Rotating device, fixing device, and image forming apparatus

Abstract

To prevent a variation in torque generated in a first rotating body when a second rotating body moves from a contact position to a separated position.SOLUTION: A rotating device comprises: a first rotating body that is rotatable in a predetermined rotation direction; a second rotating body that is movable to a contact position where it is in contact with an outer peripheral surface of the first rotating body and a separated position where it is separated from the first rotating body to the radial outside of the first rotating body, and is rotatable in the direction opposite to the rotation direction; a first driving mechanism that drives to rotate the first rotating body at a first peripheral speed, and causes the second rotating body to be rotated at the contact position; and a second driving mechanism that generates a driving force in the opposite direction for the second rotating body at the contact position and the separated position, to drive to rotate the second rotating body at a second peripheral speed slower than the first peripheral speed at the separated position and to apply a resistance force in the opposite direction to the first rotating body through the second rotating body at the contact position.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to a rotating device, a fixing device, and an image forming apparatus. [Background technology]

[0002] Patent Document 1 discloses a medium transport device comprising: an impression drum having a cylindrical shape, which rotates about a central axis to rotate and transport a medium supported on its peripheral surface, a fixed member for fixing an end of the medium in the transport direction over a length corresponding to the entire width of the medium supported on the peripheral surface in the direction approximately perpendicular to the transport direction, and a cam portion having a height greater than the height of the fixed member and a structure protruding from the peripheral surface on each of the outer sides of both ends of the fixed member in the direction approximately perpendicular to the transport direction; and a contact member having a length that exceeds the distance between one cam portion and the other cam portion in the direction approximately perpendicular to the transport direction, which is biased so as to contact the medium supported on the peripheral surface of the impression drum, but has a structure that rides up on the cam portion so as not to come into contact with the fixed member, wherein the impression drum comprises a first magnetic field generating unit that generates a predetermined magnetic field at least at a position on the peripheral surface where the contact member that rides up on the cam portion lands, and the contact member comprises a second magnetic field generating unit that generates a magnetic field that generates a repulsive force against the magnetic field generated by the first magnetic field generating unit.

[0003] Patent Document 2 discloses a fixing device having a fixing rotor equipped with a heat source and a pressure rotor arranged in pressure contact with the fixing rotor, in which a recording medium carrying a toner image to be fixed is introduced and passed through a pressure contact section formed between the fixing rotor and the pressure rotor with the toner image carrying surface facing the fixing rotor. The fixing device is characterized in that it is provided with a speed change means for changing a set value related to the rotational drive speed of the fixing rotor or pressure rotor from a fixing speed value to a slower low speed value before the rear end of the recording medium leaves the pressure contact section, and the speed change means is a means for changing the set value from the fixing speed value to the low speed value at a time when the condition L≧2 / D is satisfied, where D is the width of the pressure contact section in the direction in which the recording medium passes and L is the distance from the exit end of the pressure contact section to the distance until the rear end of the recording medium reaches the exit end of the pressure contact section. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-184189 A [Patent Document 2] JP 2007-183682 A Summary of the Invention [Problem to be solved by the invention]

[0005] The rotating device is: A first rotating body that is rotatable in a predetermined rotation direction; a second rotating body that is movable between a contact position in contact with an outer circumferential surface of the first rotating body and a spaced position spaced from the outer circumferential surface toward the radially outer side of the first rotating body and that is rotatable in a direction opposite to the rotation direction; a first drive mechanism that rotationally drives the first rotor and drives the second rotor to rotate at the contact position; a second drive mechanism that generates a drive force in the reverse direction on the second rotor at the contact position and the separated position, rotationally drives the second rotor at the separated position, and constantly applies a rotational force in the rotation direction to the first rotor via the second rotor at the contact position; A rotating device comprising: In this rotating device, the second driving mechanism constantly applies a rotational force in the rotational direction to the first rotating body via the second rotating body at the contact position, so that when the second rotating body moves from the contact position to the separated position, the torque generated in the first rotating body fluctuates greatly.

[0006] The present disclosure relates to A first rotating body that is rotatable in a predetermined rotation direction; a second rotating body that is movable between a contact position in contact with an outer circumferential surface of the first rotating body and a spaced position spaced from the outer circumferential surface toward the radially outer side of the first rotating body and that is rotatable in a direction opposite to the rotation direction; a first drive mechanism that rotationally drives the first rotor and drives the second rotor to rotate at the contact position; a second drive mechanism that generates a drive force in the reverse direction on the second rotor at the contact position and the separated position, and rotationally drives the second rotor at the separated position; A rotating device comprising: The object of the present invention is to suppress fluctuations in torque generated in the first rotating body when the second rotating body moves from the contact position to the separated position, compared to a case in which the second driving mechanism constantly applies a rotational force in the rotational direction to the first rotating body via the second rotating body at the contact position. [Means for solving the problem]

[0007] The first aspect includes a first rotating body rotatable in a predetermined rotational direction, a second rotating body movable between a contact position in contact with an outer peripheral surface of the first rotating body and a separation position separated radially outward from the first rotating body and rotatable in a direction opposite to the rotational direction, a first drive mechanism that rotationally drives the first rotating body at a first circumferential speed and causes the second rotating body to rotate in the contact position, and a second drive mechanism that generates a drive force in the reverse direction on the second rotating body at the contact position and the separation position, rotationally drives the second rotating body at a second circumferential speed slower than the first circumferential speed at the separation position, and applies a resistance force in the reverse direction to the first rotating body via the second rotating body at the contact position.

[0008] In a second aspect, in the first aspect, the second drive mechanism has a third rotor that rotates in contact with the second rotor to rotate the second rotor.

[0009] In a third aspect, in the second aspect, the third rotating body moves integrally with the second rotating body while maintaining a state of contact with the second rotating body moving between the contact position and the separated position.

[0010] In a fourth aspect, in the second aspect, the third rotor heats the second rotor.

