JPH10282832A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain the reduction of the friction by a periphery of a heating roller and a bearing, lowering of the torque or the like, prevention for the adherence of a foreign matter such as toner with respect to the heating roller, and the prevention for the temp. unevenness of the heating roller. SOLUTION: In this fixing device consisting of the heating roller 2 equipped with a heating source, the pressure roller 3 held in press contact with a periphery of a heating roller 2, a frame holding the heating roller 2 in freely rotationally, the periphery of the heating roller 2 is supported by plural rotary bearings 4 (4a and 4b) supported by the frame in freely rotationally. The rotary bearings 4 supporting the heating roller 2, is respectively arranged with a specific space in range of 30 to 120 angular degrees with the center at a strait line that connects the axis of the pressure roller 3 and the heating roller axis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic copying machine,
Facsimile, improvement of a fixing device used in an image forming apparatus such as a printer, more specifically, when bearing the outer peripheral surface of the heating roller constituting the fixing device bearing, when the heat of the heating roller escapes through the bearing. The present invention relates to a fixing device having advantages such as prevention.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic copying machine, a transfer sheet on which a toner image on a photoreceptor has been transferred is guided into a fixing device, and pressurized while heating.
The toner image on the transfer paper is fixed on the transfer paper. This fixing device rotatably supports a heating roller and a pressure roller in a box-shaped frame (casing), and performs fixing when a transfer paper holding unfixed toner passes through a nip portion of both rollers. Is what you do. The heating roller has a heat source inside or on the surface thereof, and contacts the transfer paper surface with a release layer on the surface to fix the toner image. The pressure roller is pressed against the surface of the heating roller by elastic means or the like. As a method of supporting the heating roller by the frame, the outer peripheral surfaces at both ends in the axial direction of the heating roller are rotatably supported by bearings provided on the frame, while the support by the bearing and the pressing force from the pressing roller cooperate. There is known a structure for more stably supporting.

[0003]

For example, Patent No. 2
The technology described in Japanese Patent No. 504065 uses a sliding bearing as a bearing for supporting the outer peripheral surface of a heating roller, and the sliding bearing is arranged in contact with the entire outer peripheral surface of the heating roller. In order to prevent abrasion resistance between the surface and the side effect of increased torque, a sleeve made of a material with a smaller coefficient of friction is interposed between the heating roller and the sliding bearing to eliminate wear and prevent torque increase. ing. However, the technology described in this publication,
Since the bearing is in contact with the entire outer peripheral surface of the heating roller, there is a waste that heat from the heating roller escapes to outside through the bearing, which is contrary to the demand for energy saving. This is also true for the technique described in JP-A-8-240220. On the other hand, in the present invention, the frictional load is reduced by arranging the rolling bearing on the outer peripheral surface of the rotating shaft (heating roller) in a point contact state. In addition, since at least one or more rolling bearing outer periphery is point-contacted on the outer peripheral surface of the heating roller, escape of heat from the heating means can be reduced.

Japanese Patent Application Laid-Open No. 63-37065 discloses a technique for reducing friction and reducing load torque by using the outer periphery of an axial end of a heating roller as an inner ring of a rolling bearing. However, problems such as the necessity of processing (creation of grooves) on the outer periphery of the heating roller and the rolling element seizing due to heat from the heating roller may occur. Further, in the prior art in general, the outer periphery of the heating roller (rotating shaft) is supported by a bearing or the like over the entire periphery (since the inner periphery of the bearing and the outer peripheral surface of the heating roller are in sliding contact over the entire periphery). In addition, even when the pressure roller is separated from the heating roller, the heating roller cannot be detached from the fixing device (frame), and the maintenance workability and the assembling property are troublesome. Also,
According to the rolling mill roller disclosed in Japanese Patent No. 32883, a heating source and a porous material impregnated with an evaporable liquid are arranged inside the roller, and a uniform heat distribution is obtained by an evaporation-condensation action of the evaporable liquid. Is disclosed. However, in this conventional technique, the configuration of the roller itself is obviously complicated, which is disadvantageous in processing, production, and cost. In addition, there is a concern that the device may become dirty due to evaporation. On the other hand, in the present invention, the object is to reduce the friction and reduce the torque between the outer peripheral surface of the heating roller and the bearing, and to prevent the adhesion of foreign substances such as toner to the heating roller and the temperature unevenness of the heating roller. The purpose is.

