JPS6389882A - Fixing device - Google Patents

Abstract

PURPOSE:To reduce an elastic modulus and to improve durability by forming at lest either one of a fixing roll and a press roll by Al-Li alloy. CONSTITUTION:The fixing roll 1 and the pressing roll 2 are rotatably supported respectively by an upper case 3 and a lower case 4 at their both ends. The outer peripheries of the rolls 1, 2 are made of the Al-Li alloy and their surfaces are smoothed. For instance, an Al-Li-Cu group, an Al-Li-Cu-Mg group, etc., are optimum for the Al-Li alloy from the view points of intensity, expansion, elastic module, etc., and there is no trouble in toughness and corrosion resistance. Consequently, the generation of luster on the surface of a recording material can be prevented to easily observe an image, the stain of the recording material due to toner offset can be suppressed and the fixing property of the image can be improved.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a fixing device for an image forming apparatus such as a printer, a copying machine, a facsimile machine, or a printing machine, and particularly for fixing an unfixed image on a recording material under pressure. Regarding a fixing device.

(Prior art) Generally, in pressure fixing, a recording material such as paper or a resin sheet is passed between a rotating body for fixing such as a roller or a belt and a rotating body for applying pressure that is in pressure contact with the rotating body for fixing. This is a method of fixing objects such as toner and ink on a material. Further, pressure fixing has advantages such as short fixing time, and is applied to fixing devices such as the above-mentioned image forming apparatuses and printing machines. For example, in a copying machine, as shown in FIG.
A and 102a made of steel with a mirror finish are generally used, and an average linear load of 20 kg/cm or more is applied to fix the toner image on the recording paper P.

[Problem that the invention seeks to solve]

By the way, in general, when the recording paper P is subjected to an average linear load of 12 kg/cm or more, its surface becomes smooth and glossy. This fixing method had a problem in that the surface of the recording paper 2 became glossy, making the image difficult to see.

In order to solve this problem, as shown in FIG.
A is subjected to induction hardening and hard C plating to increase the surface hardness and extend the life of the roller, and at the same time, the roller surface is blasted to give it a matte-like unevenness, a so-called matte treatment. Fixing roller 11
A countermeasure has been proposed for preventing smoothing of the surface of the recording paper 2 and preventing the occurrence of gloss by causing the recording paper P to pass between the pressure roller 1 and the pressure roller 112 to form irregularities on the surface of the recording paper 2.

However, with the above measures, the matte-treated roller 11
Since a greater pressure is applied to the convex part 1,112 than to the fourth part, the convex part wears more easily, and the matte surface disappears and immediately the recording paper P becomes glossy, and the fixing roller surface 111
a Toner gets into the recess and is retransferred.
The so-called toner offset may stain the recording paper P,
Problems have arisen, such as the toner that has entered the recording paper P peeling off the toner on the recording paper P.

Therefore, the present invention has been made to solve the above-mentioned problems of the prior art, and its purpose is to prevent gloss from occurring on the recording material and to prevent staining of the recording material due to toner offset. The purpose is to provide a fixing device that can.

(Means for Solving the Problems) In order to achieve the above object, in the fixing device according to the present invention, a pressure roller is brought into pressure contact with the fixing roller, and the recording material is passed between these two rollers. In a fixing device that fixes an image, at least one of the rollers is made of Al-
It is constructed by forming it from a Li alloy.

(Function) In the present invention having the above configuration, at least one of the fixing roller and the pressure roller is made of an Al-Li alloy, thereby reducing the elastic modulus and improving durability.

(Example) The present invention will be explained below based on the illustrated example. Second
The figure is a schematic configuration diagram showing an embodiment of the fixing device according to the present invention, and its configuration and fixing process are as follows. That is, in the figure, 1 and 2 are a cylindrical fixing roller and a pressure roller, respectively;
The fixing roller 1 and the pressure roller 2 are rotatably supported at both ends by an upper case 3 and a lower case 4, respectively. The upper case 3 and the lower case 4 are pivotally connected to a rotatable moat by a support shaft 5 at one end, and at the other end, a port 6 is provided in both the cases 3 and 4 passing through the moat.
, a spring 7 provided around the port 6, and a nut 8 that compresses the spring 7 and generates a repulsive force to apply the pressing force ω. This pressing force ω is multiplied by the case part according to the lever principle, and between the fixing roller 1 and the pressure roller 2, the total load ZW (W>ω, the average linear load obtained by dividing W by the roller length is 20 to 50 kg) /cm ). This load W acts directly on the recording paper P as a recording material supporting the toner image T, and the toner image T on its surface
The pressure is fixed. The fixing roller 1 is rotationally driven in the direction of the arrow by a motor (not shown) via a gear (not shown) provided at an end thereof.

Pressure roller 2 is applied by Hiko friction force (when there is no recording paper P between rollers 1 and 2, it is applied by roller L; when recording paper P is pressed between rollers 1 and 2, it is applied by recording paper P) The recording paper P advances in the direction of the arrow by the rotation of both rollers 1.degree.2 rotating in the direction of the arrow, and the pressure fixation of the toner image T progresses. The supporting surface of the toner image T of the recording paper P is pressed against the fixing roller 1, and the surface thereof is brought into pressure contact with the pressure roller 2.

