JPH103227A - Image heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably carry film by constituting the device so that air retained in a cavity inside a pressure roller may be ventilated without being hermetically sealed with respect to outside air. SOLUTION: A rubber layer 11a is formed of rubber material having heat resistance such as silicone rubber, and plural cavity parts 11e for releasing heat are provided in a longitudinal direction inside the layer 11a. Furthermore, film carrying parts 11f composed of heat resistant material having higher friction coefficient than a mold-released layer 11b are concentrically and integrally provided at both ends of the layer 11a. The layer 11a and the carrying part 11f are disposed by forming a gap 11g to such an extent that the cavity part 11e is not hermetically sealed even when the air is heated and thermally expanded. Since the friction coefficient of the carrying part 11f is high, the friction coefficient between the outer peripheral surface of fixing film 14 and the carrying part 11f is made high. By such constitution, the outside diameter of the layer 11a is not changed even when the air inside the cavity part 11e is thermally expanded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image heating apparatus having a heating element (thermal heater) and a rotating element, and applying thermal energy of the heating element to a material to be heated via the rotating element.

[0002]

2. Description of the Related Art The above-mentioned heating apparatus has been proposed in, for example, JP-A-63-313182, JP-A-2-15778, JP-A-4-44075-44083 and the like. Image fixing device in image forming apparatus such as printer, laser beam printer, facsimile, micro film reader printer, image display (display) device, recorder, etc., ie, electrophotography, electrostatic recording,
The surface of a recording material (electrofax sheet, electrostatic recording sheet, transfer material sheet, printing paper, etc.) using a developer (toner) composed of a heat-meltable resin by an appropriate image forming process means such as magnetic recording. An unfixed toner image corresponding to the target image information is formed and supported by a direct method or an indirect (transfer) method, and the toner image is heated and fixed as a permanently fixed image on a recording material surface carrying the image. It can be used as an image heat fixing device.

[0003] Further, for example, it can be used as an apparatus for heating a recording material carrying an image to improve the surface properties such as gloss, or an apparatus for assuming a deposition.

[0004] A heating device of a film heating type can use a heating element having a low heat capacity as a heating element. By using a thin film as a film, a heating device of a conventional type such as a heat roller type can be used. It has advantages such as saving power and shortening the wait time (quick start).

FIGS. 7 and 8 each show a schematic structure of an example of a film heating type heating apparatus using an endless belt-like film as a heat resistant film. The heating devices shown in FIGS. 7 and 8 are both applied to an image heating and fixing device.

In the heating apparatus shown in FIG. 7, reference numeral 14 denotes an endless belt-like thin heat-resistant film, which comprises a driving roller 5, a driven roller 6 also serving as a tension roller, and a heating element 12, which are disposed substantially in parallel with each other. Is suspended between the three members. Reference numeral 1 denotes a pressure roller that forms a pressure contact nip portion (fixing nip portion) N with a film interposed between the heating member 12 and the heating member 12. The heating element 12 is a ceramic heater having a low heat capacity as a whole, and is held by a heater holding member 13 made of a heat insulating material. The heater holding member 13 is attached and held to a reinforcing member (stay) 16.

When the drive roller 5 is driven to rotate clockwise in the figure by the drive source M, an endless belt-shaped heat-resistant film (hereinafter simply referred to as a film or a fixing film) 14 has an inner surface facing the heater 12. The pressure roller 1 is driven to rotate in accordance with the rotation of the film.

In a state where the film 14 is driven to rotate by the driving roller 5 and the heating element 12 is heated to a predetermined temperature by energization, the unfixed toner image 20 is removed from the image forming unit (not shown). When a recording material 19 formed and supported as a heated material is introduced between the film 14 in the pressure nip N and the pressure roller 1, the recording material 19 comes into close contact with the outer surface of the film 14 which rotates endlessly. It passes through the press-contact nip N in an overlapping state together with 14.

In the process of passing through the pressure nip, the heating element 1
2 is applied to the recording material 19 via the film 14, the unfixed toner image 20 on the recording material 19 is heated and fused, and the recording material 19 is further pressed into the pressure nip N
And is separated from the surface of the film 14 and discharged.

A driving roller 5 is provided inside an endless belt-like film 14 like the heating device shown in FIG. 7, and the film is driven to rotate in a tensioned state, and the pressing roller 1 as a pressing member is driven to rotate. The heating device of the method for causing the film to be driven is hereinafter referred to as a “film drive type” heating device.

