JP2011197019A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device, along with an image forming apparatus, capable of facilitating work of replacing a nip forming member.SOLUTION: A fixing belt 21 is mounted on a reinforcing member, a flange 35 is attached to both ends in the axial direction of the reinforcing member, a nip forming unit 30 is inserted in the axial direction between the reinforcing member exposed on the side of the flange 35 and the fixing belt 21, and an endless belt unit 21u is achieved. By attaching and detaching the flange 35 in the endless belt unit 21u to/from the frame of the fixing device, the entire endless belt unit 21u is appropriately attached and detached to/from the frame, and the nip forming unit 30 is detachable from the side of the flange 35 from the endless belt unit 21u detached from the frame of the fixing device.

Description

  The present invention relates to a fixing device that fixes a formed image on a recording medium at a nip between an endless belt-shaped fixing member and a pressure rotating member, and an image forming apparatus including the fixing device.

  Conventionally, various image forming apparatuses using an electrophotographic system have been devised as image forming apparatuses such as copying machines and printers, 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. This process is established by a process in which the transferred image is transferred onto a recording paper by a transfer device to carry the image, and the toner image on the recording paper is fixed by a fixing device using pressure or heat.

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

  As an example of the fixing device, a technique using a fixing belt stretched around a plurality of roller members as a fixing member is known (for example, see Patent Document 1). An apparatus using such a fixing belt includes a fixing belt (endless belt) 204 as a fixing member, a plurality of roller members that stretch and support the fixing belt 204, and one roller among the plurality of roller members 202 and 203. It comprises a heater 201 provided inside the member 202, a pressure roller (pressure member) 205, etc. (FIG. 21). The heater heats the fixing belt via the roller member. Then, the toner image on the recording medium conveyed toward the nip formed between the fixing belt and the pressure roller is fixed on the recording medium by receiving heat and pressure at the nip. Belt fixing method).

Further, in the fixing device used in the image forming apparatus described above, there is a fixing device having a fixing member that is in sliding contact with the inner surface of a fixing member that is a rotating body.
For example, in Patent Document 2, a fixing nip portion N is formed by sandwiching a heat resistant film (fixing film) 213 between a ceramic heater 211 as a heating element and a pressure roller 212 as a pressure member. A recording material on which an unfixed toner image to be image-fixed is formed and supported is introduced between the film 213 and the pressure roller 212 in the fixing nip portion N, and is nipped and conveyed together with the film 213, whereby the nip portion In N, the heat of the ceramic heater 211 is applied to the recording material through the film 213, and the fixing device of the film heating system that fixes the unfixed toner image on the surface of the recording material by the pressing force of the fixing nip N. Is disclosed (FIG. 22). This film heating type fixing device can be configured as an on-demand type device using a ceramic heater and a member having a low heat capacity as a film, and energizes the ceramic heater as a heat source only when the image forming apparatus performs image formation. Thus, it is only necessary to generate heat at a predetermined fixing temperature, the waiting time from the power-on of the image forming apparatus to the image forming executable state is short (quick start property), and the power consumption during standby is greatly reduced ( There are advantages such as (power saving).

  In Patent Documents 3 and 4, a rotatable heat-fixing roll whose surface is elastically deformed, an endless belt (pressure belt) that can run while being in contact with the heat-fixing roll, and a non-rotation inside the endless belt The endless belt is placed in pressure contact with the heat fixing roll, a belt nip is provided between the endless belt and the heat fixing roll to allow recording paper to pass, and the surface of the heat fixing roll is elastic. A pressure belt type image fixing device having a pressure pad to be deformed has been proposed. According to this fixing method, the lower pressure member is used as a belt, and the contact area between the paper and the roll is widened to greatly improve the heat conduction efficiency, and it is possible to reduce the energy consumption and at the same time realize the miniaturization. It has become.

  However, although the fixing device described in Patent Document 1 described above is suitable for speeding up the device as compared with a device using a fixing roller, it is a warm-up time (a time required to reach a printable temperature). In addition, there is a limit to shortening the first print time (the time from when a print request is received until the print operation is performed and the paper discharge is completed).

On the other hand, the fixing device described in Patent Document 2 can reduce the warm-up time and the first print time by reducing the heat capacity, and also reduce the size of the device. However, the fixing device described in Patent Document 2 has a problem of durability and a problem of belt temperature stability. In other words, the wear resistance due to the sliding between the ceramic heater, which is a heat source, and the inner surface of the belt is insufficient. Or, a phenomenon such as an increase in the driving torque of the fixing device occurs, and as a result, the transfer paper forming the image slips and the image shifts, or the stress on the driving gear increases, causing damage to the gear. (Problem 1).
In the film heating type fixing device, since the belt is locally heated at the nip portion, when the rotating belt returns to the nip entrance, the belt temperature becomes the coldest state (especially at high speed rotation). , There was a problem that fixing failure was likely to occur (Problem 2).

  On the other hand, in Patent Document 3, a glass fiber sheet (PTFE-impregnated glass cloth) impregnated with PTFE as a low friction sheet (sheet-like sliding material) on the surface layer of the pressure pad is used, and the slidability of the belt inner surface and the fixing member is improved. Means for improving the problem are disclosed. However, such a pressure belt type fixing device (Patent Documents 3 and 4) 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).

  With respect to the above problems 1 to 3, in Patent Document 5, a substantially pipe-shaped counter member (metal heat conductor) disposed on the inner peripheral side of the endless fixing belt, and the inner periphery of the counter member By providing a resistance heating element such as a ceramic heater that is placed on the side to heat the opposing member, the entire fixing belt can be warmed, the warm-up time and first print time can be shortened, and high-speed rotation A fixing device that can solve the shortage of heat at the time has been proposed.

  However, in the fixing device described in Patent Document 5, the nip portion formed by pressing a pressure roller as a pressure member on the fixing belt side is supported by a metal thermal conductor, so the nip width in the nip portion, The pressure was unstable.

  Therefore, in Patent Document 6, in order to maintain and stabilize the state, shape, position, and the like of the nip portion N and the pipe-shaped metal body 224 formed by the fixing belt 221 and the pressure roller 222, a portion where the nip portion N is formed. A configuration is proposed in which a nip forming member (contact member) 223, a reinforcing member 226, and the like are provided corresponding to (FIG. 23).

