JP2022191660A - Belt member, fixation device, and image formation device - Google Patents

Abstract

To fully reduce abrasions caused by the sliding contact with a slide member.SOLUTION: In a fixation belt 21 (a belt member), the Martens hardness H1 (N/mm2) is 20≤H1≤70 and the pencil hardness H2 is in the range of HB to 2H, both inclusive, in an inner circumferential surface 21a (a slide surface) in sliding contact with a nip part formation member 26 (a sliding contact member). This can fully reduce the abrasion of the fixation belt 21 and the nip part formation member 26 by the sliding contact with the formation member 26 (a sliding member).SELECTED DRAWING: Figure 4

Description

The present invention relates to a belt member such as a fixing belt, a fixing device having the belt member, and an image forming apparatus such as a copier, printer, facsimile machine, or a multi-function machine thereof.

2. Description of the Related Art Conventionally, in image forming apparatuses such as copiers and printers, there has been known a technique of using a belt member such as a fixing belt which is in sliding contact with a sliding contact member (see, for example, Japanese Unexamined Patent Application Publication No. 2002-100003).

On the other hand, Japanese Patent Application Laid-Open No. 2002-100000 discloses that the Vickers hardness Hv1 of the inner surface of the fixing film and the ratio of the Vickers hardness Hv1 of the inner surface of the fixing film and the support member for the purpose of reducing wear due to sliding contact between the fixing film (belt member) and the support member (sliding contact member). A technique is disclosed for setting the relationship between the Vickers hardness Hv2 of the contact portion and |Hv1-Hv2|≤200.

The conventional belt member cannot sufficiently reduce wear between the belt member and the sliding contact member due to sliding contact with the sliding contact member.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a belt member, a fixing device, and an image forming apparatus in which wear due to sliding contact with a sliding contact member is sufficiently reduced. It is in.

The belt member according to the present invention has a Martens hardness H1 [N/mm ² ] of 20≦H1≦70 and a pencil hardness H2 of HB or more and 2H or less at the sliding contact surface that comes into sliding contact with the sliding contact member.

According to the present invention, it is possible to provide a belt member, a fixing device, and an image forming apparatus in which abrasion due to sliding contact with a sliding contact member is sufficiently reduced.

1 is an overall configuration diagram showing an image forming apparatus according to an embodiment of the present invention; FIG. 2 is a configuration diagram showing a fixing device; FIG. 3 is a side view of the fixing device as viewed in the width direction; FIG. It is an enlarged view showing the vicinity of the nip portion. 4 is a cross-sectional side view showing a fixing belt held by a holding member; FIG. 4 is an enlarged view showing the vicinity of the sliding contact surface between the fixing belt and the nip portion forming member; FIG. 6 is an enlarged view showing the vicinity of the sliding contact surface between the fixing belt and the nip portion forming member over time as a comparative example; FIG. FIG. 3 is a table showing experimental conditions and results; FIG. 10 is a configuration diagram showing a fixing device as a modified example;

BEST MODE FOR CARRYING OUT THE 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 redundant description thereof will be appropriately simplified or omitted.

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 this embodiment is a tandem color printer. Four toner bottles 102Y, 102M, 102C, and 102K corresponding to respective colors (yellow, magenta, cyan, and black) are detachably (exchangeably) installed in the bottle storage unit 101 above the image forming apparatus main body 1. ing.
An intermediate transfer unit 85 is arranged below the bottle accommodating portion 101 . Imaging units 4Y, 4M, 4C, and 4K corresponding to respective colors (yellow, magenta, cyan, and black) are arranged side by side so as to face the intermediate transfer belt 78 of the intermediate transfer unit 85 .

Photoreceptor drums 5Y, 5M, 5C and 5K are arranged in the image forming units 4Y, 4M, 4C and 4K, respectively. Further, a charging section 75, a developing section 76, a cleaning section 77, a neutralizing section (not shown), etc. are arranged around the respective photosensitive drums 5Y, 5M, 5C, and 5K. Then, an image forming process (charging process, exposure process, development process, transfer process, cleaning process, and static elimination process) is performed on each of the photoreceptor drums 5Y, 5M, 5C, and 5K. , 5C, and 5K are formed.

The photosensitive drums 5Y, 5M, 5C, and 5K are rotated clockwise in FIG. 1 by a driving motor (not shown). Then, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K are uniformly charged at the position of the charging section 75 (charging step).
After that, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K reach the irradiation position of the laser light L emitted from the exposure unit 3, and an electrostatic latent image corresponding to each color is formed by exposure scanning at this position. (This is the exposure process.)

After that, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K reach positions facing the developing section 76, and the electrostatic latent images are developed at this position to form toner images of each color (developing process is.).
After that, 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. , 5C, and 5K are transferred onto the intermediate transfer belt 78 (primary transfer step). At this time, a small amount of untransferred toner remains on the photosensitive drums 5Y, 5M, 5C, and 5K.

After that, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K reach a position facing the cleaning portion 77, and at this position the untransferred toner remaining on the photosensitive drums 5Y, 5M, 5C, and 5K is removed by the cleaning portion. It is mechanically collected by the cleaning blade of 77 (cleaning process).
Finally, the surfaces of the photoreceptor drums 5Y, 5M, 5C, and 5K reach a position facing the static elimination unit (not shown), and the residual potential on the photoreceptor drums 5Y, 5M, 5C, and 5K is removed at this position. be.
Thus, a series of image forming processes performed on the photosensitive drums 5Y, 5M, 5C, and 5K are completed.

After that, the toner images of each color formed on each photosensitive drum through the development process are superimposed and transferred onto the intermediate transfer belt 78 . A color image is thus 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, and 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 endlessly moved in the direction of the arrow in FIG.

