JP2001075391A - Image heating device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent recording material from being wound round film and to easily perform jamming disposal by making the tip of a separation pawl abut on the film when a winding detecting member detects the winding of a recording sheet round the film. SOLUTION: When the recording sheet S which starts winding passes through a gap between a fixing device cover 35 and a thin heat-resistant film 34, the winding detecting member 40 rotates clockwise centering a rotary shaft C1 and the tip of the separation pawl 41 comes in contact with the sagging part (floating part from a stay 33 on the downstream side of an inflection part) of the film 34. When the sheet S wound round the film 34 is carried further, the sheet S is separated from the film 34 by the pawl 41. The separated sheet S has no place where it should go and becomes a small accordion state and is accumulated in a gap between the heating unit 31 and a pressure roller 32, or the film 34 is slipped and carrying the sheet S is stopped because carrying space for the sheet S is eliminated.

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 and an image forming apparatus having the same.
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus equipped with a fixing device using a thin heat-resistant film for fixing an image on a recording sheet such as a copying machine, a printer, and a facsimile machine using electrophotography.

[0002]

2. Description of the Related Art A fixing device using a thin heat-resistant film,
As shown in FIG. 2, a nip 36 is formed by the heating unit 31 and the pressure roller 32, and the recording sheet S passed through the nip 36 is heated and pressed to fix an image on the sheet.

In this apparatus, a semicircular inflection portion 37 which is continuous in the width direction of the recording sheet S is provided downstream of the nip portion of the stay 33 of the heating unit 31 so that the curvature of the thin heat-resistant film 34 is reduced. By partially increasing the size, the recording sheet S that has passed through the nip is separated from the thin heat-resistant film 34. Further, a fixing device cover 35 is provided to prevent a user from directly touching the heating unit 31 and the pressure roller 32.

Conventionally, as shown in FIG. 3, when a jam occurs for some reason and the recording sheet S is in an accordion state in the fixing device cover 35, the destination on the rear end side of the recording sheet S is narrowed, and the recording sheet S is narrowed. S and thin heat-resistant film 34
Cannot be separated, and the thin heat-resistant film 34 and the recording sheet S are kept in close contact with each other via the toner.
4 may rotate and the recording sheet S may enter the nip portion 36 again. Then, the rear end of the recording sheet S and the portion that has reentered the nip portion 36 are adhered by toner as shown in FIG.

Therefore, the gap t between the downstream side of the heating unit 31 and the downstream wall of the fixing device cover 35 is narrowed to prevent the recording sheet S from winding around the thin heat-resistant film.

[0006]

However, even if the gap t is set to be small as described above, if the thin heat-resistant film 34 and the recording sheet S are difficult to separate, for example, when the print density on the recording sheet S is high, As shown in FIG. 5, the thin heat-resistant film 34 is pushed by the recording sheet S in the accordion state due to the jam and escapes in a direction to widen the gap t with the fixing device cover 35, and the recording sheet S passes through the gap t. In some cases, they were bonded in a loop as shown in FIG.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an image heating apparatus and an image forming apparatus which can prevent a recording material from being wound around a film and can easily perform jam processing. And

[0008]

An image heating apparatus and an image forming apparatus according to the present invention have the following features to solve the above-mentioned problems.

[1] A heating unit which is supported by a stay and heats a recording material via a rotatable cylindrical film, and a pressing member which forms a nip portion with the heating unit and presses the recording material. In an image heating apparatus that heats an image on a recording material by transporting the recording material while rotating the film while nipping the recording material at the nip portion, a separation claw that can be separated from and attached to the film of the heating unit; An image heating apparatus comprising a recording material wrap detecting member, wherein when the wrap detecting member detects the wrapping of the recording sheet around the film, the leading end of the separation claw contacts the film.

[2]: A separation inflection portion for separating the film and the recording material is provided downstream of the nip portion of the stay, and the separation claw contacts the film downstream of the separation inflection portion. The image heating device according to [1].

[3] The method according to [1] or [2], wherein a cover for preventing contact with the heating unit and the pressure roller is provided, and the separation claw is arranged between the cover and the film. Image heating equipment.

