Driving device and image forming apparatus

Abstract

To reduce the likelihood of the occurrence of a poor fitting between a drive coupling and a driven coupling without an increase in size and cost of a device.SOLUTION: A relay member 37 transmitting a turning force of a rotation shaft 35 to a drive coupling 36 to rotate the drive coupling 36 together with the rotation shaft 35 is installed fixed to the rotation shaft 35 to be inserted into a hole part 36a of the drive coupling 36. The drive coupling 36 is configured to, when moving toward one end in an axial direction with respect to the relay member 37, be urged toward the other end in the axial direction by a compression spring 38 and is provided with an outer peripheral side regulation part 36c that is opposite to an outer periphery of the compression spring 38 and regulates the movement in a radial direction of the compression spring 38. The relay member 37 is provided with an inner peripheral side regulation part 37e that is opposite to an inner periphery of the compression spring 38 and regulates the movement in the radial direction of the compression spring 38.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to a drive device that drives a detachable unit such as a fixing device or a process cartridge that is detachably mounted on a device main body such as an image forming device, and to an image forming device equipped with the drive device. [Background technology]

[0002] Conventionally, image forming devices have been known that are equipped with a drive device that drives detachable units such as a fixing device and a process cartridge that are detachably installed in the image forming device main body (device main body) (see, for example, Patent Document 1). Such a drive device is provided with a drive coupling that engages with the driven coupling of the detachable unit in conjunction with the attachment operation of the detachable unit to the device main body, and the driving force of the drive motor of the device main body is transmitted to the driven coupling via the drive coupling, thereby driving the detachable unit.

[0003] Such a drive device is configured such that, when the detachable unit is attached to the device main body, and the driven coupling of the detachable unit and the drive coupling of the device main body are in a rotational position such that, when the driven coupling does not engage with the drive coupling, the driven coupling is pushed axially by the driven coupling and slides on the rotation shaft (on which the drive coupling is installed) against the biasing force of a compression spring wound around the rotation shaft. When rotation of the drive coupling begins, the drive coupling assumes a rotational position that allows it to engage with the driven coupling, and moves axially due to the biasing force of the compression spring so that it engages with the driven coupling.

[0004] On the other hand, Patent Document 1 discloses a technique in which a detachable unit is attached to the device body, and a member is provided to hold the compression spring when the drive coupling is pushed in the axial direction by the driven coupling. Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional technology, when the detachable unit is attached to the device body and the driven coupling pushes the drive coupling in the axial direction, and then the drive coupling starts to rotate, the compression spring prevents the drive coupling from moving straight in the axial direction, causing the drive coupling and the driven coupling to not fit together properly.When this occurs, the detachable unit cannot be driven properly. In response to this problem, it is possible to apply the technology of Patent Document 1 and provide a member that holds the compression spring when the drive coupling is pushed axially by the driven coupling. However, in this case, space and costs are required to provide the member that holds the compression spring, which results in an increase in the size and cost of the device.

[0006] The present invention has been made to solve the above-mentioned problems, and aims to provide a drive unit and an image forming apparatus in which poor fitting between the drive coupling and the driven coupling is unlikely to occur, without increasing the size and cost of the apparatus. [Means for solving the problem]

[0007] The drive device of this invention is a drive device that drives a detachable unit that is detachably installed in a device main body, and includes: a drive coupling that moves toward and away from a driven coupling of the detachable unit in conjunction with the attachment and detachment operation of the detachable unit to and from the device main body; an intermediary member that is fixed to a rotating shaft and is inserted into a hole of the drive coupling so as to transmit the rotational force of the rotating shaft to the drive coupling so that the drive coupling rotates together with the rotating shaft; and a compression spring that is wound around the rotating shaft and has one axial end that contacts a contact member that is located farther from the driven coupling than the intermediary member, and has the other axial end that contacts the intermediary member, and is configured to be biased toward the other axial end by the compression spring when the drive coupling moves toward the one axial end relative to the intermediary member, and is equipped with an outer periphery side limiting portion that faces the outer periphery of the compression spring and limits radial movement of the compression spring. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a drive unit and an image forming apparatus in which poor fitting between the drive coupling and the driven coupling is unlikely to occur, without increasing the size and cost of the apparatus. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is an overall configuration diagram showing an image forming apparatus according to an embodiment of the present invention; [Figure 2] FIG. 2 is a diagram illustrating the configuration of an image forming unit. [Figure 3] FIG. 2 is a diagram illustrating a configuration of a fixing device. [Figure 4] 1A is a diagram showing a state immediately before the fixing device is attached to the drive device, and FIG. 1B is a diagram showing a state after the fixing device has been attached to the drive device. [Figure 5] 1A is a diagram showing a state in which the drive coupling and the driven coupling are normally engaged with each other, and FIG. 1B is a diagram showing a state in which the drive coupling and the driven coupling are not normally engaged with each other. [Figure 6] 1A is a diagram showing the main parts of the drive device, and FIG. 1B is a diagram showing the main parts of the drive device from a different direction. [Figure 7] 7A is a diagram showing the main part of the drive device of FIG. 6 excluding the gears, and FIG. 7B is a diagram showing the main part of the drive device from another angle. [Figure 8] 3A to 3C are diagrams showing the relay member from various directions. [Figure 9] 1A to 1C are views showing the drive coupling from various directions. [Figure 10] FIG. [Figure 11] FIG. 2 is a cross-sectional view showing a main part of a drive device. [Figure 12] 1A is a diagram showing a main part of a drive device according to the present invention, and FIG. 1B is a diagram showing a main part of a drive device as a comparative example. [Figure 13] (A) A diagram showing the distance from the axial center of the first and second drive transmission parts, and (B) a diagram showing the first and second virtual polygons formed by the first and second drive transmission parts. [Figure 14] 10 is a graph showing a change over time in a shaft reaction force generated in a drive device. [Figure 15] FIG. 10 is a perspective view showing a main part of a drive device as a comparative example. [Figure 16] FIG. 10 is a front view showing a main part of a drive device as another comparative example. [Figure 17] FIG. 10 is a perspective view showing a main part of a drive device as a first modified example. [Figure 18] FIG. 10 is a perspective view showing a main part of a drive device as a second modified example. [Figure 19] 10A is a perspective view showing a main part of a drive device as a third modified example, and FIG. 10B is a perspective view showing a drive coupling thereof. [Figure 20] FIG. 11 is a perspective view showing a main part of a drive device as a fourth modified example. [Figure 21] FIG. 13 is a perspective view showing a main part of a drive device as a fifth modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and redundant explanations will be appropriately simplified or omitted.

[0011] First, the overall configuration and operation of an image forming apparatus 100 will be described with reference to FIGS. FIG. 1 is a structural diagram showing a printer as an image forming apparatus, and FIG. 2 is an enlarged view showing a part of the image forming unit. 1, an intermediate transfer belt device 15 is installed in the center of the image forming apparatus main body 100. In addition, process cartridges 6Y, 6M, 6C, and 6K corresponding to each color (yellow, magenta, cyan, and black) are arranged side by side so as to face the intermediate transfer belt 8 of the intermediate transfer belt device 15. These process cartridges 6Y, 6M, 6C, and 6K are installed in the image forming apparatus main body 100 so as to be detachable (replaceable).

