Fixing device and image forming apparatus

Abstract

To suppress influence of image fixation to a recording medium as compared with a case where a rotary member moves in direction advancing / retreating to / from a fixing member by transmitting rotary driving force to the rotary member.SOLUTION: A fixing device 14 includes: a fixing member 53 which is used for fixing of an image on a recording medium; a rotary member 61 which is pressed on the fixing member 53, is rotatably provided and forms a pressurization section N by which the recording medium is pressurized between the rotary member and the fixing member 53, and a transmission section 92 which transmits rotary driving force to the rotary member 61. The rotary member 61 is movable in a direction D advancing / retreating to / from the fixing member 53. The advancing / retreating direction D of the rotary member 61 does not match an application direction of driving force 93 by the transmission section 82.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] For example, Patent Document 1 discloses a fixing device having an endless fixing rotor that heats toner as it rotates and fixes it onto a recording medium, a pressure rotor that sandwiches and pressurizes the toner and recording medium between the fixing rotor, and a support portion that supports the fixing rotor from the inside at a contact portion where the fixing rotor and the pressure rotor come into contact with each other so that the peak pressure on the outlet side of the recording medium is equal to or lower than the peak pressure on the inlet side. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-44257 A Summary of the Invention [Problem to be solved by the invention]

[0004] Here, consider a case where a rotating member is pressed against a fixing member used for fixing an image on a recording medium, forming a pressure section where the recording medium is pressed between the fixing member and the rotating member, and the rotating member is movable in a direction toward and away from the fixing member. When the rotating member moves in a direction toward and away from the fixing member due to a rotational driving force being transmitted to the rotating member, the fixing of the image on the recording medium is affected. The object of the present invention is to suppress the effects of image fixing on the recording medium compared to a case in which a rotational driving force is transmitted to the rotating member, causing the rotating member to move toward and away from the fixing member. [Means for solving the problem]

[0005] The invention described in claim 1 is a fixing device comprising a fixing member used to fix an image on a recording medium, a rotating member that is pressed against the fixing member and rotatably arranged to form a pressure section between the fixing member and the fixing member where pressure is applied to the recording medium, and a transmission section that transmits a rotational driving force to the rotating member, wherein the rotating member is movable in a direction toward and away from the fixing member, and the direction in which the rotating member moves toward and away from the fixing member does not coincide with the direction in which the driving force is applied by the transmission section. The invention described in claim 2 is the fixing device described in claim 1, characterized in that the transmission part is located on the opposite side of the rotating member from the fixing member. The invention described in claim 3 is the fixing device described in claim 1, characterized in that the transmission portion includes a gear that meshes with a spur gear that is coaxial with a rotation shaft of the rotating member. The invention described in claim 4 is the fixing device described in claim 3, characterized in that the gear is provided on a fixed member together with a driving gear that meshes with the gear, and the gear maintains meshing with the spur gear when the rotating member is separated from the fixing member. The invention described in claim 5 is the fixing device described in claim 1, characterized in that a rotating annular member is provided between the fixing member and the rotating member, and the annular member rotates by the driving force of the rotating member. The invention described in claim 6 is a fixing device comprising a fixing member used to fix an image on a recording medium, a rotating member that is pressed against the fixing member and rotatably arranged to form a pressure section between the fixing member and the recording medium where pressure is applied to the recording medium, and a transmission section that transmits a rotational driving force to the rotating member, wherein the rotating member is movable in a direction toward and away from the fixing member, and the transmission section is connected coaxially with the rotation axis of the rotating member. The invention described in claim 7 is the fixing device described in claim 6, characterized in that the transmission portion includes a coupling. The invention as recited in claim 8 is an image forming apparatus including the fixing device as recited in claim 1. The invention as set forth in claim 9 is an image forming apparatus including the fixing device as set forth in claim 6. Effect of the Invention

