Drive transmission device and image forming apparatus

Abstract

To reduce the number of electric clutches to solve a problem of temperature increase due to heat generation, and ensure the degree of freedom of drive operation of driven bodies resulting from the reduction in the number of electric clutches.SOLUTION: A drive transmission device transmits a driving force from the same driving source 63 to at least three driven bodies 1, 43, 8a. An electric clutch 85 is arranged on a second drive transmission path to the second driven body 8a. A third drive transmission path to the third driven body 8a is provided with a path B1 for normal rotation including a first one-way clutch 88A transmitting the driving force to the third driven body during the normal rotation of the driving source, and a path B2 for reverse rotation including a second one-way clutch 88B transmitting the driving force to the third driven body during the reverse rotation of the driving source. At least one of the paths B1, B2 transmits the driving force to the third driven body through the electric clutch on the second drive transmission path.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a drive transmission device and an image forming apparatus. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there has been known a drive transmission device that transmits a drive force from a single drive source to a plurality of driven elements.

[0003] Patent Document 1 discloses a drive transmission device that is installed in an image forming apparatus with four photoconductors arranged along an intermediate transfer belt and transmits drive force from a single drive source to the photoconductors (first driven element) and the developing sleeve (second driven element). This drive transmission device has an electromagnetic clutch (electrical clutch) disposed in a second drive transmission path that transmits drive force from the drive source to the developing sleeve. When a print request is received, this drive transmission device turns off the electromagnetic clutch for the developing sleeve of a color not used in the image formation operation to interrupt drive transmission, thereby stopping the rotation of the developing sleeve even while the photoconductor of that color is rotating. Furthermore, this drive transmission device rotates the developing sleeve of a color not used in the image formation operation in the reverse direction about half a turn along with the photoconductor of that color before rotating the photoconductor of the color to be used in the forward direction (rotation during the image formation operation). This positions the surface of the developing sleeve not carrying developer in the development zone, avoiding problems that may occur when developer is present in the development zone. Summary of the Invention [Problem to be solved by the invention]

[0004] However, in a configuration in which a driving force from the same driving source is transmitted to at least three driven bodies, in order to make the driving times of these driven bodies different from one another, it is necessary to place an electric clutch such as an electromagnetic clutch on each of the drive transmission paths for at least two of the driven bodies. In this case, heat generated by two or more electric clutches can cause a problem of temperature rise. [Means for solving the problem]

[0005] In order to solve the above-mentioned problems, the present invention provides a drive transmission device that transmits a drive force from a same drive source to at least three driven bodies, wherein: The latent image carrier in the electrophotographic image forming apparatus One driven body, a registration roller that conveys, at a predetermined conveying timing, a recording material onto which an image obtained by developing the latent image on the latent image carrier by a developing device is transferred; Second driven body 、 and , the developer carrier of the developing device The drive power transmission system includes a first drive transmission path, a second drive transmission path, and a third drive transmission path that transmit the driving force to each of the third driven bodies, and an electric clutch is disposed in the second drive transmission path. The third drive transmission path includes a forward rotation path that transmits the driving force to the third driven body when the drive source rotates in the forward direction, and a reverse rotation path that transmits the driving force to the third driven body when the drive source rotates in the reverse direction. The forward rotation path includes a first one-way clutch that transmits the driving force to the third driven body when the drive source rotates in the forward direction, and does not transmit the driving force to the third driven body when the drive source rotates in the reverse direction. The reverse rotation path includes a second one-way clutch that does not transmit the driving force to the third driven body when the drive source rotates in the forward direction, and transmits the driving force to the third driven body when the drive source rotates in the reverse direction. At least one of the forward rotation path and the reverse rotation path transmits the driving force to the third driven body via the electric clutch on the second drive transmission path. [Effects of the Invention]

[0006] According to the present invention, it is possible to reduce the number of electric clutches and suppress the problem of temperature rise due to heat generation, while ensuring the degree of freedom in the driving operation of the driven body. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram showing a printer according to an embodiment. [Figure 2] FIG. 2 is an enlarged schematic view showing a photosensitive member and its surrounding structure in the printer. [Figure 3] FIG. 2 is a schematic diagram of the printer with the access cover open. [Figure 4] 1 is an external perspective view of a drive unit including a drive transmission device according to an embodiment; [Figure 5] 5 is a perspective view showing the drive device shown in FIG. 4 with a resin housing removed. FIG. [Figure 6] FIG. 10 is a perspective view of the drive unit with the mounting plate removed, viewed from the mounting plate side. [Figure 7] FIG. 4 is an explanatory diagram for explaining a transmission path of a driving force of the drive motor when the drive motor rotates forward in the embodiment. [Figure 8] 5 is an explanatory diagram for explaining a transmission path of the driving force of the drive motor when the drive motor rotates in the reverse direction in the embodiment. FIG. [Figure 9] 5 is a flowchart showing an example of control during reverse rotation of a drive motor in the embodiment. [Figure 10] FIG. 10 is an explanatory diagram illustrating a transmission path of the driving force of the drive motor when the drive motor rotates forward in a modified example. [Figure 11] FIG. 10 is an explanatory diagram illustrating a transmission path of the driving force of the drive motor when the drive motor rotates in the reverse direction in a modified example. [Figure 12] FIG. 10 is an external perspective view showing a joint portion according to a modified example. [Figure 13] FIG. 4 is an explanatory diagram showing backlash of the joint portion. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment will be described in which the drive transmission device according to the present invention is applied to an electrophotographic printer (hereinafter simply referred to as "printer") as an image forming apparatus that forms images by electrophotography.

[0009] The present invention will be described with reference to an example of a drive transmission device in an electrophotographic image forming apparatus that transmits drive force from a single drive source to four driven elements: a photosensitive element, a developing roller (developing sleeve), a registration roller (pair of registration rollers), and a paper feed roller. However, the present invention is not limited to this. For example, the number of driven elements to which drive force from a single drive source is transmitted by the drive transmission device may be three, five, or more. The types of driven elements may also be different from the above (e.g., recording material transport members such as transport rollers and paper discharge rollers, or various rotating elements such as charging rollers, cleaning rollers, transfer rollers, screws, and agitators). The device in which the drive transmission device of the present invention is installed may be a non-electrophotographic image forming apparatus (e.g., an inkjet or stencil printing image forming apparatus), or may be a device other than an image forming apparatus.