The four primary transfer bias rollers 79Y, 79M, 79C and 79K sandwich the intermediate transfer belt 78 with the photosensitive drums 5Y, 5M, 5C and 5K respectively to form primary transfer nips. A transfer bias opposite in polarity to the toner is applied to the primary transfer bias rollers 79Y, 79M, 79C, and 79K.
The intermediate transfer belt 78 runs in the direction of the arrow and sequentially passes through the primary transfer nips of the primary transfer bias rollers 79Y, 79M, 79C, and 79K. In this way, the toner images of the respective colors on the photosensitive drums 5Y, 5M, 5C, and 5K are superimposed on the intermediate transfer belt 78 and primarily transferred.

After that, the intermediate transfer belt 78 on 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 sandwiches the intermediate transfer belt 78 with the secondary transfer roller 89 to form a secondary transfer nip. The four-color toner image formed on the intermediate transfer belt 78 is transferred onto the sheet P conveyed to the position of the secondary transfer nip. At this time, untransferred toner that has not been transferred onto the sheet P remains on the intermediate transfer belt 78 .
After that, the intermediate transfer belt 78 reaches the position of the intermediate transfer cleaning station 80 . At this position, untransferred toner on the intermediate transfer belt 78 is collected.
Thus, a series of transfer processes performed on the intermediate transfer belt 78 are completed.

Here, the sheet P conveyed to the position of the secondary transfer nip passes from the paper feeding unit 12 disposed below the apparatus main body 1 through the paper feeding roller 97, registration roller pair 98 (timing roller pair), and the like. It was transported by
Specifically, in the paper feeding unit 12, a plurality of sheets P such as transfer paper are stacked and stored. When the paper feed roller 97 is driven to rotate counterclockwise in FIG. 1, the topmost sheet P is fed between the rollers of the registration roller pair 98 .

The sheet P conveyed to the registration roller pair 98 temporarily stops at the roller nip position of the registration roller pair 98 whose rotational drive is stopped. Then, the registration roller pair 98 is rotationally driven in synchronization with the timing of the color image on the intermediate transfer belt 78, and the sheet P is conveyed toward the secondary transfer nip. A desired color image is transferred onto the sheet P in this manner.

Thereafter, the sheet P onto which the color image has been transferred at the position of the secondary transfer nip is conveyed to the position of the fixing device 20 . At this position, the color image transferred to the surface is fixed onto the sheet P by heat and pressure from the fixing belt 21 and pressure roller 31 .
After that, the sheet P passes between the rollers of the paper discharge roller pair 99 and is discharged outside the apparatus. The sheets P discharged outside the apparatus by the paper discharge roller pair 99 are sequentially stacked on the stack section 100 as an output image.
Thus, 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 5 and the like.
2 to 4, the fixing device 20 includes a fixing belt 21 as a belt member, a nip portion forming member 26 as a sliding contact member, a reinforcing member 23, a heater 25 (heat source) as heating means, It is composed of a pressure roller 31 as a pressure member, a temperature sensor 40, a reflecting member 27, and the like.

Here, the fixing belt 21 as a belt member is a thin flexible endless belt that rotates (runs) in the direction of the arrow (counterclockwise) in FIG. The fixing belt 21 has a base material layer, an elastic layer, and a release layer, which are sequentially laminated from the inner peripheral surface 21a (the surface in sliding contact with the nip portion forming member 26) side. It is set to 1 mm or less.
The base material layer 21A (see FIG. 6) of the fixing belt 21 has a layer thickness of about 30 to 70 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 about 100 to 300 μm, and is made of a rubber material such as silicone rubber, foamed silicone rubber, fluororubber, or the like. By providing the elastic layer, minute unevenness is not formed on the surface of the fixing belt 21 at the nip portion, and heat is evenly transferred to the toner image T on the sheet P, thereby suppressing the generation of the orange peel image.
The release layer of the fixing belt 21 has a layer thickness of about 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, the releasability (releasability) of the toner T (toner image) is ensured.
In the present embodiment, the substrate layer 21A of the fixing belt 21 has Martens hardness and pencil hardness on the inner peripheral surface 21a (the sliding contact surface with the nip portion forming member 26 and the flange 29). A surface layer 21Aa having an adjusted layer thickness of about 9 to 15 μm is provided, which will be described later in detail.

Further, the diameter of the fixing belt 21 is set to be approximately 15 to 120 mm.
A nip portion forming member 26, a heater (heating means), a reinforcing member 23, a reflecting member 27, and the like are fixed inside the fixing belt 21 (on the inner peripheral surface side).
Here, the nip portion forming member 26 is fixed so as to be in sliding contact with the inner peripheral surface 21 a (sliding contact surface) of the fixing belt 21 . A nip portion (fixing nip portion) where the sheet P is conveyed is formed by pressing the nip portion forming member 26 against the pressure roller 31 via the fixing belt 21 . 3 and 5, the nip portion forming member 26 is held by flanges 29 (holding members) fixedly supported by the side plates 43 of the fixing device 20 at both ends in the width direction. Further, the fixing belt 21 is rotatably held by flanges 29 at both ends in the width direction. The nip portion forming member 26 and the flange 29 will be described later in detail.
The fixing belt 21 is directly heated by radiant heat from a heater 25 (heating means) installed therein.

The heater 25 as heating means is a halogen heater (or a carbon heater), and both ends thereof are fixed to the side plates 43 of the fixing device 20 (see FIG. 3). A portion of the fixing belt 21 except for the nip portion is mainly heated by radiant heat from the heater 25 (heating means) whose output is controlled by the power supply section of the apparatus main body 1 . Further, heat is applied to the toner image T on the sheet P from the heated surface of the fixing belt 21 . 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 facing the surface of the fixing belt 21 . Further, the temperature of the fixing belt 21 (fixing temperature) can be set to a desired temperature by controlling the output of the heater 25 in this way.
Although one heater 25 is installed on the inner peripheral surface side of the fixing belt 21 in this embodiment, a plurality of heaters may be installed on the inner peripheral surface side of the fixing belt 21 .

As described above, in the fixing device 20 of the present 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 is locally heated. Therefore, even when the speed of the apparatus is increased, the fixing belt 21 is sufficiently heated, and the occurrence of fixing failure can be suppressed. That is, since the fixing belt 21 can be efficiently heated with a relatively simple configuration, the warm-up time and the first print time can be shortened, and the size of the apparatus can be reduced.
In particular, since the fixing device 20 in the present 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, The device 20 can be further reduced in cost and size.

