JP3251129B2 - Fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device using a heating roller in a copying machine, a printer or the like.

[0002]

2. Description of the Related Art Conventionally, as a fixing device in a copying machine, a printer, and the like, a fixing device using a heating roller is known. In this fixing device, there is often a problem of image contamination due to foreign matters such as developer (toner) and paper powder remaining on the heating roller and the pressure roller at the time of fixing. The following techniques have been proposed as conventional techniques related to such a problem.

(1) In a fixing unit in which a cleaning felt is brought into contact with the surface of a heating roller, a rotating body cleaner is provided in the vicinity of the felt to remove dirt from toner or the like on the surface of the heating roller, and to perform copying at the time of fixing. (The "fixing unit" described in JP-A-3-28873).

(2) The outer circumference felt portion of the coating roller is integrally formed by a felt member and a reinforcing member, and the outer circumference felt portion is detachable from the support portion, so that the offset preventing agent supply means is provided. Simplification and cost reduction ("Felt exchange type offset prevention coating roller" described in JP-A-4-107489).

(3) A pair of rotating bodies forming a nip for cooperating and conveying the transfer material on which the unfixed developer image is formed, and at least one of the rotating bodies. A cleaning unit having a pressing roller for pressing one surface and the other surface of the web-shaped cleaning member against one rotating body, wherein the surface layer of the pressing roller of the cleaning unit is formed of a layer containing a fluororesin. That is, the occurrence of image contamination due to foreign matters such as developer and paper powder remaining on the fixing roller is prevented beforehand (“Fixing device” described in JP-A-5-53468).

(4) Fixing means for passing a material to be fixed between the fixing roller and a pressure roller which is pressed against the fixing roller, and for fixing the developed image transferred onto the material to be fixed, and the fixing means Release roller coating means for coating a release agent on the surface of the fixing roller, and contact / separation control means for controlling the release agent coating means so as to be capable of coming and coming from the fixing roller of the fixing means. A coating roller as a release agent applying unit for applying a release agent to the surface of the fixing roller of the fixing unit, which can be brought into and away from the fixing roller via a cam as a contact / separation control unit,
When the fixing roller is stopped or when the temperature drops below the specified temperature, the fixing roller is separated from the fixing roller to release the contact state, and the toner and paper dust are contaminated by the release agent applying means to the fixing roller. To prevent an offset from being generated on an image fixed on copy paper (“Fixing device” described in JP-A-5-119656).

(5) High viscosity (30000 to 60000C)
S) The silicon oil is supplied to the heating roller by a small amount of oil applying roller which is wound by attaching a web having a base cloth to a hollow cylindrical member having an oil supply hole incorporating silicon oil and preventing offset. "A trace oil-applied roller".

(6) Oil is uniformly supplied to the heating roller by a minute oil coating roller whose outermost layer is formed of a microporous film, so that the coating roller itself is not easily stained.

[0009]

In the above-mentioned prior art (1), when fixing to paper (particularly Western paper) having a large amount of large-grain components such as calcium carbonate as a paper filler, The toner is liable to be offset to the heating roller due to the poor adhesion between the filler and the fiber of the paper, and the cleaning means of the heating roller is immediately stained, and the cleaning performance deteriorates in a short time. Therefore, in this technique, it is difficult to guarantee the performance of the cleaning member until the periodic inspection.

In the prior art (2), similarly to the prior art (1), when using paper or the like, it is necessary to inspect the cleaning felt several times before the predetermined periodic inspection. Not preferred.

In the prior art (3), since the cleaning mechanism is large-scale, there are disadvantages such as an increase in installation space and an increase in cost.

In the prior art (4), a means for contacting and separating the release agent applying means from the fixing roller and its control are required, so that the cost is high and the effect of improving the life by contacting and separating is small. There are disadvantages.

