JP2001100555A - 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 which is in press-contact with a fixing belt 110 to be heated and coated with oil, and either the belt 110 or the roller 120 is driven and the other follows it. Recording material 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 G at both ends of the roller 120 in the peripheral direction thereof. The rugged pattern of the surface of the member G is inclined to the width direction of the roller 120. The rugged pattern is linearly symmetric with respect to the center line in the width direction of the roller 120.

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. 13 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. 14 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. 13, a recording material which is relatively slippery is provided at a pressure contact portion N between a rotationally driven pressure roller 9 and a belt 6 driven by the 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. 14, 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. Particularly, 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; and a rotating body pressed against the fixing belt. One of the rotators is driven, 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 rotator to heat and fuse the toner image to form a recording material. A fixing device for fixing on the upper side, wherein a high grip member is provided at both end portions of the rotating body along a circumferential direction thereof, and the uneven pattern on the surface of the high grip member has a width of the rotating body. It is characterized by being inclined with respect to the direction.

[0007]

According to the belt fixing device of the first aspect, the recording material on which the toner image has been formed is heated by one of which is driven and the other is driven by the fixing belt, and is rotated by being pressed against the fixing belt. When the toner image passes through the center of the pressure contact portion with the body, 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 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 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. Moreover, since the uneven pattern on the surface of the high grip member is inclined with respect to the width direction of the rotating body,
In the pressure contact portion with the fixing belt, the wedge effect (rotational direction (driving direction)
Wedge effect). Therefore,
The grip force in the high grip portion is improved, and the slip is more effectively prevented (at least hardly occurs), and as a result, a more stable fixing operation is performed. Also, if the uneven pattern on the surface of the high grip member is not inclined with respect to the width direction of the rotating body (parallel to the axial direction of the rotating body), vibration due to drive transmission (caused by the uneven pattern) However, according to the belt fixing device of the first aspect, the uneven pattern on the surface of the high grip member is
Since the rotating body is inclined with respect to the width direction, such vibration is significantly reduced, and the drive transmission is smoothly performed.

[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. As shown in FIG. 2, the heating roller 140 is provided with guide rings 145 and 145 as regulating portions for regulating the deviation of the belt 110 by contacting the side end of the fixing belt 110. Fifteen
0 is an oil application roller as oil application means,
Release oil is applied 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 and a surface layer 113 coated on the surface. The belt base 112 is made of, for example, conductive polyimide. The surface layer 113 is formed by coating the surface of the belt base 112 with a high release material (a material having excellent releasability from a 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 both ends of 20 is described. FIG. 3A is an exploded perspective view of an end of the pressure roller 120, and FIG. 3B is a perspective view of the end. 4A is a partially omitted front view of the pressure roller 120, and FIGS. 4B and 4C are front views showing examples of the concavo-convex pattern.

As shown in these figures, as shown in FIG.
0 at both ends of the high grip member G along its circumferential direction.
Are fixed via an adhesive layer 116 (see FIG. 5B). In the high grip member G, the uneven pattern GP on the surface G4 is inclined with respect to the width direction (axial direction) of the pressure roller 120. In FIG. 4, an uneven pattern GP with respect to the circumferential direction of the roller (the vertical direction in FIG. 4)
Is indicated by θ. The inclination angle of the concavo-convex pattern GP is determined by the center line CL in the width direction of the pressure roller 120.
It is desirable to be configured to be line-symmetric with respect to,
In this embodiment, the angle is set to approximately 45 °. The high grip member G can be made of an appropriate material, for example, rubber, synthetic resin, or the like. Also, an appropriate pattern can be adopted as the concave / convex pattern GP on the surface thereof. For example, a lattice pattern as shown in FIG. 4A, a long hole or an elliptical shape as shown in FIG. A continuous pattern of (track shape) convex portions GP1 or a continuous pattern of rectangular or rhombic holes or convex portions GP2 as shown in FIG.

FIGS. 5A and 5B are views showing an end portion of the pressure roller 120 employed in this embodiment. FIG. 5A is an enlarged front view with a part omitted, and FIG. 5B is a sectional view taken along line bb in FIG. is there. In this embodiment, as shown in FIG. 5, the high grip member G is made of a cloth (including a net) woven or knitted with thread bodies 114a and 114b crossing each other. Thread 1
14 (a, b) may be composed of a single wire (for example, a so-called monofilament) or may be composed of an aggregate of a plurality of fine wires (for example, a so-called multifilament).
In any case, the material of the thread 114 may be aramid, polyimide, glass fiber, PET (polyethylene terephthalate) or the like. C1
The cloth G has oil absorbency because the oil can be held in the thread body 114. However, if the thread body 114 is composed of an aggregate of a plurality of fine wires, the oil is also absorbed inside the thread body 114 itself. Therefore, it is desirable that the thread 114 be formed of an aggregate of a plurality of fine wires in order to enhance the oil absorbency. The gap C1 is open in the vertical direction in FIG.
(B), the cloth G has oil permeability and oil fluidity in the roller circumferential direction.

