. The roller 26 is urged. In the state shown in FIGS. 3 and 4, the distal ends 54 a of the left and right bearings 54 are in contact with the secondary transfer roller contact / separation cam 46 and are separated from the surface of the intermediate transfer belt 5. Here, a protrusion 57a for preventing the bearing 54 from coming off is provided at the end of the bearing slide guide 57 on the side of the apparatus main body frame 56, so that the secondary transfer roller 7 does not come off even if the process cartridge B is pulled out from the apparatus main body. It has become.
[0038]
In the above configuration, the cleaning contact / separation means includes the ICL contact / separation cam 45, the drive transmission gear 49, the compression spring 34, and the bearing 33. Similarly, the secondary transfer unit contact / separation unit includes a secondary transfer roller contact / separation cam 46, a drive transmission gear 49, a compression spring 55, and a bearing 54.
[0039]
The state in which the charging roller 8 and the secondary transfer roller 7 are separated from the intermediate transfer belt 5 is a state in which a toner image is formed on the intermediate transfer belt 5 or a state in which the image forming apparatus main body itself is at rest. . Also, the ICL contact / separation cam 45 and the secondary transfer roller contact / separation cam 46 maintain the charging roller 8 and the secondary transfer roller in the state where the process cartridge B is removed from the apparatus main body and when the process cartridge B is mounted on the apparatus main body. The transfer roller 7 is positioned at a phase that keeps the transfer roller 7 separated.
[0040]
When a toner image is formed on the intermediate transfer belt 5 and the toner image is secondarily transferred to the sheet, the driving force is transmitted to the gear 50 so that the drive transmission gear 49 is driven to rotate, and as shown in FIG. The contact / separation cam 45 and the secondary transfer roller contact / separation cam 46 are integrally rotated by 180 °. As a result, the ICL contact / separation cam 45 has a smaller phase with respect to the bearing tip 33a of the charging roller 8, and the charging roller 8 is urged against the intermediate transfer belt 5 by the urging force of the compression spring. Similarly, the secondary transfer roller contact / separation cam 46 has a smaller phase with respect to the bearing end 54 a of the secondary transfer roller 7, so that the secondary transfer roller 7 is biased by the compression spring 55 so that the intermediate transfer belt It is urged to 5.
[0041]
In this manner, the bearing of the secondary transfer roller 7 or the charging roller 8 is urged and brought into contact with the cam provided coaxially with the driving roller, and the cam is rotated so that the secondary transfer roller 7 or the charging roller 8 is brought into contact with or separated from the cam. With this configuration, the contact / separation unit can be provided in the intermediate transfer body unit with a very simple configuration, and the drive transmission path can be minimized.
[0042]
(Cam drive transmission means)
Next, the configuration of the cam drive transmitting means for transmitting the drive from the image forming apparatus main body to the cam drive transmitting means will be described. In FIG. 5, the gear ratio of the gear 50 directly connected to the second coupling and the cam drive gears 47a and 47b is 1: 2, and the cam is rotated half a rotation by one rotation of the coupling.
[0043]
As shown in FIG. 9A, one of the D cut portions at both ends of the cam drive shaft 60 is inserted into the gear 50, and the D cut portion at the other end is inserted into the coupling 61 (second coupling). . The coupling 61 is provided with two holes 61a, and a groove 61b is formed on the outer periphery. A slide ring 62 for inserting the cam drive shaft 60 is provided between the coupling 61 and the gear 50, and is urged toward the coupling 61 by a compression spring 63. At this time, the two claw portions 62 a of the slide ring 62 are inserted into the holes 61 a of the coupling 61. Further, the protrusion 62b, which is a locking means provided on the outer periphery of the slide ring 62, penetrates the groove 61b provided on the outer periphery of the coupling 61 and fits into the groove 43a provided on the right side cover 43. I agree.
[0044]
Then, when connecting the drives, as shown in FIG. 9B, the drive coupling 64 slides out of the image forming apparatus main body and protrudes. Then, the claw portion 64 a of the drive coupling 64 is inserted into the hole 61 a of the coupling 61 on the process cartridge B side, and the claw portion 62 a of the slide ring 62 pushes the entire slide ring 62 against the compression spring 63.