  However, in the fixing device described in Patent Document 6, since the nip forming member (contact member) 223 slides and wears against the rotating fixing belt 221, the nip forming member (contact member) 223 is replaced. It is necessary to fix the nip forming member (contact member) 223 at both ends in the width direction to the side plate of the fixing device by screws, snap fits, etc., but the specific configuration is not presented It was. In addition, the relationship between the fixing belt and its internal constituent members attached to and detached from the side plate of the fixing device has not been considered.

  SUMMARY An advantage of some aspects of the invention is that it provides a fixing device and an image forming apparatus capable of easily replacing a nip forming member.

The present invention provided to solve the above problems is as follows.
[1] A flexible and rotating endless belt (fixing belt 21, pressure belt 310), and a facing member (pressure roller 31) disposed on the outer peripheral side of the endless belt so as to be able to contact the endless belt. , A fixing roller 210), a nip forming member (nip forming unit 30) that is disposed on the inner peripheral side of the endless belt and forms a nip portion by contacting the opposing member via the endless belt, and the fixing device A reinforcing member (reinforcing member 23) that is fixed to the frame (frame 20f) and supports the nip forming member, and a flange that can be attached to and detached from the frame of the fixing device while holding both ends in the axial direction of the reinforcing member. A member (flange 35), the endless belt is attached to the reinforcing member, the flange member is attached to both ends of the reinforcing member in the axial direction, and the nip forming member is attached to the flange. An endless belt unit (endless belt units 21u, 310u) is inserted between the reinforcing member exposed on the side surface of the belt member and the endless belt in the axial direction, and the flange member in the endless belt unit is used as the fixing device. When attached to the frame, the reinforcing member is fixed to the frame of the fixing device, and the endless belt and the nip forming member are arranged so as to form the nip portion, and the flange member in the endless belt unit is fixed to the fixing device. When removed from the frame of the apparatus, the entire endless belt unit is detached from the frame of the fixing apparatus, and the nip forming member can be removed from the side surface of the flange member (fixing apparatus 20, FIG. 2, FIGS. 12 to 14, and 20).
[2] The nip forming member in the endless belt unit has a protrusion (small protrusion 40) supported on the reinforcing member in contact with a surface corresponding to the circumferential direction of the endless belt. 3. The fixing device described in (3).
[3] When the endless belt unit is mounted on the frame of the fixing device, both end portions in the axial direction of the nip forming member (both end portions of the fixing member 26) are in contact with the main surface of the frame of the fixing device. The fixing device according to [1] or [2], wherein the forming member is positioned in the axial direction.
[4] The fixing device according to any one of [1] to [3], wherein the nip forming member has a sliding member (lubricating sheet material 27) detachably.
[5] The [1] to [4], wherein the endless belt unit includes a rotation support member (holding member 22) that supports rotation of the endless belt inside the endless belt. The fixing device described.
[6] The fixing device according to [5], wherein the rotation support member has a pipe shape.
[7] The fixing device according to [5] or [6], wherein the rotation support member is a metal heat conductor.
[8] Any of the above [1] to [7], comprising a heat source (halogen heater 24, induction heating mechanism, resistance heating element, planar heating element) for directly or indirectly heating the endless belt. A fixing device according to claim 1.
[9] An image forming apparatus (image forming apparatus 1, FIG. 1), comprising the fixing device (fixing apparatus 20) according to any one of [1] to [8].

According to the fixing device of the present invention, when the flange member in the endless belt unit is removed from the frame of the fixing device, the entire endless belt unit is detached from the frame of the fixing device, and a nip is formed from the side surface of the flange member. The member can be removed, and the entire nip forming member or one member that wears with the operation of the fixing device can be easily replaced.
Further, according to the image forming apparatus including the fixing device according to the present invention, the nip forming member in the fixing device is appropriately replaced and the nip portion is appropriately maintained. Quality image formation is performed over a long period of time.

1 is a schematic configuration diagram of an entire image forming apparatus for explaining an embodiment of the present invention. FIG. 3 is a front cross-sectional view illustrating a main part in the embodiment of the fixing device according to the present invention. FIG. 2 is an enlarged cross-sectional view of an internal configuration of a fixing belt in the present embodiment. It is sectional drawing of the reinforcement member of this embodiment. It is a perspective view which shows the end surface part of the reinforcement member of this embodiment. It is a side view which shows the end surface part of the reinforcement member of this embodiment. It is a figure which shows a connection state with the flange which supports the edge part of the reinforcement member of this embodiment. It is a perspective view which shows the connection state of FIG. It is a perspective view which shows the connection state of FIG. 7 from the back side. It is a perspective view which shows the edge part of the nip formation unit of this embodiment. It is a disassembled perspective view which fractures | ruptures and shows the structural member of the nip formation unit of this embodiment partially. It is a perspective view which shows the structure of the longitudinal direction edge part of an endless belt unit. FIG. 4 is a perspective view showing a state in which an endless belt unit is attached to a fixing device frame. FIG. 4 is a side view showing a state where an endless belt unit is attached to a fixing device frame. It is sectional drawing which shows the modification of the reinforcement member of this embodiment. It is sectional drawing which shows the other modification of the reinforcement member of this embodiment. It is sectional drawing which shows the other modification of the reinforcement member of this embodiment. It is sectional drawing which shows the other modification of the reinforcement member of this embodiment. It is explanatory drawing of the effect in the modification of the reinforcement member of FIG. FIG. 6 is a front cross-sectional view illustrating a configuration in another embodiment of a fixing device according to the present invention. It is a schematic block diagram which shows the fixing device of the conventional belt fixing system. It is a schematic block diagram which shows the conventional fixing device of a film heating system. It is a schematic block diagram which shows an example of the conventional fixing device.

Below, the structure in embodiment of this invention is demonstrated.
FIG. 1 is a schematic configuration diagram of an entire image forming apparatus for explaining an embodiment of the present invention. In this example, a tandem color printer is shown as the image forming apparatus.

  In FIG. 1, four toner bottles 102Y, 102M, 102C, and 102K corresponding to the respective colors (yellow, magenta, cyan, and black) are detachably attached to a bottle accommodating portion 101 installed above the image forming apparatus main body 1 ( It is installed freely.

  An intermediate transfer unit 85 is disposed below the bottle housing portion 101. Image forming portions 4Y, 4M, 4C, and 4K corresponding to the respective colors (yellow, magenta, cyan, and black) are arranged in parallel so as to face the intermediate transfer belt 78 installed in the intermediate transfer unit 85.

