JPH0816017A - Fixing apparatus - Google Patents

Abstract

PURPOSE:To provide a fixing apparatus which can utilize static electricity generated in a cleaning roller for a purpose to improve a cleaning function more than a conventional one by composing a means to supply an oil to a heating roller and the cleaning roller to clean the oil supplying means in the way the means and the cleaning roller can be electrically insulated from an apparatus main body, resp. CONSTITUTION:An oil supplying apparatus 16 composed as a unit is installed in the right upper side of a fixing apparatus shown as a figure. The oil supplying apparatus 16 is composed of mainly an oil applying roller 2, which is an oil supplying means to come into contact with a fixing roller 5 and a cleaning roller 3 to clean the adhering substances on the surface of the oil applying roller 2. The bearings supporting rollers 2, 3 respectively are made of insulating materials such as silicone resin, etc., and the surface of the cleaning roller 3 is coated with an insulating layer. Consequently, substances adhering to a fixing roller 5 easily transfer to the oil applying roller 2 and the cleaning roller 3 due to static electricity generated by rotation of the cleaning roller 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device mounted on an image forming apparatus such as a copying machine, a facsimile, a laser printer or the like, which uses an electrostatic photography system.

[0002]

2. Description of the Related Art In an electrostatic image forming apparatus,
The unfixed image formed on the transfer paper by the toner in the image forming section is carried into the fixing device, sandwiched between the heating roller and the pressure roller pressed against the fixing roller, fixed on the transfer paper, and ejected. It is designed to be ejected onto the tray.

When sandwiched between the pair of fixing rollers, the unfixed toner image is heated and melted, and is pressed to be fixed on the transfer paper. Adheres to another place or another transfer paper to form a ghost image, impairing the image quality.

Therefore, in order to prevent toner from adhering to the fixing roller, it has been widely practiced to apply oil to the fixing roller in order to improve the releasing property of the fixing roller. There are various methods for applying the oil, and for example, as disclosed in Japanese Patent Laid-Open No. 62-5284, there is a method for applying the oil to a fixing roller from an oil storage tank with an application member such as felt interposed. Other well-known coating methods include, for example, JP-A-61-1090.
In some cases, a roller impregnated with high-viscosity oil is brought into contact with a fixing roller as disclosed in Japanese Patent Laid-Open No. 84. Further, there is also known a coating roller as disclosed in Japanese Utility Model Laid-Open No. 1-120171, in which oil is contained in a hollow roller and an oil impregnating layer is provided on the outer peripheral surface of the peripheral wall of the hollow roller.

[0005]

By applying oil to the surface of the fixing roller in this manner, most of toner adhesion can be prevented, but it is not perfect, and a small amount of toner or paper dust adheres to the fixing roller. It is inevitable. Such adhered substances will then adhere to the oil application roller. When such adhesion is repeated, the surface of the oil application roller is eventually covered with the adhered matter, and the oil application amount decreases. When the amount of oil applied decreases, the releasability of the fixing roller deteriorates, and toner sticking to the fixing roller occurs. Further, when the adhering material on the oil supply member (oil supply means) such as the application roller is peeled off and transferred to the fixing roller, and further transferred to the transfer paper, an abnormal image with small spots is formed on the transfer paper.

Therefore, as means for cleaning the oil supply means,
Although it is conceivable to use a cleaning roller, it is an object of the present invention to provide a fixing device that can use the static electricity generated by the cleaning roller for the purpose of further improving the cleaning performance of the cleaning roller.

[0007]

In order to solve the above problems, according to the present invention, means for supplying oil to a heating roller and a cleaning roller for cleaning the oil supplying means are provided, and these oil supplying means are provided. Each cleaning roller is configured to be electrically insulated from the main body of the apparatus.

It is even better if at least the surface of the cleaning roller is made of a resin which has the same surface-active energy as the toner base resin or is close to the resin.

Further, it is preferable that a pressing member which comes into elastic contact with the surface of the cleaning roller is provided.

The surface of the cleaning roller is preferably knurled. Alternatively, the cleaning roller may be formed of a porous hollow body.

It is also preferable that the cleaning roller is formed in a barrel shape.

[0012]

The details of the present invention are explained below based on the embodiments shown in the drawings.

In FIG. 1 showing the structure of a fixing device according to the present invention, a transfer paper 14 having an unfixed toner image conveyed from a transfer section (not shown) is guided by an entrance guide plate 15,
The toner image is nipped between the heating roller 5 (fixing roller) having the heater 7 built therein and the pressure roller 6 rotatably pressed against the heating roller 5, and the toner image is heated and pressed to transfer the transfer paper 14
Is fixed in.

