JP2019148618A - Fixation device and image formation apparatus - Google Patents

Abstract

To provide a fixation device which can suppress the rotation transmission failure to a cap from a fixation belt due to the leakage of a lubricant.SOLUTION: A fixation device includes: a rotatable endless fixation belt; a pressure member which forms a pressure region between the fixation belt and itself; a pressing member which presses the fixation belt to the pressure member by contacting the inner peripheral surface of the fixation belt via the lubricant in the pressure region; and a cap member 31 which is attached via an elastic member to the end in the rotational shaft direction of the fixation belt and rotates integrally with the fixation belt. The cap member 31 has a contact part 61a to which the end face in the rotational shaft direction of the fixation belt contacts. In the contact part 61a, a groove 71 for holding the lubricant leaking from the inner peripheral surface of the fixation belt is formed along the rotational shaft direction.SELECTED DRAWING: Figure 4A

Description

  The present invention relates to a fixing device that fixes a toner image onto a sheet and an image forming apparatus including the fixing device.

  In the image forming apparatus, the toner image formed on the surface of the image carrier is transferred to a sheet and then fixed on the sheet by being heated and pressed by a fixing device.

  As a fixing method of the fixing device, there is a sliding fixing method in which a fixing belt is driven and rotated by a press roller. The fixing belt is pressed against the press roller by a pressing pad. If the fixing belt stops during the fixing operation (heating), abnormal heat is generated. Therefore, as a safety measure, the fixing device of the sliding fixing type is equipped with a rotation detection mechanism that detects the presence or absence of rotation of the fixing belt. It is done. The rotation detection mechanism detects rotation of a cap that is put on the end of the fixing belt and rotates together with the fixing belt. An elastic member having a high coefficient of friction is interposed between the fixing belt and the cap so that the rotation of the fixing belt is reliably transmitted to the cap.

  On the other hand, a relatively low viscosity lubricant is interposed between the fixing belt and the pressing pad in order to reduce the sliding load between the fixing belt and the pressing pad. If the lubricant flows out from the inner peripheral surface of the fixing belt and adheres to the elastic member, the elastic member slips, and there is a possibility that rotation from the fixing belt to the cap is not smoothly transmitted. For this reason, it is necessary to control the flow of the leaked lubricant.

  Therefore, the fixing device described in Patent Literature 1 includes an elastic member that abuts against the inner peripheral surface of the fixing belt by thermal expansion and blocks the lubricant.

Japanese Patent Laid-Open No. 2006-118708

  However, in the fixing device described in Patent Document 1, depending on the thermal expansion state of the elastic member, it may not necessarily contact the inner peripheral surface of the fixing belt. Moreover, since it is necessary to add another member, there exists a problem that cost increases.

  In view of the above circumstances, an object of the present invention is to provide a fixing device capable of suppressing a rotation transmission failure from a fixing belt to a cap due to leakage of a lubricant and an image forming apparatus including the fixing device.

  In order to achieve the above object, the fixing device of the present invention includes a rotatable endless fixing belt, a pressure member that forms a pressure region between the fixing belt, and the fixing region in the pressure region. A pressing member that contacts the inner peripheral surface of the belt via a lubricant and presses the fixing belt against the pressure member; and an elastic member is attached to an end of the fixing belt in the rotation axis direction; A cap member that rotates integrally with the fixing belt, and the cap member has a contact portion with which an end surface of the fixing belt in the rotation axis direction contacts, and the contact portion includes the fixing belt. A groove for holding the lubricant leaking from the inner peripheral surface is formed along the rotation axis direction.

  In the fixing device of the present invention, the groove may be a planar shape of a triangular shape that tapers outwardly in the rotation axis direction of the fixing belt.

  An image forming apparatus according to the present invention includes: an image forming unit that forms a toner image on a sheet; and the fixing device described above that fixes the toner image formed by the image forming unit on a sheet. And

  According to the present invention, since the leaked lubricant can be stored in the groove in a stable state, the rotation of the fixing belt can be reliably transmitted to the cap member.

1 is a schematic diagram illustrating an outline of a color printer according to an embodiment of the present invention. 1 is a cross-sectional view illustrating a fixing device according to an embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating an end portion of a fixing device according to an embodiment of the present invention. FIG. 3 is a perspective view showing a cap member of the fixing device according to the embodiment of the present invention. FIG. 6 is a perspective view showing a groove formed in a cap member of the fixing device according to the embodiment of the present invention.

