JP2012108189A - Fixing device and image forming apparatus - Google Patents

Abstract

The cost of a fixing device is reduced by reducing the component cost.
A fixing belt 21 which is a flexible endless belt, a pressure roller 31 disposed on the outer peripheral side of the fixing belt 21 so as to be able to press the fixing belt 21, and an inner peripheral side of the fixing belt 21. And a nip forming member 23 that forms a nip portion by contacting the pressure roller 31 through the fixing belt 21 by pressing of the pressure roller 31 and is fixed in the vicinity of the inner peripheral side of the fixing belt 21. In the fixing device 20 having a pipe-shaped metal heat conductor 22 and a reinforcing member (stay, support member) 25 that is fixed to the inner peripheral surface side of the fixing belt 21 and reinforces the strength of the contact member. The member 25 includes a positioning member 26 as positioning means for the nip forming member 23 of the reinforcing member 25 and a load receiving member 27 as load receiving means for receiving a load from the pressure roller 31 side.
[Selection] Figure 2

Description

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

  Various image forming apparatuses using an electrophotographic system have been devised as image forming apparatuses such as copiers, printers, facsimiles, and their combined machines, and are well known in the art. In the image forming process, an electrostatic latent image is formed on the surface of the photosensitive drum as an image carrier, and the electrostatic latent image on the photosensitive drum is developed with a toner as a developer to be visualized and developed. The image is formed by a process in which the transferred image is transferred onto a recording paper (also referred to as paper, recording material, or recording medium) by a transfer device to carry the image, and a toner image on the recording paper is fixed by a fixing device using pressure, heat, or the like. Yes.

  In the fixing device, a fixing member and a pressure member constituted by opposing rollers or belts or a combination thereof are disposed so as to contact each other to form a nip portion. And a pressure is applied to fix the toner image on the recording paper.

  For example, a belt fixing type fixing device as shown in FIG. 7 includes a heating roller 74 having a heater 76 as a heat source, a fixing belt 79 including a fixing roller 72 having a rubber layer on the surface, and a fixing belt 79. The transferred toner image is heated and pressed and fixed in the process of passing the recording paper P onto which the toner has been transferred through a nip portion (fixing nip portion) formed by the pressure roller 71 in contact with the toner.

  Further, Patent Document 1 discloses a film heating type fixing device. For example, as shown in FIG. 8, such a film heating type fixing device has a heat resistant film (fixing film 84) between a ceramic heater 81 as a heating element and a pressure roller 71 as a pressure member. Is formed between the film 84 and the pressure roller 71 in the fixing nip portion, and the recording paper P to which toner has been transferred is interposed between the film 84 and the film 84 so as to be nipped and conveyed. The heat of the ceramic heater 81 is applied to the recording paper through the film 84 at the portion, and the unfixed toner image is fixed to the recording paper surface by heat and pressure with the applied pressure of the fixing nip portion.

  Such a film heating type fixing device can constitute an on-demand type device using a ceramic heater and a low heat capacity member as a film, and a ceramic heater as a heat source only when image forming of the image forming apparatus is executed. It is sufficient to energize the printer and heat it up to the specified fixing temperature. The waiting time from turning on the image forming apparatus to the image forming executable state is short (quick start), and the power consumption during standby is greatly increased. There are advantages such as small (power saving).

  Patent Document 2 discloses a pressure belt type fixing device. This fixing device is disposed with a rotatable heat-fixing roller whose surface is elastically deformed, an endless belt that can run while being in contact with the heat-fixing roller, and a non-rotating state inside the endless belt to heat-fix the endless belt A belt nip that allows the recording paper to pass between the endless belt and the heat fixing roller is provided between the endless belt and the heat fixing roller, and a pressure pad that elastically deforms the surface of the heat fixing roller is provided. By increasing the contact area between the recording paper and the roller, the heat conduction efficiency is greatly improved, energy consumption is reduced, and at the same time, miniaturization is realized.

  However, the fixing device described in Patent Document 1 has a problem of durability and a problem of belt temperature stability. In other words, the wear resistance due to the sliding of the ceramic heater that is the heat source and the inner surface of the belt is insufficient, and the surface that repeats continuous friction becomes rough and the frictional resistance increases when operated for a long time, and the running of the belt becomes unstable. There is a problem that a phenomenon such as an increase in driving torque of the fixing device occurs (issue 1).

