JP2016114867A - Fixation device and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixation device and an image formation device that reduce friction between a fixation belt and a depressure member and are excellent in durability.SOLUTION: A fixation device 18 has: a fixation belt 31 that is rotatably provided; a pressure rotor 32 that is rotatably provided, comes into pressure-contact with the fixation belt 31 to form a fixation nip 54 between the fixation belt 31 and the pressure rotor; and a depressure member 34 that depresses the fixation belt 31 from an inner side with respect to the pressure rotor 32. The depressure member 34 is formed of a material having rigidity, and a face opposing the pressure rotor 32 has a recess part 51 having a lubricant contained.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fixing device that fixes a toner image on a recording medium, and an image forming apparatus including the fixing device.

  2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus such as a copying machine, a printer, a fax machine, or a multifunction machine includes a fixing device that fixes a toner image on a recording medium such as paper. Some fixing devices include a fixing belt that is heated by a heat source, and a pressure member that presses the fixing belt to form a fixing nip.

  In the fixing device having such a configuration, the fixing belt is pressed against the pressure member by the pressing member. However, the driving torque of the fixing belt increases due to friction generated between the fixing belt and the pressing member, or the fixing belt. There is a problem that the pressing member wears.

  In order to solve such a problem, Patent Document 1 discloses a fixing device including a porous lubricant holding member that supplies a lubricant to the inner peripheral surface of the fixing belt in the vicinity of the pressing member. Patent Document 2 discloses a fixing device in which a pressing member is formed of an elastic material such as rubber containing a lubricant. Further, Patent Document 3 discloses a fixing device including a lubricant impregnated member between a fixing belt and a pressing member.

Japanese Patent Laid-Open No. 11-219052 JP 2005-37681 A JP 2012-168484 A

  However, in the fixing device described in Patent Document 1, the lubricant holding member is disposed in the vicinity of the pressing member. However, the tension is not applied to the fixing belt in the vicinity of the pressing member. There is a possibility that the contact with the pressing member becomes unstable, and the lubricant cannot be smoothly supplied to the fixing belt. Moreover, in the fixing device described in Patent Document 2, since the pressing member is formed of an elastic material, deformation and wear of the pressing member become a problem. Further, in the fixing device described in Patent Document 3, since the sliding sheet having a low surface roughness is provided on the surface of the lubricant-impregnated member, the configuration is complicated.

  In view of the above circumstances, an object of the present invention is to provide a fixing device and an image forming apparatus that reduce friction between a fixing belt and a pressing member and have excellent durability.

  In order to solve the above-described problems, a fixing device of the present invention includes a fixing belt that is rotatably provided, and a pressure that is rotatably provided and presses against the fixing belt to form a fixing nip with the fixing belt. A rotating member; and a pressing member that presses the fixing belt toward the pressure rotating member from the inside. The pressing member is made of a material having rigidity, and faces the pressing rotating member. The surface is characterized by having a recess containing a lubricant.

  By adopting such a configuration, the pressing member is not easily deformed, so that the fixing belt can always be pressed in a constant posture, and the fixing performance can be stabilized. In addition, since the fixing belt slides against the pressing member via the lubricant, the torque applied from the pressing member to the fixing belt can be reduced, the rotation of the fixing belt can be stabilized, and the wear of the fixing belt and the pressing member can be suppressed. it can.

  In the fixing device of the present invention, the pressing member may be formed of a porous heat-resistant resin, and pores inside the pressing member may communicate with the recess.

  By adopting such a configuration, the lubricant is also contained in the pores, so that the supply capability of the lubricant can be increased.

  In the fixing device of the present invention, the surface of the pressing member that faces the pressure rotator may have a convex portion with a spherical tip.

  By adopting such a configuration, the contact area between the pressing member and the fixing belt can be reduced, so that the friction between the pressing member and the fixing belt can be reduced, and the rotation of the fixing belt can be stabilized. The wear of the member can be suppressed.

