JPH09152800A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve productivity and the stability of a fixing operation by installing a heating roller and a pressure roller in a frame body at a distance capable of generating an initial load for pressurizing between the mutual rollers. SOLUTION: The heating roller 1 and the pressure roller 2 are installed in the frame body 3 at a distance capable of generating the initial load for pressurizing between the rollers. Compared with the conventional constitution that the pressure roller is pressed toward the heating roller from both end parts by a bearing equipped with a pair of coil springs, the complicated adjustment of the strength of each coil at attaching, the occurrence of a relief generated by the pressure roller and the influence of the lowering of a pressure force due to the deterioration, etc., of the coil spring are eliminated, then, the productivity and the stability of the fixing operation are improved. Then, the device may be provided with a pair of supporting arms erected on the frame body 3 toward the pressure roller 2, and with a U-shaped leading end part opening toward the pressure roller 2, and it is allowed to rotatably support the rotary shaft of the heating roller 1 from both ends.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device,
In particular, the present invention relates to a fixing device installed in an electrophotographic printing device.

[0002]

2. Description of the Related Art A conventional fixing device 50 is shown in FIG. The conventional example shown here is installed in an electrophotographic printing apparatus, and further, inside the printing apparatus, the toner image is arranged on the downstream side of the photosensitive drum D in the conveying direction of the recording paper P and the toner image is transferred onto the paper surface. The fixing device 50 for fixing the recorded recording sheet P is shown.

This conventional fixing device 50 has a heating roller 51 having a heat source 51A and a pressure roller 52 having elasticity.
And a frame 53 that holds these rollers 51 and 52 rotatably and in parallel, and at the time of fixing, the recording paper P having the toner image transferred onto the paper surface is heated by the heating roller 51.
It is heated by and the pressure is applied between the heating roller 51 and the pressure roller 52.

Therefore, in the conventional fixing device 50,
In order to apply pressure to the printing paper P, bearings 55 mounted on the frame body 53 via coil springs 54 are engaged with both ends of the rotation shaft of the pressure roller 52, and each coil spring 54 has a frame shape. It is provided in a state of pressing the pressure roller 52 from the body 53 toward the heating roller 51.

[0005]

However, in the above-mentioned conventional example, as described above, each bearing which engages with both ends of the rotary shaft of the pressure roller is individually mounted on the frame body via the coil spring. Since the pressing state of the pressure roller to the heating roller side is formed by doing so, if the two coil springs do not generate the pressing force evenly, the balance at both ends of the rotating shaft of the pressure roller becomes poor, It has a disadvantage that fixing cannot be performed uniformly.

For this reason, adjustment in mounting the two coil springs has been indispensable.

Further, since the pressure roller is configured to press against the heating roller side, there is a possibility that the pressure roller may escape from the state of contacting the heating roller depending on the magnitude of the pressing force (for example, FIG. 2). Therefore, it is necessary to adjust the spring constants of both coil springs.

Further, the coil springs normally press the pressure roller by elastic force due to elastic deformation, but if the contracted state continues as the number of printed sheets increases, plastic deformation or deterioration occurs. , Its pressing force decreases,
There is an inconvenience that the fixed fixing performance cannot be maintained.

Further, in the above-mentioned conventional example, a pair of coil springs and bearings are indispensable, and there is a disadvantage that the economical efficiency is deteriorated due to the parts cost of each of these parts and the mounting cost due to the above adjustments.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the disadvantages of the conventional example, eliminate complicated adjustment of each part, and provide a fixing device with high productivity.

[0011]

According to a first aspect of the present invention, a heating roller having a heat source, a pressure roller having elasticity for contacting the outer peripheral surfaces of the heating roller with each other, and each of these rollers are rotatable. And a frame body that holds them in parallel.

The frame is equipped with a heating roller and a pressure roller with a distance between them that produces an initial pressure load.

In the case of each of the above-mentioned constitutions, for example, when the unfixed toner adheres to the recording paper and is conveyed between the pressure roller and the heating roller, an initial pressing load is preliminarily applied between the rollers. Since they are in contact with each other in a generated state, they are heated and pressed by the heat generated from the heat source of the heating roller, and the toner is fixed on the recording sheet.

According to a second aspect of the present invention, a structure is provided which is similar to that of the first aspect of the present invention, and the frame body supports the pressure roller individually at both ends of the rotary shaft of the pressure roller. Of the supporting arms, and the tips of each of the supporting arms are formed in a U shape facing the heating roller side, and the rotation axis of the pressure roller is engaged with the U-shaped tips. I am letting you.

Similarly to the structure of the first aspect of the present invention, when the unfixed toner adheres to the recording sheet and is conveyed between the pressure roller and the heating roller, the space between the rollers is preliminarily set to the initial pressure. Since they are in contact with each other with a load, they are heated and pressed by the heat generated from the heat source of the heating roller,
The toner is fixed on the recording paper.