[0010] First, the basic configuration of the printer according to this embodiment will be described. FIG. 1 is a schematic diagram showing a printer according to this embodiment. In the figure, the printer includes a photosensitive member 1 as a latent image carrier, and a paper feed cassette 100 that is detachably attached to a main body housing 50. The paper feed cassette 100 contains a plurality of recording sheets S as recording materials in a sheet stack.

[0011] The recording sheets S in the paper feed cassette 100 are sent out from the cassette by the rotational drive of the main body paper feed roller 41, and only the topmost sheet is separated and sent out at the separation nip between the main body paper feed roller 41 and the separation pad 48, and reaches the main body paper feed path R1, which is the first conveyance path. Thereafter, the recording sheet S is sandwiched (held) in the conveyance nip of the relay roller pair 42, which is the upper conveyance roller pair, and is conveyed in the main body paper feed path R1 from the upstream side to the downstream side in the conveyance direction.

[0012] The downstream end of the main body paper feed path R1 communicates with a common transport path R3, and a pair of registration rollers 43 is disposed on the common transport path R3. A registration sensor 49 that detects the recording sheet S is disposed on the common transport path R3 upstream of the pair of registration rollers 43 in the transport direction. The transport of the recording sheet S is temporarily stopped when its leading edge abuts against the nip of the stopped pair of registration rollers 43. When the recording sheet S abuts, any skew of the recording sheet S is corrected. The registration sensor 49 is also used for initial operations and for checking remaining sheets when the device is restarted due to an abnormal stop.

[0013] The pair of registration rollers 43 starts rotating at a timing when the recording sheet S can be superimposed on the toner image on the surface of the photosensitive member 1 at the transfer nip, and sends the recording sheet S toward the transfer nip. At this time, the pair of relay rollers 42 also starts rotating at the same time, and resumes the transportation of the recording sheet S that had been temporarily stopped.

[0014] The main body 50 of the printer is provided with a manual paper feed unit 30 including a manual tray 31, a manual paper feed roller 32, a separation pad 33, a manual feed bottom plate 34, and a manual feed bottom plate cam 35. A recording sheet S manually fed into the manual tray 31 of the manual paper feed unit 30 is sent from the manual tray 31 to a manual paper feed path R2, which is a second transport path, by the rotational drive of the manual paper feed roller 32. The downstream end of the manual paper feed path R2, together with the downstream end of the main body paper feed path R1, merges with the common transport path R3. The recording sheet S sent out by the manual paper feed roller 32 passes through a separation nip in the manual paper feed path R2, where the manual paper feed roller 32 abuts against the separation pad 33, and is then sent into the common transport path R3 and transported to the registration roller pair 43. Thereafter, like the recording sheet S fed from the paper feed cassette 100, this recording sheet S passes through a pair of registration rollers 43 and is then fed to the transfer nip.

[0015] FIG. 2 is an enlarged schematic diagram showing the photosensitive member 1 and its surrounding structure in this printer. Around the drum-shaped photoreceptor 1, which is driven to rotate clockwise in the figure, are arranged a cleaning blade 2, a collection 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 portion, rotates while in contact with the photoreceptor 1, forming a charging nip. A voltage is applied to this charging roller 4 from a charging power source. As a result, the surface of the photoreceptor 1 is uniformly charged by a charging bias generated between the surface of the photoreceptor 1 and the surface of the charging roller 4 in the charging nip.

[0016] The latent image writing device 7 is equipped with an LED array and performs optical writing using LED light on the uniformly charged surface of the photoreceptor 1. The potential of the area of ​​the uniformly charged surface of the photoreceptor 1 that is irradiated with the writing light decays, and an electrostatic latent image is formed on the surface of the photoreceptor 1.

[0017] As the photoreceptor 1 rotates, the electrostatic latent image passes through a development area facing the developing device 8. The developing device 8 has a circulating transport section and a developing section, and the circulating transport section contains a developer containing toner and magnetic carriers. The circulating transport section has a first screw 8b that transports the developer to be supplied 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. It also has an inclined screw 8d that transfers 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 parallel positions. In contrast, the inclined screw 8d is arranged in an inclined position relative to them.

[0018] As the first screw 8b rotates, it transports the developer from the rear to the front in a direction perpendicular to the paper surface of the figure. During this process, the first screw 8b supplies some of the developer to the developing roller 8a disposed opposite it. The developer transported by the first screw 8b to the vicinity of the front end in the direction perpendicular to the paper surface of the figure is dropped onto the second screw 8c.

[0019] The second screw 8c receives used developer from the developing roller 8a and transports the received developer from the rear side to the front side in a direction perpendicular to the paper surface as it rotates. The developer transported by the second screw 8c to the vicinity of the front end in the direction perpendicular to the paper surface is then transferred to the inclined screw 8d. Then, as the inclined screw 8d rotates, the developer is transported from the front side to the rear side in the direction perpendicular to the paper surface, and is then transferred to the first screw 8b near the rear end in the same direction.

[0020] The developing roller 8a, which serves as a developer carrier, includes a rotatable developing sleeve made of a cylindrical non-magnetic material and a magnetic roller fixed within the sleeve so as not to rotate along with the developing sleeve. A portion of the developer being transported by the first screw 8b is drawn up onto 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 faces the doctor blade. The developer is then transported in the development region facing the photoreceptor 1, rubbing against the surface of the photoreceptor 1.

[0021] A developing bias of the same polarity as the uniform charging potential (background potential) of the toner and the photosensitive member 1 is applied to the developing sleeve. The absolute value of this developing bias is greater than the absolute value of the latent image potential and smaller than the absolute value of the background potential. Therefore, in the development area, a developing potential acts between the electrostatic latent image on the photosensitive member 1 and the developing sleeve, which electrostatically moves toner from the developing sleeve to the photosensitive member 1. Meanwhile, a background potential acts between the background of the photosensitive member 1 and the developing sleeve, which electrostatically moves toner from the photosensitive member 1 to the developing sleeve. As a result, in the development area, toner selectively adheres to the electrostatic latent image on the photosensitive member 1, developing the electrostatic latent image.

[0022] The developer that has passed through the development area enters the opposing area between the development sleeve and second screw 8c as the development sleeve rotates. In this opposing area, a repulsive magnetic field is formed by two magnetic poles of the same polarity among the multiple magnetic poles provided on the magnet roller. The developer that has entered the opposing area is separated from the surface of the development sleeve by the action of the repulsive magnetic field and collected by second screw 8c.