The prior arts (5) and (6) have the same drawbacks as the prior art (1), and may require the addition of a separate cleaning member.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned point, and by providing a larger gap in the pressure contact area of the cleaning roller, even if the cleaning roller is in the pressure contact state, the cleaning is performed from the fixing roller. It is an object of the present invention to provide a fixing device that allows toner transferred to a roller to easily reach a deep layer of a cleaning roller, and that can prevent separation of soiled toner once transferred to the cleaning roller.

[0015]

The present invention SUMMARY OF THE INVENTION To solve the problems described above, at least one of the heating roller and the pressure roller, the fixing device comprising contacting the cleaning roller, the cleaning roller, away Built-in mold
A hollow cylindrical member having a release agent supply hole on the outer periphery;
Adhere to the outer periphery of the hollow cylindrical member and regulate the supply amount of release agent
An intermediate layer, and an adjacent layer having a gap in close contact with the outer periphery of the intermediate layer
And further in close contact with the outer periphery thereof and connected to the gap of the adjacent layer.
It has an outermost layer with a thickness of 10 to 30 μm and
And the thickness of the outermost layer is smaller than the thickness of the adjacent layer,
The porosity of the adjacent layer is higher than the porosity of the outermost layer.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings together with reference examples. FIG. 1 shows an example of the fixing device.
As shown in FIG. 1A, the fixing device of this embodiment includes a heating roller 1, a pressure roller 2, a thermistor 3, a separating claw 4, an oil application roller 5, a cleaning roller 6, and the like.

The heating roller 1 is a roller having a surface coated with a thin film (preferably 5 mm to 30 mm) of a fluororesin (for example, PFA, PTFE) having a good toner releasability, and having a heater 1a disposed therein. It is configured.

The pressure roller 2 is made of a heat-resistant rubber whose surface is elastically deformed (for example, silicone rubber; hardness: 10 to 50 Hs).
t is preferable), and the fixing nip width A formed with the heating roller 1 is several millimeters (preferably 5 to 10 mm).
Is applied to the heating roller 1 such that

The thermistor 3 detects the surface temperature of the heating roller 1, and based on the detection output, detects the temperature of the heating roller 1.
The surface temperature of the heating roller 1 is maintained at a predetermined fixing temperature by ON / OFF control of the heater 1a built in the heating roller 1a.

The separating claw 4 includes a heating roller 1 and a pressing roller 2.
In order to prevent the copy 7 fixed in the fixing nip area from being wound around the peripheral surface of the heating roller 1, the copy 7 is separated (separated) from the heating roller 1 and guided downstream.

The oil application roller 5 is provided with a release agent (oil; viscosity: 10,000 to 1) for preventing toner offset.
5D is built in, and the built-in release agent 5
A small amount of d is supplied to the surface of the heating roller 1 and applied to prevent the offset of the toner at the time of fixing (with a release agent of several tens of grams, the offset of the toner at the time of fixing several hundred thousand copies is reduced. Can be prevented). Silicon-based oil, fluorine-based oil, or the like is used as the release agent 5d.

The cleaning roller 6 removes stains such as toner and paper dust adhering to the surface of the pressure roller 2 to prevent back stains on the copy 7 during fixing.

In FIG. 1A, the unfixed toner carried as a visible image on the surface of the copy 7 after a well-known predetermined developing step and transfer step is transferred to the heating roller 1 and the pressure roller. Is fixed as a copy image on the surface of the copy 7 in the fixing nip area.

It is difficult to fix all the unfixed toner carried on the copy 7 to the copy 7 side in the fixing nip area even if the surface of the heating roller 1 has a very good releasability. Although a very small amount, a part of the toner is offset to the heating roller 1 (hereinafter, this is referred to as a small amount offset), and a part of the small amount of toner is transferred to the oil application roller 5. .

The transfer of the toner to the oil application roller 5 causes clogging of the release agent application portion of the oil application roller 5, so that proper application of the release agent 5 d to the heating roller 1 can be achieved. As a result, a large amount of unfixed toner is offset on the heating roller 1 to cause a deterioration in the image quality of the copy.