  As a result, there has been a problem that the recording paper forming the image slips and the image shifts, or the stress applied to the drive gear increases and the gear is damaged.

  In the film heating type fixing device, since the belt is locally heated at the nip, when the rotating belt returns to the nip entrance, the belt temperature becomes the coldest, especially at high speed. However, there is a problem that fixing failure is likely to occur (Problem 2).

  On the other hand, as means for improving the problem of slidability between the belt inner surface and the fixing member, in the above-mentioned Patent Document 2, a glass fiber sheet obtained by impregnating PTFE as a low friction sheet (sheet-like sliding material) on the surface layer of the pressure pad A method using (PTFE-impregnated glass cloth) is disclosed, and it is shown that slidability is improved.

  However, such a pressure belt type fixing device has a problem that it takes a long time to warm up because the heat capacity of the fixing roller is large and the temperature rise is slow (Problem 3).

  As a technique for solving all of the above problems 1 to 3, in Patent Document 3, a pipe-shaped metal heat conductor is fixed inside an endless belt (fixing belt) so as to guide the movement of the endless belt. A fixing device including a pressure roller that heats an endless belt via a metal heat conductor by a heat source in the metal heat conductor and further contacts the metal heat conductor via the endless belt to form a nip portion is disclosed. ing. According to the invention of Patent Document 3, it is possible to warm the entire endless belt constituting the fixing device, to reduce the first print time from the heating standby time, and to solve the shortage of heat at the time of high-speed rotation. Can do.

  Further, Patent Document 4 discloses a fixing member (nip forming member) that slides on the inner surface side of the fixing belt and forms a nip portion with the pressure roller via the fixing belt, and a reinforcing member that supports and reinforces the fixing member. A fixing device including a (support member) is disclosed.

  However, in the conventional fixing device, the reinforcing member that supports the fixing member requires a reinforcing member having a different shape for each fixing device, and it has not been possible to share parts.

  Accordingly, the present invention enables a fixing member suitable for various fixing devices to be used in common, thereby reducing the cost of components and reducing the cost of the fixing device. An object is to provide an image forming apparatus provided.

  To achieve this object, the fixing device according to claim 1 is a fixing member that is an endless belt having flexibility, and a pressure member that is disposed on the outer peripheral side of the fixing member so as to be able to press the fixing member. A contact member that is disposed on the inner peripheral side of the fixing member and that forms a nip portion by contacting the pressure member through the fixing member by pressing of the pressure member, and is adjacent to the inner peripheral side of the fixing member. A fixing member having a pipe-shaped metal heat conductor fixed on the inner peripheral surface side of the fixing member and reinforcing the strength of the abutting member. The first reinforcing member as a positioning means for the abutting member of the member and a second reinforcing member as a load receiving means for receiving a load from the pressure member side.

  According to a second aspect of the present invention, in the fixing device according to the first aspect, the thickness of the second reinforcing member perpendicular to the load direction from the pressure member side is set according to the load from the pressure member side. The shape is changed.

  According to a third aspect of the present invention, in the fixing device according to the first or second aspect, the first reinforcing member has the same shape regardless of the shape of the second reinforcing member, and both ends in the axial direction. In FIG. 2, the flange member is fixed.

  According to a fourth aspect of the present invention, there is provided the fixing device according to the second aspect, further comprising a heating unit that is disposed on the inner peripheral side of the metal heat conductor and heats the metal heat conductor. The thickness of the member is adjusted by changing the surface of the second reinforcing member opposite to the side facing the heating means.

  An image forming apparatus according to a fifth aspect includes the fixing device according to any one of the first to fourth aspects.

  According to the present invention, the cost of parts can be reduced, and the cost of the fixing device can be reduced.

1 is a schematic configuration diagram of an image forming apparatus according to an exemplary embodiment. 1 is a schematic configuration diagram of a fixing device according to an exemplary embodiment. It is a schematic block diagram of (A) a reinforcing member, (B) a positioning member, and (C) a load receiving member. It is an example of the cross-sectional schematic diagram in the axial direction of (A) a positioning member, (B) a load receiving member, and (C) a reinforcing member. It is a cross-sectional schematic diagram in the axial direction (left side) and thickness direction (right side) of (A) a positioning member, (B) a load receiving member, and (C) a reinforcing member. It is another example of the cross-sectional schematic diagram in the axial direction of (A) a positioning member, (B) a load receiving member, and (C) a reinforcing member. 1 is a schematic configuration diagram of a belt fixing type fixing device. 1 is a schematic configuration diagram of a film heating type fixing device.

