Fixing device and image forming apparatus

Abstract

The invention discloses a fixing device and an image forming apparatus. The fixing device includes a fixing belt; a plurality of holding members that rotatably hold the fixing belt; a pressing roller 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 unit that coats oil on an inner circumferential surface of the fixing belt; and a first guide member provided on at least one of the holding members, a guide surface in contact with an end of the fixing belt being configured from an inclined surface inclined outward in a longitudinal direction.

Description

Technical Field

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

[0002] Japanese Patent Application Laid-Open No. 2005-266376 describes a fixing device including a fixing belt, a heating device, a pressure roller, a pressing member, a guide member, a driving roller, and a driving belt.

[0003] Japanese Patent Application Laid-Open No. 2005-266376 discloses that: the guide members contact the inner peripheral surfaces of both side edges of the fixing belt to guide the fixing belt to move around; and the drive belt transmits the driving force of the drive roller to the fixing belt.

[0004] Japanese Patent Application Laid-Open No. 2004-286923 describes a fixing device including a fixing belt wound around a heating member and a nip forming member, a pressure roller, and a nip forming member.

[0005] In addition, Japanese Patent Application Laid-Open No. 2004-286923 describes a structure in which projections for limiting meandering are provided integrally with the engagement forming member on both sides in the longitudinal direction of the engagement forming member.

[0006] Japanese Patent Application Laid-Open No. 11-91978 describes a fixing device including a fixing belt stretched between at least a driving roller and a driven roller, a belt deviation detecting member, a supporting unit, and a belt driving device.

[0007] In addition, the Japanese Patent Gazette No. 11-91978 states that: the belt deviation detection component is supported to be able to rotate freely independently from the driven roller; the support unit supports the end of the driven roller at right angles to the axial direction; and the belt drive device has a conversion mechanism that converts the displacement of the end of the driven roller shaft into a displacement in a predetermined direction at right angles to the axial direction.

[0008] Furthermore, Japanese Patent Application Laid-Open No. 11-91978 discloses that the support unit includes a shaft end support member, a belt urging member, and a guide member for guiding the shaft end support member in a predetermined direction and in a direction in which the fixing belt is tensioned. Summary of the invention

[0009] The object of the present invention is to provide a fixing device, which applies oil to the inner peripheral surface of a fixing belt and makes the end of the fixing belt contact with the guide surface of a guide component to correct the meandering of the fixing belt. In the fixing device, compared with the case where the guide surface of the guide component is a vertical surface along the thickness direction of the fixing belt, the situation in which oil is wrapped around the outer peripheral surface of the fixing belt due to the fixing belt passing through the guide component is suppressed.

[0010] According to a first aspect of the present invention, there is provided a fixing device comprising: a fixing belt; a plurality of retaining members, the retaining members retaining the fixing belt so as to be rotatable; a pressing roller, the pressing roller pressing the fixing belt from the outer peripheral surface side onto one of the retaining members to form a fixing processing portion; a coating unit, the coating unit coating oil onto the inner peripheral surface of the fixing belt; and a first guide member, the first guide member being arranged on at least one of the retaining members, the guide surface with which the end of the fixing belt contacts being composed of an inclined surface inclined toward the outside in the length direction.

[0011] According to a second aspect of the present invention, in the fixing device according to the first aspect, the guide surface is an inclined surface inclined in a curved shape convex toward the outside.

[0012] According to a third aspect of the present invention, in the fixing device according to the first aspect, the guide surface is a linearly inclined slope.

[0013] According to the fourth aspect of the present invention, in the fixing device based on any one of the first to third aspects, the at least one retaining component is a steering roller that corrects the meandering by acting through a restoring force after being tilted corresponding to the meandering of the fixing belt, and the first guide component is configured to be able to move axially relative to the rotation axis of the steering roller.

[0014] According to the fifth aspect of the present invention, in the fixing device based on the fourth aspect, another retaining component among the multiple retaining components is a rotating roller having a heating unit, and a second guide component is fixedly arranged on the rotating roller, and at least a portion of the guide surface of the second guide component for contact with the end of the fixing belt is located on the axial outside of the steering roller than the guide surface of the first guide component.

[0015] According to the sixth aspect of the present invention, in the fixing device based on the fifth aspect, with respect to the guide surface of the second guide member, its outermost end is at the same position as the outermost end of the guide surface of the first guide member when the steering roller is tilted to the maximum extent and the first guide member is moved to the outer side in the axial direction.

[0016] According to a seventh aspect of the present invention, in the fixing device according to the sixth aspect, the guide surface of the second guide member is an inclined surface inclined outward in the axial direction of the rotating roller.

[0017] According to the eighth aspect of the present invention, in the fixing device based on the fourth aspect, a second guide component is fixedly arranged on all the retaining components among the multiple retaining components except the steering roller, and at least a portion of the guide surface of the second guide component for contact with the end of the fixing belt is located on the axially outer side of the steering roller than the guide surface of the first guide component.

[0018] According to the ninth aspect of the present invention, in the fixing device based on the eighth aspect, with respect to the guide surface of the second guide member, its outermost end is at the same position as the outermost end of the guide surface of the first guide member when the steering roller is tilted to the maximum extent and the first guide member is moved to the outer side in the axial direction.

[0019] According to a tenth aspect of the present invention, in the fixing device according to the ninth aspect, the guide surface of the second guide member is an inclined surface inclined outward in the longitudinal direction of all the holding members.

[0020] An eleventh aspect of the present invention provides an image forming apparatus including the fixing device according to any one of the first to tenth aspects.

[0021] (Effect)

[0022] According to the first aspect, compared with a case where the guide surface of the guide member for guiding the end of the fixing belt is a vertical surface along the thickness direction of the fixing belt, it is possible to suppress the oil from being circulated around the outer peripheral surface of the fixing belt as the fixing belt passes through the guide member.

[0023] According to the second aspect, compared with a case where the guide surface is an inclined surface inclined in a curved shape convex toward the inner side opposite to the outer side, an increase in load caused by the end of the fixing belt contacting the guide surface can be suppressed.

[0024] According to the third aspect, compared with a case where the guide surface is a vertical surface, it is possible to suppress the oil from entering the outer peripheral surface of the fixing belt.

[0025] According to the fourth aspect, compared with a case where the first guide member is not provided on the switchback roller, it is possible to correct the meandering of the fixing belt and suppress the oil from entering the outer peripheral surface of the fixing belt.

[0026] According to the fifth aspect, compared with the case where the guide surface of the second guide component fixedly arranged on the rotating roller is arranged at the same axial position as the guide surface of the first guide component of the steering roller, it is possible to suppress the oil from winding around the outer peripheral surface of the fixing belt without damaging the function of the steering roller to correct the meandering of the fixing belt.

[0027] According to the sixth aspect, compared with a situation where the outermost end of the guide surface of the second guide component is located at a position closer to the outside in the axial direction when the outermost end of the guide surface of the first guide component is maximally inclined than the steering roller and the first guide component is moved to the outside, the load exerted on the end of the serpentine fixing belt due to contact with the guide surface composed of the inclined surface of the first guide component of the maximally inclined steering roller can be reduced.

[0028] In addition, according to the sixth aspect, compared with a situation where the outermost end of the guide surface of the second guide component is located at a position closer to the inner side in the axial direction when the first guide component is moved to the outer side and the outermost end of the guide surface of the second guide component is maximally inclined than the steering roller, the increase in the load on the end of the serpentine fixing belt due to contact with the guide surface of the fixed second guide component can be avoided.

[0029] According to the seventh aspect, compared with a case where the guide surface of the second guide member is a vertical surface, it is possible to suppress the oil from being circulated around the outer peripheral surface of the fixing belt due to the fixing belt passing through the second guide member.

[0030] According to the eighth aspect, compared with a case where the second guide member fixedly provided on all retaining members other than the steering roller is provided at the same position in the length direction as the guide member of the steering roller, it is possible to suppress the oil from being wound around the outer peripheral surface of the fixing belt due to the fixing belt passing through all the guide members of the retaining members without damaging the function of the steering roller in correcting the meandering of the fixing belt.

[0031] According to the ninth aspect, compared with a case where the outermost end of the guide surface of the second guide component is located at a position closer to the axial outside when the outermost end of the guide surface of the first guide component is maximally inclined than the steering roller and the first guide component is moved to the outside, the load exerted on the end of the serpentine fixing belt due to contact with the guide surface composed of the inclined surface of the guide component of the maximally inclined steering roller can be reduced.

