JP2001022215A - Belt unit for fixing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing belt unit capable of a steady fixing operation. SOLUTION: The unit has a pressure roller 120 which is brought into pressure contact with a fixing belt 110 heated and coated with oil, one being driven and the other following, and passes a recording material S with a toner image formed thereon through the middle N1 of a pressure contact part N, thereby melting the toner image under heat and fixing it to the surface of the recording material. A high grip member G which has the ability to absorb oil and the ability to cause oil to flow in the direction of the perimeter of the belt is affixed round both ends of the fixing belt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in an image forming apparatus such as a printer, a facsimile, a copying machine, etc., capable of forming a toner image on a recording material such as paper by using an electrophotographic technique. The present invention relates to a belt fixing device using a heated fixing belt.

[0002]

2. Description of the Related Art In general, an image forming apparatus for forming a toner image on a recording material such as paper by using an electrophotographic technique includes a photoconductor which is driven to rotate, and an electrostatic latent image formed on the surface by exposing the photoconductor. Exposure means for forming an image, developing means for developing the electrostatic latent image into a toner image, transfer means for transferring the toner image to a recording material, and a recording material on which the toner image has been transferred by the transfer means And a fixing device for fixing the toner image on the recording material by heating while passing through the recording material.

[0003] The fixing device usually has a rotating body to be heated and a rotating body pressed against the rotating body. The two rotating bodies heat the recording material while pressing the recording material, thereby heating the recording material. The upper toner image is fused and fixed on a recording material. In such a fixing device, if there is a difference between the peripheral speeds of the two rotating members, the toner image on the recording material passing through the pinching portion (pressing portion) is rubbed and the image is disturbed. It does not drive the rotating body, but employs a configuration in which only one rotating body is driven and the other rotating body is driven by it. Further, if the rotating body to be heated is a roller, a long time is required for the initial heating, so that the heated rotating body is an endless belt (fixing belt), and a belt fixing method in which the initial heating time is reduced. Vessels are known.

FIG. 12 is a view showing a first example of a belt fixing device (Japanese Patent Laid-Open No. Hei 9-138600). The belt fixing device includes an endless heat-resistant belt 6, rollers 7a and 7b for supporting the belt 6 from the inside, a roller 8 for heating the belt 6, and a pressure roller 9 for contacting the outer peripheral surface of the belt 6. The pressure roller 9 is rotationally driven in the direction of the arrow a by the motor M, and the belt 6 is driven by the pressure roller 9. The recording material on which the toner image is formed is supplied to a pressure contact portion N between the belt 6 and the pressure roller 9 as shown by an arrow b,
The toner image is heated and melted by passing through the pressure contact portion N, and is fixed on the recording material. FIG. 13 is a view showing a second example of the belt fixing device (Japanese Patent Application Laid-Open No. 8-334997). In this belt fixing device, a fixing belt 1 is wound and stretched between a rotating fixing roller 2 and a heating roller 3 having a built-in heater, and a pressure roller 4 is attached to the fixing roller 2 via the fixing belt 1. The recording material S on which the toner image T is formed is passed through the pressed portion N in the direction of the arrow in the drawing, and the toner image T is heated and melted and fixed on the recording material S. The fixing device also includes a releasing agent such as silicone oil on the surface of the fixing belt 1 as a release agent in order to prevent a phenomenon that a toner on a recording material is transferred to the surface of the fixing belt 1 (a so-called offset phenomenon). An oil application roller 5 for applying release oil is provided.

[0005]

In the conventional belt fixing device shown in FIG. 12, a recording material which is relatively slippery is placed on a pressure contact portion N between a rotationally driven pressure roller 9 and a belt 6 driven by the pressure roller. For example, when a sheet made of synthetic resin is supplied, the slippery recording material intervenes so that the pressure roller 9 on the driving side can be used.
And / or a recording material and / or a slip occurs between the recording material and the driven belt 6, causing a peripheral speed difference between the pressure roller 9 and the belt 6, resulting in a stable fixing operation. May not be performed. Similarly, in the conventional belt fixing device shown in FIG. 13, a relatively slippery recording material is supplied to the pressure contact portion N between the belt 1 driven by the fixing roller 2 and the pressure roller 4 driven by the belt. The slippage of the recording material causes a slip between the belt 1 on the driving side and the recording material and / or between the recording material and the pressure roller 4 on the driven side. There is a possibility that a peripheral speed difference occurs between the roller 4 and the roller 4, and as a result, a stable fixing operation cannot be performed. In particular, in the belt fixing device shown in FIG.
Since the release oil is applied to the surface of the substrate, the slip is promoted. Further, the oil applied to the surface of the belt 1 gradually enters the end portion N ′ of the pressure contact portion N, and reduces the frictional force between the fixing roller 2 and the pressure roller 4 at the end portion N ′. The above-mentioned slip is further promoted. An object of the present invention is to solve the above-described problems and to provide a belt fixing device capable of performing a stable fixing operation.