  Hereinafter, an image forming apparatus and a fixing device according to an embodiment of the present disclosure will be described with reference to the accompanying drawings.

  First, the overall configuration of a color printer 1 as an image forming apparatus will be described with reference to FIG. FIG. 1 is a front view schematically showing the internal configuration of the color printer. In the following description, the front side in FIG. 1 is the front side (front side) of the color printer 1. L and R shown in each figure indicate the left side and the right side of the color printer 1, respectively.

  The main body of the color printer 1 includes a paper feed cassette 3 that stores paper S, a paper feed device 5 that feeds the paper S from the paper feed cassette 3, and an image forming unit 7 that forms a full-color toner image on the paper S. A fixing device 9 for fixing the toner image on the paper S, a paper discharge device 11 for discharging the paper S, and a paper discharge tray 13 on which the discharged paper S is stacked. Further, a conveyance path 15 through which the sheet S is conveyed from the sheet feeding device 5 through the image forming unit 7 and the fixing device 9 to the sheet discharge device 11 is formed in the apparatus main body.

  Next, the fixing device 9 will be described with reference to FIGS. FIG. 2 is a cross-sectional view showing the fixing device, and FIG. 3 is a cross-sectional view showing an end portion of the fixing device.

  As shown in FIG. 2, the fixing device 9 includes an endless fixing belt 21, an IH heater 23 that heats the fixing belt 21, and a pressure member that forms a pressure region N between the fixing belt 21. The pressing roller 25, the pressing pad 27 as a pressing member that presses the fixing belt 21 against the pressing roller 25 in the pressure region N, and the fixing belt 21 are attached to the end of the fixing belt 21 via an elastic member 29. And a cap member 31 (see FIG. 3 and FIG. 4) that rotate integrally therewith.

  The fixing belt 21 is an endless belt having a predetermined inner diameter and a width longer than the width of the paper S. The fixing belt 21 is formed of a flexible material, and includes a base material layer, an elastic layer provided on the outer peripheral surface of the base material layer, and a release layer provided on the outer peripheral surface of the elastic layer. Yes. The base material layer is formed of a polyimide resin provided with a magnetic metal such as Ni or a metal such as Cu, Ag, or Al. The elastic layer is made of silicon rubber or the like. The release layer is formed of a PFA tube or the like.

  As shown in FIGS. 2 and 3, the holding member 41 passes through the hollow portion of the fixing belt 21. The holding member 41 is a square cylindrical member having a length shorter than the width of the fixing belt 21. As shown in FIG. 3, stays 43 are fitted to both ends of the holding member 41. A flange portion 45 and an annular groove 47 are formed in the stay 43 along the circumferential direction. The annular groove 47 is formed on the outer side in the axial direction of the fixing belt 21 with respect to the flange portion 45. The end portion of the holding member 41 is in contact with the flange portion 45. Both stays 43 are supported by a housing (not shown) of the fixing device 9.

  As shown in FIG. 2, the belt guide 51 is supported on one surface of the holding member 41, and the pressing pad 27 is supported on the other surface. The belt guide 51 has an arcuate cross-sectional shape along the inner peripheral surface of the fixing belt 21 and is formed of a material having a spring property. The belt guide 51 applies tension to the fixing belt 21 to stabilize the rotation trajectory of the fixing belt 21. The pressing pad 27 is a flat, substantially rectangular parallelepiped member that is long in the width direction of the fixing belt 21 and is formed of a resin such as a liquid crystal polymer. The outer peripheral surface of the pressing pad 27 is covered with a sliding sheet 53. The sliding sheet 53 is in contact with the inner peripheral surface of the fixing belt 21. A lubricant is infiltrated into the sliding sheet 53. The lubricant is a lubricant having a relatively low viscosity, such as fluorine grease or silicone oil. When the fixing belt 21 rotates, the sliding sheet 53 slides with respect to the fixing belt 21.

  The IH heater 23 includes a coil part, a coil bobbin that holds the coil part, and an arch core. The IH heater 23 is disposed so as to face the belt guide 51 with the fixing belt 21 interposed therebetween. A magnetic field is generated by applying a high-frequency AC voltage to the coil portion. Due to the action of this magnetic field, an eddy current is generated in the base material layer of the fixing belt 21, the base material layer generates heat, and the fixing belt 21 is heated. .