[0032] In addition, according to the ninth aspect, compared with a situation where the outermost end of the guide surface of the second guide component is located at a position closer to the inner side in the axial direction when the first guide component is moved to the outer side and the outermost end of the guide surface of the second guide component is inclined to the maximum extent than the steering roller, the increase in the load applied to the end of the serpentine fixing belt due to contact with the guide surfaces of the fixed second guide component can be avoided.

[0033] According to the tenth aspect, compared with a case where the guide surface of the second guide member is a vertical surface, it is possible to suppress the oil from being circulated around the outer peripheral surface of the fixing belt due to the fixing belt passing through the second guide member.

[0034] According to the eleventh aspect, in the fixing device, it is possible to suppress the oil from being entangled in the outer peripheral surface of the fixing belt when the fixing belt passes through the guide member, and it is possible to suppress fixing unevenness and image quality degradation caused by the oil entanglement. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the image forming apparatus according to Embodiment 1;

[0036] Figure 2 is a schematic diagram of the fixing device of Embodiment 1;

[0037] Figure 3 (A) is Figure 2 A schematic side view of a steering roller and a guide member in a fixing device of Figure 3 (B) is an enlarged view of a guide component in the steering roller of (A);

[0038] Figure 4 (A) means Figure 2 A conceptual diagram showing the relationship between the components of the fixing device. Figure 4 (B) means Figure 3 An enlarged view of a state in which a steering roller and a guide member hold the fixing belt;

[0039] Figure 5 (A) means Figure 4 Conceptual diagram of the state of the fixing belt snaking in the fixing device. Figure 5 (B) is an enlarged view showing a state in which a steering roller and a guide member tilted by the meandering of the fixing belt hold the fixing belt;

[0040] Figure 6 is a schematic diagram of a fixing device according to Embodiment 2;

[0041] Figure 7 Yes means Figure 6 A conceptual diagram of the relationship between the components of the fixing device;

[0042] Figure 8 It means in Figure 6 A conceptual diagram of a state in which a fixing belt in a fixing device is snaking;

[0043] Fig. 9 Yes means Figure 8 An enlarged view of a state in which each holding member and a guide member of each holding member in the fixing device holds the fixing belt;

[0044] Fig.10 (A) is an enlarged view showing a modified example of the guide surface of the guide member, Fig.10 (B) means Fig.10(A) is an enlarged view of a state in which a steering roller provided with a guide member holds a fixing belt;

[0045] Fig.11 (A) is a schematic side view showing a steering roller in a fixing device and a guide member of a comparative object, Fig.11 (B) means Fig.11 (A) is a schematic side view of a state in which a steering roller and a guide member of a comparative object are moved by a meandering fixing belt;

[0046] Fig.12 This means that the fixing belt passes through Fig.11 Schematic diagram of oil entering the outer peripheral surface of the fixing belt due to the steering roller of the fixing belt and the guide member of the comparative object. DETAILED DESCRIPTION

[0047] Next, a mode for carrying out the present invention will be described.

[0048] Implementation method 1.

[0049] Figure 1 Detailed Description of the Invention An image forming apparatus 10 according to Embodiment 1 of the present invention is shown in FIG. Figure 2 Detailed Description of the Preferred Embodiment 1 shows a fixing device 5A according to the first embodiment.

[0050] In this specification and the accompanying drawings, substantially the same components are marked with common symbols. In addition, in this specification, repeated descriptions of the same components are omitted. Furthermore, in the accompanying drawings, in order to ensure ease of understanding, illustrations other than those required for the description are generally omitted.

[0051] (1) Structure of Image Forming Apparatus

[0052] The image forming apparatus 10 is an apparatus that forms an unfixed image corresponding to image information input from the outside on a paper 9 as an example of a recording medium.

[0053] like Figure 1 As shown, the image forming apparatus 10 has a housing 11 having a desired appearance. The image forming apparatus 10 is configured such that an image forming unit 20 , a paper supply device 40 , a paper conveying device 45 , a fixing device 5A, etc. are arranged in the internal space of the housing 11 .

[0054] Figure 1 The dashed line in denoted a main conveying path for conveying the paper 9 by the paper conveying device 45 in the housing 11 .

[0055] The image forming section 20 is a section that forms a toner image made of toner as a developer and transfers the image onto the paper 9 .

[0056] The image forming unit 20 in Embodiment 1 is configured as an image forming unit using an electrophotographic method and 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.

[0057] The photosensitive drum 21 is an example of an image holding unit and is a drum-shaped photosensitive body having a photosensitive layer serving as an image forming surface or an image holding surface. The photosensitive drum 21 rotates in the direction indicated by arrow A by receiving power from a driving device (not shown).

[0058] The charging device 22 is a device for charging the outer peripheral surface (image forming surface) of the photosensitive drum 21 to a desired surface potential. As the charging device 22, for example, a device having a charging member in the form of a roller that contacts the image forming surface of the outer peripheral surface of the photosensitive drum 21 and is supplied with a charging current is used.

[0059] The exposure device 23 is a device that irradiates the outer peripheral surface of the charged photosensitive drum 21 with light corresponding to the image information and exposes it to form an electrostatic latent image. The exposure device 23 operates by receiving an image signal generated by performing predetermined processing on image information input from the outside by an image processing unit (not shown) or the like. The image information is, for example, information related to images such as characters, graphics, photos, and patterns.

[0060] 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 (for example, black) to visualize it as a toner image of a predetermined color. As the developer, for example, a two-component developer containing a toner and a carrier is used.

[0061] The transfer device 25 transfers the unfixed toner image formed on the outer peripheral surface of the photosensitive drum 21 onto the paper 9. The transfer device 25 includes a transfer member in the form of a roller or the like that contacts the outer peripheral surface of the photosensitive drum 21 and is supplied with a transfer current.

[0062] A portion where the transfer device 25 faces the photosensitive drum 21 serves as a transfer position TP where an unfixed toner image is transferred.

[0063] The cleaning device 26 is a device that removes unnecessary toner, paper dust, and other unnecessary substances adhering to the outer peripheral surface of the photosensitive drum 21 to clean the outer peripheral surface of the photosensitive drum 21 .

[0064] 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 delivers it at a predetermined timing.

[0065] The paper supply device 40 is configured by arranging devices such as a container 41 for accommodating the paper 9 and a feeder 43 for feeding out the paper 9 one by one.

[0066] In the first embodiment, two containers 41A and 41B are used as the container 41, and two delivery devices 43A and 43B are used as the delivery device 43. The container 41A contains paper 9A, and the container 41B contains paper 9B. The paper 9A and the paper 9B are, for example, paper of different sizes.

[0067] The paper 9 may be any sheet-shaped recording medium as long as it can be conveyed in the housing 11 and can transfer and fix an unfixed toner image. As long as the recording medium satisfies the above conditions, its material, form, etc. are not particularly limited.

[0068] In the image forming apparatus 10 , recording media such as plain paper, coated paper, film, thick paper, etc. cut into a predetermined size, and recording media such as envelopes are used as the paper 9 .

[0069] The paper transport device 45 is a device that transports the paper 9 to a desired location within the housing 11 .

[0070] The paper conveying device 45 has a supply path, a relay path, an ejection path, and the like. The supply path is a path for conveying 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 for conveying the paper 9 from the transfer position TP in the image forming unit 20 to the fixing device 5A. The ejection path is a path for conveying the paper 9 from the fixing device 5A to the ejection port 12 provided in the side portion of the housing 11 or the like.

[0071] The paper conveying device 45 is composed of a plurality of conveying roller pairs 46, a conveying path member (not shown), and the like. The conveying roller pair 46 is a pair of conveying rollers that sandwich and convey the paper 9. In the first embodiment, for example, six conveying roller pairs 46a to 46f are used. The conveying path member is a member that forms a conveying space for the paper 9 and guides the paper 9 to a conveying destination.

[0072] The fixing device 5A is a device that fixes an unfixed image on the paper 9. The unfixed image is a toner image formed and transferred by the image forming unit 20.

[0073] like Figure 1 , Figure 2 As shown, the fixing device 5A according to the first embodiment is configured by arranging devices such as a heating rotating body 51 and a pressing rotating body 61 in an internal space of a housing 50 .

[0074] The housing 50 is provided with an introduction port 50 a for introducing the paper 9 and an exit port 50 b for ejecting the fixed paper 9 .

[0075] The fixing device 5A is configured such that the heating rotating body 51 and the pressing rotating body 61 are in contact and rotated, and the contacting portion is constituted as a fixing processing section FN. The fixing processing section FN is a section that performs a fixing process for applying heat and pressure to the paper 9 and the toner image passing through the fixing processing section FN, and is also called a fixing nip section.

[0076] The details of the fixing device 5A will be described later.

[0077] (2) Operation of Image Forming Device

[0078] The image forming apparatus 10 performs basic image formation as follows.