In the heating apparatus shown in FIG. 8, a heat-resistant film 14 in the form of an endless belt is loosely fitted to the outside of the heating body 12 without being stretched between the stretching members, and is heated. 12 with the film 14 interposed therebetween.
1 is formed to form a press-contact nip portion N.

By rotating the pressure roller 11 in a counterclockwise direction A in the figure by a driving source M, the film 14 is heated by the frictional force between the rotating pressure roller 11 and the film 14, and the inner surface thereof is heated. It is configured to be driven to rotate clockwise B while closely sliding on the surface of the body 12.

When the film 14 is driven to rotate by the pressure roller 11 and the heating element 12 is heated to a predetermined temperature by energization, the unfixed toner image 20 Is introduced between the film 14 in the press-contact nip N and the pressure roller 11 so that the heating device is the same as the heating device in FIG. 7 described above. Then, a heat fusion fixing process of the unfixed toner image 20 on the recording material 19 is performed.

An apparatus of a type in which the pressure roller 11 is driven to rotate the film 14 like the heating apparatus of FIG. 8 is hereinafter referred to as a "pressure roller driving type" heating apparatus.

In the heating device of the pressure roller drive system, the heating element 12, the film 14, and the pressure roller 11 are equal to or larger than the width of the recording material 19 having the maximum width that can be passed through the heating device. It has a longitudinal width.

When the pressure roller 11 obtains a driving force and rotates in the direction A, the recording material 19 sandwiched between the pressure roller 11 and the film 14 causes the frictional force of the outer peripheral surface of the pressure roller 11 to cause the recording material 19 to rotate.
Conveyed in the direction. At this time, the frictional force f1 of the surface of the recording material 19 acts on the film 14 in a range within the pass area of the recording material 19, and the film 14 is in a range where the pressure roller 11 and the film 14 directly contact outside the pass area of the recording material 19. , A frictional force f2 on the surface of the pressure roller 11 acts.

Accordingly, the film 14 is driven to rotate in the B direction by the film transport force F1 due to the resultant force of the friction force f1 and the friction force f2.

At this time, against the rotation of the film 14,
Since the frictional force f3 acts between the heating element 12 and the inner surface of the film 14, the film transport force F1 is increased by the frictional force f3 to stably rotate the film 14 without slipping between the recording material 19 and the recording material 19. Need to be bigger. Here, the slip between the film 14 and the recording material 19 causes disturbance of the fixed image and generation of wrinkles on the recording material.

The outer peripheral surfaces of the pressure roller 11 and the film 14 are provided with a surface layer of PF to prevent unfixed toner or paper powder conveyed by the recording material 19 from adhering to the surface.
It is formed of a material having good releasability, such as a fluorine-based material such as A or FEP. Since the friction coefficient between materials having good releasability is generally low, the frictional force f1 of the pressure roller 11 for rotating the film 14 cannot be increased.

Therefore, conventionally, in order to reduce the frictional force f3, the friction between the heating body 12 and the film 14 is reduced,
The surface of the heating body 12 is coated with a low friction layer or grease.

The heating device of the film drive system (FIG. 7) and the heating device of the pressure roller drive system (FIG. 8) described above use the latter pressure roller drive system as compared with the former film drive system. The device can reduce the number of drive rollers, which makes it possible to reduce the size and cost of the device.In addition, the moving force of the film to one side or the other in the rotation axis direction of the film during the rotation process is small, and the film This has the advantage that the control means can be simplified.

In this pressure roller driving type apparatus, as described above, in order for the film 14 to be stably driven without slipping, the film transport force F1 due to the resultant force of the friction force f1 and the friction force f2 acting on the film 14 is used. More frictional force f
3, the heating element 12 and the film 14
In order to reduce friction during the heating, the surface of the heating body 12 is coated with a low friction layer or grease is applied. However, there were the following disadvantages.

The coating or grease applied to the heating element 12 lowers the friction coefficient of the surface of the heating element at first, but has no durability, so the frictional force f3 between the heating element 12 and the film 14 is low.
It is difficult to lower stably.

As described above, the frictional force f2 between the film 14 and the pressure roller 11 cannot be increased.

The frictional force f1 between the film 14 and the recording material 19
Is determined by the friction coefficient between the film 14 and the recording material 19 as the material to be heated. However, when a recording material having a low friction coefficient such as an OHP film is used, the frictional force f1 decreases.

