JPH11109773A - Fixing device for both-side recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the fixing device of a both-side recorder by which the surface of a pressure roller is sufficiently heated even though the elastic body layer of the pressure roller is thickly provided so as to obtain a sufficient nip width and simultaneous both-side fixing with excellent quality is provided. SOLUTION: A fixing member is constituted of a heating roller 11 consisting of a cylindrical core bar 11a, the elastic body layer 11b provided on the core bar and a heat source 17 provided inside of the core bar and a thermal belt heating pressing device 18 consisting of the pressure roller 20 having the elastic body layer 20a whose thickness is larger than that of the elastic body layer 11b of the heating roller 11, a thermal roller 19 provided with the heat source 17 inside of the cylindrical core bar 19a and an endless belt 12 laid over the thermal roller 19 and the pressure roller 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous paper holding a toner image in an unfixed state on both front and rear sides while holding and pressing the pair of fixing members while applying heat and pressure to simultaneously fix the toner images on both sides of the continuous paper. The present invention relates to a fixing device for a double-sided recording device.

[0002]

2. Description of the Related Art In a laser printer that performs printing on continuous paper using a well-known electrophotographic process, the need for double-sided printing on continuous paper has been increasing in recent years, and an unfixed toner image is held on both front and back sides. The fixing device of the double-sided recording device for nipping and transporting the continuous paper while heating and pressing it with a pair of fixing members and simultaneously fixing the toner image on both surfaces of the continuous paper includes a cylindrical metal core and an outer periphery of the metal core. There is known a configuration in which a heating roller composed of an elastic layer provided on a surface and a heat source provided inside the core is pressed against each other to perform fixing.

[0003]

In such a fixing device configuration, the temperature tends to decrease as the inner peripheral surface of the core metal closest to the heat source moves to the outer peripheral surface of the elastic layer. In particular, since the core metal is generally made of a metal having high thermal conductivity, the gradient of the temperature drop is small, but the thermal conductivity of the elastic layer is lower than that of the core metal. The effect of the drop is large.

Here, the energy required to fix the unfixed toner image held on both sides of the continuous paper is as follows:
Although it is determined by the surface temperature of the elastic layer and the heating time, that is, the time required to pass through the nip width, if the elastic layer is thickened to obtain a long nip width, a sharp temperature drop occurs as described above. Will be lost.

When the temperature of the heat source is increased to eliminate the above-mentioned rapid temperature drop, the boundary between the core metal and the elastic layer becomes extremely hot, and the elasticity is increased by mechanical stress due to pressurization. The material of the body layer is deteriorated, resulting in a disadvantage that the life of the heating roller is shortened.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a high-quality simultaneous double-sided pressurizing roller which can sufficiently heat the surface of the pressing roller even if the elastic layer of the pressing roller is provided thick enough to obtain a sufficient nip width. An object of the present invention is to realize a fixing device of a double-sided recording device capable of providing fixing.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to hold and transport a continuous paper holding an unfixed toner image on both front and back sides while heating and pressing with a pair of fixing members. In the fixing device of the double-sided recording apparatus for fixing simultaneously, a cylindrical core, an elastic body layer provided on the core, and a heat source provided inside the core, A heat roller supported so as to be in contact with one surface, a pressure roller having an elastic layer thicker than the elastic layer of the heat roller, a heat roller including a heat source inside a cylindrical core, and the heat roller. A heat belt heating / pressing device comprising a roller and an endless belt stretched over the pressing roller, wherein the pressing roller is arranged so as to be able to contact the other surface of the continuous paper via the endless belt. This is achieved by:

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a fixing device of the present invention,
FIG. 2 is an overall configuration diagram of a double-sided recording apparatus equipped with the fixing device of the present invention. In FIG. 2, when a printing operation start signal is output from the controller, the photoconductor 1 having photoconductivity rotates at a speed corresponding to the printing speed, and for example, a positive (+) high voltage is applied by the charger 2. As a result, the surface of the photoconductor 1 is uniformly charged.

The character data and graphic data converted into dot images by the controller are turned on / off by laser light.
The signal is transmitted to the printing apparatus as a signal, and the laser beam from the optical unit 3 is applied to the uniformly charged surface of the photoconductor 1. The toner charged positively (+) by the developing device 4 is electrostatically attracted to the portion where the charge on the surface of the photoconductor 1 has disappeared by the irradiation of the laser beam, and adheres onto the photoconductor 1 to form a toner image 5.

The toner image 5 formed on the photoreceptor 1 is transferred by the electrostatic attraction force of the transfer unit 8 onto the continuous paper 7 which is conveyed while being kept at a constant tension by the tractors 6a and 6b. After the transfer of the toner image 5 is completed, the photoconductor 1 uniformly loses the charge on the surface, and then the residual toner is removed by the cleaner 9 to start the next printing process again. In the double-sided recording apparatus shown in FIG.
After being performed on the front and back of the continuous paper 7, the paper is conveyed to a fixing unit.

