JPH07129014A - Thermal fixing device - Google Patents

Abstract

PURPOSE:To provide a thermal fixing device capable of preventing the occurrence of reverse curling even in the case the diameter of a fixing roller is made smaller, also, preventing the defective image with reference to a half-tone image, and also surely preventing the waving of a small-sized transfer material. CONSTITUTION:The outside diameter shape of the fixing roller 9 is formed like a wave repeating that the outside diameter of the roller 9 is made larger as it comes from the central part to nearer the end part and the outside diameter is gradually made smaller thereafter. By forming the fixing roller to a shape like a wave in such a way, a pair of forces (a) for partially pulling the transfer material outwards in a transfer material width direction and a pair of forces (b) exerting in a direction of eliminating the aforesaid force are alternately added, then, the stress is periodically released by the influence of the wavy shape, so that the stress is not centralized in the end part and the occurrence of waving is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device provided in an image forming apparatus adopting an electrophotographic system, an electrostatic recording system or the like, and more specifically, a heating rotary member and a heating member arranged in pressure contact with each other. The present invention relates to a heating and fixing device including a pressure rotating body.

[0002]

2. Description of the Related Art Conventionally, in a fixing device provided in an image forming apparatus which employs an electrophotographic system, an electrostatic recording system, etc., a transfer material carrying an unfixed toner image is heated for pressing and rotating each other. By passing through a nip portion formed by a fixing roller that is a rotating body and a pressure roller that is a rotating body for pressure application, a permanent image is fixed on the transfer material,
A so-called heating roller fixing device is widely used. In such a heating roller fixing device, the outer diameter shape of at least one of the fixing roller and the pressure roller is set such that the outer diameters of both ends in the longitudinal direction thereof are maximum and the outer diameter of the central portion is minimum. It has a so-called inverted crown shape, and wrinkles are prevented by pulling both ends of the transfer material when passing through the nip portion. In such a configuration, the transfer material is forcibly stretched in the longitudinal direction of the fixing roller or the like, and its distortion extends to both end portions of the transfer material having a weak stiffness, and as a result, both end portions of the transfer material are wavy. In some cases, so-called "waviness" occurs, and the image quality is impaired during double-sided printing.

In view of this, in Japanese Patent Laid-Open No. 2-262684, the maximum outer diameter portion of a pressure roller having an inverted crown shape is located inside both end portions of the pressure roller, and the transfer material corresponding to this portion is slightly different. There is disclosed a technique of forming streaks to impart rigidity to both ends of a transfer material to prevent wrinkles while preventing wrinkles.

[0004]

However, according to the study by the present inventors, it has been found that the following problems occur even in the above-mentioned improvement proposal.

1. In order to reduce the size of the image forming apparatus, when the diameter of the fixing roller is reduced, the mechanical strength of the fixing roller decreases, and when the fixing roller is pressed against the pressure roller, it bends in an arc shape. This causes more pressure and heat to be applied to both ends of the transfer material, the fibers of the transfer material are greatly stretched, and the output transfer material is curved along the non-printing surface, so-called reverse curl occurs. It becomes easier. This reverse curl cannot be completely removed even by the reverse curl correcting means in an image forming apparatus such as a personal computer printer which is often used for face-down paper ejection, and it can be said that the stacking property is good. In addition, in the face-up paper ejection, the ejected transfer material is curled up and the image quality is remarkably deteriorated.

2. The above improvement proposal states that the waviness is prevented by adding a slight streak to the end of the transfer material, but this streak is almost unknown in a normal character image, but when halftone is printed, the streak is not visible. Was sometimes recognized.

3. The above-mentioned improvement proposal can exert the effect against the waviness on the maximum size transfer material, but cannot obtain the effect on the small size transfer material having a narrow width.

The present invention solves the above problems, does not cause reverse curl even when the fixing roller has a small diameter, does not cause image defects even in a halftone image, and is reliable even with a small-sized transfer material. It is an object of the present invention to provide a heat fixing device capable of preventing waviness.