[4]: The separating claw and the winding detecting member are integrally formed so as to be rotatable about a rotation axis. When the recording material starts to be wound on the film, the recording material is wound. The image heating apparatus according to [1], [2], or [3], wherein the image heating apparatus rotates about the rotation axis by abutting on a detection member, and causes the separation claw to contact the film by this rotation.

[5]: The winding detection member is a rotatable member having a rotation axis near the film of the heating unit, and has a stopper for fixing the separation claw at a predetermined position. When the detecting member detects the winding of the recording material on the film, the detecting member rotates around the rotation axis, the stopper comes off, the tip of the separation claw contacts the film, and the wound recording material is separated [ The image heating device according to [1], [2] or [3].

[6]: The winding detection member and the separation claw are arranged so that the recording material separated from the film by the separation claw does not apply a force in a direction in which the separation claw separates from the film [1]. Or any one of [5]
Item 10. The image heating device according to item 1.

[7] The image heating apparatus according to any one of [1] to [6], wherein the separation claw contacts a slack portion of the film.

[8]: After removing the wound recording material,
The image heating apparatus according to any one of [1] to [7], wherein the separation claw is automatically separated from the film.

[0017]

[9]: After removing the wound recording material,
The image heating apparatus according to any one of [1] to [7], wherein the separation claw is separated from the film by a spring or its own weight.

[10]: The heat treatment is a process for thermally fixing an image on a recording material to the recording material [1] to [1].

The image heating apparatus according to any one of [9].

[11] In an image forming apparatus having an image forming means for forming an image on a recording material and an image heating means for heating the image on the recording material, [1] as the image heating means
An image forming apparatus, comprising the image heating device according to any one of the above items [10] to [10].

<Operation> As described above, the separation claw is brought into contact with the film when the winding of the recording material is detected by the winding detection means, and the contact between the separation claw and the film is made only when necessary. By doing so, it is possible to prevent the recording material from wrapping around the film when a jam occurs without causing the film to be scratched or excessively worn, and to easily perform the jam processing.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment An image heating apparatus to which the present invention is applied and an image forming apparatus equipped with the same as a fixing device will be described below with reference to the drawings. FIG. 1 is a schematic sectional view showing a schematic configuration of an electrophotographic printer as the image forming apparatus.

First, a schematic configuration of an electrophotographic printer will be described with reference to FIG. As shown in FIG. 1, the electrophotographic printer 1 uses the charging roller 5 to uniformly charge the surface of the photosensitive drum 2. Next, the laser beam L is irradiated onto the photosensitive drum via the mirror 4 by the laser scanner 3 to image-expose the target image to form a latent image.

Next, the latent image is developed by applying the toner 8 in the developing device 6 onto the surface of the photosensitive drum via the developing roller 7 to form a toner image. On the other hand, the recording sheets (recording material) S stacked on the paper feed tray 13 are fed one by one by the paper feed roller 12 and the separation pad, and sent to the transport roller pair 11. The recording sheet S is sent from the conveying roller pair 11 to a portion (transfer nip portion) where the transfer roller 10 and the photosensitive drum 2 are opposed to each other, and a transfer bias is applied from the transfer roller 10 to transfer the toner image on the photosensitive drum surface to the recording sheet S. Transcribed above.
The toner 8 transferred to the recording sheet S is fixed by the fixing device 16, and the recording sheet S is discharged out of the main body of the electrophotographic printer by the discharge roller pair 17. On the other hand, photosensitive drum 2
After the transfer, the toner 8 remaining after the transfer is cleaned by the cleaner 9 and the process proceeds to the next stage.

Next, the fixing unit will be described. FIG. 6 is a schematic sectional view of a fixing unit according to the embodiment of the present invention. In the figure, H is a planar heater (ceramic heater in this example) that generates heat when energized, 34 is a thin cylindrical heat-resistant film that is in sliding contact with the heater H, and 33 is a heater that supports the heater H with the heating surface facing downward. In addition, it is a support member (stay) that rotatably supports the thin heat-resistant film 34, and these elements H, 33, and 34 constitute the heating unit 31 of this example. Reference numeral 32 denotes a pressing member (pressing roller) that forms a nip portion 36 by pressing against the heating unit 31.
The pressure roller 32 is driven by a driving means (not shown) to rotate in the counterclockwise direction indicated by an arrow a, and the film 3
4 is driven in the direction of arrow a '.