[0006] According to the invention of claim 1, the effect of image fixing on the recording medium can be suppressed compared to a case in which a rotational driving force is transmitted to the rotating member, causing the rotating member to move in the direction toward or away from the fixing member. According to the invention of claim 2, the transmission section can save space inside the device, compared to a case where the transmission section is not provided with a configuration in which the transmission section is located on the opposite side of the fixing member across the rotating member. According to the invention of claim 3, the transmission section can save space inside the device, compared to a case where the transmission section does not include a configuration including a gear that meshes with a spur gear coaxial with the rotation shaft of the rotating member. According to the invention of claim 4, the gear is provided on the fixed member together with a driving gear that meshes with the gear, and when the rotating member separates from the fixing member, the gear can reduce the effect of localized heat on the rotating member compared to a case in which the gear does not have a configuration that maintains meshing with the spur gear. According to the invention of claim 5, a rotating annular member is provided between the fixing member and the rotating member, and the annular member can rotate more stably than when the annular member is not configured to rotate by the driving force of the rotating member. According to the invention of claim 6, the effect of image fixing on the recording medium can be suppressed compared to a case in which a rotational driving force is transmitted to the rotating member, causing the rotating member to move in the direction toward or away from the fixing member. According to the invention of claim 7, the transmission section can transmit the driving force even when eccentricity occurs between the shafts, compared to a case where the transmission section does not include a coupling. According to the invention of claim 8, the effect of image fixing on the recording medium can be suppressed compared to a case in which a rotational driving force is transmitted to the rotating member, causing the rotating member to move in the direction toward or away from the fixing member. According to the invention of claim 9, the effect of image fixing on the recording medium can be suppressed compared to a case in which a rotational driving force is transmitted to the rotating member, causing the rotating member to move in the direction toward or away from the fixing member. [Brief description of the drawings]

[0007] [Figure 1] 1 is a diagram illustrating an image forming apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram illustrating a configuration of a fixing unit according to the present embodiment. [Diagram 3] FIG. 2 is a diagram illustrating a fixing unit according to the first embodiment. [Figure 4] FIG. 3 is a diagram illustrating a transmission unit according to the first embodiment. [Diagram 5] FIG. 11 is a diagram illustrating a fixing unit according to a second embodiment. [Figure 6] FIG. 11 is a diagram illustrating a fixing unit according to a second embodiment. [Figure 7] 13 is a diagram illustrating a transmission unit according to the second embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a diagram showing an image forming apparatus 1 according to the present embodiment. The image forming apparatus 1 shown in the figure is an apparatus that forms an image on a sheet of paper P. The image forming apparatus 1 is provided with an image forming section 10, a sheet transport section 20, and a control section 40.

[0009] The image forming section 10 includes an image forming unit 11, an intermediate transfer belt 12, a secondary transfer section 13, and a fixing device 14. In this embodiment, the image forming units 11 include four image forming units 11Y, 11M, 11C, and 11K corresponding to toner of four colors, Y (yellow), M (magenta), C (cyan), and K (black), respectively.

[0010] The image forming units 11Y, 11M, 11C, and 11K are arranged side by side in the moving direction of the intermediate transfer belt 12, and form toner images by electrophotography. Each of the image forming units 11Y, 11M, 11C, and 11K includes a photoconductor drum 111, a charging unit 112, an exposure unit 113, a developing unit 114, and a primary transfer unit 115. Each of the image forming units 11Y, 11M, 11C, and 11K forms a toner image of any one of the colors YMCK, and transfers this toner image onto the intermediate transfer belt 12. As a result, a toner image in which the toner images of the respective colors YMCK are superimposed is formed on the intermediate transfer belt 12.

[0011] The photoconductor drum 111 rotates at a predetermined speed in the direction of the arrow A. Furthermore, an electrostatic latent image is formed on the circumferential surface of the photoconductor drum 111. The charging unit 112 charges the peripheral surface of the photoconductor drum 111 to a predetermined potential. The exposure unit 113 irradiates the charged peripheral surface of the photoconductor drum 111 with light, forming an electrostatic latent image on the peripheral surface of the photoconductor drum 111 . The developing unit 114 deposits toner onto the electrostatic latent image formed on the circumferential surface of the photoconductor drum 111 to form a toner image.

