JP7207928B2 - image forming device - Google Patents

Description

The present invention relates to an image forming apparatus such as a printer, a copier, a facsimile machine, or a multifunction machine using electrophotography.

An image forming apparatus forms an electrostatic image by selectively exposing a photosensitive drum that is uniformly charged by a charging device to light, develops the electrostatic image with a developer by a developing device, and transfers the image to an intermediate transfer member, for example. After transfer, the image is transferred to a recording medium to form an image. The photosensitive drum is accommodated in, for example, a drum cartridge, and is detachably attached to the main body of the image forming apparatus. Here, the photosensitive drum and the drum driving gear of the apparatus main body are connected by a connecting portion, and the rotational driving force of the drum driving gear is transmitted to the photosensitive drum via the connecting portion. As such a connecting portion, there is known a structure in which a convex portion projecting in the axial direction and a concave portion recessed in the axial direction are provided, and the photosensitive drum and the drum driving gear are connected by detachably fitting these portions. (see Patent Document 1).

This connecting portion is provided on the drum drive gear and includes a substantially triangular projection as viewed from the rotation axis direction, and a substantially triangular recess as viewed from the rotation axis direction that can be fitted with the projection provided on the photosensitive drum. have. The projections and recesses are twisted in the rotational axis direction of the photosensitive drum. For this reason, when the photosensitive drum rotates in the forward rotation direction, the convex portion and the concave portion are retracted toward each other in the rotation axis direction. Further, the drum cartridge housing the photosensitive drum is movable with respect to the apparatus main body in the rotation axis direction of the drum drive gear, and the connecting portion is connected and disconnected as the drum cartridge is attached to and detached from the apparatus main body. Further, the drum driving gear is biased toward the photosensitive drum by a biasing spring such as a compression coil spring.

When the drum cartridge is attached to the main body of the apparatus, the convex portion and the concave portion of the connecting portion are opposed to each other in the rotation axis direction. At this time, the phases of the vertices of the triangles of the convex portion and the concave portion may not match each other. In this case, in order to prevent the drum cartridge from being mounted due to interference between the convex portion and the concave portion, the drum drive gear is pushed in the direction opposite to the photosensitive drum in the rotation axis direction against the biasing spring. , a drum cartridge can be installed. By rotating the drum driving gear in this state, when the phases of the convex portion and the concave portion match, the drum driving gear moves toward the photosensitive drum due to the biasing force of the biasing spring, and the connection of the connecting portion is completed. .

JP 2011-154407 A

However, in the configuration of the connecting portion between the photosensitive drum and the drum drive gear described in Japanese Patent Application Laid-Open No. 2002-200010, the biasing spring is provided in contact with the drum drive gear. Therefore, as the drum driving gear rotates, the biasing spring and the drum driving gear rotate while generating friction. In particular, in Patent Document 1, since the biasing spring is a compression coil spring, the end of the wire that constitutes the compression coil spring slides on the drum drive gear, which may cause excessive wear or generate loud noise. be. For this reason, a configuration that does not generate friction between the drum driving gear and the biasing spring has been desired.

The present invention provides an image forming apparatus comprising a driving gear for driving a rotating body and a biasing spring for biasing the driving gear in the direction of the rotation axis, wherein the driving gear and the end of the biasing member excessively rub against each other. An object of the present invention is to provide an image forming apparatus capable of suppressing the occurrence of an image.

An image forming apparatus of the present invention comprises: an apparatus main body; a rotatable rotating body detachably provided in the apparatus main body; a driving gear for driving the rotating body; a biasing member for biasing the driving gear toward the rotating body; and rotation of the rotating body. With respect to the axial direction, the drive gear is provided between the drive gear and the biasing member, and has a sliding surface slidable with the drive gear, the drive gear being in contact with the drive gear when the rotating body is drivingly connected to the drive gear. is maintained in contact with the sliding surface, and when the drive gear rotates in the forward direction, the device main body and the rotating body are engaged in the rotational direction of the forward rotation. and a sliding member whose directional rotation is restricted.

According to the present invention, in an image forming apparatus including a driving gear for driving a rotating body and a biasing spring for biasing the driving gear in the direction of the rotation axis, the ends of the driving gear and the biasing member are excessively It is possible to provide an image forming apparatus capable of suppressing rubbing.

1 is a schematic cross-sectional view of an image forming apparatus according to an embodiment; FIG. 1 is a schematic cross-sectional view of a drum cartridge according to an embodiment; FIG. 4 is a perspective view of a mounting portion of the drum cartridge according to the embodiment; FIG. It is a perspective view of the connection part which concerns on embodiment. (A) is a perspective view of a drum holding member, and (B) is a perspective view of a drum drive gear. (A) is a side view of the drum holding member, and (B) is a plan view of the drum holding member. FIG. 4 is a plan view showing the connecting portion during forward rotation of the drum drive gear according to the embodiment; FIG. 10 is a plan view showing the connecting portion during reverse rotation of the drum drive gear according to the embodiment; It is a side view which shows the connection part at the time of reverse rotation of the drum drive gear which concerns on embodiment. It is a side view which shows the drum drive gear which concerns on embodiment. FIG. 4 is a perspective view showing normal rotation of the drum drive gear according to the embodiment; FIG. 5 is a perspective view showing reverse rotation of the drum drive gear according to the embodiment; It is a side view which shows the time of reverse rotation of the drum drive gear which concerns on embodiment. 7 is a graph showing the time course of the rotation speed of each part during reverse rotation of the drum drive gear according to the embodiment. It is a side view which shows the state before reverse rotation of the drum drive gear which concerns on embodiment. 7 is a graph showing the passage of time of the resultant force acting in the pull-out direction during reverse rotation of the drum drive gear according to the embodiment. FIG. 8 is a perspective view showing a modified example of the drum driving gear according to the embodiment, in which (a) is a curved surface projecting from the downstream side to the upstream side in the θ direction, and (b) is a reverse rotation restricted portion; This is the case where the restricting portion is a curved surface recessed from the upstream side to the downstream side in the θ direction. It is a perspective view which shows the modification of the drum drive gear which concerns on embodiment. (a) is a case where the reverse rotation restricting portion is an inclined plane, (b) is a case where the reverse rotation restricting portion is a curved surface projecting from the upstream side to the downstream side in the θ direction, and (c) is a reverse rotation restriction. This is the case where the portion is a curved surface recessed from the downstream side to the upstream side in the θ direction. FIG. 11 is a perspective view showing a modification of the drum driving gear according to the embodiment, in which both the reverse rotation restricted portion and the reverse rotation restricting portion are inclined planes.

