JP2001134130A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device with which a uniform nip width is obtained and fixing property is secured by receiving the deformation of a fixing roller by means of a receiving member arranged outside the roller main body of the fixing roller so as to prevent the deformation of the fixing roller while causing no increase in the cost nor deterioration in the yield. SOLUTION: The device is provided with the fixing roller, a pressure roller and also a plurality of deformation preventing means for preventing the deformation of the fixing roller.

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 an electrophotographic image forming apparatus such as a copying machine or a laser printer.

[0002]

2. Description of the Related Art To save energy, there has been a demand for a fixing device capable of stopping lighting of a heater in a standby state and instead quickly raising a fixing temperature when necessary.
The simplest and most effective method for achieving this is to reduce the heat capacity by reducing the thickness of the fixing roller so that the fixing roller is sensitive to the heat supplied from the heater.

When the wall thickness is reduced in this manner, the roller is bent in an arc at the nip portion in contact with the pressure roller, the contact pressure at the central portion is weakened, the nip is reduced, and the fixing rate is deteriorated. However, since the toner is not fixed to the recording paper, there is a problem that the toner falls off when rubbed by hand, and the skewing or wrinkling is liable to occur when the fixing roller rotates.

[0006] Such a phenomenon will be described with reference to an example shown in FIG. 6 which is a typical fixing device. In this fixing device, 1 is a fixing roller, 2 is a pressure roller, 3 is a frame side plate, 4 is an upper stay, 5 is a fixing roller bearing, 6
Is a drive gear for transmitting drive to the fixing roller 1, 7 is a pressure roller bearing, and 8 is a pressure spring.

[0005] Such a fixing device is usually a fixing roller 1
Is made of iron and has an outer shape of 40 mm.
The time required for the surface temperature to rise from room temperature to 170 ° C (warm-up time) is set to within 10 seconds.

According to an experiment conducted on such a device, when the rise time was examined using a 1200 W heater, the thickness of the fixing roller 1 had to be reduced to about 0.3 mm. Although the rising time up to this point was satisfied, in this state, a deflection a of 0.45 mm occurred in the nip portion at the center of the fixing roller 1 as shown in FIG. The width increased by 0.2mm due to the collapse. In this case, there are problems such as poor fixing at the center portion and paper transport performance.

When a thin roller of this order is formed, the fixing roller 1 is pushed up by the pressing force from the pressure roller 2, and at this time, the lower surface is lifted while receiving a compressive force, and the upper surface is lifted while receiving a tensile force. Try to. However, since the strength is weak, the upper surface cannot withstand the pulling force, and extends in the lateral direction and does not bend upward. As a result, as shown by the dashed line in FIG. 7, the roller rises only at the lower surface, and expands laterally without changing the upper surface, forming a collapsed shape. In such a state, as shown in FIG. 8, the diameter D1 of the nip at the central portion a is smaller than the diameter D2 at both ends, and a fixing failure at the central portion occurs.

[0008]

To solve such a problem, Japanese Patent Application Laid-Open No. 57-1555 discloses a method for solving the above problem.
No. 71 and (2) Japanese Patent Application Laid-Open No. 10-39665 have proposed a fixing device. By the way, in these fixing devices, the fixing roller is formed by drawing, in which external pressure is applied from the outer peripheral surface to the inner surface, and the concave portion is formed by cutting, welding, or the like. As a result, the amount of cutting during cutting increases,
There is a problem that the amount of cutting is increased in order to correct a roller that is distorted due to the thermal deformation of welding, resulting in a high cost and a low yield.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the problems of the conventional fixing device as described above, without increasing the cost and reducing the yield, without reinforcing the fixing roller, and without reinforcing the fixing roller. It is an object of the present invention to provide a fixing device capable of preventing deformation of a fixing roller by receiving deformation of the fixing roller by a receiving member provided on an outer side, obtaining a uniform nip width, and securing fixing property.

[0010]

In order to achieve the above-mentioned object, the present invention has been made to solve the above-mentioned problem. A plurality of deformation preventing means for preventing deformation of the fixing roller.

According to a second aspect of the present invention, in the first aspect, the deformation preventing means has a surface hardness equal to or less than a surface hardness of the fixing roller.

According to a third aspect of the present invention, in the first aspect of the invention, the deformation preventing means has a surface hardness equal to or less than a surface hardness of the fixing roller, and a convex curvature of an outer peripheral surface of the fixing roller. And a sliding contact member having a concave curvature matched with the above.

According to a fourth aspect of the present invention, in the first aspect of the present invention, a cleaning means is provided in contact with the fixing roller at an upstream side of the fixing nip portion. Things.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention shown in FIGS. 1 to 5 will be described below. In this description, the same parts as those of the conventional example are denoted by the same reference numerals, and the description thereof will be omitted. The different parts will be mainly described. FIGS. 1 and 2 show a first embodiment of the present invention. In this embodiment, the fixing roller 1 has a longitudinal section in the vicinity of a central portion in the longitudinal direction, and a fixing roller 1 attached to a frame side plate (not shown). A plurality of (three in this embodiment) support arms 12 bent inward from the middle portion of the letter-shaped stay 10 and the lower ends of both hanging portions 14 and 15 are used to prevent deformation of supporting the outer periphery of the fixing roller 1. Are rotatably mounted.

