JPH04178676A - Fusing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a heat fixing device, in particular, to a heat fixing device, in particular, to pass a transfer material having an unfixed toner image between a fixing roller and a pressure roller that are in pressure contact with each other, and to fix the unfixed toner image. The present invention relates to a heat fixing device for fixing images.

[Prior Art] Conventionally, this type of fixing device uses a dry powder developer, and a pressure contact portion (hereinafter referred to as
A heated roller fixing device that passes a transfer material carrying a developed image through a nip (referred to as a nip) is widely used. This fixing device forms a nip section mainly due to deformation of the pressure roller side due to the difference in hardness between the surfaces of the fixing roller and the pressure roller, the material of the fixing roller, etc. After fixing, the transfer material is horizontally moved along the fixing roller. The paper is configured to be ejected upward. I wanted to,
After fixing, the fixing roller and the transfer material may not be separated and may become wrapped, so this wrapping is prevented by an upper separating claw disposed in contact with the fixing roller. However, there is a problem that the upper separation claw comes into contact with the image on the transfer material and disturbs the image, and especially in color image forming apparatuses, the upper separation claw cannot be used, and the transfer material is moved to the pressure roller. The configuration was such that the paper was ejected downward from the horizontal direction. That is, the fixing roller is made to have more elasticity than the pressure roller, and the nip is formed mainly by deformation on the fixing roller side.

FIG. 2 shows a schematic diagram of such a conventional fixing device, in which a rotatable fixing roller 1, a pressure roller 2 that rotates while being pressed against the fixing roller 1, and a It has a structure including a coating device 3 that can be freely approached and separated for supplying a mold release agent, and a cleaning wipe 4 that cleans toner and paper dust adhering to the surfaces of the fixing roller 1 and the pressure roller 2.

The fixing roller 1 has a structure in which the surface of a metal vibrator is coated with silicone rubber and fluorocarbon rubber, and the pressure roller 2 is a metal roller with silicone rubber on the surface and a fluorocarbon resin coated on the surface. It is something.

A heater such as a halogen lamp is placed inside the fixing roller 1 and the pressure roller 2 to heat the surfaces. Further, a thermistor 5 is in contact with the pressure roller 2, and the temperature of the roller is adjusted by controlling the voltage applied to the heater via a temperature adjustment circuit. These rollers 1,
2 is rotatably supported by the device main body (not shown) in the direction of the arrow. Further, in order to discharge the transfer material downward along the pressure roller 2, the surface hardness of the fixing roller l is softer than that of the pressure roller 2. For this reason,
The pressure roller 2 is slightly bitten into the fixing roller 1, and a nip is formed by deformation on the fixing roller side.

The coating device 3 includes a mold release agent tank 3a that stores silicone oil as a mold release agent, a pumping roller 3b that pumps up the mold release agent from there, a coating cooling roller 3c that applies the mold release agent to the fixing roller l, and a mold release agent. Blade 3 for controlling the amount of coating
It is composed of d. The application roller 3c is rotatable and has a sponge rubber surface coated with silicone rubber, and can freely approach and separate from the fixing roller 1 to apply a release agent. The amount of the release agent applied is adjusted by the plate 3d, and the release agent is applied in a constant amount from the leading edge to the trailing edge of the transfer material.

The cleaning cloth 4 uses a nickel wafer 4a, and is brought into pressure contact with the fixing roller 1 to clean the roller.

Nomex felt 4b is brought into pressure contact with the pressure roller 2 to clean the roller.

In this state, when the transfer material that has passed through the input logite 6 passes between the fixing roller l and the pressure roller 2, the transfer material is heated and pressed from both the front and back sides by the roller 1.2, and the unfixed toner carried on the surface is heated and pressed. is melted and fixed, and separated by curvature below the horizontal due to the shape of the nip due to the difference in hardness between the fixing roller 1 and the pressure roller 2. Therefore, since separation is possible without providing a bell release claw, good fixing can be performed without disturbing the image.

[Problems to be Solved by the Invention] However, according to the conventional example described above, the hardness of the surface of the fixing roller is softer than that of the pressure roller, and therefore, there are the following problems. In other words, the rubber thickness on the surface of the fixing roller is thicker than the rubber thickness on the surface of the pressure roller, and for this reason, the thermal conductivity of the fixing roller is suppressed to some extent. Furthermore, since the nip is formed on the fixing roller side, the rubber material for the fixing roller is limited.

An object of the present invention is to solve the above-mentioned problems and to effectively separate the transfer material without disturbing the image on the transfer material and without imposing restrictions on the rubber material, thickness, etc. of the fixing roller. The purpose is to provide a fixing device that can.

[Means for Solving the Problems] According to the present invention, the above object has at least a pair of a fixing rotary body and a pressure rotary body, and a pressure contact portion formed between the two rotary bodies is used to solve the problem. In a heat fixing device that fixes the unfixed image by conveying a transfer material carrying a fixed image while heating it under pressure, the pressure contact portion is arranged so that the transfer material that has passed through the pressure contact portion is transferred to the fixing rotating body. A separating rotary body is disposed in front of the pressure contact portion in the transfer material conveying direction, and is disposed so as to be able to freely approach and separate from the fixing rotary body. Alternatively, the transfer material after passing through the pressure contact portion is passed between the fixing rotary body and the separating rotary body, and the transfer material is discharged along the separating rotary body side. This is achieved by being present.

