JP2014174369A - Fixing belt, fixing device and image forming apparatus including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing belt capable of preventing leakage of lubricant, a fixing device and an image forming apparatus including the fixing device.SOLUTION: A fixing device includes a heat source and a nip part forming member 106 arranged inside a fixing belt 1, and a pressure roller 103 arranged outside the fixing belt 1. The fixing belt 1 is applied with lubricant on an inner peripheral surface 1a. The inner peripheral surface 1a of the fixing belt 1 has a part 1b with high smoothness and parts 1c with low smoothness formed thereon.

Description

  The present invention relates to a fixing device used in an electrostatic recording image forming apparatus such as a copying machine, a facsimile machine, and a printer, and more specifically, a recording medium that forms a nip portion with a pressure roller and passes through the nip portion. The present invention relates to a fixing belt for fixing a toner image to the toner.

  In recent years, market demands for energy saving and high speed have been increasing for image forming apparatuses such as printers, copiers, and facsimiles.

  In an image forming apparatus, an unfixed toner image is formed on a recording medium such as recording paper by an image transfer method or a direct method by an image forming process such as electrophotographic recording, electrostatic recording, or magnetic recording.

  As a fixing device for fixing an unfixed toner image, a contact heating method fixing device such as a heat roller method, a film heating method, and an electromagnetic induction heating method is widely used.

  As examples of such a fixing device, a belt-type fixing device and a surf fixing (film fixing) fixing device using a ceramic heater are known.

  The belt-type fixing device has the following three problems.

  Problem 1: In recent years, further reduction in warm-up time and first print time is desired. The warm-up time is the time required from a normal temperature state to a predetermined printable temperature (reload temperature) such as when the power is turned on. The first print time is a time from when a print request is received to when a print operation is performed through a print preparation and paper discharge is completed.

  Problem 2: With the increase in the speed of image forming apparatuses, the number of sheets to be passed per unit time has increased, and the required amount of heat has increased. Therefore, there is a problem that the amount of heat is insufficient (so-called temperature drop) particularly at the beginning of continuous printing.

  Problem 3: As a method for solving Problem 1, surf fixing using a ceramic heater has been proposed. With this method, it is possible to reduce the heat capacity and reduce the size as compared with a belt-type fixing device. However, since only the nip portion is locally heated, the other portions are not heated.

  Therefore, the belt is in the coldest state at the entrance of the sheet or the like in the nip portion, and there is a problem that fixing failure is likely to occur. In particular, in a high-speed machine, there is a problem in that fixing failure is more likely to occur because the belt rotates fast and the heat radiation of the belt outside the nip increases.

  In order to solve the above-described problems 1 to 3, a fixing device as disclosed in, for example, Japanese Patent Application Laid-Open No. 2007-334205 has been proposed.

  In the fixing device of Patent Document 1, a pipe-shaped metal heat conductor (support member) is fixed inside a fixing belt formed in an endless belt shape so as to guide the movement of the fixing belt. A heat source is provided in the metal heat conductor. The endless belt is heated by the heat source through the metal heat conductor.

  A pressure roller that presses the fixing belt is disposed outside the fixing belt. This pressure roller forms a nip portion in contact with the metal heat conductor via the fixing belt. The fixing belt rotates while being heated by the metal heat conductor as the pressure roller rotates.

  In the fixing device of Patent Document 1, since the entire fixing belt is warmed by such a configuration, the first print time from the heating standby time can be shortened, and the shortage of heat at the time of high-speed rotation is solved. Therefore, even when the fixing device disclosed in Patent Document 1 is mounted on a high-production image forming apparatus, good fixability can be obtained.

  However, in order to further save energy and shorten the first print time, it is necessary to further improve the thermal efficiency.

  Therefore, a configuration in which the fixing belt is indirectly heated by a metal heat conductor, or a configuration in which the fixing belt is directly heated without using the metal heat conductor is conceivable. As a result, the thermal efficiency is greatly improved, so that the power consumption is reduced and the first print time from the heating standby time can be further shortened. In this case, the cost can be reduced by not using the metal heat conductor.

