JP2000330411A - Web feeding mechanism for heat fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of soiling by oil of transfer paper due to a great quantity of offset prevention liquid dripping to a heating roll from a web that is wound to a web feeding roll while preventing generation of a side effect and any rise in cost while at the same time preventing an extreme deterioration in d kinematic viscosity of the offset prevention liquid by moving the web feeding roll away from the heating roll and lowering the surrounding temperature in vicinity of the web feeding roll. SOLUTION: In a heat fixing device provided with the web 10 coming into contact with the heating roll 1 and a web feeding mechanism 5 sequentially feeding the new web surface while keeping the web surface in a pressurized contact with the heating roll, the web feeding mechanism is provided with the web feeding roll 11 feeding the web toward the heating roll, a press contact means 12 bringing the web surface into a pressurized contact with the heating roll, a web winding up roll 13 winding up the web surface whose pressurized contact with the heating roll is finished and driving mechanisms 14 and 15 driving each web winding up roll are provided. In this case, the web feeding roll is installed in a position that is sufficiently separated from the heating roll in a horizontal direction or the web feeding roll is separated from the fixing roll.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic copying machine,
The present invention relates to an improvement in an image forming apparatus such as a printer and a plain paper facsimile apparatus, and more particularly to an improvement in a web supply apparatus used in a heat fixing device used in an image forming apparatus.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus,
2. Description of the Related Art A heat fixing device is used as a means for fixing a toner image transferred onto a transfer sheet by applying pressure while heating in an image forming unit. This heat fixing device includes a heating roller having a heat generating means on the inner or outer surface thereof, and a pressure roller which presses against a peripheral surface of the heating roller, and transfers the transfer paper carrying the unfixed toner image to both rollers. , The toner image is heated and pressurized and fixed. By the way, what is most problematic in the fixing device is the contamination of the heating roller by toner or the like, and the occurrence of an offset phenomenon or the like in which the toner once fixed on the transfer paper peels off and adheres to the heating roller side. In order to prevent such a problem from occurring, a web device (web supply mechanism) for cleaning the heating roller and applying an anti-offset liquid is used in the heat fixing device. The web device has a web, i.e., a long material made of a material that absorbs and retains the anti-offset liquid, and has one end fixed to the take-up roller, the other end wound around the web supply roller, and sent out from the supply roller. A configuration is provided in which the web is wound by a wind roller. Then, the web drawn between the rollers is pressed against the heating roller by a pressing means for pressing the web against the peripheral surface of the heating roller, so that the dirt on the heating roller is wiped, and at the same time, the silicon oil or the like previously impregnated in the web is used. Apply anti-offset liquid. The take-up roller is rotated in the take-up direction by a driving device such as a motor, and takes up the web surface that has been pressed against the heating roller, and the new web surface is constantly pressed against the heating roller surface. Does not drop.

Incidentally, the surface of the heating roller is 150 to 21.
Since the temperature is controlled at 0 ° C., the temperature around the heating roller also becomes high. Silicon oil generally used as an offset preventing liquid (release agent) for a heating roller is 80 to 1
It is known that when the temperature exceeds 00 ° C., the kinematic viscosity extremely decreases. In general, a web supply roller (web apparatus) is often disposed directly above a heating roller (for example, Japanese Patent Application Laid-Open No. 58-199371, "Cleaning Web", and Japanese Patent Application Laid-Open No. 1-237583, " Peripheral surface cleaning device ”), the anti-offset liquid uniformly impregnated in the web is placed in a high-temperature atmosphere, and the kinematic viscosity is reduced. Therefore, the anti-offset liquid easily moves downward in the supply roller. Accumulate. For this reason, before the web sent from the supply roller contacts the heating roller at the pressure contact position, the web stretched directly from the web supply roller and further from the web stretched between the web supply roller and the pressure contact means on the surface of the heating roller. A large amount of the anti-offset liquid is easily dripped, and as a result, a situation in which oil stains occur on the transfer paper has occurred. Conventional examples of solving such problems include, for example, a method of increasing the kinematic viscosity of the anti-offset liquid to prevent dripping, and a method of encapsulating the anti-offset liquid in microcapsules (JP-A-4-3088).
No. 80, “Circumferential surface cleaning device for fixing rotating body”)
Was proposed. However, there is a problem that the side effect of reducing the amount of application to the heating roller occurs, and the configuration of the anti-offset liquid is complicated, so that the cost is extremely increased.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and an object of the present invention is to reduce the ambient temperature around the web supply roller by moving the web supply roller away from the heating roller. This prevents the kinematic viscosity of the anti-offset liquid from dropping extremely, suppresses the occurrence of side effects and increases the cost, and also causes the anti-offset liquid to dripping onto the heating roller from the web wrapped around the web supply roller. The purpose is not to generate. A second object of the present invention is to reduce the ambient temperature at which the web supply roller is disposed without increasing the size of the web supply mechanism by isolating the supply roller from the heating roller. A third object of the present invention is to further cool the web supply roller by arranging the supply roller in a cooling duct and directly blowing cold air to the web supply roller. A fourth object of the present invention is to make the core metal of the web supply roller a hollow shape such as a pipe, and to flow cool air into the core, thereby lowering the core metal temperature of the supply roller and preventing the temperature of the supply roller from rising. I have.