[0012] 2, the process cartridge 6Y corresponding to yellow is composed of a photosensitive drum 1Y as an image carrier, and a charging device 4Y, a developing device 5Y, a cleaning device 2Y, a lubricant supplying device 3, and a discharging device (not shown) arranged around the photosensitive drum 1Y (drum). Then, an image forming process (charging process, exposure process, developing process, transfer process, cleaning process, discharging process) is performed on the photosensitive drum 1Y, and a yellow image is formed on the surface of the photosensitive drum 1Y.

[0013] The other three process cartridges 6M, 6C, and 6K are configured almost identically to the yellow process cartridge 6Y, except for the toner colors they use, and form images corresponding to their respective toner colors. Below, we will omit the explanation of the other three process cartridges 6M, 6C, and 6K as appropriate and will only explain the yellow process cartridge 6Y.

[0014] 2, the photosensitive drum 1Y is rotated counterclockwise by a drive motor. Meanwhile, a charging bias is applied to the charging device 4Y by a power supply. As a result, the surface of the photosensitive drum 1Y is uniformly charged at the position of the charging device 4Y (charging process). Thereafter, the surface of the photosensitive drum 1Y reaches the irradiation position of the laser light L emitted from the exposure device 7, and an electrostatic latent image (exposure potential) corresponding to yellow is formed by exposure scanning in the width direction (the direction perpendicular to the paper surface of Figures 1 and 2, which is the main scanning direction) at this position (this is the exposure process).

[0015] Thereafter, the surface of the photosensitive drum 1Y reaches a position facing the developing device 5Y, where the electrostatic latent image is developed to form a yellow toner image (developing step). Thereafter, the surface of the photosensitive drum 1Y reaches a position facing the intermediate transfer belt 8 and the primary transfer roller 9Y, where the toner image formed on the surface of the photosensitive drum 1Y is primarily transferred onto the surface of the intermediate transfer belt 8 (the primary transfer step). At this time, a small amount of untransferred toner remains on the photosensitive drum 1Y.

[0016] Thereafter, the surface of the photosensitive drum 1Y reaches a position facing the cleaning device 2Y, and at this position, the untransferred toner remaining on the photosensitive drum 1Y is collected into the cleaning device 2Y by the cleaning blade 2a (cleaning process). Here, a lubricant supplying device 3 (photosensitive drum lubricant supplying device) consisting of a lubricant supplying roller 3a, a solid lubricant 3b, a compression spring 3c, etc. is installed inside the cleaning device 2Y. The lubricant supplying roller 3a, which rotates clockwise in Fig. 2, scrapes off the lubricant little by little from the solid lubricant 3b, and the lubricant is supplied to the surface of the photosensitive drum 1Y by the lubricant supplying roller 3a. Finally, the surface of the photosensitive drum 1Y reaches a position facing a static eliminator (not shown), where the residual potential on the photosensitive drum 1Y is removed. Thus, a series of image forming processes performed on the photosensitive drum 1Y is completed.

[0017] The above-described image forming process is also performed in the other process cartridges 6M, 6C, and 6K in the same manner as in the yellow process cartridge 6Y. That is, laser light L based on image information is irradiated from an exposure device 7 disposed above the image forming unit onto the photosensitive drums 1M, 1C, and 1K of each process cartridge 6M, 6C, and 6K. Thereafter, the toner images of each color formed on the photosensitive drums 1M, 1C, and 1K through the development process by the developing devices 5M, 5C, and 5K are primarily transferred onto the intermediate transfer belt 8 in a superimposed manner. In this way, a color image is formed on the intermediate transfer belt 8.

[0018] The intermediate transfer belt 8 is stretched and supported by a plurality of roller members, and is moved endlessly in the direction of the arrow in FIG. 1 by rotation of a drive roller driven by a motor (not shown). Four primary transfer rollers (see primary transfer roller 9Y in FIG. 2) sandwich the intermediate transfer belt 8 between the photosensitive drums 1Y, 1M, 1C, and 1K, respectively, to form primary transfer nips. A transfer voltage (primary transfer bias) of a polarity opposite to that of the toner is applied to the primary transfer roller (9Y). The intermediate transfer belt 8 then travels in the direction of the arrow and passes through the primary transfer nips in sequence. In this way, the toner images of each color on the photosensitive drums 1Y, 1M, 1C, and 1K are primarily transferred onto the surface of the intermediate transfer belt 8 in a superimposed manner (primary transfer process).

[0019] Thereafter, the intermediate transfer belt 8, onto which the toner images of each color have been primarily transferred in a superimposed state, reaches a position facing the secondary transfer roller 40. At this position, the secondary transfer opposing roller 19 sandwiches the intermediate transfer belt 8 between itself and the secondary transfer roller 74, forming a secondary transfer nip. The four-color toner images formed on the intermediate transfer belt 8 are then secondarily transferred onto a sheet P, such as paper, that has been transported to the position of this secondary transfer nip (secondary transfer process). At this time, untransferred toner that has not been transferred to the sheet P remains on the intermediate transfer belt 8.

[0020] Thereafter, the intermediate transfer belt 8 reaches the position of the intermediate transfer cleaning device, where untransferred toner and other adhering matter adhering to the surface of the intermediate transfer belt 8 is removed. Thus, the series of transfer processes performed on the intermediate transfer belt 8 is completed.

[0021] Referring to FIG. 1, the sheet P transported to the secondary transfer nip position is transported from a paper feed device 41 disposed below the device main body 100 via a paper feed roller 42, a pair of registration rollers 43, etc. More specifically, a plurality of sheets P such as paper are stacked and stored in the paper feed device 41. When the paper feed roller 42 is rotated counterclockwise in FIG. 1, the topmost sheet P is fed through the conveying path toward between the rollers of the pair of registration rollers 43.

[0022] The sheet P conveyed to the registration roller pair 43 (timing roller pair) is temporarily stopped at the roller nip position of the registration roller pair 43, which has stopped rotating. Then, the registration roller pair 43 is rotated in synchronization with the color image on the intermediate transfer belt 8, and the sheet P is conveyed toward the secondary transfer nip. In this way, the desired color image is transferred onto the sheet P.

[0023] Thereafter, the sheet P onto which the color image has been transferred at the secondary transfer nip position is transported to the position of the fixing device 20 (detachable unit) by the transport belt 50. Then, at this position, the color image transferred onto the surface is fixed onto the sheet P by the heat and pressure of the fixing roller and pressure roller (the fixing process). Thereafter, the sheet P passes through a conveyance path and is discharged to the outside of the apparatus by a pair of discharge rollers. The sheets P discharged to the outside of the apparatus by the pair of discharge rollers are sequentially stacked on a stack unit as output images. In this way, a series of image forming operations (printing) in the image forming apparatus is completed. In this embodiment, the fixing device 20 is a detachable unit that can be attached to the image forming apparatus main body 100 as the apparatus main body, which will be described in detail later.

[0024] Next, the configuration and operation of the developing device 5Y in the process cartridge 6Y will be described in more detail with reference to FIG. The developing device 5Y is composed of a developing roller 51Y facing the photosensitive drum 1Y, a doctor blade 52Y facing the developing roller 51Y, two conveying screws 55Y disposed in a developer container, and a concentration detection sensor 56Y that detects the toner concentration in the developer. The developing roller 51Y is composed of a magnet fixed inside and a sleeve that rotates around the magnet. A two-component developer G consisting of carrier and toner is contained in the developer container.

