Fixing device and image forming device

Abstract

To provide a fixing device which corrects the meandering of a fixing belt by applying oil to an inner peripheral surface of the fixing belt and bringing an end of the fixing belt into contact with a guide surface of a guide member, wherein the oil is prevented from going around an outer peripheral surface of the fixing belt by the passage of the guide member, compared to a case where the guide surface of the guide member is a vertical surface along a thickness direction of the fixing belt.SOLUTION: There is provided a fixing device 5A which comprises: a fixing belt 52; a plurality of holding members 53, 54, 55 which rotatably hold the fixing belt 52; a pressing roll 62 which presses the fixing belt 52 to one holding member 54 of the holding members from an outer peripheral surface side to form a fixation processing part FN; application means 57 which applies oil to an inner peripheral surface of the fixing belt 52; and guide members 70A, 70B which are provided near both ends in a longitudinal direction of at least one holding member 55 of the holding members, and in which the guide surfaces with which ends 52c, 52d of the fixing belt 52 are contacted are composed of a slope surface 76 inclined outwardly in the longitudinal direction.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] Japanese Patent Application Laid-Open No. 2005-266376 (Patent Document 1) describes a fixing device having a fixing belt, a heating device, a pressure roll, a pressing member, a guide member, a driving roll, and a driving belt. Patent document 1 also describes that the guide members abut against the inner peripheral surfaces of both side edges of the fixing belt to guide the circular movement of the fixing belt, and that the drive belt transmits the driving force of the drive roll to the fixing belt.

[0003] Japanese Patent Laid-Open Publication No. 2004-286923 (Patent Document 2) describes a fixing device including a fixing belt wound around a heating member and a nip forming member, a pressure roller, and the nip forming member. Furthermore, Patent Document 2 describes that protrusions for regulating belt meandering are provided integrally with the nip forming member on both sides in the longitudinal direction of the nip forming member.

[0004] Patent Document 3, JP-A-11-91978, describes a fixing device including at least a fixing belt stretched between a drive roller and a driven roller, a belt deviation detection member, a support means, and a belt driving device. Patent document 3 also describes that the belt deviation detection member is supported so as to be rotatable independently of the driven roller, that the support means supports the end of the driven roller perpendicular to the axial direction, and that the belt drive device has a conversion means for converting the displacement of the end of the driven roller shaft into displacement in a specified direction perpendicular to the axial direction. Furthermore, Patent Document 3 describes that the support means includes a shaft end support member, a belt biasing member, and a guide member that guides the shaft end support member in a predetermined direction and in the direction in which the fixing belt is stretched. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2005-266376 A (Claim 1, Figures 2 to 5) [Patent Document 2] JP 2004-286923 A (Claim 1, Figures 1-2) [Patent Document 3] JP 11-91978 A (claims 1, 5, figures 1 and 13) Summary of the Invention [Problem to be solved by the invention]

[0006] The objective of the present invention is to prevent oil from leaking onto the outer peripheral surface of the fixing belt as the guide member passes, in a fixing device that applies oil to the inner peripheral surface of the fixing belt and brings the end of the fixing belt into contact with the guiding surface of a guiding member to correct the meandering of the fixing belt, compared to when the guiding surface of the guiding member is a vertical surface that runs along the thickness direction of the fixing belt. [Means for solving the problem]

[0007] The first aspect of the present invention is A fixing belt; a plurality of holding members for rotatably holding the fixing belt; a pressing roll that presses the fixing belt from an outer peripheral surface side against one of the holding members to form a fixing processing portion; a coating means for coating an inner peripheral surface of the fixing belt with oil; a first guide member provided on at least one of the holding members, the first guide member having a guide surface with which an end of the fixing belt comes into contact, the guide surface being an inclined surface inclined outward in the longitudinal direction; The fixing device is provided with:

[0008] The second aspect of the present invention is the fixing device according to the first aspect, The fixing device has a guide surface that is an inclined surface that is curved and convex outward.

[0009] The third aspect of the present invention is the fixing device according to the first aspect, In the fixing device, the guide surface is a linearly inclined slope.

[0010] The fourth aspect of the present invention is the fixing device according to the first aspect, the at least one holding member is a steering roll that corrects meandering by applying a returning force to the holding member after tilting in response to meandering of the fixing belt, The first guide member is a fixing device that is provided so as to be movable in the axial direction relative to the rotation shaft of the steering roll.

[0011] A fifth aspect of the present invention is a fixing device according to the fourth aspect, Another of the plurality of holding members is a rotating roll having a heating means, The fixing device has a second guide member fixed to the rotating roll, at least a portion of the guide surface with which the end of the fixing belt contacts being positioned further outward in the axial direction of the steering roll than the guide surface of the first guide member.

[0012] A sixth aspect of the present invention is a fixing device according to the fifth aspect of the present invention, The fixing device has a guide surface of the second guide member whose outermost end is in the same position as the outermost end of the guide surface of the first guide member when the steering roll is inclined to its maximum and the first guide member moves outward in the axial direction.

[0013] The seventh aspect of the present invention is the fixing device according to the sixth aspect, The guide surface of the second guide member is a fixing device that is an inclined surface that is inclined outward in the axial direction of the rotating roll.

[0014] The eighth aspect of the present invention is the fixing device according to the fourth aspect, In this fixing device, a second guide member is fixed to all of the multiple holding members other than the steering roll, and at least a portion of the guide surface with which the end of the fixing belt contacts is located outside the axial direction of the steering roll relative to the guide surface of the first guide member.

[0015] The ninth aspect of the present invention is the fixing device according to the eighth aspect, The fixing device has a guide surface of the second guide member whose outermost end is in the same position as the outermost end of the guide surface of the first guide member when the steering roll is inclined to its maximum and the first guide member moves outward.

[0016] The tenth aspect of the present invention is the fixing device according to the ninth aspect, The guide surface of the second guide member is a fixing device that is an inclined surface inclined outward in the longitudinal direction of all the holding members.

[0017] An eleventh aspect of the present invention is an image forming apparatus comprising the fixing device according to any one of the first to tenth aspects. Effect of the Invention

[0018] According to the fixing device of the first means described above, it is possible to prevent oil from getting around to the outer peripheral surface of the fixing belt as the guide member passes through, compared to when the guide surface of the guide member at the end of the fixing belt is a vertical surface along the thickness direction of the fixing belt.

[0019] According to the fixing device of the second means described above, the increase in load caused by the end of the fixing belt coming into contact with the guide surface can be suppressed compared to when the guide surface is an inclined surface that is curved and convex toward the inside, opposite the outside.

[0020] According to the fixing device of the third means, the oil can be prevented from flowing around the outer circumferential surface of the fixing belt, compared to when the guide surface is a vertical surface.

[0021] According to the fixing device of the fourth means described above, compared to a case where the steering roll is not provided with the first guide member, it is possible to correct the meandering of the fixing belt while suppressing the intrusion of oil onto the outer peripheral surface of the fixing belt.

[0022] According to the fixing device of the fifth means described above, the guide surface of the second guide member fixed to the rotating roll is provided at the same axial position as the guide surface of the first guide member of the steering roll, and compared to the case where this guide surface is provided at the same axial position as the guide surface of the first guide member of the steering roll, it is possible to suppress the intrusion of oil onto the outer peripheral surface of the fixing belt without impairing the function of the steering roll of correcting the meandering of the fixing belt.

[0023] According to the fixing device of the sixth means described above, the load received by the end of the serpentine fixing belt when it comes into contact with the guide surface consisting of the inclined surface of the first guiding member of the steering roll at its maximum inclination can be reduced, compared to when the outermost end of the guide surface of the second guiding member is located axially outer than the outermost end of the guide surface when the steering roll is at its maximum inclination and the first guiding member moves outward. In addition, according to the fixing device of the sixth means described above, it is possible to avoid an increase in the load that the end of the serpentine fixing belt receives when it comes into contact with the fixed guide surface of the second guide member, compared to when the outermost end of the guide surface of the second guide member is located axially more inward than the outermost end of the guide surface when the steering roll is tilted to its maximum and the first guide member moves outward.

[0024] According to the fixing device of the seventh means described above, the oil can be prevented from getting around to the outer peripheral surface of the fixing belt as the second guiding member passes through, compared to when the guiding surface of the second guiding member is a vertical surface.

[0025] According to the fixing device of the eighth means described above, the second guide member fixed to all holding members other than the steering roll can be prevented from causing oil to flow around the outer peripheral surface of the fixing belt by passing through all of the guide members of the holding members without impairing the function of correcting the meandering of the fixing belt of the steering roll, compared to the case where the second guide member is fixed to all holding members other than the steering roll and is provided at the same position in the longitudinal direction as the guide member of the steering roll.

