JP2022042704A - Fixing device and image forming apparatus - Google Patents

Abstract

To provide a fixing device and an image forming apparatus that can reliably prevent meandering of a fixing belt without causing damage to the fixing belt.SOLUTION: In a heating roller 32 on which a fixing belt 33 is laid, an end regulation member 323 and a ring spring 324 are attached to a roller main body 322 at each of its ends. The end regulation member 323 is attached to an outer peripheral surface of the roller main body 322 and regulates the fixing belt 33 from moving along an axial direction of the heating roller 32. The ring spring 324 is attached to an outer peripheral surface of the end regulation member 323 and urges the end regulation member 323 toward the roller main body 322 to bring an inner peripheral surface of the end regulation member 323 into intimate contact with the outer peripheral surface of the roller main body 322 without a gap.SELECTED DRAWING: Figure 4

Description

The present invention relates to a fixing device and an image forming device using a fixing belt.

Some fixing devices used in electrophotographic image forming devices use a fixing belt. The fixing belt is stretched between the heating roller and the drive roller, and it is necessary to regulate the movement in the roller axial direction in order to prevent meandering between the rollers. Patent Document 1 discloses a belt driving device in which a meandering prevention member is attached to an end portion of a heating roller.

Japanese Unexamined Patent Publication No. 8-119484

The meandering prevention member in Patent Document 1 has a C shape having a cut in the outer peripheral direction of the roller and has a spring property. Further, the meandering prevention member directly attached to the heating roller needs to have heat resistance, and is limited to a material having both springiness and heat resistance.

The meandering prevention member of Patent Document 1 has a problem that it is difficult to make an appropriate design due to the limitation of the material thereof. For example, the meandering prevention member of Patent Document 1 is made of stainless steel, and if the plate thickness is increased, an appropriate spring property cannot be given. On the other hand, if the plate thickness of the meandering prevention member is thin, the belt end portion of the fixing belt may ride on the meandering prevention member, and the meandering of the fixing belt may not be prevented.

Further, if the meandering prevention member does not have a spring property, the meandering prevention member needs to be gap-fitted to the roller body of the heating roller in order to avoid an excessive load due to thermal expansion of the heating roller. In this case, a gap is generated between the inner peripheral surface of the meandering prevention member and the outer peripheral surface of the roller body, and the end portion of the fixing belt may be caught in this gap and damaged.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a fixing device and an image forming device capable of surely preventing meandering of the fixing belt without causing damage to the fixing belt. do.

In order to solve the above problems, the fixing device according to the first aspect of the present invention is a fixing device including a heating roller and a fixing belt stretched on the heating roller, and the heating roller is a fixing device. An end restricting member attached to the outer peripheral surface of the roller body at the end of the roller body and restricting the movement of the fixing belt along the axial direction of the heating roller, and the end regulation. A ring spring that is attached to the outer peripheral surface of the member and urges the end regulating member toward the roller body so that the inner peripheral surface of the end regulating member is brought into close contact with the outer peripheral surface of the roller body without gaps. It is characterized by having and.

According to the above configuration, the inner peripheral surface of the fixing belt is set to the outer peripheral surface of the roller body by the urging force of the ring spring with respect to the end regulating member for preventing the meandering of the fixing belt (movement along the axial direction of the heating roller). Can be brought into close contact with each other without any gaps. Therefore, the end regulating member does not need an elastic force to maintain close contact with the roller body, and an appropriate design for surely preventing meandering of the fixing belt becomes easy. For example, the end regulating member can be designed so that the end surface on the side facing the fixing belt has a sufficient height from the outer peripheral surface of the roller body. As a result, it is possible to surely prevent the belt end portion of the fixing belt from riding on the end limiting member, and it is possible to surely prevent the fixing belt from meandering.

In addition, the end regulating member is urged by the ring spring to maintain the inner peripheral surface of the end regulating member in close contact with the outer peripheral surface of the roller body regardless of the degree of thermal expansion in the roller body. Will be done. As a result, it is possible to prevent a gap from being generated between the inner peripheral surface of the end regulating member and the outer peripheral surface of the roller body, and it is possible to prevent the end portion of the fixing belt from being caught and damaged in this gap.

