JP2024023903A - Fixing device and image forming device - Google Patents

Abstract

[Problem] A fixing method that has a short warm-up time and first print time, does not cause fixing failures, etc. even when the speed of the device is increased, and does not cause the fixing member that is in pressure contact with the reinforcing member to fall. and an image forming apparatus. SOLUTION: A fixing member 26 that presses against a pressure rotating body 31 via a fixing belt 21 to form a nip portion, and a reinforcing member that comes into contact with the fixing member 26 from inside the fixing belt 21 to reinforce the fixing member 26. 23 is installed. The fixing member 26 has a plurality of rows of protrusions 26a and 26b that protrude toward the opposing surface 23a of the reinforcing member 23 so as to come into contact with the reinforcing member 23 in a plurality of rows along the conveying direction. [Selection diagram] Figure 4

Description

The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction device thereof, and a fixing device installed therein.

Conventionally, in image forming apparatuses such as copying machines and printers, fixing devices have been known that have a short warm-up time and first print time, and are less likely to cause fixing defects even when the speed of the apparatus is increased (for example, (See Patent Document 1.)

Specifically, the fixing device described in FIGS. 2, 4, etc. of Patent Document 1 includes a fixing belt (reference numeral 21), a pipe-shaped pipe fixed to face the inner circumferential surface of the fixing belt except for the nip portion. A heating member (numeral 22), a heater (numeral 25) installed inside the heating member to heat the heating member, and a pressure roller (numeral 31) through the fixing belt to form a nip portion. The fixing belt includes a fixing member (reference numeral 26) installed inside the fixing belt, a substantially plate-shaped reinforcing member (reference numeral 23) that abuts against and reinforces the fixing member, and the like. The substantially plate-shaped reinforcing member is formed to have a relatively narrow width (length in the transport direction) so as to come into contact with a part of the surface of the fixing member.
Then, the fixing belt is heated by a pipe-shaped heating member heated by the heater, and the toner image on the recording medium conveyed toward the nip section receives heat and pressure at the nip section and is transferred onto the recording medium. It will be established.

In the above-mentioned fixing device of Patent Document 1, the fixing member is installed so as to be fitted into the recess of the pipe-shaped heating member, so the contact area (contact width) of the reinforcing member that contacts the fixing member is narrow. Even if the balance of forces that the fixing member receives from the reinforcing member becomes unbalanced, the fixing member does not fall down as a result.

On the other hand, in the fixing device disclosed in Patent Document 1, for the purpose of further improving the heating efficiency of the fixing belt and reducing the cost and size of the device, the pipe-shaped heating member is removed and the pipe-shaped heating member is used. A possible solution is to adopt a configuration in which the fixing belt is directly heated by a heating means instead of the above.
However, in that case, there is no longer a heating member (recess) that prevents the fixed member from falling, so the fixed member with the reinforcing member pressed against it cannot be held in a well-balanced manner, and there is a possibility that the fixed member may fall. There is. If the fixing member is tilted in this way, a desired nip cannot be formed, resulting in poor fixing of the output image or poor conveyance of the recording medium.

This invention was made to solve the above-mentioned problems, and has a short warm-up time and first print time, and even when the speed of the device is increased, fixing failure does not occur, and the reinforcing member An object of the present invention is to provide a fixing device and an image forming apparatus in which a fixing member that is pressed against the fixing member does not fall down.

The fixing device according to the invention according to claim 1 of the present invention includes a flexible endless fixing belt and a pressurizing rotary body disposed inside the fixing belt and sandwiching the fixing belt. a nip forming member that forms a nip portion in which a recording medium is conveyed between the fixing belt and the pressure rotating body; a heat source that faces the fixing belt and heats the fixing belt; and the fixing belt. a reinforcing member that is disposed inside the fixing belt and has opposing surfaces that come into contact with the nip forming member; and a pair of guide members that guide both ends of the fixing belt in the width direction, and the nip forming member an upstream contact part that contacts the opposing surface on the upstream side of the transport direction; a downstream contact part that contacts the opposing surface on the downstream side of the transport direction; and the upstream contact part and the downstream side. The fixing belt has a non-contacting part that does not abut the opposing surface between the contacting part and the fixing belt, and a sheet-like member is interposed between the nip forming member and the fixing belt.

In this application, the state in which the fixing member or the reinforcing member is "fixed" is defined as a state in which the fixing member or the reinforcing member is held in a non-rotating manner without being rotationally driven. Therefore, for example, even if the fixing member is biased toward the nip by a biasing means such as a spring, if the fixing member is held non-rotating, the fixing member is "fixed". state.

In addition, in this application, the "conveyance direction" of the recording medium refers to the same direction as the tangential direction of the nip when the fixing belt and the pressure rotating body contact each other in an ideal arc without being deformed at the nip. It is defined as .
Furthermore, in the present application, the "width direction" is defined as a direction perpendicular to the conveyance direction and the same direction as the rotation axis direction of the fixing belt and the pressure rotating body.

In the present invention, a plurality of rows of protrusions that protrude toward the reinforcing member so as to come into contact with the reinforcing member are formed on the fixing member along the conveying direction. As a result, the warm-up time and first print time are short, and even when the speed of the device is increased, fixing failure does not occur, and the fixing member that is pressed against the reinforcing member does not fall. An apparatus and an image forming apparatus can be provided.

1 is an overall configuration diagram showing an image forming apparatus in Embodiment 1 of the present invention. FIG. FIG. 2 is a configuration diagram showing a fixing device. FIG. 3 is a side view of the fixing device viewed in the width direction. FIG. 3 is an enlarged view showing the vicinity of the nip portion. FIG. 3 is a cross-sectional side view showing a state in which the fixing belt is held by a holding member. FIG. 3 is a schematic front view showing a fixing belt and a reinforcing member held by a holding member. They are (A) a side view and (B) a bottom view showing the fixing member in a state where the sheet-like member is covered. In FIG. 7(A), (A) a schematic sectional view showing the X1-X1 cross section, (B) a schematic sectional view showing the X2-X2 cross section, and (C) a schematic sectional view showing the X3-X3 cross section. be. They are (A) a side view and (B) a bottom view showing the fixing member. It is a development view showing a sheet-like member. It is a top view which shows a plate-shaped member. FIG. 2 is a configuration diagram showing a fixing device in Embodiment 2 of the present invention.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals, and repeated explanations thereof will be simplified or omitted as appropriate.

Embodiment 1.
Embodiment 1 of the present invention will be described in detail with reference to FIGS. 1 to 11.
First, the configuration and operation of the entire image forming apparatus will be described with reference to FIG.
As shown in FIG. 1, the image forming apparatus 1 in the first embodiment is a tandem color printer. Four toner bottles 102Y, 102M, 102C, and 102K corresponding to each color (yellow, magenta, cyan, and black) are removably (replaceably) installed in a bottle accommodating section 101 located above the image forming apparatus main body 1. ing.
An intermediate transfer unit 85 is arranged below the bottle accommodating section 101. Image forming sections 4Y, 4M, 4C, and 4K corresponding to each color (yellow, magenta, cyan, and black) are arranged in parallel to face the intermediate transfer belt 78 of the intermediate transfer unit 85.

Each of the image forming units 4Y, 4M, 4C, and 4K is provided with a photosensitive drum 5Y, 5M, 5C, and 5K, respectively. Further, a charging section 75, a developing section 76, a cleaning section 77, a static eliminating section (not shown), etc. are arranged around each of the photosensitive drums 5Y, 5M, 5C, and 5K. Then, an image forming process (charging process, exposure process, developing process, transfer process, cleaning process) is performed on each photoconductor drum 5Y, 5M, 5C, 5K, and each photoconductor drum 5Y, 5M, 5C, Images of each color will be formed on 5K.

