JP2001100565A - Belt type fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a belt type fixing device capable of performing stable fixing operation. SOLUTION: This device has a pressure roller 120 press-containing with a fixing belt 110 to be heated, and either the belt 110 or the roller 120 is driven and the other follows it. Then, recording materials S where a toner image is formed is made to pass through the center part N1 of a press-contact part N so that the toner image is heated, melted and fixed on the material S. The device is provided with high grip members at both ends of the roller 120 in the peripheral direction thereof. The grip member is constituted of an endless belt having an inner diameter smaller than the outer diameter of the end of the roller 120 in a free state and equipped with elongating and contracting property.

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. 9 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 has been formed is supplied to the pressure contact portion N between the belt 6 and the pressure roller 9 as shown by an arrow b, and the toner image is heated and melted by passing through the pressure contact portion N, so that the toner image is formed on the recording material. Be established. FIG. 10 is a view showing a second example of the belt fixing device (Japanese Patent 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. 9, a recording material which is relatively slippery is applied to 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 is interposed between the pressure roller 9 on the driving side and the recording material and / or the belt 6 on the recording material and the driven side.
Between the pressure roller 9 and the belt 6, and as a result, a stable fixing operation may not be performed. Similarly,
In the conventional belt fixing device shown in FIG.
When a relatively slippery recording material is supplied to the pressure contact portion N between the belt 1 driven by the belt and the pressure roller 4 driven by the belt 1,
Due to the slippery recording material, the driving belt 1
And / or a recording material and / or a slippage between the recording material and the driven pressure roller 4, resulting in a peripheral speed difference between the belt 1 and the pressure roller 4, resulting in a stable There is a possibility that the fixing operation is not performed. In particular, in the belt fixing device shown in FIG. 10, since the release oil is applied to the surface of the belt 1, 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; and a rotating body pressed against the fixing belt. One of the rotating members is driven, and the other is driven, and the recording material on which the toner image is formed is passed through the central portion of the pressure contact portion between the fixing belt and the rotating member to heat and fuse the toner image for recording. A fixing device for fixing on a material, wherein a high grip member is provided on both ends of the rotating body along a circumferential direction thereof, and the high grip member is free from the end of the rotating body in a free state. It is characterized by being constituted by an endless belt having an inner diameter smaller than the outer diameter of the elastic member and having elasticity.

[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. Since a high grip member is provided at both ends of the rotating body along the circumferential direction, a high grip portion for the fixing belt is formed at both ends of the rotating body. . 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 rotating body (or the fixing belt), the action of the high grip portion causes the driving side fixing belt (or the rotating body) to move. The followability of the driven rotating body (or the fixing belt) 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 portion is constituted by an elastic endless belt having an inner diameter smaller than the outer diameter of the end of the rotating body in a free state, a high grip member is provided with respect to the end of the rotating body. Can be extended and contracted to form a high grip portion in a state along the end of the rotating body. Further, for example, when the high grip member is wound around and fixed to both ends of the rotating body, there is a possibility that the high grip member is easily peeled off from the joint.
According to the configuration described above, such a possibility is eliminated, and the high grip member also serves as a reinforcing member for the end portion of the rotating body, so that the mechanical reliability is improved.

[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 fixing belt 110 is a heat-resistant belt, and includes an endless belt base 112 and the belt base 11.
2 in the width direction (the left-right direction in FIG. 2 and the axial direction of each roller). The belt base 112 is made of, for example, conductive polyimide. Surface layer 113,
The central portion 112a in the width direction of the belt base 112 is formed by coating a high release material (a material having excellent releasability from recording material and toner, for example, silicone rubber).

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.

A recording material S, on which a toner image is formed (transferred) by a transfer unit of an image forming apparatus (not shown), is placed on the frame 101 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 pressure roller 1
The structure of the end portion 20 will be described.
FIG. 3A is an exploded perspective view of an end of the pressure roller 120,
(B) is a side view, (c) is a perspective view of an end, and (d) is a side view. 4A is a partially omitted sectional view of the pressure roller 120 (a sectional view taken along line IVa-IVa in FIG. 3C), and FIGS. 4B and 4C are partially enlarged views of FIG.

