JP3236077B2 - Image heating device - Google Patents

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 for heating an image on a recording material via an endless film. In particular, the present invention relates to an apparatus for modifying and fixing the surface properties of an image.

2. Description of the Related Art Conventionally, a heat roller system is often used as a fixing device for heating and fixing an image on a recording material, but the applicant has disclosed a thin film in Japanese Patent Application Laid-Open No. 63-313182. An image heating device that heats an image on a recording material through the medium is proposed.

In this film heating method, a heating element having a low heat capacity can be used, and since heat can be concentrated on the nip side, power consumption can be reduced and a wait time can be reduced or eliminated.

When an endless film is used in this film heating system, the endless film shifts.

It is difficult to strictly control the shift of the endless film.

Therefore, Japanese Patent Application No. 2-153602-153 discloses
No. 610, No. 2-33997-339900, it has been proposed that the film be loosely hung to reduce the biasing force of the endless film and that the end of the endless film be received by a flange to control the leaning.

In this apparatus, the film is driven by a pressurizing rotating body that forms a nip with a heating body via the film, and the flange is provided except for the nip portion.

[0008]

However, when the edge of the film is regulated by the flange as described above, if the biasing force of the film is increased, the film may be broken depending on the film thickness and the material, and the generation of wrinkles and cracks may be reduced. As a result, in the image heating / fixing apparatus, deterioration of a fixed image, poor running of a fixing film, shortening of a durable life, generation of a deviation control sound of the film, and the like are observed.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a heating element, an endless film which slides on the heating element, and a pressurizing method for forming a nip with the heating element via the film. A member and a regulating member that regulates an end of the film to prevent the film from shifting, in an image heating apparatus that heats an image on a recording material by heat from the heating body through the film. The regulating member has a regulating surface in which an interval between an imaginary surface perpendicular to a longitudinal direction of the heating body gradually decreases toward a downstream side in a moving direction of the film immediately after the nip, and the regulating surface following the regulating surface. A regulating surface perpendicular to the longitudinal direction of the heating element.

[0010]

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

FIG. 1 is a sectional view of a laser beam printer which is an image forming apparatus using an image heating device according to an embodiment of the present invention as a fixing device.

Reference numeral 1 denotes an electrophotographic photosensitive member (hereinafter, referred to as a drum) rotated at a predetermined peripheral speed. The drum 1 is uniformly charged to a predetermined positive or negative potential by a primary charger 2 in the course of rotation, and is then scanned and written with target image information by laser scanning exposure L by a laser scanner 3. As a result, an electrostatic latent image is formed on the drum 1. The surface of the drum 1 on which the latent image is formed is supplied with the toner T by the developing device 4 and is visualized as a toner image.

The transfer paper P, which is a recording material, loaded on the paper feed cassette 20 is separated one by one by a paper feed roller 21 and a separation pad 22 and fed to a pair of registration rollers 23. Next, in the process of passing through the position of the transfer roller 5, the toner image is sequentially transferred to the surface of the transfer paper P sent between the transfer roller 5 and the drum 1 at a timing by a pair of registration rollers. The transfer from the drum 1 to the transfer paper P surface is performed by the transfer roller 5 charging the reverse side of the transfer paper P surface with the polarity opposite to the polarity of the charged electrode of the toner image. Next, the transfer paper P is discharged by the discharging needle 6 to which a voltage having a polarity opposite to that of the transfer roller 5 is applied, separated from the drum 1, and transported to the heating device 7. The heating device 7 heats and melts the toner T on the transfer sheet P, and fixes the toner T on the transfer sheet P as a permanent fixed image.

FIG. 2 is a front view of the image heating apparatus according to the embodiment of the present invention, and FIG. 3 is a sectional view.

The endless belt-shaped fixing film 8 is a single-layer fixing film having heat resistance, toner release property and toughness, or a composite layer film subjected to a desired surface treatment or lamination. For example, a heat-treated polyester (PET) or polyimide (PI) monolayer film of about 50 μm, or a composite layer film in which the film surface is further subjected to a release layer treatment with ethylene tetrafluoride (PTFE).

The fixing film 8 includes a film guide 10
The tension is not applied except for the nip portion at least when stopped.

The pressure roller 9 is driven by a drive source (not shown), and the fixing film 8 rotates and rotates only by the frictional force with the pressure roller 9.

The heater 14 and the pressure roller 9 in contact with a film guide member 10 (not shown) that guides the inner surface of the fixing film 8 over the entire area in the longitudinal direction are fixed to the fixing film 8.
Are pressed against each other with a predetermined contact pressure (for example, A4 width and a total pressure of 3 to 6 kg) by the pressing springs 11a and 11b. Ta formed on the surface of the heater 14 by vapor deposition, sputtering, CVD, screen printing, or the like.
Sio2, silver-palladium, Ta ₂ N, RuO _2, there is a thin-film heating element portion of the line or strip-like, such as nichrome.

Flange 1 for regulating deviation of fixing film
The third regulating surface 13a has its regulating surface orthogonal to the fixing film center axis except for 13b on the downstream side of the fixing nip.