The photosensitive drums 5Y, 5M, 5C, and 5K are driven to rotate clockwise in FIG. 1 by a drive motor (not shown). Then, at the position of the charging section 75, the surfaces of the photoreceptor drums 5Y, 5M, 5C, and 5K are uniformly charged (this is a charging process).
Thereafter, the surfaces of the photoreceptor drums 5Y, 5M, 5C, and 5K reach the irradiation position of the laser beam L emitted from the exposure section 3, and electrostatic latent images corresponding to each color are formed by exposure scanning at this position. (This is an exposure process.)

Thereafter, the surfaces of the photoreceptor drums 5Y, 5M, 5C, and 5K reach a position facing the developing device 76, where the electrostatic latent images are developed to form toner images of each color (developing step ).
Thereafter, the surfaces of the photoreceptor drums 5Y, 5M, 5C, and 5K reach positions facing the intermediate transfer belt 78 and the first transfer bias rollers 79Y, 79M, 79C, and 79K, and at this position, the surfaces of the photoreceptor drums 5Y, 5M , 5C, and 5K are transferred onto the intermediate transfer belt 78 (this is a primary transfer step). At this time, a small amount of untransferred toner remains on the photoreceptor drums 5Y, 5M, 5C, and 5K.

Thereafter, the surfaces of the photoreceptor drums 5Y, 5M, 5C, and 5K reach a position facing the cleaning section 77, and at this position, the untransferred toner remaining on the photoreceptor drums 5Y, 5M, 5C, and 5K is transferred to the cleaning section. It is mechanically recovered by a cleaning blade 77 (this is a cleaning process).
Finally, the surfaces of the photoreceptor drums 5Y, 5M, 5C, and 5K reach a position where they face a static eliminator (not shown), and at this position, the residual potential on the photoreceptor drums 5Y, 5M, 5C, and 5K is removed. Ru.
In this way, a series of image forming processes performed on the photoreceptor drums 5Y, 5M, 5C, and 5K are completed.

Thereafter, the toner images of each color formed on each photoreceptor drum through a developing process are transferred onto the intermediate transfer belt 78 in an overlapping manner. In this way, a color image is formed on the intermediate transfer belt 78.
Here, the intermediate transfer unit 85 includes an intermediate transfer belt 78, four primary transfer bias rollers 79Y, 79M, 79C, 79K, a secondary transfer backup roller 82, a cleaning backup roller 83, a tension roller 84, and an intermediate transfer cleaning section 80. , etc. The intermediate transfer belt 78 is stretched and supported by three rollers 82 to 84, and is moved endlessly in the direction of the arrow in FIG. 1 by the rotation of one roller 82.

The four primary transfer bias rollers 79Y, 79M, 79C, and 79K sandwich the intermediate transfer belt 78 between the photosensitive drums 5Y, 5M, 5C, and 5K, respectively, to form primary transfer nips. Then, a transfer bias opposite to the polarity of the toner is applied to the primary transfer bias rollers 79Y, 79M, 79C, and 79K.
The intermediate transfer belt 78 then travels in the direction of the arrow and sequentially passes through the primary transfer nip of each primary transfer bias roller 79Y, 79M, 79C, and 79K. In this way, the toner images of each color on the photoreceptor drums 5Y, 5M, 5C, and 5K are primarily transferred onto the intermediate transfer belt 78 in an overlapping manner.

Thereafter, the intermediate transfer belt 78, onto which the toner images of each color have been superimposed and transferred, reaches a position facing the secondary transfer roller 89. At this position, the secondary transfer backup roller 82 and the secondary transfer roller 89 sandwich the intermediate transfer belt 78 between them to form a secondary transfer nip. Then, the four-color toner images formed on the intermediate transfer belt 78 are transferred onto the recording medium P conveyed to the position of this secondary transfer nip. At this time, untransferred toner that has not been transferred to the recording medium P remains on the intermediate transfer belt 78.
After that, the intermediate transfer belt 78 reaches the position of the intermediate transfer cleaning section 80 . At this position, untransferred toner on the intermediate transfer belt 78 is collected.
In this way, the series of transfer processes performed on the intermediate transfer belt 78 is completed.

Here, the recording medium P conveyed to the position of the secondary transfer nip is transferred from the paper feed section 12 disposed below the main body 1 to a paper feed roller 97, a pair of registration rollers 98 (a pair of timing rollers), etc. It was transported via
Specifically, the paper feed section 12 stores a plurality of recording media P such as transfer paper in a stacked manner. Then, when the paper feed roller 97 is rotationally driven in the counterclockwise direction in FIG. 1, the uppermost recording medium P is fed toward between the rollers of the registration roller pair 98.

The recording medium P conveyed to the registration roller pair 98 temporarily stops at the roller nip position of the registration roller pair 98 whose rotational drive has been stopped. Then, the registration roller pair 98 is rotationally driven in synchronization with the color image on the intermediate transfer belt 78, and the recording medium P is conveyed toward the secondary transfer nip. In this way, a desired color image is transferred onto the recording medium P.

Thereafter, the recording medium P onto which the color image has been transferred at the secondary transfer nip position is conveyed to the fixing unit 20 position. Then, at this position, the color image transferred to the surface is fixed onto the recording medium P by heat and pressure from the fixing belt 21 and the pressure roller 31.
Thereafter, the recording medium P passes between the rollers of the paper ejection roller pair 99 and is ejected out of the apparatus. The recording medium P discharged from the apparatus by the paper discharge roller pair 99 is sequentially stacked on the stack unit 100 as an output image.
In this way, a series of image forming processes in the image forming apparatus are completed.

Next, the configuration and operation of the fixing device 20 installed in the image forming apparatus main body 1 will be described in detail with reference to FIGS. 2 to 11.
2 to 4, the fixing device 20 includes a fixing belt 21 (belt member) as a fixing member, a fixing member 26 (nip forming member), a reinforcing member 23, and a heater 25 (heat source) as a heating means. ), a pressure roller 31 as a pressure rotating body, a temperature sensor 40, a sheet member 22, a screw 24, a plate member 28 (fixing plate), a reflecting member 27, and the like.

Here, the fixing belt 21 is a thin and flexible endless belt, and rotates (travels) in the direction of the arrow (counterclockwise) in FIG. 2 . The fixing belt 21 has a base material layer, an elastic layer, and a release layer laminated in this order from the inner circumferential surface 21a (the surface in sliding contact with the fixing member 26), and has a total thickness of 1 mm or less. is set to .
The base material layer of the fixing belt 21 has a layer thickness of 30 to 50 μm, and is made of a metal material such as nickel or stainless steel, or a resin material such as polyimide.
The elastic layer of the fixing belt 21 has a layer thickness of 100 to 300 μm, and is made of a rubber material such as silicone rubber, foamable silicone rubber, or fluororubber. By providing the elastic layer, minute irregularities are not formed on the surface of the fixing belt 21 at the nip portion, heat is uniformly transmitted to the toner image T on the recording medium P, and the generation of a yuzu skin image is suppressed.
The release layer of the fixing belt 21 has a layer thickness of 10 to 50 μm and is made of PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), PTFE (polytetrafluoroethylene), polyimide, polyetherimide, PES ( Polyether sulfide), etc. By providing the release layer, release properties (peelability) for the toner T (toner image) are ensured.

Further, the diameter of the fixing belt 21 is set to be 15 to 120 mm. Note that in the first embodiment, the inner diameter of the fixing belt 21 is set to 30 mm.
Inside the fixing belt 21 (on the inner peripheral surface side), there are a fixing member 26, a heater (heating means), a reinforcing member 23, a reflecting member 27, a sheet-like member 22, a screw 24, a plate-like member 28 (fixing plate), etc. is permanently installed.
Here, the fixing member 26 is fixed so as to be in sliding contact with the inner peripheral surface 21a of the fixing belt 21. Then, the fixing member 26 comes into pressure contact with the pressure roller 31 via the fixing belt 21, thereby forming a nip portion through which the recording medium P is conveyed. Referring to FIGS. 3 and 5, both ends of the fixing member 26 in the width direction are held by a flange 29 (holding member) fixedly supported by the side plate 43 of the fixing device 20. Further, the fixing belt 21 is rotatably held by flanges 29 at both ends in the width direction. Note that the configurations of the fixing member 26 and the flange 29 will be explained in more detail later.
The fixing belt 21 is directly heated by radiant heat from a heater 25 (heating means) installed inside the fixing belt 21.

