JPH05297752A - Fixing device - Google Patents

Abstract

PURPOSE:To uniformly execute cleaning by making the magnitude of load by component force for moving the center of a gear which acts on a cleaning roller and an elastic member on the gear side equal to the magnitude of the load by an elastic member on an opposite side to the gear side. CONSTITUTION:The magnitude of the load obtained by adding the pressuring force of a spring 34 on the gear 33 side to the component force F2 is made equal to the magnitude by the pressuring force of a spring 35 on the opposite side. Supposing that the pressuring force on the gear 33 side of the cleaning roller 30 is P, P=P1-F2 holds, and the pressuring force on the opposite side of the roller 30 is still P2, then the magnitude of the pressuring force P1 and P2 of the springs 34 and 35 are set so that P1+(-F2) P2 may hold to obtain P P2. Namely, the pressuring force P1 of the spring 34 is set to be larger than the press force P2 of the spring 35 by F2. By such constitution, the difference of the pressuring force between the gear 33 side of the roller 30 and the opposite side is hardly found.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing roller pair, in which a cleaning roller for contacting and cleaning the surface of at least one roller is connected to a drive gear train for driving the fixing roller pair. And a fixing device that is rotated.

[0002]

2. Description of the Related Art Fixing devices of the above type are well known and are used in copying machines, printers, facsimiles and the like. In this type of fixing device, a cleaning roller is provided for cleaning toner, paper dust, etc. attached to the fixing roller pair. This cleaning roller is known to rotate around the fixing roller, or to rotate the cleaning roller so that the gear on the cleaning roller meshes with the gear attached to the fixing roller directly or via an idle gear. In this rotation driving method, springs for urging a pressing force having substantially the same magnitude are provided on both sides of the cleaning roller to ensure the contact of the cleaning roller with the fixing roller.

The former swing-type cleaning roller may not swing due to a slip phenomenon, and a good cleaning action may not be obtained. On the other hand, the latter cleaning roller of the rotary drive type,
Such a problem does not occur, and a peripheral speed difference can be generated between the surface of the fixing roller and the surface of the cleaning roller by appropriately setting the gear ratio of the fixing roller and the cleaning roller. It is possible to efficiently remove the toner, paper dust, and the like.

[0004]

However, since the cleaning roller of the rotational driving type described above has a rotational torque acting in the pressure angle direction of the gear attached thereto,
A component force for rotating the gear and a component force for moving the center of the gear are generated. At this time, the component force for moving the center of the gear affects the pressure contact force between the fixing roller and the cleaning roller only on one side. That is, in order to guarantee the contact between the fixing roller and the cleaning roller, the cleaning roller is urged to the fixing roller by the spring, but a part of the component force for moving the center of the gear is due to this pressing force. The effect of strengthening or weakening. As a result, the cleaning roller has a pressure difference between the side where the gear is attached and the side opposite to the side where the gear is attached, and the cleaning state becomes uneven in the longitudinal direction of the fixing roller. As a result, there is a problem that toner adheres to a part of the fixing roller due to defective cleaning due to use over time.

The present invention solves the above-mentioned conventional problems,
An object of the present invention is to provide a fixing device capable of uniformly cleaning the fixing roller in the longitudinal direction.

[0006]

According to the present invention to achieve this object, a drive gear train for driving a fixing roller pair by a cleaning roller that contacts the surface of at least one roller of the fixing roller pair and cleans the surface. In a fixing device rotated via a gear connected to the cleaning roller, elastic members for urging the cleaning roller in a direction in which the cleaning roller is pressed are provided on both sides of the cleaning roller, and the cleaning roller is rotated when the gear rotates. It is characterized in that the component force for moving the center of the gear acting on the gear and the load due to the elastic member provided on the gear side and the load due to the elastic member provided on the opposite side are substantially equal to each other.

Furthermore, the present invention is characterized in that the gear is attached to the shaft of the cleaning roller via an Oldham shaft joint.