An embodiment of the present invention will be described with reference to FIGS. 1 to 16. FIG. First, a schematic configuration of an image forming apparatus 100 of this embodiment will be described with reference to FIGS. 1 to 3. FIG. In the present embodiment, the forward rotation direction (first rotation direction) is the rotation direction of the rotating member during image formation, and the reverse rotation direction (second rotation direction) is the opposite of the forward rotation direction. direction is the direction of rotation.

[Image forming apparatus]
The image forming apparatus 100 is of a tandem type intermediate transfer system in which the image forming units formed into cartridges as drum cartridges 1y, 1m, 1c, and 1k are arranged along the downward surface of an intermediate transfer belt 8 as an intermediate transfer body in an installed state. is a full-color printer. The image forming apparatus 100 has an apparatus main body 101 .

The drum cartridges 1y, 1m, 1c, and 1k have almost the same configuration except that the toner colors used in the developing devices 4y, 4m, 4c, and 4k are yellow, magenta, cyan, and black. In the following, the drum cartridge 1y will be described, and the other drum cartridges 1m, 1c, and 1k will be described by replacing the y at the end of the reference numerals with m, c, and k. The drum cartridge 1y surrounds the photosensitive drum 2y and has a charging roller 3y, a developing device 4y, and a cleaning device 6y. Details of the drum cartridge 1y will be described later.

An exposure device 7 is arranged below the drum cartridge 1y, and a primary transfer roller 5y is arranged at a position facing the photosensitive drum 2y with the intermediate transfer belt 8 interposed therebetween. The photosensitive drum 2y has a photosensitive layer with a negative charging polarity formed on the outer peripheral surface of an aluminum cylinder. 2). Toner bottles 70y, 70m, 70c and 70k are arranged below the developing devices 4y, 4m, 4c and 4k, respectively. The toners consumed by the developing devices 4y, 4m, 4c, and 4k for image formation are replenished from toner bottles 70y, 70m, 70c, and 70k, respectively.

The intermediate transfer belt 8 is stretched over and supported by a tension roller 11, a drive roller 10 also serving as a secondary transfer counter roller, and a tension roller 13, and is driven by the drive roller 10 to rotate in the direction of arrow R2.

The secondary transfer portion T2 is configured by a secondary transfer roller 12 in contact with an intermediate transfer belt 8 whose inner surface is stretched by a drive roller 10 . By applying a positive DC voltage to the secondary transfer roller 12, a transfer electric field for the toner image is formed between the secondary transfer roller 12 and the drive roller 10 connected to the ground potential. The belt cleaning device 9 removes transfer residual toner adhering to the surface of the intermediate transfer belt 8 that has passed through the secondary transfer portion T2 by rubbing a cleaning blade against the intermediate transfer belt 8 .

Next, a procedure for executing image formation by the image forming apparatus 100 will be described below. In the drum cartridge 1 y , a yellow toner image is formed on a photosensitive drum 2 y as an image carrier and transferred to the intermediate transfer belt 8 . In the drum cartridges 1m, 1c, and 1k, a magenta toner image, a cyan toner image, and a black toner image are formed on the photosensitive drums 2m, 2c, and 2k, respectively, and transferred to the intermediate transfer belt 8. FIG.

The separation roller 19 separates the sheets S, which are recording materials conveyed from the sheet cassette 18 , one by one, and feeds them to the registration rollers 14 . The registration rollers 14 receive and wait the sheet S in a stopped state, and send the sheet S to the secondary transfer portion T2 in timing with the toner image on the intermediate transfer belt 8 .

The four-color toner images primarily transferred to the intermediate transfer belt 8 are conveyed to the secondary transfer portion T2 and secondarily transferred onto the sheet S collectively. The sheet S on which the four-color toner images are secondarily transferred is conveyed to the fixing device 16 . The fixing device 16 forms a heating nip by pressing a pressure roller 16b against a fixing roller 16a provided with a heater. The sheet S is subjected to heat and pressure at the heated nip to melt the toner image and fix the full color image to its surface. The sheet having the toner image fixed on its surface by the fixing device 16 is discharged to the upper tray 17 through the discharge roller 15 .

