JP2004212408A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device in which the scarring on a fixing roll surface is effectively suppressed and toner soiling of a backside of transfer paper is also effectively solved. <P>SOLUTION: A fixing roll provided with a heat source inside and a press roll provided while abutting on the fixing roll are included in the fixing device and a toner image is fixed on the transfer paper surface by allowing the transfer paper with the toner image transferred to its surface to pass through a nip region between the fixing roll and the press roll. The fixing roll is provided to be abutted so that a metal or alloy rigid cleaning roll carries out a following rotation. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fixing device used in an electrophotographic image forming apparatus such as a copying machine, a facsimile, and a printer.
[0002]
[Prior art]
In an image forming apparatus based on electrophotography, an image is formed in the following manner.
That is, the photoreceptor is uniformly charged in a predetermined polarity, and is image-exposed by light irradiation based on predetermined image information to form an electrostatic latent image. Next, a developer is supplied to the surface of the photoreceptor to develop the electrostatic latent image to form a toner image on the surface of the photoreceptor, and the toner image is transferred to a predetermined paper using a transfer roller or a corona charger for transfer. (Transfer material). The transfer paper on which the toner image has been transferred is introduced into a fixing device, and the toner image is fixed on the surface of the transfer paper by heat and pressure. On the other hand, after the completion of the transfer, the toner remaining on the surface of the photoconductor is cleaned, and if necessary, static elimination is performed. Thus, one cycle of the image forming process is completed, and the next image is formed.
[0003]
The fixing device used in the above-described image forming apparatus includes a pair of a pressing roller and a fixing roller having a built-in heat source provided to face each other with a predetermined nip width. In a state where the toner image is heated to the fixing temperature, a predetermined sheet (transfer sheet) on which the toner image is formed passes through the nip area of the roller pair, and the toner image is pressed against the surface of the transfer sheet by the heated fixing roller. And a structure for fixing the toner image.
[0004]
In the fixing device as described above, a cleaning member for removing a toner adhered to a fixing roller using a web impregnated with silicone oil or the like is widely used (for example, see Patent Document 1).
[0005]
[Patent Document 1]
JP-A-9-6174 (FIGS. 1 to 6)
[0006]
[Problems to be solved by the invention]
That is, a fixing device as disclosed in Patent Document 1 stretches a cleaning web onto a take-up roller from a web roller around which a cleaning web impregnated with silicone oil or the like is wound. The fixing roller is cleaned by pressing the fixing web against the fixing roller by a pressing roller.The cleaning web is gradually taken up by a take-up roller, and the cleaning roller is always cleaned on a clean surface. Cleaning is performed.
[0007]
However, the above-described fixing device has a problem that fine flaws are generated in the fixing roller.
That is, an elastic roller is used as the fixing roller in order to secure an appropriate nip width between the fixing roller and the pressure roller. If the nip width is small, fixing is not effectively performed, and fixing unevenness is likely to occur. For this reason, fine flaws are generated on the surface of the elastic fixing roller by the cleaning web pressed by the pressing roller.
When the above-mentioned fine scratches occur on the surface of the fixing roller, the silicone oil oozing out of the cleaning web enters into the scratches, and when fixing is performed in this state, the resulting fixed image has fine fine particles. Streaky unevenness of gloss is generated in response to a scratch. Such gloss unevenness appears particularly in the case of a color image, and significantly impairs its commercial value.
[0008]
If the above-mentioned fine scratches are generated on the surface of the fixing roller, unfixed toner and the like accumulated in the portion where the cleaning web is pressed enter the scratches and gradually accumulate. If the fixing roller is started in such a state, unfixed toner and the like deposited on this portion will pass through the cleaning web, flow into the surface of the pressure roller, and contaminate the back surface of the transfer paper. This phenomenon varies depending on the amount of toner on the transfer paper supplied to the fixing device. However, in general, when a high-density color image is formed, the frequency of occurrence of the phenomenon becomes extremely high.
[0009]
Further, if the pressing force of the pressing roller is increased to increase the contact area between the cleaning web and the fixing roller, the amount of unfixed toner and the like accumulated in the portion where the web is pressed increases. Therefore, even in this case, when the fixing roller is started, unfixed toner or the like passes through the cleaning web and flows into the surface of the pressure roller, thereby contaminating the back surface of the transfer paper.
In order to solve such a problem, it is conceivable that the contact area between the web and the fixing roller is reduced by pulling the web upward at the pressing roller portion to reduce the curvature of the web, but in this case, In this case, the pressing force of the pressing roller is concentrated, and the generation of scratches on the surface of the fixing roller becomes more remarkable.
[0010]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fixing device in which the generation of scratches on the surface of a fixing roller is effectively suppressed, and the toner contamination on the back surface of a transfer sheet is also effectively solved.
