One-way clutch mechanism, drive unit, and image forming apparatus

Abstract

The present invention provides a one-way clutch mechanism, a drive device, and an image forming apparatus that enable the common use of components between two one-way clutch mechanisms whose rotation directions during drive transmission of input components are different from each other. [Solution] Each of the protrusions (111b, 173b, 193b) of the second engaging portion of the common joint member 110, which is a joint member of the one-way clutch mechanism (70, 90), and the output engaging portion of the output gear (73, 93), which is an output member, has a first inclined surface (111b3, 173b3, 193b3) from the top of the protrusion that gradually decreases in height toward the rotational direction when drive is transmitted, and a second inclined surface (111b4, 173b4, 193b4) from the top of the protrusion that gradually decreases in height toward the rotational direction when drive is disconnected.

Description

Technical Field

[0001] The present invention relates to a one-way clutch mechanism, a driving device, and an image forming apparatus.

Background Art

[0002] Conventionally, the following one-way clutch mechanism has been known. That is, the one-way clutch mechanism includes an input engagement portion, an input member to which a driving force is input from a driving source, an output member that is arranged coaxially with the input member, has an output engagement portion, and outputs a driving force, and a joint member that is arranged movably in the axial direction between the input member and the output member and has a first engagement portion that engages with the input engagement portion and a second engagement portion that engages with the output engagement portion. When the input member rotates in the driving transmission rotation direction, which is the rotation direction when the input member outputs a driving force from the output member, the input engagement portion and the first engagement portion engage with each other, and the second engagement portion and the output engagement portion engage with each other to perform driving transmission. On the other hand, when the input member rotates in the driving interruption rotation direction opposite to the driving transmission rotation direction, the engagement between the second engagement portion and the output engagement portion is disengaged to interrupt driving transmission, which is a one-way clutch mechanism.

[0003] Patent Document 1 describes a one-way clutch mechanism in which the second engagement portion of a driving transmission member, which is a joint member, has the following configuration. That is, the second engagement portion is provided on an opposing surface perpendicular to the axial direction facing the output gear, which is the output member of the driving transmission member, and has a configuration in which a plurality of convex portions protruding in the axial direction in the circumferential direction are arranged side by side. Each convex portion is composed of a plane perpendicular to the circumferential direction (parallel to the axial direction) and an inclined surface whose height gradually decreases as it goes to the upstream side in one direction, which is the rotation direction in which driving transmission is performed, from the top of the convex portion, and has a right triangle shape when viewed from the radial direction.

[0004] The output engagement portion of the output gear is provided on an opposing surface perpendicular to the axial direction, facing the drive transmission member, and consists of multiple protrusions arranged in a row that project axially in the circumferential direction. Each protrusion is composed of a plane perpendicular to the circumferential direction (parallel to the axial direction) and an inclined surface whose height gradually decreases as it moves downstream in one direction, which is the rotational direction in which drive transmission takes place, from the top of the protrusion. When viewed from the radial direction, the protrusion has the shape of a right triangle.

[0005] The opposing surface of the drive transmission member facing the input gear, which is the input member, has a first engagement portion that protrudes in the axial direction and engages with the input engagement portion of the input gear, and an input-side inclined surface that extends from the first engagement portion toward the upstream side in the aforementioned direction and whose height gradually decreases.

[0006] When the drive motor rotates in the forward direction and the input gear rotates in the direction of drive transmission, the input engagement portion of the input gear contacts the inclined surface on the input side of the drive transmission member from the axial direction, pushing the drive transmission member toward the output gear and moving it toward the output gear. Then, the input engagement portion of the input gear abuts against the first engagement portion of the drive transmission member from the circumferential direction, engaging with the first engagement portion, transmitting driving force from the input gear to the drive transmission member, and causing the drive transmission member to rotate together with the input gear.

[0007] When the drive transmission member rotates, the planes of each protrusion on the second engagement portion of the drive transmission member abut against the planes of each protrusion on the output engagement portion of the output gear, causing the second engagement portion to engage with the output engagement portion, and the driving force is transmitted from the drive transmission member to the output gear.

[0008] When the drive motor rotates in reverse and the input gear rotates in the opposite direction to the drive transmission rotation direction (drive disconnection rotation direction), the input engagement part separates from the inclined surface on the input side. Then, when the input gear rotates by a predetermined amount in the drive disconnection rotation direction, the input engagement part abuts against the first engagement part of the drive transmission member from the opposite direction, and the input engagement part engages with the first engagement part again, the driving force is transmitted from the input gear to the drive transmission member, and the drive transmission member rotates together with the input gear.

[0009] When the drive transmission member rotates with the input gear in the rotational direction when the drive is cut off, the inclined surfaces of each protrusion of the output engagement part push the inclined surface of the second engagement part toward the input gear. As described above, when the drive motor rotates in reverse, the input engagement part is separated from the input-side inclined surface, so the drive transmission member moves toward the input member due to the pushing by the inclined surfaces of each protrusion of the output engagement part, the engagement between the second engagement part and the output engagement part is released, and the drive transmission is cut off. [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] However, there was a challenge in standardizing components between two one-way clutch mechanisms where the rotational directions of input components such as input gears were different. [Means for solving the problem]

[0011] To solve the above-mentioned problems, the present invention provides an input member having an input engagement portion to which a driving force is input from a drive source; an output member disposed coaxially with the input member and having an output engagement portion to output the driving force; and a joint member disposed axially movable between the input member and the output member and having a first engagement portion that engages with the input engagement portion and a second engagement portion that engages with the output engagement portion, wherein when the input member rotates in the drive transmission rotation direction, which is the rotation direction when the output member outputs the driving force, the input engagement portion and the first engagement portion engage, and the second engagement portion and the output engagement portion engage to perform drive transmission, and when the input member rotates in the drive interruption rotation direction opposite to the drive transmission rotation direction, the second engagement portion and the front A one-way clutch mechanism that disconnects drive transmission by disengaging from the output engagement portion, wherein the second engagement portion is provided on the axially perpendicular opposing surface of the joint member facing the output member, and has a plurality of axially projecting protrusions arranged in a circumferential direction, and the output engagement portion is provided on the axially perpendicular opposing surface of the output member facing the joint member, and has a plurality of axially projecting protrusions arranged in a circumferential direction, and each protrusion of the second engagement portion and each protrusion of the output engagement portion is characterized by having a first inclined surface from the top of the protrusion toward the rotation direction during drive transmission, and a second inclined surface from the top of the protrusion toward the rotation direction when the drive is disconnected. [Effects of the Invention]

[0012] According to the present invention, it is possible to standardize components between two one-way clutch mechanisms in which the rotational directions of the input members are different. [Brief explanation of the drawing]

[0013] [Figure 1] A schematic diagram showing a printer according to this embodiment. [Figure 2] An enlarged schematic diagram showing the photoreceptor and its surrounding components in a printer according to this embodiment. [Figure 3]A schematic diagram of a printer showing the cover in the open position. [Figure 4] A perspective view showing the basic configuration of the drive unit. [Figure 5] A perspective view showing the forward rotation one-way clutch mechanism and the reverse rotation one-way clutch mechanism in the same basic configuration. [Figure 6] This diagram illustrates the drive transmission when the drive motor is rotating in the forward direction in the same basic configuration. [Figure 7] This diagram illustrates the drive transmission when the drive motor reverses in the same basic configuration. [Figure 8] This diagram illustrates the operation of the forward rotation one-way clutch mechanism when the drive motor is rotating in the forward direction in the same basic configuration. [Figure 9] This diagram illustrates the operation of the reverse one-way clutch mechanism when the drive motor reverses in the same basic configuration. [Figure 10] This figure shows the case where the forward rotation joint member and forward rotation output gear shown in Figure 7 are assembled to the reverse one-way clutch mechanism in the same basic configuration. [Figure 11] A perspective view showing the forward-rotating one-way clutch mechanism and the reverse-rotating one-way clutch mechanism of this embodiment. [Figure 12] A perspective view showing the common joint member in this embodiment. [Figure 13] (a) is a diagram illustrating the operation of the forward-rotating one-way clutch mechanism in this embodiment when the drive motor is rotating in reverse, and (b) is a diagram illustrating the operation of the reverse-rotating one-way clutch mechanism 90 in this embodiment when the drive motor is rotating in the forward direction. [Figure 14] (a) is a diagram illustrating the operation of the forward-rotating one-way clutch mechanism in this embodiment when the drive motor is rotating in the forward direction, and (b) is a diagram illustrating the operation of the reverse-rotating one-way clutch mechanism in this embodiment when the drive motor is rotating in the reverse direction. [Figure 15] A perspective view showing an example of a configuration in which the output gear is shared between the forward-rotating one-way clutch mechanism and the reverse-rotating one-way clutch mechanism. [Figure 16](a) is a schematic diagram showing a modified example of a forward one-way clutch mechanism, and (b) is a schematic diagram showing a modified example of a reverse one-way clutch mechanism. [Figure 17] A diagram showing a modified example of each convex portion of the second engaging portion of the common joint member and each convex portion of the output engaging portion of the output gear.

Embodiments for Carrying Out the Invention

[0014] Hereinafter, as an image forming apparatus to which the present invention is applied, an electrophotographic printer (hereinafter simply referred to as a printer) that forms an image by an electrophotographic method will be described as an example. The present invention will be described with respect to an image forming apparatus using an electrophotographic method, but is not limited thereto, and can also be applied to image forming apparatuses such as an inkjet method and a stencil printing method.

