JPH0816019A - Fixing apparatus - Google Patents

Abstract

PURPOSE:To extend the life of a cleaning roller in a fixing apparatus and make cleaning work of a roller for fixing easy. CONSTITUTION:A fixing apparatus is provided with a pair of rollers for fixing, a cleaning roller, a cleaning mode instructing means, and a cleaning roller touching and parting means. The cleaning roller 23 is journalled to one end of an arm 24 and energized toward the direction parting from an upper fixing roller 21 by an energizing force of a spring 27. A control part 28 drives a solenoide 26 following the operation of a cleaning mode key 29 and controls the cleaning roller 23 in the direction to press the outer circumference of the fixing roller 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device, and more particularly to a fixing device for fixing a toner image on a sheet.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a fixing device for fixing a toner image transferred on a sheet is arranged downstream of an image forming section. This fixing device includes a pair of fixing rollers that conveys a sheet while heating and pressing the sheet, and a cleaning roller that contacts at least one outer peripheral surface of the fixing roller.

In such a fixing device, the sheet is heated and pressed by a pair of fixing rollers, and the toner image on the surface is fixed. The fixing-processed sheet is conveyed to the discharge roller side by the fixing roller. At this time, the surface of the fixing roller is cleaned by the rotating cleaning roller.

[0004]

In such a fixing device, as a cleaning roller, a roller which is filled with an offset preventing liquid such as silicon oil and whose outer peripheral surface is made of felt is generally used. When the fixing operation of the copying machine is performed, the cleaning roller is rotated along with the rotation of the fixing roller, and the offset preventing liquid inside permeates the felt portion. As a result, the offset prevention liquid is applied to the outer peripheral surface of the fixing roller, and the fixing roller is cleaned.

However, the cleaning roller is always in contact with the outer peripheral surface of the fixing roller, and the offset prevention liquid is applied to the surface of the fixing roller each time the fixing operation is performed.
Therefore, the consumption amount of the offset prevention liquid of the cleaning roller increases, and the number of times of maintenance for filling the offset prevention liquid increases. Further, since the cleaning roller is constantly in contact with the fixing roller, there is a problem that the life of the cleaning roller is shortened due to abrasion.

In order to solve such a problem, a fixing device as disclosed in Japanese Unexamined Patent Publication No. 5-88579 has been proposed. This fixing device is provided with a roller contacting / separating unit that operates so that the cleaning roller is pressed against the fixing roller only during the printing operation. Therefore, in this fixing device, the cleaning roller is separated from the fixing roller when the printing operation is not performed, so that the consumption amount of the offset prevention liquid is reduced and the abrasion of the cleaning roller is reduced.

However, offset often occurs in a copying machine when double-sided copying is performed. Also,
Even when there are many solid black portions in the photo mode and the like, the fixing roller becomes heavily soiled. On the other hand, in the normal copy mode, the phenomenon in which toner adheres to the fixing roller and causes offset does not occur very often. Therefore,
When the fixing device as described above is used, the offset prevention liquid is applied to the fixing roller even in the normal copy mode, and the offset prevention liquid is consumed more than necessary. For this reason, the problem that the number of times of maintenance for filling the offset prevention liquid increases is still included. Further, there is still a problem that the life of the cleaning roller is shortened due to abrasion. Further, when the toner once adheres to the fixing roller, the cleaning of the fixing roller is incomplete only by applying the offset prevention liquid during the printing operation, and the offset occurs continuously. In this case, it is necessary to clean the fixing roller by a service person, which involves complicated work.

An object of the present invention is to extend the life of the cleaning roller and facilitate the cleaning of the fixing roller by a user or a service person.

[0009]

A fixing device according to the present invention comprises a fixing roller, a cleaning roller, a cleaning mode instructing means, and a cleaning roller contacting / separating means. The fixing roller passes the paper while sandwiching the paper.
The cleaning roller can contact at least one outer peripheral surface of the fixing roller. The cleaning mode instructing unit instructs the cleaning operation of the fixing roller by the cleaning roller. The cleaning roller contacting / separating means is
According to the instruction of the cleaning mode instruction means, the cleaning roller is brought into contact with at least one outer peripheral surface of the fixing roller.

