JPH06348156A - Heating device - Google Patents

Abstract

PURPOSE:To stably convey a film while using a heated material having a low friction coefficient by increasing the static friction coefficient and dynamic friction coefficient between the outer periphery of the film and the surface of a pressure rotor outside the passing area of the heated material. CONSTITUTION:The friction force f2 between a film 14 and a pressure roller 11 serving as a pressure rotor sliding and rotatively driving the film 14 into pressure contact with a heating element 12 is increased by a reasonable means. A mold releasing layer 11b having a distance to the right and left against the maximum paper passing width is provided, and rubber layer exposure sections D, D are provided on the right and left. The rubber layer exposure sections D, D have a high dynamic friction coefficient and a high static friction coefficient, thus the friction coefficient mu2 with the outer periphery of the fixing film 14 can be increased. No stain is stuck by a toner or the like outside the passing area of a recording material. Even when the recording material having a low friction coefficient is used and the friction force f1 is decreased, the friction coefficient mu2 is increased, and the friction force f2 is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a heating body (thermal heater) and a heat-resistant film that is in close contact with the heating body and runs slidingly. The present invention relates to a film-heating-type heating device that moves the heating element along with the film and passes the heat energy of the heating element to the material to be heated through the film.

[0002]

2. Description of the Related Art A heating device of the film heating type as described above is disclosed in, for example, JP-A-63-313182 and JP-A-2-157878.
In the image forming apparatus such as an electrophotographic copying machine, a laser beam printer, a facsimile, a micro film reader printer, an image display (display) device, and a recording machine, it has been proposed in Japanese Patent Publication No. 4-44075 to 44083. An image heating and fixing device, that is, a recording material (electrofax sheet / electrostatic sheet) using a developer (toner) made of a heat-meltable resin by an appropriate image forming process means such as electrophotography, electrostatic recording and magnetic recording. Direct or indirect (transfer) on the surface of recording sheet, transfer material sheet, printing paper, etc.
In this method, an unfixed toner image corresponding to desired image information is formed and carried, and the toner image is heat-fixed as a permanently fixed image on the surface of the recording material carrying the image.

Further, it can be used, for example, as a device for heating a recording material carrying an image to modify the surface properties of gloss and the like, a device for post-treatment.

The heating device of the film heating system can use a heating body having a low heat capacity, and by using a film of a thin film, compared with the heating devices of other systems such as the conventional heat roller system. It has advantages such as power saving and shortened wait time (quick start).

FIG. 4 and FIG. 5 each show a schematic structure of an example of a heating device of a film heating type using an endless belt-shaped film as a heat resistant film. The heating device of this example is an image heating and fixing device.

In the apparatus shown in FIG. 4, reference numeral 14 denotes an endless belt-shaped thin film heat-resistant film, which is arranged substantially parallel to each other, and includes a driving roller 5, a driven roller 6 also serving as a tension roller, and a heating body 12. It is suspended between the three members.

Reference numeral 1 is a pressure roller which forms a pressure contact nip portion (fixing nip portion) N by sandwiching the film with the heating body 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 by a reinforcing member (stay) 16.

The drive roller 5 is rotated clockwise by the drive source M in the figure, so that the heat-resistant film 14 in the form of an endless belt is rotated clockwise while the inner surface of the heat-resistant film 14 slides in close contact with the surface of the heating body 12. Driven. The pressure roller 1 is driven to rotate as the film rotates.

While the film 14 is rotationally driven by the drive roller 5 and the heating body 12 is heated to a predetermined temperature by energization, the unfixed toner image 20 is transferred from the image forming unit side (not shown). When the recording material 19 as a material to be heated that has been formed and carried is introduced between the film 14 in the pressure contact nip portion N and the pressure roller 1, the recording material 19 is brought into close contact with the outer surface of the rotating film 14 to form a film. It passes through the pressure contact nip portion N in an overlapping state with 14.

During the process of passing through the pressure contact nip portion, the thermal energy of the heating body 12 is applied to the recording material 19 via the film 14, and the unfixed toner image 20 on the recording material 19 is heated and fused and fixed. The recording material 19 passes through the pressure contact nip portion N, is separated from the surface of the film 14, and is discharged.

As in the apparatus shown in FIG. 4, a drive roller 5 is provided inside the endless belt film 14 to rotate the film in a tensioned state, and the pressure roller 1 as a pressure member is driven to rotate. The device is hereinafter referred to as a "film drive system" device.

In the apparatus shown in FIG. 5, the heat-resistant film 14 in the form of an endless belt is not stretched between tension members, but the heating element 1 is used.
2 is loosely fitted on the outer side of 2, and the film 14 is sandwiched between the heating body 12 and the pressure roller 11 so that the pressure contact nip portion N is formed.