[0009]

According to the first invention of the present application,
The purpose is to pass the transfer material on which the unfixed image is formed through a nip region formed between the heating rotator maintained at a predetermined temperature and the pressure rotator pressed against the heating rotator. Thus, in the heat fixing device for fixing the unfixed image on the transfer material as a permanent image, the outer diameter shape of at least one of the heating rotator and the pressure rotator gradually increases in the transfer material passage area. This is achieved by having a wavy shape that becomes larger and then gradually decreases in outer diameter.

Further, according to the second invention of the present application, the above object is to provide a heating rotator in which the transfer material having an unfixed image formed thereon is maintained at a predetermined temperature, and a rotator for pressurizing contact with the rotator. In the heat fixing device for fixing the unfixed image as a permanent image on the transfer material by passing through the nip region formed between the heating rotating body and the pressing rotating body, It has a wavy shape in which the outer diameter gradually increases and then gradually decreases in the transfer material passage area.The heating rotor and the pressing rotor have opposite wave phases. It is achieved by becoming.

Further, according to the third invention of the present application, the above object is to provide a heating rotator in which a transfer material on which an unfixed image is formed is maintained at a predetermined temperature, and a rotator for pressurizing contact with the rotator. In the heat fixing device for fixing the unfixed image as a permanent image on the transfer material by passing through the nip region formed between the heat roller and the heating rotary member, the outer diameter shape change rate is 0.02. It has the above parts, and the core metal recess is R
It is formed with a smooth curve of 20 or more or a change angle of 160 degrees or more, and is achieved by using a heat shrinkable PFA tube for the surface release layer.

Further, according to the fourth invention of the present application, the above object is to provide a heating rotator in which a transfer material on which an unfixed image is formed is maintained at a predetermined temperature, and a rotator for pressurizing contact with the heating rotator. In the heat fixing device for fixing the unfixed image as a permanent image on the transfer material by passing through the nip region formed between the heat roller and the heating rotary member, the outer diameter shape change rate is 0.02. It has the above-mentioned portions, and is achieved by transfer coating a fluororesin dispersion on the surface release layer.

[0013]

According to the first invention of the present application, by forming at least one of the heating rotator and the pressure rotator in the above-described shape, the stress in the width direction of the transfer material is dispersed in a short cycle, Corresponding to multiple transfer material sizes, preventing waving of the transfer material. Further, the transfer material is deformed at a short cycle in the width direction so as to give the transfer material a rigidity, and the curl is reduced without applying a deforming force in a specific direction to the entire transfer material.

Further, according to the second invention of the present application, by constructing the shapes of the heating rotator and the pressure rotator as described above, the force for making the transfer material follow the shape of the fixing roller acts strongly. The action described in the first aspect of the invention works more reliably and prevents waviness and wrinkles. In addition, the nip width formed by the heating rotator and the pressure rotator becomes uniform in the transfer material width direction, and the fixing property in the transfer material width direction becomes uniform. It is possible to improve the property and lower the control temperature of the fixing roller, so that not only curling and waviness are reduced, but also the power consumption of the heater of the heating rotator is reduced.

Further, according to the third invention of the present application, by using a PFA heat-shrinkable tube as the surface release layer of the heating rotor, the surface layer has a predetermined thickness and surface roughness in advance.
It eliminates the need for surface polishing and does not cause uneven gloss in images such as solid black. Moreover, the change angle θ of the outer diameter shape of the core metal
Is 160 ° or more, or R (diameter) when concave outer diameter is 2
By setting it to 0 or more, the PFA tube gradually melts and shrinks from the central part of the heating rotor, and the air between the PFA tube and the core metal escapes to the end of the heating rotor, and the PFA heat-shrinkable tube does not generate bubbles. Can be welded, and the PFA tube can be completely adhered regardless of the uneven shape of the core metal of the heating rotor.

Further, according to the fourth aspect of the present invention, the heating rotary member is provided with a portion having an outer diameter shape change rate of 0.02 or more, and the surface release layer is transfer coated with a fluororesin dispersion. It becomes possible to eliminate the need for surface polishing, to obtain a uniform film thickness and surface roughness in the surface release layer of the heating rotator having a complicated shape, and to prevent uneven glossiness in a solid black image or the like.

