JP2011242682A - Image heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image heating device capable of efficiently cleaning and removing deposits such as a toner adhering to each surface of a heating rotor and an external heating rotor.SOLUTION: A supply roller for supplying a web as a cleaning member which abuts on a heating rotor and an external heating rotor, drive-connects to a contact roller which abuts on the heating rotor via the web.

Description

  The present invention relates to an image heating apparatus used in an image forming apparatus such as a copying machine or a printer. Examples of the image heating device include a fixing device that heats and fixes an unfixed image formed on a recording material as a fixed image, and a glossiness increasing device that increases the glossiness of an image by heating the image fixed on the recording material. Can be mentioned.

  As a fixing device used in an image forming apparatus such as a copying machine or a printer using an electrophotographic system, there is one that enables high-speed continuous fixing within a limited rated power consumption range of the image forming apparatus. . Specifically, there is known a type including an external heating roller that rotatably contacts a heat fixing roller having a built-in heat source and heats the roller surface from the outside. This fixing device heats and maintains the surface of the heat fixing roller quickly and stably at a temperature necessary for heat fixing. That is, an unfixed (toner) image on a recording sheet sent one after another during high-speed continuous fixing is heat-fixed satisfactorily at a stable heating temperature by the heat-fixing roller.

  In the fixing device including such an external heating roller, a cleaning device is generally provided for cleaning deposits such as toner and paper dust attached to the surface of the heat fixing roller. However, there are deposits such as toner that cannot be removed by the cleaning device. The deposits on the heat fixing roller that are not removed are transferred and adhered to the external heating roller, and gradually accumulate on the surface of the external heating roller as the number of recording sheets to be fixed increases. When deposits such as toner accumulate on the surface of the external heating roller, the deposits are interposed between the external heating roller and the heat fixing roller. As a result, heat transfer loss from the external heating roller to the heat fixing roller occurs, or toner accumulated in the external heating roller re-transfers to the heat fixing roller side and adheres to the recording sheet at the time of fixing. As a result, there is a problem that the image quality is deteriorated.

  On the other hand, in a fixing device including an external heating roller that heats the heat fixing roller from the outside, a fixing device including a web (cleaning member) that moves in contact with both surfaces of the heat fixing roller and the external heating roller. It has been proposed (Patent Document 1).

Japanese Patent Laid-Open No. 11-174889

  However, in this fixing device, as shown in FIG. 4, the external heating roller 4 is driven with respect to the rotation of the fixing roller 1, and therefore the fixing roller rotation direction A and the external heating roll rotation direction B are opposite to each other. . The web 6 as a cleaning member is wound around the web supply shaft 7 in advance, and moves in the web movement direction C by the web take-up shaft 8 via the web take-up gear 54. The web winding shaft 8 includes a reverse rotation prevention mechanism and does not move in the direction opposite to the web moving direction C. That is, the web 6 does not move in the fixing roller rotation direction A at the pressure contact portion between the fixing roller 1 and the fixing web roller 9, and the web does not sag.

  On the other hand, slack occurs between the pressure contact portion between the fixing roller 1 and the fixing web roller 9 and the pressure contact portion between the external heating roller 4 and the external heating web roller 50. This is because the external heating roller 4 is rotated via the external heating belt 5 by the rotation of the external heating roller 4 at the pressure contact portion between the external heating roller 4 and the external heating web roller 50, and the web 6 is fed from the web supply shaft 7. It is caused by being sent out. As a result, the web 6 enters the contact portion between the external heating roller 4 and the fixing roller 1, which causes a cleaning failure, a fixing failure, or a fixing device failure.

  Here, at the contact portion between the external heating roller 4 and the external heating web roller 50, it is conceivable that the load of the web supply roller 70 is made heavier than the force with which the web 6 is sent out by a brake member or the like. However, when the load is too large, problems such as web breakage, winding failure, and winding drive damage occur.

  The present invention has been made in order to solve such problems of the prior art, and its purpose is to more efficiently clean deposits such as toner adhering to the surfaces of the heating rotator and the external heating rotator. An object of the present invention is to provide an image heating apparatus that can be removed.