As shown in FIG. 2, the charging roller 3y is driven to rotate by the photosensitive drum 2y, and is applied with an oscillating voltage obtained by superimposing an AC voltage on a DC voltage with a negative polarity, thereby uniformly charging the photosensitive drum 2y with a negative polarity. Charge to a potential. The exposure device 7 (see FIG. 1) uses a rotating mirror to scan a laser beam obtained by ON-OFF modulating scanning line image data representing a yellow separation color image, thereby electrostatically forming an image on the surface of the charged photosensitive drum 2y. write an image. The exposure device 7 similarly writes electrostatic images on the respective photosensitive drums 2m, 2c, and 2k for magenta, cyan, and black separated color images. The developing device 4y transfers the toner onto the photosensitive drum 2y to develop the electrostatic image into a toner image.

As shown in FIG. 1, the primary transfer roller 5y presses the intermediate transfer belt 8 to form a primary transfer portion T1y between the photosensitive drum 2y and the intermediate transfer belt 8. As shown in FIG. By applying a positive DC voltage to the primary transfer roller 5y, the negative toner image carried on the photosensitive drum 2y is primarily transferred onto the intermediate transfer belt 8 passing through the primary transfer portion T1y. The cleaning device 6y removes transfer residual toner adhering to the surface of the photosensitive drum 2y that has passed through the primary transfer portion T1y by sliding a cleaning blade against the photosensitive drum 2y. The removed toner is conveyed by the toner conveying screw 60y to a toner discharge port (not shown) and then discharged from the toner discharge port. Each member such as the photosensitive drum 2y, the charging roller 3y, the developing device 4y, the cleaning device 6y, and the like is integrally combined into a cartridge to form a drum cartridge 1y. The drum cartridges 1y, 1m, 1c, and 1k can form an image on a sheet when a drum drive gear 22, which will be described later, is driven to rotate in the forward rotation direction by a drive source.

As shown in FIG. 3, the drum cartridge 1y is detachably attached to a cartridge attachment portion 34y provided in the image forming apparatus 100. As shown in FIG. In FIG. 3, only the yellow drum cartridge 1y among the drum cartridges is exemplified. Attached detachably. The direction in which the drum cartridges 1y, 1m, 1c, and 1k are mounted in the cartridge mounting portions 34y, 34m, 34c, and 34k is the insertion direction (one end in the direction of the rotation axis) D1, and the opposite direction is the extraction direction (the direction of the rotation axis). the other end) D2.

The cartridge mounting portions 34y, 34m, 34c and 34k have opening/closing members 30y, 30m, 30c and 30k and guide members 31y, 31m, 31c and 31k. When opening/closing members 30y, 30m, 30c, and 30k are opened, guide members 31y, 31m, 31c, and 31k for cartridge mounting are attached to the lower portion of the cartridge mounting space. The guide members 31y, 31m, 31c and 31k are provided with guide portions 32y, 32m, 32c and 32k that serve as guides for inserting the drum cartridges. The drum cartridges are guided and inserted by the guide portions 32y, 32m, 32c, and 32k. For example, a regulated portion (not shown) provided on the drum cartridge 1y inserted to the innermost portion of the guide portion 32y is regulated by a regulating member 33y provided on the guide portion 32y, and the drum cartridge 1y is pulled out in the pull-out direction D2. fixed so that it does not move. Then, the drum cartridges 1y, 1m, 1c and 1k are attached to the image forming apparatus 100 by closing the opening/closing members 30y, 30m, 30c and 30k.

[Structure of Connection Portion Between Drum Cartridge and Apparatus Main Body]
Next, the configuration of the connecting portion 24 between the drum cartridge and the apparatus main body 101 will be described in detail with reference to FIGS. 4 and 5. FIG. In the following description, the configuration of the Y station will be described on the assumption that the multiple photosensitive drums have the same configuration. Elements such as the photosensitive drum 2, the drum holding member 21, and the drum driving gear (driving gear) 22, which are provided in separate drum cartridges for each toner color, are represented by common reference numerals regardless of the toner color used. is attached and explained. The drum drive gear 22 is rotatably supported by the support member 101a (see FIG. 10) of the apparatus main body 101 (see FIG. 1) and is movably supported by the support member 101a in the rotational axis direction of the photosensitive drum 2. and driven to rotate by a drive source (not shown). Further, the drum driving gear 22 includes a connection portion 24 that is drivingly connected to the photosensitive drum 2 in the rotation axis direction of the photosensitive drum 2 , and drives the photosensitive drum 2 . In this embodiment, the drum holding member 21 and the photosensitive drum 2 are rotating bodies.

As shown in FIG. 4, a drum holding member 21 is integrally fixed to the tip of the photosensitive drum 2 in the insertion direction D1. is provided. The drum driving gear 22 is provided with a cylindrical boss portion 224 protruding from the central portion in the pull-out direction D2. The end portions of the boss portion 21 a of the drum holding member 21 and the boss portion 224 of the drum driving gear 22 are fitted to each other, whereby the photosensitive drum 2 and the drum holding member 21 are connected, and the drum driving gear 22 receives rotational driving force. By receiving it, it rotates as one. That is, the connecting portion 24 has a fitting concave portion 221 and a fitting convex portion 211 (see FIG. 5), which will be described later, and drives and connects the drum driving gear 22 and the drum holding member 21 . The clockwise direction when the drum drive gear 22 side is viewed from the photosensitive drum 2 side in the rotational axis direction is defined as the θ direction.