[0008]

According to the above construction, even if the pressing force on the side where the gear is provided is strengthened or weakened by the component force that moves the center of the gear that acts on the cleaning roller when the gear rotates, Since the magnitude of the load due to the elastic member provided on the gear side and the magnitude of the load due to the elastic member provided on the opposite side are made substantially equal, the cleaning roller is provided on the side provided with the gear and the opposite side. The difference in applied pressure can be almost eliminated.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic explanatory view of a laser printer including a fixing device according to the present invention. In FIG. 1, reference numeral 1
Is a device main body, and the device main body 10 is an upper structure 10
a and the lower structure 10b, and the upper structure 10a
Is attached to the lower structure 10b via a shaft 11 so as to be openable and closable. An image forming unit having a belt-shaped photoconductor 12 is provided in the main body 10 of the apparatus, and the photoconductor 12 runs in the direction of the arrow.

Electrophotographic process means excluding the optical writing means such as the charging means 13, the developing device 14, the transfer means 15, and the cleaning means 16 are arranged around the photosensitive member 12 in the order of the traveling direction thereof. An optical writing unit 17 is arranged below these electrophotographic process units, and a sheet feeding device 18 is arranged above the right side.

The transfer material fed by the paper feed roller 19 of the paper feed device 18 is timed by the registration roller pair 21 and passes through the conveyance path 20 to the photosensitive member 1.
2 is conveyed to the upper side. The photoconductor 12 is rotationally driven counterclockwise as shown by the arrow, and at this time, the charging means 13
The surface is uniformly charged by the optical writing means 1
Laser light from 7 is emitted from below. as a result,
An electrostatic latent image is formed on the photoconductor 12. This latent image is visualized by toner when facing the developing device 14. Then, this visible image is transferred by the transfer means 15 to the lower surface of the transfer material that has been conveyed to the upper side of the photoconductor 12. The transferred transfer material is conveyed to the fixing device 22, and the visible image on the transfer material is fixed. Fixing device 2
The transfer material exiting 2 is guided by the paper discharge roller 23 to the paper discharge guide 24 and is stacked on the paper discharge tray 25.

The fixing device 22 is, as shown in FIG.
The casing 26 has a fixing roller 27 having a heater 28 as a heating means therein, and a pressure roller 29 pressed against the fixing roller 27. The fixing device 22 contacts the surface of the fixing roller 27. The cleaning roller 30 is provided. As shown in FIG. 3, a gear 31 is attached to the fixing roller 27.
1 is one in a gear train drivingly connected to a driving device (not shown), and the fixing roller 27 is rotated counterclockwise in FIG.

As shown in FIG. 3, bearings 32 are mounted on both ends of the shaft 30a of the cleaning roller 30, and the bearings 32 are cut out from the casing 26.
It is movably fitted to a. A gear 33 that meshes with the gear 31 of the fixing roller 27 is attached to one end of the shaft 30a of the cleaning roller, and the cleaning roller 30 is rotated in the clockwise direction in FIG. Further, the cleaning roller 30 is cut off at both sides of the cleaning roller 30 via bearings 32.
Springs 34 and 35 are provided as elastic members that urge the fixing roller 27 in the direction of contact therewith.

FIG. 4 is an explanatory view showing the force acting on the cleaning roller 30 during rotation. As the gear 31 of the fixing roller 27 rotates, the gear 33 of the cleaning roller 30 rotates in the clockwise direction.
The force F acts from the gear 31 of No. 7 to the gear 33 of the cleaning roller 30. The force F acts on the intersection of the straight line connecting the centers of the two gears 31 and 33 and the common tangent line of the respective pitch circles, and the direction of the force acts in a direction inclined by the magnitude of the pressure angle of the gear 33 from the common tangent line. ..

This force F acts as a component force F1 on the common tangent line and a component force F2 in a direction perpendicular to it. The component force F1 is
It works as a force to rotate the cleaning roller 30,
The component force F2 acts on the cleaning roller 30 in the direction of moving the center of the gear 33, that is, in the direction of weakening the pressing force of the spring 34. Therefore, as shown in FIG. 3, the pressing force of the springs 34 and 35 is P
1 and P2, the gear 33 of the cleaning roller 30
The pressing force on the side provided with is P1-F2. On the other hand, the pressing force on the opposite side remains P2. Therefore, when the magnitude of the pressing force of the springs 34 and 35 is P1 = P2, the cleaning roller 30 has a difference in pressing force between the side on which the gear 33 is mounted and the side opposite thereto, and cleaning is performed in the longitudinal direction of the fixing roller 27. The condition becomes uneven.