In the fixing device of this embodiment, as shown in FIG. 1 (b), the oil storage container portion of the oil application roller 5 has at least an outermost layer 5a having a porosity ρ1 and an average radius r1.
An intermediate layer (oil supply control layer) 5b having a porosity ρ2 and a radius r2 closer to the center than the outermost layer 5a;
3 (e.g., a plurality of through-holes having a diameter of 0.2 to 1.0 mm are provided to regulate the amount of oil supply) and has a hollow cylindrical member 5c having an oil supply hole. , Porosity ρ2, radius r2 is ρ1r2
The oil applying roller 5 is configured so that> ρ2r1.

The oil coating roller 5 configured as described above
As compared with the conventional oil-applying roller configured so that ρ1r2 ≒ ρ2r1, the dirt toner transferred to the outermost layer 5a reaches the deeper portion, and the oil-applying roller 5 can be prevented from being spotted in the copy caused by the toner once attached to the transfer roller 5 being transferred to the heating roller 1 again.

The spot-like background stain phenomenon of the copy easily occurs particularly when using copy paper made of paper. The reason is that the amount of natural calcium carbonate used as a filler in the paper and the size thereof are large compared to other fillers (for example, titanium oxide), and the filler is relatively high from the surface of the paper. It is believed that there is a very close relationship with being easily detached.

According to the fixing device of this embodiment, foreign matters such as toner and paper dust adhering to the heating roller 1 can be more reliably captured and removed (cleaned). However, it is possible to prevent or reduce the occurrence of spot-like stains.

A second example of the fixing device will be described. In this example, as shown in FIG. 2, when the outermost layer 5a of the oil applying roller 5 is pressed against the heating roller 1, for example, the surface of the outermost layer 5a when compressed becomes the surface when uncompressed. Than 0.
Elastically deformed by a compression deformation amount p of about 2 to 1.0 mm,
This outermost layer 5a is connected to a porous heat-resistant rubber, a brush-like member,
It is composed of an elastic layer such as a spongy member. As a result, the toner transfer from the heating roller 1 to the oil applying roller 5 is performed in a state where the pressure is continuously applied for a predetermined time or more (a state where the elastic residual effect is reduced). However, after passing through the pressure contact portion between the heating roller 1 and the oil application roller 5, it is possible to suppress cooling and solidification on the surface side of the oil application roller 5.

A third example of the fixing device will be described. In this example, as shown in FIG. 3A, the outermost layer 5a of the oil storage container portion of the oil application roller 5 is spirally wound at a predetermined interval. As described above, when the outermost layer 5a is spirally wound at a predetermined interval, the protrusions of the outermost layer 5a arranged at a predetermined pitch are formed on the surface of the heating roller 1 with respect to the surface of the heating roller 1. The pressurized state can be maintained at a constant pressure, and the oil application roller 5 can be smoothly rotated.

According to this embodiment, the toner transferred to the oil applying roller 5 is easily solidified in a state where it has entered the concave portion formed by the outermost peripheral layer 5a spirally wound. Therefore, the release agent 5d always intervenes on the surface (oil-applied surface) of the convex portion of the outermost layer 5a that comes into pressure contact with the heating roller 1, and the toner is applied to the oil-applied surface. Even if the toner adheres, the amount of the toner is extremely small. Therefore, even if the small amount of toner is detached from the outermost layer 5a, spot-like image stains of a size, number, and frequency that cause a problem. Will not cause.

In this embodiment, since it is not necessary to allow the release agent 5d to pass through the lower part of the concave portion of the outermost peripheral layer 5a, as shown in FIG. The oil supply through hole of the cylindrical member 5c is
By providing only at the portion corresponding to the convex portion of a and not providing it at the portion corresponding to the concave portion of the outermost layer 5a, it becomes easier for the toner to harden in a state where it has entered the concave portion, and The toner is less likely to be extruded and released by the release agent 5d, and the above effect can be made more remarkable.

