JP2003316198A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device which can prevent winding of recording paper around both rollers without adversely affecting images with a simple structure. <P>SOLUTION: The fixing device comprises a pressurizing roller and a fixing roller, in which the surface potential E1 of the fixing roller, the surface potential E2 of the pressurizing roller and the surface potential E of recording paper have the relation |E2-E3|>|E1-E3| and a rubber base configurating the surface layer of the pressurizing roller is provided with means for preventing the winding of the recording paper around the roller. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device incorporated in an electrophotographic apparatus such as a copying machine, a facsimile machine, a printer or the like, for thermally fixing an unfixed toner image.

[0002]

2. Description of the Related Art In a fixing device composed of a fixing roller and a pressure roller, the recording paper passing through the nip portion of both rollers may be wound around one of the rollers. In order to add up such a problem, a separation claw has been conventionally used to prevent the recording paper from being wrapped around the roller.

Also, a technique for preventing wrapping with a simpler mechanism has been proposed. Japanese Unexamined Patent Application Publication No. 6-11986 proposes a technique for preventing the recording paper from sticking by the restoring action of the protrusion member attached to the fixing roller.

[0004]

In the above-mentioned prior art, the projections have an adverse effect on the image because they are on the image forming surface. Further, there is a problem that no effect is obtained when the recording paper is wrapped around the pressure roller.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a fixing device which has a simple structure and can prevent the recording paper from being wrapped around both rollers without adversely affecting the image.

[0006]

In order to achieve the above-mentioned object, the invention according to claim 1 is a fixing device comprising a pressure roller and a fixing roller, and a surface potential E1 of the fixing roller.
And the surface potential E2 of the pressure roller and the surface potential E of the recording paper.
3 has a relationship of | E2-E3 |> | E1-E3 |,
The most main feature is a fixing device in which a recording paper wrapping preventing means is provided on a rubber base that constitutes the surface layer of the pressure roller.

According to a second aspect of the present invention, in the fixing device according to the first aspect, the recording paper wrapping preventing means is a fixing device which is integrally formed on the rubber base and is an appropriate number of peeling pieces that are biased outward. The main feature.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a fixing device according to an embodiment of the present invention. This fixing device comprises a pressure roller 1 and a fixing roller 2.

In the pressure roller 1, a rubber base 12 having a wall thickness of 1 to 40 mm is formed on the surface layer of a mandrel 11.
In the fixing roller 2, a fixing layer 22 made of rubber, resin or the like is formed on the surface layer of a cored bar 21 having a diameter of 15 to 30φ. The toner image on the recording paper P is melted and fixed in the process of passing the recording paper P through the nip portion of the pressure roller 1 and the fixing roller 2 (the linear pressure is set to 50 to 500 g).

On the surface of the rubber base 12 of the pressure roller 1, a suitable number of peeling pieces 12-1 that are biased outward are integrally formed on the surface of the rubber base 12, as shown in the portion A. The elastic force of the peeling piece 12-1 is smaller than the nip pressure. Therefore, the peeling piece 12-1 becomes horizontal against its own elastic force due to the pressure in the nip portion as shown in the portion B. When the nip portion is separated, as shown in the portion A, the rubber base 12 is urged outward so as to project from the surface of the rubber base 12. Further, the elastic force of the peeling piece 12-1 is larger than the winding force of the recording paper P around the pressure roller 1.

In the present invention, the surface potential E1 of the fixing roller 2, the surface potential E2 of the pressure roller 1, and the surface potential E3 of the recording paper P are | E2-E3 |> | E1-E3.
Have a relationship of |. Therefore, the recording paper P is the pressure roller 1
Try to get around. In other words, the recording paper P is forced to move toward the pressure roller 1.

However, as described above, the peeling piece 12-1
Is urged outward so as to project from the surface of the rubber base 12 as shown in the section A when leaving the nip portion.
The recording paper P which is about to be wound around the pressure roller 1 can be peeled off by the urging force.

[0013]

As described above, according to the present invention,
In a fixing device including a pressure roller and a fixing roller, a surface potential E1 of the fixing roller and a surface potential E2 of the pressure roller
And the surface potential E3 of the recording paper are | E2-E3 |> | E1
-E3 | and the recording paper wrapping preventing means for the rubber base forming the surface layer of the pressure roller, specifically, an appropriate number of peeling pieces that are integrally formed on the rubber base and are urged outward. Since it is provided, it is possible to prevent the recording paper from being wrapped around both rollers with a simple structure without adversely affecting the image.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a fixing device according to an embodiment of the present invention.

[Explanation of symbols]

1 pressure roller 11 Shinkin 12 rubber base 12-1 Peeling piece 2 fixing roller 21 Shinkin 22 Fixing layer

Claims (2)

[Claims] 1. In a fixing device including a pressure roller and a fixing roller, a surface potential E1 of the fixing roller, a surface potential E2 of the pressure roller, and a surface potential E3 of the recording paper are | E2-.
A fixing device having a relationship of E3 |> | E1-E3 |, wherein a recording paper wrapping preventing means is provided on a rubber base forming a surface layer of the pressure roller. 2. The fixing device according to claim 1, wherein the recording paper wrapping prevention means is a proper number of peeling pieces that are integrally formed on the rubber base and are urged outward.