Therefore, in order to secure the transport force F1 of the film 14 under the above conditions, it is difficult to use a recording material (heated material) having a low friction coefficient.

In order to solve the above-mentioned drawbacks, for example, Japanese Patent Laid-Open Publication No. Hei 6-348156 proposes a method of increasing the coefficient of friction between the outer peripheral surface of the film and the pressurizing rotary body outside the passage of the material to be heated. I have.

[0028]

Normally, this type of pressure roller is provided with an FEP, PFA, etc. on the outer peripheral surface of a foaming silicone rubber having a cavity inside for the reason of suppressing hardness, heat resistance and thermal expansion. A coating having a low coefficient of friction and a high airtightness is often used.

However, as proposed in Japanese Patent Application Laid-Open No. 6-348156, in order to increase the coefficient of friction in the portion outside the passage of the material to be heated, coating of both ends of the roller is abolished to expose the rubber layer. In some cases, a sufficient coefficient of friction cannot be obtained simply by roughening the coating surface.

Japanese Patent Application Laid-Open No. 6-348156 proposes that a roller-shaped member made of a material having a high friction coefficient is separately provided on the left and right sides.

However, when such a member is provided with a highly airtight coating on the outer peripheral surface and is in close contact with both ends of a foamable silicone rubber having a cavity inside, the inside cavity is sealed, and when heated, There is a problem in that the air in the cavity expands and the pressure roller expands like a balloon, and the conveying speed of the material to be heated by the pressure roller changes, which adversely affects the performance of the apparatus.

An object of the invention according to the present application is to provide an image heating apparatus capable of guaranteeing stable friction driving of a rotating body by the pressing rotating body even when the rotating pressurizing body is heated.

[0033]

According to a first aspect of the present invention, a rotating body, a heating body provided inside the rotating body, and a rotating body in contact with the rotating body. A pressurizing rotator to be driven, wherein a heating target carrying an image is nipped and conveyed at a contact portion between the rotator and the pressurizing rotator, and is heated by the heat from the heating body via the rotator. In an image heating device that heats an image on a heating material, the pressing rotator includes a main body formed of a heat-resistant material having a cavity therein,
A surface layer having high airtightness with respect to the cavity formed on the outer peripheral surface of the main body portion in the heated material passage area, and having a friction coefficient in contact with the outer peripheral surface of the rotating body outside the heated material passage area. A high friction portion having an outer peripheral surface higher than an outer peripheral surface in the material passage area, and a ventilation means for communicating a cavity inside the main body with outside air.

A second configuration for realizing the object of the invention according to the present application is a rotating body, a heating body provided inside the rotating body, and a pressurizing rotating body in contact with the rotating body and driving the rotating body. Having a contact member between the rotating body and the pressurized rotating body, holding and transporting the heated material carrying the image, and forming an image on the heated material by heat from the heating body via the rotating body. In the image heating apparatus for heating, the pressurizing rotator is formed of a heat-resistant material having a cavity in the passage of the material to be heated, and a first main body having a surface layer whose outer peripheral surface is highly airtight with respect to the cavity. Contacting the outer peripheral surface of the rotating body and having a friction coefficient of the first
An image heating apparatus, comprising: the first main body portion and a second main body portion provided with a gap outside the heated material passage area higher than an outer peripheral surface of the main body portion.

A third structure for realizing the object of the invention according to the present application is a rotating body, a heating body provided inside the rotating body, and a pressure rotating body which is in contact with the rotating body and drives the rotating body. Having a contact member between the rotating body and the pressurized rotating body, holding and transporting the heated material carrying the image, and forming an image on the heated material by heat from the heating body via the rotating body. In the image heating apparatus for heating, the pressurizing rotator is formed of a heat-resistant material having a cavity in the passage of the material to be heated, and a first main body having a surface layer whose outer peripheral surface is highly airtight with respect to the cavity. A second main body part that is in contact with the first main body part outside the passage of the material to be heated and has a higher coefficient of friction with the outer peripheral surface of the rotating body than the outer peripheral surface of the first main body part; And the second
An image heating apparatus according to an image heating apparatus, further comprising a ventilation hole for communicating the cavity of the first main body with the outside air in a state of being in close contact with the main body.

A fourth structure for realizing the object of the invention according to the present application is the above-described third structure, wherein the ventilation hole is formed as a through hole in the length direction of the second main body. A feature of the invention is an image heating apparatus.