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.
As shown in FIG. 3A, an adhesive layer 116 (not shown in FIG. 3) is attached to the end of the pressure roller 120 in a state in which the end is slightly wider than the outer diameter of the end by utilizing its elasticity. (B) as shown in FIG.
It is fixed to the end of the pressure roller 120 with its shrinkability and adhesive layer 116. The adhesive layer 116 is made of an adhesive having flexibility and oil absorbability (for example, a silicone-based adhesive).
It consists of.

In this embodiment, as shown in FIG. 5B, the outer diameter D2 of the high grip member G is
It is configured to be larger than the outer diameter D1 of 2a. In this embodiment, the outer diameter D2 of the high grip member G is larger than the outer diameter D1 of the surface layer 122a by configuring the thickness t2 of the adhesive layer 116 and the high grip member G to be greater than the thickness t1 of the surface layer 122a. It is configured to be large.

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. 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. Accordingly, the relatively slippery recording material S is supplied to the central portion N1 of the pressure contact portion N between the fixing belt 110 and the pressure roller 120, and the driving side pressure roller 1
Even if a slip is likely to occur between the recording material S and the recording material S and / or between the recording material S and the fixing belt 110 on the driven side, the pressure on the driving side is exerted by the action of the high grip portion (G). Fixing belt 1 on the driven side with respect to roller 120
10, 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. In addition, since the uneven pattern GP on the surface G4 of the high grip member G is inclined with respect to the width direction of the pressure roller 120, the inclined irregularities GP are formed in the pressure contact portion N2 (see FIG. 2) with the fixing belt 110. According to the pattern GP,
In other words, a wedge effect (a wedge effect in the rotation direction (drive transmission direction)) can be obtained. Therefore, the grip force in the high grip portion (G) is improved, and the above-described slip is more effectively prevented (at least, it is hardly generated),
As a result, a more stable fixing operation is performed. Further, if the uneven pattern on the surface of the high grip member is not inclined with respect to the roller width direction (parallel to the axial direction of the pressure roller 120 or the like), vibration due to drive transmission (caused by the uneven pattern) However, the belt fixing device 10 of this embodiment may
According to No. 0, since the uneven pattern GP on the surface G4 of the high grip member G is inclined with respect to the roller width direction, such vibration is significantly reduced, and drive transmission is smoothly performed.

(B) Since the concavo-convex pattern GP on the surface G4 of the high gripping member G is line-symmetric with respect to the center line CL in the width direction of the pressure roller 120, it is caused by the inclination of the concavo-convex pattern GP. The thrust force (force acting in the width direction of the belt) is offset, and the fixing belt 110
Is obtained.

(C) Since the high grip member G is constituted by an elastic endless belt having an inner diameter smaller than the outer diameter of the end of the pressure roller 120 in a free state,
The high grip member G expands and contracts well with the end of the pressure roller 120, and a high grip portion that is in good condition along the end of the pressure roller 120 can be formed. Further, for example, when a tape-shaped high grip member is wound around and fixed to both ends of the pressure roller 120,
There is a possibility that the high grip member may be easily peeled off from the joint (see L in FIG. 7). However, according to the configuration of this embodiment, such a possibility is eliminated, and the mechanical reliability is improved.

(D) Since the high grip member G is made of cloth, the surface G4 of the high grip member G (see FIG. 4)
Are formed into fine irregularities by the thread (woven or knitted thread) 114 that forms the cloth, and the irregularities are almost uniformly spread on the surface of the high grip member G.
Therefore, vibration and speed fluctuation generated by drive transmission at both ends of the pressure roller 120 are extremely reduced,
As a result, smoother drive transmission is achieved. Also, since the irregularities are formed by the thread 114,
The projection is rounded. Therefore, stress concentration in the fixing belt 110 is reduced, and the fixing belt 110
Is improved in durability. Further, the strength (particularly, strength against shearing force) is excellent as compared with the case where the high grip member G is made of, for example, a synthetic resin film or 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. In the case where the high grip member G is made of cloth, even if the fiber (thread) 114 at the edge portion is cracked and broken, the break propagates. In addition, since only one fiber break occurs, the strength is excellent.

