JPS6252302B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heated roller type toner image fixing device, and more particularly to a fixing device in which at least one roller is coated with an anti-offset liquid.

In a hot roller type toner image fixing device, an anti-offset liquid is usually applied to a fixing roller that is pressed against the image surface side of a toner image support material. This liquid can be applied to the fixing roller by dipping one end in a liquid tank and directly contacting the other end of a liquid transmission member such as a cloth or felt that uses capillary action against the fixing roller; A typical method is to bring the coating material into contact with a rotating application roller. In either method, the amount of liquid applied to the fixing roller tends to be larger than the required amount, resulting in wasted liquid consumption, especially in models where the roller constantly rotates. If the members remain in contact, fluid consumption will significantly increase. Furthermore, if the toner image supporting material is soiled or if the fixing or pressing roller has a swellability with respect to liquid, the diameter of the roller increases and the performance of the fixing device changes.
In addition, liquid transmission members such as felt and cloth mentioned above,
If the fixing roller or applicator roller remains in contact with the fixing roller while the fixing operation is stopped, a large amount of liquid will accumulate in this contact area, and this liquid will stain the toner image support material when the fixing operation is resumed, or the rollers may This may cause inconveniences such as causing slippage and disturbing the toner image.
The liquid transmission member is usually separated from the fixing roller or application roller when the fixing operation is stopped. However, during the above-mentioned separation, a change occurs in the liquid impregnation distribution state in the liquid transmission member, and when the fixing operation is resumed, excessive liquid concentrates near the surface that should come into contact with the fixing or coating roller, which also supports the toner image. This may cause contamination of the material, or there may be a shortage of liquid near the surface, which may cause inconveniences such as an offset when the fixing operation is restarted or the toner image support material being wrapped around the fixing roller. Ta.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fixing device that solves the above-mentioned disadvantages.

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, the roller 1 is a fixing roller with a core metal pipe 2 coated with a thin layer of release material 3 such as silicone rubber or tetrafluoroethylene resin, and the roller 4 is a fixing roller with a core metal pipe 2 coated with a relatively thick silicone rubber. This is a pressure roller coated with rubber 6. Both rollers are pressed against each other with appropriate pressure and rotate in the direction of the arrow. A toner image support paper 7 holding a heat-fusible toner powder image 8 is conveyed under heat and pressure between rollers 1 and 4, thereby fixing the toner image on the paper. The fixing roller 1 is heated by a halogen heater 9 which is an internal heat source.
The surface temperature is controlled to always be within a constant temperature range by a temperature sensing element 10 such as a thermistor. Although it varies depending on the toner material, etc., this surface temperature is usually 150 to 250°C. Separation claws 11 and 12 are used to reliably separate and convey the fixed paper from the rollers 1 and 4. Although the plate-shaped oil scraper 13 in contact with the pressure roller 4 is not necessary in all cases, it is particularly
When the thick silicone rubber layer 6 is a dimethyl silicone-based elastomer layer, and the offset prevention liquid described below is a dimethyl silicone-based oil and has a particularly low viscosity, the edge area where the paper does not pass or where the paper enters. Changes in the volume of the silicone rubber layer due to impregnation of the silicone rubber layer 6 with the liquid transferred from the roller 1 in the previous steps are minimized.

The apparatus A for applying silicone oil as an offset prevention liquid to the fixing roller is constructed as follows in this embodiment. That is, 14 is a tank containing silicone oil 15. Immersed in the oil 15 of this tank 14 is an end 16' of a liquid transmission (or supply) member 16, such as a heat-resistant felt or cloth, which absorbs and transports the oil by capillary action. The other end 16'' of this liquid transmission member is folded in two and packed into a gutter-shaped bag 17.
The bottom surface of the bag 17 filled with felt 16 is selectively moved toward and away from the upper surface of the roller 1 by a mechanism described later.