  In the configuration in which the fixing belt is directly heated, the nip portion forming member is disposed in contact with the inner peripheral surface of the fixing belt inside the fixing belt. The pressure roller presses the fixing belt against the nip portion forming member to form a nip portion with the fixing belt.

  A lubricant is applied to the inner peripheral surface of the fixing belt. This lubricant has a fixing function by suppressing the frictional resistance between the fixing belt and the nip forming member and smoothly rotating the fixing belt.

  However, in the conventional fixing belt, when the temperature of the fixing belt rises due to heating, the viscosity of the lubricant decreases and spreads on the inner peripheral surface. Therefore, when the fixing belt rotates, the lubricant leaks from the end of the fixing belt. As a result, the rotation property of the fixing belt is lowered and the fixing function of the fixing belt is lowered. In addition, the lubricant leaking from the fixing belt may contaminate other parts of the fixing device.

  SUMMARY An advantage of some aspects of the invention is that it provides a fixing belt, a fixing device, and an image forming apparatus including the fixing belt that can prevent a lubricant from leaking.

  As a result of intensive studies, the present inventors have employed the following fixing belt, fixing device, and image forming apparatus in order to solve the above-described problems.

The fixing belt of the present invention is a fixing belt that is formed into an endless belt, is coated with a lubricant on its inner peripheral surface, and is rotatable.
Inside the fixing belt, a heat source that heats the fixing belt and a nip portion forming member that is in contact with the inner peripheral surface of the fixing belt are disposed.
A pressure roller that presses the fixing belt against the nip portion forming member to form a nip portion with the fixing belt and rotates the fixing belt is disposed outside the fixing belt.
A portion with high smoothness and a portion with low smoothness are formed on the inner peripheral surface.

  In the fixing belt of the present invention, a portion having high smoothness and a portion having low smoothness are formed on the inner peripheral surface. For this reason, even if the temperature of the fixing belt rises due to heating of the fixing belt and the lubricant spreads on the inner peripheral surface, the lubricant remains and is retained by the surface tension at the portion having low smoothness. Therefore, the fixing belt of the present invention can prevent the leakage of the lubricant.

1 is a schematic diagram of an image forming apparatus showing an embodiment of the present invention. It is a schematic diagram of the fixing device of the embodiment. It is a figure which shows the positional relationship of the fixing belt and pressure roller of the embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram of an image forming apparatus 1000 showing an embodiment of the present invention. Here, a basic configuration of the image forming apparatus 1000 will be described.

  An image forming apparatus 1000 shown in FIG. 1 is a color printer that uses a tandem system in which image forming units that form a plurality of color images are juxtaposed along a belt extending direction. However, the present invention is not limited to this method. The present invention can be applied not only to a printer but also to a copying machine, a facsimile machine, and the like.

  The image forming apparatus 1000 has a tandem structure. In this tandem structure, photosensitive drums 20Y, 20C, 20M, and 20Bk as image carriers are arranged in parallel. The image carrier can form an image as an image corresponding to each color separated into yellow, cyan, magenta, and black.

  As is well known, the image forming apparatus 1000 forms an electrostatic latent image on each of the photosensitive drums 20Y, 20C, 20M, and 20Bk, and develops each electrostatic latent image with toner of each color to form a visible image (toner image). ). Subsequently, the visible image is superimposed and transferred onto the intermediate transfer member (transfer belt 11) (primary transfer), and then transferred onto the recording paper S in a lump (secondary transfer), and then the fixing device 100. To fix on the recording paper S.

  An endless belt is used as the transfer belt 11. The transfer belt 11 is movable in the direction of the arrow A1 while facing the photosensitive drums 20Y, 20C, 20M, and 20Bk.

  Around each of the photosensitive drums 20Y, 20C, 20M, and 20Bk, an apparatus for image forming processing is arranged according to the rotation of the photosensitive drum. This will be described below by taking the photosensitive drum 20Bk for forming a black image as an example.

