The present disclosure relates to an electrophotographic image forming apparatus for forming an image on a recording medium using an electrophotographic system, with a cartridge mounted therein.
In an electrophotographic image forming apparatus (hereinafter simply referred to as “image forming apparatus”), an electrophotographic photosensitive member serving as an image bearing member, which is generally drum shaped, that is, a photosensitive drum, is uniformly charged with electricity. Next, the charged photosensitive drum is selectively exposed to light to form an electrostatic latent image (an electrostatic image) on the photosensitive drum. Then, the electrostatic latent image formed on the photosensitive drum is developed into a toner image with toner serving as a developer. The toner image formed on the photosensitive drum is transferred to a recording medium, such as recording paper or a plastic sheet, the toner image transferred onto the recording medium is then subjected to heat or pressure so that the toner image is fixed to the recording medium, and thus the image is printed.
Such image forming apparatuses generally need replenishing of toner and maintenance of various processing units. To facilitate the replenishing of toner and the maintenance, a process cartridge in which a photosensitive drum, a charging unit, a developing unit, a cleaning unit, and so on are combined in a frame and which is detachably mounted to an image forming apparatus main body is in practical use.
This process cartridge system remarkably enhances the operability because a user can perform maintenance by himself/herself, thus providing an image forming apparatus having excellent usability. For this reason, this process cartridge system is widely used in image forming apparatuses.
Japanese Patent Laid-Open No. 8-328449 discloses an image forming apparatus including a driving-force transmission member that includes a coupling that transmits drive to a process cartridge from an image forming apparatus main body at an end and that is urged toward the process cartridge by a spring. This image forming apparatus is configured such that, when the openable cover of the image forming apparatus main body is closed, the driving-force transmission member is pushed by the spring and moves toward the process cartridge into engagement with a coupling of the process cartridge to transmit the driving force. Furthermore, when the openable cover of the image forming apparatus main body is opened, the driving-force transmission member is moved away from the process cartridge against the spring by a cam into a detachable state.
The present disclosure is intended to develop the related art and provides a configuration in which the driving-force transmission member can be positioned with stability in the direction of the axis of rotation.
In another aspect of the present disclosure, the following electrophotographic image forming apparatus is provided.
The electrophotographic image forming apparatus forms an image on a recording medium in a state in which a cartridge is mounted to an apparatus main body. The apparatus includes a drive source, a drive gear, and a driving-force transmission member. The drive gear is configured to be rotated by the drive source. The driving-force transmission member is configured to be rotated by a driving force transmitted from the drive gear to transmit the driving force to the cartridge. The driving-force transmission member includes a coupling portion, a first helical gear portion, and a second helical gear portion. The coupling portion includes a driving-force transmission surface configured to engage with a cartridge coupling of the cartridge and transmits the driving force to the cartridge coupling. The first helical gear portion is configured to engage with a driven gear of the cartridge to transmit the driving force. The second helical gear portion is configured to engage with the drive gear to receive the driving force. The coupling portion, the first helical gear portion, and the second helical gear portion rotate integrally with each other when the driving-force transmission member rotates about an axis of rotation. The driving-force transmission surface of the coupling portion is shaped with a twist in a same direction as a rotation direction of the driving-force transmission member from a downstream side to an upstream side in a predetermined direction parallel to the axis of rotation when the driving-force transmission member is viewed in the predetermined direction from the cartridge coupling. Helical teeth of the first helical gear portion are shaped with a twist in a same direction as a twist direction of the driving-force transmission surface. Helical teeth of the second helical gear portion are shaped with a twist in a direction opposite to the twist direction of the helical teeth of the first helical gear portion.
Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings).
An embodiment of the present disclosure will be described. In the following description, an apparatus main body A refers to a part of the electrophotographic image forming apparatus excluding a cartridge B. A longitudinal direction AM is defined as the direction of the axis of rotation of an electrophotographic photosensitive drum 62 in a state in which the cartridge B is mounted in the apparatus main body A. A side on which a driving-force transmission member 81 that transmits drive from the image forming apparatus main body A to the electrophotography photosensitive drum 62 in the longitudinal direction AM of the apparatus main body A is defined as a drive side, and the opposite side is defined as a non-drive side.
