JPH0535142A - Fixing device - Google Patents

Abstract

PURPOSE:To provide a fixing device for which a cleaning mechanism which performs cleaning to remove the stain of a heating roller over a long term is adopted and in which stable fixing actions are kept over a long term. CONSTITUTION:This device is constituted by providing the heating roller 6 for welding a toner image T on a paper P, a pressure roller 8 for pressing the paper P to the roller 6, a cleaning roller 20 which rolls in contact with the surface of the roller 6 and rotates in a reverse direction to the roller 6 so as to make the surface of the roller 6 in a clean state, and a roller supporting means which supports the roller 20 so that the roller 20 always rolls in contact with the roller 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device applied to an image forming apparatus such as an electrophotographic copying machine or a laser printer.

[0002]

2. Description of the Related Art In recent years, as one of fixing devices of this type, a heating roller and a pressure roller which is in pressure contact with the heating roller are provided, and a transfer member such as a sheet is placed between the rollers. A heating roller type fixing device for heating and fusing and fixing a powder image on a transfer member by passing it through is widely put into practical use.

This type of fixing device has a feature that it is possible to perform stable fixing although it has a small structure, but on the other hand, since powder adheres to the surface of the heating roller and stains it, it is removed. A cleaning mechanism is needed to keep it clean.

Conventionally, a cleaning mechanism has been used as a cleaning mechanism.
There is a problem in that the cleaning life is short because the contacting position is fixed because the contacting position of the ning felt is fixed.

Therefore, as a cleaning mechanism capable of extending the cleaning life, a heating roller is provided on the surface of the heating roller.
Attempts have been made to adopt a roller-type cleaning mechanism for rolling a cleaning roller that rotates in the opposite direction to the roller to bring the surface of the heating roller into a clean state.

However, when it is attempted to transmit the driving force of the heating roller to the cleaning roller through the gear group including the intermediate gear, the gear mounted on the cleaning roller will be affected by the rotational direction. Gear that meshes with (intermediate gear)
There was a problem that the cleaning roller floated up due to the force in the direction away from the heating roller, and did not reliably contact the heating roller, so that a good cleaning state could not be obtained.

[0007]

As described above, there has been no conventional cleaning mechanism that can clean the dirt of the heating roller for a long period of time, and the cleaning mechanism is stable over a long period of time. There was a problem that the fixing operation could not be maintained.

The present invention has been made based on the above circumstances, and it is an object of the present invention to employ a cleaning mechanism capable of cleaning dirt on a heating roller for a long period of time. An object of the present invention is to provide a fixing device that can maintain a stable fixing operation.

[0009]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a heating roller for welding a powder image onto a transfer member, and the transfer member for the heating roller. A pressure roller for pressing, and a cleaning roller that contacts the surface of the heating roller and rotates in the opposite direction of the heating roller to clean the surface of the heating roller. And a roller supporting means for supporting the cleaning roller so that the cleaning roller is always in rolling contact with the heating roller.

[0010]

As described above, the roller supporting means is provided and the cleaner is provided.
The fixing roller is supported so that it always rolls on the heating roller, and in this state the cleaning roller is rotated in the direction opposite to the direction of the heating roller. The cleaning life is greatly improved as compared with the case of using a felt, and the contamination of the heating roller can be prevented for a long time. This makes it possible to maintain a stable fixing operation for a long period of time.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows a state in which the fixing unit 1 as the fixing device of the present invention is incorporated in the main body 2 of the image forming apparatus.

The fixing unit 1 is equipped with a heating roller 6 containing a heater lamp 5 as a heat source, and a pressure roller 8 pressed against the heating roller 6 by an urging force of a spring 7. It is a heating roller type fixing device.

Then, by passing a sheet P as a transfer member between the heating roller 6 and the pressure roller 8, the toner image T as a powder image on the sheet P is fused and fixed. It is like this.

The heating roller 6 and the pressure roller 8 are surrounded by an upper casing 10 and a lower casing 11, and the outside is kept as much as possible so as to secure a favorable temperature atmosphere necessary for fixing. It is structured so that heat cannot escape. Further, on the upper surface side of the upper casing 10, a fuser guard 12 is provided as a safety means for preventing burns in a state of covering the upper casing 10.
Is provided.

Further, paper guides 13 and 14 are arranged in the vicinity of the upstream side of the contact portion between the heating roller 6 and the pressure roller 8, and an image forming mechanism of the preceding stage (shown in the figure) is arranged via a transport mechanism 15. The leading end of the paper P fed from (No) is reliably guided between the heating roller 6 and the pressure roller 8.

Further, in the vicinity of the downstream side of the contact portion between the heating roller 6 and the pressure roller 8, the paper P wrapped around the heating roller 6 is formed.
Peeling claw 16 that also serves as a guide for peeling the sheet, and the paper guide 1
7 is provided, and the fixed sheet P is ejected to the roller pair 1
It is supposed to lead to 8.

Further, a roller type cleaning mechanism 21 provided with a cleaning roller 20 made of felt and rolling on the upper portion of the heating roller 6 is provided and adhered to the surface of the heating roller 6. The toner as powder is removed.

Further, a thermistor 22 as a temperature sensor is provided in contact with the heating roller 6 downstream of the position of the cleaning roller 20 in the rotating direction, in contact with the heating roller 6. The surface temperature of 6 is detected, and the temperature is controlled so as to maintain the temperature required for fixing.

Next, referring to FIG. 1 and FIG.
The la-type cleaning mechanism 21 will be described.

The cleaning roller 20 is supported by the roller supporting means 19 so as to always be in rolling contact with the heating roller 6.