[0006]

According to a first aspect of the present invention, there is provided a belt fixing device comprising: a fixing belt to be heated; a rotating body pressed against the fixing belt; An oil applying means for applying a release oil, wherein one of the fixing belt and the rotating body is driven, the other is driven, and the recording material on which the toner image is formed,
Pass through the center of the pressure contact part between the fixing belt and the rotating body,
A fixing device that heats and melts the toner image and fixes the toner image on a recording material, wherein a high grip member is provided at both ends of the fixing belt along a circumferential direction thereof, and the high grip member is an oil. It is characterized by having absorbability. According to a second aspect of the present invention, in the belt fixing device of the first aspect, the high grip member has an oil fluidity in a belt circumferential direction. According to a third aspect of the present invention, there is provided a belt fixing device according to the first or second aspect.
In the above-described belt fixing device, the high grip member has oil permeability and is fixed to both ends of the belt via an adhesive layer having oil absorbency.

[0007]

According to the belt fixing device of the present invention, a recording material on which a toner image is formed is heated by one of which is driven and the other is driven by a fixing belt and a rotator which is pressed against the fixing belt. The toner image is heated and melted and fixed on the recording material. Further, since an oil applying means for applying the release oil to the surface of the fixing belt is provided, the offset phenomenon is less likely to occur. Since a high grip member is provided at both ends of the fixing belt along the circumferential direction, a high grip portion for the rotating body is formed at both ends of the fixing belt by the high grip member. Will be done. Therefore, a relatively slippery recording material is supplied to the center of the pressure contact portion between the fixing belt and the rotating body, and the driving-side fixing belt (or the rotating body) and the recording material are separated by the slippery recording material. And / or even if a slip is likely to occur between the recording material and the driven-side rotating body (or the fixing belt), the driving side fixing belt (or the rotating body) is operated by the action of the high grip portion.
Accordingly, the followability of the rotating body (or the fixing belt) on the driven side is improved, and the fixing belt and the rotating body rotate at substantially the same peripheral speed. For this reason, the above-mentioned slip is prevented (at least hardly occurs), and as a result, a stable fixing operation is performed. Therefore, the toner image on the recording material is hardly rubbed, and the image is hardly disturbed. In addition, since the high grip member has oil absorbency, the following operation and effect can be further obtained. That is, when the release oil is applied to the surface of the fixing belt, as described above, the oil gradually enters the end of the pressure contact portion between the fixing belt and the rotating body, According to the belt fixing device of the present invention, the high grip member is provided at both ends of the fixing belt along the circumferential direction, and the high grip member has oil absorbency. The oil that has entered the end of the press-contact portion is absorbed by the high grip member. Therefore, the amount of oil present on the surface of both ends of the fixing belt, that is, the surface of the high grip member forming the high grip portion, becomes small,
As a result, the grip force at both ends of the press contact part is secured,
The above-mentioned slip is prevented (at least, it is hardly caused to occur), and a stable fixing operation is performed. That is, according to the belt fixing device of the first aspect, it is possible to obtain a stable fixing operation even though the releasing oil is applied to the surface of the fixing belt. According to the belt fixing device of the second aspect, in the belt fixing device of the first aspect, the high grip member has oil fluidity in a belt circumferential direction, so that the high grip member is made of oil. Even if the high grip member is saturated, the oil absorbed in the high grip member is discharged to a portion other than the press contact portion in the circumferential direction of the belt by the press contact force at the press contact portion. Therefore, even if the high grip member becomes saturated with oil, the amount of oil existing on the surface of the high grip member forming the high grip portion at both ends of the fixing belt in the press contact portion becomes small, and as a result, As a result, the grip force at both ends of the press contact portion is ensured, the above-mentioned slip is prevented (at least, it is hardly generated), and a stable fixing operation is performed. According to the belt fixing device of claim 3, in the belt fixing device of claim 1 or 2, the high grip member has an oil passage property,
Also, since it is fixed to both ends of the belt via an adhesive layer having oil absorbency, oil that has entered the end of the press contact portion is absorbed by the adhesive layer via the high grip member. It will be. Therefore, the amount of oil present on the surface of the high grip member which forms the high grip portion at both ends of the fixing belt is small, and as a result, the grip force at both ends of the press contact portion is secured, and the slip is prevented (at least significantly). This makes it difficult to cause such a situation, and a stable fixing operation is performed. That is, according to the belt fixing device of the third aspect, although the release oil is applied to the surface of the fixing belt,
It is possible to obtain a stable fixing operation.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> FIG. 1 is a schematic side view showing a first embodiment of a belt fixing device according to the present invention, and FIG. 2 is a schematic perspective view of a main part.

