JP2003337481A - Thermal fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a pressure roller from being soiled with paper containing calcium carbonate. <P>SOLUTION: Within a fixing nip, a projection is formed for sharply deforming the surface of the pressure roller. The projection is formed by molding a ceramic heater edge or a heater support body. <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 heating member and a fixing device for heating and fixing a toner image regulated by an electrophotographic method, an electrostatic recording method or the like on a sheet.

[0002]

2. Description of the Related Art Conventionally, a fixing device using this type of heating body has a structure as shown in FIG.

In the figure, 1 is a fixing film, 2 is a heating element, 3
Is a film guide that guides the support of the heating body and the running of the fixing film, and 4 is a pressure roller that is in pressure contact with the heating body via the fixing film to convey the heated member under pressure.

The fixing film 1 has a diameter of 24 mm and a thickness of 50.
A 4 micron primer and a surface Teflon (R) layer 10 micron are laminated on a micron polyimide.

The pressure roller 4 is formed by coating an aluminum core having a diameter of 13 mm with a silicone rubber having a thickness of 3.5 mm, and coating a PFA tube or a fluorine resin or a fluorine latex on the surface layer thereof.

A heating element used in such a fixing device is shown in FIG.

Reference numeral 5 is a ceramic base made of alumina or aluminum nitride. As the heating element pattern 6, silver is mixed with palladium and alloyed, and this is mixed with glass paste and screen-printed. In order to supply power to the heating element, a conductor pattern 7a is formed by screen-printing silver or silver / platinum mixed with glass paste. On the surface of the heating element, in order to improve slidability and dielectric strength,
It has a glass coat.

An electrode 8 is formed at the end of the conductor pattern. A conductor pattern 7b for detecting the thermistor 9 and its resistance is formed on the back surface of the ceramic base material.

[0009]

In such a fixing device, when paper containing a large amount of calcium carbonate, which has been increasing in number in recent years, is passed, toner and paper powder are deposited on the surface of the pressure roller. Then it came out on the paper and caused the problem of smearing the image.

[0010]

According to the present invention, the surface of the pressure roller in the fixing nip is rapidly changed, so that the expansion and contraction of the surface material and the change in curvature are used to fix the toner and the paper powder fixed on the surface. The sediment (hereinafter abbreviated as sediment) is isolated and crushed and discharged onto paper in a size invisible to the naked eye.

Specifically, a method is adopted in which the edge of the heating element projects in the fixing nip to deform the pressure roller.

Alternatively, a method of deforming the pressure roller by projecting a part of the support body holding the heating body in the fixing nip is adopted.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) FIG. 1 is a sectional view of a fixing device used in an embodiment of the present invention. In this example, the downstream end Ne of the nip formed by the pressure roller 4 and the fixing film 1 is located outside the edge E of the heating element. As a result of this, the pressure roller surface is suddenly compressed and deformed in the last part of the nip. For this reason, the deposit that does not have viscoelasticity in the low temperature state is peeled off from the surface of the pressure roller and is crushed by receiving a sudden pressure.

In the experiment, the thickness of the heating element is 0.635 mm
The fixing film used was composed of a 50 micron polyimide base layer and a 5 micron adhesive layer and a 10 micron release layer. The pressure roller is a φ13 aluminum cored bar coated with 3.5 mm thick silicone rubber. The surface of the pressure roller is coated with fluorine latex (trade name GLS213) manufactured by Daikin Industries Co., Ltd. It improves the sex.

The product hardness of this roller is 45 degrees as measured by Asker-C, and the surface is 45 degrees as measured by Micro Hardness Meter MD-1 (Type A Durometer) manufactured by Kobunshi Keiki Co., Ltd. ing. Total pressure is 150N
I did this.

In FIG. 4, the surface hardness of the pressure roller was measured by micro hardness, and the condition under which stains did not appear was represented by the amount of penetration of the heating element edge into the pressure roller.

The amount of invasion can be measured by determining the amount of deformation of the rubber of the pressure roller from the position of the core metal of the pressure roller and the position of the heating body. , It is possible to determine by drawing whether the heating body edge is included.

In the figure, the upper left side is the condition that the pressure roller is not soiled, and the lower right is the condition that it is soiled.

The shaded area is an area where stains on the pressure roller occur suddenly.

Since the surface hardness of the pressure roller changes depending on the thickness of the coat, it is preferable to apply it thinly. However, if it is thin, the abrasion resistance is deteriorated and the release layer is worn away. Further, since uneven coating occurs, a smooth surface cannot be obtained, which is rather bad for stains.

