JPH01223486A - Fixing elastic roller and fixing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides an elastic roller for applying pressure to the unfixed image when fixing the unfixed image, and at least one of the pair of rollers is an elastic roller. Regarding a fixing device.

(Prior art) In recent years, a recording material supporting an unfixed image is passed through the nip between a pair of rollers, and at this time, the unfixed image is fixed by applying pressure or heat and pressure to the unfixed image. It is widely practiced.

In such an apparatus, in order to obtain a nip width, at least one of the rollers is an elastic roller, and in particular, the roller on the side not in contact with the unfixed image is an elastic roller.

In this case, in order to obtain uniform fixing performance along the longitudinal direction of the rollers, it is necessary that the pressure between the pair of rollers be uniform throughout the longitudinal direction of the rollers.

(Problems to be Solved by the Invention) However, since the roller pair applies pressure at the ends, there is a problem in that the pressure is higher at the ends of the rollers than at the center of the rollers.

Also, when polishing is done as a finishing touch in the production of elastic rollers, so-called relief occurs at the ends of the rollers, and the outer diameter of the ends of the rollers becomes larger than the center, causing them to come into contact with the other roller with pressure. However, there is a difference in the contact between the center portion and the end portion of the roller, and this problem also causes a problem in that the contact pressure in the longitudinal direction at the contact portion becomes non-uniform.

In order to solve this problem, it has been considered to provide a pair of rollers that intersect, but if this angle of intersection becomes large, the recording material tends to wrinkle or skew.

It has also been considered to manufacture the roller in a crown shape, but it takes time and effort to manufacture the roller. Furthermore, there is a problem in that when the crown amount becomes too large, wrinkles tend to occur in the recording material.

(Means for Solving the Problems) The present invention to solve the above problems provides an elastic roller for applying pressure to an unfixed image when fixing the unfixed image. and an elastic layer provided on the outside of this base material, and this elastic layer is characterized by having a recess or recess provided only on the side end surface, and an unfixed material between a pair of rollers pressed together. In a fixing device that fixes an unfixed image by passing the image through an image supporting material that supports the image, at least one of the pair of rollers is an elastic roller having an elastic layer, and the elastic layer of the elastic roller is formed only on the side end surface. It is characterized by having a concave portion or a convex portion.

(Example of the invention) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a side end view of an elastic fixing roller according to an embodiment of the present invention, and FIG. 2 is a sectional view in the longitudinal direction of the roller.

In the elastic roller 1, a rubber elastic layer 12 is provided on a cylindrical metal core member 11, and only the end surface K has approximately circular concave portions 1 and 3 on the coaxial circumference of the core metal. A large number of them are arranged at intervals, forming substantially circumferential recesses. The shape of the recess and the depth of the recess are preferably selected arbitrarily so that the surface hardness of the roller in the circumferential direction at the end of the roller is approximately uniform. To,
The material was coated with silicone rubber having a hardness of 30° (JISA) to form an elastic roller with an outer diameter of 22 m1 and a roller length of 215 mm. The cross section of the roller has a diameter of 1.5fi and a depth of 2.5mm.
A large number of dragon recesses are arranged on the same periphery as the core metal.

Next, FIG. 3 shows a sectional view of an embodiment of a fixing device using this fixing rotating body as a pressure roller.

2 is a fixing roller, which is equipped with a heater H inside.

The elastic roller 1 is provided in pressure contact with the fixing roller 1.

By passing the recording material P with the unfixed image T supported on the fixing roller 2 side through the nip 3 between the two pairs of rows, the unfixed image is fixed onto the recording material by heat and pressure.

Reference numeral 4 denotes a thermistor for detecting the surface temperature of the fixing roller 2. Based on the detection result, the amount of heat generated by the heater H is controlled to keep the roller surface temperature substantially constant.

Further, the fixing roller 2 is provided with a drive means (not shown) that rotates the fixing roller 2 in the direction of arrow A.

The fixing roller 2 is made of an A1 alloy core 21 with an outer diameter of 25mm and a wall thickness of 1.4mm coated with fluororesin 22, and the elastic roller 1 is used as a pressure roller to maintain a total pressure of 6mm.
It was press-fitted with a weight of 1 kg so that it could rotate freely.

In addition, a 1.1 kW halogen heater is used as a heating means for the fixing device, and an NTC thermistor is brought into contact with the fixing roller as a means for detecting the temperature on the surface of the fixing roller. It was controlled by a control means. Additionally, the fixing roller 2 has a circumferential speed of 48 mtx/
Rotate it in the direction of arrow A using see.

A fixing process test was conducted at a frequency of 8 sheets per minute on A4 size paper of 80 g/m2 on which an unfixed toner image of the test pattern was formed under the above conditions.

Uniform and good fixing properties were obtained both at the edges and in the center of the condensed paper.

Similarly, A4 size paper 52 on which an unfixed toner image of a test pattern was formed. ! When a similar test was conducted using an elastic roller having the same hardness and dimensions as in the example, a difference in fixing performance was observed between the edges and the center of the paper in the fixing process test.

Furthermore, in the conveyance test, the paper wrinkle occurrence rate was as high as 1.5 inches.

In this way, by forming a recess, especially a substantially circular or circumferential recess, only at the side end of the elastic fixing roller, the pressure at the end is reduced and the roller can be fixed without the problem of wrinkles. Approximately uniform pressure can be obtained over the longitudinal direction.

Further, a certain degree of effect can be obtained by providing a convex portion instead of a concave portion. However, in terms of ease of processing and degree of effectiveness, concave portions are preferred. Further, it is preferable that the recessed portions are provided only at the end portions, particularly only at the non-passing portions of the recording material, and not provided at the portions through which the recording material passes.

Furthermore, in the embodiments described above, the plurality of recesses are provided in a circumferential shape, or they may be provided in a continuous circumferential shape.

(Effects of the Invention) As explained above, according to the present invention, substantially uniform fixing performance in the longitudinal direction of the roller can be obtained without reducing the conveyance accuracy of the recording material.

[Brief explanation of the drawing]

1 is a side end view of an elastic roller for fixing according to an embodiment of the present invention, FIG. 2 is a longitudinal cross-sectional view of the roller of the embodiment shown in FIG. 1, and FIG. 3 is a cross-sectional view of a fixing device according to an embodiment of the present invention. It is. 1... Pressure roller 2... Fixing roller 3... Nip section H... Heater

Claims (7)

[Claims] (1) In an elastic roller for applying pressure to an unfixed image when fixing the unfixed image, the elastic roller has a base material and an elastic layer provided outside the base material, and the elastic roller An elastic roller for fixing, characterized in that the layer is provided with recesses or projections only on the side end surfaces. (2) The fixing elastic roller according to claim 1, wherein the concave portion or convex portion is provided substantially circumferentially. (3) The fixing elastic roller according to claim 1 or 2, wherein the elastic layer is a silicone rubber layer. (4) In a fixing device that fixes an unfixed image by passing an image support material supporting the unfixed image between a pair of rollers pressed together, at least one of the pair of rollers is an elastic roller provided with an elastic layer. A fixing device characterized in that the elastic layer of the elastic roller has a concave portion or a convex portion only on a side end surface. (5) The fixing device according to claim 4, wherein the elastic roller is a roller that does not come into contact with the unfixed image. (6) The fixing device according to claim 4 or 5, respectively, wherein the recessed portion or the convex portion is provided substantially circumferentially. (7) The fixing device according to any of claims 4 to 6, wherein the elastic layer is a silicone rubber layer.