That is, the support shaft portion 25a on one end side is rotatably held by the bush 27 as a bearing engaged and held by the bearing holding groove 26a of the bearing holding bracket 26, and the support shaft portion 25b on the other end side is supported. It is rotatably held by being fitted in the bearing hole of the arm 28.

At the tip of the support shaft portion 25a on the one end side,
A gear 30 is attached and, as shown in FIG. 1, a first gear meshing with a gear 31 for driving the heating roller 6.
The second intermediate gear 33, which is integral with the intermediate gear 32 of FIG.

When the fixing unit 1 is incorporated in the apparatus body 2 of the image forming apparatus, the gear 31 is in mesh with the drive gear 34 on the apparatus body 2 side and receives the driving force. The heating roller 6 rotates in the direction of arrow a in FIG. 2 and the cleaning roller 20 rotates in the opposite direction (direction of arrow b).

A fixed bracket 36 screwed to the upper casing 10 is provided with a shaft 35 that rotatably supports the integrated intermediate gears 32 and 33.

The bearing holding bracket 26 is rotatably attached via the shaft 35. The bearing holding bracket 26 is provided with a torsion spring 40 as a biasing means in which a winding portion is externally fitted around the shaft 35, one end side is engaged with the fixed bracket 36, and the other end side is engaged with the bearing holding bracket 26. The cleaning roller 20 is always urged in the direction of pressing it against the heating roller 6.

On the other hand, the support arm 28 rotatably holding the support shaft portion 25b on the other end side of the cleaning roller 20 is
Fixed bracket 4 screwed to upper casing 10
1 is rotatably supported with respect to a shaft 42 protruding from the shaft 1, and a winding portion is externally fitted to the shaft 42 so that one end side is a fixed bracket 41 and the other end side is a support arm 28. With the torsion spring 43 as the biasing means engaged, at all times,
The cleaning roller 20 is urged in the direction in which it is pressed against the heating roller 6.

Reference numerals 45 and 46 shown in FIG. 3 are heating rollers.
A group of gears 47 for transmitting the driving force of the gear 31 for driving the roller 6 to the paper discharge roller pair 18 side, and 47 for supplying the electric power to the heater lamp 5 which is the heat source of the heating roller 6. It is a power supply terminal for supplying.

Therefore, the toner t attached to the surface of the heating roller 6 is a cleaner which rotates in the direction opposite to that of the heating roller 6.
The cleaning roller 20 removes the cleaning roller 20 and the cleaning life is greatly improved as compared with the case where a conventional fixed cleaning felt is used, and the heating roller 6 can be prevented from being soiled for a long period of time. This makes it possible to maintain a stable fixing operation for a long period of time.

Further, as described above, the cleaning roller 2
No. 0 is a bearing hole of a support arm 28, and a support shaft portion 25a on one end side thereof is supported by a bush 27 engaged and held by a bearing holding groove 26a of a bearing holding bracket 26, and a support shaft portion 25b on the other end side thereof is a bearing hole of a supporting arm 28. By fitting (not shown),
Each is supported. Therefore, the bearing holding bracket 26 is rotationally displaced against the biasing force of the torsion spring 40 to release the engagement between the bearing holding groove 26a and the bush 27, and thereafter, the support shaft portion on the other end side. By pulling 25b in the direction of pulling it out from the bearing hole (not shown) of the support arm 28, it can be easily removed, and it can be mounted by the reverse operation, and replacement is extremely easy.

Further, the cleaning roller 20 is heated by a heating roller.
When the driving force of the rotor 6 is transmitted through the gear groups 31, 32, 33 and 30, the gear 30 attached to the cleaning roller 20 is separated from the intermediate gear 33 meshing with the gear because of the rotational direction. However, since the bearing holding bracket 26 that holds the bush 27 in engagement is pressed by the torsion spring 40, the cleaning roller is pressed.
The roller 20 does not float, and the roller 20 is reliably in contact with the heating roller. As a result, a reliable and stable fixing operation can be maintained.

The present invention is not limited to the above embodiment,
Of course, various modifications can be made without departing from the spirit of the invention.

[0033]

As described above, according to the present invention,
It is possible to employ a cleaning mechanism capable of cleaning dirt on the heating roller for a long period of time, and to provide a fixing device capable of maintaining a stable fixing operation for a long period of time.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a fixing device of the present invention.

FIG. 2 is a schematic configuration diagram showing a state where the image forming apparatus is incorporated in the apparatus main body.

FIG. 3 is an exploded perspective view of the same main part.

[Explanation of symbols]

P ... Paper (transfer member), T ... Toner image (powder image), 1 ...
Fixing unit (fixing device), 2 ... Image forming apparatus main body, 5 ... Heater lamp (heat source), 6 ... Heating roller, 8 ...
Pressure roller, 10 ... upper casing, 11 ... lower casing, 20 ... cleaning roller, 21 ... cleaning mechanism, t toner (powder), 25a ... support shaft on one end side Part, 2
5b ... Shaft part on the other end side, 26 ... Bearing holding bracket, 2
6a ... Bearing retaining groove, 27 ... Bush (bearing), 28 ... Support arm, 30 ... Gear, 31 ... Gear, 32 ... First intermediate gear, 33 ... Second intermediate gear, 34 ... Drive gear, 35 …
Shaft, 36 ... Fixed bracket, 40 ... Torsion spring (biasing means), 41 ... Fixed bracket, 42 ... Shaft, 43 ... Torsion spring (biasing means).

Claims (1)

Claim: What is claimed is: 1. A heating roller for welding a powder image onto a transfer member, and a pressure roller for pressing the transfer member against the heating roller. A cleaning roller that contacts the surface of the heating roller and rotates in a direction opposite to the direction of the heating roller to clean the surface of the heating roller; A fixing device comprising: a roller supporting means for supporting the cleaning roller so as to always be in rolling contact with the heating roller.