A fourth example of the fixing device will be described. This example is different from the third example shown in FIG.
Of the outermost layer 5a is configured to rotate in such a manner that the outermost layer 5a comes into sliding contact with the surface of the heating roller 1 disposed opposite to the outermost layer 5a. According to the present embodiment, since a sliding force acts between the oil applying roller 5 and the heating roller 1, dirt such as toner adhering to the surface of the heating roller 1 is removed by the sliding force. It is scraped off by the convex portion of the outermost layer 5a of the coating roller 5,
The dirt such as toner and paper dust transferred to the oil coating roller 5 is effectively captured by the recesses of the outermost layer 5a of the oil coating roller 5, and the transfer to the heating roller 1 side is less likely to occur. Here, preferably, when a speed difference of 10% or more of the rotation speed of the heating roller 1 is provided between the rotation speed of the oil coating roller 5 and the rotation speed of the heating roller 1, the effect of this embodiment is further enhanced. be able to.

A fifth example of the fixing device will be described. In this embodiment, the outermost layer 5a of the oil application roller 5 is configured by a layer in which an oil supply layer 5a-1 and a cleaning layer 5a-2 are mixed. That is, as shown in FIG. 4, the outermost layer 5a of the oil application roller 5 in this example is a material that easily transmits the release agent 5d to the surface and does not easily adhere to the dirt toner or the like on the heating roller 1. (For example, foamed silicone rubber, etc.)
And an oil supply layer 5a-1 composed of the following, and conversely, the surface of the release agent 5d is hardly permeated (there is almost no capillary phenomenon),
And tends material contamination such as toner on the heating roller 1 is attached (e.g., felt or foamed urethane, continuous foaming onset foam rubber) and a cleaning layer 5a-2 made of, formed by arranging alternately I have. Therefore, according to the oil application roller 5 of the present embodiment, the oil supply layer 5a-1 can ensure a stable oil application function over time, and the cleaning layer 5a-2 allows the heating roller 1
It is possible to maintain the cleaning effect for reliably capturing the dirt toner and the like adhering to the toner for a long time.

A sixth example of the fixing device will be described. In this embodiment, the porosity of the cleaning layer 5a-2 of the outermost layer 5a of the oil application roller 5 is determined by the oil supply layer 5a-1.
(Area ratio of oil passage portion). According to the present example, the oil application function and the cleaning function of the oil application roller 5 can be more reliably separated, and the oil application effect of applying the release agent 5d to the heating roller 1, and The cleaning effect of removing toner stains and the like attached to the heating roller 1 can be further enhanced.

A seventh example of the fixing device will be described. In this example, the outermost layer 5 of the oil application roller 5 described in the fifth example is used.
a is composed of an elastic layer. According to this example, the second
As in the case of the fixing device described in the example, the toner transfer from the heating roller 1 to the oil applying roller 5 takes a predetermined time or more.
The transfer is performed in a state where the pressure is continuously applied (the state where the elastic after-effect is reduced). After the transferred toner passes through the pressure contact portion between the heating roller 1 and the oil applying roller 5, the transferred toner is applied. Cooling and solidification on the surface side of the roller 5 can be suppressed. In the present embodiment, the pressing nip width between the oil coating roller 5 and the heating roller 1 can be increased to a predetermined value or more, so that the outermost layer 5a, especially the cleaning layer 5a-2, is surely elastically deformed. In the case of using the open-celled foam rubber, the hollow cylindrical member 5c and the intermediate layer 5b of the oil applying roller 5 are used to separate a portion having oil supply to the intermediate layer 5b from a portion having almost no oil supply. By doing so, in the outermost peripheral layer 5a as well, it is possible to make the same distinction between the part with oil supply and the part with little oil supply as described above. According to the present example, the cleaning portion of the heating roller 1 can be formed by the portion of the outermost layer 5a where there is almost no oil supply.