Now, the bag 17 mentioned above is a non-fibrous polymeric synthetic resin membrane having fine continuous pores, i.e., it is made of a non-fibrous polymeric synthetic resin membrane, such as felt, in which fibers are entangled, or air bubbles or single cells are dispersed, as in a sponge. Rather, it is composed of a heat-resistant, flexible membrane with many microscopic pores that penetrate from the front surface to the back surface of the membrane. GORE-TEX (WLGORE &
These include ASSOCIATES, INC., product name) and Fluoropore (Sumitomo Electric Industries, Ltd., product name).
The membrane with such a trade name is a tetrafluoroethylene resin membrane manufactured based on the manufacturing method described in Japanese Patent Publication No. 48-3068, and the fine continuous pore diameters formed in it are very uniform. The diameter distribution is approximately 100% concentrated in an extremely narrow range around the average diameter, and has a delta function shape.

Now, the above-mentioned bag 17 is fixedly supported by a frame 18 at its mouth. And this frame 1
8, an arm 20 is pivotably attached at its end 20', while the other end 20'' of the arm 20 is pivotably attached to a stationary member 19 of the main body of the apparatus. This arm 20 is biased by a tension spring 21 to rotate counterclockwise around the axis of the end 20'', and this biasing force causes the felt end 16'' to be compressed. The bottom surface of the polymer synthetic resin film bag 17 is in surface contact with the upper surface of the roller 1.Here, 22 is a cam against which the arm 20 is brought into contact, and when the cam 22 is in the position shown in the figure. The bag 17 is brought into contact with the roller 1 by the bias of the spring 21, but when the cam 22 rotates 180 degrees from the position shown in the figure and the cam surface portion 22' engages the arm 20, the bag 17 is brought into contact with the felt integrally with the frame 18. The filled bag 17 at the end 16'' also rises, and the bag 17 is separated from the roller 1. The rotation of the cam 22 is controlled by a control circuit (not shown) according to a known sequence, so that, for example, when a plurality of sheets of paper are successively fixed, the first sheet of paper is fixed by the rollers 1 and 4. From just before the paper enters the space between the rollers 1 and 4 until the last paper set by the operator finishes coming out from between the rollers 1 and 4, and even when a sheet of paper is to be fixed, the paper remains between the rollers 1 and 4.
From just before entering the gap until it finishes exiting, bag 17
The bottom surface of the roller 1 is brought into contact with the roller 1, and silicone oil is applied to the roller 1 at this time.

That is, the silicone oil transmitted by the felt 16 from the tank 14 to the end 16'' by capillary action is
The roller 1 passes through the aforementioned fine continuous pores of the membrane 17.
The necessary amount of silicone oil is supplied to the surface of the roller 1 and squeezed by the surface contact between the bag 17 and the roller 1, so that an extremely thin film of silicone oil is formed on the surface of the roller 1.

Incidentally, since the above-mentioned tetrafluoroethylene resin film having fine continuous pores has good slip properties, the bag 17 slides into contact with the roller, but there is hardly any wear. Furthermore, since it has excellent non-adhesive properties, it is possible to prevent problems such as the pores being clogged with toner or paper dust and reducing oil seepage. For this reason, a very small amount of oil can be stably and uniformly applied to the roller 1 over a long period of time. In addition, membranes such as Fluoropore membrane and GORE-TEX are stretched during the manufacturing process and are stretched into membranes, but they are difficult to stretch in the direction of stretching, and in the direction perpendicular to it. It is easy to stretch and undergo plastic deformation. Therefore, it is preferable that the direction in which the membrane is stretched and the rotational direction of the roller 1 are arranged so that they substantially coincide with each other at their abutting portions. Further, when the bag 17 is constructed by laminating and bonding a plurality of membranes, if the stretching directions of at least two of the membranes are made to intersect, preferably orthogonally, it is possible to Although the arrangement direction of the film is relatively arbitrary, even in this case, the stretching direction of at least one film, preferably the outermost film in direct contact with the roller 1, is set at the contact area with the roller 1. It is desirable that the rollers be arranged so as to coincide with the rotational direction of the roller 1.