The fixing device 100 has a fixing belt 110 to be heated, and a pressure roller 120 as a rotating body pressed against the fixing belt 110, and records on which a toner image (not shown) is formed. The material S is passed through a central portion N1 of a pressure contact portion N between the fixing belt 110 and the pressure roller 120 as indicated by an arrow S1, and the toner image is heated and melted and fixed on the recording material S. The fixing device 100 of this embodiment has a backup roller 130 as a backup member that supports the fixing belt 110 from the inside at the press contact portion N, and a heating roller 140 as a heating unit that heats the fixing belt 110. The fixing belt 110 includes a backup roller 130 and a heating roller 1.
It is stretched between 40 and 40. Reference numeral 150 denotes an oil application roller as oil application means, which applies a release oil to the surface of the fixing belt 110.

As the driving roller for rotating the fixing belt 110 and each roller, any roller other than the oil application roller 150 can be used. In this embodiment, the pressing roller 120 is used. Used as a drive roller. That is, the pressure roller 1
Reference numeral 20 denotes a backup roller 1 which is rotationally driven in the direction of the arrow (counterclockwise) in FIG.
30, the fixing belt 110, the heating roller 140, and the oil application roller 150 are driven. More specifically, the fixing belt 110 is
And the backup roller 130 is pressed against the fixing belt 110 and the backup roller 1.
30 is driven by the pressure roller 120, and the fixing belt 110 is wound around the heating roller 140, so that the heating roller 140 is driven by the fixing belt 110, and the oil application roller 150 is pressed against the fixing belt 110. As a result, the oil application roller 150 is driven by the fixing belt 110. In FIG. 1, 1
Reference numeral 11 denotes a thermistor for detecting the surface temperature of the fixing belt 110 at a portion where the fixing belt 110 is wound around the backup roller 130. The thermistor 111 is provided on the upstream side of the pressure contact portion N with the pressure roller 120.

The backup roller 130 has a metal core 131 and a relatively thick elastic layer 132 provided on the surface of the core 131.
At 31a, the fixing device 100 is rotatably supported on the side plate 101 of the frame. The heating roller 140 is formed in a pipe shape from a material having excellent thermal conductivity (for example, aluminum), and a halogen lamp 141 as a heat source is disposed inside the heating roller 140. The heating roller 140 can rapidly heat the fixing belt 110 at a portion where the fixing belt 110 is wound. The heating roller 140 according to this embodiment is configured as a tension roller, and is urged in the tensioning direction of the fixing belt 110 by an appropriate urging unit (not shown). Note that in FIG.
Is a thermistor for detecting the temperature of the heating roller 140.

The pressure roller 120 has a pipe-shaped core material 121 having excellent heat conductivity, and a relatively thin elastic layer provided on the surface of the core material 121 and harder than the elastic layer 132 of the backup roller 130. 122 and the elastic layer 122
And a surface layer 122a having excellent releasability from the recording material and the toner formed on the surface thereof, and a halogen lamp 123 as a heat source is disposed inside the core material 121. The pressure roller 120 is connected to the frame side plate 101 of the fixing device 100.
The fixing device 100 is rotatably supported with respect to
1 is driven to rotate in a direction indicated by an arrow in FIG. 1 (counterclockwise) by a driving unit (not shown) provided in an image forming apparatus main body (not shown) to which is attached. The pressing roller 120
Is immovably mounted in its radial direction,
The elastic layer 122 and the elastic layer 132 of the backup roller 130 are pressed against the backup roller 130 via the fixing belt 110 by the elastic force of the elastic layer 132. The pressure contact N
Since the elastic layer 132 of the backup roller 130 is thicker and softer than the elastic layer 122 of the pressure roller 120, the elastic layer 132 is formed in a convex shape on the backup roller 130 side.
In FIG. 1, reference numeral 124 denotes a thermistor for detecting the surface temperature of the pressure roller 120.

On the frame 101, a recording material S on which a toner image is formed (transferred) by a transfer unit of an image forming apparatus (not shown) is provided at a central portion of a pressure contact portion (nip portion) N between the fixing belt 110 and the pressure roller 120. A guide 102 leading to N1 is provided. Downstream of the pressure contact portion N, there are provided a paper discharge roller pair 103 and a guide 104 for guiding the fixed recording material S to a paper discharge path of an image forming apparatus (not shown). Each of the thermistors is connected to a control unit (not shown) of the image forming apparatus, and the heat sources 123 and 141 are controlled by the control unit according to the temperature detected from each thermistor.
Is controlled.