With such a configuration, the support roller 11 contacts and rotates to support the upper surface and both side surfaces of the fixing roller 1, so that even if the fixing roller 1 is thin, it protrudes in the lateral direction of the load as shown in FIG. Is prevented, and a uniform nip width can be obtained to ensure accurate fixing performance. Such a supporting roller 11 is provided with a PFA on the surface of the fixing roller 1.
It is desirable that the fixing roller 1 be made of a roller of, for example, non-added ethylene tetrafluoride, which has the same heat resistance as that of the material and the like and has a low strength, and damages the surface of the fixing roller 1 by using such a material. Is suppressed, and a longer life can be achieved.

FIGS. 3 and 4 show a second embodiment of the present invention, which is a support roller according to the first embodiment.
Instead of 11, a support pad 13 made of the same material as the support roller 11 is used. When the support pad 13 supports the fixing roller 1, the deformation of the fixing roller 1 is performed in the same manner as the support roller 11. The fixing roller 1
And the support pad 13 will make surface contact,
Further, deformation of the fixing roller 1 can be reliably prevented.

FIG. 5 shows a third embodiment of the present invention. In this embodiment, the lower end of the hanging portion 15 of the support arm 12 of the first embodiment is extended below the support roller 11, and A bent portion 16 having a tip bent inward is formed.
A cleaning member 17 made of a felt pad is attached to 16, and the width of the cleaning member 17 is wider than the length of the support roller 11. With such a structure, the adhered matter adhered to the surface of the fixing roller 1 is cleaned. In addition, such a cleaning member
17 can be similarly provided in the second embodiment.

[0018]

The present invention is as described above, and the invention according to claim 1 is provided with a plurality of deformation preventing means for contacting and supporting the outer periphery of the fixing roller to prevent deformation of the fixing roller. Deformation of the fixing roller is prevented by preventing deformation of the fixing roller by deformation preventing means provided outside the roller body without reinforcing the fixing roller without inviting that cost and yield are deteriorated, There is an effect that a uniform nip width can be obtained and the fixing property can be secured.

According to a second aspect of the present invention, the deformation preventing means is constituted by a rotating body having a surface hardness equal to or less than the surface hardness of the fixing roller. Since the friction load of the rotating body is small and low friction driving is possible, and the surface hardness of the rotating body is equal to or less than that of the fixing roller, the surface of the fixing roller is not damaged, and the life is prolonged. There is an effect that can be achieved.

According to a third aspect of the present invention, the deformation preventing means has a sliding contact surface having a surface hardness equal to or less than the surface hardness of the fixing roller and having a concave surface curvature matching the convex surface curvature of the outer peripheral surface of the fixing roller. Since the fixing roller is composed of members, it is possible to more effectively prevent deformation of the fixing roller, and since the surface hardness of the contact member is equal to or less than that of the fixing roller, the surface of the fixing roller may be damaged. There is an effect that longevity can be attained.

According to the fourth aspect of the present invention, since the cleaning means for cleaning by contacting the fixing roller is provided on the upstream side of the fixing nip portion, the toner and other adhering substances adhering to the surface of the fixing roller are removed from the rotating body. Alternatively, there is an effect that the contact with the contact member can be prevented from sticking to the surface of the fixing roller and adhering to the recording paper.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part of a first embodiment of the present invention.

FIG. 2 is a perspective view of the same.

FIG. 3 is a longitudinal sectional view of a main part of a second embodiment of the present invention.

FIG. 4 is a perspective view of the same.

FIG. 5 is a longitudinal sectional view of a main part of a third embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of a conventional fixing device of the same type as the present invention.

FIG. 7 is a modified view of the above fixing roller.

FIG. 8 is a modified view of a central portion of the identification attaching roller.

[Explanation of symbols]

Reference Signs List 1 fixing roller 2 pressure roller 3 frame side plate 4 upper stay 5 fixing roller bearing 6 drive gear 7 pressure roller bearing 8 pressure spring 10 stay 11 support roller 12 support arm 13 support pad 14 hanging part 15 hanging part 16 bending part 17 Cleaning member

Claims (4)

[Claims] 1. A fixing device having a fixing roller and a pressure roller, wherein a plurality of deformation preventing means for contacting and supporting an outer periphery of the fixing roller to prevent deformation of the fixing roller are provided. 2. The fixing device according to claim 1, wherein the deformation preventing means is constituted by a rotating body having a surface hardness equal to or less than a surface hardness of the fixing roller. 3. The deformation preventing means is constituted by a sliding contact member having a surface hardness equal to or less than a surface hardness of the fixing roller and having a concave curvature matched with a convex curvature of an outer peripheral surface of the fixing roller. The fixing device according to claim 1, wherein: 4. The fixing device according to claim 1, further comprising a cleaning unit provided on an upstream side of the fixing nip for cleaning by contacting the fixing roller.