[0012] The primary transfer unit 115 transfers the toner image formed on the circumferential surface of the photosensitive drum 111 onto the intermediate transfer belt 12 . A voltage of a polarity opposite to the charge polarity of the toner is applied to the primary transfer unit 115. As a result, the toner images formed on the circumferential surface of the photoconductor drum 111 are electrostatically attracted in sequence onto the intermediate transfer belt 12, and a single overlapping color toner image is formed on the intermediate transfer belt 12.

[0013] The intermediate transfer belt 12 is supported by a plurality of roll-shaped members. The intermediate transfer belt 12 is formed in an endless shape and circulates in the direction of the arrow B. The intermediate transfer belt 12 has an outer circumferential surface 12a and an inner circumferential surface 12b. The intermediate transfer belt 12 is used to transport a toner image. In this embodiment, a toner image is formed on an outer peripheral surface 12a of the intermediate transfer belt 12, and this toner image is transported to a secondary transfer unit 13 by the movement of the intermediate transfer belt 12.

[0014] In this embodiment, a drive roll 121 that is driven by a motor (not shown) and drives the intermediate transfer belt 12 is provided as a roll-shaped member disposed inside the intermediate transfer belt 12. In addition, an idle roll 123 that supports the intermediate transfer belt 12 and a backup roll 132 are provided as roll-shaped members. These roll-shaped members are rotatably provided and pressed against the inner circumferential surface 12 b of the intermediate transfer belt 12 .

[0015] The paper transport section 20 is provided with a paper storage section 21 in which a plurality of sheets of paper P are stored in a stacked state, and a pick-up roll 22 that picks up and transports the paper P stored in the paper storage section 21. The paper transport section 20 is also provided with a transport roll 23 that transports the paper P picked up by the pickup roll 22 along the paper transport path 30, and a paper guide section 24 that guides the paper P transported by the transport roll 23 to the secondary transfer section 13. Furthermore, the paper transport section 20 is provided with a transport belt 25 that transports the paper P after the secondary transfer to the fixing device 14, and a paper guide section 26 that guides the paper P after the fixing to a paper discharge section 27.

[0016] The secondary transfer section 13 is provided with a secondary transfer roll 134 arranged in contact with the outer peripheral surface 12a of the intermediate transfer belt 12, and a backup roll 132 arranged on the inner peripheral surface 12b side of the intermediate transfer belt 12 and serving as an opposing electrode to the secondary transfer roll 134. In this embodiment, a metallic power supply roll 133 that applies a secondary transfer bias to the backup roll 132 is provided. The secondary transfer unit 13 thus configured transfers the toner image, which has been conveyed to the secondary transfer unit 13 by the intermediate transfer belt 12, onto the paper P which has also been conveyed thereto.

[0017] The fixing unit 14 is disposed downstream of the secondary transfer unit 13 in the transport direction of the paper P. The fixing unit 14 includes a fixing belt module 50 having a heat source, and a pressure roll 61 disposed opposite the fixing belt module 50. When the paper P that has passed through the secondary transfer unit 13 is transported between the fixing belt module 50 and the pressure roll 61, the unfixed toner image on the paper P is melted and then fixed onto the paper P. As a result, an image made of the toner image is formed on the paper P.

[0018] FIG. 2 is a diagram illustrating the configuration of the fixing unit 14 according to the present embodiment. As shown in the figure, the fixing device 14 according to the present embodiment includes the above-mentioned fixing belt module 50 having the fixing belt 51, and the above-mentioned pressure roll 61 that contacts the outer surface of the fixing belt 51.

[0019] The fixing belt module 50 includes the above-mentioned fixing belt 51 that moves in a direction of the arrow C, and a first tension roll 52 that stretches the fixing belt 51 from the inside of the fixing belt 51. The fixing belt module 50 also includes a second tension roll 55 that stretches the fixing belt 51 from the inside, upstream of the first tension roll 52 in the direction of the arrow C. The fixing belt module 50 also includes a pressing unit 53 that is located downstream of the first tension roll 52 in the direction of the arrow C and has a pad portion 53a for pressing the fixing belt 51 against the pressure roll 61 to form a nip portion N.