Here, referring to FIG. 5, two flanges 29 as holding members are made of a heat-resistant resin material or the like, and are fitted to side plates 43 at both ends in the width direction of fixing device 20, respectively. 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), and the like. is provided.
In the present embodiment, the members that come into contact with the inner peripheral surface 21a of the fixing belt 21 are only the flanges 29 at both ends in the width direction and the nip portion forming member 26. There is no member (belt guide) that contacts and guides the rotation of the fixing belt 21 .

Here, in the present embodiment, a reinforcing member 23 that reinforces the strength of the nip portion forming member 26 that forms the nip portion is fixed to the inner peripheral surface of the fixing belt 21 . Referring to FIG. 3 , reinforcing member 23 is formed to have the same length in the width direction as nip portion forming member 26 , and both ends in the width direction thereof are attached to flanges 29 (holding members) of fixing device 20 . is held in Specifically, the reinforcing member 23 is sandwiched between the flange 29 and the nip portion forming member 26 to determine its position.
When the reinforcing member 23 contacts the pressure roller 31 via the nip portion forming member 26 and the fixing belt 21, the nip portion forming member 26 receives the pressure of the pressure roller 31 at the nip portion and is greatly deformed. Prevents trouble. In the present embodiment, the reinforcing member 23 is a substantially U-shaped plate-like member formed so that the recess faces the side where the heater 25 is located. In order to satisfy the functions described above, the reinforcing member 23 is preferably made of a metal material having high mechanical strength such as stainless steel or iron.

Further, in the present embodiment, a reflecting member 27 (reflecting plate) is fixed to the surface of the reinforcing member 23 facing the heater 25 . As a result, heat directed from the heater 25 toward the reinforcing member 23 (heat for heating 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 increases. It will improve further.
Similar effects 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, pressure roller 31 as a pressure member that contacts the outer peripheral surface of fixing belt 21 at the position of the nip portion (fixing nip portion) has a diameter of about 30 mm and a hollow metal core. An elastic layer 33 is formed on 32 . The elastic layer 33 of the pressure roller 31 (pressure member) is made of a material such as foamed silicone rubber, silicone rubber, or fluororubber. A thin release layer made of PFA, PTFE, or the like may be provided on the surface layer of the elastic layer 33 . The pressure roller 31 presses against the fixing belt 21 to form a desired nip portion between the two members. 3, the pressure roller 31 is provided with a gear 45 that meshes with a driving gear of a drive mechanism (not shown), and the pressure roller 31 moves in the direction of the arrow (clockwise) in FIG. rotationally driven. The pressure roller 31 is rotatably supported by side plates 43 of the fixing device 20 via bearings 42 at both ends in the width direction. A heat source such as a halogen heater may be provided inside the pressure roller 31 .

If the elastic layer 33 of the pressure roller 31 is made of a sponge-like material such as foamed silicone rubber, the pressure acting on the nip portion can be reduced. can be mitigated. Furthermore, the heat insulation of the pressure roller 31 is enhanced, and the heat of the fixing belt 21 is less likely to move to the pressure roller 31 side, so that the heating efficiency of the fixing belt 21 is improved.
Further, in the present embodiment, the fixing belt 21 is formed so that the diameter of the fixing belt 21 is approximately equal to the diameter of the pressure roller 31 , but the diameter of the fixing belt 21 is formed so as to be smaller than the diameter of the pressure roller 31 . You can also 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 sheet P delivered from the nip portion is easily separated from the fixing belt 21 .

Referring to FIG. 4, nip portion forming member 26 as a sliding contact member that slides against inner peripheral surface 21a (sliding contact surface) of fixing belt 21 has a surface 26a facing pressure roller 31 (sliding on fixing belt 21). The contact surface (see FIG. 6) is formed in a concave shape following the curvature of the pressure roller 31 . As a result, since the sheet P is delivered from the nip part so as to follow the curvature of the pressure roller 31, it is possible to prevent the problem that the sheet P after the fixing process is attracted to the fixing belt 21 and is not separated. can.
In this embodiment, the nip portion forming member 26 forming the nip portion is formed in a concave shape, but the nip portion forming member 26 forming the nip portion may also be formed in a planar shape. That is, the facing surface 26a of the nip portion forming member 26 (the surface that slides against the fixing belt 21) can be formed in a planar shape. As a result, the shape of the nip portion becomes substantially parallel to the image surface of the sheet P, and the adhesion between the fixing belt 21 and the sheet P increases, thereby improving the fixability. Furthermore, since the curvature of the fixing belt 21 on the exit side of the nip portion is large, the sheet P delivered from the nip portion can be easily separated from the fixing belt 21 .

As a material for forming the nip portion forming member 26 as a sliding contact member, a resin material or a metal material can be used. A rigid, heat-resistant and heat-insulating resin material (liquid crystal polymer, polyamide-imide, polyimide, etc.) is suitable.
Also, the facing surface 26a of the nip portion forming member 26 (including the case where the surface is coated) may be formed with grooves or convex patterns.

The facing surface 26a of the nip portion forming member 26 (the surface in sliding contact with the fixing belt 21) is coated with a low-friction material (for example, diamond-like carbon, PTFE, etc.) in order to reduce sliding resistance with the fixing belt 21. , molybdenum disulfide, graphite, etc.) is preferably coated. In this case, the coating layer can be formed by forming a film of the above-mentioned low-friction material-dispersed paint on the opposing surface 26a of the nip portion forming member 26 made of a resin material by a method such as spray painting, and then baking the film. can.
In addition, the facing surface 26a of the nip portion forming member 26 (including the case where the surface is coated) is coated with a lubricant (for example, silicone oil, the base oil of which is silicone oil) in order to reduce sliding resistance with the fixing belt 21. silicone grease, fluorosilicone oil, fluorosilicone grease whose base oil is fluorosilicone oil, fluorine oil, fluorine grease whose base oil is fluorine oil, or a combination of any two or more of these. ) can also be applied.
Further, in this embodiment, the heater 25 is used as a heating means for heating the fixing belt 21 . On the other hand, by using a ceramic heater or the like as the nip portion forming member 26, the nip portion forming member 26 that functions as a sliding contact member can also be configured to function as a heating means. In this case, the facing surface 26a of the nip portion forming member 26 may be made of an inorganic material such as glass or ceramics, or may be made of a resin coating film formed on the outermost surface.

