JP2004110064A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten assembly-manhours, to simplify automatic assembly and to improve operability of maintenance. <P>SOLUTION: A bearing 10 having half ring-like parts 10a in shapes obtained by dividing a cylindrical ring-like member into almost halves supports an outer periphery of heating roller so that it is surrounded. The bearing 10 supports a part of not less than 180° at an outer periphery of the heating roller. The shortest gap of a lack part of the bearing 10 is made smaller than a diameter of the heating roller. Steps 10c are disposed in end parts of the bearing 10, and a distance from the steps 10c to a center axis of the heating roller is set to be longer than a radius of the heating roller. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a fixing device applied to a copying machine, a printer, a facsimile machine, and the like, for fixing an image on recording paper.

(2) In order to fix a toner image on a recording sheet, a copying machine or the like is provided with a fixing device for heating and pressing the recording sheet on which the toner image is formed.

定 着 As a fixing device of this type, there is a fixing device described in Japanese Patent Application Laid-Open Publication No. HEI 10-163191. According to the description in this publication, the bearings of the heating roller and the pressure roller are formed in half, so that the bearing can be incorporated after the roller, thereby reducing the number of assembling steps and simplifying automated assembly. There is disclosed a technology that can do so.

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

At the time of assembling, first, the pressure roller 2 is attached to a frame (not shown), then the heat roller 1 is attached, the bearing 3 is mounted on the heat roller 1, and then the support member 4 is attached. The part is composed.
JP-A-2-126159 Microfilm of Japanese Utility Model Application No. 2-7262 (Japanese Utility Model Application No. 3-98318)

However, the configuration shown in FIG. 8 can reduce the number of assembling steps and simplify the automated assembling at the time of manufacturing, but the bearing 3 is in an unstable state at the time of maintenance. The work of assembling the support member 4 with the support member 3 becomes very difficult.

Because the bearing 3 is a relatively expensive member having excellent heat resistance, its half-structure contributes to a reduction in material costs. However, the half-split structure tends to cause deformation due to the influence of heat. In particular, when both ends of the bearing 3 apply excessive pressure to the heat-generating roller 1, rotation of the heat-generating roller 1 is hindered. , The linear velocity changes, and image disturbance or jam may occur.

The object of the present invention is to provide a fixing device which solves such problems, reduces the number of assembling steps, simplifies automated assembling, and improves the workability of maintenance.

In order to achieve the above object, the present invention provides a heating roller that rotates by obtaining a driving force from a driving source, and a substantially half structure having a missing portion in a part thereof, so as to wrap the outer periphery of the heating roller. A fixing device for fixing the toner image transferred to the recording material on the recording material by heating the recording material with the heating roller, wherein the bearing is 180 ° or more on the outer periphery of the heating roller. The shortest gap of the missing part of the bearing is smaller than the diameter of the heat generating roller, and at least one end of the bearing is provided on a surface opposed to the heat generating roller in a state assembled to the bearing. The heating roller has a step or a recess, and a distance from the step or the recess to a central axis of the heat roller is longer than a radius of the heat roller.

軸 受 Further, the bearing is characterized in that the length of the shortest gap of the missing portion can be increased to the same length as the outer diameter of the heat roller by elastic deformation.

Further, 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.

According to the present invention, since the heat generating roller can be mounted on the bearing after the bearing is first mounted on the support member, it is difficult to mount the support member on the bearing mounted on the heat generating roller as in the related art. Therefore, assembling work can be facilitated and workability at the time of maintenance can be improved.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same members as those of the related art shown in FIG. 8 or 9 are denoted by the same reference numerals, and detailed description thereof is omitted.

First, prior to the description of the embodiment of the present invention, Reference Examples 1 and 2 will be described.

FIG. 1 is a plan view showing a cross section of a main part of Reference Example 1, FIG. 2 is a side view showing a cross section of a main part of Reference Example 1, 6 shows a bearing, and 7 shows a support member. In this reference example 1, a bearing 6 and a support member 7 shown in FIGS. 1 and 2 are provided in place of the bearing 3 and the support member 4 in the prior art shown in FIGS.