[0011]
[Means for Solving the Problems]
According to the present invention, a fixing roller having a heat source therein and a pressure roller provided in contact with the fixing roller are provided, and a toner image is transferred to the surface in a nip area between the fixing roller and the pressure roller. A fixing device for fixing the toner image on the surface of the transfer paper by passing the transferred transfer paper,
A fixing device is provided, wherein a rigid cleaning roller made of a metal, an alloy, or a resin having a hardness (Asuka C) of 50 or more is in contact with the fixing roller so as to be driven to rotate. .
[0012]
That is, in the present invention, since the cleaning of the surface of the fixing roller is performed by the rigid roller that rotates following the fixing roller, the generation of scratches on the surface of the fixing roller can be effectively avoided. Further, since the web is not used, even if a rigid roller (cleaning roller) is strongly pressed against the fixing roller in order to enhance the cleaning property, there is no possibility that a scratch is generated unlike the case where the web is used.
Further, since the above-mentioned rigid roller rotates following the fixing roller, the unfixed toner does not accumulate on the portion where the rigid roller is pressed, and the unfixed toner pressing roller when the fixing roller is activated. Can be effectively avoided, and toner contamination on the back surface of the transfer paper can be effectively prevented.
[0013]
In the present invention,
1. An oil, for example, a cleaning web impregnated with silicone oil is pressed against the cleaning roller (rigid roller);
2. A pressing roller is provided facing the cleaning roller, the cleaning web is sandwiched between the pressing roller and the cleaning roller, and the cleaning roller is pressed against the fixing roller by the pressing roller. That
Is preferred.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
In FIG. 1, which shows a schematic structure of the fixing device of the present invention, the fixing device includes a fixing roller 1, a pressure roller 2, and a cleaning roller 3. The pressure roller 2 is provided so as to press against the fixing roller 1 (a pressure mechanism is omitted). The fixing roller 1 and the pressure roller 2 abut on each other with a predetermined nip width. The cleaning roller 2 and the cleaning roller 3 are configured to rotate following the rotation of the fixing roller 1.
[0015]
The fixing roller 1 has a heat source 5 such as a halogen lamp inside, and the same heat source 5 is also provided inside the pressure roller 2. Of course, the heat source 5 may be provided only inside the fixing roller 1. Generally, the surface of the fixing roller 1 is heated to a predetermined fixing temperature (generally, 130 to 180 ° C.), and in this state, the transfer paper 7 having the toner image 6 on the surface is separated by the fixing roller 1 and the pressure roller 2. And the toner image 6 is fixed on the surface of the transfer paper 7 by the heat and pressure applied at this time.
[0016]
Further, the fixing roller 1 has an elastic layer 12 on a hollow core shaft 10 in order to secure an appropriate nip width between the fixing roller 1 and the pressure roller 2. Further, a fluorine-containing resin layer 14 is provided on the elastic layer 12 in order to prevent the toner from adhering or fusing to the surface.
[0017]
The core shaft 10 is formed of a metal or alloy material such as iron, aluminum, copper, nickel, and stainless steel, but may be omitted as long as the fixing roller 1 can rotate without distortion.
[0018]
The elastic layer 12 is formed of various rubbers, for example, silicone rubber, polybutadiene rubber, chloroprene rubber, isoprene rubber, polyolefin rubber, polyurethane rubber, acrylic rubber, or copolymer rubber such as EPDM. In order to suppress as much as possible and stabilize the surface temperature at the time of fixing, it is preferable to be formed of an elastic material having a high heat capacity. Specifically, it is preferably formed of a foam of the above rubber, particularly a foam of silicon rubber.
[0019]
The fluorine-containing resin layer 14 formed on the surface of the fixing roller 1 is made of polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkylvinyl ether copolymer (PFA), tetrafluoroethylene / hexafluoropropylene copolymer ( FEP), polychlorotrifluoroethylene (PCTFE), ethylene / tetrafluoroethylene copolymer (ETFE), ethylene / chlorotrifluoroethylene copolymer (ECTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF) Among them, polytetrafluoroethylene (PTFE) and tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA) are preferable, and PFA is most preferable.
[0020]
In addition, it is generally preferable that the Aska C hardness of the fluorine-containing resin layer 14 be in the range of 20 to 70 degrees in order to bring the pressure roller 2 and the heating roller 3 into close contact with a sufficient nip width.
[0021]
Further, the fluorine-containing resin layer 14 preferably has a thickness of 10 to 100 μm. If the fluorine-containing resin layer 14 is too thick, the elasticity of the elastic body layer 12 is impaired, and it becomes difficult to make the nip width with the pressure roller 2 sufficiently large. If the thickness of the fluorine-containing resin layer 14 is thinner than necessary, the mechanical properties such as the strength of the layer become unsatisfactory, and the durability of the fixing roller 1 may be reduced. Molding also becomes difficult.
[0022]
The fixing roller 1 as described above can be manufactured at low cost, for example, by winding a fluororesin film around a roller having the elastic layer 12.
[0023]
The pressure roller 2 provided with a predetermined nip width with respect to the fixing roller 1 described above is formed of a metal or an alloy having high thermal conductivity, for example, iron, stainless steel, copper, aluminum, nickel, or the like.