The recording sheet S on which the toner image has been formed is introduced into the nip 36 by the above-described image forming means including the photosensitive drum 2, the laser scanner 3, the developing device 6, and the transfer roller 10. The toner image is heat-fixed to the recording sheet S by the heat from the heater H via the film 34 and the nip pressure.

In such a configuration, if the recording sheet S is not conveyed earlier than the paper discharge roller pair 17 for some reason, the recording sheet S is set inside the fixing device cover 35 and the paper discharge roller pair 1.
Between the nip portion 36 and the nip portion 36, the recording sheet S becomes accordion-like, and the destination of the recording sheet S becomes narrower. When the recording sheet S is further conveyed, the recording sheet S and the thin heat-resistant film 34 are not separated by the separating inflection portion 37, and the recording sheet S is
And starts to wind around.

When the recording sheet S that has begun to wind passes through the gap between the fixing device cover 35 and the thin heat-resistant film 34, the winding detection member 40 rotates clockwise about the rotation axis C1, and the tip of the separation claw 41 is moved. It comes into contact with the slack portion of the thin heat-resistant film 34 (the portion floating from the stay 33 on the downstream side of the inflection portion). When the recording sheet S wound around the thin heat-resistant film is further conveyed, the recording sheet S and the thin heat-resistant film 34 are separated by the separating claws 41 as shown in FIG. The separated recording sheet S loses its place to go and becomes a smaller accordion state and accumulates in the gap between the heating unit 31 and the pressure roller 32, or the thin heat-resistant film 34 slips because there is no space for conveying the recording sheet S. Then, the conveyance of the recording sheet S stops.

After the jam has been cleared, the winding detection member 40 and the separation claw 41 are automatically moved to their normal positions by the weight of the winding detection member 40 (the detection member 40 reaches the lowest point and the separation claw 41 separates from the film 34). Position).

The separation claw 41 is placed on a thin heat-resistant film.
It is arranged at more than three places, preferably at a plurality of places (three places in the example of the figure) as shown in FIG.

As described above, according to this embodiment, at the time of normal fixing, the winding detection member and the separation claw are arranged without contacting the thin heat-resistant film, and detect that the recording sheet has begun to wind around the thin heat-resistant film. For the first time, the separation claw comes into contact with the thin heat-resistant film, so that no unnecessary force is applied to the thin heat-resistant film, and the thin heat-resistant film is not scratched or excessively abraded. Can be prevented, and the user can perform jam processing according to the procedure.

<Second Embodiment> Next, a second embodiment will be described with reference to FIG. FIG. 9 is a schematic sectional view of the vicinity of the fixing device according to the second embodiment of the present invention. This embodiment is different from the above-described embodiment in that a recording material separated from a film is configured so that no force is applied to the separation claw in a direction away from the film, and other configurations are the same. For this reason, the same elements are given the same reference numerals, and the description thereof is partially omitted.

If the recording sheet S is not conveyed beyond the discharge roller pair 17 for some reason, the fixing device cover 35
Inside, and between the discharge roller pair 17 and the nip portion 36, the recording sheet S becomes accordion-like from the discharge roller pair 17 side, and the destination of the recording sheet S narrows.
When the recording sheet S is further conveyed, the thin heat-resistant film 34
Nip 3 of stay 33 that supports and regulates the shape
(6) The recording sheet S and the thin heat-resistant film 34 are not separated by the separation inflection portion 37 of the thin heat-resistant film 34 regulated by the semicircular inflection portion that is continuous in the paper width direction on the downstream side, and Then, the recording sheet S comes into close contact with the thin heat-resistant film 34 and starts to be wound.