The heater 25 as a heating means is a halogen heater (or carbon heater), and both ends thereof are fixed to the side plate 43 of the fixing device 20 (see FIG. 3). The fixing belt 21 is heated mainly in a portion other than the nip portion by the radiant heat of the heater 25 (heating means) whose output is controlled by the power supply section of the apparatus main body 1. Furthermore, heat is applied to the toner image T on the recording medium P from the heated surface of the fixing belt 21 . Note that the output control of the heater 25 is performed based on the detection result of the belt surface temperature by a temperature sensor 40 such as a thermistor that faces the surface of the fixing belt 21. Further, by controlling the output of the heater 25 in this manner, the temperature of the fixing belt 21 (fixing temperature) can be set to a desired temperature.
In the first embodiment, one heater 25 is installed on the inner peripheral surface of the fixing belt 21, but a plurality of heaters may be installed on the inner peripheral surface of the fixing belt 21.

In this way, in the fixing device 20 according to the first embodiment, the fixing belt 21 is heated over a relatively wide range in the circumferential direction, rather than only a part of the fixing belt 21 being heated locally. Therefore, even when the speed of the apparatus is increased, the fixing belt 21 is sufficiently heated and the occurrence of fixing defects can be suppressed. That is, since the fixing belt 21 can be efficiently heated with a relatively simple configuration, the warm-up time and first print time can be shortened, and the apparatus can be downsized.
In particular, since the fixing device 20 in the first embodiment is configured such that the fixing belt 21 is directly heated by the heater 25 (heating means), the heating efficiency of the fixing belt 21 is further improved, and The fixing device 21 can be further reduced in cost and size.

Here, with reference to FIGS. 5 and 6, the two flanges 29 serving as holding members are made of a heat-resistant resin material or the like, and are fitted into the side plates 43 at both ends of the fixing device 20 in the width direction. There is. The flange 29 includes a guide portion 29a for holding the fixing belt 21 while maintaining the circular posture of the fixing belt 21, a stopper portion 29b for restricting movement of the fixing belt 21 in the width direction (belt deviation), etc. is provided.
Furthermore, the inner circumferential surface 21a of the fixing belt 21 has a sliding portion (encircled by a broken line in FIG. 5) with the guide portion 29a of the flange 29 at both ends in the width direction (the left-right direction in FIG. 5). A low friction portion 21a1 is formed to reduce the sliding resistance at the lower portion. Specifically, the low friction portion 21a1 is formed by coating the surface of the base material layer with a low friction material such as fluororesin. With this configuration, even if the fixing belt 21 and the flange 29 (guide portion 29a) come into sliding contact with each other due to the rotation (traveling) of the fixing belt 21, the fixing belt 21 and the flange 29 (guide portion 29a) are unlikely to wear out and deteriorate. .
In the first embodiment, the only members that come into contact with the inner peripheral surface 21a of the fixing belt 21 are the flanges 29 at both ends in the width direction and the fixing member 26. There is no member (belt guide) that guides the rotation of the fixing belt 21.

Here, in the first embodiment, a reinforcing member 23 that reinforces the strength of the fixing member 26 forming the nip portion is fixedly provided on the inner peripheral surface side of the fixing belt 21. Referring to FIG. 3, the reinforcing member 23 is formed so that its length in the width direction is equal to that of the fixing member 26, and both ends of the reinforcing member 23 in the width direction are held by the flange 29 (holding member) of the fixing device 20. has been done. Specifically, the reinforcing member 23 is positioned so as to be sandwiched between the flange 29 and the fixing member 26. In the first embodiment, as shown in FIG. 6, the end surfaces (reference surfaces 23b) of the two upright portions 23c (portions that stand up in the direction away from the opposing surface 23a) of the reinforcing member 23 is configured so that the reinforcing member 23 is held in contact with a holding portion 29c (see FIG. 6) of the flange 29. On the other hand, the reinforcing member 23 can also be held in contact with the side plate 43 instead of the holding part 29c of the flange 29.
Since the reinforcing member 23 contacts the pressure roller 31 via the fixing member 26 and the fixing belt 21, it is possible to prevent the fixing member 26 from deforming significantly at the nip portion due to the pressing force of the pressure roller 31. ing. In the first embodiment, the reinforcing member 23 is a substantially U-shaped plate member formed such that a recessed portion faces the side where the heater 25 is located. This reinforcing member 23 is preferably formed of a metal material with high mechanical strength, such as stainless steel or iron, in order to satisfy the above-mentioned functions.
Note that the configuration of the reinforcing member 23 will be explained in more detail later.

Further, in the first embodiment, a reflecting member 27 (reflecting plate) is fixedly provided on the side of the reinforcing member 23 that faces the heater 25 . As a result, the heat directed from the heater 25 toward the reinforcing member 23 (the heat that heats the reinforcing member 23) is reflected by the reflecting member 27 and used to heat the fixing belt 21, so that the heating efficiency of the fixing belt 21 is improved. It will improve further.
Note that the same effect can be obtained even if part or all of the surface of the reinforcing member 23 facing the heater 25 is mirror-finished or provided with a heat insulating member.

Referring to FIG. 2, a pressure roller 31 as a pressure rotating body that comes into contact with the outer circumferential surface of the fixing belt 21 at the nip portion has a diameter of 30 mm, and has an elastic layer on a core metal 32 having a hollow structure. 33 was formed. The elastic layer 33 of the pressure roller 31 (pressure rotating body) is made of a material such as foamable silicone rubber, silicone rubber, or fluororubber. Note that a thin mold release layer made of PFA, PTFE, etc. can also be provided on the surface layer of the elastic layer 33. Pressure roller 31 presses against fixing belt 21 to form a desired nip between both members. Further, referring to FIG. 3, the pressure roller 31 is provided with a gear 45 that meshes with a drive gear of a drive mechanism (not shown), and the pressure roller 31 moves in the direction of the arrow (clockwise) in FIG. Rotationally driven. Further, the pressure roller 31 is rotatably supported at both ends in the width direction by a side plate 43 of the fixing device 20 via a bearing 42 . Note that a heat source such as a halogen heater may be provided inside the pressure roller 31.

Note that when the elastic layer 33 of the pressure roller 31 is made of a sponge-like material such as foamable silicone rubber, the pressure applied to the nip portion can be reduced, so that the load generated on the fixing member 16 can be reduced. It can be reduced. Furthermore, the heat insulation of the pressure roller 31 is improved, and the heat of the fixing belt 21 is less likely to move toward the pressure roller 31, so that the heating efficiency of the fixing belt 21 is improved.
Further, in the first embodiment, the diameter of the fixing belt 21 is formed to be approximately equal to the diameter of the pressure roller 31, but the diameter of the fixing belt 21 is formed to be smaller than the diameter of the pressure roller 31. It can also be formed. In this case, since the curvature of the fixing belt 21 at the nip portion is smaller than the curvature of the pressure roller 31, the recording medium P sent out from the nip portion is likely to be separated from the fixing belt 21.

