JPS6360475A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent a release agent from overflowing from an oil pan, and also, to always uniformly apply the release agent to a fixing roller without being influenced by a variation of a liquid level height and an inclination of an image forming device body, by providing a release agent impregnating member such as felt, etc., in the oil pan. CONSTITUTION:An impregnating member 4 consisting of felt, etc., which has been placed in an oil pan P so as to surround the lower face of a draw roller 1 is impregnated with silicone oil O in the oil pan P, and always contact the outside peripheral surface of the lower part of the draw roller 1. Accordingly, as for the silicone oil, its greater part contacts the draw roller 1 in a state that the impregnating member 4 has been impregnated therewith, therefore, even if the draw roller 1 and an applying roller 2 rotate in order to apply the silicone oil to a fixing roller, it does not occur that the silicone oil is drawn up abundantly onto the draw roller 1 due to a flow resistance by the impregnating member 4, and an overflow of the oil does not occur. Also, a variation of a liquid level height h3 of the silicone oil, which follows up a rotation of both the rollers 1, 2 does not occur, therefore, the quantity of application to the fixing roller 3 can always be kept constant.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Purpose of Light January [Field of Industrial Application] The present invention relates to a fixing device used in an image forming device such as an electrophotographic copying device or an electrostatic recording device.

More specifically, transfer paper - electrostatic recording paper,
It has a roller that fixes an unfixed toner image formed on a member such as paper (hereinafter referred to as a transfer material), and a release agent such as silicone oil is applied to the roller to prevent the toner from being offset to the fixing roller. The present invention relates to a fixing device that applies an agent.

[Conventional technology]

Conventionally, fixing devices that apply a #type agent (hereinafter referred to as oil) such as silicone oil to the fixing roller have either applied oil to the fixing roller using felt, or pumped up the oil with felt and fixed it via the application roller. Products that are applied to rollers have been put to practical use. However, when using felt to supply oil to the fixing roller or applicator roller as described above, the amount of oil supplied becomes uneven due to the surface roughness and dirt of the felt. Streaks remained on the transfer material, damaging the image.

In order to eliminate this oil streak, a fixing device has been proposed that uses a pumping roller to pump up silicone oil, as shown in FIG. That is, in the figure, P is silicone oil 0
1 is a pumping roller immersed in oil 0 in the oil pan P, 2 is a pumping roller that stores a mold release agent such as
The application roller 3Φ3a, which is in constant contact with the troller l, is a fixing roller. The roller 1112 is rotationally driven in the direction of the arrow in the figure by a drive source (not shown) to pump up the silicone oil 0 in the oil pan P. Also, application roller 2
The drawing roller 1 is rotated back and forth around the axis 11 of the pumping roller 1 by a drive source (not shown) to approach and separate from the fixing roller 3, and is normally located at the chain line position in the figure, where the transfer material enters the fixing device. At this time, the application roller 2 comes into contact with the fixing roller 3, and the silicone oil O is applied to the fixing roller 3.

[Problem that the invention seeks to solve]

However, the fixing device as described above also has the following problems.

The first problem is that silicone oil O overflows from the oil pan P. That is, when the viscosity of the silicone oil 0 is high, as the pumping roller rotates, the silicone oil 0 is pumped up onto the roller l- in a large amount. This silicone oil 0 is pumped up, blocked at the nip between the troller 1 and the application roller 2, and flows back. In this case, if the gap between the pumping roller 1 and the wall surface P1 of the oil pan P is small, some of the silicone oil that has flowed back cannot pass through this gap, gradually forming an oil pool, and finally ending up in the oil pan. It has the disadvantage that it overflows over the wall surface P of P. In addition, the level of the silicone oil in the oil pan P is kept constant by means such as chicken feed in order to keep the oil applied to the fixing roller 3 constant. The rotation of the pumping roller 1 causes the silicone oil to flow into the pumping roller 1 as shown in the figure.
When the oil is pumped upward, the level of the oil in the oil pan P decreases, so silicone oil is replenished from an external oil tank (not shown in the figure) or the like. For this reason, oil pan P
More silicone oil than originally set is supplied to the fixing roller 3, which causes fluctuations in the amount of silicone oil applied to the fixing roller 3 and causes the above-mentioned silicone oil smearing.

In order to solve the problem of oil spills caused by pumping up silicone oil due to the rotation of the rollers, the height of the wall surface P of the oil pan P should be made sufficiently high.
In the fixing device shown in FIG. 2, there is a limit to the height of this wall surface, and it is not possible to completely prevent silicone oil from spilling. If the gap is made sufficiently large, oil overflow will not occur, but the oil pan P itself will become larger, and the pumping roller L will have a larger diameter, or a new intermediate roller will be installed between the pumping roller and the application roller. There is a drawback that the entire fixing device becomes larger.