[0017]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Embodiment 1> First, Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram of an image forming apparatus according to the present invention.

In FIG. 1, 1 is a photosensitive drum, and O
A photosensitive material such as PC, amorphous Se, or amorphous Si is formed on a cylindrical substrate such as aluminum or nickel. The photosensitive drum 1 is rotationally driven in the direction of the arrow, and first, the surface thereof is a charging roller 2 as a charging device.
Are uniformly charged by. Next, turn on according to the image information
Scanning exposure is performed by the laser beam 3 controlled to be ON / OFF, and an electrostatic latent image is formed. This electrostatic latent image is developed and visualized by the developing device 4. As a developing method, a jumping developing method, a two-component developing method, an FEED developing method, or the like is used, and image exposure and reversal developing are often used in combination.

The visualized toner image is transferred onto the transfer material P conveyed at a predetermined timing by the transfer roller 5 as a transfer device. The transfer material P on which the toner image has been transferred is conveyed to the fixing device 6 and fixed as a permanent image, and is then discharged face-down onto the discharge tray 7. On the other hand, transfer residual toner remaining on the photosensitive drum 1 is removed by the cleaning device 8 from the photosensitive drum 1.
It is removed from the surface.

FIG. 2 shows the structure of the heat fixing device 6 according to the present invention. In FIG. 2, 9 is a fixing roller, and 10 is a pressure roller, each rotating in the direction of the arrow. In this embodiment, the maximum transfer material size that can be passed is LTR size (width 21
6 mm, length 279 mm), and the fixing roller 9
Is PFA12 on the surface layer of the hollow core metal 11 made of aluminum having a thickness of 3 mm and an inner diameter of 24 mm and excellent in heat resistance.
Is coated with a thickness of 30 μm, and the hollow core metal 11
A halogen heater 13 for heating the fixing roller 9 is provided inside. On the other hand, the pressure roller 10 has a wall thickness of 10 mm on the outer periphery of a core metal 14 made of iron and having an outer diameter of 10 mm.
A silicone rubber 15 having an excellent releasability of mm is formed. The pressure roller 10 has a hardness of 50 ° (A
SKER-C 500 g when overloaded). The fixing roller 9 and the pressure roller 10 are pressed against each other by springs (not shown) at both ends in the longitudinal direction. A thermistor 16 for detecting the surface temperature of the fixing roller 9 is in contact with the fixing roller 9, and the surface temperature information of the fixing roller 9 detected by the thermistor 16 is A / D converter ( CPU (not shown)
(Not shown), and based on this, the CPU (not shown) controls ON / OFF of the halogen heater 13 via an AC driver (not shown), so that the surface temperature of the fixing roller 9 is Is controlled to a predetermined value.

Further, the shape of the fixing roller provided in the heat fixing device according to the present invention will be described in detail with reference to FIG. The fixing roller 9 has a wavy shape in which the outer diameter gradually increases from the center toward the end and then gradually decreases. In this embodiment, it has a wavy outer diameter shape that is symmetrical with respect to the central portion a in the transfer material passage area. FIG. 4 shows a graph of the outer diameter shape of the fixing roller 9.

By imparting such a wavy shape to the fixing roller, a pair of forces a for partially pulling the transfer material outward in the width direction of the transfer material and a direction for canceling the force as shown in FIG. A pair of forces b that act on are alternately applied. As a result, in the conventional inverted crown shape, the stress concentrates on the end portion of the transfer material, whereas in the present embodiment, the stress is periodically released due to the influence of the wavy shape, so the stress concentrates on the end portion. Rippling can be prevented without doing. In addition, a pair of forces b tending to bring the transfer material that causes wrinkles toward the center is periodically applied to the transfer material, but its width is short and it can be held up by the stiffness of the transfer material, leading to wrinkles. There is no.