  The press roller 25 has a metal core, an elastic layer provided on the outer peripheral surface of the metal core, and a release layer provided on the outer peripheral surface of the elastic layer. The elastic layer is made of silicon rubber or the like. The release layer is formed of a PFA tube or the like.

  The press roller 25 is pressed against the pressing pad 27 with the fixing belt 21 interposed therebetween. As a result, a pressure region N is formed between the press roller 25 and the fixing belt 21. The press roller 25 is driven by a drive source (not shown) and rotates in the clockwise direction of FIG. When the press roller 25 rotates, the fixing belt 21 follows the press roller 25 and rotates in the counterclockwise direction opposite to the rotation direction of the press roller 25. As a result, the conveyed paper S passes through the pressurizing area N.

  The cap member 31 will be described with reference to FIGS. 2 and 3 and FIGS. 4A and 4B. FIG. 4A is a perspective view showing an end wall of the cap member, and FIG. 4B is a perspective view showing a groove. In FIG. 4A, only one groove 71 is depicted.

  The cap member 31 is a bottomed cylindrical resin molded product that covers the end of the fixing belt 21, and as shown in FIG. 3, a circular end wall 61 and a cylindrical shape along the outer periphery of the end wall 61. Outer peripheral wall 63. The end wall 61 has a contact portion 61 a with which the end surface of the fixing belt 21 contacts. The outer peripheral wall 63 faces the outer peripheral surface of the end portion of the fixing belt 21 with a predetermined gap. A through hole 65 is opened at the center of the end wall 61. The stay 43 fitted to the holding member 41 protrudes through the through-hole 65. The cap member 31 is rotatably supported between the flange portion 45 of each stay 43 and the C ring 67 attached to the annular groove 47.

  As shown in FIGS. 3 and 4A, a groove 71 cut along the axial direction of the rotating shaft of the fixing belt 21 is provided in the contact portion 61a of the end wall 61 with a predetermined interval in the circumferential direction. Is formed. Specifically, the groove 71 is formed along the side wall 65a of the through hole 65 from the contact portion 61a. As shown in FIG. 4B, the groove 71 has an isosceles triangular planar shape that is tapered outward in the axial direction and whose base angle is larger than the apex angle. As an example, when the diameter of the cap member 31 is 30 mm, the number of grooves 71 is 40, the length T of the grooves 71 in the radial direction is 1 mm, the depth D of the grooves 71 is 1 mm to 3 mm, and the opening width of the grooves 71 W is 1 mm, and the apex angle of the groove 71 is 20 to 90 degrees.

  An elastic member 29 is interposed in the gap between the outer peripheral surface of the end portion of the fixing belt 21 and the outer peripheral wall 63 of the cap member 31. The elastic member 29 is a cylindrical member and is formed of a material having a high friction coefficient such as silicon rubber. When the fixing belt 21 rotates as described above, the rotation of the fixing belt 21 is transmitted to the cap member 31 via the elastic member 29.

  The fixing operation of the fixing device 9 having the above configuration will be described. First, the press roller 25 is driven and rotated by a drive source, and the fixing belt 21 is driven to rotate in the clockwise direction of FIG. 2 opposite to the rotation direction of the press roller 25. At the same time, the IH heater 23 is driven to heat the fixing belt 21. The fixing belt 21 is heated to a predetermined control temperature (for example, 160 ° C.). After the fixing belt 21 is heated in this way, the sheet S on which the toner image is transferred is conveyed to the pressure area N. The sheet S is heated by the fixing belt 21 when passing through the pressurizing region N and is pressed by the press roller 25 and the fixing belt 21, so that the toner image is fixed on the sheet S. The sheet S on which the toner image is fixed is transported along the transport path 15 from the pressure area N.

  Further, when the fixing belt 21 rotates, the cap member 31 rotates through the elastic member 29. Then, a rotation detection mechanism (not shown) detects the rotation of the cap member 31, and it is determined that the fixing belt 21 is rotating normally.