As shown in FIG. 5, a hole having a substantially triangular cross section is provided at the leading end of the boss portion 224 of the drum drive gear 22 in the pull-out direction D2 to form a fitting recess (recess) 221 . The fitting recess 221 has a shape recessed in the rotation axis direction. At the tip of the boss portion 21a of the drum holding member 21 in the insertion direction D1, there is provided a fitting convex portion (convex portion) 211 having a substantially triangular prism shape. The fitting protrusion 211 has a shape protruding in the rotation axis direction. The fitting convex portion 211 can be detachably fitted into the fitting concave portion 221 and can be driven and connected, and the photosensitive drum 2 and the drum holding member 21 are connected by coupling. As shown in FIGS. 5 and 6, the fitting projection 211 of the boss 21a of the drum holding member 21 has a side surface twisted in the -.theta. direction as it advances in the insertion direction D1. Similarly, the fitting recess 221 of the drum drive gear 22 has a shape in which the side surface of the hole is twisted in the -θ direction as it progresses in the insertion direction D1. That is, the fitting convex portion 211 and the fitting concave portion 221 are twisted in the same direction about the rotation axis of the drum drive gear 22, and when the drum drive gear 22 rotates in the reverse rotation direction, they are axially aligned with each other. It is formed in a shape that generates a force in the direction of pulling apart. In other words, the fitting convex portion 211 and the fitting concave portion 221 are twisted in the same direction about the rotation axis of the drum holding member 21 so that a pulling force is generated with each other when the drum driving gear 22 rotates forward. is. The fitting recess 221 may be provided on the drum holding member 21 side, and the fitting projection 211 may be provided on the drum driving gear 22 side. In other words, the fitting protrusion 211 may be provided on one of the drum holding member 21 and the drum drive gear 22 , and the fitting recess 221 may be provided on the other of the drum holding member 21 and the drum drive gear 22 .

As shown in FIG. 7, during image formation by the image forming apparatus 100, the drum driving gear 22 rotates in the .theta. direction. At this time, the forward rotation abutting portion 222 provided in the fitting concave portion 221 of the drum drive gear 22 and the forward rotation abutting portion 212 provided in the fitting convex portion 211 of the drum holding member 21 abut against each other. As a result, the rotational drive of the drum driving gear 22 is transmitted to the drum holding member 21, and the photosensitive drum 2 rotates. That is, the drum holding member 21 is detachably drivingly connected to the pull-out direction D2 side of the drum driving gear 22 and rotates as the drum driving gear 22 rotates. At this time, the drum drive gear 22 rotates in the θ direction, and the drum holding member 21 applies a force in the insertion direction D1 so that the fitting projection 211 of the drum holding member 21 bites into the fitting recess 221 of the drum driving gear 22 . will receive. As a result, for example, the alignment between the drum drive gear 22 and the drum holding member 21 may be shifted, or the drum holding member 21 may receive disturbance in the pull-out direction D2. It is possible to prevent the release from being performed without

[Force acting when the photosensitive drum rotates in reverse]
During image formation by the image forming apparatus 100, the drum drive gear 22 rotates in the θ direction. It rotates in the -θ direction for about 0.1 to 1 second and stops. At this time, the drum drive gear 22 rotates up to about 120 degrees, for example.

The purpose of this operation will be explained. At the end of image formation, the toner scraped off by the cleaning blade 6 may adhere to the photosensitive drum 2 at the contact position between the photosensitive drum 2 and the cleaning blade 6 . In this case, the toner adhering to the photosensitive drum 2 may repeatedly rush into the contact position between the cleaning blade 6 and the photosensitive drum 2 due to the rotation of the photosensitive drum 2 during the next image formation. In this case, the rotational torque of the photosensitive drum 2 fluctuates and the rotation at a constant speed cannot be maintained. There is a possibility that an elongated streak may occur.

In order to suppress such deterioration in image quality, the photosensitive drum 2 is rotated in the -θ direction after the image formation of the image forming apparatus 100 is completed. As a result, the toner accumulated at the contact position between the photosensitive drum 2 and the cleaning blade 6 is diffused over the circumferential surface of the photosensitive drum 2 to prevent the toner from adhering to the photosensitive drum 2, thereby improving the image quality. can be suppressed.

As shown in FIG. 8, when the drum drive gear 22 rotates in the −θ direction, the reverse rotation contact portion 223 of the fitting recess 221 provided in the drum drive gear 22 and the fitting projection of the drum holding member 21 A reverse rotation abutted portion 213 provided on the portion 211 abuts thereon. At this time, the force that the fitting convex portion 211 of the drum holding member 21 receives from the fitting concave portion 221 of the drum drive gear 22 is a force that separates the drum holding member 21 in the pull-out direction D2. At this time, as shown in FIG. 9, force F2 acts from the reverse rotation contact portion 223 to the reverse rotation contact portion 213, and the force F2 acts from the reverse rotation contact portion 213 to the reverse rotation contact portion 223. A force F1 acts due to the reaction of . Here, the forces F1 and F2 are the resultant forces of the three reverse rotation abutment portions 223 and the three reverse rotation abutted portions 213, respectively.

As a result, the drum drive gear 22 receives the decoupling force f1 of the insertion direction D1 component of the force F1, and the photosensitive drum 2 receives the decoupling force f2 of the pullout direction D2 component of the force F2. Therefore, there is a possibility that the drum drive gear 22 and the photosensitive drum 2 may move in the direction of releasing the coupling by receiving the coupling releasing forces f1 and f2 as reaction forces. In this embodiment, for example, the regulated portion (not shown) provided on the drum cartridge 1y inserted to the innermost portion of the guide portion 32y is prevented from moving in the pull-out direction D2 by the regulating member 33y provided on the guide portion 32y. (see Figure 3). As a result, even if disconnection forces f1 and f2 are generated between the drum drive gear 22 and the photosensitive drum 2, the disconnection is prevented.