Referring to
Overall Configuration of Electrophotographic Image Forming Apparatus
The electrophotographic image forming apparatus illustrated in
The apparatus main body A further includes a pick-up roller 5a, a feed roller pair 5b, a conveying roller pair 5c, a transfer guide 6, a transfer roller 7, a conveyance guide 8, a fixing unit 9, a discharge roller pair 10, an output tray 11, and so on in the conveying direction D of the sheet material P. The fixing unit 9 is constituted of a heating roller 9a and a pressure roller 9b.
Image Forming Process
The outline of the image forming process will be described. The electrophotographic photosensitive drum (hereinafter referred to as “drum 62”) is rotationally driven at a predetermined circumferential speed (process speed) in the direction of arrow R on the basis of a print start signal. A charging roller 66 to which a bias voltage is applied comes into contact with the outer circumferential surface of the drum 62 to uniformly charge the outer circumferential surface of the drum 62.
The exposing unit 3 outputs a laser beam L according to image information. The laser beam L passes through a laser opening 71h provided in a cleaning housing 71 of the cartridge B to scan the outer circumferential surface of the drum 62 for exposure. Thus an electrostatic latent image corresponding to the image information is formed on the outer circumferential surface of the drum 62.
Referring now to
As illustrated in
The sheet material P to which the toner image is transferred is separated from the drum 62 and is conveyed to the fixing unit 9 along the conveyance guide 8. The sheet material P then passes through a nip between the heating roller 9a and the pressure roller 9b that constitute the fixing unit 9. The toner image subjected to a pressing and heating fixing process at the nip is fixed to the sheet material P. The sheet material P subjected to the toner-image fixing process is conveyed to the discharge roller pair 10 and is discharged onto the output tray 11.
Referring to
In the above description, the charging roller 66, the developing roller 32, the transfer roller 7, and the cleaning member 77 constitute a processing unit working on the drum 62.
Cartridge Configuration
The overall configuration of the cartridge B will be described with reference to
The cartridge B is what is called a process cartridge including the cleaning unit 60 and the developing unit 20. The process cartridge is an integrated combination of an electrophotographic photosensitive member and a processing unit for processing the electrophotographic photosensitive member, including at least one of a charging device, a developing device, and a cleaning unit and is detachably mounted to the main body of an electrophotographic image forming apparatus.
The cleaning unit 60 includes the drum 62, the charging roller 66, the cleaning member 77, and the cleaning housing 71 that supports them. As illustrated in
The cleaning member 77 includes a rubber blade 77a, which is a blade-like elastic member formed of rubber, or an elastic material, and a supporting member 77b that supports the rubber blade 77a. The rubber blade 77a is in contact with the drum 62 counter to the rotation direction of the drum 62. In other words, the rubber blade 77a is in contact with the drum 62 such that its distal end is directed upstream of the rotation direction of the drum 62.
The waste toner removed from the surface of the drum 62 by the cleaning member 77 is stored in the waste-toner chamber 71b formed by the cleaning housing 71 and the cleaning member 77. A leakproof sheet 65 for preventing the waste toner from leaking from the cleaning housing 71 is disposed at the edge of the cleaning housing 71 so as to be in contact with the drum 62.
The charging roller 66 is rotatably mounted to the cleaning unit 60 via charging-roller bearings 67 at both ends of the cleaning housing 71 in the longitudinal direction (substantially parallel to the axis of rotation of the drum 62). The charging roller 66 is brought into pressure-contact with the drum 62 because the charging-roller bearings 67 are pushed toward the drum 62 by urging members 68. The charging roller 66 is rotated with the rotation of the drum 62.
The developing unit 20 includes the developing roller 32, a developer container 23 that supports the developing roller 32, a developing blade 42, and so on. The developing roller 32 is rotatable mounted to the developer container 23 using bearing members 26 and 27 provided at both ends. The developing roller 32 includes a magnet roller 34 therein. The developing unit 20 includes the developing blade 42 for adjusting the toner layer on the developing roller 32. Roller-shaped space holding members 38 are rotatably attached to both ends of the developing roller 32. The space holding members 38 and the drum 62 are in contact with each other so that the developing roller 32 is held with a slight clearance from the drum 62. A leakproof sheet 33 for preventing toner from leaking from the developing unit 20 is disposed at the edge of a bottom member 22 so as to be in contact with the developing roller 32. The toner chamber 29 formed by the developer container 23 and the bottom member 22 is provided with the conveying member 43. The conveying member 43 stirs the toner contained in the toner chamber 29 and conveys the toner to the toner supply chamber 28.