The main feature of this embodiment is that the fixing belt 1
The structure of FIG. 10 will be described. FIG.
(A) shows the fixing belt 110 (backup roller 130)
FIG. 6B is an exploded perspective view of an end of the fixing belt 110) before being stretched between the fixing belt 110 and the heating roller 140, and FIG. FIG. 4A is a partially omitted sectional view of the fixing belt 110 (a sectional view taken along line IVa-IVa in FIG. 3A),
(B) and (c) are partial enlarged views of FIG.

The fixing belt 110 is a heat-resistant belt, and includes an endless belt base 112 and a belt base 11.
2 in the width direction (the left-right direction in FIG. 2 and the axial direction of each roller) and a surface layer 113 coated on the surface of the central portion 112a, and both ends 112b have high grip along the circumferential direction. A member G is provided. The belt base 112 is made of, for example, conductive polyimide. The surface layer 113 is formed by coating a central part 112a in the width direction of the belt base 112 with a high release material (a material excellent in releasability from a recording material and a toner, for example, silicone rubber).
The high grip member G in this embodiment is formed of a cloth as shown in FIG. The cloth referred to here includes a nonwoven fabric as shown in FIG. 5 in addition to a fabric woven or knitted with the weft yarn 114a and the warp yarn 114b. The thread (weft and warp) 114 may be constituted by a single line (for example, a so-called monofilament) as shown in FIG.
As shown in FIG. 4C, it may be constituted by an aggregate (for example, a so-called multifilament) of a plurality of fine wires 114c. In any case, as a material of the thread 114, aramid, polyimide, glass fiber, PET (polyethylene terephthalate), or the like can be used. As shown in FIG. Even in this case, since the oil can be held in the gap C1 between the thread bodies 114, the cloth G has oil absorbency. However, as shown in FIG. If it is constituted by an aggregate, the oil will be absorbed inside the thread 114 itself. Therefore, in order to enhance the oil absorbency, it is desirable that the thread 114 be constituted by an aggregate of a plurality of fine wires. At least weft 114a, warp 114
It is desirable that one of b is constituted by an aggregate of a plurality of thin wires. Further, since the gap C1 communicates with the belt in the circumferential direction (the direction orthogonal to the plane of FIG. 4), the cloth G has oil fluidity in the belt circumferential direction. As the cloth G, a nonwoven cloth (for example, Nomek nonwoven cloth) as shown in FIG. 5 can be used. The nonwoven fabric also has oil absorbency and oil fluidity in the belt circumferential direction. 4 and 5, reference numeral 115 denotes an adhesive layer (for example, an adhesive) fixing the high grip member G to the belt base 112. In this embodiment, FIG.
As shown in (a), a high grip member G formed in a ring shape in advance is slightly wider than the outer diameter of the belt base 112 by utilizing its elasticity (expansion and contractibility). As shown in FIG. 3B, the high grip member G is attached to the portion 112b via an adhesive layer 115 (not shown in FIG.
At 15, it is fixed to the end 112 b of the belt base 112.

