JP2018049136A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device that fixes a toner image to a recording medium at a nip part at which a heated fixing belt is brought into pressure contact with a pressure roller rotated by a nip forming member, and to maintain stable rotation of the fixing belt in pressure contact with the nip forming member.SOLUTION: A fixing device 30 fixes a toner image t to a recording medium S by winding a fixing belt 33 to be stretched over a heating roller 31 and a nip forming member 32 and bringing the fixing belt into pressure contact with a pressure roller 34 driven to rotate by the nip forming member with the fixing belt therebetween at a nip part formed by the fixing belt and pressure roller. A guide member 35 guiding the fixing belt between the nip forming member and heating roller is provided separated from the nip forming member, and a member for sliding 36 is provided between at least a portion at which the nip forming member and fixing belt are in contact with each other.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, and a multifunction machine of these, and a fixing device that fixes a toner image formed on a recording medium to the recording medium in such an image forming apparatus. In particular, an endless fixing belt wound around the heating side member and the nip forming member, and a pressure roller that is rotationally driven in a state of being pressed against the nip forming member via the fixing belt. In the fixing device in which the pressure roller is brought into pressure contact with the fixing belt and rotationally driven, and the toner image is fixed on the recording medium in the nip portion where the fixing belt and the pressure roller are pressed, the fixing belt is a nip forming member. The frictional resistance between the fixing belt and the fixing belt is reduced by a simple configuration so that the fixing belt is stably rotated while being pressed against the nip forming member.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, a printer, a facsimile, and a composite machine of these, a toner image transferred to a recording medium is fixed on the recording medium by a fixing device.

  In such a fixing device, in order to save energy when fixing the toner image transferred to the recording medium to the sheet by heat and pressure, an endless fixing belt is connected to a heating roller and a heating roller. The toner image is wound around the side roller and rotated while the pressure roller is in pressure contact with the heating side roller via the fixing belt, and the toner image is formed in the nip portion where the fixing belt and pressure roller are pressed. Is used that is fixed to a recording medium.

  In recent years, in order to further save energy, for example, as shown in Patent Document 1, in place of the heating side roller, the pressure roller is pressed against the portion where the nip is formed. Using a non-rotating fixing member provided with an elastic member, the fixing belt is wound around the heating roller and the fixing member, and the pressure roller to be rotated is connected to the fixing belt via the fixing belt. The toner image is fixed on the recording medium at the nip portion where the fixing belt and the pressure roller are pressed by rotating the fixing belt together with the pressure roller while being pressed against the heat-resistant elastic member. Has been proposed.

  However, in the one disclosed in Patent Document 1, sliding resistance is generated due to friction between the heat-resistant elastic member and the fixing belt in the fixing member, and the rotation of the fixing belt becomes unstable, which adversely affects the formed image. There was a problem such as affecting.

JP 2008-46663 A.

  The present invention solves the above-described problems in a fixing device that fixes a toner image transferred to a recording medium onto the recording medium in an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a combination of these. It is to be an issue.

  In the present invention, an endless fixing belt that is wound around the heating side member and the nip forming member, and a rotary drive that is rotationally driven in a state of being pressed against the nip forming member via the fixing belt. In a fixing device, comprising: a pressure roller, wherein the pressure roller is pressed against the fixing belt and rotated, and a toner image is fixed on a recording medium at a nip portion where the fixing belt and the pressure roller are pressed. The frictional resistance between the belt and the nip forming member is reduced with a simple configuration so that the fixing belt is stably rotated in a state of being pressed against the nip forming member, and appropriate image formation can be stably performed. The problem is to do so.

  In the fixing device according to the present invention, in order to solve the above-described problems, an endless fixing belt wound around the heating side member and the nip forming member, and a fixing belt attached to the nip forming member. A pressure roller that is rotationally driven in a state of being in pressure contact therewith, and is driven to rotate by pressure-contacting the pressure roller to the fixing belt, and the toner in a nip portion where the fixing belt and the pressure roller are pressure-contacted In the fixing device for fixing an image on a recording medium, a guide member for guiding the fixing belt between the nip forming member and the heating side member is provided separately from the nip forming member, and at least the nip forming member and the fixing belt are provided. A sliding member was provided between the portions in contact with each other.