The transfer paper 14 after fixing is peeled off from the fixing roller 5 by a separating claw 9 arranged so that its tip is in contact with the fixing roller 5, and is guided by the paper discharge guide plates 11 and 12 so that a pair of paper discharge rollers is provided. By sending 13, the sheet is discharged from the fixing device. The thermistor 8 arranged around the fixing roller 5 contacts the fixing roller 5, detects the surface temperature of the fixing roller 5, and is used for temperature control of the fixing roller 5.

On the upper right side of the fixing device as seen in the drawing, an oil supply device 16 formed as a unit is arranged. The oil supply device 16 is mainly composed of an oil application roller 2 which is an oil supply means which comes into contact with the fixing roller 5, and a cleaning roller 3 which cleans adhered matters on the surface of the oil application roller 2. You may employ another member, such as felt, as an oil supply means. A curved plate-shaped pressing member attached to the frame of the oil supply device 16 elastically contacts the surface of the cleaning roller 3 (not shown in FIG. 1). The pressing member will be described later.

As shown in FIG. 2a, the oil applying roller 2 and the cleaning roller 3 are attached to respective ends of the oil applying roller 2 along a guide (not shown) on a bracket (not shown) of the oil supply device. And bearings 17 and 18 respectively supporting the respective shafts of the cleaning roller 3 and the cleaning roller 3 are mounted, and the coil spring 20 presses the bearing 17,
The oil application roller 2 is brought into pressure contact with the fixing roller, and the leaf spring 19
The bearing 18 is pressed by and the cleaning roller 3 is brought into pressure contact with the oil applying roller 2. The opposite ends of the rollers 2 and 3 are basically configured in the same manner.
The oil applying roller 2 and the cleaning roller 3 are brought into contact with the fixing roller 5 and the oil applying roller 3 with appropriate pressures to rotate together, but they may be driven by different driving means.

As described above, the shaft end portion of the roller is pressed, and at least the surface of the oil applying roller 2 is highly elastic. Therefore, the pressure at the contact portion between the oil applying roller 2 and the cleaning roller 3 is in the axial direction. It tends to be high at the edges and low as it approaches the center. Therefore, in order to make the contact pressure uniform in the axial direction, as shown in FIG. 3, the cleaning roller 3 is formed in a so-called barrel shape in which the outer diameter of the roller is larger in the central portion than in the end portions.

Bearings 17, 18 for supporting the rollers 2, 3
Is formed of an insulating resin such as a silicone resin or an insulating porcelain such as silica. The surface of the cleaning roller 3 is
As shown in FIG. 2b, it is covered with an insulating layer 3a made of an insulating material such as fluororubber. With such a configuration, when the oil applying roller 2 and the cleaning roller 3 rotate, they are in an insulating state in the oil supply unit, so that static electricity easily occurs, and a small amount of adhered matter such as toner on the surface of the fixing roller. Is easily transferred to the oil applying roller 2 and the cleaning roller 3, and the cleaning performance is improved.

At least the surface material of the cleaning roller 3 is not only insulating but also the same resin as the base resin of the toner, or a resin having a surface active energy close to that of the resin (having a similar molecular structure). Is good. For example, polyester, polystyrene, polytetrafluoroethylene and the like. With such a resin, since the adhered matter on the oil application roller 2 is mainly a mixture of toner and paper powder, the surface active energy is close and the adhered matter is likely to adhere to the cleaning roller 3.

The surface of the cleaning roller 3 is shown in FIG.
As shown in, the knurling is attached in a mesh shape. By providing the knurls in this way, the cleaning roller bites into the oil applying roller, the contact area increases, and the adhered matter on the oil applying roller easily moves to the cleaning roller. The same effect can be obtained by forming a groove along the axial direction (Fig. 4b) or forming a spiral groove (Fig. 4c).

Further, not only is the knurled surface provided on the surface of the cleaning roller, but as shown in FIG. 5, the roller is formed of a hollow body, and its thick portion has a large number of through holes such as a mesh structure. If the structure has
It is still preferable. With such a structure, as shown in FIG. 6, the adhering matter transferred from the oil applying roller 2 is pushed into the inside of the roller through the through hole of the cleaning roller 3 and accumulated. Therefore, it is possible to prevent the cleaning roller 3 from being excessively attached to the surface thereof to deteriorate the cleaning performance, or to be attached to the surface of the roller too much to return to the oil application roller or drop in the unit. As a structure including a large number of through holes,
In addition to the mesh structure described above, there may be mentioned one having a large number of circular holes.

