JP2008074501A - Driving force transmitting device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To securely maintain engagement of a D-cut part and a rotating body for stably transmitting driving force without rotation of a retaining ring at a predetermined angle or more to the rotating body and without dropping and missing the retaining ring from a groove part by forming a projection part at a position on the rotating body corresponding to a flat part of the D-cut part for engaging with a notch of the retaining ring. <P>SOLUTION: A driving force transmitting device comprises a shaft provided with the D-cut part having an approximately D-shaped cross section and formed with the flat part at a part of a circular cylinder and the groove part formed on a circular peripheral surface of the D-cut part, the rotating body provided with an approximately D-shaped center hole and engaging with the D-cut part to rotate with the shaft, and the retaining ring provided with the notch for engaging with the groove part of the shaft and preventing the rotating body from moving to the axial direction. The rotating body is provided with the projection part for engaging with the notch of the retaining ring formed at the position corresponding to the flat part of the D-cut part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a driving force transmission device and an image forming apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a printer, a transport roller is used to feed out recording paper stored in a paper feed cassette and feed it to an image forming unit (for example, see Patent Document 1).

In a driving force transmission device for transmitting a driving force from a driving motor to the conveying roller, a shaft having a D cut portion formed at one end so as to have a D-shaped cross section is generally used. ing. In this case, the shaft and the rotary member are non-rotatably connected to each other by engaging a D-shaped center hole (hole) provided in the rotary member such as a gear and a pulley with the D-cut portion. Can be transmitted from the rotating member to the shaft. Further, when the rotating member moves in the axial direction of the shaft, the rotating member falls off from the shaft, so that the rotating member moves in the axial direction of the shaft by engaging a retaining ring such as an E ring with a groove formed in the shaft. Is to prevent.
Japanese Utility Model Publication No. 5-611147

  However, in the conventional driving force transmission device, the retaining ring may fall off from the groove formed on the shaft. For example, the E-ring has three engaging portions that engage with the groove of the shaft, but when the E-ring rotates, one of the engaging portions comes off the groove formed in the D-cut portion. As a result, the sitting of the E-ring deteriorates, and the E-ring may fall out of the groove.

  The present invention solves the problems of the conventional driving force transmission device, and includes a shaft including a D-cut portion in which a flat portion is formed in a part of a cylinder and a transverse section is substantially D-shaped, A rotating body having a substantially D-shaped center hole, which engages with the D-cut portion and rotates together with the shaft, and engages with a groove formed on an arc-shaped peripheral surface of the D-cut portion. In the driving force transmission device having a retaining ring for preventing the movement of the retaining ring in the axial direction, a protrusion that engages the notch portion of the retaining ring is formed on the rotating body at a position corresponding to the flat portion of the D-cut portion. By doing so, the retaining ring does not rotate more than a predetermined angle with respect to the rotating body, the retaining ring does not come off from the groove and falls off, and the engagement between the D-cut portion and the rotating body is ensured. Driving force transmission device and image which can be maintained and can transmit driving force stably And to provide a forming apparatus.

  Therefore, in the driving force transmission device of the present invention, a flat portion is formed on a part of a cylinder, and a D-cut portion having a substantially D-shaped cross section, and an arc-shaped peripheral surface of the D-cut portion. A shaft provided with the formed groove portion, a substantially D-shaped center hole, a rotating body that engages with the D cut portion and rotates together with the shaft, a notch portion, and engages with the groove portion of the shaft. And a retaining ring for preventing axial movement of the rotating body, wherein the rotating body is formed in a notch of the retaining ring formed at a position corresponding to the flat portion of the D-cut portion. A protrusion that engages with the portion.

  According to the present invention, the driving force transmission device includes a shaft including a D-cut portion having a flat portion formed in a part of a cylinder and having a substantially D-shaped cross section, and a substantially D-shaped center hole. A rotating body that engages with the D-cut portion and rotates together with the shaft, and a retaining ring that engages with a groove formed on the arc-shaped peripheral surface of the D-cut portion to prevent the rotating body from moving in the axial direction. And a protrusion that engages with the notch of the rotating body is formed at a position corresponding to the flat portion of the D-cut section. As a result, the retaining ring does not rotate more than a predetermined angle with respect to the rotating body, the retaining ring does not come off from the groove portion and falls off, and the engagement between the D-cut portion and the rotating body is reliably maintained. The driving force can be transmitted stably.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 2 is a schematic diagram of the image forming apparatus according to the first embodiment of the present invention.