  Photosensitive drums 5Y, 5M, 5C, and 5K are disposed in the image forming units 4Y, 4M, 4C, and 4K, respectively. Further, around each of the photosensitive drums 5Y, 5M, 5C, and 5K, a charging unit 75, a developing unit 76, and a cleaning unit 77 (only those corresponding to the photosensitive drum 5K are shown in FIG. 1). Etc. are arranged. The photosensitive drums 5Y, 5M, 5C, and 5K rotate, and the following image forming processes (charging process, exposure process, developing process, transfer process) are performed on the photosensitive drums 5Y, 5M, 5C, and 5K. , A cleaning step) is performed, and an image of each color is formed on each of the photosensitive drums 5Y, 5M, 5C, and 5K.

  The image forming process for the photosensitive drums 5Y, 5M, 5C, and 5K will be described below.

  The photosensitive drums 5Y, 5M, 5C, and 5K are driven to rotate clockwise in FIG. 1 by a drive motor (not shown). In the charging unit 75, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K are uniformly charged (charging process).

  After being charged, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K are irradiated and exposed with laser light emitted from the exposure unit 3, and electrostatic latent images corresponding to the respective colors are formed (exposure process). On the photosensitive drums 5Y, 5M, 5C, and 5K on which the latent images are formed, the electrostatic latent images are developed with toner by the developing device 76, and toner images of respective colors are formed (developing step).

  The toner images on the photosensitive drums 5Y, 5M, 5C, and 5K are transferred onto the intermediate transfer belt 78 by the intermediate transfer belt 78 and the first transfer bias rollers 79Y, 79M, 79C, and 79K (primary transfer process). . In this way, the toner image is transferred onto the intermediate transfer belt 78 so that a color image is formed on the intermediate transfer belt 78.

  After the transfer, the photosensitive drums 5Y, 5M, 5C, and 5K reach the cleaning unit 77, and the untransferred toner remaining on the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K is removed by the cleaning blade of the cleaning unit 77. It is recovered mechanically (cleaning process). Thereafter, the residual potential on the surface of the photoconductive drums 5Y, 5M, 5C, and 5K is removed by the static eliminating unit.

  Thus, a series of image forming processes for the photosensitive drums 5Y, 5M, 5C, and 5K is completed.

  Next, a series of transfer processes performed on the intermediate transfer belt 78 will be described.

  The intermediate transfer unit 85 includes an endless 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, The intermediate transfer cleaning unit 80 is used.

  The intermediate transfer belt 78 is stretched and supported by the secondary transfer backup roller 82, the cleaning backup roller 83, and the tension roller 84, and is moved in the direction of the arrow in FIG.

  The primary transfer bias rollers 79Y, 79M, 79C, and 79K form primary transfer nips such that the intermediate transfer belt 78 is sandwiched between the photosensitive drums 5Y, 5M, 5C, and 5K. A transfer bias reverse to the polarity of the toner is applied to the primary transfer bias rollers 79Y, 79M, 79C, and 79K.

  The intermediate transfer belt 78 travels in the direction of the arrow, and sequentially passes through the primary transfer nip between the intermediate transfer belt 78 and the photosensitive drums 5Y, 5M, 5C, and 5K. 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 primary transfer is performed.

After the primary transfer, the intermediate transfer belt 78 reaches a position facing the secondary transfer roller 89. At this position, the secondary transfer backup roller 82 forms a secondary transfer nip so as to sandwich the intermediate transfer belt 78 with the secondary transfer roller 89. At the secondary transfer nip, the four color toner images formed on the intermediate transfer belt 78 are transferred onto the recording medium P being conveyed. After the transfer, the intermediate transfer belt 78 reaches the intermediate transfer cleaning unit 80, and the untransferred toner on the intermediate transfer belt 78 is collected.
Thus, a series of transfer processes performed on the intermediate transfer belt 78 is completed.

  Here, the recording medium P conveyed to the position of the secondary transfer nip is conveyed from the paper supply unit 12 disposed below the image forming apparatus main body 1 via the paper supply roller 97 and the registration roller 98. Is.

  That is, a plurality of recording media P such as transfer paper are stored in the paper supply unit 12 in a stacked manner. When the paper feed roller 97 is driven to rotate counterclockwise in FIG. 1, the paper is fed to the registration rollers 98 in order from the top recording medium P.

  The recording medium P conveyed to the registration roller 98 is temporarily stopped at the position of the roller nip of the registration roller 98 that has stopped rotating. Then, the registration roller 98 is rotationally driven in synchronization with the toner image on the intermediate transfer belt 78, whereby the recording medium P is conveyed toward the secondary transfer nip. In this way, the toner image is transferred onto the recording medium P.

  The recording medium P on which the color image has been transferred at the secondary transfer nip is conveyed to the fixing device 20. The recording medium P is heated and pressed by the fixing belt 21 and the pressure roller 31 in the fixing device 20, and the toner image transferred onto the surface is fixed on the recording medium P.

  Thereafter, the recording medium P is discharged out of the apparatus main body 1 through the paper discharge roller 99 and is sequentially stacked on the stack unit 100.

  FIG. 2 is a front sectional view showing a main part in the embodiment of the fixing device according to the present invention, and FIG. 3 is an enlarged sectional view of the internal configuration of the fixing belt in the present embodiment.

  As shown in FIG. 2, the fixing device 20 according to the present exemplary embodiment includes a fixing belt 21 that is an endless belt member, a contact with the inner peripheral wall of the fixing belt 21, and a cross-sectional shape of the fixing belt 21. A holding member 22 that functions as a heat conducting member that conducts heat to 21, a reinforcing member 23 that joins a part of the holding member 22 to reinforce the mechanical strength of the holding member 22, and an inner peripheral surface of the holding member 22 A halogen heater 24 that is a heat source for heating the toner, and a core member 31a as an opposing member that receives a pressing biasing force from a biasing member (not shown) and abuts against the fixing belt 21 to form a fixing nip portion N. And a pressure roller 31 made of a rubber layer 31b.

  The holding member 22 is made of a metal pipe material, and has a substantially circular cross-sectional shape as a whole, and has a concave shape that is recessed inward at the nip portion N.

  As shown in FIGS. 2 and 3, the concave portion 22a of the holding member 22 is made of an aluminum material in which a nip forming member 25 made of a fluorine-based rubber material and a plurality of inward projections 26a are arranged in parallel in the longitudinal direction. The fixing member 26, the lubricating sheet material 27 provided so as to wrap around the outer periphery of the nip forming member 25 and the fixing member 26 except for the inward protrusion 26 a, and the folding portion 27 a of the lubricating sheet material 27 are fixed by the fixing member 26. A nip forming unit 30 including a support plate 28 to be sandwiched, and a screw 29 for fixing the folding portion 27 a of the lubricating sheet material 27 and the support plate 28 to the fixing member 26 is installed.