FIG. 1 shows the main parts of an embodiment of the present invention, in which the outer peripheries la and 2a of the fixing roller 1 and the pressure roller 2 are made of Al-L
It is made of i-alloy and has a smooth surface. As the above-mentioned Al-Li alloy, for example, Al-Li
-Cu-based (e.g. 2090 alloy) or Al-Li-Cu-
Mg-based rollers (for example, 8090 alloy) are most suitable for the above-mentioned rollers in terms of strength, elongation, elastic modulus, etc., and there are no problems in terms of toughness and corrosion resistance.

Table 1 shows 2090 as an example of the above-mentioned A=Li alloy.
Alloy (manufactured by Alcoa), 8090 alloy (Pech
iney) and Li-free 70 for reference.
75 alloy composition 1 mechanical properties.

lh, which has the above characteristics! ; L-Li alloy t±
It has an elastic modulus of about 80 (GPa), but this 1-direction C±2
The fixing roller 1 and the pressure roller 2 are made of A-Li alloy (aluminum-lithium alloy)
It is clearly understood that when the tt and tt flora are formed in a pressure-contact area, strain is likely to occur. Therefore, roller 1,
Since the pressure applied to roller 2 is dispersed over the entire area of the pressure contact surface (L in the figure) expanded by the above-described strain, even if the surfaces of rollers 1 and 2 are made smooth, the transfer paper P will not become glossy. In addition, the density of Al-Li alloy is 2.5 to 2.8 (g/c 3), which is the density of conventional iron materials (
It is significantly smaller than the 7075 alloy (density 7.88 g/cm3), which does not contain Li (density 2.88 g/cm3).
8 g/Cff13), so it is about 10% smaller than
It is possible to reduce the weight of the fixing device body.

Next, the fixing roller l and pressure roller 2 of this embodiment were made of Al-
When the Li alloy is used (Case 1) (Fig. 1), when the fixing roller and pressure roller are made of steel with mirror-finished surfaces (Case 2) (Fig. 3), the fixing roller and the pressure roller The durability of the roller and the fixation of the image were evaluated in three cases (Case 3) (Figure 4), in which hard Cr plating was applied to the surface of the rollers and the surfaces of both rollers were blasted to give them matte irregularities (Case 3) (Figure 4). , I will explain an experiment that investigated the presence or absence of gloss on recording paper. In the experiment, each of the above rollers was
The fixing device shown in the figure is applied to a copying device, and the number of copies at which the surface condition of the roller changes and toner offset becomes noticeable is determined as the number of copies that can be made, that is, the life of the roller. It was. The fixing roller used was 57 mm in diameter, and the recording paper was A4 size.

As a result of the experiment, Table 2 shows the number of copies that the roller lasts for four types of average linear loads, and Table 3 shows the toner image fixability for each average linear load, which is the same as Table 2. The results are shown below for the quality of the recording paper and the presence or absence of gloss on the surface of the recording paper.

Table 2 Durability of fixing roller (roller diameter φ57) A4 size table 3 Fixing performance judgment results (initial) A... Good B... Average C... Unsuitable From 2 and Table 3, the specular roller of Case 2 In this case, the durability is good up to about 200,000 to 300,000 sheets, but the purpose is to improve fixing performance.

It can be seen that it is necessary to apply an average linear load of about 20 kg/cm to the recording paper, which causes the recording paper to become glossy. In addition, in the case of case 3, which is a matte roller, 15
It has been found that although good fixing performance can be obtained with an average linear load of about kg/cm and the generation of gloss on the recording paper can be prevented, the roller's lifespan ends after about 5,000 sheets, so durability is significantly lacking.

On the other hand, as shown in Case 1, in the case of the present invention using an Al-Li alloy roller, good toner image fixing performance can be obtained even with a low average linear load of about 12 kg/cm. Furthermore, it can be seen that gloss on the surface of the recording paper does not occur even at a high average linear load of 20 kg/am, and in terms of durability, toner offset does not occur up to about 1 million sheets.

However, if the roller is made of Al-Li alloy, case 2 described above. It can be seen that Case 3 has the most excellent characteristics in terms of image fixability, prevention of recording paper gloss, and durability, even when compared with Case 3.

In the above embodiment, the fixing roller 1 and the pressure roller 2 are
We have described the case where both are made of Al-Li alloy,
The present invention is not limited to this, but the fixing roller 1
Alternatively, the same effect can be obtained by forming one of the pressure rollers 2 from a human-Li alloy and the other from another material such as iron material.

Further, in the above embodiment, the surface of the roller 1.2 is made of Al.
Although the recording material was formed to be smooth using a Li alloy, if the surface is appropriately roughened, the anti-glossy property 11 of the surface of the recording material will be significantly improved.

(Effects of J1) The present invention has one or more configurations and functions, and by using an Al-Li alloy for at least one of the fixing roller or the pressure roller, the generation of gloss on the surface of the recording material is prevented and the image is Various effects can be obtained, such as making it easier to see, preventing staining of the recording material due to toner offset, and improving image fixability.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the fixing device according to the present invention, and FIG. 1 is an enlarged sectional view of the main part. FIG. 2 is a schematic configuration diagram, FIG. 3 is an enlarged sectional view of a main part of a conventional fixing device, and FIG. 4 is an enlarged sectional view of a main part of another conventional fixing device. Explanation of symbols 1... Fixing roller 2... Pressure roller P...
・Recording paper (recording material) T...Toner image ゛1・'-ζ・
−−゛・n′

Claims (1)

[Claims] A fixing device that fixes an unfixed image by pressing a pressure roller against a fixing roller and passing a recording material between these rollers, characterized in that at least one of the rollers is made of an Al-Li alloy. Fusing device.