[0005]

In order to achieve the above object,
According to a first aspect of the present invention, there is provided a fixing device including a heating roller having a heat source, a pressing roller that presses against an outer peripheral surface of the heating roller, and a frame that rotatably holds the heating roller. The surface is supported by one or more rolling bearings rotatably supported on the frame. According to a second aspect of the present invention, in the fixing device according to the first aspect, the rolling bearing for supporting the heating roller has an angle of 30 to 120 degrees centered on a straight line connecting the axis of the pressure roller and the axis of the heating roller. It is characterized by being arranged at predetermined intervals within the range of °. The invention of claim 3 is
A rolling bearing or a pressure roller that supports the heating roller is supported by a lid or lever supported by a frame of the fixing device, and the rolling bearing or the pressure roller is heated by rotating the lid or the lever. It is characterized in that it is configured to be able to contact and separate from the roller.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments shown in the drawings. FIG. 1 is a longitudinal sectional view of a fixing device according to an embodiment of the present invention. The fixing device includes a heating roller 2 and a pressure roller 3 in a frame (casing) 1.
And a rolling bearing 4 and the like that are in rolling contact with the outer periphery of the heating roller. The heating roller 2 having a heat generating means (heat source) inside or on its surface is rotatably supported on the outer peripheral surfaces at both ends in the axial direction by supporting holes provided in the side wall 1a of the frame 1, while being on the upper peripheral surface (shaft). (Both ends in the direction) are supported by the rolling bearing 4 and the lower peripheral surface is pressurized and supported by the pressure roller. The pressure roller 3 is rotatably supported on its shaft by a bearing or the like provided on the frame side wall 1a, and is pressed against the peripheral surface of the heating roller by a pressure spring or the like. A gear 10 is coaxially fixed to the outer periphery of one end in the axial direction of the heating roller located outside the frame side wall, and a gear 11 connected to a motor (not shown) is meshed with the gear 10. Drive rotationally.
One or a plurality of the rolling bearings 4 are arranged at predetermined circumferential intervals. Each rolling bearing 4 has a shaft 4A supported by the inner wall of the frame side wall 1a, and is rotatably supported by the shaft 4A. Conventionally, the heating roller 2 provided with a heat generating means is pressed in the direction of the arrow by the pressing roller 3, and when the pressure from the pressing roller 3 is applied, the heating roller 2 is pressed by a large frictional load generated between the two rollers. When rotating, a large torque is required. On the other hand, in the present invention, at least one or more rolling bearings 4 are arranged on the outer periphery of the heating roller in a point contact state in order to rotate the heating roller which receives a load from the pressure roller at the time of rotation with a little torque. The friction load is reduced, and the load on the driving means for rotating the heating roller is reduced. Further, since the rolling bearing is arranged on the outer periphery of the heating roller by point contact, it is not necessary to consider heat resistance of the rolling bearing so much, and it is possible to construct an inexpensive rolling bearing. Furthermore, since the rolling bearing only makes point contact with the peripheral surface of the heating roller, it hardly takes heat for fixing from the peripheral surface of the heating roller provided with the heating means,
It is also effective for energy saving of the heating means.