[0026] According to the fixing device of the ninth means described above, the load received by the end of the serpentine fixing belt when it comes into contact with the guide surface consisting of the inclined surface of the guide member of the steering roll at its maximum inclination can be reduced, compared to when the outermost end of the guide surface of the second guide member is located axially outer than the outermost end of the guide surface when the steering roll is at its maximum inclination and the first guide member moves outward. In addition, according to the fixing device of the ninth means described above, it is possible to avoid an increase in the load that the end of the serpentine fixing belt receives when it comes into contact with each guide surface of the fixed second guide member, compared to when the outermost end of the guide surface of the second guide member is located axially more inward than the outermost end of the guide surface when the steering roll is tilted to its maximum and the first guide member moves outward.

[0027] According to the fixing device of the tenth aspect, the oil can be prevented from getting around the outer peripheral surface of the fixing belt as the second guiding member passes through, compared to when the guiding surface of the second guiding member is a vertical surface.

[0028] According to the image forming apparatus of the above-mentioned 11th means, the passage of the guide member in the fixing device prevents oil from wrapping around the outer peripheral surface of the fixing belt, thereby making it possible to suppress the induction of uneven fixing and degradation in image quality caused by the oil wrapping around the fixing belt. [Brief description of the drawings]

[0029] [Figure 1] 1 is a schematic diagram of an image forming apparatus according to a first embodiment. [Diagram 2] 1 is a schematic diagram of a fixing device according to a first embodiment. [Diagram 3] FIG. 3A is a schematic side view of a steering roll and a guide member in the fixing device of FIG. 2, and FIG. 3B is an enlarged view of one of the guide members in the steering roll of FIG. [Figure 4] 3A is a conceptual diagram showing the relationship between the components of the fixing device in FIG. 2, and FIG. 3B is an enlarged view showing a state in which the steering roll and one of the guide members in FIG. 3 hold the fixing belt. [Diagram 5] FIG. 5A is a conceptual diagram showing the state when the fixing belt meanders in the fixing device of FIG. 4, and FIG. 5B is an enlarged view showing the state in which the steering roll tilted due to the meandering of the fixing belt and one of the guide members hold the fixing belt. [Figure 6] FIG. 11 is a schematic diagram of a fixing device according to a second embodiment. [Figure 7] 7 is a conceptual diagram showing the relationship between the components of the fixing device in FIG. 6. [Figure 8] 7 is a conceptual diagram showing a state in which the fixing belt of the fixing device of FIG. 6 meanders. FIG. [Figure 9] 9 is an enlarged view showing a state in which each holding member and one guide member of each holding member hold a fixing belt in the fixing device of FIG. 8. [Figure 10] 1A is an enlarged view showing a modified example of a guide surface of a guide member, and FIG. 1B is an enlarged view showing a state in which a steering roll provided with the guide member of FIG. 1A holds a fixing belt. [Figure 11] FIG. 1A is a schematic side view of a steering roll in a fixing device and a comparative guide member, and FIG. 1B is a schematic side view showing the state when the steering roll in (A) and the comparative guide member are operated by a meandering fixing belt. [Figure 12] 12 is a schematic diagram showing the flow of oil onto the outer peripheral surface of a fixing belt caused by the passage of the steering roll of FIG. 11 and a comparative guide member. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Hereinafter, an embodiment of the present invention will be described.

[0031] Embodiment 1 Fig. 1 shows an image forming apparatus 10 according to a first embodiment of the present invention. Fig. 2 shows a fixing device 5A according to the first embodiment. In this specification and the drawings, the same reference numerals are used for substantially the same components. In this specification, duplicated explanations of the same components are omitted. Furthermore, in the drawings, in order to ensure ease of understanding, illustrations other than those necessary for the explanation are almost omitted.

[0032] (1) Configuration of Image Forming Apparatus The image forming apparatus 10 is a device that forms an unfixed image corresponding to image information input from the outside on a sheet of paper 9, which is an example of a recording medium. 1, the image forming apparatus 10 has a housing 11 having a desired external shape. The image forming apparatus 10 is configured by arranging an image forming section 20, a paper supply device 40, a paper transport device 45, a fixing device 5A, etc. in the internal space of the housing 11. 1 indicates a main transport path along which the paper 9 is transported by the paper transport device 45 within the housing 11.

[0033] The image forming unit 20 is a section that forms a toner image made of toner as a developer and transfers it onto the paper 9 . The image forming unit 20 in the first embodiment is configured as an electrophotographic image forming unit. The image forming unit 20 includes a photosensitive drum 21, a charging device 22, an exposure device 23, a developing device 24, a transfer device 25, a cleaning device 26, and other devices.

[0034] Among these, the photosensitive drum 21 is an example of an image carrying means, and is a photosensitive body having a drum shape with a photosensitive layer that becomes an image forming surface or an image carrying surface. The photosensitive drum 21 receives power from a driving device (not shown) and rotates in the direction indicated by the arrow A. The charging device 22 is a device that charges the outer peripheral surface (image forming surface) of the photosensitive drum 21 to a required surface potential. As the charging device 22, for example, a device equipped with a charging member in the form of a roll or the like that is brought into contact with the image forming surface of the outer peripheral surface of the photosensitive drum 21 and to which a charging current is supplied is used.

[0035] The exposure device 23 is a device that forms an electrostatic latent image by irradiating and exposing the charged outer peripheral surface of the photosensitive drum 21 with light corresponding to image information. The exposure device 23 operates by receiving an image signal that is generated by subjecting image information input from the outside to predetermined processing by an image processing means (not shown) or the like. The image information is, for example, information related to images such as characters, figures, photographs, and patterns. The developing device 24 is a device that develops the electrostatic latent image formed on the outer peripheral surface of the photosensitive drum 21 with a developer (toner) of a corresponding predetermined color (e.g., black) to visualize it as a toner image of the predetermined color. As the developer, for example, a two-component developer containing a toner and a carrier is used.

[0036] The transfer device 25 is a device that transfers the unfixed toner image formed on the outer peripheral surface of the photosensitive drum 21 onto the paper 9. As the transfer device 25, a device that includes a transfer member in the form of a roll or the like that is brought into contact with the outer peripheral surface of the photosensitive drum 21 and is supplied with a transfer current is used. The location where the transfer device 25 and the photosensitive drum 21 face each other is a transfer position TP where an unfixed toner image is transferred. The cleaning device 26 is a device that cleans the outer circumferential surface of the photosensitive drum 21 by removing unnecessary matter such as unnecessary toner and paper powder adhering to the outer circumferential surface of the photosensitive drum 21 .

[0037] The paper supply device 40 is a device that stores the paper 9 to be supplied to the transfer position TP in the image forming unit 20 and sends it out at a predetermined time. The paper feeder 40 includes a container 41 for storing the paper 9, a delivery device 43 for delivering the paper 9 one sheet at a time, and other devices. In the first embodiment, two containers 41A and 41B are used as the container 41, and two sending devices 43A and 43B are used as the sending device 43. Furthermore, container 41A stores paper 9A. Container 41B stores paper 9B. Paper 9A and paper 9B are, for example, different sizes.

[0038] The paper 9 may be any sheet-like recording medium that can be transported inside the housing 11 and onto which an unfixed toner image can be transferred and fixed. As long as the recording medium satisfies these conditions, there are no particular restrictions on the material, shape, etc., of the recording medium. In the image forming apparatus 10, as the paper 9, recording media such as plain paper cut to a predetermined size, coated paper, film, thick paper, and also recording media such as envelopes.

[0039] The paper transport device 45 is a device that transports the paper 9 within the housing 11 to a required location. The paper transport device 45 has a supply path, a relay path, a discharge path, etc. The supply path is a path that transports the paper 9 from the paper supply device 40 to the transfer position TP in the image forming unit 20. The relay path is a path that transports the paper 9 from the transfer position TP in the image forming unit 20 to the fixing device 5A. The discharge path is a path that transports the paper 9 from the fixing device 5A to the discharge port 12 provided on a side portion or the like of the housing 11. Further, the paper transport device 45 is configured by combining a plurality of transport roll pairs 46, transport path members (not shown), etc. The transport roll pair 46 is a pair of transport rolls that sandwich and transport the paper 9. In the first embodiment, for example, six transport roll pairs 46a to 46f are used. The transport path members are members that form a transport space for the paper 9, etc., and guide the paper 9 to its destination.

[0040] The fixing device 5A is a device that fixes the unfixed image onto the paper 9. The unfixed image is a toner image that is formed in the image forming section 20 and transferred.