[0015] First, the basic configuration of the printer according to the embodiment will be described. FIG. 1 is a schematic diagram showing a printer according to the embodiment. The directions of X, Y, and Z shown in the figure are as follows, and the same applies to other figures. The X direction is a view of FIG. 1 from the front of the printer, parallel to the left and right of the apparatus, and is a direction from left to right. The Y direction is parallel to the front and back of the apparatus and is a direction from front to back. The Z direction is vertical and is a direction from bottom to top.

[0016] In the same figure, this printer includes a photoreceptor 1 as a latent image carrier, a paper feed cassette 100 as a sheet storage means configured to be detachable from the main body housing 50, and the like. Inside the paper feed cassette 100, a plurality of recording sheets S are stored in a state of a sheet bundle.

[0017] The recording sheet S in the paper feed cassette 100 is fed out of the cassette by the rotational drive of the main unit paper feed roller 41. At the separation nip between the main unit paper feed roller 41 and the separation pad 48, only the uppermost sheet is separated and fed out, reaching the main unit paper feed path R1, which is the first transport path. Subsequently, the recording sheet S is caught (held) by the transport nip of the upper transport roller pair, which is the relay roller pair 42, and transported from the upstream side to the downstream side in the transport direction within the main unit paper feed path R1. Note that at least one of the transport roller pair may be a belt transport member pair.

[0018] The downstream end of the main paper feed path R1 is connected to the common transport path R3, where a pair of register rollers 43 is installed. A register sensor 49 for detecting the recording sheet S is located upstream of the register roller pair 43 in the transport direction on the common transport path R3. When the recording sheet S is stopped, its transport is temporarily halted when its leading edge comes into contact with the nip of the stopped register roller pair 43. At this point, the skew of the recording sheet S is corrected. The register sensor 49 is also used for initial operation and checking the remaining sheets when the device malfunctions and stops are resolved.

[0019] The registration roller pair 43 starts rotating at the timing when the recording sheet S can be superimposed on the toner image on the surface of the photoreceptor 1 at the transfer nip, and feeds the recording sheet S toward the transfer nip. At the same time, the relay roller pair 42 starts rotating to resume the transport of the recording sheet S, which had been temporarily stopped.

[0020] The main body housing 50 of this printer is equipped with a manual feed section 30, which serves as a manual feed delivery unit, and includes a manual feed tray 31, a manual feed roller 32, a separation pad 33, a manual feed bottom plate 34, and a manual feed bottom plate cam 35. Recording sheets S that are manually fed into the manual feed tray 31 of this manual feed section 30 are fed from the manual feed tray 31 to the manual feed path R2, which is a second transport path, by the rotational drive of the manual feed roller 32. The downstream end of the manual feed path R2 merges with the downstream end of the main body feed path R1 into the common transport path R3. The recording sheets S fed by the manual feed roller 32 undergo a separation nip due to contact between the manual feed roller 32 and the separation pad 33 within the manual feed path R2, and are then fed into the common transport path R3 and transported to the registration roller pair 43. Subsequently, similar to the recording sheet S fed from the paper feed cassette 100, it passes through the registration roller pair 43 and is then sent to the transfer nip.

[0021] Figure 2 is an enlarged schematic diagram showing the photoreceptor 1 and its surrounding structure in this printer. In the diagram, a drum-shaped photoreceptor 1 is driven to rotate clockwise, and around it are arranged a cleaning blade 2, a recovery screw 3, a charging roller 4, a charging cleaning roller 5, a scraper 6, a latent image writing device 7, a developing device 8, a transfer roller 10, and the like. The charging roller 4, which has a conductive rubber roller section, rotates while in contact with the photoreceptor 1 to form a charging nip. A voltage is applied to this charging roller 4 from a charging power supply. As a result, the surface of the photoreceptor 1 is uniformly charged by the charging bias that is generated between the surface of the photoreceptor 1 and the surface of the charging roller 4 at the charging nip.

[0022] The latent image writing device 7 is equipped with an LED array and performs optical writing on the uniformly charged surface of the photoreceptor 1 using LED light. The potential of the region of the uniformly charged surface of the photoreceptor 1 that is irradiated with writing light is attenuated, and an electrostatic latent image is formed on the surface of the photoreceptor 1.

[0023] The electrostatic latent image passes through the developing area facing the developing device 8 as the photoreceptor 1 rotates. The developing device 8 has a circulating transport section and a developing section, and the circulating transport section contains a developer containing toner and a magnetic carrier. The circulating transport section has a first screw 8b that transports the developer for supply to the developing roller 8a, and a second screw 8c that transports the developer in an independent space located directly below the first screw 8b. Furthermore, it also has an inclined screw 8d for transferring the developer from the second screw 8c to the first screw 8b. The developing roller 8a, the first screw 8b, and the second screw 8c are arranged in a parallel position to each other. In contrast, the inclined screw 8d is arranged in an inclined position relative to them.

[0024] The first screw 8b, as it rotates, transports the developer from the back to the front in a direction perpendicular to the plane of the paper in the figure. At this time, it supplies some of the developer to the developing roller 8a, which is positioned opposite it. The developer transported by the first screw 8b to near the front end in a direction perpendicular to the plane of the paper in the figure is dropped onto the second screw 8c.

[0025] The second screw 8c receives the used developer from the developing roller 8a and, driven by its own rotation, transports the received developer from the back to the front in a direction perpendicular to the plane of the paper shown in the figure. The developer transported by the second screw 8c to near the front edge in a direction perpendicular to the plane of the paper shown in the figure is then passed to the inclined screw 8d. Then, driven by the rotation of the inclined screw 8d, it is transported from the front to the back in a direction perpendicular to the plane of the paper shown in the figure, and then passed to the first screw 8b near the back edge in the same direction.

[0026] The developing roller 8a comprises a rotatable developing sleeve made of a cylindrical non-magnetic material and a magnetic roller fixed inside the sleeve so as not to be carried along with the developing sleeve. A portion of the developer being transported by the first screw 8b is picked up from the surface of the developing sleeve by the magnetic force of the magnetic roller. The developer carried on the surface of the developing sleeve is transported as the developing sleeve rotates, and its layer thickness is regulated as it passes the position where the developing sleeve and the doctor blade face each other. After that, it is transported in the developing region facing the photoreceptor 1, rubbing against the surface of the photoreceptor 1.

[0027] A development bias of the same polarity as the uniform charging potential (skin potential) of the toner and photoreceptor 1 is applied to the developing sleeve. The absolute value of this development bias is greater than the absolute value of the latent image potential and less than the absolute value of the skin potential. Therefore, in the developing region, a development potential acts between the electrostatic latent image of photoreceptor 1 and the developing sleeve, causing the toner to electrostatically move from the developing sleeve side to the photoreceptor 1 side. On the other hand, a skin potential acts between the skin of photoreceptor 1 and the developing sleeve, causing the toner to electrostatically move from the photoreceptor 1 side to the developing sleeve side. As a result, in the developing region, the toner selectively adheres to the electrostatic latent image of photoreceptor 1, and the electrostatic latent image is developed.

[0028] As the developing sleeve rotates, the developer enters the opposing region between the developing sleeve and the second screw 8c. In this opposing region, a repulsive magnetic field is formed by two magnetic poles of the same polarity among the multiple magnetic poles provided on the magnetic roller. The developer that enters the opposing region is separated from the surface of the developing sleeve by the action of the repulsive magnetic field and is collected by the second screw 8c.

[0029] The developer conveyed by the inclined screw 8d contains the developer recovered from the developing roller 8a, and since this developer contributes to development in the developing area, the toner concentration decreases. The developing device 8 is equipped with a toner concentration sensor that detects the toner concentration of the developer conveyed by the inclined screw 8d. The control unit 80, which consists of semiconductor circuits such as a CPU, outputs a replenishment operation signal to replenish toner to the developer conveyed by the inclined screw 8d as needed, based on the detection result from the toner concentration sensor.

[0030] A toner cartridge 9 is positioned above the developing device 8. This toner cartridge 9 agitates the toner it contains using an agitator 9b fixed to a rotating shaft member 9a. The toner supply member 9c is rotated according to a supply operation signal output from the control unit 80, supplying an amount of toner corresponding to the amount of rotation to the inclined screw 8d of the developing device 8.

[0031] The toner image formed on the photoreceptor 1 by development enters the transfer nip where the photoreceptor 1 and the transfer roller 10 come into contact, as the photoreceptor 1 rotates. A voltage opposite in polarity to the latent image potential of the photoreceptor 1 is applied to the transfer roller 10, thereby creating a transfer bias within the transfer nip.

[0032] As described above, the registration roller pair 43 feeds the recording sheet S toward the transfer nip at a timing that allows it to be superimposed on the toner image on the photoreceptor 1 within the transfer nip. The toner image on the photoreceptor 1 is transferred to the recording sheet, which is in close contact with the toner image in the transfer nip, due to the effects of the transfer bias and nip pressure.

[0033] After passing through the transfer nip, the surface of the photoreceptor 1 has residual toner that was not transferred to the recording sheet S. The residual toner is scraped off the surface of the photoreceptor 1 by the cleaning blade 2 which is in contact with the photoreceptor 1, and then transported by the recovery screw 3 and sent to the waste toner bottle.