  In the fixing device of the present invention, a sliding member made of a material having a lower coefficient of friction than the pressing member is interposed between the pressing member and the fixing belt. May be characterized in that a large number of through holes are formed.

  By adopting such a configuration, even when a material having a high friction coefficient is used as the material of the pressing member, the sliding resistance of the fixing belt can be reduced, so that the selection range of the material of the pressing member can be expanded. .

  The image forming apparatus of the present invention includes any one of the fixing devices described above.

  According to the present invention, friction between the fixing belt and the pressing member can be reduced and deformation and wear of the pressing member can be suppressed, so that the durability of the pressing member can be improved and the fixing operation can be stabilized.

1 is a schematic diagram illustrating an outline of a printer according to an embodiment of the present invention. 1 is a front sectional view of a fixing device according to a first embodiment of the present invention. 1 is a side sectional view of a fixing device according to a first embodiment of the present invention. FIG. 3 is a front sectional view of a pressing member of the fixing device according to the first embodiment of the present invention. FIG. 6 is a front sectional view of a pressing member of a fixing device according to a second embodiment of the present invention. FIG. 6 is a front sectional view of a pressing member of a fixing device according to a third embodiment of the present invention.

  The image forming apparatus and fixing device of the present invention will be described below with reference to the drawings.

  First, the overall configuration of the printer 1 (image forming apparatus) will be described with reference to FIG. FIG. 1 is a diagram schematically showing an outline of the printer 1. In the following, the front side of the paper in FIG. 1 is the front side (front side) of the printer, and the left and right directions will be described with reference to the direction viewed from the front of the printer.

  The printer 1 includes a box-shaped printer main body 2, and a paper feed cassette 3 that stores paper (recording medium) is accommodated in a lower portion of the printer main body 2. A paper discharge tray is disposed on the upper surface of the printer main body 2. 4 is provided. An upper cover 5 is attached to the upper surface of the printer main body 2 so as to be openable and closable on the side of the paper discharge tray 4, and a toner container 6 is accommodated below the upper cover 5.

  An exposure unit 7 composed of a laser scanning unit (LSU) is disposed below the paper discharge tray 4 above the printer body 2, and an image forming unit 8 is provided below the exposure unit 7. Yes. The image forming unit 8 is rotatably provided with a photosensitive drum 10 as an image carrier. Around the photosensitive drum 10, a charger 11, a developing device 12, a transfer roller 13, and a cleaning device are provided. The apparatus 14 is disposed along the rotation direction of the photosensitive drum 10 (see arrow X in FIG. 1).

  Inside the printer main body 2, a paper transport path 15 extending from the paper feed cassette 3 to the paper discharge tray 4 is provided. A paper feed unit 16 is provided at the upstream end of the conveyance path 15, and a transfer unit 17 configured by the photosensitive drum 10 and the transfer roller 13 is provided at a middle portion of the conveyance path 15. Is provided with a fixing device 18, and a paper discharge unit 19 is provided at the downstream end of the conveyance path 15. A reverse path 20 for double-sided printing is formed below the transport path 15.

  Next, an image forming operation of the printer 1 having such a configuration will be described. First, after the surface of the photosensitive drum 10 is charged by the charger 11, exposure corresponding to image data is performed on the photosensitive drum 10 by laser light from the exposure device 7 (see the two-dot chain line in FIG. 1). As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 10. Next, the electrostatic latent image is developed by the developing device 12 into a toner image with toner.

  On the other hand, the sheet taken out from the sheet cassette 3 by the sheet feeding unit 16 is conveyed to the transfer unit 17 in synchronization with the above-described image forming operation, and the toner image on the photosensitive drum 10 is transferred to the sheet by the transfer unit 17. Is transcribed. The sheet on which the toner image has been transferred is conveyed downstream in the conveyance path 15 and enters the fixing device 18 where the toner image is fixed on the sheet. The paper on which the toner image is fixed is discharged from the paper discharge unit 19 to the paper discharge tray 4. The toner remaining on the photosensitive drum 10 is collected by the cleaning device 14.

