JP4848668B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to a technique for preventing rotation unevenness of an image carrier in an image forming apparatus and a plurality of types of image carriers having different specifications such as characteristics and sizes in a color image forming apparatus, and to rotate the image carrier. The present invention relates to a technique capable of definitely combining a plurality of types of driving devices prepared for each image carrier.

  The color image forming apparatus has, for example, an image carrier for each primary color of yellow (Y), magenta (M), cyan (C), and black (K), and each image carrier forms a toner image of each color. Then, this is superimposed on an intermediate transfer member, and a toner image having four colors is transferred onto a transfer sheet to form a color image.

  Each image carrier constitutes an image forming unit having a charging device, a developing device, a transfer device, a cleaning device, etc., and the image forming unit for each color and the intermediate transfer member are integrated into a process. The cartridge is configured. This process cartridge can be pulled out from the main body of the image forming apparatus, and each image carrier unit and developing device can be attached to and detached from the process cartridge while the process cartridge is pulled out.

  Each image carrier is driven by a driving device provided for each image carrier. The drive device is fixed to the main body side of the image forming apparatus, and transmits the rotation reduced from the main motor through the plurality of gears to the rotation shaft. When the process cartridge is loaded in the image forming apparatus, the rotating shaft is configured to pass through the cylindrical image carrier and be supported by the bearing on the opposite side, and the rotating shaft is rotated by the driving device and rotated. Is transmitted to the image carrier by coupling (for example, Patent Document 1).

  Each image carrier varies in size and characteristics depending on the model and color, and there are various types of drive motors such as different specifications such as voltage. In some cases, the dimensions of the couplings coincide with each other regardless of differences in characteristics and specifications. In such a case, if the combination of the image carrier and the drive motor is used incorrectly, it will cause image defects, and this must be prevented.

  As a method for that purpose, a method of making the coupling shape different for each combination is conceivable. Due to the difference in shape, the wrong combination of couplings cannot be connected and mistakes can be prevented.

However, the coupling is formed by molding using a mold or machining, but in the case of a mold, it is necessary to prepare a separate mold for each shape, which causes an increase in cost. In the case of machining as well, since it is necessary to perform machining according to various couplings, process management becomes complicated, and more types of parts are stored as spare parts, and inventory management becomes complicated.
JP 2005-62806 A

  The present invention has been conceived from such a fact, and in an image forming apparatus having an image carrier, the image carrier and the drive unit of the correct combination among various image carriers and various drive units are used. An object of the present invention is to provide an image forming apparatus provided with a coupling that can be connected only in some cases and can prevent wrong combinations.

In order to achieve the above object, an image forming apparatus according to claim 1 of the present application is an image forming apparatus for transferring a rotation of a driving means to an image carrier to transfer a toner image to a transfer medium.
The driving means and the image carrier are connected by a coupling, and the coupling includes a driving side coupling and an image carrier side coupling, and both couplings are relatively relative to the rotation axis direction of the driving means. Each coupling has a contact surface for transmitting or receiving a driving force, and each of the couplings has an erroneous loading prevention member at a position different from the contact surface. Yes, and the drive-side coupling, if the erroneous loading are connected in combination with incorrect and image carrier-side coupling, as characterized in that the said loading errors preventing member has a configuration that can not connect the two couplings Yes.

  In the image forming apparatus according to claim 2 of the present application, the erroneous loading prevention member has a protrusion formed on one of the driving side coupling and the image carrier side coupling, and the other is provided in order to fit the protrusion. And having a formed hole.

  The image forming apparatus according to claim 3 of the present application is characterized in that when the contact surfaces of the two couplings are in contact with each other, the protrusion and the hole are loosely fitted and do not contact each other.

The image forming apparatus according to claim 4 of the present application is characterized in that the erroneous loading preventing member is formed by post-processing on the driving side coupling and the image carrier side coupling.

The image forming apparatus according to claim 5 of the present application is characterized in that at least one of the drive side coupling and the image carrier side coupling is a molded product by a mold.

The image forming apparatus according to claim 6 of the present application is characterized in that there are a plurality of the contact surfaces on both the drive side coupling and the image carrier side coupling, and the power is transmitted by contacting at a plurality of locations. .

The image forming apparatus according to claim 7 of the present application is characterized in that there are a plurality of the image carriers, and each toner image is transferred to a transfer medium and superimposed.

