JP3971531B2 - Web supply mechanism of thermal fixing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in an image forming apparatus such as an electrophotographic copying machine, a printer, a plain paper facsimile machine, and the like, and more particularly to an improved web supply apparatus used in a heat fixing apparatus used in the image forming apparatus.
[0002]
[Prior art]
In an electrophotographic image forming apparatus, a thermal fixing device is used as a means for fixing a toner image transferred onto a transfer sheet in an image forming unit by applying pressure while heating. This heat fixing device is composed of a heating roller having a heating means inside or on its outer surface, and a pressure roller in pressure contact with the peripheral surface of the heating roller, and transfers the transfer paper carrying an unfixed toner image to both rollers. By passing through the nip portion, the toner image is pressed and fixed while being heated.
By the way, the most serious problem in the fixing device is the contamination of the heating roller with toner or the like, and the occurrence of an offset phenomenon in which the toner once fixed on the transfer paper is peeled off and fixed to the heating roller side.
In order to prevent the occurrence of such a problem, a web apparatus (web supply mechanism) for cleaning the heating roller and applying an anti-offset liquid is used in the heat fixing apparatus. The web device has one end of a web, ie, a material that absorbs and holds the offset prevention liquid, is fixed to the take-up roller, and the other end is wound around the web supply roller and sent out from the supply roller. The web is wound up by a winding roller. The web drawn between the two rollers is pressed against the heating roller by pressing means that presses against the circumferential surface of the heating roller, so that the dirt on the heating roller is wiped off, and at the same time, silicon oil or the like impregnated in the web in advance Apply an anti-offset solution. The take-up roller is rotated in the take-up direction by a driving device such as a motor to take up the web surface after the press contact with the heating roller, and the new web surface is always pressed against the surface of the heating roller. It will not decline.
[0003]
By the way, since the surface of the heating roller is controlled at 150 to 210 ° C., the temperature around the heating roller is also high. It is known that silicone oil generally used as an anti-offset liquid (release agent) for a heating roller has an extremely reduced kinematic viscosity when it exceeds 80 to 100 ° C. In general, the web supply roller (web device) is often disposed directly above the heating roller (for example, Japanese Patent Application Laid-Open No. 58-199371 “Cleaning Web”, Japanese Patent Application Laid-Open No. 1-223783 “Fixing Rotating Body”). Peripheral surface cleaning device)), because the anti-offset liquid evenly impregnated in the web is placed in a high-temperature atmosphere, the kinematic viscosity decreases, so the anti-offset liquid easily moves down in the supply roller. Accumulate. For this reason, before the web fed from the supply roller comes into contact with the heating roller at the pressure contact position, the web is directly applied to the surface of the heating roller from the web supply roller or from the web stretched between the web supply roller and the pressure contact means. A large amount of the anti-offset liquid is likely to drip, and as a result, a situation has occurred where oil stains are generated on the transfer paper.
As conventional examples for solving such problems, for example, (1) a method for preventing the dripping by increasing the kinematic viscosity of the offset preventing liquid, and (2) a method for enclosing the offset preventing liquid in a microcapsule (special feature) Japanese Laid-Open Patent Publication No. 4-308880 ("Facilizing surface cleaning device for fixing member") has been proposed. However, (1) has the side effect of reducing the amount of application to the heating roller, and (2) has a problem that the cost of the solution increases extremely because the construction of the offset preventing liquid is complicated.
