JPS638677A - Heat fixing roller - Google Patents

Abstract

PURPOSE:To speed up the transfer of an electric charge from an elastic layer to an arbor and to ground the arbor so as to prevent the electric charge of the elastic layer by using elastic rubber formed by incorporating a good electrically conductive material into heat resistant rubber to form the elastic layer to be fixed to the arbor of a heat fixing roller. CONSTITUTION:A heat fixing device 13 consists of a pair of upper and lower heat fixing rollers 17, 18. The two rollers 17, 18 are electrically ground by metallic bearings, side plates, etc. The heat fixing roller 18 is formed by fixing the elastic layer 23 consisting of the elastic rubber obtd. by incorporating carbon black powder which is the good electrically conductive material into the heat resistant rubber such as heat resistant silicone rubber to the cylindrical arbor 22 consisting of a metal such as alumina. The surface resistance of the elastic layer 23 is, therefore, 10<4>-10<7>OMEGA with 25V impressed voltage and has eventually the good electrical conductivity. The transfer of the electric charge from the elastic layer 23 to the arbor 22 is thereby quickly executed and since the heat fixing roller is grounded through the arbor 22, the electric charge is substantially obviated.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a heat treatment system used for heating and fixing a toner powder image formed on a recording paper in an image recording apparatus such as an electrostatographic copying machine or a facsimile machine. The present invention relates to a fixing roller.

(Prior Art) This type of heat fixing roller is made by laminating an elastic layer made of heat-resistant rubber firmly on a core bar, and baking liquid fluorine-based rubber onto the elastic layer. One in which a skin layer of 300 μm is formed is known from Japanese Patent Publication No. 58-51262.

[Problem that the invention seeks to solve]

The above conventional example has the following problems.

In other words, when the above-mentioned heat fixing roller is pressed into contact with the heating roller and rotated, it is charged by friction on the contact surface. It is.

However, the heat-resistant rubber that forms the elastic layer is usually 2
With an applied voltage of 5V, the surface resistance is 1O13 to IQIsΩ, and the dielectric constant is high, so even if the core metal is grounded, the charges on the elastic layer cannot be moved immediately. Therefore, especially when the atmospheric humidity in the fixing path is low, high voltage is likely to occur in the elastic layer even though the core metal is grounded.
When the electrostatic withstand voltage of the heat fixing roller is exceeded, electrostatic noise may be generated due to leakage to separation claws or other metal members near the roller, which may cause malfunction of the electrical system control circuit.

An object of the present invention is to solve the problems of the conventional example.

[Means for solving problems]

In order to achieve the above object, the present invention is characterized in that the elastic layer fixed to the core metal of the heat fixing roller is formed of an elastic rubber made of heat-resistant rubber mixed with an electrically conductive substance. .

[Effect]

According to the above configuration, the elastic layer has eclipse conductivity and the charge is quickly transferred from the elastic layer to the core metal, so that as long as the core metal is grounded, the elastic layer is hardly charged.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 schematically shows an electrophotographic copying machine, which is an example of an image recording device. In this copying machine, a photoreceptor 4 is mounted horizontally on a copying machine main body 3, which has a document table 1 and a document holder 2 on the top. At the same time,
A charging device 5, a developing device 6, a transfer device 7, a recording paper separating device 8, and a cleaning device 9 are arranged in this order around the photoreceptor 4, and a movable optical system is arranged in the space below the document table l. an exposure device 10, a paper feed conveyance device 12 that conveys the recording paper in the cassette case 11 to the transfer device 7, a paper discharge conveyance device 14 that conveys the separated recording paper to the thermal fixing device 13, and , transfer the recording paper after fixing to Tray 1.
5 is provided with a discharge roller 16 for discharging the paper.

The heat fixing device 13, as shown in FIGS. 2 and 3,
It consists of a pair of upper and lower heat fixing rollers 17.18, and both rollers 17.1B are electrically grounded via metal bearings, side plates, and the like.

One heat fixing roller 17 is responsible for heating, and has a cylindrical core 19 made of metal such as aluminum and a fluorine-based resin 20.
The core metal 19 is coated with a heater 21 such as a heating lamp or a coil.

