JP2002023540A - Belt fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably fix toner to a recording medium by suppressing the deformation or breakage of an end part of a belt wound around a pressure roller as the belt shifts and abuts against a restriction member for the pressure roller when the toner is fixed to the recording medium by moving the belt by the pressure roller and also pressing it against the recording medium supplied with the toner. SOLUTION: The endless belt 20 is extended between the pressure roller 10 having its roller part 11 made of an elastic material and at least another roller 31 or 32. Restriction members 13 which restrict the deviation of the belt are provided at both the sides of the roller part of the pressure roller. The belt is moved as the pressure roller rotates and also pressed against the recording medium 34 supplied with the toner (t) which is fixed to the recording medium. Grooves 12 which extend along the axis of the pressure roller are cut and formed on the outer peripheral surface of the roller part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used for fixing toner supplied on a recording medium to a recording medium in an image forming apparatus such as a copying machine or a printer. A regulating member that wraps the resulting belt over a pressing roller whose roller portion is made of an elastic material and at least one other roller, and that restricts the displacement of the belt on both sides of the roller portion in the pressing roller. A belt fixing device that moves the belt with the rotation of the pressing roller and presses the belt onto a recording medium supplied with toner by the pressing roller to fix the toner on the recording medium. It is about.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, toner is supplied onto a recording medium, and the toner is fixed on the recording medium by a fixing device.

Here, as such a fixing device, conventionally, a fixing device composed of a pair of rollers composed of a heating roller and a pressure roller whose outer peripheral portion is generally formed of an elastic body is used. The recording medium supplied with the toner is guided between the rollers, and the toner is heated and pressed between the pair of rollers to fix the toner on the recording medium.

On the other hand, in recent years, the speed of the image forming apparatus as described above has been increased, and it has become necessary to sufficiently fix toner on a recording medium at a high speed in a fixing apparatus, and in a full-color image forming apparatus. In this method, a toner layer of a plurality of colors is supplied onto a recording medium to increase the thickness of the toner layer, and it is necessary to sufficiently fix the toner having such a thickened layer to the recording medium.

Here, in order to sufficiently fix the toner on the recording medium at a high speed in the fixing device as described above, or to sufficiently fix the toner having a thick layer on the recording medium, the pair of rollers described above is used. In the meantime, it is necessary to increase the width of the nip portion for heating and pressing the toner.

[0006] In the above fixing device,
In order to increase the width of the nip portion, a method of increasing the diameter of the pair of rollers or increasing the thickness of the elastic body at the outer peripheral portion of the heating roller can be considered.

However, when the diameter of the roller is increased as described above, there are problems that the fixing device becomes large, the recording medium is easily wound around the roller, and the elastic body at the outer peripheral portion of the heating roller becomes thick. In this case, heat is not easily transmitted to the surface of the heating roller, and the toner cannot be sufficiently heated by the heating roller. To heat it sufficiently
There has been a problem that a large amount of power is required and the cost is high.

For this reason, in recent years, FIG.
As shown in (B), an endless belt 2 is wound around a pressing roller 1 having a roller portion 1a made of an elastic material and another roller 5, and the belt 2 is moved by the rotation of the pressing roller 1. At the same time, the belt 2 is pressed against a pressing roller 3 provided opposite to the pressing roller 1, and the recording medium 4 supplied with the toner t is guided between the belt 2 and the pressing roller 3. A belt fixing device in which the belt 2 is pressed against the recording medium 4 to which the toner t is supplied by the pressing roller 1, and the toner t is fixed to the recording medium 4 at a nip portion between the belt 2 and the pressing roller 3. A device has been proposed.

Here, in such a belt fixing device, the pressing roller 1 on which the belt 2 is stretched as described above is used.
When the belt 2 is not parallel to the other roller 5 or when the belt 2 is pressed by the pressing roller 1, the position of the belt 2 stretched over the pressing roller 1 may be caused by various factors such as uneven pressing force. The belt 2 meanders,
The belt 2 may come off from the pressing roller 1.