  In the figure, reference numeral 10 denotes an image forming apparatus according to the present embodiment. For example, a printer, a copying machine, a facsimile machine, a multifunction machine, or the like that forms an image on a recording sheet P by an electrophotographic method. It may be an image forming apparatus. The recording paper P as the recording medium is, for example, plain paper. In addition to plain paper, special paper such as envelope, OHP (Over Head Projector) sheet, card, postcard, cardboard, envelope, coated paper, etc. It may be. The image forming apparatus 10 may form a monochrome image or a color image. Here, the image forming apparatus 10 forms a color image by a tandem method. The case where it is what will be described.

  The image forming apparatus 10 is sequentially arranged in the conveyance direction of the recording paper P (the direction indicated by the arrow A), and forms an image forming unit for forming four color toner images of black, yellow, magenta, and cyan on the recording paper P. 12K, 12Y, 12M and 12C. Here, the left side (downstream side in the conveyance direction of the recording paper P) in the figure is the F direction (front), and the right side (upstream side in the conveyance direction of the recording paper P) in the figure is the R direction (rear). Since the image forming units 12K, 12Y, 12M, and 12C have the same structure, the structure will be described here by taking the image forming unit 12K as an example.

  The image forming unit 12K includes a photosensitive drum 30 as an image carrier that carries a toner image on the surface. The photosensitive drum 30 is rotationally driven by a drum motor (not shown). Around the photosensitive drum 30, a charging roller 31 as a charging device, an LED (Light Emitting Diode) head 32 as an exposure device, and a developing unit 33 as a developing device are disposed. The developing unit 33 includes a toner container 33c that stores toner, and a developing roller 33a and a toner supply roller 33b are disposed in the toner container 33c. The developing units 33 of the image forming units 12K, 12Y, 12M, and 12C contain black, yellow, magenta, and cyan toners, respectively. In addition, a transfer roller 34 as a transfer unit, which is a roller-like member, is disposed below the photoconductive drum 30 so as to sandwich the recording paper P between the photoconductive drum 30 and the like. .

  The charging roller 31 uniformly charges the surface of the photosensitive drum 30. The LED head 32 selectively exposes the uniformly charged photosensitive layer of the photosensitive drum 30 according to image information. Then, in the photosensitive layer of the photosensitive drum 30, the charged portion is removed from the exposed portion, and the charged portion remains in the unexposed portion to form an electrostatic latent image. The developing unit 33 forms a toner image by attaching toner to the electrostatic latent image on the photosensitive drum 30. The transfer roller 34 transfers the toner image formed on the surface of the photosensitive drum 30 to the recording paper P by applying a charge having a polarity opposite to that of the toner from the back surface of the recording paper P.

  A belt 11 as a toner carrier for conveying the recording paper P is an endless belt and is stretched around a pair of rollers 35 and 36. The rollers 35 and 36 are arranged so that the transfer rollers 34 of the image forming units 12K, 12Y, 12M and 12C are sandwiched therebetween. The rollers 35 and 36 are disposed such that the axial direction thereof coincides with the width direction of the belt 11. The roller 35 is rotationally driven by a belt driving roller (not shown), and the belt 11 moves in the direction indicated by the arrow A by the rotation of the roller 35.

  In the drawing, on the left side of the roller 35, a fixing device 26 for fixing the toner image by pressing and heating the recording paper P is disposed. The fixing device 26 includes a fixing roller 26a that includes a heater (not shown), a press roller 26b that sandwiches the recording paper P between the fixing roller 26a, and a driving force that rotates the fixing roller 26a (not shown). A motor and a mechanism (for example, a gear train) for transmitting the driving force of the fixing motor to the fixing roller 26a. Further, on the left side of the fixing device 26, two sets of discharge roller pairs 27 and 28 that guide the recording paper P to a discharge unit 29 provided in the upper part of the image forming apparatus 10 are provided.

  A storage unit 20 that stores the recording paper P is disposed below the image forming apparatus 10. A small-diameter auxiliary roller 22 and a large-diameter paper feed roller 23 that feed the recording paper P out of the storage unit 20 are arranged side by side on the right side of the storage unit 20. The auxiliary roller 22 and the paper feed roller 23 are rotationally driven by a paper feed motor (not shown). Further, an inclined plate 21 for pressing the leading end of the recording paper P against the auxiliary roller 22 and the paper feed roller 23 is disposed on the auxiliary roller 22 side of the storage unit 20.

