JP3514342B2 - Fixing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device which is applied to a copying apparatus, a printer apparatus, a facsimile apparatus and the like and fixes an image on a recording sheet.

[0002]

2. Description of the Related Art A copying machine or the like is equipped with a fixing device for heating and pressing the recording paper on which the toner image is formed in order to fix the toner image on the recording paper.

As a fixing device of this type, an actual flat plate 2-126 is used.
There is one described in Japanese Patent No. 159. According to the description of this publication, since the bearings of the heating roller and the pressure roller have a half-divided structure, the bearings can be incorporated after the rollers, and the number of assembly steps can be shortened and the automated assembly can be simplified. Techniques such as being possible are disclosed.

FIG. 8 is a front view showing a cross section of a main part of a conventional fixing device, and FIG. 9 is a side view showing a side cross section of the fixing device shown in FIG. 8, where 1 is a heat generating roller and 2 is a heat generating roller 1. The pressure roller 3 in contact with the bearing 3 has a half structure for supporting the heat generating roller 1, 4 is a supporting member of the bearing 3, and 5 is a driving means of the heat generating roller 1. The pressure roller 2 is biased toward the heat generating roller 1 by a biasing means (not shown), and as a result, a nip portion is formed between the heat generating roller 1 and the pressure roller 2.

At the time of assembling, the pressure roller 2 is first attached to a frame (not shown), and then the heat roller 1 is attached.
After mounting the bearing 3 on the heat generating roller 1 and then assembling the support member 4, the main part of the fixing device is constructed.

[0006]

However, in the configuration shown in FIG. 8, the number of assembly steps can be shortened during manufacturing and the automated assembly can be simplified, but the bearing 3 is in an unstable state during maintenance. Therefore, it becomes very difficult to assemble the support member 4 to the bearing 3 by hand.

Further, since the bearing 3 is a relatively expensive member which is excellent in heat resistance, the bearing structure 3 contributes to the reduction of the material cost. However, the half-split structure makes it easier to deform under the influence of heat, and especially the bearing 3
Both ends of the heating roller 1 apply more pressure than necessary to the heating roller 1, and as a result, rotation of the heating roller 1 is hindered,
The linear velocity may change, and the image may be disturbed or jam may occur.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fixing device which solves such problems, shortens the number of assembly steps, simplifies automated assembly, and improves the workability of maintenance. And

[0009]

In order to solve the above-mentioned problems, the present invention provides a heat generating roller that rotates by receiving a driving force from a driving source, and a substantially half-structure having a cutout part. , A recess for supporting the heat roller so as to wrap it
A bearing having, and a support member for supporting the bearing,
In a fixing device for fixing a toner image transferred onto a recording material by heating the recording material by the heat generating roller, when the bearing is assembled to the supporting member, a part of the bearing and the A stopper for locking the part of the support member to restrict the movement of the bearing in a direction returning to the mounting direction of the bearing and preventing the bearing from dropping from the support member, the bearing or the The recess is provided in at least one of the supporting members.
With respect to the direction in which the part assembles the bearing to the support member
It is characterized by facing in the opposite direction .

Further, the bearing supports a portion of the outer circumference of the heat roller of 180 ° or more, and the shortest gap of the missing portion of the bearing is smaller than the diameter of the heat roller.

The heat generating roller is assembled to the bearing.
In a contact state, at least one end of the bearing is provided with a step portion or a concave portion on the surface facing the heat generating roller, and the distance from the step portion or the concave portion to the central axis of the heat generating roller is set to be smaller than the radius of the heat generating roller. It is also characterized by being set longer.

Further, the bearing is provided with an elastically deformable region capable of expanding the length of the shortest gap of the missing portion of the bearing to the same length as the outer diameter of the heat generating roller.

Further, it is characterized in that an arcuate surface or a planar surface is formed by deleting a corner of the shortest clearance portion of the missing portion of the bearing or the vicinity thereof.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In order to better understand the present invention, modes of embodiments for solving the problems, that is, embodiments will be described in detail below with reference to the drawings. The same members as those according to the conventional technique shown in FIG. 8 or 9 are designated by the same reference numerals, and detailed description thereof is omitted.

FIG. 1 is a plan view showing a cross section of an essential part of a first embodiment of the present invention, FIG. 2 is a side view showing a cross section of an essential part of the first embodiment of the present invention, and 6 is a bearing. , 7 are support members. In this first embodiment, instead of the bearing 3 and the support member 4 in the conventional technique shown in FIGS.
The bearing 6 and the support member 7 shown in FIG. 2 are provided.

The bearing 6 is composed of a half ring-shaped portion 6a in which a cylindrical ring-shaped member is divided into approximately half and a stop portion 6b extending from the central portion of the outer peripheral surface of the half ring-shaped portion 6a. Has been done. On a virtual straight line including this stop 6b,
The center of the half ring-shaped portion 6a forming the bearing 6 is included.
Further, a slit 6c is formed along the virtual straight line at the center of the stopper 6b, and the stopper 6b divides the stopper 6b into two plate-shaped elastic portions. Further, the tip of the stopper 6b is formed in a tapered shape, and the starting point of this taper is the hook 6d. That is, the stopper 6b is formed in an arrow shape.