[0020] In the fixing device 14, a part of the outer circumferential surface 61a of the pressure roll 61 is pressed against the outer circumferential surface 51a of the fixing belt 51, which is in contact with the pressing portion 53, from the side opposite to the pressing portion 53, thereby forming a nip portion N. The nip portion N, where the outer circumferential surface 61a of the pressure roll 61 and the fixing belt 51 are in contact with each other, is a passage portion through which the paper P on which the toner image is formed passes while being pressurized and heated.

[0021] The paper P that enters the nip portion N has a toner image forming surface on which a toner image is formed, but in this embodiment, the paper P enters the nip portion N with the toner image forming surface facing upward. As a result, in this embodiment, the toner image forming surface side of the paper P comes into contact with the fixing belt 51.

[0022] In the present embodiment, the pressure roll 61 is rotated by a motor 62, and the fixing belt 51 moves in a circular motion following the pressure roll 61. That is, the fixing belt 51 receives a driving force from the rotating pressure roll 61 and moves in a circular motion (circulation) in the direction of arrow C. More specifically, the rotational driving force of the motor 62 is transmitted to the pressure roll 61 via a drive transmission system 90. The motor 62 is controlled by the control unit 40.

[0023] The first tension roll 52 and the second tension roll 55 are supported rotatably, and the fixing belt 51 is wound around them at positions spaced apart from each other, thereby supporting the fixing belt 51 so as to be capable of rotating. The pressing unit 53 is disposed at a position facing the pressure roll 61 with the fixing belt 51 sandwiched therebetween, and presses the fixing belt 51 against the pressure roll 61 without rotating. The pressure roll 61 has an elastically deformable layer on the outer circumferential surface side, and the pressing unit 53 comes into contact with the pressure roll 61 via the fixing belt 51, causing the pressure roll 61 to assume a recessed shape at the nip portion N. In this embodiment, the paper P is sandwiched from both sides by the pressure roll 61 and the pressing unit 53, and pressure is applied to the paper P.

[0024] A heater 52a is provided inside the first tension roll 52. A heater 55a is provided inside the second tension roll 55. These heaters 52a and 55a are, for example, halogen heaters. The first tension roll 52 is heated by the heat of the heater 52a, and the second tension roll 55 is heated by the heat of the heater 55a. The fixing belt 51 is heated by the heat from the first tension roll 52 and the second tension roll 55. 2, the fixing belt 51 is wound around the outer circumferential surface of the first tension roll 52 in a section that is about a quarter of the circumference, and the fixing belt 51 is wound around the outer circumferential surface 55b in a section that is about half or more of the circumference. This allows the amount of heat from the heaters 52a and 55a to be imparted to the fixing belt 51.

[0025] The fixing belt module 50 includes a liquid applicator 54 between the first tension roll 52 and the second tension roll 55, which applies oil to the inner surface of the fixing belt 51. The liquid applicator 54 includes an oil-impregnated member 541 that contacts the inner surface of the fixing belt 51, a housing 542 that holds the oil-impregnated member 541, and a support member 543 that supports a portion of the oil-impregnated member 541 including its tip from the side opposite the fixing belt 51.

[0026] The oil-impregnated member 541 is a nonwoven fabric made of heat-resistant fibers impregnated with oil. For example, PTFE (polytetrafluoroethylene) is used as the heat-resistant fiber. The oil applied to the inner circumferential surface 51b of the fixing belt 51 by the oil-impregnated member 541 reduces the coefficient of friction between the pressing portion 53 and the fixing belt 51, and suppresses wear of the fixing belt 51.

[0027] The fixing belt module 50 includes an upstream cleaning roll 71 as a component for cleaning the outer peripheral surface 51 a of the fixing belt 51 . The upstream cleaning roll 71 is a cleaning member for cleaning the outer peripheral surface 51a of the fixing belt 51, and more specifically, removes any attached matter or the like that has adhered to the outer peripheral surface 51a of the fixing belt 51 after passing through the nip portion N.