Referring to FIG. 4, the fixing member 26 that comes into sliding contact with the inner circumferential surface 21a of the fixing belt 21 has a concave surface that faces the pressure roller 31 (sliding surface) that follows the curvature of the pressure roller 31. is formed. As a result, since the recording medium P is sent out from the nip portion so as to follow the curvature of the pressure roller 31, problems such as the recording medium P being attracted to the fixing belt 21 after the fixing process and not being separated can be prevented. be able to.
In the first embodiment, the shape of the fixing member 26 forming the nip portion is formed into a concave shape, but the shape of the fixing member 26 forming the nip portion may also be formed into a planar shape. That is, the sliding surface of the fixing member 26 (the surface facing the pressure roller 31) can be formed to have a planar shape. As a result, the shape of the nip portion becomes substantially parallel to the image surface of the recording medium P, and the adhesion between the fixing belt 21 and the recording medium P increases, thereby improving fixing performance. Furthermore, since the curvature of the fixing belt 21 on the exit side of the nip section is increased, the recording medium P sent out from the nip section can be easily separated from the fixing belt 21.

Further, as a material for forming the fixing member 26, a resin material or a metal material can be used, but the material has enough rigidity that it will not bend significantly even when it is subjected to the pressure applied by the pressure roller 31, and is heat resistant. Resin materials (liquid crystal polymer, polyamideimide, etc.) having heat insulating properties are suitable. In the first embodiment, liquid crystal polymer (LCP) is used as the material for the fixing member 26.

Further, the fixing member 26 is covered with a sheet-like member 22 made of a low-friction material such as PTFE in order to reduce sliding resistance with the fixing belt 21. Specifically, the sheet-like member 22 is arranged around the fixing member 26 (as seen in a cross section as shown in FIG. ) around the member 26. Further, the sheet-like member 22 in the first embodiment is formed of a fibrous material (a cloth member made of PTFE) impregnated with a lubricant such as silicone oil. As a result, the lubricant is retained on the surfaces where the fixing member 26 and the fixing belt 21 come into contact. Therefore, the problem of wear of both members 21 and 26 due to sliding contact between the fixing member 26 and the fixing belt 21 is reduced.
Note that the configurations of the sheet-like member 22 and the fixing member 26 will be explained in more detail later.

Here, in the first embodiment, the reinforcing member 23 (and the reflecting member 27) is installed so as to isolate the space between the fixing member 26 and the heater 25 (heating means).
In the first embodiment, since the heater 25 is installed so as to face a relatively wide range in the circumferential direction of the fixing belt 21 (inner circumferential surface 21a), the fixing can be performed even during heating standby (print operation standby). The belt 21 can be heated evenly in the circumferential direction. Therefore, after receiving a print request, the print operation can be performed immediately. At this time, in conventional on-demand type fixing devices (for example, see Japanese Patent No. 2884714), if heat is applied to the pressure roller while it is deformed during heating standby at the nip, the rubber of the pressure roller Depending on the material, thermal deterioration may occur, shortening the life of the pressure roller, or compression permanent strain may occur in the pressure roller. ). When compression permanent strain occurs in the pressure roller, a portion of the pressure roller becomes recessed, making it impossible to obtain the desired nip width, resulting in poor fixing and abnormal noises during rotation. do.
On the other hand, in the first embodiment, the reinforcing member 23 (and the reflecting member 27) is installed between the fixing member 26 and the heater 25 so as to block the heat of the heater 25. Heat is less likely to reach the fixing member 26 during standby. Therefore, the problem that the pressure roller 31 is heated to a high temperature in a deformed state during heating standby is alleviated, and the above-mentioned problem can be prevented from occurring.

Further, the lubricant applied between the fixing member 26 and the fixing belt 21 in order to reduce the frictional resistance between the two members deteriorates due to use under high temperature conditions in addition to the high pressure conditions at the nip portion, and the fixing belt 21 There is a possibility that problems such as slipping may occur.
In contrast, in the first embodiment, the reinforcing member 23 (and the reflecting member 27) is installed between the fixing member 26 and the heater 25 so as to block the heat of the heater 25. 25 becomes difficult to reach the lubricant in the nip. Therefore, deterioration of the lubricant due to high temperatures is reduced, and the above-mentioned problems can be prevented from occurring.

Furthermore, in the first embodiment, since the reinforcing member 23 (and the reflective member 27) is installed between the fixing member 26 and the heater 25 so as to block the heat of the heater 25, the fixing member 26 Because of the heat insulation, the fixing belt 21 is not actively heated in the nip portion. Therefore, the temperature of the recording medium P fed into the nip section becomes low when it is sent out from the nip section. That is, at the exit of the nip portion, the temperature of the toner image fixed on the recording medium P becomes low, the viscosity of the toner decreases, and the adhesive force of the toner to the fixing belt 21 decreases, and the recording medium P It is separated from the fixing belt 21. Therefore, the problem that the recording medium P immediately after the fixing process is wrapped around the fixing belt 21 and jammed is prevented, and toner sticking to the fixing belt 21 is also suppressed.

The normal operation of the fixing device 20 configured as described above will be briefly described below.
When the power switch of the apparatus main body 1 is turned on, power is supplied to the heater 25 and rotational driving of the pressure roller 31 in the arrow direction in FIG. 2 is started. As a result, the fixing belt 21 is also driven (rotated) in the direction of the arrow in FIG. 2 due to the frictional force with the pressure roller 31 at the nip portion.
Thereafter, the recording medium P is fed from the paper feeding section 12, and the unfixed color image is carried (transferred) onto the recording medium P at the position of the secondary transfer roller 89. The recording medium P carrying the unfixed image T (toner image) is conveyed in the direction of arrow Y10 in FIG. It is fed into the nip section.
Then, the toner image T is fixed on the surface of the recording medium P by the heating by the fixing belt 21 heated by the heater 25 and the pressing force of the fixing member 26 reinforced by the reinforcing member 23 and the pressure roller 31. . Thereafter, the recording medium P sent out from the nip portion is conveyed in the direction of arrow Y11.

Hereinafter, the characteristic configuration and operation of the fixing device 20 in the first embodiment will be described in detail.
As described above, the fixing device 20 in the first embodiment includes a fixing device that is fixed to the inner peripheral surface of the fixing belt 21 and presses against the pressure roller 31 via the fixing belt 21 to form a nip portion. and a reinforcing member 23 that is fixed to the inner peripheral surface of the fixing belt 21 and abuts the fixing member 26 from inside the fixing belt 21 to reinforce the fixing member 26.
Here, in the first embodiment, as shown in FIG. 4, protrusions 26a and 26b protrude toward the opposing surface 23a of the reinforcing member 23 so as to come into contact with the reinforcing member 23 on the fixed member 26. A plurality of rows are provided along the conveyance direction of the medium P (or the rotational direction of the fixing belt 21). Specifically, the plurality of rows of protrusions include an upstream protrusion 26a that protrudes toward the opposing surface 23a of the reinforcing member 23 so as to come into contact with the reinforcing member 23 on the upstream side with respect to the conveying direction of the recording medium P; A downstream protrusion 26b is formed that protrudes toward the opposing surface 23a of the reinforcing member 23 so as to come into contact with the reinforcing member 23 on the downstream side with respect to the transport direction of P. That is, the fixing member 26 has two rows of protrusions 26a and 26b spaced apart in the conveying direction on the side facing the reinforcing member 23 (the distance between the upstream end and the downstream end is set to B). ) are provided, and these two rows of protrusions 26a, 26b come into surface contact with the opposing surface 23a of the reinforcing member 23, respectively.

With such a configuration, even if a pipe-shaped heating member into which the fixing member 26 is fitted and fixed is not installed, the fixing member 26 with the reinforcing member 23 in pressure contact is held in a well-balanced manner. 26 is prevented from falling down. Then, the desired nip is formed with high precision, and problems such as poor fixing of the output image and poor conveyance of the recording medium are prevented.
That is, when the fixed member 26 contacts the reinforcing member 23 biased toward the upstream side or the downstream side in the transport direction, or when the contact width (distance B) of the fixed member 26 that contacts the reinforcing member 23 is narrow, etc. In this case, the fixing member 26, which receives pressure contact force at the nip portion, tends to rotate (easily fall over) in the clockwise or counterclockwise direction in FIG. . On the other hand, in the present embodiment, the fixing member 26 does not come into contact with the reinforcing member 23 biased toward the upstream side in the conveying direction or the downstream side in the conveying direction, and the contact width ( Since the distance B) is set to be sufficiently large, the fixing member 26 that receives pressure contact at the nip portion is supported in a well-balanced manner by the reinforcing member 23, and the fixing member 26 does not fall down using the contact portion with the reinforcing member 23 as a fulcrum. It becomes difficult.