The support member 7 has a semicircular recess 7a corresponding to the outer peripheral shape of the bearing 6 at a position for positioning and supporting the bearing 6, and a through hole 7 is formed in the center of the recess 7a.
equipped with b. Then, the stopper 6b is inserted into the through hole 7b, and the hook 6d is hooked on the outer surface of the support member 7, whereby the bearing 6 is fixed to the support member 7.

When constructing the apparatus, the heat roller 1 is supported by the bearing 6 by assembling the support member 7 to which the bearing 6 is previously attached to the assembly of the pressure roller 2 and the heat roller 1. Become so. At this time, the virtual straight line substantially coincides with the virtual straight line connecting the center of the pressure roller 2 and the center of the heat generating roller 1. As a result, since the bearing 6 is fixed to the support member 7 by the stopper 6b, it does not come off, and the support member 4 (see FIG. 8) is attached to the bearing 3 (see FIG. 8) previously assembled as in the conventional case. It can eliminate the difficult work of assembling.

FIG. 3 is a plan view showing a cross section of a main part of a second embodiment of the present invention, and 8 shows a bearing. The second embodiment is a bearing 6 in the first embodiment shown in FIGS.
Instead of the above, the bearing 8 shown in FIG. 3 is provided. The same members as the members according to the first embodiment shown in FIG. 1 or 2 are designated by the same reference numerals, and detailed description thereof is omitted.

The bearing 8 is a C-shaped half ring-shaped portion 8a in which a cylindrical ring-shaped member leaves a portion of 180 ° or more from the center.
And a stopper portion 8b extending from the central portion of the outer peripheral surface of the half ring portion 8a. Furthermore, at room temperature (20 ℃ ~
Under an environment of 25 ° C), the missing portion 8c of the half ring-shaped portion 8a
The shortest gap X is smaller than the diameter D of the heat generating roller 1. Note that the shape of the stopper 8b is the same as the shape of the stopper 6b (see FIG. 1) in the first embodiment, and thus the description thereof will be omitted.

By configuring the bearing 8 in this way,
The heat generating roller 1 is gripped by the bearing 8.
Therefore, by attaching the bearing 8 to the support member 7 and further assembling the heat generating roller 1 to the bearing 8, the support member 7 can be attached to the unit body on the pressure roller 2 side as an integrated unit body. As a result, it is possible to eliminate the difficult work of assembling the bearing 3 (see FIG. 8) to the unsupported heat-generating roller 1 during maintenance.

FIG. 4 is a plan view showing a cross section of the main part of the third embodiment of the present invention, and 10 shows a bearing. The third embodiment is a bearing 6 according to the first embodiment shown in FIGS.
Instead of the above, the bearing 10 shown in FIG. 4 is provided. The same members as the members according to the first embodiment shown in FIG. 1 or 2 are designated by the same reference numerals, and detailed description thereof is omitted.

FIG. 5 is a front view showing the structure of a bearing according to the third embodiment of the present invention, and FIG. 6 is an enlarged view of part A of FIG. Bearing 10 is a cylindrical ring-shaped member 180 ° from the center
It is composed of a C-shaped half ring-shaped portion 10a remaining the above-mentioned portion and a stop portion 10b extending from the central portion of the outer peripheral surface of the half ring-shaped portion 10a. The semi-ring portion 10a is formed by forming a step 10c at the end of the inner peripheral surface of the semi-ring portion 8a of the second embodiment, and further forming an arcuate curved surface 10e at the end of the step 10c , so-called chamfering. Is. Since the shape of the stopper 10b is the same as the shape of the stopper 6b (see FIG. 1) in the first embodiment, the description thereof will be omitted. Further, the end of the step 10c may be formed into a tapered surface.

The step 10c is located on the inner peripheral surface of the half ring-shaped portion 10a in the vicinity of positions A and B on a straight line including the diameter of the half ring-shaped portion 10a in the direction perpendicular to the direction in which the stopper 10b extends. It is a boundary. In addition, the missing portion 10d of the half ring-shaped portion 10a
The shortest gap X'of is configured to be shorter than the diameter D of the heat generating roller 1 in an environment of normal temperature (20 ° C to 25 ° C).

With this structure, when the heat generating roller 1 is assembled to the bearing 10, a gap Y is formed between the heat generating roller 1 and the inner peripheral surface of the bearing 10 in the region where the step 10c is formed. Become. Therefore, when both ends of the bearing 10 are tilted due to the influence of heat when the heat roller 1 is heated, the gap is reduced and the pressure applied to the heat roller 1 by the bearing 10 gripping the heat roller 1 is reduced. To do.
As a result, it is possible to prevent a linear velocity change, an image disturbance, a jam, and the like due to an increase in the rotation load on the heat generating roller 1. Also, by chamfering the end of the bearing 10,
The bearing 10 can be smoothly assembled to the heat-generating roller 1 without damaging the heat-generating roller 1 due to the corners.