[0011] In a fifth aspect, in the first aspect, the second driving mechanism applies a rotational force in the rotational direction to the first rotating body via the second rotating body at the contact position, and then applies a resistance force in the opposite direction to the first rotating body via the second rotating body before moving to the separated position.

[0012] In a sixth aspect, in the fifth aspect, the second driving mechanism drives the second rotating body to rotate at the second circumferential speed in the separated position, and then drives it to rotate at a third circumferential speed faster than the first circumferential speed before moving to the contact position.

[0013] In a seventh aspect, in the first aspect, a recess is formed on the outer peripheral surface of the first rotating body, and the second rotating body is located in the separated position at a rotational position of the first rotating body facing the recess.

[0014] In an eighth aspect, in the seventh aspect, a recording medium is sandwiched between the first rotating body and the second rotating body, and an image on the recording medium is fixed onto the recording medium.

[0015] A ninth aspect includes a rotating section to which a holding section for holding a recording medium is attached and which is wrapped around the first rotating body and rotates with the rotation of the first rotating body to transport the recording medium, a transfer body around which the rotating section is wrapped and which transfers an image to the recording medium transported by the orbiting section, and a fixing device according to the first aspect which fixes the image transferred by the transfer body onto the recording medium. Effect of the Invention

[0016] According to the configuration of the first aspect, the fluctuation in torque generated in the first rotating body is suppressed when the second rotating body moves from the contact position to the separated position, compared to when the second driving mechanism applies a rotational force in the rotational direction to the first rotating body via the second rotating body at the contact position.

[0017] According to the configuration of the second aspect, the configuration around the rotation shaft of the second rotor is simplified, compared to a case in which the second drive mechanism directly drives and rotates the second rotor.

[0018] According to the configuration of the third aspect, fluctuations in the rotation speed of the second rotor are suppressed compared to when the third rotor is moving away from the second rotor that comes into contact with and moves away from the second rotor.

[0019] According to the configuration of the fourth aspect, the number of parts is reduced compared to the case where the second rotating body is heated by a heating means separate from the third rotating body.

[0020] According to the configuration of the fifth aspect, the torque generated in the first rotating body when the second rotating body is located at the contact position is smaller than when the second driving mechanism always applies a resistance force in the opposite direction to the first rotating body via the second rotating body at the contact position.

[0021] According to the configuration of the sixth aspect, the torque generated in the first rotating body when the second rotating body moves from the separated position to the contact position is smaller than when the second driving mechanism always drives and rotates the second rotating body at the second circumferential speed in the separated position.

[0022] According to the configuration of the seventh aspect, vibrations caused by steps in the recesses of the second rotating body and collisions with contents when the contents are placed in the recesses are suppressed compared to when the second rotating body is positioned in a separated position only at the rotational position of the first rotating body where the part of the outer surface of the first rotating body other than the recesses faces.

[0023] According to the configuration of the eighth aspect, vibration of the fixing device is suppressed compared to a case in which the second driving mechanism imparts a rotational force in the rotation direction to the first rotating body via the second rotating body at the contact position.

[0024] According to the configuration of the ninth aspect, transfer defects are suppressed compared to a case in which the second driving mechanism imparts a rotational force in the rotation direction to the first rotating body at the contact position via the second rotating body. [Brief description of the drawings]

[0025] [Figure 1] 1 is a schematic diagram illustrating an image forming apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view showing a configuration around a transfer cylinder according to the embodiment. [Diagram 3] FIG. 2 is a perspective view showing a configuration around a fixing cylinder according to the embodiment. [Figure 4] FIG. 2 is a perspective view showing a gripper according to the embodiment. [Diagram 5] 2 is a side view showing a fixing cylinder, a heating roll, a pair of external heating rolls, a first driving mechanism, and a second driving mechanism according to the embodiment; FIG. [Figure 6] 6 is a side view showing a state in which the fixing cylinder and the heating roll are separated from each other in the configuration shown in FIG. 5. FIG. [Figure 7] 2 is a schematic diagram showing a fixing cylinder, a heating roll, and a pair of external heating rolls according to the present embodiment. FIG. [Figure 8] 8 is a schematic diagram showing a state in which a fixing cylinder and a heating roll are separated from each other in the configuration shown in FIG. 7. [Figure 9] 8 is a schematic diagram showing a state in which a recording medium is sandwiched between a fixing cylinder and a heating roll in the configuration shown in FIG. 7. [Figure 10] FIG. 4 is a side view showing the peripheral speeds of a fixing cylinder and a heating roll according to the embodiment. [Figure 11] 11 is a schematic diagram showing a contact state between a fixing cylinder and a heating roll in the configuration shown in FIG. 10. [Figure 12] 6 is a graph showing torque generated in a fixing cylinder according to the present embodiment. [Figure 13] 11 is a side view showing an example in which the peripheral speed of the heating roll is faster than the peripheral speed of the fixing cylinder. FIG. [Figure 14] 14 is a schematic diagram showing a contact state between a fixing cylinder and a heating roll in the configuration shown in FIG. 13. [Figure 15] 14 is a graph showing torque generated on a fuser cylinder in the configuration shown in FIG. 13. [Figure 16] 11 is a side view showing an example in which the peripheral speed of the heating roll and the peripheral speed of the fixing cylinder are the same. FIG. [Figure 17] 17 is a schematic diagram showing a contact state between a fixing cylinder and a heating roll in the configuration shown in FIG. 16. [Figure 18] 17 is a graph showing torque generated on a fuser cylinder in the configuration shown in FIG. 16. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

[0027] <Image forming apparatus 10> The configuration of an image forming apparatus 10 according to this embodiment will be described. Fig. 1 is a schematic diagram showing the configuration of an image forming apparatus 10 according to this embodiment. Note that the arrow H shown in each figure indicates the vertical direction, which is the up-down direction of the apparatus, the arrow W indicates the horizontal direction, which is the width direction of the apparatus, and the arrow D indicates the horizontal direction, which is the depth direction of the apparatus (the front-rear direction of the apparatus). The dimensional ratios of the parts shown in each figure in the H direction, W direction, and D direction may differ from the actual dimensional ratios.