  Hereinafter, a configuration according to the present invention will be described in detail based on the embodiment shown in FIGS. The fixing device (20) according to the present embodiment includes a fixing member (fixing belt 21) that is a flexible endless belt, and a pressure member that is disposed on the outer peripheral side of the fixing member so as to be able to press the fixing member. (Pressure roller 31) and an abutting member (nip forming member 23) which is disposed on the inner peripheral side of the fixing member and forms a nip portion by contacting the pressing member via the fixing member by pressing of the pressing member. ), A pipe-shaped metal heat conductor (22) fixed near the inner peripheral side of the fixing member, and a reinforcement fixed on the inner peripheral surface side of the fixing member to reinforce the strength of the contact member In the fixing device having a member (stay, support member (25)), the reinforcing member is a first reinforcing member (positioning member 26) as a positioning means for the abutting member of the reinforcing member, and from the pressure member side. Second reinforcing member (load) as load receiving means for receiving the load of Only those consisting of member 27).

(Configuration and operation of image forming apparatus)
First, the configuration and operation of the entire image forming apparatus will be described with reference to FIG. In FIG. 1, reference numeral 1 denotes an apparatus main body of a copying machine as an image forming apparatus, 2 an original reading unit that optically reads image information of an original D, and 3 an exposure light L based on image information read by the original reading unit 2. Is exposed to the photosensitive drum 5, 4 is an image forming unit for forming a toner image (image) on the photosensitive drum 5, and 7 is a toner image formed on the photosensitive drum 5 on the recording medium P. A transfer unit 10 for transferring, a document transport unit for transporting the set document D to the document reading unit 2, 12 to 14 a paper feed unit storing a recording medium P such as transfer paper, and 20 on the recording medium P A fixing device for fixing an unfixed image, 21 is a fixing belt as a fixing member installed in the fixing device 20, and 31 is a pressure roller as a pressure member installed in the fixing device 20.

  An operation during normal image formation in the image forming apparatus shown in FIG. 1 will be described. First, the document D is conveyed from the document table in the direction of the arrow in the drawing by the conveyance roller of the document conveyance unit 10 and passes over the document reading unit 2. At this time, the document reading unit 2 optically reads the image information of the document D passing above.

  Then, the optical image information read by the document reading unit 2 is converted into an electric signal and then transmitted to the exposure unit 3 (writing unit). Then, exposure light L such as laser light based on the image information of the electrical signal is emitted from the exposure unit 3 toward the photosensitive drum 5 of the image forming unit 4.

  On the other hand, in the image forming unit 4, the photosensitive drum 5 is rotated in the clockwise direction in the drawing, and image information is transferred onto the photosensitive drum 5 through a predetermined image forming process (charging process, exposure process, development process). An image (toner image) corresponding to is formed. Thereafter, the image formed on the photosensitive drum 5 is transferred by the transfer unit 7 onto the recording medium P conveyed by the registration roller.

  On the other hand, the recording medium P conveyed to the transfer unit 7 operates as follows. First, one of the plurality of paper feeding units 12, 13, and 14 of the image forming apparatus main body 1 is automatically or manually selected (for example, the uppermost paper feeding unit 12 is selected). To do). Then, the uppermost sheet of the recording medium P stored in the paper feeding unit 12 is conveyed toward the position of the conveyance path K.

  Thereafter, the recording medium P passes through the conveyance path K and reaches the position of the registration roller. Then, the recording medium P that has reached the position of the registration roller is conveyed toward the transfer unit 7 at the same timing in order to align with the image formed on the photosensitive drum 5.

  After the transfer process, the recording medium P passes through the position of the transfer unit 7 and then reaches the fixing device 20 through the conveyance path. The recording medium P that has reached the fixing device 20 is fed between the fixing belt 21 and the pressure roller 31, and the image is fixed by heat received from the fixing belt 21 and pressure received from both members. The recording medium P on which the image has been fixed is delivered from between the fixing belt 21 and the pressure roller 31 (nip portion) and then discharged from the image forming apparatus main body 1. Thus, a series of image forming processes is completed.

(Configuration of fixing device)
Next, the configuration and operation of the fixing device 20 installed in the image forming apparatus main body 1 will be described in detail. As shown in FIG. 2, the fixing device 20 includes a fixing belt 21 as a fixing member, a metal heat conductor 22, a nip forming member 23, a heater 24, a reinforcing member 25, a pressure roller 31 as a pressure member, and a separation plate. 32 etc.