Now, when the fixing operation of the device is completed as described above, the bag 17 filled with the end of the felt 16 is raised by the rotation of the cam 22, and the bag 17 is moved up by the roller 1.
be separated from As a result, the application of silicone oil to the roller 1 is naturally interrupted. If left in this state for a long time, the end 1 of the felt 16
A large amount of oil impregnated with this felt concentrates at the bottom of the 6" bend, and in the past, this oil would drip and wet the roller surface, or even if not, a large amount of oil would be released when the fusing operation was restarted. However, in the device shown in FIG. 1 in which the surface of the felt 16 is covered with a film 17, oil is deposited on the bent portion 16'' of the felt while the fixing operation is stopped. Even if the fixing operation is restarted, the membrane 17 prevents the passage of the oil, thereby preventing inconveniences such as oil dripping onto the roller surface or a large amount of oil temporarily adhering to the roller when the fixing operation is restarted. can. Bag 17 on roller 1
When the felt 16 comes into contact with the roller 1, the oil in the felt 16 oozes out through the fine continuous pores.
One of the reasons why the leakage is prevented or minimized when the bag 17 is separated from the roller 1 is that when the bag 17 is separated from the roller 1, the temperature of the felt end 16'' and thus of the silicone oil impregnated therein is reduced. The viscosity of the oil also decreases, which causes the viscosity of the same oil to increase.
This is thought to be because it makes it extremely difficult to pass through continuous pores that have minute diameters and are very uniform in size, such as those in No. 7. Therefore, when the bag 17 is separated from the roller 1, the temperature of the bag 17 is 30°C lower than the surface temperature of the roller 1.
In other words, although the bag 17 and the felt and oil inside it are heated by the heat dissipation of the roller 1, the temperature of the bag 17 due to the heating becomes 30°C or more lower than the surface temperature of the roller 1. It has been found that the effect becomes more pronounced when the ratio is between the two.

In addition, the material of the toner, the material of the image support material, and the roller 1
Although it varies depending on the surface temperature of the film, its peripheral speed of rotation (corresponding to the fixing processing speed), etc., the film 1
7 has a thickness of 50 to 4000μ, an average diameter of fine continuous pores of 0.1 to 5μ, and a porosity of 20 to 95%.
The standard viscosity of offset prevention liquid at room temperature is 100 to
It was experimentally confirmed that it is sufficient to use a 10K CS.

FIG. 2 shows another embodiment, and the same reference numerals as those in FIG. 1 are used to apply the explanation in FIG. 1. In FIG. 2, a bag 17 made of a polymeric synthetic resin having fine continuous pores such as the aforementioned Fluoropore or GORE-TEX is brought into contact with and separated from the roller 1.
is filled with a heat-resistant sponge 23. This sponge 23 absorbs and retains silicone oil, exudes silicone oil, and supplies the oil to the roller 1 via the control membrane 17. Silicone oil is supplied to the sponge 23 by a heat-resistant felt 16. That is, one end 16' of the felt 16 is immersed in the oil 14 in the tank 15, and the oil is transmitted by capillary action. The other end 16'' of the felt 16 is folded in half and stuffed into a bag 24. Like the bag 17, this bag 24 is also made of a polymeric synthetic resin having the aforementioned fine continuous pores, such as Fluoropore or GORE-TEX. The opening of the bag 24 of this control membrane is fixedly supported by a frame 25. A lever 20 similar to that shown in FIG. 1 is connected to this frame 25. Bag 17 The frame 18 supporting the is connected to the frame 25 by a link 26. In the state shown in the figure, the frames 17, 18,
The link 26 expands due to the weight of the member 23, and 1
7, 18, and 23 are suspended from the frame 25 by links 26. That is, the bottom surface of the bag 17 is spaced apart from the roller 1, and the bottom surface of the bag 24 is also spaced apart above the sponge 23. In short, the state shown in the figure is a state in which the fixing operation is stopped. At this time, the oil impregnated in the sponge 23 concentrates in the lower part of the sponge 23, but since the volume of the sponge 23 itself is small, the amount of concentrated oil is also relatively small. Due to the action of the membrane 17, this concentrated oil hardly comes out to the surface of the membrane 17. On the other hand, the action of the membrane 24 prevents the silicone oil concentrated at the lower part of the felt end 16'' from dripping onto the sponge 23 and from temporary oversupply when the sponge 23 and the bag 24 come into contact again.

