JPS6333152B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat roller fixing device for an electrophotographic copying machine, etc., and more specifically to a heat roller fixing device for use in a heat roller fixing device comprising a heat roller forming a nip and a pressure roller. The roller and the pressure roller are constructed of pipes without flanges.

As is well known, the electrophotographic method records an optical image of an original image in the form of an electrostatic latent image on a photosensitive member, and sequentially visualizes the latent image using an electroscopic developing substance, usually called a toner. The visualized image is either directly fixed on a photosensitive member, or the image is transferred from the member to a transfer member such as a sheet of plain paper and then fixed. In order to fix the toner image, it is necessary to increase the temperature of the toner material.

Incidentally, in recent years, there has been a demand for electrophotographic copying apparatuses to be faster, more reliable, and lower in price, and a heat roller fixing device is known and widely used as a fixing device that meets these demands.

Compared to conventionally used hot plate type fixing devices, this heat roller fixing device has superior heat transfer characteristics because it uses two rollers, a heating roller and a pressure roller, to press the transfer member and then transport it for fixing. Because of this, it has the advantage that not only can the set temperature be lowered, but also high-speed conveyance is possible.

However, the heating roller and pressure roller of the conventional heating roller fixing device have flanges formed at both ends thereof. That is, in FIG. 1, 1 is a heating roller, 2 is a pressure roller, and flanges 1', 1', 2', and 2' are formed at both ends of the heating roller 1 and the pressure roller 2.

As a result, the structure has become complicated and expensive. In addition, the heating roller and the pressure roller are heated to high temperatures, and since they form a nip, they are subjected to high pressure loads, and the concentrated stress is concentrated on the flange, causing damage and damage to the flange. Because of the frequent damage, a special processing method has been adopted to construct the flange portion, for example, a method such as constructing only the flange portion with a thick wall. Therefore, manufacturing control of the rollers and maintenance control of the fixing device must also be adequately controlled.
Also, one possible way to reduce the heat capacity of the heating roller and reduce heat loss is to use a thin-walled roller as the fixing roller, but in this case, the material of the roller must have a certain strength, so it is necessary to use a thin-walled roller. has its limits. Note that when reducing the outer diameter of the heating roller in order to reduce its heat capacity, the bearing as the heating roller support member and the bearing and drive unit of the pressure roller may get in the way of each other. Due to this reason, it is not possible to reduce the outer diameter of the heating roller.

The present invention provides a heat roller fixing device that eliminates the above-mentioned drawbacks, in which at least one of the heat roller and the pressure roller is composed of a pipe having a simple structure, and further, the interior of the pressure roller is By inserting the pressure roller bearing in the heating roller bearing, the heating roller drive unit, and the pressure roller bearing do not get in the way of each other, the outer diameter of the heating roller can be reduced, and the heat capacity can be reduced. can be made smaller. Needless to say, the present invention can be applied to a heat roller fixing device in which one side is a roller and the other side is not a roller.

The embodiment of the present invention shown in FIG. 2 will be described below.

1 is a heating roller, and 2 is a pressure roller, each of which is constructed of a simple pipe.

The heating roller 1 has a built-in heater 3 for heating the heating roller 1, and the surface of the heating roller 1 is coated with a fluorine-containing resin for the purpose of preventing toner from adhering to the heating roller 1. The heating roller 1 is usually made of aluminum or stainless steel. Further, bearings 5 are provided at both ends of the heating roller 1 via a heat insulating material 4, and a driving member 6 for driving and rotating the heating roller 1 is provided at one end. The driving member 6 is
It is usually composed of gears or sprockets, and is driven by other gears or chains (not shown).

As described above, the heating roller 1 of the present invention has a simple structure (the outer circumference is approximately the same diameter in the longitudinal direction), unlike a conventional heating roller having a flange 1'. cylindrical pipe). This allows the heating roller to be constructed with a thinner wall than the conventional heating roller, which had to have a thick wall near the bearing part, making it possible to manufacture a simple construction with uniform wall thickness over the entire roller area. It is something.

The surface of the pressure roller 2 is lined with a silicone rubber lining 7 in consideration of heat resistance and mold releasability. In addition, the elasticity of this rubber forms a nip width during pressure bonding, contributing to improved fixing performance. A bearing 8 is provided inside the pressure roller 2.
The support shaft 9 of the pressure roller 2 is supported.

As described above, the pressure roller according to the present invention is constructed of a pipe and has a flange 2' as seen in conventional pressure rollers, and is different from the support shaft 9 of the pressure roller 2. The bearing 8 that supports the pressure roller 2 is built inside the pressure roller 2 .

As explained above, the heating roller and fixing roller of the heating roller fixing device of the present invention are constructed of pipes, and in particular, the heating roller is a cylindrical pipe, so it does not have a flange like a conventional roller. Unlike the above, it has a simple structure and is inexpensive. Furthermore, since there is no flange, no special processing is required. Furthermore, whereas conventional heating rollers had to have a thick wall near the bearing part, the heating roller can be constructed with a thin wall and can be easily manufactured with a uniform wall thickness over the entire roller area. It is. Furthermore, since the fixing roller according to the present invention has a bearing built inside, it does not interfere in any way and does not come into contact with the bearing and drive member of the heating roller, and thus the entire heating roller fixing device. This is to make it smaller and more compact. Therefore, it is possible to configure the heating roller with a small outer diameter and a thin wall configuration,
The heat capacity of the heating roller can also be reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional heat roller fixing device.
FIG. 2 is a sectional view of a heat roller fixing device according to the present invention. 1... Heating roller, 2... Pressing roller, 1'...
...Heating roller flange, 2'... Pressing roller flange, 3... Heater, 5... Heat roller bearing, 6... Heating roller driving member, 7... Lining, 8... Pressing roller bearing.

Claims (1)

[Claims] 1. In a heat roller fixing device that fixes a transfer material carrying toner by heating and pressing it, a heat roller rotatably supported by a support member on the outer peripheral surface of a cylindrical pipe containing a built-in heater outside the fixing area; A heat roller fixing device including a pressure roller rotatably supported on the inner surface of a pipe by a bearing member.