Here, in this embodiment, the reinforcing member 23 (and the reflecting member 27) is installed so as to separate the space between the nip portion forming member 26 and the heater 25 (heating means).
In this embodiment, the heater 25 is installed so as to face a relatively wide range in the circumferential direction of the fixing belt 21 (inner peripheral surface 21a). 21 can be heated in the circumferential direction without temperature unevenness. Therefore, after receiving a print request, the print operation can be performed quickly. At this time, in a conventional on-demand fixing device (see, for example, Japanese Patent No. 2884714), if heat is applied to the pressure roller while it is deformed in the nip portion while waiting for heating, the rubber of the pressure roller will be deformed. Depending on the material of the roller, heat deterioration may occur, shortening the life of the pressure roller, or permanent compression strain may occur in the pressure roller. increase by joining). When compression set occurs in the pressure roller, a portion of the pressure roller becomes dented and the desired nip width cannot be obtained, resulting in poor fixing and abnormal noise during rotation. do.
On the other hand, in the present embodiment, since the reinforcing member 23 (and the reflecting member 27) is installed between the nip portion forming member 26 and the heater 25 so as to block the heat of the heater 25, Heat is less likely to reach the nip portion forming member 26 during standby for heating. Therefore, it is possible to reduce the problem that the pressure roller 31 is heated to a high temperature in a deformed state during standby for heating, thereby preventing the above-described problem from occurring.

Further, when a lubricant is applied between the nip portion forming member 26 and the fixing belt 21 in order to reduce the frictional resistance between the two members, the lubricating agent deteriorates due to use under high temperature conditions in addition to high pressure conditions at the nip portion. , there is a possibility that problems such as slippage of the fixing belt 21 may occur.
On the other hand, in the present embodiment, since the reinforcing member 23 (and the reflecting member 27) is installed between the nip portion forming member 26 and the heater 25 so as to block the heat of the heater 25, Heat from the heater 25 is less likely to reach the lubricant in the nip portion. Therefore, deterioration of the lubricant due to high temperature is reduced, and the occurrence of the above-described problems can be suppressed.

Further, in this embodiment, since the reinforcing member 23 (and the reflecting member 27) is installed between the nip portion forming member 26 and the heater 25 so as to block the heat of the heater 25, the nip portion is formed. Since the member 26 is insulated, the fixing belt 21 is not actively heated at the nip portion. Therefore, the temperature of the sheet P fed into the nip portion is lowered when the sheet P is fed from the nip portion. That is, at the exit of the nip portion, the temperature of the toner image fixed on the sheet P is lowered, the viscosity of the toner is lowered, and the adhesive force of the toner to the fixing belt 21 is reduced. 21. Therefore, the problem that the sheet P immediately after the fixing process is wrapped around the fixing belt 21 and jams is prevented, and the fixation of the toner 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 the pressure roller 31 is started to rotate in the direction of the arrow in FIG. As a result, the fixing belt 21 is also driven (rotated) in the direction of the arrow in FIG.
After that, the sheet P is fed from the paper feeding unit 12 , and the unfixed color image is carried (transferred) on the sheet P at the position of the secondary transfer roller 89 . The sheet P bearing the unfixed image T (toner image) is conveyed in the direction of arrow Y10 in FIG. sent to the department.
Then, the toner image T is fixed on the surface of the sheet P by the heating by the fixing belt 21 heated by the heater 25 and the pressing force between the nip portion forming member 26 reinforced by the reinforcing member 23 and the pressure roller 31 . be. Thereafter, the sheet P delivered from the nip portion is conveyed in the arrow Y11 direction.

The fixing belt 21, which is characteristic of the fixing device 20 (image forming apparatus 1) according to the present embodiment, will be described in detail below.
As described above with reference to FIGS. A pressure roller 31 as a pressure member forming a nip portion (fixing nip portion) where the sheet P is conveyed by being pressed against the portion forming member 26 (sliding contact member), a flange 29, and the like are installed.
The inner peripheral surface 21a of the fixing belt 21 (belt member) serves as a sliding contact surface that makes sliding contact with the nip portion forming member 26 and the flange 29 as sliding contact members.

Here, the fixing belt 21 (belt member) in this embodiment has an inner peripheral surface as a sliding contact surface that makes sliding contact with a sliding contact member (in this embodiment, the nip portion forming member 26 and the flange 29). The Martens hardness H1 [N/mm ² ] of 21a is 20≦H1≦70, and the pencil hardness H2 is HB or more and 2H or less.
Specifically, in the present embodiment, the base material layer 21A of the fixing belt 21 (the innermost layer in the laminated structure) is the inner peripheral surface 21a (the sliding contact surface with the nip forming member 26). ) side is provided with a surface layer 21Aa having a layer thickness of about 9 to 15 μm. This surface layer 21Aa (the inner peripheral surface 21a of the base layer 21A (fixing belt 21)) is a mixture of polyimide varnish (or polyamide resin), PTFE, and carbon black, and has a Martens hardness of H1 [N/mm ² ] satisfies 20≤H1≤70, and the pencil hardness H2 is adjusted to HB or more and 2H or less.

The "Martens hardness" is an index indicating the degree of hardness by the load required to form a dent of a certain depth by scratching the object to be measured with an indenter.
"Pencil hardness" is the value of the hardest pencil scale that leaves no scar on the measurement object.

By configuring in this way, even if the nip portion forming member 26 or the flange 29 and the fixing belt 21 are in sliding contact with each other, wear of the fixing belt 21, the nip portion forming member 26 or the flange 29 can be reduced.