In the third embodiment, the bearing
Since the degree of tilting of both ends of the bearing 10 due to the influence of heat varies depending on factors such as the shape, material, thickness, etc. of 10, the size of the gap Y may be appropriately set according to various conditions. Further, the range in which the step 10c is formed with respect to the bearing 10 can be appropriately set so as not to deviate from the original purpose of the bearing 10 that the heat roller 1 is supported without backlash. In addition, in the third embodiment, the bearing
Although the steps 10c are formed at both ends of the step 10, the steps 10c may be formed only at one of the ends, and the steps 10c may be formed on the inner and outer peripheral surfaces of the bearing 10 as shown in FIG. It is not necessary to form them on concentric circles, and as shown in FIG. 7, it is possible to form them in a concave shape to enhance elasticity. That is, a step or recess is formed on the facing surface so that the distance from the arbitrary position at the end of the bearing 10 to the surface facing the heating roller 1 to the central axis of the heating roller is longer than the radius of the heating roller. It should be provided.

Further, in the second and third embodiments,
In order to grip the heat generating roller 1, a certain length is required for both ends of the bearing.
In order to support the outer periphery of 0 ° or more, if the end of the bearing is too long, it may be necessary to assemble the bearing so that the heat-generating roller is passed from the side. Therefore, both ends of the bearing are provided with elasticity so that the shortest clearance of the missing part of the bearing can be expanded to the same length as the outer diameter of the heat generating roller within the elastic deformation region of the bearing. By setting the length, the assemblability can be further improved.

[0028]

According to the present invention configured as described above, the bearing can be assembled to the support member first, and the bearing can be attached to the heat-generating roller in a state where the stopper is hooked. Since the difficult work of assembling the support member to the bearing assembled to the heat roller is eliminated, the assembling work can be facilitated and the workability at the time of maintenance can be improved.

[Brief description of drawings]

FIG. 1 is a plan view showing a cross section of a main part of a first embodiment of the present invention.

FIG. 2 is a side view showing a cross section of a main part of the first embodiment of the present invention.

FIG. 3 is a plan view showing a cross section of a main part of a second embodiment of the present invention.

FIG. 4 is a plan view showing a cross section of a main part of a third embodiment of the present invention.

FIG. 5 is a front view showing a configuration of a bearing according to a third embodiment of the present invention.

FIG. 6 is an enlarged view of part A of FIG.

FIG. 7 is an enlarged front view of a main part showing another configuration of the bearing according to the third embodiment of the invention.

FIG. 8 is a front view showing a cross section of a main part of a conventional fixing device.

9 is a side view showing a side cross section of the fixing device of FIG.

[Explanation of symbols]

1 ... Heating roller, 2 ... Pressure roller, 3, 6, 8, 10
... Bearing, 4,7 ... Supporting member, 5 ... Driving means, 6
a, 8a, 10a ... Half-ring-shaped portion, 6b, 8b, 10b ... Stop portion, 6c ... Slit, 6d ... Hook portion, 7a ... Recessed portion,
7b ... through hole, 8c, 10d ... missing portion, 10c ... step, 10
e ... curved surface.

Claims (5)

(57) [Claims] 1. A heat-generating roller that rotates by receiving a driving force from a drive source, and a substantially half-structure having a partly lacking portion, and a concave portion that supports the heat-generating roller so as to wrap it. A fixing device that includes a bearing and a support member that supports the bearing, wherein the heat roller heats the recording material to fix the toner image transferred to the recording material on the recording material, When assembled to a support member, a part of the bearing and a part of the support member are locked to restrict movement of the bearing in a direction returning to the assembly direction of the bearing, and the bearing is At least one of the bearing and the support member is provided with a stopper for preventing the recess from falling off from the support member , and the recess is
Opposite to the direction in which the bearing is assembled to the support member
A fixing device characterized by being face-up . 2. The bearing according to claim 1, wherein the bearing supports a portion of the outer circumference of the heat roller of 180 ° or more, and the shortest gap of the missing portion of the bearing is smaller than the diameter of the heat roller. Fixing device. 3. A step portion or a concave portion is provided on a surface of the bearing facing the heat generating roller in at least one end of the bearing in a state where the heat generating roller is assembled to the bearing, and the heat generating roller is formed from the step portion or the concave portion. The fixing device according to claim 2, wherein the distance to the central axis of the fixing roller is set longer than the radius of the heat generating roller. 4. The bearing is provided with an elastic deformation region that allows the length of the shortest gap of the missing portion of the bearing to be extended to the same length as the outer diameter of the heat roller. Or the fixing device described in 3. 5. The fixing device according to claim 4, wherein the shortest gap portion of the missing portion of the bearing or a corner in the vicinity thereof is deleted to form an arc-shaped surface or a planar surface.