According to a third aspect of the present invention, a structure is provided which is similar to that of the first aspect of the present invention, and the frame body supports the heating roller individually at both ends of the rotary shaft of the heating roller. The support arms are held via arms, and the tips of the respective support arms are formed in a U-shape facing the pressure roller side, and the rotary shaft of the heating roller is engaged with the U-shape tips. There is.

Similarly to the structure of the first aspect of the present invention, when the unfixed toner adheres to the recording sheet and is conveyed between the pressure roller and the heating roller, the space between the rollers is preliminarily set for the initial pressure. Since they are in contact with each other with a load, they are heated and pressed by the heat generated from the heat source of the heating roller,
The toner is fixed on the recording paper.

The present invention is intended to achieve the above-mentioned object by each of the above configurations.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. In this embodiment, the electrophotographic printing apparatus is equipped with the toner image, which is arranged downstream of the photosensitive drum D and the transfer roller R in the conveyance direction of the recording paper P and the toner image is transferred onto the paper surface in the printing apparatus. The fixing device 10 for fixing the recording sheet P thus formed is shown.

The fixing device 10 includes a heating roller 1 having a heat source 1A, a pressure roller 2 having elasticity so that the outer peripheral surfaces of the heating roller 1 are in contact with each other, and the rollers 1,
And a frame body 3 for holding 2 in a rotatable and parallel manner.

The heating roller 1 is composed of a roller main body 1B, which is a hollow cylindrical member, and a heat source 1A disposed substantially at the center of the inside of the roller main body 1B.
A rotary shaft that engages with the frame body 3 is formed at both outer ends of the roller body 1B (not shown). The rotating shaft is rotatably held by engaging with a fitting hole (not shown) of the frame body 3. In addition, the wiring of the heat source 1A is connected to the printing apparatus side via the rotating shaft, and the heating roller 1 is rotated by a driving unit disposed in the vicinity of the fixing apparatus 10 inside the printing apparatus. Energized.

On the other hand, the pressure roller 2 is in contact with the heating roller 1 and has a soft elastic body (for example, heat-resistant rubber, synthetic resin, etc.) whose outer peripheral portion has some elasticity, and a rotation arranged at the center thereof. It is composed of a shaft 2A and contacts the heating roller 1 while maintaining a constant surface contact.

Further, the pressure roller 2 has a rotating shaft 2A.
Both ends of each are individually held by a pair of support arms 4 provided on the frame body 3. That is, each of the support arms 4 is vertically provided from the frame body 3 toward the heating roller 1 side, and a tip portion 4A thereof is formed in a U-shape that opens toward the heating roller 1 side. The rotating shaft 2A of the pressure roller 2 is engaged with the tip 4A.

Here, the shape of the tip portion 4A will be described more specifically. The tip portion 4A is a semi-circular cutout having a diameter substantially the same as that of the rotary shaft 2A of the pressure roller 2. Has been formed. For this reason, since the tip end portion 4A abuts on the rotary shaft 2A of the pressure roller 2 at the entire cutout portion, the installation surface pressure becomes smaller and the sliding friction generated is reduced, and the pressure roller 2 becomes a support arm. It is possible to smoothly rotate with the rotation of the heating roller 1 while being held by 4A.

The tip portion 4A of the support arm 4 is
Since it is not a circular hole but a semicircular cutout, the rotary shaft 2A of the pressure roller 2 can be attached to and detached from the frame body 3. That is, since the front end portion 4A is open to the heating roller 1 side, in the normal mounting state, the pressure roller 2 is caused by the reaction force due to the contact generated on the side opposite to the heating roller 1. The tip 4A is not inadvertently detached from the tip portion 4A and is held well.

When a paper jam occurs in the fixing device 10 or the pressure roller 2 is deteriorated or damaged, the outer peripheral portion of the pressure roller 2 is made of an elastic material. The pressure roller 2 can be removed from the frame body 3 by pulling it toward the heating roller 1.

Further, the length of the support arm 4 in the vertical direction in FIG. 1 is set to a predetermined length. That is,
With the pressure roller 2 mounted on the support arm 4,
The lengths are set so that the axial distance between both the pressure roller 2 and the heating roller 1 becomes somewhat smaller than the total of the radii of both the pressure roller 2 and the heating roller 1.

As a result, the heating roller 1 and the pressure roller 2
And are mounted on the frame body 3 in a state where an initial load for pressurization is generated between them.

The fixing operation of this embodiment will be described.

First, in a state in which the unfixed toner T is transferred onto the recording paper P by the photosensitive drum D and the transfer roller R, the heating roller 1 and the pressure roller 2 of the fixing device 10 are transferred through a conveying means (not shown). It is transported to the contact part.

At this time, the heat source 1A of the heating roller 1 is in a heat-generating state in advance, and the heating roller 1 and the pressure roller 2 are in contact with each other in a state where an initial load for pressure is generated, so that the roller body The recording paper P is heated via 1B and pressed against the rollers 1 and 2, so that the unfixed toner T is fixed on the surface of the recording paper P.