When the wound recording sheet S passes through the gap between the fixing device cover 35 and the thin heat-resistant film 34, the recording sheet S is pushed by the recording sheet S and the winding detection member 40 rotates the rotation axis C.
Rotating clockwise around l, the tip of the separation claw 41 contacts the thin heat-resistant film 34. Further, when the recording sheet S is conveyed while being wound on the thin heat-resistant film, the recording sheet S and the thin heat-resistant film 34 are separated by the separation claws 41 as shown in FIG. The separated recording sheet S stays in the separation claw portion and the pocket portion of the fixing cover 35 as shown in FIG. At this time, if the separation claw 41 is arranged as shown in FIG. 11, the recording sheet S separated from the thin heat-resistant film applies a force F to the separation claw 41 in a direction away from the counterclockwise thin heat-resistant film 34. In addition, the contact force between the thin heat-resistant film 34 and the separation claw 41 is not stable. This is because the separation claw 41 'has the rotation axis C
Assuming that the direction of rotation toward the film 34 with respect to 1 is f and the direction of rotation away from the film 34 is b, the surface 41'a facing the rotation direction f and the surface 41'b facing the rotation direction b The separation claw 41 'comes into contact with the recording sheet S on the two surfaces. When the force applied to the surface 41'b becomes larger than the force applied to the surface 41'a, the separation claw 41' is separated from the film 34. This is because the directional force F acts.

Therefore, in this embodiment, as shown in FIGS. 10 and 12, when the tip of the separation claw contacts the film 34, the surface facing the rotation direction b, that is, the direction in which the separation claw 41 is released when the recording sheet S comes into contact. The surfaces 41b and 41c where the force is generated are located at the same or slightly outside of the inner surface of the fixing device cover 35, and the recording sheet S separated by the separation claw 41 is received by the fixing device cover 35, so that a counterclockwise force is not applied. By arranging the separation claws 41 as described above, the contact between the thin heat-resistant film 34 and the separation claws 41 is stabilized.

The separated recording sheet S loses its place to go,
It becomes a smaller accordion state and the heating unit 3
The thin heat-resistant film 34 slips due to accumulation in the gap between the pressure roller 1 and the pressure roller 32 or the space for conveying the recording sheet S runs out, and the conveyance of the recording sheet S stops.

After the jam has been cleared, the winding detection member 40 and the separation claw 41 automatically return to their normal positions due to the weight of the winding detection member 40 or the force of the spring 39 as shown in FIG.

The separating claw 41 is placed on a thin heat-resistant film.
There are more than one locations.

As described above, according to this embodiment, at the time of normal fixing, the winding detection member and the separation claw are arranged without contacting the thin heat-resistant film, and detect that the recording sheet has begun to wind around the thin heat-resistant film. For the first time, the separation claw comes into contact with the thin heat-resistant film, the separation force from the thin heat-resistant film and the separation claw by the recording sheet S separated from the thin heat-resistant film is not applied, and a stable contact force is obtained. This eliminates the need to apply force, prevents the thin heat-resistant film from being scratched or excessively abraded, prevents the thin heat-resistant film from being wound around with a simple mechanism, and enables the user to perform the jam processing according to the procedure.

Third Embodiment Next, a third embodiment will be described with reference to FIG. FIG. 14 shows a third embodiment of the present invention.
FIG. 4 is a schematic cross-sectional view of the vicinity of a fixing device according to the embodiment. This embodiment is different from the above-described embodiment in that when the winding detection member detects the winding of the recording material, the stopper comes off and the tip of the separation claw comes into contact with the film, and the other configuration is the same. For this reason, the same elements are given the same reference numerals, and the description thereof is partially omitted.

If the recording sheet S is not conveyed earlier than the discharge roller pair 17 for some reason, the fixing device cover 35
Inside, and between the discharge roller pair 17 and the nip portion 36, the recording sheet S becomes accordion-like from the discharge roller pair 17 side, and the destination of the recording sheet S narrows.
When the recording sheet S is further conveyed by the fixing device formed by the heating unit 31 and the pressure roller 32, the thin sheet 34 is supported by the thin heat-resistant film 34, and the shape thereof is regulated. Inflection portion 37 of thin heat-resistant film 34 regulated by semicircular inflection portion
As a result, the recording sheet S and the thin heat-resistant film 34 are not separated, and the recording sheet S comes into close contact with the thin heat-resistant film 34 via the toner and starts to wind.