[0025] The developing device 5Y configured in this manner operates as follows. The sleeve of the developing roller 51Y rotates in the direction of the arrow in FIG. 2. The developer G carried on the developing roller 51Y by the magnetic field generated by the magnet moves on the developing roller 51Y as the sleeve rotates. The developer G in the developing device 5Y is adjusted so that the ratio of toner in the developer G (toner concentration) falls within a predetermined range. Specifically, when a toner concentration sensor installed in the developing device 5Y detects that the toner concentration is low, new toner is replenished from the toner container 58 into the developing device 5Y so that the toner concentration falls within the predetermined range. Thereafter, the toner supplied from the toner container 58 to the developer storage section circulates between the two separated developer storage sections (movement in the direction perpendicular to the plane of the paper in FIG. 2) while being mixed and stirred by the two transport screws 55Y together with the developer G. Then, the toner in the developer G is attracted to the carrier due to frictional charging with the carrier, and is carried on the developing roller 51Y together with the carrier by the magnetic force formed on the developing roller 51Y.

[0026] The developer G carried on the developing roller 51Y is transported in the direction of the arrow in FIG. 2 and reaches the position of the doctor blade 52Y. The developer G on the developing roller 51Y is then adjusted to an appropriate amount at this position, and then transported to a position facing the photosensitive drum 1Y (the developing area). The toner is then attracted to the latent image formed on the photosensitive drum 1Y by an electric field formed in the developing area. Thereafter, the developer G remaining on the developing roller 51Y reaches above the developer storage section as the sleeve rotates, and is detached from the developing roller 51Y at this position. The electric field formed in the developing area is formed by the potential difference between the developing bias applied to the developing roller 51Y by a power supply and the exposure potential on the photosensitive drum 1Y. The toner container 58 is detachably (replaceably) installed in the process cartridge 6Y (image forming apparatus 100). When the new toner stored therein becomes empty, the toner container 58 is removed from the developing device 5Y (image forming apparatus 100) and replaced with a new one.

[0027] Hereinafter, the fixing device 20 as a detachable unit in this embodiment will be described with reference to FIG. The fixing device 20 functions as a detachable unit that can be attached to the image forming apparatus main body 100, which serves as the apparatus main body. Specifically, a user, service person, or other worker opens the access cover of the image forming apparatus main body 100 when the image forming apparatus is not in operation to expose the fixing device 20, and then pulls out the fixing device 20 toward the front in the installation direction (the direction perpendicular to the plane of the paper in FIG. 1, and the left-right direction in FIG. 4) to perform maintenance, replacement, jam clearance, or the like on the fixing device 20. As shown in FIG. 3, the fixing device 20 is made up of a fixing roller 21 as a fixing rotor, a rod-shaped heater 25 (heating means), a pressure roller 22 as a pressure rotor, and the like. Fixing roller 21, which serves as a fixing rotor, is a roller member with a multilayer structure in which an elastic layer and a release layer are laminated on a core metal, and is in pressure contact with pressure roller 22, which serves as a pressure rotor, to form a nip portion (fixing nip). Fixing roller 21 is driven to rotate clockwise in FIG. 2 by drive device 30 controlled by control unit 90. The drive device 30 will be described in detail later. A rod-shaped heater 25 is fixed inside the hollow fixing roller 21. The fixing roller 21 is heated by radiant heat from the heater 25, the output of which is controlled by the control unit 90, and the heat is applied to the toner image T on the sheet P from the surface of the heated fixing roller 21. The output control of the heater 25 is performed based on the detection result of the roller surface temperature by a temperature sensor that faces the surface of the fixing roller 21 without contacting it. 3. The pressure roller 22 as a pressure rotating body is mainly a roller member having an elastic layer formed on a core metal, and is rotated counterclockwise in FIG.

[0028] When a print command (print request) is input, the drive device 30 starts rotating the fixing roller 21 clockwise, and the pressure roller 22 starts rotating counterclockwise. Thereafter, a sheet P is fed from the paper feed device 41, and at the position of the secondary transfer roller 40, the toner image on the intermediate transfer belt 8 is carried on the sheet P as an unfixed image. The sheet P carrying the unfixed image T (toner image) is transported in the direction of the arrow in FIG. 3 and sent into the nip portion between the fixing roller 21 and the pressure roller 22, which are in a pressure-contact state. The toner image T is then fixed on the surface of the sheet P by the heat from the fixing roller 21 and the pressing force of the fixing roller 21 and the pressure roller 22. After the fixing process, the sheet P is sent out from the nip portion in the direction of the arrow by the rotating fixing roller 21 and pressure roller 22.

[0029] The driving device 30, which is a feature of the image forming apparatus 100 according to the present embodiment, will be described in detail below. Referring to FIG. 4, a driving device 30 drives a fixing device 20 (fixing unit) as a detachable unit that is detachably installed in an image forming apparatus main body 100 as an apparatus main body. As shown in FIG. 4, the driving device 30 is made up of a driving motor 31, a driving gear 32, a gear 33, a rotating shaft 35, a driving coupling 36, a relay member 37, a compression spring 38, bearings 34 and 39, and the like. The drive motor 31 is fixed to a side plate of the image forming apparatus main body 100, and a drive gear 32 (meshing with a gear 33 of a rotary shaft 35) is provided on the motor shaft. The rotating shaft 35 is rotatably supported by the main body side plate (and bracket) of the image forming apparatus main body 100 via two bearings 34, 39. A gear 33, a drive coupling 36, an intermediate member 37, and the like that are rotatable together with the rotating shaft 35 are mounted on the rotating shaft 35. The rotational force (driving force) of the drive motor 31 is transmitted from the drive gear 32 to the gear 33, and the rotating shaft 35 rotates together with the drive coupling 36 and intermediate member 37 in a predetermined direction. The configurations and operations of the drive coupling 36 and the relay member 37 will be described in detail later with reference to FIGS. 6 to 9.

[0030] Referring to FIG. 4, fixing device 20 as a detachable unit is configured to be detachable from image forming apparatus main body 100 (apparatus main body). Specifically, during maintenance, jam removal, etc., the fixing device 20 is pulled out from the image forming apparatus main body 100 along a slide rail (not shown) in the direction opposite to the arrow in Fig. 4(A) (moving from the state in Fig. 4(B) to the state in Fig. 4(A)). At this time, the driven coupling 26 of the fixing device 20 is disengaged from the drive coupling 36 of the image forming apparatus main body 100. After the worker has finished the work, the fixing device 20 is pushed along a slide rail (not shown) into the image forming apparatus main body 100 in the direction of the arrow in FIG. 4A (moving from the state in FIG. 4A to the state in FIG. 4B). As a result, a positioning pin (not shown) provided on the housing of the fixing device 20 engages with a positioning hole (not shown) formed in a side plate of the image forming apparatus main body 100, thereby determining the position of the fixing device 20 relative to the image forming apparatus main body 100. Furthermore, as shown in FIGS. 4B and 5A, the driven coupling 26 provided on the fixing device 20 engages with the drive coupling 36 of the drive device 30 of the image forming apparatus main body 100, enabling the fixing device 20 to be driven by the drive device 30 (drive motor 31). The fixing device 20 (detachable unit) has a driven coupling 26 (see FIG. 10) formed with a gear portion 27 rotatably mounted via a bearing 29 (see FIG. 5) on a stud fixedly mounted on the housing of the fixing device 20 (detachable unit). The gear portion 27 of the driven coupling 26 is engaged with a gear 28 mounted on the fixing roller 21. This configuration enables the driving device 30 to drive the fixing device 20 (rotating the fixing roller 21 and pressure roller 22).