Further, in the fixing device, the end regulating member is composed of two dividing members, and the split member has a substantially cylindrical end regulating member on a plane passing through the central axis of the roller body. It can be configured to have a divided shape as a divided surface.

According to the above configuration, even if thermal expansion occurs in the roller body, the amount of deformation due to thermal expansion is absorbed by the gap between the divided surfaces of the two divided members. This makes it possible to prevent an excessive load from being applied to the end regulation member.

Further, in the fixing device, the end regulating member may be configured to have a substantially cylindrical shape having a cut in a part in the circumferential direction of the end regulating member.

According to the above configuration, even if thermal expansion occurs in the roller body, the amount of deformation due to thermal expansion is absorbed by the gap of the cut provided in the end regulating member. This makes it possible to prevent an excessive load from being applied to the end regulation member.

Further, in the fixing device, the two split members have protrusions on one of the split surfaces facing each other, and the gap between the facing split surfaces is adjusted by the protrusions. It can be configured.

According to the above configuration, with respect to the arrangement of the two dividing members, it is possible to prevent one gap from becoming wider than the other gap due to the deviation in the circumferential direction, and the end portion of the fixing belt is caught in the widened gap. Can be prevented.

Further, in the fixing device, the two dividing members have an engaging convex portion on one of the divided surfaces facing each other and an engaging concave portion on the other, and the engaging convex portion and the engaging portion are engaged. By engaging the joint recesses with each other, the two dividing members can be positioned in the axial direction of the heating roller.

According to the above configuration, the engaging convex portions and the engaging concave portions facing each other are engaged with each other so that the positions of the two divided portions in the roller axial direction are aligned.

Further, in the fixing device, the end restricting member has a large diameter portion and a small diameter portion formed on the axially outer side of the heating roller with respect to the large diameter portion and having a smaller diameter than the large diameter portion. The ring spring and the bearing are attached to the small diameter portion, and the bearing may be arranged on the outer side in the roller axial direction with respect to the ring spring.

According to the above configuration, the ring spring is arranged so as to be sandwiched between the large diameter portion (side surface portion) of the end restricting member and the bearing, and the position in the roller axial direction is restricted. By restricting the position of the ring spring in the roller axial direction, the ring spring can apply an urging force to an appropriate portion of the end regulating member.

Further, in order to solve the above problems, the image forming apparatus according to the second aspect of the present invention is characterized by including the fixing apparatus described above.

The fixing device and the image forming device of the present invention are configured to bring the inner peripheral surface of the end regulating member into close contact with the outer peripheral surface of the roller body without a gap by the urging force of the ring spring, thereby designing the end regulating member. It has the effect of increasing the degree of freedom and reliably preventing the fixing belt from meandering. In addition, it has the effect of preventing the end of the fixing belt from being caught in the gap between the inner peripheral surface of the end regulating member and the outer peripheral surface of the roller body and being damaged.

It shows an embodiment of the present invention and is a schematic cross-sectional view of an image forming apparatus. It is sectional drawing which shows the schematic structure of the main part in a fixing device. It is an exploded perspective view at the end portion of the heating roller which concerns on Embodiment 1. FIG. It is sectional drawing at the end part of the heating roller which concerns on Embodiment 1. FIG. It is a perspective view of the state in which the end regulation member and the ring spring are attached to the end of the roller main body which concerns on Embodiment 1. FIG. It is a perspective view which shows the end part regulation member which concerns on Embodiment 2. FIG. It is the schematic which looked at the end regulation member which concerns on Embodiment 2 from the roller axial direction. It is the schematic which looked at the end regulation member which concerns on Embodiment 3 from the direction orthogonal to the roller axis. It is an exploded perspective view at the end portion of the heating roller which concerns on Embodiment 4. FIG.

[Embodiment 1]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus 10 to which the present invention is applied. The image forming apparatus 10 shown in FIG. 1 is a color image forming apparatus having a plurality of process units, but the present invention is not limited to this, and is a monochrome image forming apparatus having a single process unit. It can also be applied.