When the recording sheet S that has begun to wind passes through the gap between the fixing device cover 35 and the thin heat-resistant film 34, the winding detection member 40 rotates clockwise about the rotation axis Cl as shown in FIG. The stopper holding the separation claw 41 at a height not in contact with the thin heat-resistant film comes off, and the separation claw 41 is in a free state, rotates clockwise around the rotation axis C2, and the tip of the separation claw 41 has its own weight or The thin heat-resistant film 34 is brought into contact with the thin heat-resistant film 34 at a constant force by a spring force. Further, when the recording sheet S is conveyed while being wound on the thin heat-resistant film, the recording sheet S and the thin heat-resistant film 34 are separated by the separating claws 41 as shown in FIG. The separated recording sheet S loses its place to go and becomes a smaller accordion state and accumulates in the gap between the heating unit 31 and the pressure roller 32, or the thin heat-resistant film 34 slips because there is no space for conveying the recording sheet S. Then, the conveyance of the recording sheet S stops.

After the jam has been cleared, the winding detection member 40 returns to the normal position by its own weight, so that a force is applied to the stopper portion of the separation claw 41 counterclockwise around the rotation axis C2,
The separation claw 41 separates from the thin heat-resistant film 34 and returns to the normal position.

The separation claw 41 is arranged so as to be in contact with the film at one place or at a plurality of places in the width direction of the recording material.

As described above, according to this embodiment, at the time of normal fixing, the winding detection member and the separation claw are arranged without contacting the thin heat-resistant film, and detect that the recording sheet has begun to wind around the thin heat-resistant film. When the stopper supporting the separation claw is released, the separation claw contacts the thin heat-resistant film for the first time. Since the separation claw with the stopper removed is in a free state, a constant contact force can be obtained by its own weight or spring force, so that unnecessary force is not applied to the thin heat-resistant film, and the thin heat-resistant film is scratched or excessively worn. Without wrapping around a thin heat-resistant film with a simple mechanism,
It becomes possible for the user to perform jam processing according to the procedure.

Also in this embodiment, the surface of the separation claw 41 which is in contact with the recording sheet S and in which the force is applied in the direction away from the film 34 is arranged at the same or slightly outside the inner surface of the fixing device cover. The winding detection member and the separation claw may be arranged so that a force is not applied in a direction away from 34.

As shown in FIG. 16, a receiving member 35a for receiving the recording sheet S inside the inner surface 41d of the separation claw 41 at the time of contact with the film 34 is fixed to the fixing device cover 35 adjacent to the separation claw 41. In this case, the separation claw 41 may be configured so that a force in the direction in which the separation claw 41 is separated from the film 34 is not applied.

<Others> In the above embodiment, an example was described in which a ceramic heater was used as the heat source of the heating unit. However, the present invention is not limited to this, and the magnetic force from the exciting coil 42 is increased as shown in FIG. An electromagnetic induction heating type device that acts on a film 34 ′ having a heat generating layer made of a magnetic material to generate an induced current and heat it may be used.

In the above embodiment, the winding detecting means and the separating claw are linked to each other. However, the present invention is not limited to this. It is also possible to adopt a configuration in which the detection is performed, and the separation claw is brought into contact with or separated from the film using a drive source such as a solenoid.

[0049]

As described above, according to the present invention, it is possible to provide an image heating apparatus and an image forming apparatus which can prevent a recording material from being wound around a film and can easily carry out jam processing.

[Brief description of the drawings]

FIG. 1 is a schematic side sectional view showing a schematic configuration of an electrophotographic printer.

FIG. 2 is a schematic side sectional view of a conventional example.

FIG. 3 is a schematic side sectional view showing a state where a recording sheet is wound around a heating unit.

FIG. 4 is an explanatory view showing a state in which the toner on the wound recording sheet and the toner on the recording sheet before fixing are adhered to each other;

FIG. 5 is a schematic cross-sectional view showing a state where a recording sheet has begun to be wound by deforming a thin heat-resistant film.

FIG. 6 is a schematic side sectional view according to the first embodiment of the present invention.

FIG. 7 is a schematic side sectional view according to the first embodiment of the present invention.

