JPH03265879A - Heat fixing device - Google Patents

Abstract

PURPOSE:To prevent the accumulation of the charges in a pressurizing roller by forming bearings supporting the shaft parts of the pressurizing roller of a conductive material and ground connecting these bearings. CONSTITUTION:The charges electrified on the rear surface of recording paper P move to the surface of the roller body 7 of the pressurizing roller 3 and are accumulated therein when fixing operations are continuously executed. The charges electrified on the roller body 7 flow gradually from the metallic shaft 6 to the respective bearings 8, 8 and further flow through respective compression coil springs 10, 10 and respective spring rests 9, 9 to a device body 1 when the potential on the surface of the pressurizing roller 3 attains a certain magnitude. Further, the charges flow from the device body 1 to the device body of an electrophotographic recorder and the charges electrified on the pressurizing roller 3 are destaticized. The charges electrified on the pressurizing roller 3 are well escaped and the potential by electrification is suppressed to a lower level in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a heat fixing type fixing device provided in an electrophotographic recording apparatus.

(Prior Art) A thermal fixing type fixing device installed in an electrophotographic recording device heats a fixing roller with a heat source, passes the recording paper that has completed the transfer process between the fixing roller and a pressure roller, and then transfers the recording paper to the fixing roller. comes into contact with the toner image forming surface of the recording paper and presses the recording paper against the fixing roller from the back side using a pressure roller, thereby heat-pressing the toner image formed on the toner image forming surface of the recording paper onto the surface of the recording paper. It is something. This fixing device constitutes a unit by providing a fixing roller, a pressure roller, and a heat source disposed inside the fixing roller in the main body of the device, which is a housing.

Conventionally, in a heat fixing type fixing device, a fixing roller has a structure in which the surface of an aluminum cylindrical body is coated with a synthetic resin material having good mold releasability and heat resistance.

Further, the pressure roller has a structure in which a roller body made of an elastic, heat-insulating and heat-resistant material is fitted onto the surface of a metal shaft. The bearing that rotatably supports the metal shaft of this pressure roller is made of synthetic resin with excellent wear resistance.

These +A charges are adopted for the following reasons.

In other words, the shaft of the pressure roller is made of a metal material with high wear resistance, and a roller body made of elastic and heat-resistant rubber is used to keep the recording paper in stable contact with the regular roller. It is attached to a metal shaft. The bearing that supports the shaft of the pressure roller is made of heat-resistant resin that has excellent wear resistance because the material cost is low and it is lightweight.

(Problems to be Solved by the Invention) However, this conventional heat fixing device has the following problems.

That is, in general, in an electrophotographic recording device, the back side of the recording paper is charged in the transfer process to transfer the toner image formed on the photoreceptor drum to the recording paper, so the recording paper is transferred to the pressure roller of the thermal fixing device. The back of the recording paper is charged with an electric charge until it passes through the

Therefore, charges move and accumulate on the pressure roller body that contacts the back surface of the recording paper each time the recording paper passes.

Furthermore, since the roller body of the pressure roller comes into pressure contact with the recording paper, charges are also accumulated due to charging caused by this friction.

In this way, electric charge is accumulated in the roller body of the pressure roller, and the accumulated electric charge is transferred from the metal shaft of the pressure roller to a metal product installed near the pressure roller, such as a bearing that supports the metal shaft. This can cause electrical discharge and generate noise in the control device of the electrophotographic recording device, causing malfunction.

Therefore, in conventional charging devices, in order to suppress the accumulation of charge on the pressure roller, a slip ring is brought into pressure contact with the metal shaft using its elastic force, or a static elimination brush is brought into contact with the roller body. A means is employed to release the accumulated charge.

However, with either method, the load on the pressure roller increases due to the metal shaft and the members that contact the roller body, causing a delay in the rotation of the pressure roller. There is a problem in that slippage occurs due to the difference, and the toner image transferred to the recording paper is disturbed.

The present invention has been made based on the above-mentioned circumstances, and an object of the present invention is to provide a thermal fixing device that can prevent charge accumulation on the pressure roller without applying a load to the pressure roller.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, a thermal fixing device of the present invention includes a fixing roller, a pressure roller that presses a recording paper against the fixing roller, and the fixing roller. A heat source for heating the pressure roller and a bearing for supporting the shaft of the pressure roller are made of a conductive material, and the bearing is grounded.

(Function) The electric charge on the pressure roller can be released to the ground through the conductive bearing, and accumulation of electric charge in the pressure opening can be prevented.

Further, there is no need to apply a load to the pressure roller in order to remove the electric charge accumulated on the pressure roller.

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

An embodiment of the fixing device of the present invention will be described with reference to FIGS. 1 and 2.