For this reason, in the belt fixing device as described above, generally, as shown in FIG. 1B, regulating members 1b for regulating the displacement of the belt 2 are provided on both sides of the roller portion 1a of the pressing roller 1. Was like that.

However, when the regulating member 1b is provided in this manner, the end of the belt 2 which is displaced is connected to the regulating member 1b.
And the end of the belt 2 rides on the regulating member 1b to be deformed or the end of the belt 2 is damaged.

[0012]

According to the present invention, an endless belt is wound around a pressing roller having a roller portion made of an elastic material and at least one other roller, and a roller in the pressing roller is provided. A regulating member for regulating the displacement of the belt is provided on both sides of the unit, and the belt is moved with the rotation of the pressing roller, and the belt is pressed onto the recording medium supplied with the toner by the pressing roller. It is an object of the present invention to solve the above-described problems in a belt fixing device configured to fix toner on a recording medium.

That is, in the present invention, in the above-described belt fixing device, even if the position of the belt stretched over the pressing roller is shifted and the belt hits the regulating member provided on the pressing roller, The end of the belt does not continue to be strongly pressed against the regulating member, so that the end of the belt is suppressed from being deformed or damaged, and the toner can be stably fixed to the recording medium for a long period of time. It is an object to do so.

[0014]

In the belt fixing device according to the present invention, in order to solve the above-mentioned problems, an endless belt is formed by at least one pressing roller having a roller portion made of an elastic material. Along with the other roller, a regulating member for regulating the displacement of the belt is provided on both sides of the roller portion of the pressing roller,
In a belt fixing device that moves the belt with the rotation of the pressing roller and presses the belt onto a recording medium supplied with toner by the pressing roller to fix the toner on the recording medium, the pressing roller Is provided with a cut groove extending in the axial direction on the outer peripheral surface of the roller portion.

Here, in the belt fixing device according to the present invention, as described above, the pressing roller over which the belt is stretched is not parallel to the other roller, or the belt is placed on the recording medium to which toner is supplied by the pressing roller. Press
In fixing the toner to the recording medium, the position of the belt stretched over the pressing roller shifts due to various factors such as uneven pressing force as described above, and the end of the belt is restricted by the regulating member. Even if it hits, when the portion of the kerf provided in the roller portion of this pressing roller is separated from the portion in contact with the belt, the force acting on the roller portion is released at this kerf portion, The roller portion that has been deformed unevenly is restored to the original state.

Therefore, the end of the belt does not keep being strongly pressed against the regulating member, and the end of the belt is prevented from riding on the regulating member and being deformed or damaged, and is stable for a long period of time. As a result, the toner can be fixed on the recording medium.

Here, in the belt fixing device according to the present invention, when the kerf portion provided on the roller portion separates from the portion in contact with the belt as described above, the force acting on the roller portion is reduced. Since the roller portion which has been released at the cut groove portion and the unevenly deformed roller portion is restored to the original state, the axial direction as described above is performed so that such restoration is quickly performed. It is preferable that a plurality of extended cut grooves are provided in the circumferential direction of the pressing roller at a required interval.

In the belt fixing device according to the present invention, if the width of the cut groove provided in the roller portion of the pressing roller is too large, when the pressing roller presses the belt against the recording medium supplied with toner, The force of pressing the belt against the recording medium at the portion of the kerf decreases, and the pressing force of the belt against the recording medium becomes uneven, making it impossible to perform a fixed fixing. It is preferable that the width be equal to or less than 1/10 of the width of the nip portion for pressing the medium.