[0079] In the image forming apparatus 10, when a control unit (not shown) receives an operation command for forming an image, the image forming unit 20 performs charging, exposure, development, and transfer operations. In the image forming apparatus 10, the paper supply device 40 and the paper conveying device 45 also perform paper feeding operations.

[0080] Thus, 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. On the other hand, in the paper supply device 40, the desired paper 9 (9A, 9B) is fed out and supplied to the transfer position TP of the image forming unit 20 via the supply path of the paper conveying device 45.

[0081] 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.

[0082] In the image forming unit 20 , the cleaning operation of the cleaning device 26 is performed while the photosensitive drum 21 is rotating.

[0083] Thus, the image forming surface of the photosensitive drum 21 is cleaned by the cleaning device 26 at a time including after the toner image is transferred.

[0084] Next, in the image forming apparatus 10, the paper 9 to which the toner image is transferred is conveyed to the fixing device 5A via a relay path of the paper conveying device 45. In the relay path, the paper 9 is fed out while being sandwiched between the rotating photosensitive drum 21 and the transfer device 25.

[0085] In the fixing device 5A, as shown in FIG. Figure 2 As shown, a fixing operation is performed in which the paper 9 (9A, 9B) to which the toner image 92 is transferred is subjected to a fixing process in the fixing process section FN.

[0086] Thus, in the fixing device 5A, when the unfixed toner image 92 on the paper 9 is introduced and passes through the fixing process section FN, it is heated under pressure and fixed to the paper 9 .

[0087] Next, in the image forming apparatus 10 , the fixed paper 9 is discharged from 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 .

[0088] As a result, the paper 9 is fed out by the transport roller pair 46 e and stored in a paper discharge storage section (not shown) provided in a part of the housing 11 .

[0089] Through the above series of operations, the basic image forming operation of forming a monochrome image on one side of a sheet of paper 9 is completed.

[0090] (3-1) Structure of Fixing Device

[0091] Next, the fixing device 5A will be described in detail.

[0092] like Figure 2 As shown, the fixing device 5A uses a belt-nip type heating unit as the heating rotating body 51. In addition, the fixing device 5A uses a pressure roller 62 as an example of a pressing roller configured as a roller type as the pressing rotating body 61.

[0093] The heating rotating body 51 includes a fixing belt 52 , three holding members 53 , 54 , and 55 that rotatably hold the fixing belt 52 , an oil coating device 57 , and the like.

[0094] The three holding members are the heating roller 53, the contact member 54 and the steering roller 55. The fixing belt 52 is held in the direction indicated by the arrow B ( Figure 2 counterclockwise in the direction of rotation).

[0095] The fixing belt 52 is an endless belt whose outer peripheral surface 52 a contacts the surface of the paper 9 to which the toner image 92 is transferred in the fixing process section FN to perform a fixing process.

[0096] An endless belt having thermal conductivity, flexibility, and heat resistance is used as the fixing belt 52. In addition, a belt having a laminate structure in which an elastic layer and a release layer are sequentially formed on the outer peripheral surface of a cylindrical belt substrate is used as the fixing belt 52, for example.

[0097] As the tape substrate, a cylindrical member made of a synthetic resin such as polyimide or polyamide is used. As the elastic layer, a layer made of an elastic material such as silicone rubber is formed. As the anti-adhesive layer, a layer made of a resin material such as polytetrafluoroethylene is formed.

[0098] The heating roller 53 is an example of a rotating roller having the heating unit 56 . The heating roller 53 is a rotating roller that heats the fixing belt 52 while being heated by the heating unit 56 .

[0099] As the heating roller 53 , a roller body having a structure in which a surface layer 531 is laminated on the outer peripheral surface of a cylindrical roller base material 532 is used.

[0100] The roller base 532 is a cylindrical body made of a metal material such as aluminum. The roller base 532 is rotatably mounted to a part of the frame 50 via a bearing (not shown). The surface layer 531 is a layer having non-conductivity and good thermal conductivity.

[0101] As the heating means 56 , for example, a plurality of electric heat lamps arranged in the internal space of the roller base material 532 are used.

[0102] The contact member 54 is a member that contacts the inner peripheral surface 52 b of the fixing belt 52 at a fixed position to hold the fixing belt 52 .

[0103] As the contact member 54, Figure 4 As shown in FIG. 1 and the like, a structure in which a cushion 542 is provided on the lower surface of a cylindrical support 541 is used.

[0104] The support body 541 is a structure made of a metal material such as aluminum. The support body 541 is fixedly mounted on a part of the frame body 50. The cushion member 542 is a member having heat resistance, elasticity, and the like.

[0105] The contact member 54 includes a sliding sheet (not shown) disposed so as to be interposed between the outer surface of the cushion member 542 and the inner peripheral surface 52b of the fixing belt 52. One end of the sliding sheet is attached to the support body 541.

[0106] Furthermore, the contact member 54 is arranged to guide the side of the paper 9 to be fixed (at Figure 2 The left side in the middle is raised at the corner and the whole is slightly tilted backward.

[0107] like Figure 3 (A) and Fig.11 As shown, the steering roller 55 is a roller that stops the meandering of the fixing belt 52 by the action of a restoring force after the rotating shaft 551 is tilted according to the meandering of the fixing belt 52. Therefore, the steering roller 55 may also be called a meandering correction roller.

[0108] like Figure 3 As shown in (A), the steering roller 55 in the first embodiment includes a rotating shaft 551, a roller body 552 fixed to the rotating shaft 551, and first guide members 70A, 70B provided at portions of the rotating shaft 551 adjacent to both ends of the roller body 552.

[0109] The rotating shaft 551 is rotatably supported at both ends by bearings 553. The bearings 553 are mounted in mounting elongated holes (not shown) provided in the front surface portion 50c and the rear surface portion 50d of the frame body 50 so as to be movable by a predetermined distance in the substantially vertical direction Sr.

[0110] Thus, the rotating shaft 551 can move a predetermined distance in the substantially vertical direction Sr with respect to the long mounting hole (not shown) via the bearing 553 .

[0111] The bearing 553 is pulled upward with a certain elastic force F1 by the tension spring 554. The upper end of the tension spring 554 is attached to the attachment portion 502 provided on the front surface portion 50c and the rear surface portion 50d of the frame body 50.

[0112] Thus, the rotating shaft 551 is held in a state of being pulled upward by a certain elastic 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 the mounting slot (not shown).

[0113] The roller body 552 is a roller portion that holds the inner portion of the fixing belt 52 excluding the end portions including both ends 52 c and 52 d. The roller body 552 is fixed to the rotating shaft 551 and rotates together with the rotating shaft 551 .

[0114] The first guide members 70A and 70B are provided so as to be rotatable and movable in the axial direction with respect to the above-mentioned portion of the rotation shaft 551 of the steering roller 55 .

[0115] Other details of the switchback roller 55 and the first guide members 70A and 70B will be described later.

[0116] The oil application device 57 is an example of an oil application unit that applies oil to the inner peripheral surface 52 b of the fixing belt 52 .

[0117] The oil is applied to reduce the sliding resistance between the inner peripheral surface 52 b of the fixing belt 52 and the contact member 54 and to remove the wear powder on the inner peripheral surface 52 b of the fixing belt 52 .

[0118] As the oil coating device 57, an oil coating device composed of an impregnation member impregnated with oil, a holding member, and the like is used.

[0119] The holding member is a member that holds the impregnation member in contact with the inner peripheral surface 52b of the fixing belt 52. As the oil, for example, silicone oil or the like is used.

[0120] The oil coating device 57 is arranged to coat the portion of the inner peripheral surface 52b of the fixing belt 52 between the heating roller 53 and the steering roller 55. The oil is coated over the entire width direction (direction perpendicular to the rotation direction B) of the inner peripheral surface 52b of the fixing belt 52.

[0121] The pressure roller 62 as the pressure rotating body 61 is a roller that presses the fixing belt 52 from the outer peripheral surface 52 a side against the contact member 54 to form the fixing process portion FN.

[0122] like Figure 2 As shown, the pressure roller 62 is a roller structure in which an elastic release layer 64 is provided on the outer peripheral surface of a roller base material 63 having a cylindrical or cylindrical shape. Figure 2 Reference numeral 65 in the figure denotes shaft portions provided at both ends of the roller base material 63 .

[0123] The pressure roller 62 is supported by a support mechanism (not shown) so that the shaft portion 65 thereof can be displaced in a direction approaching or separating from the contact member 54 .

[0124] In addition, the pressure roller 62 applies a predetermined pressure toward the contact member 54 to the shaft portion 65 thereof by a pressure mechanism (not shown) at least during the fixing operation.