  The concave portion 22a of the holding member 22 is fixed to the reinforcing concave portion 23a formed in the nip portion N portion of the reinforcing member 23 by a screw 33 while being sandwiched between the receiving member 32 having a concave cross section.

  In this state, the nip forming unit 30 is mounted on the concave portion 22a of the holding member 22, and the inward protrusion 26a and the receiving member 32 are in contact with each other in the pressing direction F from the pressure roller 31, and in the recording medium conveyance direction A. The small protrusion 40 that protrudes outward from the lubricating sheet material 27 from the side portion of the fixing member 26 comes into contact with the concave portion 22 a of the holding member 22.

  In the nip forming unit 30, the lubricating sheet material 27 (the nip forming member 25 when the lubricating sheet material 27 is omitted) slides with the inner peripheral surface of the fixing belt 21. At this time, the shape of the surface corresponding to the nip portion N of the nip forming member 25 is a concave shape, but may be a flat shape or other shapes. However, when the shape of the portion of the nip forming member 25 is concave, the discharge direction of the front end of the recording medium is closer to the pressure roller 31 at the exit of the nip portion N, so that the separability is improved and the occurrence of jamming is suppressed. Therefore, it is preferable.

  In the present embodiment, the fixing belt 21, the holding member 22, the reinforcing member 23, the halogen heater 24, the nip forming member 25, the fixing member 26, the lubricating sheet material 27, the support plate 28, and the pressure roller 31 are illustrated in the drawing. On the other hand, it extends in the vertical direction (axial direction, longitudinal direction) and contributes to forming the nip portion N. The end in the longitudinal direction is supported by an in-device chassis (frame) (not shown).

  The fixing belt 21 is a thin and flexible endless belt. The fixing belt 21 is pressed against the nip forming member 25 by a pressure roller 31 via a lubricating sheet material 27 and generates a predetermined pressure on the nip portion N. is doing. Further, the fixing belt 21 receives the rotational force of the pressure roller 31 that is rotationally driven by the drive unit, and rotates together with the pressure roller 31 counterclockwise in FIG. 2, and is guided by the outer periphery of the holding member 22. Slide and rotate in the circumferential direction.

  The nip forming unit 30 is in contact with the bottom of the reinforcing recess 23a of the reinforcing member 23 via the receiving member 32 and the holding member 22 (elastically contacted by receiving a pressing force in the direction F from the pressure roller 31), and the reinforcing member 23 is held by the in-device chassis as will be described later, the fixing belt 21 and each part of the nip forming unit 30 are securely fixed at this portion. Therefore, the state of the nip portion N is maintained / held appropriately and satisfactorily.

  4 is a cross-sectional view of the reinforcing member of the present embodiment, and FIG. 5 is a perspective view showing an end surface portion of the reinforcing member of the present embodiment.

  The reinforcing member 23 is made of a stainless steel plate material, and a reinforcing concave portion 23a that is an overlapped portion is formed by a hemming bending process in which the plate material is folded back approximately 180 degrees and bent. Then, as shown in FIG. 3, the reinforcing recess 23 a is first reinforced along the inner periphery of the first side surface 22 a-1 located upstream of the recording medium transport direction A in the recessed portion 22 a of the holding member 22. The second reinforcing portion 23a-2 is provided along the inner periphery of the second side surface 22a-2 located on the downstream side in the recording medium transport direction A in the concave portion 22a of the holding member 22. Is arranged.

  The reinforcing member 23 is hard to deform because the reinforcing recess 23a is work-hardened by hemming bending, and in the axial direction (longitudinal direction) of the reinforcing member 23, on the upstream side and the downstream side in the conveyance direction of the recording medium with respect to the nip portion N. Since the reinforcing member 23 is reinforced and the length of the reinforcing member 23 in the pressurizing direction is sufficiently secured, the bending and deformation of the reinforcing member 23 in the axial direction are suppressed.

  For this reason, it is possible to prevent displacement and deformation of the concave portion 22a of the holding member 22 and each portion constituting the nip forming unit 30, and the cross-sectional shape of the fixing belt 21 can be stably held by the holding member 22. For example, the nip portion N can be properly maintained in the entire nip forming region.

  In particular, when the holding member 22 is formed in a pipe shape as shown in the drawing so that the side ends are aligned by bending the plate material (see the concave portion 224a in FIG. 23), the side end matching portion is provided. By disposing in the reinforcing recess 23a, it is possible to prevent the side end portion from being opened by the spring back after assembly.

  The strength of the reinforcing member 23 greatly depends on the distance B (the length in the pressing force direction F) shown in FIG. However, lengthening the B portion of the reinforcing member 23 is accompanied by an increase in the amount of heat ray shielding of the halogen heater 24 that is a heat source.

  For this reason, in this embodiment, between the 1st reinforcement site | part 23a-1 and the 2nd reinforcement site | part 23a-2 of the reinforcement recessed part 23a, it is set as the shape by which the opposite side to the nip part N was open | released. A halogen heater 24 is installed. By adopting such a shape and arrangement configuration, it is possible to suppress the heat ray shielding amount of the halogen heater 24 while sufficiently taking the length of the nip forming unit 30 in the pressing force direction F.

  Further, in the reinforcing member 23 of the present embodiment, the first reinforcing portion 23a-1 and the second reinforcing portion 23a-2 are each extended inward, and the extended end portion is bent and extended in a substantially right angle direction. End portions 23a′-1 and 23a′-2 are formed. The extension end portions 23a'-1 and 23a'-2 increase the pressure-resistant length of the reinforcing member 23, thereby further improving the bending strength.

  6 is a side view showing an end face portion of the reinforcing member of the present embodiment, FIG. 7 is a view showing a connection state with a flange supporting the end portion of the reinforcing member of the present embodiment, and FIG. 8 is a connection state of FIG. FIG. 9 is a perspective view showing the connected state of FIG. 7 from the back side.

  The reinforcing member 23 is held by abutting and engaging with a plurality of engaging portions 35a, 35b of the inner diameter portion of the flange 35 fixed at both ends to an in-device chassis (not shown). In this example, as shown in FIGS. 5 and 6, the reinforcing member 23 is formed with notched portions 36 and 36 in the extended end portions 23 a′-1 and 23 a′-2 at both ends of the reinforcing member 23. Further, inclined portions 37 and 37 are formed so as to be inclined from the reinforcing portions 23a-1 and 23a-2 to the extended end portions 23a'-1 and 23a'-2.