Here, the cleaning roller contact / separation means is
The cleaning roller may be in contact with the outer peripheral surface of the fixing roller for a predetermined time when instructed by the cleaning mode instructing means.

[0011]

In the fixing device according to the present invention, the toner image on the paper is heat-fixed by sandwiching the paper between the fixing rollers and passing the paper. When the cleaning operation is instructed by the cleaning mode instructing means, the cleaning roller contacting / separating means drives the cleaning roller to bring it into contact with at least one outer peripheral surface of the fixing roller. As a result, the outer peripheral surface of the fixing roller is uniformly cleaned by the cleaning roller. Since this cleaning operation is performed only when instructed by the cleaning mode instructing means, it is possible to extend the life of the cleaning roller. When the toner adheres to the fixing roller and the offset is frequently generated, the user or the service man can operate the cleaning mode instructing means to easily clean the fixing device.

When the cleaning roller is in contact with the outer peripheral surface of the fixing roller for a predetermined time when the cleaning mode instructing means gives an instruction, the toner adhered to the outer peripheral surface of the fixing roller is kept for the predetermined time. If you set the time that is considered to be removed, it is possible to clean the fixing roller, and if the dirt from the toner is not removed by one cleaning, operate the cleaning mode instruction means multiple times. This makes it possible to clean the fixing roller.

[0013]

FIG. 1 shows a copying machine to which an embodiment of the present invention is applied. In the figure, an original placing table 2 is fixed to the upper surface of a copying machine main body 1. A document holder 3 is mounted on the document table 2 so as to be openable and closable. On the other hand, a bypass tray 4 and paper feed cassettes 5 and 6 are detachably mounted on the right side of the copying machine main body 1 in the figure, and a discharge tray 7 for discharging copied sheets on the left side. Is installed. Inside the copying machine main body 1, an optical system 8 for reading a document is provided above the main body. The optical system 8 is composed of a light source, a mirror and the like. Also,
A photoconductor drum 9 on the surface of which an electrostatic latent image is formed is arranged at substantially the center of the main body device 1.

Around the photosensitive drum 9, a main charging device 10 for charging the photosensitive drum 9 to a predetermined electric charge, a developing device 11 for developing an electrostatic latent image on the photosensitive drum 9, and a toner image on a sheet are transferred. A transfer device 12, a paper separating device 13 for separating the paper from the photosensitive drum 9, and a cleaning device 1 for removing residual toner and the like on the photosensitive drum 9.
4 are provided.

Paper feed rollers 16a and 16b are provided above the leading ends of the paper feed cassettes 5 and 6, respectively. Roller 16
Between the a and 16b and the image forming unit, a paper feeding device 17 for supplying paper to the image forming unit is provided. A transport device 18 is provided on the downstream side of the image forming unit. A fixing device 20 for fixing the transferred image on the conveyed sheet is provided between the conveying device 18 and the discharge roller 19.

As shown in FIG. 2, the fixing device 20 includes a pair of upper fixing roller 21 and lower fixing roller 22 that allow a sheet to pass therethrough, and a fixing roller driving portion (not shown) that rotationally drives the fixing roller. No.) and the cleaning roller 23. As the fixing roller, for example, the upper fixing roller 21 may be a heating roller having a heater therein, and the lower fixing roller 22 may be a pressure roller biased toward the upper fixing roller 21 side.

The cleaning roller 23 has a structure as shown in FIG. 3, for example. Many through holes 30, 30
An oil holding tank 32 is provided on the outer circumference of a metal tube body 31 having the above, and a felt layer 33 is further provided on the outer circumference thereof. The hollow inside of the tubular body 31 is filled with an offset prevention liquid such as silicon oil. The cleaning roller 23 is rotatably supported by the tip of an arm 24 that swings around a fulcrum 25. The other end of the arm 24 is connected to a solenoid 26 and a spring 27 whose one end is fixed to the apparatus main body side. The spring 27 biases the arm 24 in a direction in which the cleaning roller 23 is separated from the outer peripheral surface of the upper fixing roller 1. Solenoid 26 is control unit 28
The cleaning roller 23 is urged in a direction in which the cleaning roller 23 comes into pressure contact with the upper fixing roller 21 by the control. A cleaning mode key 29 provided on an operation panel (not shown) of the copying machine body 1 is connected to the control unit 28. When the cleaning mode key 29 is operated, the control unit 28 drives the solenoid 26 to control the cleaning roller 23 so as to be in pressure contact with the outer peripheral surface of the upper fixing roller 21.