The pressure roller 11 is rotated in the counterclockwise direction A in the figure by the drive source M, and the friction force between the rotary pressure roller 11 and the film 14 causes the film 14 to move to the inner surface of the heating body 12. It is configured to rotate and drive in the clockwise direction B while sliding closely on the surface.

While the film 14 is driven to rotate by the pressure roller 11 and the heating body 12 is heated to a predetermined temperature by energization, the unfixed toner image 20 is fed from the image forming unit side (not shown). The recording material 19 as a material to be heated, on which the recording material 19 is formed and carried, is introduced between the film 14 in the pressure contact nip portion N and the pressure roller 11, so that the recording material 19 on the recording material 19 is transferred in the same manner as in the case of the apparatus shown in FIG. The unfixed toner image 20 is heated and fused and fixed.

An apparatus of the type in which the pressure roller 11 is driven to rotate the film 14 as in the apparatus of FIG. 5 is hereinafter referred to as a "pressure roller driving type" apparatus.

In this pressure roller driving type heating device, the heating element 12, the film 14 and the pressure roller 11 have a longitudinal direction which is equal to or greater than the width of the recording material 19 which is the maximum width that can pass through the device. Has a width of.

When the pressure roller 11 receives the driving force and rotates in the direction A, the recording material 19 sandwiched between the pressure roller 11 and the film 14 is moved to F by the frictional force of the outer peripheral surface of the pressure roller 11.
Is 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 the range within the passing area of the recording material 19, and the pressure roller 11 and the film 14 directly contact with each other outside the passing area of the recording material 19. A frictional force f2 on the surface of the pressure roller 11 acts on the film 14.

Therefore, the film 14 is driven and rotated in the B direction by the film conveying force F1 which is the resultant of the frictional force f1 and the frictional force f2.

At this time, since the frictional force f3 acts between the heating body 12 and the inner surface of the film 14 against the rotation of the film 14, the film 14 is stably driven without slipping with the recording material 19. In order to rotate, the film conveying force F1 needs to be larger than the frictional force f3. Film 14
The slip between the recording material 19 and the recording material 19 causes disturbance of the fixed image and wrinkles on the recording material.

The outer peripheral surfaces of the pressure roller 11 and the film 14 are covered with a PF surface layer in order to prevent unfixed toner and paper powder conveyed by the recording material 19 from adhering to the surface.
It is made of a material having a good releasability such as a fluorine-based material such as A or FEP. Since the coefficient of friction between materials having good releasability is generally low, the above-mentioned 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 was coated with a low friction layer or grease.

[0024]

The film-driving-type heating device (FIG. 4) and the pressure roller-driving-type heating device (FIG. 5) described above are different from the former film-driving-type device. The pressure roller drive type device can reduce the size and cost of the device because the number of drive rollers can be reduced, and the displacement force to one side or the other side of the film rotation axis in the film rotation process is small. It has the advantage that the film shift control means can be simplified.

In this pressure roller drive type apparatus, as described above, in order to stably rotate the film 14 without slipping, the film conveying force by the resultant force of the frictional force f1 and the frictional force f2 acting on the film 14 is used. It is necessary to make the frictional force f3 smaller than that of F1, and the heating body 12 and the film 1
In order to reduce friction during the period of 4, the surface of the heating body 12 was coated with a low friction layer or grease was applied.
However, it has the following drawbacks.

.. Although coating or applying grease to the heating element 12 initially lowers the friction coefficient on the surface of the heating element, since it has no durability, the frictional force f between the heating element 12 and the film 14 is reduced.
It is difficult to lower 3 stably.

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

.. Friction force f between the film 14 and the recording material 19
1 is determined by the friction coefficient between the film 14 and the recording material 19 as the material to be heated, but 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 transporting force F1 of the film 14 under the above conditions, it was difficult to use a recording material (heated material) having a low friction coefficient.

Therefore, the present invention solves the above-mentioned problems in the film heating type heating device of the pressure roller driving type, that is, the film 14 and the film are pressed against the heating body 12, and the film is placed on the heating body surface. The frictional force f of the pressure roller 11 as a pressure rotating body that slides and rotates.
By increasing No. 2 by a rational means, the transport force of the film 14 can be enhanced, and even if a heated material having a low friction coefficient is used, stable film transportation can be performed without slipping between the film and the heated material. Accordingly, it is an object of the present invention to provide an image heating fixing device capable of preventing image defects such as disorder of a fixed image and wrinkles of a recording material when the heating device is an image heating fixing device.

