JP3195164B2 - Fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device which is mounted on an image forming apparatus such as a copying machine, a facsimile, a laser printer or the like by using an electrophotographic method.

[0002]

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

When the toner image is unfixed between the fixing roller pair, the unfixed toner image is heated and melted, and is pressurized and fixed on the transfer paper. Adheres to another place or another transfer paper, and forms a ghost image, deteriorating the image quality.

Therefore, conventionally, in order to prevent toner from adhering to the fixing roller, oil has been widely applied to the fixing roller in order to improve the releasability of the fixing roller. There are various methods for applying the oil. For example, as disclosed in Japanese Patent Application Laid-Open No. 62-5284, there is a method in which an oil is applied to a fixing roller from a tank storing oil through an application member such as felt. Other well-known coating methods include, for example, JP-A-61-1090.
No. 84, there is a roller in which a roller impregnated with high-viscosity oil is brought into contact with a fixing roller. Further, there is also known an application roller in which oil is incorporated in a hollow roller and an oil-impregnated layer is provided on an outer peripheral surface of a peripheral wall of the hollow roller, as disclosed in Japanese Utility Model Laid-Open No. 1-120171.

[0005]

By applying oil to the surface of the fixing roller in this way, most of the toner adhesion can be prevented, but not completely, and a small amount of toner and paper dust adhere to the fixing roller. That is inevitable. Such deposits then adhere to the oil application roller. When such adhesion is repeated, the surface of the oil application roller is eventually covered with the attached matter, and the oil application amount decreases. When the amount of oil applied is reduced, the releasability of the fixing roller is reduced, and toner sticking to the fixing roller may occur. In addition, if an adhering matter on an oil supply member (oil supply means) such as an application roller is peeled off and transferred to the fixing roller, and further transferred to the transfer paper, an abnormal image having small spots is formed on the transfer paper.

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

[0007]

According to the present invention, there is provided, in accordance with the present invention, means for supplying oil to a heating roller and a cleaning roller for cleaning the oil supply means. Each of the cleaning rollers is configured to be electrically insulated from the apparatus main body.

[0008] It is more preferable that at least the surface of the cleaning roller is made of a resin having the same or close to the surface active energy as that of the toner base resin.

It is preferable that a pressing member elastically contacting 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 preferable that the cleaning roller is formed in a barrel shape.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below based on embodiments shown in the drawings.

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

The transfer paper 14 after fixing is peeled off from the fixing roller 5 by a separation claw 9 arranged so that the leading end thereof is in contact with the fixing roller 5, and guided by paper discharge guide plates 11 and 12 to form a paper discharge roller pair. 13 is fed out of the fixing device. The thermistor 8 disposed around the fixing roller 5 contacts the fixing roller 5, detects the surface temperature of the fixing roller 5, and controls the temperature of the fixing roller 5.

An oil supply device 16 formed as a unit is disposed on the upper right side of the fixing device as viewed in the drawing. The oil supply device 16 mainly includes an oil application roller 2 serving as an oil supply unit that comes into contact with the fixing roller 5, and a cleaning roller 3 that cleans deposits on the surface of the oil application roller 2. Another member such as felt may be used as the 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 holding member will be described later.

As shown in FIG. 2A, the oil application roller 2 and the cleaning roller 3 are attached to each end by a bracket (not shown) of the oil supply device along a guide (not shown). And bearings 17 and 18 respectively supporting the respective shafts of the cleaning roller 3 are mounted, and the coil spring 20 presses the bearing 17 to
The oil application roller 2 is pressed against the fixing roller, and the plate spring 19 is pressed.
To press the cleaning roller 3 against the oil application roller 2. The opposite end of each of the rollers 2 and 3 has basically the same configuration.
The oil application roller 2 and the cleaning roller 3 rotate together with the fixing roller 5 and the oil application roller 3 with an appropriate pressure, but may be driven by different driving means.

As described above, the roller is pressed at the shaft end, and at least the surface of the oil application roller 2 is rich in elasticity. Therefore, the pressure of the contact portion between the oil application roller 2 and the cleaning roller 3 is reduced in the axial direction. It tends to be high at the edges and low as it approaches the center. Therefore, in order to achieve uniform contact pressure 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 at the center than at the end.

Bearings 17 and 18 for supporting the rollers 2 and 3
Is formed of insulating resin such as silicone resin or insulating porcelain such as silica.
As shown in FIG. 2B, it is covered with an insulating layer 3a made of an insulating material such as fluoro rubber. With such a configuration, when the oil application roller 2 and the cleaning roller 3 rotate, they are in an insulated state in the oil supply unit, so that static electricity is easily generated, and a small amount of adhered matter such as toner on the surface of the fixing roller. Is easily transferred to the oil application 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 similar surface active energy to the resin (a resin having a similar molecular structure). Is good. For example, polyester, polystyrene, polytetrafluoroethylene, and the like. With such a resin, since the deposit on the oil application roller 2 is mainly a mixture of toner and paper powder, the surface active energy is close and the deposit easily adheres to the cleaning roller 3.