As shown in FIG. 10, on the insertion direction D1 side of the drum driving gear 22, a cylindrical shaft portion 226 having substantially the same diameter as the boss portion 224 and protruding in the insertion direction D1 is provided. This cylindrical shaft portion 226 is rotatably supported by a bearing member 225 fixed to the apparatus main body 101, and rotates in the θ direction during image formation. The inner peripheral sides of the boss portion 224 and the cylindrical shaft portion 226 communicate with each other in the rotation axis direction, and the inner peripheral side of the boss portion 224 is provided with a cylindrical rib 227 protruding from the connecting portion 24 in the insertion direction D1. there is An end face of the rib 227 on the insertion direction D1 side is a ring-shaped first abutting face 227a perpendicular to the rotation axis direction. That is, the drum drive gear 22 has a first abutment surface 227a facing the insertion direction D1.

Inside the cylindrical shaft portion 226, a coil spring (biasing member) 40 made of a compression coil spring is provided to press the drum drive gear 22 against the support member 101a in the pull-out direction D2. That is, the coil spring 40 is provided between the first abutment surface 227a and the support member 101a in the rotation axis direction, and is directly interposed between the sliding plate 229 as a sliding member and the support member 101a. It is The coil spring 40 urges the drum drive gear 22 against the supporting member 101a via the rubbing plate 229 in the pull-out direction D2 (biasing direction) toward the drum holding member 21. As shown in FIG. The biasing force of the coil spring 40 is set to be greater than the decoupling force f1 in the insertion direction D1 component that the reverse rotation contact portion 223 receives. As a result, even when the drum driving gear 22 rotates in the reverse direction, the connection between the photosensitive drum 2 and the drum driving gear 22 is not released.

The end of the coil spring 40 on the insertion direction D1 side is fixed as a fixed end 41 to a support member 101a fixed to the apparatus main body 101, and the end of the coil spring 40 on the extraction direction D2 side is a free end 42 that slides. It is in contact with the scraping plate 229 . When the drum drive gear 22 rotates, the coil spring 40 and the drum drive gear 22 are in direct contact with each other, and in order to suppress wear due to rotational rubbing, there is friction between the coil spring 40 and the drum drive gear 22. A plate 229 is provided. The rubbing plate 229 has a disc portion and is provided rotatably about the rotation axis of the photosensitive drum 2 inside the cylindrical shaft portion 226 . The rubbing plate 229 is interposed between the coil spring 40 and a first abutment surface 227a formed inside the cylindrical shaft portion 226 so as to face the insertion direction D1, and is rotatable by a distance G2, which will be described later. there is

The rubbing plate 229 has a circular second abutment surface 229a perpendicular to the rotation axis direction on the pullout direction D2 side. The second abutment surface 229a as a sliding surface is slidable on the first abutment surface 227a of the drum drive gear 22 . That is, the second abutment surface 229a abuts against the first abutment surface 227a from the rotation axis direction, and can rotate relative to the first abutment surface 227a while sliding. When the drum drive gear 22 rotates, the rubbing plate 229 and the coil spring 40 do not rotate relative to each other, and the second abutment surface 229a of the rubbing plate 229 and the first abutment surface 227a of the drum drive gear 22 rub against each other. relative rotation. For this reason, the rubbing plate 229 is made of synthetic resin such as POM, which has high slidability, in order to suppress wear due to rotational rubbing against the drum driving gear 22 .

Here, the coil spring 40 is made of a metal wire, and the free end 42 is a cut portion of the wire. When the drum driving gear 22 rotates, if the frictional force d1 between the drum driving gear 22 and the rubbing plate 229 is greater than the frictional force d2 between the free end 42 of the coil spring 40 and the rubbing plate 229, the drum driving gear 22 and There is a possibility that the sliding plate 229 will rotate together. In this case, the coil spring 40 and the rubbing plate 229 rub against each other, and there is a risk that the rubbing plate 229 will wear due to the cut portion of the wire, or sliding noise will occur.

Therefore, in this embodiment, the abrasion of the rubbing plate 229 is prevented by eliminating the relative rotation between the coil spring 40 and the rubbing plate 229 . For this reason, in this embodiment, as shown in FIG. 11, when the drum driving gear 22 rotates in the .theta. are provided. The regulating mechanism 23 has a regulating portion 232 of a regulating protrusion 231 provided on the rubbing plate 229 and a regulated portion 241 of a regulated member 240 provided on the support member 101a. The restricting protrusion 231 is a portion that protrudes in the insertion direction D1 from a position along the peripheral edge of the rubbing plate 229, and has a columnar shape with an arc-shaped cross section. The restricting portion 232 as the first engaging portion is provided so as to protrude in the rotation axis direction from the second abutment surface 229a as the sliding surface. Specifically, the restricting portion 232 is formed on the restricting projection 231 and is a flat surface facing the downstream side in the θ direction along the rotation axis direction. The regulated member 240 is a portion protruding from the support member 101a in the pull-out direction D2, and has a columnar shape with an arc-shaped cross section. A regulated portion 241 as a second engaging portion is provided on the apparatus main body 101, protrudes in the rotation axis direction, and can be engaged with the regulating portion 232 when the drum drive gear 22 rotates forward. Specifically, the regulated portion 241 is formed on the regulated member 240 and is a flat surface facing the upstream side in the θ direction along the rotation axis direction. Since the regulating portion 232 and the regulated portion 241 are both flat surfaces along the rotation axis direction, when the drum drive gear 22 rotates in the θ direction and comes into contact with each other, an urging force is generated in the rotation axis direction. Therefore, it is possible to suppress the load from being applied to the bearing or the like. In this embodiment, two regulating portions 232 and two regulated portions 241, and two first contact portions 234 and two second contact portions 242, which will be described later, are provided at intervals of about 90 degrees in the rotational direction. It is