  Next, the fixing device 18 according to the first embodiment will be described with reference to FIGS. 2 is a front sectional view showing the fixing device, FIG. 3 is a side sectional view showing the fixing device, and FIG. 4 is a front sectional view of the pressing member.

  The fixing device 18 includes a fixing belt 31 that is rotatably provided, a pressure roller 32 (pressure rotating body) that is rotatably provided below the fixing belt 31, a heater 33 that heats the fixing belt 31, and a fixing belt. And a pressing member 34 that presses 31 against the pressing member 32 from the inside. The fixing belt 31, the heater 33, and the pressing member 34 are supported by the frame 35.

  The fixing belt 31 has a substantially cylindrical shape that is long in the front-rear direction, and is formed of a flexible material. The fixing belt 31 includes, for example, a base material layer, an elastic layer provided around the base material layer, and a release layer that covers the elastic layer. The base layer is made of a metal such as SUS or a resin such as PI (polyimide), the elastic layer is made of, for example, silicone rubber, and the release layer is made of, for example, PFA (tetrafluoroethylene-perfluoroalkyl). Vinyl ether copolymer) tube. In each figure, each layer (base material layer, elastic layer, release layer) of the fixing belt 31 is displayed without being particularly distinguished.

  Both ends of the fixing belt 31 are supported by a belt end holding member 41 supported by the frame 35. The belt end holding member 41 is provided with a holding part 42 having a semicircular arc shape whose sectional shape is convex upward, and a flange part 43 having a larger diameter than the holding part 42. The fixing belt 31 has a substantially upper half portion that slides along the outer peripheral surface of the holding portion 42, and both ends of the fixing belt 31 are restricted from moving in the front-rear direction by flange portions 43. Further, a thermistor 44 is disposed outside the fixing belt 31 so as to detect the surface temperature of the fixing belt 31.

  The pressure roller 32 has a substantially cylindrical shape that is long in the front-rear direction. The pressure roller 32 includes, for example, a columnar core material, an elastic layer provided around the core material, and a release layer that covers the elastic layer. The core material is made of, for example, a metal such as iron, the elastic layer is made of, for example, silicone rubber, and the release layer is made of, for example, a PFA tube. In each figure, each layer (core material, elastic layer, release layer) of the pressure roller 32 is displayed without being particularly distinguished.

  The pressure roller 32 is disposed below the fixing belt 31 and is supported so as to be rotatable in the clockwise direction in FIG. 2 about a rotation shaft 47 extending in the front-rear direction.

  The heater 33 is a heat source that radiates radiant heat radially, and is configured by, for example, a halogen heater. The heater 33 is disposed at a position above the hollow portion of the fixing belt 31 so as to extend in the longitudinal direction of the fixing belt 31, and both ends thereof are supported by the frame 35. The heater 33 is controlled to be turned on / off based on the surface temperature of the fixing belt 31 detected by the thermistor 44 so as to keep the surface temperature of the fixing belt 31 constant.

  As shown in FIG. 4, the pressing member 34 has a substantially rectangular parallelepiped shape that is long in the front-rear direction and has a horizontally long cross-sectional shape, and the lower surface is curved downward toward the downstream side in the rotation direction of the fixing belt 31. Yes. Moreover, it is curving in circular arc shape between a lower surface and both side surfaces. On the upper surface of the pressing member 34, a plurality of support columns 49 are erected in the center in the left-right direction with a predetermined interval in the front-rear direction.

The pressing member 34 is made of a porous material having rigidity, and a large number of recesses 51 are formed on the lower surface. The pore P formed inside the pressing member 34 communicates with the recess 51. As the material having rigidity, a material having a flexural modulus (10 ³ kgf / cm ² ) of 30 or more, preferably 35 or more can be used. As such a material, a foamed resin obtained by foaming a heat-resistant resin such as PI (polyimide), PEEK (polyetheretherketone), PPS (polyphenylene sulfide), PAI (polyamideimide), LCP (liquid crystal polymer) is used. can do. By using such a material, the deformation of the pressing member 34 can be suppressed. Further, the surface opening ratio of the recess 51 is preferably 30% to 50%, and the porosity of the pressing member 34 is preferably 30% to 50%.

