JPH0582585B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a fixing device for heating and fixing a toner image onto an image support sheet such as a recording paper in an image recording apparatus such as an electrophotographic copying machine, and particularly relates to The present invention relates to an improvement of a heat roller fixing device consisting of a set of a heat roller and a pressure roller.

[Conventional technology]

2. Description of the Related Art In image recording apparatuses such as electrophotographic copying machines, a heating roller type fixing device is often used to fix an unfixed image onto an image support sheet such as a recording paper. In this type of system, a recording paper supporting an unfixed toner image is conveyed between a heating roller equipped with a heat source and a pressure roller that is in pressure contact with the heating roller.
It heats and fixes the toner onto the recording paper.

Conventionally, in this type of fixing device, when the recording paper is pressed between a heating roller and a pressure roller and the toner image is fixed, a part of the toner is offset to the heating roller, and then the recording paper is recorded after one rotation of the heating roller. The paper or pressure roller is offset again, resulting in image stains or pressure roller stains.

For this reason, a cleaning means such as a heat-resistant pad, roller, or blade is pressed against the heating roller to remove the adhered toner.

[Problem that the invention seeks to solve]

However, such a fixing device in which the cleaning means is pressed against the heating roller has a complicated mechanism and structure, which inevitably leads to high costs. When toner accumulates on the means, the toner in contact with the heating roller melts, transfers to the heating roller, and eventually offsets to the pressure roller, resulting in dirt on the pressure roller or back surface. I found out that it would happen. This is a big problem in light of the recent trend toward maintenance-free printing, and service personnel have been forced to clean the rollers and replace the cleaning member after thousands to tens of thousands of copies have been made. Efforts have been made to reduce the burden on cleaning members, such as improving toner materials and precisely controlling the temperature of heating rollers. However, the stains on copied images have been improved to the point that they cannot be discerned, but as the number of copies is repeated, The offset toner, which is invisible to the naked eye, is directly released from the heating roller.
Alternatively, it is inevitable that the dirt will be indirectly transferred to the pressure roller through the cleaning member, resulting in dirt on the pressure roller that can be recognized as dirt.

Furthermore, if toner adheres to the back side of the recording paper before fixing due to toner stains inside the copying machine, it will be transferred to the pressure roller, causing stains on the recording paper itself and the back side of the recording paper after the next copy. If toner adhesion accumulates on the toner, the adhesion to the recording paper will increase, and paper feed jams may occur due to wrapping, etc.

[Means for solving problems]

The present invention effectively prevents toner stains on the heating roller and the pressure roller in a fixing device that performs fixing using a heating roller and a pressure roller.
The object of the present invention is to provide a heat roller fixing device that has a simple structure and is easy to maintain.

The fixing device of the present invention that achieves this object includes a rotatable heating roller, a pressure roller that rotates in pressure contact with the heating roller, and a pressure lever that supports the pressure roller and biases the pressure roller toward the heating roller. a fixing shaft that is fixed to the fixing device frame parallel to the rotation axis of the pressure roller and pivotally supports the pressure lever in a swingable manner; and a fixed shaft that is loosely fitted to the outer peripheral surface of the fixed shaft. a cleaning member having a cylindrical shape and having an inner wall surface in contact with the outer circumferential surface of the fixed shaft formed as a smooth surface with a small coefficient of friction; supported by being pinched by the surface,
Moreover, it is characterized in that it rotates as a result of the drive rotation of the pressure roller and slides on the outer periphery of the fixed shaft.

[Effect]

According to the present invention, the cleaning member is provided only on the side of the pressure roller that is in pressure contact with the heating roller, and the cleaning member is pressed between the pressure roller and the opposing surfaces of each outer periphery of the fixed shaft and rotates as a result. As a result, the toner adhering to the heating roller during the paper non-passing period is transferred to the pressure roller, the toner on the pressure roller is cleaned by the cleaning member that rotates as a result, and then the recording paper is transferred between the two rollers. By performing fixing throughout the image, it is possible to perform satisfactory fixing without staining the pressure roller.

〔Example〕

One embodiment of the invention is shown in FIGS. 1-4. FIG. 1 shows the main parts of a copying machine equipped with a fixing device 10 of the present invention. Recording paper fed in the direction of arrow P1 undergoes a toner image transfer in an image forming section 1, and is then recorded. The transferred side of the paper becomes the heating roller side and is conveyed to the fixing device 10 by the conveying device 2, and then is discharged from the machine in the direction of arrow P2 after undergoing a fixing process.