  As in the fixing device, a guide member for guiding the fixing belt between the nip forming member and the heating side member is provided separately from the nip forming member, and a sliding member is provided at least with the nip forming member. If it is provided between the portions that contact the fixing belt, the guide member prevents the fixing belt from contacting the nip forming member more than necessary, or from contacting the member that fixes the nip forming member, etc. The fixing belt is appropriately guided between the nip forming member and the heating side member, and the sliding member reduces sliding resistance due to friction between the fixing belt and the nip forming member. The fixing belt is stably rotated while being pressed against the nip forming member.

  Here, if at least the opposite corners of the nip forming member and the guide member are rounded, the resistance when the fixing belt moves between the nip forming member and the guide member is reduced, and the fixing belt is stable. And become rotated.

  Further, in the fixing device, when the fixing belt is bent at a portion where the nip forming member and the guide member face each other so that the nip forming member side is larger than the guide member side, the sliding member is not disposed. Compared with the case where the bending of the fixing belt in the guide member is large, the sliding resistance in the fixing belt can be reduced, and rotation failure in the fixing belt can be prevented.

  Further, when the sliding member is provided at least between the portions where the nip forming member and the fixing belt are in contact with each other, the sliding member is preferably attached so as to be wound around the nip forming member. With this configuration, when the fixing belt rotates, the sliding member while the fixing belt and the nip forming member are in contact with each other is brought into contact with the fixing belt and the nip forming member as the fixing belt rotates. It is possible to prevent the belt from being displaced from the portion or coming off while the fixing belt and the nip forming member are in contact with each other.

  In the fixing device, it is preferable to apply a lubricant to the inner peripheral surface of the fixing belt. In this way, the sliding resistance at the portion where the fixing belt and the nip forming member come into contact can be reduced, rotation failure in the fixing belt can be prevented, and wear of the fixing belt can be suppressed to improve durability. be able to.

  Here, as the lubricant, a silicon-based or fluorine-based lubricant having high heat resistance is desirable, and viscous grease is used so that the lubricant does not easily leak from the end of the fixing belt. In particular, it is preferable to use fluorine-based grease having excellent heat resistance.

  In addition, when applying the lubricant to the inner peripheral surface of the fixing belt as described above, irregularities are formed on the surface of the sliding member on the side in contact with the fixing belt, and the lubricant is held on the irregularities. It is preferable to do.

  In the fixing device, when the guide member for guiding the fixing belt between the nip forming member and the heating side member is provided separately from the nip forming member, the guide belt is moved more than the nip forming member. It is preferable that the heating side member is provided only at a position on the upstream side in the moving direction of the fixing belt with respect to the nip forming member. In this case, the fixing belt heated by the heating side member does not come into contact with the guide member before being guided to the nip forming member, and the fixing belt is directly guided to the nip forming member in a tensioned state. In addition to reducing the sliding resistance of the fixing belt, the heat of the fixing belt is prevented from being taken away by the guide member, and the heat of the fixing belt guided between the nip forming member and the pressure member is reduced. And the cost of the guide member is reduced.

  In the fixing device, the nip forming member is fixed to a fixing member formed in a groove shape, and the nip forming member is brought into contact with the fixing belt in this state, and the fixing belt is fixed to the fixing member from the heating side member. It is preferable that the nip forming member is guided so as not to contact the nip forming member. In this way, it is possible to prevent the fixing belt heated by the heating side member from coming into contact with the fixing member and taking heat away, or the fixing belt from being worn due to contact with the fixing member. In order to prevent the fixing belt from being brought into contact with the fixing member from the heating side member and guided to the nip forming member in this way, the fixing member formed in the groove shape is upstream of the nip forming member. It is preferable to make the length of this part shorter than the length of the downstream part.