  Around the photosensitive drum 20Bk, a charging device 30Bk, a developing device 40Bk, a primary transfer roller 12Bk, and a cleaning device 50Bk that perform image forming processing along the rotational direction of the photosensitive drum 20Bk are arranged. An optical writing device 8 is used for writing performed after charging.

  In the superimposing transfer (primary transfer) to the transfer belt 11, the visible image formed on each photosensitive drum 20 </ b> Y, 20 </ b> C, 20 </ b> M, 20 </ b> Bk is the same as that on the transfer belt 11 in the process in which the transfer belt 11 moves in the A1 direction. It is performed so that the image is transferred in a superimposed manner.

  Specifically, the visible images formed on the respective photosensitive drums 20Y, 20C, 20M, and 20Bk are directed from the upstream side to the downstream side in the A1 direction by voltage application by the primary transfer rollers 12Y, 12C, 12M, and 12Bk. This is done at different timings. The primary transfer rollers 12Y, 12C, 12M, and 12Bk are arranged to face the respective photosensitive drums 20Y, 20C, 20M, and 20Bk with the transfer belt 11 interposed therebetween.

  The photosensitive drums 20Y, 20C, 20M, and 20Bk are arranged in this order from the upstream side in the A1 direction. Each of the photosensitive drums 20Y, 20C, 20M, and 20Bk is provided in an image station (four image stations) for forming yellow, cyan, magenta, and black images, respectively.

  Although overlapping with the above description, the image forming apparatus 1000 includes four image stations, the transfer belt unit 10, the secondary transfer roller 5, the cleaning device 13, and the optical writing device 8.

  The four image stations perform image formation processing for each color. The transfer belt unit 10 is disposed so as to face above the photosensitive drums 20Y, 20C, 20M, and 20Bk. Further, the transfer belt unit 10 includes a transfer belt 11 and primary transfer rollers 12Y, 12C, 12M, and 12Bk.

  The secondary transfer roller 5 is a transfer member that is disposed to face the transfer belt 11 and rotates following the transfer belt 11. The cleaning device 13 is disposed to face the transfer belt 11 and cleans the transfer belt 11.

  The optical writing device 8 is arranged opposite to the lower side of the four image stations. The optical writing device 8 includes a semiconductor laser as a light source, a coupling lens, an fθ lens, a toroidal lens, a folding mirror, a rotating polygon mirror as a deflecting unit, and the like.

  The optical writing device 8 emits writing light corresponding to each color to each of the photosensitive drums 20Y, 20C, 20M, and 20Bk, and outputs an electrostatic latent image to each of the photosensitive drums 20Y, 20C, 20M, and 20Bk. Form.

  Further, the image forming apparatus 1000 includes a sheet feeding device 61, a registration roller pair 4, and a sensor (not shown).

  The sheet feeding device 61 is disposed at the lower part of the main body of the image forming apparatus 1000. The sheet feeding device 61 includes a paper feeding cassette. This paper feed cassette is loaded with recording paper S.

  Further, the sheet feeding device 61 includes a feeding roller 3. The feeding roller 3 is in contact with the upper surface of the uppermost recording sheet S. Then, the sheet feeding device 61 feeds the uppermost recording sheet S toward the registration roller pair 4 when the feeding roller 3 is rotationally driven in the counterclockwise direction.

  The registration roller pair 4 feeds the recording paper S sent from the sheet feeding device 61 toward the photosensitive drums 20Y, 20C, 20M, and 20Bk and the transfer belt 11. The recording paper S is fed out in accordance with the timing of toner image formation by the four image stations.

  The sensor detects that the leading edge of the recording paper S has reached the registration roller pair 4.

  Further, the image forming apparatus 1000 includes a fixing device 100, a paper discharge roller 7, a paper discharge tray 17, and toner bottles 9Y, 9C, 9M, and 9Bk.

  The fixing device 100 is a roller fixing type fixing unit for fixing the toner image to the recording paper S on which the toner image is transferred. The paper discharge roller 7 discharges the fixed recording paper S to the outside of the main body of the image forming apparatus 1000.

  The paper discharge tray 17 is disposed on the upper part of the main body of the image forming apparatus 1000. The paper discharge tray 17 stacks the recording paper S discharged from the main body of the image forming apparatus 1000 by the paper discharge roller 7.