  Further, registration roller pairs 24 and 25 as two pairs of conveyance rollers for conveying the recording paper P are disposed on the conveyance path of the recording paper P from the storage unit 20 to the image forming unit 12K. The registration roller pairs 24 and 25 convey the recording paper P fed from the storage unit 20 to the belt 11. Further, when the recording sheet P fed from the storage unit 20 is skewed and fed out, the skew of the recording sheet P is corrected (registered) by the registration roller pair 24 and conveyed to the registration roller pair 25. It has become.

  Next, the configuration of the driving force transmission device that transmits the driving force to the registration roller pair 24 will be described in detail.

  FIG. 1 is a perspective view of a registration roller pair according to the first embodiment of the present invention, and FIG. 3 is an exploded perspective view of the registration roller pair according to the first embodiment of the present invention.

  As shown in the figure, the registration roller pair 24 includes a registration roller 41 and a pressure roller 43. The registration roller 41 includes a metal shaft 41b as an axis, and the metal shaft 41b is press-fitted into the rubber roller 41a.

  Reference numerals 44L and 44R denote registration roller holders used as bearings for the registration roller 41. The metal shaft 41b of the registration roller 41 is supported by registration roller holders 44L and 44R so as to be rotatable and immovable in the axial direction.

  And as FIG. 3 shows, D cut part 41d is formed in the edge part which protruded from the registration roller holder 44R of the said metal shaft 41b. The D-cut portion 41d is a portion having a substantially D-shaped cross section, and is obtained by forming a flat portion on a part of a metal shaft 41b that is a cylinder. In the example shown in the figure, the flat portion faces downward. Further, as shown in FIG. 3, the D-cut portion 41d is formed with an arc-shaped groove portion 41e along its circumferential surface.

  In the figure, reference numeral 40 denotes a driving gear as a rotating body in a driving force transmission device that transmits a driving force from a driving source such as a motor (not shown) to the registration roller 41. As shown in FIG. 3, the drive gear 40 is a two-stage gear composed of a large-diameter drive gear 40a and a small-diameter drive gear 40b that are integrally coupled, and has a central portion along the rotation axis. A central hole 40d penetrating therethrough is formed. The cross-sectional shape of the center hole 40d has a substantially D-shape corresponding to the outer shape of the D-cut portion 41d, and the D-cut portion 41d is inserted into and engaged with the center hole 40d. Thus, when the D cut portion 41d and the center hole 40d are engaged, the metal shaft 41b and the drive gear 40 are coupled to each other so as not to rotate, and rotate integrally.

  Further, after the D-cut portion 41d is inserted into the center hole 40d, the E ring 42 as a retaining ring is fitted into the groove portion 41e and engaged. The E-ring 42 is a metal substantially annular member called an E-shaped retaining ring. However, the E-ring 42 is not completely annular but has a shape including a notch part in which a part of the ring is missing. Thereby, the drive gear 40 is prevented from moving in the distal direction of the metal shaft 41b by the E-ring 42, and is not detached from the metal shaft 41b. The movement of the drive gear 40 in the direction opposite to the tip of the metal shaft 41b is prevented by the registration roller holder 44R. That is, the drive gear 40 is sandwiched from both sides by the E-ring 42 and the registration roller holder 44R, and is prevented from moving in the axial direction.

  A protrusion 40c is formed on the surface of the drive gear 40 opposite to the registration roller holder 44R. The protrusion 40c is formed at a position corresponding to the flat portion of the D-cut portion 41d, and engages with a notch portion of the E-ring 42 that engages with the groove portion 41e. Thereby, rotation with respect to the metal shaft 41b and the drive gear 40 of the E ring 42 is prevented. The protruding portion 40c and the cutout portion of the E-ring 42 are engaged with each other with a certain amount of shakiness. Further, it is desirable that the protruding height of the protrusion 40c is equal to or greater than the thickness of the E-ring 42.