[Fixing belt]
The fixing belt 21 as a fixing member is a thin and flexible endless belt (or film), and rotates together with an external roller. In the example shown in FIG. 2, the pressure roller 31 is rotated by a driving source (not shown), and the driving force is transmitted to the belt at the nip portion, whereby the fixing belt 21 is rotated.

  The fixing belt 21 is formed by sequentially laminating an elastic layer and a release layer on a base material, and the entire thickness thereof is set to 1 mm or less. The base material of the fixing belt 21 has a layer thickness of 30 to 50 μm and is formed 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 formed of a rubber material such as silicone rubber, foamable silicone rubber, or fluororubber. When there is no elastic layer, the heat capacity is reduced and the fixability is improved, but when the unfixed image is crushed and fixed, minute irregularities on the belt surface are transferred to the image and the image has a crusty skin-like shape. There is a problem that marks remain. On the other hand, by providing the elastic layer, minute irregularities on the surface of the fixing belt 21 in the nip portion are not formed, and heat is uniformly transmitted to the toner image on the recording medium P, thereby preventing the generation of a scum skin image.

  The release layer of the fixing belt 21 has a layer thickness of 10 to 50 μm, such as PFA (tetrafluoroethylene bar fluoroalkyl vinyl ether copolymer resin), polyimide, polyetherimide, PES (polyether sulfide), and the like. Made of material. By providing the release layer, the releasability (peelability) for the toner image is secured.

  In the present embodiment, the diameter of the fixing belt 21 is set to 30 mm. Inside the fixing belt 21 (inner peripheral surface side), a metal heat conductor 22, a nip forming member 23, a heater 24, a reinforcing member 25, and the like are fixed.

[Nip forming member]
The nip forming member 23 is fixed to the inner peripheral surface side of the fixing belt 21 and abuts against the pressure roller 31 through the fixing belt 21 to form a nip portion. Note that it is preferable that the slidable contact surface of the nip forming part 23 is formed of a material having a low coefficient of friction so that the wear of the fixing belt 21 is reduced even if the nip forming member 23 and the fixing belt 21 are in sliding contact. Further, a sliding sheet may be provided between the nip forming member 23 and the inner peripheral surface of the fixing belt 21.

  In the example shown in FIG. 2, the shape of the nip portion is a flat shape, but may be a concave shape or other shapes. For example, by making the shape of the nip portion concave, the discharge direction of the leading end of the recording paper is closer to the pressure roller, improving the separation property and suppressing the occurrence of jam.

[heater]
The heater 24 as a heat source is a halogen heater, and both ends thereof are fixed to a side plate (not shown) of the fixing device 20. Then, the metal thermal conductor 22 is heated by the radiant heat of the heater 24 whose output is controlled by the power supply unit of the image forming apparatus 1. Further, the fixing belt 21 is entirely heated by the metal heat conductor 22, and heat is applied to the toner image on the recording medium P from the surface of the heated fixing belt 21.

  The output control of the heater 24 is controlled based on the detection result of the belt surface temperature by a temperature sensor (not shown) 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 such output control of the heater 24.

  In the example shown in FIG. 2, the halogen heater 24 is used as the heat source. However, the present invention is not limited to this, and an induction heating means (IH coil), a resistance heating element, a carbon heater, or the like may be used as the heat source. good.

[Metal heat conductor]
The hollow metal heat conductor 22 is fixed so as to face the inner peripheral surface of the fixing belt 21 at a position excluding the nip portion, and is heated by the radiant heat of the heater 24 to heat the fixing belt 21 (heat is generated). Tell). In addition, as a material of the metal thermal conductor 22, a material having thermal conductivity such as aluminum, iron, and stainless steel can be used. In this embodiment, SUS having excellent strength is used. In the example shown in FIG. 2, the metal heat conductor 22 has a shape in which the circular top portion is crushed, but is not limited thereto, and may be circular or rectangular. Other cross-sectional shapes may be used.

  Even if the speed of the apparatus is increased because the fixing belt 21 is heated over a wide range in the circumferential direction by the metal heat conductor 22 without locally heating only a part of the fixing belt 21. The fixing belt 21 is sufficiently heated to prevent the occurrence of fixing failure.