[0028] 1 is an image forming apparatus that forms a toner image (one example of an image) on a recording medium P. Specifically, the image forming apparatus 10 includes an image forming section 12, a fixing device 15, and a conveying mechanism 16. Each section of the image forming apparatus 10 (the image forming section 12, the fixing device 15, and the conveying mechanism 16) will be described below.

[0029] <Image forming unit 12> The image forming unit 12 is a component that forms a toner image on the recording medium P by an electrophotographic method. Specifically, as shown in Fig. 1, the image forming unit 12 has a toner image forming unit 20 that forms a toner image, and a transfer device 13 that transfers the toner image formed in the toner image forming unit 20 onto the recording medium P.

[0030] <Toner image forming unit 20> A plurality of toner image forming units 20 shown in Fig. 1 are provided so as to form toner images for each color. In this embodiment, toner image forming units 20 for a total of four colors, yellow (Y), magenta (M), cyan (C), and black (K), are provided. (Y), (M), (C), and (K) shown in Fig. 1 indicate components corresponding to the above-mentioned respective colors.

[0031] In addition, since the toner image forming units 20 of each color are configured in the same manner except for the toner used, in FIG. 1, the respective parts of the toner image forming unit 20(K) are denoted by reference numerals as a representative of the toner image forming units 20 of each color.

[0032] Specifically, each of the toner image forming units 20 for each color has a photoconductor 22 that rotates in one direction (for example, the counterclockwise direction in FIG. 1). Each of the toner image forming units 20 for each color also has a charger 23, an exposure device 24, and a developing device 25.

[0033] In the toner image forming unit 20 for each color, the charger 23 charges the photoconductor 22. Furthermore, the exposure device 24 exposes the photoconductor 22 charged by the charger 23 to light, thereby forming an electrostatic latent image on the photoconductor 22. Furthermore, the development device 25 develops the electrostatic latent image formed on the photoconductor 22 by the exposure device 24, thereby forming a toner image.

[0034] <Transfer device 13> The transfer device 13 shown in Fig. 1 is a device that transfers a toner image formed in the toner image forming unit 20 onto a recording medium P. Specifically, the transfer device 13 performs primary transfer of the toner images of the photoconductors 22 of each color onto a transfer belt 30 serving as an intermediate transfer body, and performs secondary transfer of the superposed toner images onto the recording medium P. As shown in Fig. 1, the transfer device 13 includes the transfer belt 30, a primary transfer roll 32, and a transfer cylinder 40. The transfer cylinder 40 is an example of a transfer body.

[0035] The primary transfer roll 32 is a roll that transfers the toner image of each color of the photoconductor 22 to the transfer belt 30 at a primary transfer position T1 between the photoconductor 22 and the primary transfer roll 32. In this embodiment, a primary transfer electric field is applied between the primary transfer roll 32 and the photoconductor 22, so that the toner image formed on the photoconductor 22 is transferred to the transfer belt 30 at the primary transfer position T1.

[0036] The toner image is transferred from the photoconductor 22 of each color to the outer peripheral surface of the transfer belt 30. As shown in Fig. 1, the transfer belt 30 is endless and is wound around a plurality of rolls 33 and an opposing roll 34 so as to assume an inverted triangular posture when viewed from the front (when viewed in the depth direction of the device). The transfer belt 30 rotates in the direction of arrow A when at least one of the plurality of rolls 33 is driven to rotate.

[0037] The transfer cylinder 40 has a function of transferring the toner image transferred onto the transfer belt 30 onto a recording medium P. As shown in Figures 1 and 2, this transfer cylinder 40 (specifically, a cylinder main body 42 described below) has a recess 41 formed on an outer circumferential surface 40A, and rotates in a rotation direction B. The recess 41 is elongated along the axial direction of the transfer cylinder 40, and has a depth along the radial direction of the transfer cylinder 40.

[0038] 1, the transfer cylinder 40 is disposed below the transfer belt 30 so as to face the transfer belt 30. Furthermore, the transfer cylinder 40 contacts the transfer belt 30 in the range of the outer peripheral surface 40A from the upstream end to the downstream end of the recess 41 in the rotation direction.

[0039] 2, the transfer cylinder 40 is provided with a pair of sprockets 64 on both axial ends. Specifically, the transfer cylinder 40 is configured to have a substantially cylindrical cylinder main body 42 and a pair of sprockets 64 provided on both axial ends of the cylinder main body 42. The pair of sprockets 64 are arranged coaxially on the cylinder main body 42.

[0040] In the transfer cylinder 40, the cylinder main body 42 is rotated in a rotational direction B by a drive unit (not shown), so that the cylinder main body 42 and the pair of sprockets 64 rotate in the rotational direction B together.

[0041] In this embodiment, the transfer belt 30 and the transfer cylinder 40 (specifically, the cylinder main body 42) convey the recording medium P in a sandwiched state at the secondary transfer position T2 (see FIG. 1). Then, the transfer cylinder 40 transfers the toner image transferred onto the transfer belt 30 to the recording medium P at the secondary transfer position T2 by applying a secondary transfer electric field between the opposing roll 34 and the transfer cylinder 40. Note that a gripper 60 and an attachment member 63 (described below) that hold the recording medium P are accommodated in a recess 41 when passing through the secondary transfer position T2, and are prevented from coming into contact with the transfer belt 30.

[0042] <Fixing device 15> Fixing device 15 is an example of a rotating device, and is a device that fixes a toner image transferred to recording medium P by transfer cylinder 40 to the recording medium P. Specifically, fixing device 15 has a fixing cylinder 50, a heating roll 52, and a pair of external heating rolls 54, as shown in Fig. 1. Furthermore, fixing device 15 has a first driving mechanism 70 and a second driving mechanism 80, as shown in Figs. 5 and 6. Fixing cylinder 50 is an example of a first rotating body, and heating roll 52 is an example of a second rotating body.