Next, when the fixing operation is resumed, the cam 22 rotates and the lever 20 rotates counterclockwise around the shaft 20'' by the force of the spring 21. Therefore, the bottom of the bag 17 first comes into contact with the roller 1, and then The link 26 is bent so that the bottom surface of the bag 24 comes into contact with the top surface of the sponge 23. In this way, the oil transmitted through the felt 16 penetrates into the sponge 23 under the control of the membrane 24.
The oil supplied to the sponge 23 is applied to the roller 1 under the control of the membrane 17.

Although the membrane 24 is provided on the felt 16 side in FIG. 2, it may be provided on the upper surface of the sponge 23.
In any case, the device shown in FIG. 2 is more effective for low viscosity oil.

In addition, in FIG. 2, the bag 17 is kept in contact with the roller 1 at all times regardless of whether the fixing operation is in operation or not, and the bag 24 is brought into contact with and away from the sponge 23 in response to switching between the fixing operation and non-operation. may be configured.

Also in the embodiment of FIG. 2, the thickness of the films 17 and 24,
Regarding the average pore diameter, porosity, and oil viscosity, the same can be said as in the embodiment shown in FIG.

In the embodiments shown in FIGS. 1 and 2, the control membrane bag 17 filled with felt 16 or sponge 23 containing silicone oil was brought into direct contact with the fixing roller 1. However, as shown in FIG. 3, an application roller 27 that rotates in contact with the fixing roller 1 is provided;
7, the above-mentioned bag 17 may be moved toward and away from the fixing device according to the change in fixing operation and non-operation. The oil is first supplied to the roller 27, which applies it to the roller 1. It is also possible to use a roller row consisting of two or more rollers that sequentially abut and rotate as the application roller row.

Further, the oil application device described above may be applied not to the fixing roller 1 but to the pressing roller 4, or to both rollers 1 and 4.

As described above, according to the present invention, with a simple configuration, it is possible to prevent inconveniences such as staining of the toner image support material and image destruction due to changes in the liquid distribution in the liquid-impregnated holding member when the operation is stopped.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining one embodiment of the present invention, FIG. 2 is another embodiment, and FIG. 3 is a still further embodiment, in which 1 is a fixing roller, 4 is a pressing roller,
9 is a heater, 16 is a felt, 17 is a control membrane, 2
0 is a lever, and 22 is a cam.

Claims (1)

[Scope of Claims] 1. In a fixing device that fixes a toner image by sandwiching and conveying a toner image support material between a first roller and a second roller, at least one of which is heated, the first roller a polymeric synthetic resin film having a coating means for applying an anti-offset liquid to the first roller when the first roller comes into contact with and separates from the first roller; A fixing device characterized by being provided with. 2. Claims in which the application means is spaced apart from the first roller at a distance such that the temperature is maintained at least 30°C lower than that of the first roller when the application means is spaced apart from the first roller. The fixing device according to item 1. 3. The fixing device according to claim 1 or 2, wherein the polymer synthetic resin film is a tetrafluoroethylene resin film having fine continuous pores. 4. In a fixing device that fixes a toner image by sandwiching and conveying a toner image support material between a first roller and a second roller, at least one of which is heated, a coating means for applying an anti-offset liquid to the roller; and a supply means that comes into contact with and separates from the application means and supplies the anti-offset liquid to the application means when in contact with the roller, and a contact/separation portion between the supply means and the application means. A fixing device characterized in that a polymer synthetic resin film having fine continuous pores is provided in the fixing device. 5. Claim 4, wherein the supply means is spaced apart from the application means at a distance such that when the supply means is separated from the application means, the temperature is maintained at least 30° C. lower than that of the first roller. The fixing device described. 6. The fixing device according to claim 4 or 5, wherein the polymer synthetic resin film is a tetrafluoroethylene resin film having fine continuous pores.