[0041] As shown in FIGS. 1 and 2, the fixing device 5A according to the first embodiment is configured by arranging devices such as a heating rotor 51 and a pressure rotor 61 in the internal space of a housing 50. The housing 50 is provided with an inlet 50a for introducing the paper 9 and an outlet 50b for discharging the paper 9 after fixing. The fixing device 5A is arranged so that the heating rotator 51 and the pressure rotator 61 rotate in contact with each other, and the contacting portion is configured as the fixing processing portion FN. The fixing processing portion FN is a portion that performs a fixing process by applying heat and pressure to the paper 9 and toner image passing therethrough, and is also called a fixing nip. The fixing device 5A will be described in detail later.

[0042] (2) Operation of the image forming device The image forming apparatus 10 forms a basic image as follows.

[0043] In image forming apparatus 10, when a control means (not shown) receives a command for an operation of forming an image, a charging operation, an exposing operation, a developing operation, and a transferring operation are performed in image forming section 20. Also, in image forming apparatus 10, a paper feed operation is performed in paper feed device 40 and paper transport device 45.

[0044] As a result, in the image forming unit 20, a toner image corresponding to the image information is formed on the image forming surface of the photosensitive drum 21 rotating in the direction indicated by the arrow A. Meanwhile, in the paper supply device 40, the desired paper 9 (9A, 9B) is sent out and supplied to the transfer position TP of the image forming unit 20 via the supply path of the paper transport device 45. Then, in the image forming unit 20, the toner image is transferred from the photosensitive drum 21 to the paper 9 (9A, 9B) at the transfer position TP.

[0045] In the image forming unit 20, the cleaning device 26 performs a cleaning operation while the photosensitive drum 21 is rotating. As a result, the image forming surface of the photosensitive drum 21 is cleaned by the cleaning device 26 at times including after the toner image has been transferred.

[0046] Next, in the image forming apparatus 10, the paper 9 onto which the toner image has been transferred is transported to the fixing device 5A via the relay path of the paper transport device 45. In the relay path, the paper 9 is sent out in a state of being sandwiched between the rotating photosensitive drum 21 and the transfer device 25.

[0047] In the fixing device 5A, as shown in FIG. 2, a fixing operation is performed in which the paper 9 (9A, 9B) onto which the toner image 92 has been transferred is subjected to a fixing process in the fixing unit FN. As a result, in the fixing device 5A, the unfixed toner image 92 on the paper 9 is introduced into the fixing processing section FN and heated under pressure as it passes through, thereby being fixed to the paper 9.

[0048] Subsequently, in the image forming apparatus 10, the paper 9 after fixing is discharged from the inside of the housing 50 of the fixing device 5A, and then conveyed to the discharge port 12 via the discharge path of the paper conveying device 45. As a result, the paper 9 is sent by the transport roll pair 46e to an ejected paper storage section (not shown) provided in a part of the housing 11, and is stored therein.

[0049] Through the above series of operations, the basic image forming operation for forming a monochrome image on one side of one sheet of paper 9 is completed.

[0050] (3-1) Configuration of the Fixing Device Next, the fixing device 5A will be described in detail.

[0051] 2, the fixing device 5A uses a heating unit having a belt-nip configuration as the heating rotator 51. The fixing device 5A also uses a pressure roll 62, which is an example of a pressing roll having a roll configuration, as the pressure rotator 61.

[0052] The heating rotator 51 includes a fixing belt 52, three holding members 53, 54, and 55 that rotatably hold the fixing belt 52, an oil application device 57, and the like. Of these, the three supporting members are a heating roll 53, a contact member 54, and a steering roll 55. The fixing belt 52 is supported so as to rotate in the direction indicated by an arrow B (counterclockwise in FIG. 2).

[0053] The fixing belt 52 is an endless belt whose outer circumferential surface 52a comes into contact with the surface of the paper 9 onto which the toner image 92 has been transferred in the fixing unit FN to perform the fixing process. An endless belt having thermal conductivity, flexibility, and heat resistance is used as the fixing belt 52. In addition, as the fixing belt 52, for example, a belt having a laminated structure in which an elastic layer and a release layer are formed in this order on the outer peripheral surface of a cylindrical belt base material is used.

[0054] The belt substrate is a cylindrical member made of a synthetic resin such as polyimide or polyamide, the elastic layer is made of an elastic material such as silicone rubber, and the release layer is made of a resin material such as polytetrafluoroethylene.

[0055] The heating roll 53 is an example of a rotating roll having a heating unit 56. The heating roll 53 is a rotating roll that is heated by the heating unit 56 and heats the fixing belt 52. As the heating roll 53, a roll body having a structure in which a surface layer 532 is laminated on the outer peripheral surface of a cylindrical roll base material 531 is used.

[0056] The roll base 531 is a cylindrical body made of a metal material such as aluminum. The roll base 531 is rotatably attached to a part of the housing 50 via a bearing (not shown). The surface layer 532 is a layer that is non-conductive and has good thermal conductivity. As the heating means 56, for example, a plurality of electric heating lamps arranged in the internal space of the roll base material 531 are used.

[0057] The contact member 54 is a member that contacts the inner circumferential surface 52b of the fixing belt 52 at a certain position to hold the fixing belt 52. As shown in FIG. 4 and other figures, the contact member 54 is a structure in which a pad material 542 is provided on the lower surface of a cylindrical support 541. The support 541 is a structure made of a metal material such as aluminum. The support 541 is fixedly attached to a part of the housing 50. The pad material 542 is a member having heat resistance, elasticity, and the like.

[0058] The contact member 54 also includes a sliding sheet (not shown) disposed between the outer surface of the pad material 542 and the inner circumferential surface 52b of the fixing belt 52. One end of the sliding sheet is attached to the support 541. Furthermore, the corner of the contact member 54 on the side where the paper 9 to be fixed is introduced (the left side in FIG. 2) is raised, and the contact member 54 is disposed in a state in which it is inclined slightly backward as a whole.

[0059] 3A and 11, the steering roll 55 is a roll that prevents the meandering of the fixing belt 52 by applying a returning force to the rotation shaft 551 after the rotation shaft 551 is tilted in response to the meandering of the fixing belt 52. For this reason, the steering roll 55 can also be called a meandering correction roll. As shown in FIG. 3(A), the steering roll 55 in embodiment 1 includes a rotating shaft 551, a roll body 552 fixed to the rotating shaft 551, and first guide members 70A, 70B provided on the rotating shaft 551 adjacent to both ends of the roll body 552.

[0060] Both ends of the rotating shaft 551 are rotatably supported by bearings 553. The bearings 553 are attached to elongated mounting holes (not shown) provided in the front surface 50c and the rear surface 50d of the housing 50 so as to be movable a predetermined distance approximately in the vertical direction Sr. This allows the rotating shaft 551 to move via the bearing 553 by a predetermined distance in the vertical direction Sr relative to a mounting slot (not shown).

[0061] Moreover, bearing 553 is pulled upward with a constant spring force F1 by tension spring 554. Tension spring 554 has an upper end attached to attachment portions 502 provided on front surface 50c and rear surface 50d of housing 50. As a result, the rotating shaft 551 is maintained in a state in which it is pulled upward by a constant spring force F1 by the tension spring 554 via the bearing 553. In principle, the rotating shaft 551 is maintained in a state in which the bearing 553 is in contact with the upper end of an elongated mounting hole (not shown).

[0062] The roll body 552 is a roll portion that holds the inner portion of the fixing belt 52 excluding the end portions including both ends 52c and 52d. The roll body 552 is fixed to the rotating shaft 551 and rotates together with the rotating shaft 551.

[0063] The first guide members 70A and 70B are provided relative to the above-mentioned portion of the rotation shaft 551 of the steering roll 55 so as to be rotatable and axially movable. The steering roll 55 and the first guide members 70A and 70B will be described in detail later.

[0064] The oil application device 57 is an example of an oil application means that applies oil to the inner circumferential surface 52 b of the fixing belt 52 . The oil is applied in order to reduce the sliding resistance between the inner circumferential surface 52b of the fixing belt 52 and the contact member 54, and to remove wear particles present on the inner circumferential surface 52b of the fixing belt 52.

[0065] The oil application device 57 is made up of an oil-impregnated member, a holding member, and the like. The holding member is a member that holds the impregnated member so as to be in contact with the inner circumferential surface 52b of the fixing belt 52. As the oil, for example, an oil such as silicone oil is used. Further, the oil application device 57 is disposed so as to apply oil to a portion of the inner circumferential surface 52b of the fixing belt 52 that is between the heating roll 53 and the steering roll 55. The oil is applied to the entire area of ​​the inner circumferential surface 52b of the fixing belt 52 in the width direction (the direction perpendicular to the rotation direction B).