On the other hand, if the surface hardness of the pressure roller is made hard, it becomes difficult to obtain the amount of penetration, and it becomes difficult to deform the surface, so that it is difficult to obtain the effect intended by the present invention.
In addition, the torque for driving the pressure roller also increases.

Therefore, it is necessary to properly select the surface hardness, the pressing force, and the penetration amount of the pressure roller to select a region free from dirt.

FIG. 3 shows the deformed state of the pressure roller in the fixing nip of the conventional example. In the past, the end of the nip was always contained within the width of the heating element, so the surface of the pressure roller was deformed both when entering and exiting the nip, but the change was gradual. .

An embodiment of the present invention and a conventional example. When KymLux paper containing calcium carbonate was passed, stains were accumulated on the pressure roller after 500 sheets in the conventional example, and black spots were generated on the image.

On the other hand, in the example of the present invention, even when 5000 sheets were passed, stains did not accumulate on the pressure roller and no stain was generated on the image.

(Embodiment 2) In this embodiment, as shown in FIG. 2, a protrusion for deforming the pressure roller at the nip portion is provided on the support of the heating element. In the previous embodiment, the edge of the heating element was used, but in that case, abrasion of the fixing film occurs, and scraped polyimide is mixed with grease applied to the inner surface of the fixing film to reduce lubricity, This caused a large variation in sliding resistance such that the fixing film slips. This is because the heating body is made by dividing the ceramic base material by forming the grooves by laser scribing and then dividing the ceramic base material, and the fracture surface is inevitably jagged.

On the other hand, in the present invention, when the support is molded, since the protrusion B is formed by the mold, it is possible to give sufficient surface smoothness, which adversely affects the sliding of the fixing film. Do not give. Moreover, since the support itself is not worn, the lubricity of the grease is not deteriorated. Further, since it can be formed by molding, the protrusion can be provided at a desired position on the downstream side of the nip.

That is, in the region where the pressure roller is not heated as far downstream as possible from the nip, the surface of the pressure roller is rapidly changed in a non-viscous state in which the temperature of the deposits is further lowered, and the soiling occurs. It is possible to easily release the deposit and prevent fouling.

[0029]

As described above, when the pressure roller is rapidly deformed by using the edge portion of the heating element,
Due to the elastic difference between the deposit on the surface of the pressure roller and the rubber material on the surface of the pressure roller, the deposit can be released to prevent the pressure roller from being soiled. Also, by forming protrusions on the support of the heating element, it is possible to rapidly deform the pressure roller after cooling in the nip, and to release the deposit in the state where the difference in viscoelasticity is larger. Became.

[Brief description of drawings]

FIG. 1 is a sectional view of a fixing nip showing a first embodiment of the present invention.

FIG. 2 is a sectional view of a fixing nip showing a second embodiment of the present invention.

FIG. 3 is a sectional view of a fixing nip of a conventional example.

FIG. 4 is a diagram showing a relationship between a combination of surface hardness and a penetration amount of a pressure roller and dirt in the present invention.

FIG. 5 is a back view, a front view, and a cross-sectional view of a heating element used in the present invention.

FIG. 6 is a sectional view of a fixing device used in the present invention and a conventional example.

[Explanation of symbols]

1 fixing film 3 Film guide 4 pressure roller 5 Ceramic substrate 6 heating element pattern 7a, b conductor pattern 8 electrodes B protrusion E heating element edge P paper T toner

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kenji Kashijima             Kyano, 3-30-2 Shimomaruko, Ota-ku, Tokyo             Within the corporation (72) Inventor ▲ Yoshi ▼ Masato Oka             Kyano, 3-30-2 Shimomaruko, Ota-ku, Tokyo             Within the corporation (72) Inventor Nobuta Adachi             Kyano, 3-30-2 Shimomaruko, Ota-ku, Tokyo             Within the corporation (72) Inventor Miura Mietsu             Kyano, 3-30-2 Shimomaruko, Ota-ku, Tokyo             Within the corporation (72) Inventor Ken Shinmura             Kyano, 3-30-2 Shimomaruko, Ota-ku, Tokyo             Within the corporation F-term (reference) 2H033 AA08 AA45 BA25 BA26 BA59                       BB29 BB30 BB33 BE03

Claims (3)

[Claims] 1. A heating body, a support for the heating body, a film that slides around the heating body and the support, and a pressure member that forms a nip with the heating body via the film. In a heat fixing device for feeding and heating a material to be heated in the nip and supplying the thermal energy of the heating element to the material to be heated through the film, a convex portion is formed in the nip on the heating element side. A heating and fixing device characterized by the above. 2. The heat fixing device according to claim 1, wherein the convex portion is formed by using the edge portion of the heating body. 3. The heat fixing device according to claim 1, wherein a convex portion is formed on the support of the heating body.