When the drum drive gear 22 rotates in the forward rotation direction, the regulating portion 232 abuts against the regulated member 240 of the support member 101a, thereby regulating the rotation of the rubbing plate 229 with respect to the support member 101a. That is, the rubbing plate 229 is restricted from rotating in the forward rotation direction with respect to the apparatus main body 101 by the engagement between the restricting portion 232 and the restricted portion 241 . The regulated portion 241 is provided to face the regulating portion 232 in the forward rotation direction when the drum drive gear 22 rotates in the forward rotation direction, and when the drum drive gear 22 rotates in the .theta. 232, and the relative rotation between the rubbing plate 229 and the support member 101a stops. At least one of the two regulating portions 232 may abut against the regulated portion 241 . As a result, it is possible to prevent the rubbing plate 229 from continuing to rotate when the drum drive gear 22 rotates, and to prevent abrasion of the rubbing plate 229 by eliminating rubbing between the coil spring 40 and the rubbing plate 229 . That is, it is possible to suppress the wear and noise caused by the coil spring 40 provided between the rotating member and the fixed member in the connecting portion 24 that transmits the rotational drive, and to extend the life of the sliding plate 229. can be achieved.

Next, the force applied to the drum driving gear 22 and the rubbing plate 229 when the drum driving gear 22 rotates in the reverse direction will be described. As described above, when the drum drive gear 22 rotates in the reverse direction, it is necessary to prevent the drum drive gear 22 from moving in the insertion direction D1 and disconnecting from the photosensitive drum 2 . Therefore, the pressing force f5 of the coil spring 40 is set larger than the force f1 that the reverse rotation contact portion 223 receives in the insertion direction D1. As shown in FIG. 12, when the drum driving gear 22 rotates in the reverse direction, the rubbing plate 229 and the drum driving gear 22 exert forces on each other, so that frictional force is generated due to rotational rubbing. It is desirable to reduce the biasing force of the coil spring 40 in order to prolong the life of the drive system or reduce the size and weight of the device.

Therefore, in this embodiment, the auxiliary biasing portion 25 is provided to generate biasing force in the same direction as the biasing direction of the coil spring 40 when the drum driving gear 22 rotates in the -θ direction. The auxiliary biasing portion 25 has a first contact portion 234 of the regulating protrusion 231 provided on the rubbing plate 229 and a second contact portion 242 of the regulated member 240 provided on the support member 101a. there is

The first contact portion 234 is provided on the rubbing plate 229 and comes into contact with the main body of the apparatus when the drum drive gear rotates in the reverse direction. Specifically, the first contact portion 234 is formed on the regulating projection 231 and has a flat surface that is inclined in a direction that intersects the rotation axis direction facing the upstream side in the θ direction and the reverse rotation direction. In the present embodiment, the first contact portion 234 is an inclined surface that is inclined downstream with respect to the reverse rotation direction more downstream with respect to the biasing direction of the coil spring 40 than with respect to the upstream side. That is, the first contact portion 234 is an inclined surface that is inclined downstream in the -θ direction as it goes downstream in the pull-out direction (biasing direction) D2. The second contact portion 242 is provided on the apparatus main body 101 and is capable of contacting the first contact portion 234 . Specifically, the second contact portion 242 is formed on the regulated member 240 and is a flat surface along the rotation axis direction facing the downstream side in the θ direction. The second contact portion 242 contacts the first contact portion 234 when the drum drive gear 22 rotates in the reverse rotation direction. In this embodiment, the second contact portion 242 is a corner provided at the intersection of a plane along the rotation axis direction and a plane perpendicular to the rotation axis direction along the reverse rotation direction. The shape of the corners here may be a substantially right-angled corner or an arc shape with appropriate chamfering. As a result, when the drum driving gear 22 rotates in the -θ direction, the frictional force acting between the drum driving gear 22 and the rubbing plate 229 causes the rubbing plate 229 to rotate, and the first contact portion 234 moves toward the second position. The rubbing plate 229 comes into contact with the contact portion 242 and stops rotating.

Furthermore, the assist force by the auxiliary biasing portion 25 will be described in detail with reference to FIG. 13 . The inclined surface of the first contact portion 234 is such that when the drum drive gear 22 is rotating in the reverse direction while being in contact with the second contact portion 242 , the sliding plate 229 is positioned so as to prevent the drum drive gear 229 from moving in the rotation axis direction. 22 is formed to receive a force from the device main body 101 . A specific description will be given. The action/reaction force that the first contact portion 234 receives from the second contact portion 242 is assumed to be F3. The assist force Fa1 of the pull-out direction D2 component of this action and reaction force is Fa1= A relationship of F3×cosφ holds. As a result, the force in the pull-out direction D2 that the drum drive gear 22 receives from the rubbing plate 229 is the sum of the pressure force F5 and the assist force Fa1. It is desirable to set the tilt angle φ in the range of 10 degrees to 80 degrees. The inclined surface is formed on the side of the second contact portion 242 so that the rubbing plate 229 exerts a force in the direction toward the drum drive gear 22 when the drum drive gear 22 is rotating in the reverse direction as described above. You can accept it. That is, the inclined surface may be formed on either the first contact portion 234 or the second contact portion 242 so as to be inclined in the rotation axis direction of the drum holding member 21 .