[0045]
At this time, the protrusion 62b provided on the outer peripheral portion of the slide ring 62 is disengaged from the groove 43a of the right side cover 43, and the lock is released. When the drive coupling 64 on the image forming apparatus main body rotates in this state, the rotational drive force is transmitted through the claw portion 64a of the drive coupling 64 and the hole 61a of the coupling 61, and further, the gear 50, the idler gears 51 and 52. The rotational driving force is transmitted to the ICL contact / separation cam 45 and the secondary transfer roller contact / separation cam 46 via the.
[0046]
The drive coupling 64 on the image forming apparatus main body side is controlled by one rotation, and is configured to stop at the same phase. Since the gear ratio between the gear 50 and the cam drive gears 47a and 47b is 1: 2, the ICL contact / separation cam 45 and the secondary transfer roller contact / separation cam 46 rotate by 180 ° for each rotation of the drive coupling 64. . The states of these cams can be determined by looking at the current values of the intermediate transfer belt 5, the secondary transfer roller 7, and the charging roller 8.
[0047]
Next, FIG. 3, FIG. 5, FIG. 6, and FIG. 9 show the positioning of the process cartridge B, which is the intermediate transfer unit, with respect to the main body, the first and second couplings, and the driving directions of the gear 50 and the cam driving gear 47a. It will be described using FIG.
[0048]
The positioning of the process cartridge B with respect to the main body is performed by first and second positioning means. As shown in FIG. 6, the first positioning means is coaxial with the drive roller 26 and protrudes from the left side cover 44, and a ring around the drive transmission coupling 59 provided on the right side cover 43. It is constituted by a shape (not shown). That is, both the first coupling (the drive transmission coupling 59) and the first positioning means are coaxial with the drive roller 26. The second positioning means is constituted by positioning protrusions 65a and 65b which are coaxial with the driven roller 27.
[0049]
As shown in FIG. 5, the gear 50 and the coupling 61 (see FIG. 9), which is the second coupling, are located substantially at the center between the first and second positioning means, and are exposed from the right side cover 43. ing.
[0050]
Here, as shown in FIG. 5, the drive is input to the gear 50 via the coupling 61 in the clockwise direction (the direction of the arrow E) in the figure, whereas the cam drive gear is transmitted via the drive transmission coupling 59. The drive is input to the counter 47a in the counterclockwise direction (arrow F direction). Therefore, the rotational moment generated in the process cartridge B by each drive input acts in a direction to cancel each other, and the load on the process cartridge B can be reduced.
[0051]
In FIG. 5, the secondary transfer roller contact / separation cam 46 driven and input via the coupling 61 and the gear 50 is in a state in which the secondary transfer roller 7 is separated. , A rotational moment in the counterclockwise direction is generated in the figure. Accordingly, the rotational moment due to the drive input to the coupling 61 and the rotational moment given to the process cartridge B by the reaction force N act on the process cartridge B, and the load on the process cartridge B can be reduced.
[0052]
【The invention's effect】
As described above, in the intermediate transfer body unit and the image forming apparatus according to the present invention, the drive transmission coupling (second coupling) to the secondary transfer contact / separation means is provided between the first and second positioning means. With this arrangement, the mounting accuracy of the coupling can be improved, the unit can be easily attached and detached, and the requirement for the dimensional accuracy of the members can be reduced.
[0053]
Further, the rotational driving force in the opposite direction is input to the first coupling and the second coupling to cancel the rotational moment, or the second coupling is moved in the direction to cancel the rotational moment due to the reaction force of the secondary transfer means contacting / separating means. , The load on the intermediate transfer body unit can be reduced, and the position of the intermediate transfer body relative to the apparatus main body during driving can be stabilized.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view illustrating a schematic configuration of an image forming apparatus.
FIG. 2 is a side view of the front surface of the intermediate transfer body unit as viewed from the left side.
