JPS63281182A - Fixing device - Google Patents

Abstract

PURPOSE:To stably supply a mold releasing agent to a fixing roller by providing a sheet member for controlling to supply the mold releasing agent to a nip part, so that it is pressed against the surface of the fixing roller, between a mold releasing agent applying device and the nip part. CONSTITUTION:To the lower face of a supporting body 13, the base part of a sheet member 20 having elasticity is attached by a fitting member 21, and a tip part 20A of the sheet member 20 is pressed against the surface of a fixing roller 1 at a position between a porous member 11 and a nip part 15. Before a recording material 30 is fed into the nip part, a mold releasing agent 40 which has oozed out of the porous member 11 and has collected moves toward the nip part 15 as the fixing roller 1 rotates, but is subjected to a control by the tip part 20A of the sheet member 20 on the way. In such a way, the mold releasing agent is supplied stably to the fixing roller.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is used in the field of fixing technology in electrophotographic copying devices, and is particularly applicable to the film thickness of the release agent formed on the surface of the fixing roller at the nip portion. The present invention relates to a fixing device that regulates

(Prior art and problems) A fixing device that includes a fixing port, a roller, and a pressure roller that rotates together with the roller while being in pressure contact with the fixing port, and causes a recording material having an unfixed image to pass through a nip between the two rollers and fix it under pressure. In the case of fixing, a release agent such as silicone oil is usually applied to the fixing roller in order to prevent unfixed toner from being offset to the front roller during fixing. For example, a release agent coating device is used to clean the roller surface by bringing felt or other porous coating material impregnated with the release agent into contact with the surface of the fixing roller to form a film layer of the release agent. I'm dealing with it.

In such a release agent applicator, the felt part is always in pressure contact with the fixing roller by a pressing spring, etc., so if the fixing roller is not used for a long period of time, the release agent impregnated in the felt part may be removed. The Ill type agent oozes out onto the surface of the fixing roller due to the pressing force of the pressing spring, and gradually accumulates between the surface of the fixing roller and the felt portion. When the fixing device is used in such a state, as the fixing roller and the pressure roller rotate, the release agent that has accumulated between the surface of the fixing roller and the felt part moves and becomes the pressure contact area between the fixing roller and the pressure roller. It will accumulate in the nip. At this time, when a recording material having an unfixed toner image enters the nip, the release agent accumulated in the nip adheres to the leading end of the recording material, causing a phenomenon called oil staining. There is a problem in that the GL type agent accumulated in the nip portion makes it unstable for the recording material to enter the nip portion, causing wrinkles in the recording material.

(Means for solving the problems) The present invention solves the problems of the above-mentioned conventional device,
It is an object of the present invention to provide a fixing device capable of forming a release agent film layer having a constant minimum necessary thickness in a nip portion.

The present invention aims to achieve the following objects.

In a pressure fixing device that includes a fixing roller and a pressure roller that rotates together with the fixing roller while being in pressure contact with the fixing roller, the recording material having an unfixed image is caused to pass through a nip between the two rollers and fixed under pressure. A regulating sheet member that is brought into contact with the fixing roller and controls the amount of release agent on the surface of the fixing roller reaching the nip section is pressed against the surface of the fixing roller at a position between the release agent supply device and the nip section. , consists of:

(Example) Hereinafter, the present invention will be described in detail based on the accompanying drawings.

In FIG. 1, 1 is a fixing roller, 2 is a pressure roller, and both rollers are supported so as to rotate in a pressed state.

A release agent coating device 1O, which also serves as a cleaner, is attached to the inner surface of the side wall of the upper frame 3 that surrounds the fixing roller 1 from above.

The above mold release agent coating equipment! ! lO is a support 13 fixed to the upper frame 3, in which a member 12 containing felt or other porous member 11 impregnated with a mold release agent such as silicone oil is housed.
It is guided and held slidably in the direction of the fixing roller l. A compression spring 14 is provided between the member 12 and the support body 13.
is present, and the porous member 11 is always pressed against the surface of the fixing roller 1 by a constant spring pressure.

An elastic sheet member 20 is provided on the lower surface of the support body 13.
The base portion of the sheet member 20 is attached by an attachment member 21, and the tip portion 20^ of the sheet member 20 is in contact with the surface of the fixing roller l at a position between the porous member 11 and the nip portion 15. This contact state is made such that the tip 20A extends in the forward direction of the rotational direction P of the fixing roller 1, but is not particularly limited to this form, and the tip is caught on the fixing roller 1. For example, even if the sheet member is oriented 20 degrees in the opposite direction to that in FIG. 1 as shown in FIG. 2, as long as the contact portion has a rounded shape, it will function in the same way as the one in FIG. 1.

When fixing is performed by passing the recording material 30 having an unfixed image through the nip portion 15 of the apparatus of this embodiment.

The release agent 40 that has oozed out from the porous member 11 and accumulated before the recording material 30 is fed into the nip section moves toward the nip section with the rotation of the fixing roller l. The film reaches the nip portion 15 with a constant minimum film thickness regulated by the tip portion 20A. Therefore, problems such as oil stains do not occur on the recording material 30.

The sheet member 20 thus restricts the movement of the release agent accumulated when the fixing roller is not rotating to the nip portion, and thus prevents the release agent from leaking from the edge of the sheet member. In order to do this, it is provided over almost the entire length of the fixing roller l in the axial direction, but for greater reliability, it is preferable to have a length that protrudes even slightly from the end of the fixing roller l.

It is preferable that the pressure of the sheet member 20 with the fixing roller 1 can be adjusted by adjusting the tightness of the mounting member 21 (not shown).

(Effects of the Invention) As described above, the present invention provides a structure in which a sheet member that is located between a release agent applicator and a nip portion and that regulates the supply of release agent to the nip portion is brought into pressure contact with the surface of the fixing roller. By providing this, it is possible to prevent a large amount of release agent from temporarily accumulating in the nip portion and to stably supply the release agent to the fixing roller. As a result, it is possible to eliminate so-called oil stains on the recording material, and also to ensure that the sheet member enters the nip portion in a stable manner at all times, thereby preventing paper wrinkles.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an apparatus according to an embodiment of the present invention, and FIG.
FIG. 3 is a partial view showing a modified example of the sheet member of the device. l...Fixing roller 2...Pressure roller IO...Type II agent coating device 15...
...Nip portion 20--Sheet member 30--Recording material patent applicant Canon Co., Ltd. agent Patent attorney Fujioka Keiyu 2 Figure 1

Claims (3)

[Claims] (1) In a pressure fixing device that includes a fixing roller and a pressure roller that rotates together with the fixing roller while being in pressure contact with the fixing roller, a recording material having an unfixed image is caused to pass through a nip between the two rollers and fixed under pressure, in which a release agent is supplied. The device is brought into contact with the fixing roller, and a regulating sheet member is placed between the release agent supply device and the nip portion to regulate the amount of release agent on the surface of the fixing roller that reaches the nip portion. A fixing device that is brought into pressure contact with the fixing device. (2) The fixing device according to claim (1), wherein the regulating sheet member extends in the forward direction of the rotation direction of the fixing roller. (3) The length of the regulating sheet member in the axial direction of the fixing roller is approximately the same as or longer than the length of the fixing roller.
The fixing device described in section 2).