Rotation timings of the drum driving gear 22, the photosensitive drum 2, and the rubbing plate 229 during reverse rotation will be described with reference to FIG. As shown in FIGS. 7 and 8, a clearance of distance G1 is set between the reverse rotation abutment portion 223 and the reverse rotation abutted portion 213 . Therefore, as shown in FIG. 14, even if the drum driving gear 22 starts rotating in the reverse direction from the state shown in FIG. 7 (t1), the photosensitive drum 2 does not immediately start rotating in the reverse direction. At t3 after T1 has elapsed, the clearance distance G1 becomes 0, and the reverse rotation contact portion 223 contacts the reverse rotation contacted portion 213 before starting to rotate.

Here, as shown in FIG. 15, a clearance of distance G2 is provided between the first contact portion 234 and the second contact portion 242 . When the drum drive gear 22 rotates in the reverse direction, the rubbing plate 229 rotates along with it, thereby decreasing the distance G2. The clearance distance G2 between the first contact portion 234 and the second contact portion 242 of the rubbing plate 229 becomes 0 earlier than the time required for the distance G1 to become 0, and the first contact portion 234 The second contact portion 242 is set to contact. That is, the rotation angle of the sliding plate 229 when the state where the restricting portion 232 and the regulated portion 241 abut (engage) is switched to the state where the first abutting portion 234 and the second abutting portion 242 abut. is set to be smaller than the play angle of the connecting portion 24 . Specifically, the rotation angle of the rubbing plate 229 in this case is set to be smaller than the play angle of the connecting portion 24 when the rotation direction of the drum drive gear 22 is switched from the forward rotation direction to the reverse rotation direction. It is As a result, the first contact portion 234 and the second contact portion 242 come into contact with each other at t2 after the lapse of T2 from when the drum drive gear 22 starts to rotate in the reverse direction, and the rubbing plate 229 stops rotating. At the same time when the rotation is stopped, the assist force Fa1 is generated, and then at t3, the photosensitive drum 2 starts to rotate in the reverse direction. Therefore, the assist force Fa1 can be generated without fail before the disconnection force f1 is generated.

As described above, according to the image forming apparatus 100 of this embodiment, the rubbing plate 229 is provided between the drum drive gear 22 and the support member 101a. The image forming apparatus 100 also has a regulation mechanism 23 that regulates the relative rotation of the rubbing plate 229 with respect to the support member 101a when the drum driving gear 22 rotates in the forward rotation direction. For this reason, the coil spring 40 provided between the drum drive gear 22 and the support member 101a to urge the drum drive gear 22 in a direction to separate it from the support member 101a has a spring force against the drum drive gear 22 and the support member 101a. It is possible to suppress the occurrence of friction.

Further, according to the image forming apparatus 100 of the present embodiment, when the drum driving gear 22 rotates in the -θ direction, the auxiliary biasing portion 25 that generates biasing force in the same direction as the biasing direction of the coil spring 40 is provided. are provided. Therefore, since the pressing force F5 of the coil spring 40 can be set low, the rubbing resistance between the rubbing plate 229 and the drum driving gear 22 can be reduced while the image forming apparatus 100 is forming an image. As a result, it is possible to contribute to reduction of noise during operation, suppression of malfunction due to generation of wear debris, and extension of the life of the drive system.

In the above-described image forming apparatus 100 of the present embodiment, a case where two restricting portions 232 and two restricted portions 241 and two first contact portions 234 and two second contact portions 242 are provided will be described. However, it is not limited to this. These may be singular, or may be three or more.

Further, in the image forming apparatus 100 of the present embodiment described above, the case where the restriction mechanism 23 and the auxiliary biasing portion 25 are provided in the connection portion 24 for driving and rotating the photosensitive drum has been described, but the installation target is this. Not limited. For example, it may be applied to a connecting portion for driving an intermediate transfer member or a developing sleeve.

In this embodiment, the first contact portion 234 is a flat surface that is inclined toward the downstream side in the reverse rotation direction as it goes downstream in the biasing direction. is not limited. For example, as shown in FIG. 17A, the first contact portion 234A is an inclined surface that is inclined toward the downstream side with respect to the reverse rotation direction as it goes downstream with respect to the biasing direction. It may be a curved surface protruding from the downstream side to the upstream side. Alternatively, for example, as shown in FIG. 17(b), the first contact portion 234B is an inclined surface that is inclined toward the downstream side in the reverse rotation direction as it goes downstream in the biasing direction, It may be a curved surface recessed from the upstream side to the downstream side in the θ direction.

Further, in the present embodiment, the case where the first contact portion 234 is an inclined surface and the second contact portion 242 is a corner portion of the regulated member 240 is described, but the present invention is not limited to this. That is, at least one of the first contact portion 234 and the second contact portion 242 may be an inclined surface that is inclined toward the downstream side in the reverse rotation direction as it goes downstream in the biasing direction. For example, as shown in FIG. 18A, the first contact portion 234C is a corner provided at the intersection of a plane along the rotation axis direction and a plane orthogonal to the rotation axis direction. The shape of the corners here may be a substantially right-angled corner or an arc shape with appropriate chamfering. In this case, the second contact portion 242A is formed on the regulated member 240, and is a flat surface that is inclined downstream in the reverse rotation direction as it goes downstream in the urging direction. As a result, when the drum driving gear 22 rotates in the −θ direction, the frictional force acting between the drum driving gear 22 and the rubbing plate 229 causes the rubbing plate 229 to rotate with the first contact portion 234C. The rubbing plate 229 comes into contact with the contact portion 242A and stops rotating.