According to the fixing device 100 of this embodiment, the following operational effects can be obtained. (A) A pressing portion of a fixing belt 110 to be heated and a pressing roller 120 as a rotating body pressed against the fixing belt 110, one of which is driven and the other of which is driven by a recording material S on which a toner image is formed. By passing through the central portion N1 of N, the toner image is heated and melted and fixed on the recording material S. Further, since the oil applying means 150 for applying the release oil to the surface of the fixing belt 110 is provided, the offset phenomenon is less likely to occur. At both ends of the fixing belt 110, a high grip member G is provided along the circumferential direction. A high grip portion will be formed. Therefore, the fixing belt 110 and the pressure roller 1
A relatively slippery recording material S is supplied to a central portion N1 of the press contact portion N with the recording material 20, and the slippery recording material S is interposed between the pressure roller 120 on the driving side and the recording material S and / or. Even if a slip is likely to occur between the recording material S and the driven side fixing belt 110, the driven side fixing belt 110 is driven by the driving side pressure roller 120 by the action of the high grip portion (G). Thus, the fixing belt 110 and the pressure roller 120 rotate at substantially the same peripheral speed. For this reason, the above-mentioned slip is prevented (at least hardly occurs), and as a result, a stable fixing operation is performed. Therefore, the toner image on the recording material S is hardly rubbed, and the image is hardly disturbed. Moreover, the high grip member G
Has oil absorbency, so that the following operation and effect can be further obtained. That is, when the release oil is applied to the surface of the fixing belt 110, the oil gradually enters the end portion N2 of the pressure contact portion N between the fixing belt 110 and the pressure roller 120 as described above. However, according to the belt fixing device 100, the fixing belt 11
A high grip member G is provided along the circumferential direction at both end portions of the high pressure member 0. Since the high grip member G has oil absorbency, it has penetrated into the end portion N2 of the press contact portion. The waste oil is absorbed by the high grip member G. Therefore, the surface of both ends of the fixing belt, that is, the surface G4 of the high grip member G forming the high grip portion
(See FIG. 4), the amount of oil present is small, and as a result, the grip force at both ends of the press contact portion is secured, the above-mentioned slip is prevented (at least, it is hardly generated), and a stable fixing operation is performed. The Rukoto. That is, according to the belt fixing device 100, it is possible to obtain a stable fixing operation even though the releasing oil is applied to the surface of the fixing belt 110. (B) Since the high grip member G is formed of cloth, the surface G4 (see FIG. 4) of the high grip portion has fine irregularities due to the thread 114 forming the cloth. Is almost uniformly spread. Therefore, vibration and speed fluctuations generated by the drive transmission at both ends of the fixing belt 110 are extremely reduced, and as a result, smooth drive transmission is achieved. Further, since the irregularities are formed by the thread 114, the convex portions are rounded. Therefore, stress concentration in the pressure roller 120 is reduced, and the durability of the pressure roller 120 is improved. Furthermore, the high grip portion is superior in strength (particularly, strength against shearing force) as compared with a case where the high grip portion is made of, for example, a rubber member having irregularities. That is, when the high grip member G is made of, for example, a film or a rubber member, when a shear force is applied to the edge, first, a crack is formed in the edge, and then the crack is rapidly propagated and expanded. However, if the high grip member is made of cloth, even if the fiber (thread) 114 at the edge portion is cracked and broken, the break does not propagate. In this case, only one fiber break occurs. Therefore, for example, the meandering of the fixing belt 110 is applied to the inner surface (145a) of the flange of the roller on which the fixing belt 110 is stretched (for example, the guide ring 145 of the heating roller 140 shown in FIG. 2). If the belt is to be brought into contact with the belt, the shearing force acting on the edge of the belt becomes large, but the high grip member G made of cloth is formed on both ends of the fixing belt 110.
Is provided, it is difficult for the high grip member G to break, and the propagation of the break to the entire belt 110 hardly occurs. In addition, the high grip portion can be configured by simply fixing the cloth G to both ends of the fixing belt 110 along the circumferential direction thereof.
The manufacturing of the fixing belt 110 is simplified as compared with the case where the end itself is processed so as to be a high grip portion. (C) Since the high grip member G has oil fluidity in the belt circumferential direction, even if the high grip member G becomes saturated with oil, it is absorbed in the high grip member G. The oil is applied to the press-contact portion N2 in the circumferential direction of the belt by the press-contact force at the press-contact portion N2.
It will be excluded to other parts. Therefore, even if the high grip member G becomes saturated with oil, the amount of oil existing on the surface G4 of the high grip member G forming the high grip portion at both ends of the fixing belt 110 in the press contact portion is small. As a result, the gripping force at both ends N2 of the press contact portion is secured, the slip is prevented (at least, it is hardly generated), and a stable fixing operation is performed.

<Second Embodiment> FIGS. 6 and 7 show a main part of a belt fixing device according to a second embodiment of the present invention. FIG. 6A shows a fixing belt 110 (backup). FIG. 7B is a partial perspective view of the fixing belt 110 before being stretched between the roller 130 and the heating roller 140, FIG. 7B is a front view of the high grip member G, and FIG.
It is a-VIIa sectional drawing. This embodiment is similar to the first embodiment.
The difference from this embodiment is that a tape-shaped high grip member G as shown in FIG. 6B is attached to the end 112b of the belt base 112 along the circumferential direction as shown in FIG. 6A. , And is fixed by the adhesive 115, and the other points remain unchanged. In this embodiment, as shown in FIGS. 6A and 7A, a winding start end G1 of a tape-shaped high grip member G is formed.
And the end portion G2 are wound and fixed so as not to overlap. Therefore, the winding start end G1 and the end G
2, a small gap L is formed, but this gap L should be minimized (at least shorter than the circumferential length of the pressure contact portion N between the fixing belt 110 and the pressure roller 120). desirable. In addition, as shown in FIG.
The winding start end G1 and the end G2 may be wound and fixed so as to overlap with each other, but in this case, an overlapping portion G3 of the winding start end G1 and the end G2 is formed.
Is thicker, the overlapping portion G3 is
There is a possibility that the speed of the fixing belt 110 on the driven side fluctuates between the time when the fixing belt 110 is pressed against the pressure roller 120 and the time other than the time when the pressure is applied. This is not desirable because stress may be concentrated on the pressure roller 120 in a portion facing the pressure roller 120 and durability of the pressure roller 120 may be reduced. According to this embodiment, the following operation and effect can be obtained in addition to the operation and effect obtained by the first embodiment. That is, since the high grip portions at both ends of the fixing belt 110 can be configured by simply winding and fixing the tape-like high grip members G to both ends of the fixing belt 110, the production of the fixing belt (therefore, the fixing device Manufacturing) is further simplified.