According to a fifth configuration for realizing the object of the invention according to the present application, in the above-mentioned third configuration, the ventilation hole has a length on a joint surface between the first main body and the second main body. The image heating device is formed in a direction perpendicular to the direction.

A sixth structure for realizing the object of the invention according to the present application is a rotating body, a heating body provided inside the rotating body, and a pressurizing rotating body in contact with the rotating body and driving the rotating body. Having a contact member between the rotating body and the pressurized rotating body, holding and transporting the heated material carrying the image, and forming an image on the heated material by heat from the heating body via the rotating body. In the image heating device for heating, the pressurizing rotator is formed of a heat-resistant material having a cavity therein, and the outer peripheral surface in the heated material passage region has a highly airtight surface layer with respect to the cavity,
Outside the heated material passage region, the surface layer is not formed on the first main body portion, and the first main body portion is in contact with the first main body portion, and the coefficient of friction between the first main body portion and the outer peripheral surface of the rotating body is smaller than that of the first main body portion. A high second main body portion, and in a state where the first main body portion and the second main body portion are in close contact with each other, the cavity of the first main body portion and the outside air are passed through the surface non-formation portion of the first main body portion. An image heating device is characterized in that the image heating device is in communication.

A seventh structure for realizing the object of the present invention according to the present invention is any one of the first to sixth structures, wherein the material to be heated is a recording material on which a fixed image is formed and carried. A fixing device for heating and fixing the unfixed image to the recording material.

An eighth structure for realizing the object of the invention according to the present application is the endless film according to any one of the first to seventh structures, wherein the pressing rotator is provided via the film. And forming a nip with the heating element.

According to a ninth configuration for realizing the object of the invention according to the present application, in any one of the first to seventh configurations, the rotating body is a roller having a cored bar, The body is in an image heating device characterized by forming a nip with this roller.

The tenth embodiment for realizing the object of the invention according to the present application is as follows.
In the image heating apparatus according to the eighth aspect, the endless film as the rotating body is loosely fitted around the heating body.

In each of the above structures, the pressurizing rotator such as the pressurizing roller is configured so that the air accumulated in the cavity inside the pressurizing rotator is ventilated to the outside air without being sealed, so that the image is heated for image heating. Even if the pressing rotator is heated, the air in the cavity flows out, so that the pressing rotator does not expand abnormally. Therefore, the rotating body driven by friction can be stably driven and rotated.

[0044]

BEST MODE FOR CARRYING OUT THE INVENTION

<First Embodiment> FIGS. 1 to 3 show a first embodiment of an image heating apparatus according to the present invention. FIG. 1 is a partially cutaway front view of a main part of the apparatus, and FIG. FIG. 3 is an enlarged schematic cross-sectional view of the vicinity of the press-contact nip. Note that the same reference numerals are given to the same constituent members and portions as those of the heating device of the pressure roller drive system shown in FIG. 8 described in the above-described conventional technique, and the description thereof will be omitted.

In FIG. 1, reference numerals 24 and 25 denote left and right side plates of the apparatus chassis, and the pressing roller 11 has a core shaft 11d.
Are disposed so as to be freely rotatable between the left and right side plates 24 and 25 via bearings 26 and 27, respectively. Reference numeral 11c denotes a gear provided concentrically and integrally with the core shaft 11d of the pressure roller 11, and the rotation of the pressure roller 11 is performed by transmitting the rotational force from the drive source M to the gear 11c. .

The heating element 12 of this embodiment is a linear heating element (hereinafter, referred to as a heater) having a low heat capacity. As shown in the schematic diagram of FIG. 3, for example, the thickness is 0.635 mm and the width is 6.5 m.
m, an alumina substrate 12a made of ceramic having a good thermal conductivity and a length of about 375 mm, and a heating element layer 12b formed by applying a current-generating resistance material along the length of the alumina substrate 12a to a width of 1.5 mm in a narrow band shape. Is a basic configuration.

In this embodiment, the heater 1 as a heating element
2 and a glass coating layer 12c on the heater surface to reduce the friction coefficient μ3 between the inner surface of the endless heat-resistant fixing film 14 as a rotating body having the heater 12 inside. Heat resistant grease is applied to the surface to improve the slidability between the heater 12 and the fixing film 14.

