JP2002014563A - Fixing unit for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing unit by which positioning for the press-contact of an oil roller and a fixing roller and that of the oil roller and a cleaning roller is easily performed and also the press-contact is performed by using elastic members whose number is made as small as possible. SOLUTION: In the fixing unit provided with a pair of rollers consisting of the fixing roller and a pressure roller respectively rotatably held at a unit frame and fixing a transfer toner image on transfer paper by passing the transfer paper having the transfer toner image between the pair of the rollers so as to make a surface on the side of the transfer toner image face the side of the fixing roller, the unit is further provided with the oil roller impregnated with releasing oil and the cleaning oil to clean the oil roller, and the cleaning roller is rotatably fixed in terms of a position at the unit frame, and the oil roller is held at the unit frame so as to come in press-contact with both the fixing roller and the cleaning roller by a cam pressed by the elastic member supported and fixed at the unit frame.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing unit used in an image forming apparatus such as a copying machine, a facsimile, and a printer for forming an image by electrophotography.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus represented by a copying machine, a photosensitive drum surface is uniformly charged, and then the photosensitive drum surface is image-exposed in accordance with predetermined image information to thereby expose the photosensitive drum. An electrostatic latent image is formed on the surface of the body drum, and a toner image formed by developing the electrostatic latent image with charged toner is transferred to a predetermined transfer paper surface, and then heated and pressed by a fixing roller. By fixing the toner image transferred to the transfer paper surface,
An image is formed.

In such an image forming apparatus, the fixing roller is paired with a pressure roller, and is provided together with the pressure roller in a fixing unit arranged on a transfer path of a transfer sheet. During this time, the transfer image is passed through the transfer sheet so that the surface on which the toner image is formed faces the fixing roller, so that the toner image is fixed on the transfer sheet surface.

The above-mentioned fixing roller is provided with a heating device such as a heater inside. The fixing roller heated to a temperature higher than the softening or melting temperature of the toner is pressed against the toner image on the transfer paper. The image is fixed on the transfer paper surface. For this reason, an oil roller impregnated with release oil such as silicone oil is pressed against the surface of the fixing roller in order to prevent toner from adhering to the surface of the fixing roller. That is, the release of oil onto the surface of the fixing roller is prevented by applying the release oil to the surface of the fixing roller by the oil roller. Also, a cleaning roller is pressed against the surface of the oil roller so that the surface of the oil roller is kept clean and a constant release oil is applied to the surface of the fixing roller for a long period of time.

[0005]

The oil roller and the cleaning roller as described above are provided in a fixing unit together with a roller pair of a fixing roller and a pressure roller.
In such a fixing unit, since the oil roller is pressed against the fixing roller and the cleaning roller is pressed against the oil roller, the positioning of each roller is very troublesome, and the oil roller is pressed against the fixing roller. An elastic member for pressing the cleaning roller and the oil roller together with an elastic member for
The number of parts is large, and the structure is complicated. Furthermore,
When a certain amount of release oil is consumed, the oil roller
The oil roller needs to be replaced, but since the oil roller is pressed against the fixing roller and the cleaning roller, there is a problem that the replacement is extremely troublesome.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to facilitate the above-described positioning for pressing the oil roller and the fixing roller and for pressing the oil roller and the cleaning roller, and to reduce the number of elastic members as small as possible. The purpose of the present invention is to provide a fixing unit in which the above-mentioned pressing is performed by using the fixing unit. Another object of the present invention is to provide a fixing unit that can easily replace an oil roller.

[0007]

According to the present invention, a transfer sheet having a transfer toner image is provided by providing a pair of rollers each including a fixing roller and a pressure roller rotatably held in a unit frame. By passing between the pair of rollers such that the image side faces the fixing roller side,
In a fixing unit for fixing a transfer toner image to transfer paper, the fixing unit includes an oil roller impregnated with release oil, and a cleaning roller for cleaning the oil roller, wherein the cleaning roller is rotatable on the unit frame. The position of the oil roller is fixed, and the oil roller is held by the unit frame so as to be pressed against both the fixing roller and the cleaning roller by a cam urged by an elastic member supported and fixed to the unit frame. A fixing unit is provided.

In the present invention, the cleaning roller is fixedly held on the unit frame, and only the oil roller is held by the elastic member so as to be in pressure contact with both the fixing roller and the cleaning roller. That is, the elastic member is supported and fixed to the unit frame, and the oil roller is urged to press against both the fixing roller and the cleaning roller by the cam urged by the elastic member. Accordingly, since the pressure contact of the cleaning roller with the oil roller and the pressure contact of the oil roller with the fixing roller are performed only by the elastic member that urges the cam, the number of parts is small, and the structure is extremely simple. . In addition, since the cleaning roller is fixed in position and only the oil roller is positioned by the elastic member, such positioning of the roller can be performed easily and reliably. Further, the replacement work of the oil roller can be performed very easily.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to specific examples shown in the accompanying drawings. FIG. 1 is a schematic view showing a positional relationship between respective rollers held by the fixing unit of the present invention, and FIG. 2 is an exploded side sectional view showing a main part of the fixing unit of the present invention.