Furthermore, in the first embodiment, only the portion of the fixing member 26 divided into the upstream protruding portion 26a and the downstream protruding portion 26b is configured to abut against the reinforcing member 23. The contact area between the reinforcing member 23 and the fixing member 26 can be reduced compared to a configuration in which one plane formed over a wide range from the side to the downstream comes into contact with the reinforcing member 23. It becomes difficult for heat to be transferred to the That is, it is possible to reduce the amount of heat transferred from the fixing belt 21 to the reinforcing member 26 through the fixing member 26 at the nip portion (the amount of heat escaping from the fixing belt 21 to the reinforcing member 23 via the fixing member 26 ). In particular, when the thickness of the fixing belt 21 is made thin (for example, when the thickness is set to 160 μm or less) or when the nip width is set wide, the amount of heat is easily transferred from the fixing belt 21 to the fixing member 26. Therefore, a configuration that reduces the contact area between the reinforcing member 23 and the fixing member 26 as in the first embodiment becomes useful.

Here, with reference to FIGS. 7 and 9, the fixing member 26 in the first embodiment has a plurality of rows of protrusions (upstream protrusions 26a and downstream protrusions 26b), respectively. It is divided into a plurality of parts at intervals in the width direction (the horizontal direction in FIGS. 7 and 9). Specifically, in the first embodiment, eight upstream protrusions 26a and eight downstream protrusions 26b are each formed at approximately equal intervals in the width direction. With such a configuration, the contact area between the reinforcing member 23 and the fixing member 26 can be further reduced, so that the above-mentioned effects can be more reliably exhibited.
In the first embodiment, the plurality of rows of protrusions 26a and 26b are configured to make surface contact with the opposing surface 23a of the reinforcing member 23, but in order to further ensure the above-mentioned effect, the plurality of rows of protrusions 26a and 26b are It is also possible to configure the protrusions 26a and 26b to make line contact or point contact (or close contact) with the opposing surface 23a of the reinforcing member 23, respectively. In the first embodiment, two rows of protrusions, the upstream protrusion 26a and the downstream protrusion 26b, are provided as the plurality of rows of protrusions, but three or more rows of protrusions are provided as the plurality of protrusions. It is also possible to provide

In addition, in the first embodiment, with reference to FIG. 4, when the fixing member 26 is viewed in a cross section perpendicular to the width direction, an imaginary straight line passing through the center of the transport direction in the nip portion and orthogonal to the transport direction (see FIG. This is the straight line shown by the dashed line in Fig. 4.).
With such a configuration, the fixing member 26 subjected to the pressure contact force at the nip portion is more easily supported by the reinforcing member 23 in a well-balanced manner, and the fixing member 26 is further prevented from collapsing.

Furthermore, in the first embodiment, as shown in FIG. 4, the length of the nip portion (nip width) with respect to the conveyance direction of the recording medium is set to A, and the fixing member 26 and the reinforcing member 23 are in contact with each other on the upstream side in the conveyance direction. The length of the reinforcing member 23 facing the fixing member 26 in the conveying direction is defined as B, which is the length from the upstream abutting part where they contact each other to the downstream abutting part where the fixing member 26 and the reinforcing member 23 abut on the downstream side in the conveying direction. When the length of the surface 23a is C,
A<B<C
It is formed so that the following relationship is established.
Further, in the conveyance direction, the range of the nip portion (range A in FIG. 4) is the range from the upstream contact portion to the downstream contact portion (range B in FIG. 4). ), and the range from the upstream contact part to the downstream contact part (range B in FIG. 4) is included in the range of the opposing surface 23a of the reinforcing member 23 (range C in FIG. 4). ).
In other words, the range of the nip width is included within the range of the conveyance direction (vertical direction in FIG. 4) of the fixing member 26 that contacts the reinforcing member 23. Further, the range of the opposing surface 23a of the reinforcing member 23 in the transporting direction includes the range of the fixing member 26 that contacts the reinforcing member 23 in the transporting direction.
With such a configuration, the fixing member 26 subjected to the pressure contact force at the nip portion is more easily supported by the reinforcing member 23 in a well-balanced manner, and the fixing member 26 is further prevented from collapsing.

Here, with reference to FIGS. 7 to 11, the sheet-like member 22 has a plurality of holes that fit into a plurality of rows of protrusions (upstream protrusions 26a and downstream protrusions 26b). 22b is formed. The sheet-like member 22 is installed in close contact with the fixing member 26 along the circumferential direction at a position excluding the plurality of rows of protrusions 26a and 26b.
Specifically, as shown in FIG. 10, the sheet-like member 22 has a rectangular shape when developed as a single component. At both ends of the rectangular sheet-like member 22, there are a plurality of holes 22a and 22b (holes that fit into the protrusions 26a and 26b) and a screw hole 22c (a screw hole for screws 24). A hole is formed through which the part is inserted.
When the sheet-like member 22 is covered with the fixed member 26, both ends of the rectangle are folded and overlapped between the upstream protrusion 26a and the downstream protrusion 26b (between the plurality of rows of protrusions). (the area surrounded by the broken line in FIG. 8 and the hatched area in FIG. 10) is formed. Then, as shown in FIG. 8, a plate-like member 28 (fixing plate) is fixed to the fixing member 26 with a plurality of screws 24 so as to sandwich the overlapping portion of the sheet-like member 22. Specifically, the plate member 28 is placed on the fixing member 26 via the overlap part so as to sandwich the overlap part of the sheet member 22, and the screw hole 28c of the plate member 28 (see FIG. 11). ) and the screw hole 22c of the sheet-like member 22, and the threaded portion of the screw 24 is screwed into the female threaded portion 26c of the fixing member 26 (see FIG. 9(B)). Here, the plurality of screws 24 are formed so that the height of the screw heads does not exceed the height of the protrusions 26a, 26b and contact the reinforcing member 23.

In this way, when the sheet-like member 22 is unfolded, the end portion corresponding to the upstream side in the conveyance direction and the end portion corresponding to the downstream side in the conveyance direction are fixedly held on the fixing member 26. Therefore, in addition to the case where the sheet-like member 22 receives a frictional force between it and the fixing belt 21 running toward the downstream side (during the normal fixing process), the sheet-like member 22 also moves toward the upstream side. Even if a frictional force is applied between the sheet-like member 22 and the fixing belt 21 running on the sheet-like member 22 (such as when the fixing belt 21 and the pressure roller 31 are manually rotated in reverse during jam removal), the sheet-like member 22 This will prevent problems such as a gap or wrinkles occurring between the fixing member 26 and the fixing member 26 due to displacement.
In particular, in the present embodiment, the overlapping portion of the sheet-like member 22 is sandwiched between the plate-like members 28, and the plate-like member 28 is fastened to the fixing member 26 with a plurality of screws 24 arranged approximately evenly in the width direction. Therefore, the fixing member 26 The sheet-like member 22 can be stably and firmly fixed to.

Further, the holes 22a and 22b of the sheet-like member 22 are fitted into the protrusions 26a and 26b of the fixing member 26, and the plate-like member 28 and the screw 24 are inserted between the protrusions 26a and 26b (at the center in the conveyance direction). Since it is installed, the fixing member 26 with the sheet-like member 22 installed can be made compact.
In addition, since the fixing member 26 with the sheet-like member 22 installed can be managed as a single sub-assembled part, parts management and assembly are improved during manufacturing and maintenance. be able to.
In addition, since the sheet-like member 22 is held by fitting into the plurality of protrusions 26a and 26b divided at approximately equal intervals in the width direction, even if the sheet-like member 22 is subjected to sliding contact force, the plurality of holes are Force is easily applied evenly to 22a and 22b, and the problem of damage to the sheet-like member 22 due to local stress concentration can be reduced.