The heater 12 is held by being adhered to a heater holding member 13 made of a heat insulating material with a heat-resistant adhesive. Further, the heater holding member 13 is connected to a reinforcing plate 16 made of a metal material.
It is attached to. The reinforcing plate 16 serves to improve rigidity so that the heater holding member 13 is not bent. 15 guides the fixing film 14 from the inside,
It is a guide member for stabilizing the conveyance of the fixing film 14, and is fixed to the heater holding member 13.

The endless belt-like heat-resistant fixing film 14 is loosely fitted to the assembly of the heater 12, the heater holding member 13, the reinforcing plate 16 and the guide member 15. Reference numerals 22 and 23 denote a pair of left and right film end face regulating plates attached to both ends of the reinforcing plate 16, respectively.

The heater 12, the heater holding member 13, the reinforcing plate 16, the guide member 15, the fixing film 14, the regulating plate 22
・ Assembly of 23 (heater / film assembly)
A heater holding member 1 protruding outward from both right and left ends.
3 are made to protrude outside the side plates 24, 25 through through holes 24a, 25a provided in the left and right side plates 24, 25 of the apparatus chassis, respectively.・ It is located between 25. Also, the outer bent pieces 24b and 25b on the upper side of the left and right side plates 24 and 25 and the through holes 24a of the left and right side plates 24 and 25
.Heater holding members 13 projecting outward from 25a, respectively
The pressurizing springs 21 are contracted between the two end portions 13b.

With this configuration, a pressing force acts on the heater / film assembly, and the heater 12 causes the total pressure of 4 to 10 k to be applied to the upper surface of the pressure roller 11 with the fixing film 14 interposed therebetween.
The pressure contact nip N is formed by pressure contact at about gf.

As shown in the schematic diagram of FIG. 3, the fixing film 14 serving as a rotating body includes a heat-resistant base film 14c made of, for example, polyimide or polyimide ether, and PTFE or PFA on the outer peripheral surface of the film 14c in contact with an image. The release layer 14 is made of a material having good releasability such as a fluororesin-based material such as
It is an endless belt-like film provided with a.

In this embodiment, a primer layer 14b for strengthening the adhesion between the release layer 14a and the heat resistant base film 14c is coated on the polyimide heat resistant base film 14c having a thickness of about 50 μm to a thickness of about 4 μm. The surface of the fixing film 14 is coated with PTFE as a release layer 14a to a thickness of 10 μm, and has a total thickness of about 64 μm.

The transfer efficiency of the heat energy of the heater 12 to the image contact surface is better as the thickness of the fixing film 14 is thinner.
Fixing film 1 to increase the rigidity of fixing film 14
The thickness of the fixing film 14 is desirably 20 μm or more and less than 100 μm because 4 is preferably thicker.

The heater 12 is rapidly heated by the heat generated by the heating element layer 12b when AC100V is supplied from both ends in the longitudinal direction of the heating element layer 12b. The temperature of the heater 12 is controlled to a predetermined temperature by controlling the energization of the heating element layer 12b by a control system (not shown).

When the pressure roller 11 is rotated in the direction A by the drive source M, the film 14 is heated by the frictional force between the pressure roller 11 and the fixing film 14 so that the inner surface of the film 14 is heated by the heater 12.
Is driven to rotate in the B direction while closely sliding on the surface.

The left and right film end face regulating plates 22.2
Reference numeral 3 denotes a member for regulating the position of the fixing film 14 in the longitudinal direction.
When the fixing film 14 is at a regular position, the fixing film 14 and the regulating plate 22 are provided.
23 does not come into contact, and when the fixing film 14 is slightly rotated on one side or the other side in the longitudinal direction during rotation, the side of the regulating plate 22 or 23 on the end face of the fixing film 14 hits, so that the fixing film 14 It serves to keep it within a predetermined range.

In a state where the fixing film 14 is driven to rotate by the pressure roller 11 and the heater 12 is heated to a predetermined temperature by energization, the unfixed toner image 20 The recording material 19 (FIG. 3) as a material to be heated on which is formed and carried is guided by the entrance guide 18 and introduced between the fixing film 14 in the press-contact nip portion N and the pressure roller 11, as described above. 8, the unfixed toner image 20 on the recording material 19 is the same as in the case of the heating device shown in FIG.
Is performed by heat-fusion fixing.