At both ends of the pressure roller 120, high grip members G are provided along the circumferential direction. The high grip member G in this embodiment is formed of a cloth as shown in FIG. The cloth referred to here is weft 114
A nonwoven fabric as shown in FIG. 5 is also included in addition to a woven or knitted one (including a net-like body) formed by a and the warp 114b. The thread (weft and warp) 114 may be formed of a single line (for example, a so-called monofilament) as shown in FIG. 4B, or a plurality of thin lines 114c as shown in FIG.
(For example, a so-called multifilament). In any case, as the material of the thread 114, aramid, polyimide, glass fiber, PET (polyethylene terephthalate), or the like can be used.
As shown in (b), even in the case of the cloth in which the thread 114 is formed of a single line, the oil can be held in the gap C1 between the thread 114, so that the cloth G has oil absorbency. As shown in FIG. 4 (c), if the thread 114 is composed of an aggregate of a plurality of fine wires, oil will be absorbed inside the thread 114 itself. It is desirable that 114 be constituted by an aggregate of a plurality of fine wires. It is desirable that at least one of the weft thread 114a and the warp thread 114b be formed of an aggregate of a plurality of fine wires. Further, since the gap C1 is open in the vertical direction in FIG. 4A and communicates also in the roller circumferential direction (the direction orthogonal to the paper surface in FIG. 4), the cloth G has oil permeability. And has oil fluidity in the roller 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 roller circumferential direction. 3, 4 and 5, reference numeral 115 denotes an adhesive layer (for example, an adhesive) fixing the high grip member G to the end of the pressure roller 120.

In this embodiment, the high grip member G
3 (see FIG. 3) is formed in an endless belt shape having an inner diameter smaller than the outer diameter of the end portion of the pressure roller 120 in a free state and having elasticity.
(A) As shown in (b), by using the elasticity, the end of the pressure roller 120 is slightly wider than the outer diameter of the end of the pressure roller 120 via the adhesive layer 115 at the end, as shown in FIGS. Is attached as shown in FIG.
5 is fixed to the end of the pressure roller 120.

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. Since the high grip members G are provided at both ends of the pressure roller 120 along the circumferential direction, the fixing belts 110 are provided at both ends of the pressure roller 120 by the high grip members G. , A high grip portion is 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
Is constituted by an elastic endless belt having an inner diameter smaller than the outer diameter of the pressure roller 120 in a free state, so that the high grip member G expands and contracts with respect to the end of the pressure roller 120. It is possible to form a high grip portion that is fitted and is in good condition along the end of the pressure roller 120. Further, for example, when a tape-shaped high grip member is wound around both ends of the pressure roller 120 and fixed, there is a possibility that the high grip member is easily peeled off from the joint (between the winding start end and the end). However, according to the configuration of this embodiment, such a fear is eliminated and the high grip member G is
Since it also plays a role as a reinforcing material at the 20 end, mechanical reliability is improved. Furthermore, since the high grip portion can be configured by simply fixing the high grip member G to both ends of the pressure roller 120 along the circumferential direction thereof, for example, the end itself of the pressure roller 120 can be used. ,
The manufacturing of the pressure roller 120 is simplified as compared with the case where the processing is performed so as to form a high grip portion. (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 pressure roller 120 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 fixing belt 110 is reduced, and the durability of the fixing belt 110 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, when 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. (1) Since only one fiber break occurs, the strength is excellent. (C) Since the high grip member G 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 110, the oil is applied to the fixing belt 110 as described above.
And gradually enters the end portion N2 of the pressure contact portion N between the pressure roller 120 and the pressure roller 120. According to the belt fixing device 100, both ends of the pressure roller 120 are disposed along the circumferential direction. Since the high grip member G is provided, and the high grip member G has oil absorbency, the oil that has entered the end portion N2 of the press contact portion is absorbed by the high grip member G. The Rukoto. Therefore, the amount of oil existing on the surfaces of both ends of the pressure roller 120, that is, on the surface G4 (see FIG. 4) of the high grip member G forming the high grip portion is small, and as a result, the grip force at both ends of the press contact portion is reduced. As a result, the slip is prevented (at least significantly less likely to occur), and a stable fixing operation is performed. 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. (D) Since the high grip member G has oil fluidity in the roller circumferential direction, even if the high grip member G becomes saturated with oil, it is absorbed in the high grip member G. At the press contact portion N2 (see FIG. 2), the oil is discharged to a portion other than the press contact portion N2 in the roller circumferential direction (a direction orthogonal to the paper surface of FIG. 4) due to the press contact force. Therefore, even if the high grip member G becomes saturated with oil, the amount of oil present on the surface G4 of the high grip member G forming the high grip portion at both ends of the pressure roller 120 in the press contact portion is small. 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.

<Second Embodiment> FIG. 6 is a view showing a main part of a second embodiment of a belt fixing device according to the present invention.
(A) is a partial plan view of the pressure roller 120, (b) and (c).
3 is a cross-sectional view taken along line bb in FIG. In the figure, the same or corresponding parts as in the first embodiment are denoted by the same reference numerals. This embodiment is characterized by oil absorption and roller circumferential direction (FIG. 6).
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), the direction perpendicular to the roller peripheral surface (vertical direction in FIG. (B)), the lateral direction (horizontal direction in FIG. (A)), and the vertical direction (vertical direction in FIG. (A)) It is composed of a heat-resistant tape made of a synthetic resin having fine voids C2 that extend, or is composed of an open-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 roller 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 absorbency and oil fluidity in the roller circumferential direction by the action of the open-cell pore C3. Therefore,
According to this embodiment, the same operation and effect as (a), (c) and (d) according to the first embodiment can be obtained. That is, since the high grip member G is made of a material having an oil absorbing property and an oil fluidity in the roller circumferential direction, even if the high grip member G becomes saturated with oil, the high grip member G The oil absorbed into the inside of the press-contact portion N2 is removed by the press-contact force to a portion other than the press-contact portion N2 in the roller circumferential direction as shown by arrows Y1 and Y2 in FIG. Become. Therefore, even if the high grip member G becomes saturated with oil, the amount of oil present on the surfaces of both ends of the pressure roller 120, that is, the surface G4 of the high grip member G, is small in the press contact portion N2. As a result, the grip force at both ends N2 of the press contact portion is secured,
The above-mentioned slip is prevented (at least, it is hardly caused to occur), and a stable fixing operation is performed.