  The toner bottles 9Y, 9C, 9M, and 9Bk are located below the paper discharge tray 17. The toner bottles 9Y, 9C, 9M, and 9Bk are filled with toner of each color of yellow, cyan, magenta, and black.

  The transfer belt unit 10 includes a drive roller 72 and a driven roller 73 around which the transfer belt 11 is wound, in addition to the transfer belt 11 and the primary transfer rollers 12Y, 12C, 12M, and 12Bk.

  The driven roller 73 also has a function as tension urging means for the transfer belt 11. For this reason, the driven roller 73 is provided with a biasing means using a spring or the like. Such a transfer belt unit 10, the primary transfer rollers 12Y, 12C, 12M, and 12Bk, the secondary transfer roller 5, and the cleaning device 13 constitute a transfer device 71.

  Although not shown in detail, the cleaning device 13 includes a cleaning brush and a cleaning blade that are disposed so as to face and contact the transfer belt 11.

  The cleaning device 13 cleans the transfer belt 11 by scraping and removing foreign matters such as residual toner on the transfer belt 11 with the cleaning brush and the cleaning blade. Further, the cleaning device 13 has a discharge means (not shown) for carrying out and discarding the residual toner removed from the transfer belt 11.

  FIG. 2 is a schematic diagram of the fixing device 100. First, a basic configuration of the fixing device 100 will be described. The fixing device 100 includes a fixing belt 1, a heat source 102 disposed inside the fixing belt 1, a nip portion forming member 106, and a pressure roller 103 disposed outside the fixing belt 1.

  The fixing belt 1 is formed in an endless belt shape and is rotatably arranged. A protective member 110 is disposed on the outer surface side of the fixing belt 1 so as to cover it. The protective member 110 may rotate with the rotation of the fixing belt 1 or may remain stationary.

  For the base material of the fixing belt 1, a metal such as nickel or SUS or a resin such as polyimide is used. The surface layer of the base material of the fixing belt 1 has a release layer such as a PFA or PTFE layer. The fixing belt 1 prevents the toner from adhering to the release layer.

  An elastic layer such as a silicone rubber layer may be provided between the base material of the fixing belt 1 and the PFA or PTFE layer. In the absence of a silicone rubber layer, the heat capacity is reduced and the fixability is improved. However, when the toner image is crushed and fixed, minute irregularities on the surface of the belt are transferred to the image, and there is a problem that a crumpled glossy unevenness (scratched skin image) remains on the solid portion of the image.

  In order to improve this problem, it is necessary to provide a silicone rubber layer of 100 μm or more. Due to the deformation of the silicone rubber layer, fine irregularities are absorbed and the skin image is improved.

  A halogen heater is used as the heat source 102. As a heat source, in addition to the halogen heater, IH, a resistance heating element, a carbon heater, or the like may be used. The fixing belt 1 is directly heated from the inner peripheral side by the heat source 102.

  The number of halogen heaters is not particularly limited. In the present embodiment, the number of halogen heaters is three. In this case, the fixing belt 1 can be heated to an optimum temperature according to various sizes of recording media.

  The nip portion forming member 106 is in direct contact with the inner peripheral surface 1a of the fixing belt 1 or indirectly through a sliding sheet (not shown).

  The pressure roller 103 is disposed to face the nip forming member 106 with the fixing belt 1 interposed therebetween. The pressure roller 103 is rotated by a driving force transmitted from a driving source such as a motor provided in the image forming apparatus 1000 via a gear.

  The pressure roller 103 includes a metal core 105 and an elastic rubber layer 104 provided on the outer periphery of the metal core 105. A release layer (not shown) is provided on the surface of the elastic rubber layer 104 in order to obtain release properties from the recording medium. A PFA layer or a PTFE layer is used as the release layer.

  The pressure roller 103 may be a hollow roller. The pressure roller 103 may have a heat source such as a halogen heater inside. The elastic rubber layer 104 may be a layer formed of solid rubber. When there is no heat source inside the pressure roller 103, it is desirable to use sponge rubber. When sponge rubber is used, the heat insulating property is enhanced and the heat of the fixing belt 1 is not easily taken.