As shown in FIG. 1, the image forming apparatus 10 includes a main body portion 11, a document reading unit 12, a document transporting device 13, and a paper feeding device 14. The main body portion 11 has an image forming portion inside for printing an image on a recording paper. The document reading unit 12 is arranged above the main body unit 11 and reads the document when copying the document. In the automatic scanning mode, the document transporting device 13 sequentially transports the documents placed on the document set tray toward the document loading table of the document reading unit 12. The paper feeding device 14 stocks the recording paper and feeds the recording paper to the main body 11 at the time of image formation.

The image data handled by the image forming apparatus 10 is one corresponding to a color image using each color of black (K), cyan (C), magenta (M), and yellow (Y), or a single color (for example, black). It corresponds to the monochrome image that was there. For this reason, the image forming apparatus 10 has four process units 20 associated with black, cyan, magenta, and yellow. Each process unit 20 uses electrophotographic technology to form a toner image according to the image data.

Each toner image formed by each process unit 20 is sequentially transferred and superimposed on the intermediate transfer belt 21. As a result, a color toner image is formed on the intermediate transfer belt 21. The color toner image on the intermediate transfer belt 21 is transferred onto the recording paper, and the recording paper is heated and pressurized by the fixing device 30 to fix the color toner image on the recording paper.

Subsequently, a specific structure of the fixing device 30 will be described. FIG. 2 is a cross-sectional view showing a schematic configuration of a main part of the fixing device 30. As shown in FIG. 2, the fixing device 30 includes a fixing roller 31, a heating roller 32, a fixing belt 33, and a pressure roller 34. The fixing roller 31 is a drive roller that rotates by receiving a drive force from a drive source (not shown). The heating roller 32 has a heater 321 inside, and the fixing belt 33 is heated by the heater 321 during the fixing operation. The fixing belt 33 is stretched at least on the fixing roller 31 and the heating roller 32, and is rotationally driven by the fixing roller 31. The pressure roller 34 is in pressure contact with the fixing roller 31 with the fixing belt 33 interposed therebetween, and forms a nip portion for passing the fixing paper between the pressure roller 34 and the fixing belt 33.

The fixing device 30 has a meandering prevention mechanism in the heating roller 32 in order to prevent the fixing belt 33 stretched on the fixing roller 31 and the heating roller 32 from meandering. This meandering prevention mechanism will be described with reference to FIGS. 3 to 5. In the following description, the meandering prevention mechanism at one end of the heating roller 32 will be described, but a similar meandering prevention mechanism is also provided at the other end. Further, in FIGS. 3 to 5, the heater 321 arranged inside the heating roller 32 is not shown.

FIG. 3 is an exploded perspective view of the end portion of the heating roller 32. FIG. 4 is a cross-sectional view at the end of the heating roller 32. As shown in FIGS. 3 and 4, at the end of the heating roller 32, an end restricting member 323, a ring spring 324, and a bearing 325 are attached to the roller main body 322.

The roller body 322 is a metal raw tube having high thermal conductivity. The end regulating member 323 is made of heat-resistant resin and is attached to the outer peripheral surface of the roller body 322. However, the end regulation member 323 according to the first embodiment is divided into two dividing members 3231 and 3232, in other words, a substantially cylindrical end portion is formed by combining these two dividing members 3231 and 3232. The regulatory member 323 is formed. Specifically, the dividing members 3231 and 3232 have a shape in which a substantially cylindrical end restricting member 323 is divided into a plane passing through the central axis of the roller main body 322 as a dividing surface 323a. However, when the two dividing members 3231 and 3232 are attached to the outer peripheral surface of the roller main body 322, a certain amount of gap is formed between the divided members 3231 and 3232 divided surfaces 323a facing each other.

The ring spring 324 is a C-ring-shaped urging member having a cut in the circumferential direction. The ring spring 324 is fitted to the outer peripheral side of the end restricting member 323, and urges each of the split members 3231 and 3232 toward the roller main body 322. As a result, the inner peripheral surface of the end regulating member 323 can be brought into close contact with the outer peripheral surface of the roller main body 322 without any gap.

The bearing 325 is a bearing member that is attached to the frame member 35 of the fixing device 30 and supports the end portion of the heating roller 32. The bearing 325 is fitted at a position different from that of the ring spring 324 in the roller axial direction on the outer peripheral side of the end regulating member 323. In the example of FIGS. 3 and 4, the bearing 325 is fitted to the end restricting member 323 on the outer side of the ring spring 324 along the roller axial direction. Further, the bearing 325 is fitted in a gap with respect to the end regulating member 323.