[0004]
[Problems to be solved by the invention]
The present invention has been made in view of the above, and in the first aspect of the present invention, the web supply roller is cooled by directly applying cold air to the web supply roller, and the core metal of the web supply roller is formed into a pipe-like hollow shape. By flowing cool air inside, the core metal temperature of the supply roller is lowered to prevent the temperature increase of the supply roller, and the web supply roller is further away from the heating roller to lower the ambient temperature around the web supply roller. As a result, transfer paper oil is produced by dripping a large amount of the anti-offset liquid onto the heating roller from the web wound around the web supply roller, while preventing an extreme decrease in the kinematic viscosity of the anti-offset liquid and suppressing side effects and cost increases. The purpose is to prevent contamination.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 is directed to a fixing roller pair comprising a heating roller heated by a heater, a pressure roller pressed against the heating roller, and a web pressed against the heating roller; And a web supply mechanism that 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, and the web surface to the heating roller. and urging means for pressing the web take-up roller for taking up the web surface has been completed the pressure contact with the heating roller, and a drive mechanism for driving the U E Bed winding roller, a provided, the web supply roller in the cooling duct The web feed roller cored bar is formed into a pipe-like hollow shape, and cold air is allowed to flow inside the cored bar. Further, the web feed roller is laterally moved from the heating roller. Characterized in that it is arranged to heat a position not dripping release agent impregnated in the web by from the heating roller.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
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. This heat fixing device includes a heating roller 1 provided with a heater 2 inside, and a pressure contacted with a peripheral surface of the heating roller 1. A fixing roller pair including a pressure roller 3, temperature detection means 4 such as a thermistor, and a web supply mechanism 5 are provided.
A pressure roller 3 having an elastic surface is pressed against the heating roller 1 heated by the heater 2, and the transfer paper P having an unfixed image passes through the nip portion of the fixing roller pair while being heated. Pressure is applied and fixing is performed.
The web supply mechanism 5 winds a web supply roller 11 that supplies the web 10 toward the heating roller 1, a press contact means 12 that presses the web surface against the heating roller 1, and a web surface that has finished press contact with the heating roller 1. A web winding roller 13 is provided, 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 drive mechanism. A web supply mechanism 5 is disposed for the purpose of applying oil for preventing offset to the surface of the heating roller 1 and cleaning the surface.
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.
One end of the web 10 is fixed to the winding shaft 13 a and the other end is wound around the supply shaft 11 a, and the web 10 drawn between the rollers 11 and 13 is pressed against the heating roller 1 by the pressure contact means 12. Let
The pressing means 12 includes a pressing roller 12a that presses the web 10 against the heating roller, and an elastic member 12b that presses the pressing roller 12a against the heating roller. When the web 10 is pressed against the surface of the rotating heating roller, the dirt on the heating roller 1 is wiped off. Further, oil is applied by impregnating the web 10 with an anti-offset liquid such as silicon oil.
Thereafter, the web take-up roller 13 is rotated by a motor 14 or the like, and the web 10 wound around the supply shaft 11a is gradually taken up. Setting values such as a winding amount and a winding interval are changed according to fixing conditions, transfer paper, environment, images, and the like.
In FIG. 1, the web supply roller that has been disposed at a position directly above the heating roller 1 is disposed laterally from the heating roller 1, so that the oil impregnated in the web by the heat from the heating roller is heated by the heating roller. It is possible to prevent the situation of dropping on the top.
[0007]
Next, FIG. 2 is a block diagram of another embodiment of the present invention. The same parts as those in FIG. The characteristic configuration of this embodiment is that the web supply roller 11 is disposed at a position sufficiently away from the heating roller 1, in other words, at a position where the offset preventing liquid impregnated by the web is not adversely affected by heat. It is in the point.
According to this, a decrease in the kinematic viscosity of the offset preventing liquid impregnated in the web 10 of the web supply roller 11 is not observed, and a large amount of the offset preventing liquid is dripped onto the surface of the heating roller 1 and the transfer paper P. Absent.
Next, FIG. 3 shows another embodiment of the present invention. In this embodiment, the arrangement position of the web supply roller 11 is not greatly separated from the heating roller 1 as in the case of FIG. In this embodiment, the web supply roller 11 is surrounded by a partition wall (heat resistant resin, heat insulating material, etc.) 20 and is isolated from the heating roller 1 as shown in the figure. A large amount of the anti-offset liquid does not drip (even if close to each other).