[0031] The driving device 30 will be described in detail below. As previously described with reference to FIG. 4, the drive coupling 36 moves toward and away from (engages and disengages from) the driven coupling 26 of the fixing device 20 in conjunction with the attachment and detachment of the fixing device 20 (attachment / detachment unit) to and from the image forming apparatus main body 100 (apparatus main body). When the drive coupling 36 is properly engaged with the driven coupling 26, as shown in FIG. 5(A), the three claw portions 36b of the drive coupling 36 are engaged with the three claw portions 26b of the driven coupling 26, respectively. Then, a rotational force (driving force) is transmitted from the three claw portions 36b of the drive coupling 36 to the three claw portions 26b of the driven coupling 26, respectively.

[0032] As shown in Figures 5 to 7, the relay member 37 is fixed to the rotating shaft 35 so as to be inserted into the hole portion 36a (a through hole formed around the central axis so as to include the central axis) of the drive coupling 36. The relay member 37 transmits the rotational force of the rotating shaft 35 to the drive coupling 36 so that the drive coupling 36 rotates together with the rotating shaft 35. That is, the relay member 37 is a member that receives the rotational force of the rotating shaft 35 and relays and transmits the rotational force to the drive coupling 36. The drive coupling 36 is held axially movable relative to the relay member 37, which is fixed to the rotating shaft 35 so as not to move axially. As shown in FIGS. 5 to 7, three protrusions 37c (see FIG. 8) of the relay member 37 are fitted into three recesses (portions formed by three small-diameter portions 36d; see FIGS. 9, 13, etc.) of the drive coupling 36, respectively. The rotational force (driving force) is transmitted from the three protrusions 37c of the relay member 37 to the three recesses (small-diameter portions 36d) of the driven coupling 26, respectively.

[0033] 5 to 7, 11, etc., the compression spring 38 is wound around the rotary shaft 35. One axial end of the compression spring 38 (on the right side in FIG. 11) is in contact with the bearing 34 (located farther from the driven coupling 26 than the relay member 37) serving as an abutment member, and the other axial end (on the left side in FIG. 11) is in contact with the relay member 37. In other words, the compression spring 38 is wound around the rotary shaft 35 with a gap between the bearing 34 and the driven coupling 26. At this time, the biasing force (spring force) of the compression spring 38 is not acting on the drive coupling 36. When the drive coupling 36 is normally engaged with the driven coupling 26 as shown in Fig. 5(A) or when the fixing device 20 is separated from the drive device 30 (image forming apparatus main body 100) as shown in Fig. 4(A), the compression spring 38 is located between the bearing 34 and the contact portion 37d of the relay member 37 (see Figs. 6(A), 8(B), etc.). When the drive coupling 36 is not normally engaged with the driven coupling 26 as shown in Fig. 5(B), the compression spring 38 is located between the bearing 34 and the small diameter portion 36d of the drive coupling 36 (see Fig. 9, etc.), and urges the drive coupling 36 toward the driven coupling 26. That is, when the drive coupling 36 moves toward one axial end (the right side in Figure 11) relative to the relay member 37, it is configured so that it is biased by the compression spring 38 toward the other axial end (the left side in Figure 11, in the direction approaching the driven coupling 26).

[0034] Specifically, the drive coupling 36 is configured so that when it moves beyond a predetermined distance W toward one axial end (the right side in Figure 11) relative to the relay member 37, it is biased by the compression spring 38 toward the other axial end (the left side in Figure 11, in the direction approaching the driven coupling 26). 5(B), when the drive coupling 36 is pushed by the driven coupling 26 due to a fitting failure and moves toward one axial end, the compression spring 38 does not come into contact with the drive coupling 36 (small diameter portion 36d) until the moving distance reaches a predetermined distance W, and after the moving distance reaches the predetermined distance W, the compression spring 38 comes into contact with the drive coupling 36 (small diameter portion 36d) and a biasing force acts on the drive coupling 36. Here, the above-mentioned "predetermined distance W" is set to be sufficiently shorter than the distance by which the drive coupling 36 is pushed by the driven coupling 26.

[0035] 5(B), the drive coupling 36 moves to one axial end side (the right side in FIG. 11) due to the relationship between the rotational orientation of the three claw portions 26b of the driven coupling 26 of the fixing device 20 and the rotational orientation of the three claw portions 36b of the drive coupling 36 when the fixing device 20 is being attached to the image forming apparatus main body 100 as shown in FIG. 4(A). Specifically, if the rotational orientation of the claw portions 26b, 36b causes the tips of the claw portions 26b, 36b to come into contact with each other as shown in FIG. 5(B), the driven coupling 26 will push the drive coupling 36 in the axial direction against the biasing force of the compression spring 38, causing it to slide on the rotation shaft 35. Then, when the drive device 30 (drive motor 31) starts to rotate the drive coupling 36, the drive coupling 36 assumes a rotational posture (the posture shown in Figure 5(A)) that allows it to engage with the driven coupling 26, and moves axially due to the biasing force of the compression spring 38 to engage with the driven coupling 26 (the side surfaces of both claw portions 26b, 36b come into contact with each other).

[0036] The relay member 37 will now be described in more detail. As shown in FIG. 8, the relay member 37 is a substantially cylindrical member having a hole 37a formed therein, a stopper portion 37b, a protrusion 37c, and the like. The stopper portion 37b restricts movement of the drive coupling 36 toward the other axial end side (the left side in FIG. 11), and is formed so as to be able to come into contact with the other axial end side of the small diameter portion 36d (see FIG. 9) of the drive coupling 36. Providing the stopper portion 37b can prevent the drive coupling 36 from falling off the rotating shaft 35.

[0037] The protruding portions 37c are divided into three parts at equal intervals in the circumferential direction around the rotation axis, and are formed so as to protrude radially in the radial direction. The side surface of the protrusion 37c (the side surface on the upstream side in the rotation direction) is a portion that contacts the drive coupling and functions as a first drive transmission portion 37c1 that transmits the rotational force of the rotary shaft 35 to the drive coupling . In this embodiment, the first drive transmission portion 37c1 is a portion where the relay member 37 and the drive coupling 36 make line contact. That is, the protrusion 37c of the relay member 37 and the small diameter portion 36d of the drive coupling 36 make line contact rather than surface contact. Specifically, in this embodiment, the side surface (drive-receiving portion) of the small diameter portion 36d of the drive coupling 36 is formed into a curved surface, and the first drive transmission portion 37c1 of the relay member 37 is formed into a flat surface. This reduces frictional resistance caused by contact between the protrusion 37c and the small diameter portion 36d, and allows the rotational force (driving force) to be efficiently transmitted from the relay member 37 to the drive coupling 36.