  In order to achieve the above object, a typical configuration of an image heating apparatus according to the present invention includes a heating rotator and a pressure rotator that is in pressure contact with the heating rotator, and the heating rotator and the heating rotation. In an image heating apparatus that heats an image on a recording material by sandwiching and conveying the recording material at a nip formed by the body, an external heating rotator for heating the outside of the heating rotator, and the heating rotation A cleaning device having a cleaning member that contacts both the body and the external heating rotator, wherein the cleaning device includes a supply roller for the cleaning member, a take-up roller for the cleaning member, and the heating rotator. A heating rotator contact roller that is in contact with the cleaning member via the cleaning member, and drive connecting means for drivingly connecting the supply roller and the heating rotator contact roller.

    ADVANTAGE OF THE INVENTION According to this invention, deposits, such as a toner adhering to each surface of a heating rotary body and an external heating rotary body, can be cleaned and removed more efficiently.

1 is a schematic configuration diagram of a fixing device according to an embodiment of the present invention. 1 is a schematic configuration diagram of an image forming apparatus using a fixing device according to an embodiment of the present invention. FIG. 6 is a schematic diagram of a cleaning operation of the fixing device in the embodiment of the present invention. It is a schematic sectional view of a conventional fixing device.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  In all the drawings of the following embodiments, the same or corresponding parts are denoted by the same reference numerals.

<< First Embodiment >>
(Image forming device)
FIG. 2 is a diagram illustrating a schematic configuration of the electrophotographic image forming apparatus. 1 is a fixing roller, 2 is a pressure roller, 10 is an image forming unit, 11 is a photosensitive drum, 12 is a developing device, 13 is an intermediate transfer belt, 14 is a secondary transfer unit, 15 is a laser scanning laser scanner unit, and 17 is A primary transfer portion. Also, 20 is an image reading unit, 21 is a document feeding table, 22 is a platen roller, 23 is a document discharge table, 24 is an image sensor, 25 is a first scanning unit, 26 is a second scanning unit, and 27 is a document placing table. It is. Reference numeral 18 denotes a registration roller, 30 denotes a paper feeding unit, 31 denotes a cassette, and 32 denotes a paper feeding unit. 41 and 42 are conveyance paths, FP1, FP2 and FP3 are flappers for switching the conveyance paths, and 43, 45, 46 and 47 are conveyance rollers, and the conveyance paths are two-sided copies for the first and second sheets P1 and P2. In this case, the paper discharge reversing path is included.

  Hereinafter, main operations of the image forming apparatus 100 will be described. When an image reading signal is output from the control device provided in the apparatus main body 102 to the image reading unit 20, the document placed on the document placing table 27 is irradiated with light from the light source of the first scanning unit 25. The light reflected from the document is input to the image sensor 24 via the first scanning unit 25 and the second scanning unit 26 in which the ratio of the distance moved in the horizontal direction is 2 to 1, and is converted into an electrical signal as image information. Is done. A laser beam corresponding to the electrical signal is irradiated onto the photosensitive drum 11 by the laser scanner unit 15. At this time, the drum 11 is charged in advance, and an electrostatic latent image is formed by irradiation with light. Next, the electrostatic latent image is developed by the developing device 12 to form a toner image on the drum 11. The toner image on the drum 11 is transferred to the intermediate transfer belt 13 by the primary transfer unit 17 by the rotation of the drum 11.

  On the other hand, when a paper feed signal is output from the control device provided in the apparatus main body 102 to the paper feed unit 30, the recording material P is supplied from the cassette 31. Then, the fed recording material P is sent to a transfer unit constituted by the intermediate transfer belt 11 and the secondary transfer unit 14 at a predetermined timing. The sheet sent to the transfer unit is conveyed to the fixing unit FX after the toner image is transferred.

  Regarding the fixing unit FX, a sheet as a recording material is nipped and conveyed at a nip portion formed by a fixing roller 1 as a heating rotator and a pressure roller 2 as a pressure rotator, and an image on the recording material is heated. Is done. That is, the unfixed transfer image is stably fixed on the recording material sheet P by being heated and pressed by the fixing roller 1 and the pressure roller 2 of the fixing unit FX. The sheet on which the image is fixed is discharged from the apparatus main body 100 by the discharge roller 43 and transferred to the processing apparatus 101.

