JP3522196B2 - Fixing unit in image forming apparatus - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] 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. 2. Description of the Related Art In an electrophotographic image forming apparatus represented by a copying machine, the surface of a photosensitive drum is uniformly charged, and then the surface of the photosensitive drum is image-exposed according to predetermined image information. To form an electrostatic latent image on the surface of the photoreceptor drum, transfer the toner image formed by developing the electrostatic latent image with charged toner to a predetermined transfer paper surface, and then heat by a fixing roller. By fixing the toner image transferred to the transfer paper surface by pressing,
An image is formed. In such an image forming apparatus, a fixing roller forms a pair with a pressure roller, and is provided together with the pressure roller in a fixing unit disposed on a transfer path of transfer paper. During this time, the toner image is fixed on the surface of the transfer paper by passing the transfer paper such that the surface on which the toner image is formed faces the fixing roller. The above-mentioned fixing roller is provided with a heating device such as a heater inside, and 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 to thereby form the toner. The image is fixed on the transfer paper surface. Therefore, in order to prevent toner from adhering to the surface of the fixing roller, an oil roller impregnated with release oil such as silicone oil is pressed against the surface of the fixing roller. That is, the oil roller applies the release oil to the surface of the fixing roller to prevent toner from adhering to the surface of the fixing roller. Further, 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 above-described oil roller and cleaning roller 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. 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. To provide a fixing unit in which these pressure weldings are performed. Another object of the present invention is to provide a fixing unit that can easily replace an oil roller. According to the present invention, there is provided a transfer sheet having a transfer toner image, comprising a pair of rollers each comprising a fixing roller and a pressure roller rotatably held by a fixing unit frame. Is passed through the pair of rollers such that the surface on the side of the transfer toner image faces the fixing roller side, thereby fixing the transfer toner image to the transfer paper in a fixing unit. a roller, and a cleaning roller for cleaning the oil roller, the cleaning roller, as well is rotatably positioned fixed to the fixing unit frame, said fixing Yoo
A pressing cam is slidably provided on the knit frame.
The pressing cam is supported and fixed to the fixing unit frame.
The oil roller is energized by the elastic member.
Is the pressing force urged by the elastic member.
It is pressed energized by arm, the fixing roller and are held in the fixing unit frame so as to press both of the cleaning roller, the fixing unit, the Cree
Oil roller holding a running roller and the oil roller
The cleaning roller has a built-in knit
Is rotatably fixed to the oil unit.
The shaft of the oil roller is provided on the side of the oil unit.
Movably held in the opening,
By attaching the knit to the fixing unit frame,
The cleaning roller and the oil roller are
A fixing unit is provided, which is positioned at a predetermined position of a slot frame . In the present invention, the cleaning roller is fixed and held on the unit frame, and only the oil roller is held by an elastic member so as to press against 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 by the cam urged by the elastic member so as to be in pressure contact with both the fixing roller and the cleaning roller. Therefore, 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 operation of the oil roller can be performed very easily. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on specific examples shown in the accompanying drawings. FIG. 1 is a schematic diagram showing a positional relationship between rollers held by a 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 between the rollers 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)
Are held so as 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.
The fixing roller 1 is heated to a temperature higher than 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 oil roller 6 applies release oil 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, whereby the release oil is applied 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 cam is fixed to a unit frame (fixing unit frame) not shown, and the oil roller is spring-biased.
The pressing cam 8 is supported by the unit frame so as to be energized. 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 indicated by, for example, an arrow A in FIG. Has been energized in the direction. The cam surface of the cam 8 is in contact with the shaft 6a of the oil roller 6 as shown in FIG. 1, so that the oil roller 6 is moved in the direction shown by the arrow B in FIG. As a result, the fixing roller 1 and the cleaning roller 7
It is pressed against both. 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 becomes 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 energized 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 using the cam 8 described above can be assembled as shown in FIG. That is, in FIG. 2 showing an exploded view of a main part of the fixing unit of the present invention, the oil roller 6 and the 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 in 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 designated by 20, the shafts of the fixing roller 1 and the pressure roller 2 are supported on the 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 a rear accommodation part 21b. In the oil unit housing 22, a guide 25 extending from the back wall 20c and extending in parallel with 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 is slidable up and down along the inner surface of the rear wall 20c and the inner surface of the guide 25. The fixing unit of the present invention can be easily assembled by inserting the above-described oil unit 10 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. Accordingly, in this state, the oil unit 10 shown in FIG.
It is necessary to push the shaft 6a into the introduction portion 21a by pressing the middle left side . Thus, the shaft 6a is connected to the introduction section 2
1a, the cam 8 slides upward along with it, but the shaft 6a moves to the vertex 8a of the cam surface of the cam 8.
, The spring 26 pushes the shaft 6a into the housing 21b on the rear side, so that an elastic force is applied from the cam 8 to the shaft 6a.
Acts on a. Therefore, after this, the oil unit 1
0 need not be pressed, and the shaft 6a is automatically
1 will be pushed. The shaft 6a is the accommodation portion 21b
When the oil roller 6 is pushed into the inside, the oil roller 6 comes into contact with the roller surface of the fixing roller 1 which is already fixed in position, 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 above-described fixing unit of the present invention, the oil unit 10 can be easily attached 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 part 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 outward from 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. 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 fixed to the fixing roller and the cleaning roller. Can be pressed against both.
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. [Description of Signs] 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)

(57) [Claim 1] A transfer sheet having a transfer toner image is provided with a pair of rollers each including a fixing roller and a pressure roller rotatably held in a fixing unit frame. An oil roller impregnated with release oil; a fixing unit for fixing a transfer toner image to transfer paper by passing between the pair of rollers such that the image side faces the fixing roller side; and a cleaning roller for cleaning the oil roller, the cleaning roller, as well is rotatably positioned fixed to the fixing unit frame, said the fixing unit frame is freely pressing cam slide
The pressing cam is supported by the fixing unit frame.
The oil roller is energized by the elastic member held and fixed, and the oil roller is energized by the elastic member.
It is pressed energized by the pressing cam are, the fixing roller and are held in the fixing unit frame so as to press both of the cleaning roller, the fixing unit, the said cleaning roller
An oil unit that holds the oil roller is incorporated
The cleaning roller is attached to the oil unit.
The oil roller is rotatably fixed in position, and the oil roller has its shaft
Moves into an opening provided on the side surface of the oil unit.
And the oil unit is fixed to the fixing unit.
By mounting the cleaning roller on the cleaning frame,
And the oil roller are positioned at predetermined positions on the fixing unit frame.
Fixing unit characterized in that it is-decided fit.