[0043] 7, 8, and 9, in the fixing device 15, the heating roll 52 is disposed above the fixing cylinder 50. The fixing cylinder 50 has a larger diameter than the heating roll 52 and a larger mass (i.e., moment of inertia) than the heating roll 52. The heating roll 52 is in contact with a pair of external heating rolls 54 and is heated by the pair of external heating rolls 54.

[0044] The fixing cylinder 50 is a rotating body that can rotate in a rotation direction E. The fixing cylinder 50 (specifically, a cylinder main body 53 described later) has a recess 51 formed on an outer peripheral surface 50A, and is rotated in the rotation direction E by a first drive mechanism 70 (see Figs. 5 and 6). The rotation direction E is an example of a predetermined rotation direction. The recess 51 is provided in a part of the circumferential direction on the outer peripheral surface of the fixing cylinder 50. Furthermore, the recess 51 is elongated along the axial direction of the fixing cylinder 50 and has a depth along the radial direction of the fixing cylinder 50. The recess 51 accommodates a gripper 60 and an attachment member 63 described later. This prevents the gripper 60 and the attachment member 63 from coming into contact with the heating roll 52 when passing through the fixing position NP.

[0045] As shown in Fig. 3, the fixing cylinder 50 is provided with a pair of sprockets 65 on both axial ends. Specifically, the fixing cylinder 50 is configured to have a substantially cylindrical cylinder main body 53 and sprockets 65 provided on both axial ends of the cylinder main body 53. The pair of sprockets 65 are arranged coaxially on the cylinder main body 53. When the cylinder main body 53 is rotationally driven by a first drive mechanism 70 (see Figs. 5 and 6) to rotate in a rotational direction E, the fixing cylinder 50 rotates integrally with the cylinder main body 53 and the pair of sprockets 65 in the rotational direction E.

[0046] The heating roll 52 is a rotating body that can rotate in a rotation direction F (clockwise direction in FIG. 7) that is the opposite direction to the rotation direction E (counterclockwise direction in FIG. 7). The heating roll 52 can move between a contact position (position shown in FIGS. 5 and 7) where it contacts the outer circumferential surface of the fixing cylinder 50, and a separated position (position shown in FIGS. 6 and 8) where it is separated from the fixing cylinder 50 toward the radially outer side of the fixing cylinder 50. In this embodiment, the heating roll 52 rotates in the forward direction (rotation direction F) relative to the rotation of the fixing cylinder 50 at the contact position. The rotation direction F is an example of the reverse direction.

[0047] In this embodiment, the heating roll 52 and a pair of external heating rolls 54 are supported by a support 58, and the heating roll 52 moves together with the pair of external heating rolls 54 between a contact position (position shown in Figures 5 and 7) and a separated position (position shown in Figures 6 and 8) by a moving mechanism using a cam or the like.

[0048] The moving mechanism positions the heating roll 52 at a contact position at a rotational position where a contact area 56 (see FIG. 7) on the fixing cylinder 50 faces the heating roll 52. At the contact position, the heating roll 52 and the fixing cylinder 50 are in contact with each other (hereinafter, referred to as a contact state). The contact area 56 (see FIG. 7) is the range of the outer circumferential surface 50A from the upstream end 51A to the downstream end 51B of the recess 51. It is not necessary for the contact area 56 (see FIG. 7) on the fixing cylinder 50 to be in contact with the heating roll 52 over the entire rotational position.

[0049] The moving mechanism positions the heating roll 52 at a separation position at a rotation position where the recessed portion 51 in the fixing cylinder 50 faces the heating roll 52. At the separation position, the heating roll 52 and the fixing cylinder 50 are separated from each other (hereinafter, referred to as the separation state). Note that the separation state does not need to be established over the entire rotation position where the recessed portion 51 in the fixing cylinder 50 faces the heating roll 52.

[0050] In the contact state, the heating roll 52 comes into contact with the contact area 56, and sandwiches the recording medium P between the heating roll 52 and the fixing cylinder 50, as shown in Fig. 9. Note that the heating roll 52 does not need to come into contact with the entire contact area 56, and it is sufficient that the heating roll 52 comes into contact with at least a part of the contact area 56.

[0051] Then, in the fixing device 15, while the recording medium P is conveyed in a state in which it is sandwiched between the heating roll 52 and the fixing cylinder 50 at the fixing position NP, the heating roll 52 heats the recording medium P, and the heating roll 52 and the fixing cylinder 50 press the recording medium P, thereby fixing the toner image transferred to the recording medium P to the recording medium P. The first driving mechanism 70 and the second driving mechanism 80 will be described later.

[0052] <Transport mechanism 16> 1 is a mechanism for transporting a recording medium P. The transport mechanism 16 has a pair of chains 66 and a gripper 60, as shown in FIGS.

[0053] The chain 66 is an example of a rotation portion, and the gripper 60 is an example of a holding portion. Note that, in Fig. 1, only one of the pair of chains 66 is shown, and the chain 66 and the gripper 60 are shown in a simplified manner.

[0054] The pair of chains 66 are formed in a loop as shown in Fig. 1. The pair of chains 66 are arranged at an interval in the apparatus depth direction (direction D in the figure) as shown in Fig. 2. Each of the pair of chains 66 is wound around a pair of sprockets 64 provided on both axial ends of the transfer cylinder 40 and a pair of sprockets 65 (see Fig. 3) provided on both axial ends of the fixing cylinder 50. The transfer cylinder 40 is rotated in a rotation direction B (arrow B direction) and the fixing cylinder 50 is rotated in a rotation direction E, whereby the chain 66 rotates in a rotation direction C (arrow C direction).