As described above, according to the embodiment of the present invention, at least one, preferably two or more rolling bearings are provided in a point contact state on the outer peripheral surface of the heating roller opposite to the pressure contact portion with the pressure roller. By arranging, the heating roller can be easily attached to and detached from the frame of the fixing device, and the assembling property and the maintenance property can be improved. Further, since the rolling bearing 4 is located on the outer peripheral surface of the heating roller, it is possible to use a small-diameter rolling bearing, which is advantageous in terms of cost, and enables downsizing of the fixing device. Further, since the outer peripheral surface of the rolling bearing is in point contact with the outer peripheral surface of the heated heating roller, it is advantageous for heat resistance, and there is an advantage that an inexpensive rolling bearing can be used. In addition, heat can be prevented from being dispersed through the rolling bearings, and the fixing efficiency can be maintained. In addition, since the heating roller is supported by rolling bearings, the frictional load during rotation of the heating roller can be reduced, and the load on the drive system that drives the fixing device can be reduced. Noise can be reduced.

Next, FIG. 2 is a schematic view showing an arrangement relationship between each roller and a rolling bearing according to an embodiment of the present invention. In this embodiment, two rolling bearings 4a, 4b a predetermined circumferential spacing, i.e. the center point of the pressure roller (axis) O ₂ from rolling bearings 4a, 4b center point of the (axis) O _3, O connecting to ₄ with respective connecting it straight L1, L2 angle θ of set to be 30 to 120 degrees, the center point O ₂ and the center point of the heating roller of the pressure roller and the (axis) O ₁ The distance from the straight line L3 to the center points O ₃ and O ₄ of the rolling bearings 4a and 4b is set to be equal. In other words, in other words, the angle θ can be said to be an angle that spreads left and right evenly around a straight line connecting the axis of the pressure roller and the axis of the heating roller. It is the present invention that one or two or more rolling bearings are arranged within the range.

In this example, since the two rolling bearings are arranged in a predetermined arrangement, it is advantageous in responding to sudden torque fluctuation. That is, as described above, placing at least one or more rolling bearings between the angle θ (30 ° ~120 °) around the straight line L3 connecting the pressing roller center O ₂ and the heating roller center O ₁ This is effective against a sudden change in torque (the position of the heating roller can be kept constant). The same effect can be obtained by arranging a plurality of rolling bearings such as three, four,... Between 30 ° and 120 °. In other words, it is necessary to keep the position of the heating roller constant at the time when the heating roller drive starts up or the torque fluctuates with time, which is a problem that has occurred when a conventional sliding bearing (particularly made of resin) is used. it can.

FIGS. 3 and 4 are diagrams showing the configuration and operation of another embodiment of the present invention. In each embodiment, the frame 1 of the fixing device comprises a frame body 20 and a lid 21. Is characteristic. The frame body 20 is a box body that rotatably supports the heating roller 2 and the heating roller 3 and has an open upper surface. The lid body 21 is pivotally supported by a hinge 22 to open and close the upper surface of the frame body 20. The rolling bearing 4 is rotatably supported on the lid 21. The lid 21 is held in a closed state by a fixing tool such as a screw 2. The frame body 20 has a support hole 25 rotatably supporting an outer peripheral surface of an axial end portion of the heating roller 2 on each of the front and rear side walls, and a support portion for pivotally supporting the shaft 3 a of the pressure roller 3. 26, and a lever 28 that rotates vertically about a shaft 27 to press the pressure roller 3 toward the heating roller 2, and a tension spring 29 that urges the lever 28 in the pressure direction. And Lid 21
The rolling bearing 4 is rotatably supported by a shaft 4A supported on the inner wall thereof. When the rolling bearing 4 is closed, the circumferential surface of the heating roller 2 pressed by the pressing roller 2 The surfaces are configured to make point contact. 4 differs from that of FIG. 3 only in that the means for pressing the pressure roller 3 is a compression spring.

As described above, in this embodiment, the cover 21 having one or more rolling bearings 4 is rotatably assembled to the frame main body 20 so that at least one or more rolling bearings 4 and a heating roller are provided. 2, and the positional relationship with the pressure roller 3 can be determined. By at least one or more rolling bearings 4 attached to the lid 21,
Since the heating roller and the pressure roller are positioned and held, the heating roller and the pressure roller can be easily attached to and detached from the frame and the rolling bearing by opening and closing the lid, thereby improving maintainability and assemblability.