[0034] The surface of the photoreceptor 1, cleaned by the cleaning blade 2, is then discharged by the static discharge means and then uniformly charged again by the charging roller 4. Foreign matter such as toner additives and toner that could not be completely removed by the cleaning blade 2 adheres to the charging roller 4, which is in contact with the surface of the photoreceptor 1. This foreign matter is transferred to the charging cleaning roller 5, which is in contact with the charging roller 4, and then scraped off from the surface of the charging cleaning roller 5 by the scraper 6, which is in contact with the charging cleaning roller 5. The scraped-off foreign matter falls onto the recovery screw 3 described above.

[0035] In Figure 1, the recording sheet S, having passed through the transfer nip where the photoreceptor 1 and the transfer roller 10 are in contact, is sent to the fuser 44. The fuser 44 forms a fuser nip through the contact between a fuser roller 44a, which contains a heat source such as a halogen lamp, and a pressure roller 44b that presses toward it. The toner image is fixed to the surface of the recording sheet S, which is sandwiched in the fuser nip, by the action of heating and pressurizing. After that, the recording sheet S, having passed through the fuser 44, goes through the paper output path R4 and is then sandwiched in the paper output nip of the paper output reversal roller pair 46.

[0036] This printer can switch between a single-sided mode, in which an image is formed on only one side of the recording sheet S, and a double-sided mode, in which an image is formed on both sides of the recording sheet S. In single-sided mode, or in double-sided mode when an image has already been formed on both sides of the recording sheet, the paper output reversal roller pair 46 continues to rotate in the forward direction, ejecting the recording sheet S from the paper output path R4 to the outside of the machine. The ejected recording sheet S is stacked in a stack section provided on the top surface of the main unit housing 50.

[0037] On the other hand, in double-sided mode, when an image is formed on only one side of the recording sheet S, the paper output reversal roller pair 46 is driven in reverse when the rear end of the recording sheet S enters the paper output nip of the paper output reversal roller pair 46. At this time, a switching claw 47 located near the downstream end of the paper output path R4 is activated, blocking the paper output path R4 and opening the entrance to the reversal resend path R5. The recording sheet S, which has started to move backward due to the reverse drive of the paper output reversal roller pair 46, is fed into the reversal resend path R5. The downstream end of the reversal resend path R5 merges with the upstream side of the registration roller pair 43 of the common transport path R3, and after being transported within the reversal resend path R5, it is resent to the registration roller pair 43 of the common transport path R3. After that, the toner image is transferred to the other side at the transfer nip, and then it is discharged outside the machine via the fuser 44, the paper output path R4, and the paper output reversal roller pair 46.

[0038] The fixing device 44, which is a unit of this embodiment, is equipped with a cleaning roller 44d, which is a contact / separation member that removes deposits such as toner and paper dust that adhere to the surface of the pressure roller 44b, which is the object to be contacted and separated from. This cleaning roller 44d moves in and out of contact with the pressure roller 44b by a contact / separation mechanism.

[0039] Furthermore, the fixing device 44 also includes components that constitute the section from the fixing nip to the switching claw 47 of the paper discharge path R4. Specifically, it includes a paper discharge guide member 59, a paper discharge reversal guide member 58, and a relay transport roller pair 51. The paper discharge guide member 59 has a guide portion 59a that faces the contact surface of the recording sheet S with the fixing roller 44a after it has passed the fixing nip, and guides the recording sheet S to the switching claw 47. The paper discharge reversal guide member 58 faces the contact surface of the recording sheet S with the pressure roller 44b after it has passed the fixing nip. The paper discharge reversal guide member 58 has a paper discharge guide portion 58a that guides the recording sheet S to the switching claw 47, and a reversal guide portion 58b that faces and guides the image forming surface of the recording sheet in the reversal re-feed path R5 after it has passed the switching claw 47. The paper discharge reversal guide member 58 also has driven rollers 52b of the reversal transport roller pair 52 that transport the recording sheet in the reversal re-feed path R5 attached to it.

[0040] Furthermore, an opening / closing cover 55 is provided on the left side of the main body housing 50 of the printer as shown in the figure. This opening / closing cover 55 is equipped with an inversion guide member 57 that faces and guides the non-image forming surface of the recording sheet in the inversion retransmission path R5, and the drive roller 52a of the inversion transport roller pair 52 is attached to the inversion guide member 57.

[0041] Figure 3 is a schematic diagram of the printer showing the open / close cover 55 in the open position. When the opening / closing cover 55 is opened, the fuser unit 44 is exposed, and the fuser unit 44 is attached to and detached from the printer body in the direction of arrow A in the figure.

[0042] Next, we will explain the basic configuration of the drive mechanism that this printer is equipped with. Figure 4 is a perspective view showing the basic configuration of the drive unit 60. This drive unit 60 transmits the driving force of the drive motor 61 to the paper ejection reversal roller pair 46, which is the first rotating body, and the fixing roller 44a, which is the second rotating body. The drive unit 60 includes a drive motor 61 which is the drive source, a motor input gear 62, a forward rotation one-way clutch mechanism 70, a reverse rotation one-way clutch mechanism 90, a paper discharge reversal output gear 63, and a fixing output gear 64. The forward rotation one-way clutch mechanism 70 transmits the driving force of the drive motor 61 when the drive motor 61 is rotating in the forward direction and disconnects the drive transmission when the drive motor 61 is rotating in the reverse direction. The reverse rotation one-way clutch mechanism 90 disconnects the driving force of the drive motor 61 when the drive motor 61 is rotating in the forward direction and transmits the driving force when the drive motor 61 is rotating in the reverse direction.

[0043] The motor input gear 62 meshes with the motor gear directly formed on the motor shaft 61a of the drive motor 61, the forward input gear 71 of the forward one-way clutch mechanism 70, and the reverse input gear 91 of the reverse one-way clutch mechanism 90. The motor input gear 62 transmits the driving force of the drive motor 61 to the forward input gear 71 and the reverse input gear 91.

[0044] The drive transmission path for the paper discharge reversal roller pair 46, which is the forward and reverse drive transmission path, consists of a motor input gear 62, a forward input gear 71, and a paper discharge reversal output gear 63. The first forward drive transmission path that rotates the fixing roller 44a in the forward direction when the drive motor 61 is rotating in the forward direction consists of a motor input gear 62, a forward one-way clutch mechanism 70, and a fixing output gear 64. The second forward drive transmission path that rotates the fixing roller 44a in the forward direction when the drive motor 61 is rotating in the reverse direction consists of a motor input gear 62, a reverse one-way clutch mechanism 90, a forward output gear 73 of the forward one-way clutch, and a fixing output gear 64.

[0045] Figure 5 is a perspective view showing the forward rotation one-way clutch mechanism 70 and the reverse rotation one-way clutch mechanism 90. The forward rotation one-way clutch mechanism 70 includes a forward rotation input gear 71 which is an input member, a forward rotation joint member 72 which is a joint member, and a forward rotation output gear 73 which is an output member. The forward rotation input gear 71, the forward rotation joint member 72, and the forward rotation output gear 73 are rotatably supported on a first support shaft 74. The forward rotation joint member 72 is supported on the first support shaft 74 so as to be axially movable between the forward rotation input gear 71 and the forward rotation output gear 73.

[0046] The forward rotation input gear 71 has a forward rotation input gear portion 71a that meshes with the motor input gear 62 and the paper output reversal output gear 63, and a forward rotation pushing portion 71b that pushes the forward rotation joint member 72 toward the forward rotation output gear 73. The forward rotation input gear 71 also has a forward rotation input engagement portion 71c that engages with the first forward rotation engagement portion 72a of the forward rotation joint member 72. Two forward rotation pushing portions 71b and forward rotation input engagement portions 71c are provided, spaced 180° apart in the rotational direction.

[0047] The forward rotation push portion 71b and the forward rotation input engagement portion 71c are provided on the opposing surfaces of the forward rotation input gear 71 that face the forward rotation joint member 72. The forward rotation push portion 71b has an inclined surface 71b1 that is inclined so as it goes upstream in the direction of rotation when the forward rotation input gear 71 is rotating in the forward direction (the direction in which the forward rotation input gear 71 rotates when the drive motor 61 is rotating in the forward direction), and a flat portion 71b2 that is perpendicular to the axial direction. The forward rotation input engagement portion 71c protrudes toward the forward rotation joint member 72 from the downstream end of the flat portion 71b2 in the direction of rotation when the forward rotation input gear 71 is rotating in the forward direction.

[0048] The forward rotation joint member 72 has a first forward rotation engagement portion 72a that protrudes toward the forward rotation input gear 71 and a second forward rotation engagement portion 72b that engages with the forward rotation output engagement portion 73b of the forward rotation output gear 73. Two first forward rotation engagement portions 72a are provided, spaced 180° apart in the rotational direction. The second forward rotation engagement portion 72b consists of a plurality of protrusions 172b that protrude toward the forward rotation output gear 73, and these protrusions 172b are arranged along the circumferential direction. Each protrusion 172b consists of a flat portion perpendicular to the circumferential direction and an inclined surface whose height decreases as it moves upstream in the rotational direction during drive transmission (reducing the amount of protrusion toward the forward rotation output gear), and is shaped like a right triangle when viewed from the radial direction.