Due to the above-described effects, in the present embodiment, concentration of stress on the end portions can be prevented without depending on the size of the transfer material. Further, in the present embodiment, as shown in FIG. 5, since the transfer material is curved in the width direction in a wave shape with a short cycle, the transfer material is not strongly curled in a specific direction, and deformation in a region with a small width is prevented. Therefore, due to the stiffness of the transfer material, there is almost no curling due to the influence of the shape of the fixing roller.

In order to obtain the above action and effect, it is preferable that the period of the wavy shape is short, but in order to prevent wrinkles and almost eliminate the transfer material size dependency, the period is 100 m.
m or less, preferably 70 mm or less, and the wave depth is 5
The inventors of the present invention have found that 0 to 300 μm is preferable. Further, the shape of the wavy portion was a smooth curve such as an arc shape, a parabola shape, or a hyperbola shape, and there was almost no effect on the image.

Further, as the outer diameter shape of the fixing roller, it is more sure that the center line b (corresponding to the integral value of the waveform) connecting the wavy shapes as shown in FIG. 4 is straight or reverse crown shape. The inventors of the present invention have found that it is preferable for preventing wrinkling of the material.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIG. The heat fixing device of the present embodiment is characterized in that the fixing roller has the same outer diameter shape as that of the first embodiment, and that foam sponge is used for the elastic layer of the pressure roller.

FIG. 6 is a sectional view of the heat fixing device 60 of this embodiment. The fixing roller 9 has the same configuration and shape as those in the first embodiment, and thus the description thereof will be omitted. Similarly, the same components as those in the first embodiment are designated by the same reference numerals as those in FIG.

As in the present invention, when the outer diameter of the fixing roller has a wavy shape in which the outer diameter gradually increases from the central portion and then decreases unlike the reverse crown shape, the rate of change of the outer diameter of the fixing roller is If it is increased, the elastic layer of the pressure roller does not sufficiently follow the change of the shape of the fixing roller, and the nip width becomes uneven, and uneven gloss may occur in a solid black image such as thin paper. I understood.

Therefore, in this embodiment, the pressure roller 61 has a silicone rubber sponge layer 612 on a core metal 611 made of SUS, iron or the like having an outer diameter of 10 mm, and the outer diameter shape gradually increases from the central portion to the end portion. After polishing to an inverted crown shape with a large outer diameter or a straight shape with a constant outer diameter to a thickness of 9.5 mm, add 0.5
A silicone rubber layer 613 having a thickness of mm is coated, and the pressure roller has an outer diameter of 30 mm and a hardness of 45 ° (ASKER-
C) was finished.

By using the heat-fixing device having such a structure, the function and effect described in the first embodiment can be obtained, and not only waviness and wrinkles can be prevented, but also the pressure roller uses the sponge layer as the elastic layer. Since the sponge layer is soft and can easily follow minute shape changes, even if the outer diameter shape of the fixing roller changes intricately as in the present invention, it is possible to follow the shape and apply pressure. As a result, the nip width becomes relatively uniform, and the effect of eliminating solid black gloss unevenness that tends to stand out on thin paper or the like can be obtained.

<Third Embodiment> Next, a third embodiment of the present invention will be described with reference to FIGS. The heat fixing device of the present embodiment is characterized in that both the fixing roller and the pressure roller have the wavy shape as in the above embodiment, and the phases of the wavy shape of the fixing roller and the pressure roller are opposite to each other. There is.

FIG. 7 is a sectional view of the heat fixing device 70 of this embodiment. Members having the same configurations as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. This embodiment is characterized by the relationship between the outer diameter shapes of the fixing roller and the pressure roller and the configuration of the pressure roller, which will be described. The pressure roller 71 is a cored bar 71 made of SUS, iron or the like having an outer diameter of 10 mm.
1, a silicone rubber layer 712 having a thickness of about 10 mm is provided, and a PFA tube layer 713 having a thickness of 50 μm is coated and adhered thereon, the outer diameter thereof is 30 mm, and the hardness thereof is 45 °.
Is. Next, the relationship between the outer diameter shapes of the fixing roller and the pressure roller will be described with reference to FIG. The outer diameter shape of the fixing roller 9 has a wavy shape in which the outer diameter gradually increases from the transfer material passage area central portion a toward the end portion, and then gradually decreases, while Pressure roller 7
No. 1 has a wavy shape having a phase opposite to that of the fixing roller 9 as the outer diameter gradually decreases from the central portion a of the transfer material passing area toward the end and then gradually increases. FIG. 9 shows an outer diameter shape graph of the fixing roller and the pressure roller.

