JPH02291590A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent a pressure roller from being ground and to uniform the nip width by providing a heat roller and the pressure roller and providing release parts which absorb strain due to compressing deformation at both axial end parts of an elastic body. CONSTITUTION:The pressure roller 3 engages a frame 6 rotatably. The core 2 of the pressure roller is supported by a bearing 10 and the elastic body 1 of the pressure roller is pressed against the heat roller 3 by a spring 4. The elastic body 1 of the pressure roller is formed coating the outer periphery of the core 2 and annular release parts 1b which absorb the strain due to the compressive deformation of swelling 1a are formed at both axial end parts. Consequently, the compressive deformation strain due to an increase in the external diameter of both ends of pressure rollers 1 and 2 can be absorbed when pressure is applied, the pressure rollers 1 and 2 are prevented from being ground by recording material edges, and the nip width can be made uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fixing device for fixing an unfixed image onto a recording material.

[Conventional technology]

Conventionally, the pressure roller used in this type of fixing device has a third
As shown in the figure, it was made up of a shaft core 2 and an elastic body 1 coated on the outer periphery of the shaft core 2. [Problems to be Solved by the Invention] By the way, the outer periphery of the shaft core 2 is covered with foamed silicone rubber. When covering and molding an elastic body 1 such as a sponge, a bulge 1a is created on the outer diameter of both ends of the pressurizing port, but conventionally this bulge 1a absorbs the strain caused by compressive deformation. I couldn't do it. Therefore, the edge portion of the recording material comes into strong contact with the bulge 1a of the outer diameter, causing problems such as scraping of the pressure roller and the adhesion of floating toner due to scraping of the coating portion.Furthermore, the nip (NIP) width is The drawback is that the recording material becomes wrinkled as it becomes larger in some areas. An object of the present invention is to provide a fixing device that solves the above problems. [Means for Solving the Problems] In order to achieve the above object, the fixing device 7 according to the present invention includes a heating roller equipped with a heat source, a shaft core, and an elastic body coated on the outer periphery of the shaft core. The elastic body has a pressure roller formed at the top, and reliefs are provided at both ends of the elastic body in the axial direction to absorb strain caused by compressive deformation. [Example] Next, the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention. In the figure, the heating roller 3 is rotatably engaged with the frame 6. The axis 2 of the pressure roller is supported by a bearing 10, and the elastic body 1 of the pressure roller is connected to the heating roller 3 by a spring 4.
are pressed together. The galley is fixed to the heating roller 3,
Rotationally driven by receiving driving force from the main body. The heat source 8 is fixed from both sides by supporting members 7 and is provided inside the heating roller 3, and is controlled based on the output of a temperature sensor 9 that detects the surface temperature of the heating roller 3. FIG. 2 is a longitudinal cross-sectional view showing details of the pressure roller. The elastic body 1 of the pressure roller is coated and molded around the outer periphery of the shaft core 2, and the elastic body 1 of the pressure roller is coated and molded at both ends in the axial direction due to compressive deformation of the bulge 1a. Therefore, according to the present invention, the strain generated when the bulges 1a at both axial ends of the pressure roller are compressed and deformed is formed as an annular relief 1b for absorbing the stress.
b, the reaction force caused by the bulge 1a is prevented from becoming abnormally high, and the elastic body 1 can apply a uniform pressing force to the recording material over the axial range of the heating roller 3.

〔Effect of the invention〕

As explained above, the present invention can absorb the compressive deformation strain due to the bulge in the outer diameter of both ends of the pressure roller during pressurization, prevent the pressure roller from being scraped by the edge of the recording material, and also prevent the pressure roller from being scraped due to the edges of the recording material. 1, which has the effect of achieving uniformity of

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, FIG. 2 is a longitudinal sectional view showing a pressure roller in a fixing device of the invention, and FIG. 3 is a longitudinal sectional view showing a conventional example. ■...Elastic body of the pressure roller 2...Axis of the pressure roller 3...Heating roller 4...
・Spring 5...Gear 6...Frame
7...Support material 8...Heat source 10...Bearing 9...Temperature detector

Claims (1)

[Claims] (1) It has a heating roller equipped with a heat source, and a pressure roller composed of an axial core and an elastic body coated on the outer periphery of the axial core. A fixing device characterized by having a relief for absorbing distortion.