  As shown in FIGS. 7 to 9, the notch portions 36 and 36 of the reinforcing member 23 and the end surfaces of the reinforcing portions 23 a-1 and 23 a-2 are engaged with the locking portions 35 a and 35 b of the flange 35, thereby reinforcing the reinforcement. The member 23 is held by the flange 35.

  In the present embodiment, the notch portions 36 and 36 are formed in the end surface portion of the reinforcing member 23, and the width of the extended end portions 23a'-1 and 23a'-2 of the reinforcing member 23 is reduced at this portion, thereby Accordingly, the insertion portion of the reinforcing member 23 into the flange 35 is reduced. Since the size of the flange 35 is formed in accordance with the diameters of the holding member 22 and the fixing belt 21, the diameter of the flange 35 can be increased by forming the notches 36 and 36 in the end surface portion of the reinforcing member 23. In addition, the reinforcing member 23 can be attached to the flange 35 without increasing the diameter of the holding member 22 and the fixing belt 21.

  On the contrary, it is conceivable that the extended end portions 23a′-1 and 23a′-2 of the reinforcing member 23 are all formed with the width of the notch 36 in the longitudinal direction. In this case, the reinforcing member 23 is bent. Strength decreases. Therefore, it is preferable to make the width of the portion mounted on the flange 35 wider than the end surface portion of the reinforcing member 23 mounted on the flange 35 in order to increase the bending strength.

  Further, the end face of the reinforcing member 23 is not cut into a rectangular shape as shown by a dotted line in FIG. The reduction in the area and volume of the member 23 can be minimized, thereby increasing the bending strength of the reinforcing member 23 (area S in FIG. 6).

  FIG. 10 is a perspective view showing an end portion of the nip forming unit of the present embodiment. As shown in FIG. 3, the nip forming unit 30 fixes the folding portion 27a of the lubricating sheet material 27 and the support plate 28 to the fixing member 26 with screws 29, and removes the screw 29 from the screwing position. An inward protrusion 26 a of the member 26 protrudes from the lubricating sheet material 27 and the support plate 28 to the outside. Further, on the side portion of the fixing member 26, small protrusions 40 that protrude from the lubricating sheet material 27 and come into contact with the concave portion 22 a of the holding member 22 are provided at a plurality of locations.

  A plurality of inward projections 26a of the fixing member 26 are provided in the longitudinal direction. In the present embodiment, the inward projection 26a at the center portion is longer than the inward projection 26a at the end in the longitudinal direction. I am doing so. Thereby, even if the reinforcing member 23 is slightly bent, it is possible to prevent the nip pressure at the central portion from being lowered and to suppress the occurrence of variations in the nip pressure in the longitudinal direction.

  Further, the inward projections 26a are juxtaposed at intervals, and the heads of the screws 29 and 33 (see FIG. 3) are arranged in the gap portion. This avoids contact between the head of the screw 29 and the head of the screw 33 shown in FIG. 3 and the inward projection 26a, and even if the screws 29 and 33 are installed, the nip forming unit 30 rattles, etc. Can be prevented from occurring.

  FIG. 11 is an exploded perspective view showing a part of the constituent members of the nip forming unit of the present embodiment, with the inward protrusions 26a on both sides in the longitudinal direction of the lubricating sheet material 27 made of a nonwoven fabric or the like in the unfolded state. A plurality of long holes 27a for projecting are arranged side by side, and the metal support plate 28 has a plurality of long holes 28a for projecting the inward projections 26a and a plurality of through holes 28b for inserting the screws 29. It is installed side by side. The lubricating sheet material 27 is folded on both sides so as to wrap around the outer periphery of the nip forming member 25 and the fixing member 26 so that the long holes 27a coincide.

  Here, in the fixing device 20, the portion where the nip portion N is formed is most inferior in durability. In particular, the lubricating sheet material 27 continues to receive a shearing force due to the pressure rotation during the operation of the device. It is quite possible that it will wear and tear. Therefore, the lubricating sheet material 27 (or the nip forming member 25) is the part that requires the most frequent replacement / maintenance. The present invention proposes a configuration in which the replacement and maintenance performance of the nip forming unit 30 is improved.

  That is, in the fixing belt 21, a holding member 22, a heat source (halogen heater 24), a nip forming unit 30, a support (a reinforcing member 23 for preventing deflection of the nip forming unit 30) and a plurality of components are arranged. However, as described above, the lubricating sheet material 27 (or the nip forming member 25) needs to be replaced and maintained most frequently. In the present invention, an endless belt unit including the fixing belt 21, the holding member 22, the reinforcing member 23, the receiving member 32, the nip forming unit 30, and the flange 35 so that the inside of the fixing belt 21 does not need to be disassembled every time replacement or maintenance is performed. The configuration is such that only the nip forming unit 30 from 21u is not fixed to the holding member 22 or the like so that it can be removed from the inside. Specifically, the nip forming unit 30 is fixed independently of the holding member 22 and the reinforcing member 23 to the flange 35 holding the holding member 22 and the reinforcing member 23 at both ends.

Hereinafter, the detail of the part which makes the foundation of this invention is demonstrated.
First, in the fixing device 20, the fixing belt 21 and its related members are assembled as follows.
(S11) First, the reinforcing member 23 is arranged on the inner peripheral side of the holding member 22, and the concave portion 22a of the holding member 22 is sandwiched between the reinforcing concave portion 23a of the reinforcing member 23 and the receiving member 32 with the screw 33. Secure and unite.
(S12) Next, the fixing belt 21 is attached to the outer periphery of the holding member 22 and the reinforcing member 23 which are integrated.
(S13) Next, flanges 35 are attached to both ends in the longitudinal direction (axial direction) of the holding member 22 and the reinforcing member 23 to which the fixing belt 21 is attached. At this time, when the flange 35 is viewed from the longitudinal direction of the fixing belt 21, a concave portion on the circumferential cross section of the holding member 22 and the reinforcing member 23 integrated from the side surface of the flange 35 (that is, the concave portion 22 a of the holding member 22 is formed It can be confirmed that the space surrounded by the reinforcing concave portion 23a of the reinforcing member 23 and the receiving member 32 and screwed) and the inner peripheral surface of the fixing belt 21 is exposed.
(S14) Next, the nip forming unit 30 is set so that the nip forming member 25 is on the fixing belt 21 side and the fixing member 26 is on the receiving member 32 side, and the holding member 22 exposed on the side surface of one of the flanges 35 is exposed. And between the concave part on the circumferential cross section of the reinforcing member 23 and the fixing belt 21, it is inserted in the longitudinal direction (axial direction) to form an endless belt unit 21u.