[0066] The pressure roll 62 as the pressure rotating body 61 is a roll that presses the fixing belt 52 from its outer circumferential surface 52a side against the contact member 54 to form the fixing processing section FN. 2, the pressure roll 62 has a roll structure in which an elastic release layer 64 is provided on the outer peripheral surface of a columnar or cylindrical roll substrate 63. Reference numeral 65 in FIG. 2 denotes shaft portions provided on both ends of the roll substrate 63.

[0067] The pressure roll 62 is supported by a support mechanism (not shown) so that the shaft portion 65 can be displaced in a direction approaching and separating from the contact member 54 . At least during the fixing operation, a predetermined pressure is applied to the shaft portion 65 of the pressure roll 62 by a pressure mechanism (not shown) in the direction toward the contact member 54 . Furthermore, during a fixing operation or the like, the pressure roll 62 receives power from a driving device (not shown) and is driven to rotate in the direction indicated by an arrow C. In the fixing device 5A, the pressure roll 62 rotates in the direction indicated by the arrow C, thereby rotating the fixing belt 52 in the direction indicated by the arrow B. Note that the fixing device 5A may be configured such that the heating roll 53 receives power from a driving device (not shown) at a predetermined time and rotates in the direction indicated by the arrow B.

[0068] (3-2) Configuration of guide members to be compared Before describing the first guide members 70A, 70B of the steering roll 55 in the first embodiment, a comparative first guide member 70X illustrated in FIG. 11 will be described.

[0069] The first guide member 70X for comparison is a structure having a main body portion 71 and an attachment portion 72, as exemplified in FIG. The main body 71 is a part having a semi-disk shape, and a guide surface 73 and a movement guide surface 74 are formed thereon. The attachment portion 72 is a portion that attaches the first guide member 70X so as to be rotatable about the rotation shaft 551 and movable in the axial direction by a predetermined distance.

[0070] The guide surfaces 73 of the main body 71 are surfaces with which both ends 52c, 52d of the fixing belt 52 come into contact and guide the fixing belt 52. The guide surfaces 73 are formed on the inner portion of the main body 71 facing the roll body 552. The guide surface 73 of the first guide member 70X for comparison is formed as a vertical plane along the thickness direction tb (see FIG. 12) of the fixing belt 52. The thickness direction tb is the direction indicating the thickness of the portion of the fixing belt 52 held by the steering roll 55. In other words, the guide surface 73 is formed as a plane perpendicular to the direction of the axis JL of the steering roll 55 (the axial direction).

[0071] The movement guide surface 74 in the main body 71 is an inclined surface that contacts the fixed guide jig 75 to guide the movement of the first guide member 70X. The movement guide surface 74 is formed as an inclined surface that guides the first guide member 70X to move downward when the first guide member 70X moves to the outside of the rotation shaft 551 when the fixing belt 52 meanders. The fixed guide jig 75 is made of a sphere or a round bar. The fixed guide jig 75 is in contact with the lower end portion of the movement guide surface 74 under normal conditions.

[0072] (3-3) Steering roll operation The steering roll 55 provided with the comparative first guide member 70X operates as follows.

[0073] Here, as illustrated in FIG. 11B, the description will be given on the assumption that the fixing belt 52 meanders so as to be displaced forward as indicated by an arrow M1. In this case, the end 52c of the meandering fixing belt 52E comes into strong contact with the guide surface 73 of the first guide member 70X at the front end when passing through the steering roll 55.

[0074] As a result, the first guide member 70X is pushed by one end 52c of the meandering fixing belt 52E and moves so as to be slightly shifted in the outward (front) direction E1 of the rotation shaft 551. Also, when the first guide member 70X moves in the outward direction E1 of the rotation shaft 551, the moving guide surface 74 comes into contact with the fixed guide jig 75 and moves, whereby the first guide member 70X is guided so as to be moved downward.

[0075] At this time, the first guide member 70X moves downward, so that the front end of the rotating shaft 551 is moved downward in the direction indicated by the arrow N via the bearing 553 from its normal position. As a result, the steering roll 55 is in a tilted state with its front end lowered below its normal position (the position of the axis JL) as shown in FIG. 11(B).

[0076] Furthermore, when the steering roll 55 is tilted in this manner, the front bearing 553 moves downward, and the tension spring 554 is stretched downward, so that the bearing 553 receives an upward spring force F2 from the tension spring 554. The spring force F2 at this time is greater than the spring force F1 under normal conditions.

[0077] As a result, the tilted steering roll 55 moves upward so that the front end that had moved downward is returned to its original normal position, and the steering roll 55 is no longer tilted. At this time, the first guide member 70X on the front side also moves upward as the moving guide surface 74 comes into contact with the fixed guide jig 75 and moves, and moves to the rear side of the rotation shaft 551 to return to its normal position.

[0078] 11B, the meandering fixing belt 52E is pushed with a predetermined force Fa by the guide surface 73 of the front first guide member 70X when one end 52c of the fixing belt 52E passes through the steering roll 55. As a result, the meandering fixing belt 52E moves entirely backward and is returned to a normal running position.

[0079] In this manner, the steering roll 55 exerts a function of preventing the fixing belt 52 from meandering. The meandering prevention function of the steering roll 55 is also exerted in the case where the fixing belt 52 meanders so as to be displaced rearward as indicated by the arrow M2 in FIG. 11B.

[0080] (3-4) Problems when using the guide members to be compared On the other hand, in a fixing device using the steering roll 55 provided with the comparative first guide member 70X, the following problems may occur.

[0081] That is, as illustrated in FIG. 12, a portion 59m of the oil 59 applied to the fixing belt 52 may flow around from one end 52c of the fixing belt 52 to the outer peripheral surface 52a while passing through and rotating through the comparative first guiding member 70X in the steering roll 55. A portion 59m of this flowing oil 59 moves upward from the gap between one end 52c of the fixing belt 52 and the guide surface 73 of the first guide member 70X, and then the portion of the oil moves so as to spread over the end region of the outer peripheral surface 52a of the fixing belt 52.

[0082] If oil gets around the outer peripheral surface 52a of the fixing belt 52 in this manner, part of the outer peripheral surface 52a of the fixing belt 52 may become contaminated with oil, resulting in uneven fixing, or the fixing belt 52 may slip, causing unstable rotation and deteriorating the image quality of the fixed image. In this case, the image quality may be degraded even in the image forming apparatus 10 equipped with the fixing device.

[0083] (3-5) Configuration of the First Guide Member in the First Embodiment The first guide members 70A and 70B in the fixing device 5A are movably provided near both ends of the steering roll 55. In the first embodiment, the vicinity of both ends of the steering roll 55 corresponds to portions of the rotating shaft 551 adjacent to both ends of the roll body 522. As illustrated in FIG. 3B, each of the first guide members 70A and 70B is a member having a main body portion 71 and an attachment portion 72, almost similar to the comparative first guide member 70X.

[0084] The main body 71 is a portion having a semi-disk shape, and is formed with a guide surface consisting of an inclined surface 76 and a movement guide surface 74, which will be described later. The mounting portion 72 is a portion for mounting the first guide members 70A, 70B so as to be rotatable about the rotation shaft 551 and movable by predetermined distances in directions E1, E2 along the axial direction.

[0085] Furthermore, as shown in FIG. 3, the guide surfaces of both first guide members 70A and 70B that come into contact with both ends 52c and 52d of fixing belt 52 are each configured as inclined surfaces 76 that are inclined outward in the longitudinal direction D of steering roll 55. In this case, the longitudinal direction D of the steering roll 55 is the axial direction of the rotation shaft 551. The outer sides of the longitudinal direction D are the sides facing both ends from the center in the axial direction of the rotation shaft 551.

[0086] The inclined surface 76 of the guide surface in the first embodiment is formed as an inclined surface that is curved and inclined so as to protrude outward in the axial direction of the steering roll 55, as shown in FIG. 3(B). Furthermore, the inclined surface 76 is roughly divided into a lower curved surface portion 76a and an upper curved surface portion 76b.

[0087] The lower curved surface portion 76a is a slope portion that is a portion on the side closer to the roll body 522 of the steering roll 55 and that rises with a small curvature from a lower end 76d of the slope 76. The upper curved surface portion 76b is a slope portion that continues from the upper end of the lower curved surface portion 76a and that rises to an upper end 76t of the slope 76 with a curvature larger than that of the lower curved surface portion 76a. The lower end 76d of the inclined surface 76 is located at a position where the radial distance from the rotation axis 551 of the steering roll 55 is the same as the radial distance of the surface 552a of the roll body 522.