[0049] The forward rotation output gear 73 is a two-stage gear and has a forward rotation output gear section 73a and a fixed output gear 64. The forward rotation output gear section 73a meshes with the reverse rotation output gear section 93a of the reverse rotation output gear 93. The forward rotation output gear 73 also has a forward rotation output engaging section 73b that engages with the second forward rotation engaging section 72b of the forward rotation joint member 72. The forward rotation output engaging section 73b consists of a plurality of protrusions 173b that project toward the forward rotation joint member 72, and these protrusions 173b are arranged along the circumferential direction. When viewed from the radial direction, each protrusion 173b is a right-angled triangle shape which is the left-right inversion of the protrusion 172b of the second forward rotation engaging section 72b. That is, each protrusion 173b consists of a flat section perpendicular to the circumferential direction and an inclined surface whose height decreases (the amount of protrusion toward the forward rotation joint member decreases) as it moves downstream in the rotational direction during drive transmission.

[0050] The reverse one-way clutch mechanism 90 includes a reverse input gear 91 which is an input member, a reverse joint member 92 which is a joint member, and a reverse output gear 93 which is an output member. The reverse input gear 91, the reverse joint member 92, and the reverse output gear 93 are rotatably supported on a second support shaft 94. The reverse joint member 92 is supported on the second support shaft 94 so as to be axially movable between the reverse input gear 91 and the reverse output gear 93.

[0051] The reverse input gear 91 has a reverse input gear portion 91a that meshes with the motor input gear 62, a reverse push portion 91b that pushes the reverse joint member 92 toward the reverse output gear 93, and a reverse input engaging portion 91c that engages with the first reverse engaging portion 92a of the reverse joint member 92.

[0052] The reverse push portion 91b and the reverse input engagement portion 91c are provided on the opposing surfaces of the reverse input gear 91 that face the reverse joint member 92. The reverse push portion 91b has an inclined surface 91b1 that is inclined so as to decrease in height towards the upstream side in the direction of rotation when the reverse input gear 91 is rotating in reverse (the direction in which the reverse input gear 91 rotates when the drive motor 61 is reversed), and a flat portion 91b2 that is perpendicular to the axial direction. The reverse input engagement portion 91c protrudes toward the reverse joint member 92 from the downstream end of the flat portion 91b2 in the direction of rotation when the reverse input gear 91 is rotating in reverse.

[0053] The reversing joint member 92 has a first reversing engagement portion 92a that protrudes toward the reversing input gear 91 and a second reversing engagement portion 92b that engages with the reversing output engagement portion 93b of the reversing output gear 93. The second reversing engagement portion 92b consists of a plurality of protrusions 192b that protrude toward the reversing output gear 93, and these protrusions 192b are arranged along the circumferential direction. When viewed from the radial direction, each protrusion 193b is in the shape of a right triangle, which is a left-right inversion of the protrusion 172b of the second forward rotation engagement portion 72b.

[0054] The reverse output gear 93 has a reverse output gear portion 93a that meshes with the forward output gear portion 73a of the forward output gear 73, and a reverse output engaging portion 93b that engages with the second reverse engaging portion 92b of the reverse joint member 92. The reverse output engaging portion 93b consists of a plurality of protrusions 193b that project toward the reverse joint member 92, and these protrusions 193b are arranged along the circumferential direction. When viewed from the radial direction, each protrusion 193b is a right-angled triangle that is a left-right inversion of the protrusion 192b of the second reverse engaging portion 92b.

[0055] In the following explanation, when there is no particular distinction between the components of the forward-rotating one-way clutch mechanism 70 and the components of the reverse-rotating one-way clutch mechanism 90, the terms "forward rotation" and "reverse rotation" may be omitted.

[0056] Figure 6 illustrates the drive transmission in the basic configuration of the drive unit 60 when the drive motor is rotating in the forward direction. As shown in Figure 6, when the drive motor is rotating forward, the motor shaft 61a rotates in the direction of A1 in the figure, and the motor input gear 62 rotates in the direction of arrow B1 in the figure. Then, the forward input gear 71 of the forward one-way clutch mechanism 70 rotates in the direction of arrow C1 in the figure, and the reverse input gear 91 of the reverse one-way clutch mechanism 90 rotates in the direction of arrow D1 in the figure. As the forward input gear 71 rotates in the direction of arrow C1, the paper discharge reversal output gear 63 that meshes with the forward input gear 71 rotates in the direction of arrow E1 in the figure, driving the paper discharge reversal roller pair 46 in the forward direction and ejecting the recording sheet S in the paper discharge path R4 to the outside of the machine.

[0057] Furthermore, as the forward input gear 71 rotates in the direction of arrow C1, the forward joint member 72 engages with the forward output gear 73. As a result, the driving force transmitted to the forward input gear 71 is transmitted to the forward output gear 73 via the forward joint member 72, causing the forward output gear 73 to rotate in the direction of arrow F1 in the figure. Then, the fixing output gear 64, which is integrally provided with the forward output gear 73, rotates together with the forward output gear 73, and the fixing roller 44a is driven to rotate in the forward direction.

[0058] Figure 7 illustrates the power transmission during reverse rotation of the drive motor. As shown in Figure 7, when the drive motor is reversed, the motor shaft 61a rotates in the opposite direction to that in Figure 6, in the direction of arrow A2 in the figure, and the motor input gear 62 rotates in the opposite direction to that in Figure 6, in the direction of arrow B2 in the figure. Then, the forward input gear 71 of the forward one-way clutch mechanism 70 rotates in the opposite direction to that in Figure 6, in the direction of arrow C2 in the figure, and the reverse input gear 91 of the reverse one-way clutch mechanism 90 rotates in the opposite direction to that in Figure 6, in the direction of arrow D2 in the figure. As the forward input gear 71 rotates in the direction of arrow C2, the paper discharge reversal output gear 63 that meshes with the forward input gear 71 rotates in the opposite direction to that in Figure 6, in the direction of arrow E2 in the figure, causing the paper discharge reversal roller pair 46 to be driven in reverse, and the recording sheet S in the paper discharge path R4 is fed into the reversal re-feed path R5.

[0059] Furthermore, as the reverse input gear 91 rotates in the direction of arrow D2, the reverse joint member 92 engages with the reverse output gear 93, and the driving force transmitted to the reverse input gear 91 is transmitted to the reverse output gear 93 via the reverse joint member 92, causing the reverse output gear 93 to rotate. As a result, the forward output gear 73, which meshes with the reverse output gear 93, rotates in the direction of arrow F1 in the figure, the same direction as in Figure 6. Consequently, the fixing output gear 64, which is integrally provided with the forward output gear 73, rotates together with the forward output gear 73 in the same direction as in Figure 6, and the fixing roller 44a is driven to rotate in the forward direction.

[0060] Thus, the paper ejection reversal roller pair 46 is driven in the forward direction when the drive motor 61 is rotating in the forward direction, and in the reverse direction when the drive motor 61 is rotating in the reverse direction, while the fixing roller 44a is driven in the forward direction both when the drive motor is rotating in the forward direction and when it is rotating in the reverse direction. This makes it possible to drive both a rotating body that is always driven in the forward direction and a rotating body that is driven in both forward and reverse directions with a single drive motor 61.

[0061] Next, the operation of the forward rotation one-way clutch mechanism 70 will be explained. Figure 8 illustrates the operation of the forward rotation one-way clutch mechanism 70 when the drive motor is rotating in the forward direction. As shown in Figure 8(a), the forward rotation input gear 71 receives the driving force from the motor input gear 62 to the drive motor 61 and rotates in the direction of arrow C1 in the figure. At this point, the tip of the first forward rotation engagement portion 72a of the forward rotation joint member 72 comes into contact with the inclined surface 71b1 of the forward rotation push portion 71b. As the forward rotation input gear 71 rotates, the first forward rotation engagement portion 72a is pushed toward the forward rotation output gear 73 by this inclined surface 71b1. As a result, the forward rotation joint member 72 moves toward the forward rotation output gear 73, as shown by arrow X1 in the figure.

[0062] As the tip of the first forward rotation engagement portion 72a ascends the inclined surface 71b1, and the tip of the first forward rotation engagement portion 72a reaches the flat surface 71b2 of the forward rotation pushing portion 71b, as shown in Figure 8(b), the forward rotation input engagement portion 71c abuts against the first forward rotation engagement portion 72a of the forward rotation joint member 72 from the direction of arrow C1. As a result, the forward rotation input engagement portion 71c engages with the first forward rotation engagement portion 72a, and the forward rotation joint member 72 rotates together with the forward rotation input gear 71.

[0063] Furthermore, the second forward rotation engagement portion 72b of the forward rotation joint member 72 engages with the forward rotation output engagement portion 73b of the forward rotation output gear 73, causing the forward rotation output gear 73 to rotate together with the forward rotation joint member 72, and the forward rotation output gear 73 to rotate in the direction of arrow F1. As a result, the fixing output gear 64, which is integrally provided with the forward rotation output gear 73, rotates together with the forward rotation output gear 73, and the fixing roller 44a is driven to rotate in the forward direction.