As illustrated in
A first end 46Lb of an urging member 46L on the non-drive side is fixed to a surface 23k of the developer container 23, and a second end 46La comes into contact with a surface 711, which is a part of the cleaning unit 60. A first end 46Rb of an urging member 46R on the drive side is fixed to a surface 26b of the bearing member 26, and a second end 46Ra comes into contact with a surface 71k, which is part of the cleaning unit 60.
In the present embodiment, the urging member 46R and the urging member 46L are compressed springs. By urging the developing unit 20 against the cleaning unit 60 by the urging force of the springs, the developing roller 32 is reliably pushed against the drum 62. The developing roller 32 is held at a predetermined interval from the drum 62 by the space holding members 38 attached to both ends of the developing roller 32.
Configuration of Apparatus Main Body
Referring next to
The apparatus main body A has a casing formed of plastic or the like. The casing is made up of a side plate 15 on the drive side, a side plate 16 on the non-drive side, and a front plate 18 and a back plate 100 connecting the side plates 15 and 16 together. The apparatus main body A includes an openable cover 13 supported so as to be rotatable with respect to the casing. The cartridge B becomes detachable from the apparatus main body A through a cartridge insertion opening 17 which is exposed by opening the openable cover 13. Upper guide rails 15g and 16d and lower guide rails 15h and 16e that guide the cartridge B at the attachment and detachment of the cartridge B, which will be described in detail in
Drive Unit
Referring to
The driving force is supplied to the cartridge B by the driving-force transmission member 81. A second gear portion 81e of the driving-force transmission member 81 engages with a drive gear 105 that is rotated by the driving force transmitted from the motor 104 via the gears on the outside of the side plate 15, so that the driving force from the motor 104 is transmitted thereto. A coupling recess 81b and a first gear portion 81a protrude from a hole 15k provided in the side plate 15 to the inside of the side plate 15 so that the driving force can be transmitted to the cartridge B.
The transfer roller 7 is rotatably mounted to the back plate 100 via bearing members 7a at both ends. The transfer roller 7 is configured to apply a predetermined contact pressure to the photosensitive drum 62 using transfer pressure springs 7b attached to the bearing members 7a. The transfer roller 7 comes into contact with the photosensitive drum 62 to form a transfer nip and conveys the sheet material P conveyed from the conveying roller pair 5c to the fixing unit 9 while transferring the toner image. The transfer roller 7 is not connected to the drive train and is driven by the photosensitive drum 62.
The pressure roller 9b and the heating roller 9a are fixed to a fixing frame 9c to form the fixing unit 9. The fixing frame 9c is fixed to the upper surfaces of the side plate 15 and the side plate 16 using screws or the like (not shown). In the fixing unit 9, a pressure-roller drive gear (not shown) is fixed to one end of the pressure roller 9b. The pressure roller 9b rotates by receiving the driving force from the motor 104 serving as a drive source via the drive train. The sheet material P conveyed from the transfer portion is conveyed to the discharge roller pair 10 while the toner image is fixed to the sheet material P through the fixing roller pair.
Configuration of Vicinity of Driving-Force Transmission Member 81
Next, the configuration of the driving-force transmission member 81 and the vicinity thereof will be described.
Driving-Force Transmission Member 81
Next, the configuration of the driving-force transmission member 81 will be described with reference to
A central portion 81d of the driving-force transmission member 81 in the longitudinal direction AM has a clearance M from the hole 15k in the side plate 15. The driving-force transmission member 81 is supported so as to be slightly movable within the clearance M when the cartridge B is not mounted to the apparatus main body A. The following description is made on the assumption that the axis of rotation of the driving-force transmission member 81 is parallel to the longitudinal direction AM.
The driving-force transmission member 81 includes the first gear portion 81a (a first helical gear portion), the second gear portion (a second helical gear portion) 81e, and the coupling recess 81b on the non-drive side. A distal end 81b1 is provided at the distal end of the coupling recess 81b. In the driving-force transmission member 81, the coupling recess 81b, the first gear portion 81a, and the second gear portion 81e are disposed in that order from the non-drive side to the drive side in the longitudinal direction AM.
Cylindrical Cam 86
Next, the cylindrical cam 86 for moving the driving-force transmission member 81 in the longitudinal direction AM will be described.
As illustrated in
Mounting Cartridge B to Apparatus Main Body A
Next, mounting of the cartridge B will be described.