In the image forming apparatus according to claim 8 of the present application, the transfer medium is an intermediate transfer member, and the intermediate transfer member and the plurality of image bearing members constitute at least a part of a process cartridge. It is characterized in that it can be detached from the image forming apparatus by releasing the connection between each image carrier side coupling and the other side driving side coupling.

[Action]
When the rotation of the motor or the like is transmitted to the image carrier via a gear train or the like, the driving means such as the motor and the image carrier are connected by coupling. Both the driving side coupling and the image carrier side coupling have contact surfaces that abut against each other, and the rotation of the driving side coupling is transmitted to the image carrier side coupling by these contacts, and the image carrier. Will rotate. The drive side coupling and the image carrier side coupling are each provided with an erroneous loading preventing member at a position different from the contact surface. As a result, in the case where the image carrier and the drive means are in an incorrect combination, the coupling cannot be coupled, so that an error in the combination can be prevented.

  The misloading prevention member has a structure in which a protrusion is provided on one coupling, and a hole into which this protrusion is inserted is formed in the other coupling. When the image carrier and the driving means are in the correct combination, the protrusion is a hole. To be able to enter. Alternatively, both couplings are cylindrical, and a convex portion and a concave portion are formed on the front end surface so that the convex portion of one coupling is fitted into the concave portion of the other coupling only when the combination is correct. Prevent misloading.

  When the contact surfaces come into contact with each other and power is transmitted from the driving side coupling to the driven side coupling, it is desirable that the holes and the protrusions are not in contact with each other in order to eliminate rotation unevenness.

  According to the present invention, in an image forming apparatus that transmits the rotation of the driving unit to the image carrier, the driving unit side coupling and the image carrier side coupling can be connected only when the image carrier and the driving unit are in the correct combination. Therefore, wrong combinations can be prevented, and troubles such as image defects can be prevented.

  If the erroneous loading preventing means can be provided by post-processing such as machining after the coupling is formed, the types of coupling can be reduced. When the coupling is molded with a mold, the types of molds can be reduced.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a color image forming apparatus according to an embodiment of the present invention. Note that the present invention is not limited to the image forming apparatus of the present embodiment. The color image forming apparatus shown in FIG. 1 is called a tandem type color image forming apparatus, and includes an automatic document feeder 30, an image reading device 60, image writing devices 3Y, 3M, 3C, 3K, an image carrier 1Y, 1M, 1C, 1K, charging devices 2Y, 2M, 2C, 2K, developing devices 4Y, 4M, 4C, 4K, fixing device 24, belt-like intermediate transfer body 6, paper feeding means 21A, 21B, 21C, transport system 22 Etc.

  The automatic document conveying means 30 is means for automatically conveying a double-sided or single-sided original d. The image reading device 60 is a device in which image information is read by a movable optical system, and the contents of a large number of documents d fed from the document table are reflected by three movable mirrors 60C, and a condensing lens. With 60B, an image is formed on an image sensor 60A made of a CCD and read.

  The image forming unit 10Y that forms a yellow image includes a charging device 2Y, an image writing device 3Y, a developing device 4Y, and a cleaning device 8Y disposed around an image carrier 1Y as an image forming body. The image forming unit 10M that forms a magenta image includes an image carrier 1M as an image forming body, a charging device 2M, an image writing device 3M, a developing device 4M, and a cleaning device 8M. The image forming unit 10C that forms a cyan image includes an image carrier 1C as an image forming body, a charging device 2C, an image writing device 3C, a developing device 4C, and a cleaning device 8C. The image forming unit 10K that forms a black image includes an image carrier 1K as an image forming body, a charging device 2K, an image writing device 3K, a developing device 4K, and a cleaning device 8K. The charging device 2Y and the image writing device 3Y, the charging device 2M and the image writing device 3M, the charging device 2C and the image writing device 3C, and the charging device 2K and the image writing device 3K constitute a latent image forming unit.

  The intermediate transfer member 6 as a transfer medium is an endless belt, is stretched by a plurality of rollers, and is rotatably supported. In the above configuration, the image forming units 10Y, 10M, 10C, and 10K and the intermediate transfer member 6 constitute a process cartridge and can be pulled out from the main body of the image forming apparatus. The image carriers 1Y, 1M, 1C, and 1K and the charging devices 2Y, 2M, 2C, and 2K corresponding to the image carriers 1Y, 1M, 1C, and 1K constitute an image carrier unit, and the image carriers and developing devices 4Y, 4M, 4C, and 4K When the process cartridge is pulled out, it can be detached from the process cartridge.