[0023] The developer transported by the inclined screw 8d contains developer recovered from the developing roller 8a, and the developer has a reduced toner concentration because it contributes to development in the development area. The developing device 8 is equipped with a toner concentration sensor that detects the toner concentration of the developer transported by the inclined screw 8d. Based on the detection result from the toner concentration sensor, the control unit 80, which is made up of semiconductor circuits such as a CPU, outputs a replenishment operation signal to replenish toner to the developer transported by the inclined screw 8d, as necessary.

[0024] A toner cartridge 9 is disposed above the developing device 8. The toner cartridge 9 agitates the toner contained therein with an agitator 9b fixed to a rotary shaft member 9a. The toner supply member 9c is rotationally driven in response to a supply operation signal output from the control unit 80, and supplies the inclined screw 8d of the developing device 8 with toner in an amount corresponding to the rotational drive amount.

[0025] As the photosensitive member 1 rotates, the toner image (image) formed on the photosensitive member 1 by development enters the transfer nip where the photosensitive member 1 and transfer roller 10 come into contact. A voltage of the opposite polarity to the latent image potential of the photosensitive member 1 is applied to the transfer roller 10, which forms a transfer bias in the transfer nip.

[0026] As described above, the pair of registration rollers 43 sends the recording sheet S toward the transfer nip at a timing that allows the recording sheet S to be superimposed on the toner image on the photosensitive member 1 within the transfer nip. The toner image on the photosensitive member 1 is transferred onto the recording sheet that has been brought into close contact with the toner image at the transfer nip by the action of the transfer bias and nip pressure.

[0027] After passing through the transfer nip, residual toner that has not been transferred to the recording sheet S adheres to the surface of the photoreceptor 1. The residual toner is scraped off from the surface of the photoreceptor 1 by a cleaning blade 2 that is in contact with the photoreceptor 1, and then transported by a collection screw 3 and sent to a waste toner bottle.

[0028] The surface of the photoreceptor 1 cleaned by the cleaning blade 2 is neutralized by a neutralization means and then uniformly charged again by the charging roller 4. Foreign matter such as toner additives and toner that was not 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 in contact with the charging roller 4, and then scraped off from the surface of the charging cleaning roller 5 by the scraper 6 in contact with the charging cleaning roller 5. The scraped off foreign matter falls onto the collection screw 3 described above.

[0029] In FIG. 1, the recording sheet S that has passed through the transfer nip where the photosensitive element 1 and the transfer roller 10 come into contact is sent to the fixing device 44. The fixing device 44 forms a fixing nip by the contact of a fixing roller 44a containing a heat source such as a halogen lamp and a pressure roller 44b that is pressed against the fixing roller 44a. A toner image is fixed to the surface of the recording sheet S that has been sandwiched in the fixing nip by the action of heat and pressure. After passing through the fixing device 44, the recording sheet S then passes through a paper discharge path R4 and is sandwiched in the paper discharge nip of a pair of paper discharge rollers 46.

[0030] This printer can be switched 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 images are formed on both sides of the recording sheet S. In the single-sided mode, or in the double-sided mode in which images have already been formed on both sides of the recording sheet, the pair of discharge rollers 46 continues to rotate forward, thereby discharging the recording sheet S in the discharge path R4 outside the machine. The discharged recording sheet S is stacked in a stack section provided on the top surface of the main body housing 50.

[0031] On the other hand, in the duplex mode, when an image is formed on only one side of the recording sheet S, the pair of discharge rollers 46 is driven in reverse when the trailing edge of the recording sheet S enters the discharge nip of the pair of discharge rollers 46. At this time, a switching claw 47 disposed near the downstream end of the discharge path R4 is activated, blocking the discharge path R4 and opening the entrance to the reverse re-feed path R5. The recording sheet S begins to return due to the reverse drive of the pair of discharge rollers 46 and is sent into the reverse re-feed path R5. The downstream end of the reverse re-feed path R5 meets the upstream side of the pair of registration rollers 43 of the common transport path R3. After being transported through the reverse re-feed path R5, the recording sheet S is re-fed to the pair of registration rollers 43 of the common transport path R3. Thereafter, a toner image is transferred to the other side at the transfer nip, and the recording sheet is discharged outside the apparatus via the fixing device 44, the discharge path R4, and the pair of discharge rollers 46.

[0032] The fixing device 44 of this embodiment includes a cleaning roller 44d that removes toner, paper dust, and other adhering matter from the surface of the pressure roller 44b. The cleaning roller 44d is moved toward and away from the pressure roller 44b by a contact / separation mechanism.

[0033] The fixing device 44 also includes components that form the section of the paper discharge path R4 from the fixing nip to the switching claw 47. Specifically, the fixing device 44 includes a paper discharge guide member 59, a paper discharge reversing guide member 58, and a relay conveyance roller pair 51. The paper discharge guide member 59 faces the contact surface of the recording sheet S that has passed through the fixing nip with the fixing roller 44a, and has a guide portion 59a that guides the recording sheet S to the switching claw 47. The paper discharge reversing guide member 58 includes a paper discharge guide portion 58a and a reversing guide portion 58b. The paper discharge guide portion 58a faces the contact surface of the recording sheet S that has passed through the fixing nip with the pressure roller 44b, and guides the recording sheet S to the switching claw 47. The reversing guide portion 58b faces the image forming surface of the recording sheet on the reversing return path R5 that has passed through the switching claw 47, and guides it. The discharge sheet reversing guide member 58 also has attached thereto the driven roller 52b of the pair of reversing and conveying rollers 52 that convey the recording sheet in the reversing and re-feeding path R5.

[0034] 1, the main body casing 50 of the printer is provided with an opening / closing cover 55. The opening / closing cover 55 is provided with a reversing guide member 57 that faces and guides the non-image forming side of the recording sheet on the reversing and returning path R5, and the driving roller 52a of the reversing and conveying roller pair 52 is attached to the reversing guide member 57.

[0035] FIG. 3 is a schematic diagram of the printer showing the opening / closing cover 55 in an open state. When the open / close cover 55 is opened, the fixing device 44 is exposed, and the fixing device 44 is attached to or detached from the printer body in the direction of the outline arrow in the figure.

[0036] Next, a drive transmission device, which is a feature of this embodiment, will be described. FIG. 4 is a perspective view showing the appearance of a drive unit 60 equipped with a drive transmission device according to this embodiment. FIG. 5 is a perspective view showing a state in which the resin housing 61 is removed from the drive device 60 shown in FIG. The drive transmission device mounted on the drive unit 60 of this embodiment transmits driving force from a drive motor, which is the same drive source, to four driven elements: the photosensitive element 1, the developing device 8, the pair of registration rollers 43, and the main body paper feed roller 41.