FIG. 4A shows the surface of the cleaning roller 3.
As shown in the figure, knurls are provided in a mesh form. By applying the knurling in this manner, the cleaning roller bites into the oil application roller, the contact area increases, and the deposits on the oil application roller are easily transferred to the cleaning roller. The same effect can be obtained by forming grooves along the axial direction (FIG. 4B) or by forming grooves spirally (FIG. 4C).

Further, not only the surface of the cleaning roller is provided with knurls, but also, 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 preferred. With such a structure, as shown in FIG. 6, the deposits transferred from the oil application roller 2 are pushed into the inside of the cleaning roller 3 through the through holes of the cleaning roller 3 and accumulated. For this reason, it is possible to prevent the cleaning performance from deteriorating due to excessive attachments on the surface of the cleaning roller 3 or returning to the oil application roller or dropping in the unit due to excessive attachments on the roller surface. As a structure with many through holes,
In addition to the above-mentioned mesh structure, there can be cited 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. Since at least the surface of the cleaning roller contact portion of the pressing member 4 is made of a fluororesin such as polytetrafluoroethylene, it is difficult for the pressing member 4 to adhere to the cleaning member. Is securely and uniformly fixed on the roller surface. Since the adhesiveness of the pressing member is low, there is no possibility of removing the adhered matter on the cleaning roller. 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 pressing member 4 through the hole.

[0023]

According to the first aspect of the present invention, there is provided a fixing device including a means for supplying oil to the fixing roller and a cleaning roller for cleaning the oil supply means. Because 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 transfer to the oil supply means and the cleaning roller, thereby improving the cleaning performance. Can be.

According to the fixing device of the present invention, at least the surface of the cleaning roller is made of a resin having the same or close to the surface active energy as that of the toner base resin. The deposits are more easily transferred by the cleaning roller, and the effect of claim 1 is enhanced.

According to the third aspect of the present invention, since the pressing member that elastically contacts the surface of the cleaning roller is provided, the deposits on the cleaning roller are reliably and uniformly pressed against the cleaning roller. Thus, it is possible to prevent the attached matter of the cleaning roller from being peeled off and returning to the oil supply means, and the cleaning performance can be secured.

According to the fourth aspect of the present invention, since the surface of the cleaning roller is knurled, the cleaning roller bites into the oil application 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 formed of a porous hollow body,
The adhering matter transferred 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 adhering matter of the cleaning roller, and prevent the adhering matter from peeling off and returning to the oil supply means.

According to the fixing device of the present invention, since the cleaning roller is formed in 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. And cleaning properties can be made uniform.

[Brief description of the drawings]

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

FIGS. 2A and 2B are schematic diagrams illustrating attachment of an oil application roller and a cleaning roller of the fixing device, wherein 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 diagram illustrating 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 a mesh knurl, (b) is the groove in the axial direction, and (c) is the groove in a spiral shape.

5A and 5B show an example in which the cleaning roller is a porous hollow body, wherein FIG. 5A shows the roller surface and FIG. 5B shows the cross section.

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

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

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

[Explanation of symbols]

 Reference Signs List 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

──────────────────────────────────────────────────続 き Continued from the front page (72) Inventor Satoshi Takanashi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (56) References JP-A-6-118833 (JP, A) JP-A Heihei 4-3161572 (JP, A) JP-A-3-65977 (JP, A) JP-A-58-18662 (JP, A) JP-A-61-193169 (JP, A) JP-A-50-142034 (JP, A) A) JP-A-57-74768 (JP, A) JP-A-62-104267 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 13/20 G03G 15/20

Claims (6)

(57) [Claims] 1. A fixing device for heating and pressing an unfixed toner image on a sheet by a heating roller whose temperature is controlled, and a pressing roller which presses and rotates with the heating roller, means for supplying oil to the heating roller. A fixing device, comprising: a cleaning roller for cleaning the oil supply means; and wherein the oil supply means and the cleaning roller are electrically insulated from the apparatus main body, respectively. 2. The fixing device according to claim 1, wherein at least the surface of the cleaning roller is formed of a resin having the same or close to surface active energy as that of the toner base resin. 3. The fixing device according to claim 1, further comprising a pressing member that elastically contacts a surface of the cleaning roller. 4. The cleaning roller according to claim 1, wherein a knurl is provided on a surface of the cleaning roller.
The fixing device according to claim 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.