<Third Embodiment> FIG. 8 is a view showing a main part of a third embodiment of a belt fixing device according to the present invention.
(A) is a partial front view of the fixing belt 110, (b) is a development view of a tape-shaped cloth G. In FIG. 8, the same or corresponding portions as those in the second embodiment are denoted by the same reference numerals. This embodiment is different from the second embodiment in that the winding start end G1 and the end G2 of the tape-shaped high grip member G are inclined to face each other. The point remains the same. That is, the winding start end G1 and the end G2 of the tape-shaped high grip member G in this embodiment are formed by the pressing roller 120.
Is not parallel to the axial direction of the fixing belt 11.
It is also inclined with respect to the zero circulation direction. According to this embodiment, the following operation and effect can be obtained in addition to the operation and effect obtained by the second embodiment. That is, assuming that the winding start end G1 and the end G2 of the tape-shaped high grip member G are not inclined (for example, inclined with respect to the width direction of the belt 110 or the axial direction of the pressure roller 120), Start end G1 and end G2
Is formed between the pressure roller 120
There is a possibility that the speed of the driven fixing belt 110 fluctuates between the time when the fixing belt 110 is pressed and the other time. For example, suppose that the aforementioned gap L in the second embodiment is used.
Is a pressure contact portion N between the fixing belt 110 and the pressure roller 120.
If it is longer than the length in the circumferential direction, there is a high possibility that the speed fluctuation will occur. On the other hand, according to the third embodiment, the tape-like high grip member G
Since the winding start end G1 and the end G2 are inclined to face each other, the speed of the driven fixing belt 110 is less likely to fluctuate.

<Fourth Embodiment> FIG. 9 is a diagram showing a main part of a fourth embodiment of a belt fixing device according to the present invention.
(A) is a partial plan view of the fixing belt 110, and (b) and (c) are bb cross-sectional views in FIG. In the figure, the same reference numerals are given to the same or corresponding parts as in the first to third embodiments. This embodiment is characterized by oil absorption and belt circumferential direction (FIG. 9).
FIG. 7A shows a high grip member G having oil fluidity in a vertical direction (arrows Y1 and Y2 directions) in FIG.
As shown in (b), it extends in a direction perpendicular to the belt surface (vertical direction in FIG. (B)), a lateral direction (horizontal direction in FIG. (A)), and a vertical direction (vertical direction in FIG. (A)). It is composed of a heat-resistant tape made of a synthetic resin having fine voids C2, or is composed of a continuous-cell porous material (for example, silicone sponge) as shown in FIG. In FIG. (C), the open cell portion is indicated by C3. The heat-resistant tape made of a synthetic resin as shown in FIGS. (A) and (b) also has oil absorbency and oil fluidity in the belt circumferential direction due to the action of the fine gap C2.
Further, the open-cell porous material as shown in FIG. 3C also has oil absorption and oil flow in the belt circumferential direction by the action of the open-cell pore C3. Depending on the mode, the same operation and effect as (a) and (c) according to the first embodiment can be obtained. That is,
Since the high grip member G is made of a material having oil absorbency and oil flowability in the belt circumferential direction, even if the high grip member G becomes saturated with oil, the high grip member G The absorbed oil is pressed by the pressing force at the pressing portion N2 as shown in FIG.
As shown by arrows Y1 and Y2 in the belt peripheral direction, it is excluded to a portion other than the press contact portion N2. Therefore, even if the high grip member G becomes saturated with oil, the amount of oil existing on the surfaces of both ends of the fixing belt, that is, the surface G4 of the high grip member G, becomes small at the press contact portion N2. As a result, the grip force at both ends N2 of the press contact portion is ensured, the above-mentioned slip is prevented (at least hardly to occur), and a stable fixing operation is performed.