[0037] The drive unit 60 has a resin housing 61 made of flame-retardant resin and a mounting sheet metal 62. The resin housing 61 has a motor housing portion 61a that covers a drive motor 63, which is the drive source, and a gear housing portion 61b that covers the gear. An opening 61c is formed at the top of the motor housing portion 61a in the figure to take in air for cooling the drive motor and other components, and to pass through a harness that connects the drive motor to the control unit 80 and power supply.

[0038] A photosensitive member drive shaft 74, the tip of which is inserted into the photosensitive member 1, and a coupling portion 90a of the developer drive transmission member 90 pass through the gear housing portion 61b. A photosensitive member coupling 75 is attached to the photosensitive member drive shaft 74 to engage with a flange portion of the photosensitive member 1 and transmit drive force to the photosensitive member 1. Reference numeral 87 in the drawing denotes a registration output gear that outputs drive force from the drive motor 63 to the registration roller pair 43.

[0039] FIG. 6 is a perspective view of the drive unit 60 with the mounting plate 62 removed, as viewed from the mounting plate 62 side. As shown in Fig. 6, a first input gear 71 and a second input gear 81 mesh with a motor gear provided directly on the motor shaft 63a of the drive motor 63. An idler gear 72 meshes with the first input gear 71, and a photosensitive member gear 73 meshes with the idler gear 72. As shown in Fig. 5, the photosensitive member gear 73 is attached to a photosensitive member drive shaft 74.

[0040] The first input gear 71, the second input gear 81, and the idler gear 72 are provided between the mounting metal plate 62 and the motor bracket 63b made of a metal plate.

[0041] A branch gear 82 meshes with the second input gear 81, and this branch gear 82 meshes with a first paper feed gear portion 83a of the paper feed conveyance gear 83 and a first registration gear 84. A first one-way clutch 88A and a first development gear 89 (see FIG. 5) are provided coaxially with this branch gear 82. A driving force is transmitted from the branch gear 82 to the first development gear 89 via the first one-way clutch 88A. The first development gear 89 meshes with a development gear portion 90b of a development drive transmission member 90.

[0042] The first one-way clutch 88A is configured to transmit the driving force from the drive motor 63 to the developing gear portion 90b when the drive motor 63 rotates forward, and not to transmit the driving force from the drive motor 63 to the developing gear portion 90b when the drive motor 63 rotates reversely. Here, in this embodiment, the time when the drive motor 63 is driven to rotate in the direction that rotates the photosensitive member 1 during latent image formation is referred to as "forward rotation," and the time when the drive motor 63 is driven to rotate in the direction opposite to this forward rotation is referred to as "reverse rotation."

[0043] The paper feed conveying gear 83 has a first paper feed gear portion 83a and a second paper feed gear portion 83b, and the driving force of the drive motor 63 input to the first paper feed gear portion 83a is transmitted by the second paper feed gear portion 83b to a paper feed conveying drive transmission mechanism which transmits the driving force to the main body paper feed roller 41.

[0044] A registration electromagnetic clutch 85 (see FIG. 5), which is an electromagnetic clutch serving as an electric clutch, and a registration second gear 86 (see FIG. 5) are provided coaxially with the registration first gear 84. A driving force is transmitted from the registration first gear 84 to the registration second gear 86 via the registration electromagnetic clutch 85. The registration second gear 86 is in mesh with a registration output gear 87, which outputs the driving force of the drive motor to the registration roller pair 43.

[0045] In this embodiment, the driving force from the registration first gear 84 via the registration electromagnetic clutch 85 is also transmitted to the development first gear 89 via the second one-way clutch 88B. The second one-way clutch 88B is configured so as not to transmit the driving force from the drive motor 63 to the development gear portion 90b when the drive motor 63 rotates forward, but to transmit the driving force from the drive motor 63 to the development gear portion 90b when the drive motor 63 rotates reversely.

[0046] FIG. 7 is an explanatory diagram for explaining the transmission path of the driving force of the drive motor 63 when the drive motor 63 rotates forward. FIG. 8 is an explanatory diagram for explaining the transmission path of the driving force of the drive motor 63 when the drive motor 63 rotates in the reverse direction.

[0047] 7, during forward rotation of the drive motor 63, the driving force from the drive motor 63 passes through the second input gear 81 and the branch gear 82, and is transmitted to the first development gear 89 and the development drive transmission member 90 via the first one-way clutch 88A, thereby driving the development roller 8a to rotate through a forward rotation path B1. At this time, the driving force from the drive motor 63 is not transmitted to the development gear portion 90b via the second one-way clutch 88B.

[0048] On the other hand, when the drive motor 63 rotates in the reverse direction, as shown in Fig. 8, the driving force from the drive motor 63 passes through the second input gear 81, the branch gear 82, and the registration first gear 84, and is transmitted to the developing roller 8a (developing sleeve) via the registration electromagnetic clutch 85, the registration second gear 86, and the second one-way clutch 88B, and then from the developing first gear 89 and the developing drive transmission member 90 through a reverse rotation path B2, which can drive the development roller 8a to rotate. However, in this embodiment, as shown in Fig. 8, the registration electromagnetic clutch 85 is disposed on the drive transmission path upstream of the second one-way clutch 88B in the reverse rotation path. Therefore, when the drive motor 63 rotates in the reverse direction, the transmission and interruption of the driving force to the development roller 8a can be performed by controlling the on / off of the registration electromagnetic clutch 85.

[0049] Whether the drive motor 63 is rotating forward or backward, the driving force from the drive motor 63 passes through the first input gear 71 and the idler gear 72, and is transmitted from the photosensitive gear 73 to the photosensitive member 1 via the drive transmission path A, which rotates the photosensitive member 1. In addition, whether the drive motor 63 is rotating forward or reverse, the driving force from the drive motor 63 passes through the second input gear 81, the branch gear 82 and the first register gear 84, and then through the register electromagnetic clutch 85, the second register gear 86 and the register output gear 87 to the pair of register rollers 43, thereby driving the pair of register rollers 43 to rotate through the drive transmission path C.