  FIG. 12 shows the configuration of the endless belt unit 21u. In this state, the nip forming unit 30 is supported so that the small protrusion 40 contacts the concave portion 22a of the holding member 22 and does not move in the circumferential direction of the fixing belt 21, but moves in the longitudinal direction (axial direction). Is in a free state.

(S15) Next, the flange 35 of the endless belt unit 21u is attached to the frame (also referred to as a chassis) of the fixing device 20.
This is shown in FIG. The frame 20f that is both side plates of the fixing device 20 is provided with notches corresponding to the flange surface shape of the flange 35, and flanges at both ends in the axial direction of the endless belt unit 21u are provided in the notches. Each of the flanges 35 is inserted so that only 35 is on the outside of the frame 20f, and each flange 35 is fixed to the frame 20f with screws in a state where the flange surface is in contact with the outer main surface of the frame 20f. As a result, the holding member 22 and the reinforcing member 23 are fixed to the frame 20 f via the flange 35, and the fixing belt 21 and the nip forming unit 30 can form the nip portion N with respect to the pressure roller 31. Will be placed.

Specifically, when the endless belt unit 21u is thus attached to the frame 20f of the fixing device 20, as shown in FIG. 14, the circumferential cross sections of the holding member 22 and the reinforcing member 23 that are exposed on the side surface of the flange 35. The space between the upper concave portion and the fixing belt 21 (that is, both ends in the longitudinal direction (axial direction) of the nip forming unit 30) is covered with the frame 20f. As a result, both end portions of the fixing member 26 which are both end portions in the longitudinal direction (axial direction) of the nip forming unit 30 come into contact (contact) with the main surface of the frame 20f, and the longitudinal direction (axial direction) of the nip forming unit 30 Positioning in the fixing device 20 is performed. Accordingly, an appropriate nip portion N can be formed by pressing the pressure roller 31.
Thereafter, the halogen heater 24 is attached to the endless belt unit 21u from the side surface of one flange 35.

  On the other hand, when the flange 35 in the endless belt unit 21u is removed from the frame 20f, the entire endless belt unit 21u is detached from the frame 20f of the fixing device 20, resulting in the state shown in FIG. Therefore, the nip forming unit 30 can be removed from the side surface of the flange 35, and the entire nip forming unit 30 or the lubricating sheet material 27 that is worn with the operation of the fixing device 20 can be easily replaced.

  The holding member 22 of the present embodiment uses a metal pipe material to guide the rotation of the fixing belt 21 (support the rotation of the belt) and to heat the fixing belt 21, but the holding member 22 If the fixing belt 21 does not need to be heated by the belt 22, a metal pipe material need not be used. Furthermore, if there is another member that appropriately guides the rotation of the fixing belt 21, the endless belt unit 21u. In this case, the holding member 22 can be omitted, and in this case, the function and effect of the present invention can be obtained. At this time, the nip forming unit 30 is held by the reinforcing recess 23 a of the reinforcing member 23.

  Next, since the fixing operation of the fixing device 20 configured as described above is the same as a known one, an outline thereof will be described.

  When the power switch of the image forming apparatus main body 1 in FIG. 1 is turned on, power is supplied to the halogen heater 24, and the pressure roller 31 starts to rotate in the direction of the arrow in FIG. When the pressure roller 31 rotates, the fixing belt 21 is driven (rotated) by the frictional force of the pressure roller 31 in the direction of the arrow in FIG.

  At this time, the fixing belt 21 is sandwiched and rotated by the nip portion N, but is rotated by being guided by the holding member 22 that is a pipe-like metal body except for the nip portion N. Therefore, the fixing belt 21 and the holding member 22 are set to have a diameter difference of 1 mm or less so that the fixing belt 21 and the holding member 22 are not separated beyond a certain distance.

  During this rotation operation, the recording medium P is fed from the paper supply unit 12, and a toner image is carried (transferred) onto the recording medium P by the secondary transfer roller 89. The recording medium P carrying the toner image is conveyed in the direction of arrow A in FIG. 2 while being guided by a guide plate (not shown), and sent to the nip portion N between the fixing belt 21 and the pressure roller 31 that are in a pressure contact state. Is done.

  In the nip portion N, the toner image T is fixed on the surface of the recording medium P by the heating by the fixing belt 21 heated via the holding member 22 and the pressure by the pressure roller 31, and the recording medium P is sent out from the nip portion N. And then conveyed to the paper discharge unit.

  According to the present embodiment, the structure is inexpensive and excellent in durability, and the metal pipe-shaped holding member 22 diffuses heat and gives uniform heat to the entire fixing belt 21, so that warm-up is quick. In addition, since the temperature of the entire fixing belt 21 is stabilized, it is possible to realize a fixing device that performs good fixing over a long period of time.

  Next, the structure and material of each component in the present embodiment will be described more specifically.

  In the fixing belt 21, an elastic layer and a release layer are sequentially laminated on a base material, and the overall thickness 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 resin.

  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 of the fixing belt 21 is reduced and the fixability is improved. However, when the unfixed image is crushed and fixed, minute irregularities on the surface of the belt are transferred to the image and become solid on the image. The defect that the mark of a yuzu skin remains remains. On the other hand, by providing the elastic layer, minute irregularities on the surface of the fixing belt 21 at the nip portion with the pressure roller 31 are not formed, and heat is uniformly transmitted to the toner image T on the recording medium P, so-called. The generation of the yuzu skin image is suppressed.

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

  Furthermore, the slidability with the holding member 22 can be improved by applying a fluorine-based resin to the surface of the base material that is the inner layer of the fixing belt 21.

  As an example of the fixing belt 21, in order from the innermost periphery, a Ni layer with a thickness of 30 μm as a base material, a silicone rubber layer with a thickness of 200 μm as an elastic layer, and a PFA resin layer with a thickness of 30 μm as a release layer In addition, a fluorine-based resin was applied to the inner peripheral surface of the substrate, and the inner diameter was 30 mm and the outer diameter was 30.52 mm.

  As shown in FIGS. 2 and 3, the nip portion N of the contact portion between the fixing belt 21 and the pressure roller 31 has a concave shape depending on the shape of the nip forming member 25. However, the nip portion N has a flat shape or other shapes. There may be. When the shape of the nip portion N is concave, the discharge direction of the front end of the paper, which is a recording medium, is closer to the pressure roller 31 and the separation of the paper after fixing is improved, so that jamming is suppressed. In the pressure roller 31, a rubber layer 31b is provided on the outer side of a hollow metal roller as a core material 31a, and a release layer (PFA resin layer or PTFE resin layer) is provided on the outermost surface in order to obtain releasability. Yes.