[0088] The lower curved surface portion 76a is a portion that occupies an area that is, for example, about 2 mm or less in the axial direction from the lower end 76d of the inclined surface 76 when viewed in the axial direction of the steering roll 55. The upper curved surface portion 76b is a portion that occupies an area of ​​the inclined surface 76 excluding the lower curved surface portion 76a. In this case, the lower end 76d of the inclined surface 76 is the axially innermost end of the inclined surface 76. Also, the upper end 76t of the inclined surface 76 is the axially outermost end of the inclined surface 76. The upper curved surface portion 76b may be a linearly inclined surface.

[0089] (3-6) Operation of the steering roll provided with the first guide member The steering roll 55 provided with the first guide members 70A and 70B holds the fixing belt 52 in the following manner during normal times when the fixing belt 52 does not meander. That is, under normal conditions, as shown in Figures 3(A) and 4(A), the steering roll 55 holds the fixing belt 52 in a state in which both ends 52c, 52d of the fixing belt 52 are in contact with the lower curved portions 76a (see Figure 3(B)) of the inclined surfaces 76 on each guide surface of the first guide members 70A, 70B.

[0090] At this time, a portion of the fixing belt 52 including both ends 52c, 52d comes into contact with a part of the lower curved portion 76a of the inclined surface 76 on each guide surface of the first guide members 70A, 70B and is bent slightly upward (bent end 52e), as illustrated in Figure 4(B). At this time, the bent end 52e of the fixing belt 52 receives a reaction force due to the bending and is pressed against the inclined surface 76 of the guide surface. As a result, the oil 59 applied to the inner circumferential surface 52b of the fixing belt 52 is kept trapped between, for example, the bent end portion 52e of the fixing belt 52 and the inclined surface 76 (particularly the lower curved surface portion 76a) of the guide surface.

[0091] Therefore, in the fixing device 5A, even when the fixing belt 52 passes through the first guide members 70A, 70B of the steering roll 55, the fixing belt 52 is prevented from wrapping around the outer peripheral surface 52a of the fixing belt 52, compared to when the guide surface 73 of the comparative first guide member 70X is a vertical surface along the thickness direction tb of the fixing belt 52 (see Figure 12).

[0092] Further, when the fixing belt 52 meanders so as to be displaced forward as indicated by the arrow M1 as illustrated in FIG. 5A, the steering roll 55 provided with the first guide members 70A and 70B operates as follows. The operation at this time is substantially the same as that in the case of the steering roll 55 provided with the first guide member 70X for comparison (see FIG. 11(B)).

[0093] In this case, one end 52c of the meandering fixing belt 52E comes into strong contact with the guide surface formed by the inclined surface 76 of the first guide member 70A on the front side when passing through the steering roll 55. As a result, the first guide member 70A is pushed by one end 52c of the meandering fixing belt 52E and moves slightly outward (in the front direction E1) of the rotating shaft 551. When the first guide member 70A moves outward from the rotating shaft 551, the moving guide surface 74 comes into contact with the fixed guide jig 75 and moves, whereby the first guide member 70A is guided to move downward.

[0094] At this time, the front end of the rotating shaft 551 is moved downward via the bearing 553 due to the downward movement of the first guide member 70A. As a result, the steering roll 55 is in an inclined state with the front end lowered below its normal position (see FIG. 11(B)). Furthermore, when the steering roll 55 is tilted in this way, the front bearing 553 receives an upward spring force F2 from the downwardly stretched tension spring 554 (see FIG. 11(B)).

[0095] As a result, the tilted steering roll 55 moves upward so that the front end that had moved downward is returned to its original normal position, and the steering roll 55 is no longer tilted. At this time, the first guide member 70A on the front side also moves upward and to the rear side of the rotation axis 551 as the moving guide surface 74 comes into contact with and moves against the fixed guide jig 75, returning to its normal position (see Figure 3(A)).

[0096] 5A, the meandering fixing belt 52E is pushed with a predetermined force Fa by the guide surface formed of the inclined surface 76 of the first guide member 70A when one end 52c of the meandering fixing belt 52E passes through the steering roll 55. As a result, the meandering fixing belt 52E moves entirely backward and is returned to a normal running position.

[0097] In this manner, the steering roll 55 exerts a function of preventing the fixing belt 52 from meandering. The meandering prevention function of the steering roll 55 is also exerted in the case where the fixing belt 52 meanders so as to be displaced rearward as indicated by the arrow M2 in FIG. 5A.

[0098] Incidentally, both ends 52c, 52d of the meandering fixing belt 52E come into contact with a portion of the inclined surfaces 76 on each guide surface of the first guiding members 70A, 70B, as illustrated in FIG. 5(B), and are bent slightly upward (bent ends 52g). At this time, both ends 52c, 52d of the meandering fixing belt 52E are in contact with the upper end side of the lower curved surface portion 76a or a part of the upper curved surface portion 76b of the inclined surface 76. Moreover, the bent end portion 52g of the meandering fixing belt 52E at this time is bent more than the bent end portion 52e (see FIG. 4B) at one end 52c of the fixing belt 52 under normal conditions. Furthermore, the bent end 52g of the meandering fixing belt 52E receives a reaction force due to the bending and is pressed against the inclined surface 76 of the guide surface.

[0099] As a result, oil 59 applied to inner circumferential surface 52b of meandering fixing belt 52E is kept trapped between bent end portion 52g of fixing belt 52E and inclined surface 76 of the guide surface. As a result, in the fixing device 5A, even if the meandering fixing belt 52E passes through the first guide members 70A and 70B of the steering roll 55, the oil 59 is prevented from getting around the outer circumferential surface 52a of the fixing belt 52E.

[0100] Embodiment 2 FIG. 6 is a conceptual diagram of a fixing device 5B according to the second embodiment of the present invention. Fixing device 5B has the same configuration as fixing device 5A according to the first embodiment, except that heating roll 53 and contact member 54 are provided with second guide members 81 and 85, respectively.

[0101] (1-1) Configuration of the second guide member provided on the heating roll In the fixing device 5B, second guide members 81A and 81B are fixedly provided near both ends of the heating roll 53 as shown in FIG. The vicinity of both ends of the heating roll 53 is a portion that is inward by a predetermined distance from each of both ends in the axial direction of the heating roll 53. In addition, the vicinity of both ends of the heating roll 53 is also a portion that does not hinder the rotational running of the fixing belt 52 under normal conditions without meandering.

[0102] As shown in FIG. 7, the second guide members 81A and 81B have guide surfaces 82 with which the opposite ends 52c and 52d of the fixing belt 52 can come into contact. Each of the guide surfaces 82 of the second guide members 81A and 81B is an inclined surface that inclines outward in the axial direction of the heating roll 53. The guide surface 82 in the second embodiment is configured as an inclined surface obtained by narrowing the width of the inclined surface 76 on the guide surfaces of the first guide members 70A and 70B in the axial direction of the heating roll 53, for example.

[0103] Further, as shown in FIG. 7, the second guide members 81A, 81B are arranged so that at least a portion of each guide surface 82 is positioned outside the axial direction of the steering roll 55 relative to the guide surface consisting of the inclined surface 76 of the first guide members 70A, 70B. At this time, the first guide members 70A and 70B are in their normal positions when the fixing belt 52 is not meandering and is rotating and running in a normal position. As shown in FIG. 7, second guide members 81A and 81B in the second embodiment are provided so that the entire guide surfaces 82 thereof are positioned on the outside.

[0104] Furthermore, the second guide members 81A and 81B have the following positional relationship for the outermost ends 82t of the respective guide surfaces 82. In other words, when the steering roll 55 is tilted to its maximum by the serpentine fixing belt 52E and the first guide members 70A, 70B move axially outward, the outer end 82t of each guide surface 82 is in the same position as the upper end 76t of the guide surface consisting of the inclined surface 76 of the first guide members 70A, 70B.

[0105] In Figure 7, the dotted lines P1 and P2 are imaginary straight lines that pass through the upper ends 76t of each guide surface consisting of the inclined surfaces 76 of the first guide members 70A and 70B when the steering roll 55 is not tilted and both of the first guide members 70A and 70B are in their normal positions. In addition, in Figure 7, the dotted lines P3 and P4 are imaginary straight lines that pass through the outermost ends 76ts of each guide surface consisting of the inclined surfaces 76 of the first guide members 70A and 70B when the steering roll 55 is tilted to its maximum and the first guide members 70A and 70B move outward.

[0106] Therefore, the outermost ends 82t of the guide surfaces 82 of the second guide members 81A and 81B are positioned on the one-point lines P3 and P4, respectively.