[0050] The drive device 60 of this embodiment includes a drive transmission device that transmits drive force from the same drive motor 63 to at least three driven members: the photosensitive member 1 as a first driven member, the pair of registration rollers 43 as a second driven member, and the developing roller 8a as a third driven member. In such a drive device 60, it may be desired to drive these driven members 1, 43, and 8a so that their drive times are different from each other when the drive motor 63 is rotating forward or reverse, or both.

[0051] For example, in this embodiment, when a print job is input, the drive motor 63 is driven in the forward direction, and the driving force of the drive motor 63 is transmitted to the photosensitive member 1, causing the photosensitive member 1 to rotate in the forward direction. At this time, the driving force of the drive motor 63 is also transmitted to the developing roller 8a via the forward rotation path B1 and the first one-way clutch 88A, causing the developing roller 8a to rotate in the forward direction as well. Thereafter, when the image forming operation is started, a latent image is formed on the photosensitive member 1, which is being rotated, and the latent image is developed by the developer on the developing roller 8a, which is also being rotated.

[0052] Furthermore, the rotation of the registration roller pair 43 must be stopped until the recording sheet S hits the nip of the registration roller pair 43. Therefore, for a while after the image forming operation starts, even while the photosensitive member 1 and the developing roller 8a are rotating, the registration electromagnetic clutch 85 is turned off and the rotation of the registration roller pair 43 is stopped. Thereafter, at a timing when the recording sheet S can be superimposed on the toner image on the surface of the photosensitive member 1 at the transfer nip, the registration electromagnetic clutch 85 is turned on for a certain period of time, and the recording sheet S is sent to the transfer nip. Then, after the registration roller pair 43 has rotated for a certain period of time, the registration electromagnetic clutch 85 is turned off again and the rotation of the registration roller pair 43 is stopped.

[0053] Thus, in this embodiment, when the drive motor 63 rotates forward, the drive times of the photosensitive member 1 and the developing roller 8a are the same, but the drive time of the registration roller pair 43 is set shorter than the drive time of the photosensitive member 1 and the developing roller 8a.

[0054] Also, for example, in this embodiment, each time a print job is completed, the drive motor 63 is driven in the reverse direction, thereby transmitting the drive force of the drive motor 63 to the photoreceptor 1 and driving it to rotate in the reverse direction. This is because rotating the photoreceptor 1 in the reverse direction separates from the cleaning blade 2 paper dust and toner that accumulates in the contact area between the photoreceptor 1 and the cleaning blade 2 during forward rotation. The paper dust and toner separated from the cleaning blade 2 then falls off the surface of the photoreceptor 1 and is removed from the photoreceptor 1. Note that the drive amount during reverse rotation may cause problems such as affecting the travel distance of the photoreceptor, so it is preferable to keep the drive amount to the minimum necessary.

[0055] At this time, the driving force of the drive motor 63 during reverse rotation is transmitted to the developing roller 8a via the second one-way clutch 88B, thereby driving the developing roller 8a to rotate in the reverse direction as well. Rotating the developing roller 8a in the reverse direction at the end of a print job also has the effect of breaking up the accumulation of developer in the developing device 8 and restoring the fluidity of the developer. However, because driving the developing roller 8a in the reverse direction increases stress on the developer, it is preferable to drive the developing roller 8a in the reverse direction less frequently than the frequency at which the photoconductor 1 is driven in the reverse direction (every time a print job is completed). For example, the developing roller 8a is driven in the reverse direction once every J times (J=2 or a natural number greater than 1) at the end of a print job.

[0056] Therefore, in this embodiment, when the drive motor 63 drives in the reverse direction, it is necessary to provide an electric clutch on the reverse rotation path that can cut off the drive transmission to the developing roller 8a so that the developing roller 8a does not drive in the reverse direction even while the photosensitive member 1 is driven to rotate in the reverse direction. However, if this electric clutch is provided separately from the resist electromagnetic clutch 85, the number of electric clutches mounted in the drive device 60 will increase.

[0057] The electromagnetic clutch generates heat while it is ON (in a state in which it transmits driving force) in order to generate electromagnetic force. In particular, in the present driving device 60, the electromagnetic clutch is housed in a space enclosed by the resin housing 61 and the mounting sheet metal 62, and the heat generated by the electromagnetic clutch when it is driven is trapped within this space. Additionally, the electromagnetic clutch used as a conventional developing clutch is ON for most of the time during image formation (the duty of the electromagnetic clutch is nearly 100%), making temperature rise a significant concern. Therefore, it is preferable to avoid providing an electromagnetic clutch separate from the registration electromagnetic clutch 85 in view of the problem of temperature rise due to heat generated by the electromagnetic clutch. Furthermore, it is also preferable to avoid providing a separate electromagnetic clutch in view of the increased parts costs.

[0058] Therefore, in this embodiment, the resist electromagnetic clutch 85 is used as an electric clutch that can cut off the transmission of drive force to the developing roller 8a so that the developing roller 8a does not rotate in the reverse direction even while the photosensitive member 1 is rotating in the reverse direction when the drive motor 63 is rotating in the reverse direction. This makes it possible to suppress the problem of temperature rise due to heat generated by the electromagnetic clutch and also suppresses increases in parts costs, compared to when an electromagnetic clutch is provided separately from the resist electromagnetic clutch 85.

[0059] Here, if another electric clutch is used as the electric clutch that can cut off the drive transmission to the developing roller 8a when the drive motor 63 is rotating in the reverse direction, the second driven body (the pair of registration rollers 43 in this embodiment), which is the original drive transmission target of the other electric clutch, and the developing roller 8a will be simultaneously turned on and off. Therefore, the other electric clutch that can be used in this embodiment must be an electric clutch that is used for a driven body that can cut off the drive transmission to the developing roller 8a during the period when the drive motor 63 is rotating in the reverse direction, and can transmit the drive during the period when the drive is transmitted to the developing roller 8a.

[0060] In this embodiment, the registration roller pair 43, which is the driving target of the registration electromagnetic clutch 85, does not need to be driven when the drive motor 63 is rotating in reverse, which is an operation other than image formation, because it does not need to transport the recording sheet S. Moreover, even if the registration roller pair 43 is driven when the drive motor 63 is rotating in reverse, there is no recording sheet S, so it simply rotates idly and no adverse effect occurs. Therefore, the registration electromagnetic clutch 85 can be used as an electric clutch that can cut off the drive transmission to the developing roller 8a when the drive motor 63 is rotating in reverse. Of course, any electric clutch other than the registration electromagnetic clutch 85 may be used as long as it satisfies the above-mentioned conditions.