[0038] In addition, the protrusion 37c is formed in a stepped shape on the other axial end side, with the small diameter portion functioning as the inner limiting portion 37e (the portion facing the inner diameter portion of the compression spring 38), and the stepped portion (the wall surface whose diameter changes) functioning as the contact portion 37d. Here, the inner periphery-side limiting portion 37e of the relay member 37 faces the inner periphery of the compression spring 38 and limits the radial movement of the compression spring 38. That is, even if the compression spring 38 attempts to move (shift) radially by the amount of the gap between the compression spring 38 and the rotary shaft 35, the inner periphery of the compression spring 38 comes into contact with the inner periphery-side limiting portion 37e, thereby limiting the movement. That is, the inner periphery-side limiting portion 37e functions as a guiding member to maintain the position of the compression spring 38 relative to the rotary shaft 35. Therefore, as previously described with reference to FIGS. 5A and 5B, even if the compression spring 38 expands and contracts (expands and contracts between a position where it does not contact the drive coupling 36 and a position where it contacts the drive coupling 36, which moves in the axial direction), problems such as radial shift or tilt of the compression spring 38 are reduced.

[0039] 6A, 7B, etc., the contact portion 37d is a portion with which the end face on the other axial end side of the compression spring 38 comes into contact under normal conditions. As described above, when the drive coupling 36 and the driven coupling 26 are normally engaged with each other and the fixing device 20 is driven by the drive device 30, the compression spring 38 comes into contact with the contact portion 37d (relay member 37), and the biasing force thereof does not act on the drive coupling 36. That is, in this embodiment, when the drive coupling 36 is engaged with the driven coupling 26 and drive can be transmitted from the drive coupling 36 to the driven coupling 26, the compression spring 38 comes into contact with the contact portion 37d of the relay member 37 without coming into contact with the drive coupling 36. This makes it possible to reduce the inconvenience of a large axial reaction force being applied to the drive coupling 36 and the driven coupling 26 even if the drive coupling 36 and the driven coupling 26 are misaligned or have an angular misalignment.

[0040] In this embodiment, the contact portion 37d of the relay member 37 is divided into three or more portions (three portions in this embodiment) in the circumferential direction around the rotation axis. By providing three or more contact portions 37d in the circumferential direction in this manner, the end face of the compression spring 38 can be supported in a balanced manner, and the problem of the compression spring 38 coming into contact with the drive coupling 36 under normal conditions can be prevented.

[0041] 8, a tapered portion 37f is formed on the other axial end side of the inner limiting portion 37e, the diameter of which gradually decreases toward the other axial end side. By providing the tapered portion 37f in this manner, as previously described with reference to FIGS. 5A and 5B, the compression spring 38 can smoothly expand and contract (i.e., expand and contract between a position where it does not contact the drive coupling 36 and a position where it contacts the drive coupling 36 as it moves in the axial direction) without being caught on the inner limiting portion 37e. In other words, the tapered portion 37f functions as a guide surface that guides the expansion and contraction of the compression spring 38.

[0042] In this embodiment, the relay member 37 is made of a metal material, similar to the rotating shaft 35. In the manufacturing process of the drive unit 30, the relay member 37 is attached to the rotating shaft 35 from the other axial end side (the left side in FIG. 11 ) and fixed to the rotating shaft 35 by press-fitting or the like.

[0043] Next, the drive coupling 36 will be described in more detail. As shown in FIG. 9 , the drive coupling 36 is a substantially cylindrical member made of a resin material, with a hole 36a formed inside and three claws 36b formed at one axial end of the drive coupling 36. Three small-diameter portions 36d are formed inside the drive coupling 36 at equal intervals with gaps (recesses) between them. As described above, the protrusion 37c of the relay member 37 fits into the three gaps (recesses) formed by the three small-diameter portions 36d, thereby transmitting drive force from the relay member 37 to the drive coupling 36. Specifically, the side surface of the protrusion 37c (first drive transmission portion 37c1) contacts the side surface of the small-diameter portion 36d (the side surface upstream in the rotation direction) to transmit the rotational force of the rotary shaft 35 to the drive coupling 36. As described above, the surface of one axial end of the small diameter portion 36d is formed so as to be able to come into contact with the stopper portion 37b of the relay member 37. Furthermore, the surface of the other axial end of the small diameter portion 36d is the portion that comes into contact with the end face of one axial end of the compression spring 38 when a fitting failure occurs between the drive coupling 36 and the driven coupling 26.

[0044] The three claws 36b of the drive coupling 36 are formed at equal intervals with gaps between them. The side surface of the claw portion 36b (the side surface upstream in the rotational direction) is a part that functions as a second drive transmission portion 36b1 that contacts the side surface (the driven transmission portion 26b1) of the claw portion 26b (see Figure 10) of the driven coupling 26 and transmits the rotational force of the drive coupling 36 to the driven coupling 26. In this embodiment, the second drive transmission portion 36b1 is a portion where the drive coupling 36 and the driven coupling 26 come into line contact. That is, the claw portions 36b of the drive coupling 36 and the claw portions 26b of the driven coupling 26 are configured to come into line contact rather than surface contact. Specifically, in this embodiment, the second drive transmission portion 36b1 of the claw portions 36b of the drive coupling 36 is formed into a curved surface, and the driven transmission portion 26b1 of the claw portions 26b of the driven coupling 26 is formed into a flat surface. This reduces frictional resistance caused by contact between the claw portions 26b, 36b, and allows the rotational force (driving force) to be efficiently transmitted from the drive coupling 36 to the driven coupling 26.

[0045] 9 and other figures, the small diameter portion 36d of the drive coupling 36 is provided so as to form a step at a position away from the end face on the other axial end side toward the one axial end side, and the step portion functions as the outer circumferential limiting portion 36c. The outer limiting portion 36c of the drive coupling 36 faces the outer periphery of the compression spring 38 and limits the radial movement of the compression spring 38. That is, even if the compression spring 38 attempts to move (shift) radially by the amount of the gap between the compression spring 38 and the rotary shaft 35, the outer periphery of the compression spring 38 comes into contact with the outer limiting portion 36c, thereby limiting the movement. That is, the outer limiting portion 36c functions as a guiding member to maintain the position of the compression spring 38 relative to the rotary shaft 35. Therefore, as previously described with reference to FIGS. 5(A) and 5(B), even if the compression spring 38 expands and contracts (expands and contracts between a position where it does not contact the drive coupling 36 and a position where it contacts the drive coupling 36, which moves in the axial direction), problems such as radial displacement or tilt of the compression spring 38 are reduced. The outer peripheral limiting portion 36c of the drive coupling 36 is formed in a circumferential (annular) shape so as to cover the other axial end side of the compression spring 38 in the hole portion 36a.

[0046] 10, the driven coupling 26 of the fixing device 20 (detachable unit) has three claws 26b formed at the axial end of the gear portion 27. As described above, the side surfaces of the three claws 26b function as the drive transmission portion 26b1. In the present embodiment, the driven coupling 26 has a bearing integrally installed in its hole 26 a , and is rotatably held by a stud installed in the housing of the fixing device 20 .

[0047] In this way, in the drive device 30 of this embodiment, an outer periphery limiting portion 36c that faces the outer periphery of the compression spring 38 and limits the radial movement of the compression spring 38 is formed on the drive coupling 36, and an inner periphery limiting portion 37e that faces the inner periphery of the compression spring 38 and limits the radial movement of the compression spring 38 is formed on the relay member 37. This makes it possible to prevent improper fitting between the drive coupling 36 and the driven coupling 26 without increasing the size and cost of the drive device 30.