[0064] When the drive motor reverses direction, the forward one-way clutch mechanism 70 changes from the state shown in Figure 8(b) to the state shown in Figure 8(a), thereby interrupting the transmission of drive to the forward output gear 73. Specifically, the forward input gear 71 rotates in the opposite direction to arrow C1 from the state shown in Figure 8(b), and the first forward engagement portion 72a of the forward joint member 72 is released from contact with the flat portion 71b2 of the forward push portion 71b from the axial direction. As a result, an axial gap is created between the first forward engagement portion 72a and the forward push portion 71b, allowing the forward joint member 72 to move toward the forward input gear 71.

[0065] Then, when the forward input gear 71 rotates half a turn, the forward input engagement portion 71c abuts against the first forward engagement portion 72a in the opposite direction to arrow C1 in the figure, causing the forward joint member 72 to rotate in the opposite direction to arrow C1 in the figure. Meanwhile, the forward output gear 73 receives driving force from the reverse output gear 93 and rotates in the direction of arrow F1 in the figure. As a result, the second forward engagement portion 72b of the forward joint member 72 is pushed toward the forward input gear 71 by the inclined surface 173b2 of the protrusion 173b of the forward output engagement portion 73b of the forward output gear 73. At this time, as described above, the forward joint member 72 is separated from the forward pushing portion 71b and is movable toward the forward input gear. Therefore, the inclined surface 173b2 of the protrusion 173b of the forward rotation output engagement portion 73b pushes the forward rotation joint member 72 toward the forward rotation input gear 71, resulting in the state shown in Figure 8(a). As a result, the engagement between the second forward rotation engagement portion 72b of the forward rotation joint member 72 and the forward rotation output engagement portion 73b of the forward rotation output gear 73 is released, and the drive transmission is interrupted.

[0066] Next, the operation of the reverse one-way clutch mechanism 90 will be explained. Figure 9 illustrates the operation of the reverse one-way clutch mechanism 90 when the drive motor reverses direction. As the reverse input gear 91 rotates in the direction of arrow D2 in the figure, the driving force from the drive motor 61 is transmitted from the motor input gear 62 to the reverse input gear 91, causing the tip of the first reverse engagement portion 92a of the reverse joint member 92 to contact the inclined surface 91b1 of the reverse push portion 91b. As the reverse input gear 91 rotates, the first reverse engagement portion 92a is pushed towards the reverse output gear 93 by this inclined surface 91b1. As a result, the reverse joint member 92 moves towards the reverse output gear 93, as shown by arrow X2 in the figure.

[0067] Then, the tip of the first reversal engagement portion 92a ascends the inclined surface 91b1, and when the tip of the first reversal engagement portion 92a reaches the flat surface 91b2 of the reversal push portion 91b, as shown in Figure 9(b), the reversal input engagement portion 91c abuts against the first reversal engagement portion 92a of the reversal joint member 92 from the direction of arrow D2. As a result, the reversal input engagement portion 91c engages with the first reversal engagement portion 92a, and the reversal joint member 92 rotates together with the reversal input gear 91. In addition, the second reversal engagement portion 92b of the reversal joint member 92 engages with the reversal output engagement portion 93b of the reversal output gear 93, and the reversal output gear 93 rotates together with the reversal joint member 92, and the reversal output gear 93 rotates in the direction of arrow G1.

[0068] The reverse one-way clutch mechanism 90 interrupts the transmission of drive to the reverse output gear 93 in the same manner as the forward one-way clutch mechanism 70 when the drive motor 61 is rotating in the forward direction. That is, when the drive motor 61 is rotating in the forward direction, the reverse input gear 91 rotates in the opposite direction to arrow D2 shown in Figure 9(b), and the reverse joint member 92 moves away from the reverse push-in part 91b and becomes movable toward the reverse input gear. Then, when the reverse input gear 91 rotates half a turn in the opposite direction to arrow D2, the reverse input engaging part 91c abuts against the first reverse engaging part 92a in the opposite direction to arrow D2 in the figure, causing the reverse joint member 92 to rotate in the opposite direction to arrow D2 in the figure.

[0069] On the other hand, the reverse output gear 93 receives driving force from the forward output gear 73 and rotates in the direction of arrow G1 in the figure. As a result, the second reverse engagement portion 92b of the reverse joint member 92 is pushed toward the reverse input gear 91 by the inclined surface 193b2 of the protrusion 193b of the reverse output engagement portion 93b of the reverse output gear 93. Consequently, the reverse joint member 92 moves toward the reverse input gear 91, resulting in the state shown in Figure 9(a). This disengages the second reverse engagement portion 92b of the reverse joint member 92 from the reverse output engagement portion 93b of the reverse output gear 93, and the drive transmission is interrupted.

[0070] Next, the distinctive features of this embodiment will be described. In the drive unit 60 with this basic configuration, as shown in Figures 8 and 9, the protrusions 172b, 173b, 192b, and 193b of the second engaging portion of the joint member of each one-way clutch mechanism 70, 90 and the output engaging portion of the output gear are composed of a plane perpendicular to the circumferential direction and an inclined surface whose height (protrusion amount) decreases as it moves away from the top of the protrusion, forming a right-angled triangle when viewed from the radial direction. Furthermore, as shown in Figures 8 and 9, the right-angled triangle shape of each protrusion 192b of the second reverse-rotation engaging portion 92b is a left-right inversion of the right-angled triangle shape of each protrusion 192b of the second forward-rotation engaging portion 72b. Similarly, the right-angled triangle shape of each protrusion 193b of the reverse-rotation output engaging portion 93b is a left-right inversion of the right-angled triangle shape of each protrusion 173b of the forward-rotation output engaging portion 73b. Furthermore, the forward rotation push-in portion 71b of the forward rotation input gear 71 has a shape that is horizontally inverted in the figure compared to the reverse rotation push-in portion 91b of the reverse rotation input gear 91.

[0071] Figure 10 shows the case where the forward rotation joint member 72 and the forward rotation output gear 73 shown in Figure 7 are assembled to the reverse one-way clutch mechanism 90. As described above, when the drive motor 61 rotates in the forward direction, the reverse input engagement portion 91c abuts against the first forward engagement portion 72a of the forward joint member 72 in the opposite direction to when the drive is transmitted. Also, the forward output gear 73 attached to the reverse one-way clutch mechanism 90 rotates in the direction of arrow G1 as the drive force is transmitted from the forward one-way clutch mechanism 70. At this time, the second forward engagement portion 72b of the forward joint member 72 attached to the reverse one-way clutch mechanism 90 is pushed in the circumferential direction by the plane 173b1 perpendicular to the circumferential direction of the protrusion 173b of the forward output engagement portion 73b of the forward output gear 73, as shown by arrow H1 in the figure. Therefore, the forward output gear 73 attached to the reverse one-way clutch mechanism 90 does not move toward the reverse input gear, the engagement between the second engagement portion and the output engagement portion is not disengaged, and the drive transmission is not interrupted.

[0072] Therefore, in the basic configuration of the drive unit, each component of the forward rotation one-way clutch mechanism 70 (forward rotation input gear 71, forward rotation joint member 72, and forward rotation output gear 73) has a different shape from each component of the reverse rotation one-way clutch mechanism 90 (reverse rotation input gear 91, reverse rotation joint member 92, and reverse rotation output gear 93).

[0073] However, each component of the forward-rotating one-way clutch mechanism 70 and each component of the reverse-rotating one-way clutch mechanism 90 require a mold, which increases mold costs. In addition, the forward-rotating joint member 72 and the reverse-rotating joint member 92 only differ in the shape of their second engagement portions, which may lead to incorrect assembly. This necessitates measures such as changing the color of the forward-rotating joint member 72 and the reverse-rotating joint member 92.

[0074] Therefore, in this embodiment, the joint member is used in common with the forward rotation one-way clutch mechanism 70 and the reverse rotation one-way clutch mechanism 90 in the following manner.

[0075] Figure 11 is a perspective view showing the forward-rotating one-way clutch mechanism 70 and the reverse-rotating one-way clutch mechanism 90 of this embodiment. Figure 12 is a perspective view showing a common joint member 110 used in both the forward-rotating one-way clutch mechanism 70 and the reverse-rotating one-way clutch mechanism 90. In this embodiment, as shown in Figure 12, the protrusion 111b of the second engaging portion 110b of the common joint member 110 used in both the forward rotation one-way clutch mechanism 70 and the reverse rotation one-way clutch mechanism 90 has the following shape. That is, it has a first inclined surface 111b3 whose height gradually decreases in one direction, and a second inclined surface 111b4 whose height gradually decreases in the opposite direction from the top of the protrusion 111b, and its shape when viewed from the radial direction is an isosceles triangle.

[0076] Furthermore, as shown in Figure 11, the protrusions of the output engagement portions of the output gears of the forward-rotating one-way clutch mechanism 70 and the reverse-rotating one-way clutch mechanism 90 have a shape similar to the protrusion 111b of the common joint member 110. That is, they have first inclined surfaces 173b3, 193b3 whose height gradually decreases in one direction, and second inclined surfaces 173b4, 193b4 whose height gradually decreases in the opposite direction from the top of the protrusion, and their shape when viewed from the radial direction is an isosceles triangle.