[0008]
Next, FIG. 4 shows another embodiment of the present invention. In this embodiment as well, the web supply roller is not greatly separated from the heating roller 1. Instead, in this embodiment, the web supply roller 11 is disposed in the cooling duct 25, and cooling air is blown into the cooling duct 25 from a fan or the like (not shown). For this reason, cold air is directly applied to the supply roller 11 by a fan or the like, and the supply roller 11 can be further cooled without being sufficiently separated from the heating roller 1 (even if 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. In this embodiment as well, the web supply roller is not greatly separated from the heating roller 1. Instead, in this embodiment, the supply shaft (core metal) 11a is formed in a hollow shape such as a pipe, and the supply roller 11 is cooled by flowing cold air through a fan or the like not shown in the drawing. . For this reason, similarly, a large amount of dripping of the offset preventing liquid can be prevented.
Further, even if the supply shaft 11a is a heat pipe and a fin is attached to the end portion to cool the fin, the heat pipe quickly transfers the heat of the supply roller to the fin, so that the same effect can be obtained. .
The configuration of the embodiment shown in FIG. 5 may be combined with the embodiment of FIG. 2, FIG. 3, or FIG. Further, all the above embodiments can be used in combination with all other embodiments.
[0009]
【The invention's effect】
As described above, according to the first aspect of the present invention, the web supply roller is moved away from the heating roller to lower the ambient temperature around the web supply roller, thereby preventing an extreme decrease in the kinematic viscosity of the offset preventing liquid and causing side effects. While suppressing the occurrence and cost increase, it is possible to prevent the transfer paper from being contaminated with oil due to a large amount of the anti-offset liquid dripping from the web wound around the web supply roller onto the heating roller. That is, the web supply roller is moved away from the heating roller, and the ambient temperature in which the web supply roller is placed can be lowered, so that the decrease in the kinematic viscosity of the offset prevention liquid impregnated in the web supply roller is not seen, and In addition, oil stains of the transfer paper due to a large amount of dripping on the transfer paper and the entrance guide plate are not generated. Further, the web supply roller can be further cooled by disposing the supply roller in the cooling duct and directly applying the cold air to the web supply roller. Moreover, the core metal of the web supply roller is formed in a pipe- like hollow shape, and the cool air is allowed to flow inside, thereby lowering the core metal temperature of the supply roller and preventing the temperature increase of the supply roller.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a thermal fixing apparatus including a web supply mechanism according to an embodiment of the present invention.
FIG. 2 is a schematic configuration diagram of a heat fixing apparatus including a web supply mechanism according to another embodiment of the present invention.
FIG. 3 is a schematic configuration diagram of a heat fixing apparatus including a web supply mechanism according to another embodiment of the present invention.
FIG. 4 is a schematic configuration diagram of a heat fixing apparatus including a web supply mechanism according to another embodiment of the present invention.
FIG. 5 is a schematic configuration diagram of a heat fixing apparatus including a web supply mechanism according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Heating roller, 2 Heater, 3 Pressure roller, 4 Temperature detection means, 5 Web supply mechanism, 10 Web, 11 Web supply roller, 11a Supply shaft, 12 Press contact means, 13 Web winding roller, 13a Winding shaft, 14 Motor, 15 control unit, 20 partition, 25 cooling duct.

Claims (1)

A fixing roller pair comprising a heating roller heated by a heater and a pressure roller in pressure contact with 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;
In the thermal fixing device with
The web supply mechanism includes a web supply roller that supplies the web toward the heating roller, a pressure contact unit that presses the web surface against the heating roller, and a web winding roller that winds the web surface after the pressure contact with the heating roller. comprising a driving mechanism for driving the U E Bed winding roller, a,
Placing the web supply roller in a cooling duct;
The core of the web supply roller has a pipe-like hollow shape, and cold air is flowed inside the core,
Further, the web supply roller of the heat fixing apparatus is characterized in that the web supply roller is disposed laterally from the heating roller at a position where the release agent impregnated in the web is not dripped by heat from the heating roller .

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