  1 and 3 are diagrams showing a schematic configuration and operation of a cross section of a fixing device as an image heating device including a fixing roller, an external heating unit, and a cleaning device according to an embodiment of the present invention. In FIG. 1, 4 is an external heating roller with a built-in heating source, and 5 is an external heating belt for transferring the heat of the surface of the external heating roller 4 to the surface of the fixing roller 1. The external heating belt 5 is configured as an endless belt that is stretched and driven by a plurality of external heating rollers. The external heating belt 5 is used to efficiently transfer the heat of the external heating roller by expanding the contact area with the fixing roller.

  Reference numeral 110 denotes a cleaning device that cleans both the fixing roller 1 and the external heating rotating body 60 (the external heating roller 4 rotated by the external heating belt 5) by a long web 6 serving as a cleaning member. The cleaning device 110 is disposed on the upstream side in the rotation direction of the fixing roller 1 from the contact portion between the fixing roller 1 and the external heating roller 4. The fixing roller 1 contacts the external heating rotating body 60 after contacting the web 6 as a cleaning member. Thereby, since the surface of the fixing roller 1 is first cleaned by the web 6 as a cleaning member, the amount of deposits transferred and adhered from the fixing roller 1 to the external heating rotator 60 is reduced. Further, even if there is a deposit that is not removed by the web 6 and it is transferred and adhered to the external heating rotary body 60, the deposit is removed by the web 6.

  In the cleaning device 110, reference numeral 7 denotes a web supply shaft on which the web 6 is wound in advance and is rotatably arranged in the direction in which the web 6 is fed out. Reference numeral 8 denotes a web winding shaft in which the tip end portion of the web 6 is fixed and rotatably disposed in the direction of winding the web. A supply roller 70 and a take-up roller 80 are attached to the web supply shaft 7 and the web take-up shaft 8, respectively, so as to be rotatable. Reference numeral 9 denotes a fixing web roller as a heating rotator contact roller rotatably disposed at a position where the web 6 is pressed against the surface upstream of the external heating belt 5 in the rotation direction of the fixing roller 1. Reference numeral 50 denotes an external heating web roller rotatably disposed at a position where the web 6 is pressed against the outer peripheral surface of the external heating belt 5 between the fixing web roller 9 and the web supply roller 7.

  The web 6 is formed of a non-woven fabric having heat resistance, and is set so that the web winding shaft 8 is gradually wound by driving the web driving gear 54 by a web driving motor (not shown). When the recording material sheet P passes through the fixing portion, the web is fed by a certain amount (for example, 0.2 mm for A4 / sheet), and thus the web is repeatedly moved and stopped while the fixing roller 1 is rotating. Further, both the fixing web roller 9 and the external heating web roller 50 are made of an elastic material such as a sponge except for the shaft core, and are supported so as to press the web 6 with a predetermined pressing force. Yes.

  Reference numeral 51 denotes a drive connecting belt that connects the driving of the web supply roller 70 and the fixing web roller 9 via the one-way pulley 52 and the pulley 53. When the web 6 is pulled out by this connecting belt, the rotational drive of the web supply roller 70 is transmitted to the fixing web roller 9, and the web 6 is wound around the winding shaft 8 through the rotation of the fixing web roller 9. No slack occurs.

  According to such a cleaning device, the cleaning web 6 is pressed against the surfaces of both the fixing roller 1 and the external heating belt 5, whereby each surface of the rollers 1 and 5 can be cleaned. More specifically, deposits such as toner adhering to the surface of the fixing roller 1 that has passed through the fixing portion (nip portion) in pressure contact with the pressure roll 2 are applied to the surface of the fixing roller 1 on the fixing web roller 9. Then, the cleaning web 6 is removed by the pressure contact. Even if the deposits that have not been removed by the web 6 remain attached to the external heating belt 5 and transfer and adhere to the external heating belt 5 that is in contact with the fixing roller 1 on the downstream side of the fixing web roller 9, cleaning is performed. It will be removed by the web 6.

  By the way, when the fixing roller 1 rotates, a web feed force T is generated at the external heating cleaning contact portion S of the external heating belt 5 and the external heating web roller 50 that are driven to rotate by the fixing roller 1 (for example, 1 kg). The feed force T is transmitted to the web supply shaft 7 by the web 6 and becomes the web supply shaft rotational force U. Since the web supply shaft 7 and the fixing web roller 9 are connected by the drive connecting belt 51, the web supply rotational force U is transmitted to the fixing web roller 9 and becomes the fixing web roller rotational force W.