The fixing device 10 is provided with a fixing roller pair consisting of a heating roller 11 having a built-in heater lamp and a pressure roller 13 that is elastically pressed against the heating roller 11 and driven by its rotation.
The heating roller 11 has a gear G2 fixed thereto.
is rotated counterclockwise by being driven from a drive gear (not shown) on the copying machine main body side via a gear G1, and therefore the pressure roller 13 is rotated clockwise.

On the other hand, a cleaning member 14 is also provided against the pressure roller 13 and rotates counterclockwise as the cleaning member 14 comes into elastic pressure contact with the pressure roller 13 and rotates counterclockwise. On the other hand, the gear G1 meshes with the gear G5 of the paper discharge roller 15 via intermediate gears G2, G3, and G4. That is, the paper ejection roller 15 rotates clockwise in the same direction as the pressure roller 13 rotates, and serves to eject the recording paper that has been conveyed through the pressure roller pair to the outside of the machine. It's summery.

FIG. 2 shows a side view of the fixing device 10 according to the present invention, and FIG. 3 shows a cross-sectional view of the fixing device. FIG. 4 shows each of the aforementioned rollers 13, 11, 15 and 14.
FIG. 4 is a cross-sectional view obtained by developing a cross-sectional view perpendicular to each axis in a plane, and shows a cross-sectional view taken along the line AA in FIG. 3.

The heating roller 11 is formed into a cylindrical shape, and is made of a metal cylinder provided with a surface made of Teflon, and a heater lamp 12 is disposed inside thereof. The pressure roller 13 is composed of a metal roller 13B provided with a surface portion 13A made of silicone rubber, and its rotating shaft 13C.
Bearings 16 are provided at both ends. A pressure bonding lever 17 is fixed to the bearing 16 from below, and a bearing 18 is provided at one end of the pressure lever 17, and a coil spring 19 is provided between the bearing 16 and the chassis 20 at the other end. The pressure roller 13 is therefore connected to the spring 1
Due to the biasing force of 9, it is pressed against the heating roller 11 via the pressure lever 17.

Bearing 1 fixed to one end of this crimp lever 17
A fixed shaft 21 is fitted into and passes through the hole 8 . Both ends of the fixed shaft 21 are held on the chassis 20 by support members 22. Crimp lever 1
7 is rotatable around a fixed shaft 21. The pressure roller 13 described above is rotatably supported in the middle of the lever 17, and a portion near the other end is biased by a spring 19.

A cleaning member 1 is provided on the outer periphery of the fixed shaft 21.
4 is loosely fitted. This cleaning member 14 is
It has a hollow cylindrical shape, such as a paper tube made from pressboard paper. The outer wall surface 14A of this paper tube is a rough surface, and the inner wall surface 14B is a smooth surface with a small coefficient of friction. This inner wall surface 14B
is formed by, for example, applying an oil-impregnating process such as a grease treatment, applying a lubricant, or laminating a plastic film.

The cleaning member 14 has a pressure bonding lever 17
The fixed shaft 21, which is the rotation center of the
At this pressure contact position, the outer wall surface 14A of the cleaning member 14 and the elastic surface portion 13A of the pressure roller 13 form a predetermined nip.

Here, when the pressure roller 13 is rotated by the heating roller 11, the cleaning member 14
Due to the difference in the coefficient of friction between the inner and outer walls, the fixed shaft 21 and the inner wall surface 14B, which have smooth surfaces, slide and idle, and the outer wall surface 14A, which has a rough surface, rotates together with the pressure roller 13.

Note that a guide plate 24 for guiding the recording paper is disposed above the paper discharge roller 15 on the discharge side of both rollers 11 and 13.

The functions of the fixing device configured as above will be explained below.

When the copy button is pressed, the exposure section and paper feeding section are activated, and at the same time, both rollers 11 and 13 start rotating. After passing through the processes of exposure, charging, and development, the image is transferred to a recording paper (transfer paper) at a transfer section, and then the recording paper reaches a fixing section.

The recording paper carrying image toner on its surface is sandwiched between a heating roller 11 and a pressure roller 13 that are in pressure contact with each other in a fixing device.
is heated and melted and fixed on the recording paper. However, some of the toner, which cannot be visually discerned, adheres to the circumferential surface of the heating roller 11 and is transferred to the trailing edge of the recording paper and further to the pressure roller 13, where the toner on the pressure roller comes into contact with the cleaning member that rotates as a result of the pressure. 1
removed by 4. Note that offset toner stains on the trailing edge of the recording paper cannot be visually determined and pose no practical problem. Thus, the heating roller 11 is thoroughly cleaned indirectly through the pressure roller 13 by the cleaning member 14, and the pressure roller 13 is thoroughly cleaned directly. In addition, the heating roller 11 and the pressure roller 1
Toner, paper powder, etc. that have adhered to the pressure roller 3 and transferred to the pressure roller 13 after the rotation starts are sufficiently cleaned by the cleaning member 14, and then the recording paper passes between both rollers.