[0055] 2, a mounting member 63 to which a gripper 60 is attached is hung between the pair of chains 66 in the device depth direction. A plurality of mounting members 63 are fixed to the pair of chains 66 at predetermined intervals along the circulating direction C of the chains 66.

[0056] As shown in Fig. 2, a plurality of grippers 60 are attached to the attachment member 63 at predetermined intervals along the depth direction of the device. The grippers 60 function as a holder that holds the leading end of the recording medium P. Specifically, as shown in Fig. 4, the gripper 60 has a claw 61 and a claw base 62. The gripper 60 is configured to hold the recording medium P by pinching the leading end of the recording medium P between the claw 61 and the claw base 62. In addition, the gripper 60 has a claw 61 pressed against the claw base 62 by a spring or the like, and the claw 61 opens and closes with respect to the claw base 62 by the action of a cam or the like.

[0057] In the transport mechanism 16, the leading end of the recording medium P sent from a storage unit (not shown) in which the recording medium P is stored is held by a gripper 60 as shown in Fig. 4. The gripper 60 holding the leading end of the recording medium P transports the recording medium P by rotating the chain 66 in the rotation direction C, and passes the secondary transfer position T2. ​​Then, at the secondary transfer position T2, the transfer cylinder 40 secondarily transfers the toner images of each color that have been primarily transferred and superimposed on the transfer belt 30 at the primary transfer position T1, onto the recording medium P at the secondary transfer position T2.

[0058] Furthermore, as the chain 66 rotates in the rotation direction C, the gripper 60 holding the leading end of the recording medium P conveys the recording medium P and passes through the fixing position NP. Then, in the fixing device 15, at the fixing position NP, the heating roll 52 sandwiches the recording medium P between the fixing cylinder 50 and the recording medium P, and the image of the recording medium P is fixed to the recording medium.

[0059] In addition, when gripper 60 passes through secondary transfer position T2, it is accommodated together with mounting member 63 in recess 41 formed on the outer peripheral surface of transfer cylinder 40, and when it passes through fixing position NP, it is accommodated together with mounting member 63 in recess 51 formed on the outer peripheral surface of fixing cylinder 50.

[0060] <First driving mechanism 70 and second driving mechanism 80> 5 and 6 is a mechanism that drives the fixing cylinder 50 to rotate at a first peripheral speed (V1) in the rotation direction E, and rotates the heating roll 52 at the contact position of the heating roll 52 (the position shown in FIG. 11), as shown in FIG. 10 and 11. As shown in FIG. 5 and 6, the first driving mechanism 70 has a driving source 72 constituted by a driving motor or the like, and a transmission unit 74 that transmits the driving force of the driving source 72 to the fixing cylinder 50. The transmission unit 74 is constituted by mechanical elements such as gears, couplings, belts, and pulleys.

[0061] The second driving mechanism 80 shown in Figures 5 and 6 is a mechanism that generates a driving force in the rotation direction F to the heating roll 52 at the contact position of the heating roll 52 (position shown in Figure 11) and at the separated position of the heating roll 52 (position shown in Figure 10).

[0062] The second drive mechanism 80 drives and rotates the heating roll 52 at a second peripheral speed (V2) slower than the first peripheral speed (V1) of the fixing cylinder 50 at the separated position of the heating roll 52 (position shown in FIG. 10). Furthermore, the second drive mechanism 80 applies a resistance force (see arrow XA) in the opposite direction to the rotation direction E to the fixing cylinder 50 via the heating roll 52 at the contact position of the heating roll 52 (position shown in FIG. 11).

[0063] 5 and 6, the second drive mechanism 80 has a drive source 82 constituted by a drive motor or the like, and a transmission unit 84 that transmits the drive force of the drive source 82 to the heating roll 52. The transmission unit 84 is constituted by mechanical elements such as gears, couplings, belts, and pulleys, and a pair of external heating rolls 54. The pair of external heating rolls 54 is an example of a third rotating body.

[0064] In this embodiment, with the pair of external heating rolls 54 in contact with the heating roll 52, the second drive mechanism 80 drives and rotates at least one of the pair of external heating rolls 54 in the rotation direction G, thereby rotating the heating roll 52 in a driven manner. While maintaining a state of contact with the heating roll 52, the pair of external heating rolls 54 move integrally with the heating roll 52, which comes into contact with and separates from the fixing cylinder 50. In this embodiment, the pair of external heating rolls 54, which rotate the heating roll 52 in a driven manner, heat the heating roll 52.

[0065] 5 and 6, the second drive mechanism 80 has a torque limiter 86 that limits the drive force transmitted from the drive source 82 to the heating roll 52. The torque limiter 86 is disposed in the transmission path of the transmission unit 84.

[0066] When the load torque from the fixing cylinder 50 to the heating roll 52 reaches or exceeds a predetermined torque at the contact position of the heating roll 52, the torque limiter 86 cuts off the transmission of the driving force of the drive source 82 to the heating roll 52. This causes the heating roll 52 to rotate following the fixing cylinder 50. At this time, a resistance force (see arrow XA) in the opposite direction to the rotation direction E is applied to the fixing cylinder 50 from the heating roll 52.

[0067] As described above, the torque limiter 86 functions as a limiting section that limits the driving force transmitted from the driving source 82 to the heating roll 52. Instead of the torque limiter 86, a one-way clutch may be used as the limiting section.

[0068] The second drive mechanism 80, together with the heating roll 52 and the pair of external heating rolls 54, is supported by a support 58, and moves, together with the heating roll 52 and the pair of external heating rolls 54, between a contact position (position shown in Figure 5) and a separated position (position shown in Figure 6).

[0069] <Action of this embodiment> In this embodiment, as described above, the second drive mechanism 80 applies a resistance force (see arrow XA) in the opposite direction to the rotation direction E to the fixing cylinder 50 via the heating roll 52 at the contact position of the heating roll 52 (the position shown in Figure 11).