In the belt fixing device according to the present invention, if the heating device for heating the belt is provided separately from the pressing roller, the thickness of the roller portion made of an elastic material in the pressing roller is increased, so that the belt can record. The width of the nip portion for pressing the medium can be increased, the belt can be appropriately heated by the heating device, the toner can be sufficiently fixed on the recording medium at a high speed, and the full-color image formation can be performed. Even when a plurality of color toners are supplied onto the recording medium and the toner layer becomes thicker as in the case of the apparatus, the toner having such a thicker layer can be sufficiently fixed on the recording medium.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a belt fixing device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings, specific examples will be given, and the belt fixing device in the embodiment of the present invention will be described. It will be clarified by using a comparative example that deformation and breakage of the end portion of the belt when used are suppressed.

In the belt fixing device according to this embodiment, as shown in FIG. 2, a roller portion 1 made of an elastic material such as a silicone rubber foam is used as the pressing roller 10.
A plurality of cutting grooves 12 are provided on the outer peripheral surface of the pressing roller 10 along the axial direction at required intervals in the circumferential direction, and the pressing roller 10 has a diameter smaller than that of the roller portion 11 on both sides of the roller portion 11. Is attached to the regulating member 13 whose size has become larger.

In this embodiment, as shown in FIG. 3, the roller portion 1 of the pressing roller 10 described above is used.
An endless belt 20 is wrapped around the outer periphery of the belt 1, and the endless belt 20 is connected to a heating roller 31 provided with a heating means (not shown) such as a heater lamp therein and another heating roller 31. The guide roller 32 is stretched over.

The belt 20 wrapped around the roller portion 11 of the pressing roller 10 as described above is
0 to the pressing roller 33, and the pressing roller 1
The roller portion 11 is deformed so that the belt 20 contacts the pressure roller 33 with an appropriate nip width.

When the toner t supplied to the recording medium 34 is fixed to the recording medium 34 by the belt fixing device in this embodiment, the pressing roller 10 is rotated to move the belt 20 to the pressing roller 10. The belt 20 is heated to an appropriate temperature by the heating roller 31 while being circulated through the heating roller 31 and the guide roller 32.

The belt 20 thus heated is
The recording medium 34 to which the toner t is supplied is guided between the belt 20 and the pressure roller 33 so that the toner t contacts the recording medium. The toner t on the heating roller 34 is heated and pressed to fix the toner t on the recording medium 34.

Here, in the belt fixing device of this embodiment, the pressing roller 10, the heating roller 31, and the guide roller 32, around which the belt 20 is laid as described above, are not provided in parallel. When pressed against the pressing roller 33, the roller portion 11 of the pressing roller 10 is not uniformly deformed, and the belt 20 stretched over the pressing roller 10 is displaced. Even if one of the regulating members 13 provided on both sides of the roller portion 11 is hit, the pressing roller 10 rotates and the roller portion 1 deformed unevenly.
When the kerf 12 in FIG. 1 moves away from the portion where the belt 20 is in contact, the force acting on the roller portion 11 that has been unevenly deformed by the kerf 12 is released, and the roller portion 11 is returned to its original position. It will be restored to the state.

For this reason, the end of the belt 20 is
3, the end of the belt 20 is prevented from running on the regulating member 13 to be deformed or damaged, and the recording medium 3 is kept for a long time.
4 can stably fix the toner t.

Next, a belt fixing device according to a specific embodiment of the present invention will be described.

In this embodiment, in the belt fixing device of the above embodiment, the pressing roller 10 has an axial length of 235 mm and an outer diameter of 3 mm.
A roller portion 11 made of a silicone rubber sponge having a diameter of 0 mm is provided, and a cutting groove 12 having a width of 0.3 mm and a depth of 4 mm is formed on the outer peripheral surface of the roller portion 11 along the axial direction thereof. A plurality of roller members 11 are provided in the circumferential direction at intervals of 2 mm, and regulating members 13 each having a diameter larger than the diameter of the roller unit are attached to both ends of the roller unit 11.

As the belt 20, an elastic layer made of silicon rubber having a thickness of 200 μm is provided on the outer peripheral surface of a belt base material made of polyimide and having a thickness of 50 μm. Was 650 mm.

As the pressure roller 33, a roller provided with an elastic layer of silicon rubber having a thickness of 2 mm on the outer periphery of the roller portion and having an outer diameter of 30 mm and an axial length of 230 mm was used.