  Further, when the guide member is provided at a position downstream of the nip forming member in the moving direction of the fixing belt as described above, the lubricant is held on the guide member so as to contact the inner peripheral surface of the fixing belt. It is preferable to provide a part. As described above, when the lubricant holding portion is provided on the guide member at the position downstream of the nip forming member in the moving direction of the fixing belt, the lubrication applied to the inner peripheral surface of the fixing belt from the uneven portion of the sliding member. Part of the lubricant is temporarily held in the lubricant holding part, or part of the lubricant thus held in the lubricant holding part is applied from the lubricant holding part to the inner peripheral surface of the fixing belt. As a result, the lubricant can be stably applied to the inner peripheral surface of the fixing belt.

  Further, when the lubricant holding portion is provided on the guide member as described above, the lubricant holding portion is provided so as to protrude from the guide member toward the fixing belt, and the lubricant holding portion is provided on the inner peripheral surface of the fixing belt. It is preferable to make it contact. In this way, the lubricant holding portion is appropriately brought into contact with the inner peripheral surface of the fixing belt, so that a part of the lubricant on the inner peripheral surface of the fixing belt can be properly held and reapplied, and the fixing is performed. The contact area between the belt and the guide member can be reduced, the sliding resistance of the fixing belt can be reduced, and the heat of the fixing belt can be suppressed from being taken away by the guide member.

  In the image forming apparatus of the present invention, the fixing device as described above is used as a fixing device for fixing the toner image formed on the recording medium to the recording medium.

  In the fixing device of the present invention, as described above, the guide member for guiding the fixing belt between the nip forming member and the heating side member is provided separately from the nip forming member, and at least the nip forming member and the fixing belt are provided. If a sliding member is provided between the contact portions, the guide member prevents the fixing belt from contacting the nip forming member more than necessary or from contacting the member that fixes the nip forming member. Thus, the fixing belt is properly guided between the nip forming member and the heating side member, and the sliding resistance due to friction between the fixing belt and the nip forming member is reduced by the sliding member. The fixing belt is stably rotated while being pressed against the nip forming member.

  As a result, in the image forming apparatus using the fixing device as described above, when the toner image formed on the recording medium is heated and fixed on the recording medium, the fixing belt is stably in a state of being pressed against the nip forming member. So that appropriate image formation can be stably performed.

1 is a schematic explanatory diagram illustrating an example of an image forming apparatus using a fixing device according to an embodiment of the present invention. FIG. 2 is a schematic explanatory view showing a fixing device according to the embodiment. FIG. 5 is a partial cross-sectional explanatory view showing a state in which a sliding member is provided in a portion between the nip forming member and the fixing belt in the fixing device according to the embodiment. FIG. 2 is a schematic explanatory diagram illustrating a first modification of the fixing device according to the embodiment. FIG. 6 is a schematic explanatory diagram illustrating a second modification of the fixing device according to the embodiment. FIG. 10 is a schematic explanatory diagram illustrating a third modification of the fixing device according to the embodiment.

  Next, a fixing device according to an embodiment of the present invention and an image forming apparatus using the fixing device will be specifically described with reference to the accompanying drawings. The fixing device and the image forming apparatus according to the present invention are not limited to those shown in the following embodiments, and can be appropriately modified and implemented without departing from the scope of the invention.

  In the image forming apparatus 1 of this embodiment, as shown in FIG. 1, four imaging cartridges 10A to 10D are mounted therein.

  Here, in each of the imaging cartridges 10A to 10D, the photosensitive member 11, the charging device 12 for charging the surface of the photosensitive member 11, and the surface of the charged photosensitive member 11 are exposed according to image information. A latent image forming device 13 for forming an electrostatic latent image on the surface of the photoconductor 11, a developing device 14 for supplying toner to the electrostatic latent image formed on the surface of the photoconductor 11 to form a toner image, A first cleaning device 15 that removes toner remaining after the toner image formed on the surface of the photoconductor 11 is transferred to the intermediate transfer belt 21 from the surface of the photoconductor 11 is provided.

  In the developing devices 14 in the imaging cartridges 10A to 10D, toners of different colors are accommodated, and black, yellow, magenta, and cyan toners are accommodated.