The cartridge B is positioned in the apparatus main body A in the longitudinal direction AM in the process of mounting described above.
Arrangement of Driving-Force Transmission Member 81 and Cartridge B
Next, the arrangement of the driving-force transmission member 81 and the cartridge B will be described.
As illustrated in
As illustrated in
A portion where the developing-roller gear portion 30a and the first gear portion 81a engage with each other is referred to as an engaging portion MP1, and a portion where the second gear portion 81e and the drive gear 105 engage with each other is referred to as an engaging portion MP2. When the cartridge B is mounted, the developing roller gear portion 30a comes into contact with the first gear portion 81a at the engaging portion MP1 to apply a repulsive force in a repulsive direction FD, so that the driving-force transmission member 81 moves in the repulsive direction FD. Since the engaging portion MP1 is located upstream from the straight line L1 in the mounting direction AL, the vector of the repulsive direction FD contains the component of the mounting direction AL. The drive gear 105 is located downstream in the moving direction (repulsive direction FD) of the driving-force transmission member 81, and the engaging portion MP2 is located downstream from the straight line L1 in the mounting direction AL. This allows the engagement of the second gear portion 81e and the drive gear 105 to be maintained even if the driving-force transmission member 81 receives the repulsive force, reliably transmitting the driving force from the motor 104 to the second gear portion 81e.
Operation of Closing Door 13
Next, a state in which the openable cover 13 is closed after the cartridge B is mounted to the apparatus main body A and the cartridge B is positioned at a predetermined position will be described.
The side plate 15 includes a first positioning portion 15a and a second positioning portion 15b serving as positioning portions and a rotation stopping portion 15c. The side plate 16 includes a positioning portion 16a and a rotation stopping portion 16c. The cartridge B includes a first positioning portion 73d and a second positioning portion 73f at the drive-side end. The cartridge pressing members 1 and 2 are rotatably attached to both ends of the openable cover 13 in the longitudinal direction. The cartridge pressing springs 19 and 21 are attached to both ends in the longitudinal direction of the front plate 18 of the apparatus main body A. The cartridge B includes pressed portions 73e and 710 serving as urging-force receiving portions at positions facing the cartridge pressing members 1 and 2.
As illustrated in
In the state illustrated in
Thrust Force Applied to Driving-Force Transmission Member 81
Referring next to
As illustrated in
Next, the twisting directions of the coupling recess 81b, the first gear portion 81a, and the second gear portion 81e will be described. Let a direction parallel to the longitudinal direction AM and directed from the non-drive side to the drive side be +Z-direction (a predetermined direction), a counterclockwise direction viewed in the +Z-direction be N, and a rotation direction when the driving-force transmission member 81 is driven by the motor 104 be R (opposite to the counterclockwise direction N).
The coupling recess 81b of the driving-force transmission member 81 is a twisted triangular prismatic hole whose cross section is triangular in shape. The side of the twisted triangular hole is a driving-force transmission surface 81b3. The driving-force transmission surface 81b3 of the coupling recess 81b is twisted in the same direction as the rotation direction R from the downstream side to the upstream side in the +Z-direction, as viewed in the +Z-direction. “As viewed in the +Z-direction” stands for “when the driving-force transmission member 81 is viewed from the coupling protrusion 63b (cartridge coupling) of the cartridge B mounted to the apparatus main body A.
The first gear portion 81a of the driving-force transmission member 81 is a helical gear. The helical teeth are twisted in the same direction as the rotation direction R from the downstream side to the upstream side in the +Z-direction as viewed in the +Z-direction. In other words, the helical teeth of the first gear portion 81a are twisted in the same direction as that of the driving-force transmission surface 81b3. The second gear portion 81e of the driving-force transmission member 81 is a helical gear. The helical teeth are twisted in a direction opposite to the rotation direction R from the downstream side to the upstream side in the +Z-direction as viewed in the +Z-direction. The drive gear 105 that transmits the driving force from the motor 104 serving as a drive source to the second gear portion 81e of the driving-force transmission member 81 is a helical gear, and the helical teeth are twisted in a direction opposite to that of the helical teeth of the second gear portion 81e. The pitch circle radius of the first gear portion 81a is larger than the maximum radius of the driving-force transmission surface 81b3 in the radial direction centered on the rotation center of the driving-force transmission member 81.