  A signal of image information formed on the image sensor 60A is sent to an image processing unit (not shown). The image processing unit performs analog processing, A / D conversion, shading correction, image compression processing, and the like, and then sends a signal for each color to the image writing devices 3Y, 3M, 3C, and 3K.

  In the image writing apparatuses 3Y, 3M, 3C, and 3K, a semiconductor laser is used as a laser light source, and a light beam emitted from the semiconductor laser is formed into a scanning light beam by an optical element such as a polygon mirror to form an image as a scanned object. It enters the carriers 1Y, 1M, 1C, 1K and forms an electrostatic latent image of each color.

  The respective color images formed by the image forming units 10Y, 10M, 10C, and 10K are sequentially transferred onto the rotating intermediate transfer body 6 by transfer devices 7Y, 7M, 7C, and 7K as primary transfer devices (1). Next transfer), a synthesized color image is formed. The recording paper P stored in the paper feed cassettes 20A, 20B, and 20C is fed by the paper feed means 21A, 21B, and 21C, passes through the transport system 22, and is timed by the registration roller 23 as a secondary transfer device. Is transferred to the transfer device 7A, and a color image is transferred onto the recording paper P (secondary transfer). The recording paper P onto which the color image has been transferred is fixed by the fixing device 24, is sandwiched between the paper discharge rollers 25, and is placed on a paper discharge tray 26 outside the apparatus.

  On the other hand, after the color image is transferred to the recording paper P by the transfer device 7A, the intermediate transfer body 6 from which the recording paper P has been separated is cleaned by the cleaning device 8A.

  5Y, 5M, 5C, and 5K are toner replenishing units that replenish new toner to the developing devices 4Y, 4M, 4C, and 4K, respectively.

  FIG. 2 is a perspective view showing from the driving means of the image carrier 1 (showing any one of 1Y, 1M, 1C, and 1K) to the driving side coupling. FIG. 3 is an exploded perspective view of the periphery of the drive side coupling in FIG. 2 as seen from a slightly different angle. The drive unit 100 contains a gear train and the like, and transmits the reduced speed rotation to the rotary shaft 110 by a main motor (not shown). The driving unit 100 is fixed to the main body of the image forming apparatus, and the rotating shaft 110 is a cantilever with one end supported by the driving unit 100.

  A driving side coupling 120 is attached to the rotating shaft 110. The drive side coupling 120 shown in the embodiment is made of metal and is made of metal. The drive side coupling 120 is formed on one end side of the hollow cylindrical portion 121 so that two convex portions 122 and 122 projecting in the axial direction face each other, and between the convex portion 122 and the convex portion 122, 2 is formed. Two recesses 123, 123 are formed. One recess 123 is provided with a protrusion 128 as an erroneous loading prevention member.

  A long hole 124 extending in the axial direction is formed through the main body 121, and a through hole 111 is formed in the rotating shaft 110 so as to overlap the long hole 124. In order to attach the driving side coupling 120 to the rotating shaft 110, first, the driving side coupling 120 is inserted from the tip of the rotating shaft 110, and the long hole 124 and the through hole 111 are overlapped. Next, when the pin 125 is inserted into the through hole 111, both ends of the pin 125 protrude on both sides of the drive side coupling 120. When the E-rings 126 and 126 are fitted in the grooves 125a and 125a so that the grooves 125a and 125a at both ends of the pin 125 are substantially the same height as the outer peripheral surface of the main body 121, the drive side coupling 120 is shown in FIG. As shown, it is locked to the rotating shaft 110.

  Before the drive side coupling 120 is inserted into the rotating shaft 110, a coil spring 112 is inserted, and when the drive side coupling 120 is fitted to the image carrier side coupling 130, the coupling of both couplings is maintained. Energize to do.