(E) Since the high grip member G is fixed to the end of the pressure roller 120 via the flexible adhesive layer 116, the following operation and effect can be further obtained. That is, in this type of fixing device, the pressure roller 120 is heated at the time of its operation and is heated to a high temperature (for example, 150 to
(Approximately 200 ° C.). If the adhesive layer fixing the high grip member G to the end of the pressure roller 120 is not flexible, the pressure roller 1
Due to the difference in thermal expansion between the high grip member 20 and the high grip member G, there is a possibility that the end portion of the pressure roller 120 is easily damaged or the high grip member G is easily peeled off from the pressure roller 120. On the other hand, according to the belt fixing device 100 of this embodiment, the pressure roller 12
Adhesive layer 11 fixing the high grip member G to the end of
6 has flexibility, the difference in thermal expansion between the pressure roller 120 and the high grip member G is absorbed by the adhesive layer 116. Therefore, the end of the pressure roller 120 is damaged, or the high grip member G is
This makes it less likely that the pressure roller 120 will be peeled off, and as a result, the durability of the pressure roller 120 will be further improved.

(F) Since the oil applying means 150 for applying the release oil to the surface of the fixing belt 110 is provided, the offset phenomenon hardly occurs. As previously mentioned,
If the release oil is applied to the surface of the fixing belt 110, the oil will enter the end N2 of the pressure contact portion between the fixing belt 110 and the pressure roller 120. 100, the pressure roller 12
The high grip member G is fixed to both ends of the pressure contact portion 0, and the high grip member G has oil absorbency. It will be absorbed by the grip member G.
Therefore, the amount of oil existing on the surfaces of both ends of the pressure roller 120, that is, the surface G4 of the high grip member 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). This makes it extremely difficult to produce), 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. (G) the high grip member G has oil permeability,
In addition, since the adhesive layer 116 has oil absorbency, the oil that has entered the end portion N2 of the press contact portion is also absorbed by the adhesive layer 116 via the high grip member G. Therefore, the amount of oil existing on the surface G4 at both ends of the pressure roller 120 is small, and as a result, the grip force at both ends of the press-contact portion is better secured, and the slip is more reliably prevented (at least significantly). This hardly occurs), and a more stable fixing operation is performed. (H) Since the high grip member G is made of a material having oil absorbency and oil flowability in the roller circumferential direction, even if the high grip member G becomes saturated with oil, The oil absorbed in the G at the press contact portion N2 due to the press contact force in a region other than the press contact portion N2 in the roller circumferential direction (FIG. 4).
(In the vertical direction in (a)).
Therefore, even if the high grip member G becomes saturated with oil, the amount of oil existing on the surfaces G4 of the both ends of the pressure roller 120 at the press contact portion N2 becomes small, and as a result, both ends of the press contact portion The grip force at N2 is ensured, and the above-mentioned slip is prevented (at least hardly to occur), so that a stable fixing operation is performed. (I) The outer diameter D2 of the high grip member G is
0, the outer diameter D1 of the surface layer 122a is larger than the outer diameter D1 at both ends N2 (see FIG. 2) of the pressure contact portion N between the fixing belt 110 and the pressure roller 120, as shown in FIG. The grip member G is pressed against the fixing belt 110 with a stronger pressing force. Therefore, the gripping force between the pressure roller 120 and the fixing belt 110 is further improved, and the slip is more reliably prevented (at least becomes more unlikely to occur), and as a result, a more stable fixing operation is performed. Becomes