FIG. 1 shows the positional relationship of each roller held by the fixing unit of the present invention. In the fixing unit of the present invention, a fixing roller 1 and a pressure roller 2 are united similarly to a conventionally known fixing unit. Frame (omitted in FIG. 1)
To be pressed against each other. For example, the fixing roller 1 is rotatably held by a unit frame,
The pressure roller 2 is urged by an elastic member (not shown) and is pressed against the fixing roller 1. The fixing roller 1
A heating device such as a heater is built in.
Is heated above the softening or melting temperature of the toner image 5 formed on the transfer paper indicated by
When the transfer paper 3 is passed between the roller pair of the fixing roller 1 and the pressure roller 2 in a state where
Is fixed on the transfer paper 3.

The fixing roller 1 includes an oil roller 6
The release roller is applied by the oil roller 6 to prevent the toner from adhering to the surface of the fixing roller 1 when the toner image 5 is fixed. The oil roller 6 is a roller made of a porous resin or rubber impregnated with a release oil typified by silicone oil such as dimethyl silicone oil, and is pressed against the surface of the fixing roller 1 by pressing. The release oil oozes on the surface of the fixing roller 1, thereby applying the release oil to the surface of the fixing roller 1.

A cleaning roller 7 is pressed against the oil roller 6. This cleaning roller 7
Is formed of a rigid material such as metal or hard resin or a felt material, and the cleaning roller 7 keeps the surface of the oil roller 6 clean at all times, so that the release oil is stably applied. It has become.

In the present invention, of the oil roller 6 and the cleaning roller 7, the cleaning roller 7 is
The position of the oil roller 6 is fixed to a unit frame (not shown), and the oil roller 6 is supported by the unit frame such that the oil roller 6 is biased by a spring-biased cam 8. That is, one end of a spring (omitted in FIG. 1) is fixed to the unit frame, and a cam 8 is provided at the other end of the spring.
The cam 8 is urged in a direction indicated by, for example, an arrow A in FIG. The cam surface of the cam 8 is in contact with the shaft 6a of the oil roller 6 as shown in FIG.
The oil roller 6 is urged by the cam surface of the cam 8 in the direction shown by the arrow B in FIG. 1, and as a result, is pressed against both the fixing roller 1 and the cleaning roller 7.

As described above, by fixing the position of the cleaning roller 7 to the unit frame and urging the oil roller 6 via the cam 8, the oil roller 6 is provided with an elastic member (spring) for urging the cam 8. ), The positioning can be performed very easily and reliably, and the cleaning roller 7 does not need to be positioned, so that the unit can be easily assembled. Moreover, the oil roller 6
Is biased via the cam 8, the mounting and demounting operations can be performed with one touch, and the replacement of the oil roller 6 can be performed very easily.

The fixing unit of the present invention in which the oil roller 6 is pressed against the cleaning roller 7 and the fixing roller 1 by using the cam 8 described above can be assembled as shown in FIG.

That is, in FIG. 2 which shows an exploded view of a main part of the fixing unit of the present invention, an oil roller 6 and a cleaning roller 7 are provided in an oil unit indicated by 10 as a whole. The oil unit 10 has a box shape with one side opened, and a shaft 6a of the oil roller 6 and a shaft 7a of the cleaning roller 7 are held on a side surface 10a. That is, as is clear from FIG. 2, the shaft 6a of the oil roller 6 extends through a large opening 11 formed in the side surface 10a, and the shaft 6a can move freely in the opening 11. Has become. On the other hand, the shaft 7a of the cleaning roller 7 is rotatably fitted into a small opening (not shown) formed in the side surface 10a, and the cleaning roller 7 is fixed in position to the oil unit 10.

On the other hand, in the fixing unit frame generally denoted by 20, the shafts of the above-mentioned fixing roller 1 and pressure roller 2 are supported on side walls 20a at both ends, and these side walls 20a are connected to the upper ceiling wall. 20b and a back wall 20c located on the left side in FIG.
Although not shown, an opening is formed in the rear wall 20c so that the oil unit 10 can be incorporated into the fixing unit frame 20.

The side wall 20 of such a fixing unit frame 20
a, an oil unit housing 22 is formed,
The housing 22 has a recess 21 for housing the shaft 6 a of the oil roller 6. This recess 21
It is composed of a substantially horizontal introduction part 21a and an accommodation part 21b on the back side.