The heater 14 is provided to be longer than the width of the fixing film because of the need to receive pressure by a pressure spring and the necessity of a current-carrying electrode portion.

For this reason, in the nip portion, in order to prevent interference between the flange and the heater, the regulating surface of the flange is provided except for the nip.

At the downstream side of the fixing nip for re-regulating the end of the fixing film after the nip, the angle θ between the stationary surface and the central axis of the stationary fixing film is set to θ <90 °. By doing so, the regulating surface continuously approaches the film toward the downstream side in the moving direction of the film, and the gap between the regulating surface and the film becomes smaller.

FIG. 4 is a plan view showing a state in which deviation has occurred in the fixing film. Deviation of the fixing film is caused when the positional accuracy of various members (especially, a heater and a pressure roller) is not obtained, and a temperature distribution occurs in a width direction of the heater, so that the conveyance force of the fixing film 8 is not uniform in the width direction. This occurs when the accuracy of the single film (film thickness, cylindricity, etc.) is not sufficient, but the state of the end of the fixing film at that time is uniform and the configuration shown in FIG. 4 is adopted. That is, the difference in the fixing film conveyance force caused by the above factors causes the center axis of the fixing film to be inclined by α ° with respect to the fixing film guide and the flange depending on the difference between the inner peripheral length of the fixing film and the peripheral length of the fixing film guide. Due to a force (frictional force) F perpendicular to the width direction of the pressure roller, the fixing film shifts by a force of F sin α °. At this time, one point (A) on the periphery of the end of the fixing film should draw a spiral trajectory as shown in FIG. 4 if there is no flange. Looks like you're doing it. However, in the fixing nip that applies a rotational force and a shift force to the fixing film, the shift end of the fixing film is not restricted by the above-described reason. Therefore, as shown in FIG. 5, if the trajectory of the end portion of the rotating thin film is largely changed from the upstream side of the nip where the regulation surface is eliminated to the downstream side where the regulation surface is re-regulated, the end portion of the fixing film is damaged. .

On the other hand, in the present embodiment, the regulating flange is provided with a regulating surface for reducing the gap with the film toward the downstream side in the moving direction of the film after the nip.

If the trajectory of the fixing nip is regulated while changing its trajectory abruptly, regulation noise, wrinkles and cracks will be generated due to buckling of the ends.

On the other hand, in the present embodiment, the end of the fixing film downstream of the fixing nip gradually receives the reaction force against the biasing force from the regulating surface, so that the above problem is reduced, and the fixing failure due to wrinkles is eliminated. It has become possible to extend its durability life.

The position where the edge of the film is firmly regulated can be separated from the nip where the film is restrained by the heater and the pressure roller, and the damage to the film can be further reduced.

The burrs and notches generated when cutting the end of the fixing film have been strictly controlled. However, if the flange of this configuration is used, the concentrated load on the burrs and notches is reduced because there is no sharp regulation. You. Accordingly, the restriction on the damage to the edge of the fixing film during processing is relaxed, and the effect of cost reduction is also sufficient.

[0029]

[0030]

[0031]

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and can be variously modified within the technical idea.

[0033]

As described above, according to the present invention, it is possible to prevent damage to the film caused by sharply regulating the end of the endless film.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an image forming apparatus using an image heating device according to an embodiment of the present invention as a fixing device.

FIG. 2 is a sectional view of the image heating apparatus according to the embodiment of the present invention.

FIG. 3 is a sectional view of the image heating apparatus according to the embodiment of the present invention.

FIG. 4 is a plan view illustrating the shift of the endless film.

FIG. 5 is a partial perspective view for explaining the problem of endless film shift control.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Drum 2 Primary charger 3 Scanner 4 Developing device 5 Transfer roller 6 Static elimination needle 7 Heating device 8 Fixing film 9 Pressure roller 10 Film guide 11 Pressure spring 12 Drive gear 13 Regulator flange 14 Heater

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Sugita 3-30-2 Shimomaruko, Ota-ku, Tokyo Within Canon Inc. (56) References JP-A-3-63682 (JP, A) (58) Survey Field (Int.Cl. ⁷ , DB name) G03G 15/20 B65H 5/02 B65H 29/20

Claims (5)

(57) [Claims] 1. A heating element, an endless film that slides on the heating element, a pressing member that forms a nip with the heating element through the film, and a film that prevents the film from shifting. A regulating member for regulating an end portion, wherein the regulating member moves the film immediately after the nip by heating an image on a recording material by heat from the heating body via the film. A regulating surface in which the distance between a virtual surface perpendicular to the longitudinal direction of the heating body toward the direction downstream is gradually reduced, and a regulating surface perpendicular to the longitudinal direction of the heating body following this regulating surface,
An image heating apparatus comprising: 2. The image heating apparatus according to claim 1, wherein the regulating member regulates the film at a location other than the nip. 3. The image heating apparatus according to claim 1, wherein a length of said heating body is longer than a width of said film. 4. The image heating apparatus according to claim 1, wherein the pressing member is a rotating body that rotates by receiving a driving force, and the film moves by following the rotating body. 5. The image heating apparatus according to claim 1, wherein said regulating members are provided on both sides of said film.