In the figure] is the main body of the device, 2 is the fixing 0-ra,
3 is a pressure roller, and 4 is a halogen lamp as a heat source. The device main body 1 is made of conductive metal. The fixing roller 2 has an aluminum cylindrical body whose surface is coated with a synthetic resin material having good mold releasability and heat resistance, such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ethyl polymer (PFA), etc. It consists of The fixing roller 2 is arranged horizontally and is rotatably supported by a pair of bearings 5 attached to both side walls of the main body 1 of the apparatus. The heater 4 is disposed inside the fixing roller 2 and supported by a support member (not shown).

The pressure roller 3 is constructed by fitting a roller body 7 onto a metal shaft 6. The roller body 7 is made of an elastic heat insulating material such as silicone rubber, and is made of silicone rubber impregnated with a conductive material such as carbon, or the surface of the silicone rubber is coated with a carbon layer to make it conductive. There is.

The pressure roller 3 is arranged horizontally below the fixing roller 2,
Both ends of the metal shaft 6 are supported in a configuration described later. 8,
8 is a pair of bearings, 9, 9 is a pair of spring bearings, 1. ．． 0,1
．． 0 is a pair of compression coil springs.

The bearings 8, 8 are made of, for example, a synthetic resin with excellent wear resistance impregnated with carbon to make it conductive.

The bearings 8, 8 have, for example, a rectangular parallelepiped shape, and are formed with grooves 8a, 8a for rotatably and detachably supporting the pressure roller 3. The bearings 8, 8 are disposed in openings formed in the side walls on both sides of the apparatus main body so as to be vertically displaceable. The spring receivers 9, 9 are respectively attached to the side walls on both sides of the device main body 1, and each spring receiver 9,
Each bearing 8, 8 is supported from below by each compression coil spring 1010 supported by each bearing 9. As a result, the pressure roller 3 is supported so as to be freely displaceable, and an elastic force is applied toward the fixing roller 2. Each spring holder9. Each coil spring 1.0.10 is made of electrically conductive metal. For this reason, each of the bearings 8, 8 constitutes a ground circuit that connects to the main body 1 of the apparatus through each coil spring 1, 0, 10 and each spring receiver 9, 9.

Note that ] ] is a cleaner that removes toner remaining on the surface of the fixing roller 2 , 12 is a temperature detector that detects the surface temperature of the fixing roller , and 13 is a claw that separates the recording paper P from the fixing roller 2 .

The heat fixing device configured as described above is arranged inside the main body of an electrophotographic recording device, and the main body 1 of the device is connected to the main body 1 of the electrophotographic recording device directly with a bolt made of a conductive metal or via a member made of a conductive metal and the bolt. Attach to the main body of the recording device. The main body of the electrophotographic recording device is connected to ground. Therefore, the main body 1 of the heat fixing device is connected to the ground via the main body of the electrophotographic recording device.

That is, the pressure roller 3 of the heat fixing device is connected to ground.

Then, the thermal fixing device rotates each roller 2 and 3, and heats the fixing roller 2 with a heater 4. The recording paper P that has completed the transfer process of the electrophotographic recording apparatus passes between the fixing roller 2 and the pressure roller 3 of the thermal fixing device, and the toner image formed on the recording paper P is fixed.

When the fixing operation is continued, the charges on the back surface of the recording paper P move to the surface of the roller body 7 of the pressure roller 3 and are accumulated therein. When the potential on the surface of the pressure roller 3 reaches a certain level, the charge on the roller body 7 gradually flows from the metal shaft 6 to each bearing 8, 8, and further to each compression coil spring 1.
0, 1o and each spring receiver 9, 9, and flows into the device main body 1.

Furthermore, it flows from the main body of the electrophotographic recording device to the main body of the electrophotographic recording device. In this way, the charge on the pressure roller 3 is removed.

In addition, since the pressure roller 3 comes into pressure contact with the recording paper P,
Charges are also accumulated due to the electrification caused by this friction. In this case as well, when the potential of the roller body 7 reaches a certain level, the charge is released through the above-mentioned path to eliminate the charge.

Further, in this embodiment, since the roller body 7 of the pressure roller 3 is made conductive, the removal of static electricity from the roller body 7 can be promoted.

Note that the material forming the conductive bearing 8 is not limited to the above-mentioned embodiments, and various materials can be used. For example, the materials that make the bearings 8, 8 conductive are not limited to those of the embodiments.

[Effects of the Invention] As explained above, according to the heat fixing device of the present invention, the bearing supporting the pressure roller is made conductive, so that the pressure roller can be fixed without increasing the rotational load of the pressure roller. It is possible to effectively dissipate the electrical charge and keep the charging potential low.

[Brief explanation of drawings]

FIGS. 1 and 2 are schematic diagrams showing an embodiment of the heat fixing device of the present invention. 1...Device main body, 2...Fixing roller. 3... Pressure roller, 8... Bearing.

Claims (1)

[Claims] A fixing roller, a pressure roller that presses the recording paper against the fixing roller, a heat source that heats the fixing roller, and a bearing that supports the shaft of the pressure roller are formed of a conductive material, and this bearing is grounded. A heat fixing device characterized by being connected to.