  In the image forming apparatus 1, in each of the imaging cartridges 10 </ b> A to 10 </ b> D, the surface of the photoreceptor 11 is charged by the charging device 12, and the surface of each photoreceptor 11 charged in this way is latent. The image forming apparatus 13 performs exposure according to the image information, and forms an electrostatic latent image according to the image information on the surface of each photoconductor 11. A toner of each color is supplied from the developing device 14 to the latent image, and a toner image of each color is formed on the surface of each photoconductor 11.

  Next, the toner image of each color formed on the surface of each photoconductor 11 in each of the imaging cartridges 10A to 10D in this way is stretched between the driving roller 20a and the rotating roller 20b and is driven to rotate. The toner image is sequentially transferred onto the intermediate transfer belt 21 by the primary transfer roller 22 to form a synthesized toner image on the intermediate transfer belt 21, and the toner image thus formed is transferred to the secondary transfer roller 21 by the intermediate transfer belt 21. The toner remaining on the surface of each photoconductor 11 after transfer is removed from the surface of each photoconductor 11 by the corresponding first cleaning device 15.

  On the other hand, the recording medium S accommodated in the image forming apparatus 1 is fed by the paper feed roller 24 and guided to the timing roller 25, and the timing roller 25 feeds the recording medium S to the intermediate transfer belt at an appropriate timing. 21 and the secondary transfer roller 23.

  Then, the toner image formed on the intermediate transfer belt 21 is transferred to the recording medium S by the secondary transfer roller 23, but remains on the intermediate transfer belt 21 without being transferred to the recording medium S. The toner is removed from the intermediate transfer belt 21 by the second cleaning device 26.

  Next, the recording medium S to which the toner image is transferred in this way is guided to the fixing device 30, and the unfixed toner image transferred to the recording medium S is fixed on the recording medium S by the fixing device 30, and then the toner The recording medium S on which the image is fixed is separated from the fixing device 30 and guided to the paper discharge roller 27, and the recording medium S on which the toner image is fixed is discharged by the paper discharge roller 27.

  In the fixing device 30 in this embodiment, as shown in FIGS. 1 and 2, a heating roller 31 provided with a heating device 31 a such as a halogen lamp is used as the heating side member 31. The fixing belt 33 is heated by 31. Note that the heating side member 31 is not limited to this, and although not shown, a method of heating the fixing belt 33 with IH or a method of heating with a resistance heating element can also be used.

  Here, in the fixing device 30 in this embodiment, as the fixing belt 33, for example, a belt having a base layer, an elastic layer, and a release layer is used, and the outer diameter thereof is arbitrary. Use about 100 mm. And as said base layer, it is comprised with a polyimide, SUS, Ni electroforming etc., for example, and the thing about 5-100 micrometers in thickness can be used. Moreover, as an elastic layer, it is desirable to use what was comprised with material with high heat resistance, such as silicone rubber and fluororubber, for example, and a thing with a thickness of about 10-300 micrometers can be used. Moreover, as a mold release layer, it is desirable to use the thing of the structure which provided mold release properties, such as a fluorine tube and a fluorine-type coating, for example, and a thing with a thickness of about 5-100 micrometers can be used.

  Then, the fixing belt 33 is wound around the heating roller 31 and the nip forming member 32 fixed and held on the fixing member 32a formed in a groove shape, and the nip forming is performed. A pressure roller 34 that is rotationally driven so as to sandwich the fixing belt 33 is pressed against the member 32, and tension is applied to the fixing belt 33 by an urging means (not shown). In this state, the fixing belt The toner image t is fixed to the recording medium S at the nip portion where the heated fixing belt 33 is pressed against the pressure roller 34 by the nip forming member 32 by rotating the pressure roller 33 together with the pressure roller 34. I have to.

  Here, as the nip forming member 32, for example, a resin made of a resin such as polyphenylene sulfide, polyimide, or a liquid crystal polymer, a metal such as aluminum or iron, a ceramic, or the like can be used.

  Further, as the pressure roller 34, for example, an elastic layer and a release layer are provided on the outer periphery of the core metal, and the outer diameter is not particularly limited, but one having about 20 to 100 mm is used. it can. Here, as said core metal, what was comprised with metals, such as aluminum and iron, for example, is desirable, a thing with a thickness of 0.1-10 mm with a pipe shape, a solid, and a cross-sectional shape is a three arrow shape. It is desirable to use a release layer that has been given release properties by, for example, a fluorine tube or a fluorine-based coating, and generally has a thickness of 5 Those having a thickness of ˜100 μm can be used.