  Examples of the pressure roller 31 include an iron core material having a thickness of 1 mm and an outer diameter of 24 mm, a 3.1 mm thick silicone rubber layer provided on the surface of the core material, and a PFA having a thickness of 30 μm as a release layer. A resin tube covered with an outer diameter of 30.26 mm was used.

  The pressure roller 31 is rotated by a driving force transmitted from a driving source such as a motor provided in the image forming apparatus via a gear. The pressure roller 31 is pressed toward the fixing belt 21 by a spring or the like, and the rubber layer of the nip forming member 25 is crushed and deformed to form a predetermined nip width.

  The pressure roller 31 may be a solid roller, but a hollow roller may have a smaller heat capacity. Further, a heating source such as a halogen heater may be provided in the pressure roller 31.

  In the pressure roller 31, the silicone rubber layer may be a solid rubber, but when no heater is provided inside the pressure roller 31, sponge rubber may be used. Sponge rubber is more preferable because heat insulation is enhanced and heat of the fixing belt 21 is less likely to be taken away.

  The hollow pipe-shaped metal body constituting the holding member 22 is made of a metal material such as aluminum, iron, or stainless steel. The cross-sectional shape of the holding member 22 shown in the figure is circular, but may be other cross-sectional shape as long as it is square or pipe-shaped.

  As a heat source for raising the temperature of the holding member 22 which is a metal hollow heat conductor, the halogen heater 24 as in the present embodiment may be used, but an IH coil (electromagnetic induction heating mechanism) may be used, and resistance heating is performed. A body or a carbon heater can also be used. It is also conceivable that the fixing belt 21 itself generates heat. Alternatively, a configuration in which the sheet-like planar heating element is in contact with the inner peripheral surface of the fixing belt 21 may be employed.

  As an example of the holding member 22, a stainless steel pipe material having an inner diameter of 29.3 mm and a wall thickness of 0.1 mm and having an outer diameter of 29.5 mm was used. In this example, a black paint was applied to the inner surface in order to increase the heat absorption effect.

  The holding member 22 guides the fixing belt 21 that is sandwiched and rotated by the nip forming member 25 and the pressure roller 31 at the nip portion N at a portion other than the nip portion N, and is fixed to the fixing belt more than a certain distance from the holding member 22. 21 is kept away.

  In order to improve the slidability between the fixing belt 21 and the holding member 22, a lubricant such as silicone oil or fluorine grease is applied to the interface between the fixing belt 21 and the holding member 22.

  As a configuration of the halogen heater 24, one halogen heater may be used, but a halogen heater having a length corresponding to an A4 size sheet of paper as a recording medium and a length 2 corresponding to an A3 size sheet. A configuration in which a halogen heater of a book is installed is also conceivable.

  Further, as an example of the reinforcing member 23, ferritic stainless steel having a thickness of 1.5 mm is used, the inner width a of the open portion of the reinforcing recess 23a shown in FIG. 2 is 14 mm, and the reinforcing portions 23a-1, 23a- The length b from 2 to the extended end portions 23a′-1 and 23a′-2 was 15 mm.

  In this embodiment, the reinforcing member 23 is formed from one part formed by bending a metal material. For example, the reinforcing member 23 is formed from two parts, and the two parts are joined by screwing or welding. In this case, a temperature difference occurs between the parts, and thermal deformation occurs due to a difference in thermal expansion. In this case, since the component closer to the heat source is further thermally expanded, the reinforcing member is thermally bent inward, and the nip deviation is promoted.

  For this reason, if the reinforcing member 23 is formed from one component as in the present embodiment, the thermal deflection due to the difference in the thermal expansion amount does not occur, so that the nip deviation can be suppressed.

  In the present embodiment, the reinforcing member 23 is formed by folding the reinforcing recess 23a by hemming bending, but the shape and structure of the reinforcing portion are not particularly limited. For example, the overlapping state may be double or triple.

  Further, the bending angles of the extended end portions 23a′-1 and 23a′-2 in the reinforcing portions 23a-1 and 23a-2 of the reinforcing member 23 are set to angles other than 90 degrees, or the reinforcement shown in FIG. It is also conceivable that the extended end portions 23a′-1 and 23a′-2 are not formed like members.

  In the reinforcing member 23 shown in FIG. 16, the second reinforcing portion 23 a-2 located on the downstream side in the conveyance direction of the recording medium in the reinforcement portions 23 a-1 and 23 a-2 is located on the upstream side in the conveyance direction of the recording medium. It is set to extend longer than one reinforcing part 23a-1. By doing in this way, the amount of heat ray shielding of the halogen heater 24 by the 1st reinforcement part 23a-1 can be decreased by the part which shortened the 1st reinforcement part 23a-1.

  In addition, it is preferable to suppress the bending and deformation of each part on the downstream side (paper exit side) in the recording medium conveyance direction in the nip portion N from the upstream side in terms of fixing property and separation property (paper peeling). With the configuration shown in FIG. 5, the second reinforcing portion 23a-2 installed on the downstream side can be made longer than the first reinforcing portion 23a-1, and the strength of this portion can be increased. This is effective in terms of the reliability of the parts.

  Further, in the reinforcing member 23 shown in FIG. 17, the coating layer 41 is formed by performing surface deposition and coating on the surface with a material different from the base material (stainless steel in this example). In this case, it is preferable to apply aluminum or silver having a low emissivity as a coating material.

  In this embodiment, since the reinforcing member 23 is disposed inside the holding member 22, the heat from the halogen heater 24 is absorbed. However, by coating the surface of the reinforcing member 23 with a material having a low emissivity, Absorption can be suppressed. Since the heat that has not been absorbed by the reinforcing member 23 is absorbed by the holding member 22, the heat generation efficiency for the fixing belt 21 is increased.

  When the reinforcing member 23 is made of aluminum or silver, since the emissivity is high but the strength is low, the deflection becomes large and the nip shape is distorted. Therefore, it is possible to achieve both high strength and high heat generation efficiency by coating the surface of a high-strength material such as stainless steel with aluminum or silver having a low emissivity.