<Second Embodiment> FIGS. 7 and 8 are views showing a main part of a second embodiment of a belt fixing device according to the present invention, and FIG. Partial perspective view,
8B is a developed front view of the high grip member G, and FIG. 8A is a sectional view taken along the line VIIIa-VIIIa in FIG. In these figures, the same or corresponding parts as in the first embodiment are denoted by the same reference numerals. The difference between this embodiment and the first embodiment is that FIG.
As shown in FIG. 7A, a tape-shaped high grip member G as shown in FIG. 7B is wound around the end of the pressure roller 120 along the circumferential direction thereof via an adhesive layer 116 to form an adhesive layer. This is at the point fixed at 116, and the other points remain unchanged. In this embodiment, FIGS. 7A and 8A
As shown in (1), the winding start end G1 and the end G2 of the tape-shaped high grip member G are wound and fixed so that they do not overlap. Therefore, the winding start end G1
A small gap L is formed between the end portion G2 and the end portion G2, and this gap L is made as small as possible (at least shorter than the circumferential length of the pressure contact portion N between the fixing belt 110 and the pressure roller 120). Is desirable. In addition, as shown in FIG. 8B, the winding start end G1 and the end G2 may be wound and fixed so as to overlap each other. Since the superimposed portion G3 becomes thicker, the superimposed portion G3 is pressed against the fixing belt 110 at other times.
There is a possibility that the speed of the fixing belt 110 on the driven side fluctuates, and when the overlapping portion G3 comes into pressure contact with the fixing belt 110, stress is concentrated on the fixing belt 110 at a portion opposed to the overlapping portion G3 and fixing is performed. This is not desirable because the durability of the belt 110 may be reduced. According to this embodiment, effects other than (c) obtained by the first embodiment can be obtained, and further, the following effects can be obtained. That is, since the high grip portions at both ends of the pressure roller 120 can be configured by simply winding and fixing the tape-shaped high grip members G to the both ends of the pressure roller 120, the production of the fixing belt (and thus the fixing Manufacturing).

<Third Embodiment> FIG. 9 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 pressure roller 120, (b) is a development view of the tape-shaped high grip member G. In FIG. 9, 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 not parallel to the axial direction of the pressure roller 120.
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, if the winding start end G1 and the end G2 of the tape-shaped high grip member G are not inclined, the gap L formed between the start end G1 and the end G2 is fixed. The fixing belt 11 on the driven side depends on when the belt 110 is in pressure contact with the belt 110 and at other times.
0 may fluctuate in speed. For example, if the gap L described above in the second embodiment is longer than the circumferential length of the pressure contact portion N between the fixing belt 110 and the pressure roller 120, the above-described speed fluctuation may occur. It grows. On the other hand, according to the third embodiment, since the winding start end G1 and the end G2 of the tape-shaped high grip member G are inclined to face each other, the driven-side fixing belt 110 is inclined. Speed fluctuation hardly occurs.

<Fourth Embodiment> FIG. 10 is a partial front view of a pressure roller 120 in a belt fixing device according to a fourth embodiment of the present invention, and FIG. 11 is a developed front view of a high grip member G. is there. In these figures, the same or corresponding parts as those in the first to third embodiments are denoted by the same reference numerals. This embodiment is different from the first to third embodiments in that the side edge G5 of the high grip member G is shifted in the circumferential direction, and there is no other difference. That is, the side edge G5 is in the roller width direction (FIG. 1).
(Right and left direction at 0). In this embodiment, the side edges G5 and G5 are shifted in the circumferential direction by forming the both side edges G5 and G5 in a gentle wave shape when viewed from the front. The high grip member G can be formed in a ring shape as in the first embodiment. According to this embodiment, in addition to the functions and effects obtained by the above embodiments, the following functions and effects can be obtained.

That is, if the side end portion G5 of the high grip member G is not displaced in the circumferential direction (has a linear shape orthogonal to the roller width direction (left and right direction in FIG. 10)), the pressure roller The portions 117 and 117 (see FIG. 6) of the fixing belt 110 pressed against the side 120 and pressed against the side edge G5 of the high grip member G are locally (annularly) worn or deformed. There is a possibility that the durability of 110 may be reduced. On the other hand, according to this embodiment, since the side edge G5 of the high grip member G is displaced in the circumferential direction, local wear or deformation of the fixing belt 110 is reduced (wear or the like is reduced by a shift width). Direction), and as a result, the durability of the fixing belt 110 is improved. This effect can be obtained even when the outer diameter D2 of the high grip member G is not configured to be larger than the outer diameter D1 of the surface layer 122a of the pressure roller 120, but the high grip member G has a stronger pressing force. If no measures are taken if the structure is pressed into contact with the fixing belt 110, the local portions of the portions 117 and 117 of the fixing belt 110 which are pressed against the side edge G5 of the high grip member G. In this embodiment, the side edge G5 of the high grip member G is displaced in the circumferential direction as described above, while the typical (annular) wear or deformation may be further promoted. Therefore, local wear or deformation of the fixing belt 110 is reduced, and as a result, the durability of the fixing belt 110 is improved. That is, the configuration in which the side edge G5 of the high grip member G is shifted in the circumferential direction is particularly effective when the high grip member G is configured to be pressed against the fixing belt 110 with a stronger pressing force.
Further, as a result of improving the durability of the fixing belt 110, the fixing belt 110 can be made thin, so that the fixing belt 110 can follow the unevenness according to the amount of the toner forming the image. Is improved, and the fixing strength or the uniformity of the fixing is improved. Furthermore, since the heat capacity of the fixing belt 110 becomes smaller, more rapid heating becomes possible.