FIG. 8 is a schematic diagram showing the arrangement of the separation claw according to the present invention in the film longitudinal direction (recording material width direction).

FIG. 9 is a schematic side sectional view according to a second embodiment of the present invention.

FIG. 10 is a schematic side sectional view according to a second embodiment of the present invention.

FIG. 11 is a schematic view showing that a force is applied in a direction in which the separation claw is separated.

FIG. 12 is a schematic view according to a second embodiment of the present invention.

FIG. 13 is a schematic side sectional view according to a second embodiment of the present invention.

FIG. 14 is a schematic side sectional view according to a third embodiment of the present invention.

FIG. 15 is a schematic side sectional view according to a third embodiment of the present invention.

FIG. 16 is a schematic side sectional view according to a third embodiment of the present invention.

FIG. 17 is a schematic side sectional view showing another embodiment of the image heating apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrophotographic printer 2 Photosensitive drum 3 Laser scanner 4 Mirror 5 Charging roller 6 Developing device 7 Developing roller 8 Toner 9 Cleaner 10 Transfer roller 11 Conveyance roller pair 12 Paper feed roller 13 Paper feed tray 16 Fixing device 17 Discharge roller pair 31 Heating Unit 32 Pressure roller 33 Stay 34 Film (thin heat-resistant film) 35 Fixer cover 36 Nip part 37 Separation inflection part 38 Secondary separation inflection part 39 Spring 40 Winding detection member 41 Separation claw C1, C2 Rotating axis H Heater S Recording sheet (recording material) t Clearance between fuser cover and thin heat-resistant film

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H033 BA16 BA21 BA22 BE03 CA22 CA26 2H072 AA02 AA16 AA22 AB20 CA01 CB06 EA11 3F053 AA19

Claims (11)

[Claims] 1. A heating unit which is supported by a stay and heats a recording material via a rotatable cylindrical film, and a pressing member which forms a nip portion with the heating unit and presses the recording material. An image heating apparatus that heats an image on a recording material by nipping the recording material at the nip portion and conveying the recording material together with the rotation of the film;
An image heating apparatus comprising a recording material wrap detecting member, wherein when the wrap detecting member detects the wrapping of the recording sheet around the film, the leading end of the separation claw contacts the film. 2. The apparatus according to claim 1, further comprising: a separation inflection portion for separating the film and the recording material downstream of the nip portion of the stay, wherein the separation claw contacts the film downstream of the separation inflection portion. 2. The image heating device according to 1. 3. The image heating apparatus according to claim 1, further comprising a cover for preventing contact with the heating unit and the pressure roller, wherein the separation claw is arranged between the cover and the film. . 4. A member in which the separation claw and the winding detection member are integrally formed so as to be rotatable around a rotation axis,
When the recording material starts winding around the film, the recording material rotates around the rotation axis by hitting the winding detection member,
4. The image heating apparatus according to claim 1, wherein the rotation causes the separation claw to contact the film. 5. The winding detection member is a rotatable member having a rotation axis near a film of a heating unit, and has a stopper for fixing a separation claw at a fixed position,
When the winding detecting member detects the winding of the recording material around the film, the recording material rotates around the rotation axis, the stopper comes off, the tip of the separation claw comes into contact with the film, and the wound recording material is separated. The image heating device according to claim 1, 2, or 3. 6. The winding detection member and the separation claw are arranged so that a force is not applied in a direction in which the separation claw is separated from the film by the recording material separated from the film by the separation claw. The image heating apparatus according to any one of claims 1 to 4. 7. The image heating apparatus according to claim 1, wherein the separation claw contacts a slack portion of the film. 8. The image heating apparatus according to claim 1, wherein after the wound recording material is removed, the separation claw automatically separates from the film. 9. The image heating apparatus according to claim 1, wherein the separation claw is separated from the film by a spring or its own weight after the wound recording material is removed. 10. The image heating apparatus according to claim 1, wherein the heating process is a process of thermally fixing an image on a recording material to the recording material. 11. An image forming apparatus comprising: an image forming means for forming an image on a recording material; and an image heating means for heating the image on the recording material, wherein the image heating means is used as the image heating means. An image forming apparatus comprising the image heating device according to claim 1.