JPS6339911B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a roll fixing device for an electrophotographic copying machine.

(Prior Art) Conventionally, in order to prevent the copy paper from wrapping around the thermal roll of a thermal roll fixing device, a peeling claw is brought into contact with the surface of the thermal roll, but this has the disadvantage that the thermal roll is easily damaged.

In addition, as shown in Figure 2 of Japanese Patent Application Laid-Open No. 50-56947, several belts are inserted at intervals between the fixing roll 1 and the pressure roll 2, and the copying machine passes between both rolls 1 and 2. Tension rolls 5 and 6 are arranged on the paper outlet and inlet sides, and the belt is stretched between the tension rolls 5 and 6 and the pressure roll 2, and the belt is attached to the fixing roll 1 made of a soft material with a rubber hardness of about 60. A roll fixing device that improves heat conduction efficiency from the pressure roll 2 and prevents the copy paper from wrapping around the pressure roll 2 when the copy paper passes between the fixation roll 1 and the pressure roll 2. However, since several belts are installed on the entrance side as guides for inserting the copy paper between the fixing roll 1 and the pressure roller 2,
In areas where there are no belts, the lower pressure roll 2 protrudes above the bottom surface of the belt, causing the copy paper to wave up and down before it is pressed against the fixing roll 1 and the pressure roll 2, causing wrinkles. There was a problem in that this resulted in uneven fixing.

Furthermore, as shown in Japanese Unexamined Patent Publication No. 50-92754, a pulley is provided on the exit side of a heating roll with a built-in heater, an endless belt is stretched between the heating roll and the pulley, and shallow grooves are formed in the heating roll. There is a known roll fixing device that fixes the copy paper by inserting it between a heating roll and a pressure roll with the image side facing the endless belt and fixing the copy paper with the endless belt. Because it comes into pressure contact with the belt, it exists at the boundary between the endless belt and the shallow groove. Toner and paper particles that have accumulated in between adhere to the image paper, stain the image surface, damage the copy paper, and cause the endless belt to protrude toward the entrance side. and
There is a temperature difference between the endless belt part and the heating roll part, which causes uneven fixing.
In addition, there was a problem in that the cost increased due to the groove processing.

(Purpose) The present invention prevents the copy paper from wrapping by applying the endless belt to a pressure roll without using a peeling claw. This prevents the image from being damaged or uneven fixing due to contact, and further prevents the copy paper from being inserted directly between the heating roll and the pressure roll, causing wrinkles in the copy paper and causing uneven fixing. The purpose is to prevent the copy paper from wrapping around the pressure roll, eliminate the need for groove processing, and reduce costs.

(Structure) In order to achieve the above object, the present invention has a heating roll made of a relatively hard material such as Teflon that has heat resistance and mold releasability, and a pressure roll whose surface portion is made of an elastic material. A tension roll is disposed on the copy paper exit side of the pressure roll, and a plurality of endless belts are stretched between the pressure roll and the tension roll, and the thickness of the endless belt is determined based on the elastic material on the surface of the pressure roll. The endless belt is made thinner than the thickness, and the endless belt is embedded in the pressure contact portion of the pressure roll so that the surface of the endless belt and the surface of the pressure roll are flush with each other.

Hereinafter, a detailed description will be given based on examples. 1
Reference numeral 1 denotes a heating roll with a built-in heater 12, which is made of a relatively hard material with heat resistance and mold releasability, such as Teflon or silicone rubber. Reference numeral 13 denotes a pressure roll, the surface of which is made of an elastic body with a hardness of 80 degrees or less, preferably 70 degrees or less, and a thickness of 0.5 mm or more as measured by a rubber hardness meter. The heating roll 11 and the pressure roll 13 are pressed together by means not shown, and a tension roll 14 is placed on the copy paper exit side of the pressure roll 13.
are arranged, pressure roll 13 and tension roll 1
4, a plurality of endless belts 15 are stretched between them. The thickness of the endless belt 15 is thinner than the thickness of the elastic body of the pressure roll 13 and 0.5 mm or less,
The width is preferably 0.3 mm or less, and the width is 30 mm or less, preferably 20 mm or less. Polyimide or glass fiber is impregnated with a heat-resistant resin, and its surface is coated with a fluororesin or silicone resin to make it non-adhesive. Therefore, the endless belt 15 is embedded in the elastic surface portion of the pressure roll 13, and the surface of the endless belt 15 is flush with the surface of the pressure roll 13 at the pressure contact portion with the heating roll 11 as shown in FIG.

Next, the effect will be explained. The developed copy paper 16 is directly inserted between the heating roll 11 and the pressure roll 13 from the right side in FIG. 1 with the image side facing up. There is nothing in contact with the inlet side of the copy paper 16 to be inserted, and therefore the copy paper is inserted naturally without the undulations of the prior art. Next, at the pressure contact portion between the heating roll 11 and the pressure roll 13, the endless belt 15 becomes flush with the surface of the pressure roll 13 as shown in FIG. Even if a gap occurs between both ends of the surface of the belt 15 and both ends of the concave portion 13a of the pressure roll 13, the image surface of the front surface of the copy paper is uniformly pressed against the flat heating roll 11, and the endless belt 15 is pressed against the back surface of the copy paper. There is no possibility that the copy paper will be transported and the image will be damaged or uneven fixing will occur.

In addition, even if paper dust or the like gets stuck on the surface of the pressure roll between the edges on both sides of the endless belt, the concavities of the pressure roll will return to their original state after passing the area facing the heating roll, so the amount of adhesion will be small and extremely dry. It does not climb up and does not damage the back side of the copy paper.

(Effects) According to the present invention, a pressure roll whose surface portion is made of an elastic material is pressed into contact with a heating roll made of a relatively hard material such as Teflon that has heat resistance and mold releasability.
A tension roll is disposed on the copy paper exit side of the pressure roll, and a plurality of endless belts are stretched between the pressure roll and the tension roll, and the thickness of the endless belt is determined by the elastic material on the surface of the pressure roll. The endless belt is inserted into the pressure contact part of the pressure roll so that the surface of the endless belt and the surface of the pressure roll are flush with each other.
The endless belt and the pressure roll are in flush contact with the back side of the copy paper, and the surface of the copy paper is pressed against the smooth surface of the heating roll, so there is no damage to the image or uneven fixation. It can reliably prevent the copy paper from wrapping around the pressure roll, and since no peeling claws are used, the pressure roll will not be damaged, and it can be manufactured at low cost since no groove forming process is required.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of the present invention, and FIG. 2 is an enlarged front cross-sectional view of a pressure roll and an endless belt at a pressure contact portion with a heating roll. 11...Heating roll, 12...Heater, 13
...Pressure roll, 14...Tension roll, 1
5...Endless belt, 15a...Recessed portion.

Claims (1)

[Claims] 1 A pressure roll whose surface portion is made of an elastic material is pressed into contact with a heating roll made of a relatively hard material such as Teflon that has heat resistance and mold release properties, and a tensioner is placed on the copy paper exit side of the pressure roll. Place the roll,
A plurality of endless belts are stretched between the pressure roll and the tension roll, the thickness of the endless belt is made thinner than the thickness of the pressure roll surface elastic body, and the endless belt is inserted into the pressure contact portion of the pressure roll. A roll fixing device for an electrophotographic copying machine in which the surface of an endless belt and the surface of a pressure roll are flush with each other.