[0048] Specifically, in a comparative example, as shown in FIG. 12B , when a drive coupling 136 and relay member 137 without a limiting portion for limiting the radial movement of the compression spring 38 are used, the compression spring 38 comes into contact with the end face of the drive coupling 36 when the fixing device 20 is mounted in the image forming apparatus main body 100 and the driven coupling pushes the drive coupling 136 in the axial direction (see the area surrounded by the dashed line in FIG. 12B ). In this state, when the drive coupling 136 begins to rotate, radial misalignment or tilt of the compression spring 38 can cause the drive coupling 136 to not move straight in the axial direction, potentially resulting in a malfunction in which the drive coupling 136 and the driven coupling do not properly engage with each other. If such a malfunction occurs, the fixing device 20 will not be properly driven by the drive device 30. In contrast, referring to Figure 12(A), in this embodiment, the outer circumferential limiting portion 36c and the inner circumferential limiting portion 37e ensure that the posture of the compression spring 38 is maintained correctly even when the compression spring 38 expands or contracts, making such problems less likely to occur. In this embodiment, instead of providing a separate member for maintaining the posture of the compression spring 38, shapes are added to the drive coupling 36 and the relay member 37, respectively, to maintain the posture of the compression spring 38. This eliminates the need for space and cost for providing a member for maintaining the compression spring 38, thereby preventing the drive unit 30 from becoming larger and more expensive.

[0049] Referring to FIG. 13(A), in the drive device 30 of this embodiment, the distance M from the second drive transmission portion 36b1, where the drive coupling 36 and the driven coupling 26 come into contact, to the axial center X of the rotating shaft 35 is longer than the distance N from the first drive transmission portion 37c1, where the relay member 37 and the drive coupling 36 come into contact, to the axial center X of the rotating shaft 35 (M>N). In other words, the relay member 37 is compactly inserted into the hole 36a of the drive coupling 36 so that the portion where drive is transmitted from the relay member 37 to the drive coupling 36 is contained within the portion where drive is transmitted from the drive coupling 36 to the driven coupling 26. By configuring in this manner, the force acting on the drive transmission parts of the drive coupling 36 and the relay member 37 can be reduced and their durability can be improved by simply ensuring sufficient size in the radial direction, without having to increase the axial size of the drive coupling 36 and the relay member 37.

[0050] 13(A), the drive device 30 in this embodiment has the same number of first drive transmission parts 37c1 and second drive transmission parts 36b1, each of which is three or more and radially arranged around the rotation axis X. Specifically, in this embodiment, when viewed in the axial direction, the three first drive transmission parts 37c1 and the three second drive transmission parts 36b1 are formed at equal intervals (120° intervals) in the rotational direction. With this configuration, a well-balanced drive transmission from the relay member 37 to the driven coupling 26 via the drive coupling 36 is possible.

[0051] Furthermore, referring to Figure 13 (B), when viewed in the axial direction, the drive device 30 in this embodiment has a first imaginary polygon B circumferentially connecting the multiple first drive transmission parts 37c1 and a second imaginary polygon A circumferentially connecting the multiple second drive transmission parts 36b1, which are similar in shape. By configuring it in this manner, as shown in Figure 13(B), it becomes possible to arrange the rotational directions of the first drive transmission part 37c1 and the second drive transmission part 36b1 with their positions (phases) shifted, thereby enabling well-balanced drive transmission from the relay member 37 to the driven coupling 26 via the drive coupling 36.

[0052] In particular, referring to Figure 13(B), in this embodiment, when viewed in the axial direction, the first imaginary polygon B and the second imaginary polygon A are in a positional relationship rotated by 180 degrees. As a result, even if the drive coupling 36 is tilted due to misalignment of the shaft center or the like, it is possible to reduce the axial reaction force that occurs in the drive coupling 36. In particular, by changing the sizes of the first imaginary polygon B and the second imaginary polygon A, it is possible to keep the axial size of the drive unit 30 small while still ensuring space for the compression spring 38 to expand and contract, thereby reducing poor fitting in the drive unit 30.

[0053] FIG. 14 is a graph showing the results of an experiment conducted by the inventors of the present application to confirm the effects of the configuration of the drive device 30 described using FIG. 13, and shows the change over time in the axial reaction force generated in the drive device 30 (drive coupling 36). The drive coupling is required to transmit rotational force as is during operation. However, in actual use, mechanical variations can cause misalignment between the driven coupling on the removable unit and the drive coupling on the main assembly of the apparatus. Even when such misalignment occurs, it is necessary to reduce the force generated when the couplings are mated. However, if the magnitude or amount of fluctuation of such force is large, the force generated between the removable unit and the main assembly of the apparatus can cause various problems, such as fluctuations in the posture of the removable unit. For example, if the removable unit is a sheet transport unit such as the fixing device 20, this can cause fluctuations in the sheet transport speed or skewed sheet transport. Furthermore, if the removable unit is a unit involved in image formation such as a process cartridge, this can cause image irregularities and other abnormalities. 14(B) is a graph showing the change over time in the axial reaction force when a comparative example is used, as shown in Fig. 15, in which a drive coupling 236 transmits rotational force by a parallel pin 136 attached to a rotation shaft 135. In this experiment, an axial misalignment of 0.3 mm was applied to the engagement between the drive coupling 236 and the driven coupling 26. In contrast, Figure 14(A) is a graph showing the change in axial reaction force over time when using the driving device 30 of this embodiment, with the same axial misalignment of 0.3 mm as in Figure 14(B) and driving at the same load and rotation speed. 14(A) and (B) show that the drive unit 30 of this embodiment can significantly reduce the axial reaction force (by about 1 / 8) compared to the drive unit shown in Fig. 15. It can also be seen that the amount of variation in the axial reaction force (the difference between the maximum and minimum values) can be reduced by about 70%. FIG. 14(C) is a graph showing the change in axial reaction force over time when a drive unit, as shown in FIG. 16, is used as another comparative example, in which the first drive transmission unit 37c1 is shifted by 30° in the rotational direction relative to the drive unit shown in FIG. 13. The drive unit is shifted by 0.3 mm, the same amount of axial misalignment as in FIGS. 14(A) and 14(B), and is driven at the same load and rotation speed. The experimental results in FIGS. 14(A) and 14(C) reveal that the variation in axial reaction force (the difference between the maximum and minimum values) can be significantly reduced by positioning the first drive transmission unit 37c1 and the second drive transmission unit 36b1 under the conditions previously described with reference to FIG. 13. This means that drive force is transmitted smoothly with minimal rotational irregularities.

[0054] In this embodiment, the relay member 37 is made of a metal material and is press-fitted onto the rotating shaft 35. If the relay member 37 were made of a resin material, a retaining ring such as an E-ring would need to be installed to prevent the relay member 37 from falling off the rotating shaft 35. However, if the relay member 37 is made of a metal material, the installation of such a retaining ring is not necessary, which enables a reduction in the number of parts and space savings. In this embodiment, the drive coupling 36 is made of a resin material with excellent sliding properties, so that the axial reaction force does not become large even if the axial center is misaligned.