[0005]

In order to achieve the above object, the present invention is directed to a fixing roller pair including a heating roller heated by a heater, and a pressing roller pressed against the heating roller. A web supply mechanism that presses the web against the heating roller and sequentially supplies a new web surface to the heating roller, wherein the web supply mechanism supplies the web toward the heating roller. A roller, pressing means for pressing the web surface against the heating roller, a web winding roller for winding the web surface after the pressing with the heating roller, and a drive mechanism for driving each web winding roller, It is characterized in that the web supply roller is disposed at a position sufficiently spaced in the lateral direction from the heating roller. The invention according to claim 2 is characterized in that the web supply roller is separated from the heating roller. The invention according to claim 3 is characterized in that the web supply roller is disposed in the cooling duct. The invention according to claim 4 is characterized in that the core metal of the web supply roller is formed in a hollow shape such as a pipe, and cool air is flowed inside the core metal.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. FIG. 1 is a schematic configuration diagram of a heat fixing device provided with a web supply mechanism of the present invention. The heat fixing device includes a heating roller 1 having a heater 2 therein,
A fixing roller pair including a pressure roller 3 that is in pressure contact with the peripheral surface of the heating roller 1, a temperature detecting unit 4 such as a thermistor,
A web supply mechanism 5. A pressure roller 3 having an elastic body surface on a heating roller 1 heated by a heater 2
Is pressed, and the transfer paper P having an unfixed image passes through the nip portion of the pair of fixing rollers, so that the transfer paper P is heated and pressurized to perform fixing. The web supply mechanism 5 includes a web 10
Supply roller 11 for supplying the heat toward heating roller 1
Pressing means 12 for pressing the web surface against the heating roller 1
And a web take-up roller 13 that winds the web surface that has been pressed against the heating roller 1, a motor 14 that drives each roller, and a control unit 15 that controls the motor. The motor 14 and the control unit 15 constitute a driving mechanism. In order to apply oil for preventing offset to the surface of the heating roller 1 and to clean the surface,
A web supply mechanism 5 is provided. The web supply roller 11 includes a supply shaft 11a and a web 10 wound around the supply shaft 11a. The winding roller 13 has a winding shaft 13a. The web 10 has one end fixed to the winding shaft 13a and the other end connected to the supply shaft 11a.
The web 10 wound between the rollers 11 and 13 is pressed against the heating roller 1 by the pressing means 12. The pressing means 12 includes a pressing roller 12a for pressing the web 10 against the heating roller, and an elastic member 12b for pressing the pressing roller 12a against the heating roller. The web 10 is pressed against the surface of the rotating heating roller to wipe off dirt on the heating roller 1. In addition, web 1
The oil is applied by impregnating the offset prevention liquid such as silicone oil into the inside of 0. Thereafter, the web take-up roller 13 is rotated by a motor 14 or the like,
The web 10 wound around 1a is gradually wound up.
The set values such as the winding amount and the winding interval are changed according to fixing conditions, transfer paper, environment, images, and the like. In FIG. 1, the web supply roller, which was conventionally disposed immediately above the heating roller 1, is disposed in the lateral direction from the heating roller 1, so that the oil impregnated in the web by the heat from the heating roller is heated. The situation of dripping on the top can be prevented.

Next, FIG. 2 is a block diagram of another embodiment of the present invention, and the same parts as those of FIG. A characteristic configuration of this embodiment is that the web supply roller 11 is disposed at a position sufficiently distant from the heating roller 1, in other words, at a position distant from the heating roller 1 so that the offset preventing liquid impregnated by the web is not adversely affected by heat. It is in the point which did. According to this, the web supply roller 11
No decrease in the kinematic viscosity of the anti-offset liquid impregnated in the web 10 is observed, and a large amount of the anti-offset liquid dripping on the surface of the heating roller 1 and the transfer paper P does not occur. Next, FIG.
This is another embodiment of the present invention. In this embodiment, the arrangement position of the web supply roller 11 is not largely separated from the heating roller 1 as in the case of FIG. In this embodiment, as shown, the web supply roller 11 is surrounded by a partition wall (heat-resistant resin, heat insulating material, or the like) 20 and is isolated from the heating roller 1. Even if they are close to each other, a large amount of the anti-offset liquid does not drip.