<Fifth Embodiment> FIG. 12A is a view showing a main part of a fifth embodiment of the belt fixing device according to the present invention, and is a cross-sectional view showing an end of a fixing nip portion N. It is. In the figure, the same reference numerals are given to the same or corresponding parts as in the first to fourth embodiments. This embodiment differs from the first to fourth embodiments in the width direction of the high grip member G (in the left-right direction in FIG. 12A).
Is that the side edge G5 is chamfered (G6), and the other points remain the same. According to this embodiment, since the side edge portion G5 of the high grip member G is chamfered (G6), stress concentration on the fixing belt 110 by the end portion (G6) of the high grip member G is reduced, and as a result, The durability of the fixing belt 110 is further improved. Therefore, in the configuration in which the side edge G5 of the high grip member G is chamfered (G6), the outer diameter of the high grip member G is larger than the outer diameter of the surface layer 122a of the pressure roller 120. This is particularly effective when the high grip member G has a structure in which the high grip member G is pressed against the fixing belt 110 with a strong pressing force at both ends N2 of the pressing portion N between the fixing belt 110 and the pressure roller 120. FIG.
As shown in (b), in the first to fourth embodiments, the end G5 in the width direction of the high grip member G may not be chamfered. This is not desirable because stress may concentrate on the fixing belt 110 at the pressure contact portion with G5 and durability of the fixing belt 110 may be reduced.

<Sixth Embodiment> The feature of this embodiment is that the chamfered surface G6 is smoothed.
As means for smoothing the chamfered surface G6, means for coating the surface G6 with a fluororesin or a silicone-based resin, or, for example, smoothing the surface G6 while heating and melting it so that the surface 6 is inclined. Can be taken.
With such a configuration, since the chamfered surface G6 is smoothed, the durability of the fixing belt 110 is further improved.

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.

[0033]

According to the belt fixing device of the first aspect,
A stable fixing operation is performed. In addition, the drive transmission is performed smoothly.

[0034]

[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 a pressure roller 120, and FIG. 3B is a perspective view of the end.

FIG. 4A is a partially omitted front view of a pressure roller 120,
(B) and (c) are front views each showing an example of an uneven pattern.

5A and 5B show an end portion of the pressure roller 120, wherein FIG. 5A is an enlarged front view with a part omitted, and FIG. 5B is a cross-sectional view taken along line bb in FIG.

FIG. 6 is a sectional view of an end portion N2 of the press contact portion N according to the embodiment, and an operation explanatory diagram.

FIGS. 7A and 7B are views showing a main part of a belt fixing device according to a second embodiment of the present invention, wherein FIG. 7A is a partial perspective view of a pressure roller 120, and FIG. FIG.

8A and 8B are diagrams showing main parts of the embodiment, wherein FIG. 8A is a cross-sectional view taken along the line VIIIa-VIIIa in FIG. 7, and FIG. 8B is a cross-sectional view showing a state where a winding start end G1 and a terminal end G2 overlap.

9A and 9B are diagrams illustrating a main part of a belt fixing device according to a third embodiment of the present invention, wherein FIG. 9A is a partial front view of a pressure roller 120, and FIG. It is.

FIG. 10 is a front view of an end of a pressure roller 120 in a fourth embodiment of the belt fixing device according to the present invention.

FIG. 11 is a developed front view of the high grip member G in the embodiment.

FIG. 12A is a cross-sectional view illustrating an end portion of a fixing nip portion N, illustrating a main part of a belt fixing device according to a fifth embodiment of the present invention. (B) is sectional drawing which shows a comparative example.

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

FIG. 14 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 S Recording Material 100 Fixing Unit 110 Fixing Belt 120 Pressure Roller (Rotating Body) G High Grip Member GP Concavo-convex Pattern G4 Surface G5 Side Edge G6 Chamfered Surface N Pressure Contact N1 Center of Pressure Contact N2 End of Pressure Contact

Claims (1)

[Claims] 1. A recording apparatus comprising: 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 recording image on which a toner image is formed. A fixing member for passing the material through a central portion of a pressure contact portion between the fixing belt and the rotating body to heat and melt the toner image and to fix the toner image on a recording material; , A high grip member is provided along, and the uneven pattern on the surface of the high grip member is inclined with respect to the width direction of the rotating body.