[0061] Furthermore, instead of the one-way clutches 88A and 88B as in this embodiment, a configuration was considered in which a development electromagnetic clutch is provided on the drive transmission path from the drive motor 63 to the developing roller 8a, and both a development electromagnetic clutch and a registration electromagnetic clutch are provided. In this configuration, not only the registration roller pair 43 but also the developing roller 8a can be driven for a drive time that is different from the drive time of the photosensitive member 1, whether the drive motor 63 is rotating forward or reverse. This configuration, for example, enables the development electromagnetic clutch to be turned off and the rotation of the developing roller 8a to be stopped during forward rotation of the drive motor 63 when rotation of the developing roller 8a is not required, thereby suppressing deterioration of the developer. Furthermore, for example, even during reverse rotation of the drive motor 63, the operation of this embodiment described above, i.e., driving the developing roller 8a in the reverse direction less frequently than driving the photosensitive member 1 in the reverse direction (every time a print job is completed), is possible.

[0062] However, because the developing roller 8a must be rotating for most of the time during image formation (while the drive motor 63 is rotating in the forward direction), the developing electromagnetic clutch must remain on for a long period of time. This requires the developing electromagnetic clutch to generate a large amount of heat, which can easily cause temperature rises. This is why a configuration that eliminates the developing electromagnetic clutch is desired. In contrast, the resist electromagnetic clutch 85 is turned on only when the recording sheet S is transported to the transfer nip, so it generates little heat and is less susceptible to temperature rises. Even when the resist electromagnetic clutch 85 is used to reversely drive the developing roller 8a less frequently than the photosensitive element 1 (each time a print job is completed), as in this embodiment, the time the resist electromagnetic clutch 85 is on is not significantly increased, so the temperature rise problem remains minimal.

[0063] FIG. 9 is a flowchart showing an example of control during reverse rotation of the drive motor 63 in this embodiment. When a print job is completed (S1), the control unit 80 adds 1 to the count value n (S2), and then determines whether the count value n has reached J times (S3). If the count value n has not reached J times (No in S3), the control unit 80 stops the forward rotation of the drive motor 63 and then drives the drive motor 63 in the reverse direction (S4) while keeping the resist electromagnetic clutch 85 off. As a result, the photosensitive member 1 is driven in the reverse direction without driving the developing roller 8a in the reverse direction. After that, when t1 seconds have elapsed (Yes in S5), the reverse rotation of the drive motor 63 is stopped (S6), and the reverse rotation of the photosensitive member 1 is stopped.

[0064] On the other hand, if it is determined that the count value n has reached J (Yes in S3), the control unit 80 stops the forward rotation of the drive motor 63, then turns on the registration electromagnetic clutch 85 (S7), and drives the drive motor 63 in the reverse direction (S8). This causes both the photosensitive member 1 and the developing roller 8a to rotate in the reverse direction. After t2 seconds have elapsed (Yes in S9), the registration electromagnetic clutch 85 is turned off (S10). This stops the reverse rotation of the developing roller 8a, but the photosensitive member 1 continues to rotate in the reverse direction. Furthermore, after t3 seconds have elapsed (Yes in S11), the reverse rotation of the drive motor 63 is stopped (S12), and the reverse rotation of the photosensitive member 1 is stopped. Finally, the count value n is reset to zero (S13).

[0065] [Modification] Next, a modification of the drive transmission device of this embodiment will be described. 9, when both the photosensitive member 1 and the developing roller 8a are driven in the reverse direction (Yes in S3), the resist electromagnetic clutch 85 is turned off (S10) before the reverse driving of the drive motor 63 is stopped (S12). This allows the reverse driving time of the developing roller 8a to be shorter than the reverse driving time of the photosensitive member 1.

[0066] However, in the configuration of the above-described embodiment, the reverse drive time of the developing roller 8a cannot be made longer than the reverse drive time of the photosensitive member 1. Therefore, for example, if the reverse drive time of the photosensitive member 1 is lengthened in order to ensure that the reverse drive time of the developing roller 8a is sufficient for the required time, problems such as an increased risk of the cleaning blade turning over due to excessive reverse rotation of the photosensitive member 1 may occur.

[0067] This modified example realizes a configuration in which the reverse drive time of the developing roller 8a is longer than the reverse drive time of the photosensitive element 1, or a configuration in which the reverse drive time of the photosensitive element 1 is shorter than the reverse drive time of the developing roller 8a.

[0068] FIG. 10 is an explanatory diagram for explaining the transmission path of the driving force of the drive motor 63 when the drive motor 63 rotates forward in this modified example. FIG. 11 is an explanatory diagram for explaining the transmission path of the driving force of the drive motor 63 when the drive motor 63 rotates in the reverse direction in this modified example. In this modification, a joint portion 76 is disposed between the photosensitive member gear 73 and the photosensitive member drive shaft 74 of the photosensitive member 1 .

[0069] FIG. 12 is an external perspective view showing a joint portion 76 in this modified example. FIG. 13 is an explanatory diagram showing the backlash of the joint portion 76 in this modified example.

[0070] In this modified example, when the drive motor 63 is driven in the forward direction, the driving force from the drive motor 63 is transmitted to the photosensitive gear 73 via the first input gear 71 and the idler gear 72, and the photosensitive gear 73 is driven to rotate in the forward direction indicated by the symbol F in Fig. 13. As a result, the surface 73a of the joint claw of the photosensitive gear 73, which is downstream in the forward rotation direction, abuts against the forward rotation abutment surface 76a of the joint claw of the joint portion 76, and the joint portion 76 is driven to rotate in the forward direction together with the photosensitive gear 73. As a result, the driving force in the forward rotation direction is transmitted to the photosensitive drive shaft 74 to which the joint portion 76 is attached, and the photosensitive member 1 is driven to rotate in the forward direction.

[0071] On the other hand, when the drive motor 63 is driven in the reverse direction after being driven in the forward direction, the driving force from the drive motor 63 is transmitted to the photosensitive gear 73 via the first input gear 71 and the idler gear 72, and the photosensitive gear 73 is driven to rotate in the reverse direction indicated by the symbol R in Fig. 13. As a result, the joint claw of the photosensitive gear 73 moves in a direction away from the forward rotation abutment surface 76a of the joint claw of the joint portion 76, and eventually the surface 73b of the joint claw, downstream in the reverse direction, abuts against the reverse rotation abutment surface 76b of the joint claw of the joint portion 76. After this abutment, the joint portion 76 is driven to rotate in the reverse direction together with the photosensitive gear 73, and the driving force in the reverse direction is transmitted to the photosensitive drive shaft 74 to which the joint portion 76 is attached, and the photosensitive element 1 is driven to rotate in the reverse direction.