The second problem is that the level of oil in the oil pan P is kept as low as possible in order to make the fixing device easier to carry and to prevent the silicone oil from boiling over. Therefore, if the image forming apparatus main body is installed at an angle, the pumping roller l cannot be immersed in the silicone oil to a sufficient depth.
One end portion is not covered with silicone oil, and therefore the surface of the fixing roller 3 is also partially coated with silicone oil, which may cause offset during fixing.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device capable of reliably applying a release agent evenly to a fixing roller by solving the problems of the prior art described above.

Summary, Structure of the Invention [Means for Solving the Problems] In order to prevent the toner from offsetting to the fixing roller, the present invention uses a pumping roller immersed in a release agent such as silicone oil to remove the release agent. In a fixing device that pumps up a release agent and applies a release agent from the pumping roller to a fixing roller via an applicator roller, at least a portion of the pumping roller immersed in the release agent is covered with a release agent-impregnated member such as felt. It is characterized by

[For production]

Since at least the part immersed in the release agent is covered with a member impregnated with the release agent such as felt, even if the viscosity of the release agent is high, the flow resistance caused by the impregnated member prevents the mold from being released. The agent is not pumped up by the pumping roller at multiple ends, and since the impregnating member is always in contact with the pumping roller over its entire length, even if the image forming apparatus is installed at an angle, the agent can be easily removed from the pumping roller to the coating roller. The release agent is applied to the fixing roller without any chance.

〔Example〕

FIG. 1 is a front view of the main parts of a fixing device showing an embodiment of the present invention. In FIG. , 3 and 3a are fixing rollers whose configuration is similar to that of the second fixing roller.
This is the same as the conventional example shown in the figure. Reference numeral 4 denotes an impregnated member made of felt or the like, which is placed in the oil pan P so as to surround the lower surface of the scooping roller l, and is impregnated with silicone oil 0 in the oil pan P, and is constantly in contact with the lower outer circumferential surface of the fixing roller l. are doing.

The height from the bottom of the oil pan P to the lowest point of the scoop-F roller l is hI, and the height to the top of the impregnation member 4 is h2.
If the height of the oil level is h3, hl ・h2 ・
At least on the downstream side in the rotational direction of the scooping roller 1, there is a relationship between h3 and h3, and the oil level height h3 is controlled to be h2 within h3. Therefore, most of the silicone oil is in contact with the pumping roller 1 while being impregnated with the impregnating member 4. For this reason, apply silicone oil to the fixing roller 3! Even if the pumping roller 1φ application roller 2 rotates due to u, Ft due to the impregnating member 4
Due to the dynamic resistance, a large amount of silicone oil is not pumped up onto the pumping roller 1, and oil overflow due to this does not occur. Since no changes occur,
The amount of coating applied to the fixing roller 3 can be kept constant at all times.

Furthermore, by using a material such as felt for the impregnating member 4, the liquid level h3 of the silicone oil can be set as low as approximately the same height as the height hl of the highest point of the pumping roller 2 by utilizing its capillary phenomenon. Furthermore, even if the main body of the image forming apparatus is installed tilted, the oil can be applied uniformly over the entire length of the fixing roller 3 in the axial direction.

Furthermore, in combination with the fact that the liquid level h3 of the silicone oil can be set as low as described above, most of the oil is impregnated in the impregnating member 4, so that maintenance such as replacing or cleaning the application roller 2 etc. can be easily performed. Furthermore, when the fixing device is detached from the main body of the image forming apparatus, there is little risk of oil spilling and the fixing device can be detached easily.

C. Detailed Description of the Invention As described above, the present invention has an extremely simple structure in which a member impregnated with a mold release agent such as felt is provided in the oil pan, so that the mold release agent (silicone oil) can be absorbed into the oil pan unlike the conventional method. In addition to preventing the release agent from overflowing, it is also possible to uniformly apply the release agent to the fixing roller at all times without being affected by fluctuations in the liquid level of the release agent or the tilt of the image forming apparatus main body. Moreover, when the fixing device is removed from the image forming apparatus for maintenance or the like, there is little risk of the release agent spilling out from the oil pan, so handling is easy.

[Brief explanation of the drawing]

FIG. 1 is a front view of the main parts of a fixing device embodying the present invention, and FIG. 2 is a view of the conventional example. 1 is a pumping roller, 2 is an application roller, 3 is a fixing roller, 4
is the impregnated member, P is the oil, and 0 is the mold release agent (silicone oil).

Claims (1)

[Claims] (1) In order to prevent the toner from offsetting to the fixing roller, the releasing agent is pumped up by a pumping roller immersed in a releasing agent such as silicone oil, and then released from the pumping roller to the fixing roller via an applicator roller. A fixing device for applying a molding agent, wherein at least a portion of the scooping roller immersed in the molding agent is covered with a molding agent-impregnated member such as felt.