  Further, even when the metal heat conductor 22 is thinned to improve the heating efficiency of the fixing belt 21, the metal heat conductor 22 is separated from the nip forming member 23 that receives pressure from the pressure roller 31. Therefore, a problem that the metal heat conductor 22 is bent and the inner peripheral surface of the fixing belt 21 is rubbed strongly, a problem that the metal heat conductor 22 is bent and the driving torque of the fixing belt 21 is increased, and the like are suppressed. The

  As described above, the fixing device 20 is configured such that only the part of the fixing belt 21 is not locally heated and the fixing belt 21 is heated over a wide range in the circumferential direction by the metal heat conductor 22. Even when the speed is increased, the fixing belt 21 is sufficiently heated to prevent the occurrence of fixing failure. 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 are shortened, and the size of the apparatus is reduced.

  The difference in outer diameter between the fixing belt 21 and the metal heat conductor 22 is preferably within 1 mm. As a result, the area in which the metal heat conductor 22 and the fixing belt 21 are in sliding contact with each other is increased, and the problem that the wear of the fixing belt 21 is accelerated is suppressed, and the metal heat conductor 22 and the fixing belt 21 are separated from each other too much. A problem that the heating efficiency of the belt 21 is reduced can be suppressed. Furthermore, since the metal heat conductor 22 is placed close to the fixing belt 21, the circular posture of the flexible fixing belt 21 is maintained to some extent, so that deterioration and breakage due to deformation of the fixing belt 21 can be reduced. Can do.

  Further, the sliding surface of the metal heat conductor 22 may be formed of a material having a low friction coefficient so that the wear of the fixing belt 21 is reduced even if the metal heat conductor 22 and the fixing belt 21 are in sliding contact. good. Further, it is preferable to apply a lubricant such as silicone oil or fluorine grease to the interface between the fixing belt 21 and the metal heat conductor 22.

[Pressure roller]
The pressure roller 31 as a pressure member has a diameter of 30 mm and is formed by forming an elastic layer on a hollow cored bar. The elastic layer of the pressure roller 31 is made of a material such as foamable silicone rubber, silicone rubber, or fluororubber. A thin release layer made of PFA, PTFE, or the like can be provided on the surface layer of the elastic layer. The pressure roller 31 is pressed against the fixing belt 21 by a spring or the like, and the rubber layer is crushed and deformed to form a desired nip portion between both members.

  Note that when the elastic layer of the pressure roller 31 is formed of a sponge-like material such as foamable silicone rubber, the pressure applied to the nip portion can be reduced, so that the bending that occurs in the metal heat conductor 22 is reduced. Can be further reduced.

  In this embodiment, the fixing belt 21 has a diameter equal to that of the pressure roller 31, but the fixing belt 21 has a diameter smaller than the pressure roller 31. You can also. In that case, since the curvature of the fixing belt 21 in the nip portion is smaller than the curvature of the pressure roller 31, the recording medium P sent out from the nip portion is easily separated from the fixing belt 21.

  The pressure roller 31 is rotated by a driving force transmitted from a driving unit such as a motor through a gear. Further, the pressure roller 31 may be a solid roller, but the hollow roller may have a smaller heat capacity. Further, a heat source such as a halogen heater may also be provided on the pressure roller 31 side. If there is no heater inside the pressure roller, sponge rubber may be used. Sponge rubber is more desirable because it increases heat insulation and makes it difficult for the fixing belt to lose heat.

[Separator]
A separation plate 32 that separates the recording medium P fed from the nip portion from the fixing belt 21 is disposed on the exit side of the nip portion, which is a contact portion between the fixing belt 21 and the pressure roller 31.

[Reinforcing material]
A reinforcing member (also referred to as a support member or stay) 25 that supports the nip forming member 23 in the nip portion and reinforces the strength is fixed inside the metal thermal conductor 22, and flange members ( (Not shown) and fixed and positioned. Further, the nip forming member 23 is supported by contacting the nip forming member 23 through the opening of the metal heat conductor 22.

  The reinforcing member 25 prevents the nip forming member 23 from being in contact with the pressure roller 31 via the fixing belt 21 to deform (bend) due to the pressure applied by the pressure roller 31 at the nip portion. Thus, a uniform nip width can be obtained in the axial direction.