[0070] Here, in the case where the second drive mechanism 80 applies a rotational force (see arrow XB) in the rotation direction E to the fixing cylinder 50 via the heating roll 52 at the contact position of the heating roll 52 as shown in Fig. 14 (hereinafter referred to as form A), when the heating roll 52 moves from the contact position (position shown in Fig. 14) to the separated position (position shown in Fig. 13), the torque (i.e., rotational load) generated in the fixing cylinder 50 varies as shown in Fig. 15. Note that in form A, for example, the second drive mechanism 80 drives the heating roll 52 to rotate at a third peripheral speed (V3) faster than the first peripheral speed (V1) of the fixing cylinder 50 at the separated position of the heating roll 52 (position shown in Fig. 13).

[0071] In form A, a rotational force in the rotation direction E (see arrow XB) is applied to the fixing cylinder 50 at the contact position of the heating roll 52, and the rotational force acts as an assist force that assists the rotation of the fixing cylinder 50, so that the torque generated in the fixing cylinder 50 is reduced. Therefore, as shown in Fig. 15, the torque generated in the fixing cylinder 50 is in a "small" state.

[0072] In the configuration A, when the heating roll 52 moves from the contact position to the separated position, the assist force is lost and a load (hereinafter referred to as a separation load) is generated on the fixing cylinder 50 as the heating roll 52 separates from the fixing cylinder 50. As a result, as shown in Fig. 15, the torque generated on the fixing cylinder 50 becomes "large", and the torque (i.e., the rotation load) generated on the fixing cylinder 50 fluctuates. Note that the separation load is generated, for example, by the heating roll 52 kicking the fixing cylinder 50 when it separates from the fixing cylinder 50.

[0073] Also, in the case where the second drive mechanism 80 does not apply either a rotational force in the rotation direction E (see arrow XB in FIG. 14) or a resistance force in the opposite direction to the rotation direction E (see arrow XA in FIG. 11) to the fixing cylinder 50 via the heating roll 52 at the contact position of the heating roll 52 as shown in FIG. 17 (hereinafter referred to as form B), when the heating roll 52 moves from the contact position (position shown in FIG. 17) to the separated position (position shown in FIG. 16), the torque (i.e., the rotational load) generated in the fixing cylinder 50 fluctuates as shown in FIG. 18. Note that in form B, for example, the second drive mechanism 80 drives the heating roll 52 to rotate at a fourth peripheral speed (V4) that is the same as the first peripheral speed (V1) of the fixing cylinder 50 at the separated position of the heating roll 52 (position shown in FIG. 16).

[0074] In form B, unlike form A, the assist force is not lost when the heating roll 52 moves from the contact position to the separated position. However, a separation load is generated as the heating roll 52 separates from the fixing drum 50. As a result, as shown in FIG. 18, the torque generated in the fixing drum 50 changes from "medium" to "large," and the torque (i.e., the rotational load) generated in the fixing drum 50 fluctuates.

[0075] When the torque (i.e., the rotational load) generated in the fixing drum 50 fluctuates, as in forms A and B, the vibration caused by the fluctuation is transmitted to the transfer belt 30 via the chain 66 and the transfer drum 40, which may result in poor transfer or image distortion in the toner image forming section 20.

[0076] In contrast, in this embodiment, at the contact position of the heating roll 52, a resistance force (see arrow XA) in the opposite direction to the rotational direction E is applied to the fixing cylinder 50, so that when the heating roll 52 moves from the contact position to the separated position, this resistance force is lost and a separation load is generated as the heating roll 52 separates from the fixing cylinder 50.

[0077] As a result, the decrease in torque due to the loss of the resistance force and the increase in torque due to the generation of the separation load are offset, and as shown in Figure 12, the torque fluctuation generated in the fixing drum 50 when the heating roll 52 moves from the contact position to the separation position is suppressed compared to configurations A and B.

[0078] In this manner, the torque fluctuation occurring in the fixing cylinder 50 is suppressed, thereby suppressing the vibration of the fixing device 15 due to the torque fluctuation. Furthermore, the vibration due to the torque fluctuation is less likely to propagate to the transfer belt 30 via the chain 66 and the transfer cylinder 40, so that transfer failure and image disturbance in the toner image forming unit 20 are suppressed.

[0079] In this embodiment, the pair of external heating rolls 54 rotate in a state of contact with the heating roll 52, thereby causing the heating roll 52 to rotate in a driven manner.

[0080] As a result, there is no need for a mechanism for inputting a driving force to the rotation shaft of the heating roll 52, and the configuration around the rotation shaft of the heating roll 52 is simplified compared to when the second driving mechanism 80 directly drives and rotates the heating roll 52.

[0081] In this embodiment, the pair of external heating rolls 54 move integrally with the heating roll 52, which comes into contact with and separates from the fixing cylinder 50, while maintaining a state of contact with the heating roll 52, as described above.

[0082] Therefore, fluctuations in the rotation speed of the heating roll 52 are suppressed compared to when the pair of external heating rolls 54 are separated from the heating roll 52 that makes contact and separates.

[0083] In this embodiment, the pair of external heating rolls 54 which rotate the heating roll 52 , heat the heating roll 52 .

[0084] Therefore, the number of parts is reduced compared to the case where the heating roll 52 is heated by a heating means separate from the roll that rotates the heating roll 52 .

[0085] In this embodiment, the heating roll 52 is located at a separate position at the rotational position of the fixing cylinder 50 facing the recess 51 of the fixing cylinder 50 .

[0086] As a result, vibration of the heating roll 52 due to the step of the recess 51 and collision with the gripper 60 housed in the recess 51 are suppressed compared to when the heating roll 52 is located in a separated position only at the rotational position of the fixing cylinder 50 where the part of the outer surface 50A of the fixing cylinder 50 other than the recess 51 faces.