[0055] <Comparative Example 1> As shown in FIG. 17, in the drive device 30 as modified example 1, the outer peripheral limiting portion 36c of the drive coupling 36 is formed so that its one axial end side (the side away from the driven coupling) gradually increases in inner diameter from the other axial end side toward the one axial end side (inclined surface 36c1). That is, when viewed in a cross section including the axis center X of the rotary shaft 35, the outer circumferential limiting portion 36c is not parallel to the axis center X but is formed in an inclined tapered shape. In this way, by forming an inclined surface 36c1 on one axial end side of the outer peripheral limiting portion 36c, when assembling the compression spring 38, drive coupling 36, and relay member 37 to the rotating shaft 35, the compression spring 38 is guided by the inclined surface 36c1 and comes into contact with the desired contact portion 37d, thereby improving the assembly ease of the drive unit 30.

[0056] <Comparative Example 2> As shown in FIG. 18, in the drive device 30 of the second modification, the outer peripheral limiting portion 36c of the drive coupling 36 is formed in the shape of a rib extending in the axial direction. That is, when viewed in a cross section perpendicular to the axial direction of the rotating shaft 35, the outer peripheral limiting portion 36c is not formed in a flat circumferential shape, but is formed in an uneven circumferential shape. As described above, the drive coupling 36 is made of a resin material, and therefore needs to have an appropriate lightening shape in consideration of the molding manufacturing process. When such a lightening shape is provided in the outer peripheral limiting portion 36c, forming it into a rib shape as described above can maintain the functionality of the outer peripheral limiting portion 36c.

[0057] <Comparative Example 3> As shown in FIG. 19 , in the drive device 30 of the third modification, the second drive transmission portion 36b1 is a portion where the drive coupling 36 and the driven coupling 26 make point contact. That is, the claw portions 36b of the drive coupling 36 and the claw portions 26b of the driven coupling 26 make point contact rather than line contact. Specifically, in the third modification, the second drive transmission portion 36b1 of the claw portions 36b of the drive coupling 36 is formed in a hemispherical shape, and the driven transmission portion 26b1 of the claw portions 26b of the driven coupling 26 is formed in a flat shape. This further reduces frictional resistance caused by contact between the claw portions 26b, 36b, and allows the rotational force (driving force) to be efficiently transmitted from the drive coupling 36 to the driven coupling 26. In the third modification, the first drive transmission portion 37c1 is a portion where the relay member 37 and the drive coupling 36 make line contact, but similar to the second drive transmission portion 36b1, it may also be a portion where there is point contact. In that case, the frictional resistance caused by contact between the protrusion 37c and the small diameter portion 36d is further reduced, and the rotational force (driving force) is efficiently transmitted from the relay member 37 to the drive coupling 36.

[0058] <Comparative Example 4> As shown in Figure 20, the drive device 30 in variant example 4 is configured so that the claw portion 36b of the drive coupling 36 can be used as a drive transmission portion 36b2 on the side surface on one end side in the rotation direction in addition to the drive transmission portion 36b1 on the side surface on the other end side in the rotation direction. That is, when the drive device 30 (drive motor) is rotated forward, the drive is transmitted from the drive coupling 36 to the driven coupling 26 via the drive transmission portion 36b1 on one end side of the claw portion 36b in the rotation direction, and when the drive device 30 (drive motor) is rotated backward, the drive is transmitted from the drive coupling 36 to the driven coupling 26 via the drive transmission portion 36b2 on the other end side of the claw portion 36b in the rotation direction. In other words, the drive is normally transmitted from the drive coupling 36 to the driven coupling 26 both during forward rotation and reverse rotation. Similarly, the relationship between the relay member 37 and the drive coupling 36 is configured so that the drive is normally transmitted from the relay member 37 to the drive coupling 36 both during forward rotation and reverse rotation. With this configuration, the fixing device 20 (detachable unit) can be driven forward and backward by the driving device 30, and the operating modes of the fixing device 20 are expanded.

[0059] <Comparative Example 5> 21, in the driving device 30 of the fifth modification, the drive coupling 36 has two claw portions 36b and the relay member 37 has two protrusions 37c instead of three. Additionally, although not shown in the drawings, the driven coupling 26 also has two claw portions 26b. Furthermore, the two claws 36b of the drive coupling 36 are arranged at positions offset by 180° in the rotational direction, and the two protrusions 37c of the relay member 37 are also arranged at positions offset by 180° in the rotational direction. Furthermore, the two claws 36b of the drive coupling 36 and the two protrusions 37c of the relay member 37 are positioned such that they are out of phase with each other by 180° in the rotational direction. Even with the drive device 30 configured in this manner, the drive device 30 does not become larger or more expensive, and poor fitting between the drive coupling 36 and the driven coupling 26 is less likely to occur.

[0060] As described above, the drive device 30 in this embodiment drives the fixing device 20 (detachable unit) that is detachably mounted to the image forming apparatus main body 100 (apparatus main body). The drive device 30 is provided with a drive coupling 36 that moves toward and away from the driven coupling 26 of the fixing device 20 in response to the mounting and dismounting of the fixing device 20 relative to the image forming apparatus main body 100. The relay member 37, which transmits the rotational force of the rotating shaft 35 to the drive coupling 36 so that the drive coupling 36 rotates together with the rotating shaft 35, is fixed to the rotating shaft 35 and inserted into a hole 36a of the drive coupling 36. The compression spring 38 is wound around the rotating shaft 35. One axial end of the compression spring 38 contacts a bearing 34 (abutment member) that is located farther from the driven coupling 26 than the relay member 37, and the other axial end of the compression spring 38 contacts the relay member 37. The drive coupling 36 is configured to be biased by the compression spring 38 toward the other axial end when moved toward one axial end relative to the relay member 37, and is provided with an outer periphery limiting portion 36c that faces the outer periphery of the compression spring 38 and limits radial movement of the compression spring 38. The relay member 37 is also provided with an inner periphery limiting portion 37e that faces the inner periphery of the compression spring 38 and limits radial movement of the compression spring 38. This prevents the drive device 30 from becoming larger and more expensive, and reduces the likelihood of poor fitting between the drive coupling 36 and the driven coupling 26.

[0061] In this embodiment, the bearing 34 is used as the abutting member with which one axial end of the compression spring 38 comes into contact, but the abutting member is not limited to this, and for example, a retaining ring or the like can also be used. Furthermore, in this embodiment, the fixing device 20 is used as the removable unit to which the present invention is applied, but the removable unit to which the present invention is applied is not limited to this, and the present invention can naturally be applied to, for example, a drive device that drives the process cartridges 6Y, 6M, 6C, and 6K (see Figures 1 and 2) as removable units. Furthermore, in this embodiment, the image forming device main body 100 is used as the device main body to which the present invention is applied, but the device main body to which the present invention is applied is not limited to this, and the present invention can naturally also be applied to a drive unit installed in the device main body of equipment other than an image forming device. Even in such cases, the same effects as those of this embodiment can be obtained.

[0062] It is to be noted that the present invention is not limited to the present embodiment, and it is clear that the present embodiment can be appropriately modified within the scope of the technical concept of the present invention in addition to the modifications suggested in the present embodiment. Furthermore, the number, position, shape, etc. of the components are not limited to the present embodiment, and the number, position, shape, etc. of the components can be any number, position, shape, etc. that is suitable for implementing the present invention.