  On the other hand, the pressure roller 43 includes a rotating shaft 43b protruding from both ends in the axial direction, and the rotating shaft 43b is rotatably supported by the bearing portion 45. One rotating shaft 43b is formed with a D-cut portion 43d having the same shape as the D-cut portion 41d of the metal shaft 41b. Reference numeral 47 denotes a driven gear. The driven gear 47 is formed with a central hole 47d having the same shape as the central hole 40d of the drive gear 40. The D-cut portion 43d protruding from the bearing portion 45 is inserted into and engaged with the center hole 47d, so that the rotary shaft 43b and the driven gear 47 are coupled to each other so as not to rotate, and rotate integrally. .

  A spring 46 is wound around the bearing portion 45, and hook portions 46a connected to both ends of the spring 46 are hooked on the hook portion 44La of the registration roller holder 44L and the hook portion 44Ra of the registration roller holder 44R. It is done. As a result, the bearing portion 45 is urged toward the registration roller 41 by the urging force of the spring 46, and the pressure roller 43 contacts the rubber roller 41a of the registration roller 41 with a predetermined pressing force. Further, when the driven gear 47 meshes with the small diameter drive gear 40 b, the driving force from the drive source is transmitted to the pressure roller 43 via the drive gear 40 and the driven gear 47. In this case, when the drive gear 40 rotates in the direction indicated by the arrow B, the driven gear 47 rotates in the direction indicated by the arrow C.

  Next, the operation of the driving force transmission device having the above configuration will be described.

  FIG. 4 is a side view of the registration roller pair according to the first embodiment of the present invention, and FIG. 5 is a view showing a modification of the protruding portion according to the first embodiment of the present invention.

  As described above, the drive gear 40 is a two-stage gear composed of the large-diameter drive gear 40a and the small-diameter drive gear 40b, and the drive force from the drive source is transmitted through the gear train (not shown). When transmitted to 40a, it rotates in the direction indicated by arrow B. Since the small diameter drive gear 40b is engaged with the driven gear 47, the driven gear 47 rotates in the direction indicated by the arrow C in FIG. At this time, the gear ratio between the small diameter driving gear 40b and the driven gear 47 is set so that the surface peripheral speed of the rubber roller 41a of the registration roller 41 and the surface peripheral speed of the pressure roller 43 are substantially equal.

  When the drive gear 40 rotates in the direction indicated by the arrow B, the registration roller 41 also rotates in the direction indicated by the arrow B integrally with the drive gear 40.

  At this time, in the conventional driving force transmission device, if there is rattling between the E-ring and the groove of the shaft, the E-ring is attached to the shaft as described in the section “Problems to be solved by the invention”. Since it rotates with respect to it, one of the engaging parts with which an E ring is equipped may remove | deviate from the groove | channel of a shaft, and E ring may fall off.

  On the other hand, in the present embodiment, the protrusion 40c formed on the drive gear 40 is engaged with the notch portion of the E ring 42 with a certain amount of shakiness. It does not rotate more than a predetermined angle with respect to the drive gear 40 and the metal shaft 41b. Therefore, the E ring 42 does not come off from the groove 41e of the metal shaft 41b and fall off.

  In the present embodiment, the case where the E-ring 42 is used as the retaining ring has been described. However, even a retaining ring other than the E-ring 42 has a shape with a cutout portion in which a part of the ring is missing. Then, the same effect can be acquired by using similarly to this Embodiment.

  Further, the protrusion 40c does not necessarily have to be a single linear member as shown in FIGS. 1, 3 and 4. For example, as shown in FIG. Or a single curved member as shown in FIG. 5B. In consideration of the strength of the protrusion 40c itself, a linear single member as shown in FIGS. 1, 3 and 4 is used instead of two rod-like members as shown in FIG. 5 (a). It is desirable to be a member or a single curved member as shown in FIG.

  As described above, in the present embodiment, the protrusion 40 c that engages with the notch of the E ring 42 is formed on the drive gear 40. Thereby, the E ring 42 does not rotate more than a predetermined angle with respect to the drive gear 40 and the metal shaft 41b, and does not come off from the groove 41e of the metal shaft 41b. Therefore, the drive gear 40 does not move in the axial direction with respect to the metal shaft 41b, and does not come out of the metal shaft 41b.

  Next, a second embodiment of the present invention will be described. In addition, about the thing which has the same structure as 1st Embodiment, the description is abbreviate | omitted by providing the same code | symbol. The description of the same operations and effects as those of the first embodiment is also omitted.

  FIG. 6 is a perspective view showing a state of the gear coupled to the metal shaft in the second embodiment of the present invention.