[0087] <Modifications of the second driving mechanism 80> In this embodiment, as described above, the second drive mechanism 80 applies a resistance force (see arrow XA) in the opposite direction to the rotation direction E to the fixing cylinder 50 via the heating roll 52 at the contact position of the heating roll 52 (the position shown in Figure 11), but it is not necessary to always apply such resistance force at the contact position of the heating roll 52.

[0088] For example, the second drive mechanism 80 may apply a rotational force in the rotational direction E to the fixing cylinder 50 via the heating roll 52 at the contact position of the heating roll 52 (position shown in Figure 11) (see Figure 14), and then apply a resistance force in the opposite direction (see arrow XA) to the fixing cylinder 50 via the heating roll 52 before the heating roll 52 moves to the separated position (see Figure 11).

[0089] According to this configuration, the torque generated in the fixing cylinder 50 when the heating roll 52 is located at the contact position is smaller than when the second drive mechanism 80 always applies a resistance force in the opposite direction to the fixing cylinder 50 via the heating roll 52 at the contact position of the heating roll 52 (the position shown in Figure 11).

[0090] Furthermore, in this embodiment, as described above, the second drive mechanism 80 drives and rotates the heating roll 52 at a second circumferential speed (V2) slower than the first circumferential speed (V1) of the fixing cylinder 50 when the heating roll 52 is separated from the fixing cylinder 50 (the position shown in FIG. 10 ). However, it is not necessary to always drive and rotate the heating roll 52 at the second circumferential speed (V2) when the heating roll 52 is separated from the fixing cylinder 50.

[0091] For example, the second driving mechanism 80 may drive the heating roll 52 to rotate at a second circumferential speed (V2) when the heating roll 52 is in the separated position, and then drive the heating roll 52 to rotate at a third circumferential speed (V3) faster than the first circumferential speed (V1) before the heating roll 52 moves to the contact position (see FIG. 13).

[0092] According to this configuration, the torque generated in the fixing cylinder 50 when the heating roll 52 moves from the separated position to the contact position is smaller than when the second driving mechanism 80 always drives and rotates the heating roll 52 at the second circumferential speed (V2) when the heating roll 52 is in the separated position.

[0093] <Modifications of the first rotating body, the second rotating body, and the third rotating body> In the present embodiment, the fixing cylinder 50 is used as an example of the first rotating body, but is not limited to this. Examples of the first rotating body may include the transfer cylinder 40, a transfer roll, and a transport roll.

[0094] In the present embodiment, the heating roll 52 is used as an example of the second rotating body, but the present invention is not limited to this. Examples of the second rotating body may include, for example, a transfer roll and a transport roll.

[0095] In the present embodiment, the pair of external heating rolls 54 is used as an example of the third rotating body, but the present invention is not limited to this. An example of the third rotating body may be, for example, a roll that does not involve heating.

[0096] <Other Modifications> In the present embodiment, the pair of external heating rolls 54 rotate in contact with the heating roll 52, thereby rotating the heating roll 52, but this is not limited thereto. For example, the second driving mechanism 80 may directly drive and rotate the heating roll 52.

[0097] In addition, in this embodiment, as described above, the pair of external heating rolls 54 move integrally with the heating roll 52 that makes contact with and separates from the fixing cylinder 50 while maintaining a state of contact with the heating roll 52, but this is not limited thereto. A configuration in which the pair of external heating rolls 54 are separated from the heating roll 52 that makes contact with and separates from the fixing cylinder 50 may also be used.

[0098] In the present embodiment, the pair of external heating rolls 54 which rotate the heating roll 52 by following the heating roll 52 heats the heating roll 52, but this is not limited thereto. For example, the heating roll 52 may be heated by a heating means other than the roll which rotates the heating roll 52 by following the heating roll 52.

[0099] In addition, in this embodiment, the gripper 60 and the mounting member 63 are housed in the recess 51 of the fixing cylinder 50, but this is not limited to the above. The recess 51 may be provided for another purpose.

[0100] The present invention is not limited to the above-described embodiment, and various modifications, changes, and improvements are possible without departing from the spirit and scope of the present invention. For example, the above-described modified examples may be combined in combination as appropriate.

[0101] <Additional Notes> (((1))) A first rotating body that is rotatable in a predetermined rotation direction; a second rotor that is movable between a contact position in contact with an outer circumferential surface of the first rotor and a spaced position spaced from the first rotor toward the radially outer side of the first rotor and that is rotatable in a direction opposite to the rotation direction; a first drive mechanism that drives the first rotating body to rotate at a first peripheral speed and drives the second rotating body to rotate at the contact position; a second drive mechanism that generates a driving force in the reverse direction on the second rotor at the contact position and the separation position, rotates the second rotor at a second circumferential speed slower than the first circumferential speed at the separation position, and applies a resistance force in the reverse direction to the first rotor via the second rotor at the contact position; A rotating device comprising:

[0102] (((2))) The second drive mechanism is A third rotor is provided, which rotates in contact with the second rotor to rotate the second rotor. A rotating device as described in (((1))).

[0103] (((3))) The third rotating body moves integrally with the second rotating body while maintaining a state of contact with the second rotating body that moves between the contact position and the separated position. A rotating device as described in (((2))).

[0104] (((4))) The third rotating body heats the second rotating body. A rotation device according to (((2))) or (((3))).

[0105] (((5))) The second drive mechanism is At the contact position, a rotational force in the rotation direction is applied to the first rotating body via the second rotating body, and then a resistance force in the opposite direction is applied to the first rotating body via the second rotating body before the first rotating body moves to the separated position. A rotating device according to any one of (((1))) to (((4))).

[0106] (((6))) The second drive mechanism is At the separated position, the second rotating body is rotationally driven at the second peripheral speed, and then, before moving to the contact position, the second rotating body is rotationally driven at a third peripheral speed that is faster than the first peripheral speed. A rotating device as described in (((5))).

[0107] (((7))) A recess is formed on the outer circumferential surface of the first rotating body, The second rotating body is located at the separated position at a rotational position of the first rotating body facing the recess. A rotating device according to any one of (((1))) to (((6))).