As shown in FIG. 7, a pressing member 4 made of, for example, polyimide is in elastic contact with the cleaning roller 3. At least the surface of the pressing member 4 that contacts the cleaning roller is made of a fluororesin such as polytetrafluoroethylene. Are securely and evenly adhered to the roller surface. Since the adhesion of the pressing member is low, the adhered matter on the cleaning roller is not peeled off. If the cleaning roller is a porous hollow body, as shown in FIG. 8, the adhered matter on the roller is forcibly pushed into the inside of the roller by the holding member 4.

[0023]

According to the fixing device of the first aspect, the fixing roller is provided with means for supplying oil to the fixing roller and a cleaning roller for cleaning the oil supplying means. Since it is configured to be electrically insulated from the main body, the static electricity generated by the rotation of the cleaning roller makes it easier for the deposits on the fixing roller to move to the oil supply means and the cleaning roller, thus improving the cleaning performance. You can

According to the fixing device of the second aspect, at least the surface of the cleaning roller is made of a resin having a surface active energy which is the same as or close to that of the toner base resin. The adhering substances of (1) are more easily transferred by the cleaning roller, and the effect of claim 1 is enhanced.

According to the fixing device of the third aspect, since the pressing member that comes into elastic contact with the surface of the cleaning roller is provided, the deposits on the cleaning roller are pressed against the cleaning roller reliably and uniformly. Therefore, it is possible to prevent the adhered matter from the cleaning roller from peeling off and returning to the oil supply means, and it is possible to secure the cleaning performance.

According to the fixing device of the fourth aspect, since the surface of the cleaning roller is knurled, the cleaning roller bites into the oil applying means,
The contact area increases, and the deposits on the oil supply means are easily transferred to the cleaning roller.

According to the fixing device of the fifth aspect, since the cleaning roller is composed of the porous hollow body,
The adhered matter that has moved to the cleaning roller is pushed into the inside of the roller, and it is possible to prevent deterioration of the cleaning performance due to excessive adhered matter on the cleaning roller and to prevent the adhered matter from being peeled off and returning to the oil supply means.

According to the fixing device of the sixth aspect, since the cleaning roller is formed into a barrel shape, the contact pressure with the oil supply means can be made substantially uniform in the axial direction, and the oil application amount in the axial direction can be made uniform. It is possible to achieve uniformization and uniform cleaning property.

[Brief description of drawings]

FIG. 1 is a schematic view of a fixing device according to the present invention.

2A and 2B are schematic diagrams illustrating the attachment of an oil application roller and a cleaning roller of a fixing device, FIG. 2A shows that each roller is supported by a bearing, and FIG. 2B is a cross section of the cleaning roller.

FIG. 3 is a schematic view showing an example of a cleaning roller.

FIG. 4 is a schematic view showing an example of a cleaning roller surface,
(A) is the one with mesh knurls, (b) is the one with axial grooves, and (c) is the one with spiral grooves.

FIG. 5 shows an example in which the cleaning roller is a porous hollow body, in which (a) shows the roller surface and (b) shows a cross section.

6 is a diagram showing a state in which an adhering substance is pushed into the inside of a hollow body cleaning roller of FIG. 5 through a through hole.

FIG. 7 is a schematic view showing a state where a pressing member elastically contacts a cleaning roller.

FIG. 8 is a partial schematic view showing a pressing state of the pressing member when the cleaning roller is a hollow body.

[Explanation of symbols]

 2 Oil application roller 3 Cleaning roller 5 Fixing roller 6 Pressure roller 7 Heater 8 Thermistor 9 Separation claw 11, 12 Paper ejection guide plate 13 Paper ejection roller pair 14 Transfer paper 15 Guide plate 16 Oil supply device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Takanashi 1-3-3 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (6)

[Claims] 1. A fixing device that heats and presses an unfixed toner image on a sheet by a temperature-controlled heating roller and a pressure roller that rotates in pressure contact with the heating roller, and means for supplying oil to the heating roller. A fixing device, comprising: a cleaning roller for cleaning the oil supply means, wherein the oil supply means and the cleaning roller are electrically insulated from the main body of the apparatus. 2. The fixing device according to claim 1, wherein at least the surface of the cleaning roller is made of a resin having a surface active energy which is the same as or close to that of the toner base resin. 3. The fixing device according to claim 1, further comprising a pressing member that elastically contacts the surface of the cleaning roller. 4. The knurled surface is provided on the surface of the cleaning roller.
The fixing device according to any one of 1. 5. The fixing device according to claim 1, wherein the cleaning roller is formed of a porous hollow body. 6. The fixing device according to claim 1, wherein the cleaning roller is formed in a barrel shape.