[0072] Backlash is the interval between when the surface 73b of the joint claw downstream in the reverse direction abuts against the reverse abutment surface 76b of the joint claw of the joint portion 76, and the joint portion 76 remains stopped even when the photosensitive element gear 73 is driven to rotate in the reverse direction. Therefore, in this modified example, the photosensitive element 1 is driven in the reverse direction with a delay corresponding to the backlash after the drive motor 63 starts to drive in the reverse direction.

[0073] On the other hand, if the resist electromagnetic clutch 85 is turned on when the drive motor 63 starts to rotate in the reverse direction, the developing roller 8a will be driven in the reverse direction simultaneously with the start of the reverse drive of the drive motor 63. Therefore, according to this modification, the reverse drive time of the photosensitive member 1 can be made shorter than the reverse drive time of the developing roller 8a by the time corresponding to the backlash.

[0074] In this modified example, the time corresponding to the backlash can be changed, for example, by changing the rotational distance between the forward rotation contact surface 76a and the reverse rotation contact surface 76b of the joint claw provided in the joint portion 76. In other words, by changing the rotational distance between the forward rotation contact surface 76a and the reverse rotation contact surface 76b of the joint claw provided in the joint portion 76, the time difference between the reverse rotation drive time of the photosensitive member 1 and the reverse rotation drive time of the developing roller 8a can be adjusted.

[0075] In addition, in this modified example, by turning off the resist electromagnetic clutch 85 at a predetermined timing during the backlash period, it is possible to adjust the time difference between the reverse drive time of the photosensitive member 1 and the reverse drive time of the developing roller 8a within the time range corresponding to the backlash.

[0076] In this modified example, the joint portion 76 is disposed between the photosensitive gear 73 and the photosensitive drive shaft 74 of the photosensitive member 1, but the joint portion 76 may be disposed at any position on the drive transmission path A to the photosensitive member. The joint portion 76 may also be disposed on the drive transmission path (forward rotation path B1 or reverse rotation path B2) to the developing roller 8a.

[0077] The above description is merely an example, and each of the following aspects provides unique effects. [First aspect] The first aspect is a drive transmission device that transmits a drive force from a same drive source (for example, a drive motor 63) to at least three driven bodies, and includes a first drive transmission path A, a second drive transmission path C, and a third drive transmission path B1, B2 that transmit the drive force to a first driven body (for example, a photosensitive body 1), a second driven body (for example, a pair of registration rollers 43), and a third driven body (for example, a developing roller 8a) among the at least three driven bodies, respectively, and an electric clutch (for example, a registration electromagnetic clutch 85) is disposed in the second drive transmission path, and the third drive transmission path includes a forward rotation path B1 that transmits the drive force to the third driven body when the drive source rotates forward, and a forward rotation path B2 that transmits the drive force to the third driven body when the drive source rotates backward. and a reverse rotation path B2 for transmitting the driving force, the forward rotation path having a first one-way clutch 88A disposed therein that transmits the driving force to the third driven body when the driving source rotates forward and does not transmit the driving force to the third driven body when the driving source rotates reverse, and the reverse rotation path having a second one-way clutch 88B disposed therein that does not transmit the driving force to the third driven body when the driving source rotates forward and transmits the driving force to the third driven body when the driving source rotates reverse, and at least one of the forward rotation path and the reverse rotation path transmits the driving force to the third driven body via the electric clutch on the second drive transmission path. In a drive transmission device that transmits drive force from the same drive source to at least three driven bodies, it may be desired to drive these driven bodies so that their drive times differ when the drive source is rotating in the forward direction, reverse direction, or both. In this case, by arranging an electric clutch such as an electromagnetic clutch on each of the drive transmission paths for the two driven bodies and appropriately controlling each electric clutch while the drive source is operating, it is possible to make the drive times of the three driven bodies different from one another. However, electric clutches tend to generate heat and increase in temperature when they are turned on, which can lead to problems such as the need for a cooling device and downtime caused by the temperature increase. In particular, when two or more driven objects are driven simultaneously for a long period of time, the electric clutches are turned on for a long time, which can lead to problems caused by temperature increases. Therefore, it is desirable to reduce the number of electric clutches as much as possible and to have a configuration in which the drive times of at least three driven objects are different from each other. Consider a case where the first drive transmission path does not have an electric clutch, but the second and third drive transmission paths each have an electric clutch, and the electric clutch is simply removed from the third drive transmission path. In this case, the number of electric clutches is reduced, making it possible to suppress problems caused by temperature rise. However, the third driven body corresponding to the third drive transmission path will be driven for the same drive time, both in forward and reverse rotation, as the first driven body corresponding to the first drive transmission path, which does not have an electric clutch. This significantly limits the degree of freedom of the drive operation of the third driven body. On the other hand, consider the case where a one-way clutch is installed in the third drive transmission path instead of excluding the electric clutch from the third drive transmission path. Although a one-way clutch cannot electrically control drive transmission and drive cutoff, it generates less heat than an electric clutch, making it possible to suppress problems caused by temperature increases. However, in this case, the third driven body corresponding to the third drive transmission path is limited to being driven for the same drive time as the first driven body corresponding to the first drive transmission path during either forward or reverse rotation, and not being driven during the other rotation. This significantly limits the degree of freedom in the drive operation of the third driven body. Therefore, in this embodiment, the third drive transmission path that transmits the driving force to the third driven body is divided into two systems, a forward rotation path and a reverse rotation path, and a first one-way clutch and a second one-way clutch are provided on each path. This allows the driving force to be transmitted to the third driven body via different paths (the forward rotation path and the reverse rotation path) during forward and reverse rotation. In this embodiment, at least one of the forward rotation path and the reverse rotation path transmits the driving force to the third driven body via an electric clutch provided on the second drive transmission path. This allows the third driven body to be driven for a different drive time from the drive time of the first driven body during either forward or reverse rotation, even without providing an electric clutch on the third drive transmission path. As a result, it is possible to ensure the freedom of drive operation of the third driven body while suppressing problems caused by temperature rise by not providing an electric clutch on the third drive transmission path.