  Further, in the reinforcing member 23 shown in FIG. 18, a plurality of heat ray passage openings 42 are arranged in parallel in the longitudinal direction of the extended portions of the reinforcing portions 23 a-1 and 23 a-2. As described above, since the reinforcing member 23 also absorbs the heat of the halogen heater 24, it is possible to reduce the heat capacity of the reinforcing member 23 by reducing the heat capacity of the reinforcing member 23 by providing an opening 42 in order to increase heat utilization efficiency. it can.

  Further, by providing the opening 42, the heat capacity of the reinforcing member 23 is reduced and the heat rays of the halogen heater 24 are transmitted, so that the heat rays are efficiently absorbed by the holding member 22 as illustrated in FIG. 19. You can also.

  At that time, the shape of the openings 42 is all uniform, the openings 42 are arranged at equal intervals, and the region where the openings 42 are formed in the reinforcing member 23 is defined as the maximum sheet passing width in the nip portion N (the width direction of the sheet to be used). The maximum sheet passing area). As a result, the bias of the heat absorption rate of the holding member 22 in the sheet passing region can be suppressed, and the heat generation efficiency of the holding member 22 can be improved without promoting the temperature deviation.

  In the present embodiment, the present invention is applied to a fixing device using the pressure roller 31 as a counter member. However, the present invention is also applied to a fixing device using a pressure belt or a pressure pad as the counter member. Can be applied. In this case, the same effect as that of the present embodiment can be obtained.

FIG. 20 shows a configuration example of another embodiment of the fixing device according to the present invention.
That is, the fixing device of the present invention includes a pressure belt 310 that is flexible and rotates, and a fixing roller that is an opposing member disposed on the outer peripheral side of the pressure belt 310 so as to be able to contact the pressure belt 310. 210, the nip forming unit 30 disposed on the inner peripheral side of the pressure belt 310 and contacting the fixing roller 210 via the pressure belt 310 to form a nip portion, and fixed to the frame of the fixing device, A reinforcing member 23 that supports the nip forming unit 30 and a flange member that can be attached to and detached from the frame of the fixing device while holding both axial ends of the reinforcing member 23 are provided. Further, the fixing roller 210 has a halogen heater 24 inside.

  Also in the fixing device having such a configuration, the pressure belt 310 is attached to the reinforcing member 23, the flange members are attached to both ends of the reinforcing member 23 in the axial direction, and the nip forming unit 30 is exposed to the side surface of the flange member. The endless belt unit 310u is inserted between the reinforcing member 23 and the pressure belt 310 in the axial direction, and the flange member of the endless belt unit 310u is attached to the frame of the fixing device. The pressure belt 310 and the nip forming unit 30 are disposed so as to be fixed to the frame and the nip portion can be formed. When the flange member in the endless belt unit 310u is removed from the frame of the fixing device, the endless belt unit 310u is disposed. The whole is removed from the frame of the fixing device, and the flange Nip forming unit 30 is removable from the side surface of the wood.

  In this embodiment, the fixing belt 21 having a multilayer structure is used as the fixing member. However, an endless fixing film made of polyimide resin, polyamide resin, fluororesin, or thin plate metal may be used as the fixing member. it can. In this case, the same effect as that of the present embodiment can be obtained.

  Although the present invention has been described with the embodiments shown in the drawings, the present invention is not limited to the embodiments shown in the drawings, and other embodiments, additions, modifications, deletions, etc. Can be changed within the range that can be conceived, and any embodiment is included in the scope of the present invention as long as the effects and advantages of the present invention are exhibited.

  The present invention can be applied to a fixing device for fixing a toner image, and a fixing unit in an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multi-function machine including the fixing device.

1 Image forming apparatus body 20 Fixing apparatus 20f Frame (side plate)
21 fixing belt 21u, 310u endless belt unit 22 holding member 22a concave part of holding member 23 reinforcing member 23a reinforcing concave part of reinforcing member 23a-1 first reinforcing part 23a-2 second reinforcing part 23a'-1, 23a'-2 Extension end 24 Halogen heater 25 Nip forming member 26 Fixing member 26a Inward projection 27 Lubricating sheet material 27a Folding portion of lubricating sheet material 28 Support plate 29 Screw 30 Nip forming unit 31 Pressure roller (opposing member)
32 receiving member 33 screw 35 flange 35a, 35b locking part 36 notch part 37 inclined part 40 small protrusion 41 coating layer 42 opening N nip part P recording medium

Japanese Patent Laid-Open No. 11-2982 JP-A-4-44075 JP-A-8-262903 Japanese Patent Laid-Open No. 10-213984 JP 2007-334205 A JP 2009-3410 A

Claims (9)

A flexible and rotating endless belt;
An opposing member disposed on the outer peripheral side of the endless belt so as to be in contact with the endless belt;
A nip forming member that is disposed on the inner peripheral side of the endless belt and forms a nip portion by contacting the opposing member via the endless belt;
A reinforcing member fixed to the frame of the fixing device and supporting the nip forming member;
A flange member that can be attached to and detached from the frame of the fixing device while holding both axial ends of the reinforcing member,
The endless belt is attached to the reinforcing member, the flange members are attached to both ends of the reinforcing member in the axial direction, and the nip forming member is exposed on the side surface of the flange member between the reinforcing member and the endless belt. Insert it in the axial direction to make an endless belt unit,
When the flange member of the endless belt unit is attached to the frame of the fixing device, the reinforcing member is fixed to the frame of the fixing device, and the endless belt and the nip forming member are arranged so that the nip portion can be formed. ,
When the flange member in the endless belt unit is removed from the frame of the fixing device, the entire endless belt unit is removed from the frame of the fixing device, and the nip forming member can be removed from the side surface of the flange member. A fixing device characterized.   2. The fixing device according to claim 1, wherein the nip forming member in the endless belt unit includes a protrusion supported on the reinforcing member in contact with a surface corresponding to a circumferential direction of the endless belt.   When the endless belt unit is attached to the frame of the fixing device, both end portions in the axial direction of the nip forming member abut against the main surface of the frame of the fixing device, thereby positioning the nip forming member in the axial direction. The fixing device according to claim 1, wherein   The fixing device according to claim 1, wherein the nip forming member includes a sliding member that is detachable.   The fixing device according to claim 1, wherein the endless belt unit includes a rotation support member that supports rotation of the endless belt inside the endless belt.   The fixing device according to claim 5, wherein the rotation support member has a pipe shape.   The fixing device according to claim 5, wherein the rotation support member is a metal heat conductor.   The fixing device according to claim 1, further comprising a heat source that directly or indirectly heats the endless belt.   An image forming apparatus comprising the fixing device according to claim 1.

Images