Next, the torsional directions of the coupling protrusion 63b and the gear portion 30a will be described. A direction parallel to the longitudinal direction AM and directed from the drive side to the non-drive side is referred to as −Z-direction. Let a clockwise direction viewed in the −Z-direction be O (centered on the coupling protrusion 63b) and P (centered on the developing roller gear 30).
As illustrated in
When the drive gear 105 is rotated in the rotation direction R by the motor 104, the driving-force transmission member 81 is urged in the −Z-direction by a thrust force FB in the −Z-direction of the force of engagement between the second gear portion 81e of the driving-force transmission member 81 and the drive gear 105, as illustrated in
Referring to
As described above, the thrust forces FA, FB, and FC that act on the driving-force transmission member 81 during driving act in the same direction (−Z-direction) in the longitudinal direction AM. This causes the driving-force transmission member 81 to come into contact with a predetermined longitudinal positioning portion (in the present embodiment, the recessed bottom surface 73i of the cartridge B positioned in the longitudinal direction AM with respect to the side plate 15) so that its position in the longitudinal direction AM is determined. In other words, all of the thrust forces FA, FB, and FC function as forces to butt the driving-force transmission member 81 to the predetermined longitudinal positioning portion. This enables the driving-force transmission member 81 to butt against the predetermined positioning portion with stability. This allows the spring force of the driving-force-transmission-member spring 84 that urges the driving-force transmission member 81 to the non-drive side in the longitudinal direction AM to be set extremely small, thereby decreasing the force to operate the openable cover 13. In other words, the spring force of the driving-force-transmission-member spring 84 has only to bring the butting surface 81g into contact with the first end 86c of the cylindrical cam 86 to retract the driving-force transmission member 81 during non-driving during which the thrust forces FA, FB, and FC are not generated.
In the above embodiment, the predetermined positioning portion against which the driving-force transmission member 81 butts is the recessed bottom surface 73i of the drum bearing 73 of the cartridge B positioned with respect to the side plate 15, as illustrated in
Next, positioning of the driving-force transmission member 81 in the longitudinal direction AM by the recessed bottom surface 73i of the drum bearing 73 of the cartridge B positioned with respect to the side plate 15 will be described. This increases the positional accuracy in the longitudinal direction AM of the driving-force transmission member 81, the coupling protrusion 63b of the cartridge B, and the gear portion 30a of the developing roller gear 30. If the amount of retraction of the driving-force transmission member 81 in the longitudinal direction AM is made as small as possible, the apparatus main body A can be reduced in size in the longitudinal direction AM. The minimum amount of retraction necessary for preventing the coupling protrusion 63b from interfering with the coupling recess 81b has been determined. Therefore, the increase in the positional accuracy of the driving-force transmission member 81 and the coupling protrusion 63b allows the amount of retraction of the driving-force transmission member 81 to be set as small as possible while ensuring the minimum amount of retraction required, reducing the size of the apparatus main body A in the longitudinal direction AM. By making the amount of retraction of the driving-force transmission member 81 as small as possible, the width of the gear portion 30a of the developing roller gear 30 in the longitudinal direction AM can also be made as small as possible.
In the present embodiment, the engaging force of the developing roller gear is used as a force to move the driving-force transmission member 81 to the drive side. Alternatively, an idle gear that drives a load member, such as the developing roller 32 or the first conveying member 43, may also be used for assist.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
Number | Date | Country | Kind |
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2016-118182 | Jun 2016 | JP | national |
The present application is a continuation of U.S. patent application Ser. No. 15/615,708, filed Jun. 6, 2017, entitled “ELECTROPHOTOGRAPHIC IMAGE FORMING APPARATUS HAVING A DRIVING-FORCE TRANSMISSION MEMBER FEATURING FIRST AND SECOND HELICAL GEAR PORTIONS WITH OPPOSING TWIST DIRECTIONS”, the content of which is expressly incorporated by reference herein in its entirety. Further, the present application claims priority from Japanese Patent Application No. 2016-118182, filed Jun. 14, 2016, which is also hereby incorporated by reference herein in its entirety.
Number | Name | Date | Kind |
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20120269532 | Watanabe | Oct 2012 | A1 |
20160041519 | Sato | Feb 2016 | A1 |
Number | Date | Country | |
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20190243306 A1 | Aug 2019 | US |
Number | Date | Country | |
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Parent | 15615708 | Jun 2017 | US |
Child | 16386989 | US |