  The recess 51 and the pores P contain a lubricant. As the lubricant, silicone oil, fluorine oil, or the like can be used. The lubricant contained in the recess 51 and the pores P can be supplied from a support column 49 provided on the upper surface of the pressing member 34, for example. In this case, some of the columns 49 are tubular, and the lubricant is supplied to the recesses 51 and the pores P through the columns 49 from an external supply source. The number of tubular struts 49, the supply timing, and the like depend on the image forming speed of the printer 1 and the like.

  2 and 3, the pressing member 34 is disposed below the heater 33 in the hollow portion of the fixing belt 31 so as to face the pressure roller 32, and is pressed downward by the support member 53. So that it is supported. The fixing belt 31 is pressed downward by the pressing member 34 to form a fixing nip 54 between the fixing belt 31 and the pressure roller 32. As described above, since the lower surface of the pressing member 34 is curved downward toward the downstream side in the rotation direction of the fixing belt 31, the length of the fixing nip 54 can be increased, and the fixing performance is stabilized. The support member 53 is a member having a U-shaped opening facing upward, and is formed of, for example, SECC (galvanized steel sheet). A positioning hole 55 is formed in the bottom portion of the support member 53 with a predetermined interval in the front-rear direction. A support column 49 of the pressing member 34 is inserted, and the pressing member 34 is positioned and supported by the support member 53. It has become so. Both ends of the support member 53 are supported by the frame 35.

  In the fixing device 18 having the above configuration, when the pressure roller 32 is rotated, the fixing belt 31 pressed against the pressure roller 32 by the pressing member 34 is driven to rotate in the direction opposite to the pressure roller 32. Between the fixing belt 31 and the pressing member 34, the lubricant contained in the recess 51 and the pores P oozes out on the surface of the pressing member 34, and the fixing belt 31 is pressed through the lubricant film. Slide against member 34. When the fixing belt 31 is heated by the heater 33, the paper and toner image passing through the fixing nip 54 are heated and pressurized, and the toner image is fixed on the paper.

  As described above, in the fixing device 18 of the present invention, since the pressing member 34 is not easily deformed, the fixing belt 31 can be pressed in a constant posture over a long period of time. Further, since the fixing belt 31 slides with respect to the pressing member 34 via the lubricant contained in the recess 51 and the pores P, the torque applied from the pressing member 34 to the fixing belt 31 is reduced, and the fixing belt 31 The rotation can be stabilized and wear of the fixing belt 31 and the pressing member 34 can be suppressed. Furthermore, since the lubricant contained in the pores P in the pressing member 34 is supplied to the recess 51, the supply capability of the lubricant can be increased. Furthermore, since the pressing member 34 is not easily deformed, a certain amount of lubricant can always be held in the pores P and the recesses 51. Furthermore, since the pressing member 34 is formed of a single component, the configuration of the fixing device 18 can be simplified.

  In the present embodiment, the pressing member 34 is formed of a porous material, but is not necessarily porous, and only the recess 51 capable of containing a lubricant may be formed on the surface. However, when a foamed resin is used as the material of the pressing member 34, the concave portion 35 and the pores P can be formed simultaneously.

  Next, the pressing member of the fixing device 18 according to the second embodiment will be described with reference to FIG. FIG. 5 is a side sectional view of the pressing member.

  The pressing member 34 is made of a porous material having rigidity, and a plurality of convex portions 61 are formed on the lower surface. The convex portion 61 is hemispherical, and a concave portion 51 communicating with the internal pore P is also formed on the surface of the convex portion 61. When a foamed resin is used as the material of the pressing member 34, the concave portion 35 and the pores P and the convex portion 61 can be molded simultaneously.