[Function] According to the present invention, when the transfer material enters the nip between the fixing rotor and the pressure rotor, the separating rotor, which can freely approach and separate from the fixing rotor, comes into contact with the fixing rotor. urge Then,
The transfer material discharged above the horizontal passes between the separating rotary body and the fixing rotary body, and is separated from the fixing rotary body by, for example, curvature separation. In this way, a good separation operation can be performed without disturbing the image on the transfer material and without placing any restrictions on the material of the fixing rotor.

[Example] A first example and a second example of the present invention will be described based on the accompanying drawings.

First Embodiment> FIG. 1 is a schematic diagram of a fixing device according to a first embodiment of the present invention, and parts common to those of the conventional example in FIG. 2 are given the same reference numerals and explanations thereof will be omitted.

In FIG. 1, the surface of the fixing roller 1, which is a rotating body for fixing and heating, is harder than the pressure roller 2, which is a rotating body for pressing, and the fixing roller 1 slightly bites into the pressure roller 2. The transfer material that has been fixed by forming a nip is discharged upward from the horizontal along the fixing roller 1 due to curvature separation due to the shape of the nip.

In FIG. 1, numeral 7 denotes a separation roller which is a rotating body for separation that can freely approach and separate from the fixing roller 1, and its surface hardness is l
It is harder than the surface of the fixing roller 1 and rotates at the same speed as the fixing roller 1 in the forward direction. Reference numeral 8 denotes an auxiliary guide that ensures that the transfer material passes between the fixing roller l and the separation roller 7 after fixing.

Reference numeral 9 denotes a separation claw that is in contact with the separation roller. With this configuration, the transfer material fixed by the fixing roller 1 and the pressure roller 2 is discharged above the horizontal along the fixing roller l, and is sent between the fixing roller l and the separation roller by the auxiliary guide 8. . When the paper is passed through the auxiliary guide 8, the separation roller 7 is pressed against the fixing roller l. Here, since the fixing roller 1 has more elasticity than the separating roller 7, the separating roller 7 slightly bites into the fixing roller 1.
A nip is formed on the fixing roller l side. Then, the transfer material is discharged along the separation roller rough by curvature separation due to the nip shape between the fixing roller 1 and the separation roller 7.

In addition, since the separation claw 9 that prevents the transfer material from wrapping around the separation roller 7 by the separation claw 9 hits the back side of the transfer material, the
It does not disturb the image. Here, the transfer material may be electrically attracted by applying a bias to the separation roller rough.

As described above, according to this embodiment, the transfer material can be separated without disturbing the image. Moreover, there are no restrictions on the rubber material of the fixing roller, and a fixing roller with excellent thermal conductivity, durability, mold releasability, etc. can be used.

<Second example> Next, a second embodiment of the present invention will be described.

Note that explanations of parts common to the first embodiment will be omitted.

This embodiment differs from the first embodiment in that the separating roller rough is made of a rubber material whose raw material is fluororubber or the like, which has higher adhesiveness than silicone rubber. According to this embodiment, the transfer material that has passed between the fixing roller 1 and the separation roller ruff is discharged along the separation roller ruff due to the adhesiveness of the separation roller ruff.

According to this embodiment, as in the first embodiment, good separation can be performed without disturbing the image.

Third embodiment> Next, a third embodiment of the present invention will be described.

Note that explanations of parts common to the first embodiment will be omitted.

In this embodiment, the material and surface hardness of the separation roller luff are set to be the same as those of the fixing roller 1, and the separation roller luff is rotated in the forward direction with respect to the fixing roller l at a higher speed than the fixing roller l. different from.

According to this embodiment, the transfer material that has passed between the fixing roller 1 and the separation roller ruff is discharged from the fixing roller 1 along the separation roller ruff that rotates at a high speed.

In this embodiment as well, the same effects as in the first embodiment can be achieved.

[Effects of the Invention] As described above, according to the present invention, the transfer material after passing through the pressure contact portion of the fixing rotor and the pressure rotor is set to be discharged above horizontally, and the fixing rotor is Since the separating rotary body that can be freely moved toward and away from the fixing body is used, there is no need to impose restrictions on the rubber material, thickness, etc. of the fixing rotary body. That is, the fixing rotor has a hard surface hardness and the pressure rotor has a soft surface hardness, in other words, the fixing rotor has a thin rubber layer.
Alternatively, the thermal conductivity of the rubber layer can be improved, and at the same time, it has become possible to thicken the rubber layer of the pressurizing rotor.

This makes it possible to improve the thermal conductivity of the fixing rotor without reducing the nip radius, leading to improvements in performance and efficiency.

In addition, since a nip can be formed on the side of the pressurizing rotor, the rubber material of the fixing rotor is less constrained, and it has become possible to use a rubber material that is effective in improving durability, mold releasability, and the like.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the schematic structure of a device according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view showing the schematic structure of a conventional device.

Claims (1)

[Scope of Claims] It has at least a pair of a fixing rotating body and a pressing rotating body, and a transfer material carrying an unfixed image is sandwiched while being heated at a pressure contact portion formed between the two rotating bodies. In the heat fixing device that fixes the unfixed image by conveying the unfixed image under pressure, the pressure contact portion is arranged so that the transfer material that has passed through the pressure contact portion is ejected above horizontally along the fixing rotary body. A separating rotary body is arranged in front of the pressure contact portion in the conveying direction of the transfer material, and is disposed so as to be able to freely approach and separate from the fixing rotor. A fixing device, characterized in that the fixing device is disposed such that the transfer material passes between a rotating body and the separating rotating body, and the transfer material is discharged along the side of the separating rotating body.