JPH04270369A - Fixing device - Google Patents

Abstract

PURPOSE:To support a fixing roller without using a bearing and to prevent a large load torque from occurring by arranging a roller member with a small diameter rotatably disposed on an opposite position to the fixing roller and making the outer periphery of the roller abut on that of the fixing roller. CONSTITUTION:A shaft 2b is fixed and provided on a frame body 1 in order to attach the roller 2a with the small diameter for supporting the fixing roller 3. Consequently, the roller 2a rotates while taking the shaft 2b as a center. The fixing roller 3 is positioned by making the outer periphery part of the fixing roller abut on the roller 2a with the small diameter on both ends part, and is supported by three points by the pressing of a pressure roller 4a from a lower part. When the fixing roller 3 rotates, the roller 2a with the small diameter rotates around the shaft 2b, and also holds the position of the fixing roller 3, so that it functions as the bearing. Resistance as the bearing on this occasion, is sliding resistance between the roller 2a with the small diameter and the shaft 2b, and rolling resistance between the roller 2a with the small diameter and the outer periphery of the fixing roller 3, however both of them are small.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for electrophotographic devices such as laser beam printers and copying machines.

0002

2. Description of the Related Art A conventional fixing device, as shown in FIG.
It has a fixing roller 3 in the shape of a metal hollow pipe and an elastic roller member 4a supported by a metal shaft 4b. The metal shaft 4b is supported by a bearing 5, and the bearing 5 is supported by a pressure spring 6.
is energized by As a result, the elastic roller member 4a is placed in pressure contact with the fixing roller 3 with a predetermined pressing force.

In the conventional device as described above, in order to position the fixing roller 3 with respect to the frame, a bearing 17 such as a ring-shaped sliding member or a bearing that fits around the outer circumference of the fixing roller 3 is used. It was used.

0004

[Problems to be Solved by the Invention] However, in the above conventional example, when a bearing is used as a bearing for the fixing roller, it is necessary to fit it to the outer circumference of the fixing roller. Two bearings are required on both sides, which is not cost-effective.

Therefore, instead of a bearing, a resin or metal ring-shaped bearing with good sliding properties as shown in FIG. 8 is used to slide the outer periphery of the fixing roller 3 and the inner periphery of the fixing roller bearing 17. We are trying to reduce costs.

However, even with this configuration, as shown in FIG. 8, the pressure spring force is applied via the pressure roller in the area A where the outer periphery of the fixing roller and the fixing roller bearing contact, resulting in the following problem. . (2) The sliding resistance in area A is large, and the load torque of the fixing device itself is large, requiring reinforcement of each part. ■ Load torque is likely to change due to scratches on the outer periphery of the fixing roller, surface properties on the inner circumferential surface of the bearing, or changes in surface properties before and after durability. ■ Due to variations in the load torque of the fixing device, a relatively large drive motor is required even for a small machine in order to provide a margin to prevent step-out even at the maximum load torque, which poses a cost problem.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a fixing device that supports a fixing roller without using a bearing and has means for not generating large load torque.

[0008]

[Means for Solving the Problems] According to the present invention, the above object is to provide a fixing roller having a heating element therein, and an elastic roller member supported by a metal shaft and disposed so as to come into pressure contact with the fixing roller. In the fixing device, at least one end of the fixing roller has at least one shaft supported at a position facing the elastic roller member in the radial direction of the fixing roller so as to come into contact with the end. The roller-shaped member is
This is achieved by being rotatably arranged.

[0009]

According to the present invention, the fixing roller is positioned in the radial direction by the roller-like member and the elastic roller member, and when the fixing roller rotates, the roller and the elastic roller member are driven to rotate.

0010

Embodiments First to fifth embodiments of the present invention will be described with reference to the drawings.

First Embodiment First, a first embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 shows an apparatus according to a first embodiment of the present invention. Reference numeral 1 denotes a frame body constituting the main body of the fixing device. A shaft 2b is fixedly provided for mounting. Therefore, the rollers 2a are rotatable about the shaft 2b. Further, a pressure roller 4a, which is an elastic roller member, is disposed so as to be in pressure contact with the fixing roller 3, and a pressure roller center axis 4b is provided.
is supported by a pressure roller bearing 5 that transmits the pressure from a pressure spring 6. 7 is a fixing heater.

As shown in FIG. 2, the fixing roller 3 is positioned by the outer periphery of the fixing roller coming into contact with two rotatable small-diameter rollers 2a at both ends thereof, and by the pressure of the pressure roller 4 from below. It is supported at three points and perfectly positioned. When the fixing roller 3 rotates, the small diameter roller 2a
rotates around the fixed shaft 2b and the position of the fixing roller 3 remains firmly determined, so it functions as a bearing.