FIG. 4 shows another embodiment of the present invention. In this embodiment, the web supply roller is not largely separated from the heating roller 1. Instead, in this embodiment, the web supply roller 11 is
The cooling air is blown into the cooling duct 25 from a fan (not shown) or the like. For this reason, the cool air is directly blown against the supply roller 11 by a fan or the like, so that the supply roller 11 can be further cooled without being sufficiently separated from the heating roller 1 (even if it is close to the heating roller 1). In addition, a large amount of the anti-offset liquid can be prevented from dripping. Next, FIG. 5 shows another embodiment of the present invention. Also in this embodiment, the web supply roller is not largely separated from the heating roller 1. Instead, in this embodiment, the supply roller (core bar) 11a is formed in a hollow shape such as a pipe, and the supply roller 11 is cooled by flowing cool air through a fan or the like (not shown). . For this reason, similarly, a large amount of the anti-offset liquid can be prevented from dripping. Further, even if the supply shaft 11a is a heat pipe and a radiating fin is attached to the end thereof to cool the fin, the same effect can be obtained because the heat pipe quickly transfers the heat of the supply roller to the fin. . The configuration of the embodiment shown in FIG. 5 may be combined with the embodiment shown in FIG. 2, FIG. 3, or FIG. Further, all the above embodiments can be used in combination with all the other embodiments.

[0009]

As described above, according to the first aspect of the present invention,
By keeping the web supply roller away from the heating roller and lowering the ambient temperature around the web supply roller, the kinematic viscosity of the anti-offset liquid is prevented from drastically lowering and wrapping around the web supply roller while suppressing side effects and cost increases. It is possible to prevent generation of oil stains on the transfer paper due to a large amount of offset prevention liquid dripping from the web onto the heating roller. That is, since the web supply roller is moved away from the heating roller and the temperature of the atmosphere in which the web supply roller is placed can be lowered, the kinematic viscosity of the offset prevention liquid impregnated in the web supply roller does not decrease, and the offset prevention liquid is not heated. Also, the transfer paper and the entrance guide plate are prevented from generating oil stains on the transfer paper caused by dripping in large quantities. According to the second aspect of the present invention, by separating the supply roller from the heating roller by the partition wall, the temperature of the atmosphere where the web supply roller is disposed can be lowered without increasing the size of the web supply mechanism. According to the third aspect of the present invention, the web supply roller can be further cooled by arranging the supply roller in the cooling duct and directly applying the cool air to the web supply roller. According to the invention of claim 4, the core metal of the web supply roller is formed into a hollow shape such as a pipe, and the inside of the web is cooled by flowing cool air to lower the core metal temperature of the supply roller and prevent the temperature of the supply roller from rising. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a heat fixing device including a web supply mechanism according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a heat fixing device provided with a web supply mechanism according to another embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of a heat fixing device including a web supply mechanism according to another embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a heat fixing device including a web supply mechanism according to another embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a heat fixing device provided with a web supply mechanism according to another embodiment of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 heating roller, 2 heater, 3 pressure roller, 4 temperature detecting means, 5 web supply mechanism, 10 web, 11
Web supply roller, 11a supply shaft, 12 press-contact means, 13 web take-up roller, 13a take-up shaft, 1
4 motors, 15 control units, 20 bulkheads, 25 cooling ducts.

Claims (4)

[Claims] A heating roller heated by a heater;
A fixing roller pair comprising: a pressure roller that presses against the heating roller; and a web supply mechanism that presses the web against the heating roller and sequentially supplies a new web surface to the heating roller. The web supply mechanism includes a web supply roller that supplies the web toward the heating roller, a pressing unit that presses the web surface against the heating roller, and a web winding roller that winds the web surface after the pressing with the heating roller is completed. And a drive mechanism for driving each web take-up roller, wherein the web supply roller is disposed at a position sufficiently spaced laterally from the heating roller. 2. The web supply mechanism according to claim 1, wherein the web supply roller is separated from the heating roller. 3. The web supply mechanism according to claim 1, wherein the web supply roller is disposed in the cooling duct. 4. The web supply mechanism of a thermal fixing device according to claim 1, wherein the core of the web supply roller has a hollow shape such as a pipe, and cool air flows inside the core.