An eighth example of the fixing device will be described. In this example, the outermost layer 5 of the oil application roller 5 described in the fifth example is used.
a is configured to rotate so as to be in slidable contact with the surface of the heating roller 1 arranged opposite to the heating roller 1. According to the present example, as in the case of the fixing device described in the fourth example, a rubbing force acts between the oil application roller 5 and the heating roller 1. Dirt such as toner adhering to the surface is more effectively captured by the cleaning layer 5a-2 of the outermost layer 5a of the oil application roller 5, and the toner and paper dust transferred to the oil application roller 5 are transferred. Re-transfer of dirt such as to the heating roller 1 side is less likely to occur. As in the case of the fixing device described in the fourth example,
By providing a speed difference of 10% or more of the rotation speed of the heating roller 1 between the rotation speed of the oil application roller 5 and the rotation speed of the heating roller 1, the effect of this embodiment can be further enhanced.

A fixing device according to an embodiment of the present invention will be described. In this embodiment, the cleaning roller 6 has an adjacent layer having a void ratio higher than the void ratio of the outermost peripheral layer 6a and communicating with the void portion of the outermost peripheral layer 6a. That is, as shown in FIG. 5, the outermost layer 6a of the cleaning roller 6 in this embodiment has a porosity ρ3, a surface layer 6a-1 having a thickness t1, and a porosity ρ4, an adjacent layer 6a- having a thickness t2.
2 and a porosity ρ3,
The relationship between the thickness t1, the porosity ρ4, and the thickness t2 is ρ3 <ρ
4, t1 <t2. Thus, in the present embodiment, the suitable thickness t1 of the surface layer 6a-1 is set.
Is formed as very thin as 10 to 30 μm,
In the nip area between the cleaning roller 6 and the heating roller 1, the toner transferred from the heating roller 1 easily passes through the surface layer 6a-1 of the outermost layer 6a of the cleaning roller 6, and the toner is transferred to the adjacent layer. 6a-2 can be easily reached. In this embodiment, the porosity ρ3 of the surface layer 6a-1 is smaller than the porosity ρ4 of the adjacent layer 6a-2,
Once the toner trapped in the adjacent layer 6a-2 side is difficult to re-transfer to the heating roller 1, the toner transferred to the cleaning roller 6 side is transferred to the adjacent layer 6a-2.
Can be solidified in The structure of the cleaning roller 6 in the present embodiment can be applied to the oil application roller 5 as it is. The cleaning roller 6 shown in FIG.
b and the hollow cylindrical member 6c, a release agent (cleaning agent)
6d.

A ninth example of the fixing device will be described. In the present embodiment, as shown in FIG. 6, the outermost layer 6a of the cleaning roller 6 is constituted by a loop flocking brush. With this structure, the effects of the fifth embodiment and the device according to claim 1 can be simultaneously obtained. Obtainable. As is well known, the loop flocked brush constituting the outermost layer 6a of the cleaning roller 6 of the present embodiment has one loop formed of a large number of fiber bundles. Therefore, as shown in FIG. When the roller 6 is configured in the same manner as the oil applying roller 5, the release agent (cleaning agent) 6d contained in the cleaning roller 6 causes the surface of the cleaning roller 6 to move due to the capillary phenomenon of the loop flocking brush. Can be easily reached, and the layer immediately below the foremost part of the loop flocking brush is a loop-shaped space, so that the toner transferred from the heating roller 1 is easily captured in this space. can do. According to this example, it is possible to prevent spot-like image stains from being generated due to the detachment of the once captured toner. The structure of the cleaning roller 6 in this embodiment can be applied to the oil application roller 5 as it is.