The meandering prevention mechanism in the first embodiment is configured by the end regulating member 323 and the ring spring 324, and can surely prevent the meandering of the fixing belt 33. FIG. 5 is a perspective view showing a state in which the end regulating member 323 and the ring spring 324 are attached to the end of the roller main body 322. The operation of the meandering prevention mechanism will be described below.

The end regulating member 323 is divided into two dividing members 3231 and 3232 to maintain a state of being in close contact with the outer peripheral surface of the roller main body 322 without applying an excessive load to the end regulating member 323. Will be possible. For example, if the end regulating member 323 is one undivided cylindrical member, the end regulating member 323 needs to be gap-fitted to the roller body 322. This is because when the end regulation member 323 is fitted to the roller body 322 without a gap, when the roller body 322 thermally expands due to heating during the fixing operation, an excessive load is applied to the end regulation member 323.

On the other hand, when one undivided end regulating member 323 is gap-fitted to the roller body 322, a gap is created between the inner peripheral surface of the end regulating member 323 and the outer peripheral surface of the roller body 322. If the end of the fixing belt 33 is caught in this gap, the fixing belt 33 will be damaged. Therefore, it is preferable that the end restricting member 323 is attached in close contact with the outer peripheral surface of the roller main body 322.

In the heating roller 32 according to the first embodiment, the end regulating member 323 is divided into two dividing members 3231 and 3232, and each of the divided members 3231 and 3232 is directed toward the roller body 322 by the elastic force of the ring spring 324. Is being urged. Since the end regulating member 323 is divided into the dividing members 3231 and 3232, even if the roller body 322 undergoes thermal expansion, the amount of deformation due to the thermal expansion is absorbed by the gap between the dividing surfaces 323a of the dividing members 3231 and 3232. To. As a result, an excessive load is not applied to the end regulating member 323.

Further, by urging the split members 3231 and 3232 by the ring spring 324, the inner peripheral surface of the end regulating member 323 is in close contact with the outer peripheral surface of the roller body 322 regardless of the degree of thermal expansion in the roller body 322. Can be maintained. As a result, it is possible to prevent a gap from being generated between the inner peripheral surface of the end regulating member 323 and the outer peripheral surface of the roller main body 322, and it is possible to prevent the end portion of the fixing belt 33 from being caught in this gap.

The end regulating member 323 that is directly attached to the roller body 322 needs heat resistance, but does not need an elastic force for bringing it into close contact with the roller body 322. Therefore, the end regulating member 323 can be easily designed appropriately for surely preventing the fixing belt 33 from meandering. Specifically, the end regulating member 323 can be designed so that the end surface 323b on the side facing the fixing belt 33 has a sufficient height from the outer peripheral surface of the roller main body 322. As a result, it is possible to reliably prevent the belt end portion of the fixing belt 33 from riding on the end limiting member 323, and it is possible to reliably prevent the fixing belt 33 from meandering.

In the heating roller 32 according to the first embodiment, the bearing 325 is fitted to the outer peripheral surface of the end regulating member 323. The bearing 325 not only attaches the heating roller 32 to the frame member 35, but also has a function of integrally holding the divided divided members 3231 and 3232.

Further, in the configuration in which the bearing 325 is attached to the outer peripheral surface of the end restricting member 323, the bearing 325 can also be used for the position regulation of the ring spring 324. That is, as shown in FIG. 4, the end restricting member 323 has a large diameter portion 323c having a large diameter and a small diameter portion 323d having a smaller diameter than the large diameter portion 323c, and the small diameter portion 323d is large. It is formed on the outer side in the roller axial direction with respect to the diameter portion 323c. Both the ring spring 324 and the bearing 325 are attached to the small diameter portion 323d of the end regulating member 323, and the bearing 325 is arranged outside the roller axial direction with respect to the ring spring 324. In this case, the ring spring 324 is arranged so as to be sandwiched between the large diameter portion 323c of the end restricting member 323 and the bearing 325, and the position in the roller axial direction is regulated by the large diameter portion 323c and the bearing 325. Will be done.