Here, the surface temperature of the pressure roller 13 is lower than that of the heating roller 11, and under normal use conditions,
Since the temperature is 60℃, the cleaning member (paper tube) 14
The upper toner will not be melted again and transferred to the pressure roller 13 again. This point is a big difference from the conventional case where the cleaning member is pressed against the heating roller.

Since the temperature of the pressure roller 13 is low, the cleaning member 14 can withstand a paper tube or the like, and since its surface is fibrous, there is no need to roughen the surface, and the molten toner penetrates deep into the fibers, removing the toner once transferred. It has the advantages of being difficult to re-transfer, the outer diameter does not change much due to the elastic deformation of the paper tube even when toner is piled up, the cost is low, and there is no pollution after disposal.

Next, when a jam occurs or during long-term storage, manually operate the operating lever 23 shown in FIG. 2 and rotate it in the direction of the arrow. is pressed and rotated clockwise around the fixed shaft 21, and the roller 23A engages with the notch recess 17A of the crimping lever 17, whereby it is locked. Along with this, the pressure roller 13 is separated from the heating roller 11.
Therefore, by operating the operating lever 23, the pressure is released and the pressure roller 13 and cleaning member 1 are removed.
4 can be made to rotate freely. In this state, it is possible to clean the pressure roller 13 with, for example, a solvent. In addition, since the rollers 11 and 13 are not in pressure contact during cleaning, the toner adhering to the pressure roller 13 does not dissolve and contaminate the heating roller 11 again, making complete maintenance possible. Moreover, the cleaning member 14 itself can be removed from the crimp lever 17 and easily replaced, making maintenance easy.

In order to bring the pressure roller 13 into contact with the heating roller 11 again, the operation lever 23 can be operated in the opposite direction to the above to release the lock.

Although the present invention has been illustrated above, the above-mentioned example can be further modified based on the technical idea of the present invention.

For example, instead of the paper tube of the cleaning member 14 described above, it is also possible to use other materials, such as plastic materials, web materials, or laminates of these materials formed into a cylindrical shape. In these materials as well, it is preferable that the inner wall has a smooth surface so that it can be easily rotated by the pressure roller 13.

Further, the structure of the pressing or pressing releasing mechanism for the heating roller 11 and the pressure roller 13 may be changed, or the biasing means for the pressure roller 13 may be formed of a material other than the spring 19. Further, the pressure bonding release does not necessarily have to be done manually.

〔Effect of the invention〕

As explained above, the fixing device according to the present invention has a structure in which the heating roller and the pressure roller are pressed against each other in a fixing state, and has an extremely excellent cleaning performance, a simple structure, easy maintenance, and inexpensive cleaning. A fixing device equipped with a mechanism can be provided.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of a copying machine equipped with a fixing device of the present invention. FIGS. 2 and 3 show a side view and a sectional view of the fixing device. FIG. 4 is a cross-sectional view showing the relative relationship between the rollers of the fixing device. 10: Fixing device, 11: Heat roller, 12: Heater lamp, 13: Pressure roller, 14: Cleaning member (paper tube), 14A: External wall surface, 14B:
Inner wall surface, 15: Paper ejection roller, 17: Pressure lever,
20: Chassis, 21: Fixed shaft, 23: Operation lever.

Claims (1)

[Scope of Claims] 1. A fixing device including a rotatable heating roller, a pressure roller that rotates in pressure contact with the heating roller, and a pressure lever that supports the pressure roller and biases the pressure roller toward the heating roller. A fixed shaft that is fixed to the fixing device frame parallel to the rotation axis of the pressure roller and pivotally supports the pressure lever in a swingable manner; and a cylindrical shape that loosely fits on the outer peripheral surface of the fixed shaft. , and a cleaning member whose inner wall surface in contact with the outer circumferential surface of the fixed shaft is formed into a smooth surface with a small coefficient of friction, and the cleaning member is compressed by the outer circumferential surface of the fixed shaft and the surface of the pressure roller. What is claimed is: 1. A fixing device, characterized in that the fixing device is supported by a pressure roller, rotates as a result of driving rotation of a pressure roller, and slides on an outer periphery of the fixed shaft. 2. Claim 1, wherein the cleaning member is formed of a cylindrical paper tube.
Fixing device as described in section.