[0028] The upstream cleaning roll 71 is provided at a position upstream of the second tension roll 55 and at a position where the fixing belt 51 is sandwiched between the upstream cleaning roll 71 and the second tension roll 55. In other words, the upstream cleaning roll 71 is disposed so as to press a portion of the fixing belt 51 away from the second tension roll 55 at an entrance portion of the second tension roll 55 against the second tension roll 55.

[0029] The surface of the upstream cleaning roll 71 according to the present embodiment is formed of a nonwoven fabric, a felt material, or a porous material. The upstream cleaning roll 71 according to the present embodiment is a driven roll that rotates by contacting with the circulating fixing belt 51.

[0030] 2, the fixing belt 51 that has passed through the nip portion N is sandwiched between the upstream cleaning roll 71 and the second tension roll 55, and is deformed into a so-called S-shape. That is, the fixing belt 51 is deformed into a shape in which an inner peripheral surface side protrusion 51c that is protruding toward the inner peripheral surface 51b of the fixing belt 51 so as to fit along the upstream cleaning roll 71 and an outer peripheral surface side protrusion 51d that is protruding toward the outer peripheral surface 51a of the fixing belt 51 so as to fit along the second tension roll 55 are continuous. The inner peripheral surface convex portion 51 c is a deformation caused by the pressure of the upstream cleaning roll 71 at the entrance portion of the fixing belt 51 to the second tension roll 55 . Such S-shaped deformation is formed by the path of the fixing belt 51 caused by the pressure of the upstream cleaning roll 71 at the entrance portion of the fixing belt 51 relative to the second tension roll 55 .

[0031] Here, the paper P is an example of a recording medium, the pressing portion 53 or the fixing belt module 50 is an example of a fixing member, the pressure roll 61 is an example of a rotating member, the nip portion N is an example of a pressure portion, the fixing belt 51 is an example of an annular member, and the fixing device 14 is an example of a fixing device.

[0032] Here, in this embodiment, the pressing unit 53 (see FIG. 2) is fixed to form the nip portion N in the fixing unit 14 (see FIG. 2) and to ensure the running stability of the paper P (see FIG. 1). In addition, in order to maintain the nip load at a predetermined value against the fixed pressing unit 53, it is necessary to press the pressure roll 61 (see FIG. 2) with, for example, a spring. In order to efficiently generate the nip load with the pressure roll 61 and move in the direction of arrow D (see FIG. 3, for example), which is the direction of moving toward and away from the fixed pressing unit 53, the position of the rotation shaft portion 82 (see FIG. 3, for example) in the moving mechanism 80 described later needs to be on the upstream side or downstream side of the conveying direction of the paper P with respect to the pressure roll 61. Furthermore, when the fixed pressing unit 53 is adopted, it is necessary to drive the fixing belt 51 by the pressure roll 61. Furthermore, when the pressure roll 61 moves by a latch operation, in order to maintain the precision of the gears' axes, it is preferable to adopt a configuration in which the driving force of the motor 62 (see FIG. 2) is input to a gear rotating around the rotation shaft portion 82 described later.

[0033] However, if a configuration is adopted in which the driving force of the motor 62 is input to a gear rotating around the rotating shaft portion 82, the driving reaction force causes the nip load, which is the load at the nip portion N, to fluctuate, which has a negative effect on the fixing of the image onto the paper P. Therefore, in this embodiment, a configuration is adopted in which the nip load does not fluctuate due to the driving reaction force, thereby suppressing the nip load from fluctuating due to the driving reaction force of the motor 62. The first and second embodiments will be described below.

[0034] <First embodiment> FIG. 3 is a diagram illustrating the fixing unit 14 according to the first embodiment. The fixing device 14 of the first embodiment includes a moving mechanism 80 capable of moving the pressure roll 61 in a direction toward and away from the fixing belt module 50. Note that the fixing belt module 50 has a configuration common to that shown in FIG. 2, and therefore a description thereof may be omitted.