[0108] (((8))) A recording medium is sandwiched between the first rotating body and the second rotating body, and an image on the recording medium is fixed onto the recording medium. A fixing device as the rotating device described in (((7))).

[0109] (((9))) a rotation unit to which a holding unit for holding a recording medium is attached and which is wound around the first rotating body and rotates with the rotation of the first rotating body to transport the recording medium; a transfer body around which the rotating part is wound and which transfers an image onto a recording medium transported by the rotating part; a fixing device according to (((8))) that fixes the image transferred by the transfer body onto the recording medium; An image forming apparatus comprising:

[0110] According to the configuration (((1))), fluctuations in torque generated in the first rotating body are suppressed when the second rotating body moves from the contact position to the separated position, compared to when the second driving mechanism applies a rotational force in the rotational direction to the first rotating body via the second rotating body at the contact position.

[0111] According to the configuration (((2))), the configuration around the rotation shaft of the second rotor is simplified compared to a case in which the second drive mechanism directly drives and rotates the second rotor.

[0112] According to the configuration (((3))), fluctuations in the rotation speed of the second rotating body are suppressed compared to when the third rotating body is moving away from the second rotating body that comes into contact with and is moving away from it.

[0113] According to the configuration (((4))), the number of parts is reduced compared to the case where the second rotating body is heated by a heating means separate from the third rotating body.

[0114] According to the configuration (((5))), the torque generated in the first rotating body when the second rotating body is located at the contact position is smaller than when the second driving mechanism always applies a resistance force in the opposite direction to the first rotating body via the second rotating body at the contact position.

[0115] According to the configuration (((6))), the torque generated in the first rotating body when the second rotating body moves from the separated position to the contact position is smaller than when the second driving mechanism constantly drives and rotates the second rotating body at the second circumferential speed in the separated position.

[0116] According to the configuration (((7))), vibrations caused by steps in the recesses of the second rotating body and collisions with contents when the contents are placed in the recesses are suppressed, compared to when the second rotating body is positioned in a separated position only at the rotational position of the first rotating body where the part of the outer surface of the first rotating body other than the recesses faces.

[0117] According to the configuration (((8))), vibration of the fixing device is suppressed compared to a case in which the second driving mechanism applies a rotational force in the rotational direction to the first rotating body via the second rotating body at the contact position.

[0118] According to the configuration (((9))), transfer defects are suppressed compared to a case in which the second drive mechanism applies a rotational force in the rotation direction to the first rotating body via the second rotating body at the contact position. [Explanation of symbols]

[0119] 10 Image forming device 12 Image forming section 13 Transcription device 15 Fixing device (an example of a rotating device) 16 Conveyor mechanism 20 Toner image forming unit 22 Photoreceptor 23 Charger 24 Exposure equipment 25 Developing device 30 Transfer belt 32 Primary transfer roll 33 Rolls 34 Opposing Roll 40 Transfer cylinder (an example of a transfer body) 40A outer surface 41 Recess 42 Body 50 Fixing cylinder (an example of the first rotating body) 50A outer surface 51 Recess 51A Upstream end 51B Downstream end 52 Heating roll (an example of a second rotating body) 53 Body 54 External heating roll (an example of a third rotating body) 56 Contact Range 58 Support 60 Gripper (an example of a holding part) 61 Nails 62 Nail stand 63 Mounting material 64 Sprocket 65 sprocket 66 Chain (an example of a rotating part) 70 First drive mechanism 72 Power Source 74 Transmission section 80 Second drive mechanism 82 Power Source 84 Transmission section 86 Torque limiter P Recording medium

Claims

1. A first rotating body that is rotatable in a predetermined rotation direction; a second rotor that is movable between a contact position in contact with an outer circumferential surface of the first rotor and a spaced position away from the first rotor toward the radially outer side of the first rotor and that is rotatable in a direction opposite to the rotation direction; a first drive mechanism that drives the first rotating body to rotate at a first peripheral speed and drives the second rotating body to rotate at the contact position; a second drive mechanism that generates a driving force in the reverse direction on the second rotor at the contact position and the separation position, rotates the second rotor at a second circumferential speed slower than the first circumferential speed at the separation position, and applies a resistance force in the reverse direction to the first rotor via the second rotor at the contact position; A rotating device comprising:

2. The second drive mechanism is A third rotor is provided, which rotates in contact with the second rotor to rotate the second rotor. The rotating device according to claim 1 .

3. The third rotating body moves integrally with the second rotating body while maintaining a state of contact with the second rotating body that moves between the contact position and the separated position. The rotating device according to claim 2 .

4. The third rotating body heats the second rotating body. The rotating device according to claim 2 .

5. The second drive mechanism is At the contact position, a rotational force in the rotation direction is applied to the first rotating body via the second rotating body, and then a resistance force in the opposite direction is applied to the first rotating body via the second rotating body before the first rotating body moves to the separated position. The rotating device according to claim 1 .

6. The second drive mechanism is At the separated position, the second rotating body is rotationally driven at the second peripheral speed, and then, before moving to the contact position, the second rotating body is rotationally driven at a third peripheral speed that is faster than the first peripheral speed. The rotating device according to claim 5.

7. A recess is formed on the outer circumferential surface of the first rotating body, The second rotating body is located at the separated position at a rotational position of the first rotating body facing the recess. The rotating device according to claim 1 .

8. A recording medium is sandwiched between the first rotating body and the second rotating body, and an image on the recording medium is fixed onto the recording medium. A fixing device as the rotating device according to claim 7.

9. a rotation unit to which a holding unit for holding a recording medium is attached and which is wound around the first rotating body and rotates with the rotation of the first rotating body to transport the recording medium; a transfer body around which the rotating part is wound and which transfers an image onto a recording medium transported by the rotating part; a fixing device according to claim 8 for fixing the image transferred by the transfer body onto the recording medium; An image forming apparatus comprising:

Images