A tenth example of the fixing device will be described. In this example, the outermost layer 5a of the oil applying roller 5 is formed of an elastic layer having a gap through which oil passes,
-3 and a lower layer 5a-4.
a of the surface layer 5a-3 of the lower layer 5a-4
Is larger than the compressive deformation rate ΔV2. In this example, the thickness t3 (10 μm) of the surface layer 5a-3 of the outermost layer 5a
(Preferably 1.0 mm) is thinner than the thickness t4 of the lower layer 5a-4, that is, t3 ≦ t4. Here, the compressive deformation rate is the amount of compressive deformation with respect to a predetermined pressing force in actual use conditions, and the compressive deformation rate ΔV1 of the outermost layer 5a of the surface layer 5a-3 is ΔV10, Assuming that the volume of the surface layer at the time of compression is ΔV1p, ΔV1 = (ΔV10−ΔV1p) / ΔV10 The compression deformation rate ΔV2 of the lower layer 5a-4 of the outermost layer 5a is as follows. Assuming that the volume at the time of compression is ΔV2p, ΔV2 = (ΔV20−ΔV2p) / ΔV20, and (ΔV10−ΔV1p) / ΔV10 <(ΔV
20−ΔV2p) / ΔV20.

In this embodiment, since the surface layer 5a-3 is formed thin, the heating roller 1
The toner transferred from the heating roller 1 in the nip area between the outermost layer 5a and the outermost layer 5a
-3, and can easily reach the lower layer 5a-4. Thus, in this example, the toner trapped in the lower layer 5a-4 has a structure that is difficult to be re-transferred to the heating roller 1 side, so that the toner transferred to the oil application roller 5 is transferred to the lower layer 5a-4. The toner can be solidified in the inside, and the occurrence of spot-like image stains due to the detachment of the once captured toner can be prevented.

[0043]

According to the present invention, as described above, the contaminated toner once transferred to the cleaning roller can be more reliably solidified in the deep layer of the cleaning roller, so that the heating roller can be cleaned for a long period of time. In addition, the occurrence of spot-like image stains can be extremely reduced.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a first example of a fixing device.

FIG. 2 is a schematic sectional view of an oil applying section in a second example of the fixing device.

FIG. 3 is a schematic sectional view of an oil applying roller in a third example of the fixing device.

FIG. 4 is a schematic sectional view of a main part of an oil application roller in a fifth example of the fixing device.

FIG. 5 is a schematic sectional view of a main part of a cleaning roller in the embodiment of the fixing device of the present invention.

FIG. 6 is a schematic sectional view of a main part of a cleaning roller in a ninth example of a fixing device.

FIG. 7 is a schematic sectional view of a main part of an oil application roller in a tenth example of a fixing device.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 heating roller 2 pressure roller 5 oil coating roller 5a outermost layer of oil coating roller 5a-1 oil supply layer of outermost layer of oil coating roller 5a-2 cleaning layer of outermost layer of oil coating roller 5a-3 Surface layer of outermost layer of oil application roller 5a-4 Lower layer of outermost layer of oil application roller 5b Middle layer of oil application roller 5c Hollow cylindrical member of oil application roller 5d Release agent 6 Cleaning roller 6a Outermost layer of oil application roller 6a-1 Surface layer of outermost layer of oil application roller 6a-2 Adjacent layer of outermost layer of oil application roller 6b Intermediate layer of oil application roller 6c Oil application roller 6d Mold release agent (cleaning agent) ρ1 Porosity of the outermost layer of the oil-applying roller r1 Average radius of the outermost layer of the oil-applying roller ρ2 Oil-applying roller The radius of the intermediate layer porosity r2 oil paint with the roller la of the intermediate layer

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 13/20 G03G 15/20

Claims (1)

(57) [Claims] To claim 1, wherein at least one of the heating roller and the pressure roller, the fixing device comprising contacting the cleaning roller, the cleaning roller, incorporates a release agent, external
A hollow cylindrical member having a release agent supply hole on its periphery, and the hollow cylinder
An intermediate layer that adheres to the outer periphery of the member and regulates the amount of release agent supplied
An adjacent layer having an air gap in close contact with the outer periphery of the intermediate layer;
In close contact with the outer periphery and communicated with the gap of the adjacent layer
The outermost layer having a thickness of 10 to 30 μm with voids,
The thickness of the outermost layer is smaller than the thickness of the adjacent layer, and the porosity of the adjacent layer is higher than the porosity of the outermost layer.