Also, if necessary, a fluorine-containing resin layer can be provided on the surface of the pressure roller 2 as well as the fixing roller 1.
[0024]
In the present invention, a rigid roller is used as the cleaning roller 3. That is, the cleaning roller (hereinafter, also referred to as a rigid roller) 3 is a raw pipe made of a metal or alloy such as iron, stainless steel, copper, aluminum, and nickel, or a rigid pipe having a hardness (Asuka C) of 50 or more. It is made of a base tube made of a resin, for example, a polyamide resin such as polycarbonate or nylon. That is, by performing cleaning of the fixing roller 1 (removal of unfixed toner and the like adhering to the surface of the fixing roller 1) using such a rigid roller 3, generation of scratches on the surface of the fixing roller 1 is effectively prevented. be able to. Further, since the rigid roller 3 rotates following the fixing roller 1, unfixed toner does not accumulate on the portion (nip portion) against which the rigid roller 3 is pressed. For example, when the fixing roller 1 is activated. Further, such unfixed toner does not flow to the pressure roller 2 side, and therefore, the back surface of the transfer paper 7 can be effectively prevented.
[0025]
In the present invention, it is preferable that the rigid roller 3 has a smaller diameter than the fixing roller in terms of cleaning performance. That is, if the diameter of the rigid roller 3 is too large, the pressing force of the rigid roller 3 against the fixing roller 1 becomes non-uniform, which not only tends to cause uneven cleaning but also increases the size of the apparatus.
[0026]
As shown in FIG. 1, the rigid roller 3 is pressed against the surface of the fixing roller 1 by a pressing roller 20, and a desired cleaning property is secured by the pressing. It is preferable to interpose a cleaning web 22 impregnated with an oil for preventing offset such as silicone oil between the roller (cleaning roller) 3.
That is, the cleaning web 22 is wound around a web roller 24, and is further wound up by a winding roller 26. By the cleaning web 22, unfixed toner adhering to the rigid roller 3 is collected, and at the same time, oil is supplied to the surface of the fixing roller 1 via the cleaning roller 3 to effectively prevent offset.
[0027]
In the present invention, the above-described pressing roller 20 may be a rigid roller or an elastic roller having a high flexibility. It is preferable to use an elastic roller made of various rubbers or the like.
[0028]
Further, as the web 22, a nonwoven fabric such as a cotton cloth, paper, or the like can be used.
Further, the web 22 is used so as to be wound up little by little by a winding roller 26.
[0029]
In the present invention, a fluorine-containing resin layer may be formed on the surface of the rigid roller 3 as in the case of the fixing roller 1. That is, by forming such a fluorine-containing resin layer, the unfixed toner can be efficiently collected from the rigid roller 3 by the web 22.
[0030]
In the present invention, if an elastic roller is used in place of the rigid roller 3 described above, it is difficult to prevent toner recontamination, even if the occurrence of scratches on the surface of the fixing roller 1 can be avoided. In other words, when cleaning is performed using the elastic roller, it is necessary to strongly press against the surface of the fixing roller 1 in order to secure a desired cleaning property. As a result, the nip width with the fixing roller 1 increases. A large amount of unfixed toner accumulates in the nip portion, and the unfixed toner flows at once when the fixing roller 1 is started up, flows into the pressure roller 2 side, and causes the back surface of the transfer paper 7 to be stained. In the present invention in which cleaning is performed using the rigid roller 3, such inconvenience is effectively avoided.
[0031]
【The invention's effect】
According to the present invention, since the cleaning is performed by the rigid roller that rotates following the fixing roller, it is possible to effectively avoid the generation of scratches on the surface of the fixing roller.
Further, since the rigid roller (cleaning roller) is rotated following the fixing roller, the unfixed toner does not accumulate, and the unfixed toner flows out to the pressure roller when the fixing roller is started. The toner stain on the back surface of the transfer paper is also effectively prevented.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic structure of a fixing device of the present invention.
[Explanation of symbols]
1: fixing roller 2: pressure roller 3: cleaning roller (rigid roller)
20: pressing roller 22: cleaning web impregnated with oil

Claims (3)

It consists of a fixing roller equipped with a heat source inside and a pressure roller provided in contact with the fixing roller, and passes through the transfer paper on which the toner image has been transferred to the nip area between the fixing roller and the pressure roller. In the fixing device for fixing the toner image on the transfer paper surface,
A fixing device, wherein a rigid cleaning roller made of a metal, an alloy, or a resin having a hardness (Asuka C) of 50 or more is provided in contact with the fixing roller so as to be driven to rotate. The fixing device according to claim 1, wherein a cleaning web impregnated with oil is pressed against the cleaning roller. A pressing roller is provided facing the cleaning roller, the cleaning web is sandwiched between the pressing roller and the cleaning roller, and the cleaning roller is pressed against the fixing roller by the pressing roller. The fixing device according to claim 2.

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