Therefore, in this embodiment, the magnitude of the load obtained by applying the pressure force of the spring 34 provided on the gear 33 side to the component force F2 and the magnitude of the load due to the pressure force of the spring 35 provided on the opposite side are defined. It is configured to be almost equal. In this example, the component force F2 acts as a force in the direction of weakening, so that if the total pressure of the cleaning roller 30 on the side where the gear 33 is provided is P, then P = P1-F2. Further, since the pressing force on the opposite side of the cleaning roller 30 is still P2, therefore P1 is set to P≈P2.
Spring 34, 35 so that + (-F2) ≈P2
The magnitudes of the pressing forces P1 and P2 are set respectively.
That is, the pressure P1 of the spring 34 is
It is set to be larger than the pressing force P2 of 5 by about F2.

According to this structure, compared with the case where the magnitude of the pressing force of the springs 34 and 35 is P1 = P2, the cleaning roller 30 has almost no difference in the pressing force between the side on which the gear 33 is mounted and the side opposite thereto. Then, the cleaning roller 30 is evenly pressed in the longitudinal direction of the fixing roller 27.

In the above embodiment, the gear 33 of the cleaning roller 30 is the gear 31 attached to the fixing roller 27.
Although the gear 33 is directly meshed with the gear 33, the gear 33 may be meshed via an idle gear. Depending on the arrangement of the gear 33 of the cleaning roller 30 and the like, the component force F2 causes the cleaning roller 30 to move to the fixing roller 27.
It may work in the direction of pressure contact with. In this case, P1
Since + F2≈P2, the pressing force P2 of the spring 35 is
Should be set to be larger than the pressing force P1 of the spring 34 by about F2.

FIG. 5 is an exploded perspective view showing another embodiment of the present invention. In this embodiment, a cleaning roller 30 is provided with a gear 33 meshing with a gear 31 of a fixing roller 27 via an Oldham shaft joint 36. There is. Then, the magnitude of the pressing force of the springs 34, 35 (the spring 35 is not shown in the figure) for urging the cleaning roller 30 toward the fixing roller 27 is set to P1 = P2.

In the thus constructed fixing device, the cleaning roller 30 and the gear 31 of the fixing roller 27 mesh with the gear 33.
Although the rotation torque is transmitted more, only the rotation torque is transmitted to the cleaning roller 30 without affecting the spring 34 because it passes through the Oldham shaft joint 36.

[0021]

According to the above construction, according to the present invention, even if the pressing force on the side where the gear is provided is strengthened or weakened by the component force that moves the center of the gear that acts on the cleaning roller when the gear rotates. Since the component force and the load due to the elastic member provided on the gear side and the magnitude of the load due to the elastic member provided on the opposite side are substantially equal to each other, the cleaning roller has a gear side and its side. It is possible to reduce the difference in the pressing force generated on the opposite side.
Further, if a gear that meshes with the gear train is attached to the cleaning roller via the Oldham shaft coupling, only the rotational torque can be transmitted to the cleaning roller without affecting the elastic member.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of a laser printer including a fixing device according to the present invention.

FIG. 2 is a side view illustrating an embodiment of a fixing device according to the present invention.

FIG. 3 is an exploded perspective view showing the embodiment of FIG.

FIG. 4 is an explanatory diagram showing a force acting on a cleaning roller.

FIG. 5 is an exploded perspective view showing another embodiment of the present invention.

[Explanation of symbols]

 27 Fixing Roller 29 Pressure Roller 30 Cleaning Roller 31 Fixing Roller Gear 33 Cleaning Roller Gear 34, 35 Spring 36 Oldham Shaft Coupling

Claims (2)

[Claims] 1. A fixing device in which a cleaning roller for contacting and cleaning the surface of at least one roller of the fixing roller pair is rotated via a gear connected to a drive gear train for driving the fixing roller pair. In the above, elastic members for urging the cleaning roller against the fixing roller are provided on both sides of the cleaning roller, and the component force for moving the center of the gear acting on the cleaning roller when the gear rotates and the gear A fixing device characterized in that the magnitude of the load applied by the elastic member provided on the side and the magnitude of the load applied by the elastic member provided on the opposite side are substantially equal. 2. A fixing device in which a cleaning roller that contacts the surface of at least one of the pair of fixing rollers and cleans the surface is rotated via a gear connected to a drive gear train that drives the pair of fixing rollers. In the fixing device, the gear is attached to the shaft of the cleaning roller via an Oldham shaft joint.