  In the present embodiment, as shown in FIG. 6, the drive gear 40 includes a guide surface portion 40 e that guides the E ring 42 when the E ring 42 is engaged with and engaged with the groove portion 41 e of the metal shaft 41 b, and And a guide rib 40f formed so as to surround the periphery of the guide surface portion 40e. The protruding height of the guide rib 40f is desirably equal to or greater than the thickness of the E-ring 42.

  In the drive gear 40, a protrusion 40c is formed at a position corresponding to the flat portion of the D-cut portion 41d of the metal shaft 41b, as in the first embodiment. And this projection part 40c is engaged with the notch part of E ring 42 in the state with a certain amount of shakiness.

  Since the configuration of other points is the same as that of the first embodiment, description thereof is omitted.

  Next, the operation of the driving force transmission device in the present embodiment will be described.

  Usually, the rotating body such as the drive gear 40 used in the image forming apparatus 10 is formed using a resin such as polyacetal (POM) as a material. In most cases, the color of the resin is designated as a natural color, that is, white. This is to make the grease inconspicuous even when white grease generally used for the sliding portion of the rotating body is used together with the problem of material cost.

  However, if the color of the resin is white, the protrusions 40c formed on the drive gear 40 are less noticeable. Further, if the diameter of the metal shaft 41b of the registration roller 41 is small, when the E-ring 42 is fitted into the groove 41e of the metal shaft 41b and engaged, the operator can find where the D-cut portion 41d of the metal shaft 41b is located. It may not be possible to distinguish at a glance.

  Therefore, in the present embodiment, the E-ring 42 is applied to the guide surface portion 40e, and the E-ring 42 is slid toward the metal shaft 41b along the guide rib 40f, so that the E-ring 42 is grooved 41e of the metal shaft 41b. Can be easily inserted in an appropriate direction.

  Thus, in the present embodiment, the protrusion 40c that engages with the notch of the E-ring 42 is formed at a position corresponding to the flat portion of the D-cut portion 41d of the metal shaft 41b in the drive gear 40. . Therefore, the E-ring 42 does not rotate more than a predetermined angle with respect to the drive gear 40 and the metal shaft 41b, does not come off from the groove portion 41e of the metal shaft 41b, and does not fall off. The retaining function can be maintained.

  Further, a guide surface portion 40e for guiding the E ring 42 and a guide rib 40f formed so as to surround the periphery of the guide surface portion 40e are formed in the drive gear 40. Therefore, the E-ring 42 can be easily assembled to the D-cut portion 41d of the metal shaft 41b without making a mistake in the mounting direction, so that the assembling work can be improved.

  Next, a third embodiment of the present invention will be described. In addition, about the thing which has the same structure as 1st and 2nd embodiment, the description is abbreviate | omitted by providing the same code | symbol. The description of the same operations and effects as those of the first and second embodiments is also omitted.

  FIG. 7 is a perspective view showing the state of the gear coupled to the metal shaft in the third embodiment of the present invention, and FIG. 8 shows the state of the gear coupled to the metal shaft in the third embodiment of the present invention. It is sectional drawing shown.

  In the present embodiment, as shown in FIGS. 7 and 8, the drive gear 40 has a guide surface portion 40e that guides the E ring 42 when the E ring 42 is engaged with the groove portion 41e of the metal shaft 41b. The guide rib 40f is formed so as to surround the guide surface portion 40e, and the cylindrical rib 40g is formed as a cylindrical wall portion so as to cover the periphery of the protrusion 40c. The protruding height L of the draft cylindrical rib 40g is set to be equal to or greater than the outer diameter of the E-ring 42.

  Since the configuration of other points is the same as that of the first and second embodiments, the description thereof is omitted.

  Next, the operation of the driving force transmission device in the present embodiment will be described.

  Normally, when performing maintenance and disassembly of the image forming apparatus 10, if the E-ring 42 is removed by using a precision screwdriver, the E-ring 42 may fly away in an unexpected direction or may be lost. It may take the time to find the inside, and the disassembly workability may be significantly impaired.

  Therefore, in order not to lose the E-ring 42, the operator rotates the E-ring 42 in a predetermined direction with respect to the metal shaft 41b in advance, adjusts the direction in which the E-ring 42 jumps, and jumps the E-ring. It is conceivable to receive 42 by hand. However, in the first and second embodiments, since the protrusion 40c is formed on the drive gear 40, the E-ring 42 cannot be rotated relative to the metal shaft 41b. Can not adjust the direction of jumping.