In the embodiment shown in FIG. 18(a), the second contact portion 242A is a flat surface that is inclined toward the downstream side in the reverse rotation direction as it goes downstream in the biasing direction. but not limited to this. For example, as shown in FIG. 18(b), the second contact portion 242B is an inclined surface inclined toward the downstream side in the reverse rotation direction as it goes downstream in the biasing direction. It may be a curved surface projecting from the upstream side to the downstream side. Alternatively, for example, as shown in FIG. 18(c), the second contact portion 242C is an inclined surface that is inclined toward the downstream side in the reverse rotation direction as it goes downstream in the biasing direction, It may be a curved surface recessed from the downstream side to the upstream side in the θ direction.

Moreover, although each embodiment described above describes a case where one of the first contact portion 234 and the second contact portion 242 is an inclined surface and the other is a corner portion, the present invention is not limited to this. For example, as shown in FIG. 19, each of the first contact portion 234 and the second contact portion 242A has an inclined surface that is inclined toward the downstream side in the reverse rotation direction as it goes downstream in the biasing direction. may be In this case, it is preferable that both the first contact portion 234 and the second contact portion 242A are flat and have the same inclination angle with respect to the rotation axis direction.

[Example]
A comparison was made between an example according to the present embodiment and a comparative example that does not have the auxiliary biasing portion 25 with respect to the resultant force of the pull-out direction D2 received by the drum drive gear 22 . As shown in FIG. 16, in the comparative example, it is necessary to set the pressing force F5 high in order to maintain the resultant force after reverse rotation equal to the resultant force in the example. That is, it was confirmed that according to this embodiment, the pressing force F5 can be set lower than in the conventional configuration that does not have the auxiliary biasing portion 25. FIG.

1c, 1k, 1m, 1y... drum cartridge (image forming unit), 2... photosensitive drum (rotating body, image carrier), 21... drum holding member (rotating body), 22... drum driving gear (driving gear), 24 Coupling portion 40 Coil spring (biasing means, compression coil spring) 100 Image forming apparatus 101 Apparatus main body 101a Supporting member 211 Fitting projection (projection) 221 Fitting recess (Concave portion) 227a First abutment surface 229 Sliding plate (sliding member) 229a Second abutment surface (sliding surface) 232 Regulating portion (first engaging portion) 234, 234A, 234B, 234C... First contact portion 241... Regulated portion (second engaging portion) 242, 242A, 242B, 242C... Second contact portion D1... Insertion direction (one end side in rotation axis direction) ), D2 .

Claims (6)

a device body;
a rotatable rotating body detachably provided in the device main body;
a driving gear that is supported by the apparatus main body so as to be movable in the direction of the rotation axis of the rotating body, has a connection part that drives and connects with the rotating body in the direction of the rotation axis of the rotating body, and drives the rotating body;
a biasing member that biases the drive gear toward the rotating body;
A sliding surface is provided between the driving gear and the biasing member with respect to the rotation axis direction of the rotating body and is slidable with the driving gear, and the rotating body is drivingly connected to the driving gear. The driving gear is configured to keep contact with the sliding surface when the driving gear rotates forward, and when the driving gear rotates forward, the device main body and the rotating body are engaged in the rotational direction. and a sliding member whose rotation in the forward rotation direction is regulated,
An image forming apparatus characterized by: the sliding member protrudes from the sliding surface in the direction of the rotation axis of the rotating body, and engages with the device main body when the drive gear is rotating forward; a second engaging portion provided in the device main body, protruding in the direction of the rotation axis of the rotating body, and capable of being engaged with the first engaging portion when the drive gear is rotating in the forward direction; , the first engaging portion and the second engaging portion are engaged to restrict rotation of the sliding member in the forward rotation direction with respect to the device main body;
2. The image forming apparatus according to claim 1, wherein: A surface with which the first engaging portion and the second engaging portion engage is a plane along the rotation axis direction,
3. The image forming apparatus according to claim 2, wherein: The connecting portion is provided on one of the rotating body and the driving gear and has a shape projecting in the rotation axis direction, and is provided on the other of the rotating body and the driving gear and extends in the rotation axis direction. a concave portion having a concave shape and capable of being driven and connected by detachably fitting the convex portion;
The convex portion and the concave portion have a shape twisted in the same direction about the rotation axis of the rotating body so that a mutual pull-in force is generated when the drive gear rotates forward,
a first abutting portion provided on the sliding member and abutting against the device main body side when the drive gear rotates in the reverse direction;
a second contact portion provided in the device main body and capable of contacting the first contact portion;
When the drive gear rotates in the opposite direction while the first contact portion and the second contact portion are in contact with each other, the sliding member moves against the drive gear with respect to the rotation axis direction of the rotating body. An inclined surface inclined in a rotation axis direction of the rotating body is formed on one of the first contact portion and the second contact portion so as to receive a force from the apparatus main body in a direction toward the apparatus body,
4. The image forming apparatus according to claim 2, wherein: The rotation angle of the sliding member when switching from the state in which the first engaging portion and the second engaging portion are engaged to the state in which the first contact portion and the second contact portion are in contact is , less than the angle of play in the rotational direction of the coupling,
5. The image forming apparatus according to claim 4, wherein: The biasing member is a compression coil spring,
6. The image forming apparatus according to claim 1, wherein:

Images