[0125] Furthermore, the pressure roller 62 receives power from a driving device (not shown) and is driven to rotate in the direction indicated by arrow C during a fixing operation or the like.

[0126] In the fixing device 5A, the fixing belt 52 rotates in the direction indicated by the arrow C as the pressure roller 62 rotates. In the fixing device 5A, the heating roller 53 may rotate in the direction indicated by the arrow B by receiving power from a driving device (not shown) at a predetermined time.

[0127] (3-2) Structure of the guide component of the comparison object

[0128] Here, before explaining the first guide members 70A and 70B of the steering roller 55 in the first embodiment, Fig.11 The first guide member 70X as a comparative example will be described.

[0129] like Fig.12 As shown in FIG. 1 , a first guide member 70X as a comparative object is provided as a structure including a main body portion 71 and a mounting portion 72 .

[0130] The main body 71 is a semi-disc-shaped portion, and is formed with a guide surface 73 and a movement guide surface 74 .

[0131] The attachment portion 72 is a portion that attaches the first guide member 70X so as to be rotatable relative to the rotation shaft 551 and movable by a predetermined distance in the axial direction.

[0132] The guide surface 73 in the main body 71 is a surface with which both ends 52c and 52d of the fixing belt 52 come into contact to guide the fixing belt 52. The guide surface 73 is formed in a portion of the main body 71 on the inner side facing the roller body 552.

[0133] The guide surface 73 of the first guide member 70X of the comparison object is formed along the thickness direction tb of the fixing belt 52 (see Fig.12 The thickness direction tb is a direction indicating the thickness of the portion of the fixing belt 52 held by the steering roller 55.

[0134] In addition, it can also be said that the guide surface 73 is formed as a plane that is orthogonal to the direction (axial direction) of the axis JL of the steering roller 55 .

[0135] 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 it moves outward from the rotation shaft 551 when the fixing belt 52 meanders.

[0136] The fixed guide jig 75 is formed of a sphere or a round rod and is in contact with the lower end portion of the moving guide surface 74 at ordinary times.

[0137] (3-3) Movement of the steering roller

[0138] The steering roller 55 provided with the first guide member 70X of the comparative object operates as follows.

[0139] Here, if Fig.11 As shown in (B), the description is given on the premise that the fixing belt 52 meanders so as to be displaced toward the front side indicated by the arrow M1.

[0140] In this case, the end 52 c 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 switchback roller 55 .

[0141] As a result, the first guide member 70X is pressed by the end 52c of the meandering fixing belt 52E, and moves in a manner slightly offset in the direction E1 to the outside (front side) of the rotating shaft 551. In addition, in the first guide member 70X at this time, when the first guide member 70X moves in the direction E1 to the outside of the rotating shaft 551, the movable guide surface 74 contacts and moves with the fixed guide clamp 75, thereby guiding the first guide member 70X to move downward.

[0142] Then, due to the downward movement of the first guide member 70X, the front end of the rotating shaft 551 at this time is in a state where it moves downward from the normal position via the bearing 553 as indicated by the arrow N.

[0143] The results, such as Fig.11 As shown in (B), the steering roller 55 as a whole is in a state where the front end thereof is lowered and tilted downward from the normal position (position of the axis JL).

[0144] When the steering roller 55 is tilted in this way, as the bearing 553 on the front side moves downward, the tension spring 554 is pulled downward, so the bearing 553 receives an upward elastic force F2 from the tension spring 554. The elastic force F2 at this time is greater than the normal elastic force F1.

[0145] Thereby, the inclined steering roller 55 moves upward so that the front end which has moved downward may return to the normal original position, and becomes a state which is not inclined.

[0146] At this time, the moving guiding surface 74 contacts and moves with the fixed guiding jig 75 , so that the first guide member 70X on the front side also moves upward and moves to the rear side of the rotating shaft 551 to return to the normal position.

[0147] The results, such as Fig.11 As shown in (B), the meandering fixing belt 52E is pressed by the guide surface 73 of the front first guide member 70X with a predetermined force Fa when one end 52c of the meandering fixing belt 52E passes through the switchback roller 55. As a result, the meandering fixing belt 52E as a whole moves backward and returns to a normal traveling position.

[0148] In this way, the switchback roller 55 functions to prevent the fixing belt 52 from meandering.

[0149] In addition, Fig.11 Even when the fixing belt 52 meanders so as to be displaced to the rear side indicated by the arrow M2 in (B), the meandering prevention function of the steering roller 55 can be similarly exhibited.

[0150] (3-4) Problems when using the guide component of the comparison object

[0151] On the other hand, in the fixing device to which the steering roller 55 provided with the first guide member 70X of the comparative object is applied, the following inconvenience may occur.

[0152] That is, Fig.12 As shown, a part 59m of the oil 59 applied to the fixing belt 52 may be wound around the outer peripheral surface 52a from the one end 52c of the fixing belt 52 while passing through the first guide member 70X of the comparative object in the switchback roller 55 and rotating.

[0153] The part 59 m of the wound-in oil 59 is generated when the oil 59 moves upward from the gap between the one end 52 c of the fixing belt 52 and the guide surface 73 of the first guide member 70X and spreads toward the end side area on the outer peripheral surface 52 a of the fixing belt 52 .

[0154] When such oil is drawn into the outer peripheral surface 52a of the fixing belt 52, part of the outer peripheral surface 52a of the fixing belt 52 is contaminated with oil, causing uneven fixing, or the fixing belt 52 slips, making the rotation unstable, and causing degradation in the quality of the fixed image.

[0155] In this case, the image quality may also be degraded in the image forming apparatus 10 including the fixing device.

[0156] (3-5) Structure of the First Guide Member in Embodiment 1

[0157] The first guide members 70A and 70B in the fixing device 5A are movably provided near both ends of the steering roller 55. The vicinity of both ends of the steering roller 55 in the first embodiment is a portion of the rotating shaft 551 adjacent to both ends of the roller body 552.

[0158] In addition, if Figure 3 As shown in (B), the first guide members 70A and 70B are substantially the same as the first guide member 70X of the comparative object, and are members including a main body portion 71 and a mounting portion 72 .

[0159] The main body 71 is a portion having a semi-disc shape, and is provided with a guide surface composed of an inclined surface 76 described later and a movement guide surface 74 .

[0160] The attachment portion 72 is a portion to which the first guide members 70A and 70B are attached so as to be rotatable relative to the rotation shaft 551 and movable by a predetermined distance in the directions E1 and E2 along the axial direction.

[0161] Furthermore, if Figure 3 As shown, each of the first guide members 70A and 70B includes a guide surface with which the two ends 52 c and 52 d of the fixing belt 52 come into contact, and a slope 76 that is inclined toward the outside in the longitudinal direction D of the switchback roller 55 .

[0162] In this case, the longitudinal direction D of the steering roller 55 is the axial direction of the rotation shaft 551. In addition, the outer side in the longitudinal direction D is the side from the center of the rotation shaft 551 in the axial direction toward both ends.

[0163] like Figure 3 As shown in FIG. 2 (B), the inclined surface 76 of the guide surface in the first embodiment is formed as an inclined surface inclined in a curved shape convex toward the axial direction outer side of the steering roller 55 .

[0164] The inclined surface 76 is roughly divided into a lower curved surface portion 76 a and an upper curved surface portion 76 b .

[0165] The lower curved surface portion 76a is a portion of the steering roller 55 on the side close to the roller body 552, and is an inclined surface portion that rises with a small curvature from the lower end 76d of the inclined surface 76. The upper curved surface portion 76b is a portion that is continuous from the upper end of the lower curved surface portion 76a, and is an inclined surface portion that rises to the upper end 76t of the inclined surface 76 with a curvature greater than that of the lower curved surface portion 76a.

[0166] The lower end 76 d of the inclined surface 76 is located at a position where the radial distance from the rotation axis 551 of the steering roller 55 is the same as the radial distance from the surface 552 a of the roller body 552 to the rotation axis 551 .

[0167] The lower curved surface 76a is a portion that occupies a range of 2 mm or less from the lower end 76d of the inclined surface 76 in the axial direction when viewed in the axial direction of the steering roller 55. The upper curved surface 76b is a portion that occupies a range of the inclined surface 76 excluding the lower curved surface 76a.

[0168] In this case, the lower end 76d of the inclined surface 76 is the end located most innerward in the axial direction of the inclined surface 76. In addition, the upper end 76t of the inclined surface 76 is the end located most outerward in the axial direction of the inclined surface 76.

[0169] Furthermore, the upper curved surface portion 76b may be a sloped surface that is inclined linearly.