  FIG. 4 is a perspective view showing a state before the coupling 150 including the driving side coupling 120 and the image carrier side coupling 130 is fitted. In the embodiment, the image carrier side coupling 130 is made of metal manufactured by molding. The image carrier side coupling 130 is fitted into one end of a cylindrical image carrier 1 and is integrated with the image carrier 1, and has a shape complementary to the drive side coupling 120. In other words, the image carrier side coupling 130 has two convex portions 132 and 132 as convex portions and two concave portions 133 and 133 formed therebetween. The convex portions 132 and 132 are loosely fitted into the concave portions 123 and 123 of the driving side coupling 120, and the convex portions 122 and 122 of the driving side coupling 120 are loosely fitted into the concave portions 133 and 133.

  When the driving side coupling 120 and the image carrier side coupling 130 are connected and the driving side coupling 120 rotates, one of the convex portions 122 of the driving side coupling 120 becomes the contact surface 122a, and the image carrier side coupling 130 is obtained. One end surface of the convex portion 132 becomes the contact surface 132a, and both surfaces come into contact with each other to transmit the rotation. Since there are two convex portions 122 and 132, two contact surfaces 122a and 132a can be formed respectively.

  A hole 135 is formed at a position different from the contact surface 132 a of the image carrier side coupling 130. The hole 135 has a diameter that allows the protrusion 128 of the drive side coupling 120 to be loosely fitted, and is slightly deeper than the length of the protrusion 128. That is, the protrusion 128 and the hole 135 constitute an erroneous loading preventing member. Therefore, the position of the protrusion 128 and the position of the hole 135 are provided at positions that can be loosely fitted only when the combination of the image carrier 1 and the driving means 100 is correct. If the combination is wrong, the projection 128 cannot enter the hole 135, and the coupling 150 cannot be coupled, thereby preventing erroneous loading.

  5A and 5B are views of the drive side coupling 120, where FIG. 5A is a front view seen from the axial direction, and FIG. 5B is a side view. As shown in these drawings, the drive side coupling 120 has a cylindrical shape and includes two convex portions 122 and 122 and concave portions 123 and 123 formed therebetween. In FIG. 5A, the top surfaces of the convex portions 122 and 122 are shown by cross-hatching for easy understanding. Each one end surface of the convex portions 122 and 122 is a contact surface 122a, and these contact surfaces 122a and 122a are in contact with one end surface 132a of the two convex portions 132 of the image carrier side coupling 130 and rotate. Transmission takes place.

  In the state where the driving side coupling 120 and the image carrier side coupling 130 are connected, the tips of the convex portions 122 and 132 and the bottom surfaces of the concave portions 123 and 133 are in contact with each other. However, since these contact surfaces are parallel to the rotation direction, the driving force cannot be transmitted or transmitted.

  In addition, the height of the protrusion 128 is preferably the same as or slightly lower than the height of the convex portion 122. If the height of the protrusion 128 is extremely lower than the convex portion 122, both couplings can be connected even though there is no hole 135, and it is possible to transmit the rotation, thereby preventing an incorrect combination. become unable. On the other hand, when the height of the protrusion 128 is higher than the height of the convex portion 122, the drive side coupling 120 and the image carrier side coupling 130 may not be properly fitted. That is, when the process cartridge is accommodated in the image forming apparatus main body, both the couplings 120 and 130 are not sufficiently fitted, and immediately after the driving side coupling 120 starts to be driven, Further, when the projection 128 and the hole 135 are fitted, if the projection 128 is higher than the convex portion 122, the projection 128 collides with the convex portion 132 of the image carrier side coupling 130, and there is a situation in which the projection 128 is not properly fitted. To get.

  In FIG. 5 (a), the rotating shaft 110 is indicated by an imaginary line. The rotating shaft 110 is loosely fitted to the drive side coupling 120, and there is a gap of δ over the entire circumference. This gap allows play in the connecting portion with the coupling 150 connected.

  In a state where the process cartridge is accommodated in the image forming apparatus main body, the rotating shaft 110 penetrates the image carrier 1 and the tip of the rotating shaft 110 is supported by a bearing provided in the image forming apparatus main body. The drive side coupling 120 and the image carrier side coupling 130 are in a fitted state. When the process cartridge is pulled out from the image forming apparatus, each rotating shaft 110 is pulled out from the image carrier 1Y, 1M, 1C, 1K of each color.