The reason for this will be described in detail below.
Conventionally, in the fixing device 20, at the fixing nip portion, the sliding resistance between the inner peripheral surface 21a of the fixing belt 21 and the nip portion forming member 26 as a sliding contact member is large, and abrasion powder from these members is generated. was happening a lot. In particular, even if a lubricant is applied to the sliding contact surfaces of these members in order to reduce the sliding resistance at the fixing nip portion, the viscosity of the lubricant increases due to mixing of the lubricant and abrasion powder. On the contrary, the drive torque of the device has increased.
If the Martens hardness or the pencil hardness of the fixing belt 21 is simply set to be large in order to solve such a problem, the wear of the fixing belt 21 can be reduced, but the nip portion forming member 26 (sliding contact) can be reduced. member) wear is accelerated. This is because hardness is generally a property that serves as an indicator of hardness, that is, which of two different substances is scratched when they are brought into sliding contact with each other.
For this reason, conventionally, the problem has been solved by the following two approaches.
The first approach is to adjust the relationship between the hardness of the fixing belt and the hardness of the sliding contact member to a certain fixed relationship, thereby minimizing the total amount of abrasion powder generated in both members. is. Although this approach has had some effect, it has not been able to sufficiently reduce the wear of both members. That is, in this approach, by aiming at a point where both members wear out little by little, setting is merely made so as to satisfy the life of the fixing device, and the wear itself is not sufficiently reduced.
A second approach is to use a lubricant to reduce contact between both members. In this approach, it is important to control the oil film formed by the lubricant, and it is theoretically possible to completely prevent wear by controlling the material and surface properties. However, due to the limitations of mechanical precision, such as slight irregularities and undulations inherent in organic materials, it has been difficult to achieve a completely non-contact lubricating state for both members. In addition, if the fixing device is designed so that the maximum performance is achieved at high temperatures, the drive torque at low temperatures increases, and there is some inconvenience in setting the temperature range that can be handled. In addition, it has been extremely difficult to realistically achieve an ideal oil film due to factors such as the absorption of lubricating oil by organic materials, volatilization, and the occurrence of wear due to extrinsic impurities.

In order to solve such a problem, the inventors of the present application conducted analyzes and experiments, and as a result, focused on two types of hardness, the Martens hardness H1 and the pencil hardness H2, and set the Martens hardness H1 low. Therefore, the wear of the inner peripheral surface 21a of the fixing belt 21 is reduced by manufacturing the fixing belt 21 having the inner peripheral surface 21a (sliding contact surface) having contradictory characteristics such that the pencil hardness H2 is set high. In addition, the wear of the sliding contact member (nip forming member 26) can be reduced.
The inner peripheral surface 21a of the fixing belt 21, which has a low Martens hardness and a high pencil hardness, is locally and temporarily affected by the influence of roughness, undulation, vibration, etc. slightly present in the sliding contact member (nip portion forming member 26). Even if the sliding pressure is increased, the surface layer 21Aa having the inner peripheral surface 21a is softly deformed, thereby exerting a suspension effect. Therefore, a highly robust sliding state can be realized, and while the wear of the inner peripheral surface 21a of the fixing belt 21 is prevented, the wear of the sliding contact member (nip forming member 26) can also be prevented.
Martens hardness contains a relatively large amount of hardness information near the outermost surface.
On the other hand, the pencil hardness contains relatively much information about the adhesive force between the surface layer 21Aa and its underlying layer. In other words, the mechanism is considered to be that the surface layer 21Aa, which is soft on the surface but hard on the inside and adheres firmly to the substrate, does not wear the sliding contact member and itself does not wear.

FIG. 6 is an enlarged view of a portion where the inner peripheral surface 21a (surface layer 21Aa) of the fixing belt 21 and the opposing surface 26a of the nip portion forming member 26 are in sliding contact.
As shown in FIG. 6A, when at least one of the inner peripheral surface 21a (surface layer 21Aa) and the opposing surface 26a is made of an organic material, the inner peripheral surface 21a and the opposing surface 26a are not mirror surfaces but have a certain degree of will have roughness.
However, in the present embodiment, the inner peripheral surface 21a (surface layer 21Aa) has a low Martens hardness and a high pencil hardness, so that the surface layer 21Aa is very soft and has a high deformability. Therefore, even if the inner peripheral surface 21a and the opposing surface 26a are in sliding contact with each other for a long time and are affected by roughness, undulation, vibration, contamination, etc., their displacements are buffered, as shown in FIG. As shown in B), the inner peripheral surface 21a and the opposing surface 26a are brought into sliding contact with each other while the roughness of the inner peripheral surface 21a and the opposing surface 26a is maintained without being reduced. That is, the sliding resistance between the inner peripheral surface 21a and the opposing surface 26a is prevented from locally and temporarily increasing, and abrasion powder is less likely to occur on the inner peripheral surface 21a and the opposing surface 26a. In other words, since the surface layer 21Aa is very soft, abrasion dust is less likely to occur not only from the fixing belt 21 (surface layer 21Aa) but also from the nip portion forming member 26 (opposing surface 26a).
On the other hand, when the conventional fixing belt 121 (see FIG. 7) is used, the inner peripheral surface 121a (base material layer 121A) of the fixing belt 121 and the facing surface 26a of the nip portion forming member 26 are If they are in sliding contact for a long period of time, wear progresses from places where the sliding pressure is locally and temporarily increased due to the effects of roughness, undulation, vibration, contamination, etc. on both sides. Therefore, the abrasion powder generated by such abrasion causes a further localized pressure increase, and even if the inner peripheral surface 121a and the opposing surface 26a initially have roughness, eventually the 7, the inner peripheral surface 121a and the opposing surface 26a are in a state close to a mirror surface. When the wear between the inner peripheral surface 121a and the facing surface 26a becomes large, problems such as an increase in the drive torque of the apparatus and a problem in which the original functions of the fixing belt 1 and the nip portion forming member 26 are deteriorated occur. will occur.

