JPS6190180A - Heat roll fixing device - Google Patents

Abstract

PURPOSE:To attain a required nip width without requiring a large space by forming a heat roll and a press-fixing roll to elastically deformable thin cylinders and deforming elastically thin cylinders with plural guide members arranged on the inside or the outside of these roll. CONSTITUTION:Each of a heat roll 1 and a press-fixing roll 2 consisting of elastically deformable thin cylinders is attached to a pair of upper and lower guide members 3 so that it is circumscribed to them, and the gap between pairs of guide members 3 is set properly to deform elastically rolls 1 and 2 in the state where their outside peripheral surfaces are pressed to each other. Consequently, the press-contacting surface between rolls 1 and 2 has a considerably large area in comparison with the case where rolls 1 are pressed to each other with cylindrical shapes, and a nip width 4 effective for the fixing action is formed. Thus, the required nip width is obtained by guide members requiring no large spaces, and the device is made small-sized and low-cost.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention uses a thin heating roller and a pressure roller in an elastically deformed state, thereby reducing the warming-up time. The present invention relates to a roller fixing device.

[Prior art]

Various methods are known for heating and fixing a toner image formed on a recording medium in an electrostatic recording device such as an electrophotographic copying machine or a facsimile IJ. The currently widely used fixing methods can be roughly divided into non-contact fixing methods, in which toner is heated and fixed using radiant energy such as infrared rays, and non-contact fixing methods, in which a heating member is brought into contact with a recording medium carrying unfixed toner, and conductive fixing methods from the heating member are used. There is a contact fixing method that uses heat to heat and fix toner.

As a fixing device using the latter method, a heat roller type fixing device is generally known and consists of a rotatable heating roller with a built-in heater and a rotating pressure roller that is in pressure contact with the heating roller, and has been widely put into practical use. has been done. This contact fixing method has advantages such as high thermal efficiency, low power consumption, and high-speed fixing, so it has recently been widely adopted in conjunction with the demand for faster recording devices. There is.

On the other hand, after the heater of the heating roller is energized, the surface temperature of the heating roller reaches a temperature f&(150"0 to 18") suitable for fixing.
The disadvantage is that it takes a long time (so-called warming-up time) to rise to 0°0.

Conventionally, as an attempt to shorten this warming-up time, it has not been possible to reduce the warming-up time to one minute by increasing the power of the heater and reducing the thickness of the heating roller to lower the heat capacity. However, since there is a limit to the power consumption of the recording device (for example, 1.5 KW or less), there is a limit to the power consumption that can be used for fusing.
Further, reducing the wall thickness causes problems such as the heating roller being deformed due to mechanical external force exerted by the pressing roller being pressed against the heating roller with a load exceeding a certain level. For example, a method is to use sponge rubber with low hardness for the pressure roller to create a large nip width between the heating roller and the pressure roller even though the pressure force is small, thereby reducing the thickness of the roller while maintaining fixing performance. However, in this case, if the heating roller is kept in pressure contact with the pressure roller for a long period of time and kept at the fixing temperature, the sponge p
- There is a problem in that the rubber causes permanent deformation.

Furthermore, when the wall thickness of a conventional heating roller is made extremely thin, there is a large difference in hardness between the two 7-run sections at both ends of the roller and the micrometer-deep center section, and the nip width becomes uneven in the length direction of the roller. There was also the problem of.

In view of the above points, the present inventor first constructed a heating roller and a pressure roller using a thin cylinder that can be elastically deformed and a support member that supports both end receiving parts of this cylinder so that they can be elastically deformed. A method for configuring this is proposed in Japanese Patent Application No. 56-73514.

However, as explained in the above proposal, it is necessary to provide a pressure roller on the circumferential surface of the heating roller and the pressure roller that faces the pressure contact surface of the heating roller and the pressure roller, respectively, in order to form a nip width. In addition to the heating roller and pressure roller, a support frame for holding the pressure roller is also required, making it extremely difficult to apply it to a fixing device with a small space.

[Problems to be Solved by the Invention] The present invention improves the conventional suppression method for elastically deforming a thin-walled cylinder used in a pair of heat rollers, which requires large-scale folding and a large space. The objective is to obtain a required nip width using a guide member that is highly durable and takes up little space.