  Further, in the fixing device 30 in this embodiment, as shown in FIGS. 2 and 3, a sliding member 36 is provided so as to include at least a portion between the nip forming member 32 and the fixing belt 33. Yes.

  In this embodiment, as the sliding member 36, as shown in FIG. 3, a fluorine-based resin 36b is provided so as to cover a sheet material 36a made of glass fiber. Concavities and convexities are formed on the surface of the moving member 36 on the side of the fixing belt 33, and a lubricant g using, for example, a fluorine-based grease having viscosity and excellent heat resistance is held on the concave and convex portions. Yes.

  In this way, the sliding member 36 suppresses the heat from the fixing belt 33 from escaping to the nip forming member 32, can increase the heat-resistant temperature in the nip forming member 32, and further the fixing belt 33. And the nip forming member 32 can be reduced to prevent the drive torque from increasing, and the lubricant g can be easily applied to the inner peripheral surface of the fixing belt 33.

  Here, the size of the unevenness formed on the surface of the sliding member 36 on the fixing belt 33 side is not particularly limited, but the function of holding the lubricant g in the uneven portion and the image caused by the unevenness of the sliding member 36. From the viewpoint of suppressing unevenness, it is desirable that the surface roughness Ra of the sliding member 36 be in the range of 1 to 50 μm.

  In the fixing device 30 in this embodiment, as shown in FIGS. 1 and 2, the fixing belt 33 is moved downstream in the moving direction from the position where the nip forming member 32 and the pressure roller 34 are in pressure contact with each other. The guide member 35 for guiding the fixing belt 33 between the nip forming member 32 and the heating roller 31 is separated from the nip forming member 32 on the fixing member 32a on the heating roller 31 side of the nip forming member 32. The guide member 35 is provided with a lubricant holding portion 35a for holding the lubricant g using the fluorine-based grease having the above-described viscosity and excellent heat resistance so as to protrude toward the fixing belt 33. The lubricant holding portion 35 a is provided in contact with the inner peripheral surface of the fixing belt 33.

  Here, when the lubricant holding portion 35 a is provided so as to contact the inner peripheral surface of the fixing belt 33 as described above, the lubricant holding portion 35 a is applied to the inner peripheral surface of the fixing belt 33 while being held by the uneven portion of the sliding member 36. A part of the lubricant g thus held is temporarily held in the lubricant holding part 35a, or a part of the lubricant g held in the lubricant holding part 35a in this way is this lubricant holding part 35a. The lubricant g can be stably applied to the inner peripheral surface of the fixing belt 33.

  Further, as described above, the lubricant holding portion 35a is provided so as to protrude from the guide member 35 toward the fixing belt 33, and only the lubricant holding portion 35a is brought into contact with the inner peripheral surface of the fixing belt 33 to thereby guide the guide member. If the fixing belt 33 is not brought into contact with other portions of the belt 35, the contact area between the fixing belt 33 and the guide member 35 can be reduced, and the sliding resistance of the fixing belt 33 can be reduced. The heat of the guide member 35 is appropriately prevented from being taken away.

  In the above-described embodiment, the lubricant holding portion 35 a is provided so as to protrude from the guide member 35 toward the fixing belt 33, and only the lubricant holding portion 35 a is brought into contact with the inner peripheral surface of the fixing belt 33. However, it is also possible to provide the lubricant holding portion 35a along the surface of the guide member 35 so that the fixing belt 33 contacts the guide member 35 and the lubricant holding portion 35a.

  As the material for the lubricant holding portion 35a, it is preferable to use a material having an excellent function of holding the lubricant g. For example, a highly heat-resistant fibrous member such as aramid fiber or fluorine fiber, silicon It is desirable to use a porous member having high heat resistance such as sponge.