[0107] (1-2) Configuration of the second guide member provided on the contact member In addition, in the fixing device 5B, second guide members 85A and 85B are fixedly provided near both ends of the contact member 54 as shown in FIG. The vicinity of both ends of the contact member 54 is a portion that is inward a predetermined distance from both ends of the contact member 54 in the longitudinal direction D. In addition, the vicinity of both ends of the contact member 54 is also a portion that does not hinder the rotational running of the fixing belt 52 under normal conditions without meandering.

[0108] 6 or 7, the second guide members 85A and 85B are provided at a position upstream of the fixing unit FN in the rotation direction B of the fixing belt 52. The second guide members 85A and 85B are attached so as to be fixed to a part of the support 541 of the contact member 54.

[0109] As shown in FIG. 7, the second guide members 85A and 85B have guide surfaces 86 with which the opposite ends 52c and 52d of the fixing belt 52 can come into contact. Each of the guide surfaces 86 of the second guide members 85A, 85B is an inclined surface that slopes outward in the longitudinal direction D of the contact member . The guide surface 86 in the second embodiment is configured as an inclined surface obtained by narrowing the width of the inclined surface 76 on the guide surfaces of the first guide members 70A and 70B in the axial direction of the heating roll 53, for example.

[0110] Further, as shown in FIG. 7, the second guide members 85A, 85B are arranged so that at least a portion of each guide surface 86 is positioned outside the axial direction of the steering roll 55 relative to the guide surface consisting of the inclined surface 76 of the first guide members 70A, 70B. As shown in FIG. 7, the second guide members 85A and 85B in the second embodiment are provided so that the entire guide surfaces 86 thereof are positioned on the outside.

[0111] Furthermore, the second guide members 85A and 85B have the following positional relationship in which the outermost ends 86t of the respective guide surfaces 86 thereof are located. In other words, the outermost end 86t of each guide surface 86 is in the same position as the upper end 76t of the guide surface 76 of the first guide members 70A, 70B when the steering roll 55 is tilted to its maximum due to the serpentine fixing belt 52E and the first guide members 70A, 70B move axially outward.

[0112] In other words, the outermost ends 86t of each guide surface 86 of the second guide members 85A, 85B are positioned on the one-point lines P3, P4, which are the virtual straight lines described above, similar to the upper ends 76t of each guide surface 76 of the second guide members 81A, 81B. In this case, the steering roll 55 is tilted to the maximum when the serpentine fixing belt 52E comes into contact with the guide surfaces of the first guide members 70A and 70B, and the bearings 553 (see Figure 3(A)) of the steering roll 55 reach the lowest position to which they can move.

[0113] (2) Operation of a fixing device provided with a first guide member and a second guide member In the fixing device 5B, under normal circumstances when the fixing belt 52 does not meander, the fixing belt 52 is held as follows.

[0114] First, the steering roll 55 provided with the first guide members 70A and 70B holds the fixing belt 52, similarly to the fixing device 5A in the first embodiment. Specifically, under normal conditions, as shown in FIG. 7, the steering roll 55 holds the fixing belt 52 in a state in which both ends 52c, 52d of the fixing belt 52 are in contact with the lower curved portions 76a (see FIG. 3(B)) of the inclined surfaces 76 on each guide surface of the first guide members 70A, 70B.

[0115] Next, the heating roll 53 provided with the second guide members 81A, 81B holds the fixing belt 52 in a state where both ends 52c, 52d of the fixing belt 52 are not in contact with each of the guide surfaces 82 of the second guide members 81A, 81B, as shown in FIG. In addition, the contact member 54 provided with the second guide members 85A, 85B holds the fixing belt 52 in a state where both ends 52c, 52d of the fixing belt 52 are not in contact with each of the guide surfaces 82 of the second guide members 81A, 81B, as shown in FIG. 7.

[0116] In the fixing device 5B under normal circumstances, a portion of the fixing belt 52 including both ends 52c, 52d is in substantially the same state as in the fixing device 5A according to the first embodiment.

[0117] In other words, a portion of the fixing belt 52 including both ends 52c, 52d comes into contact with a part of the lower curved surface portion 76a of the inclined surface 76 on each guide surface of the first guide members 70A, 70B and is bent slightly upward (bent end portion 52e) (see Figure 4(B)). At this time, the bent end 52e of the fixing belt 52 receives a reaction force due to the bending and is pressed against the inclined surface 76 of the guide surface. As a result, the oil 59 applied to the inner circumferential surface 52b of the fixing belt 52 is kept trapped between, for example, the bent end portion 52e of the fixing belt 52 and the inclined surface 76 of the guide surface (see FIG. 4B).

[0118] Therefore, even in the fixing device 5B, even when the fixing belt 52 passes through at least each of the first guide members 70A, 70B of the steering roll 55, the fixing belt 52 is prevented from wrapping around the outer peripheral surface 52a of the fixing belt 52, compared to when the guide surface 73 of the comparative first guide member 70X is a vertical surface along the thickness direction tb of the fixing belt 52 (see Figure 12).

[0119] In the fixing device 5B, when the fixing belt 52 meanders so as to be displaced forward as indicated by the arrow M1 as illustrated in FIG. 8, the fixing belt 52 is held as follows.

[0120] In this case, the steering roll 55 provided with the first guide members 70A, 70B is first tilted once and then returned to its normal position, almost similarly to the fixing device 5A according to the first embodiment.

[0121] 8, when one end 52c of the fixing belt 52E that has meandered forward passes through the steering roll 55, the fixing belt 52E is pushed backward with a predetermined force Fa by the guide surface formed of the inclined surface 76 of the first guide member 70A. As a result, the fixing belt 52E that has meandered forward moves entirely backward and is returned to a normal running position. In this manner, the steering roll 55 exerts a function of preventing the fixing belt 52 from meandering.

[0122] Furthermore, in the fixing device 5B, as in the case of the fixing device 5A of embodiment 1, even when the serpentine fixing belt 52E passes through the first guiding members 70A, 70B of the steering roll 55, the oil 59 is prevented from flowing around the outer peripheral surface 52a of the fixing belt 52.

[0123] Specifically, one end 52c of the meandering fixing belt 52E comes into contact with a part of the inclined surface 76 of the guide surface of the first guiding member 70A and is bent slightly upward (bent end 52g), as illustrated in FIG. Further, the bent end 52g of the meandering fixing belt 52E receives a reaction force due to the bending and is pressed against the inclined surface 76 of the guide surface.

[0124] As a result, oil 59 applied to inner circumferential surface 52b of meandering fixing belt 52E is kept trapped between bent end portion 52g of fixing belt 52E and inclined surface 76 of the guide surface. Therefore, in the fixing device 5B as well, the oil 59 is prevented from getting around the outer peripheral surface 52a of the meandering fixing belt 52E as described above.

[0125] In addition, in the fixing device 5B, as illustrated in FIG. 8, the fixing belt 52E, meandering forward, passes through and comes into contact with the guide surface 82 of the second guide member 81A located in front of the heating roll 53 and the guide surface 86 of the second guide member 85A located in front of the contact member 54.

[0126] At this time, the portion of the fixing belt 52E on one end 52c side comes into contact with a part of the guide surface 82 consisting of the inclined surface of the second guide member 81A of the heating roll 53, as illustrated in Figure 9, and becomes bent slightly upward (bent end 52h). At this time, the portion of the fixing belt 52E on one end 52c side comes into contact with a part of the guide surface 86 consisting of the inclined surface of the second guide member 85A of the contact member 54, and becomes bent slightly upward (bent end 52i), as illustrated in Figure 9.

[0127] At this time, the bent end 52h and the bent end 52i on the one end 52c side of the fixing belt 52E will be bent in substantially the same state if the inclined surfaces of the guide surface 82 and the guide surface 86 have the same configuration. At this time, the bent end 52h of the fixing belt 52E is pressed against the inclined surface of the guide surface 82 of the second guide member 81A by the reaction force due to the bending. The bent end 52i of the fixing belt 52E is pressed against the inclined surface of the guide surface 86 of the second guide member 86A by the reaction force due to the bending.

[0128] As a result, the oil 59 applied to the inner surface 52b of the serpentine fixing belt 52E is kept trapped between the bent end 52h of the fixing belt 52E and the inclined surface of the guide surface 82 as it passes through the second guiding member 85A. In addition, the oil 59 applied to the inner peripheral surface 52b of the meandering fixing belt 52E is kept trapped between the bent end 52i of the fixing belt 52E and the inclined surface of the guide surface 86 as the fixing belt 52E passes through the second guiding member 85A.