[0035] (Moving mechanism 80) As shown in FIG. 3, the movement mechanism 80 according to the first embodiment includes a main body portion 81, a rotating shaft portion 82, and a cam member 83.

[0036] The main body 81 is rotatable about a rotation shaft 82. The rotation shaft 82 does not move relative to the fixing belt module 50. The main body 81 also supports the rotation shafts 61b on both ends of the pressure roll 61 so that the rotation shafts 61b are rotatable. Therefore, the pressure roll 61 supported by the main body 81 can move in conjunction with the movement of the main body 81 in the direction of arrow D. That is, the pressure roll 61 can advance and retreat with respect to the fixing belt module 50. The direction of the arrow D here is an example of a direction in which the pressure roll 61 advances and retreats relative to the fixing belt module 50.

[0037] The cam member 83 is a disk-shaped part having a cam surface 83a whose distance from the rotation axis varies depending on the circumferential position, and is driven by a motor (not shown) and the circumferential position is controlled. A stepping motor capable of positioning control can be used as the motor (not shown).

[0038] More specifically, the cam member 83 is located below the main body portion 81. A portion of the main body portion 81 is in contact with a cam surface 83a, and moves up and down around the rotation shaft portion 82 as the cam member 83 rotates. As a result, the pressure roll 61 supported by the main body 81 can be displaced from a position in contact with the fixing belt module 50, indicated by a solid line, to a position away from the fixing belt module 50, indicated by a dashed line, and also in the reverse direction. Therefore, the pressure roll 61 can be moved in a direction toward and away from the fixing belt module 50 by the cam member 83.

[0039] (Drive train 90) In the first embodiment, the drive transmission system 90 includes a transmission unit 91. The transmission unit 91 is connected coaxially to the rotation shaft 61b of the pressure roll 61. Therefore, the pressure roll 61 receives the rotational driving force of the motor 62 (see FIG. 2) coaxially with the pressure roll 61. Therefore, no moment is generated in the direction of the arrow D about the rotating shaft 82. Therefore, the load fluctuation in the nip N caused by the input of the rotational driving force from the transmission part 91 to the pressure roll 61 is suppressed. The transmission unit 91 is located on the opposite side of the pressure roll 61 from the pressing unit 53 .

[0040] FIG. 4 is a diagram illustrating the transmission unit 91 in the first embodiment. 4, the transmission unit 91 is composed of a coupling or a shaft joint. That is, the transmission unit 91 includes a drive shaft 91a on the motor 62 (see FIG. 2) side and a driven shaft 91b connected to the rotation shaft 61b of the pressure roll 61.

[0041] More specifically, the transmission unit 91 is a flexible coupling that allows for eccentricity, angular deviation, and vibration between the drive shaft 91a and the driven shaft 91b. When the pressure roll 61 moves in the direction of arrow D, for example, even if the pressure roll 61 is displaced from the driven shaft 91b shown by the solid line to the driven shaft 91b shown by the dashed line, the transmission unit 91 can follow the displacement. The amount of displacement δ in this case is, for example, about 3 mm, and the positional deviation can be absorbed.

[0042] <Second embodiment> Figures 5 and 6 are diagrams for explaining a fixing unit 14 according to the second embodiment, and also show a moving mechanism 80. Figures 5 and 6 correspond to Figure 3 for explaining the first embodiment. Also, Figure 7 is a diagram for explaining a transmission unit 92 in the second embodiment.

[0043] (Moving mechanism 80) 5 or 6, the moving mechanism 80 includes a main body portion 81, a rotating shaft portion 82, and a cam member 83. The moving mechanism 80 according to the second embodiment is the same as that of the first embodiment shown in FIG. 3, so the same reference numerals are used and the description thereof will be omitted.

[0044] (Drive train 90) 5 to 7, in the second embodiment, the drive transmission system 90 (see FIG. 2) includes a transmission unit 92. The transmission unit 92 is located on the opposite side of the pressure roll 61 from the pressing unit 53.