  In the following description, as shown in FIGS. 2 to 6, the length (stay length) in the axial direction of the reinforcing member 25 (the direction of the rotation axis of the pressure roller 31 and the fixing belt 21) is the Z direction. The horizontal width (stay width) of the reinforcing member 25 is defined as the X direction, and the thickness (stay thickness) of the reinforcing member 25 is defined as the Y direction.

The shape of the reinforcing member 25 is not particularly limited as long as the reinforcing member 25 can be disposed inside the metal heat conductor 22, but the bending equation (1) or (2) can be calculated (cantilever beam). As shown in (), what values the stay width and stay thickness are made is important in preventing deflection.
δ = PL ³ / 3EI (1)
^{I = bh 3/12 ··· (} 2)
However, (delta) (mm): Deflection, E (kg / m < ² >): Young's modulus, I (mm < ⁴ >): Sectional moment of inertia, P (kg): Load, L (mm): Stay length, b (mm ): Stay thickness, h (mm): stay width.

  The reinforcing member 25 is bent in the horizontal direction because the pressure from the pressure roller 31 facing the nip forming member 23 is applied. Therefore, by forming the reinforcing member 25 so as to have a horizontally long cross section along the pressing direction by the pressure roller 31, the section modulus is increased and the mechanical strength of the reinforcing member 25 can be increased. That is, it can be said that the reinforcing member 25 in the fixing device is most preferably configured to have a substantially maximum stay width near the center where the horizontal diameter inside the metal heat conductor 22 is maximum.

  Therefore, the strength of the reinforcing member 25 can be obtained by changing the thickness of the reinforcing member 25 according to the performance of the fixing device (particularly, the pressure from the pressure member side). However, in determining the shape of the reinforcing member 25, increasing the thickness of the reinforcing member 25 is contrary to the heat capacity reduction in the fixing device for shortening the warm-up time, the cost reduction due to the material reduction, and the unit weight reduction. Therefore, it is not desirable.

  On the other hand, regardless of the performance of the fixing device, it is desired in terms of mass productivity and cost reduction that the common reinforcing member 25 is used to share parts. However, until now, when the thickness of the reinforcing member is optimized, a reinforcing member having a different shape is required for each fixing device in accordance with the performance of the fixing device, and it has not been possible to share parts. Further, since the shape of the reinforcing member is different, it has been impossible to make the parts common to the flange member that receives the reinforcing member.

  Therefore, as shown in FIG. 3, the fixing device 20 according to the present embodiment positions the reinforcing member 25 (FIG. 3A) by fixing the reinforcing member 25 to the flange member that positions the reinforcing member 25. Positioning member (first reinforcing member, FIG. 3B) 26 and load receiving member 27 (second reinforcing member, FIG. 3C) that receives a load that varies depending on the performance of the fixing device 20. It is set as a separate member, and it is set as the structure used as the reinforcement member 25 combining this.

  The schematic diagram of the reinforcing member 25 shown in FIG. 3 is shown in FIG. 4 and FIG. 4A is a schematic cross-sectional view in the axial direction of a positioning member 26, FIG. 4B is a load receiving member 27, and FIG. 4C is a reinforcing member 25 that is a combination of the positioning member 26 and the load receiving member 27. Is shown. The reinforcing member 25 adjusts (sets) the thickness of the load receiving member 27 (indicated by “a” in FIG. 4B) to a thickness capable of obtaining a desired strength in accordance with the performance of the fixing device. 26 can be attached.

  5A is a positioning member 26, FIG. 5B is a load receiving member 27, and FIG. 5C is an axial direction (left side) of a reinforcing member 25 that is a combination of the positioning member 26 and the load receiving member 27. Figure) and a schematic cross-sectional view in the thickness direction (right side view) are shown. As shown in FIG. 5A, the positioning member 26 has a shape in which both ends 26a of the stay positioned by the flange member are connected by a portion (indicated by 26b) located on the side opposite to the nip. . As shown in FIGS. 4 and 5, the positioning member 26 has the same shape regardless of the thickness of the load receiving member 27.

  Here, the method of fixing the load receiving member 27 formed so as to have a desired thickness to the positioning member 26 is not particularly limited, and for example, it may be attached by screwing. It is also preferable that the positioning member 26 is provided with a guide rail for guiding the load receiving member 27 and is fixed by fitting.