As explained above, in the first embodiment, the protrusions 26a and 26b that protrude toward the reinforcing member 23 so as to come into contact with the reinforcing member 23 are formed in a plurality of rows along the conveying direction. has been done. As a result, the warm-up time and first print time are short, and even when the speed of the device is increased, fixing failure does not occur, and the problem of the fixing member 26 falling when the reinforcing member 23 is pressed is reduced. can do.

In the first embodiment, the fixing belt 21 having a multilayer structure is used as the fixing belt, but an endless fixing film made of polyimide, polyamide, fluororesin, metal, etc. can also be used as the fixing belt. Also in that case, the same effects as in the first embodiment can be obtained.

Embodiment 2.
Embodiment 2 of the present invention will be described in detail with reference to FIG.
FIG. 12 is a configuration diagram showing a fixing device in the second embodiment, and corresponds to FIG. 2 in the first embodiment. The fixing device according to the second embodiment differs from that of the first embodiment in that the fixing belt 21 is heated by electromagnetic induction.

As shown in FIG. 12, the fixing device 20 in the second embodiment also includes a fixing belt 21 (belt member), a fixing member 26, a reinforcing member 23, a pressure roller 31 ( It is composed of a heating rotating body), a temperature sensor 40, a sheet-like member 22, a screw 24, a plate-like member 28 (fixing plate), and the like.
Also, in the second embodiment, similarly to the first embodiment, the fixing member 26 has a plurality of rows of protrusions (upstream A side protrusion 26a and a downstream protrusion 26b) are formed.

Here, in the fixing device 20 according to the second embodiment, an induction heating section 50 is installed as a heating means instead of the heater 25. The fixing belt 21 in the second embodiment is heated by electromagnetic induction by the induction heating unit 50, unlike the fixing belt 21 in the first embodiment, which is heated by radiant heat from the heater 25.

The induction heating section 50 includes an excitation coil, a core, a coil guide, and the like. The excitation coil is a litz wire made of bundled thin wires extending in the width direction (perpendicular to the plane of the paper in FIG. 12) so as to cover a part of the fixing belt 21. The coil guide is made of a highly heat-resistant resin material and holds the excitation coil and core. The core is a semi-cylindrical member made of a ferromagnetic material such as ferrite (relative magnetic permeability is about 1000 to 3000). A side core is provided. The core is installed so as to face the excitation coil extending in the width direction.
On the other hand, in addition to the base material layer, elastic layer, and mold release layer described in the first embodiment, the fixing belt 21 includes a heat generating layer (for example, an elastic layer and a mold release layer) that are heated by electromagnetic induction by the induction heating section 50. layer, or the base material layer can be used as a heat generating layer). As the material of the heat generating layer, nickel, stainless steel, iron, copper, cobalt, chromium, aluminum, gold, platinum, silver, tin, palladium, an alloy made of a plurality of these metals, etc. can be used.

The fixing device 20 configured in this manner operates as follows.
When the fixing belt 21 is rotated in the direction of the arrow in FIG. 12, the fixing belt 21 is heated at a position facing the induction heating section 50. Specifically, by passing a high-frequency alternating current through the excitation coil, lines of magnetic force are formed around the fixing belt 21 so as to alternately switch in both directions. At this time, an eddy current is generated on the surface of the heat generating layer of the fixing belt 21, and Joule heat is generated due to the electric resistance of the heat generating layer itself. This Joule heat causes the heating layer to be heated by electromagnetic induction, and the fixing belt 21 is heated.
In order to efficiently heat the fixing belt 21 by electromagnetic induction, it is preferable that the induction heating section 50 be configured to face the entire circumferential area of the fixing belt 21.

As explained above, in the second embodiment as well, the fixed member 26 has protrusions 26a and 26b that protrude toward the reinforcing member 23 so as to come into contact with the reinforcing member 23. , are formed in multiple rows along the conveyance direction. As a result, the warm-up time and first print time are short, and even when the speed of the device is increased, fixing failure does not occur, and the problem of the fixing member 26 falling when the reinforcing member 23 is pressed is reduced. can do.

In the second embodiment, the fixing belt 21 is heated by electromagnetic induction heating, but the fixing belt 21 can also be heated by the heat of a resistance heating element. Specifically, a resistance heating element is brought into contact with part or all of the inner circumferential surface or outer circumferential surface of the fixing belt 21 . The resistance heating element is a planar heating element such as a ceramic heater, and a power source is connected to both ends thereof. Then, when a current is passed through the resistance heating element, the temperature of the resistance heating element increases due to its own electric resistance, and heats the fixing belt 21 in contact with the resistance heating element.
Even in such a case, by providing the upstream protrusion 26a and the downstream protrusion 26b on the fixing member 26, the same effects as in the second embodiment can be obtained.

It should be noted that the present invention is not limited to each of the embodiments described above, and that each of the embodiments described above may be modified as appropriate within the scope of the technical idea of the present invention in addition to what is suggested in each of the embodiments described above. is clear. Further, the number, position, shape, etc. of the constituent members are not limited to those in each of the embodiments described above, and can be set to a number, position, shape, etc. suitable for carrying out the present invention.

(Additional note)
(Additional note 1)
an endless fixing belt that runs in a predetermined direction to heat and melt the toner image and has flexibility;
a fixing member that is fixedly installed on the inner peripheral surface side of the fixing belt and forms a nip portion in which the recording medium is conveyed by being in pressure contact with the pressure rotating body through the fixing belt;
a reinforcing member that is fixed to the inner peripheral surface of the fixing belt and abuts the fixing member from inside the fixing belt to reinforce the fixing member;
Equipped with
The fixing device is characterized in that the fixing member includes a plurality of rows of protrusions that protrude toward the opposing surface of the reinforcing member so as to come into contact with the reinforcing member, along the conveyance direction of the recording medium.
(Additional note 2)
The plurality of rows of protrusions include an upstream protrusion that protrudes toward the opposing surface of the reinforcing member so as to come into contact with the reinforcing member on the upstream side with respect to the conveyance direction, and an upstream protrusion that protrudes toward the opposing surface of the reinforcing member on the upstream side with respect to the conveyance direction, and an upstream protrusion that protrudes toward the opposing surface of the reinforcing member on the downstream side with respect to the conveyance direction and a downstream protrusion protruding toward the opposing surface of the reinforcing member so as to come into contact with the reinforcing member.
(Additional note 3)
The fixing device according to appendix 1 or 2, wherein the plurality of rows of protrusions are each divided into a plurality of parts at intervals in the width direction.
(Additional note 4)
A sheet-like member made of a low-friction material and covered along the circumferential direction of the fixing member so as to be interposed in the width direction between the fixing member and the fixing belt at the nip portion. ,
The sheet-like member includes a plurality of holes that fit into the plurality of rows of protrusions, and is installed so as to closely contact the fixing member along the circumferential direction at positions excluding the plurality of rows of protrusions. The fixing device according to appendices 1 to 3, characterized in that:
(Appendix 5)
The sheet-like member has a rectangular shape when unfolded as an individual component, and when covered by the fixing member, both ends of the rectangle are folded between the plurality of rows of protrusions to form an overlapping part. formed,
The fixing device according to appendix 4, wherein the plate-like member is fixed to the fixing member with a plurality of screws so as to sandwich the overlapping portion of the sheet-like member.
(Appendix 6)
5. The fixing device according to appendix 4 or 5, wherein the sheet-like member is formed of a fibrous material impregnated with a lubricant.
(Appendix 7)
The fixing member is characterized in that, when viewed in a cross section perpendicular to the width direction, it is formed to be line symmetrical with respect to an imaginary straight line passing through the center of the nip portion in the transport direction and perpendicular to the transport direction. The fixing device according to any one of Supplementary Notes 1 to 6.
(Appendix 8)
a holding member that holds both ends of the fixing belt in the width direction;
heating means that opposes or contacts the fixing belt and heats the fixing belt;
The fixing device according to any one of appendices 1 to 7, further comprising:
(Appendix 9)
An image forming apparatus comprising the fixing device according to any one of appendices 1 to 8.