By restricting the position of the ring spring 324 in the roller axial direction in this way, the ring spring 324 can apply an urging force to an appropriate portion of the end restricting member 323, and a necessary portion in the end regulating member 323 can be applied. (That is, the end portion on the opposite side to the fixing belt 33), the inner peripheral surface of the end portion regulating member 323 can be reliably brought into close contact with the outer peripheral surface of the roller main body 322.

[Embodiment 2]
As described in the first embodiment, when the end restricting member 323 is divided into the dividing members 3231 and 3232, in the heating roller 32, the divided surfaces 323a in the dividing members 3231 and 3232 face each other and face each other. There is a certain amount of gap between the surfaces 323a. This gap occurs at two points in the circumferential direction.

At this time, if there is a bias in the circumferential direction with respect to the arrangement of the dividing members 3231 and 3232, one gap becomes wider than the other gap. In this case, since the end portion of the fixing belt 33 may be easily caught in the widened gap, it is preferable to eliminate the bias in the arrangement of the dividing members 3231 and 3232 and make both gaps of the same size.

In the end regulation member 323 according to the second embodiment, each of the division members 3231 and 3232 is provided with a protrusion 323e on a part of the division surface 323a as shown in FIG. The protrusion 323e is provided on either one of the dividing members 3231 and the dividing surface 323a facing each other. Note that FIG. 6 shows only the dividing member 3231, and the protrusion 323e is provided only on one dividing surface 323a. In this case, the protrusion 323e is provided on the split surface 323a of the split member 3232 facing the split surface 323a on which the protrusion 323e of the split member 3231 is not provided.

When the split members 3231 and 3232 provided with the protrusion 323e are attached to the roller main body 322, the width of the gap between the facing split surfaces 323a can be adjusted by the protrusion 323e, as shown in FIG. .. As a result, it is possible to prevent one of the gaps between the facing split surfaces 323a from becoming wider than the other, and prevent the end portion of the fixing belt 33 from being caught in the widened gap. In other words, if there is no protrusion 323e, one of the divided surfaces 323a may come into contact with each other and there may be no gap, and a wide gap may be generated between the other divided surfaces 323a. However, the protrusion 323e is provided on the divided surface a. This makes it possible to make the gap between one dividing surface 323a and the other dividing surface 323a uniform.

The formed portion of the protrusion 323e is outside the mounting position of the ring spring 324 in the roller axial direction. This is due to the following reasons. That is, at the portion where the protrusion 323e is formed, the inner peripheral surface of the end restricting member 323 cannot be reliably brought into close contact with the outer peripheral surface of the roller body 322. However, by setting the mounting position of the ring spring 324 (that is, the urging point by the ring spring 324) inside the protrusion 323e in the roller axial direction, at least at the end facing the fixing belt 33, the end restricting member 323 The inner peripheral surface of the roller body 322 can be reliably brought into close contact with the outer peripheral surface of the roller body 322.

Further, in order to more reliably prevent the end portion of the fixing belt 33 from being caught in the gap between the facing split surfaces 323a, the chamfered portion 323f (FIG. 6) may be formed.

[Embodiment 3]
When the end restricting member 323 is divided into the dividing members 3231 and 3232, the heating roller 32 needs to align the divided members 3231 and 3232 in the roller axial direction. In the example shown in FIG. 4, on the inner peripheral surface of the end regulating member 323, a convex rib 323 g is provided at the outer end portion in the roller axial direction, and the convex rib 323 g is brought into contact with the end surface of the roller main body 322 to be divided. The positions of the members 3231 and 3232 in the roller axial direction are aligned. However, in the configuration of FIG. 4, since the movement of the split members 3231 and 3232 in the roller axial direction can be restricted in only one direction, the alignment function is not sufficient.

In the end regulation member 323 according to the third embodiment, as shown in FIG. 8, an engaging convex portion 323h is provided on one of the dividing members 3231 and 3232, and an engaging concave portion 323i is provided on the other. As a result, in the heating roller 32, the engaging convex portions 323h and the engaging concave portions 323i facing each other are engaged with each other, and the positions of the dividing members 3231 and 3232 in the roller axial direction are aligned.

