JPH02289880A - Fixing device - Google Patents

Abstract

PURPOSE:To absorb strain due to the compression of the expansion of the diameter of both edges of a pressure roll by providing the pressure roll constituted of a shaft core and coating elastic body formed on the outer periphery thereof, and providing reliefs on both edges of the elastic body in its axial direction. CONSTITUTION:The coating elastic body 1 is formed on the core shaft 2, and ring slits (reliefs) 1b are provided on both edges in the axial direction so that the strain due to the compression deformation is absorbed to it. Since thus constituted elastic body 1 has the hollow structure on only both edges in its axial direction, the strain due to the compression deformation of the expansion of both edges of the pressure roll can be absorbed at the time of pressurizing. Therefore, it is prevented that the pressure roll is weared by the edges of a recording material and simultaneously, a nipping 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 unfixed images. [Prior Art] Conventionally, the pressure roller used in this type of fixing device has a third
As shown in the figure, an elastic body 1 was molded around the outer periphery of the shaft core 2. [Problems to be Solved by the Invention] In the conventional fixing device described above, both ends of the elastic body 1 of the pressure roller in the axial direction are solid and laterally extended, so foamed silicone rubber is used. It was not possible to absorb the strain caused by compressive deformation of the outer diameter bulge 1a at both ends of the pressure roller, which occurs when the elastic body 1, such as a sponge, is expanded and molded. Therefore, the edge portion of the recording material has the outer diameter bulge 1a.
This has the disadvantage of strong contact with the pressure roller, scraping of the coating, and adhesion of floating toner, and furthermore, the NIP width increases at both ends in the axial direction, leading to wrinkles in the recording material. 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 present invention provides a fixing device for fixing a toner image transferred onto a recording material onto the recording material, in which a shaft core and an outer periphery of the shaft core are coated. It has a pressure roller made of a molded elastic body, and has reliefs at both axial ends of the elastic body to absorb strain caused by compressive deformation. [Example] Next, the present invention will be explained 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 with the heat source 8 is attached to the frame 6
It is rotatably engaged with. Pressure roller shaft core 2 is bearing 1
0, and a spring 4 presses the heating port roller 3 and the elastic body 1 of the pressure roller. The galley is fixed to the heating roller 3 and transmits the driving force from the main body. A heat source 8 is fixed to the support member 7 from both sides, and 9 is a temperature sensor. Figure 2 is a longitudinal sectional view showing details of the pressure roller. The elastic body 1 is coated and molded on the shaft core 2, and has annular slits (relief) at both ends in the axial direction to absorb strain caused by compressive deformation.
lb is provided. Therefore, according to the invention:
The strain generated when the bulges 1a located at both axial ends of the elastic body 1 are compressed and deformed is absorbed by the slits 1b.
[Effects of the Invention] As explained above, the present invention has a hollow structure in which only both ends in the axial direction of the elastic body constituting the pressure roller of the fixing device are hollow, so that the bulges at both ends of the pressure roller when pressure is applied It has the effect of being able to absorb the strain caused by compressive deformation of the recording material, preventing the pressure roller from being scraped by the edge of the recording material, and making the NIP width uniform.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing a fixing device according to the present invention, FIG. 2 is a vertical cross-sectional view showing a pressure roller in the fixing device of the present invention, and FIG. 3 is a vertical cross-sectional view showing a conventional pressure roller. be. 1... 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 9... Temperature detector 10.
・Bearing diagram 1

Claims (1)

[Claims] (1) A fixing device for fixing a toner image transferred onto a recording material onto the recording material, the fixing device having a shaft core and a pressure roller made of an elastic body coated on the outer periphery of the shaft core;
A fixing device characterized in that both ends of the elastic body in the axial direction are provided with reliefs for absorbing strain caused by compressive deformation.