(Additional note)
(Appendix 11)
a flexible endless fixing belt;
a fixing member that is disposed on the inner peripheral surface side of the fixing belt and forms a nip portion in which the recording medium is conveyed by being in pressure contact with the pressure rotating body through the fixing belt;
a heater that directly opposes at least a portion of the fixing belt other than the nip portion and heats the fixing belt;
a reinforcing member disposed between the fixing member and the heater on the inner circumferential side of the fixing belt and abutting against the fixing member to reinforce the fixing member;
a holding member that holds both ends of the fixing belt in the width direction;
Equipped with
The reinforcing member is not in contact with the fixing belt when the fixing belt rotates,
The fixing member includes a plurality of rows of protrusions that protrude toward the opposite surface of the reinforcing member so as to come into contact with the reinforcing member along the conveyance direction of the recording medium, and the low-friction sheet-like member is provided across the width direction. A fixing device that contacts the fixing belt through a fixing device.
(Appendix 12)
The plurality of rows of protrusions include an upstream protrusion that abuts the opposing surface on the upstream side of the conveyance direction, and a downstream protrusion that abuts the opposing surface on the downstream side of the conveyance direction. The fixing device according to appendix 11, characterized in that:
(Appendix 13)
The fixing device according to appendix 11 or 12, wherein the plurality of rows of protrusions are each divided into a plurality of parts at intervals in the width direction.
(Appendix 14)
The low-friction sheet-like member includes a plurality of holes,
The fixing device according to attachments 11 to 13, wherein the plurality of holes fit into the plurality of rows of protrusions.
(Appendix 15)
The low-friction sheet-like member has a rectangular shape when unfolded as a single component, and when covered by the fixing member, both ends of the rectangle are folded and overlapped between the plurality of rows of protrusions. part is formed,
15. The fixing device according to appendix 14, further comprising a contact member that contacts the fixing member via the overlapping portion between the plurality of rows of protrusions.
(Appendix 16)
The fixing device according to appendix 14 or 15, wherein the low-friction sheet-like member is formed of a fibrous material impregnated with a lubricant.
(Appendix 17)
The fixing member is characterized in that, when viewed in a cross section perpendicular to the width direction, it is formed to be line symmetrical with respect to an imaginary straight line passing through the center of the nip portion in the transport direction and perpendicular to the transport direction. The fixing device according to any one of appendix 11 to appendix 16.
(Appendix 18)
The reinforcing member includes an upstream side wall portion that is upstream with respect to the opposing surface and provided substantially perpendicularly in a direction opposite to the fixing member, and an upstream wall portion that is provided downstream with respect to the opposing surface and is provided with the fixing member. The fixing device according to any one of attachments 11 to 17, further comprising: a downstream wall section that is provided substantially perpendicularly in a direction opposite to the upstream wall section and faces the upstream wall section.
(Appendix 19)
Assuming that the length of the nip portion with respect to the conveyance direction of the recording medium is A, the fixing member is formed on the downstream side of the conveyance direction from an upstream contact portion where the fixing member and the reinforcing member abut on the upstream side of the conveyance direction. When the length to the downstream contact portion where the and the reinforcing member come into contact is B,
A<B
As a relationship is established,
According to any one of Supplementary Notes 11 to 18, wherein the range of the nip portion is formed to be included in the range from the upstream side contact portion to the downstream side contact portion with respect to the conveyance direction. Fixing device as described.
(Additional note 20)
The fixing device according to any one of attachments 11 to 19, wherein the plurality of rows of protrusions are each formed in line contact or point contact with the opposing surface of the reinforcing member.
(Additional note 21)
The reinforcing member is provided with a heat insulating member on a part or all of the surface facing the heater,
The fixing device according to any one of attachments 11 to 20, wherein the fixing member is made of a material having heat insulating properties.
(Additional note 22)
An image forming apparatus comprising the fixing device according to any one of attachments 11 to 21.

(Additional note)
(Appendix 31)
a flexible endless fixing belt;
a fixing member that is disposed on the inner peripheral surface side of the fixing belt and forms a nip portion in which the recording medium is conveyed by being in pressure contact with the pressure rotating body through the fixing belt;
a heater that directly opposes at least a portion of the fixing belt other than the nip portion and heats the fixing belt;
a reinforcing member disposed between the fixing member and the heater on the inner peripheral surface side of the fixing belt and abutting the fixing member;
a holding member that holds both ends of the fixing belt in the width direction;
Equipped with
The reinforcing member is not in contact with the fixing belt when the fixing belt rotates,
The fixing member includes a plurality of rows of protrusions that protrude toward the opposing surface of the reinforcing member along the conveyance direction of the recording medium, and contacts the fixing belt across the width direction via the sheet-like member;
The fixing device is characterized in that the length of the protrusion in the width direction is longer than the length in the conveyance direction.
(Appendix 32)
The plurality of rows of protrusions include an upstream protrusion that abuts the opposing surface on the upstream side of the conveyance direction, and a downstream protrusion that abuts the opposing surface on the downstream side of the conveyance direction. The fixing device according to appendix 1, characterized in that:
(Appendix 33)
The fixing device according to appendix 31 or 32, wherein the plurality of rows of protrusions are each divided into a plurality of parts at intervals in the width direction.
(Appendix 34)
34. The fixing device according to appendix 33, wherein a plurality of the protrusions are provided at equal intervals in the width direction.
(Appendix 35)
The sheet-like member includes a plurality of holes,
The fixing device according to attachments 31 to 34, wherein the plurality of holes fit into the plurality of rows of protrusions.
(Appendix 36)
The sheet-like member has a rectangular shape when unfolded as an individual component, and when covered by the fixing member, both ends of the rectangle are folded between the plurality of rows of protrusions to form an overlapping part. formed,
The fixing device according to appendix 5, further comprising a contact member that contacts the fixing member via the overlapping portion between the plurality of rows of protrusions.
(Additional note 37)
The fixing device according to appendix 35 or 36, wherein the sheet-like member is formed of a fibrous material impregnated with a lubricant.
(Appendix 38)
The fixing member is characterized in that, when viewed in a cross section perpendicular to the width direction, it is formed to be line symmetrical with respect to an imaginary straight line passing through the center of the nip portion in the transport direction and perpendicular to the transport direction. The fixing device according to any one of appendix 31 to appendix 37.
(Appendix 39)
The reinforcing member includes an upstream side wall portion that is upstream with respect to the opposing surface and provided substantially perpendicularly in a direction opposite to the fixing member, and an upstream wall portion that is provided downstream with respect to the opposing surface and is provided with the fixing member. 39. The fixing device according to any one of attachments 31 to 38, further comprising: a downstream wall section that is provided substantially perpendicularly in a direction opposite to the upstream wall section and faces the upstream wall section.
(Additional note 40)
Assuming that the length of the nip portion with respect to the conveyance direction of the recording medium is A, the fixing member is formed on the downstream side of the conveyance direction from an upstream contact portion where the fixing member and the reinforcing member abut on the upstream side of the conveyance direction. When the length to the downstream contact portion where the and the reinforcing member come into contact is B,
A<B
As a relationship is established,
According to any one of appendices 31 to 39, characterized in that the range of the nip portion is formed to be included in the range from the upstream contact portion to the downstream contact portion with respect to the conveyance direction. Fixing device as described.
(Appendix 41)
An image forming apparatus comprising the fixing device according to any one of attachments 31 to 40.