<Fifth Embodiment> FIGS. 10 and 11 show a main part of a belt fixing device according to a fifth embodiment of the present invention. In these figures, the same or corresponding parts as those in the first to fourth embodiments are denoted by the same reference numerals. The feature of this embodiment is that the high grip member G has both ends 112b of the belt through an adhesive layer 116 having oil permeability and oil absorbability.
In that it is fixed to Specifically, for example, FIG.
As shown in FIGS. 0 (a) and (b), the high grip member G made of cloth is fixed to both ends 112b of the belt via an adhesive layer (for example, a silicone rubber layer) 116 having oil absorbency. Alternatively, as shown in FIG. 11A, a synthetic resin heat-resistant tape having fine voids C2 (FIG. 9A)
The high grip member G made of the tape shown in FIG.
It is fixed to both ends 112b of the belt via the adhesive layer 116. Alternatively, as shown in FIGS. 11B and 11C, a high grip member G made of a synthetic resin heat-resistant tape having a large number of through holes C4 is attached to both end portions 112b of the belt via the adhesive layer 116. Stick. Note that the nonwoven fabric shown in FIG. 5 or the open-cell porous material shown in FIG.
May be fixed. According to this embodiment, the oil that has entered the end portion N2 of the press contact portion N is absorbed by the adhesive layer 116 via the cloth G. Therefore, the amount of oil existing on the surface G4 at both ends of the fixing belt is further reduced, and as a result, the grip force at both ends of the press contact portion is sufficiently ensured, and the above-mentioned slip is prevented (at least significantly less likely to occur). Thus, a more stable fixing operation is performed.

[0021]

EXAMPLE A further specific example will be described. The structure of the fixing belt 110 is a seamless belt, and the belt base 112 is an endless belt-like sheet made of conductive polyimide. Belt base 112
Has a thickness of about 150 μm. The width of the belt base 112 is about 392 mm, and only the center portion thereof is coated with silicone rubber to a thickness of about 200 μm to cover the surface layer 1.
13 and exposed portions 112 having a width of about 27 mm at both ends.
b is formed. The inner diameter of the belt base 112 is about φ60 mm.

The structure of the pressure roller 120 is iron (SUM2) having hollow shaft portions 125 (see FIG. 2) at both ends.
4) A pipe portion 121 having an outer diameter of about 32 mm and an inner diameter of about 22 is made of a silicone rubber as an elastic layer 122 on the outer peripheral surface and a fluorine resin as a surface layer 122 a on the outer peripheral surface. The rubber hardness of the elastic layer 122 is J
IS-A is about 20 °, and the layer thickness is about 1.5 mm. The surface layer 122a is a fluorine latex film that is thermally cured after applying a fluorine latex paint. The layer thickness is about 60 μm. The calorific value of the halogen lamp 123 provided in the hollow portion is about 230 W at 100 V. The outer diameter of the pressure roller 120 is about 35.2 mm. Shaft 1
Roller width (length in the axial direction) including 24 is 444.3 mm
Degree. The pressing load on the backup roller 130 is applied to the shaft portions 125, 125, and is approximately 60 kg on one side (total load on both ends is 120 kg). The backup roller 130 and the pressure roller 120 are fixed to the frame 101 at a fixed position (the distance between the shafts is fixed), and no special pressing means is provided. The pressing load is generated when the two rollers 120 and 130 are fixed to the frame 101 such that the distance between the shafts is shorter than the sum of the outer diameters of the two rollers 120 and 130, and the two rollers cut into each other. The position where the load is applied to the roller is a position where the roller is fixed to the frame, and is a position of a bearing (not shown) which is a bearing of the shaft 124. The circumferential length L2 of the press contact portion N with the fixing belt 110 is about 11 mm.

The structure of the backup roller 130 is as follows. The outer peripheral surface of a solid iron (SUM24) roller of approximately φ26 having a shaft portion 131a of approximately φ10 at both ends is formed of silicone rubber as an elastic layer 132, and the outer peripheral surface thereof. Is coated with PFA (ethylene tetrafluoride / perfluoroalkoxy ethylene copolymer) as the surface layer 132a. The outer diameter of the backup roller 130 is about 38.5 mm, and the roller width excluding the shaft 131a is about 398 mm. The layer thickness of the elastic layer 132 is about 6.25 mm. Rubber hardness is about JIS-A10 °. Surface layer 1
32a uses a heat-shrinkable PFA resin tube. The layer thickness after coating is about 110 μm.

(Regarding the heating roller 140) The structure has a shaft portion 144 of about φ20 at both ends, an outer diameter of about φ28,
A pipe-shaped aluminum roller having a thickness of about 3 mm is used. The roller width excluding the shaft 144 is about 393 mm. The heating means 141 disposed in the hollow portion of the roller is a halogen lamp. The heat value is about 695 W at 100 V.

The structure of the oil applying roller 150 is such that an oil retaining layer 152 composed of an oil impregnated layer 152a and an oil supply layer 152b and a surface layer 153 are sequentially laminated on an iron (SUM24) shaft 151 having a diameter of about 10 mm. Structure. The outer diameter of the oil application roller 150 is about 36 mm, and the roller width not including the shaft end is 337 to 3
The range is about 92 mm, desirably a range that covers the paper passing range without involving the high grip portion. Specifically, it is about 337 mm. The oil-impregnated layer 152a is made of sponge and has a thickness of about 11 mm. Oil supply layer 152b
Is made of felt, and the layer thickness is about 2 mm. The surface layer 153 is made of porous PTFE (tetrafluoroethylene polymer) resin and has a thickness of about 120 μm. The material of the release agent is dimethyl silicone oil. Viscosity (20 ° C
Is about 100 centistokes, and the total amount of impregnation is about 140 g. The contact load (pressing load) to the fixing belt 110 can be appropriately set within a range of a total load of 0.5 to 2 kg, but is more preferably about 1 kg. The contact width (length in the belt moving direction) between the oil application roller 150 and the fixing belt 110 is about 3 mm.