[0077] Figure 13(a) is a diagram illustrating the operation of the forward-rotating one-way clutch mechanism 70 in this embodiment when the drive motor is reversed. When the drive motor 61 rotates in reverse, the forward input engagement portion 71c abuts the first engagement portion 110a of the common joint member 110 from the opposite direction (direction of arrow C2) to the direction of drive transmission, and the forward output gear 73 rotates in the direction of arrow F1 due to the drive transmission from the reverse output gear 93. At this time, the second inclined surface 111b4 of the protrusion 111b of the second engagement portion 110b of the common joint member 110 is pushed in the direction shown by arrow H3 in the figure by the first inclined surface 173b3 of the protrusion 173b of the forward output engagement portion 73b of the forward output gear 73. This pushing of the first inclined surface 173b3 in the direction of arrow H3 in the figure causes the common joint member 110 to move toward the forward input gear 71, as shown by arrow H4 in the figure, disengaging the engagement between the second engagement portion 110b and the forward output engagement portion 73b, thereby interrupting drive transmission.

[0078] Figure 13(b) illustrates the operation of the reverse one-way clutch mechanism 90 in this embodiment when the drive motor is rotating in the forward direction. When the drive motor 61 rotates forward, the reverse input engagement portion 91c abuts against the first engagement portion 110a of the common joint member 110 in the opposite direction to when the drive is transmitted, and the reverse output gear 93 rotates in the direction of arrow G1 as the drive force is transmitted from the forward output gear 73. At this time, the first inclined surface 111b3 of the protrusion 111b of the second engagement portion 110b of the common joint member 110 is pushed in the direction shown by arrow H5 in the figure by the second inclined surface 193b4 of the protrusion 193b of the reverse output engagement portion 93b of the reverse output gear 93. This pushing of the second inclined surface 193b4 in the direction of arrow H5 in the figure causes the common joint member 110 to move toward the reverse input gear side, as shown by arrow H6 in the figure, disengaging the engagement between the second engagement portion 110b and the reverse output engagement portion 93b, thereby interrupting the drive transmission.

[0079] Figure 14(a) is a diagram illustrating the operation of the forward-rotating one-way clutch mechanism 70 in this embodiment when the drive motor is rotating in the forward direction. As shown in Figure 14(a), when the drive motor is rotating forward, the common joint member 110 is pushed in the direction of arrow H7 in the figure by the second inclined surface 173b4 of the protrusion 173b of the forward rotation output engaging portion 73b due to the reaction force of the forward rotation output gear 73. However, when the drive motor is rotating forward, the common joint member 110 is restricted from moving toward the forward rotation input gear 71 by the flat portion 71b2 of the forward rotation pushing portion 71b. Therefore, even if the common joint member 110 is pushed toward the forward rotation input gear by the second inclined surface 173b4 of the protrusion 173b, the common joint member 110 does not move toward the forward rotation input gear. Thus, the engagement between the second engaging portion 110b and the forward rotation output engaging portion 73b is maintained, and drive transmission can be performed smoothly.

[0080] Figure 14(b) illustrates the operation of the reverse-rotating one-way clutch mechanism 90 in this embodiment when the drive motor is reversed. As shown in Figure 14(b), when the drive motor reverses direction, the common joint member 110 is pushed in the direction of arrow H8 in the figure by the first inclined surface 193b3 of the protrusion 193b of the reverse output engaging portion 93b due to the reaction force of the reverse output gear 93. However, when the drive motor reverses direction, the common joint member 110 is restricted from moving toward the reverse input gear 91 by the flat portion 91b2 of the reverse pushing portion 91b. Therefore, even if the common joint member 110 is pushed toward the reverse input gear by the first inclined surface 193b3 of the protrusion 193b, the common joint member 110 does not move toward the reverse input gear. Thus, the engagement between the second engaging portion 110b and the reverse output engaging portion 93b is maintained, and drive transmission can be performed smoothly.

[0081] Thus, in this embodiment, each protrusion of the second engaging portion of the joint member and each protrusion of the output engaging portion of the output gear have a first inclined surface whose height gradually decreases in one direction and a second inclined surface whose height gradually decreases in the opposite direction from the top of the protrusion, and the shape when viewed from the radial direction is an isosceles triangle. As a result, even if a common joint member is used for both the forward rotation one-way clutch mechanism 70 and the reverse rotation one-way clutch mechanism 90, each one-way clutch mechanism can perform drive transmission and drive interruption normally.

[0082] Furthermore, by using a common joint member 110 for both the forward-rotating one-way clutch mechanism 70 and the reverse-rotating one-way clutch mechanism 90, mold costs can be reduced, and the cost of the drive unit 60 can be lowered. In addition, by using a common joint member 110 for both the forward-rotating one-way clutch mechanism 70 and the reverse-rotating one-way clutch mechanism 90, incorrect assembly of the joint member between the two mechanisms is prevented.

[0083] Furthermore, the forward rotation output gear 73 and the reverse rotation output gear 93 can be made common. Alternatively, the output gears can be made common by using an output gear with an integrated fixing output gear 64 for both the reverse rotation output gear 93 and the forward rotation output gear 73. Alternatively, as shown in Figure 15, the fixing output gear 64 can be made a separate component, and the fixing output gear 64 can be attached to the common output gear 112 of the forward rotation one-way clutch mechanism 70. When the output gears are made common for the forward rotation one-way clutch mechanism 70 and the reverse rotation one-way clutch mechanism 90, the gear portion should have spur teeth. By making the output gears common for the forward rotation one-way clutch mechanism 70 and the reverse rotation one-way clutch mechanism 90 in this way, mold costs can be further reduced, and the cost of the drive unit 60 can be further reduced.

[0084] Furthermore, as shown in Figure 16, the joint members 72 and 92 may be provided with a shape similar to the push-in portions 71b and 91b on the input gear, which consist of an inclined surface 71b1 (91b1) and a flat surface 71b2 (91b2). Specifically, as shown in Figure 16, input engagement portions 71c and 91c are provided on the surfaces of the input gears 71 and 91 that face the joint members 72 and 92. The joint members 72 and 92 are provided with push-in portions 72c and 92c, which consist of an inclined surface 72c1 (92c1) and a flat surface 72c2 (92c2), and which are pushed toward the output gear side by the input engagement portions 71c and 91c during drive transmission. Even with this configuration, during power transmission, the tips of the input engagement portions 71c and 91c move up the inclined surface, gradually moving the joint member toward the output gear, allowing the second engagement portion of the joint member to engage with the output engagement portion of the output gear. Furthermore, when the input engagement portions 71c and 91c abut against the first engagement portions 72a and 92a of the joint member and power is being transmitted, the flat portions 92c2 and 92c2 of the pushed-in portions 72c and 92c come into contact with the tips of the input engagement portions 71c and 91c, restricting the joint member's movement toward the input gear. In the configuration shown in Figure 16, the input gear and output gear can be shared between the forward rotation one-way clutch mechanism 70 and the reverse rotation one-way clutch mechanism 90.

[0085] Furthermore, as described above, the protrusion 111b of the second engaging portion of the common joint member and the protrusions 173b and 193b of the output engaging portion of the output gear are made to be isosceles triangles when viewed from the radial direction, and the inclination angles of the first inclined surface and the second inclined surface are the same. However, as shown in Figure 17(a), the inclination angles of the first inclined surface and the second inclined surface of the protrusion may be different from each other.

[0086] By configuring each protrusion in this way, the circumferential force applied from the protrusion 111b of the common joint member 110 to the protrusion 173b of the forward rotation output gear when the drive is transmitted by the forward rotation one-way clutch mechanism 70 can be made to be different from the circumferential force applied from the protrusion 111b of the common joint member 110 to the protrusion 193b of the reverse rotation output gear 93 when the drive is transmitted by the reverse rotation one-way clutch mechanism 90.

[0087] Therefore, when the load torque when power is transmitted by the forward-rotating one-way clutch mechanism 70 and the load torque when power is transmitted by the reverse-rotating one-way clutch mechanism 90 are different, power can be transmitted smoothly by configuring the inclined surface of the common joint member 110 with a smaller inclination angle with respect to the axial direction to engage with the protrusion of the output gear when power is transmitted by the one-way clutch mechanism with the larger load torque.

[0088] Furthermore, as shown in Figure 17(b), the top of the convex portion may be a plane parallel to the circumferential direction, resulting in a trapezoidal shape when viewed from the radial direction. Making the top of the convex portion a plane has the advantage of ensuring the strength of the mold used to form the common joint member 110 and the output gears 73 and 93. However, if the top is a plane, during drive transmission, the top of the convex portion 111b of the common joint member 110 may hit the tops of the convex portions 173b and 193b of the output gears 73 and 93, preventing the convex portion 111b of the common joint member 110 from fitting between the convex portions 173b and 193b of the output gears 73 and 93. For this reason, it is advisable to add a radius to both ends of the circumferential plane of the top, or to make the plane of the top as short as possible.

[0089] On the other hand, as in this embodiment, by making the tops of the protrusions 111b, 173b, and 193b acute angles, when the input gear's push-in portions 71b and 91b are pressed, the protrusion 111b of the second engaging portion of the common joint member 110 can be properly engaged between the protrusions 173b and 193b of the output engaging portions of the output gears 73 and 93. This has the advantage that the second engaging portion 110b can be properly engaged with the output engaging portions 73b and 93b when the drive is transmitted.