In a normal state, the cleaning roller 23 is kept separated from the upper fixing roller 21 by the urging force of the spring 27. When the cleaning mode key 29 is operated, the controller 28 drives the solenoid 26 to bring the cleaning roller 23 into pressure contact with the outer peripheral surface of the upper fixing roller 21. As a result, the cleaning roller 23 rotates along with the rotation of the fixing roller, and the offset prevention liquid filled in the tubular body 31 permeates the surface of the felt layer 33 through the through hole 30. The offset prevention liquid that has permeated the surface of the felt layer 33 is applied to the outer peripheral surface of the upper fixing roller 21 to remove the toner attached to the surface of the upper fixing roller 21. In the control unit 28, when the cleaning mode key 29 is operated, the solenoid 26 is operated for a certain period of time.
Is driven to clean the upper fixing roller 21.

In the present invention, the cleaning roller 23 is pressed against the outer peripheral surface of the upper fixing roller 21 for a certain period of time only when the cleaning mode key 29 is operated to clean the fixing roller.
It is possible to reduce the consumption of the offset prevention liquid filled in the inside, and it is possible to reduce the abrasion on the surface of the cleaning roller 23. Therefore, the cleaning roller 2
It is possible to prolong the life of No. 3. [Other Embodiments] (a) It is also possible to adopt a configuration in which the cleaning roller 23 is brought into pressure contact with the outer peripheral surface of the upper fixing roller 21 during copying in the double-sided copy mode and the photo mode.

[0020]

According to the present invention, since the cleaning roller is brought into contact with at least one outer peripheral surface of the fixing roller by the cleaning roller contacting / separating means only when the cleaning operation is instructed by the cleaning mode instructing means, the length of the cleaning roller is long. It is possible to extend the life. Further, when the offset occurs in the fixing device, the cleaning operation can be instructed by the cleaning mode instructing means, so that the fixing roller can be cleaned, which simplifies the work.

Further, when the cleaning roller is in contact with the outer peripheral surface of the fixing roller for a predetermined time when the cleaning mode instructing means gives an instruction, the fixing roller is cleaned for a fixed time for cleaning. Since the roller is brought into contact with the outer peripheral surface of the fixing roller, the life of the cleaning roller can be maintained for a long time and the cleaning operation of the fixing roller can be simplified.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional configuration diagram of a copying machine to which an embodiment of the present invention is applied.

FIG. 2 is a schematic configuration diagram showing a fixing device of the copying machine.

FIG. 3 is a partial cross-sectional perspective view showing the configuration of a cleaning roller.

[Explanation of symbols]

 20 Fixing Device 21 Fixing Upper Roller 22 Fixing Lower Roller 23 Cleaning Roller 28 Control Section 29 Cleaning Mode Key

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masayuki Nakayasu 1-2-2 Tamatsukuri, Chuo-ku, Osaka Mita Engineering Co., Ltd.

Claims (2)

[Claims] 1. A fixing device for fixing a toner image to a sheet, the pair of fixing rollers passing the sheet between them, and cleaning capable of contacting at least one outer peripheral surface of the fixing roller. A roller; a cleaning mode instruction means for instructing a cleaning operation of the fixing roller by the cleaning roller; and a cleaning operation for bringing the cleaning roller into contact with at least one outer peripheral surface of the fixing roller according to an instruction of the cleaning mode instruction means. And a roller contacting / separating unit. 2. The fixing device according to claim 1, wherein the cleaning roller contacting / separating means brings the cleaning roller into contact with the outer peripheral surface of the fixing roller for a predetermined time when instructed by the cleaning mode instructing means. .