<Third Embodiment> FIGS. 7 and 8 show a main part of a belt fixing device according to a third embodiment of the present invention. In these drawings, the same or corresponding parts as those in the first and second embodiments are denoted by the same reference numerals. The feature of this embodiment is that the high grip member G
Is fixed to both ends of the pressure roller 120 via an adhesive layer 116 having oil permeability and having oil absorbency. Specifically, for example, FIG.
(A) As shown in (b), the high grip member G made of cloth is fixed to both ends of the pressure roller 120 via an adhesive layer (for example, a silicone-based adhesive) 116 having oil absorbency. Alternatively, as shown in FIG. 8 (a), a synthetic resin heat-resistant tape having fine voids C2 (FIG. 6 (a)
The high grip member G made of the tape shown in FIG.
It is fixed to both ends of the pressure roller 120 via the adhesive layer 116. Alternatively, as shown in FIGS. 8B and 8C, 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 ends of the pressure roller 120 via the adhesive layer 116. Stick to the part. Since the nonwoven fabric shown in FIG. 5 or the open-cell porous material shown in FIG. 6C also has oil permeability, these materials are applied to both ends of the pressure roller 120 via the adhesive layer 116. May be fixed. According to this embodiment, the same operation and effect as (a) in the first embodiment can be obtained. Further, 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 pressure roller 1
The amount of oil existing on the surface G4 at both ends is smaller, 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 hardly occurs), so that the oil is more stable. The fixing operation is performed. In addition, according to FIG. 7, the same operation and effect as (b) to (d) according to the first embodiment can be obtained, and according to FIG. 8A, the first embodiment can be obtained. Thus, the same operation and effect as those of (c) and (d) can be obtained.

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

[0022]

According to the belt fixing device of the first aspect,
A stable fixing operation is performed. In addition, the high grip member can be extended and contracted and fitted to the end of the rotating body to form a high grip portion that is in good condition along the end of the rotating body. Reliability is improved.

[0023]

[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 pressure roller 120, FIG. 3B is a side view thereof, FIG. 3C is a perspective view of the end,
(D) is a side view thereof.

4A is a partially omitted cross-sectional view of the pressure roller 120 (a cross-sectional view taken along the line IVa-IVa in FIG. 3C), and FIG.
(C) is a partial enlarged view of FIG.

5A is a partially omitted cross-sectional view of the pressing roller 120 (a view corresponding to a cross-sectional view taken along the line IVa-IVa in FIG. 3C), and FIG. 5B is a partially enlarged view of FIG.

FIGS. 6A and 6B are diagrams showing main parts of a belt fixing device according to a second embodiment of the present invention, wherein FIG. 6A is a partial plan view of a pressure roller 120, and FIGS. Bb in)
Sectional view.

FIGS. 7A and 7B are diagrams showing a first example of a main part of a third embodiment of the belt fixing device according to the present invention, wherein FIG.
(B) is a bb sectional view in FIG. (A).

8A is a cross-sectional view showing a second example of a main part of a belt fixing device according to a third embodiment of the present invention (a diagram corresponding to a bb cross-sectional view in FIG. 7A). . (B) and (c) show the third part of the main part of the third embodiment of the belt fixing device according to the present invention.
FIG. 3B is a diagram illustrating an example, in which FIG. 4B is a partial plan view of the pressure roller 120, and FIG.

FIG. 9 is an explanatory diagram of a conventional technique.

FIG. 10 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 S Recording Material 100 Fixing Device 110 Fixing Belt 115, 116 Adhesive Layer 120 Pressure Roller (Rotating Body) G High Grip Member N Pressure Contact N1 Center of Pressure Contact N2 End of Pressure Contact

Claims (1)

[Claims] An image forming apparatus includes: a fixing belt to be heated; and a rotating body pressed against the fixing belt. One of the fixing belt and the rotating body is driven, and the other is driven to form a toner image. A fixing device for passing a recording material through a central portion of a pressure contact portion between the fixing belt and a rotating body to heat and melt the toner image to fix the toner image on the recording material. Along the direction, a high grip member is provided, and this high grip member,
A belt fixing device comprising: an elastic endless belt having an inner diameter smaller than an outer diameter of the end of the rotating body in a free state.