In the oil unit housing 22, a guide 25 extending from the back wall 20c and extending parallel to the back wall 20c extends from the ceiling wall 20b. , The spring 26 is fixed,
The cam 8 is attached to the tip of the spring 26. That is, the cam 8 can slide up and down along the inner surface of the rear wall 20c and the inner surface of the guide 25.

In the fixing unit of the present invention, the above-described oil unit 10 is easily assembled by inserting it into the oil unit accommodating portion 22 of the fixing unit frame 20 having the above-described structure. That is, the oil unit 10
Is inserted into the fixing unit frame 20, the shaft 6 a of the oil roller 6 is inserted through the concave portion 21 of the housing portion 22, but passes through the horizontal introduction portion 21 a in the concave portion 21. Occasionally, as apparent from FIG. 2, an elastic force that is pushed back by the cam 8 acts on the shaft 6 a. Therefore, in this state, it is necessary to press the upper portion of the oil unit 10 to push the shaft 6a into the introduction portion 21a. In this way, when the shaft 6a is pushed into the introduction portion 21a, the cam 8 slides upward accordingly. 6a is the accommodation section 2 on the back side
An elastic force that pushes into the shaft 1b acts on the shaft 6a from the cam 8. Therefore, thereafter, there is no need to press the oil unit 10, and the shaft 6a is automatically pushed into the housing portion 21b. When the shaft 6a is pushed into the housing portion 21b, the oil roller 6 comes into contact with the roller surface of the fixing roller 1 whose position is already fixed, and the oil roller 6 comes into pressure contact with the fixing roller 1.

In this state, the frame of the oil unit 10 is
The cleaning roller 7 is positioned by being fitted and fixed in an elastic fitting portion (not shown) formed in the fixing unit frame 20, and the oil roller 6 pressed against the fixing roller 1 is also fixed to the cleaning roller 7. It is kept in a pressed state. As described above, by utilizing the cam 8 urged by the spring 26, the oil roller 6 is pressed against both the cleaning roller 7 and the fixing roller 1 with a simple operation of pushing the oil unit 10 and with one touch. can do.

In the fixing unit of the present invention described above, the oil unit 10 can be easily attached to and detached from the fixing unit with one touch. That is, when the frame of the oil unit 10 is pulled out from the elastic fitting portion provided on the fixing unit frame 20 (not shown), and the upper portion of the oil unit 10 is pulled up, the shaft 6a of the oil roller 6 becomes a cam. 8 while pushing it upward.
1b, when the shaft 6a passes over the apex 8a of the cam surface of the cam 8, the shaft 6a is moved by the spring 26 into the introduction portion 21 in the same manner as when the oil unit 10 is mounted.
An elastic force that pushes the shaft 6a out of the shaft 6a acts on the shaft 6a.
Therefore, thereafter, the shaft 6a is automatically taken out of the concave portion 21, and thus the oil unit 10 is detached from the fixing unit frame 20. In this manner, the attachment and detachment of the oil unit 10 from the fixing unit can be easily performed with one touch. Therefore, in the fixing unit of the present invention, the replacement of the oil roller 6 can be performed very easily.

[0023]

According to the present invention, the oil roller is urged by using the cam urged by the elastic member supported and fixed to the unit frame, so that the oil roller is used as both the fixing roller and the cleaning roller. Can be pressed.
That is, the elastic member used only needs to urge the cam. Therefore, the structure of the fixing unit is extremely simple, the number of components is small, and the positioning of each roller is performed easily and reliably. be able to. Further, the work of attaching and detaching the oil roller and the cleaning roller to and from the fixing unit can be easily performed, and the replacement of the oil roller can be performed very easily.

[Brief description of the drawings]

FIG. 1 is a view showing a schematic structure of a tandem type full-color image forming apparatus of the present invention.

FIG. 2 is a diagram showing a planar structure of an air blowing device used in the image forming apparatus shown in FIG.

[Explanation of symbols]

 1: Fixing roller 6: Oil roller 6a: Oil roller shaft 7: Cleaning roller 7a: Cleaning roller shaft 8: Cam 10: Oil unit 26: Spring 20: Fixing unit frame

Claims (1)

[Claims] An image forming apparatus includes a pair of rollers each including a fixing roller and a pressure roller rotatably held by a unit frame. The transfer paper having a transfer toner image is transferred to a surface of the transfer toner image facing the fixing roller. In the fixing unit for fixing the transfer toner image to the transfer paper by passing between the pair of rollers as described above, an oil roller impregnated with release oil, and a cleaning roller for cleaning the oil roller are provided. The cleaning roller is rotatably fixed to the unit frame, and the oil roller is fixed to the fixing roller and the cleaning unit by a cam biased by an elastic member supported and fixed to the unit frame. A fixing unit, wherein the fixing unit is held by the unit frame so as to be in pressure contact with both rollers.