The function and effect of this embodiment are particularly effective for a pressure roller using a PFA tube having excellent surface layer releasability and durability. When a PFA tube is used for the surface layer of the pressure roller, the slipperiness of the surface layer of the pressure roller is improved, so that the gripping force of the transfer material is weakened and it becomes difficult to obtain the effect described in the first embodiment. Further, since the surface layer of the pressure roller becomes hard, it becomes difficult for the pressing force to follow the complicated shape of the fixing roller, and the nonuniformity of the fixing property increases. However, by constructing the shapes of the fixing roller and the pressure roller in this way, the force for making the transfer material follow the shape of the fixing roller works strongly, so that the action and effect described in the first embodiment can be obtained more effectively. It is possible to prevent waviness and wrinkles. Furthermore, since the nip width formed by the fixing roller and the pressure roller is likely to be uniform in the width direction of the transfer material, and the fixing property in the width direction of the transfer material is uniform, conventionally, the fixing property in the central portion where the nip width is small is reduced. Compared to the case where the control temperature of the fixing roller is determined to be good, the control temperature of the fixing roller can be lowered, curling and waviness are reduced, and the power consumption of the fixing heater is also reduced. Is possible. The explanation of the function and effect of this embodiment is that the surface of the pressure roller is PF.
Although the system using the A tube has been described, it is needless to say that the same action and effect can be obtained also in the system having no PFA tube on the surface layer of the pressure roller.

<Fourth Embodiment> Next, a fourth embodiment of the present invention will be described with reference to FIGS. The purpose of the present embodiment is to provide an optimum fixing roller structure for obtaining a fixing roller shape having a large outer diameter change rate as in the above-described embodiments. The contents of this embodiment will be described below with reference to the heating roller shown in FIG.

The fixing roller 101 is cut into a desired shape by controlling the core metal NC made of Al, iron or the like, and then the surface of the core metal 1011 is subjected to surface treatment such as blasting or alumite treatment, and then washed or washed. Only the treatment is performed, then the primer 1012 is applied, and 20 to 50 μm is applied.
m PFA heat shrink tube 1013 is coated to
And the PFA heat-shrinkable tube 1013 is welded onto the cored bar 1011. After that, the tube end can be cut into a predetermined size to obtain the fixing roller 101.

In this way, the PFA heat shrink tube is used as the release layer on the surface of the fixing roller, and by heating it above the melting point of PFA, the PFA tube gradually melts and shrinks from the center of the fixing roller, and the core of the PFA tube and core. The air between the gold can escape to the end of the fixing roller (when the heating temperature is low, the shrinkage is insufficient and the removal of bubbles is incomplete). As a result, regardless of the uneven shape of the fixing roller core metal 1011, P
Air bubbles do not occur inside the FA tube, and the PFA tube can be completely bonded to the core metal 1011.

Further, PFA is used as a release layer on the surface of the fixing roller.
Since a heat-shrinkable tube has a certain film thickness and surface roughness in advance, there is no need for surface polishing, and PFA powder is electrostatically coated as in the past, or PTFE, PFA
Compared to a fixing roller that was spray-coated with a depth version and then polished, unevenness in the coating due to unevenness of the outer diameter of the fixing roller and uneven polishing during polishing do not occur, and the film thickness and surface roughness of the release layer Can be made uniform, so that uneven gloss does not occur in an image such as solid black.