The bearing 6 is composed of a half ring-shaped portion 6a formed by dividing a cylindrical ring-shaped member into substantially half, and a stop portion 6b extending from the center of the outer peripheral surface of the half ring-shaped portion 6a. . The center of the semi-ring-shaped portion 6a constituting the bearing 6 is included on the virtual straight line including the stop portion 6b. A slit 6c is formed at the center of the stop 6b along the virtual straight line. The slit 6c divides the stop 6b into two plate-like elastic portions. Further, the tip of the stopper 6b is formed in a tapered shape, and a portion serving as a starting point of the taper is a hook 6d. That is, the stopper 6b is formed in an arrow shape.

The support member 7 has a semicircular concave portion 7a corresponding to the outer peripheral shape of the bearing 6 at a position where the bearing 6 is positioned and supported, and further has a through hole 7b at the center of the concave portion 7a. The bearing 6 is fixed to the support member 7 by inserting the stop 6b into the through hole 7b and hooking the hook 6d on the outer surface of the support member 7.

When the apparatus is constructed, a support member 7 to which a bearing 6 has been previously assembled is attached to a member assembled with the pressure roller 2 and the heat generation roller 1 so that the heat generation roller 1 is supported by the bearing 6. Become. At this time, the virtual straight line substantially coincides with a virtual straight line connecting the center of the pressure roller 2 and the center of the heat generating roller 1. As a result, the bearing 6 is fixed to the support member 7 by the stopper 6b, so that it does not come off, and the support member 4 (see FIG. 8) is attached to the previously assembled bearing 3 (see FIG. 8). The tedious work of assembling can be eliminated.

FIG. 3 is a plan view showing a cross section of a main part of Reference Example 2, and 8 indicates a bearing. In the second embodiment, a bearing 8 shown in FIG. 3 is provided instead of the bearing 6 in the first embodiment shown in FIGS. The same members as those of the first embodiment shown in FIG. 1 or FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

The bearing 8 includes a C-shaped semi-ring-shaped portion 8a having a cylindrical ring-shaped member remaining at least 180 ° from the center, and a stop portion 8b extending from the center of the outer peripheral surface of the half-ring-shaped portion 8a. It consists of: Further, in an environment of normal temperature (20 ° C. to 25 ° C.), the shortest gap X of the missing portion 8c of the half ring-shaped portion 8a is configured to be shorter 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 Reference Example 1, and a description thereof will be omitted.

発 熱 By configuring the bearing 8 in this manner, the heat generating roller 1 is gripped by the bearing 8. Therefore, by attaching the bearing 8 to the support member 7 and further attaching the heat generating roller 1 to the bearing 8, the support member 7 can be assembled to the unit body on the pressure roller 2 side as an integrated unit body. Thus, it is possible to eliminate the difficult operation 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 a main part of one embodiment of the present invention, and reference numeral 10 denotes a bearing. In this embodiment, a bearing 10 shown in FIG. 4 is provided instead of the bearing 6 in the reference example 1 shown in FIGS. The same members as those of the first embodiment shown in FIG. 1 or FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

5 is a front view showing the configuration of the bearing according to the present embodiment, and FIG. 6 is an enlarged view of a portion A in FIG. The bearing 10 has a C-shaped semi-ring-shaped portion 10a in which a cylindrical ring-shaped member is left 180 ° or more from the center, and a stop portion 10b extending from the center of the outer peripheral surface of the half-ring-shaped portion 10a. It consists of: The half ring-shaped portion 10a has a configuration in which a step 10c is provided at an end of the inner peripheral surface of the half ring-shaped portion 8a of Reference Example 2, and an arc-shaped curved surface 10e is formed at the end of the step 10c, so-called chamfering is performed. is there. The shape of the stopper 10b is the same as the shape of the stopper 6b (see FIG. 1) in the first embodiment, and a description thereof will be omitted. Further, the end of the step 10c may be formed in a tapered surface.