[0031]

The present invention is a heating device characterized by the following constitutions.

(1) A heat-resistant film in the form of an endless belt, a heating body provided inside the film, and a pressure contact nip portion formed by sandwiching the film between the heating body and the inner surface of the film. And a heating member for rotating the film in the material conveying direction at a predetermined speed while sliding on the heating member surface, and the heating member is provided between the outer surface of the film at the pressure nip portion and the pressing member. In the heating device of the film heating system for applying the heat energy of the heating body to the material to be heated through the film by moving the pressure contact nip portion together with the film, and the film outer peripheral surface and the pressure rotating body. The heating device is characterized in that the coefficient of static friction and the coefficient of dynamic friction between the two are increased outside the area through which the material to be heated passes.

(2) The heating device according to (1), characterized in that the coefficient of static friction and the coefficient of dynamic friction of the outer peripheral surface of the pressurizing rotary member outside the heated material passage region are increased.

(3) The heating device as described in (1) or (2), wherein the coefficient of static friction and the coefficient of dynamic friction outside the area through which the material to be heated passes on the outer peripheral surface of the film are increased.

(4) The heating material is a recording material on which an unfixed image is formed and carried, and the fixing device heats and fixes the unfixed image on the recording material (1) to (3). ) The heating device according to any one of 1).

[0036]

The material to be heated introduced into the apparatus has a low coefficient of friction, so that even if the frictional force f1 between the film and the material to be heated is reduced, the coefficient of static friction between the outer peripheral surface of the film and the rotating body under pressure is reduced. And the friction coefficient f2 is increased by increasing the coefficient of kinetic friction outside the heated material passing region, that is, by increasing the coefficient of friction μ2 between the film and the rotating body, the film conveying force F1.
The cost is low and space is saved. Therefore, even if a heated material with a low coefficient of friction is used, the film and the heated material do not slip, and stable film transport is possible. Disturbance of a fixed image due to slip between the film and the recording material and image defects such as wrinkles of the recording material can be prevented.

[0037]

【Example】

<First Embodiment> FIGS. 1 to 3 show a heating device (image heating and fixing device) according to an embodiment of the present invention. FIG. 1 is a partially cutaway front view of the main part of the device. 2 is an enlarged cross-sectional view of a main part, and FIG. 3 is an enlarged cross-sectional model diagram near the pressure contact nip.

The same components and parts as those of the pressure roller driving system shown in FIG. 5 are designated by the same reference numerals, and the repetitive description will be omitted.

In FIG. 1, reference numerals 24 and 25 denote left and right side plates of the apparatus chassis, and the pressure roller 11 has a cored bar shaft 11d.
Both end portions of the above are rotatably supported and disposed between the left and right side plates 24 and 25 via bearings 26 and 27, respectively.
Reference numeral 11c designates a gear concentrically provided on the cored bar shaft 11d of the pressure roller 11, and the rotation force of the pressure roller 11 is driven by transmitting a rotational force from the drive source M to the gear.

The heating element 12 is a linear heating element (hereinafter referred to as a heater) having a low heat capacity, and as an example, as shown in the model diagram of FIG. 3, the thickness is 0.635 mm, the width is 6.5 mm, and the length is about 37.
Alumina substrate 12a made of ceramics having a good thermal conductivity of 5 mm, and a heating element layer 1 formed by coating the surface of the alumina substrate 12a with a current-carrying heating resistance material in a width of 1.5 mm in a strip shape.
2b is a basic configuration.

In this embodiment, the heater 12 and the fixing film 1
In order to reduce the friction coefficient μ3 with the inner surface of No. 4, a glass coat layer 12c is provided on the heater surface, and heat resistant grease is applied to the heater surface to improve the slidability between the heater 12 and the fixing film 14.

The heater 12 is a heater holding member 1 made of a heat insulating material.
The heater holding member 13 is attached to a reinforcing plate 16 made of a metal material. The reinforcing plate 16 serves to improve the rigidity so that the heater holding member 13 does not bend.
Reference numeral 15 denotes a guide member that guides the fixing film 14 from the inside to stabilize the conveyance of the fixing film 14, and is fixed to the heater holding member 13.

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

The heater 12, the heater holding member 13,
Both ends 13b and 13b of the heater holding member 13 are formed by projecting an assembly (heater / film assembly) of the reinforcing plate 16, the guide member 15, the fixing film 14, and the regulation plates 22 and 23 outward from both left and right ends thereof. The device chassis is arranged between the left and right side plates 24, 25 on the upper side of the pressure roller 11 in a state of being projected to the outside of the side plates 24, 25 through the through holes 24a, 25a provided in the left and right side plates 24, 25, respectively.