  In the fixing operation, since the lubricant is applied to the outer peripheral surface of the pressing pad 27 (sliding sheet 53), the sliding load on the pressing pad 27 of the fixing belt 21 is reduced, and the fixing belt 21 is made smooth. Rotate. On the other hand, when the fixing belt 21 rotates, the end surface of the fixing belt 21 contacts the contact portion 61 a of the end wall 61 of the cap member 31. At this time, the lubricant adhered to the inner peripheral surface of the fixing belt 21 from the pressing pad 27 may leak from the end surface of the fixing belt 21 to the contact portion 61 a of the end wall 61. The leaked lubricant is guided and stored in the groove 71.

  As described above, according to the fixing device 9 of the present invention, the lubricant leaking from the end portion of the fixing belt 21 enters the respective grooves 71 and is stored. That is, since the lubricant does not flow out toward the elastic member 29, a situation in which the lubricant adheres to the elastic member 29 and slips with respect to the fixing belt 21 does not occur. Accordingly, since the rotation of the fixing belt 21 can be reliably transmitted to the cap member 31 via the elastic member 29, the rotation of the fixing belt 21 can be accurately detected by the rotation detection mechanism.

  In general, a liquid such as a lubricant acts to reduce the surface area by intermolecular force. The intermolecular force also acts between the liquid and the portion where the liquid comes into contact. In consideration of this, as shown in FIG. 4, the lubricant that has entered the innermost part of the groove 71 (the apex portion of the triangle) is intermolecular between the side walls 71a and the bottom wall 71b of the groove 71. It is easy to be held stable by force. That is, it can be said that the lubricant is more easily held as the area of the portion in contact with the lubricant is larger. On the other hand, the lubricant facing the opening of the groove 71 is relatively unstable because the intermolecular force from the opening side (air side) does not work. However, since the groove 71 is formed along the rotation axis direction and is drawn into the back side of the groove 71 by the intermolecular force of the lubricant that has entered the back of the groove 71, the lubricant is stably held in the groove 71. Can be kept.

  For this reason, it is preferable that the groove 71 has a large contact area with the lubricant and a small opening area. In the present embodiment, since the groove 71 has a triangular planar shape, the contact area is widened at the innermost part of the groove 71 (the apex angle portion of the triangle) to increase the force for retaining the lubricant. it can. Further, the planar shape of the groove 71 may be a rectangular shape or a trapezoidal shape that is long in the rotation axis direction. Alternatively, the end wall 61 may be formed by hollowing out the contact portion 61a in the rotation axis direction.

  Further, the lubricant flows out from the inner peripheral surface of the fixing belt 21 toward the outer side in the rotation axis direction of the fixing belt 21, and the groove 71 is formed from the contact portion 61 a along the rotation axis direction of the fixing belt 21. Yes. Accordingly, the lubricant that has flowed out can be smoothly guided to the groove 71.

  Further, since only the shape of the cap member 31 is changed, it is possible to prevent rotation failure of the fixing belt 21 due to leakage of the lubricant without adding another member.

  Furthermore, since the above description of the embodiments of the present invention describes preferred embodiments of the fixing device and the image forming apparatus according to the present invention, various technically preferable limitations may be imposed. However, the technical scope of the present invention is not limited to these embodiments unless specifically described to limit the present invention. That is, the above-described components in the embodiment of the present invention can be appropriately replaced with existing components and the like, and various variations including combinations with other existing components are possible. The description of the embodiment of the present invention described above does not limit the contents of the invention described in the claims.

1 Printer (image forming device)
7 Image forming unit 9 Fixing device 21 Fixing belt 25 Press roller (pressure member)
27 Press pad (pressing member)
29 Elastic member 31 Cap member 61a Contact part 71 Groove

Claims (3)

A rotatable endless fixing belt;
A pressure member that forms a pressure region with the fixing belt;
A pressing member that contacts the inner peripheral surface of the fixing belt via a lubricant in the pressing region and presses the fixing belt against the pressing member;
A cap member that is attached to an end of the fixing belt in the rotation axis direction via an elastic member and rotates integrally with the fixing belt;
The cap member has a contact portion with which an end surface of the fixing belt in the rotation axis direction contacts,
The fixing device is characterized in that a groove for holding the lubricant leaking from the inner peripheral surface of the fixing belt is formed in the contact portion along the rotation axis direction.   The fixing device according to claim 1, wherein the groove has a triangular planar shape that is tapered toward an outer side in a rotation axis direction of the fixing belt. An image forming unit for forming a toner image on paper;
An image forming apparatus comprising: the fixing device according to claim 1, wherein the toner image formed by the image forming unit is fixed on a sheet.

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