[0170] (3-6) Movement of the steering roller provided with the first guide member

[0171] The switchback roller 55 provided with the first guide members 70A and 70B holds the fixing belt 52 as follows when the fixing belt 52 does not meander.

[0172] That is, Figure 3 (A) Figure 4 As shown in (A), the normal steering roller 55 is formed by connecting the two ends 52c and 52d of the fixing belt 52 with the lower curved surface 76a of the inclined surface 76 in each guide surface of the first guide member 70A and 70B (see Figure 3 The fixing belt 52 is maintained in a contact state with (B).

[0173] At this time, if Figure 4 As shown in (B), a portion of the fixing belt 52 including both ends 52c and 52d is in contact with a portion of the lower curved surface 76a of the inclined surface 76 in each guide surface of the first guide members 70A and 70B and is slightly bent upward (bent end portion 52e).

[0174] In addition, at this time, the bent end portion 52 e 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.

[0175] Thus, the oil 59 applied to the inner peripheral surface 52 b of the fixing belt 52 remains sealed between, for example, the curved end portion 52 e of the fixing belt 52 and the inclined surface 76 (particularly, the lower curved surface portion 76 a ) in the guide surface.

[0176] Therefore, in the fixing device 5A, even if the fixing belt 52 passes through the first guide members 70A and 70B of the steering roller 55, the guide surface 73 of the first guide member 70X of the comparison object is a perpendicular surface along the thickness direction tb of the fixing belt 52 (see Fig.12 ) can also prevent the oil 59 from being wound around the outer peripheral surface 52a of the fixing belt 52.

[0177] In addition, if Figure 5 As illustrated in FIG. 2A , the steering roller 55 provided with the first guide members 70A and 70B operates as follows when the fixing belt 52 meanders so as to be displaced to the front side indicated by the arrow M1 .

[0178] The operation at this time is similar to that in the case where the steering roller 55 of the first guide member 70X for comparison is provided (see Fig.11 (B)) Similar action content.

[0179] In this case, one end 52 c of the meandering fixing belt 52E strongly contacts the guide surface formed of the inclined surface 76 of the first guide member 70A located on the front side when passing through the switchback roller 55 .

[0180] As a result, the first guide member 70A is pressed by the end 52c of the meandering fixing belt 52E, and moves in a manner slightly offset in the direction E1 to the outside (front side) of the rotating shaft 551. In addition, in the first guide member 70A at this time, when the first guide member 70A moves to the outside of the rotating shaft 551, the movable guide surface 74 contacts and moves with the fixed guide clamp 75, thereby guiding the first guide member 70A to move downward.

[0181] Then, as the first guide member 70A moves downward, the front end of the rotating shaft 551 at this time is moved downward via the bearing 553 .

[0182] As a result, the steering roller 55 as a whole is in a state where the front end thereof is lowered and tilted downward from the normal position (see Fig.11 (B)).

[0183] When the steering roller 55 is tilted in this manner, the bearing 553 on the front side thereof receives an upward elastic force F2 (see Fig.11 (B)).

[0184] Thereby, the inclined steering roller 55 moves upward so that the front end that has moved downward returns to the original position at ordinary times, and becomes a non-inclined state.

[0185] At this time, the movable guide surface 74 contacts and moves with the fixed guide fixture 75, so that the first guide member 70A at the front side also moves upward and moves to the rear side of the rotation axis 551 and returns to the normal position (see Figure 3 (A)).

[0186] The results, such as Figure 5 As shown in (A), the meandering fixing belt 52E is pressed by the guide surface of the first guide member 70A formed by the inclined surface 76 with a predetermined force Fa when one end 52c of the meandering fixing belt 52E passes through the switchback roller 55. As a result, the meandering fixing belt 52E as a whole moves backward and returns to the normal travel position.

[0187] In this way, the switchback roller 55 functions to prevent the fixing belt 52 from meandering.

[0188] In addition, the fixing belt 52 is Figure 5 Even when the vehicle meanders in the manner of rearward displacement as indicated by arrow M2 in (A), the meandering prevention function of the steering roller 55 can be exerted in the same manner.

[0189] By the way, if Figure 5 As illustrated in (B), both ends 52c and 52d of the meandering fixing belt 52E are in a curved state (curved end portions 52g) that are in contact with a portion of the inclined surface 76 of each guide surface of the first guide members 70A and 70B and are slightly curved upward.

[0190] At this time, both ends 52c and 52d of the meandering fixing belt 52E are in contact with the upper end side of the lower curved surface 76a of the inclined surface 76 or a part of the upper curved surface 76b. In addition, the bent end 52g of the meandering fixing belt 52E is larger than the bent end 52e of the one end 52c of the fixing belt 52 at ordinary times (see FIG. Figure 4 (B) is much more curved.

[0191] Furthermore, the curved end portion 52g of the meandering fixing belt 52E receives a reaction force due to the curve and is pressed against the inclined surface 76 of the guide surface.

[0192] Thus, the oil 59 applied to the inner peripheral surface 52 b of the meandering fixing belt 52E is kept sealed between the curved end portion 52 g of the fixing belt 52E and the inclined surface 76 in the guide surface.

[0193] 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 switchback roller 55, the oil 59 is prevented from being entangled in the outer peripheral surface 52a of the fixing belt 52E.

[0194] Implementation method 2.

[0195] Figure 6 This is a schematic diagram of a fixing device 5B according to Embodiment 2 of the present invention.

[0196] The fixing device 5B has the same configuration as the fixing device 5A of the first embodiment except that the following changes are made: the heating roller 53 and the contact member 54 are provided with second guide members 81 and 85 , respectively.

[0197] (1-1) Structure of the Second Guide Member Provided on the Heating Roller

[0198] In the fixing device 5B, as shown in FIG. Figure 7 As shown, second guide members 81A and 81B are fixedly provided near both ends of the heating roller 53 .

[0199] The vicinity of both ends of the heating roller 53 is a portion that is inwardly moved a predetermined distance from both ends of the axial direction of the heating roller 53. The vicinity of both ends of the heating roller 53 is also a portion that does not hinder the normal rotation of the fixing belt 52 without meandering.

[0200] like Figure 7 As shown, the second guide members 81A and 81B have guide surfaces 82 with which both ends 52 c and 52 d of the fixing belt 52 can contact, respectively.

[0201] Each guide surface 82 of the second guide members 81A and 81B is an inclined surface inclined toward the outside in the axial direction of the heating roller 53 .

[0202] The guide surface 82 in the second embodiment is configured as a sloped surface obtained by reducing the sloped surface 76 of the guide surfaces of the first guide members 70A and 70B by narrowing the width in the axial direction of the heating roller 53 , for example.

[0203] In addition, if Figure 7 As shown, the second guide members 81A and 81B are provided so that at least a portion of each guide surface 82 thereof is located outside the guide surface formed by the inclined surface 76 of the first guide members 70A and 70B in the axial direction of the steering roller 55 .

[0204] At this time, the first guide members 70A and 70B are in a state where the fixing belt 52 is not meandering but is in a normal position where it rotates and travels in a normal position.

[0205] like Figure 7 As shown, the second guide members 81A and 81B in the second embodiment are provided so that the guide surfaces 82 thereof are entirely located on the outer side.

[0206] Furthermore, in the second guide members 81A and 81B, the outermost ends 82t of the guide surfaces 82 thereof have the following positional relationship.

[0207] That is, when the steering roller 55 is tilted to the maximum due to the meandering fixing belt 52E and the first guide members 70A and 70B move to the outside in the axial direction, the outer end 82t of each guide surface 82 is at the same position as the upper end 76t of the guide surface formed by the inclined surface 76 of the first guide members 70A and 70B.

[0208] exist Figure 7 In FIG. 1 , the dashed lines P1 and P2 are imaginary straight lines passing through the upper ends 76t of the guide surfaces formed by the inclined surfaces 76 of the first guide members 70A and 70B, respectively, when the steering roller 55 is not tilted and the first guide members 70A and 70B are both in their normal positions.

[0209] In addition, Figure 7 In FIG. 5 , the dashed lines P3 and P4 are imaginary straight lines passing through the outermost ends 76ts of the guide surfaces composed of the inclined surfaces 76 of the first guide members 70A and 70B when the steering roller 55 is tilted to the maximum and the first guide members 70A and 70B move to the outer sides.

[0210] Therefore, the outermost ends 82t of the guide surfaces 82 of the second guide members 81A and 81B are located on the dashed-dotted lines P3 and P4, respectively.

[0211] (1-2) Structure of the second guide member provided on the contact member

[0212] In addition, in the fixing device 5B, as shown in FIG. Figure 7 As shown, second guide members 85A and 85B are also fixedly provided near both ends of the contact member 54 .