FIG. 5 shows another embodiment. In this embodiment, the frame 35 has a structure without a cover, and the rolling bearing 4 is rotatably supported by a shaft 4A at an upper portion in the frame. The heating roller 2 pushed up by the pressure roller 3 is brought into contact with the heating roller 2 to support the heating roller. In this embodiment, the pressing force of the pressure roller 3 is obtained by vertically moving the shaft 27 as a fulcrum and pulling up and pressing the tip of a lever 28 supporting the shaft 3a of the pressure roller 3 at an intermediate position by a spring 29. By releasing the lever 28 as indicated by the dotted line and lowering the pressure roller, the heating roller 2 can be removed from the frame, and maintenance and assemblability can be improved. As described above, each of the embodiments shown in FIGS. 3 to 5 has a configuration in which the rolling bearing or the pressure roller supporting the heating roller can be easily opened and closed (separated from the heating roller). Assemblability and exchangeability are greatly improved.

[0013]

As described above, according to the first aspect of the present invention,
In a fixing device having a structure in which a pressing roller is pressed against the outer periphery of a heating roller, at least one, preferably two or more rolling bearings are point-contacted on the outer peripheral surface of the heating roller on the side opposite to the pressing portion with the pressing roller. By arranging in the state, the attachment and detachment of the heating roller to the frame of the fixing device becomes easy,
The assemblability and maintainability can be improved. In addition, rolling bearings
Since it is located on the outer peripheral surface of the heating roller, it is possible to use a small-diameter rolling bearing, which is advantageous in terms of cost, and makes it possible to reduce the size of the fixing device. Further, since the outer peripheral surface of the rolling bearing is in point contact with the outer peripheral surface of the heated heating roller, it is advantageous for heat resistance, and there is an advantage that an inexpensive rolling bearing can be used. In addition, heat can be prevented from being dispersed through the rolling bearings, and the fixing efficiency can be maintained. In addition, since the heating roller is supported by rolling bearings, the frictional load during rotation of the heating roller can be reduced, and the load on the drive system that drives the fixing device can be reduced. Noise can be reduced. According to the invention of claim 2, at least one or more rolling bearings are arranged within a range of an angle θ (30 ° to 120 °) about a straight line connecting the axis of the pressure roller and the axis of the heating roller. Therefore, the position of the heating roller can always be kept constant at the time of heating roller driving start-up or torque fluctuation over time, which is a problem that has occurred when a conventional sliding bearing (particularly made of resin) is used. . According to the third aspect of the present invention, since the rolling bearing or the pressure roller supporting the heating roller can be easily opened and closed (separated), the attachment and detachment of the heating roller is easy, and the assemblability and exchangeability are greatly improved. .

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a fixing device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating the principle of another embodiment of the present invention.

FIG. 3 is a configuration explanatory view of another embodiment of the present invention.

FIG. 4 is a configuration explanatory view of another embodiment of the present invention.

FIG. 5 is a configuration explanatory view of another embodiment of the present invention.

[Explanation of symbols]

1 frame (casing), 1a side wall, 2 heating roller, 3 pressure roller, 4 rolling bearing, 10 gear,
11 gears, 20 frame body, 21 lid, 22
Hinge, 25 support hole, 26 support, 27 axis, 28
lever,

Claims (3)

[Claims] 1. A fixing device comprising: a heating roller provided with a heat source; a pressure roller that presses against an outer peripheral surface of the heating roller; and a frame that rotatably holds the heating roller. A fixing device supported by at least one rolling bearing rotatably supported by the frame. 2. The fixing device according to claim 1, wherein
The rolling bearing that supports the heating roller has a 30 ° centering on a straight line connecting the axis of the pressure roller and the axis of the heating roller.
A fixing device, wherein the fixing devices are arranged at predetermined intervals within a range of about 120 °. 3. A rolling bearing or a pressure roller for supporting the heating roller is supported by a lid or lever rotatably supported by a frame of the fixing device, and is rotated by rotating the lid or lever. The fixing device according to claim 1, wherein the rolling bearing or the pressure roller is configured to be able to contact and separate from the heating roller.