In this embodiment, the function and effect are described with the corrugated fixing roller. For example, as shown in FIG. 11, the outer diameter gradually increases from the central portion to the end portion.
Alternatively, a fixing roller core metal 1111 (a part corresponding to the end of the maximum size of the transfer material has a small outer diameter is formed by a fixing roller having a constant outer diameter from the central portion to the end, and the outer diameter sharply decreases at the end. Similarly, as shown in FIG. 12, the outer diameter gradually increases from the central portion to the end portion, or the fixing roller having a constant outer diameter from the central portion to the end portion abruptly increases the outer diameter on the way to the end portion. The diameter of the fixing roller core 1211 is such that the diameter becomes smaller, then the outer diameter becomes larger again, and finally the outer diameter becomes sharply smaller again (the outer diameter of the portion corresponding to the end of the maximum size of the transfer material and the smaller size is By fusing the PFA heat-shrinkable tubes (1112, 1212) on the (thinning), the fixing rollers 111, 121 with uniform film thickness can be obtained by the same effect.

The application of the PFA heat-shrinkable tube is superior to other fluororesin coating methods.
According to the study by the present inventor, it was found that the rate of change in outer diameter of the fixing roller (slope: (D1-D2) / L in FIG. 11) has a portion of 0.02 mm or more per 1 mm in the width direction. On the other hand, as described above, when the PFA heat-shrinkable tube is applied and the shape of the outer diameter changes suddenly, the air inside may not escape and bubbles may occur. In particular, this phenomenon is likely to occur in a concave portion that transitions from a portion having a small outer diameter shape to a portion having a large outer diameter shape, and there is an appropriate value for this as well. According to the study of the present inventors, as shown in FIG.
It has been found that the PFA heat-shrinkable tube 1312 can be welded without generating bubbles when the change angle θ of the outer diameter shape of 311 is 160 ° or more or the R (diameter) in the concave outer diameter shape is 20 or more.

<Fifth Embodiment> Next, a fifth embodiment of the present invention will be described with reference to FIG. The purpose of this embodiment is to provide an optimum fixing roller configuration for obtaining the fixing roller shape suggested in the above-mentioned embodiments and the conventional example. The contents of this embodiment will be described below with reference to the fixing roller shown in FIG.

The fixing roller 141 is cut into a desired shape by controlling the core metal NC made of Al, iron or the like, and then the surface of the core metal 1411 is subjected to surface treatment such as blasting or alumite treatment, followed by cleaning or cleaning treatment. Do only
After that, a primer 1412 is applied, and a PFA (or PTFE or PFA / PTFE mixed type) dispersion 1414 is applied to 10 to 30 μm as shown in FIG.
Can be applied by a roll coater 151 having a shape following the shape of the fixing roller core metal 1411 and heated and baked at the melting point of PFA or higher to obtain the fixing roller 141.

As described above, the PFA dispersion is applied by a transfer method using a roll coater having a shape that follows the shape of the fixing roller core metal 1411 so that the PFA dispersion is applied with a uniform film thickness following the uneven shape of the core metal. Further, a constant pressure is applied to the PFA dispersion layer by the roll coater at the time of coating, the effect of smoothing the surface is produced, and the need for polishing is eliminated.
As a result, as in the above-described embodiment, the film thickness and surface roughness of the surface release layer can be made uniform regardless of the unevenness of the outer diameter of the fixing roller, so that uneven glossiness may occur in an image such as solid black. Lost.

The coating method of this embodiment is superior to other general fluororesin coating methods when the outer diameter change rate of the fixing roller is 0.02 or more, as in the above embodiment. Further, this embodiment has an advantage that there is no concern that bubbles are generated unlike the PFA heat shrink tube specification.

[0045]

As described above, according to the present invention,
The outer diameter shape of at least one of the heating rotator and the pressure rotator in the heat fixing device is a wavy shape in which the outer diameter gradually increases in the transfer passage area and then gradually decreases. As a result, it is possible to effectively prevent wavy, curl, and wrinkle of the transfer material that occurs when passing through the heat fixing device. Further, by using a PFA heat-shrinkable tube or a PFA dispersion coated by a roll coater on the surface release layer of the heating roller having a portion having a large outer diameter change rate like the above shape,
It is possible to obtain a heat fixing roller in which the surface release layer has a uniform thickness and surface roughness.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a heat fixing device in Embodiment 1 of the present invention.