In contrast, when the fixing belt 21 of the present embodiment is used, wear of the fixing belt 21 and the nip portion forming member 26 (and the flange 29) can be reduced over time.
Focusing on the process of generating abrasion powder from the inner peripheral surface 21a (surface layer 21Aa), the inner peripheral surface 121a of the conventional fixing belt 121 (see FIG. 7) deforms from the sliding contact member (nip forming member 26). When a force is applied and the generated displacement reaches its limit, a part of the inner peripheral surface 121a is detached as abrasion powder. Therefore, in the present embodiment, when the inner peripheral surface 21a (surface layer 21Aa) of the fixing belt 21 is subjected to a deformation force, rather than being hardened to resist the deformation force, displacement is easily generated. In order to prevent abrasion powder from detaching from the film, the Martens hardness of the inner peripheral surface 21a (surface layer 21Aa) is lowered and the pencil hardness is increased. That is, the Martens hardness is an index of how easily the mating member (nip forming member 26) is scratched due to the hardness of the outermost surface (inner peripheral surface 21a), and the pencil hardness is an index of the mating member (nip forming member 26). Since it is an index of the difficulty of falling off of the surface layer film when receiving an impact force (attack) from the member 26), the fixing belt 21 having contradictory characteristics of low Martens hardness and high pencil hardness is useful for abrasion prevention. Become.

Here, the fixing belt 21 (belt member) in the present embodiment has a permanent strain of 50% or more and 80% or less with respect to the indentation depth when measuring the Martens hardness H1 on the inner peripheral surface 21a (sliding contact surface). It is formed to be
Further, in the fixing belt 21 (belt member) in the present embodiment, the layer thickness of the surface layer 21Aa having the inner peripheral surface 21a (sliding contact surface) is set to 10 μm or more.
By configuring in this manner, the effect of reducing wear of the fixing belt 21, the nip portion forming member 26, and the flange 29 described above is further exhibited.

The reason for this will be described in detail below.
When the inner peripheral surface 21a (surface layer 21Aa) of the fixing belt 21 receives a deformation force from the nip portion forming member 26, the surface layer 21Aa of the fixing belt 21 is easily deformable, and the thickness Thicker is better. Further, the deformation of the inner peripheral surface 21a (surface layer 21Aa) at that time is not elastic deformation, but plastic deformation maintains the effect of reducing the generation of abrasion powder for a long time.
Therefore, the surface layer 21Aa, which has a permanent strain (residual strain) of 50% or more with respect to the indentation depth at the time of Martens hardness measurement and a layer thickness of 10 μm or more, can be used for both the fixing belt 21 and the nip portion forming member 26. Wear can be significantly reduced over the long term. This is because when a material having excellent elastic deformation properties is used for the surface layer 21Aa, it is possible to maintain a state in which no scratches are made as long as the deformation is within the elastic deformation region. This is because when deformation exceeding the elastic deformation region occurs, cohesive failure, that is, the generation of abrasion powder occurs. This is because materials with excellent elastic deformation generally have a crosslinked structure, a high molecular weight, or few grain boundaries. It is considered that this is because the breakage and fatigue failure of the steel occur.
On the other hand, when a soft material with excellent plastic deformation property is used as the surface layer 21Aa, the molecular weight is low and the grain boundaries are large. However, it is thought that the material is difficult to separate as abrasion powder and stabilizes again in the state after deformation.
From these facts, the deformation of the inner peripheral surface 21a (surface layer 21Aa) of the fixing belt 21 is not elastic deformation, but plastic deformation is less likely to generate abrasion powder even if it is scratched. Such an effect will be maintained for a long time.

Here, the fixing belt 21 (belt member) in the present embodiment is formed such that the emissivity of the inner peripheral surface 21a (sliding contact surface) is 0.94 or more. Specifically, the material and color of the fixing belt 21 (particularly the surface layer 21Aa) are selected so as to achieve such an emissivity.
This “emissivity” is the ease with which heat is emitted from an object, and is represented by a number between 0 and 1 (the closer to “0”, the less heat is emitted, and the closer to “1”, the more heat is emitted). easy to radiate). The emissivity is the emissivity when the temperature of the object surface is measured with a thermometer and the measured temperature matches the temperature of the radiation thermometer whose thermal radiation is set to "1".
"Emissivity" is also the receptivity of light to thermal energy. Therefore, when the fixing belt 21 with high emissivity is used, the heat energy generated from the heater 25 can be efficiently received, energy loss is reduced, and the fixing device 20 with a long life and high energy efficiency is realized. be able to. In particular, when the emissivity of the fixing belt 21 is less than 0.94, sufficient energy saving and durability cannot be obtained.
In the fixing device 20 according to the present embodiment, the emissivity of the fixing belt 21 (inner peripheral surface 21a) is set to 0.94 or higher, so energy saving and high durability can be improved.

The conditions and results of experiments conducted by the inventors of the present application to confirm the effects of the present invention will be described below with reference to FIG.
As shown in FIG. 8, as Examples 1 to 5 and Comparative Examples 1 to 5, ten fixing belts 21 having different Martens hardness and pencil hardness (and permanent deformation) were used. An experiment was conducted to confirm the durability of 20).

The "Martens hardness" of the inner peripheral surface 21a of the fixing belt 21 is measured using a measuring device "Fischerscope HCU H100VP" under the measurement conditions of a diamond indenter (surface angle of 136°), indentation depth of 5 µm, The indentation speed was 5 μm/20 s (same for both loading and unloading).
The measurement was performed 10 times in an environment of 23°C, and the average value was used. Further, in order to reduce floating during measurement, the fixing belt 21 was fixed to a metal stage having a flat surface with an R of about 20 mm, and the measurement was performed. In addition, if there is an elastic layer made of silicone rubber or PFA on the inner peripheral surface 21a side of the fixing belt 21, it is removed and the base material layer 21A (made of stainless steel, nickel, polyimide, etc.) of the fixing belt 21 is removed. was in direct contact with the metal stage. In addition, avoid using double-sided tape or the like to secure it to the back. Martens hardness was taken as a value at a depth of 1 μm.
In addition, "permanent strain" in FIG. 8 is the residual strain of the inner peripheral surface 21a (surface layer 21Aa), which is the value of the indentation depth at the moment when there is no load at the end of the experiment in the indentation depth-load curve. is the value [μm] read from the graph, and the value obtained by dividing 5 [μm], which is the indentation depth, was expressed as a percentage. That is, the "permanent strain" in FIG. 8 is the ratio (%) of the permanent strain to the indentation depth when measuring the Martens hardness.