[0014] The resistance as a bearing at this time is the small diameter roller 2a.
There is a sliding resistance between the fixed shaft 2b and the fixed shaft 2b, and a rolling resistance between the outer periphery of the small diameter roller 2a and the outer periphery of the fixing roller 3, but the sliding resistance is slight because the sliding area is very small.

Furthermore, since the resin or metal roller is in contact with the metal fixing roller, there is little rolling resistance due to deformation during the nip.

Regarding the angle θ of the center of the two small diameter rollers with respect to the center of the fixing roller 3, the smaller the pressing force W is, the more
The smaller the force to move the fixing roller in the paper conveyance direction X, the narrower the angle is sufficient, but the angle can be selected arbitrarily.

<Second Embodiment> Next, a second embodiment of the present invention will be described using FIG. 3. Note that the same reference numerals are given to the same parts as in the first embodiment, and the explanation thereof will be omitted.

FIG. 3 is a front view of the fixing device of the second embodiment, in which the small diameter roller 10a has a flange having a diameter larger than the roller diameter, and also has the function of positioning the fixing roller 3 in the thrust direction.

This embodiment can also provide the same effects as the first embodiment.

<Third Embodiment> Next, a third embodiment of the present invention will be described using FIG. 4. Note that the same reference numerals are given to the same parts as in the first embodiment, and the explanation thereof will be omitted.

FIG. 4 shows a third embodiment of the device, in which small diameter rollers 1
The fixing roller 3 is positioned by arranging three rollers 1a on one side. In this case, even if the pressure roller is removed for maintenance, for example, the fixing roller 3 is retained and maintenance can be easily performed. In this case as well, the angle α between the center of the roller and the center of the fixing roller is arbitrary.

<Fourth Embodiment> Next, a fourth embodiment of the present invention will be described using FIG. 5. Note that the same reference numerals are given to the same parts as in the first embodiment, and the explanation thereof will be omitted.

FIG. 5 shows a fourth embodiment of the device in which a small diameter roller and a shaft are integrated.

According to this embodiment, not only the same effects as the first embodiment can be achieved, but also the cost can be reduced.

<Fifth Embodiment> Next, a fifth embodiment of the present invention will be described using FIG. 6. Note that the same reference numerals are given to the same parts as in the first embodiment, and the explanation thereof will be omitted.

FIG. 6 shows a fifth embodiment of the apparatus in which the rollers that come into contact with the fixing roller 3 are arranged on one side at a position facing the pressure side. In this case, since the maximum pressure is applied to the opposing positions, left and right positioning can be performed using regulating members 15a and 15b made of resin or the like with good sliding properties.

[0027]

[Effects of the Invention] As explained above, according to the present invention,
A small diameter roller member rotatably disposed at a position facing the pressure roller with the fixing roller in between, and by bringing the outer periphery of the roller into contact with the outer periphery of the fixing roller, it functions as a bearing for the fixing roller. Can be done. As a result, it is possible to reduce costs by simply installing rollers, without using conventional expensive large-diameter bearings or ring-shaped bearing members that have large sliding resistance and high load torque due to surface sliding. A large reduction in load torque can also be achieved.

[Brief explanation of the drawing]

FIG. 1 is a front view showing a schematic configuration of an apparatus according to a first embodiment of the present invention.

FIG. 2 is a partially cutaway side view of the device of FIG. 1;

FIG. 3 is a side view showing a schematic configuration of a device according to a second embodiment of the present invention.

FIG. 4 is a front view showing a schematic configuration of a device according to a third embodiment of the present invention.

FIG. 5 is a side view showing a schematic configuration of a device according to a fourth embodiment of the present invention.

FIG. 6 is a front view showing a schematic configuration of a device according to a fifth embodiment of the present invention.

FIG. 7 is a front view showing a schematic configuration of a conventional device.

FIG. 8 is a front view showing the relationship between a bearing member and a fixing roller of a conventional device.

[Explanation of symbols]

2a Roller-shaped member (roller) 3 Fixing roller 4a Elastic roller member (pressure roller) 4b Metal shaft

Claims (1)

[Claims] Claim 1: A fixing roller having a heating element inside;
In a fixing device having an elastic roller member supported by a metal shaft and disposed so as to be in pressure contact with the fixing roller, the elastic roller member is disposed at at least one end of the fixing roller in a radial direction of the fixing roller. A fixing device characterized in that at least one roller-shaped member is rotatably disposed at a position facing the member and pivotally supported so as to come into contact with the end portion.