FIG. 3 is a diagram illustrating a shape of a fixing roller according to the first exemplary embodiment of the present invention.

FIG. 4 is a diagram illustrating outer diameter shapes of a fixing roller and a pressure roller according to the first exemplary embodiment of the present invention.

FIG. 5 is a diagram showing a force applied to a transfer material from a fixing roller in Embodiment 1 of the present invention.

FIG. 6 is a configuration diagram of a heat fixing device according to a second embodiment of the present invention.

FIG. 7 is a configuration diagram of a heat fixing device according to a third embodiment of the present invention.

FIG. 8 is a diagram showing shapes of a fixing roller and a pressure roller according to a third exemplary embodiment of the present invention.

FIG. 9 is a diagram illustrating outer diameter shapes of a fixing roller and a pressure roller according to a third exemplary embodiment of the present invention.

FIG. 10 is a diagram showing a shape of a fixing roller in Embodiment 4 of the present invention.

FIG. 11 is a diagram showing the shape of a fixing roller in Embodiment 4 of the present invention.

FIG. 12 is a diagram illustrating a shape of a fixing roller according to a fourth exemplary embodiment of the present invention.

FIG. 13 is a diagram illustrating a shape of a fixing roller according to a fourth exemplary embodiment of the present invention.

FIG. 14 is a diagram showing a shape of a fixing roller and a PFA application method according to a fifth embodiment of the present invention.

[Explanation of symbols]

 9 Fixing Roller (Rotating Body for Heating) 10 Pressure Roller (Rotating Body for Pressure) 612 Silicone Sponge Layer (Elastic Layer) 1011 Core Bar 1013 Heat Shrinkable PFA Tube P Transfer Material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoru Izawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (6)

[Claims] 1. A transfer material on which an unfixed image is formed is passed through a nip region formed between a heating rotator maintained at a predetermined temperature and a pressure rotator pressed against the heating rotator. As a result, in the heat fixing device for fixing the unfixed image on the transfer material as a permanent image, the outer diameter shape of at least one of the heating rotator and the pressure rotator gradually becomes the outer diameter in the transfer material passage area. The heat-fixing device has a wavy shape in which the outer diameter gradually increases and then gradually decreases. 2. The heating and fixing device according to claim 1, wherein the corrugated shape of the heating rotator or the pressure rotator is formed in a cycle of 100 mm or less. 3. The heat fixing device according to claim 1, wherein the pressing rotary body has an elastic layer, and the elastic layer is made of a foam elastic body. 4. A transfer material on which an unfixed image is formed is passed through a nip area formed between a heating rotator maintained at a predetermined temperature and a pressure rotator pressed against the heating rotator. As a result, in the heat fixing device for fixing the unfixed image on the transfer material as a permanent image, the outer diameter shape of the heating rotating body and the pressing rotating body is gradually increased in the transfer material passing region. The heating and fixing device is characterized in that it has a wavy shape in which the outer diameter is gradually reduced, and then the heating rotating member and the pressing rotating member have opposite wave phases. 5. A transfer material on which an unfixed image is formed is passed through a nip region formed between a heating rotator maintained at a predetermined temperature and a pressure rotator pressed against the heating rotator. As a result, in the heat fixing device for fixing the unfixed image on the transfer material as a permanent image, the heating rotator has a portion having an outer diameter shape change rate of 0.02 or more, and the core metal concave portion is R20. A heat fixing device, which is formed with the above smooth curve or a change angle of 160 degrees or more, and uses a heat shrinkable PFA tube for the surface release layer. 6. A transfer material on which an unfixed image is formed is passed through a nip region formed between a heating rotator maintained at a predetermined temperature and a pressure rotator pressed against the heating rotator. As a result, in the heat fixing device for fixing the unfixed image on the transfer material as a permanent image, the heating rotator has a portion having an outer diameter shape change rate of 0.02 or more, and has a surface release layer. Is a heat fixing device characterized by transfer coating of fluororesin dispersion.