[0063] (Addendum) (Appendix 1) A drive device that drives a detachable unit that is detachably installed in a device main body, a drive coupling that moves toward and away from a driven coupling of the detachable unit in association with an attachment / detachment operation of the detachable unit with respect to the apparatus main body; an intermediate member fixed to the rotary shaft so as to be inserted into the hole of the drive coupling, and transmitting a rotational force of the rotary shaft to the drive coupling so that the drive coupling rotates together with the rotary shaft; a compression spring wound around the rotary shaft, one axial end of which contacts an abutment member located farther from the driven coupling than the relay member, and the other axial end of which contacts the relay member; Equipped with the drive coupling is configured to be biased by the compression spring toward the other axial end when the drive coupling moves toward the one axial end with respect to the relay member, and includes an outer periphery limiting portion that faces an outer periphery of the compression spring and limits radial movement of the compression spring, The drive device is characterized in that the relay member has an inner periphery limiting portion that faces the inner periphery of the compression spring and limits radial movement of the compression spring. (Appendix 2) 2. The drive device according to claim 1, wherein when the drive coupling is engaged with the driven coupling and drive power can be transmitted from the drive coupling to the driven coupling, the compression spring comes into contact with the contact portion of the relay member without coming into contact with the drive coupling. (Appendix 3) 3. The drive device according to claim 2, wherein the contact portion of the relay member is divided into three or more portions in the circumferential direction around the rotation axis. (Appendix 4) The drive device described in any one of Supplementary Note 1 to Supplementary Note 3, characterized in that the outer peripheral limiting portion of the drive coupling is formed circumferentially in the hole portion so as to cover the other axial end side of the compression spring. (Appendix 5) The drive device described in Appendix 4, wherein the outer circumferential limiting portion is formed so that its axial one end side has an inner diameter that gradually increases from the axial other end side toward the axial one end side. (Appendix 6) 6. The drive device according to any one of claims 1 to 5, wherein the relay member includes a stopper portion that restricts movement of the drive coupling toward the other end in the axial direction. (Appendix 7) The drive device according to any one of Supplementary Note 1 to Supplementary Note 6, wherein a distance from a second drive transmission section, where the drive coupling and the driven coupling come into contact, to the axial center of the rotating shaft is longer than a distance from a first drive transmission section, where the relay member and the drive coupling come into contact, to the axial center of the rotating shaft. (Appendix 8) The drive device described in Appendix 7, characterized in that the first drive transmission part and the second drive transmission part are each formed in equal numbers of three or more radially around the rotation axis. (Appendix 9) The drive device described in Appendix 8, wherein, when viewed in the axial direction, a first imaginary polygon circumferentially connecting the plurality of first drive transmission parts and a second imaginary polygon circumferentially connecting the plurality of second drive transmission parts are similar in shape. (Appendix 10) 10. The drive device according to claim 9, wherein the first imaginary polygon and the second imaginary polygon are in a positional relationship rotated by 180 degrees when viewed in the axial direction. (Appendix 11) the first drive transmission portion is a portion where the relay member and the drive coupling make line contact or point contact, The drive device according to any one of Supplementary Note 7 to Supplementary Note 10, wherein the second drive transmission portion is a portion where the drive coupling and the driven coupling come into line contact or point contact. (Appendix 12) The drive device described in any one of Supplementary Note 1 to Supplementary Note 11, characterized in that the drive coupling is configured to be biased toward the other axial end by the compression spring when it moves toward one axial end relative to the relay member by more than a predetermined distance. (Appendix 13) 13. An image forming apparatus, wherein the driving device according to any one of Supplementary Notes 1 to 12 is installed in an image forming apparatus main body as the apparatus main body. [Explanation of symbols]

[0064] 20 Fixing device (detachable unit), 26 driven coupling, 27 gear section, 30 drive unit, 31 drive motor, 33 gears, 34 Bearing (contact member), 35 rotation axis, 36 drive coupling, 36a Hole (inner diameter), 36b Claw part, 36b1 second drive transmission part; 36c outer circumferential limiting portion, 36d small diameter section, 37 relay members, 37b stopper part, 37c protrusion, 37c1 first drive transmission part, 37d contact part, 37e inner circumference limiting portion; 37f tapered section, 38 compression springs, 100 Image forming apparatus (image forming apparatus main body, apparatus main body), A: Second imaginary polygon, B: First imaginary polygon. [Prior art documents] [Patent documents]

[0065] [Patent Document 1] Patent No. 6504449

Claims

1. A drive device that drives a detachable unit that is detachably installed in a device main body, a drive coupling that moves toward and away from a driven coupling of the detachable unit in association with an attachment / detachment operation of the detachable unit with respect to the apparatus main body; an intermediate member fixed to the rotary shaft so as to be inserted into the hole of the drive coupling, and transmitting a rotational force of the rotary shaft to the drive coupling so that the drive coupling rotates together with the rotary shaft; a compression spring wound around the rotary shaft, one axial end of which contacts an abutment member located farther from the driven coupling than the relay member, and the other axial end of which contacts the relay member; Equipped with the drive coupling is configured to be biased toward the other axial end by the compression spring when the drive coupling moves toward one axial end with respect to the relay member, and is provided with an outer periphery limiting portion that faces an outer periphery of the compression spring and limits radial movement of the compression spring.

2. 2. The drive device according to claim 1, wherein when the drive coupling is engaged with the driven coupling and drive power can be transmitted from the drive coupling to the driven coupling, the compression spring comes into contact with the contact portion of the relay member without coming into contact with the drive coupling.

3. 3. The drive unit according to claim 2, wherein the contact portion of the relay member is divided into three or more portions in the circumferential direction around the rotation axis.

4. The drive device according to any one of claims 1 to 3, characterized in that the outer peripheral limiting portion of the drive coupling is formed circumferentially in the hole portion so as to cover the other axial end side of the compression spring.

5. 5. The drive device according to claim 4, wherein the outer peripheral limiting portion is formed such that the inner diameter of one axial end thereof gradually increases from the other axial end toward the one axial end.

6. 6. The drive device according to claim 1, wherein the relay member includes a stopper portion that restricts movement of the drive coupling toward the other end in the axial direction.

7. 7. The drive device according to claim 1, wherein a distance from a second drive transmission portion, where the drive coupling and the driven coupling come into contact, to the axial center of the rotation shaft is longer than a distance from a first drive transmission portion, where the relay member and the drive coupling come into contact, to the axial center of the rotation shaft.

8. The drive device according to claim 7 , wherein the first drive transmission parts and the second drive transmission parts are each formed in equal numbers of three or more radially around the rotation shaft.

9. 9. The drive device according to claim 8, wherein, when viewed in the axial direction, a first imaginary polygon circumferentially connecting the plurality of first drive transmission parts and a second imaginary polygon circumferentially connecting the plurality of second drive transmission parts are similar in shape.

10. 10. The drive device according to claim 9, wherein the first imaginary polygon and the second imaginary polygon are in a positional relationship rotated by 180 degrees when viewed in the axial direction.

11. the first drive transmission portion is a portion where the relay member and the drive coupling make line contact or point contact, The drive device according to any one of claims 7 to 10, wherein the second drive transmission portion is a portion where the drive coupling and the driven coupling make line contact or point contact.

12. The drive device according to any one of claims 1 to 11, characterized in that the drive coupling is configured to be biased toward the other axial end by the compression spring when the drive coupling moves toward one axial end relative to the relay member by more than a predetermined distance.

13. 13. An image forming apparatus, wherein the driving device according to claim 1 is installed in a main body of the image forming apparatus as the main body of the apparatus.

Images