  In order to fit the drive side coupling 120 and the image carrier side coupling 130, the tip of the rotating shaft 110 is inserted into the central hole of the image carrier side coupling 130. The rotation shaft 110 passes through the cylindrical image carrier 1. The convex portion 122 of the drive side coupling 120 and the convex portion 132 of the image carrier side coupling 130 enter the counterpart concave portions 133 and 123, respectively. At the same time, the projection 128 enters the hole 135, and the couplings are connected. . When the coupling 150 is fitted, the process cartridge is pushed in and accommodated in a predetermined position of the image forming apparatus. As a result, the tip of the rotating shaft 110 protruding from the opposite side of the image carrier 1 is fitted and supported by a bearing (not shown) provided on the frame. The driving side coupling 120 advances and retracts in the axial direction along the long hole 124 by the urging force of the coil spring 112, and the coupling 150 can maintain the fitted state.

  Note that a switching means such as a solenoid can be provided in place of the coil spring 112 so that the coupling 150 can be contacted and separated.

  When the driving side coupling 120 is connected to the image carrier side coupling 130 and the driving side coupling 120 is slightly rotated, first, the one abutting surface 122a and the abutting surface 132a facing the abutting surface abut against each other. At this time, the other contact surface 122a and the contact surface 132a opposite to the other contact surface 122a are not necessarily in contact with each other. This is because it is affected by errors caused by accumulation of component tolerances such as variations in machining accuracy.

  Such a problem per one point and a solution to the problem are described in Patent Document 1 which is the prior application of the inventor of the present application, and the outline thereof is as follows.

  When the other abutment surface is not abutted, the drive side coupling 120 is per one point if there is no play in the connecting portion of the coupling 150. The rotation center of the image carrier 1 is different from the rotation center of the rotation shaft 110 or the coupling 150 due to the cleaning blade or its own weight. If the backlash of the connection portion of the coupling 150 is small, the number of points becomes one, and the rotation center moves from the rotation center of the image carrier 1, and the rotation unevenness deteriorates.

  On the other hand, in the embodiment of the present invention, the rotation shaft 110 and the drive side coupling 120 are provided with a gap δ over the entire circumference as described above. In addition, both the fitting between the convex portion 122 and the concave portion 133 and the fitting between the convex portion 132 and the concave portion 123 are loosely fitted so that a gap is formed. Therefore, the driving-side coupling 120 can be moved by the biasing force and the rotational force of the coil spring 112 even after one of the contact surfaces comes into contact, and the contact surface 122a and the contact surface 133a on the opposite side also contact each other. be able to. As a result, contact at a plurality of locations is ensured, and per point can be prevented.

  In the conventional color image forming apparatus, when the image carrier 1 is in close contact with the transfer medium such as the intermediate transfer member 6 to transfer the toner image, there is no play in the conventional coupling. Rotation unevenness easily occurs, and a deviation occurs between the image carrier 1 and the intermediate transfer member 6 during transfer, causing image defects. On the other hand, in the coupling 150 of the present invention, since contact at a plurality of points can be ensured, the surface velocities of the image carrier 1 and the intermediate transfer member 6 can be highly matched to reduce image displacement. .

  In the above embodiment, the depth of the hole 135 is larger than the length of the protrusion 128, the diameter of the hole 135 is larger than the diameter of the protrusion 128, and the protrusion 128 is loosely fitted in the hole 135. When the contact surfaces 122a and 132a are in contact with each other and the rotational force is transmitted, the protrusion 128 and the hole 135 are kept out of contact with each other. This is because if the projection 128 and the hole 135 come into contact with each other, there may be cases where the contact at the contact surfaces 122a and 132a cannot be made, and one point is obtained.

  The drive side coupling 120 and the image carrier side coupling 130 may be formed by cutting, but it is desirable to use mold forming because cost can be reduced. In that case, the protrusion 128 and the hole 135 may be formed by machining after the drive side coupling 120 and the image carrier side coupling 130 are formed.

  Various combinations can be made by slightly changing the positions of the projections 128 and the holes 135 of the coupling 150. However, if they are to be formed at the same time as the coupling is formed, many types of molds are created. On the other hand, if it is post-processing, it is only necessary to form a coupling with the same shape, and then perform drilling and standing processing of protrusions, thereby reducing the types of molds. .