Then, the outer bent pieces 24b and 25b on the upper sides of the left and right side plates 24 and 25 and the through holes 2 of the left and right side plates 24 and 25.
The pressure spring 21 is provided between the both ends 13b and 13b of the heater holding member 13 which is protruded outward from 4a and 25a, respectively.
・ 21 are reduced. As a result, a pressing force acts on the heater / film assembly so that the heater 12 sandwiches the fixing film 14 and applies a total pressure of 4 to 4 to the upper surface of the pressure roller 11.
The pressure contact nip portion N is kept in a state of being pressure-contacted at about 10 kgf.

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

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

The transfer efficiency of the heat energy of the heater 12 to the image abutting surface is better as the thickness of the fixing film 14 is thinner. From the viewpoint of the stability of conveyance of the fixing film 14, the fixing film 14 is fixed in order to increase its rigidity. Since it is better that the film 14 is thicker, the thickness of the fixing film 14 is 20 μm.
m or more and less than 100 μm is desirable.

The heater 12 is connected to both sides of the heating element layer 12b by A
When C100V is energized, the temperature of the heating element layer 12b is rapidly increased by the heat generated. 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 rotationally driven in the direction A by the drive source M, the inner surface of the film 14 is heated by the friction force between the pressure roller 11 and the fixing film 14.
It is rotationally driven in the B direction while sliding in close contact with the second surface.

The left and right film end surface regulating plates 22.2
Reference numeral 3 is a member that regulates the position of the fixing film 14 in the longitudinal direction.
The fixing film 14 and the regulation plate 22 are provided with a distance of 2 mm, and when the fixing film 14 is in the regular position.
23 does not contact, and when the fixing film 14 slightly rotates to one side or the other side in the longitudinal direction during rotation, the end surface of the fixing film 14 and the side surface of the regulation plate 22 or 23 come into contact with each other, so that the fixing film 14 is It serves to keep it within a predetermined range.

While the fixing film 14 is being rotationally driven by the pressure roller 11 and the heater 12 is being energized to raise the temperature to a predetermined temperature, the unfixed toner image 20 is fed from the image forming side (not shown). The recording material 19 (FIG. 3), which is a material to be heated and which has been formed and carried, is guided by the inlet guide 18 and introduced between the fixing film 14 and the pressure roller 11 in the pressure contact nip portion N as shown in FIG. The unfixed toner image 20 on the recording material 19 is heated and fused and fixed in the same manner as in the above apparatus.

In this embodiment, the pressure roller 11 has a roller-like rubber layer 11a formed concentrically with the mandrel shaft 11d, and a release layer for preventing toner and the like from adhering to the surface of the rubber layer 11a. 11b is formed. The rubber layer 11a is a heat-resistant rubber material such as silicone rubber, and the release layer 11b.
Is made of a fluororesin having good releasability such as FEP and PFA.

In this embodiment, the rubber layer 11a has a rubber hardness of 40.
A material composed of liquid silicone rubber of -50 ° and having FEP dispersed in fluororubber as the release layer 11b on the surface thereof is used.
The coating is about 0 μm.

Although the pressure roller 11 is provided with a release layer 11b within the maximum paper passing width C of the recording material 19, the maximum paper passing width C
The outer portion is the rubber layer exposed portions D and D where the release layer 11b is not provided and the rubber layer 11a is exposed, and is provided on the left and right of the recording material 19 with a width of about 5 to 40 mm.

In this embodiment, the release layer 11b has a width of 3 mm with respect to the maximum sheet passing width of 257 mm, and the release layer 11b has a width of 26 mm.
It is provided with a width of 3 mm, and the rubber layer exposed portions D and D are provided on the left and right sides with a width of about 15 mm.

Since the rubber layer exposed portions D and D have high friction coefficients (both dynamic friction coefficient and static friction coefficient), the friction coefficient μ2 with the outer peripheral surface of the fixing film 14 can be increased. Since it is outside the pass area of the recording material 19, a stable friction coefficient can be obtained without dirt such as toner attached.

When the pressure roller 11 receives the driving force and rotates in the A direction, the recording material 19 sandwiched between the pressure roller 11 and the fixing film 14 is moved in the F direction by the frictional force of the outer peripheral surface of the pressure roller 11. Be transported. At this time, in the range within the passage area of the recording material 19, the fixing film 14 is subjected to the frictional force f1 due to the friction coefficient μ1 with the surface of the recording material 19, and outside the passage area of the recording material 19, the rubber layer exposed portion of the pressure roller 11 is exposed. A frictional force f2 due to the friction coefficient μ2 between D and D and the outer peripheral surface of the fixing film 14 acts. Therefore, the fixing film 14 is moved by the film conveying force F1 which is the resultant force of the frictional force f1 and the frictional force f2.
Rotates in the B direction.