  The pressure roller 103 presses the fixing belt 1 against the nip forming member 106 by a spring (not shown) or the like. As a result, the elastic rubber layer 104 is crushed and deformed, and a nip portion N is formed between the elastic rubber layer 104 and the fixing belt 1. The nip portion N has a predetermined width (nip width) in the axial direction of the pressure roller 103. The recording paper S is passed through the nip portion N.

  In the present embodiment, the shape of the nip portion N is flat, but may be a concave shape or other shapes. When the shape of the nip portion N is concave, the discharge direction of the leading edge of the recording paper S is closer to the pressure roller 103 and the separation from the fixing belt 1 is improved, so that the occurrence of jam is suppressed.

  A support member 107 (stay) for supporting the nip portion forming member 106 is disposed inside the fixing belt 1. The support member 107 prevents the nip portion forming member 106 that receives pressure from the pressure roller 103 from bending, and obtains a uniform nip width in the axial direction. Both ends of the support member 107 are held and fixed by holding members 108 and positioned.

  A reflective member 109 is disposed between the heat source 102 and the support member 107. The reflection member 109 suppresses useless energy consumption due to the support member 107 being heated by radiant heat from the heat source 102 or the like. Even if the surface of the support member 107 is subjected to heat insulation treatment or mirror treatment instead of including the reflection member 109, the same effect can be obtained.

  Next, the operation of the fixing belt 1 will be described. The fixing belt 1 rotates using the rotation of the pressure roller 103. Specifically, the pressure roller 103 is rotated by a driving source (not shown), and the driving force is transmitted to the fixing belt 1 at the nip portion N, whereby the fixing belt 1 rotates. Further, the fixing belt 1 is moved to either side by driving from the pressure roller 103 and abuts against the protection member 110.

  As described above, the fixing device 100 according to the present embodiment is inexpensive and can warm up quickly.

  Although not shown, the fixing device 100 may include a light shielding member. The light shielding member is arranged so as to rotate without contact along the inner side of the fixing belt 1. The light shielding member has a stepped shape provided with a light shielding area according to the width of various recording sheets S.

  The light shielding member uses this stepped shape to rotate to a position corresponding to the width of various recording sheets S to shield an area unnecessary for heating. As a result, even if the recording paper S having a narrow paper width is continuously passed, the non-sheet passing area does not become overheated, and it is necessary to perform control such as reducing productivity in order to cancel the overheated area. There is no. For this reason, the number of halogen heaters can be reduced from three to two.

  Next, the configuration of the fixing belt 1 according to the present invention will be described with reference to FIG. As is well known, a lubricant (not shown) is applied to the inner peripheral surface 1 a of the fixing belt 1. This lubricant reduces the frictional resistance between the fixing belt 1 and the nip portion forming member 106 and moves the fixing belt 1 smoothly. As the lubricant, silicone oil or fluorine grease is desirable.

  The inner peripheral surface 1a of the fixing belt 1 is formed with a portion having high smoothness and a portion having low smoothness. Specifically, the central portion 1b of the inner peripheral surface 1a is a portion having high smoothness, and both end portions 1c and 1c, which are portions on the left and right sides of the central portion 1b, are portions having low smoothness.

  When the fixing belt 1 is heated, the temperature of the fixing belt 1 rises, and accordingly, the viscosity of the lubricant is lowered and the lubricant spreads on the inner peripheral surface 1a. Since both end portions 1c and 1c of the inner peripheral surface 1a are portions having low smoothness, the lubricant can be retained and retained by the surface tension at the both end portions 1c and 1c. Therefore, the fixing belt 1 of the present embodiment can prevent the lubricant from leaking.

  In addition, since the fixing device 100 and the image forming apparatus 1000 of the present embodiment can prevent the leakage of the lubricant by using the fixing belt 1 of the present embodiment, the rotation of the fixing belt 1 is reduced. It is possible to prevent the fixing function of the fixing belt 1 from being lowered. Further, it is possible to prevent other parts from being damaged by the lubricant.