In the present embodiment, the pressure roller 11 forms a roller-shaped rubber layer 11a concentrically and integrally with the core shaft 11d, and a release layer to prevent toner and the like from adhering to the surface of the rubber layer 11a. 11b. Rubber layer 11a
Is formed of a heat-resistant rubber material such as silicon rubber, and a plurality of hollow portions 11e for releasing heat are provided in the inside thereof in the longitudinal direction as shown in FIG.
The release layer 11b is made of a fluorine resin having good releasability such as FEP and PFA.

In this embodiment, the rubber layer 11a is composed of liquid silicon rubber having a rubber hardness of 40 to 50 °, and the surface thereof is coated with a release rubber layer 11b of a material in which FEP is dispersed in fluorine rubber to a thickness of about 30 μm. .

Further, at both ends of the rubber layer 11a, a film transport portion 11f made of a heat-resistant material having a higher coefficient of friction than the release layer 11b is provided concentrically and integrally. The rubber layer 11a and the film transport section 11f are provided with a gap 11g such that the cavity 11e is not sealed even when heated and thermally expanded.

In this embodiment, the maximum sheet passing width is 257 m.
rubber layer 11 with a distance of 3 mm on the left and right
a is provided with a width of 263 mm, a gap 11 g of 1 to 2 mm is provided, and a film transport section 11 f is provided with a width of about 15 mm.

Here, since the film transport section 11f has a high friction coefficient (both the dynamic friction coefficient and the static friction coefficient), the friction coefficient μ2 with the outer peripheral surface of the fixing film 14 can be increased. Since this is outside the pass area of the recording material 19, a stable friction coefficient can be obtained without adhesion of dirt such as toner.

Further, the rubber layer 11a and the film transport section 11
f is provided with a gap 11g such that the cavity 11e is not sealed even when heated and thermally expanded.
Even if the air in the cavity 11e thermally expands, it flows out of the rubber layer and the outer diameter of the rubber layer 11a does not change, so that the recording material 19 can be stably conveyed.

When the pressure roller 11 obtains a driving force and rotates in the direction A, the recording material 19 sandwiched between the pressure roller 11 and the fixing film 14 is moved in the direction F by the frictional force of the outer peripheral surface of the pressure roller 11. Conveyed. At this time, a frictional force f1 due to a friction coefficient μ1 with the surface of the recording material 19 acts on the fixing film 14 in a range within the passing region of the recording material 19, and the film transport portion 11f of the pressure roller 11 outside the passing region of the recording material 19. A frictional force f2 is exerted on the fixing film 14 and the outer peripheral surface by the friction coefficient μ2. Therefore, the frictional force f1 and the frictional force f2
Fixing film 1 by film transport force F1 due to resultant force
4 rotates in the B direction.

At this time, since the frictional force f3 due to the friction coefficient μ3 between the heater 12 and the inner surface of the fixing film 14 acts against the rotation of the fixing film 14, the fixing film 14 is stably driven without slipping. To rotate,
It is necessary to increase the film transport force F1 acting on the fixing film 14.

In this embodiment, the recording material 1 having a low friction coefficient
9, the frictional force f2 is increased by increasing the friction coefficient μ2, and the film transport force F is increased.
1 as well as the pressure roller 11
The thermal expansion of the rubber layer 11a due to the heating of the heater 12 can be suppressed, and the recording material can be stably conveyed.

<Second Embodiment> FIG. 4 is a partial sectional view of a pressure roller showing a second embodiment of the present invention.

In FIG. 4, the rubber layer 1 of the pressure roller 11
1a and film transport units 11 arranged on both sides thereof
f is in close contact unlike the first embodiment. However, the film transport unit 11f is provided so that the air in the cavity 11e provided inside the rubber layer 11a is not sealed off from the outside air.
Is provided with a plurality of ventilation holes 11h over the entire area in the axial direction.

(First Modification of the Second Embodiment) FIG. 5 shows a first modification of the second embodiment.

In the first modified example, unlike the first embodiment, the rubber layer 11a of the pressure roller 11 and the film transport section 11f are brought into close contact with each other, but the hollow portion provided inside the rubber layer 11a is provided. A vent groove 11i is formed on the joint surface of the film transport portion 11f with the rubber layer 11a so that the air in the film 11e is not sealed from the outside air, so that the outside air and the cavity communicate with each other outside the pass area of the recording material. I have. In this modification, the ventilation groove 11i is formed on the film transport section 11f side, but the film transport section 11 in the rubber layer 11a is formed.
The same effect can be obtained even if a similar ventilation groove is formed on the joint surface side with f.

(Second Modification of Second Embodiment) FIG. 6 shows a second modification of the second embodiment.