[0078] [Second mode] The second aspect is characterized in that, in the first aspect, at least one of the paths is such that the electric clutch on the second drive transmission path is located upstream of the drive transmission path of the first one-way clutch or the second one-way clutch. This allows the second driven body to be controlled by the electric clutch without being affected by the operation of the first one-way clutch or the second one-way clutch.

[0079] [Third aspect] The third aspect is characterized in that, in the first or second aspect, the first driven body is a latent image carrier (e.g., photosensitive body 1) in an electrophotographic image forming apparatus (e.g., a printer), and the third driven body is a developer carrier (e.g., developing roller 8a) of a developing device that develops a latent image on the latent image carrier. This makes it possible to ensure freedom of driving operation of the third driven body while suppressing problems caused by temperature rise in a configuration in which the latent image carrier and the developer carrier are driven by the same driving source.

[0080] [Fourth aspect] The fourth aspect is characterized in that, in the third aspect, the second driven body is a registration roller (e.g., a pair of registration rollers 43) that transports, at a predetermined transport timing, a recording material (e.g., a recording sheet S) onto which an image obtained by developing a latent image by the developing device is transferred. This makes it possible to ensure the freedom of driving operation of the third driven body while suppressing problems caused by temperature rise in a configuration in which the latent image carrier, developer carrier, and registration roller are driven by the same drive source. In particular, the electric clutch that cuts off the transmission of drive to the registration roller generates little heat, so it is highly effective in suppressing problems caused by temperature rise.

[0081] [Fifth mode] A fifth aspect is characterized in that, in any of the first to fourth aspects, at least one of the first drive transmission path, the second drive transmission path, and the third drive transmission path has a joint portion 76 in which a backlash is set to generate a drive time difference between the driven body corresponding to the at least one drive transmission path and the driven body corresponding to the other drive transmission paths. This increases the degree of freedom in setting the drive times of the first driven body, the second driven body, and the third driven body.

[0082] [Sixth aspect] The sixth aspect is an image forming apparatus (e.g., a printer) having at least three driven bodies to which a driving force from the same driving source (e.g., a driving motor 63) is transmitted, characterized in that the driving transmission device of any one of the first to fifth aspects is used as a driving transmission device that transmits the driving force from the same driving source to the at least three driven bodies. According to this aspect, it is possible to provide an image forming apparatus that can reduce the number of electric clutches to suppress the problem of temperature rise due to heat generation, while ensuring freedom of driving operation of the driven body by reducing the number of electric clutches. [Explanation of symbols]

[0083] 1: Photoreceptor 2: Cleaning blade 4: Charging roller 7: Latent image writing device 8: Developing device 8a: Developing roller 10: Transfer roller 30: Manual feed unit 41: Main body paper feed roller 42: Relay roller pair 43: Registration roller pair 44: Fixing device 46: Paper discharge roller pair 49: Resist sensor 50: Main unit housing 55: Opening and closing cover 60: Drive unit 61: Resin housing 62: Mounting plate 63: Drive motor 63a: Motor shaft 71: First input gear 72: Idler gear 73: Photosensitive gear 73a: Downstream surface of the jointed claw in the forward rotation direction 73b: Downstream surface of the jointed claw in the reverse direction 74: Photoconductor drive shaft 75: Photoconductor coupling 76: Joint 76a: Contact surface of joint claw during normal rotation 76b: Contact surface of joint claw when rotating in reverse 80: Control unit 81: Second input gear 82: Branch gear 83: Paper feed transport gear 83a: First paper feed gear section 83b:Second paper feed gear section 84: First Resist Gear 85: Resist electromagnetic clutch 86: Resist Second Gear 87: Resist output gear 88A: First one-way clutch 88B: Second one-way clutch 89: First gear for development 90: Development drive transmission member 90a: Coupling part 90b: Developing gear part 100: Paper cassette A: Drive transmission path to the photoconductor B1: Forward rotation path to the developing roller B2: Reverse rotation path to the developing roller C: Drive transmission path to the registration roller pair S: Recording sheet [Prior art documents] [Patent documents]

[0084] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-170215

Claims

1. A drive transmission device that transmits a drive force from a same drive source to at least three driven bodies, Among the at least three driven bodies, a first driven body is a latent image carrier in an electrophotographic image forming apparatus, a second driven body is a registration roller that conveys, at a predetermined conveying timing, a recording material onto which an image obtained by developing a latent image on the latent image carrier by a developing device is transferred, and a third driven body is a developer carrier of the developing device, each of which is provided with a first drive transmission path, a second drive transmission path, and a third drive transmission path that transmit the drive force to each of the first driven body, a latent image carrier in an electrophotographic image forming apparatus, a second driven body is a registration roller that conveys, at a predetermined conveying timing, a recording material onto which an image obtained by developing a latent image on the latent image carrier by a developing device is transferred, and a third driven body is a developer carrier of the developing device, an electric clutch is disposed in the second drive transmission path; the third drive transmission path includes a forward rotation path that transmits the drive force to the third driven body when the drive source rotates in a forward direction, and a reverse rotation path that transmits the drive force to the third driven body when the drive source rotates in a reverse direction, a first one-way clutch is disposed in the forward rotation path, the first one-way clutch transmitting the driving force to the third driven body when the driving source is rotating in the forward direction and not transmitting the driving force to the third driven body when the driving source is rotating in the reverse direction; a second one-way clutch is disposed in the reverse rotation path, the second one-way clutch not transmitting the driving force to the third driven body when the driving source is rotating in the forward direction, and transmitting the driving force to the third driven body when the driving source is rotating in the reverse direction; a drive transmission device, characterized in that at least one of the forward rotation path and the reverse rotation path transmits the drive force to the third driven body via the electric clutch on the second drive transmission path.

2. 2. The drive transmission device according to claim 1, A drive transmission device characterized in that, in at least one of the paths, the electric clutch on the second drive transmission path is located upstream of the first one-way clutch or the second one-way clutch.

3. In the drive transmission device according to claim 1 or 2, a drive transmission device characterized in that at least one of the first drive transmission path, the second drive transmission path, and the third drive transmission path has a joint portion in which backlash is set, causing a drive time difference between the driven body corresponding to the at least one drive transmission path and the driven body corresponding to the other drive transmission paths.

4. An image forming apparatus having at least three driven bodies to which a driving force from the same driving source is transmitted, 4. An image forming apparatus, comprising: a drive transmission device according to claim 1, for transmitting a drive force from the same drive source to the at least three driven members.

Images