[0129] Therefore, in the fixing device 5B, even if the serpentine fixing belt 52E passes through the first guiding members 70A, 70B and also the second guiding members 81A, 81B and the second guiding members 85A, 85B, the oil 59 applied to the inner surface 52b of the fixing belt 52E is prevented from flowing around to the outer surface 52a of the fixing belt 52E.

[0130] Furthermore, in the fixing device 5B, the second guide members 81A, 81B, 85A, and 85B are arranged so that at least a portion of each of their guide surfaces 82, 86 is positioned outside the axial direction of the steering roll 55 relative to the guide surfaces of the first guide members 70A and 70B, as shown in FIG.

[0131] As a result, in the fixing device 5B, compared to when the second guide members 81A, 81B, 85A, 85B are provided at the same axial position as the first guide members 70A, 70B on the steering roll 55, there is no risk that the first guide members 70A, 70B on the steering roll 55 will not be prevented from moving axially outward due to contact with the meandering fixing belt 52E by the meandering fixing belt 52E coming into contact with the guide surfaces 82, 86 of the second guide members 81A, 81B, 85A, 85B before they come into contact with them.

[0132] As a result, according to the fixing device 5B, there is no impairment of the function of the steering roll 55 to correct the meandering of the fixing belt 52. In addition, even when the meandering fixing belt 52E passes between the guide surfaces of the first guiding members 70A and 70B and the guide surfaces 82 and 86 of the second guiding members 81A, 81B, 85A and 85B, the oil 59 is prevented from getting around the outer circumferential surface 52a of the fixing belt 52E.

[0133] Furthermore, as shown in Figures 7 and 8, the second guide members 81A, 81B, 85A, 85B in the fixing device 5B are arranged such that the outermost ends 82t, 86t of their respective guide surfaces 82, 86 are in the same position as the upper ends 76t of the guide surfaces of the first guide members 70A, 70B when the second guide members 81A, 81B, 85A, 85B move in conjunction with the steering roll 55 being tilted to its maximum by the serpentine fixing belt 52E.

[0134] As a result, in the fixing device 5B, the fixing belt 52E, which has meandered forward, may come into contact with the inclined guide surface of the first guide member 70A on the front side of the steering roll 55 and move axially outward, causing the steering roll 55 to tilt to its maximum extent.

[0135] However, in this case, in the fixing device 5B, the following occurs compared to the case where the outermost ends 82t, 86t of the guide surfaces 82, 86 are positioned axially outer than the upper ends 76t of the guide surfaces of the first guide members 70A, 70B when the steering roll 55 moves in conjunction with its maximum tilt. That is, in this case, as shown in Figures 8 and 9, before the steering roll 55 is tilted to its maximum, one end 52c of the fixing belt 52E, which has meandered forward, also comes into contact with the guide surface 82 of the second guide member 81A and the guide surface 86 of the second guide member 85A.

[0136] As a result, in the fixing device 5B, even when the steering roll is in a state just before or at its maximum inclination, the load that one end 52c of the fixing belt 52E which meanders forward and comes into contact with the guide surface consisting of the inclined surface 76 of the first guide member 70A at the front of the inclined steering roll 55 is reduced.

[0137] In this case, in the fixing device 5B, the following occurs compared to the case where the outermost ends 82t, 86t of the guide surfaces 82, 86 are positioned axially inward of the upper ends 76t of the guide surfaces of the first guide members 70A, 70B when the steering roll 55 moves in conjunction with its maximum tilt. That is, in the case where the steering roll 55 is in the inner position, when there is a possibility that the steering roll 55 is inclined to the maximum, one end 52c of the fixing belt 52E which meanders forward may strongly contact the guide surface 82 of the second guide member 81A fixed to the heating roll 53 and the guide surface 86 of the second guide member 85A fixed to the contact member 54 first. However, in the fixing device 5B, this risk does not occur.

[0138] Therefore, according to the fixing device 5B, an increase in the load that the serpentine fixing belt 52E receives when one end 52c of the fixing belt 52E comes into contact with the heating roll 53 and the guide surface 82 of the second guide member 81A fixed to the contact member 54 and the guide surface 86 of the second guide member 85A, respectively, is avoided.

[0139] Variations. The present invention is not limited to the configuration examples exemplified in the first and second embodiments, and may be modified as necessary, such as by combination, without departing from the spirit of the inventions described in the claims. Therefore, the present invention also includes, for example, the following modified examples.

[0140] The guide surfaces of the first guide members 70A and 70B may be linearly inclined slopes 77, as shown in FIG. The linearly inclined slope 77 may be a slope that extends in a straight line from its lower end 77d to its upper end 77t. The inclination angle α of the slope 77 with respect to the axis JL of the steering roll 55 may be set within a range of 30° to 75°, for example. If the inclination angle α is smaller than 30°, problems such as an inability to prevent the oil 59 from wrapping around the outer peripheral surface 52a of the fixing belt 52 occur. Conversely, if the inclination angle α is larger than 75°, problems such as the fixing belt 52 riding up along the inclined surface 77 causing the end of the fixing belt 52 to exceed the breaking elongation threshold and causing cracks.

[0141] At this time, the lower end 77d of the inclined surface 77 becomes the axially innermost end of the inclined surface 77. Moreover, the upper end 77t of the inclined surface 77 becomes the axially outermost end of the inclined surface 77. Furthermore, the lower end 77d of the inclined surface 77 is located at a position where the radial distance from the rotation shaft 551 of the steering roll 55 is the same as the radial distance of the surface 552a of the roll body 522.

[0142] The steering roll 55 provided with the first guide member 70A (70B) having the guide surface formed of the inclined surface 77 holds the fixing belt 52 as follows in normal times when the fixing belt 52 does not meander. That is, under normal circumstances, the steering roll 55 holds the fixing belt 52 in a state in which one end 52c of the fixing belt 52 contacts a part of the inclined surface 77 on the guide surface of the first guiding member 70A, as illustrated in FIG. 10(B).

[0143] At this time, a portion of the fixing belt 52 including one end 52c comes into contact with a part of the inclined surface 77 on the guide surface of the first guide member 70A and is bent slightly upward (bent end 52k), as illustrated in Figure 10(B). At this time, the bent end 52k of the fixing belt 52 receives a reaction force due to the bending and is pressed against the inclined surface 77 of the guide surface. As a result, the oil 59 applied to the inner circumferential surface 52b of the fixing belt 52 is kept trapped between, for example, the bent end portion 52k of the fixing belt 52 and the inclined surface 77 of the guide surface.

[0144] Therefore, in the fixing device employing the first guide member 70A, 70B having a guide surface consisting of the inclined surface 77, the oil 59 is prevented from flowing around the outer peripheral surface 52a of the fixing belt 52, in a manner similar to that of the fixing devices 5A, 5B of the first and second embodiments.

[0145] The guide surface of the first guide member 70 may be an inclined surface formed of a curved line with a single curvature. Also, the guide surface of the first guide member 70 may be an inclined surface that combines a curved inclined surface portion and a linear inclined surface portion. The second guide members 81, 85 may be provided only on one of the heating roll 53 and the contact member 54, and the provision of the second guide members 81, 85 on the other may be omitted. The guide surfaces 82, 86 of the second guide members 81, 85 may be inclined surfaces having a configuration different from that of the guide surfaces of the first guide member 70. In addition, at least one of the guide surfaces 82, 86 of the second guide members 81, 85 may be a vertical surface like the guide surface 73 of the comparative first guide member 70X.

[0146] As long as the fixing device of the present invention applies oil 59 to the inner surface 52b of the fixing belt 52 and is equipped with a steering roll 55, the type and method of the heating means 56, and the types and number of holding members other than the steering roll 55 that hold the fixing belt 52 may be changed. The oil application device 57 can be changed in terms of the location where it is installed and the number of the devices installed.

[0147] In addition, in the first embodiment and the like, a configuration example in which a monochrome image is formed is shown as the image forming apparatus 10, but the image forming apparatus of the present invention may be an apparatus that forms a multi-color image composed of a combination of toners of multiple colors. In addition, the image forming apparatus of the present invention is not particularly limited in terms of its image forming method, transfer method, and the like, so long as it is applied with the fixing device of the present invention.