[0213] The vicinity of both ends of the contact member 54 is a portion that is inwardly moved a predetermined distance from both ends of the contact member 54 in the longitudinal direction D. The vicinity of both ends of the contact member 54 is also a portion that does not hinder the normal rotation of the fixing belt 52 without meandering.

[0214] In addition, if Figure 6 or Figure 7As shown, the second guide members 85A and 85B are provided at a position upstream of the fixing process section FN in the rotation direction B of the fixing belt 52 . The second guide members 85A and 85B are attached to a part of the support body 541 of the contact member 54 so as to be fixed thereto.

[0215] like Figure 7 As shown, the second guide members 85A and 85B have guide surfaces 86 with which both ends 52 c and 52 d of the fixing belt 52 can contact, respectively.

[0216] Each guide surface 86 of the second guide members 85A and 85B is an inclined surface inclined outward in the longitudinal direction D of the contact member 54 .

[0217] The guide surface 86 in the second embodiment is configured as a slope obtained by reducing the slope 76 of the guide surfaces of the first guide members 70A and 70B by narrowing the width in the axial direction of the heating roller 53 , for example.

[0218] In addition, if Figure 7 As shown, the second guide members 85A and 85B are provided so that at least a portion of each guide surface 86 thereof is located outside the guide surface formed by the inclined surface 76 of the first guide members 70A and 70B in the axial direction of the steering roller 55 .

[0219] like Figure 7 As shown, the second guide members 85A and 85B in the second embodiment are provided so that the guide surfaces 86 thereof are all located on the outer side.

[0220] Furthermore, the outermost ends 86t of the guide surfaces 86 of the second guide members 85A and 85B have the following positional relationship.

[0221] That is, when the steering roller 55 is tilted to the maximum due to the meandering fixing belt 52E and the first guide members 70A, 70B move to the outside in the axial direction, the outermost end 86t of each guide surface 86 is located at the same position as the upper end 76t of the guide surface 76 of the first guide members 70A, 70B.

[0222] That is, similar to the outermost end 82t of each guide surface 82 of the second guide components 81A and 81B, the outermost end 86t of each guide surface 86 of the second guide components 85A and 85B is located on the single-point dashed lines P3 and P4 which are the above-mentioned imaginary straight lines.

[0223] In this case, the state in which the steering roller 55 is tilted to the maximum corresponds to the bearing 553 (see FIG. 1 ) of the steering roller 55 being contacted by the meandering fixing belt 52E and the guide surfaces of the first guide members 70A and 70B. Figure 3 (A)) can be moved to the lowest position.

[0224] (2) Operation of the fixing device provided with the first guide member and the second guide member

[0225] In the fixing device 5B, when the fixing belt 52 does not meander, the fixing belt 52 is held as follows.

[0226] First, the fixing belt 52 is held by the steering roller 55 provided with the first guide members 70A and 70B, similarly to the case of the fixing device 5A in the first embodiment.

[0227] Specifically, in the normal turning roller 55, as shown in FIG. Figure 7 As shown, the two ends 52c, 52d of the fixing belt 52 and the lower curved surface 76a of the inclined surface 76 in each guide surface of the first guide member 70A, 70B (see Figure 3 The fixing belt 52 is maintained in a contact state with (B).

[0228] Next, in the heating roller 53 provided with the second guide members 81A and 81B, as shown in FIG. Figure 7 As shown, the fixing belt 52 is held in a state where both ends 52 c and 52 d of the fixing belt 52 are not in contact with the guide surfaces 82 of the second guide members 81A and 81B.

[0229] In addition, in the contact member 54 provided with the second guide members 85A and 85B, as shown in FIG. Figure 7 As shown, the fixing belt 52 is held in a state where both ends 52 c and 52 d of the fixing belt 52 are not in contact with the guide surfaces 82 of the second guide members 81A and 81B.

[0230] In the normal fixing device 5B, a portion of the fixing belt 52 including both ends 52 c and 52 d is in substantially the same state as that of the fixing device 5A according to the first embodiment.

[0231] That is, a portion of the fixing belt 52 including both ends 52c and 52d is in contact with a portion of the lower curved surface 76a of the inclined surface 76 in each guide surface of the first guide member 70A and 70B and is slightly bent upward (bent end portion 52e) (see Figure 4 (B)).

[0232] In addition, at this time, the bent end portion 52 e 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.

[0233] Thus, the oil 59 applied to the inner peripheral surface 52b of the fixing belt 52 is kept sealed between the curved end portion 52e of the fixing belt 52 and the inclined surface 76 of the guide surface (see FIG. 5 ). Figure 4 (B)).

[0234] Therefore, even in the fixing device 5B, even if the fixing belt 52 passes through at least the first guide members 70A and 70B of the steering roller 55, the guide surface 73 of the first guide member 70X of the comparison object is a perpendicular surface along the thickness direction tb of the fixing belt 52 (see Fig.12 ) can also prevent the oil 59 from being wound around the outer peripheral surface 52a of the fixing belt 52.

[0235] In addition, in the fixing device 5B, as shown in FIG. Figure 8 As illustrated, when the fixing belt 52 meanders so as to be displaced toward the front side indicated by the arrow M1 , the fixing belt 52 is held as follows.

[0236] In this case, first, the steering roller 55 provided with the first guide members 70A and 70B is tilted once and then returns to the normal position in substantially the same manner as in the fixing device 5A of the first embodiment.

[0237] By the action of the steering roller 55, Figure 8 As shown, when one end 52c of the fixing belt 52E zigzagging forward passes the switchback roller 55, it is pressed backward by the guide surface of the first guide member 70A formed by the inclined surface 76 with a predetermined force Fa. As a result, the fixing belt 52E zigzagging forward moves backward as a whole and returns to a normal travel position.

[0238] In this way, the switchback roller 55 functions to prevent the fixing belt 52 from meandering.

[0239] In the fixing device 5B, similarly to the fixing device 5A of the first embodiment, even when the meandering fixing belt 52E passes through the first guide members 70A and 70B of the switchback roller 55 , the oil 59 is prevented from being entangled in the outer peripheral surface 52 a of the fixing belt 52 .

[0240] Specifically, if Fig. 9 As shown, one end 52c of the meandering fixing belt 52E is in a bent state (bent end portion 52g) that is in contact with a part of the inclined surface 76 in the guide surface of the first guide member 70A and is slightly bent upward.

[0241] The bent end portion 52g of the meandering fixing belt 52E receives a reaction force due to the bend and is pressed against the inclined surface 76 of the guide surface.

[0242] Thus, the oil 59 applied to the inner peripheral surface 52b of the meandering fixing belt 52E is kept

[0243] The fixing belt 52E is enclosed between the curved end portion 52g and the inclined surface 76 of the guide surface.

[0244] Therefore, also in the fixing device 5B, as described above, it is possible to suppress the oil 59 from being entangled in the outer peripheral surface 52 a of the meandering fixing belt 52E.

[0245] In addition, in the fixing device 5B, as shown in FIG. Figure 8 As shown in the example, the fixing belt 52E meandering forward contacts and passes through the guide surface 82 of the second guide member 81A located in front of the heating roller 53 and the guide surface 86 of the second guide member 85A located in front of the contact member 54 .

[0246] At this time, if Fig. 9 As shown in the example, the portion on the one end 52c side of the fixing belt 52E is in a curved state (curved end portion 52h) that is slightly curved upward while contacting a portion of the inclined guide surface 82 of the second guide member 81A in the heating roller 53.

[0247] In addition, at this time, if Fig. 9 As shown in the example, the portion on the one end 52c side of the fixing belt 52E is in a curved state (curved end portion 52i) that is slightly curved upward while contacting a portion of the inclined guide surface 86 of the second guide member 85A in the contact member 54.

[0248] At this time, the curved end portion 52 h and the curved end portion 52 i on the one end 52 c side of the fixing belt 52E are in substantially the same curved state if the inclined surfaces of the guide surface 82 and the guide surface 86 have the same structure.

[0249] At this time, the bent end 52h of the fixing belt 52E receives a reaction force due to the bending and is pressed against the inclined surface of the guide surface 82 of the second guide member 81A. Also, the bent end 52i of the fixing belt 52E receives a reaction force due to the bending and is pressed against the inclined surface of the guide surface 86 of the second guide member 85A.

[0250] Thus, the oil 59 applied to the inner peripheral surface 52 b of the meandering fixing belt 52E remains enclosed between the curved end portion 52 h of the fixing belt 52E and the inclined surface of the guide surface 82 when passing through the second guide member 81A.