At this time, since the frictional force f3 between the heater 12 and the inner surface of the fixing film 14 due to the friction coefficient μ3 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 transporting force F1 acting on the fixing film 14.

In this embodiment, the recording material 19 having a low friction coefficient is used.
Even if the frictional force f1 is reduced by using, the frictional force f2 is increased by increasing the frictional coefficient μ2.
Can be increased.

Therefore, stable film conveyance is performed without slipping between the fixing film 14 and the recording material 19, and image defects such as dirt on the fixed image and wrinkles on the recording material can be prevented.

In particular, in this embodiment, the friction coefficient is increased by exposing a part of the rubber layer D of the pressure roller 14, and there is an advantage that the cost is not increased due to addition of another member or process. is there.

<Second Embodiment> In the first embodiment,
In order to increase the coefficient of friction outside the passage area of the recording material 19 on the outer periphery of the pressure roller 11, the surface of the rubber layer 11a of the pressure roller 11 was exposed at both ends D and D of the roller, but the surface was roughened. Even if a coating layer for increasing the friction coefficient is provided, or roller-like members made of a material having a high friction coefficient are separately provided on the left and right sides, the same effect can be obtained.

<Third Embodiment> In the first embodiment and the second embodiment, the friction coefficient of the pressure roller 11 is increased, but the outer peripheral surface of the fixing film 14 is outside the passage area of the recording material 19. Coating that enhances the coefficient of static and dynamic friction of
Even if the friction coefficient of the outer peripheral surface of the fixing film 14 is increased by the surface roughening process, the static friction coefficient and the dynamic friction coefficient between the outer peripheral surface of the film and the pressure roller surface can be increased outside the passage area of the recording material. The same effect can be obtained.

[0065]

As described above, according to the present invention, in the film heating type heating device using the pressure roller driving system, the outer peripheral surface of the film and the pressure rotator (pressure roller).
By increasing the coefficient of static friction and the coefficient of dynamic friction between the surface and the outside of the passage area of the material to be heated (recording material), the friction force f2 between the film and the rotating pressure member is increased, so that the transport force of the film can be reduced at low cost. Even if a heated material with a low coefficient of friction can be used in a space, the film and the heated material do not slip, and stable film transport can be performed. Image defects such as wrinkles on the recording material can be prevented.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of a main part of a heating device (image heating and fixing device) according to an embodiment.

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

[Fig. 3] Enlarged cross-sectional model view near the pressure contact nip

FIG. 4 is a schematic configuration diagram of an example of a film heating type heating device of a film driving type.

FIG. 5 is a schematic configuration diagram of an example of a heating device of a film heating system of a pressure roller driving system.

[Explanation of symbols]

11 Pressurizing Roller (Pressurizing Rotating Body) 12 Heating Body 14 Endless Belt-shaped Heat Resistant Film (Fixing Film) 19 Recording Material (Heating Material) N Pressing Nip Part (Fixing Nip Part) 11a Rubber Layer of Pressing Roller 11b Release layer C Maximum paper feed width D Exposed area of rubber layer

Claims (4)

[Claims] 1. A heat-resistant film in the form of an endless belt, a heating body provided inside the film, and a press nip portion formed by sandwiching the film between the heating body,
And a pressure rotating body for rotating the film in the material conveying direction at a predetermined speed while sliding the inner surface of the film on the surface of the heating body, and between the outer surface of the film at the pressure contact nip portion and the pressure rotating body. In the heating device of the film heating system, which introduces the material to be heated and moves it through the pressure contact nip part together with the film to apply the heat energy of the heating element to the material to be heated through the film. A heating device characterized in that a coefficient of static friction and a coefficient of dynamic friction with a rotating body are increased outside a region through which a material to be heated passes. 2. The heating device according to claim 1, wherein the coefficient of static friction and the coefficient of dynamic friction of the outer peripheral surface of the pressurizing rotary member outside the heated material passage region are increased. 3. The heating device according to claim 1, wherein the coefficient of static friction and the coefficient of kinetic friction of the outer peripheral surface of the film outside the area through which the material to be heated passes are increased. 4. The fixing material for heating and fixing the unfixed image on the recording material, wherein the material to be heated is a recording material on which an unfixed image is formed and carried. The heating device according to any one of claims.