The heating roller 31 has an outer diameter of 1 mm.
A 7 mm, 1 mm thick aluminum tube provided with a heater lamp inside was used.

On the other hand, in the comparative example, a roller in which the outer peripheral surface of the roller portion 11 of the above-mentioned pressing roller 10 was not provided with the cut groove 12 was used.

Then, by using the belt fixing devices of the embodiment and the comparative example, the above-mentioned pressure roller 33 and the pressure roller 10 are respectively rotated to set the feed speed of the above-mentioned belt 20 to 150 mm / sec. The belt 20 was heated to 180 ° C. by the heating roller 31 and the belt 20 was pressed against the pressing roller 33 by the pressing roller 10 with a pressing force of 40 Nf, and a continuous operation was performed for 700 hours.

As a result, in the belt fixing device of the comparative example, when the belt was operated for 500 hours, the end portion of the belt 20 was stretched and deformed. Cracks occurred at the end of No. 20.

On the other hand, in the belt fixing device of the embodiment, even after the continuous operation for 700 hours, the end portion of the belt 20 was not deformed or damaged.

[0037]

As described above in detail, in the belt fixing device according to the present invention, the endless belt is
A roller portion is stretched over a pressing roller made of an elastic material and at least one other roller, and the belt is moved with the rotation of the pressing roller, and the belt is pressed on a recording medium supplied with toner. In fixing the toner to the recording medium by pressing, a cut groove extending in the axial direction is provided on the outer peripheral surface of the roller portion of the pressing roller, so that the pressing roller over which the belt is wound and the other roller are not parallel. When the belt was pressed onto the recording medium to which the toner was supplied by the pressing roller and the toner was fixed on the recording medium, the belt was wrapped around the pressing roller due to various factors such as uneven pressing force. Even if the belt is displaced and the end of the belt hits one of the restricting members provided on both sides of the roller portion, the pressure roller When the kerf provided in the roller portion is separated from the portion in contact with the belt, the force acting on the roller portion that has been deformed unevenly is released at this kerf portion, and the roller portion is released. Now restored to its original state.

As a result, in the belt fixing device of the present invention, the end of the belt does not continue to be strongly pressed against the regulating member, and the end of the belt rides on the regulating member and is deformed or damaged. Therefore, the toner can be stably fixed on the recording medium for a long period of time.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a conventional belt fixing device and a state in which toner is fixed on a recording medium by the belt fixing device.

FIG. 2 is a schematic perspective view of a pressing roller used in the belt fixing device according to the embodiment of the present invention.

FIG. 3 is a schematic explanatory diagram showing a state in which toner is fixed on a recording medium by a belt fixing device according to the embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 pressing roller 11 roller portion 12 kerf 13 regulating member 20 belt 31 heating roller (heating device) 32 guide roller 33 pressure roller 34 recording medium t toner

Continued on the front page F term (reference) 2H033 AA14 BA11 BB12 BB17 BB30 BB37 3J103 AA02 AA64 AA72 AA74 BA31 BA41 FA02 FA05 FA09 FA18 GA02 GA52 GA57 GA58 HA03 HA12 HA18 HA53

Claims (3)

[Claims] An endless belt is wound around a pressing roller whose roller portion is made of an elastic material and at least one other roller, and the belt is provided on both sides of the roller portion in the pressing roller. The belt is moved with the rotation of the pressing roller, and the belt is pressed onto the recording medium supplied with the toner by the pressing roller to fix the toner on the recording medium. A belt fixing device according to claim 1, wherein a cutting groove extending in the axial direction is provided on an outer peripheral surface of a roller portion of said pressing roller. 2. The belt fixing device according to claim 1, wherein a plurality of the cut grooves are provided at predetermined intervals in a circumferential direction of the pressing roller. 3. The belt fixing device according to claim 1, wherein a heating device for heating the belt is provided separately from the pressing roller.