The continuous paper 7 conveyed to the fixing unit is changed in conveyance path by a paper guide 10. In the paper guide 10, for example, as proposed in Japanese Patent Application No. 9-119611, a guide using air is used to prevent the toner image 5 in an unfixed state from being disturbed. Further, the paper guide 10 is provided so as to be swingable, and also has a buffer function of absorbing a change in the transport speed of the continuous paper 7 by the heating roller 11 and the heating belt heating / pressing device 18.

The continuous paper 7 holding the unfixed toner image 5 passes through the paper guide 10 and is conveyed in the vertical direction.
It passes through a heat belt preheating device 22. Heat belt preheating device 2
2 is wound around a driving roller 14 having a heat source 13 such as a halogen lamp therein, a driven roller 15, and a driving roller 14 and a driven roller 15 as proposed in Japanese Patent Application No. 9-30554. The endless belt 12 is constituted by an endless belt 12 and a belt tension spring 16 and is arranged in a non-contact state with respect to the paper surface of the continuous paper 7. ) And at the same speed as the transport speed of the continuous paper 7 (which may be lower or higher than the transport speed),
The continuous paper 7 is efficiently preheated with little electric power. In the present embodiment, the heat source 13 is provided on the drive roller 14, but may be provided on the driven roller 15 on the side closer to the heating roller 11.

After being preheated by the heat belt preheating device 22,
The continuous paper 7 is nipped and conveyed while being heated and pressurized in a nip region formed at a pressure contact portion between the heating roller 11 and the heat belt heating and pressing device 18, and the toner images 5 are simultaneously fixed on both surfaces of the continuous paper 7. You.

Next, the fixing device of the present invention will be described with reference to FIG. Heating roller 11 in contact with one side of continuous paper 7
Is composed of a cylindrical metal core 11a, a rubber layer 11b provided on the outer peripheral surface of the metal core 11a, and a heat source 17 provided inside the metal core 11a. On the other hand, the heat belt heating / pressing device 18 in contact with the other surface of the continuous paper 7 includes a pressing roller 20 having a rubber layer 20a thicker than the rubber layer 11b of the heating roller 11, and a cylindrical core 19a. Heat roller 19 provided with a heat source 17 such as a halogen lamp inside
, Over the pressure roller 20 and the heat roller 19,
Coating layer 12b having excellent release properties on the surface of metal belt 12a
And a tension applying member 21 that applies tension to the endless belt 12.

With the above configuration, the endless belt 12 receives heat supply from the heat roller 19. The base material of the endless belt 12 is a thin metal belt that can be easily deformed, and has a small heat capacity.
b, and the surface temperature of the heat roller 19 and the surface temperature of the endless belt 12 can be made substantially the same. The endless belt 12 efficiently heated by the heat roller 19 is sent to the nip area, and the continuous paper 7 is heated and pressed by the heating roller 11 and the heated endless belt 12 to apply the toner image 5 to the continuous paper 7. Fixing is completed.

The rubber layer 20a of the pressure roller 20 has a characteristic of low heat conductivity, which has a heat insulating effect to efficiently transfer the heat of the endless belt 12 to the continuous paper 7 and the toner image 5. Preferably. In addition, a heat source having a heat retaining effect may be provided inside the pressure roller 20 in order to prevent heat transfer to the pressure roller 20.

[0017]

As described above, according to the present invention, even if the elastic layer of the pressure roller is provided thick enough to obtain a sufficient nip width, the surface of the pressure roller can be sufficiently heated. Thus, it is possible to realize a fixing device of a double-sided recording apparatus capable of providing high-quality simultaneous double-sided fixing.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a fixing device of the present invention.

FIG. 2 is an overall configuration diagram of a double-sided recording apparatus equipped with a fixing device of the present invention.

[Explanation of symbols]

5 toner image, 7 continuous paper, 11 heating roller, 12
Endless belt, 17: heat source, 18: heat belt heating / pressing device, 19: heat roller, 20: pressure roller, 21: tension applying member.

Continued on the front page (72) Inventor Muneki Akai 1060 Takeda, Hitachinaka City, Ibaraki Prefecture Inside Hitachi Koki Co., Ltd. (72) Inventor Akihiko Yamazaki 1060 Takeda Hitachinaka City, Ibaraki Prefecture Inside Hitachi Koki Co., Ltd.

Claims (1)

[Claims] 1. A double-sided recording apparatus wherein a continuous paper holding an unfixed toner image on both front and back sides is nipped and conveyed while being heated and pressed by a pair of fixing members, and the toner image is simultaneously fixed on both sides of the continuous paper. In the fixing device, the fixing device includes a cylindrical core, an elastic layer provided on the core, and a heat source provided inside the core, and is supported so as to be able to contact one surface of the continuous paper. Heating roller, a pressure roller having an elastic layer thicker than the elastic layer of the heating roller, a heat roller having a heat source inside a cylindrical cored bar, and a heat roller and the pressure roller. A double-sided recording apparatus, comprising: a heat belt heating / pressing device comprising a passed endless belt, wherein the pressure roller is disposed so as to be able to contact the other surface of the continuous paper via the endless belt. Fixing device.