  Further, in the fixing device 30 in the above-described embodiment, the nip forming member 32 and the pressure roller 34 are in pressure contact with the guide member 35 that guides the fixing belt 33 between the nip forming member 32 and the heating roller 31. The fixing belt 33 is provided only on the fixing member 32a on the heating roller 31 side of the nip forming member 32 on the downstream side of the position in the moving direction of the fixing belt 33. However, the fixing belt 33 is connected to the nip forming member 32 and the heating roller. The position where the guide member 35 that guides the vehicle 31 is provided is not limited to this.

  For example, as in the first to third modifications shown in FIGS. 4 to 6, the guide belt 35 is fixed to the fixing belt more than the position where the nip forming member 32 and the pressure roller 34 are pressed. 33 may be provided at positions on both the upstream side and the downstream side in the moving direction.

  Here, in the first modification shown in FIG. 4, the guide member 35 that guides the fixing belt 33 between the nip forming member 32 and the heating roller 31 is separated from the nip forming member 32, and the nip described above is used. Fixing is performed on the fixing member 32a on the downstream side in the moving direction of the fixing belt 33 from the position where the forming member 32 and the pressure roller 34 are in pressure contact with each other, and on the fixing member 32 a position where the nip forming member 32 and the pressure roller 34 are pressed. In addition to being provided below the fixing member 32a on the upstream side in the moving direction of the belt 33, the opposing corners of the nip forming member 32 and each guide member 35 have an R shape.

  As described above, when the opposing corners of the nip forming member 32 and each guide member 35 have an R shape, the resistance when the fixing belt 33 moves between the nip forming member 32 and the guide member 35 is reduced. The fixing belt 33 is rotated stably.

  In the second modified example shown in FIG. 5 as well, the guide member 35 that guides the fixing belt 33 between the nip forming member 32 and the heating roller 31 is provided, as in the first modified example shown in FIG. The nip forming member 32 is separated from the nip forming member 32 on the fixed member 32a on the downstream side in the moving direction of the fixing belt 33 from the position where the nip forming member 32 and the pressure roller 34 are in pressure contact with each other. Provided below the fixing member 32a on the upstream side in the moving direction of the fixing belt 33 from the position where the pressure roller 34 is in pressure contact, and opposite corners of the nip forming member 32 and each guide member 35 are formed in an R shape. Like to do.

  In the second modification shown in FIG. 5, the nip forming member 32 protrudes in the vertical direction of the fixing member 32 a, while the guide members 35 are not in contact with the nip forming member 32. The bending of the fixing belt 33 at each of the upper and lower ends of the nip forming member 32 is made larger than the bending of the fixing belt 33 at a portion of each guide member 35 facing the nip forming member 32.

  As described above, when the bending of the fixing belt 33 at the upper and lower ends of the nip forming member 32 where the sliding member 36 is disposed is increased, the nip forming member 32 of each guide member 35 where the sliding member 36 is not disposed. As compared with the case where the bending of the fixing belt 33 is increased at the portion opposed to the fixing belt 33, the sliding resistance of the fixing belt 33 can be reduced, and the rotation failure of the fixing belt 33 can be prevented.

  Also in the third modification shown in FIG. 6, as in the first modification shown in FIG. 4, the guide member 35 that guides the fixing belt 33 between the nip forming member 32 and the heating roller 31 is provided. The nip forming member 32 is separated from the nip forming member 32 on the fixed member 32a on the downstream side in the moving direction of the fixing belt 33 from the position where the nip forming member 32 and the pressure roller 34 are in pressure contact with each other. Provided below the fixing member 32a on the upstream side in the moving direction of the fixing belt 33 from the position where the pressure roller 34 is in pressure contact, and opposite corners of the nip forming member 32 and each guide member 35 are formed in an R shape. Like to do.

  In the third modification shown in FIG. 6, the sliding member 36 is attached so as to be wound around the nip forming member 32.

  In this way, when the sliding member 36 is attached so as to be wound around the nip forming member 32, the nip formation with the fixing belt 33 is performed when the fixing belt 33 is rotated by pressing the pressure roller 34 against the nip forming member 32. The sliding member 36 during contact with the member 32 may be displaced from a portion where the fixing belt 33 and the nip forming member 32 are in contact with each other, or may be peeled off while the fixing belt 33 and the nip forming member 32 are in contact with each other. Therefore, the sliding resistance of the fixing belt 33 can be stably and appropriately reduced, and the fixing belt 33 is rotated in a stable state.

