JPH0588574A - Thermal roller fixing device - Google Patents

Abstract

PURPOSE:To attain reduction in a heat generation, a heat loss, and a cost by composing the pivotally supporting means of a fixing roller of a short rotary member circumscribed and driven on the outer periphery of the fixing roller on its end part, and a pressure roller. CONSTITUTION:The fixing roller 4 incorporating a heater 1 does not have squeezing processing on the end part of the roller 4, and is press-contacted to the pressure roller over the entire length. A supporting roller 6 are provided in such a manner that it is pivotally supported by a side plate so as to be circumscribed on the end part of the fixing roller 4, and driven-rotated to the rotation of the fixing roller 4. The supporting roller 6 is a stepped roller provided so that its stepped part is opposite to the end face of the fixing roller 4, to regulate a movement in a longitudinal direction. Thus, it is unnecessary that the end part of the fixing roller 4 has the squeeze-processing and a large- diameter spherical bearing is used, and the members of the supporting roller 6, etc., can be miniaturized. Further, a sliding area with the fixing roller 4 is reduced, and the heat generation and the heat loss are reduced without increasing driving torque, as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat roller fixing device for an electrophotographic image forming apparatus.

[0002]

2. Description of the Related Art As a fixing device of an image forming apparatus utilizing an electrophotographic process such as an electrophotographic copying machine, a laser printer, a facsimile, etc., as shown in FIG. 9 or FIG. Has a fixing roller 4 which is rotatably supported around a predetermined axis image by a driving source and is rotationally driven by a driving source through a driving gear 3, and an elastic body surface layer. A transfer paper, which is composed of a pressure roller 5 which is in pressure contact with the entire length and is driven to rotate, carries a transfer paper carrying an unfixed toner image through a nip portion between the fixing roller 4 and the pressure roller 5. A heat roller fixing device for fusing and fixing the toner image on the transfer paper surface is widely adopted.

As shown in FIGS. 9 and 10, the fixing roller 4 has a bearing 2 which is larger than the fixing roller 4 in order to accommodate the heater 1 therein. As the diameter of the bearing increases, the torque of the plain bearing increases, so the fixing roller 4 as shown in FIG.
The outer diameter of the position where the bearing 2 is set is reduced by drawing the end of the bearing 2, but the cost for this processing cannot be denied. When the outer diameter of the fixing roller 4 is small, as shown in FIG. 10, both ends of the fixing roller 4 are not subjected to a drawing process, and a main bearing having the outer diameter of the main portion of the fixing roller 4 is provided. However, in the case of high speed drive or large diameter to some extent, ball bearings must be used in order to avoid an increase in torque, and there was a problem that the cost would increase accordingly. .. In addition, when the shaft support has a large diameter, if a sliding bearing that slides over the entire circumference is used, the contact area becomes large in addition to the increase in torque, so heat is generated, and heat is generated, causing heat transfer to the surrounding parts. There was a problem that it had an influence and caused heat loss of the fixing roller.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems relating to the bearing of the shaft supporting portion of the fixing roller of the conventional heat roller fixing device, the present invention takes into consideration the processing cost associated with the drawing of both ends of the fixing roller. It is an object of the present invention to provide a heat roller fixing device capable of achieving a reduction in driving torque of a fixing unit and a reduction in heat loss without increasing the cost of the ball bearing and the cost of using a ball bearing.

[0005]

In the heat roller fixing device of the present invention, in order to solve the above problems, the shaft supporting means of the fixing roller has an outer periphery of the fixing roller at the end of the fixing roller. It is characterized in that it is constituted by a rotating member which is circumscribed on the surface and is driven to rotate, and a pressure roller.

[0006]

With the above-mentioned structure, the fixing roller is sufficient to rotatably pivot about a predetermined axis, but the sliding area with the fixing roller is very small. Also, heat generation and heat loss are reduced without increasing the torque.
Also, the fixing roller support member is much smaller than large-diameter slide bearings and ball bearings, and drawing work at the end of the fixing roller is unnecessary, contributing to a significant cost reduction. To do.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a diagram showing a general configuration of the present invention.
The fixing roller 4 incorporating the heater 1 is not drawn at its end, the pressure roller 5 is in pressure contact over its entire length, and the support roller 6 is fixed to the fixing roller 4. The end plate is rotatably supported by a side plate (not shown) so as to be circumscribed, and is rotated by the rotation of the fixing roller. Support roller 6
In the example of FIG. 1, a stepped roller 7 as shown in FIGS. 6 (a) and 6 (b) is provided, and the stepped portion 7a is provided so as to face the end surface of the fixing roller 4. It regulates the movement in the longitudinal direction. However, the support roller is not limited to this shape, and the roller 8 without steps as shown in FIGS. 7A and 7B and the holding frame as shown in FIGS. It may be the ball 9a held by 9b. Besides this,
Although not shown in the figure, it is also possible to partially slide and support with a special material such as an oil-impregnated plastic bearing material having a low frictional resistance. In order to rotatably support one end of the fixing roller 4 about a predetermined axis, the total number of the pressure roller and the rotating member should be at least three.