[0251] Furthermore, the oil 59 applied to the inner peripheral surface 52 b of the meandering fixing belt 52E remains sealed between the curved end portion 52 i of the fixing belt 52E and the inclined surface of the guide surface 86 when passing through the second guide member 85A.

[0252] Therefore, also in the fixing device 5B, even if the serpentine fixing belt 52E sometimes passes through the second guide members 81A, 81B and the second guide members 85A, 85B in addition to the first guide members 70A, 70B, the oil 59 coated on the inner peripheral surface 52b of the fixing belt 52E can be prevented from winding around the outer peripheral surface 52a of the fixing belt 52E.

[0253] Furthermore, in the fixing device 5B, as shown in FIG. Figure 7 As shown, the second guide members 81A, 81B, 85A, 85B are provided so that at least a portion of the guide surfaces 82, 86 thereof are located outside the guide surfaces of the first guide members 70A, 70B in the axial direction of the steering roller 55.

[0254] Therefore, in the fixing device 5B, compared with the case where the second guide members 81A, 81B, 85A, 85B are arranged at the same axial position as the first guide members 70A, 70B in the steering roller 55, there is no possibility that the serpentine fixing belt 52E first contacts the guide surfaces 82, 86 of the second guide members 81A, 81B, 85A, 85B, thereby preventing the first guide members 70A, 70B in the steering roller 55 from moving axially outward by contacting the serpentine fixing belt 52E.

[0255] As a result, according to the fixing device 5B, the function of the steering roller 55 to correct the meandering of the fixing belt 52 is not impaired. In addition, even if the meandering fixing belt 52E passes through the guide surfaces of the first guide members 70A and 70B and the guide surfaces 82 and 86 of the second guide members 81A, 81B, 85A and 85B, the oil 59 is prevented from winding around the outer peripheral surface 52a of the fixing belt 52E.

[0256] In addition, if Figure 7 , Figure 8 As shown, the second guide components 81A, 81B, 85A, and 85B in the fixing device 5B are in the following relationship: the outermost ends 82t and 86t of their respective guide surfaces 82 and 86 are in the same position as the upper ends 76t of the guide surfaces of the first guide components 70A and 70B when they move in conjunction with the maximum tilt of the steering roller 55 caused by the serpentine fixing belt 52E.

[0257] Thus, in the fixing device 5B, the fixing belt 52E meandering forward may come into contact with the inclined guide surface of the first guide member 70A on the front side of the switchback roller 55 and move outward in the axial direction, so that the switchback roller 55 may be tilted to the maximum extent.

[0258] However, in this case, in the fixing device 5B, compared with the case where the outermost ends 82t, 86t of the guide surfaces 82, 86 are located axially outside of the upper ends 76t of the guide surfaces of the first guide members 70A, 70B when moving in conjunction with the maximum tilt of the steering roller 55, the following effects are achieved.

[0259] That is, in this case, if Figure 8 and Fig. 9 As shown, before the switchback roller 55 is tilted to the maximum, the one end 52c of the fixing belt 52E meandering toward the front side also contacts the guide surface 82 of the second guide member 81A and the guide surface 86 of the second guide member 85A.

[0260] Thus, in the fixing device 5B, even in the state before the steering roller is tilted to the maximum or in the state where it is tilted to the maximum, the load received by the end 52c of the fixing belt 52E snaking toward the front side and contacting the guide surface formed by the inclined surface 76 of the first guide component 70A on the front side of the tilted steering roller 55 can be reduced.

[0261] In addition, in this case, in the fixing device 5B, the following effect is achieved compared to the case where the outermost ends 82t, 86t of the guide surfaces 82, 86 are located axially inner than the upper ends 76t of the guide surfaces of the first guide members 70A, 70B when moving in conjunction with the maximum tilt of the steering roller 55.

[0262] That is, when the outermost ends 82t and 86t of the guide surfaces 82 and 86 are located at the inner side, if the steering roller 55 may be tilted to the maximum, the end 52c of the fixing belt 52E that meanders toward the front side may first strongly contact the guide surface 82 of the second guide member 81A fixed to the heating roller 53 and the guide surface 86 of the second guide member 85A fixed to the contact member 54. However, this possibility does not exist in the fixing device 5B.

[0263] Therefore, according to the fixing device 5B, the load caused by the one end 52c of the meandering fixing belt 52E contacting the guide surface 82 of the second guide member 81A fixed to the heating roller 53 and the guide surface 86 of the second guide member 85A fixed to the contact member 54 and thus being increased can be avoided.

[0264] Modifications

[0265] The present invention is not limited to the configuration examples shown in Embodiments 1 and 2, and necessary changes or combinations can be made without changing the gist of each invention described in the claims. Therefore, the present invention also includes the following modified examples.

[0266] The guide surface of the first guide member 70A, 70B is as follows Fig.10 As one example is shown in FIG. 7 , a linearly inclined slope 77 may be used.

[0267] The linearly inclined slope 77 may be a slope extending straight from the lower end 77d to the upper end 77t. The inclination angle α of the slope 77 with respect to the axis JL of the steering roller 55 may be set within a range of 30° to 75°, for example.

[0268] When the inclination angle α is less than 30°, the oil 59 may not be prevented from being wound around the outer peripheral surface 52a of the fixing belt 52. On the contrary, when the inclination angle α is greater than 75°, the fixing belt 52 may ride up along the inclined surface 77, and the end of the fixing belt 52 may exceed the threshold value of the elongation at break and crack.

[0269] At this time, the lower end 77d of the inclined surface 77 is the end located most in the axial direction of the inclined surface 77. In addition, the upper end 77t of the inclined surface 77 is the end located most in the axial direction of the inclined surface 77. Furthermore, the lower end 77d of the inclined surface 77 is located at a position where the distance from the rotating shaft 551 of the steering roller 55 in the radial direction is the same as the distance from the surface 552a of the roller body 552 in the radial direction of the rotating shaft 551.

[0270] The switchback roller 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 when the fixing belt 52 does not meander.

[0271] That is, Fig.10 As illustrated in (B) of FIG. 1 , the steering roller 55 in normal state holds the fixing belt 52 in a state where one end 52 c of the fixing belt 52 is in contact with a portion of the inclined surface 77 in the guide surface of the first guide member 70A.

[0272] At this time, if Fig.10 As illustrated in (B), a portion of the fixing belt 52 including the one end 52 c is in contact with a portion of the inclined surface 77 in the guide surface of the first guide member 70A and is slightly bent upward (bent end portion 52 k ).

[0273] In addition, at this time, the bent end portion 52 k 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.

[0274] Thus, the oil 59 applied to the inner peripheral surface 52 b of the fixing belt 52 is kept sealed between, for example, the bent end portion 52 k of the fixing belt 52 and the inclined surface 77 of the guide surface.

[0275] Therefore, in the fixing device using the first guide members 70A and 70B having the guide surface formed of the slope 77 , the oil 59 can be prevented from winding around the outer peripheral surface 52 a of the fixing belt 52 , similarly to the fixing devices 5A and 5B of the first and second embodiments.

[0276] The guide surface of the first guide member 70 may be an inclined surface formed by a curve having a single curvature. In addition, the guide surface of the first guide member 70 may be an inclined surface formed by combining a curved inclined surface and a linear inclined surface.

[0277] The second guide members 81 and 85 may be provided only on one of the heating roller 53 and the contact member 54 , and omitted on the other.

[0278] The guide surfaces 82 and 86 of the second guide members 81 and 85 may be inclined surfaces with a different structure from the inclined surface of the first guide member 70. In addition, at least one of the guide surfaces 82 and 86 of the second guide members 81 and 85 may be a vertical surface like the guide surface 73 of the first guide member 70X of comparison.

[0279] As for the fixing device of the present invention, the type and method of the heating unit 56, the type and number of retaining components other than the steering roller 55 that retains the fixing belt 52, etc. can also be changed, as long as the fixing device is provided with oil 59 applied to the inner circumferential surface 52b of the fixing belt 52 and a steering roller 55.

[0280] The oil coating device 57 may be provided at a different position or in different numbers.

[0281] In the first embodiment, etc., a configuration example of forming a monochrome image is shown as the image forming apparatus 10, but the image forming apparatus of the present invention may also be an apparatus that forms a multi-color image formed by combining multi-color toners. In addition, as far as the image forming apparatus of the present invention is concerned, its image forming method, transfer method, etc. are not particularly limited as long as it is an image forming apparatus to which the fixing device of the present invention is applied.