[Means for solving problems]

In the present invention, a plurality of shed guide members are disposed at positions that press against the outer peripheral surface or the inner peripheral surface of a thin-walled cylinder, and the guide members elastically deform the thin-walled cylinder to provide a nip width to a pair of heat rollers. It is configured to form a
In a fixing device having a rotatable heating roller and a pressure roller that rotates in pressure contact with the heating roller, each of the rollers is an elastically deformable thin cylinder, and a guide member is provided inside or outside of each roller. This is achieved by a heat roller fixing device characterized in that the roller maintains a deformed and pressed state.

〔Example〕

Embodiments according to the present invention are shown in FIGS. 1 and 2.

Although the heating roller 1 and the pressure roller 2 in this embodiment are made with exactly the same structure, the case of the heating roller 1 will be explained below.

The heating roller 1 is made by coating the outer peripheral surface of a cylindrical metal roll with a thickness of about 0.5 wN with 2727 layers to improve the separability of toner. It has the property of being able to deform into an elliptical shape as shown in the figure within the elastic limit.

When the heating roller 1 and the pressure roller 2 are mounted so as to be in circumscribed contact with a pair of upper and lower guide members 3, respectively, installed between a substrate (not shown) of the fixing device, the mutual spacing between the guide members 3 can be set appropriately. By doing this, the heating roller 1 and the pressure roller 2 are deformed by pressing their outer circumferential surfaces against each other, so that an oval shape is obtained as shown in the figure.

In this state, the pressure contact surface between the heat roller 1 and the pressure roller 2 has a much larger pressure contact area than when they are in cylindrical shape, so that the pressure contact area between the heating roller 1 and the pressure roller 2 is much larger than that in the case where they are in contact with each other in a cylindrical shape. This will form a nip@4.

Therefore, when the heat roller 1 is heated to a temperature necessary for fixing by the heat roller 7 contained therein, and is driven by the rotation of the friction roller 5 inscribed therein and the sandwiching between the driven roller 6 and the driven roller 6 in pressure contact therewith, the heating roller 1 is heated to the temperature necessary for fixing. The transfer paper is held between the wide nip width 4 formed at the pressure contact portion with the roller 2, and the toner image is welded to perform a sufficient fixing action. At the same time, the transfer paper is reliably conveyed to the paper ejection port. 0 As described above, in the heat roller fixing device of the present invention, there is no need to provide a flange member to the metal plate.
It is possible to form a sufficiently large nip width between a pair of heat rollers by simply arranging a few simple guide members, and it is possible to form a sufficiently large nip width between a pair of heat rollers. It is no longer used.

Note that if the guide member 3 is configured as a roller member so that it can be driven to rotate, the frictional resistance with the inner circumferential surfaces of the heating roller 1 and the pressure roller 2 is reduced, and the driving force of the friction roller 5 is transmitted more efficiently. Become so.

In FIGS. 2 fa) and ib), the heating roller 1 is
The pressure rollers 2 are each elastically deformed into an elliptical shape, and the pressure rollers 2 shown in FIGS. Further, FIG. 1d) shows an example in which these guide members work together, and in this case, one of the guide members 63b has a structure in which one elastically presses against the other. is taken.

Since the guide members 33, 43, 53 and 63b all maintain surface contact with the circumferential surface, there is no need to provide them over the entire length of the heat roller pair; If it has, it can sufficiently maintain the 70 circumferential surface in an elliptical shape.

〔Effect of the invention〕

The present invention makes it possible to form a desired nip width in a pair of heat rollers constituted by a thin-walled cylinder by simply using a guide member that does not require space, and as a result,
Kogyo now offers an inexpensive and more durable heat roller fusing device.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a main part of a Phμm fixing device according to the present invention. FIG. M2 is a conceptual diagram showing the arrangement of various guide members in the device. l...heating roller 2...pressing roller 3,
13.23.33.43.53.63a, 63b-guide member 4...nip 41W5...is's, =-ra 6
...Followed roller 7.Heater agent Patent attorney
Field 1) Father-in-law Figure 2 (d)

Claims (1)

[Claims] In a fixing device that includes a rotatable heating roller and a pressure roller that rotates in pressure contact with the heating roller, at least the heating roller of the rollers is an elastically deformable thin cylinder, and a guide member is provided inside or outside of each roller. A heat roller fixing device characterized in that the heat roller is maintained in a deformed pressure contact state with the pressure roller by the guide roller.