JPH01307786A - Fixing device of electrophotographic printer - Google Patents

Abstract

PURPOSE:To prevent the generation of wrinkles by providing a couple of rollers which consists of a fixing roller performing thermal fitting and a pressure roller, providing a couple of pressurizing springs which pressurizes and press-contacts one of said couple of rollers to the other roller and mutually and unevenly setting the spring powers of the pressurizing springs constituting the set. CONSTITUTION:The fixing roller 1 is supported by bearings 10 and 11 which are integrated in a frame 2. Brackets 4 and 5 for supporting the pressure roller support the pressure roller on the frame 2 in the way that the pressure roller can recede and advance toward the fixing roller 1, pivotally and turnably support said roller and regulate the relative position and the posture of the pressure roller 3 with respect to the fixing roller 1 by means of their free motion. Then, the spring powers of the pressurizing springs 8 and 9 which energize the right and the left edges of the pressure roller 3 are provided in the way that the spring powers in right and left are different from each other. Therefore regarding nip width W, one edge w1 becomes narrower compared with the other edge w1 and the external form of the nip width becomes closer to a line with respect to an axis direction. Thus, sheets are smoothly fed and the appearance of wrinkles can be prevented.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a fixing device for an electrophotographic printer.

[Conventional technology]

Conventionally, this type of fixing device has used springs with the same force at both ends of the pressure roller to bring the pressure roller into pressure contact with the fixing roller.

[Problem to be solved by the invention]

When the pressure roller is brought into pressure contact with the fixing roller, the fixing roller and the pressure roller deflect in opposite directions. In conventional devices, the spring force of the pair of pressure springs that bias the pressure roller is set to be the same, so the nip width formed between the fixing roller and the pressure roller as shown in FIG. W is not uniform in the axial direction, and both ends W1. The curve is such that W1 is wide and center line 2 is narrow, and when the sheet is passed by the fixing roller and the pressure roller, the urging direction of the sheet in the lateral direction is not constant, resulting in wrinkles.

An object of the present invention is to provide a fixing device for an electrophotographic printer that solves the above problems.

[Means to solve the problem]

In order to achieve the above object, the fixing device for an electrophotographic printer according to the present invention includes a pair of a fixing roller and a pressure roller that performs heat fixing, and a pressure roller that presses one roller of the pair of rollers against the other roller. A pair of pressurizing springs are brought into contact with each other, and the spring forces of the pair of pressurizing springs are set to be non-uniform.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a front view of an embodiment of the present invention.

The fixing roller 1 has bearings 10 and 1 incorporated into the frame 2.
1 is supported. Further, the pressure roller supporting brackets 4 and 5 are supported on the frame 2 so as to be movable forward and backward toward the fixing roller 1, and are also rotatably supported, so that the brackets 4 and 5 can freely move to support the fixing roller 1. The relative position and posture of the pressure roller 3 are regulated. Pressure roller 3
is supported by bearings 6 and 7 and installed between brackets 4 and 5. Furthermore, spring force is 900gr (spring length 34mm)
Pressure spring 8 and spring cuff 00g r (spring length 34m
), the pressure roller 3 is pressed against the fixing roller 1 by the pressure spring 9.
Pressure weld to.

12 is a gear that receives a drive from the main body.

According to the present invention, since the spring force of the pressure spring that urges the left and right ends of the pressure roller 3 is different on the left and right sides, the nip width W is
As shown in the figure, 1*1 is narrower than the other end v1, and the nip width outer shape becomes close to a straight line with respect to the axial direction.

〔Effect of the invention〕

As described above, according to the present invention, the direction in which the paper is urged by the pressure roller when the paper is passed is constant, the paper is conveyed smoothly, and the occurrence of wrinkles can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an embodiment of the present invention, FIG. 2 is an outline diagram of the nip width of a fixing device according to the invention, and FIG. 3 is an outline diagram of the nip width of a conventional fixing device. 1... Fixing roller 2... Frame 3...
・Pressure roller 4, 5...Bracket 8.9
... Pressure spring patent applicant Niigata NEC Co., Ltd. Figure 1 Figure 3

Claims (1)

[Claims] (1) A pair of a fixing roller and a pressure roller that performs thermal fixing;
An electrophotographic system characterized by a pair of pressure springs that press one roller of the pair of rollers into pressure contact with the other roller, and a spring force of the pressure springs forming the pair set to be mutually non-uniform. Printer fixing device.