In this embodiment, as described above, since the heating roller 1 and the pressure roller 2 are mounted on the frame body 3 at a distance between them, which produces an initial load for pressing, the conventional structure is different from the conventional one. In addition, compared with the structure in which the pressure roller is pressed from both ends to the heating roller side by the bearing equipped with a pair of coil springs, complicated adjustment of strength of each coil spring at the time of mounting and occurrence of escape occurring in the pressure roller , And the influence of the reduction of the pressing force due to the deterioration of the coil spring can be eliminated, and the productivity can be improved and the fixing operation can be stabilized.

Here, a pair of support arms is provided which is erected from the frame 3 to the pressure roller 2 side and has a U-shaped tip portion whose tip is open to the pressure roller 2 side. The heating shaft of the heating roller 1 may be rotatably supported from both ends.

In such a case, the wiring of the heat source 1A connected to the printing apparatus side from the rotary shaft of the heating roller 1 and the engaging portion with the driving means for urging the rotational operation are also detachable, so that the heating roller is No. 1 can also be made detachable, and the same effect as that of the pressure roller 2 can be obtained when replacing the heating roller.

Each of the support arms 4 described above may be formed of a material having elasticity. Accordingly, when the axes of the heating roller 1 and the pressure roller 2 are arranged so as to be smaller than the total of the radii of each other, the elastic force when each support arm bends causes the rollers to press each other for the initial pressure. It becomes possible to generate a load.

The frame 3 described above may be composed of two parts, that is, the heating roller 1 side and the pressure roller 2 side, and these parts may be detachably formed (in the vertical direction in FIG. 1). As a result, the fixing device 10 can be easily assembled at the time of production, and the above heating roller 1 and the pressure roller 2 can be easily replaced.

In this case, it is more preferable to provide a holding member for maintaining a distance between the axes of the heating roller 1 and the pressure roller 2 at which mutual initial pressure loads are generated when the frame body 3 is combined.

[0038]

According to the first aspect of the present invention, since the heating roller and the pressure roller are mounted on the frame body at a distance between the heating roller and the pressure roller, which produces an initial load for pressure application, as in the prior art,
Compared with the structure in which the pressure roller is pressed from both ends to the heating roller by the bearing equipped with a pair of coil springs, complicated adjustment of the strength of each coil spring at the time of mounting,
It is possible to eliminate the effects of the escape occurring in the pressure roller and the influence of the decrease in the pressing force due to the deterioration of the coil spring,
It is possible to improve productivity and stabilize the fixing operation.

Further, according to the present invention, it is possible to reduce the number of parts such as the pair of coil springs and the bearings, thereby improving the productivity in terms of parts cost.

According to the second aspect of the present invention, the same effect as that of the first aspect of the present invention is obtained, and the frame body is provided with a pair of support arms each having a U-shaped tip end portion facing the heating roller. As a result, since both ends of the rotary shaft of the pressure roller are individually supported, the pressure roller can be freely attached to and detached from the frame body. For example, paper jam between the heating roller and the pressure roller. When the pressure roller is deteriorated, or the pressure roller is deteriorated or damaged, it is possible to remove the pressure roller from the frame and clear the paper jam or replace the pressure roller. .

According to the third aspect of the present invention, the same effect as that of the first aspect of the present invention is obtained, and the frame body is provided with a pair of support arms having a U-shaped end portion facing the heating roller. As a result, since both ends of the rotary shaft of the heating roller are individually supported, the heating roller can be freely attached to and detached from the frame body, and paper jamming can be performed in the same manner as in the invention according to claim 2. Can be eliminated or the heating roller can be replaced.

According to the present invention, it is possible to provide an unprecedented excellent fixing device configured and functioning as described above.

[Brief description of the drawings]

FIG. 1 is a partially cutaway schematic explanatory view of an embodiment of the present invention.

FIG. 2 is a partially cutaway schematic explanatory view showing a conventional example.

[Explanation of symbols]

 1 Heating Roller 1A Heat Source 2 Pressure Roller 2A Rotating Shaft 3 Frame 4 Support Arm 4A Tip Part 10 Fixing Device

Claims (3)

[Claims] 1. A fixing device comprising: a heating roller provided with a heat source; a pressure roller provided with elasticity, the outer peripheral surfaces of which are in contact with the heating roller; and a frame body for holding these rollers rotatably and in parallel. In the apparatus, the frame is equipped with the heating roller and the pressure roller with a distance between them that produces an initial pressure load. 2. The frame body holds the pressure roller via a pair of support arms that individually support both ends of a rotary shaft of the pressure roller, and the tip end of each of the support arms is 2. The fixing device according to claim 1, wherein the fixing device is formed in a U shape facing the heating roller side, and a rotary shaft of the pressure roller is engaged with a tip end portion of the U shape. 3. The frame body holds the heating roller via a pair of support arms that individually support both ends of a rotary shaft of the heating roller, and the tip end of each of the support arms is connected to the heating arm. 2. The fixing device according to claim 1, wherein the fixing device is formed in a U-shape facing the pressure roller, and a rotary shaft of the heating roller is engaged with a tip end of the U-shape.