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

With this configuration, when the heat generating roller 1 is assembled to the bearing 10, a gap Y is generated between the heat generating roller 1 and the inner peripheral surface of the bearing 10 in a region where the step 10c is formed. Therefore, when both ends of the bearing 10 have fallen due to the heat effect when the heating roller 1 is heated, the gap is only reduced, and the pressure applied to the heating roller 1 by the bearing 10 gripping the heating roller 1 is reduced. I do. As a result, it is possible to prevent a change in linear velocity, image disturbance, jam, and the like due to an increase in the rotational load on the heat generating roller 1. Further, since the end of the bearing 10 is chamfered, the bearing 10 can be smoothly assembled to the heating roller 1 without damaging the heating roller 1 due to the corner of the bearing 10.

In the present embodiment, the degree of the inclination of the both ends of the bearing 10 due to the influence of heat is different due to factors such as the shape, material, thickness and the like of the bearing 10. Therefore, the size of the gap Y is appropriately determined according to various conditions. It is good to set. Also, 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, which supports the heat generating roller 1 without play. Further, in the present embodiment, the step 10c is formed at both ends of the bearing 10, but the step 10c may be formed at only one of the ends, and the step 10c is also formed as shown in FIG. It is not necessary to form a concentric circle with respect to the inner and outer peripheral surfaces of the bearing 10, but it may be formed in a concave shape as shown in FIG. That is, steps or recesses are formed in the facing surface so that the distance from an arbitrary position of the end of the bearing 10 to the surface facing the heating roller 1 to the center axis of the heating roller is longer than the radius of the heating roller. It should be provided.

Further, in the present embodiment, a certain length is required for both ends of the bearing in order to grip the heat generating roller 1. However, since the outer circumference of the heat generating roller 1 of 180 ° or more is supported, the end of the bearing is required. If the part is too long, it may be necessary to assemble the bearing so that the heat-generating roller passes through the bearing from the side. For this reason, both ends of the bearing are provided with elasticity or both ends of the bearing so that the shortest gap portion of the missing portion of the bearing can be expanded to the same length as the outer diameter of the heat roller within the elastic deformation region. By setting the length, the assemblability can be further improved.

The present invention can be applied to an electrophotographic apparatus such as a copying machine, a printer, a facsimile machine, etc., so that workability during maintenance of the fixing device can be improved.

FIG. 4 is a plan view showing a cross section of a main part of Reference Example 1. Side view showing a cross section of a main part of Reference Example 1. Plan view showing a cross section of a main part of Reference Example 2. The top view which shows the cross section of the principal part of one Embodiment of this invention. Front view showing the configuration of the bearing in the present embodiment Enlarged view of part A in FIG. Front view which expanded the principal part which shows the other structure of the bearing in this embodiment. Front view showing a cross section of a main part of a conventional fixing device 8 is a side view showing a side cross section of the fixing device of FIG.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Heat generation roller 2 Pressure roller 3,6,8,10 Bearing 4,7 Support member 5 Driving means 6a, 8a, 10a Half ring-shaped part 6b, 8b, 10b Stop part 6c Slit 6d Hook part 7a Recessed part 7b Through hole 8c , 10d missing part 10c step 10e curved surface

Claims (3)

A heating roller that rotates by obtaining a driving force from a driving source; and a bearing that has a substantially half structure having a cutout in a part and that supports the heating roller so as to wrap the outer circumference of the heating roller. In the fixing device for fixing the toner image transferred to the recording material on the recording material by heating the bearing, the bearing supports a portion of the outer periphery of the heat roller of 180 ° or more, and the shortest part of the missing portion of the bearing is supported. The gap is smaller than the diameter of the heating roller, and at least one end of the bearing has a step or a recess on a surface facing the heating roller in a state of being assembled to the bearing. A distance from the heating roller to a central axis of the heating roller is longer than a radius of the heating roller. The fixing device according to claim 1, wherein the bearing is capable of expanding the length of the shortest gap of the missing portion to the same length as the outer diameter of the heat roller by elastic deformation. 3. The fixing device according to claim 2, wherein the shortest gap portion of the missing portion of the bearing or a corner near the shortest gap portion is deleted to form an arcuate surface or a planar surface.

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