  The central portion 1b of the inner peripheral surface 1a of the fixing belt 1 is a portion facing the nip portion N (the pressure roller 103). Both end portions 1c and 1c of the inner peripheral surface 1a are portions that do not face the nip portion N even when variations in the fixing belt 1 and the pressure roller 103 are taken into consideration.

  In other words, the central portion 1 b of the inner peripheral surface 1 a of the fixing belt 1 is a portion that is pressed against the nip portion forming member 106 by the pressure roller 103, and both end portions 1 c and 1 c are nip portion forming members by the pressure roller 103. This is a portion that cannot be pressed against 106.

  Therefore, in the fixing belt 1 of the present embodiment, the both end portions 1c and 1c are portions having low smoothness, so that even if a portion having low smoothness is formed on the inner peripheral surface 1a, the nip portion forming member 106 and It is possible to prevent the frictional resistance of the roller from increasing and not moving smoothly.

  As an index indicating smoothness, for example, there is a method represented by surface roughness (Ra). When expressed in terms of surface roughness, Ra of high smoothness portions (portions where surface roughness is not rough) is 0.5 μm or less, and Ra of low smoothness portions (portion where surface roughness is rough) is 3 μm or more. To do. Moreover, you may prescribe | regulate as another parameter | index which shows smoothness by a wave | undulation.

  Although not shown, when the coating material is applied to the inner peripheral surface 1a of the fixing belt 1, the inner peripheral surface 1a has high smoothness by forming the surface of the coating material to have a different roughness. A part and a part with low smoothness are formed.

  In the present embodiment, the roughness of the surface of the coating material applied to the central portion 1b of the inner peripheral surface 1a is set to be a portion having high smoothness. Further, the roughness of the surface of the coating material applied to both end portions 1c, 1c of the inner peripheral surface 1a is set to be a portion having low smoothness. Further, the wear resistance of the coating material is not so important, and it is sufficient that the coating material has excellent heat resistance.

  A method for changing the surface roughness of the coating material includes a method for changing the material of the coating material. Specifically, a slippery material such as fluorine-based resin is used for the central portion 1b of the inner peripheral surface 1a, and a silicone-based heat-resistant resin or ceramic-based resin is used for both ends 1c, 1c of the inner peripheral surface 1a. It is desirable to use a material that is not so required to be slippery.

  Further, the same coating material is used for both the central portion 1b and both end portions 1c and 1c of the inner peripheral surface 1a, and the filler is mixed with the coating material applied to the central portion 1b, thereby improving the smoothness of the central portion 1b. The smoothness of both end portions 1c and 1c may be lowered by increasing it.

  Further, as another method for changing the roughness of the surface of the coating material, the same coating material is applied to the entire inner peripheral surface 1a to roughen both ends 1c and 1c, thereby increasing the smoothness of the central portion 1b. The smoothness of both ends 1c and 1c may be lowered. Specifically, there are a method of roughening both ends 1c, 1c using sand paper, a method of applying sandblast to both ends 1c, 1c, and the like.

  Another method for changing the surface roughness of the coating material is to use the same coating material and change the coating conditions to provide a difference in the smoothness of the inner peripheral surface 1a.

  For example, there is a method of changing the moving speed of the spray gun used for applying the coating material. If coating is performed while the spray gun is moved quickly, uneven coating occurs, and the smoothness of the portion where the uneven coating occurs is reduced. Therefore, the spray gun is moved in the left-right direction of the inner peripheral surface 1a (the axial direction of the pressure roller 103), and the moving speed at that time is changed.

  Specifically, the spray gun is moved fast at both ends 1c, 1c of the inner peripheral surface 1a, and the spray gun is moved slowly at the central portion 1b. As a result, coating unevenness occurs at both end portions 1c and 1c, so that the smoothness can be lowered.