  Therefore, in the present embodiment, the cylindrical rib 40g is formed on the drive gear 40. As a result, when the E-ring 42 is removed, even if the E-ring 42 jumps, the E-ring 42 does not fly in an unexpected direction because it bounces off the inner wall of the cylindrical rib 40g. Further, since the height L of the cylindrical rib 40g is equal to or larger than the outer diameter of the E-ring 42, it becomes a tray that is sufficient to catch and hold the E-ring 42 that has bounced off the inner wall of the cylindrical rib 40g. It is possible to reliably prevent the ring 42 from dropping and entering the image forming apparatus 10.

  As described above, in the present embodiment, the driving gear 40 is formed with the cylindrical rib 40g that prevents the E ring 42 from scattering and dropping off. Thereby, when performing maintenance and disassembly of the image forming apparatus 10, it is possible to prevent the E ring 42 from being accidentally skipped and lost, or the E ring 42 from entering the image forming apparatus 10. Therefore, maintenance and disassembly workability of the image forming apparatus 10 can be improved.

  In the first to third embodiments, the engagement surface between the protrusion 40c and the E ring 42 has a substantially arc shape, but the shape of the corresponding portion of the E ring 42 is not limited to this. You just have to adapt to. The example in which the protrusion 40c is integrally formed with the drive gear 40 has been described. However, the protrusion 40c is used as a pin, and a portion (for example, a hole) that engages with the pin is provided in the drive gear 40. Also good. However, in order to reduce the number of parts, it is desirable to integrally form the protrusion 40c and the drive gear 40. Note that the material of the protrusion 40c is POM, similar to the material of the drive gear 40.

  In the present invention, the example applied to the driving gear used by engaging with the metal shaft of the conveying roller having the D-cut portion in the electrophotographic printer has been described. However, the rotating body other than the gear such as a cam or a lever is described. It can also be applied to. Further, the present invention can also be applied to a rotating body used in an image forming apparatus such as a copying machine, a facsimile machine, or a printer that forms an image on recording paper using various printing methods other than an electrophotographic printer.

  Furthermore, the present invention is not limited to the above-described embodiment, and various modifications can be made based on the spirit of the present invention, and they are not excluded from the scope of the present invention.

It is a perspective view of a registration roller pair in the first embodiment of the present invention. 1 is a schematic diagram of an image forming apparatus according to a first embodiment of the present invention. It is a disassembled perspective view of the registration roller pair in the 1st Embodiment of this invention. It is a side view of the registration roller pair in the first embodiment of the present invention. It is a figure which shows the modification of the projection part in the 1st Embodiment of this invention. It is a perspective view which shows the state of the gear couple | bonded with the metal shaft in the 2nd Embodiment of this invention. It is a perspective view which shows the state of the gear couple | bonded with the metal shaft in the 3rd Embodiment of this invention. It is sectional drawing which shows the state of the gear couple | bonded with the metal shaft in the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 40 Drive gear 40c Projection part 40d Center hole 40e Guide surface part 40g Cylindrical rib 41b Metal shaft 41d D cut part 41e Groove part 42 E ring

Claims (4)

(A) A shaft provided with a D-cut portion in which a flat portion is formed in a part of a cylinder and the cross section is substantially D-shaped, and a groove portion formed on an arc-shaped peripheral surface of the D-cut portion;
(B) a rotating body provided with a substantially D-shaped center hole, which engages with the D-cut portion and rotates together with the shaft;
(C) A driving force transmission device including a notch portion and a retaining ring that engages with a groove portion of the shaft and prevents the rotating body from moving in the axial direction,
(D) The rotating body includes a projecting portion that engages with a notch portion of the retaining ring formed at a position corresponding to the flat portion of the D-cut portion. 2. The driving force transmission device according to claim 1, wherein the rotating body includes a guide surface portion that is formed on a side opposite to the protruding portion across the center hole and guides the retaining ring. 2. The driving force transmission according to claim 1, wherein the rotating body includes a cylindrical wall that protrudes in the same direction as the protrusion, covers the periphery of the protrusion, and has a height equal to or greater than the outer diameter of the retaining ring. apparatus. An image forming apparatus for forming an image on a recording medium by a predetermined image forming process, comprising the driving force transmitting device according to claim 1.

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