[0090] Furthermore, the second rotating body, which receives driving force from both the forward-rotating one-way clutch mechanism 70 and the reverse-rotating one-way clutch mechanism 90 and rotates in the forward direction both when the drive motor 61 is rotating in the forward and reverse directions, is not limited to the fuser roller 44a. The second rotating body can be anything that rotates in a constant direction at all times during printing. For example, it could be the photoreceptor 1, the charging roller 4, the rotating members of the developing device 8 such as the developing roller 8a and screw, the agitator 9b in the toner cartridge, the transfer roller 10, the paper feed roller and registration roller that transport the recording sheet S, etc., or multiple of these could be driven to rotate.

[0091] Although preferred embodiments of the present invention have been described above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the spirit of the present invention as described in the claims, unless otherwise specifically limited in the above description.

[0092] The above is just one example; each of the following embodiments produces its own unique effects. (Aspect 1) The joint member (110) comprises an input member (forward input gear 71, reverse input gear 91) having input engagement parts (71c, 91c) to which driving force is input from the drive source of the drive motor 61; an output member (forward output gear 73, reverse output gear 93) arranged coaxially with the input member and having output engagement parts (73b, 93b) to output driving force; and a joint member (110) arranged to be axially movable between the input member and the output member and having a first engagement part (110a) that engages with the input engagement part and a second engagement part (110b) that engages with the output engagement part. When the input member rotates in the drive transmission rotation direction, which is the rotation direction during drive transmission, the input engagement part and the first engagement part engage, and the second engagement part and the output engagement part engage to perform drive transmission. When the input member rotates in the drive interruption rotation direction, which is the opposite direction to the drive transmission rotation direction, the engagement between the second engagement part and the output engagement part disengages. A one-way clutch mechanism (70, 90) for interrupting drive transmission, wherein the second engagement portion is provided on an axially perpendicular opposing surface of the joint member (110) facing the output member, and has a plurality of axially projecting protrusions (111b) arranged in a circumferential direction, and the output engagement portion is provided on an axially perpendicular opposing surface of the output member facing the joint member, and has a plurality of axially projecting protrusions (173b, 193b) arranged in a circumferential direction, and each protrusion (111b) of the second engagement portion and each protrusion (173b, 193b) of the output engagement portion has a first inclined surface (111b3, 173b3, 193b3) from the top of the protrusion that gradually decreases in height toward the rotation direction during drive transmission, and a second inclined surface (111b4, 173b4, 193b4) from the top of the protrusion that gradually decreases in height toward the rotation direction when drive is interrupted. In the one-way clutch mechanism described in Patent Document 1, the protrusions of the second engaging portion and the output engaging portion are composed of a plane perpendicular to the circumferential direction (parallel to the axial direction) and an inclined surface. When the input member rotates in the rotational direction during power transmission, the plane of the second engaging portion and the plane of the output engaging portion engage. Therefore, when the input member rotates in the rotational direction during power transmission, the reaction force from the output engaging portion to the second engaging portion is in the circumferential direction. The shape of the protrusion between the second engagement portion and the output engagement portion of the output member in the one-way clutch mechanism described in Patent Document 1 (hereinafter referred to as the forward-rotating one-way clutch mechanism) and the one-way clutch mechanism in which the rotation direction of the input member is reversed during drive transmission (hereinafter referred to as the reverse-rotating one-way clutch mechanism) cannot be adopted. This is because the rotation direction during drive transmission in the forward-rotating one-way clutch mechanism of Patent Document 1 is the rotation direction when the drive is cut off in the reverse-rotating one-way clutch mechanism. Therefore, if the shape of the protrusion described in Patent Document 1 is adopted as the shape of the protrusion between the second engagement portion and the output engagement portion of the output member, when the joint member rotates with the input member in the rotation direction when the drive is cut off, the reaction force from the output engagement portion to the second engagement portion will be in the circumferential direction. As a result, the second engagement portion will not move toward the input member, the engagement between the second engagement portion and the output engagement portion of the output member will not be released, and the drive transmission will not be cut off. Therefore, when two one-way clutch mechanisms have different rotation directions during drive transmission, it is necessary to provide joint members and output members with different shapes for the protrusions of the second engagement portion and the output engagement portion. In contrast, in embodiment 1, the protrusions of the second engagement portion and the output engagement portion are configured to have a first inclined surface whose height gradually decreases from the top of the protrusion toward the rotation direction during drive transmission, and a second inclined surface whose height gradually decreases from the top of the protrusion toward the rotation direction during drive disconnection. As a result, when the joint member (110) rotates in one direction, the reaction force from the first inclined surfaces (173b3, 193b3) of the output engagement portion (73b, 93b) pushes the second inclined surface 111b4 of the second engagement portion 110b toward the input member, and when the joint member (110) rotates in the opposite direction to the above one direction, the reaction force from the second inclined surfaces (173b4, 193b4) of the output engagement portion (73b, 93b) pushes the first inclined surface 111b3 of the second engagement portion 110b toward the input member. In this way, during rotation of the joint member in one direction or in the opposite direction, the joint member is pushed toward the input member by the reaction force of the output engagement part, allowing the engagement between the second engagement part and the output engagement part to be released, and thus enabling the interruption of drive transmission. As a result, even when using the same joint member and output member, the drive can be effectively interrupted in both one-way clutch mechanisms, even if the rotation directions during drive transmission are different for each other. Furthermore, during drive transmission, as described above, the joint member is pushed towards the output member by the input member. Therefore, even if the joint member is pushed towards the input member by the reaction force of the output engagement part, the joint member will not move towards the input member, and the drive transmission will not be interrupted. Therefore, it becomes possible to use common joint members and output members between two one-way clutch mechanisms where the rotation direction of the input members during drive transmission is different, thereby reducing the cost of the one-way clutch mechanism.

[0093] (Aspect 2) In embodiment 1, the input member, such as an input gear, has a push-in portion (71b, 91b) that pushes the joint member into the output member, such as an output gear, when it rotates in the rotational direction during drive transmission. According to this, as explained in the embodiment (see Figure 14), during drive transmission, the joint member (110) is pushed towards the output member by the push-in portion (71b, 91b), and even if the joint member is pushed towards the input member by the reaction force of the output engagement portion, the joint member does not move towards the input member, and the drive transmission is not interrupted. As a result, the driving force of the drive source such as the drive motor 61 can be output smoothly.

[0094] (Aspect 3) In embodiment 1 or 2, the tops of each protrusion (111b) of the second engaging portion (110b) and each protrusion (173b, 193b) of the output engaging portions (73b, 93b) are acute angles. According to this, as described in the embodiment, compared to the case where the tops of each protrusion are planes perpendicular to the axial direction, the protrusion (111b) of the second engaging portion of the joint member (110) can be properly inserted between the protrusions (173b, 193b) of the output engaging portion of the output member such as the output gear during drive transmission, and the second engaging portion (110b) can be properly engaged with the output engaging portions (73b, 93b) during drive transmission.

[0095] (Aspect 4) In embodiment 1 or 2, the tops of each protrusion (111b) of the second engaging portion (110b) and each protrusion (173b, 193b) of the output engaging portions (73b, 93b) are planes perpendicular to the axial direction. According to this, as explained using Figure 17(b), the strength of the mold used to form the joint member and output member can be ensured compared to those where the tops of each protrusion are sharp angles.

[0096] (Aspect 5) A drive device 60 comprising a drive source such as a drive motor 61 capable of forward and reverse rotation, and a drive transmission mechanism having a one-way clutch mechanism (70, 90) for transmitting the driving force of the drive source, wherein one of the one-way clutch mechanisms of embodiment 1 to 4 is used as the one-way clutch mechanism. According to this, the cost of the drive unit 60 can be reduced.

[0097] (Aspect 6) In embodiment 5, the drive transmission mechanism has a first drive transmission path (in this embodiment, composed of a motor input gear 62, a forward-rotating one-way clutch mechanism 70, and a fixing output gear 64) that outputs the driving force of a drive source such as a drive motor 61 when the drive source is rotating in the forward direction, and a second drive transmission path (in this embodiment, composed of a motor input gear 62, a reverse-rotating one-way clutch mechanism 90, a forward-rotating one-way clutch forward output gear 73, and a fixing output gear 64) that outputs the driving force of a drive source when the drive source is rotating in the reverse direction. One-way clutch mechanisms are arranged in the first and second drive transmission paths, and the joint members of the one-way clutch mechanisms such as the forward-rotating one-way clutch mechanism 70 arranged in the first drive transmission path and the joint members of the one-way clutch mechanisms such as the reverse-rotating one-way clutch mechanism 90 arranged in the second drive transmission path are common. According to this, as described in the embodiment, mold costs can be reduced and the cost of the drive unit can be lowered.

[0098] (Aspect 7) In embodiment 6, the output members such as the forward rotation output gear of a one-way clutch mechanism such as a forward rotation one-way clutch mechanism 70 arranged in the first drive transmission path and the output members such as the reverse rotation output gear 93 of a one-way clutch mechanism such as a reverse rotation one-way clutch mechanism 90 arranged in the second drive transmission path are common. According to this, as described in the embodiment, further reductions in mold costs can be achieved, and further reductions in the cost of the drive unit can be achieved.