In the configuration shown in FIG. 8, if the height (circumferential length) of the engaging convex portion 323h is made larger than the depth (circumferential length) of the engaging concave portion 323i, the engaging convex portion 323h In addition, the function of the protrusion 323e in the third embodiment can be combined.

[Embodiment 4]
In the first to third embodiments, the configuration in which the end regulation member 323 is divided into two divided members 3231 and 3232 has been exemplified. However, the present invention is not limited to this, and the end regulating member may not necessarily be divided. FIG. 9 is an exploded perspective view of an end portion of the heating roller 32 according to the fourth embodiment. The heating roller 32 shown in FIG. 9 has a configuration in which the end regulating member 323'is used instead of the end regulating member 323 in the first to third embodiments.

The end regulating member 323'is not divided into two members, and has a shape having a cut 323j in a part of the substantially cylindrical end regulating member 323'in the circumferential direction. That is, the end regulating member 323'has a substantially C-shaped cross section when viewed from the roller axial direction. The end restricting member 323'is fitted into a gap with respect to the roller body 322 in a state where it does not receive the urging force of the ring spring 324, but the inner peripheral surface of the end regulating member 323' receives the urging force of the ring spring 324. Can be brought into close contact with the outer peripheral surface of the roller body 322 without a gap. Further, since the end restricting member 323'has a cut 323j, even if the roller body 322 undergoes thermal expansion, the amount of deformation due to the thermal expansion is absorbed by the gap of the cut 323j, and the end regulating member 323' Will not be overloaded.

The embodiments disclosed this time are exemplary in all respects and are not grounds for limited interpretation. Therefore, the technical scope of the present invention is not construed solely by the embodiments described above, but is defined based on the description of the scope of claims. It also includes all changes within the meaning and scope of the claims.

10 Image forming device 30 Fixing device 31 Fixing roller 32 Heating roller 321 Heater 322 Roller body 323, 323'End restricting member 323, 323 2 Dividing member 323a Dividing surface 323b End surface 323c Large diameter part 323d Small diameter part 323e Protrusion part 323f Chamfering part 323g Convex rib 323h Engagement convex part 323i Engagement concave part 323j Cut 324 Ring spring 325 Bearing 33 Fixing belt 34 Pressurizing roller 35 Frame member

Claims (7)

A fixing device including a heating roller and a fixing belt stretched on the heating roller.
The heating roller
With the roller body
An end restricting member attached to the outer peripheral surface of the roller body at the end of the roller body and restricting the fixing belt from moving along the axial direction of the heating roller.
By being attached to the outer peripheral surface of the end regulating member and urging the end regulating member toward the roller body, the inner peripheral surface of the end regulating member has a gap with respect to the outer peripheral surface of the roller body. A fixing device characterized by having a ring spring that makes it adhere to each other. The fixing device according to claim 1.
The end regulation member is composed of two split members.
The split member is a fixing device having a shape in which the end-regulating member having a substantially cylindrical shape is divided with a plane passing through the central axis of the roller body as a split surface. The fixing device according to claim 1.
The end regulating member is a fixing device having a substantially cylindrical shape having a cut in a part in the circumferential direction of the end regulating member. The fixing device according to claim 2.
The two dividing members have protrusions on either one of the divided surfaces facing each other.
A fixing device characterized in that the gap between the facing divided surfaces is adjusted by the protrusion. The fixing device according to claim 2 or 4.
The two dividing members have an engaging convex portion on one of the divided surfaces facing each other and an engaging concave portion on the other.
A fixing device characterized in that the two dividing members are positioned in the axial direction of the heating roller by engaging the engaging convex portion and the engaging concave portion with each other. The fixing device according to any one of claims 1 to 5.
The end regulating member has a large diameter portion and a small diameter portion formed on the axially outer side of the heating roller with respect to the large diameter portion and having a smaller diameter than the large diameter portion.
A fixing device characterized in that a ring spring and a bearing are attached to the small diameter portion, and the bearing is arranged outside in the roller axial direction with respect to the ring spring. An image forming apparatus comprising the fixing apparatus according to any one of claims 1 to 6.

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