In the embodiment shown in FIG. 2, the shaft support means at one end of the fixing roller is composed of one pressure roller 5 and two support rollers 6, and the pressure roller is composed of two pressure rollers. 5 is a fixing roller 4
To be pressed by the pressing of the F _1, fixing roller - La 4 is positioned rotatably supported around the predetermined axis.

In the embodiment shown in FIG. 3, the shaft supporting means at one end of the fixing roller is composed of two pressure rollers 5 and two support rollers 6.
It is composed of and. These four rotating members are provided so as to circumscribe the outer peripheral surface of the fixing roller 4. Two
Since the pressure roller 5 of the book is pressed against the fixing roller 4 by the pressing force of F ₂ and F ₃ , respectively, and two nip portions are formed, the length of each nip portion is the pressure roller. Since the number of lines is one half and the pressing force may be small, there is an advantage that wrinkles can be prevented even when a laminated recording material such as an envelope is used as the transfer paper.

When two pressure rollers 5 are used, one support roller 6 may be used as shown in FIG.

In the embodiment shown in FIGS. 5A and 5B, one end of the fixing roller 4 is rotated around a predetermined axis by three supporting rollers 6 provided at intervals of 120 ° around the fixing roller 4. The pressure roller 5 is rotatably supported, and conditions can be set so that it is convenient for the pressure roller 5 to perform its original function regardless of the support of the fixing roller. It is possible.

[0013]

As described above, according to the present invention, the fixing roller is
There is no need to draw the end of the blade or use a large-diameter ball bearing, and the supporting roller and other members are small in size, which is effective for cost reduction and heat generated by the large sliding area. There is no heat loss and it contributes to energy saving.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a general configuration of the present invention.

FIG. 2 is a cross-sectional view showing the configuration of an example of the present invention.

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

FIG. 4 is a cross-sectional view showing the configuration of still another embodiment of the present invention.

5A and 5B are diagrams showing still another configuration of the present invention, in which FIG. 5A is a sectional view and FIG. 5B is a side view.

6A and 6B are views showing an example of a rotary member supporting a fixing roller, FIG. 6A is a side view, and FIG. 6B is a front view.

FIG. 7 is a view showing another example of a rotating member, (a) is a side view,
(B) is an end view.

8A and 8B are views showing still another example of the rotating member, wherein FIG. 8A is a side view and FIG. 8B is a front view.

FIG. 9 is a cross-sectional view showing an end of an example of a conventional heat roller fixing device.

FIG. 10 is a cross-sectional view showing an end portion of another example of the conventional heat roller fixing device.

[Explanation of symbols]

 1 Heater 3 Drive Gear 4 Fixing Roller 5 Pressurizing Roller 6 Support Roller (Rotating Member) 7, 8, 9 Other Rotating Members

Claims (6)

[Claims] 1. A fixing roller having a built-in heater, rotatably supported by a shaft supporting means around a predetermined axis, and rotationally driven by a driving source, and the fixing roller over substantially the entire length. A transfer paper, which has a pressure roller which is pressed and driven to rotate, and which carries an unfixed toner image, is passed between the fixing roller and the pressure roller to transfer the toner image to the transfer paper. In a heat roller fixing device of an image forming apparatus for fusing and fixing, the shaft supporting means of the fixing roller is driven by being circumscribed on the outer peripheral surface of the fixing roller at the end of the fixing roller. A fixing device comprising a rotating short rotating member and the above-mentioned pressure roller. 2. The fixing roller according to claim 1, wherein the shaft supporting means at each end of the fixing roller comprises two rotating members and one pressure roller. Fixing device. 3. The fixing device according to claim 1, wherein the shaft supporting means at each end of the fixing roller comprises two rotating members and two pressure rollers. apparatus. 4. The fixing device according to claim 1, wherein the shaft supporting means at each end of the fixing roller comprises one rotating member and two pressure rollers. apparatus. 5. The fixing device according to claim 1, wherein the shaft supporting means at each end of the fixing roller is composed of only three rotating members. 6. The sliding bearing material having a low frictional resistance, which is in sliding contact with a part of the outer peripheral surface of the fixing roller, is used instead of the rotating member. The fixing device according to the item.