In the second modified example, unlike the first embodiment, the rubber layer 11a of the pressure roller 11 and the film transport section 11f are brought into close contact with each other, but the end of the rubber layer 11a outside the recording material passage area. As for (2), a rubber layer exposed portion 11j that exposes the rubber layer 11a without providing the release layer 11b on the surface is provided.

The rubber layer 11a is formed of a sponge-like foam material, and the air in the cavity 11e provided therein is configured to ventilate with the outside air through a fine foam.

In the first embodiment described above, since there is no object in pressure contact with the heater 12 at the gap 11g on the pressure roller side, heat is less likely to be lost, and therefore the temperature of the heater 12 is partially reduced. To rise. However, in the above-described second embodiment shown in FIGS. 4 to 6, any part of the pressure roller 12 is pressed against the entire area in the longitudinal direction of the heater 12, so that the temperature distribution of the heater 12 becomes uniform and the heater 12 becomes uniform. 12, the same effects as in the first embodiment can be obtained without sacrificing durability.

<Third Embodiment> FIG. 9 is a schematic view of a heat fixing device as a fixing device according to a third embodiment of the present invention.

The heat fixing device of the present embodiment is of a type in which a halogen heater is incorporated in a fixing roller, 32 is a fixing roller which is a rotating body, 35 is a pressure roller, and 41 is a recording material P which is applied to both rollers 32. A guide for guiding between the rollers 35, 42 and 43 are separation claws for preventing the recording material P passing through the rollers 32 and 35 from being wound around the rollers, and 44 and 45 are discharge rollers for feeding the recording material P.

The fixing roller 32 has, for example, a surface layer of a low friction material such as Teflon on a cored bar, and has a built-in heating halogen heater 32a as a heating body at the center thereof. The pressing roller 35 is a driving roller that is driven to rotate by a driving source (not shown), and drives the fixing roller 32 that comes into pressure contact with a predetermined pressing force.

In this embodiment, the pressure roller 35
Has a roller configuration similar to that of the above-described first and second embodiments. For example, a gap is provided between both ends of a rubber layer having a cavity passing therethrough in the axial direction, outside the recording material passage area. Or a friction member having a hole or a groove communicating between the cavity and the outside is provided in contact with both ends of the rubber layer. Friction members are provided in contact with both ends of the rubber layer, and at that time, portions where the rubber layer is exposed without a release layer at both ends of the rubber layer are formed, and these friction members serve as a rotating member of a fixing roller. By contacting the surface with low friction, the coefficient of friction therebetween increases, and the driving force of the pressure roller 35 is reliably transmitted to the fixing roller 32.

In each of the above embodiments, the high-friction portions are provided on both sides of the pressing roller as the pressing rotator. However, the present invention is not limited to this. good.

[0081]

According to the inventions according to the first to tenth aspects, the air collected in the cavity inside the pressure roller is heated without being sealed with respect to the outside air. Also, since the air in the cavity flows out, the pressure roller does not expand abnormally. Therefore, even if a material to be heated having a low coefficient of friction is used, the film and the material to be heated do not slip, and not only can the film be stably transported, but also the outer diameter changes little even when the pressure roller is heated. Also, the material to be heated can be stably conveyed, and in an image heating and fixing apparatus, disturbance of a fixed image can be prevented.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view of a main part of an image heating apparatus according to a first embodiment.

FIG. 2 is an enlarged cross-sectional view of a main part of FIG.

FIG. 3 is an enlarged schematic cross-sectional view showing the vicinity of a press-contact nip portion according to the first embodiment.

FIG. 4 is a cross-sectional view of a pressure rotating body according to a second embodiment.

FIG. 5 is a cross-sectional view of a pressure rotating body showing a first modification of the second embodiment.

FIG. 6 is a cross-sectional view of a pressure rotating body showing a second modification of the second embodiment.

FIG. 7 is a configuration diagram of a conventional heating device using a film-driven film heating method.

FIG. 8 is a schematic diagram of a conventional heating device using a film heating system driven by a pressure roller.

FIG. 9 is a sectional view of a fixing device according to a third embodiment.