On the other hand, the fixing web roller 9 is strongly pressed to increase the width of the contact portion R for cleaning the fixing roller 1. The adhering matter adhering to the surface layer of the fixing roller 1 is first cleaned by the fixing cleaning contact portion R, and then the adhering matter that has passed through is cleaned by the external heating cleaning contact portion S. Because of this order, the cleaning amount of the deposit is set so that the fixing cleaning contact portion R is larger than the external heating cleaning contact portion S. That is, in order to increase the cleaning ability, the external heating cleaning contact portion R is set to have a larger pressure than the fixing cleaning contact portion S. As described above, the force (for example, 2 kg) generated by the rotation of the fixing roller 1 with respect to the fixing web roller 9 is derived from the force (for example, 1 kg) generated by the rotation of the external heating roller 4 on the left side in FIG. It is a big relationship.

  As the fixing roller 1 rotates, the fixing web roller 9 acts in the fixing rotation direction A, and is opposite to the fixing web roller rotational force W, that is, the direction in which the force T generated at the external heating cleaning contact portion S acts. Thereby, the web 6 is not sent out by the strong force such as the web feed force T at the contact portion S.

  During and after the recording material sheet P passes through the fixing portion, the web 6 is fed in a certain amount C direction by the web winding shaft 54 being rotated by the web winding gear 54. The fixing web roller 9 is rotated by the frictional force with the web 6. This rotation causes the web roller pulley 53 to rotate, and the drive transmission belt 51 causes the web supply shaft one-way pulley 52 to rotate. The web supply shaft one-way pulley 52 is set to be free (idle rotation) in the clockwise direction and locked in the counterclockwise direction with respect to the web supply shaft 7 in the drawing.

  Further, the rotation amount of the web supply shaft one-way pulley 52 by the web drive transmission belt 51 is set larger than the rotation amount of the web supply shaft 7 when the web 6 is fed out. This is done by making the diameter of the web supply shaft larger than the diameter of the fixing web roller 9 or by changing the number of teeth of the web roller pulley 53 and the web supply shaft one-way pulley 52. As a result, the web supply shaft one-way pulley 52 rotates freely so that the web 6 can be reliably wound without an increase in load.

  Therefore, in the fixing unit FX (FIG. 2) of the present embodiment, both the surface of the fixing roller 1 and the surface of the external heating belt 5 are always kept in a clean state free from dirt due to adhered matter. That is, deposits such as toner adhering to the surfaces of the heating rotator and the external heating rotator can be cleaned and removed more efficiently and reliably and for a relatively long period of time.

<< different embodiments >>
In the embodiment described above, the external heating web roller 50 is used, and the external heating web roller 50 is brought into contact with the external heating rotating body 60 via the web 6 as a cleaning member. However, the arrangement relationship of the supply roller 70 with respect to the fixing web roller 9 can be adjusted, and the external heating web roller 50 can be omitted. That is, if the web 6 stretched between the fixing web roller 9 and the supply roller 70 is disposed at a position corresponding to the tangent to the left external heating roller 4 in FIG. It is not necessary to use the external heating web roller 50.

  Further, in this embodiment, the cleaning device 110 is disposed on the upstream side in the rotation direction of the fixing roller 1 from the contact portion between the fixing roller 1 and the external heating roller 4, but may be disposed on the downstream side in the rotation direction. .

1 .. Fixing roller 2.. Pressure roller 4, 5 .. External heating roller 5.. External heating belt 6, Web 9.. Fixing web roller 50 50 External heating web roller 51 ..Drive connecting belt, 70 ..Supply roller, 80 ..Winding roller, 110 ..Cleaning device

Claims (2)

A heating rotator and a pressure rotator that is in pressure contact with the heating rotator, and sandwiches and conveys the recording material at a nip formed by the heating rotator and the pressure rotator. In an image heating apparatus for heating an image,
An external heating rotator for heating the outside of the heating rotator;
A cleaning device comprising a cleaning member that contacts both the heating rotator and the external heating rotator,
The cleaning device includes:
A supply roller for the cleaning member;
A winding roller of the cleaning member;
A heating rotator contact roller that contacts the heating rotator via the cleaning member;
Drive coupling means for drivingly coupling the supply roller and the heating rotator contact roller;
An image heating apparatus comprising:   The image heating apparatus according to claim 1, wherein the external heating rotator includes a plurality of external heating rollers and an endless belt that is stretched and driven by the plurality of external heating rollers.