[0282] (Note) (((1)))

[0284] A fixing device, comprising:

[0285] Fusing belt;

[0286] a plurality of holding members for holding the fixing belt so as to be rotatable;

[0287] a pressing roller that presses the fixing belt from an outer peripheral surface side onto one of the holding members to form a fixing processing portion;

[0288] a coating unit that coats oil on an inner peripheral surface of the fixing belt; and

[0289] The first guide member is provided on at least one of the holding members, wherein a guide surface with which the end of the fixing belt contacts is constituted by an inclined surface inclined outward in the longitudinal direction. (((2)))

[0291] The fixing device according to (((1))), wherein:

[0292] The guide surface is an inclined surface inclined in a curved shape convex toward the outer side. (((3)))

[0294] The fixing device according to (((1))), wherein:

[0295] The guide surface is a linearly inclined slope. (((4)))

[0297] The fixing device according to any one of (((1))) to (((3))), wherein:

[0298] The at least one holding member is a steering roller that is tilted in accordance with the meandering of the fixing belt and then corrects the meandering by the action of a restoring force.

[0299] The first guide member is provided so as to be movable in the axial direction with respect to the rotation axis of the steering roller. (((5)))

[0301] The fixing device according to (((4))), wherein:

[0302] Another holding member among the plurality of holding members is a rotating roller having a heating unit,

[0303] A second guide member is fixed to the rotating roller, and at least a portion of a guide surface of the second guide member with which the end of the fixing belt contacts is located outside the guide surface of the first guide member in the axial direction of the switchback roller. (((6)))

[0305] The fixing device according to (((5))), wherein:

[0306] The outermost end of the guide surface of the second guide member is located at the same position as the outermost end of the guide surface of the first guide member when the steering roller is tilted to the maximum and the first guide member is moved to the outer side in the axial direction. (((7)))

[0308] The fixing device according to (((6))), wherein:

[0309] The guide surface of the second guide member is an inclined surface inclined outward in the axial direction of the rotating roller. (((8)))

[0311] The fixing device according to (((4))), wherein:

[0312] A second guide member is fixedly provided on all the retaining members except the steering roller among the plurality of retaining members, and at least a portion of a guide surface of the second guide member with which the end of the fixing belt contacts is located axially outside the guide surface of the first guide member in the steering roller. (((9)))

[0314] The fixing device according to (((8))), wherein:

[0315] The outermost end of the guide surface of the second guide member is located at the same position as the outermost end of the guide surface of the first guide member when the steering roller is tilted to the maximum and the first guide member is moved to the outer side in the axial direction. (((10)))

[0317] The fixing device according to (((9))), wherein:

[0318] The guide surface of the second guide member is an inclined surface inclined outward in the longitudinal direction of all the holding members. (((11)))

[0320] An image forming apparatus includes the fixing device described in any one of (((1))) to (((10))).

[0321] According to the fixing device of (((1))), compared with a case where the guide surface of the guide member for guiding the end of the fixing belt is a vertical surface along the thickness direction of the fixing belt, it is possible to suppress oil from being circulated around the outer peripheral surface of the fixing belt as the fixing belt passes through the guide member.

[0322] According to the fixing device of (((2))), compared with a case where the guide surface is an inclined surface inclined in a curved shape convex toward the inner side opposite to the outer side, an increase in load caused by the end of the fixing belt contacting the guide surface can be suppressed.

[0323] According to the fixing device of (((3))), compared with a case where the guide surface is a vertical surface, it is possible to suppress the oil from being entangled with the outer peripheral surface of the fixing belt.

[0324] According to the fixing device of (((4))), compared with a case where the first guide member is not provided on the steering roller, it is possible to correct the meandering of the fixing belt and suppress the oil from being wound around the outer peripheral surface of the fixing belt.

[0325] According to the fixing device of (((5))), compared with a case where the guide surface of the second guide member fixedly arranged on the rotating roller is arranged at the same axial position as the guide surface of the first guide member of the steering roller, it is possible to suppress the oil from winding around the outer peripheral surface of the fixing belt without damaging the function of the steering roller to correct the meandering of the fixing belt.

[0326] According to the fixing device of (((6))), the load applied to the end of the serpentine fixing belt due to contact with the guide surface consisting of the inclined surface of the first guide member of the maximally inclined steering roller can be reduced compared to a case where the outermost end of the guide surface of the second guide member is located at a position closer to the outside in the axial direction when the first guide member is moved to the outside and the outermost end of the guide surface of the first guide member is located at a position closer to the outside in the axial direction.

[0327] In addition, according to the fixing device of (((6))), compared with a case where the outermost end of the guide surface of the second guide component is located at a position closer to the inner side of the axial direction when the first guide component is moved to the outer side and the outermost end of the guide surface of the first guide component is inclined to the maximum extent relative to the steering roller, the increase in the load applied to the end of the serpentine fixing belt due to contact with the guide surface of the fixed second guide component can be avoided.

[0328] According to the fixing device of (((7))), compared with a case where the guide surface of the second guide member is a vertical surface, it is possible to suppress the oil from being entangled in the outer peripheral surface of the fixing belt due to the fixing belt passing through the second guide member.

[0329] According to the fixing device of (((8))), compared with a case where the second guide member fixedly provided on all retaining members other than the steering roller is provided at the same position in the length direction as the guide member of the steering roller, it is possible to suppress the oil from being wound around the outer peripheral surface of the fixing belt due to the fixing belt passing through all the guide members of the retaining members without damaging the function of the steering roller in correcting the meandering of the fixing belt.

[0330] According to the fixing device of (((9))), the load exerted on the end of the serpentine fixing belt due to contact with the guide surface consisting of the inclined surface of the guide member of the maximally inclined steering roller can be reduced compared to a case where the outermost end of the guide surface of the second guide member is located at a position closer to the axial outside when the first guide member is moved to the outside and the outermost end of the guide surface of the first guide member is located at a position closer to the outside in the axial direction.

[0331] In addition, according to the fixing device of (((9))), compared with a case where the outermost end of the guide surface of the second guide component is located at a position closer to the inner side of the axial direction when the first guide component is moved to the outer side and the outermost end of the guide surface of the first guide component is inclined to the maximum extent relative to the steering roller, the increase in the load applied to the end of the serpentine fixing belt due to contact with the guide surfaces of the fixed second guide component can be avoided.

[0332] According to the fixing device of (((10))), compared with a case where the guide surface of the second guide member is a vertical surface, it is possible to suppress the oil from being entangled in the outer peripheral surface of the fixing belt due to the fixing belt passing through the second guide member.

[0333] According to the fixing device of (((11))), in the fixing device, it is possible to suppress the oil from being entangled in the outer peripheral surface of the fixing belt due to the fixing belt passing through the guide member, and it is possible to suppress fixing unevenness and image quality degradation caused by the oil entanglement.

Claims

1. A fixing device, characterized in that: have: Fusing belt; a plurality of holding members for holding the fixing belt so as to be rotatable; a pressing roller that presses the fixing belt from an outer peripheral surface side onto one of the holding members to form a fixing processing portion; a coating unit for coating oil on the inner peripheral surface of the fixing belt; as well as The first guide member is provided on at least one of the holding members, wherein a guide surface with which the end of the fixing belt contacts is constituted by an inclined surface inclined outward in the longitudinal direction.

2. The fixing device according to claim 1, wherein: The guide surface is an inclined surface inclined in a curved shape convex toward the outer side.

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

4. The fixing device according to any one of claims 1 to 3, wherein: The at least one holding member is a steering roller that is tilted in accordance with the meandering of the fixing belt and then corrects the meandering by the action of a restoring force. The first guide member is provided so as to be movable in the axial direction with respect to the rotation axis of the steering roller.

5. The fixing device according to claim 4, wherein: Another holding member among the plurality of holding members is a rotating roller having a heating unit, A second guide member is fixed to the rotating roller, and at least a portion of a guide surface of the second guide member with which the end of the fixing belt contacts is located outside the guide surface of the first guide member in the axial direction of the switchback roller.

6. The fixing device according to claim 5, wherein: The outermost end of the guide surface of the second guide member is located at the same position as the outermost end of the guide surface of the first guide member when the steering roller is tilted to the maximum and the first guide member is moved to the outer side in the axial direction.

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 roller.

8. The fixing device according to claim 4, wherein: A second guide member is fixedly provided on all the retaining members except the steering roller among the plurality of retaining members, and at least a portion of a guide surface of the second guide member with which the end of the fixing belt contacts is located axially outside the guide surface of the first guide member in the steering roller.

9. The fixing device according to claim 8, wherein: The outermost end of the guide surface of the second guide member is located at the same position as the outermost end of the guide surface of the first guide member when the steering roller is tilted to the maximum and the first guide member is moved to the outer side in the axial direction.

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 the holding members.

11. An image forming device, characterized in that: A fixing device according to any one of claims 1 to 10 is provided.

Images