[0045] 7, the transmission unit 92 includes a drive gear 92a to which the rotational driving force of the motor 62 (see FIG. 2) is input, a driven gear 92b meshing with the drive gear 92a, and a gear 92c at the end of the pressure roll 61 meshing with the driven gear 92b. The drive gear 92a and the driven gear 92b are provided in the main body 81 of the movement mechanism 80.

[0046] As shown in Figures 5 and 6, in the second embodiment, the drive gear 92a, the driven gear 92b, and the gear 92c are made up of spur gears to save space, but any of them may be gears other than spur gears, for example, bevel gears.

[0047] Here, the gear 92c is an example of a spur gear coaxial with the rotation axis of the rotating member, the driven gear 92b is an example of a gear that meshes with the spur gear, and the driving gear 92a is an example of a driving gear. The main body 81 is an example of a fixed member.

[0048] 5, the transmission unit 92 is configured so that a driving reaction force 93 generated when the rotational driving force from the motor 62 (see FIG. 2) is transmitted from the driven gear 92b to the gear 92c at the end of the pressure roll 61 is directed toward the rotating shaft unit 82. More specifically, the direction in which the driving force from the transmission unit 92 acts is toward the rotating shaft unit 82, and is different from the direction of arrow D, that is, the direction in which the pressure roll 61 advances and retreats relative to the fixing belt module 50. In other words, the direction of arrow D, which is the direction in which the pressure roll 61 advances and retreats, does not coincide with the direction in which the driving force from the transmission unit 92 acts. Therefore, no moment is generated in the direction of the arrow D about the rotating shaft 82. Therefore, the load fluctuation in the nip N caused by the input of the rotational driving force from the transmission part 92 to the pressure roll 61 is suppressed.

[0049] The direction of the driving reaction force 93 shown in Fig. 5 is the direction toward the center of the rotating shaft 82, which is indicated by the dashed line. More specifically, the direction of the driving reaction force 93 is determined by the pressure angle of the gear. The pressure angle is the angle between a radial line passing through an arbitrary point on the tooth profile and a tangent to the tooth profile, and the gear transmits force in the direction of the pressure angle.

[0050] As shown in FIG. 6, when the pressure roll 61 moves in the direction of arrow D relative to the fixing belt module 50, the driven gear 92b moves following the gear 92c at the end of the pressure roll 61. The drive gear 92 a does not displace relative to the fuser belt module 50 .

[0051] Thus, in the transmission unit 92 of the second embodiment, the driven gear 92b maintains meshing with the gear 92c when the pressure roll 61 is separated from the fixing belt module 50. This makes it possible to rotate the pressure roll 61 even when the pressure roll 61 is separated from the fixing belt module 50. By rotating the pressure roll 61 that is separated from the fixing belt module 50, the influence of local heat from the fixing belt module 50 to the pressure roll 61 is suppressed.

[0052] <Additional Notes> (((1))) a fixing member used to fix an image on a recording medium; a rotating member that is pressed against the fixing member and rotatably provided, and that forms a pressure section between the fixing member and the rotating member, where a recording medium is pressed; A transmission unit that transmits a rotational driving force to the rotating member; Equipped with the rotating member is movable toward and away from the fixing member, The direction in which the rotating member advances and retreats does not coincide with the direction in which the driving force is applied by the transmission unit. Fixing device. (((2))) the transmission portion is located on the opposite side of the rotating member from the fixing member, The fixing device according to (((1))) above. (((3))) The transmission unit includes a gear that meshes with a spur gear that is coaxial with the rotation axis of the rotating member. The fixing device according to (((1))) or (((2))) above. (((4))) The gear is provided on a fixed member together with a drive gear that meshes with the gear, When the rotating member is separated from the fixing member, the gear maintains meshing with the spur gear. The fixing device according to (((3))) above. (((5))) a rotating annular member is provided between the fixing member and the rotating member, The annular member rotates by the driving force of the rotating member. The fixing device according to any one of ((1))) to (((4))). (((6))) a fixing member used to fix an image on a recording medium; a rotating member that is pressed against the fixing member and rotatably provided, and that forms a pressure section between the fixing member and the rotating member, where a recording medium is pressed; A transmission unit that transmits a rotational driving force to the rotating member; Equipped with the rotating member is movable toward and away from the fixing member, The transmission unit is connected coaxially to the rotation axis of the rotating member. Fixing device. (((7))) The transmission unit includes a coupling. The fixing device according to (((6))) above. (((8))) An image forming apparatus including the fixing device described in (((1))). (((9))) An image forming apparatus including the fixing device according to (((6))).