  In the second embodiment, since the apex of each convex portion 61 of the pressing member 34 contacts the fixing belt 31 between the fixing belt 31 and the pressing member 34, the contact area between the pressing member 34 and the fixing belt 31. The friction between the fixing belt 31 and the pressing member 34 can be reduced. Further, since the lubricant that has oozed out from the concave portion 51 on the lower surface of the pressing member 34 is held in the space between the convex portions 61, an appropriate amount of lubricant can be held on the lower surface of the pressing member 34. Therefore, the friction between the pressing member 34 and the fixing belt 31 can be further reduced.

  Next, a pressing member of the fixing device 18 according to the third embodiment will be described with reference to FIG. FIG. 6 is a side sectional view of the pressing member.

  The pressing member 34 is formed of a rigid porous material and includes a sliding member 63 that covers the outer peripheral surface. A plurality of protrusions 65 are formed on the upper surface of the pressing member 34 on the left and right sides of the support column 49 with a predetermined interval in the front-rear direction. The height of the protrusion 65 is lower than the height of the support column 49, and the upper surface is a flat surface.

  The sliding member 63 is a sheet-like member formed of a material having a lower friction coefficient than the pressing member 34, and for example, a sheet made of PEEK, fluororesin, or PI can be used. The sliding member 63 is formed with a plurality of fine through holes 64 penetrating in the thickness direction.

  The sliding member 63 is wound so as to cover the lower surface and both side surfaces of the pressing member 34, and both ends are locked to the protrusions 65 on the upper surface of the pressing member 34. The pressing member 34 having the sliding member 63 wound around the outer peripheral surface in this way is supported by the support member 53 by inserting each support column 49 into the positioning hole 55 formed at the bottom of the support member 53. At this time, the upper surface of each protrusion 65 comes into contact with the lower surface of the support member 53.

  In the third embodiment, the lubricant contained in the recess 51 of the pressing member 34 is supplied between the sliding member 63 and the fixing belt 31 through the through hole 64 of the sliding member 63. For this reason, even if a material having a high friction coefficient is used as the material of the pressing member 34, the fixing belt 31 slides with the sliding member 63, so that the torque applied to the fixing belt 31 can be reduced. Therefore, the selection range of the material of the pressing member 34 can be expanded. For example, a material that easily forms a recess on the surface, a material that easily foams into a porous shape, or the like can be selected regardless of the friction coefficient.

  In the embodiment of the present invention, the case where the configuration of the present invention is applied to the printer 1 has been described. However, in another different embodiment, the image forming apparatus other than the printer 1 such as a copying machine, a facsimile machine, and a multifunction machine is used. A configuration may be applied.

  Furthermore, since the above description of the embodiment of the present invention describes a preferred embodiment of the image forming apparatus according to the present invention, there may be various technically preferable limitations. 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)
18 Fixing Device 31 Fixing Belt 32 Pressure Rotator (Pressure Roller)
34 Pressing member 51 Concavity 61 Convex portion 63 Sliding member P Fine hole

Claims (5)

A fixing belt provided rotatably;
A pressure rotator that is rotatably provided and presses against the fixing belt to form a fixing nip with the fixing belt;
A pressing member that presses the fixing belt from the inside toward the pressure rotator, and
The fixing device is characterized in that the pressing member is made of a material having rigidity, and a surface facing the pressurizing rotator has a concave portion containing a lubricant.   The fixing device according to claim 1, wherein the pressing member is formed of a porous heat-resistant resin, and pores inside the pressing member communicate with the recess.   3. The fixing device according to claim 1, wherein a surface of the pressing member facing the pressure rotator has a convex portion having a spherical tip.   A sliding member made of a material having a lower coefficient of friction than the pressing member is interposed between the pressing member and the fixing belt, and a plurality of through holes are formed in the sliding member. The fixing device according to claim 1, wherein the fixing device is a fixing device.   An image forming apparatus comprising the fixing device according to claim 1.

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