Although the embodiments and examples of the present invention have been described above, the present invention is not limited to the above-described embodiments or examples, and may be appropriately modified within the scope of the present invention. It is.

[0027]

According to any one of the belt fixing devices according to the first to third aspects, a stable fixing operation can be obtained even though the releasing oil is applied to the surface of the fixing belt. .

[0028]

[Brief description of the drawings]

FIG. 1 is a schematic side view showing a first embodiment of a belt fixing device according to the present invention.

FIG. 2 is a schematic perspective view of a main part.

3A is an exploded perspective view of an end of the fixing belt 110 (the fixing belt 110 before being stretched between the backup roller 130 and the heating roller 140), and FIG. It is a perspective view.

4A is a partially omitted cross-sectional view of the fixing belt 110 (a cross-sectional view taken along IVa-IVa in FIG. 3A), and FIG.
(C) is a partial enlarged view of FIG.

5A is a partially omitted cross-sectional view of the fixing belt 110 (a cross-sectional view taken along a line IVa-IVa in FIG. 3A), and FIG.
3 is a partially enlarged view of FIG.

6A and 6B are diagrams illustrating a main part of a belt fixing device according to a second embodiment of the present invention. FIG. 6A illustrates a fixing belt 110 (before being stretched between a backup roller 130 and a heating roller 140). Partial perspective view of the fixing belt 110) in the state of FIG.
(B) is a front view of the high grip member G.

FIGS. 7A and 7B are diagrams showing main parts of the embodiment, wherein FIG. 7A is a cross-sectional view taken along the line VIIa-VIIa in FIG. 6, and FIG.

8A and 8B are diagrams showing a main part of a belt fixing device according to a third embodiment of the present invention, wherein FIG. 8A is a partial front view of a fixing belt 110, and FIG. is there.

9A and 9B are diagrams showing a main part of a fourth embodiment of the belt fixing device according to the present invention, wherein FIG. 9A is a partial plan view of the fixing belt 110, and FIGS. It is bb sectional drawing.

FIGS. 10A and 10B are diagrams showing a first example of a main part of a belt fixing device according to a fifth embodiment of the present invention, wherein FIG.
0 is a partial plan view, and (b) is a bb cross-sectional view in FIG.

FIG. 11A is a cross-sectional view showing a second example of a main part of a belt fixing device according to a fifth embodiment of the present invention (FIG. 10A).
FIG. 2 is a diagram corresponding to a bb cross-sectional view in FIG. (B) and (c) are views showing a third example of a main part of a belt fixing device according to a fifth embodiment of the present invention, (b) is a partial plan view of the fixing belt 110, and (c) is a diagram ( It is cc sectional drawing in b).

FIG. 12 is an explanatory diagram of a conventional technique.

FIG. 13 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 S Recording Material 100 Fixing Unit 110 Fixing Belt 112 Belt Base 112a Central Part of Belt Base in Width Direction 112b End of Belt Base 113 Surface Layer G High Grip Member 115, 116 Adhesive Layer 120 Pressure Roller (Rotating Body) 150 Oil Roller ( Oil application means) N pressure contact part N1 central part of pressure contact part N2 end part of pressure contact part

Continued on the front page (72) Inventor Hiroshi Tanaka 3-3-5 Yamato, Suwa-shi, Nagano Seiko Epson Corporation F-term (reference) 2H033 AA14 BA42 BA43 BB03 BB30 BE03 3F049 BA01 BA11 DA04 LA02 LB03

Claims (3)

[Claims] An image forming apparatus comprising: a fixing belt to be heated; a rotating body pressed against the fixing belt; and an oil applying unit for applying a release oil to a surface of the fixing belt. One of them is driven, the other is driven, and the recording material on which the toner image is formed is passed through the center of the pressure contact portion between the fixing belt and the rotating body, and the toner image is heated and melted and fixed on the recording material. A high-grip member is provided at both ends of the fixing belt along a circumferential direction thereof, and the high-grip member has oil absorbability. Belt fuser. 2. The high grip member has oil fluidity in a belt circumferential direction.
The belt fixing device as described. 3. The belt according to claim 1, wherein the high grip member has an oil-permeable property and is fixed to both ends of the belt via an adhesive layer having an oil-absorbing property. Belt fuser.