[0053] According to the invention (((1))), the effect of image fixing on the recording medium can be suppressed compared to a case in which a rotational driving force is transmitted to the rotating member, causing the rotating member to move toward and away from the fixing member. According to the invention (((2))), the transmission section can save space inside the device, compared to a case in which the transmission section is not provided with a configuration located on the opposite side of the rotating member from the fixing member. According to the invention (((3))), the transmission section can save space inside the device compared to a case in which the transmission section does not have a configuration including a gear that meshes with a spur gear coaxial with the rotation shaft of the rotating member. According to the invention (((4))), the gear is provided on the fixed member together with a drive gear that meshes with the gear, and when the rotating member separates from the fixing member, the gear can reduce the effects of localized heat on the rotating member compared to a case in which the gear does not have a configuration that maintains meshing with the spur gear. According to the invention (((5))), a rotating annular member is provided between the fixing member and the rotating member, and the annular member can rotate more stably than when the annular member is not configured to rotate by the driving force of the rotating member. According to the invention (((6))), the effect of image fixing on the recording medium can be suppressed compared to a case in which a rotational driving force is transmitted to the rotating member, causing the rotating member to move toward and away from the fixing member. According to the invention (((7))), the transmission section can transmit the driving force even when eccentricity occurs between the shafts, compared to a case where the transmission section does not include a coupling. According to the invention (((8))), the effect of image fixing on the recording medium can be suppressed compared to a case in which a rotational driving force is transmitted to the rotating member, causing the rotating member to move toward and away from the fixing member. According to the invention (((9))), the effect of image fixing on the recording medium can be suppressed compared to a case in which a rotational driving force is transmitted to the rotating member, causing the rotating member to move toward and away from the fixing member. [Explanation of symbols]

[0054] 1: image forming apparatus, 14: fixing device, 51: fixing belt, 53: pressing portion, 61: pressure roll, 91, 92: transmission portion, 92a: driving gear, 92b: driven gear, 92c: gear, N: nip portion

Claims

1. a fixing member used to fix an image on a recording medium; a rotating member that is pressed against the fixing member and rotatably provided, and that forms a pressure section between the fixing member and the rotating member, where a recording medium is pressed; A transmission unit that transmits a rotational driving force to the rotating member; Equipped with the rotating member is movable toward and away from the fixing member, The direction in which the rotating member advances and retreats does not coincide with the direction in which the driving force is applied by the transmission unit. Fixing device.

2. the transmission portion is located on the opposite side of the rotating member from the fixing member, 2. The fixing device according to claim 1,

3. The transmission unit includes a gear that meshes with a spur gear that is coaxial with the rotation axis of the rotating member.

2. The fixing device according to claim 1,

4. The gear is provided on a fixed member together with a drive gear that meshes with the gear, When the rotating member is separated from the fixing member, the gear maintains meshing with the spur gear.

4. The fixing device according to claim 3.

5. a rotating annular member is provided between the fixing member and the rotating member, The annular member rotates by the driving force of the rotating member.

2. The fixing device according to claim 1,

6. a fixing member used to fix an image on a recording medium; a rotating member that is pressed against the fixing member and rotatably provided, and that forms a pressure section between the fixing member and the rotating member, where a recording medium is pressed; A transmission unit that transmits a rotational driving force to the rotating member; Equipped with the rotating member is movable toward and away from the fixing member, The transmission unit is connected coaxially to the rotation axis of the rotating member. Fixing device.

7. The transmission unit includes a coupling.

7. The fixing device according to claim 6,

8. An image forming apparatus comprising the fixing device according to claim 1 .

9. An image forming apparatus comprising the fixing device according to claim 6.

Images