  Another method is to change the particle size of the coating material by changing the size of the spray gun aperture. Specifically, the aperture of the spray gun is increased at both ends 1c and 1c of the inner peripheral surface 1a. As a result, the particle size of the coating material increases, so that the degree of unevenness increases and the smoothness decreases. In the central portion 1b of the inner peripheral surface 1a, the aperture of the spray gun is reduced. Thereby, since the particle size of the coating material is reduced, the degree of unevenness is reduced and the smoothness is increased.

  The above two methods, that is, a method of changing the moving speed of the spray gun and a method of changing the aperture of the spray gun may be used in combination.

  Moreover, you may give a difference in the smoothness of the internal peripheral surface 1a by providing the part which does not apply | coat a coating material to the internal peripheral surface 1a. Specifically, a coating material is applied to the central portion 1b of the inner peripheral surface 1a using a slippery material, and no coating material is applied to both end portions 1c and 1c. Thereby, the smoothness of the center part 1b becomes high, and the smoothness of the both ends 1c and 1c becomes low.

  In this case, if the surface property of the base material of the fixing belt 1 is originally rough, it is easy to make a difference in the smoothness of the inner peripheral surface 1a. When the surface property of the substrate is smooth, unevenness is formed by etching at both end portions 1c and 1c so as to give a difference in the smoothness of the inner peripheral surface 1a.

  As mentioned above, although embodiment which concerns on this invention was illustrated, this embodiment does not limit the content of this invention. Various modifications can be made without departing from the scope of the claims of the present invention.

  For example, in the fixing belt 1 of the present embodiment, the example in which the present invention is applied when the inner peripheral surface 1a is directly heated has been described. However, the present invention is applied when the inner peripheral surface 1a is indirectly heated. May be. Further, in the fixing belt 1 of the present embodiment, the smoothness of both end portions 1c, 1c of the inner peripheral surface 1a is lowered, but the smoothness of one end portion 1c may be lowered.

DESCRIPTION OF SYMBOLS 1 Fixing belt 1a Inner peripheral surface 1b Center part of inner peripheral surface (part facing nip part)
1c, 1c Both end portions of the inner peripheral surface (portions not facing the nip portion)
DESCRIPTION OF SYMBOLS 100 Fixing device 102 Heat source 103 Pressure roller 106 Nip part forming member N Nip part 1000 Image forming apparatus

JP 2007-334205 A

Claims (6)

A fixing belt that is formed into an endless belt, has a lubricant applied to its inner peripheral surface, and is rotatable;
Inside the fixing belt, a heat source that heats the fixing belt and a nip portion forming member that is in contact with the inner peripheral surface of the fixing belt are disposed.
A pressure roller that presses the fixing belt against the nip portion forming member to form a nip portion with the fixing belt and rotates the fixing belt is disposed outside the fixing belt.
A fixing belt characterized in that a portion with high smoothness and a portion with low smoothness are formed on the inner peripheral surface. The fixing belt according to claim 1,
The high smoothness portion is formed in a portion facing the nip portion on the inner peripheral surface, and the low smoothness portion is formed in a portion not facing the nip portion on the inner peripheral surface. Fixing belt. The fixing belt according to claim 1 or 2,
A coating material is applied to the inner peripheral surface, and the surface of the coating material is formed to have a different roughness. A portion with a small surface roughness of the coating material is defined as a portion with high smoothness, A fixing belt characterized in that a portion having a large surface roughness is a portion having the low smoothness. The fixing belt according to claim 1 or 2,
A portion where the coating material is applied and a portion where the coating material is not applied are formed on the inner peripheral surface, a portion where the coating material is applied is the highly smooth portion, and a portion where the coating material is not applied A fixing belt having the low smoothness portion. A fixing belt that is formed into an endless belt, is coated with a lubricant on its inner peripheral surface, and is rotatable;
A heat source that heats the fixing belt and a nip portion forming member that is in contact with the inner peripheral surface of the fixing belt, disposed inside the fixing belt;
A fixing device provided outside the fixing belt, and including a pressure roller that presses the fixing belt against the nip portion forming member to form a nip portion with the fixing belt and rotates the fixing belt.
A fixing device using the fixing belt according to claim 1 as the fixing belt.   An image forming apparatus comprising the fixing device according to claim 5.