  In this way, by configuring the positioning member 26 and the load receiving member 27 as separate members for the reinforcing member 25, the load receiving member 27 according to the performance of the fixing device 20, that is, according to the required strength. Only the shape (thickness) is appropriately changed, and the positioning member 26 can have a common shape regardless of the performance of the fixing device 20. For this reason, the reinforcing member 25 can be used in common in various fixing devices. In addition, the flange member for fixing the positioning member 26 can also have a common shape. Therefore, mass production and parts cost reduction can be achieved, and the cost of the fixing device 20 can be reduced.

  Moreover, it is preferable to adjust the thickness of the load receiving member 27 described above on the surface opposite to the side facing the heater 25. That is, as shown in FIGS. 6A to 6C, in adjusting the thickness of the load receiving member 27, the surface 27 a on the side where the heater 25 is provided is a reference surface common to the positioning member 26, and the reference It is preferable to adjust the thickness on the surface 27b side opposite to the surface.

  This is because if the thickness of the surface 27a on the heat source side of the load receiving member 27 is increased, the distance between the heater 24 and the reinforcing member 25 becomes closer, so that the heat transfer to the reinforcing member 25 increases and heating is performed. This is because the efficiency may decrease. In addition, when a heat insulating member or the like is provided on the surface of the reinforcing member 25 to perform a heat insulating process, the surface position of the reinforcing member 25 is changed, and there is a possibility that attachment to the same member cannot be performed. Therefore, by adjusting the thickness in the direction opposite to the heat source side, the above-described effect can be obtained without affecting the heating efficiency.

  In addition, in order to satisfy the function mentioned above, the reinforcing member 25 is preferably formed of a metal material having high mechanical strength such as stainless steel or iron. Further, when the reinforcing member 25 is heated by radiant heat of a heat source or the like, useless energy consumption can be suppressed by performing heat insulation or mirror treatment on the surface of the reinforcing member to prevent excessive heating.

  By using the image forming apparatus (FIG. 1) provided with the fixing device 20 having the above-described configuration, an image forming apparatus that functions as described above can be configured.

  The above-described embodiment is a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, in the above-described embodiment, the fixing device using the pressure roller 31 as the pressure member has been described as an example. However, the fixing device is not limited thereto. For example, a pressure belt or a pressure pad is used as the pressure member. It is also preferable.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Original reading part 3 Exposure part 4 Image forming part 5 Photosensitive drum 7 Transfer part 10 Original conveyance part 12, 13, 14 Paper feed part 20 Fixing apparatus 21 Fixing belt 22 Metal thermal conductor 23 Nip forming member 24 Heater 25 Reinforcement member 26 Positioning member (first reinforcement member)
27 Load receiving member (second reinforcing member)
31 Pressure roller 32 Separating plate 71 Pressure roller 72 Fixing roller 73 Separating claw 74 Heating roller 75 Fixing cover 76 Heater 77 Tension roller 78 Spring 79 Fixing belt 80 Thermistor 81 Ceramic heater 82 Stay 83 Holder 84 Fixing film D Document K L Exposure light P Recording medium

JP-A-4-44075 JP-A-8-262903 JP 2007-334205 A JP 2010-96782 A

Claims (5)

A fixing member which is an endless belt having flexibility;
A pressure member arranged to be able to press the fixing member on an outer peripheral side of the fixing member;
An abutting member that is disposed on the inner peripheral side of the fixing member and forms a nip portion by contacting the pressing member via the fixing member by the pressing of the pressing member;
A pipe-shaped metal heat conductor fixed in the vicinity of the inner peripheral side of the fixing member;
A fixing member that is fixed to an inner peripheral surface side of the fixing member and reinforces the strength of the contact member,
The reinforcing member includes a first reinforcing member as positioning means for the reinforcing member with respect to the contact member, and a second reinforcing member as load receiving means for receiving a load from the pressure member side. Fixing device.   The thickness of the said 2nd reinforcement member orthogonal to the load direction from the said pressurization member side is made into the shape changed according to the load from the said pressurization member side, It is characterized by the above-mentioned. Fixing device.   3. The first reinforcing member according to claim 1, wherein the first reinforcing member has the same shape regardless of the shape of the second reinforcing member, and is fixed to the flange member at both ends in the axial direction. Fixing device. A heating means disposed on the inner peripheral side of the metal heat conductor to heat the metal heat conductor;
The fixing device according to claim 2, wherein the thickness of the second reinforcing member is adjusted by changing a surface of the second reinforcing member opposite to the side facing the heating unit.   An image forming apparatus comprising the fixing device according to claim 1.