  FIG. 6 shows a second embodiment of the present invention. Since most of them are common to the first embodiment, the differences will be mainly described. The two convex portions 222 and 222 ′ of the drive side coupling 220 are different in size (in the embodiment, the length along the circumference), and the two concave portions 223 and 223 ′ formed therebetween are also different. is doing. On the other hand, the two convex portions 232 and 232 'of the image carrier side coupling 230 are also different in size, and the two concave portions 233 and 233' formed therebetween are also different. The convex portions 232 and 232 'are loosely fitted into the concave portions 223 and 223' of the driving side coupling 220, and the convex portions 222 and 222 'of the driving side coupling 220 are loosely fitted into the concave portions 233 and 233'. Thus, various combinations can be obtained by changing the ratio of the sizes of the two convex portions and the two concave portions. These two convex portions and concave portions having different sizes constitute an erroneous loading preventing member.

  In the configuration of FIG. 6, for example, when the protrusions 222 and 222 ′ of the drive side coupling 220 are molded with a mold, the protrusions of the same size are kept at the time of molding. What is necessary is just to cut out the part of A of a figure by process. Further, when the portion B is also excised, it becomes the same as the first embodiment. By changing the lengths of the A and B portions along the circumference, a plurality of types of combinations can be obtained.

  The couplings 150 and 250 of the present invention can also be used in the drive portion of the intermediate transfer member 6 as an image carrier, and the transfer medium in that case is a recording paper. Moreover, although the example of the protrusion 128 and the hole 135 and the example of the convex part 222,222 'and the concave part 233,233' from which a magnitude | size differed as a structure of a misload prevention member, it is not limited to these forms.

1 is a diagram illustrating a color image forming apparatus according to an embodiment of the present invention. FIG. 4 is a perspective view showing the drive from the image carrier driving means to the driving side coupling. It is a disassembled perspective view of a drive side coupling. FIG. 6 is a perspective view showing a state before coupling of a coupling composed of a driving side coupling and an image carrier side coupling. It is a figure of a drive side coupling, (a) is the front view seen from the axial direction, (b) is a side view. FIG. 6 is a perspective view of a driving side coupling and an image carrier side coupling showing a second embodiment of the present invention.

Explanation of symbols

1 Image carrier 6 Intermediate transfer member (transfer medium)
DESCRIPTION OF SYMBOLS 100 Drive means 110 Rotating shaft 120,220 Drive side coupling 121 Hollow cylindrical part 122,222,222 'Convex part 122a, 222a Contact surface 123,223,223' Concave part 130,230 Image carrier side coupling 132,232, 232 ′ convex portion 132a, 232a contact surface 133, 233, 233 ′ concave portion 150, 250 coupling

Claims (8)

In the image forming apparatus for transferring the rotation of the driving means to the image carrier and transferring the toner image to the transfer medium,
The driving means and the image carrier are connected by a coupling, and the coupling includes a driving side coupling and an image carrier side coupling,
Both couplings move relative to each other in the direction of the rotation axis of the driving means and are separated from each other,
Each of the couplings has a contact surface for transmitting or receiving the driving force,
If each of the two coupling said to have a loading preventing member erroneous contact surface and different position, and the drive-side coupling, and loading errors connected with the combination the wrong and image carrier-side coupling, wherein An image forming apparatus characterized in that the coupling cannot be connected by an erroneous loading preventing member .   The erroneous loading preventing member has a protrusion formed on one of the drive side coupling and the image carrier side coupling, and a hole formed on the other for fitting the protrusion. The image forming apparatus according to claim 1.   3. The image forming apparatus according to claim 2, wherein when the contact surfaces of the two couplings are in contact with each other, the protrusion and the hole are loosely fitted and do not contact each other.   4. The image forming apparatus according to claim 1, wherein the erroneous loading prevention member is formed by post-processing on the drive side coupling and the image carrier side coupling.   5. The image forming apparatus according to claim 1, wherein at least one of the driving side coupling and the image carrier side coupling is a molded product using a mold.   6. The power transmission is performed according to claim 1, wherein the driving side coupling and the image carrier side coupling have a plurality of the contact surfaces, and the power is transmitted by contacting at a plurality of locations. Image forming apparatus.   The image forming apparatus according to claim 1, wherein there are a plurality of the image carriers, and the respective toner images are transferred to a transfer medium and superimposed.   The transfer medium is an intermediate transfer member, and the intermediate transfer member and the plurality of image carriers constitute at least a part of a process cartridge, and the process cartridge includes a coupling between each image carrier side coupling and a counterpart side. 8. The image forming apparatus according to claim 7, wherein the image forming apparatus is detachable from the image forming apparatus by releasing the connection with the driving side coupling.

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