[0148] (Additional Note) (((1))) A fixing belt; a plurality of holding members for rotatably holding the fixing belt; a pressing roll that presses the fixing belt from an outer peripheral surface side against one of the holding members to form a fixing processing portion; a coating means for coating an inner peripheral surface of the fixing belt with oil; a first guide member provided on at least one of the holding members, the first guide member having a guide surface with which an end of the fixing belt comes into contact, the guide surface being an inclined surface inclined outward in the longitudinal direction; A fixing device comprising: (((2))) The fixing device according to (((1))), wherein the guide surface is an inclined surface that is curved and convex outward. (((3))) The fixing device according to (((1))), wherein the guide surface is a linearly inclined slope. (((4))) the at least one holding member is a steering roll that corrects meandering by applying a returning force to the holding member after tilting in response to meandering of the fixing belt, The fixing device according to any one of ((1))) to (((3))), wherein the first guide member is provided axially movable relative to a rotation shaft of the steering roll. (((5))) Another of the plurality of holding members is a rotating roll having a heating means, The fixing device described in (((4))) has a second guide member fixed to the rotating roll, at least a portion of the guide surface with which the end of the fixing belt contacts being positioned further outward in the axial direction of the steering roll than the guide surface of the first guide member. (((6))) The fixing device described in (((5))), wherein the guide surface of the second guide member has an outermost end that is in the same position as the outermost end of the guide surface of the first guide member when the steering roll is inclined to its maximum and the first guide member moves outward in the axial direction. (((7))) The fixing device according to (((6))), wherein the guide surface of the second guide member is an inclined surface that inclines outward in the axial direction of the rotating roll. (((8))) The fixing device described in (((4))), wherein a second guide member is fixedly provided to all of the multiple holding members other than the steering roll, and at least a portion of a guide surface with which the end of the fixing belt contacts is positioned outer in the axial direction of the steering roll than the guide surface of the first guide member. (((9))) The fixing device described in (((8))), wherein the guide surface of the second guide member has an outermost end that is in the same position as the outermost end of the guide surface of the first guide member when the steering roll is inclined to its maximum and the first guide member moves outward. (((10))) The fixing device according to (((9))), wherein the guide surface of the second guide member is an inclined surface inclined outward in the longitudinal direction of all of the holding members. (((11))) An image forming apparatus comprising the fixing device according to any one of ((1))) to (((10))).

[0149] According to the fixing device of (((1))), it is possible to prevent oil from flowing around to the outer peripheral surface of the fixing belt as the guide member passes through, compared to when the guide surface of the guide member at the end of the fixing belt is a vertical surface along the thickness direction of the fixing belt. According to the fixing device of (((2))), the increase in load due to contact of the end of the fixing belt with the guide surface can be suppressed, compared to when the guide surface is an inclined surface that is curved and convex toward the inside, opposite the outside. According to the fixing device of (((3))), it is possible to prevent oil from flowing around the outer circumferential surface of the fixing belt, compared to a case in which the guide surface is a vertical surface. According to the fixing device of (((4))), it is possible to correct the meandering of the fixing belt while suppressing the intrusion of oil onto the outer peripheral surface of the fixing belt, compared to a case in which the first guide member is not provided on the steering roll. According to the fixing device of (((5))), compared to a case in which the guide surface of the second guide member fixed to the rotating roll is provided at the same axial position as the guide surface of the first guide member of the steering roll, it is possible to suppress the intrusion of oil onto the outer peripheral surface of the fixing belt without impairing the function of the steering roll of correcting the meandering of the fixing belt. According to the fixing device of (((6))), the load received by the end of the meandering fixing belt when it comes into contact with the guide surface consisting of the inclined surface of the first guiding member of the steering roll at its maximum inclination can be reduced, compared to when the outermost end of the guide surface of the second guiding member is located axially outer than the outermost end of the guide surface when the steering roll is at its maximum inclination and the first guiding member moves outward. Furthermore, according to the fixing device of (((6))), it is possible to avoid an increase in the load that the end of the meandering fixing belt receives when it comes into contact with the fixed guide surface of the second guiding member, compared to when the outermost end of the guiding surface of the second guiding member is positioned axially more inward than the outermost end of the guiding surface when the steering roll is tilted to its maximum and the first guiding member moves outward. According to the fixing device of (((7))), the oil can be prevented from flowing around the outer peripheral surface of the fixing belt as the second guide member passes through it, compared to when the guide surface of the second guide member is a vertical surface. According to the fixing device of (((8))), the second guide member, which is fixed to all holding members other than the steering roll, can be prevented from causing oil to flow around the outer peripheral surface of the fixing belt as the holding members pass through all of the guide members, without impairing the function of correcting the meandering of the fixing belt of the steering roll, compared to a case in which the second guide member is fixed to all holding members other than the steering roll and is provided at the same position in the longitudinal direction as the guide member of the steering roll. According to the fixing device of (((9))), the load received by the end of the meandering fixing belt when it comes into contact with the guide surface consisting of the inclined surface of the guide member of the steering roll at its maximum inclination can be reduced, compared to when the outermost end of the guide surface of the second guide member is located axially outer than the outermost end of the guide surface when the steering roll is at its maximum inclination and the first guiding member moves outward. Furthermore, according to the fixing device of (((9))), it is possible to avoid an increase in the load that the end of the meandering fixing belt receives as it comes into contact with each guiding surface of the fixed second guiding member, compared to a case in which the outermost end of the guiding surface of the second guiding member is located axially more inward than the outermost end of the guiding surface when the steering roll is tilted to its maximum and the first guiding member moves outward. According to the fixing device of (((10))), the passage of the second guide member can prevent oil from flowing around to the outer peripheral surface of the fixing belt, compared to when the guide surface of the second guide member is a vertical surface. According to the image forming apparatus of (((11))), the passage of the guide member in the fixing device prevents oil from flowing around the outer peripheral surface of the fixing belt, thereby preventing uneven fixing and deterioration of image quality caused by the oil flowing around the belt. [Explanation of symbols]

[0150] 5A, 5B... Fixing device 10...Image forming device 52...Fuser belt 52a...Outer surface 52b…Inner peripheral surface 52c,52d...edge 53... Heating roll (an example of a plurality of holding members and a rotating roll) 54...contact member (one example of a plurality of holding members) 55... steering roll (an example of at least one holding member) 551...Rotation axis 57...Oil application device (an example of an oil application means) 62...Pressure roll (an example of a pressing roll) 70A, 70B...First guide member 76...Slope (an example of a guide surface or an example of a curved slope) 76t…Top end 76ts...the outermost end when the first guide member moves 77...Slope (another example of a guideway and an example of a linearly inclined slope) 81A, 81B, 85A, 85B...Second guide members 82,86…Guide surface 82t, 86t...Top end (an example of the outermost end) FN: Fixing section D …Longitudinal direction (including axial direction) Fa...Power

Claims

1. A fixing belt; a plurality of holding members for rotatably holding the fixing belt; a pressing roll that presses the fixing belt from an outer peripheral surface side against one of the holding members to form a fixing processing portion; a coating means for coating an inner peripheral surface of the fixing belt with oil; a first guide member provided on at least one of the holding members, the first guide member having a guide surface with which an end of the fixing belt comes into contact, the guide surface being an inclined surface inclined outward in the longitudinal direction; A fixing device comprising:

2. 2. The fixing device according to claim 1, wherein the guide surface is an inclined surface that is curved and convex outward.

3. 2. The fixing device according to claim 1, wherein the guide surface is a linearly inclined slope.

4. the at least one holding member is a steering roll that corrects meandering by applying a returning force to the holding member after tilting in response to meandering of the fixing belt, 2. The fixing device according to claim 1, wherein the first guide member is provided so as to be movable in an axial direction relative to a rotation shaft of the steering roll.

5. Another holding member of the plurality of holding members is a rotating roll having a heating means, The fixing device according to claim 4, wherein a second guide member is fixed to the rotating roll, and at least a portion of a guide surface with which the end of the fixing belt contacts is located outside the axial direction of the steering roll relative to the guide surface of the first guide member.

6. The fixing device according to claim 5, wherein the guide surface of the second guide member has an outermost end that is in the same position as the outermost end of the guide surface of the first guide member when the steering roll is inclined to its maximum and the first guide member moves outward in the axial direction.

7. 7. The fixing device according to claim 6, wherein the guide surface of the second guide member is an inclined surface inclined outward in the axial direction of the rotating roll.

8. The fixing device described in claim 4, wherein a second guide member is fixed to all of the plurality of holding members other than the steering roll, and at least a portion of a guide surface with which the end of the fixing belt contacts is located outside the axial direction of the steering roll relative to the guide surface of the first guide member.

9. The fixing device according to claim 8, wherein the guide surface of the second guide member has an outermost end in the same position as the outermost end of the guide surface of the first guide member when the steering roll is inclined to its maximum and the first guide member moves outward.

10. 10. The fixing device according to claim 9, wherein the guide surface of the second guide member is an inclined surface inclined outward in the longitudinal direction of all of the holding members.

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

Images