[0099] (Pattern 8) In embodiment 6 or 7, the inclination angles of the first inclined surfaces (111b3, 173b3, 193b3) of each protrusion (111b) of the second engaging portion (110b) and each protrusion (173b, 193b) of the output engaging portion (73b, 93b) are different from the inclination angles of the second inclined surfaces (111b4, 173b4, 193b4). According to this, as explained using Figure 17(a), when a driving force is output from a one-way clutch mechanism such as the forward-rotating one-way clutch mechanism 70 located in the first drive transmission path, the circumferential force applied to the convex portion of the engaging part of the output member such as the forward-rotating output gear 73 can be made to be different from the circumferential force applied to the convex portion of the engaging part of the output member such as the reverse-rotating output gear 93 when a driving force is output from a one-way clutch mechanism such as the reverse-rotating one-way clutch mechanism 90 located in the second drive transmission path. As a result, when the load torque when a driving force is output from the one-way clutch mechanism located in the first drive transmission path and the load torque when a driving force is output from the one-way clutch mechanism located in the second drive transmission path are different from each other, by adopting the configuration of embodiment 8, good drive transmission can be achieved in both the one-way clutch mechanism located in the first drive transmission path and the one-way clutch mechanism located in the second drive transmission path.

[0100] (Aspect 9) In any of embodiments 6 to 8, the drive transmission mechanism has a forward / reverse drive transmission path (in this embodiment, composed of a motor input gear 62, a forward input gear 71, and a paper discharge reversal output gear 63) that transmits driving force to a first rotating body such as a paper discharge reversal roller, causing the first rotating body to rotate in the forward direction when a drive source such as a drive motor 61 is rotating in the forward direction, and driving the first rotating body in the reverse direction when the drive source is rotating in the reverse direction; a first forward drive transmission path that transmits driving force to a second rotating body such as a fixing roller 44a when the drive source is rotating in the forward direction, causing the second rotating body to rotate in the forward direction; and a second forward drive transmission path that transmits driving force to a second rotating body when the drive source is rotating in the reverse direction, causing the second rotating body to rotate in the forward direction. The first forward drive transmission path is the first drive transmission path, and the second forward drive transmission path is the second drive transmission path. According to this, the drive transmission mechanism can be configured inexpensively, and the first rotating body, such as the paper discharge reversal roller which is driven in both forward and reverse directions, and the second rotating body, such as the fixing roller 44a which is always driven in the forward direction, can be rotated by a single drive source. As a result, the number of parts can be reduced compared to when the first rotating body which is driven in both forward and reverse directions and the second rotating body which is always driven in the forward direction are driven by separate drive sources, and the cost of the drive device can be further reduced.

[0101] (Aspect 10) In embodiment 9, the first rotating body is a paper discharge / reversal roller that discharges the sheet to the paper discharge tray or transports the sheet to a reversal path that reverses the sheet, and the second rotating body is a fixing roller 44a of a fixing device 44 that fixes the toner image formed on the sheet. According to this, as described in the embodiment, even when the paper discharge reversal roller is driven in reverse to transport the sheet to the reversal path, the fuser roller 44a can be driven in the forward direction. This allows the sheet to be fed through the fuser device 44 and the toner image to be fixed even while the sheet is being transported to the reversal path by the paper discharge reversal roller, thereby suppressing a decrease in productivity.

[0102] (Aspect 11) An image forming apparatus equipped with a drive device, wherein any of the drive devices described in embodiments 6 to 10 is used as the drive device. This would allow for a reduction in the cost of image forming equipment. [Explanation of Symbols]

[0103] 44: Fixing device 44a: Fixing roller 46: Paper output reversal roller pair 60: Drive unit 61: Drive motor 61a: Motor shaft 62: Motor input gear 63: Output gear for paper output reversal 64: Fixing output gear 70: Forward rotation one-way clutch mechanism 71: Forward rotation input gear 71a: Forward rotation input gear section 71b: Forward rotation push-in part 71b1: Inclined surface 71b2: Flat part 71c: Forward rotation input engagement part 72: Forward rotation joint member 72a: First forward rotation engagement part 72b: Second forward rotation engagement part 73: Forward rotation output gear 73a: Forward rotation output gear section 73b: Forward rotation output engagement part 74:First support shaft 90: Reversal one-way clutch mechanism 91: Reverse Input Gear 91a: Reverse input gear section 91b: Reverse push-in section 91b1: Inclined surface 91b2 :Plane part 91c: Reverse input engagement part 92: Reversal joint component 92a: First reversing engagement part 92b: Second reversing engagement part 93: Reverse Output Gear 93a: Reverse output gear section 93b: Reverse output engagement part 94:Second support shaft 110: Common joint member 110a: First engaging part 110b: Second engaging part 111b: Protrusion of the second engaging portion 111b3: First slope 111b4:Second slope 112: Common output gear 172b: Protrusion of the second forward rotation engagement part 173b: Protrusion of the forward rotation output engagement part 173b3: First inclined surface of the protrusion of the forward rotation output engagement part 173b4: Second inclined surface of the protrusion of the forward rotation output engagement part 192b: Protrusion of the second reversal engagement part 193b: Protrusion of the reverse output engagement part 193b3: First inclined surface of the protrusion of the reverse output engagement part 193b4: Second inclined surface of the protrusion of the reverse output engagement part S: Record Sheet [Prior art documents] [Patent Documents]

[0104] [Patent Document 1] Patent No. 7271317

Claims

1. An input member having an input engagement portion, to which driving force is input from a drive source, An output member is arranged coaxially with the input member, has an output engagement portion, and outputs the driving force, The joint member is arranged to be axially movable between the input member and the output member, and has a first engaging portion that engages with the input engaging portion and a second engaging portion that engages with the output engaging portion. A one-way clutch mechanism wherein when the input member rotates in the drive transmission rotation direction, which is the rotation direction when the output member outputs the driving force, the input engagement portion and the first engagement portion engage, and the second engagement portion and the output engagement portion engage to transmit drive, and when the input member rotates in the drive interruption rotation direction, which is the opposite direction to the drive transmission rotation direction, the engagement between the second engagement portion and the output engagement portion disengages and the drive transmission is interrupted. The second engaging portion is provided on the opposing surface of the joint member perpendicular to the axial direction, facing the output member, and has a plurality of protrusions that project in the axial direction arranged in a circular direction. The output engagement portion is provided on the opposing surface of the output member perpendicular to the axial direction, facing the joint member, and has a plurality of protrusions that project in the axial direction arranged in a circular direction. A one-way clutch mechanism characterized in that each protrusion of the second engaging portion and each protrusion of the output engaging portion have a first inclined surface from the top of the protrusion, which gradually decreases in height toward the rotational direction during drive transmission, and a second inclined surface from the top of the protrusion, which gradually decreases in height toward the rotational direction during drive disconnection.

2. A one-way clutch mechanism according to claim 1, The one-way clutch mechanism is characterized in that the input member has a push-in portion that pushes the joint member toward the output member when the input member rotates in the rotational direction during drive transmission.

3. A one-way clutch mechanism according to claim 1, A one-way clutch mechanism characterized in that the tops of each protrusion of the second engaging portion and each protrusion of the output engaging portion are acute angles.

4. A one-way clutch mechanism according to claim 1, A one-way clutch mechanism characterized in that the tops of each protrusion of the second engaging portion and each protrusion of the output engaging portion are planes perpendicular to the axial direction.

5. A drive source capable of forward and reverse rotation, A drive device comprising a drive transmission mechanism having a one-way clutch mechanism and transmitting the driving force of the drive source, A drive device characterized in that the one-way clutch mechanism is the one-way clutch mechanism described in claim 1.

6. In the drive device according to claim 5, The drive transmission mechanism has a first drive transmission path that outputs the driving force of the drive source when the drive source is rotating in the forward direction, and a second drive transmission path that outputs the driving force of the drive source when the drive source is rotating in the reverse direction. The one-way clutch mechanism is arranged in the first drive transmission path and the second drive transmission path. A drive device characterized in that the joint member of the one-way clutch mechanism arranged in the first drive transmission path and the joint member of the one-way clutch mechanism arranged in the second drive transmission path are common.

7. In the drive device according to claim 6, A drive device characterized in that the output member of the one-way clutch mechanism arranged in the first drive transmission path and the output member of the one-way clutch mechanism arranged in the second drive transmission path are common.

8. The drive device according to claim 6, A drive device characterized in that the inclination angle of the first inclined surface of each protrusion of the second engaging portion and each protrusion of the output engaging portion is different from the inclination angle of the second inclined surface.

9. In the drive device according to claim 6, The aforementioned drive transmission mechanism is A forward / reverse drive transmission path transmits the driving force to the first rotating body, causing the first rotating body to rotate in the forward direction when the drive source rotates in the forward direction, and to rotate the first rotating body in the reverse direction when the drive source rotates in the reverse direction, The first forward rotation drive transmission path transmits driving force to the second rotating body when the drive source is rotating in the forward direction, causing the second rotating body to rotate in the forward direction, The drive source has a second forward rotation drive transmission path that transmits driving force to the second rotating body when it is in reverse rotation, causing the second rotating body to rotate in the forward direction. A drive device characterized in that the first forward rotation drive transmission path is the first drive transmission path, and the second forward rotation drive transmission path is the second drive transmission path.

10. In the drive device according to claim 9, The first rotating body is a paper output reversal roller that discharges the sheet to the paper output tray or transports the sheet to a reversal path for inverting it. The drive device is characterized in that the second rotating body is a fixing roller of a fixing device that fixes the toner image formed on the sheet.

11. An image forming apparatus equipped with a drive device, An image forming apparatus characterized in that the drive device described in claim 6 is used as the drive device.

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