[Explanation of symbols]

11, 35: pressure roller (pressure rotating body) 12: heating element 14: heat-resistant film (fixing film) in the form of an endless belt 19: recording material (heated material) N: pressure nip (fixing nip) 11a ... Rubber layer of pressure roller 11b ... Release layer 11e ... Cavity part 11f ... Film transport part 11g ... Gap 11h ... Vent hole 11i ... Vent groove 11j ... Rubber layer exposed part 32 ... Fixing roller 32a ... Heater

Claims (10)

[Claims] 1. A rotating body, a heating body provided inside the rotating body, and a pressurizing rotating body in contact with the rotating body and driving the rotating body, wherein the rotating body and the pressurizing rotation In an image heating apparatus for nipping and transporting a material to be heated carrying an image at a contact portion of the body and heating an image on the material to be heated by heat from the heating body via the rotating body, the pressurizing rotating body includes: A main body portion formed of a heat-resistant material having a cavity therein, a surface layer having high airtightness with respect to the cavity formed on an outer peripheral surface in the heated material passage area of the main body portion, and outside the heated material passage region. A high friction portion having an outer peripheral surface which is in contact with the outer peripheral surface of the rotating body and has a higher coefficient of friction than the outer peripheral surface in the passage of the material to be heated, and ventilation for communicating a cavity inside the main body with outside air. An image heating apparatus comprising: 2. A rotating body, a heating body provided inside the rotating body, and a pressure rotating body that contacts the rotating body and drives the rotating body. In an image heating apparatus for nipping and transporting a material to be heated carrying an image at a contact portion of the body and heating an image on the material to be heated by heat from the heating body via the rotating body, the pressurizing rotating body includes: The inside of the heated material passage area is formed of a heat-resistant material having a cavity therein, and has a first body portion having a highly airtight surface layer with respect to the cavity on the outer peripheral surface, and a friction coefficient in contact with the outer peripheral surface of the rotating body. An image heating apparatus, comprising: the first main body portion and a second main body portion provided with a gap outside the heated material passage area higher than an outer peripheral surface of the first main body portion. 3. A rotating body, a heating body provided inside the rotating body, and a pressure rotating body that is in contact with the rotating body and drives the rotating body. In an image heating apparatus for nipping and transporting a material to be heated carrying an image at a contact portion of the body and heating an image on the material to be heated by heat from the heating body via the rotating body, the pressurizing rotating body includes: A first body portion formed of a heat-resistant material having a cavity therein and having a highly airtight surface layer with respect to the cavity, and a first body portion outside the passage region of the material to be heated; A second body portion having a higher coefficient of friction with the outer peripheral surface of the rotating body than the outer peripheral surface of the first body portion, and in a state of close contact between the first main body portion and the second main body portion,
An image heating apparatus, comprising: a cavity for communicating the cavity of the first main body with the outside air. 4. The image heating apparatus according to claim 3, wherein the ventilation hole is formed as a through hole in a length direction of the second main body. 5. The image heating apparatus according to claim 3, wherein the ventilation hole is formed in a joining surface between the first main body and the second main body in a direction orthogonal to a length direction. apparatus. 6. A rotating body, a heating body provided inside the rotating body, and a pressure rotating body that is in contact with the rotating body and drives the rotating body, wherein the rotating body and the pressure rotating In an image heating apparatus for nipping and transporting a material to be heated carrying an image at a contact portion of the body and heating an image on the material to be heated by heat from the heating body via the rotating body, the pressurizing rotating body includes: It is formed of a heat-resistant material having a cavity inside, and has a highly airtight surface layer with respect to the cavity on the outer peripheral surface in the heated material passage area, and the surface layer is not formed outside the heated material passage area. A first main body portion, and a second main body portion that is in contact with the first main body portion and has a higher coefficient of friction with an outer peripheral surface of the rotating body than an outer peripheral surface of the first main body portion;
An image heating apparatus, wherein a cavity of the first main body and outside air are communicated through a non-surface layer portion of the first main body in a state where the main body and the second main body are in close contact with each other. 7. The fixing device according to claim 1, wherein the material to be heated is a recording material on which a fixed image is formed and carried, and a fixing device for heating and fixing the unfixed image on the recording material. An image heating device according to any one of the preceding claims. 8. The rotating body according to claim 1, wherein the rotating body is an endless film, and the pressurizing rotating body forms a nip with the heating body through the film. An image heating device according to any one of the preceding claims. 9. The rotating body according to claim 1, wherein the rotating body is a roller having a cored bar, and the pressing rotating body forms a nip with the roller. Image heating device. 10. The image heating apparatus according to claim 8, wherein the endless film as the rotating body is loosely fitted around the heating body.