(Additional note)
(Appendix 51)
a flexible endless fixing belt;
a nip forming member disposed inside the fixing belt and sandwiching the fixing belt with a pressure rotating body to form a nip portion in which a recording medium is conveyed between the fixing belt and the pressure rotating body; and,
a heating source that faces the fixing belt and heats the fixing belt;
a reinforcing member disposed inside the fixing belt and having an opposing surface that abuts the nip forming member;
a pair of guide members that guide both ends of the fixing belt in the width direction;
Equipped with
The nip forming member includes an upstream contact portion that contacts the opposing surface on the upstream side in the conveying direction of the recording medium, a downstream contact portion that contacts the opposing surface on the downstream side in the conveying direction, and a downstream contact portion that contacts the opposing surface on the downstream side in the conveying direction. a non-contacting part that does not contact the opposing surface between the side contacting part and the downstream contacting part;
The pair of guide members each have an insertion portion inside the fixing belt,
The fixing device is characterized in that the insertion portions are spaced apart from each other inside the fixing belt.
(Appendix 52)
The fixing device according to appendix 1, wherein the heat source is a radiant heat source.
(Appendix 53)
The fixing device according to appendix 2, wherein the radiant heat source is a halogen heater.
(Appendix 54)
The reinforcing member is disposed inside the fixing belt between the nip forming member and the heat source,
4. The fixing device according to any one of appendices 1 to 3, further comprising a reflective member provided between the reinforcing member and the heat source.
(Appendix 55)
The reinforcing member includes an upstream wall portion provided upstream with respect to the opposing surface and substantially perpendicular in a direction opposite to the nip forming member, and an upstream wall portion provided downstream with respect to the opposing surface and provided with the nip forming member. The fixing device according to any one of Supplementary Notes 1 to 4, further comprising a downstream side wall portion that is provided substantially perpendicularly in a direction opposite to the forming member and faces the upstream side wall portion.
(Appendix 56)
The fixing device according to appendix 5, wherein the upstream contact portion and the downstream contact portion are provided between the upstream wall portion and the downstream wall portion in the conveyance direction.
(Appendix 57)
According to any one of Supplementary Notes 1 to 6, wherein the opposing surface is a surface facing the nip forming member and extends downstream from the downstream contact portion in the conveyance direction. fixing device.
(Appendix 58)
The nip forming member has an upstream protrusion that protrudes toward the opposing surface, and a downstream protrusion that protrudes toward the opposing surface,
The upstream protrusion has the upstream contact portion,
The fixing device according to any one of appendices 1 to 7, wherein the downstream protrusion includes the downstream contact portion.
(Appendix 59)
A surface opposite to the opposing surface of the upstream protrusion is the upstream contact portion,
The fixing device according to appendix 8, wherein a surface of the downstream protrusion that faces the opposing surface is the downstream contact portion.
(Additional note 60)
A plurality of the upstream protrusions are arranged in the longitudinal direction of the nip forming member,
The fixing device according to appendix 8 or 9, wherein a plurality of the downstream protrusions are arranged in a longitudinal direction of the nip forming member.
(Additional note 61)
The fixing device according to any one of appendices 1 to 10, wherein a sheet-like member is interposed between the nip forming member and the fixing belt.
(Appendix 62)
The fixing device according to appendix 11, wherein the nip forming member is covered by the sheet-like member.
(Additional note 63)
The sheet-like member covering the nip forming member includes a plurality of holes,
The fixing device according to any one of appendices 8 to 10, wherein the plurality of holes are fitted with the upstream protrusion or the downstream protrusion.
(Additional note 64)
The fixing device according to any one of attachments 11 to 13, wherein the sheet-like member is made of a low-friction material.
(Appendix 65)
The fixing device according to any one of appendices 11 to 14, further comprising a member fixed to the nip forming member so as to sandwich the overlapping portion of the sheet-like member.
(Appendix 66)
The fixing device according to any one of appendices 1 to 15, wherein the nip forming member has a plurality of locations in contact with the opposing surface in a direction perpendicular to the conveying direction.
(Appendix 67)
An image forming apparatus comprising the fixing device according to any one of appendices 1 to 16.

1 Image forming device main body (device main body),
20 fixing device,
21 Fixing belt (fixing member),
22 sheet-like member,
23 reinforcing member,
24 screws (fixing screws),
25 heater (heating means),
26 Fixed member,
26a upstream protrusion, 26b downstream protrusion,
28 Plate member (fixed plate),
29 flange (retaining member),
31 Pressure roller (pressure rotating body).

Patent No. 2010-96782

Claims (16)

a flexible endless fixing belt;
a nip forming member disposed inside the fixing belt and sandwiching the fixing belt with a pressure rotating body to form a nip portion in which a recording medium is conveyed between the fixing belt and the pressure rotating body; and,
a heating source that faces the fixing belt and heats the fixing belt;
a reinforcing member disposed inside the fixing belt and having an opposing surface that abuts the nip forming member;
a pair of guide members that guide both ends of the fixing belt in the width direction;
Equipped with
The nip forming member includes an upstream contact portion that contacts the opposing surface on the upstream side in the conveying direction of the recording medium, a downstream contact portion that contacts the opposing surface on the downstream side in the conveying direction, and a downstream contact portion that contacts the opposing surface on the downstream side in the conveying direction. a non-contacting part that does not contact the opposing surface between the side contacting part and the downstream contacting part;
A fixing device characterized in that a sheet-like member is interposed between the nip forming member and the fixing belt. The fixing device according to claim 1, wherein the heat source is a radiant heat source. The fixing device according to claim 2, wherein the radiant heat source is a halogen heater. The reinforcing member is disposed inside the fixing belt between the nip forming member and the heat source,
The fixing device according to claim 1, further comprising a reflective member provided between the reinforcing member and the heat source. The reinforcing member includes an upstream wall portion provided upstream with respect to the opposing surface and substantially perpendicular in a direction opposite to the nip forming member, and an upstream wall portion provided downstream with respect to the opposing surface and provided with the nip forming member. 5. The fixing device according to claim 1, further comprising a downstream wall portion that is provided substantially perpendicularly in a direction opposite to the forming member and faces the upstream wall portion. The fixing device according to claim 5, wherein the upstream side contact portion and the downstream side contact portion are provided between the upstream side wall portion and the downstream side wall portion in the conveyance direction. . The opposing surface is a surface that faces the nip forming member and extends downstream of the downstream contact portion in the conveying direction. The fixing device described in . The nip forming member has an upstream protrusion that protrudes toward the opposing surface, and a downstream protrusion that protrudes toward the opposing surface,
The upstream protrusion has the upstream contact portion,
The fixing device according to any one of claims 1 to 7, wherein the downstream protruding portion has the downstream abutting portion. A surface opposite to the opposing surface of the upstream protrusion is the upstream contact portion,
9. The fixing device according to claim 8, wherein a surface of the downstream protrusion that faces the opposing surface is the downstream abutting section. A plurality of the upstream protrusions are arranged in the longitudinal direction of the nip forming member,
10. The fixing device according to claim 8, wherein a plurality of the downstream protrusions are arranged in a longitudinal direction of the nip forming member. The fixing device according to claim 1, wherein the nip forming member is covered with the sheet-like member. The sheet-like member covering the nip forming member includes a plurality of holes,
11. The fixing device according to claim 8, wherein the plurality of holes are fitted with the upstream protrusion or the downstream protrusion. The fixing device according to claim 1, wherein the sheet-like member is made of a low-friction material. 14. The fixing device according to claim 1, further comprising a member fixed to the nip forming member so as to sandwich the overlapping portion of the sheet-like member. 15. The fixing device according to claim 1, wherein the nip forming member has a plurality of locations in contact with the opposing surface in a direction perpendicular to the conveyance direction. An image forming apparatus comprising the fixing device according to any one of claims 1 to 15.

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