  In the first to third modified examples, the opposing corners of the nip forming member 32 and the guide members 35 are R-shaped, but the corners are not necessarily R-shaped. . However, in this case, the resistance when the fixing belt 33 moves between the nip forming member 32 and the guide member 35 becomes high, and the rotation of the fixing belt 33 may not be stabilized.

  Further, as in the above-described embodiment, when the fixing belt 33 is wound around the heating roller 31 and the nip forming member 32, the diameter of the heating roller 31 is not particularly limited. The diameter of 31 is preferably 1.5 times or less, more preferably 1 time or less, of the length of the nip portion formed by the nip forming member 32 in the sheet conveyance direction. Thus, if the diameter of the heating roller 31 is reduced, the heat capacity can be reduced, the warm-up time can be shortened, and the energy saving performance can be improved.

  The image forming apparatus 1 is not limited to the one shown in FIG. 1, but may be another color type or a monochrome type image forming apparatus.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10A-10D Imaging cartridge 11 Photoconductor 12 Charging apparatus 13 Latent image forming apparatus 14 Developing apparatus 15 1st cleaning apparatus 20a Driving roller 20b Rotating roller 21 Intermediate transfer belt 22 Primary transfer roller 23 Secondary transfer roller 24 Paper feed Roller 25 Timing roller 26 Second cleaning device 27 Paper discharge roller 30 Fixing device 31 Heating roller (heating side member)
31a Heating device 32 Nip forming member 32a Fixing member 33 Fixing belt 34 Pressure roller 35 Guide member 35a Lubricant holding part 36 Sliding member 36a Sheet material 36b Fluororesin S Recording medium g Lubricant t Toner image

Claims (12)

  An endless fixing belt wound around the heating side member and the nip forming member, and a pressure roller that is rotationally driven in a state of being pressed against the nip forming member via the fixing belt, In a fixing device that presses the pressure roller against a fixing belt and rotationally drives the toner image to a recording medium at a nip portion where the fixing belt and the pressure roller are pressed, the fixing belt is a nip forming member. A guide member for guiding the heating side member is provided separately from the nip forming member, and a sliding member is provided at least between a portion where the nip forming member and the fixing belt are in contact with each other. Fixing device to do.   2. The fixing device according to claim 1, wherein at least opposing corner portions of the nip forming member and the guide member have an R shape.   3. The fixing device according to claim 1, wherein a bending of the fixing belt at a portion where the nip forming member and the guide member face each other is larger on the nip forming member side than on the guide member side. .   4. The fixing device according to claim 1, wherein the sliding member is attached so as to be wound around a nip forming member. 5.   5. The fixing device according to claim 1, wherein a lubricant is applied to an inner peripheral surface of the fixing belt. 6.   6. The fixing device according to claim 5, wherein the lubricant is fluorine-based grease.   7. The fixing device according to claim 5, wherein unevenness is formed on a surface of the sliding member on a side in contact with the fixing belt, and a lubricant is held in the uneven portion. .   8. The fixing device according to claim 1, wherein the guide member is provided only at a position downstream of the nip forming member in the moving direction of the fixing belt, and the heating side member is the nip forming member. The fixing device is provided at a position upstream of the member in the moving direction of the fixing belt.   9. The fixing device according to claim 8, wherein the nip forming member is in contact with the fixing belt while being fixed to a fixing member formed in a groove shape, and the fixing belt is in contact with the fixing member from the heating side member. And a fixing device that is guided to the nip forming member.   10. The fixing device according to claim 8, wherein a guide member provided at a position downstream of the nip forming member in the moving direction of the fixing belt is a lubricant holding portion that contacts the inner peripheral surface of the fixing belt. And a fixing device.   The fixing device according to claim 10, wherein the lubricant holding portion is provided so as to protrude from the guide member toward the fixing belt.   An image forming apparatus comprising a fixing device for fixing a toner image formed on a recording medium to a recording medium, wherein the fixing device according to any one of claims 1 to 11 is used. Forming equipment.

Images