On the other hand, the "pencil hardness" of the inner peripheral surface 21a of the fixing belt 21 was measured according to JIS-K5600.
However, a pencil (pencil scale) made by MITSUBISHI was used. In addition, for evaluation of scars, since only the adhesiveness of the surface layer 21Aa of the base material layer 21A was to be evaluated, the state in which the surface layer 21Aa was scraped and the main part of the base material layer 21A was completely exposed was determined to be "failed". . For example, if the base material layer 21A is made of stainless steel or nickel, the surface layer 21Aa does not remain at all in the area scratched with a pencil and the metallic luster can be clearly confirmed.
On the other hand, if even a small portion of the surface layer 21Aa remained at the scratched location, the pencil scale was set as "accepted". For example, when the surface layer 21Aa remains to some extent, the main portion of the base layer 21A may be seen through.
The residual condition of the surface layer 21Aa was measured with a micrometer, a laser microscope, or the like. When it was difficult to decide whether to pass or fail, the hardness of the pencil scale was increased, and when the state in which the main portion of the base layer 21A was completely exposed was confirmed, the failure was determined.

For the "durability evaluation" of the fixing belt 21, the fixing device 2 (installed in an electrophotographic image forming apparatus manufactured by Ricoh Co., Ltd.) shown in FIG. Fixing belts 21 of Examples 1 to 5 and Comparative Examples 1 to 5 were incorporated into the modified ones. In the "durability evaluation", the fixing belt 1 is subjected to a predetermined pressure and temperature, and the running sequence during printing is repeated. ], the highest value among the driving torques [N/m] of the motor until reaching . For the driving torque at the time of evaluation, the value during running at the running speed to be evaluated (for example, 300 [mm/s]) was used without using the instantaneous value at the time of operation or stop.
Also, the amount of lubricant applied to the fixing belt 21 was specified by the product (for example, 5 [g]) and was not replenished after the start of the evaluation.
In addition, since the driving torque [N/m] of the motor depends on the size and configuration of the device and the linear speed, it is standardized by the rated value of the driving torque of the motor (for example, 1.0 [N/m]). The percentage was used as the "durability evaluation result". Then, when 0 ≤ 100 x maximum drive torque value / rated drive torque value < 100 [%], the torque is judged to be OK (judgment "○"), and 100 [%] ≤ 100 x maximum drive torque value / rated drive torque value In some cases, the torque was NG (judgment "x").

In addition, the fixing belt 21 used in "Example 1" in FIG. A release layer made of PFA and having a layer thickness of 0.03 mm is formed on the substrate. In addition, this fixing belt 21 has a surface layer 21Aa of the base material layer 21A, which has a layer thickness of 15 μm, and is spray-coated with 20% by weight of polyimide varnish, 80% by weight of PTFE particles, and carbon black. A calcined one was used. However, the polyimide varnish was blended by weight after curing. A final firing was then carried out at 300°C.
On the other hand, the fixing belt 21 used in "Example 2" has a layer thickness of 13 μm as the surface layer 21Aa of the base material layer 21A, and the final baking is performed at 330° C. 1”.
In addition, the fixing belt 21 used in "Example 3" was the same as in "Example 1" except that the surface layer 21Aa of the base material layer 21A had a layer thickness of 21 µm and the final baking was performed at 280°C. It is the same as a thing.
In addition, the fixing belt 21 used in "Example 4" has a layer thickness of 9 μm as the surface layer 21Aa of the base layer 21A, and is sprayed with 20% by weight of polyamideimide resin, 80% by weight of PTFE particles, and carbon black. Same as "Example 1" except that it was painted and the final baking was done at 270°C.
In addition, the fixing belt 21 used in "Example 5" was the same as in "Example 4" except that the surface layer 21Aa of the base material layer 21A had a layer thickness of 14 µm and the final baking was performed at 300°C. It is the same as a thing.

Further, the fixing belt 21 used in "Comparative Example 1" in FIG. is the same as that of "Example 1" except that it was spray-coated and the final baking was performed at 300°C.
In addition, the fixing belt 21 used in "Comparative Example 2" has the same structure as in "Example 1" except that the surface layer 21Aa of the base material layer 21A has a layer thickness of 15 µm and the final baking is performed at 230°C. It is the same as a thing.
In the fixing belt 21 used in "Comparative Example 3", the surface layer 21Aa of the base layer 21A has a layer thickness of 13 μm, and is spray-coated with 60% by weight of polyimide varnish, 40% by weight of PTFE particles, and carbon black. Then, the final firing was performed at 350° C., the same as in “Example 1”.
In the fixing belt 21 used in "Comparative Example 4", the surface layer 21Aa of the base material layer 21A has a layer thickness of 9 μm, and is spray-coated with 10% by weight of polyimide varnish, 90% by weight of PTFE particles, and carbon black. Then, the final firing was performed at 280° C., the same as in “Example 1”.
In the fixing belt 21 used in "Comparative Example 5", the surface layer 21Aa of the base material layer 21A has a layer thickness of 9 μm, and is spray-coated with 30% by weight of polyimide varnish, 70% by weight of PTFE particles, and carbon black. Then, the final firing was performed at 330° C., which was the same as that of “Example 1”.