FIG. 3 is a side view of the front surface of the intermediate transfer unit viewed from the left side.
FIG. 4 is a side view seen from the right side with respect to the front surface of the intermediate transfer body unit.
FIG. 5 is a side view of the front surface of the intermediate transfer body unit as viewed from the right side.
FIG. 6 is a top view of the intermediate transfer unit.
FIG. 7 is a diagram illustrating the operation of a waste toner conveying unit.
FIG. 8 is a diagram illustrating a state in which a secondary transfer unit and a cleaning unit are in contact with an intermediate transfer member.
FIG. 9 is a diagram illustrating cam drive transmission means.
FIG. 10 is a diagram illustrating a conventional image forming apparatus.
[Explanation of symbols]
A: Image forming apparatus
B: Process cartridge
S ... sheet
1. Photosensitive drum
1a ... right side bearing
1b… left rotation axis
2 ... charging roller
3 Exposure means
4. Developing device
5. Intermediate transfer belt
6. Primary transfer roller
7 Secondary transfer roller
8 ... charging roller
9 ... Cleaning blade
10 ... feeding cassette
11 ... feeding roller
12 ... sensor before cash register
13… Registration roller pair
14: Conveyor belt unit
15 ... fixing means
16… Fixing discharge roller
17 ... discharge guide
18 ... discharge roller pair
19 ... discharge tray
20 ... waste toner storage box
21... Image carrier
22… Intermediate transfer member
23… Bearing
24… compression spring
25… Drum shutter
26… Driving roller
26a… Right bearing
26b… Left bearing
27… driven roller
28… Bearing
29 ... compression spring
30… Bearing
31 ... compression spring
32: Cleaning charging roller
33… Bearing
33a ... Bearing tip
34… compression spring
35… Intermediate transfer body frame
35a ... Handshake part
35b ... bearing slide
36… Squeeze sheet
37 ... Image carrier frame
38 ... Screw
39 ... waste toner passage
40 ... wire
41 ... hole
42… stirring plate
43… Right side cover
43a ... groove
44… Left side cover
45… ICL contact / separation cam
46… Secondary transfer roller contact / separation cam
47… Cam drive gear
48… through shaft
49… Drive transmission gear
50 ... gear
51, 52 ... idler gear
54… Bearing
54a… Bearing tip
55 ... compression spring
56… frame of the main unit
57… Bearing slide guide
57a ... Projection
58, 59 ... drive transmission coupling
60… Cam drive shaft
61… Coupling
61a… hole
61b ... groove
62… Slide ring
62a ... claw part
62b ... projecting part
63 ... compression spring
64… Drive coupling
64a ... claw
65a, 65b ... projection

Claims (5)

A unit detachable from the device main body,
An intermediate transfer body on which an image formed on the image carrier is primarily transferred,
A driving roller and a driven roller for stretching the intermediate transfer body,
A secondary transfer unit that transfers the image on the intermediate transfer body to a sheet, a secondary transfer unit contact / separation unit that comes into contact with and separates from the intermediate transfer body,
A first coupling for transmitting drive to the drive roller,
A second coupling for transmitting drive to the secondary transfer means contacting / separating means,
Having a first positioning means and a second positioning means for positioning the unit in the apparatus body,
The intermediate transfer body unit, wherein the second coupling is located between the first and second positioning units. The first coupling is coaxial with the drive roller,
The first positioning means is coaxial with the drive roller,
2. The intermediate transfer body unit according to claim 1, wherein the second positioning unit is coaxial with the driven roller. The intermediate transfer unit according to claim 1, wherein the first coupling and the second coupling receive rotational driving forces in opposite directions. A rotational moment applied to the unit by the reaction force when the secondary transfer means contacting / separating means separates the secondary transfer means,
2. The intermediate transfer unit according to claim 1, wherein the rotational driving force input to the second coupling is offset from a rotational moment applied to the unit by the rotational driving force. Sheet conveying means for conveying the sheet,
An image carrier for carrying an image,
An image forming apparatus comprising: the intermediate transfer body unit according to claim 1.

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