The other heat fixing roller 18 has a cylindrical core metal 22 made of a metal such as aluminum, and carbon black powder, which is an example of an electrically conductive substance, is mixed into heat-resistant rubber such as heat-resistant silicone rubber. The elastic layer 23 made of the obtained elastic rubber is fixed, and a skin layer 24 is formed on top of the elastic layer 23, which has a thickness of 10 to 20 μm and has no unevenness on the baked surface, by baking liquid fluorine rubber at high temperature. be.

Reference numeral 25 in FIG. 3 is a liquid application roller for the heat fixing roller 18, and by applying an anti-offset liquid such as silicone oil stored in a pan (not shown) to the surfaces of the rollers 17 and 18, The recording paper is on roller 17.1
The toner is configured so that it can be easily peeled off from the surface of the roller 17, and to prevent an offset phenomenon caused by a portion of the toner adhering to the roller 17.

According to the above embodiment, since the elastic layer 23 is made of elastic rubber obtained by mixing carbon black powder, which is a good electrical conductor, into heat-resistant rubber, the surface resistance of the elastic layer 23 is is 104 to 10 at an applied voltage of 25V.
'Ω, and has good conductivity.

Therefore, the charge is quickly transferred from the elastic layer 23 to the core bar 22, and is grounded via the core bar 22, so there is almost no charge.Therefore, even when the atmospheric humidity in the fixing path is low, High voltage is not generated in the roller 18, and generation of static electricity noise due to leakage can be prevented.

Furthermore, by mixing carbon black powder into the heat-resistant rubber, the mold releasability of the surface of the elastic layer 23 is reduced, but in the above embodiment, liquid fluorine rubber is added to the surface of the elastic layer 23. 10-20μ thick baked at high temperature
Moreover, since the surface layer 24 having no irregularities on the printed surface is formed, the release properties of toner and recording paper are good.

FIG. 4 shows another embodiment of the present invention. In this embodiment, a cylindrical core bar 22 made of metal such as aluminum is coated with electrically conductive silicone in heat-resistant rubber such as heat-resistant silicone rubber. The heat fixing roller 18 having the elastic layer 23 is constructed by fixing the elastic layer 23 made of elastic rubber obtained by mixing the elastic rubber, and the surface of the elastic layer 23 has a skin layer as described above. The rest of the structure is the same as the previous embodiment.

According to this embodiment, the surface resistance of the elastic layer 23 is 25V.
With an applied voltage of Since electrically conductive silicone is used as the conductive material, the surface of the elastic layer 23 has good mold releasability, and the above-mentioned skin layer 24 can be omitted, improving manufacturing efficiency and significantly reducing manufacturing costs by reducing manufacturing man-hours. It is possible to aim for down.

Although not shown, the heater 2 is also attached to the core bar 22 of the heat fixing roller 18 having the elastic layer 23 in the second embodiment.
A heater similar to 1 may be incorporated. In other words, the present invention can be similarly applied to a heat fixing roller that handles both heating and pressure.

(Effects of the Invention) The present invention has the above-described structure, and the elastic layer fixed to the core metal is made of elastic rubber obtained by mixing an electrically conductive substance into heat-resistant rubber. Since the elastic layer has good conductivity, charge can be quickly transferred from the elastic layer to the core metal, and as long as the core metal is grounded, the heat fixing roller is hardly charged.

Therefore, even when the atmospheric humidity in the fixing path is low, high voltage is not generated in the heat fixing roller, and generation of static electricity noise due to leakage and malfunction of the electrical system control circuit due to this can be prevented.

[Brief explanation of the drawing]

1 to 3 show one embodiment of the present invention, FIG. 1 is a schematic cross-sectional view of an electrostatic copying machine, FIG. 2 is a schematic vertical front view of a heat-fixing device, and FIG. 3 is a schematic cross-sectional view of a heat-fixing device. FIG. FIG. 4 is a longitudinal sectional side view of a main part showing another embodiment of the present invention. 1B... Heat fixing roller, 22... Core metal, 23...
・Elastic layer.

Claims (2)

[Claims] (1) A heat fixing roller characterized by having an elastic layer made of elastic rubber containing heat-resistant rubber mixed with a conductive material and fixed to a core metal. (2) The heat fixing roller according to claim (1), wherein the electrically conductive material is electrically conductive silicone.