From the experimental results of Examples 1 to 5 and Comparative Examples 1 to 5 in FIG. 8, the effect of the present invention described above can be confirmed.
That is, by using the fixing belt 21 formed such that the inner peripheral surface 21a has a Martens hardness H1 [N/mm ² ] of 20≦H1≦70 and a pencil hardness H2 of HB or more and 2H or less, Wear of the belt 21 and the nip portion forming member 26 is sufficiently reduced, and an increase in driving torque (decrease in durability) of the device is reduced.
Further, the permanent strain when measuring the Martens hardness H1 on the inner peripheral surface 21a is formed to be 50% or more and 80% or less with respect to the indentation depth, and the layer thickness of the surface layer 21Aa is set to 10 μm or more. By using the fixing belt 21, the effects described above are further exhibited.

<Modification>
As shown in FIG. 9, the fixing device 20 in the modified example is of the electromagnetic induction heating type, and the fixing belt 21 is heated by electromagnetic induction.
As shown in FIG. 9, the fixing device 20 in the modified example also includes a fixing belt 21 (belt member), a nip portion forming member 26 (sliding contact member), a reinforcing member 23, and a pressure roller 31 in the same manner as in FIG. (heating member), a temperature sensor 40, and the like.
Here, instead of the heater 25, the fixing device 20 in the modified example is provided with an induction heating section 50 as a heating means. Then, the fixing belt 21 in the modified example is heated by electromagnetic induction by the induction heating section 50 .
The induction heating unit 50 is composed of an excitation coil, a core, a coil guide, and the like. The exciting coil is a Litz wire bundled with fine wires extending in the width direction (perpendicular to the paper surface of FIG. 9) so as to partially cover the fixing belt 21 . The coil guide is made of a highly heat-resistant resin material or the like, and holds the excitation coil and core. The core is a semicylindrical member made of a ferromagnetic material (having a relative magnetic permeability of about 1000 to 3000) such as ferrite. A side core is provided. The core is installed so as to face the exciting coil extending in the width direction.
On the other hand, in the fixing belt 21, apart from the base material layer, the elastic layer, and the release layer described with reference to FIG. layer, or the substrate layer can be used as a heat-generating layer.) is formed. As materials for the heat generating layer, nickel, stainless steel, iron, copper, cobalt, chromium, aluminum, gold, platinum, silver, tin, palladium, alloys composed of a plurality of these metals, and the like can be used.
Then, when the fixing belt 21 is driven to rotate in the direction of the arrow in FIG. More specifically, by passing a high-frequency alternating current through the excitation coil, magnetic lines of force are formed around the fixing belt 21 so as to alternately switch between two 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 by the electrical resistance of the heat generating layer itself. The Joule heat heats the heating layer by electromagnetic induction, thereby heating the fixing belt 21 .
In the electromagnetic induction heating type fixing device 20 configured as described above, the Martens hardness H1 [N/ mm ² ] is 20≦H1≦70, and the pencil hardness H2 is HB or more and 2H or less.
As a result, abrasion of the fixing belt 21 and the nip forming member 26 due to sliding contact with the nip forming member 26 (sliding contact member) is sufficiently reduced.

As described above, the fixing belt 21 (belt member) in the present embodiment has a Martens hardness H1 [N/mm ² ] is 20≦H1≦70, and the pencil hardness H2 is HB or more and 2H or less.
As a result, abrasion of the fixing belt 21 and the nip portion forming member 26 due to sliding contact with the nip portion forming member 26 (sliding contact member) is sufficiently reduced.

In this embodiment, the present invention is applied to the fixing belt 21 as a belt member, but the belt member to which the present invention is applied is not limited to this. , for example, the intermediate transfer belt 78 as well.
Further, in this embodiment, the fixing belt 21 is configured to be in sliding contact with the nip portion forming member 26 and the flange 29, respectively. The fixing belt 21 may be configured to slide only on the forming member 26, or may be configured to slide on other members.
Further, in the present embodiment, the sliding contact member is configured to be in sliding contact with the inner peripheral surface 21a of the fixing belt 21, but the sliding contact member is configured to be in sliding contact with the outer peripheral surface (or both surfaces) of the fixing belt. can also In that case, the Martens hardness and pencil hardness of the outer peripheral surface (or both surfaces) of the fixing belt are optimized.
In the present embodiment, the base layer 21Aa of the fixing belt 21 is provided with the surface layer 21Aa with optimized Martens hardness and pencil hardness. Hardness and pencil hardness may be optimized.
Also in these cases, the same effects as those of the present embodiment can be obtained.

It should be noted that the present invention is not limited to the present embodiment, and it is obvious that the present embodiment can be appropriately modified within the scope of the technical idea of the present invention other than suggested in the present embodiment. be. Moreover, the number, position, shape, etc. of the constituent members are not limited to those of the present embodiment, and the number, position, shape, etc. can be set to be suitable for carrying out the present invention.

1 image forming apparatus (image forming apparatus main body),
20 fixing device,
21 fixing belt (belt member),
21A base layer,
21Aa surface layer,
21a sliding contact surface,
25 heater (heating means),
26 nip portion forming member (sliding contact member),
26a facing surface,
31 pressure roller (pressure member);

Japanese Patent No. 2002-134264

Claims (7)

A belt member characterized by having a Martens hardness H1 [N/mm ² ] of 20≦H1≦70 and a pencil hardness H2 of HB or more and 2H or less at a sliding contact surface that is in sliding contact with a sliding contact member. 2. The belt member according to claim 1, wherein the permanent strain when measuring the Martens hardness of said sliding contact surface is 50% or more and 80% or less with respect to the indentation depth. 3. The belt member according to claim 1, wherein the thickness of the surface layer having the sliding contact surface is 10 [mu]m or more. 4. The belt member according to claim 1, wherein the sliding contact surface has an emissivity of 0.94 or more. A fixing belt installed in a fixing device,
5. The belt member according to claim 1, wherein the sliding contact surface is an inner circumferential surface of the fixing belt. the fixing belt;
the sliding contact member;
a pressure member forming a nip portion where the sheet is conveyed by pressing against the sliding contact member via the fixing belt;
A fixing device comprising: An image forming apparatus comprising the belt member according to any one of claims 1 to 5 or the fixing device according to claim 6.

Images